Faster UTF16 -> UTF8 and UTF8 -> UTF16 (#1552)

* Fix freezing test

* Add SIMDUTF

* More micro bench snippets

* Update .gitattributes

* Update .gitattributes

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>

14 files changed, 31329 insertions, 6 deletions

diff --git a/.gitattributes b/.gitattributes
index 7fc892361..082eec550 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -6,3 +6,5 @@ src/bun.js/bindings/sqlite/sqlite3.c linguist-vendored
 src/bun.js/bindings/sqlite/sqlite3_local.h linguist-vendored
 *.lockb binary diff=lockb
 *.zig text eol=lf
+src/bun.js/bindings/simdutf.cpp linguist-vendored
+src/bun.js/bindings/simdutf.h linguist-vendored
diff --git a/bench/snippets/arraybuffersink.mjs b/bench/snippets/arraybuffersink.mjs
new file mode 100644
index 000000000..0e787dd56
--- /dev/null
+++ b/bench/snippets/arraybuffersink.mjs
@@ -0,0 +1,30 @@
+import { ArrayBufferSink } from "bun";
+import { bench, run } from "mitata";
+
+var short = "Hello World!";
+var shortUTF16 = "Hello World 💕💕💕";
+var long = "Hello World!".repeat(1024);
+var longUTF16 = "Hello World 💕💕💕".repeat(1024);
+var encoder = new ArrayBufferSink({ stream: true, highWaterMark: 512 });
+
+bench(`${short.length} ascii`, () => {
+  encoder.write(short);
+  encoder.start();
+});
+
+bench(`${short.length} utf8`, () => {
+  encoder.write(shortUTF16);
+  encoder.start();
+});
+
+bench(`${long.length} ascii`, () => {
+  encoder.write(long);
+  encoder.start();
+});
+
+bench(`${longUTF16.length} utf8`, () => {
+  encoder.write(longUTF16);
+  encoder.start();
+});
+
+await run();
diff --git a/bench/snippets/read-file.mjs b/bench/snippets/read-file.mjs
new file mode 100644
index 000000000..3e42e6a73
--- /dev/null
+++ b/bench/snippets/read-file.mjs
@@ -0,0 +1,45 @@
+import { readFileSync, writeFileSync } from "node:fs";
+import { bench, run } from "mitata";
+
+var short = (function () {
+  const text = "Hello World!";
+  const path = "/tmp/bun-bench-short.text";
+  writeFileSync(path, text, "utf8");
+  return { path, length: text.length };
+})();
+var shortUTF16 = (function () {
+  const text = "Hello World 💕💕💕";
+  const path = "/tmp/bun-bench-shortUTF16.text";
+  writeFileSync(path, text, "utf8");
+  return { path, length: text.length };
+})();
+var long = (function () {
+  const text = "Hello World!".repeat(1024);
+  const path = "/tmp/bun-bench-long.text";
+  writeFileSync(path, text, "utf8");
+  return { path, length: text.length };
+})();
+var longUTF16 = (function () {
+  const text = "Hello World 💕💕💕".repeat(1024);
+  const path = "/tmp/bun-bench-longUTF16.text";
+  writeFileSync(path, text, "utf8");
+  return { path, length: text.length };
+})();
+
+bench(`${short.length} ascii`, () => {
+  readFileSync(short.path, "utf-8");
+});
+
+bench(`${short.length} utf8`, () => {
+  readFileSync(shortUTF16.path, "utf-8");
+});
+
+bench(`${long.length} ascii`, () => {
+  readFileSync(long.path, "utf-8");
+});
+
+bench(`${longUTF16.length} utf8`, () => {
+  readFileSync(longUTF16.path, "utf-8");
+});
+
+await run();
diff --git a/bench/snippets/text-decoder.mjs b/bench/snippets/text-decoder.mjs
new file mode 100644
index 000000000..b1d669f02
--- /dev/null
+++ b/bench/snippets/text-decoder.mjs
@@ -0,0 +1,49 @@
+import { bench, run } from "../node_modules/mitata/src/cli.mjs";
+
+var short = new TextEncoder().encode("Hello World!");
+var shortUTF16 = new TextEncoder().encode("Hello World 💕💕💕");
+var long = new TextEncoder().encode("Hello World!".repeat(1024));
+var longUTF16 = new TextEncoder().encode("Hello World 💕💕💕".repeat(1024));
+bench(`${short.length} ascii`, () => {
+  var decoder = new TextDecoder();
+  decoder.decode(short);
+});
+
+bench(`${short.length} utf8`, () => {
+  var decoder = new TextDecoder();
+  decoder.decode(shortUTF16);
+});
+
+bench(`${long.length} ascii`, () => {
+  var decoder = new TextDecoder();
+  decoder.decode(long);
+});
+
+bench(`${longUTF16.length} utf8`, () => {
+  var decoder = new TextDecoder();
+  decoder.decode(longUTF16);
+});
+
+if ("Buffer" in globalThis) {
+  const buffer_short = Buffer.from(short);
+  bench(`Buffer ${buffer_short.length} ascii`, () => {
+    buffer_short.toString("ascii");
+  });
+
+  const buffer_shortUTF16 = Buffer.from(short);
+  bench(`Buffer ${buffer_shortUTF16.length} utf8`, () => {
+    buffer_shortUTF16.toString("utf8");
+  });
+
+  const buffer_long = Buffer.from(long);
+  bench(`Buffer ${buffer_long.length} ascii`, () => {
+    buffer_long.toString("ascii");
+  });
+
+  const buffer_longUTF16 = Buffer.from(longUTF16);
+  bench(`Buffer ${buffer_longUTF16.length} utf8`, () => {
+    buffer_longUTF16.toString("utf8");
+  });
+}
+
+await run();
diff --git a/bench/snippets/text-encoder.mjs b/bench/snippets/text-encoder.mjs
new file mode 100644
index 000000000..cee84bf25
--- /dev/null
+++ b/bench/snippets/text-encoder.mjs
@@ -0,0 +1,33 @@
+import { bench, run } from "mitata";
+
+var short = "Hello World!";
+var shortUTF16 = "Hello World 💕💕💕";
+var long = "Hello World!".repeat(1024);
+var longUTF16 = "Hello World 💕💕💕".repeat(1024);
+var encoder = new TextEncoder();
+
+bench(`4 ascii`, () => {
+  encoder.encode("heyo");
+});
+
+bench(`4 utf8`, () => {
+  encoder.encode("💕💕");
+});
+
+bench(`${short.length} ascii`, () => {
+  encoder.encode(short);
+});
+
+bench(`${short.length} utf8`, () => {
+  encoder.encode(shortUTF16);
+});
+
+bench(`${long.length} ascii`, () => {
+  encoder.encode(long);
+});
+
+bench(`${longUTF16.length} utf8`, () => {
+  encoder.encode(longUTF16);
+});
+
+await run();
diff --git a/bench/snippets/write-file.mjs b/bench/snippets/write-file.mjs
new file mode 100644
index 000000000..b13104bfc
--- /dev/null
+++ b/bench/snippets/write-file.mjs
@@ -0,0 +1,25 @@
+import { readFileSync, writeFileSync } from "node:fs";
+import { bench, run } from "mitata";
+
+var short = "Hello World!";
+var shortUTF16 = "Hello World 💕💕💕";
+var long = "Hello World!".repeat(1024);
+var longUTF16 = "Hello World 💕💕💕".repeat(1024);
+
+bench(`${short.length} ascii`, () => {
+  writeFileSync("/tmp/bun.bench-out.txt", short);
+});
+
+bench(`${short.length} utf8`, () => {
+  writeFileSync("/tmp/bun.bench-out.txt", shortUTF16);
+});
+
+bench(`${long.length} ascii`, () => {
+  writeFileSync("/tmp/bun.bench-out.txt", long);
+});
+
+bench(`${longUTF16.length} utf8`, () => {
+  writeFileSync("/tmp/bun.bench-out.txt", longUTF16);
+});
+
+await run();
diff --git a/src/bun.js/bindings/bun-simdutf.cpp b/src/bun.js/bindings/bun-simdutf.cpp
new file mode 100644
index 000000000..d02ff9854
--- /dev/null
+++ b/src/bun.js/bindings/bun-simdutf.cpp
@@ -0,0 +1,327 @@
+#include "simdutf.h"
+
+typedef struct SIMDUTFResult {
+    int error;
+    size_t count;
+} SIMDUTFResult;
+
+extern "C" {
+
+int simdutf__detect_encodings(const char* input, size_t length)
+{
+    return simdutf::detect_encodings(input, length);
+}
+
+bool simdutf__validate_utf8(const char* buf, size_t len)
+{
+    return simdutf::validate_utf8(buf, len);
+}
+
+SIMDUTFResult simdutf__validate_utf8_with_errors(const char* buf, size_t len)
+{
+    auto res = simdutf::validate_utf8_with_errors(buf, len);
+    return { res.error, res.count };
+}
+
+bool simdutf__validate_ascii(const char* buf, size_t len)
+{
+    return simdutf::validate_ascii(buf, len);
+}
+
+SIMDUTFResult simdutf__validate_ascii_with_errors(const char* buf, size_t len)
+{
+    auto res = simdutf::validate_ascii_with_errors(buf, len);
+    return { res.error, res.count };
+}
+
+bool simdutf__validate_utf16le(const char16_t* buf, size_t len)
+{
+    return simdutf::validate_utf16le(buf, len);
+}
+
+bool simdutf__validate_utf16be(const char16_t* buf, size_t len)
+{
+    return simdutf::validate_utf16be(buf, len);
+}
+
+SIMDUTFResult simdutf__validate_utf16le_with_errors(const char16_t* buf,
+    size_t len)
+{
+    auto res = simdutf::validate_utf16le_with_errors(buf, len);
+    return { res.error, res.count };
+}
+
+SIMDUTFResult simdutf__validate_utf16be_with_errors(const char16_t* buf,
+    size_t len)
+{
+    auto res = simdutf::validate_utf16be_with_errors(buf, len);
+    return { res.error, res.count };
+}
+
+bool simdutf__validate_utf32(const char32_t* buf, size_t len)
+{
+    return simdutf::validate_utf32(buf, len);
+}
+
+SIMDUTFResult simdutf__validate_utf32_with_errors(const char32_t* buf,
+    size_t len)
+{
+    auto res = simdutf::validate_utf32_with_errors(buf, len);
+    return { res.error, res.count };
+}
+
+size_t simdutf__convert_utf8_to_utf16le(const char* buf, size_t len,
+    char16_t* utf16_output)
+{
+    return simdutf::convert_utf8_to_utf16le(buf, len, utf16_output);
+}
+
+size_t simdutf__convert_utf8_to_utf16be(const char* buf, size_t len,
+    char16_t* utf16_output)
+{
+    return simdutf::convert_utf8_to_utf16be(buf, len, utf16_output);
+}
+SIMDUTFResult
+simdutf__convert_utf8_to_utf16le_with_errors(const char* buf, size_t len,
+    char16_t* utf16_output)
+{
+    auto res = simdutf::convert_utf8_to_utf16le_with_errors(buf, len, utf16_output);
+    return { res.error, res.count };
+}
+
+SIMDUTFResult
+simdutf__convert_utf8_to_utf16be_with_errors(const char* buf, size_t len,
+    char16_t* utf16_output)
+{
+    auto res = simdutf::convert_utf8_to_utf16be_with_errors(buf, len, utf16_output);
+    return { res.error, res.count };
+}
+size_t simdutf__convert_valid_utf8_to_utf16le(const char* buf, size_t len,
+    char16_t* utf16_buffer)
+{
+    return simdutf::convert_valid_utf8_to_utf16le(buf, len, utf16_buffer);
+}
+
+size_t simdutf__convert_valid_utf8_to_utf16be(const char* buf, size_t len,
+    char16_t* utf16_buffer)
+{
+    return simdutf::convert_valid_utf8_to_utf16be(buf, len, utf16_buffer);
+}
+
+size_t simdutf__convert_utf8_to_utf32(const char* buf, size_t len,
+    char32_t* utf32_output)
+{
+    return simdutf::convert_utf8_to_utf32(buf, len, utf32_output);
+}
+SIMDUTFResult
+simdutf__convert_utf8_to_utf32_with_errors(const char* buf, size_t len,
+    char32_t* utf32_output)
+{
+    auto res = simdutf::convert_utf8_to_utf32_with_errors(buf, len, utf32_output);
+    return { res.error, res.count };
+}
+
+size_t simdutf__convert_valid_utf8_to_utf32(const char* buf, size_t len,
+    char32_t* utf32_buffer)
+{
+    return simdutf::convert_valid_utf8_to_utf32(buf, len, utf32_buffer);
+}
+
+size_t simdutf__convert_utf16le_to_utf8(const char16_t* buf, size_t len,
+    char* utf8_buffer)
+{
+    return simdutf::convert_utf16le_to_utf8(buf, len, utf8_buffer);
+}
+
+size_t simdutf__convert_utf16be_to_utf8(const char16_t* buf, size_t len,
+    char* utf8_buffer)
+{
+    return simdutf::convert_utf16be_to_utf8(buf, len, utf8_buffer);
+}
+SIMDUTFResult simdutf__convert_utf16le_to_utf8_with_errors(const char16_t* buf,
+    size_t len,
+    char* utf8_buffer)
+{
+    auto res = simdutf::convert_utf16le_to_utf8_with_errors(buf, len, utf8_buffer);
+    return { res.error, res.count };
+}
+
+SIMDUTFResult simdutf__convert_utf16be_to_utf8_with_errors(const char16_t* buf,
+    size_t len,
+    char* utf8_buffer)
+{
+    auto res = simdutf::convert_utf16be_to_utf8_with_errors(buf, len, utf8_buffer);
+    return { res.error, res.count };
+}
+
+size_t simdutf__convert_valid_utf16le_to_utf8(const char16_t* buf, size_t len,
+    char* utf8_buffer)
+{
+    return simdutf::convert_valid_utf16le_to_utf8(buf, len, utf8_buffer);
+}
+
+size_t simdutf__convert_valid_utf16be_to_utf8(const char16_t* buf, size_t len,
+    char* utf8_buffer)
+{
+    return simdutf::convert_valid_utf16be_to_utf8(buf, len, utf8_buffer);
+}
+
+size_t simdutf__convert_utf32_to_utf8(const char32_t* buf, size_t len,
+    char* utf8_buffer)
+{
+    return simdutf::convert_utf32_to_utf8(buf, len, utf8_buffer);
+}
+
+SIMDUTFResult simdutf__convert_utf32_to_utf8_with_errors(const char32_t* buf,
+    size_t len,
+    char* utf8_buffer)
+{
+    auto res = simdutf::convert_utf32_to_utf8_with_errors(buf, len, utf8_buffer);
+    return { res.error, res.count };
+}
+
+size_t simdutf__convert_valid_utf32_to_utf8(const char32_t* buf, size_t len,
+    char* utf8_buffer)
+{
+    return simdutf::convert_valid_utf32_to_utf8(buf, len, utf8_buffer);
+}
+
+size_t simdutf__convert_utf32_to_utf16le(const char32_t* buf, size_t len,
+    char16_t* utf16_buffer)
+{
+    return simdutf::convert_utf32_to_utf16le(buf, len, utf16_buffer);
+}
+
+size_t simdutf__convert_utf32_to_utf16be(const char32_t* buf, size_t len,
+    char16_t* utf16_buffer)
+{
+    return simdutf::convert_utf32_to_utf16be(buf, len, utf16_buffer);
+}
+
+SIMDUTFResult
+simdutf__convert_utf32_to_utf16le_with_errors(const char32_t* buf, size_t len,
+    char16_t* utf16_buffer)
+{
+    auto res = simdutf::convert_utf32_to_utf16le_with_errors(buf, len, utf16_buffer);
+    return { res.error, res.count };
+}
+
+SIMDUTFResult
+simdutf__convert_utf32_to_utf16be_with_errors(const char32_t* buf, size_t len,
+    char16_t* utf16_buffer)
+{
+    auto res = simdutf::convert_utf32_to_utf16be_with_errors(buf, len, utf16_buffer);
+    return { res.error, res.count };
+}
+
+size_t simdutf__convert_valid_utf32_to_utf16le(const char32_t* buf, size_t len,
+    char16_t* utf16_buffer)
+{
+    return simdutf::convert_valid_utf32_to_utf16le(buf, len, utf16_buffer);
+}
+
+size_t simdutf__convert_valid_utf32_to_utf16be(const char32_t* buf, size_t len,
+    char16_t* utf16_buffer)
+{
+    return simdutf::convert_valid_utf32_to_utf16be(buf, len, utf16_buffer);
+}
+
+size_t simdutf__convert_utf16le_to_utf32(const char16_t* buf, size_t len,
+    char32_t* utf32_buffer)
+{
+    return simdutf::convert_utf16le_to_utf32(buf, len, utf32_buffer);
+}
+
+size_t simdutf__convert_utf16be_to_utf32(const char16_t* buf, size_t len,
+    char32_t* utf32_buffer)
+{
+    return simdutf::convert_utf16be_to_utf32(buf, len, utf32_buffer);
+}
+
+SIMDUTFResult
+simdutf__convert_utf16le_to_utf32_with_errors(const char16_t* buf, size_t len,
+    char32_t* utf32_buffer)
+{
+    auto res = simdutf::convert_utf16le_to_utf32_with_errors(buf, len, utf32_buffer);
+    return { res.error, res.count };
+}
+
+SIMDUTFResult
+simdutf__convert_utf16be_to_utf32_with_errors(const char16_t* buf, size_t len,
+    char32_t* utf32_buffer)
+{
+    auto res = simdutf::convert_utf16be_to_utf32_with_errors(buf, len, utf32_buffer);
+    return { res.error, res.count };
+}
+
+size_t simdutf__convert_valid_utf16le_to_utf32(const char16_t* buf, size_t len,
+    char32_t* utf32_buffer)
+{
+    return simdutf::convert_valid_utf16le_to_utf32(buf, len, utf32_buffer);
+}
+size_t simdutf__convert_valid_utf16be_to_utf32(const char16_t* buf, size_t len,
+    char32_t* utf32_buffer)
+{
+    return simdutf::convert_valid_utf16be_to_utf32(buf, len, utf32_buffer);
+}
+void simdutf__change_endianness_utf16(const char16_t* buf, size_t length,
+    char16_t* output)
+{
+    simdutf::change_endianness_utf16(buf, length, output);
+}
+
+size_t simdutf__count_utf16le(const char16_t* buf, size_t length)
+{
+    return simdutf::count_utf16le(buf, length);
+}
+
+size_t simdutf__count_utf16be(const char16_t* buf, size_t length)
+{
+    return simdutf::count_utf16be(buf, length);
+}
+
+size_t simdutf__count_utf8(const char* buf, size_t length)
+{
+    return simdutf::count_utf8(buf, length);
+}
+
+size_t simdutf__utf8_length_from_utf16le(const char16_t* input, size_t length)
+{
+    return simdutf::utf8_length_from_utf16le(input, length);
+}
+
+size_t simdutf__utf8_length_from_utf16be(const char16_t* input, size_t length)
+{
+    return simdutf::utf8_length_from_utf16be(input, length);
+}
+
+size_t simdutf__utf32_length_from_utf16le(const char16_t* input, size_t length)
+{
+    return simdutf::utf32_length_from_utf16le(input, length);
+}
+
+size_t simdutf__utf32_length_from_utf16be(const char16_t* input, size_t length)
+{
+    return simdutf::utf32_length_from_utf16be(input, length);
+}
+
+size_t simdutf__utf16_length_from_utf8(const char* input, size_t length)
+{
+    return simdutf::utf16_length_from_utf8(input, length);
+}
+
+size_t simdutf__utf8_length_from_utf32(const char32_t* input, size_t length)
+{
+    return simdutf::utf8_length_from_utf32(input, length);
+}
+
+size_t simdutf__utf16_length_from_utf32(const char32_t* input, size_t length)
+{
+    return simdutf::utf16_length_from_utf32(input, length);
+}
+
+size_t simdutf__utf32_length_from_utf8(const char* input, size_t length)
+{
+    return simdutf::utf32_length_from_utf8(input, length);
+}
+}
\ No newline at end of file
diff --git a/src/bun.js/bindings/bun-simdutf.zig b/src/bun.js/bindings/bun-simdutf.zig
new file mode 100644
index 000000000..f84ce56ce
--- /dev/null
+++ b/src/bun.js/bindings/bun-simdutf.zig
@@ -0,0 +1,346 @@
+pub const SIMDUTFResult = extern struct {
+    status: Status,
+    count: usize = 0,
+
+    pub const Status = enum(i32) {
+        success = 0,
+        /// Any byte must have fewer than 5 header bits.
+        header_bits = 1,
+
+        /// The leading byte must be followed by N-1 continuation bytes, where N is the UTF-8 character length
+        /// This is also the error when the input is truncated.
+        too_short = 2,
+
+        /// The leading byte must not be a continuation byte.
+        too_long = 3,
+
+        /// The decoded character must be above U+7F for two-byte characters, U+7FF for three-byte characters,
+        overlong = 4,
+
+        /// and U+FFFF for four-byte characters.
+        /// The decoded character must be less than or equal to U+10FFFF OR less than or equal than U+7F for ASCII.
+        /// The decoded character must be not be in U+D800...DFFF (UTF-8 or UTF-32) OR
+        /// a high surrogate must be followed by a low surrogate and a low surrogate must be preceded by a high surrogate (UTF-16)
+        too_large = 5,
+        surrogate = 6,
+        /// Not related to validation/transcoding.
+        _,
+    };
+};
+pub extern fn simdutf__detect_encodings(input: [*]const u8, length: usize) c_int;
+pub extern fn simdutf__validate_utf8(buf: [*]const u8, len: usize) bool;
+pub extern fn simdutf__validate_utf8_with_errors(buf: [*]const u8, len: usize) SIMDUTFResult;
+pub extern fn simdutf__validate_ascii(buf: [*]const u8, len: usize) bool;
+pub extern fn simdutf__validate_ascii_with_errors(buf: [*]const u8, len: usize) SIMDUTFResult;
+pub extern fn simdutf__validate_utf16le(buf: [*]const u16, len: usize) bool;
+pub extern fn simdutf__validate_utf16be(buf: [*]const u16, len: usize) bool;
+pub extern fn simdutf__validate_utf16le_with_errors(buf: [*]const u16, len: usize) SIMDUTFResult;
+pub extern fn simdutf__validate_utf16be_with_errors(buf: [*]const u16, len: usize) SIMDUTFResult;
+pub extern fn simdutf__validate_utf32(buf: [*c]const c_uint, len: usize) bool;
+pub extern fn simdutf__validate_utf32_with_errors(buf: [*c]const c_uint, len: usize) SIMDUTFResult;
+pub extern fn simdutf__convert_utf8_to_utf16le(buf: [*]const u8, len: usize, utf16_output: [*]u16) usize;
+pub extern fn simdutf__convert_utf8_to_utf16be(buf: [*]const u8, len: usize, utf16_output: [*]u16) usize;
+pub extern fn simdutf__convert_utf8_to_utf16le_with_errors(buf: [*]const u8, len: usize, utf16_output: [*]u16) SIMDUTFResult;
+pub extern fn simdutf__convert_utf8_to_utf16be_with_errors(buf: [*]const u8, len: usize, utf16_output: [*]u16) SIMDUTFResult;
+pub extern fn simdutf__convert_valid_utf8_to_utf16be(buf: [*]const u8, len: usize, utf16_buffer: [*]u16) usize;
+pub extern fn simdutf__convert_utf8_to_utf32(buf: [*]const u8, len: usize, utf32_output: [*]u32) usize;
+pub extern fn simdutf__convert_utf8_to_utf32_with_errors(buf: [*]const u8, len: usize, utf32_output: [*]u32) SIMDUTFResult;
+pub extern fn simdutf__convert_valid_utf8_to_utf32(buf: [*]const u8, len: usize, utf32_buffer: [*]u32) usize;
+pub extern fn simdutf__convert_utf16le_to_utf8(buf: [*]const u16, len: usize, utf8_buffer: [*]u8) usize;
+pub extern fn simdutf__convert_utf16be_to_utf8(buf: [*]const u16, len: usize, utf8_buffer: [*]u8) usize;
+pub extern fn simdutf__convert_utf16le_to_utf8_with_errors(buf: [*]const u16, len: usize, utf8_buffer: [*]u8) SIMDUTFResult;
+pub extern fn simdutf__convert_utf16be_to_utf8_with_errors(buf: [*]const u16, len: usize, utf8_buffer: [*]u8) SIMDUTFResult;
+pub extern fn simdutf__convert_valid_utf16le_to_utf8(buf: [*]const u16, len: usize, utf8_buffer: [*]u8) usize;
+pub extern fn simdutf__convert_valid_utf16be_to_utf8(buf: [*]const u16, len: usize, utf8_buffer: [*]u8) usize;
+pub extern fn simdutf__convert_utf32_to_utf8(buf: [*c]const c_uint, len: usize, utf8_buffer: [*]u8) usize;
+pub extern fn simdutf__convert_utf32_to_utf8_with_errors(buf: [*c]const c_uint, len: usize, utf8_buffer: [*]u8) SIMDUTFResult;
+pub extern fn simdutf__convert_valid_utf32_to_utf8(buf: [*c]const c_uint, len: usize, utf8_buffer: [*]u8) usize;
+pub extern fn simdutf__convert_utf32_to_utf16le(buf: [*c]const c_uint, len: usize, utf16_buffer: [*]u16) usize;
+pub extern fn simdutf__convert_utf32_to_utf16be(buf: [*c]const c_uint, len: usize, utf16_buffer: [*]u16) usize;
+pub extern fn simdutf__convert_utf32_to_utf16le_with_errors(buf: [*c]const c_uint, len: usize, utf16_buffer: [*]u16) SIMDUTFResult;
+pub extern fn simdutf__convert_utf32_to_utf16be_with_errors(buf: [*c]const c_uint, len: usize, utf16_buffer: [*]u16) SIMDUTFResult;
+pub extern fn simdutf__convert_valid_utf32_to_utf16le(buf: [*c]const c_uint, len: usize, utf16_buffer: [*]u16) usize;
+pub extern fn simdutf__convert_valid_utf32_to_utf16be(buf: [*c]const c_uint, len: usize, utf16_buffer: [*]u16) usize;
+pub extern fn simdutf__convert_utf16le_to_utf32(buf: [*]const u16, len: usize, utf32_buffer: [*]u32) usize;
+pub extern fn simdutf__convert_utf16be_to_utf32(buf: [*]const u16, len: usize, utf32_buffer: [*]u32) usize;
+pub extern fn simdutf__convert_utf16le_to_utf32_with_errors(buf: [*]const u16, len: usize, utf32_buffer: [*]u32) SIMDUTFResult;
+pub extern fn simdutf__convert_utf16be_to_utf32_with_errors(buf: [*]const u16, len: usize, utf32_buffer: [*]u32) SIMDUTFResult;
+pub extern fn simdutf__convert_valid_utf16le_to_utf32(buf: [*]const u16, len: usize, utf32_buffer: [*]u32) usize;
+pub extern fn simdutf__convert_valid_utf16be_to_utf32(buf: [*]const u16, len: usize, utf32_buffer: [*]u32) usize;
+pub extern fn simdutf__change_endianness_utf16(buf: [*]const u16, length: usize, output: [*]u16) void;
+pub extern fn simdutf__count_utf16le(buf: [*]const u16, length: usize) usize;
+pub extern fn simdutf__count_utf16be(buf: [*]const u16, length: usize) usize;
+pub extern fn simdutf__count_utf8(buf: [*]const u8, length: usize) usize;
+pub extern fn simdutf__utf8_length_from_utf16le(input: [*]const u16, length: usize) usize;
+pub extern fn simdutf__utf8_length_from_utf16be(input: [*]const u16, length: usize) usize;
+pub extern fn simdutf__utf32_length_from_utf16le(input: [*]const u16, length: usize) usize;
+pub extern fn simdutf__utf32_length_from_utf16be(input: [*]const u16, length: usize) usize;
+pub extern fn simdutf__utf16_length_from_utf8(input: [*]const u8, length: usize) usize;
+pub extern fn simdutf__utf8_length_from_utf32(input: [*c]const c_uint, length: usize) usize;
+pub extern fn simdutf__utf16_length_from_utf32(input: [*c]const c_uint, length: usize) usize;
+pub extern fn simdutf__utf32_length_from_utf8(input: [*]const u8, length: usize) usize;
+
+pub const validate = struct {
+    pub const with_errors = struct {
+        pub fn utf8(input: []const u8) SIMDUTFResult {
+            return simdutf__validate_utf8_with_errors(input.ptr, input.len);
+        }
+        pub fn ascii(input: []const u8) SIMDUTFResult {
+            return simdutf__validate_ascii_with_errors(input.ptr, input.len);
+        }
+        pub fn utf16le(input: []const u16) SIMDUTFResult {
+            return simdutf__validate_utf16le_with_errors(input.ptr, input.len);
+        }
+        pub fn utf16be(input: []const u16) SIMDUTFResult {
+            return simdutf__validate_utf16be_with_errors(input.ptr, input.len);
+        }
+    };
+
+    pub fn utf8(input: []const u8) bool {
+        return simdutf__validate_utf8(input.ptr, input.len);
+    }
+    pub fn ascii(input: []const u8) bool {
+        return simdutf__validate_ascii(input.ptr, input.len);
+    }
+    pub fn utf16le(input: []const u16) bool {
+        return simdutf__validate_utf16le(input.ptr, input.len);
+    }
+    pub fn utf16be(input: []const u16) bool {
+        return simdutf__validate_utf16be(input.ptr, input.len);
+    }
+};
+
+pub const convert = struct {
+    pub const utf8 = struct {
+        pub const to = struct {
+            pub const utf16 = struct {
+                pub const with_errors = struct {
+                    pub fn le(input: []const u8, output: []u16) SIMDUTFResult {
+                        return simdutf__convert_utf8_to_utf16le_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                    pub fn be(input: []const u8, output: []u16) SIMDUTFResult {
+                        return simdutf__convert_utf8_to_utf16be_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                };
+
+                pub fn le(input: []const u8, output: []u16) usize {
+                    return simdutf__convert_utf8_to_utf16le(input.ptr, input.len, output.ptr);
+                }
+                pub fn be(input: []const u8, output: []u16) usize {
+                    return simdutf__convert_utf8_to_utf16be(input.ptr, input.len, output.ptr);
+                }
+            };
+
+            pub const utf32 = struct {
+                pub const with_errors = struct {
+                    pub fn le(input: []const u8, output: []u32) SIMDUTFResult {
+                        return simdutf__convert_utf8_to_utf32_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                    pub fn be(input: []const u8, output: []u32) SIMDUTFResult {
+                        return simdutf__convert_utf8_to_utf32_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                };
+
+                pub fn le(input: []const u8, output: []u32) usize {
+                    return simdutf__convert_valid_utf8_to_utf32(input.ptr, input.len, output.ptr);
+                }
+                pub fn be(input: []const u8, output: []u32) usize {
+                    return simdutf__convert_valid_utf8_to_utf32(input.ptr, input.len, output.ptr);
+                }
+            };
+        };
+    };
+
+    pub const utf16 = struct {
+        pub const to = struct {
+            pub const utf8 = struct {
+                pub const with_errors = struct {
+                    pub fn le(input: []const u16, output: []u8) SIMDUTFResult {
+                        return simdutf__convert_utf16le_to_utf8_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                    pub fn be(input: []const u16, output: []u8) SIMDUTFResult {
+                        return simdutf__convert_utf16be_to_utf8_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                };
+
+                pub fn le(input: []const u16, output: []u8) usize {
+                    return simdutf__convert_valid_utf16le_to_utf8(input.ptr, input.len, output.ptr);
+                }
+                pub fn be(input: []const u16, output: []u8) usize {
+                    return simdutf__convert_valid_utf16be_to_utf8(input.ptr, input.len, output.ptr);
+                }
+            };
+
+            pub const utf32 = struct {
+                pub const with_errors = struct {
+                    pub fn le(input: []const u16, output: []u32) SIMDUTFResult {
+                        return simdutf__convert_utf16le_to_utf32_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                    pub fn be(input: []const u16, output: []u32) SIMDUTFResult {
+                        return simdutf__convert_utf16be_to_utf32_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                };
+
+                pub fn le(input: []const u16, output: []u32) usize {
+                    return simdutf__convert_valid_utf16le_to_utf32(input.ptr, input.len, output.ptr);
+                }
+                pub fn be(input: []const u16, output: []u32) usize {
+                    return simdutf__convert_valid_utf16be_to_utf32(input.ptr, input.len, output.ptr);
+                }
+            };
+        };
+    };
+
+    pub const utf32 = struct {
+        pub const to = struct {
+            pub const utf8 = struct {
+                pub const with_errors = struct {
+                    pub fn le(input: []const u32, output: []u8) SIMDUTFResult {
+                        return simdutf__convert_utf32_to_utf8_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                    pub fn be(input: []const u32, output: []u8) SIMDUTFResult {
+                        return simdutf__convert_utf32_to_utf8_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                };
+
+                pub fn le(input: []const u32, output: []u8) usize {
+                    return simdutf__convert_valid_utf32_to_utf8(input.ptr, input.len, output.ptr);
+                }
+                pub fn be(input: []const u32, output: []u8) usize {
+                    return simdutf__convert_valid_utf32_to_utf8(input.ptr, input.len, output.ptr);
+                }
+            };
+
+            pub const utf16 = struct {
+                pub const with_errors = struct {
+                    pub fn le(input: []const u32, output: []u16) SIMDUTFResult {
+                        return simdutf__convert_utf32_to_utf16le_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                    pub fn be(input: []const u32, output: []u16) SIMDUTFResult {
+                        return simdutf__convert_utf32_to_utf16be_with_errors(input.ptr, input.len, output.ptr);
+                    }
+                };
+
+                pub fn le(input: []const u32, output: []u16) usize {
+                    return simdutf__convert_valid_utf32_to_utf16le(input.ptr, input.len, output.ptr);
+                }
+                pub fn be(input: []const u32, output: []u16) usize {
+                    return simdutf__convert_valid_utf32_to_utf16be(input.ptr, input.len, output.ptr);
+                }
+            };
+        };
+    };
+};
+
+pub const length = struct {
+    pub const utf8 = struct {
+        pub const from = struct {
+            pub const utf16 = struct {
+                pub fn le(input: []const u16) usize {
+                    return simdutf__utf8_length_from_utf16le(input.ptr, input.len);
+                }
+                pub fn be(input: []const u16) usize {
+                    return simdutf__utf8_length_from_utf16be(input.ptr, input.len);
+                }
+            };
+
+            pub fn utf32(input: []const u32) usize {
+                return simdutf__utf8_length_from_utf32(input.ptr, input.len);
+            }
+        };
+    };
+
+    pub const utf16 = struct {
+        pub const from = struct {
+            pub const utf8 = struct {
+                pub fn le(input: []const u8) usize {
+                    return simdutf__utf16_length_from_utf8(input.ptr, input.len);
+                }
+                pub fn be(input: []const u8) usize {
+                    return simdutf__utf16_length_from_utf8(input.ptr, input.len);
+                }
+            };
+
+            pub fn utf32(input: []const u32) usize {
+                return simdutf__utf16_length_from_utf32(input.ptr, input.len);
+            }
+        };
+    };
+
+    pub const utf32 = struct {
+        pub const from = struct {
+            pub const utf8 = struct {
+                pub fn le(input: []const u8) usize {
+                    return simdutf__utf32_length_from_utf8(input.ptr, input.len);
+                }
+                pub fn be(input: []const u8) usize {
+                    return simdutf__utf32_length_from_utf8(input.ptr, input.len);
+                }
+            };
+
+            pub const utf16 = struct {
+                pub fn le(input: []const u16) usize {
+                    return simdutf__utf32_length_from_utf16le(input.ptr, input.len);
+                }
+                pub fn be(input: []const u16) usize {
+                    return simdutf__utf32_length_from_utf16be(input.ptr, input.len);
+                }
+            };
+        };
+    };
+};
+
+pub const trim = struct {
+    pub fn utf8_len(buf: []const u8) usize {
+        if (buf.len < 3) {
+            switch (buf.len) {
+                2 => {
+                    if (buf[buf.len - 1] >= 0b11000000) {
+                        return buf.len - 1;
+                    } // 2-, 3- and 4-byte characters with only 1 byte left
+                    if (buf[buf.len - 2] >= 0b11100000) {
+                        return buf.len - 2;
+                    } // 3- and 4-byte characters with only 2 bytes left
+                    return buf.len;
+                },
+                1 => {
+                    if (buf[buf.len - 1] >= 0b11000000) {
+                        return buf.len - 1;
+                    } // 2-, 3- and 4-byte characters with only 1 byte left
+                    return buf.len;
+                },
+                0 => return buf.len,
+                else => unreachable,
+            }
+        }
+
+        if (buf[buf.len - 1] >= 0b11000000) {
+            return buf.len - 1;
+        } // 2-, 3- and 4-byte characters with only 1 byte left
+        if (buf[buf.len - 2] >= 0b11100000) {
+            return buf.len - 2;
+        } // 3- and 4-byte characters with only 1 byte left
+        if (buf[buf.len - 3] >= 0b11110000) {
+            return buf.len - 3;
+        } // 4-byte characters with only 3 bytes left
+        return buf.len;
+    }
+
+    pub fn utf16_len(buf: []const u16) usize {
+        if (buf.len == 0) {
+            return 0;
+        }
+        if ((buf[buf.len - 1] >= 0xD800) and (buf[buf.len - 1] <= 0xDBFF)) {
+            return buf.len - 1;
+        }
+        return buf.len;
+    }
+
+    pub fn utf16(buf: []const u16) []const u16 {
+        return buf[0..utf16_len(buf)];
+    }
+
+    pub fn utf8(buf: []const u8) []const u8 {
+        return buf[0..utf8_len(buf)];
+    }
+};
diff --git a/src/bun.js/bindings/simdutf.cpp b/src/bun.js/bindings/simdutf.cpp
new file mode 100644
index 000000000..0c0c4b542
--- /dev/null
+++ b/src/bun.js/bindings/simdutf.cpp
@@ -0,0 +1,27955 @@
+/* auto-generated on 2022-11-22 11:39:54 -0500. Do not edit! */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf.cpp
+/* begin file src/simdutf.cpp */
+#include "simdutf.h"
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=implementation.cpp
+/* begin file src/implementation.cpp */
+#include <initializer_list>
+#include <climits>
+
+// Useful for debugging purposes
+namespace simdutf {
+namespace {
+
+template <typename T>
+std::string toBinaryString(T b) {
+   std::string binary = "";
+   T mask = T(1) << (sizeof(T) * CHAR_BIT - 1);
+   while (mask > 0) {
+    binary += ((b & mask) == 0) ? '0' : '1';
+    mask >>= 1;
+  }
+  return binary;
+}
+}
+}
+
+// Implementations
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64.h
+/* begin file src/simdutf/arm64.h */
+#ifndef SIMDUTF_ARM64_H
+#define SIMDUTF_ARM64_H
+
+#ifdef SIMDUTF_FALLBACK_H
+#error "arm64.h must be included before fallback.h"
+#endif
+
+
+#ifndef SIMDUTF_IMPLEMENTATION_ARM64
+#define SIMDUTF_IMPLEMENTATION_ARM64 (SIMDUTF_IS_ARM64)
+#endif
+#define SIMDUTF_CAN_ALWAYS_RUN_ARM64 SIMDUTF_IMPLEMENTATION_ARM64 && SIMDUTF_IS_ARM64
+
+
+
+#if SIMDUTF_IMPLEMENTATION_ARM64
+
+namespace simdutf {
+/**
+ * Implementation for NEON (ARMv8).
+ */
+namespace arm64 {
+} // namespace arm64
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/implementation.h
+/* begin file src/simdutf/arm64/implementation.h */
+#ifndef SIMDUTF_ARM64_IMPLEMENTATION_H
+#define SIMDUTF_ARM64_IMPLEMENTATION_H
+
+
+namespace simdutf {
+namespace arm64 {
+
+namespace {
+using namespace simdutf;
+}
+
+class implementation final : public simdutf::implementation {
+public:
+  simdutf_really_inline implementation() : simdutf::implementation("arm64", "ARM NEON", internal::instruction_set::NEON) {}
+  simdutf_warn_unused int detect_encodings(const char * input, size_t length) const noexcept final;
+  simdutf_warn_unused bool validate_utf8(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf8_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_ascii(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_ascii_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16le(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16be(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf32(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  void change_endianness_utf16(const char16_t * buf, size_t length, char16_t * output) const noexcept final;
+  simdutf_warn_unused size_t count_utf16le(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf16be(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf8(const char * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf8(const char * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf8(const char * input, size_t length) const noexcept;
+};
+
+} // namespace arm64
+} // namespace simdutf
+
+#endif // SIMDUTF_ARM64_IMPLEMENTATION_H
+/* end file src/simdutf/arm64/implementation.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/begin.h
+/* begin file src/simdutf/arm64/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "arm64"
+// #define SIMDUTF_IMPLEMENTATION arm64
+/* end file src/simdutf/arm64/begin.h */
+
+// Declarations
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/intrinsics.h
+/* begin file src/simdutf/arm64/intrinsics.h */
+#ifndef SIMDUTF_ARM64_INTRINSICS_H
+#define SIMDUTF_ARM64_INTRINSICS_H
+
+
+// This should be the correct header whether
+// you use visual studio or other compilers.
+#include <arm_neon.h>
+
+#endif //  SIMDUTF_ARM64_INTRINSICS_H
+/* end file src/simdutf/arm64/intrinsics.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/bitmanipulation.h
+/* begin file src/simdutf/arm64/bitmanipulation.h */
+#ifndef SIMDUTF_ARM64_BITMANIPULATION_H
+#define SIMDUTF_ARM64_BITMANIPULATION_H
+
+namespace simdutf {
+namespace arm64 {
+namespace {
+
+/* result might be undefined when input_num is zero */
+simdutf_really_inline int count_ones(uint64_t input_num) {
+   return vaddv_u8(vcnt_u8(vcreate_u8(input_num)));
+}
+
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+
+#endif // SIMDUTF_ARM64_BITMANIPULATION_H
+/* end file src/simdutf/arm64/bitmanipulation.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/simd.h
+/* begin file src/simdutf/arm64/simd.h */
+#ifndef SIMDUTF_ARM64_SIMD_H
+#define SIMDUTF_ARM64_SIMD_H
+
+#include <type_traits>
+
+
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace simd {
+
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+namespace {
+// Start of private section with Visual Studio workaround
+
+
+/**
+ * make_uint8x16_t initializes a SIMD register (uint8x16_t).
+ * This is needed because, incredibly, the syntax uint8x16_t x = {1,2,3...}
+ * is not recognized under Visual Studio! This is a workaround.
+ * Using a std::initializer_list<uint8_t>  as a parameter resulted in
+ * inefficient code. With the current approach, if the parameters are
+ * compile-time constants,
+ * GNU GCC compiles it to ldr, the same as uint8x16_t x = {1,2,3...}.
+ * You should not use this function except for compile-time constants:
+ * it is not efficient.
+ */
+simdutf_really_inline uint8x16_t make_uint8x16_t(uint8_t x1,  uint8_t x2,  uint8_t x3,  uint8_t x4,
+                                         uint8_t x5,  uint8_t x6,  uint8_t x7,  uint8_t x8,
+                                         uint8_t x9,  uint8_t x10, uint8_t x11, uint8_t x12,
+                                         uint8_t x13, uint8_t x14, uint8_t x15, uint8_t x16) {
+  // Doing a load like so end ups generating worse code.
+  // uint8_t array[16] = {x1, x2, x3, x4, x5, x6, x7, x8,
+  //                     x9, x10,x11,x12,x13,x14,x15,x16};
+  // return vld1q_u8(array);
+  uint8x16_t x{};
+  // incredibly, Visual Studio does not allow x[0] = x1
+  x = vsetq_lane_u8(x1, x, 0);
+  x = vsetq_lane_u8(x2, x, 1);
+  x = vsetq_lane_u8(x3, x, 2);
+  x = vsetq_lane_u8(x4, x, 3);
+  x = vsetq_lane_u8(x5, x, 4);
+  x = vsetq_lane_u8(x6, x, 5);
+  x = vsetq_lane_u8(x7, x, 6);
+  x = vsetq_lane_u8(x8, x, 7);
+  x = vsetq_lane_u8(x9, x, 8);
+  x = vsetq_lane_u8(x10, x, 9);
+  x = vsetq_lane_u8(x11, x, 10);
+  x = vsetq_lane_u8(x12, x, 11);
+  x = vsetq_lane_u8(x13, x, 12);
+  x = vsetq_lane_u8(x14, x, 13);
+  x = vsetq_lane_u8(x15, x, 14);
+  x = vsetq_lane_u8(x16, x, 15);
+  return x;
+}
+
+// We have to do the same work for make_int8x16_t
+simdutf_really_inline int8x16_t make_int8x16_t(int8_t x1,  int8_t x2,  int8_t x3,  int8_t x4,
+                                       int8_t x5,  int8_t x6,  int8_t x7,  int8_t x8,
+                                       int8_t x9,  int8_t x10, int8_t x11, int8_t x12,
+                                       int8_t x13, int8_t x14, int8_t x15, int8_t x16) {
+  // Doing a load like so end ups generating worse code.
+  // int8_t array[16] = {x1, x2, x3, x4, x5, x6, x7, x8,
+  //                     x9, x10,x11,x12,x13,x14,x15,x16};
+  // return vld1q_s8(array);
+  int8x16_t x{};
+  // incredibly, Visual Studio does not allow x[0] = x1
+  x = vsetq_lane_s8(x1, x, 0);
+  x = vsetq_lane_s8(x2, x, 1);
+  x = vsetq_lane_s8(x3, x, 2);
+  x = vsetq_lane_s8(x4, x, 3);
+  x = vsetq_lane_s8(x5, x, 4);
+  x = vsetq_lane_s8(x6, x, 5);
+  x = vsetq_lane_s8(x7, x, 6);
+  x = vsetq_lane_s8(x8, x, 7);
+  x = vsetq_lane_s8(x9, x, 8);
+  x = vsetq_lane_s8(x10, x, 9);
+  x = vsetq_lane_s8(x11, x, 10);
+  x = vsetq_lane_s8(x12, x, 11);
+  x = vsetq_lane_s8(x13, x, 12);
+  x = vsetq_lane_s8(x14, x, 13);
+  x = vsetq_lane_s8(x15, x, 14);
+  x = vsetq_lane_s8(x16, x, 15);
+  return x;
+}
+
+simdutf_really_inline uint8x8_t make_uint8x8_t(uint8_t x1,  uint8_t x2,  uint8_t x3,  uint8_t x4,
+                                         uint8_t x5,  uint8_t x6,  uint8_t x7,  uint8_t x8) {
+  uint8x8_t x{};
+  x = vset_lane_u8(x1, x, 0);
+  x = vset_lane_u8(x2, x, 1);
+  x = vset_lane_u8(x3, x, 2);
+  x = vset_lane_u8(x4, x, 3);
+  x = vset_lane_u8(x5, x, 4);
+  x = vset_lane_u8(x6, x, 5);
+  x = vset_lane_u8(x7, x, 6);
+  x = vset_lane_u8(x8, x, 7);
+  return x;
+}
+
+simdutf_really_inline uint16x8_t make_uint16x8_t(uint16_t x1,  uint16_t x2,  uint16_t x3,  uint16_t x4,
+                                       uint16_t x5,  uint16_t x6,  uint16_t x7,  uint16_t x8) {
+  uint16x8_t x{};
+  x = vsetq_lane_u16(x1, x, 0);
+  x = vsetq_lane_u16(x2, x, 1);
+  x = vsetq_lane_u16(x3, x, 2);
+  x = vsetq_lane_u16(x4, x, 3);
+  x = vsetq_lane_u16(x5, x, 4);
+  x = vsetq_lane_u16(x6, x, 5);
+  x = vsetq_lane_u16(x7, x, 6);
+  x = vsetq_lane_u16(x8, x, 7);;
+  return x;
+}
+
+simdutf_really_inline int16x8_t make_int16x8_t(int16_t x1,  int16_t x2,  int16_t x3,  int16_t x4,
+                                       int16_t x5,  int16_t x6,  int16_t x7,  int16_t x8) {
+  uint16x8_t x{};
+  x = vsetq_lane_s16(x1, x, 0);
+  x = vsetq_lane_s16(x2, x, 1);
+  x = vsetq_lane_s16(x3, x, 2);
+  x = vsetq_lane_s16(x4, x, 3);
+  x = vsetq_lane_s16(x5, x, 4);
+  x = vsetq_lane_s16(x6, x, 5);
+  x = vsetq_lane_s16(x7, x, 6);
+  x = vsetq_lane_s16(x8, x, 7);;
+  return x;
+}
+
+
+// End of private section with Visual Studio workaround
+} // namespace
+#endif // SIMDUTF_REGULAR_VISUAL_STUDIO
+
+
+  template<typename T>
+  struct simd8;
+
+  //
+  // Base class of simd8<uint8_t> and simd8<bool>, both of which use uint8x16_t internally.
+  //
+  template<typename T, typename Mask=simd8<bool>>
+  struct base_u8 {
+    uint8x16_t value;
+    static const int SIZE = sizeof(value);
+
+    // Conversion from/to SIMD register
+    simdutf_really_inline base_u8(const uint8x16_t _value) : value(_value) {}
+    simdutf_really_inline operator const uint8x16_t&() const { return this->value; }
+    simdutf_really_inline operator uint8x16_t&() { return this->value; }
+    simdutf_really_inline T first() const { return vgetq_lane_u8(*this,0); }
+    simdutf_really_inline T last() const { return vgetq_lane_u8(*this,15); }
+
+    // Bit operations
+    simdutf_really_inline simd8<T> operator|(const simd8<T> other) const { return vorrq_u8(*this, other); }
+    simdutf_really_inline simd8<T> operator&(const simd8<T> other) const { return vandq_u8(*this, other); }
+    simdutf_really_inline simd8<T> operator^(const simd8<T> other) const { return veorq_u8(*this, other); }
+    simdutf_really_inline simd8<T> bit_andnot(const simd8<T> other) const { return vbicq_u8(*this, other); }
+    simdutf_really_inline simd8<T> operator~() const { return *this ^ 0xFFu; }
+    simdutf_really_inline simd8<T>& operator|=(const simd8<T> other) { auto this_cast = static_cast<simd8<T>*>(this); *this_cast = *this_cast | other; return *this_cast; }
+    simdutf_really_inline simd8<T>& operator&=(const simd8<T> other) { auto this_cast = static_cast<simd8<T>*>(this); *this_cast = *this_cast & other; return *this_cast; }
+    simdutf_really_inline simd8<T>& operator^=(const simd8<T> other) { auto this_cast = static_cast<simd8<T>*>(this); *this_cast = *this_cast ^ other; return *this_cast; }
+
+    simdutf_really_inline Mask operator==(const simd8<T> other) const { return vceqq_u8(*this, other); }
+
+    template<int N=1>
+    simdutf_really_inline simd8<T> prev(const simd8<T> prev_chunk) const {
+      return vextq_u8(prev_chunk, *this, 16 - N);
+    }
+  };
+
+  // SIMD byte mask type (returned by things like eq and gt)
+  template<>
+  struct simd8<bool>: base_u8<bool> {
+    typedef uint16_t bitmask_t;
+    typedef uint32_t bitmask2_t;
+
+    static simdutf_really_inline simd8<bool> splat(bool _value) { return vmovq_n_u8(uint8_t(-(!!_value))); }
+
+    simdutf_really_inline simd8(const uint8x16_t _value) : base_u8<bool>(_value) {}
+    // False constructor
+    simdutf_really_inline simd8() : simd8(vdupq_n_u8(0)) {}
+    // Splat constructor
+    simdutf_really_inline simd8(bool _value) : simd8(splat(_value)) {}
+    simdutf_really_inline void store(uint8_t dst[16]) const { return vst1q_u8(dst, *this); }
+
+    // We return uint32_t instead of uint16_t because that seems to be more efficient for most
+    // purposes (cutting it down to uint16_t costs performance in some compilers).
+    simdutf_really_inline uint32_t to_bitmask() const {
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+      const uint8x16_t bit_mask =  make_uint8x16_t(0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80,
+                                                   0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80);
+#else
+      const uint8x16_t bit_mask =  {0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80,
+                                    0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80};
+#endif
+      auto minput = *this & bit_mask;
+      uint8x16_t tmp = vpaddq_u8(minput, minput);
+      tmp = vpaddq_u8(tmp, tmp);
+      tmp = vpaddq_u8(tmp, tmp);
+      return vgetq_lane_u16(vreinterpretq_u16_u8(tmp), 0);
+    }
+
+    // Returns 4-bit out of each byte, alternating between the high 4 bits and low bits
+    // result it is 64 bit.
+    // This method is expected to be faster than none() and is equivalent
+    // when the vector register is the result of a comparison, with byte
+    // values 0xff and 0x00.
+    simdutf_really_inline uint64_t to_bitmask64() const {
+      return vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(vreinterpretq_u16_u8(*this), 4)), 0);
+    }
+
+    simdutf_really_inline bool any() const { return vmaxvq_u8(*this) != 0; }
+    simdutf_really_inline bool none() const { return vmaxvq_u8(*this) == 0; }
+    simdutf_really_inline bool all() const { return vminvq_u8(*this) == 0xFF; }
+
+
+  };
+
+  // Unsigned bytes
+  template<>
+  struct simd8<uint8_t>: base_u8<uint8_t> {
+    static simdutf_really_inline simd8<uint8_t> splat(uint8_t _value) { return vmovq_n_u8(_value); }
+    static simdutf_really_inline simd8<uint8_t> zero() { return vdupq_n_u8(0); }
+    static simdutf_really_inline simd8<uint8_t> load(const uint8_t* values) { return vld1q_u8(values); }
+    simdutf_really_inline simd8(const uint8x16_t _value) : base_u8<uint8_t>(_value) {}
+    // Zero constructor
+    simdutf_really_inline simd8() : simd8(zero()) {}
+    // Array constructor
+    simdutf_really_inline simd8(const uint8_t values[16]) : simd8(load(values)) {}
+    // Splat constructor
+    simdutf_really_inline simd8(uint8_t _value) : simd8(splat(_value)) {}
+    // Member-by-member initialization
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+    simdutf_really_inline simd8(
+      uint8_t v0,  uint8_t v1,  uint8_t v2,  uint8_t v3,  uint8_t v4,  uint8_t v5,  uint8_t v6,  uint8_t v7,
+      uint8_t v8,  uint8_t v9,  uint8_t v10, uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14, uint8_t v15
+    ) : simd8(make_uint8x16_t(
+      v0, v1, v2, v3, v4, v5, v6, v7,
+      v8, v9, v10,v11,v12,v13,v14,v15
+    )) {}
+#else
+    simdutf_really_inline simd8(
+      uint8_t v0,  uint8_t v1,  uint8_t v2,  uint8_t v3,  uint8_t v4,  uint8_t v5,  uint8_t v6,  uint8_t v7,
+      uint8_t v8,  uint8_t v9,  uint8_t v10, uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14, uint8_t v15
+    ) : simd8(uint8x16_t{
+      v0, v1, v2, v3, v4, v5, v6, v7,
+      v8, v9, v10,v11,v12,v13,v14,v15
+    }) {}
+#endif
+
+    // Repeat 16 values as many times as necessary (usually for lookup tables)
+    simdutf_really_inline static simd8<uint8_t> repeat_16(
+      uint8_t v0,  uint8_t v1,  uint8_t v2,  uint8_t v3,  uint8_t v4,  uint8_t v5,  uint8_t v6,  uint8_t v7,
+      uint8_t v8,  uint8_t v9,  uint8_t v10, uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14, uint8_t v15
+    ) {
+      return simd8<uint8_t>(
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15
+      );
+    }
+
+    // Store to array
+    simdutf_really_inline void store(uint8_t dst[16]) const { return vst1q_u8(dst, *this); }
+
+    // Saturated math
+    simdutf_really_inline simd8<uint8_t> saturating_add(const simd8<uint8_t> other) const { return vqaddq_u8(*this, other); }
+    simdutf_really_inline simd8<uint8_t> saturating_sub(const simd8<uint8_t> other) const { return vqsubq_u8(*this, other); }
+
+    // Addition/subtraction are the same for signed and unsigned
+    simdutf_really_inline simd8<uint8_t> operator+(const simd8<uint8_t> other) const { return vaddq_u8(*this, other); }
+    simdutf_really_inline simd8<uint8_t> operator-(const simd8<uint8_t> other) const { return vsubq_u8(*this, other); }
+    simdutf_really_inline simd8<uint8_t>& operator+=(const simd8<uint8_t> other) { *this = *this + other; return *this; }
+    simdutf_really_inline simd8<uint8_t>& operator-=(const simd8<uint8_t> other) { *this = *this - other; return *this; }
+
+    // Order-specific operations
+    simdutf_really_inline uint8_t max_val() const { return vmaxvq_u8(*this); }
+    simdutf_really_inline uint8_t min_val() const { return vminvq_u8(*this); }
+    simdutf_really_inline simd8<uint8_t> max_val(const simd8<uint8_t> other) const { return vmaxq_u8(*this, other); }
+    simdutf_really_inline simd8<uint8_t> min_val(const simd8<uint8_t> other) const { return vminq_u8(*this, other); }
+    simdutf_really_inline simd8<bool> operator<=(const simd8<uint8_t> other) const { return vcleq_u8(*this, other); }
+    simdutf_really_inline simd8<bool> operator>=(const simd8<uint8_t> other) const { return vcgeq_u8(*this, other); }
+    simdutf_really_inline simd8<bool> operator<(const simd8<uint8_t> other) const { return vcltq_u8(*this, other); }
+    simdutf_really_inline simd8<bool> operator>(const simd8<uint8_t> other) const { return vcgtq_u8(*this, other); }
+    // Same as >, but instead of guaranteeing all 1's == true, false = 0 and true = nonzero. For ARM, returns all 1's.
+    simdutf_really_inline simd8<uint8_t> gt_bits(const simd8<uint8_t> other) const { return simd8<uint8_t>(*this > other); }
+    // Same as <, but instead of guaranteeing all 1's == true, false = 0 and true = nonzero. For ARM, returns all 1's.
+    simdutf_really_inline simd8<uint8_t> lt_bits(const simd8<uint8_t> other) const { return simd8<uint8_t>(*this < other); }
+
+    // Bit-specific operations
+    simdutf_really_inline simd8<bool> any_bits_set(simd8<uint8_t> bits) const { return vtstq_u8(*this, bits); }
+    simdutf_really_inline bool is_ascii() const { return this->max_val() < 0b10000000u; }
+
+    simdutf_really_inline bool any_bits_set_anywhere() const { return this->max_val() != 0; }
+    simdutf_really_inline bool any_bits_set_anywhere(simd8<uint8_t> bits) const { return (*this & bits).any_bits_set_anywhere(); }
+    template<int N>
+    simdutf_really_inline simd8<uint8_t> shr() const { return vshrq_n_u8(*this, N); }
+    template<int N>
+    simdutf_really_inline simd8<uint8_t> shl() const { return vshlq_n_u8(*this, N); }
+
+    // Perform a lookup assuming the value is between 0 and 16 (undefined behavior for out of range values)
+    template<typename L>
+    simdutf_really_inline simd8<L> lookup_16(simd8<L> lookup_table) const {
+      return lookup_table.apply_lookup_16_to(*this);
+    }
+
+
+    template<typename L>
+    simdutf_really_inline simd8<L> lookup_16(
+        L replace0,  L replace1,  L replace2,  L replace3,
+        L replace4,  L replace5,  L replace6,  L replace7,
+        L replace8,  L replace9,  L replace10, L replace11,
+        L replace12, L replace13, L replace14, L replace15) const {
+      return lookup_16(simd8<L>::repeat_16(
+        replace0,  replace1,  replace2,  replace3,
+        replace4,  replace5,  replace6,  replace7,
+        replace8,  replace9,  replace10, replace11,
+        replace12, replace13, replace14, replace15
+      ));
+    }
+
+    template<typename T>
+    simdutf_really_inline simd8<uint8_t> apply_lookup_16_to(const simd8<T> original) const {
+      return vqtbl1q_u8(*this, simd8<uint8_t>(original));
+    }
+  };
+
+  // Signed bytes
+  template<>
+  struct simd8<int8_t> {
+    int8x16_t value;
+
+    static simdutf_really_inline simd8<int8_t> splat(int8_t _value) { return vmovq_n_s8(_value); }
+    static simdutf_really_inline simd8<int8_t> zero() { return vdupq_n_s8(0); }
+    static simdutf_really_inline simd8<int8_t> load(const int8_t values[16]) { return vld1q_s8(values); }
+    template <endianness big_endian>
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * p) const {
+      uint16x8_t first = vmovl_u8(vget_low_u8 (vreinterpretq_u8_s8(this->value)));
+      uint16x8_t second = vmovl_high_u8(vreinterpretq_u8_s8(this->value));
+      if (big_endian) {
+        #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+        const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+        #else
+        const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+        #endif
+        first = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(first), swap));
+        second = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(second), swap));
+      }
+      vst1q_u16(reinterpret_cast<uint16_t*>(p), first);
+      vst1q_u16(reinterpret_cast<uint16_t*>(p + 8), second);
+    }
+    simdutf_really_inline void store_ascii_as_utf32(char32_t * p) const {
+      vst1q_u32(reinterpret_cast<uint32_t*>(p), vmovl_u16(vget_low_u16(vmovl_u8(vget_low_u8 (vreinterpretq_u8_s8(this->value))))));
+      vst1q_u32(reinterpret_cast<uint32_t*>(p + 4), vmovl_high_u16(vmovl_u8(vget_low_u8 (vreinterpretq_u8_s8(this->value)))));
+      vst1q_u32(reinterpret_cast<uint32_t*>(p + 8), vmovl_u16(vget_low_u16(vmovl_high_u8(vreinterpretq_u8_s8(this->value)))));
+      vst1q_u32(reinterpret_cast<uint32_t*>(p + 12), vmovl_high_u16(vmovl_high_u8(vreinterpretq_u8_s8(this->value))));
+    }
+    // Conversion from/to SIMD register
+    simdutf_really_inline simd8(const int8x16_t _value) : value{_value} {}
+    simdutf_really_inline operator const int8x16_t&() const { return this->value; }
+    simdutf_really_inline operator const uint8x16_t() const { return vreinterpretq_u8_s8(this->value); }
+    simdutf_really_inline operator int8x16_t&() { return this->value; }
+
+    // Zero constructor
+    simdutf_really_inline simd8() : simd8(zero()) {}
+    // Splat constructor
+    simdutf_really_inline simd8(int8_t _value) : simd8(splat(_value)) {}
+    // Array constructor
+    simdutf_really_inline simd8(const int8_t* values) : simd8(load(values)) {}
+    // Member-by-member initialization
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+    simdutf_really_inline simd8(
+      int8_t v0,  int8_t v1,  int8_t v2,  int8_t v3, int8_t v4,  int8_t v5,  int8_t v6,  int8_t v7,
+      int8_t v8,  int8_t v9,  int8_t v10, int8_t v11, int8_t v12, int8_t v13, int8_t v14, int8_t v15
+    ) : simd8(make_int8x16_t(
+      v0, v1, v2, v3, v4, v5, v6, v7,
+      v8, v9, v10,v11,v12,v13,v14,v15
+    )) {}
+#else
+    simdutf_really_inline simd8(
+      int8_t v0,  int8_t v1,  int8_t v2,  int8_t v3, int8_t v4,  int8_t v5,  int8_t v6,  int8_t v7,
+      int8_t v8,  int8_t v9,  int8_t v10, int8_t v11, int8_t v12, int8_t v13, int8_t v14, int8_t v15
+    ) : simd8(int8x16_t{
+      v0, v1, v2, v3, v4, v5, v6, v7,
+      v8, v9, v10,v11,v12,v13,v14,v15
+    }) {}
+#endif
+    // Repeat 16 values as many times as necessary (usually for lookup tables)
+    simdutf_really_inline static simd8<int8_t> repeat_16(
+      int8_t v0,  int8_t v1,  int8_t v2,  int8_t v3,  int8_t v4,  int8_t v5,  int8_t v6,  int8_t v7,
+      int8_t v8,  int8_t v9,  int8_t v10, int8_t v11, int8_t v12, int8_t v13, int8_t v14, int8_t v15
+    ) {
+      return simd8<int8_t>(
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15
+      );
+    }
+
+    // Store to array
+    simdutf_really_inline void store(int8_t dst[16]) const { return vst1q_s8(dst, value); }
+    // Explicit conversion to/from unsigned
+    //
+    // Under Visual Studio/ARM64 uint8x16_t and int8x16_t are apparently the same type.
+    // In theory, we could check this occurrence with std::same_as and std::enabled_if but it is C++14
+    // and relatively ugly and hard to read.
+#ifndef SIMDUTF_REGULAR_VISUAL_STUDIO
+    simdutf_really_inline explicit simd8(const uint8x16_t other): simd8(vreinterpretq_s8_u8(other)) {}
+#endif
+    simdutf_really_inline operator simd8<uint8_t>() const { return vreinterpretq_u8_s8(this->value); }
+
+    simdutf_really_inline simd8<int8_t> operator|(const simd8<int8_t> other) const { return vorrq_s8(value, other.value); }
+    simdutf_really_inline simd8<int8_t> operator&(const simd8<int8_t> other) const { return vandq_s8(value, other.value); }
+    simdutf_really_inline simd8<int8_t> operator^(const simd8<int8_t> other) const { return veorq_s8(value, other.value); }
+    simdutf_really_inline simd8<int8_t> bit_andnot(const simd8<int8_t> other) const { return vbicq_s8(value, other.value); }
+
+    // Math
+    simdutf_really_inline simd8<int8_t> operator+(const simd8<int8_t> other) const { return vaddq_s8(value, other.value); }
+    simdutf_really_inline simd8<int8_t> operator-(const simd8<int8_t> other) const { return vsubq_s8(value, other.value); }
+    simdutf_really_inline simd8<int8_t>& operator+=(const simd8<int8_t> other) { *this = *this + other; return *this; }
+    simdutf_really_inline simd8<int8_t>& operator-=(const simd8<int8_t> other) { *this = *this - other; return *this; }
+
+    simdutf_really_inline int8_t max_val() const { return vmaxvq_s8(value); }
+    simdutf_really_inline int8_t min_val() const { return vminvq_s8(value); }
+    simdutf_really_inline bool is_ascii() const { return this->min_val() >= 0; }
+
+    // Order-sensitive comparisons
+    simdutf_really_inline simd8<int8_t> max_val(const simd8<int8_t> other) const { return vmaxq_s8(value, other.value); }
+    simdutf_really_inline simd8<int8_t> min_val(const simd8<int8_t> other) const { return vminq_s8(value, other.value); }
+    simdutf_really_inline simd8<bool> operator>(const simd8<int8_t> other) const { return vcgtq_s8(value, other.value); }
+    simdutf_really_inline simd8<bool> operator<(const simd8<int8_t> other) const { return vcltq_s8(value, other.value); }
+    simdutf_really_inline simd8<bool> operator==(const simd8<int8_t> other) const { return vceqq_s8(value, other.value); }
+
+    template<int N=1>
+    simdutf_really_inline simd8<int8_t> prev(const simd8<int8_t> prev_chunk) const {
+      return vextq_s8(prev_chunk, *this, 16 - N);
+    }
+
+    // Perform a lookup assuming no value is larger than 16
+    template<typename L>
+    simdutf_really_inline simd8<L> lookup_16(simd8<L> lookup_table) const {
+      return lookup_table.apply_lookup_16_to(*this);
+    }
+    template<typename L>
+    simdutf_really_inline simd8<L> lookup_16(
+        L replace0,  L replace1,  L replace2,  L replace3,
+        L replace4,  L replace5,  L replace6,  L replace7,
+        L replace8,  L replace9,  L replace10, L replace11,
+        L replace12, L replace13, L replace14, L replace15) const {
+      return lookup_16(simd8<L>::repeat_16(
+        replace0,  replace1,  replace2,  replace3,
+        replace4,  replace5,  replace6,  replace7,
+        replace8,  replace9,  replace10, replace11,
+        replace12, replace13, replace14, replace15
+      ));
+    }
+
+    template<typename T>
+    simdutf_really_inline simd8<int8_t> apply_lookup_16_to(const simd8<T> original) {
+      return vqtbl1q_s8(*this, simd8<uint8_t>(original));
+    }
+  };
+
+  template<typename T>
+  struct simd8x64 {
+    static constexpr int NUM_CHUNKS = 64 / sizeof(simd8<T>);
+    static_assert(NUM_CHUNKS == 4, "ARM kernel should use four registers per 64-byte block.");
+    simd8<T> chunks[NUM_CHUNKS];
+
+    simd8x64(const simd8x64<T>& o) = delete; // no copy allowed
+    simd8x64<T>& operator=(const simd8<T> other) = delete; // no assignment allowed
+    simd8x64() = delete; // no default constructor allowed
+
+    simdutf_really_inline simd8x64(const simd8<T> chunk0, const simd8<T> chunk1, const simd8<T> chunk2, const simd8<T> chunk3) : chunks{chunk0, chunk1, chunk2, chunk3} {}
+    simdutf_really_inline simd8x64(const T* ptr) : chunks{simd8<T>::load(ptr), simd8<T>::load(ptr+sizeof(simd8<T>)/sizeof(T)), simd8<T>::load(ptr+2*sizeof(simd8<T>)/sizeof(T)), simd8<T>::load(ptr+3*sizeof(simd8<T>)/sizeof(T))} {}
+
+    simdutf_really_inline void store(T* ptr) const {
+      this->chunks[0].store(ptr+sizeof(simd8<T>)*0/sizeof(T));
+      this->chunks[1].store(ptr+sizeof(simd8<T>)*1/sizeof(T));
+      this->chunks[2].store(ptr+sizeof(simd8<T>)*2/sizeof(T));
+      this->chunks[3].store(ptr+sizeof(simd8<T>)*3/sizeof(T));
+    }
+
+
+    simdutf_really_inline simd8x64<T>& operator |=(const simd8x64<T> &other) {
+      this->chunks[0] |= other.chunks[0];
+      this->chunks[1] |= other.chunks[1];
+      this->chunks[2] |= other.chunks[2];
+      this->chunks[3] |= other.chunks[3];
+      return *this;
+    }
+
+    simdutf_really_inline simd8<T> reduce_or() const {
+      return (this->chunks[0] | this->chunks[1]) | (this->chunks[2] | this->chunks[3]);
+    }
+
+    simdutf_really_inline bool is_ascii() const {
+      return reduce_or().is_ascii();
+    }
+
+    template <endianness endian>
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * ptr) const {
+      this->chunks[0].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*0);
+      this->chunks[1].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*1);
+      this->chunks[2].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*2);
+      this->chunks[3].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*3);
+    }
+
+    simdutf_really_inline void store_ascii_as_utf32(char32_t * ptr) const {
+      this->chunks[0].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*0);
+      this->chunks[1].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*1);
+      this->chunks[2].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*2);
+      this->chunks[3].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*3);
+    }
+
+    simdutf_really_inline uint64_t to_bitmask() const {
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+      const uint8x16_t bit_mask = make_uint8x16_t(
+        0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80,
+        0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80
+      );
+#else
+      const uint8x16_t bit_mask = {
+        0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80,
+        0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80
+      };
+#endif
+      // Add each of the elements next to each other, successively, to stuff each 8 byte mask into one.
+      uint8x16_t sum0 = vpaddq_u8(vandq_u8(uint8x16_t(this->chunks[0]), bit_mask), vandq_u8(uint8x16_t(this->chunks[1]), bit_mask));
+      uint8x16_t sum1 = vpaddq_u8(vandq_u8(uint8x16_t(this->chunks[2]), bit_mask), vandq_u8(uint8x16_t(this->chunks[3]), bit_mask));
+      sum0 = vpaddq_u8(sum0, sum1);
+      sum0 = vpaddq_u8(sum0, sum0);
+      return vgetq_lane_u64(vreinterpretq_u64_u8(sum0), 0);
+    }
+
+    simdutf_really_inline uint64_t eq(const T m) const {
+    const simd8<T> mask = simd8<T>::splat(m);
+    return  simd8x64<bool>(
+      this->chunks[0] == mask,
+      this->chunks[1] == mask,
+      this->chunks[2] == mask,
+      this->chunks[3] == mask
+    ).to_bitmask();
+  }
+
+  simdutf_really_inline uint64_t lteq(const T m) const {
+    const simd8<T> mask = simd8<T>::splat(m);
+    return  simd8x64<bool>(
+      this->chunks[0] <= mask,
+      this->chunks[1] <= mask,
+      this->chunks[2] <= mask,
+      this->chunks[3] <= mask
+    ).to_bitmask();
+  }
+
+    simdutf_really_inline uint64_t in_range(const T low, const T high) const {
+      const simd8<T> mask_low = simd8<T>::splat(low);
+      const simd8<T> mask_high = simd8<T>::splat(high);
+
+      return  simd8x64<bool>(
+        (this->chunks[0] <= mask_high) & (this->chunks[0] >= mask_low),
+        (this->chunks[1] <= mask_high) & (this->chunks[1] >= mask_low),
+        (this->chunks[2] <= mask_high) & (this->chunks[2] >= mask_low),
+        (this->chunks[3] <= mask_high) & (this->chunks[3] >= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t not_in_range(const T low, const T high) const {
+      const simd8<T> mask_low = simd8<T>::splat(low);
+      const simd8<T> mask_high = simd8<T>::splat(high);
+      return  simd8x64<bool>(
+        (this->chunks[0] > mask_high) | (this->chunks[0] < mask_low),
+        (this->chunks[1] > mask_high) | (this->chunks[1] < mask_low),
+        (this->chunks[2] > mask_high) | (this->chunks[2] < mask_low),
+        (this->chunks[3] > mask_high) | (this->chunks[3] < mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t lt(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] < mask,
+        this->chunks[1] < mask,
+        this->chunks[2] < mask,
+        this->chunks[3] < mask
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t gt(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] > mask,
+        this->chunks[1] > mask,
+        this->chunks[2] > mask,
+        this->chunks[3] > mask
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t gteq(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] >= mask,
+        this->chunks[1] >= mask,
+        this->chunks[2] >= mask,
+        this->chunks[3] >= mask
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t gteq_unsigned(const uint8_t m) const {
+      const simd8<uint8_t> mask = simd8<uint8_t>::splat(m);
+      return  simd8x64<bool>(
+        simd8<uint8_t>(uint8x16_t(this->chunks[0])) >= mask,
+        simd8<uint8_t>(uint8x16_t(this->chunks[1])) >= mask,
+        simd8<uint8_t>(uint8x16_t(this->chunks[2])) >= mask,
+        simd8<uint8_t>(uint8x16_t(this->chunks[3])) >= mask
+      ).to_bitmask();
+    }
+  }; // struct simd8x64<T>
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/simd16-inl.h
+/* begin file src/simdutf/arm64/simd16-inl.h */
+template<typename T>
+struct simd16;
+
+  template<typename T, typename Mask=simd16<bool>>
+  struct base_u16 {
+    uint16x8_t value;
+    static const int SIZE = sizeof(value);
+
+    // Conversion from/to SIMD register
+    simdutf_really_inline base_u16() = default;
+    simdutf_really_inline base_u16(const uint16x8_t _value) : value(_value) {}
+    simdutf_really_inline operator const uint16x8_t&() const { return this->value; }
+    simdutf_really_inline operator uint16x8_t&() { return this->value; }
+    // Bit operations
+    simdutf_really_inline simd16<T> operator|(const simd16<T> other) const { return vorrq_u16(*this, other); }
+    simdutf_really_inline simd16<T> operator&(const simd16<T> other) const { return vandq_u16(*this, other); }
+    simdutf_really_inline simd16<T> operator^(const simd16<T> other) const { return veorq_u16(*this, other); }
+    simdutf_really_inline simd16<T> bit_andnot(const simd16<T> other) const { return vbicq_u16(*this, other); }
+    simdutf_really_inline simd16<T> operator~() const { return *this ^ 0xFFu; }
+    simdutf_really_inline simd16<T>& operator|=(const simd16<T> other) { auto this_cast = static_cast<simd16<T>*>(this); *this_cast = *this_cast | other; return *this_cast; }
+    simdutf_really_inline simd16<T>& operator&=(const simd16<T> other) { auto this_cast = static_cast<simd16<T>*>(this); *this_cast = *this_cast & other; return *this_cast; }
+    simdutf_really_inline simd16<T>& operator^=(const simd16<T> other) { auto this_cast = static_cast<simd16<T>*>(this); *this_cast = *this_cast ^ other; return *this_cast; }
+
+    simdutf_really_inline Mask operator==(const simd16<T> other) const { return vceqq_u16(*this, other); }
+
+    template<int N=1>
+    simdutf_really_inline simd16<T> prev(const simd16<T> prev_chunk) const {
+      return vextq_u18(prev_chunk, *this, 8 - N);
+    }
+  };
+
+template<typename T, typename Mask=simd16<bool>>
+struct base16: base_u16<T> {
+  typedef uint16_t bitmask_t;
+  typedef uint32_t bitmask2_t;
+
+  simdutf_really_inline base16() : base_u16<T>() {}
+  simdutf_really_inline base16(const uint16x8_t _value) : base_u16<T>(_value) {}
+  template <typename Pointer>
+  simdutf_really_inline base16(const Pointer* ptr) : base16(vld1q_u16(ptr)) {}
+
+  simdutf_really_inline Mask operator==(const simd16<T> other) const { return vceqq_u16(*this, other); }
+
+  static const int SIZE = sizeof(base_u16<T>::value);
+
+  template<int N=1>
+  simdutf_really_inline simd16<T> prev(const simd16<T> prev_chunk) const {
+    return vextq_u18(prev_chunk, *this, 8 - N);
+  }
+};
+
+// SIMD byte mask type (returned by things like eq and gt)
+template<>
+struct simd16<bool>: base16<bool> {
+  static simdutf_really_inline simd16<bool> splat(bool _value) { return vmovq_n_u16(uint16_t(-(!!_value))); }
+
+  simdutf_really_inline simd16<bool>() : base16() {}
+  simdutf_really_inline simd16<bool>(const uint16x8_t _value) : base16<bool>(_value) {}
+  // Splat constructor
+  simdutf_really_inline simd16<bool>(bool _value) : base16<bool>(splat(_value)) {}
+
+};
+
+template<typename T>
+struct base16_numeric: base16<T> {
+  static simdutf_really_inline simd16<T> splat(T _value) { return vmovq_n_u16(_value); }
+  static simdutf_really_inline simd16<T> zero() { return vdupq_n_u16(0); }
+  static simdutf_really_inline simd16<T> load(const T values[8]) {
+    return vld1q_u16(reinterpret_cast<const uint16_t*>(values));
+  }
+
+  simdutf_really_inline base16_numeric() : base16<T>() {}
+  simdutf_really_inline base16_numeric(const uint16x8_t _value) : base16<T>(_value) {}
+
+  // Store to array
+  simdutf_really_inline void store(T dst[8]) const { return vst1q_u16(dst, *this); }
+
+  // Override to distinguish from bool version
+  simdutf_really_inline simd16<T> operator~() const { return *this ^ 0xFFu; }
+
+  // Addition/subtraction are the same for signed and unsigned
+  simdutf_really_inline simd16<T> operator+(const simd16<T> other) const { return vaddq_u8(*this, other); }
+  simdutf_really_inline simd16<T> operator-(const simd16<T> other) const { return vsubq_u8(*this, other); }
+  simdutf_really_inline simd16<T>& operator+=(const simd16<T> other) { *this = *this + other; return *static_cast<simd16<T>*>(this); }
+  simdutf_really_inline simd16<T>& operator-=(const simd16<T> other) { *this = *this - other; return *static_cast<simd16<T>*>(this); }
+};
+
+// Signed words
+template<>
+struct simd16<int16_t> : base16_numeric<int16_t> {
+  simdutf_really_inline simd16() : base16_numeric<int16_t>() {}
+#ifndef SIMDUTF_REGULAR_VISUAL_STUDIO
+  simdutf_really_inline simd16(const uint16x8_t _value) : base16_numeric<int16_t>(_value) {}
+#endif
+  simdutf_really_inline simd16(const int16x8_t _value) : base16_numeric<int16_t>(vreinterpretq_u16_s16(_value)) {}
+
+  // Splat constructor
+  simdutf_really_inline simd16(int16_t _value) : simd16(splat(_value)) {}
+  // Array constructor
+  simdutf_really_inline simd16(const int16_t* values) : simd16(load(values)) {}
+  simdutf_really_inline simd16(const char16_t* values) : simd16(load(reinterpret_cast<const int16_t*>(values))) {}
+  simdutf_really_inline operator simd16<uint16_t>() const;
+  simdutf_really_inline operator const uint16x8_t&() const { return this->value; }
+  simdutf_really_inline operator const int16x8_t() const { return vreinterpretq_s16_u16(this->value); }
+
+  simdutf_really_inline int16_t max_val() const { return vmaxvq_s16(vreinterpretq_s16_u16(this->value)); }
+  simdutf_really_inline int16_t min_val() const { return vminvq_s16(vreinterpretq_s16_u16(this->value)); }
+  // Order-sensitive comparisons
+  simdutf_really_inline simd16<int16_t> max_val(const simd16<int16_t> other) const { return vmaxq_s16(vreinterpretq_s16_u16(this->value), vreinterpretq_s16_u16(other.value)); }
+  simdutf_really_inline simd16<int16_t> min_val(const simd16<int16_t> other) const { return vmaxq_s16(vreinterpretq_s16_u16(this->value), vreinterpretq_s16_u16(other.value)); }
+  simdutf_really_inline simd16<bool> operator>(const simd16<int16_t> other) const { return vcgtq_s16(vreinterpretq_s16_u16(this->value), vreinterpretq_s16_u16(other.value)); }
+  simdutf_really_inline simd16<bool> operator<(const simd16<int16_t> other) const { return vcltq_s16(vreinterpretq_s16_u16(this->value), vreinterpretq_s16_u16(other.value)); }
+};
+
+
+
+
+// Unsigned words
+template<>
+struct simd16<uint16_t>: base16_numeric<uint16_t>  {
+  simdutf_really_inline simd16() : base16_numeric<uint16_t>() {}
+  simdutf_really_inline simd16(const uint16x8_t _value) : base16_numeric<uint16_t>(_value) {}
+
+  // Splat constructor
+  simdutf_really_inline simd16(uint16_t _value) : simd16(splat(_value)) {}
+  // Array constructor
+  simdutf_really_inline simd16(const uint16_t* values) : simd16(load(values)) {}
+  simdutf_really_inline simd16(const char16_t* values) : simd16(load(reinterpret_cast<const uint16_t*>(values))) {}
+
+
+  simdutf_really_inline int16_t max_val() const { return vmaxvq_u16(*this); }
+  simdutf_really_inline int16_t min_val() const { return vminvq_u16(*this); }
+  // Saturated math
+  simdutf_really_inline simd16<uint16_t> saturating_add(const simd16<uint16_t> other) const { return vqaddq_u16(*this, other); }
+  simdutf_really_inline simd16<uint16_t> saturating_sub(const simd16<uint16_t> other) const { return vqsubq_u16(*this, other); }
+
+  // Order-specific operations
+  simdutf_really_inline simd16<uint16_t> max_val(const simd16<uint16_t> other) const { return vmaxq_u16(*this, other); }
+  simdutf_really_inline simd16<uint16_t> min_val(const simd16<uint16_t> other) const { return vminq_u16(*this, other); }
+  // Same as >, but only guarantees true is nonzero (< guarantees true = -1)
+  simdutf_really_inline simd16<uint16_t> gt_bits(const simd16<uint16_t> other) const { return this->saturating_sub(other); }
+  // Same as <, but only guarantees true is nonzero (< guarantees true = -1)
+  simdutf_really_inline simd16<uint16_t> lt_bits(const simd16<uint16_t> other) const { return other.saturating_sub(*this); }
+  simdutf_really_inline simd16<bool> operator<=(const simd16<uint16_t> other) const { return vcleq_u16(*this, other); }
+  simdutf_really_inline simd16<bool> operator>=(const simd16<uint16_t> other) const { return vcgeq_u16(*this, other); }
+  simdutf_really_inline simd16<bool> operator>(const simd16<uint16_t> other) const { return  vcgtq_u16(*this, other); }
+  simdutf_really_inline simd16<bool> operator<(const simd16<uint16_t> other) const { return vcltq_u16(*this, other); }
+
+  // Bit-specific operations
+  simdutf_really_inline simd16<bool> bits_not_set() const { return *this == uint16_t(0); }
+  template<int N>
+  simdutf_really_inline simd16<uint16_t> shr() const { return simd16<uint16_t>(vshrq_n_u16(*this, N)); }
+  template<int N>
+  simdutf_really_inline simd16<uint16_t> shl() const { return simd16<uint16_t>(vshlq_n_u16(*this, N)); }
+
+  // logical operations
+  simdutf_really_inline simd16<uint16_t> operator|(const simd16<uint16_t> other) const { return vorrq_u16(*this, other); }
+  simdutf_really_inline simd16<uint16_t> operator&(const simd16<uint16_t> other) const { return vandq_u16(*this, other); }
+  simdutf_really_inline simd16<uint16_t> operator^(const simd16<uint16_t> other) const { return veorq_u16(*this, other); }
+
+  // Pack with the unsigned saturation  two uint16_t words into single uint8_t vector
+  static simdutf_really_inline simd8<uint8_t> pack(const simd16<uint16_t>& v0, const simd16<uint16_t>& v1) {
+    return vqmovn_high_u16(vqmovn_u16(v0), v1);
+  }
+
+  // Change the endianness
+  simdutf_really_inline simd16<uint16_t> swap_bytes() const {
+    #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+    const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+    #else
+    const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+    #endif
+    return vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(*this), swap));
+  }
+};
+simdutf_really_inline simd16<int16_t>::operator simd16<uint16_t>() const { return this->value; }
+
+
+  template<typename T>
+  struct simd16x32 {
+    static constexpr int NUM_CHUNKS = 64 / sizeof(simd16<T>);
+    static_assert(NUM_CHUNKS == 4, "ARM kernel should use four registers per 64-byte block.");
+    simd16<T> chunks[NUM_CHUNKS];
+
+    simd16x32(const simd16x32<T>& o) = delete; // no copy allowed
+    simd16x32<T>& operator=(const simd16<T> other) = delete; // no assignment allowed
+    simd16x32() = delete; // no default constructor allowed
+
+    simdutf_really_inline simd16x32(const simd16<T> chunk0, const simd16<T> chunk1, const simd16<T> chunk2, const simd16<T> chunk3) : chunks{chunk0, chunk1, chunk2, chunk3} {}
+    simdutf_really_inline simd16x32(const T* ptr) : chunks{simd16<T>::load(ptr), simd16<T>::load(ptr+sizeof(simd16<T>)/sizeof(T)), simd16<T>::load(ptr+2*sizeof(simd16<T>)/sizeof(T)), simd16<T>::load(ptr+3*sizeof(simd16<T>)/sizeof(T))} {}
+
+    simdutf_really_inline void store(T* ptr) const {
+      this->chunks[0].store(ptr+sizeof(simd16<T>)*0/sizeof(T));
+      this->chunks[1].store(ptr+sizeof(simd16<T>)*1/sizeof(T));
+      this->chunks[2].store(ptr+sizeof(simd16<T>)*2/sizeof(T));
+      this->chunks[3].store(ptr+sizeof(simd16<T>)*3/sizeof(T));
+    }
+
+    simdutf_really_inline simd16<T> reduce_or() const {
+      return (this->chunks[0] | this->chunks[1]) | (this->chunks[2] | this->chunks[3]);
+    }
+
+    simdutf_really_inline bool is_ascii() const {
+      return reduce_or().is_ascii();
+    }
+
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * ptr) const {
+      this->chunks[0].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*0);
+      this->chunks[1].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*1);
+      this->chunks[2].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*2);
+      this->chunks[3].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*3);
+    }
+
+    simdutf_really_inline uint64_t to_bitmask() const {
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+      const uint8x16_t bit_mask = make_uint8x16_t(
+        0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80,
+        0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80
+      );
+#else
+      const uint8x16_t bit_mask = {
+        0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80,
+        0x01, 0x02, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80
+      };
+#endif
+      // Add each of the elements next to each other, successively, to stuff each 8 byte mask into one.
+      uint8x16_t sum0 = vpaddq_u8(vreinterpretq_u8_u16(this->chunks[0] & vreinterpretq_u16_u8(bit_mask)), vreinterpretq_u8_u16(this->chunks[1] & vreinterpretq_u16_u8(bit_mask)));
+      uint8x16_t sum1 = vpaddq_u8(vreinterpretq_u8_u16(this->chunks[2] & vreinterpretq_u16_u8(bit_mask)), vreinterpretq_u8_u16(this->chunks[3] & vreinterpretq_u16_u8(bit_mask)));
+      sum0 = vpaddq_u8(sum0, sum1);
+      sum0 = vpaddq_u8(sum0, sum0);
+      return vgetq_lane_u64(vreinterpretq_u64_u8(sum0), 0);
+    }
+
+    simdutf_really_inline void swap_bytes() {
+      this->chunks[0] = this->chunks[0].swap_bytes();
+      this->chunks[1] = this->chunks[1].swap_bytes();
+      this->chunks[2] = this->chunks[2].swap_bytes();
+      this->chunks[3] = this->chunks[3].swap_bytes();
+    }
+
+    simdutf_really_inline uint64_t eq(const T m) const {
+    const simd16<T> mask = simd16<T>::splat(m);
+    return  simd16x32<bool>(
+      this->chunks[0] == mask,
+      this->chunks[1] == mask,
+      this->chunks[2] == mask,
+      this->chunks[3] == mask
+    ).to_bitmask();
+  }
+
+  simdutf_really_inline uint64_t lteq(const T m) const {
+    const simd16<T> mask = simd16<T>::splat(m);
+    return  simd16x32<bool>(
+      this->chunks[0] <= mask,
+      this->chunks[1] <= mask,
+      this->chunks[2] <= mask,
+      this->chunks[3] <= mask
+    ).to_bitmask();
+  }
+
+    simdutf_really_inline uint64_t in_range(const T low, const T high) const {
+      const simd16<T> mask_low = simd16<T>::splat(low);
+      const simd16<T> mask_high = simd16<T>::splat(high);
+
+      return  simd16x32<bool>(
+        (this->chunks[0] <= mask_high) & (this->chunks[0] >= mask_low),
+        (this->chunks[1] <= mask_high) & (this->chunks[1] >= mask_low),
+        (this->chunks[2] <= mask_high) & (this->chunks[2] >= mask_low),
+        (this->chunks[3] <= mask_high) & (this->chunks[3] >= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t not_in_range(const T low, const T high) const {
+      const simd16<T> mask_low = simd16<T>::splat(low);
+      const simd16<T> mask_high = simd16<T>::splat(high);
+      return  simd16x32<bool>(
+        (this->chunks[0] > mask_high) | (this->chunks[0] < mask_low),
+        (this->chunks[1] > mask_high) | (this->chunks[1] < mask_low),
+        (this->chunks[2] > mask_high) | (this->chunks[2] < mask_low),
+        (this->chunks[3] > mask_high) | (this->chunks[3] < mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t lt(const T m) const {
+      const simd16<T> mask = simd16<T>::splat(m);
+      return  simd16x32<bool>(
+        this->chunks[0] < mask,
+        this->chunks[1] < mask,
+        this->chunks[2] < mask,
+        this->chunks[3] < mask
+      ).to_bitmask();
+    }
+
+  }; // struct simd16x32<T>
+  template<>
+  simdutf_really_inline uint64_t simd16x32<uint16_t>::not_in_range(const uint16_t low, const uint16_t high) const {
+      const simd16<uint16_t> mask_low = simd16<uint16_t>::splat(low);
+      const simd16<uint16_t> mask_high = simd16<uint16_t>::splat(high);
+      simd16x32<uint16_t> x(
+        simd16<uint16_t>((this->chunks[0] > mask_high) | (this->chunks[0] < mask_low)),
+        simd16<uint16_t>((this->chunks[1] > mask_high) | (this->chunks[1] < mask_low)),
+        simd16<uint16_t>((this->chunks[2] > mask_high) | (this->chunks[2] < mask_low)),
+        simd16<uint16_t>((this->chunks[3] > mask_high) | (this->chunks[3] < mask_low))
+      );
+      return  x.to_bitmask();
+    }
+/* end file src/simdutf/arm64/simd16-inl.h */
+} // namespace simd
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+
+#endif // SIMDUTF_ARM64_SIMD_H
+/* end file src/simdutf/arm64/simd.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/end.h
+/* begin file src/simdutf/arm64/end.h */
+/* end file src/simdutf/arm64/end.h */
+
+#endif // SIMDUTF_IMPLEMENTATION_ARM64
+
+#endif // SIMDUTF_ARM64_H
+/* end file src/simdutf/arm64.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell.h
+/* begin file src/simdutf/haswell.h */
+#ifndef SIMDUTF_HASWELL_H
+#define SIMDUTF_HASWELL_H
+
+#ifdef SIMDUTF_WESTMERE_H
+#error "haswell.h must be included before westmere.h"
+#endif
+#ifdef SIMDUTF_FALLBACK_H
+#error "haswell.h must be included before fallback.h"
+#endif
+
+
+// Default Haswell to on if this is x86-64. Even if we're not compiled for it, it could be selected
+// at runtime.
+#ifndef SIMDUTF_IMPLEMENTATION_HASWELL
+//
+// You do not want to restrict it like so: SIMDUTF_IS_X86_64 && __AVX2__
+// because we want to rely on *runtime dispatch*.
+//
+#define SIMDUTF_IMPLEMENTATION_HASWELL (SIMDUTF_IS_X86_64)
+#endif
+// To see why  (__BMI__) && (__PCLMUL__) && (__LZCNT__) are not part of this next line, see
+// https://github.com/simdutf/simdutf/issues/1247
+#define SIMDUTF_CAN_ALWAYS_RUN_HASWELL ((SIMDUTF_IMPLEMENTATION_HASWELL) && (SIMDUTF_IS_X86_64) && (__AVX2__))
+
+#if SIMDUTF_IMPLEMENTATION_HASWELL
+
+#define SIMDUTF_TARGET_HASWELL SIMDUTF_TARGET_REGION("avx2,bmi,pclmul,lzcnt")
+
+namespace simdutf {
+/**
+ * Implementation for Haswell (Intel AVX2).
+ */
+namespace haswell {
+} // namespace haswell
+} // namespace simdutf
+
+//
+// These two need to be included outside SIMDUTF_TARGET_REGION
+//
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/implementation.h
+/* begin file src/simdutf/haswell/implementation.h */
+#ifndef SIMDUTF_HASWELL_IMPLEMENTATION_H
+#define SIMDUTF_HASWELL_IMPLEMENTATION_H
+
+
+// The constructor may be executed on any host, so we take care not to use SIMDUTF_TARGET_REGION
+namespace simdutf {
+namespace haswell {
+
+using namespace simdutf;
+
+class implementation final : public simdutf::implementation {
+public:
+  simdutf_really_inline implementation() : simdutf::implementation(
+      "haswell",
+      "Intel/AMD AVX2",
+      internal::instruction_set::AVX2 | internal::instruction_set::PCLMULQDQ | internal::instruction_set::BMI1 | internal::instruction_set::BMI2
+  ) {}
+  simdutf_warn_unused int detect_encodings(const char * input, size_t length) const noexcept final;
+  simdutf_warn_unused bool validate_utf8(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf8_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_ascii(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_ascii_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16le(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16be(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf32(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  void change_endianness_utf16(const char16_t * buf, size_t length, char16_t * output) const noexcept final;
+  simdutf_warn_unused size_t count_utf16le(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf16be(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf8(const char * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf8(const char * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf8(const char * input, size_t length) const noexcept;
+};
+
+} // namespace haswell
+} // namespace simdutf
+
+#endif // SIMDUTF_HASWELL_IMPLEMENTATION_H
+/* end file src/simdutf/haswell/implementation.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/intrinsics.h
+/* begin file src/simdutf/haswell/intrinsics.h */
+#ifndef SIMDUTF_HASWELL_INTRINSICS_H
+#define SIMDUTF_HASWELL_INTRINSICS_H
+
+
+#ifdef SIMDUTF_VISUAL_STUDIO
+// under clang within visual studio, this will include <x86intrin.h>
+#include <intrin.h>  // visual studio or clang
+#else
+#include <x86intrin.h> // elsewhere
+#endif // SIMDUTF_VISUAL_STUDIO
+
+#ifdef SIMDUTF_CLANG_VISUAL_STUDIO
+/**
+ * You are not supposed, normally, to include these
+ * headers directly. Instead you should either include intrin.h
+ * or x86intrin.h. However, when compiling with clang
+ * under Windows (i.e., when _MSC_VER is set), these headers
+ * only get included *if* the corresponding features are detected
+ * from macros:
+ * e.g., if __AVX2__ is set... in turn,  we normally set these
+ * macros by compiling against the corresponding architecture
+ * (e.g., arch:AVX2, -mavx2, etc.) which compiles the whole
+ * software with these advanced instructions. In simdutf, we
+ * want to compile the whole program for a generic target,
+ * and only target our specific kernels. As a workaround,
+ * we directly include the needed headers. These headers would
+ * normally guard against such usage, but we carefully included
+ * <x86intrin.h>  (or <intrin.h>) before, so the headers
+ * are fooled.
+ */
+#include <bmiintrin.h>   // for _blsr_u64
+#include <lzcntintrin.h> // for  __lzcnt64
+#include <immintrin.h>   // for most things (AVX2, AVX512, _popcnt64)
+#include <smmintrin.h>
+#include <tmmintrin.h>
+#include <avxintrin.h>
+#include <avx2intrin.h>
+#include <wmmintrin.h>   // for  _mm_clmulepi64_si128
+// unfortunately, we may not get _blsr_u64, but, thankfully, clang
+// has it as a macro.
+#ifndef _blsr_u64
+// we roll our own
+#define _blsr_u64(n) ((n - 1) & n)
+#endif //  _blsr_u64
+#endif // SIMDUTF_CLANG_VISUAL_STUDIO
+
+#endif // SIMDUTF_HASWELL_INTRINSICS_H
+/* end file src/simdutf/haswell/intrinsics.h */
+
+//
+// The rest need to be inside the region
+//
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/begin.h
+/* begin file src/simdutf/haswell/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "haswell"
+// #define SIMDUTF_IMPLEMENTATION haswell
+SIMDUTF_TARGET_HASWELL
+/* end file src/simdutf/haswell/begin.h */
+// Declarations
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/bitmanipulation.h
+/* begin file src/simdutf/haswell/bitmanipulation.h */
+#ifndef SIMDUTF_HASWELL_BITMANIPULATION_H
+#define SIMDUTF_HASWELL_BITMANIPULATION_H
+
+namespace simdutf {
+namespace haswell {
+namespace {
+
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+simdutf_really_inline unsigned __int64 count_ones(uint64_t input_num) {
+  // note: we do not support legacy 32-bit Windows
+  return __popcnt64(input_num);// Visual Studio wants two underscores
+}
+#else
+simdutf_really_inline long long int count_ones(uint64_t input_num) {
+  return _popcnt64(input_num);
+}
+#endif
+
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+
+#endif // SIMDUTF_HASWELL_BITMANIPULATION_H
+/* end file src/simdutf/haswell/bitmanipulation.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/simd.h
+/* begin file src/simdutf/haswell/simd.h */
+#ifndef SIMDUTF_HASWELL_SIMD_H
+#define SIMDUTF_HASWELL_SIMD_H
+
+
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace simd {
+
+  // Forward-declared so they can be used by splat and friends.
+  template<typename Child>
+  struct base {
+    __m256i value;
+
+    // Zero constructor
+    simdutf_really_inline base() : value{__m256i()} {}
+
+    // Conversion from SIMD register
+    simdutf_really_inline base(const __m256i _value) : value(_value) {}
+    // Conversion to SIMD register
+    simdutf_really_inline operator const __m256i&() const { return this->value; }
+    simdutf_really_inline operator __m256i&() { return this->value; }
+    template <endianness big_endian>
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * ptr) const {
+      __m256i first = _mm256_cvtepu8_epi16(_mm256_castsi256_si128(*this));
+      __m256i second = _mm256_cvtepu8_epi16(_mm256_extractf128_si256(*this,1));
+      if (big_endian) {
+        const __m256i swap = _mm256_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14,
+                                  17, 16, 19, 18, 21, 20, 23, 22, 25, 24, 27, 26, 29, 28, 31, 30);
+        first = _mm256_shuffle_epi8(first, swap);
+        second = _mm256_shuffle_epi8(second, swap);
+      }
+      _mm256_storeu_si256(reinterpret_cast<__m256i *>(ptr), first);
+      _mm256_storeu_si256(reinterpret_cast<__m256i *>(ptr + 16), second);
+    }
+    simdutf_really_inline void store_ascii_as_utf32(char32_t * ptr) const {
+      _mm256_storeu_si256(reinterpret_cast<__m256i *>(ptr), _mm256_cvtepu8_epi32(_mm256_castsi256_si128(*this)));
+      _mm256_storeu_si256(reinterpret_cast<__m256i *>(ptr+8), _mm256_cvtepu8_epi32(_mm256_castsi256_si128(_mm256_srli_si256(*this,8))));
+      _mm256_storeu_si256(reinterpret_cast<__m256i *>(ptr + 16), _mm256_cvtepu8_epi32(_mm256_extractf128_si256(*this,1)));
+      _mm256_storeu_si256(reinterpret_cast<__m256i *>(ptr + 24), _mm256_cvtepu8_epi32(_mm_srli_si128(_mm256_extractf128_si256(*this,1),8)));
+    }
+    // Bit operations
+    simdutf_really_inline Child operator|(const Child other) const { return _mm256_or_si256(*this, other); }
+    simdutf_really_inline Child operator&(const Child other) const { return _mm256_and_si256(*this, other); }
+    simdutf_really_inline Child operator^(const Child other) const { return _mm256_xor_si256(*this, other); }
+    simdutf_really_inline Child bit_andnot(const Child other) const { return _mm256_andnot_si256(other, *this); }
+    simdutf_really_inline Child& operator|=(const Child other) { auto this_cast = static_cast<Child*>(this); *this_cast = *this_cast | other; return *this_cast; }
+    simdutf_really_inline Child& operator&=(const Child other) { auto this_cast = static_cast<Child*>(this); *this_cast = *this_cast & other; return *this_cast; }
+    simdutf_really_inline Child& operator^=(const Child other) { auto this_cast = static_cast<Child*>(this); *this_cast = *this_cast ^ other; return *this_cast; }
+  };
+
+  // Forward-declared so they can be used by splat and friends.
+  template<typename T>
+  struct simd8;
+
+  template<typename T, typename Mask=simd8<bool>>
+  struct base8: base<simd8<T>> {
+    typedef uint32_t bitmask_t;
+    typedef uint64_t bitmask2_t;
+
+    simdutf_really_inline base8() : base<simd8<T>>() {}
+    simdutf_really_inline base8(const __m256i _value) : base<simd8<T>>(_value) {}
+    simdutf_really_inline T first() const { return _mm256_extract_epi8(*this,0); }
+    simdutf_really_inline T last() const { return _mm256_extract_epi8(*this,31); }
+    simdutf_really_inline Mask operator==(const simd8<T> other) const { return _mm256_cmpeq_epi8(*this, other); }
+
+    static const int SIZE = sizeof(base<T>::value);
+
+    template<int N=1>
+    simdutf_really_inline simd8<T> prev(const simd8<T> prev_chunk) const {
+      return _mm256_alignr_epi8(*this, _mm256_permute2x128_si256(prev_chunk, *this, 0x21), 16 - N);
+    }
+  };
+
+  // SIMD byte mask type (returned by things like eq and gt)
+  template<>
+  struct simd8<bool>: base8<bool> {
+    static simdutf_really_inline simd8<bool> splat(bool _value) { return _mm256_set1_epi8(uint8_t(-(!!_value))); }
+
+    simdutf_really_inline simd8<bool>() : base8() {}
+    simdutf_really_inline simd8<bool>(const __m256i _value) : base8<bool>(_value) {}
+    // Splat constructor
+    simdutf_really_inline simd8<bool>(bool _value) : base8<bool>(splat(_value)) {}
+
+    simdutf_really_inline uint32_t to_bitmask() const { return uint32_t(_mm256_movemask_epi8(*this)); }
+    simdutf_really_inline bool any() const { return !_mm256_testz_si256(*this, *this); }
+    simdutf_really_inline bool none() const { return _mm256_testz_si256(*this, *this); }
+    simdutf_really_inline bool all() const { return static_cast<uint32_t>(_mm256_movemask_epi8(*this)) == 0xFFFFFFFF; }
+    simdutf_really_inline simd8<bool> operator~() const { return *this ^ true; }
+  };
+
+  template<typename T>
+  struct base8_numeric: base8<T> {
+    static simdutf_really_inline simd8<T> splat(T _value) { return _mm256_set1_epi8(_value); }
+    static simdutf_really_inline simd8<T> zero() { return _mm256_setzero_si256(); }
+    static simdutf_really_inline simd8<T> load(const T values[32]) {
+      return _mm256_loadu_si256(reinterpret_cast<const __m256i *>(values));
+    }
+    // Repeat 16 values as many times as necessary (usually for lookup tables)
+    static simdutf_really_inline simd8<T> repeat_16(
+      T v0,  T v1,  T v2,  T v3,  T v4,  T v5,  T v6,  T v7,
+      T v8,  T v9,  T v10, T v11, T v12, T v13, T v14, T v15
+    ) {
+      return simd8<T>(
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15,
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15
+      );
+    }
+
+    simdutf_really_inline base8_numeric() : base8<T>() {}
+    simdutf_really_inline base8_numeric(const __m256i _value) : base8<T>(_value) {}
+
+    // Store to array
+    simdutf_really_inline void store(T dst[32]) const { return _mm256_storeu_si256(reinterpret_cast<__m256i *>(dst), *this); }
+
+    // Addition/subtraction are the same for signed and unsigned
+    simdutf_really_inline simd8<T> operator+(const simd8<T> other) const { return _mm256_add_epi8(*this, other); }
+    simdutf_really_inline simd8<T> operator-(const simd8<T> other) const { return _mm256_sub_epi8(*this, other); }
+    simdutf_really_inline simd8<T>& operator+=(const simd8<T> other) { *this = *this + other; return *static_cast<simd8<T>*>(this); }
+    simdutf_really_inline simd8<T>& operator-=(const simd8<T> other) { *this = *this - other; return *static_cast<simd8<T>*>(this); }
+
+    // Override to distinguish from bool version
+    simdutf_really_inline simd8<T> operator~() const { return *this ^ 0xFFu; }
+
+    // Perform a lookup assuming the value is between 0 and 16 (undefined behavior for out of range values)
+    template<typename L>
+    simdutf_really_inline simd8<L> lookup_16(simd8<L> lookup_table) const {
+      return _mm256_shuffle_epi8(lookup_table, *this);
+    }
+
+    template<typename L>
+    simdutf_really_inline simd8<L> lookup_16(
+        L replace0,  L replace1,  L replace2,  L replace3,
+        L replace4,  L replace5,  L replace6,  L replace7,
+        L replace8,  L replace9,  L replace10, L replace11,
+        L replace12, L replace13, L replace14, L replace15) const {
+      return lookup_16(simd8<L>::repeat_16(
+        replace0,  replace1,  replace2,  replace3,
+        replace4,  replace5,  replace6,  replace7,
+        replace8,  replace9,  replace10, replace11,
+        replace12, replace13, replace14, replace15
+      ));
+    }
+  };
+
+
+  // Signed bytes
+  template<>
+  struct simd8<int8_t> : base8_numeric<int8_t> {
+    simdutf_really_inline simd8() : base8_numeric<int8_t>() {}
+    simdutf_really_inline simd8(const __m256i _value) : base8_numeric<int8_t>(_value) {}
+
+    // Splat constructor
+    simdutf_really_inline simd8(int8_t _value) : simd8(splat(_value)) {}
+    // Array constructor
+    simdutf_really_inline simd8(const int8_t values[32]) : simd8(load(values)) {}
+    simdutf_really_inline operator simd8<uint8_t>() const;
+    // Member-by-member initialization
+    simdutf_really_inline simd8(
+      int8_t v0,  int8_t v1,  int8_t v2,  int8_t v3,  int8_t v4,  int8_t v5,  int8_t v6,  int8_t v7,
+      int8_t v8,  int8_t v9,  int8_t v10, int8_t v11, int8_t v12, int8_t v13, int8_t v14, int8_t v15,
+      int8_t v16, int8_t v17, int8_t v18, int8_t v19, int8_t v20, int8_t v21, int8_t v22, int8_t v23,
+      int8_t v24, int8_t v25, int8_t v26, int8_t v27, int8_t v28, int8_t v29, int8_t v30, int8_t v31
+    ) : simd8(_mm256_setr_epi8(
+      v0, v1, v2, v3, v4, v5, v6, v7,
+      v8, v9, v10,v11,v12,v13,v14,v15,
+      v16,v17,v18,v19,v20,v21,v22,v23,
+      v24,v25,v26,v27,v28,v29,v30,v31
+    )) {}
+    // Repeat 16 values as many times as necessary (usually for lookup tables)
+    simdutf_really_inline static simd8<int8_t> repeat_16(
+      int8_t v0,  int8_t v1,  int8_t v2,  int8_t v3,  int8_t v4,  int8_t v5,  int8_t v6,  int8_t v7,
+      int8_t v8,  int8_t v9,  int8_t v10, int8_t v11, int8_t v12, int8_t v13, int8_t v14, int8_t v15
+    ) {
+      return simd8<int8_t>(
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15,
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15
+      );
+    }
+    simdutf_really_inline bool is_ascii() const { return _mm256_movemask_epi8(*this) == 0; }
+    // Order-sensitive comparisons
+    simdutf_really_inline simd8<int8_t> max_val(const simd8<int8_t> other) const { return _mm256_max_epi8(*this, other); }
+    simdutf_really_inline simd8<int8_t> min_val(const simd8<int8_t> other) const { return _mm256_min_epi8(*this, other); }
+    simdutf_really_inline simd8<bool> operator>(const simd8<int8_t> other) const { return _mm256_cmpgt_epi8(*this, other); }
+    simdutf_really_inline simd8<bool> operator<(const simd8<int8_t> other) const { return _mm256_cmpgt_epi8(other, *this); }
+  };
+
+  // Unsigned bytes
+  template<>
+  struct simd8<uint8_t>: base8_numeric<uint8_t> {
+    simdutf_really_inline simd8() : base8_numeric<uint8_t>() {}
+    simdutf_really_inline simd8(const __m256i _value) : base8_numeric<uint8_t>(_value) {}
+    // Splat constructor
+    simdutf_really_inline simd8(uint8_t _value) : simd8(splat(_value)) {}
+    // Array constructor
+    simdutf_really_inline simd8(const uint8_t values[32]) : simd8(load(values)) {}
+    // Member-by-member initialization
+    simdutf_really_inline simd8(
+      uint8_t v0,  uint8_t v1,  uint8_t v2,  uint8_t v3,  uint8_t v4,  uint8_t v5,  uint8_t v6,  uint8_t v7,
+      uint8_t v8,  uint8_t v9,  uint8_t v10, uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14, uint8_t v15,
+      uint8_t v16, uint8_t v17, uint8_t v18, uint8_t v19, uint8_t v20, uint8_t v21, uint8_t v22, uint8_t v23,
+      uint8_t v24, uint8_t v25, uint8_t v26, uint8_t v27, uint8_t v28, uint8_t v29, uint8_t v30, uint8_t v31
+    ) : simd8(_mm256_setr_epi8(
+      v0, v1, v2, v3, v4, v5, v6, v7,
+      v8, v9, v10,v11,v12,v13,v14,v15,
+      v16,v17,v18,v19,v20,v21,v22,v23,
+      v24,v25,v26,v27,v28,v29,v30,v31
+    )) {}
+    // Repeat 16 values as many times as necessary (usually for lookup tables)
+    simdutf_really_inline static simd8<uint8_t> repeat_16(
+      uint8_t v0,  uint8_t v1,  uint8_t v2,  uint8_t v3,  uint8_t v4,  uint8_t v5,  uint8_t v6,  uint8_t v7,
+      uint8_t v8,  uint8_t v9,  uint8_t v10, uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14, uint8_t v15
+    ) {
+      return simd8<uint8_t>(
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15,
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15
+      );
+    }
+
+
+    // Saturated math
+    simdutf_really_inline simd8<uint8_t> saturating_add(const simd8<uint8_t> other) const { return _mm256_adds_epu8(*this, other); }
+    simdutf_really_inline simd8<uint8_t> saturating_sub(const simd8<uint8_t> other) const { return _mm256_subs_epu8(*this, other); }
+
+    // Order-specific operations
+    simdutf_really_inline simd8<uint8_t> max_val(const simd8<uint8_t> other) const { return _mm256_max_epu8(*this, other); }
+    simdutf_really_inline simd8<uint8_t> min_val(const simd8<uint8_t> other) const { return _mm256_min_epu8(other, *this); }
+    // Same as >, but only guarantees true is nonzero (< guarantees true = -1)
+    simdutf_really_inline simd8<uint8_t> gt_bits(const simd8<uint8_t> other) const { return this->saturating_sub(other); }
+    // Same as <, but only guarantees true is nonzero (< guarantees true = -1)
+    simdutf_really_inline simd8<uint8_t> lt_bits(const simd8<uint8_t> other) const { return other.saturating_sub(*this); }
+    simdutf_really_inline simd8<bool> operator<=(const simd8<uint8_t> other) const { return other.max_val(*this) == other; }
+    simdutf_really_inline simd8<bool> operator>=(const simd8<uint8_t> other) const { return other.min_val(*this) == other; }
+    simdutf_really_inline simd8<bool> operator>(const simd8<uint8_t> other) const { return this->gt_bits(other).any_bits_set(); }
+    simdutf_really_inline simd8<bool> operator<(const simd8<uint8_t> other) const { return this->lt_bits(other).any_bits_set(); }
+
+    // Bit-specific operations
+    simdutf_really_inline simd8<bool> bits_not_set() const { return *this == uint8_t(0); }
+    simdutf_really_inline simd8<bool> bits_not_set(simd8<uint8_t> bits) const { return (*this & bits).bits_not_set(); }
+    simdutf_really_inline simd8<bool> any_bits_set() const { return ~this->bits_not_set(); }
+    simdutf_really_inline simd8<bool> any_bits_set(simd8<uint8_t> bits) const { return ~this->bits_not_set(bits); }
+    simdutf_really_inline bool is_ascii() const { return _mm256_movemask_epi8(*this) == 0; }
+    simdutf_really_inline bool bits_not_set_anywhere() const { return _mm256_testz_si256(*this, *this); }
+    simdutf_really_inline bool any_bits_set_anywhere() const { return !bits_not_set_anywhere(); }
+    simdutf_really_inline bool bits_not_set_anywhere(simd8<uint8_t> bits) const { return _mm256_testz_si256(*this, bits); }
+    simdutf_really_inline bool any_bits_set_anywhere(simd8<uint8_t> bits) const { return !bits_not_set_anywhere(bits); }
+    template<int N>
+    simdutf_really_inline simd8<uint8_t> shr() const { return simd8<uint8_t>(_mm256_srli_epi16(*this, N)) & uint8_t(0xFFu >> N); }
+    template<int N>
+    simdutf_really_inline simd8<uint8_t> shl() const { return simd8<uint8_t>(_mm256_slli_epi16(*this, N)) & uint8_t(0xFFu << N); }
+    // Get one of the bits and make a bitmask out of it.
+    // e.g. value.get_bit<7>() gets the high bit
+    template<int N>
+    simdutf_really_inline int get_bit() const { return _mm256_movemask_epi8(_mm256_slli_epi16(*this, 7-N)); }
+  };
+  simdutf_really_inline simd8<int8_t>::operator simd8<uint8_t>() const { return this->value; }
+
+
+  template<typename T>
+  struct simd8x64 {
+    static constexpr int NUM_CHUNKS = 64 / sizeof(simd8<T>);
+    static_assert(NUM_CHUNKS == 2, "Haswell kernel should use two registers per 64-byte block.");
+    simd8<T> chunks[NUM_CHUNKS];
+
+    simd8x64(const simd8x64<T>& o) = delete; // no copy allowed
+    simd8x64<T>& operator=(const simd8<T> other) = delete; // no assignment allowed
+    simd8x64() = delete; // no default constructor allowed
+
+    simdutf_really_inline simd8x64(const simd8<T> chunk0, const simd8<T> chunk1) : chunks{chunk0, chunk1} {}
+    simdutf_really_inline simd8x64(const T* ptr) : chunks{simd8<T>::load(ptr), simd8<T>::load(ptr+sizeof(simd8<T>)/sizeof(T))} {}
+
+    simdutf_really_inline void store(T* ptr) const {
+      this->chunks[0].store(ptr+sizeof(simd8<T>)*0/sizeof(T));
+      this->chunks[1].store(ptr+sizeof(simd8<T>)*1/sizeof(T));
+    }
+
+    simdutf_really_inline uint64_t to_bitmask() const {
+      uint64_t r_lo = uint32_t(this->chunks[0].to_bitmask());
+      uint64_t r_hi =                       this->chunks[1].to_bitmask();
+      return r_lo | (r_hi << 32);
+    }
+
+    simdutf_really_inline simd8x64<T>& operator|=(const simd8x64<T> &other) {
+      this->chunks[0] |= other.chunks[0];
+      this->chunks[1] |= other.chunks[1];
+      return *this;
+    }
+
+    simdutf_really_inline simd8<T> reduce_or() const {
+      return this->chunks[0] | this->chunks[1];
+    }
+
+    simdutf_really_inline bool is_ascii() const {
+      return this->reduce_or().is_ascii();
+    }
+
+    template <endianness endian>
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * ptr) const {
+      this->chunks[0].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*0);
+      this->chunks[1].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*1);
+    }
+
+    simdutf_really_inline void store_ascii_as_utf32(char32_t * ptr) const {
+      this->chunks[0].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*0);
+      this->chunks[1].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*1);
+    }
+
+    simdutf_really_inline simd8x64<T> bit_or(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return simd8x64<T>(
+        this->chunks[0] | mask,
+        this->chunks[1] | mask
+      );
+    }
+
+    simdutf_really_inline uint64_t eq(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] == mask,
+        this->chunks[1] == mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t eq(const simd8x64<uint8_t> &other) const {
+      return  simd8x64<bool>(
+        this->chunks[0] == other.chunks[0],
+        this->chunks[1] == other.chunks[1]
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t lteq(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] <= mask,
+        this->chunks[1] <= mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t in_range(const T low, const T high) const {
+      const simd8<T> mask_low = simd8<T>::splat(low);
+      const simd8<T> mask_high = simd8<T>::splat(high);
+
+      return  simd8x64<bool>(
+        (this->chunks[0] <= mask_high) & (this->chunks[0] >= mask_low),
+        (this->chunks[1] <= mask_high) & (this->chunks[1] >= mask_low),
+        (this->chunks[2] <= mask_high) & (this->chunks[2] >= mask_low),
+        (this->chunks[3] <= mask_high) & (this->chunks[3] >= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t not_in_range(const T low, const T high) const {
+      const simd8<T> mask_low = simd8<T>::splat(low);
+      const simd8<T> mask_high = simd8<T>::splat(high);
+      return  simd8x64<bool>(
+        (this->chunks[0] > mask_high) | (this->chunks[0] < mask_low),
+        (this->chunks[1] > mask_high) | (this->chunks[1] < mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t lt(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] < mask,
+        this->chunks[1] < mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t gt(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] > mask,
+        this->chunks[1] > mask
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t gteq(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] >= mask,
+        this->chunks[1] >= mask
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t gteq_unsigned(const uint8_t m) const {
+      const simd8<uint8_t> mask = simd8<uint8_t>::splat(m);
+      return  simd8x64<bool>(
+        (simd8<uint8_t>(__m256i(this->chunks[0])) >= mask),
+        (simd8<uint8_t>(__m256i(this->chunks[1])) >= mask)
+      ).to_bitmask();
+    }
+  }; // struct simd8x64<T>
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/simd16-inl.h
+/* begin file src/simdutf/haswell/simd16-inl.h */
+#ifdef __GNUC__
+#if __GNUC__ < 8
+#define _mm256_set_m128i(xmm1, xmm2) _mm256_permute2f128_si256(_mm256_castsi128_si256(xmm1), _mm256_castsi128_si256(xmm2), 2)
+#define _mm256_setr_m128i(xmm2, xmm1)  _mm256_permute2f128_si256(_mm256_castsi128_si256(xmm1), _mm256_castsi128_si256(xmm2), 2)
+#endif
+#endif
+
+template<typename T>
+struct simd16;
+
+template<typename T, typename Mask=simd16<bool>>
+struct base16: base<simd16<T>> {
+  using bitmask_type = uint32_t;
+
+  simdutf_really_inline base16() : base<simd16<T>>() {}
+  simdutf_really_inline base16(const __m256i _value) : base<simd16<T>>(_value) {}
+  template <typename Pointer>
+  simdutf_really_inline base16(const Pointer* ptr) : base16(_mm256_loadu_si256(reinterpret_cast<const __m256i*>(ptr))) {}
+
+  simdutf_really_inline Mask operator==(const simd16<T> other) const { return _mm256_cmpeq_epi16(*this, other); }
+
+  /// the size of vector in bytes
+  static const int SIZE = sizeof(base<simd16<T>>::value);
+
+  /// the number of elements of type T a vector can hold
+  static const int ELEMENTS = SIZE / sizeof(T);
+
+  template<int N=1>
+  simdutf_really_inline simd16<T> prev(const simd16<T> prev_chunk) const {
+    return _mm256_alignr_epi8(*this, prev_chunk, 16 - N);
+  }
+};
+
+// SIMD byte mask type (returned by things like eq and gt)
+template<>
+struct simd16<bool>: base16<bool> {
+  static simdutf_really_inline simd16<bool> splat(bool _value) { return _mm256_set1_epi16(uint16_t(-(!!_value))); }
+
+  simdutf_really_inline simd16<bool>() : base16() {}
+  simdutf_really_inline simd16<bool>(const __m256i _value) : base16<bool>(_value) {}
+  // Splat constructor
+  simdutf_really_inline simd16<bool>(bool _value) : base16<bool>(splat(_value)) {}
+
+  simdutf_really_inline bitmask_type to_bitmask() const { return _mm256_movemask_epi8(*this); }
+  simdutf_really_inline bool any() const { return !_mm256_testz_si256(*this, *this); }
+  simdutf_really_inline simd16<bool> operator~() const { return *this ^ true; }
+};
+
+template<typename T>
+struct base16_numeric: base16<T> {
+  static simdutf_really_inline simd16<T> splat(T _value) { return _mm256_set1_epi16(_value); }
+  static simdutf_really_inline simd16<T> zero() { return _mm256_setzero_si256(); }
+  static simdutf_really_inline simd16<T> load(const T values[8]) {
+    return _mm256_loadu_si256(reinterpret_cast<const __m256i *>(values));
+  }
+
+  simdutf_really_inline base16_numeric() : base16<T>() {}
+  simdutf_really_inline base16_numeric(const __m256i _value) : base16<T>(_value) {}
+
+  // Store to array
+  simdutf_really_inline void store(T dst[8]) const { return _mm256_storeu_si256(reinterpret_cast<__m256i *>(dst), *this); }
+
+  // Override to distinguish from bool version
+  simdutf_really_inline simd16<T> operator~() const { return *this ^ 0xFFFFu; }
+
+  // Addition/subtraction are the same for signed and unsigned
+  simdutf_really_inline simd16<T> operator+(const simd16<T> other) const { return _mm256_add_epi16(*this, other); }
+  simdutf_really_inline simd16<T> operator-(const simd16<T> other) const { return _mm256_sub_epi16(*this, other); }
+  simdutf_really_inline simd16<T>& operator+=(const simd16<T> other) { *this = *this + other; return *static_cast<simd16<T>*>(this); }
+  simdutf_really_inline simd16<T>& operator-=(const simd16<T> other) { *this = *this - other; return *static_cast<simd16<T>*>(this); }
+};
+
+// Signed words
+template<>
+struct simd16<int16_t> : base16_numeric<int16_t> {
+  simdutf_really_inline simd16() : base16_numeric<int16_t>() {}
+  simdutf_really_inline simd16(const __m256i _value) : base16_numeric<int16_t>(_value) {}
+  // Splat constructor
+  simdutf_really_inline simd16(int16_t _value) : simd16(splat(_value)) {}
+  // Array constructor
+  simdutf_really_inline simd16(const int16_t* values) : simd16(load(values)) {}
+  simdutf_really_inline simd16(const char16_t* values) : simd16(load(reinterpret_cast<const int16_t*>(values))) {}
+  // Order-sensitive comparisons
+  simdutf_really_inline simd16<int16_t> max_val(const simd16<int16_t> other) const { return _mm256_max_epi16(*this, other); }
+  simdutf_really_inline simd16<int16_t> min_val(const simd16<int16_t> other) const { return _mm256_min_epi16(*this, other); }
+  simdutf_really_inline simd16<bool> operator>(const simd16<int16_t> other) const { return _mm256_cmpgt_epi16(*this, other); }
+  simdutf_really_inline simd16<bool> operator<(const simd16<int16_t> other) const { return _mm256_cmpgt_epi16(other, *this); }
+};
+
+// Unsigned words
+template<>
+struct simd16<uint16_t>: base16_numeric<uint16_t>  {
+  simdutf_really_inline simd16() : base16_numeric<uint16_t>() {}
+  simdutf_really_inline simd16(const __m256i _value) : base16_numeric<uint16_t>(_value) {}
+
+  // Splat constructor
+  simdutf_really_inline simd16(uint16_t _value) : simd16(splat(_value)) {}
+  // Array constructor
+  simdutf_really_inline simd16(const uint16_t* values) : simd16(load(values)) {}
+  simdutf_really_inline simd16(const char16_t* values) : simd16(load(reinterpret_cast<const uint16_t*>(values))) {}
+
+  // Saturated math
+  simdutf_really_inline simd16<uint16_t> saturating_add(const simd16<uint16_t> other) const { return _mm256_adds_epu16(*this, other); }
+  simdutf_really_inline simd16<uint16_t> saturating_sub(const simd16<uint16_t> other) const { return _mm256_subs_epu16(*this, other); }
+
+  // Order-specific operations
+  simdutf_really_inline simd16<uint16_t> max_val(const simd16<uint16_t> other) const { return _mm256_max_epu16(*this, other); }
+  simdutf_really_inline simd16<uint16_t> min_val(const simd16<uint16_t> other) const { return _mm256_min_epu16(*this, other); }
+  // Same as >, but only guarantees true is nonzero (< guarantees true = -1)
+  simdutf_really_inline simd16<uint16_t> gt_bits(const simd16<uint16_t> other) const { return this->saturating_sub(other); }
+  // Same as <, but only guarantees true is nonzero (< guarantees true = -1)
+  simdutf_really_inline simd16<uint16_t> lt_bits(const simd16<uint16_t> other) const { return other.saturating_sub(*this); }
+  simdutf_really_inline simd16<bool> operator<=(const simd16<uint16_t> other) const { return other.max_val(*this) == other; }
+  simdutf_really_inline simd16<bool> operator>=(const simd16<uint16_t> other) const { return other.min_val(*this) == other; }
+  simdutf_really_inline simd16<bool> operator>(const simd16<uint16_t> other) const { return this->gt_bits(other).any_bits_set(); }
+  simdutf_really_inline simd16<bool> operator<(const simd16<uint16_t> other) const { return this->gt_bits(other).any_bits_set(); }
+
+  // Bit-specific operations
+  simdutf_really_inline simd16<bool> bits_not_set() const { return *this == uint16_t(0); }
+  simdutf_really_inline simd16<bool> bits_not_set(simd16<uint16_t> bits) const { return (*this & bits).bits_not_set(); }
+  simdutf_really_inline simd16<bool> any_bits_set() const { return ~this->bits_not_set(); }
+  simdutf_really_inline simd16<bool> any_bits_set(simd16<uint16_t> bits) const { return ~this->bits_not_set(bits); }
+
+  simdutf_really_inline bool bits_not_set_anywhere() const { return _mm256_testz_si256(*this, *this); }
+  simdutf_really_inline bool any_bits_set_anywhere() const { return !bits_not_set_anywhere(); }
+  simdutf_really_inline bool bits_not_set_anywhere(simd16<uint16_t> bits) const { return _mm256_testz_si256(*this, bits); }
+  simdutf_really_inline bool any_bits_set_anywhere(simd16<uint16_t> bits) const { return !bits_not_set_anywhere(bits); }
+  template<int N>
+  simdutf_really_inline simd16<uint16_t> shr() const { return simd16<uint16_t>(_mm256_srli_epi16(*this, N)); }
+  template<int N>
+  simdutf_really_inline simd16<uint16_t> shl() const { return simd16<uint16_t>(_mm256_slli_epi16(*this, N)); }
+  // Get one of the bits and make a bitmask out of it.
+  // e.g. value.get_bit<7>() gets the high bit
+  template<int N>
+  simdutf_really_inline int get_bit() const { return _mm256_movemask_epi8(_mm256_slli_epi16(*this, 15-N)); }
+
+  // Change the endianness
+  simdutf_really_inline simd16<uint16_t> swap_bytes() const {
+    const __m256i swap = _mm256_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14,
+                                  17, 16, 19, 18, 21, 20, 23, 22, 25, 24, 27, 26, 29, 28, 31, 30);
+    return _mm256_shuffle_epi8(*this, swap);
+  }
+
+  // Pack with the unsigned saturation two uint16_t words into single uint8_t vector
+  static simdutf_really_inline simd8<uint8_t> pack(const simd16<uint16_t>& v0, const simd16<uint16_t>& v1) {
+    // Note: the AVX2 variant of pack operates on 128-bit lanes, thus
+    //       we have to shuffle lanes in order to produce bytes in the
+    //       correct order.
+
+    // get the 0th lanes
+    const __m128i lo_0 = _mm256_extracti128_si256(v0, 0);
+    const __m128i lo_1 = _mm256_extracti128_si256(v1, 0);
+
+    // get the 1st lanes
+    const __m128i hi_0 = _mm256_extracti128_si256(v0, 1);
+    const __m128i hi_1 = _mm256_extracti128_si256(v1, 1);
+
+    // build new vectors (shuffle lanes)
+    const __m256i t0 = _mm256_set_m128i(lo_1, lo_0);
+    const __m256i t1 = _mm256_set_m128i(hi_1, hi_0);
+
+    // pack words in linear order from v0 and v1
+    return _mm256_packus_epi16(t0, t1);
+  }
+};
+
+
+  template<typename T>
+  struct simd16x32 {
+    static constexpr int NUM_CHUNKS = 64 / sizeof(simd16<T>);
+    static_assert(NUM_CHUNKS == 2, "Haswell kernel should use two registers per 64-byte block.");
+    simd16<T> chunks[NUM_CHUNKS];
+
+    simd16x32(const simd16x32<T>& o) = delete; // no copy allowed
+    simd16x32<T>& operator=(const simd16<T> other) = delete; // no assignment allowed
+    simd16x32() = delete; // no default constructor allowed
+
+    simdutf_really_inline simd16x32(const simd16<T> chunk0, const simd16<T> chunk1) : chunks{chunk0, chunk1} {}
+    simdutf_really_inline simd16x32(const T* ptr) : chunks{simd16<T>::load(ptr), simd16<T>::load(ptr+sizeof(simd16<T>)/sizeof(T))} {}
+
+    simdutf_really_inline void store(T* ptr) const {
+      this->chunks[0].store(ptr+sizeof(simd16<T>)*0/sizeof(T));
+      this->chunks[1].store(ptr+sizeof(simd16<T>)*1/sizeof(T));
+    }
+
+    simdutf_really_inline uint64_t to_bitmask() const {
+      uint64_t r_lo = uint32_t(this->chunks[0].to_bitmask());
+      uint64_t r_hi =                       this->chunks[1].to_bitmask();
+      return r_lo | (r_hi << 32);
+    }
+
+    simdutf_really_inline simd16<T> reduce_or() const {
+      return this->chunks[0] | this->chunks[1];
+    }
+
+    simdutf_really_inline bool is_ascii() const {
+      return this->reduce_or().is_ascii();
+    }
+
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * ptr) const {
+      this->chunks[0].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*0);
+      this->chunks[1].store_ascii_as_utf16(ptr+sizeof(simd16<T>));
+    }
+
+    simdutf_really_inline simd16x32<T> bit_or(const T m) const {
+      const simd16<T> mask = simd16<T>::splat(m);
+      return simd16x32<T>(
+        this->chunks[0] | mask,
+        this->chunks[1] | mask
+      );
+    }
+
+    simdutf_really_inline void swap_bytes() {
+      this->chunks[0] = this->chunks[0].swap_bytes();
+      this->chunks[1] = this->chunks[1].swap_bytes();
+    }
+
+    simdutf_really_inline uint64_t eq(const T m) const {
+      const simd16<T> mask = simd16<T>::splat(m);
+      return  simd16x32<bool>(
+        this->chunks[0] == mask,
+        this->chunks[1] == mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t eq(const simd16x32<uint16_t> &other) const {
+      return  simd16x32<bool>(
+        this->chunks[0] == other.chunks[0],
+        this->chunks[1] == other.chunks[1]
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t lteq(const T m) const {
+      const simd16<T> mask = simd16<T>::splat(m);
+      return  simd16x32<bool>(
+        this->chunks[0] <= mask,
+        this->chunks[1] <= mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t in_range(const T low, const T high) const {
+      const simd16<T> mask_low = simd16<T>::splat(low);
+      const simd16<T> mask_high = simd16<T>::splat(high);
+
+      return  simd16x32<bool>(
+        (this->chunks[0] <= mask_high) & (this->chunks[0] >= mask_low),
+        (this->chunks[1] <= mask_high) & (this->chunks[1] >= mask_low),
+        (this->chunks[2] <= mask_high) & (this->chunks[2] >= mask_low),
+        (this->chunks[3] <= mask_high) & (this->chunks[3] >= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t not_in_range(const T low, const T high) const {
+      const simd16<T> mask_low = simd16<T>::splat(static_cast<T>(low-1));
+      const simd16<T> mask_high = simd16<T>::splat(static_cast<T>(high+1));
+      return simd16x32<bool>(
+        (this->chunks[0] >= mask_high) | (this->chunks[0] <= mask_low),
+        (this->chunks[1] >= mask_high) | (this->chunks[1] <= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t lt(const T m) const {
+      const simd16<T> mask = simd16<T>::splat(m);
+      return  simd16x32<bool>(
+        this->chunks[0] < mask,
+        this->chunks[1] < mask
+      ).to_bitmask();
+    }
+  }; // struct simd16x32<T>
+/* end file src/simdutf/haswell/simd16-inl.h */
+
+} // namespace simd
+
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+
+#endif // SIMDUTF_HASWELL_SIMD_H
+/* end file src/simdutf/haswell/simd.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/end.h
+/* begin file src/simdutf/haswell/end.h */
+SIMDUTF_UNTARGET_REGION
+/* end file src/simdutf/haswell/end.h */
+
+#endif // SIMDUTF_IMPLEMENTATION_HASWELL
+#endif // SIMDUTF_HASWELL_COMMON_H
+/* end file src/simdutf/haswell.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere.h
+/* begin file src/simdutf/westmere.h */
+#ifndef SIMDUTF_WESTMERE_H
+#define SIMDUTF_WESTMERE_H
+
+#ifdef SIMDUTF_FALLBACK_H
+#error "westmere.h must be included before fallback.h"
+#endif
+
+
+// Default Westmere to on if this is x86-64, unless we'll always select Haswell.
+#ifndef SIMDUTF_IMPLEMENTATION_WESTMERE
+//
+// You do not want to set it to (SIMDUTF_IS_X86_64 && !SIMDUTF_REQUIRES_HASWELL)
+// because you want to rely on runtime dispatch!
+//
+#define SIMDUTF_IMPLEMENTATION_WESTMERE (SIMDUTF_IS_X86_64)
+#endif
+#define SIMDUTF_CAN_ALWAYS_RUN_WESTMERE (SIMDUTF_IMPLEMENTATION_WESTMERE && SIMDUTF_IS_X86_64 && __SSE4_2__ && __PCLMUL__)
+
+#if SIMDUTF_IMPLEMENTATION_WESTMERE
+
+#define SIMDUTF_TARGET_WESTMERE SIMDUTF_TARGET_REGION("sse4.2,pclmul")
+
+namespace simdutf {
+/**
+ * Implementation for Westmere (Intel SSE4.2).
+ */
+namespace westmere {
+} // namespace westmere
+} // namespace simdutf
+
+//
+// These two need to be included outside SIMDUTF_TARGET_REGION
+//
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/implementation.h
+/* begin file src/simdutf/westmere/implementation.h */
+#ifndef SIMDUTF_WESTMERE_IMPLEMENTATION_H
+#define SIMDUTF_WESTMERE_IMPLEMENTATION_H
+
+
+// The constructor may be executed on any host, so we take care not to use SIMDUTF_TARGET_REGION
+namespace simdutf {
+namespace westmere {
+
+namespace {
+using namespace simdutf;
+}
+
+class implementation final : public simdutf::implementation {
+public:
+  simdutf_really_inline implementation() : simdutf::implementation("westmere", "Intel/AMD SSE4.2", internal::instruction_set::SSE42 | internal::instruction_set::PCLMULQDQ) {}
+  simdutf_warn_unused int detect_encodings(const char * input, size_t length) const noexcept final;
+  simdutf_warn_unused bool validate_utf8(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf8_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_ascii(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_ascii_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16le(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16be(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf32(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  void change_endianness_utf16(const char16_t * buf, size_t length, char16_t * output) const noexcept final;
+  simdutf_warn_unused size_t count_utf16le(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf16be(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf8(const char * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf8(const char * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf8(const char * input, size_t length) const noexcept;
+};
+
+} // namespace westmere
+} // namespace simdutf
+
+#endif // SIMDUTF_WESTMERE_IMPLEMENTATION_H
+/* end file src/simdutf/westmere/implementation.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/intrinsics.h
+/* begin file src/simdutf/westmere/intrinsics.h */
+#ifndef SIMDUTF_WESTMERE_INTRINSICS_H
+#define SIMDUTF_WESTMERE_INTRINSICS_H
+
+#ifdef SIMDUTF_VISUAL_STUDIO
+// under clang within visual studio, this will include <x86intrin.h>
+#include <intrin.h> // visual studio or clang
+#else
+#include <x86intrin.h> // elsewhere
+#endif // SIMDUTF_VISUAL_STUDIO
+
+
+#ifdef SIMDUTF_CLANG_VISUAL_STUDIO
+/**
+ * You are not supposed, normally, to include these
+ * headers directly. Instead you should either include intrin.h
+ * or x86intrin.h. However, when compiling with clang
+ * under Windows (i.e., when _MSC_VER is set), these headers
+ * only get included *if* the corresponding features are detected
+ * from macros:
+ */
+#include <smmintrin.h>  // for _mm_alignr_epi8
+#include <wmmintrin.h>  // for  _mm_clmulepi64_si128
+#endif
+
+
+
+#endif // SIMDUTF_WESTMERE_INTRINSICS_H
+/* end file src/simdutf/westmere/intrinsics.h */
+
+//
+// The rest need to be inside the region
+//
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/begin.h
+/* begin file src/simdutf/westmere/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "westmere"
+// #define SIMDUTF_IMPLEMENTATION westmere
+SIMDUTF_TARGET_WESTMERE
+/* end file src/simdutf/westmere/begin.h */
+
+// Declarations
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/bitmanipulation.h
+/* begin file src/simdutf/westmere/bitmanipulation.h */
+#ifndef SIMDUTF_WESTMERE_BITMANIPULATION_H
+#define SIMDUTF_WESTMERE_BITMANIPULATION_H
+
+namespace simdutf {
+namespace westmere {
+namespace {
+
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+simdutf_really_inline unsigned __int64 count_ones(uint64_t input_num) {
+  // note: we do not support legacy 32-bit Windows
+  return __popcnt64(input_num);// Visual Studio wants two underscores
+}
+#else
+simdutf_really_inline long long int count_ones(uint64_t input_num) {
+  return _popcnt64(input_num);
+}
+#endif
+
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+
+#endif // SIMDUTF_WESTMERE_BITMANIPULATION_H
+/* end file src/simdutf/westmere/bitmanipulation.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/simd.h
+/* begin file src/simdutf/westmere/simd.h */
+#ifndef SIMDUTF_WESTMERE_SIMD_H
+#define SIMDUTF_WESTMERE_SIMD_H
+
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace simd {
+
+  template<typename Child>
+  struct base {
+    __m128i value;
+
+    // Zero constructor
+    simdutf_really_inline base() : value{__m128i()} {}
+
+    // Conversion from SIMD register
+    simdutf_really_inline base(const __m128i _value) : value(_value) {}
+    // Conversion to SIMD register
+    simdutf_really_inline operator const __m128i&() const { return this->value; }
+    simdutf_really_inline operator __m128i&() { return this->value; }
+    template <endianness big_endian>
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * p) const {
+      __m128i first = _mm_cvtepu8_epi16(*this);
+      __m128i second = _mm_cvtepu8_epi16(_mm_srli_si128(*this,8));
+      if (big_endian) {
+        const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+        first = _mm_shuffle_epi8(first, swap);
+        second = _mm_shuffle_epi8(second, swap);
+      }
+      _mm_storeu_si128(reinterpret_cast<__m128i *>(p), first);
+      _mm_storeu_si128(reinterpret_cast<__m128i *>(p+8), second);
+    }
+    simdutf_really_inline void store_ascii_as_utf32(char32_t * p) const {
+      _mm_storeu_si128(reinterpret_cast<__m128i *>(p), _mm_cvtepu8_epi32(*this));
+      _mm_storeu_si128(reinterpret_cast<__m128i *>(p+4), _mm_cvtepu8_epi32(_mm_srli_si128(*this,4)));
+      _mm_storeu_si128(reinterpret_cast<__m128i *>(p+8), _mm_cvtepu8_epi32(_mm_srli_si128(*this,8)));
+      _mm_storeu_si128(reinterpret_cast<__m128i *>(p+12), _mm_cvtepu8_epi32(_mm_srli_si128(*this,12)));
+    }
+    // Bit operations
+    simdutf_really_inline Child operator|(const Child other) const { return _mm_or_si128(*this, other); }
+    simdutf_really_inline Child operator&(const Child other) const { return _mm_and_si128(*this, other); }
+    simdutf_really_inline Child operator^(const Child other) const { return _mm_xor_si128(*this, other); }
+    simdutf_really_inline Child bit_andnot(const Child other) const { return _mm_andnot_si128(other, *this); }
+    simdutf_really_inline Child& operator|=(const Child other) { auto this_cast = static_cast<Child*>(this); *this_cast = *this_cast | other; return *this_cast; }
+    simdutf_really_inline Child& operator&=(const Child other) { auto this_cast = static_cast<Child*>(this); *this_cast = *this_cast & other; return *this_cast; }
+    simdutf_really_inline Child& operator^=(const Child other) { auto this_cast = static_cast<Child*>(this); *this_cast = *this_cast ^ other; return *this_cast; }
+  };
+
+  // Forward-declared so they can be used by splat and friends.
+  template<typename T>
+  struct simd8;
+
+  template<typename T, typename Mask=simd8<bool>>
+  struct base8: base<simd8<T>> {
+    typedef uint16_t bitmask_t;
+    typedef uint32_t bitmask2_t;
+
+    simdutf_really_inline T first() const { return _mm_extract_epi8(*this,0); }
+    simdutf_really_inline T last() const { return _mm_extract_epi8(*this,15); }
+    simdutf_really_inline base8() : base<simd8<T>>() {}
+    simdutf_really_inline base8(const __m128i _value) : base<simd8<T>>(_value) {}
+
+    simdutf_really_inline Mask operator==(const simd8<T> other) const { return _mm_cmpeq_epi8(*this, other); }
+
+    static const int SIZE = sizeof(base<simd8<T>>::value);
+
+    template<int N=1>
+    simdutf_really_inline simd8<T> prev(const simd8<T> prev_chunk) const {
+      return _mm_alignr_epi8(*this, prev_chunk, 16 - N);
+    }
+  };
+
+  // SIMD byte mask type (returned by things like eq and gt)
+  template<>
+  struct simd8<bool>: base8<bool> {
+    static simdutf_really_inline simd8<bool> splat(bool _value) { return _mm_set1_epi8(uint8_t(-(!!_value))); }
+
+    simdutf_really_inline simd8<bool>() : base8() {}
+    simdutf_really_inline simd8<bool>(const __m128i _value) : base8<bool>(_value) {}
+    // Splat constructor
+    simdutf_really_inline simd8<bool>(bool _value) : base8<bool>(splat(_value)) {}
+
+    simdutf_really_inline int to_bitmask() const { return _mm_movemask_epi8(*this); }
+    simdutf_really_inline bool any() const { return !_mm_testz_si128(*this, *this); }
+    simdutf_really_inline bool none() const { return _mm_testz_si128(*this, *this); }
+    simdutf_really_inline bool all() const { return _mm_movemask_epi8(*this) == 0xFFFF; }
+    simdutf_really_inline simd8<bool> operator~() const { return *this ^ true; }
+  };
+
+  template<typename T>
+  struct base8_numeric: base8<T> {
+    static simdutf_really_inline simd8<T> splat(T _value) { return _mm_set1_epi8(_value); }
+    static simdutf_really_inline simd8<T> zero() { return _mm_setzero_si128(); }
+    static simdutf_really_inline simd8<T> load(const T values[16]) {
+      return _mm_loadu_si128(reinterpret_cast<const __m128i *>(values));
+    }
+    // Repeat 16 values as many times as necessary (usually for lookup tables)
+    static simdutf_really_inline simd8<T> repeat_16(
+      T v0,  T v1,  T v2,  T v3,  T v4,  T v5,  T v6,  T v7,
+      T v8,  T v9,  T v10, T v11, T v12, T v13, T v14, T v15
+    ) {
+      return simd8<T>(
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15
+      );
+    }
+
+    simdutf_really_inline base8_numeric() : base8<T>() {}
+    simdutf_really_inline base8_numeric(const __m128i _value) : base8<T>(_value) {}
+
+    // Store to array
+    simdutf_really_inline void store(T dst[16]) const { return _mm_storeu_si128(reinterpret_cast<__m128i *>(dst), *this); }
+
+    // Override to distinguish from bool version
+    simdutf_really_inline simd8<T> operator~() const { return *this ^ 0xFFu; }
+
+    // Addition/subtraction are the same for signed and unsigned
+    simdutf_really_inline simd8<T> operator+(const simd8<T> other) const { return _mm_add_epi8(*this, other); }
+    simdutf_really_inline simd8<T> operator-(const simd8<T> other) const { return _mm_sub_epi8(*this, other); }
+    simdutf_really_inline simd8<T>& operator+=(const simd8<T> other) { *this = *this + other; return *static_cast<simd8<T>*>(this); }
+    simdutf_really_inline simd8<T>& operator-=(const simd8<T> other) { *this = *this - other; return *static_cast<simd8<T>*>(this); }
+
+    // Perform a lookup assuming the value is between 0 and 16 (undefined behavior for out of range values)
+    template<typename L>
+    simdutf_really_inline simd8<L> lookup_16(simd8<L> lookup_table) const {
+      return _mm_shuffle_epi8(lookup_table, *this);
+    }
+
+    template<typename L>
+    simdutf_really_inline simd8<L> lookup_16(
+        L replace0,  L replace1,  L replace2,  L replace3,
+        L replace4,  L replace5,  L replace6,  L replace7,
+        L replace8,  L replace9,  L replace10, L replace11,
+        L replace12, L replace13, L replace14, L replace15) const {
+      return lookup_16(simd8<L>::repeat_16(
+        replace0,  replace1,  replace2,  replace3,
+        replace4,  replace5,  replace6,  replace7,
+        replace8,  replace9,  replace10, replace11,
+        replace12, replace13, replace14, replace15
+      ));
+    }
+  };
+
+  // Signed bytes
+  template<>
+  struct simd8<int8_t> : base8_numeric<int8_t> {
+    simdutf_really_inline simd8() : base8_numeric<int8_t>() {}
+    simdutf_really_inline simd8(const __m128i _value) : base8_numeric<int8_t>(_value) {}
+    // Splat constructor
+    simdutf_really_inline simd8(int8_t _value) : simd8(splat(_value)) {}
+    // Array constructor
+    simdutf_really_inline simd8(const int8_t* values) : simd8(load(values)) {}
+    // Member-by-member initialization
+    simdutf_really_inline simd8(
+      int8_t v0,  int8_t v1,  int8_t v2,  int8_t v3,  int8_t v4,  int8_t v5,  int8_t v6,  int8_t v7,
+      int8_t v8,  int8_t v9,  int8_t v10, int8_t v11, int8_t v12, int8_t v13, int8_t v14, int8_t v15
+    ) : simd8(_mm_setr_epi8(
+      v0, v1, v2, v3, v4, v5, v6, v7,
+      v8, v9, v10,v11,v12,v13,v14,v15
+    )) {}
+    // Repeat 16 values as many times as necessary (usually for lookup tables)
+    simdutf_really_inline static simd8<int8_t> repeat_16(
+      int8_t v0,  int8_t v1,  int8_t v2,  int8_t v3,  int8_t v4,  int8_t v5,  int8_t v6,  int8_t v7,
+      int8_t v8,  int8_t v9,  int8_t v10, int8_t v11, int8_t v12, int8_t v13, int8_t v14, int8_t v15
+    ) {
+      return simd8<int8_t>(
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15
+      );
+    }
+    simdutf_really_inline operator simd8<uint8_t>() const;
+    simdutf_really_inline bool is_ascii() const { return _mm_movemask_epi8(*this) == 0; }
+
+    // Order-sensitive comparisons
+    simdutf_really_inline simd8<int8_t> max_val(const simd8<int8_t> other) const { return _mm_max_epi8(*this, other); }
+    simdutf_really_inline simd8<int8_t> min_val(const simd8<int8_t> other) const { return _mm_min_epi8(*this, other); }
+    simdutf_really_inline simd8<bool> operator>(const simd8<int8_t> other) const { return _mm_cmpgt_epi8(*this, other); }
+    simdutf_really_inline simd8<bool> operator<(const simd8<int8_t> other) const { return _mm_cmpgt_epi8(other, *this); }
+  };
+
+  // Unsigned bytes
+  template<>
+  struct simd8<uint8_t>: base8_numeric<uint8_t>  {
+    simdutf_really_inline simd8() : base8_numeric<uint8_t>() {}
+    simdutf_really_inline simd8(const __m128i _value) : base8_numeric<uint8_t>(_value) {}
+
+    // Splat constructor
+    simdutf_really_inline simd8(uint8_t _value) : simd8(splat(_value)) {}
+    // Array constructor
+    simdutf_really_inline simd8(const uint8_t* values) : simd8(load(values)) {}
+    // Member-by-member initialization
+    simdutf_really_inline simd8(
+      uint8_t v0,  uint8_t v1,  uint8_t v2,  uint8_t v3,  uint8_t v4,  uint8_t v5,  uint8_t v6,  uint8_t v7,
+      uint8_t v8,  uint8_t v9,  uint8_t v10, uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14, uint8_t v15
+    ) : simd8(_mm_setr_epi8(
+      v0, v1, v2, v3, v4, v5, v6, v7,
+      v8, v9, v10,v11,v12,v13,v14,v15
+    )) {}
+    // Repeat 16 values as many times as necessary (usually for lookup tables)
+    simdutf_really_inline static simd8<uint8_t> repeat_16(
+      uint8_t v0,  uint8_t v1,  uint8_t v2,  uint8_t v3,  uint8_t v4,  uint8_t v5,  uint8_t v6,  uint8_t v7,
+      uint8_t v8,  uint8_t v9,  uint8_t v10, uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14, uint8_t v15
+    ) {
+      return simd8<uint8_t>(
+        v0, v1, v2, v3, v4, v5, v6, v7,
+        v8, v9, v10,v11,v12,v13,v14,v15
+      );
+    }
+
+    // Saturated math
+    simdutf_really_inline simd8<uint8_t> saturating_add(const simd8<uint8_t> other) const { return _mm_adds_epu8(*this, other); }
+    simdutf_really_inline simd8<uint8_t> saturating_sub(const simd8<uint8_t> other) const { return _mm_subs_epu8(*this, other); }
+
+    // Order-specific operations
+    simdutf_really_inline simd8<uint8_t> max_val(const simd8<uint8_t> other) const { return _mm_max_epu8(*this, other); }
+    simdutf_really_inline simd8<uint8_t> min_val(const simd8<uint8_t> other) const { return _mm_min_epu8(*this, other); }
+    // Same as >, but only guarantees true is nonzero (< guarantees true = -1)
+    simdutf_really_inline simd8<uint8_t> gt_bits(const simd8<uint8_t> other) const { return this->saturating_sub(other); }
+    // Same as <, but only guarantees true is nonzero (< guarantees true = -1)
+    simdutf_really_inline simd8<uint8_t> lt_bits(const simd8<uint8_t> other) const { return other.saturating_sub(*this); }
+    simdutf_really_inline simd8<bool> operator<=(const simd8<uint8_t> other) const { return other.max_val(*this) == other; }
+    simdutf_really_inline simd8<bool> operator>=(const simd8<uint8_t> other) const { return other.min_val(*this) == other; }
+    simdutf_really_inline simd8<bool> operator>(const simd8<uint8_t> other) const { return this->gt_bits(other).any_bits_set(); }
+    simdutf_really_inline simd8<bool> operator<(const simd8<uint8_t> other) const { return this->gt_bits(other).any_bits_set(); }
+
+    // Bit-specific operations
+    simdutf_really_inline simd8<bool> bits_not_set() const { return *this == uint8_t(0); }
+    simdutf_really_inline simd8<bool> bits_not_set(simd8<uint8_t> bits) const { return (*this & bits).bits_not_set(); }
+    simdutf_really_inline simd8<bool> any_bits_set() const { return ~this->bits_not_set(); }
+    simdutf_really_inline simd8<bool> any_bits_set(simd8<uint8_t> bits) const { return ~this->bits_not_set(bits); }
+    simdutf_really_inline bool is_ascii() const { return _mm_movemask_epi8(*this) == 0; }
+
+    simdutf_really_inline bool bits_not_set_anywhere() const { return _mm_testz_si128(*this, *this); }
+    simdutf_really_inline bool any_bits_set_anywhere() const { return !bits_not_set_anywhere(); }
+    simdutf_really_inline bool bits_not_set_anywhere(simd8<uint8_t> bits) const { return _mm_testz_si128(*this, bits); }
+    simdutf_really_inline bool any_bits_set_anywhere(simd8<uint8_t> bits) const { return !bits_not_set_anywhere(bits); }
+    template<int N>
+    simdutf_really_inline simd8<uint8_t> shr() const { return simd8<uint8_t>(_mm_srli_epi16(*this, N)) & uint8_t(0xFFu >> N); }
+    template<int N>
+    simdutf_really_inline simd8<uint8_t> shl() const { return simd8<uint8_t>(_mm_slli_epi16(*this, N)) & uint8_t(0xFFu << N); }
+    // Get one of the bits and make a bitmask out of it.
+    // e.g. value.get_bit<7>() gets the high bit
+    template<int N>
+    simdutf_really_inline int get_bit() const { return _mm_movemask_epi8(_mm_slli_epi16(*this, 7-N)); }
+  };
+  simdutf_really_inline simd8<int8_t>::operator simd8<uint8_t>() const { return this->value; }
+
+  // Unsigned bytes
+  template<>
+  struct simd8<uint16_t>: base<uint16_t> {
+    static simdutf_really_inline simd8<uint16_t> splat(uint16_t _value) { return _mm_set1_epi16(_value); }
+    static simdutf_really_inline simd8<uint16_t> load(const uint16_t values[8]) {
+      return _mm_loadu_si128(reinterpret_cast<const __m128i *>(values));
+    }
+
+    simdutf_really_inline simd8() : base<uint16_t>() {}
+    simdutf_really_inline simd8(const __m128i _value) : base<uint16_t>(_value) {}
+    // Splat constructor
+    simdutf_really_inline simd8(uint16_t _value) : simd8(splat(_value)) {}
+    // Array constructor
+    simdutf_really_inline simd8(const uint16_t* values) : simd8(load(values)) {}
+    // Member-by-member initialization
+    simdutf_really_inline simd8(
+      uint16_t v0,  uint16_t v1,  uint16_t v2,  uint16_t v3,  uint16_t v4,  uint16_t v5,  uint16_t v6,  uint16_t v7
+    ) : simd8(_mm_setr_epi16(
+      v0, v1, v2, v3, v4, v5, v6, v7
+    )) {}
+
+    // Saturated math
+    simdutf_really_inline simd8<uint16_t> saturating_add(const simd8<uint16_t> other) const { return _mm_adds_epu16(*this, other); }
+    simdutf_really_inline simd8<uint16_t> saturating_sub(const simd8<uint16_t> other) const { return _mm_subs_epu16(*this, other); }
+
+    // Order-specific operations
+    simdutf_really_inline simd8<uint16_t> max_val(const simd8<uint16_t> other) const { return _mm_max_epu16(*this, other); }
+    simdutf_really_inline simd8<uint16_t> min_val(const simd8<uint16_t> other) const { return _mm_min_epu16(*this, other); }
+    // Same as >, but only guarantees true is nonzero (< guarantees true = -1)
+    simdutf_really_inline simd8<uint16_t> gt_bits(const simd8<uint16_t> other) const { return this->saturating_sub(other); }
+    // Same as <, but only guarantees true is nonzero (< guarantees true = -1)
+    simdutf_really_inline simd8<uint16_t> lt_bits(const simd8<uint16_t> other) const { return other.saturating_sub(*this); }
+    simdutf_really_inline simd8<bool> operator<=(const simd8<uint16_t> other) const { return other.max_val(*this) == other; }
+    simdutf_really_inline simd8<bool> operator>=(const simd8<uint16_t> other) const { return other.min_val(*this) == other; }
+    simdutf_really_inline simd8<bool> operator==(const simd8<uint16_t> other) const { return _mm_cmpeq_epi16(*this, other); }
+    simdutf_really_inline simd8<bool> operator&(const simd8<uint16_t> other) const { return _mm_and_si128(*this, other); }
+    simdutf_really_inline simd8<bool> operator|(const simd8<uint16_t> other) const { return _mm_or_si128(*this, other); }
+
+    // Bit-specific operations
+    simdutf_really_inline simd8<bool> bits_not_set() const { return *this == uint16_t(0); }
+    simdutf_really_inline simd8<bool> any_bits_set() const { return ~this->bits_not_set(); }
+
+    simdutf_really_inline bool bits_not_set_anywhere() const { return _mm_testz_si128(*this, *this); }
+    simdutf_really_inline bool any_bits_set_anywhere() const { return !bits_not_set_anywhere(); }
+    simdutf_really_inline bool bits_not_set_anywhere(simd8<uint16_t> bits) const { return _mm_testz_si128(*this, bits); }
+    simdutf_really_inline bool any_bits_set_anywhere(simd8<uint16_t> bits) const { return !bits_not_set_anywhere(bits); }
+     };
+  template<typename T>
+  struct simd8x64 {
+    static constexpr int NUM_CHUNKS = 64 / sizeof(simd8<T>);
+    static_assert(NUM_CHUNKS == 4, "Westmere kernel should use four registers per 64-byte block.");
+    simd8<T> chunks[NUM_CHUNKS];
+
+    simd8x64(const simd8x64<T>& o) = delete; // no copy allowed
+    simd8x64<T>& operator=(const simd8<T> other) = delete; // no assignment allowed
+    simd8x64() = delete; // no default constructor allowed
+
+    simdutf_really_inline simd8x64(const simd8<T> chunk0, const simd8<T> chunk1, const simd8<T> chunk2, const simd8<T> chunk3) : chunks{chunk0, chunk1, chunk2, chunk3} {}
+    simdutf_really_inline simd8x64(const T* ptr) : chunks{simd8<T>::load(ptr), simd8<T>::load(ptr+sizeof(simd8<T>)/sizeof(T)), simd8<T>::load(ptr+2*sizeof(simd8<T>)/sizeof(T)), simd8<T>::load(ptr+3*sizeof(simd8<T>)/sizeof(T))} {}
+
+    simdutf_really_inline void store(T* ptr) const {
+      this->chunks[0].store(ptr+sizeof(simd8<T>)*0/sizeof(T));
+      this->chunks[1].store(ptr+sizeof(simd8<T>)*1/sizeof(T));
+      this->chunks[2].store(ptr+sizeof(simd8<T>)*2/sizeof(T));
+      this->chunks[3].store(ptr+sizeof(simd8<T>)*3/sizeof(T));
+    }
+
+    simdutf_really_inline simd8x64<T>& operator |=(const simd8x64<T> &other) {
+      this->chunks[0] |= other.chunks[0];
+      this->chunks[1] |= other.chunks[1];
+      this->chunks[2] |= other.chunks[2];
+      this->chunks[3] |= other.chunks[3];
+      return *this;
+    }
+
+    simdutf_really_inline simd8<T> reduce_or() const {
+      return (this->chunks[0] | this->chunks[1]) | (this->chunks[2] | this->chunks[3]);
+    }
+
+    simdutf_really_inline bool is_ascii() const {
+      return this->reduce_or().is_ascii();
+    }
+
+    template <endianness endian>
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * ptr) const {
+      this->chunks[0].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*0);
+      this->chunks[1].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*1);
+      this->chunks[2].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*2);
+      this->chunks[3].template store_ascii_as_utf16<endian>(ptr+sizeof(simd8<T>)*3);
+    }
+
+    simdutf_really_inline void store_ascii_as_utf32(char32_t * ptr) const {
+      this->chunks[0].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*0);
+      this->chunks[1].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*1);
+      this->chunks[2].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*2);
+      this->chunks[3].store_ascii_as_utf32(ptr+sizeof(simd8<T>)*3);
+    }
+
+    simdutf_really_inline uint64_t to_bitmask() const {
+      uint64_t r0 = uint32_t(this->chunks[0].to_bitmask() );
+      uint64_t r1 =          this->chunks[1].to_bitmask() ;
+      uint64_t r2 =          this->chunks[2].to_bitmask() ;
+      uint64_t r3 =          this->chunks[3].to_bitmask() ;
+      return r0 | (r1 << 16) | (r2 << 32) | (r3 << 48);
+    }
+
+    simdutf_really_inline uint64_t eq(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] == mask,
+        this->chunks[1] == mask,
+        this->chunks[2] == mask,
+        this->chunks[3] == mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t eq(const simd8x64<uint8_t> &other) const {
+      return  simd8x64<bool>(
+        this->chunks[0] == other.chunks[0],
+        this->chunks[1] == other.chunks[1],
+        this->chunks[2] == other.chunks[2],
+        this->chunks[3] == other.chunks[3]
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t lteq(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] <= mask,
+        this->chunks[1] <= mask,
+        this->chunks[2] <= mask,
+        this->chunks[3] <= mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t in_range(const T low, const T high) const {
+      const simd8<T> mask_low = simd8<T>::splat(low);
+      const simd8<T> mask_high = simd8<T>::splat(high);
+
+      return  simd8x64<bool>(
+        (this->chunks[0] <= mask_high) & (this->chunks[0] >= mask_low),
+        (this->chunks[1] <= mask_high) & (this->chunks[1] >= mask_low),
+        (this->chunks[2] <= mask_high) & (this->chunks[2] >= mask_low),
+        (this->chunks[3] <= mask_high) & (this->chunks[3] >= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t not_in_range(const T low, const T high) const {
+      const simd8<T> mask_low = simd8<T>::splat(low-1);
+      const simd8<T> mask_high = simd8<T>::splat(high+1);
+      return simd8x64<bool>(
+        (this->chunks[0] >= mask_high) | (this->chunks[0] <= mask_low),
+        (this->chunks[1] >= mask_high) | (this->chunks[1] <= mask_low),
+        (this->chunks[2] >= mask_high) | (this->chunks[2] <= mask_low),
+        (this->chunks[3] >= mask_high) | (this->chunks[3] <= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t lt(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] < mask,
+        this->chunks[1] < mask,
+        this->chunks[2] < mask,
+        this->chunks[3] < mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t gt(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] > mask,
+        this->chunks[1] > mask,
+        this->chunks[2] > mask,
+        this->chunks[3] > mask
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t gteq(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] >= mask,
+        this->chunks[1] >= mask,
+        this->chunks[2] >= mask,
+        this->chunks[3] >= mask
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t gteq_unsigned(const uint8_t m) const {
+      const simd8<uint8_t> mask = simd8<uint8_t>::splat(m);
+      return  simd8x64<bool>(
+        simd8<uint8_t>(__m128i(this->chunks[0])) >= mask,
+        simd8<uint8_t>(__m128i(this->chunks[1])) >= mask,
+        simd8<uint8_t>(__m128i(this->chunks[2])) >= mask,
+        simd8<uint8_t>(__m128i(this->chunks[3])) >= mask
+      ).to_bitmask();
+    }
+  }; // struct simd8x64<T>
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/simd16-inl.h
+/* begin file src/simdutf/westmere/simd16-inl.h */
+template<typename T>
+struct simd16;
+
+template<typename T, typename Mask=simd16<bool>>
+struct base16: base<simd16<T>> {
+  typedef uint16_t bitmask_t;
+  typedef uint32_t bitmask2_t;
+
+  simdutf_really_inline base16() : base<simd16<T>>() {}
+  simdutf_really_inline base16(const __m128i _value) : base<simd16<T>>(_value) {}
+  template <typename Pointer>
+  simdutf_really_inline base16(const Pointer* ptr) : base16(_mm_loadu_si128(reinterpret_cast<const __m128i*>(ptr))) {}
+
+  simdutf_really_inline Mask operator==(const simd16<T> other) const { return _mm_cmpeq_epi16(*this, other); }
+
+  static const int SIZE = sizeof(base<simd16<T>>::value);
+
+  template<int N=1>
+  simdutf_really_inline simd16<T> prev(const simd16<T> prev_chunk) const {
+    return _mm_alignr_epi8(*this, prev_chunk, 16 - N);
+  }
+};
+
+// SIMD byte mask type (returned by things like eq and gt)
+template<>
+struct simd16<bool>: base16<bool> {
+  static simdutf_really_inline simd16<bool> splat(bool _value) { return _mm_set1_epi16(uint16_t(-(!!_value))); }
+
+  simdutf_really_inline simd16<bool>() : base16() {}
+  simdutf_really_inline simd16<bool>(const __m128i _value) : base16<bool>(_value) {}
+  // Splat constructor
+  simdutf_really_inline simd16<bool>(bool _value) : base16<bool>(splat(_value)) {}
+
+  simdutf_really_inline int to_bitmask() const { return _mm_movemask_epi8(*this); }
+  simdutf_really_inline bool any() const { return !_mm_testz_si128(*this, *this); }
+  simdutf_really_inline simd16<bool> operator~() const { return *this ^ true; }
+};
+
+template<typename T>
+struct base16_numeric: base16<T> {
+  static simdutf_really_inline simd16<T> splat(T _value) { return _mm_set1_epi16(_value); }
+  static simdutf_really_inline simd16<T> zero() { return _mm_setzero_si128(); }
+  static simdutf_really_inline simd16<T> load(const T values[8]) {
+    return _mm_loadu_si128(reinterpret_cast<const __m128i *>(values));
+  }
+
+  simdutf_really_inline base16_numeric() : base16<T>() {}
+  simdutf_really_inline base16_numeric(const __m128i _value) : base16<T>(_value) {}
+
+  // Store to array
+  simdutf_really_inline void store(T dst[8]) const { return _mm_storeu_si128(reinterpret_cast<__m128i *>(dst), *this); }
+
+  // Override to distinguish from bool version
+  simdutf_really_inline simd16<T> operator~() const { return *this ^ 0xFFu; }
+
+  // Addition/subtraction are the same for signed and unsigned
+  simdutf_really_inline simd16<T> operator+(const simd16<T> other) const { return _mm_add_epi16(*this, other); }
+  simdutf_really_inline simd16<T> operator-(const simd16<T> other) const { return _mm_sub_epi16(*this, other); }
+  simdutf_really_inline simd16<T>& operator+=(const simd16<T> other) { *this = *this + other; return *static_cast<simd16<T>*>(this); }
+  simdutf_really_inline simd16<T>& operator-=(const simd16<T> other) { *this = *this - other; return *static_cast<simd16<T>*>(this); }
+};
+
+// Signed words
+template<>
+struct simd16<int16_t> : base16_numeric<int16_t> {
+  simdutf_really_inline simd16() : base16_numeric<int16_t>() {}
+  simdutf_really_inline simd16(const __m128i _value) : base16_numeric<int16_t>(_value) {}
+  // Splat constructor
+  simdutf_really_inline simd16(int16_t _value) : simd16(splat(_value)) {}
+  // Array constructor
+  simdutf_really_inline simd16(const int16_t* values) : simd16(load(values)) {}
+  simdutf_really_inline simd16(const char16_t* values) : simd16(load(reinterpret_cast<const int16_t*>(values))) {}
+  // Member-by-member initialization
+  simdutf_really_inline simd16(
+    int16_t v0, int16_t v1, int16_t v2, int16_t v3, int16_t v4, int16_t v5, int16_t v6, int16_t v7)
+    : simd16(_mm_setr_epi16(v0, v1, v2, v3, v4, v5, v6, v7)) {}
+  simdutf_really_inline operator simd16<uint16_t>() const;
+
+  // Order-sensitive comparisons
+  simdutf_really_inline simd16<int16_t> max_val(const simd16<int16_t> other) const { return _mm_max_epi16(*this, other); }
+  simdutf_really_inline simd16<int16_t> min_val(const simd16<int16_t> other) const { return _mm_min_epi16(*this, other); }
+  simdutf_really_inline simd16<bool> operator>(const simd16<int16_t> other) const { return _mm_cmpgt_epi16(*this, other); }
+  simdutf_really_inline simd16<bool> operator<(const simd16<int16_t> other) const { return _mm_cmpgt_epi16(other, *this); }
+};
+
+// Unsigned words
+template<>
+struct simd16<uint16_t>: base16_numeric<uint16_t>  {
+  simdutf_really_inline simd16() : base16_numeric<uint16_t>() {}
+  simdutf_really_inline simd16(const __m128i _value) : base16_numeric<uint16_t>(_value) {}
+
+  // Splat constructor
+  simdutf_really_inline simd16(uint16_t _value) : simd16(splat(_value)) {}
+  // Array constructor
+  simdutf_really_inline simd16(const uint16_t* values) : simd16(load(values)) {}
+  simdutf_really_inline simd16(const char16_t* values) : simd16(load(reinterpret_cast<const uint16_t*>(values))) {}
+  // Member-by-member initialization
+  simdutf_really_inline simd16(
+    uint16_t v0, uint16_t v1, uint16_t v2, uint16_t v3, uint16_t v4, uint16_t v5, uint16_t v6, uint16_t v7)
+  : simd16(_mm_setr_epi16(v0, v1, v2, v3, v4, v5, v6, v7)) {}
+  // Repeat 16 values as many times as necessary (usually for lookup tables)
+  simdutf_really_inline static simd16<uint16_t> repeat_16(
+    uint16_t v0, uint16_t v1, uint16_t v2, uint16_t v3, uint16_t v4, uint16_t v5, uint16_t v6, uint16_t v7
+  ) {
+    return simd16<uint16_t>(v0, v1, v2, v3, v4, v5, v6, v7);
+  }
+
+  // Saturated math
+  simdutf_really_inline simd16<uint16_t> saturating_add(const simd16<uint16_t> other) const { return _mm_adds_epu16(*this, other); }
+  simdutf_really_inline simd16<uint16_t> saturating_sub(const simd16<uint16_t> other) const { return _mm_subs_epu16(*this, other); }
+
+  // Order-specific operations
+  simdutf_really_inline simd16<uint16_t> max_val(const simd16<uint16_t> other) const { return _mm_max_epu16(*this, other); }
+  simdutf_really_inline simd16<uint16_t> min_val(const simd16<uint16_t> other) const { return _mm_min_epu16(*this, other); }
+  // Same as >, but only guarantees true is nonzero (< guarantees true = -1)
+  simdutf_really_inline simd16<uint16_t> gt_bits(const simd16<uint16_t> other) const { return this->saturating_sub(other); }
+  // Same as <, but only guarantees true is nonzero (< guarantees true = -1)
+  simdutf_really_inline simd16<uint16_t> lt_bits(const simd16<uint16_t> other) const { return other.saturating_sub(*this); }
+  simdutf_really_inline simd16<bool> operator<=(const simd16<uint16_t> other) const { return other.max_val(*this) == other; }
+  simdutf_really_inline simd16<bool> operator>=(const simd16<uint16_t> other) const { return other.min_val(*this) == other; }
+  simdutf_really_inline simd16<bool> operator>(const simd16<uint16_t> other) const { return this->gt_bits(other).any_bits_set(); }
+  simdutf_really_inline simd16<bool> operator<(const simd16<uint16_t> other) const { return this->gt_bits(other).any_bits_set(); }
+
+  // Bit-specific operations
+  simdutf_really_inline simd16<bool> bits_not_set() const { return *this == uint16_t(0); }
+  simdutf_really_inline simd16<bool> bits_not_set(simd16<uint16_t> bits) const { return (*this & bits).bits_not_set(); }
+  simdutf_really_inline simd16<bool> any_bits_set() const { return ~this->bits_not_set(); }
+  simdutf_really_inline simd16<bool> any_bits_set(simd16<uint16_t> bits) const { return ~this->bits_not_set(bits); }
+
+  simdutf_really_inline bool bits_not_set_anywhere() const { return _mm_testz_si128(*this, *this); }
+  simdutf_really_inline bool any_bits_set_anywhere() const { return !bits_not_set_anywhere(); }
+  simdutf_really_inline bool bits_not_set_anywhere(simd16<uint16_t> bits) const { return _mm_testz_si128(*this, bits); }
+  simdutf_really_inline bool any_bits_set_anywhere(simd16<uint16_t> bits) const { return !bits_not_set_anywhere(bits); }
+  template<int N>
+  simdutf_really_inline simd16<uint16_t> shr() const { return simd16<uint16_t>(_mm_srli_epi16(*this, N)); }
+  template<int N>
+  simdutf_really_inline simd16<uint16_t> shl() const { return simd16<uint16_t>(_mm_slli_epi16(*this, N)); }
+  // Get one of the bits and make a bitmask out of it.
+  // e.g. value.get_bit<7>() gets the high bit
+  template<int N>
+  simdutf_really_inline int get_bit() const { return _mm_movemask_epi8(_mm_slli_epi16(*this, 7-N)); }
+
+  // Change the endianness
+  simdutf_really_inline simd16<uint16_t> swap_bytes() const {
+    const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+    return _mm_shuffle_epi8(*this, swap);
+  }
+
+  // Pack with the unsigned saturation  two uint16_t words into single uint8_t vector
+  static simdutf_really_inline simd8<uint8_t> pack(const simd16<uint16_t>& v0, const simd16<uint16_t>& v1) {
+    return _mm_packus_epi16(v0, v1);
+  }
+};
+simdutf_really_inline simd16<int16_t>::operator simd16<uint16_t>() const { return this->value; }
+
+template<typename T>
+  struct simd16x32 {
+    static constexpr int NUM_CHUNKS = 64 / sizeof(simd16<T>);
+    static_assert(NUM_CHUNKS == 4, "Westmere kernel should use four registers per 64-byte block.");
+    simd16<T> chunks[NUM_CHUNKS];
+
+    simd16x32(const simd16x32<T>& o) = delete; // no copy allowed
+    simd16x32<T>& operator=(const simd16<T> other) = delete; // no assignment allowed
+    simd16x32() = delete; // no default constructor allowed
+
+    simdutf_really_inline simd16x32(const simd16<T> chunk0, const simd16<T> chunk1, const simd16<T> chunk2, const simd16<T> chunk3) : chunks{chunk0, chunk1, chunk2, chunk3} {}
+    simdutf_really_inline simd16x32(const T* ptr) : chunks{simd16<T>::load(ptr), simd16<T>::load(ptr+sizeof(simd16<T>)/sizeof(T)), simd16<T>::load(ptr+2*sizeof(simd16<T>)/sizeof(T)), simd16<T>::load(ptr+3*sizeof(simd16<T>)/sizeof(T))} {}
+
+    simdutf_really_inline void store(T* ptr) const {
+      this->chunks[0].store(ptr+sizeof(simd16<T>)*0/sizeof(T));
+      this->chunks[1].store(ptr+sizeof(simd16<T>)*1/sizeof(T));
+      this->chunks[2].store(ptr+sizeof(simd16<T>)*2/sizeof(T));
+      this->chunks[3].store(ptr+sizeof(simd16<T>)*3/sizeof(T));
+    }
+
+    simdutf_really_inline simd16<T> reduce_or() const {
+      return (this->chunks[0] | this->chunks[1]) | (this->chunks[2] | this->chunks[3]);
+    }
+
+    simdutf_really_inline bool is_ascii() const {
+      return this->reduce_or().is_ascii();
+    }
+
+    simdutf_really_inline void store_ascii_as_utf16(char16_t * ptr) const {
+      this->chunks[0].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*0);
+      this->chunks[1].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*1);
+      this->chunks[2].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*2);
+      this->chunks[3].store_ascii_as_utf16(ptr+sizeof(simd16<T>)*3);
+    }
+
+    simdutf_really_inline uint64_t to_bitmask() const {
+      uint64_t r0 = uint32_t(this->chunks[0].to_bitmask() );
+      uint64_t r1 =          this->chunks[1].to_bitmask() ;
+      uint64_t r2 =          this->chunks[2].to_bitmask() ;
+      uint64_t r3 =          this->chunks[3].to_bitmask() ;
+      return r0 | (r1 << 16) | (r2 << 32) | (r3 << 48);
+    }
+
+    simdutf_really_inline void swap_bytes() {
+      this->chunks[0] = this->chunks[0].swap_bytes();
+      this->chunks[1] = this->chunks[1].swap_bytes();
+      this->chunks[2] = this->chunks[2].swap_bytes();
+      this->chunks[3] = this->chunks[3].swap_bytes();
+    }
+
+    simdutf_really_inline uint64_t eq(const T m) const {
+      const simd16<T> mask = simd16<T>::splat(m);
+      return  simd16x32<bool>(
+        this->chunks[0] == mask,
+        this->chunks[1] == mask,
+        this->chunks[2] == mask,
+        this->chunks[3] == mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t eq(const simd16x32<uint16_t> &other) const {
+      return  simd16x32<bool>(
+        this->chunks[0] == other.chunks[0],
+        this->chunks[1] == other.chunks[1],
+        this->chunks[2] == other.chunks[2],
+        this->chunks[3] == other.chunks[3]
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t lteq(const T m) const {
+      const simd16<T> mask = simd16<T>::splat(m);
+      return  simd16x32<bool>(
+        this->chunks[0] <= mask,
+        this->chunks[1] <= mask,
+        this->chunks[2] <= mask,
+        this->chunks[3] <= mask
+      ).to_bitmask();
+    }
+
+    simdutf_really_inline uint64_t in_range(const T low, const T high) const {
+      const simd16<T> mask_low = simd16<T>::splat(low);
+      const simd16<T> mask_high = simd16<T>::splat(high);
+
+      return  simd16x32<bool>(
+        (this->chunks[0] <= mask_high) & (this->chunks[0] >= mask_low),
+        (this->chunks[1] <= mask_high) & (this->chunks[1] >= mask_low),
+        (this->chunks[2] <= mask_high) & (this->chunks[2] >= mask_low),
+        (this->chunks[3] <= mask_high) & (this->chunks[3] >= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t not_in_range(const T low, const T high) const {
+      const simd16<T> mask_low = simd16<T>::splat(static_cast<T>(low-1));
+      const simd16<T> mask_high = simd16<T>::splat(static_cast<T>(high+1));
+      return simd16x32<bool>(
+        (this->chunks[0] >= mask_high) | (this->chunks[0] <= mask_low),
+        (this->chunks[1] >= mask_high) | (this->chunks[1] <= mask_low),
+        (this->chunks[2] >= mask_high) | (this->chunks[2] <= mask_low),
+        (this->chunks[3] >= mask_high) | (this->chunks[3] <= mask_low)
+      ).to_bitmask();
+    }
+    simdutf_really_inline uint64_t lt(const T m) const {
+      const simd16<T> mask = simd16<T>::splat(m);
+      return  simd16x32<bool>(
+        this->chunks[0] < mask,
+        this->chunks[1] < mask,
+        this->chunks[2] < mask,
+        this->chunks[3] < mask
+      ).to_bitmask();
+    }
+  }; // struct simd16x32<T>
+/* end file src/simdutf/westmere/simd16-inl.h */
+
+} // namespace simd
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+
+#endif // SIMDUTF_WESTMERE_SIMD_INPUT_H
+/* end file src/simdutf/westmere/simd.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/end.h
+/* begin file src/simdutf/westmere/end.h */
+SIMDUTF_UNTARGET_REGION
+/* end file src/simdutf/westmere/end.h */
+
+#endif // SIMDUTF_IMPLEMENTATION_WESTMERE
+#endif // SIMDUTF_WESTMERE_COMMON_H
+/* end file src/simdutf/westmere.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64.h
+/* begin file src/simdutf/ppc64.h */
+#ifndef SIMDUTF_PPC64_H
+#define SIMDUTF_PPC64_H
+
+#ifdef SIMDUTF_FALLBACK_H
+#error "ppc64.h must be included before fallback.h"
+#endif
+
+
+#ifndef SIMDUTF_IMPLEMENTATION_PPC64
+#define SIMDUTF_IMPLEMENTATION_PPC64 (SIMDUTF_IS_PPC64)
+#endif
+#define SIMDUTF_CAN_ALWAYS_RUN_PPC64 SIMDUTF_IMPLEMENTATION_PPC64 && SIMDUTF_IS_PPC64
+
+
+
+#if SIMDUTF_IMPLEMENTATION_PPC64
+
+namespace simdutf {
+/**
+ * Implementation for ALTIVEC (PPC64).
+ */
+namespace ppc64 {
+} // namespace ppc64
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64/implementation.h
+/* begin file src/simdutf/ppc64/implementation.h */
+#ifndef SIMDUTF_PPC64_IMPLEMENTATION_H
+#define SIMDUTF_PPC64_IMPLEMENTATION_H
+
+
+namespace simdutf {
+namespace ppc64 {
+
+namespace {
+using namespace simdutf;
+} // namespace
+
+class implementation final : public simdutf::implementation {
+public:
+  simdutf_really_inline implementation()
+      : simdutf::implementation("ppc64", "PPC64 ALTIVEC",
+                                 internal::instruction_set::ALTIVEC) {}
+  simdutf_warn_unused int detect_encodings(const char * input, size_t length) const noexcept final;
+  simdutf_warn_unused bool validate_utf8(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf8_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_ascii(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_ascii_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16le(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16be(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf32(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  void change_endianness_utf16(const char16_t * buf, size_t length, char16_t * output) const noexcept final;
+  simdutf_warn_unused size_t count_utf16le(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf16be(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf8(const char * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf8(const char * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf8(const char * input, size_t length) const noexcept;
+};
+
+} // namespace ppc64
+} // namespace simdutf
+
+#endif // SIMDUTF_PPC64_IMPLEMENTATION_H
+/* end file src/simdutf/ppc64/implementation.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64/begin.h
+/* begin file src/simdutf/ppc64/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "ppc64"
+// #define SIMDUTF_IMPLEMENTATION ppc64
+/* end file src/simdutf/ppc64/begin.h */
+
+// Declarations
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64/intrinsics.h
+/* begin file src/simdutf/ppc64/intrinsics.h */
+#ifndef SIMDUTF_PPC64_INTRINSICS_H
+#define SIMDUTF_PPC64_INTRINSICS_H
+
+
+// This should be the correct header whether
+// you use visual studio or other compilers.
+#include <altivec.h>
+
+// These are defined by altivec.h in GCC toolchain, it is safe to undef them.
+#ifdef bool
+#undef bool
+#endif
+
+#ifdef vector
+#undef vector
+#endif
+
+#endif //  SIMDUTF_PPC64_INTRINSICS_H
+/* end file src/simdutf/ppc64/intrinsics.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64/bitmanipulation.h
+/* begin file src/simdutf/ppc64/bitmanipulation.h */
+#ifndef SIMDUTF_PPC64_BITMANIPULATION_H
+#define SIMDUTF_PPC64_BITMANIPULATION_H
+
+namespace simdutf {
+namespace ppc64 {
+namespace {
+
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+simdutf_really_inline int count_ones(uint64_t input_num) {
+  // note: we do not support legacy 32-bit Windows
+  return __popcnt64(input_num); // Visual Studio wants two underscores
+}
+#else
+simdutf_really_inline int count_ones(uint64_t input_num) {
+  return __builtin_popcountll(input_num);
+}
+#endif
+
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+
+#endif // SIMDUTF_PPC64_BITMANIPULATION_H
+/* end file src/simdutf/ppc64/bitmanipulation.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64/simd.h
+/* begin file src/simdutf/ppc64/simd.h */
+#ifndef SIMDUTF_PPC64_SIMD_H
+#define SIMDUTF_PPC64_SIMD_H
+
+#include <type_traits>
+
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace simd {
+
+using __m128i = __vector unsigned char;
+
+template <typename Child> struct base {
+  __m128i value;
+
+  // Zero constructor
+  simdutf_really_inline base() : value{__m128i()} {}
+
+  // Conversion from SIMD register
+  simdutf_really_inline base(const __m128i _value) : value(_value) {}
+
+  // Conversion to SIMD register
+  simdutf_really_inline operator const __m128i &() const {
+    return this->value;
+  }
+  simdutf_really_inline operator __m128i &() { return this->value; }
+
+  // Bit operations
+  simdutf_really_inline Child operator|(const Child other) const {
+    return vec_or(this->value, (__m128i)other);
+  }
+  simdutf_really_inline Child operator&(const Child other) const {
+    return vec_and(this->value, (__m128i)other);
+  }
+  simdutf_really_inline Child operator^(const Child other) const {
+    return vec_xor(this->value, (__m128i)other);
+  }
+  simdutf_really_inline Child bit_andnot(const Child other) const {
+    return vec_andc(this->value, (__m128i)other);
+  }
+  simdutf_really_inline Child &operator|=(const Child other) {
+    auto this_cast = static_cast<Child*>(this);
+    *this_cast = *this_cast | other;
+    return *this_cast;
+  }
+  simdutf_really_inline Child &operator&=(const Child other) {
+    auto this_cast = static_cast<Child*>(this);
+    *this_cast = *this_cast & other;
+    return *this_cast;
+  }
+  simdutf_really_inline Child &operator^=(const Child other) {
+    auto this_cast = static_cast<Child*>(this);
+    *this_cast = *this_cast ^ other;
+    return *this_cast;
+  }
+};
+
+// Forward-declared so they can be used by splat and friends.
+template <typename T> struct simd8;
+
+template <typename T, typename Mask = simd8<bool>>
+struct base8 : base<simd8<T>> {
+  typedef uint16_t bitmask_t;
+  typedef uint32_t bitmask2_t;
+
+  simdutf_really_inline base8() : base<simd8<T>>() {}
+  simdutf_really_inline base8(const __m128i _value) : base<simd8<T>>(_value) {}
+
+  simdutf_really_inline Mask operator==(const simd8<T> other) const {
+    return (__m128i)vec_cmpeq(this->value, (__m128i)other);
+  }
+
+  static const int SIZE = sizeof(base<simd8<T>>::value);
+
+  template <int N = 1>
+  simdutf_really_inline simd8<T> prev(simd8<T> prev_chunk) const {
+    __m128i chunk = this->value;
+#ifdef __LITTLE_ENDIAN__
+    chunk = (__m128i)vec_reve(this->value);
+    prev_chunk = (__m128i)vec_reve((__m128i)prev_chunk);
+#endif
+    chunk = (__m128i)vec_sld((__m128i)prev_chunk, (__m128i)chunk, 16 - N);
+#ifdef __LITTLE_ENDIAN__
+    chunk = (__m128i)vec_reve((__m128i)chunk);
+#endif
+    return chunk;
+  }
+};
+
+// SIMD byte mask type (returned by things like eq and gt)
+template <> struct simd8<bool> : base8<bool> {
+  static simdutf_really_inline simd8<bool> splat(bool _value) {
+    return (__m128i)vec_splats((unsigned char)(-(!!_value)));
+  }
+
+  simdutf_really_inline simd8<bool>() : base8() {}
+  simdutf_really_inline simd8<bool>(const __m128i _value)
+      : base8<bool>(_value) {}
+  // Splat constructor
+  simdutf_really_inline simd8<bool>(bool _value)
+      : base8<bool>(splat(_value)) {}
+
+  simdutf_really_inline int to_bitmask() const {
+    __vector unsigned long long result;
+    const __m128i perm_mask = {0x78, 0x70, 0x68, 0x60, 0x58, 0x50, 0x48, 0x40,
+                               0x38, 0x30, 0x28, 0x20, 0x18, 0x10, 0x08, 0x00};
+
+    result = ((__vector unsigned long long)vec_vbpermq((__m128i)this->value,
+                                                       (__m128i)perm_mask));
+#ifdef __LITTLE_ENDIAN__
+    return static_cast<int>(result[1]);
+#else
+    return static_cast<int>(result[0]);
+#endif
+  }
+  simdutf_really_inline bool any() const {
+    return !vec_all_eq(this->value, (__m128i)vec_splats(0));
+  }
+  simdutf_really_inline simd8<bool> operator~() const {
+    return this->value ^ (__m128i)splat(true);
+  }
+};
+
+template <typename T> struct base8_numeric : base8<T> {
+  static simdutf_really_inline simd8<T> splat(T value) {
+    (void)value;
+    return (__m128i)vec_splats(value);
+  }
+  static simdutf_really_inline simd8<T> zero() { return splat(0); }
+  static simdutf_really_inline simd8<T> load(const T values[16]) {
+    return (__m128i)(vec_vsx_ld(0, reinterpret_cast<const uint8_t *>(values)));
+  }
+  // Repeat 16 values as many times as necessary (usually for lookup tables)
+  static simdutf_really_inline simd8<T> repeat_16(T v0, T v1, T v2, T v3, T v4,
+                                                   T v5, T v6, T v7, T v8, T v9,
+                                                   T v10, T v11, T v12, T v13,
+                                                   T v14, T v15) {
+    return simd8<T>(v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12, v13,
+                    v14, v15);
+  }
+
+  simdutf_really_inline base8_numeric() : base8<T>() {}
+  simdutf_really_inline base8_numeric(const __m128i _value)
+      : base8<T>(_value) {}
+
+  // Store to array
+  simdutf_really_inline void store(T dst[16]) const {
+    vec_vsx_st(this->value, 0, reinterpret_cast<__m128i *>(dst));
+  }
+
+  // Override to distinguish from bool version
+  simdutf_really_inline simd8<T> operator~() const { return *this ^ 0xFFu; }
+
+  // Addition/subtraction are the same for signed and unsigned
+  simdutf_really_inline simd8<T> operator+(const simd8<T> other) const {
+    return (__m128i)((__m128i)this->value + (__m128i)other);
+  }
+  simdutf_really_inline simd8<T> operator-(const simd8<T> other) const {
+    return (__m128i)((__m128i)this->value - (__m128i)other);
+  }
+  simdutf_really_inline simd8<T> &operator+=(const simd8<T> other) {
+    *this = *this + other;
+    return *static_cast<simd8<T> *>(this);
+  }
+  simdutf_really_inline simd8<T> &operator-=(const simd8<T> other) {
+    *this = *this - other;
+    return *static_cast<simd8<T> *>(this);
+  }
+
+  // Perform a lookup assuming the value is between 0 and 16 (undefined behavior
+  // for out of range values)
+  template <typename L>
+  simdutf_really_inline simd8<L> lookup_16(simd8<L> lookup_table) const {
+    return (__m128i)vec_perm((__m128i)lookup_table, (__m128i)lookup_table, this->value);
+  }
+
+  template <typename L>
+  simdutf_really_inline simd8<L>
+  lookup_16(L replace0, L replace1, L replace2, L replace3, L replace4,
+            L replace5, L replace6, L replace7, L replace8, L replace9,
+            L replace10, L replace11, L replace12, L replace13, L replace14,
+            L replace15) const {
+    return lookup_16(simd8<L>::repeat_16(
+        replace0, replace1, replace2, replace3, replace4, replace5, replace6,
+        replace7, replace8, replace9, replace10, replace11, replace12,
+        replace13, replace14, replace15));
+  }
+};
+
+// Signed bytes
+template <> struct simd8<int8_t> : base8_numeric<int8_t> {
+  simdutf_really_inline simd8() : base8_numeric<int8_t>() {}
+  simdutf_really_inline simd8(const __m128i _value)
+      : base8_numeric<int8_t>(_value) {}
+
+  // Splat constructor
+  simdutf_really_inline simd8(int8_t _value) : simd8(splat(_value)) {}
+  // Array constructor
+  simdutf_really_inline simd8(const int8_t *values) : simd8(load(values)) {}
+  // Member-by-member initialization
+  simdutf_really_inline simd8(int8_t v0, int8_t v1, int8_t v2, int8_t v3,
+                               int8_t v4, int8_t v5, int8_t v6, int8_t v7,
+                               int8_t v8, int8_t v9, int8_t v10, int8_t v11,
+                               int8_t v12, int8_t v13, int8_t v14, int8_t v15)
+      : simd8((__m128i)(__vector signed char){v0, v1, v2, v3, v4, v5, v6, v7,
+                                              v8, v9, v10, v11, v12, v13, v14,
+                                              v15}) {}
+  // Repeat 16 values as many times as necessary (usually for lookup tables)
+  simdutf_really_inline static simd8<int8_t>
+  repeat_16(int8_t v0, int8_t v1, int8_t v2, int8_t v3, int8_t v4, int8_t v5,
+            int8_t v6, int8_t v7, int8_t v8, int8_t v9, int8_t v10, int8_t v11,
+            int8_t v12, int8_t v13, int8_t v14, int8_t v15) {
+    return simd8<int8_t>(v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12,
+                         v13, v14, v15);
+  }
+
+  // Order-sensitive comparisons
+  simdutf_really_inline simd8<int8_t>
+  max_val(const simd8<int8_t> other) const {
+    return (__m128i)vec_max((__vector signed char)this->value,
+                            (__vector signed char)(__m128i)other);
+  }
+  simdutf_really_inline simd8<int8_t>
+  min_val(const simd8<int8_t> other) const {
+    return (__m128i)vec_min((__vector signed char)this->value,
+                            (__vector signed char)(__m128i)other);
+  }
+  simdutf_really_inline simd8<bool>
+  operator>(const simd8<int8_t> other) const {
+    return (__m128i)vec_cmpgt((__vector signed char)this->value,
+                              (__vector signed char)(__m128i)other);
+  }
+  simdutf_really_inline simd8<bool>
+  operator<(const simd8<int8_t> other) const {
+    return (__m128i)vec_cmplt((__vector signed char)this->value,
+                              (__vector signed char)(__m128i)other);
+  }
+};
+
+// Unsigned bytes
+template <> struct simd8<uint8_t> : base8_numeric<uint8_t> {
+  simdutf_really_inline simd8() : base8_numeric<uint8_t>() {}
+  simdutf_really_inline simd8(const __m128i _value)
+      : base8_numeric<uint8_t>(_value) {}
+  // Splat constructor
+  simdutf_really_inline simd8(uint8_t _value) : simd8(splat(_value)) {}
+  // Array constructor
+  simdutf_really_inline simd8(const uint8_t *values) : simd8(load(values)) {}
+  // Member-by-member initialization
+  simdutf_really_inline
+  simd8(uint8_t v0, uint8_t v1, uint8_t v2, uint8_t v3, uint8_t v4, uint8_t v5,
+        uint8_t v6, uint8_t v7, uint8_t v8, uint8_t v9, uint8_t v10,
+        uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14, uint8_t v15)
+      : simd8((__m128i){v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12,
+                        v13, v14, v15}) {}
+  // Repeat 16 values as many times as necessary (usually for lookup tables)
+  simdutf_really_inline static simd8<uint8_t>
+  repeat_16(uint8_t v0, uint8_t v1, uint8_t v2, uint8_t v3, uint8_t v4,
+            uint8_t v5, uint8_t v6, uint8_t v7, uint8_t v8, uint8_t v9,
+            uint8_t v10, uint8_t v11, uint8_t v12, uint8_t v13, uint8_t v14,
+            uint8_t v15) {
+    return simd8<uint8_t>(v0, v1, v2, v3, v4, v5, v6, v7, v8, v9, v10, v11, v12,
+                          v13, v14, v15);
+  }
+
+  // Saturated math
+  simdutf_really_inline simd8<uint8_t>
+  saturating_add(const simd8<uint8_t> other) const {
+    return (__m128i)vec_adds(this->value, (__m128i)other);
+  }
+  simdutf_really_inline simd8<uint8_t>
+  saturating_sub(const simd8<uint8_t> other) const {
+    return (__m128i)vec_subs(this->value, (__m128i)other);
+  }
+
+  // Order-specific operations
+  simdutf_really_inline simd8<uint8_t>
+  max_val(const simd8<uint8_t> other) const {
+    return (__m128i)vec_max(this->value, (__m128i)other);
+  }
+  simdutf_really_inline simd8<uint8_t>
+  min_val(const simd8<uint8_t> other) const {
+    return (__m128i)vec_min(this->value, (__m128i)other);
+  }
+  // Same as >, but only guarantees true is nonzero (< guarantees true = -1)
+  simdutf_really_inline simd8<uint8_t>
+  gt_bits(const simd8<uint8_t> other) const {
+    return this->saturating_sub(other);
+  }
+  // Same as <, but only guarantees true is nonzero (< guarantees true = -1)
+  simdutf_really_inline simd8<uint8_t>
+  lt_bits(const simd8<uint8_t> other) const {
+    return other.saturating_sub(*this);
+  }
+  simdutf_really_inline simd8<bool>
+  operator<=(const simd8<uint8_t> other) const {
+    return other.max_val(*this) == other;
+  }
+  simdutf_really_inline simd8<bool>
+  operator>=(const simd8<uint8_t> other) const {
+    return other.min_val(*this) == other;
+  }
+  simdutf_really_inline simd8<bool>
+  operator>(const simd8<uint8_t> other) const {
+    return this->gt_bits(other).any_bits_set();
+  }
+  simdutf_really_inline simd8<bool>
+  operator<(const simd8<uint8_t> other) const {
+    return this->gt_bits(other).any_bits_set();
+  }
+
+  // Bit-specific operations
+  simdutf_really_inline simd8<bool> bits_not_set() const {
+    return (__m128i)vec_cmpeq(this->value, (__m128i)vec_splats(uint8_t(0)));
+  }
+  simdutf_really_inline simd8<bool> bits_not_set(simd8<uint8_t> bits) const {
+    return (*this & bits).bits_not_set();
+  }
+  simdutf_really_inline simd8<bool> any_bits_set() const {
+    return ~this->bits_not_set();
+  }
+  simdutf_really_inline simd8<bool> any_bits_set(simd8<uint8_t> bits) const {
+    return ~this->bits_not_set(bits);
+  }
+
+  simdutf_really_inline bool is_ascii() const {
+      return this->saturating_sub(0b01111111u).bits_not_set_anywhere();
+  }
+
+  simdutf_really_inline bool bits_not_set_anywhere() const {
+    return vec_all_eq(this->value, (__m128i)vec_splats(0));
+  }
+  simdutf_really_inline bool any_bits_set_anywhere() const {
+    return !bits_not_set_anywhere();
+  }
+  simdutf_really_inline bool bits_not_set_anywhere(simd8<uint8_t> bits) const {
+    return vec_all_eq(vec_and(this->value, (__m128i)bits),
+                      (__m128i)vec_splats(0));
+  }
+  simdutf_really_inline bool any_bits_set_anywhere(simd8<uint8_t> bits) const {
+    return !bits_not_set_anywhere(bits);
+  }
+  template <int N> simdutf_really_inline simd8<uint8_t> shr() const {
+    return simd8<uint8_t>(
+        (__m128i)vec_sr(this->value, (__m128i)vec_splat_u8(N)));
+  }
+  template <int N> simdutf_really_inline simd8<uint8_t> shl() const {
+    return simd8<uint8_t>(
+        (__m128i)vec_sl(this->value, (__m128i)vec_splat_u8(N)));
+  }
+};
+
+template <typename T> struct simd8x64 {
+  static constexpr int NUM_CHUNKS = 64 / sizeof(simd8<T>);
+  static_assert(NUM_CHUNKS == 4,
+                "PPC64 kernel should use four registers per 64-byte block.");
+  simd8<T> chunks[NUM_CHUNKS];
+
+  simd8x64(const simd8x64<T> &o) = delete; // no copy allowed
+  simd8x64<T> &
+  operator=(const simd8<T> other) = delete; // no assignment allowed
+  simd8x64() = delete;                      // no default constructor allowed
+
+  simdutf_really_inline simd8x64(const simd8<T> chunk0, const simd8<T> chunk1,
+                                  const simd8<T> chunk2, const simd8<T> chunk3)
+      : chunks{chunk0, chunk1, chunk2, chunk3} {}
+
+  simdutf_really_inline simd8x64(const T* ptr) : chunks{simd8<T>::load(ptr), simd8<T>::load(ptr+sizeof(simd8<T>)/sizeof(T)), simd8<T>::load(ptr+2*sizeof(simd8<T>)/sizeof(T)), simd8<T>::load(ptr+3*sizeof(simd8<T>)/sizeof(T))} {}
+
+  simdutf_really_inline void store(T* ptr) const {
+    this->chunks[0].store(ptr + sizeof(simd8<T>) * 0/sizeof(T));
+    this->chunks[1].store(ptr + sizeof(simd8<T>) * 1/sizeof(T));
+    this->chunks[2].store(ptr + sizeof(simd8<T>) * 2/sizeof(T));
+    this->chunks[3].store(ptr + sizeof(simd8<T>) * 3/sizeof(T));
+  }
+
+
+  simdutf_really_inline simd8x64<T>& operator |=(const simd8x64<T> &other) {
+      this->chunks[0] |= other.chunks[0];
+      this->chunks[1] |= other.chunks[1];
+      this->chunks[2] |= other.chunks[2];
+      this->chunks[3] |= other.chunks[3];
+      return *this;
+    }
+
+  simdutf_really_inline simd8<T> reduce_or() const {
+    return (this->chunks[0] | this->chunks[1]) |
+           (this->chunks[2] | this->chunks[3]);
+  }
+
+
+  simdutf_really_inline bool is_ascii() const {
+    return input.reduce_or().is_ascii();
+  }
+
+  simdutf_really_inline uint64_t to_bitmask() const {
+    uint64_t r0 = uint32_t(this->chunks[0].to_bitmask());
+    uint64_t r1 = this->chunks[1].to_bitmask();
+    uint64_t r2 = this->chunks[2].to_bitmask();
+    uint64_t r3 = this->chunks[3].to_bitmask();
+    return r0 | (r1 << 16) | (r2 << 32) | (r3 << 48);
+  }
+
+  simdutf_really_inline uint64_t eq(const T m) const {
+    const simd8<T> mask = simd8<T>::splat(m);
+    return simd8x64<bool>(this->chunks[0] == mask, this->chunks[1] == mask,
+                          this->chunks[2] == mask, this->chunks[3] == mask)
+        .to_bitmask();
+  }
+
+  simdutf_really_inline uint64_t eq(const simd8x64<uint8_t> &other) const {
+    return simd8x64<bool>(this->chunks[0] == other.chunks[0],
+                          this->chunks[1] == other.chunks[1],
+                          this->chunks[2] == other.chunks[2],
+                          this->chunks[3] == other.chunks[3])
+        .to_bitmask();
+  }
+
+  simdutf_really_inline uint64_t lteq(const T m) const {
+    const simd8<T> mask = simd8<T>::splat(m);
+    return simd8x64<bool>(this->chunks[0] <= mask, this->chunks[1] <= mask,
+                          this->chunks[2] <= mask, this->chunks[3] <= mask)
+        .to_bitmask();
+  }
+
+  simdutf_really_inline uint64_t in_range(const T low, const T high) const {
+      const simd8<T> mask_low = simd8<T>::splat(low);
+      const simd8<T> mask_high = simd8<T>::splat(high);
+
+      return  simd8x64<bool>(
+        (this->chunks[0] <= mask_high) & (this->chunks[0] >= mask_low),
+        (this->chunks[1] <= mask_high) & (this->chunks[1] >= mask_low),
+        (this->chunks[2] <= mask_high) & (this->chunks[2] >= mask_low),
+        (this->chunks[3] <= mask_high) & (this->chunks[3] >= mask_low)
+      ).to_bitmask();
+  }
+  simdutf_really_inline uint64_t not_in_range(const T low, const T high) const {
+      const simd8<T> mask_low = simd8<T>::splat(low);
+      const simd8<T> mask_high = simd8<T>::splat(high);
+      return  simd8x64<bool>(
+        (this->chunks[0] > mask_high) | (this->chunks[0] < mask_low),
+        (this->chunks[1] > mask_high) | (this->chunks[1] < mask_low),
+        (this->chunks[2] > mask_high) | (this->chunks[2] < mask_low),
+        (this->chunks[3] > mask_high) | (this->chunks[3] < mask_low)
+      ).to_bitmask();
+  }
+  simdutf_really_inline uint64_t lt(const T m) const {
+    const simd8<T> mask = simd8<T>::splat(m);
+    return simd8x64<bool>(this->chunks[0] < mask, this->chunks[1] < mask,
+                          this->chunks[2] < mask, this->chunks[3] < mask)
+        .to_bitmask();
+  }
+
+  simdutf_really_inline uint64_t gt(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] > mask,
+        this->chunks[1] > mask,
+        this->chunks[2] > mask,
+        this->chunks[3] > mask
+      ).to_bitmask();
+  }
+  simdutf_really_inline uint64_t gteq(const T m) const {
+      const simd8<T> mask = simd8<T>::splat(m);
+      return  simd8x64<bool>(
+        this->chunks[0] >= mask,
+        this->chunks[1] >= mask,
+        this->chunks[2] >= mask,
+        this->chunks[3] >= mask
+      ).to_bitmask();
+  }
+  simdutf_really_inline uint64_t gteq_unsigned(const uint8_t m) const {
+      const simd8<uint8_t> mask = simd8<uint8_t>::splat(m);
+      return  simd8x64<bool>(
+        simd8<uint8_t>(this->chunks[0]) >= mask,
+        simd8<uint8_t>(this->chunks[1]) >= mask,
+        simd8<uint8_t>(this->chunks[2]) >= mask,
+        simd8<uint8_t>(this->chunks[3]) >= mask
+      ).to_bitmask();
+  }
+}; // struct simd8x64<T>
+
+} // namespace simd
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+
+#endif // SIMDUTF_PPC64_SIMD_INPUT_H
+/* end file src/simdutf/ppc64/simd.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64/end.h
+/* begin file src/simdutf/ppc64/end.h */
+/* end file src/simdutf/ppc64/end.h */
+
+#endif // SIMDUTF_IMPLEMENTATION_PPC64
+
+#endif // SIMDUTF_PPC64_H
+/* end file src/simdutf/ppc64.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/fallback.h
+/* begin file src/simdutf/fallback.h */
+#ifndef SIMDUTF_FALLBACK_H
+#define SIMDUTF_FALLBACK_H
+
+
+// Default Fallback to on unless a builtin implementation has already been selected.
+#ifndef SIMDUTF_IMPLEMENTATION_FALLBACK
+#define SIMDUTF_IMPLEMENTATION_FALLBACK 1 // (!SIMDUTF_CAN_ALWAYS_RUN_ARM64 && !SIMDUTF_CAN_ALWAYS_RUN_HASWELL && !SIMDUTF_CAN_ALWAYS_RUN_WESTMERE && !SIMDUTF_CAN_ALWAYS_RUN_PPC64)
+#endif
+#define SIMDUTF_CAN_ALWAYS_RUN_FALLBACK SIMDUTF_IMPLEMENTATION_FALLBACK
+
+#if SIMDUTF_IMPLEMENTATION_FALLBACK
+
+namespace simdutf {
+/**
+ * Fallback implementation (runs on any machine).
+ */
+namespace fallback {
+} // namespace fallback
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/fallback/implementation.h
+/* begin file src/simdutf/fallback/implementation.h */
+#ifndef SIMDUTF_FALLBACK_IMPLEMENTATION_H
+#define SIMDUTF_FALLBACK_IMPLEMENTATION_H
+
+
+namespace simdutf {
+namespace fallback {
+
+namespace {
+using namespace simdutf;
+}
+
+class implementation final : public simdutf::implementation {
+public:
+  simdutf_really_inline implementation() : simdutf::implementation(
+      "fallback",
+      "Generic fallback implementation",
+      0
+  ) {}
+  simdutf_warn_unused int detect_encodings(const char * input, size_t length) const noexcept final;
+  simdutf_warn_unused bool validate_utf8(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf8_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_ascii(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_ascii_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16le(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16be(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf32(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  void change_endianness_utf16(const char16_t * buf, size_t length, char16_t * output) const noexcept final;
+  simdutf_warn_unused size_t count_utf16le(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf16be(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf8(const char * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf8(const char * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf8(const char * input, size_t length) const noexcept;
+};
+
+} // namespace fallback
+} // namespace simdutf
+
+#endif // SIMDUTF_FALLBACK_IMPLEMENTATION_H
+/* end file src/simdutf/fallback/implementation.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/fallback/begin.h
+/* begin file src/simdutf/fallback/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "fallback"
+// #define SIMDUTF_IMPLEMENTATION fallback
+/* end file src/simdutf/fallback/begin.h */
+
+// Declarations
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/fallback/bitmanipulation.h
+/* begin file src/simdutf/fallback/bitmanipulation.h */
+#ifndef SIMDUTF_FALLBACK_BITMANIPULATION_H
+#define SIMDUTF_FALLBACK_BITMANIPULATION_H
+
+#include <limits>
+
+namespace simdutf {
+namespace fallback {
+namespace {
+
+#if defined(_MSC_VER) && !defined(_M_ARM64) && !defined(_M_X64)
+static inline unsigned char _BitScanForward64(unsigned long* ret, uint64_t x) {
+  unsigned long x0 = (unsigned long)x, top, bottom;
+  _BitScanForward(&top, (unsigned long)(x >> 32));
+  _BitScanForward(&bottom, x0);
+  *ret = x0 ? bottom : 32 + top;
+  return x != 0;
+}
+static unsigned char _BitScanReverse64(unsigned long* ret, uint64_t x) {
+  unsigned long x1 = (unsigned long)(x >> 32), top, bottom;
+  _BitScanReverse(&top, x1);
+  _BitScanReverse(&bottom, (unsigned long)x);
+  *ret = x1 ? top + 32 : bottom;
+  return x != 0;
+}
+#endif
+
+/* result might be undefined when input_num is zero */
+simdutf_really_inline int leading_zeroes(uint64_t input_num) {
+#ifdef _MSC_VER
+  unsigned long leading_zero = 0;
+  // Search the mask data from most significant bit (MSB)
+  // to least significant bit (LSB) for a set bit (1).
+  if (_BitScanReverse64(&leading_zero, input_num))
+    return (int)(63 - leading_zero);
+  else
+    return 64;
+#else
+  return __builtin_clzll(input_num);
+#endif// _MSC_VER
+}
+
+} // unnamed namespace
+} // namespace fallback
+} // namespace simdutf
+
+#endif // SIMDUTF_FALLBACK_BITMANIPULATION_H
+/* end file src/simdutf/fallback/bitmanipulation.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/fallback/end.h
+/* begin file src/simdutf/fallback/end.h */
+/* end file src/simdutf/fallback/end.h */
+
+#endif // SIMDUTF_IMPLEMENTATION_FALLBACK
+#endif // SIMDUTF_FALLBACK_H
+/* end file src/simdutf/fallback.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/icelake.h
+/* begin file src/simdutf/icelake.h */
+#ifndef SIMDUTF_ICELAKE_H
+#define SIMDUTF_ICELAKE_H
+
+
+
+#ifdef __has_include
+// How do we detect that a compiler supports vbmi2?
+// For sure if the following header is found, we are ok?
+#if __has_include(<avx512vbmi2intrin.h>)
+#define SIMDUTF_COMPILER_SUPPORTS_VBMI2 1
+#endif
+#endif
+
+#ifdef _MSC_VER
+#if _MSC_VER >= 1920
+// Visual Studio 2019 and up support VBMI2 under x64 even if the header
+// avx512vbmi2intrin.h is not found.
+#define SIMDUTF_COMPILER_SUPPORTS_VBMI2 1
+#endif
+#endif
+
+// We allow icelake on x64 as long as the compiler is known to support VBMI2.
+#ifndef SIMDUTF_IMPLEMENTATION_ICELAKE
+#define SIMDUTF_IMPLEMENTATION_ICELAKE ((SIMDUTF_IS_X86_64) && (SIMDUTF_COMPILER_SUPPORTS_VBMI2))
+#endif
+
+// To see why  (__BMI__) && (__PCLMUL__) && (__LZCNT__) are not part of this next line, see
+// https://github.com/simdutf/simdutf/issues/1247
+#define SIMDUTF_CAN_ALWAYS_RUN_ICELAKE ((SIMDUTF_IMPLEMENTATION_ICELAKE) && (SIMDUTF_IS_X86_64) && (__AVX2__) && (SIMDUTF_HAS_AVX512F && \
+                                         SIMDUTF_HAS_AVX512DQ && \
+                                         SIMDUTF_HAS_AVX512VL && \
+                                           SIMDUTF_HAS_AVX512VBMI2))
+
+#if SIMDUTF_IMPLEMENTATION_ICELAKE
+#if SIMDUTF_CAN_ALWAYS_RUN_ICELAKE
+#define SIMDUTF_TARGET_ICELAKE
+#define SIMDJSON_UNTARGET_ICELAKE
+#else
+#define SIMDUTF_TARGET_ICELAKE SIMDUTF_TARGET_REGION("avx512f,avx512dq,avx512cd,avx512bw,avx512vbmi,avx512vbmi2,avx512vl,avx2,bmi,bmi2,pclmul,lzcnt")
+#define SIMDUTF_UNTARGET_ICELAKE SIMDUTF_UNTARGET_REGION
+#endif
+
+namespace simdutf {
+namespace icelake {
+} // namespace icelake
+} // namespace simdutf
+
+
+
+//
+// These two need to be included outside SIMDUTF_TARGET_REGION
+//
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/icelake/intrinsics.h
+/* begin file src/simdutf/icelake/intrinsics.h */
+#ifndef SIMDUTF_ICELAKE_INTRINSICS_H
+#define SIMDUTF_ICELAKE_INTRINSICS_H
+
+
+#ifdef SIMDUTF_VISUAL_STUDIO
+// under clang within visual studio, this will include <x86intrin.h>
+#include <intrin.h>  // visual studio or clang
+#include <immintrin.h>
+#else
+#include <x86intrin.h> // elsewhere
+#ifndef _tzcnt_u64
+#define _tzcnt_u64(x) __tzcnt_u64(x)
+#endif // _tzcnt_u64
+#endif // SIMDUTF_VISUAL_STUDIO
+
+#ifdef SIMDUTF_CLANG_VISUAL_STUDIO
+/**
+ * You are not supposed, normally, to include these
+ * headers directly. Instead you should either include intrin.h
+ * or x86intrin.h. However, when compiling with clang
+ * under Windows (i.e., when _MSC_VER is set), these headers
+ * only get included *if* the corresponding features are detected
+ * from macros:
+ * e.g., if __AVX2__ is set... in turn,  we normally set these
+ * macros by compiling against the corresponding architecture
+ * (e.g., arch:AVX2, -mavx2, etc.) which compiles the whole
+ * software with these advanced instructions. In simdutf, we
+ * want to compile the whole program for a generic target,
+ * and only target our specific kernels. As a workaround,
+ * we directly include the needed headers. These headers would
+ * normally guard against such usage, but we carefully included
+ * <x86intrin.h>  (or <intrin.h>) before, so the headers
+ * are fooled.
+ */
+#include <bmiintrin.h>   // for _blsr_u64
+#include <bmi2intrin.h>  // for _pext_u64, _pdep_u64
+#include <lzcntintrin.h> // for  __lzcnt64
+#include <immintrin.h>   // for most things (AVX2, AVX512, _popcnt64)
+#include <smmintrin.h>
+#include <tmmintrin.h>
+#include <avxintrin.h>
+#include <avx2intrin.h>
+#include <wmmintrin.h>   // for  _mm_clmulepi64_si128
+// Important: we need the AVX-512 headers:
+#include <avx512fintrin.h>
+#include <avx512dqintrin.h>
+#include <avx512cdintrin.h>
+#include <avx512bwintrin.h>
+#include <avx512vlintrin.h>
+#include <avx512vlbwintrin.h>
+#include <avx512vbmiintrin.h>
+#include <avx512vbmi2intrin.h>
+// unfortunately, we may not get _blsr_u64, but, thankfully, clang
+// has it as a macro.
+#ifndef _blsr_u64
+// we roll our own
+#define _blsr_u64(n) ((n - 1) & n)
+#endif //  _blsr_u64
+#endif // SIMDUTF_CLANG_VISUAL_STUDIO
+
+
+
+#if defined(__GNUC__) && !defined(__clang__)
+#if __GNUC__ == 8
+#define SIMDUTF_GCC8 1
+#endif //  __GNUC__ == 8
+#endif // defined(__GNUC__) && !defined(__clang__)
+
+#if SIMDUTF_GCC8
+/**
+ * GCC 8 fails to provide _mm512_set_epi8. We roll our own.
+ */
+inline __m512i _mm512_set_epi8(uint8_t a0, uint8_t a1, uint8_t a2, uint8_t a3, uint8_t a4, uint8_t a5, uint8_t a6, uint8_t a7, uint8_t a8, uint8_t a9, uint8_t a10, uint8_t a11, uint8_t a12, uint8_t a13, uint8_t a14, uint8_t a15, uint8_t a16, uint8_t a17, uint8_t a18, uint8_t a19, uint8_t a20, uint8_t a21, uint8_t a22, uint8_t a23, uint8_t a24, uint8_t a25, uint8_t a26, uint8_t a27, uint8_t a28, uint8_t a29, uint8_t a30, uint8_t a31, uint8_t a32, uint8_t a33, uint8_t a34, uint8_t a35, uint8_t a36, uint8_t a37, uint8_t a38, uint8_t a39, uint8_t a40, uint8_t a41, uint8_t a42, uint8_t a43, uint8_t a44, uint8_t a45, uint8_t a46, uint8_t a47, uint8_t a48, uint8_t a49, uint8_t a50, uint8_t a51, uint8_t a52, uint8_t a53, uint8_t a54, uint8_t a55, uint8_t a56, uint8_t a57, uint8_t a58, uint8_t a59, uint8_t a60, uint8_t a61, uint8_t a62, uint8_t a63) {
+  return _mm512_set_epi64(uint64_t(a7) + (uint64_t(a6) << 8) + (uint64_t(a5) << 16) + (uint64_t(a4) << 24) + (uint64_t(a3) << 32) + (uint64_t(a2) << 40) + (uint64_t(a1) << 48) + (uint64_t(a0) << 56),
+                          uint64_t(a15) + (uint64_t(a14) << 8) + (uint64_t(a13) << 16) + (uint64_t(a12) << 24) + (uint64_t(a11) << 32) + (uint64_t(a10) << 40) + (uint64_t(a9) << 48) + (uint64_t(a8) << 56),
+                          uint64_t(a23) + (uint64_t(a22) << 8) + (uint64_t(a21) << 16) + (uint64_t(a20) << 24) + (uint64_t(a19) << 32) + (uint64_t(a18) << 40) + (uint64_t(a17) << 48) + (uint64_t(a16) << 56),
+                          uint64_t(a31) + (uint64_t(a30) << 8) + (uint64_t(a29) << 16) + (uint64_t(a28) << 24) + (uint64_t(a27) << 32) + (uint64_t(a26) << 40) + (uint64_t(a25) << 48) + (uint64_t(a24) << 56),
+                          uint64_t(a39) + (uint64_t(a38) << 8) + (uint64_t(a37) << 16) + (uint64_t(a36) << 24) + (uint64_t(a35) << 32) + (uint64_t(a34) << 40) + (uint64_t(a33) << 48) + (uint64_t(a32) << 56),
+                          uint64_t(a47) + (uint64_t(a46) << 8) + (uint64_t(a45) << 16) + (uint64_t(a44) << 24) + (uint64_t(a43) << 32) + (uint64_t(a42) << 40) + (uint64_t(a41) << 48) + (uint64_t(a40) << 56),
+                          uint64_t(a55) + (uint64_t(a54) << 8) + (uint64_t(a53) << 16) + (uint64_t(a52) << 24) + (uint64_t(a51) << 32) + (uint64_t(a50) << 40) + (uint64_t(a49) << 48) + (uint64_t(a48) << 56),
+                          uint64_t(a63) + (uint64_t(a62) << 8) + (uint64_t(a61) << 16) + (uint64_t(a60) << 24) + (uint64_t(a59) << 32) + (uint64_t(a58) << 40) + (uint64_t(a57) << 48) + (uint64_t(a56) << 56));
+}
+#endif // SIMDUTF_GCC8
+
+#endif // SIMDUTF_HASWELL_INTRINSICS_H
+/* end file src/simdutf/icelake/intrinsics.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/icelake/implementation.h
+/* begin file src/simdutf/icelake/implementation.h */
+#ifndef SIMDUTF_ICELAKE_IMPLEMENTATION_H
+#define SIMDUTF_ICELAKE_IMPLEMENTATION_H
+
+
+namespace simdutf {
+namespace icelake {
+
+namespace {
+using namespace simdutf;
+}
+
+class implementation final : public simdutf::implementation {
+public:
+  simdutf_really_inline implementation() : simdutf::implementation(
+      "icelake",
+      "Intel AVX512 (AVX-512BW, AVX-512CD, AVX-512VL, AVX-512VBMI2 extensions)",
+      internal::instruction_set::AVX2 | internal::instruction_set::PCLMULQDQ | internal::instruction_set::BMI1 | internal::instruction_set::BMI2 | internal::instruction_set::AVX512BW | internal::instruction_set::AVX512CD | internal::instruction_set::AVX512VL | internal::instruction_set::AVX512VBMI2 ) {}
+  simdutf_warn_unused int detect_encodings(const char * input, size_t length) const noexcept final;
+  simdutf_warn_unused bool validate_utf8(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf8_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_ascii(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_ascii_with_errors(const char *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16le(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf16be(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused bool validate_utf32(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused result validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * buf, size_t len, char32_t* utf32_output) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) const noexcept final;
+  void change_endianness_utf16(const char16_t * buf, size_t length, char16_t * output) const noexcept final;
+  simdutf_warn_unused size_t count_utf16le(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf16be(const char16_t * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t count_utf8(const char * buf, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf8(const char * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept;
+  simdutf_warn_unused size_t utf32_length_from_utf8(const char * input, size_t length) const noexcept;
+};
+
+} // namespace icelake
+} // namespace simdutf
+
+#endif // SIMDUTF_ICELAKE_IMPLEMENTATION_H
+/* end file src/simdutf/icelake/implementation.h */
+
+//
+// The rest need to be inside the region
+//
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/icelake/begin.h
+/* begin file src/simdutf/icelake/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "icelake"
+// #define SIMDUTF_IMPLEMENTATION icelake
+SIMDUTF_TARGET_ICELAKE
+
+/* end file src/simdutf/icelake/begin.h */
+// Declarations
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/icelake/bitmanipulation.h
+/* begin file src/simdutf/icelake/bitmanipulation.h */
+#ifndef SIMDUTF_ICELAKE_BITMANIPULATION_H
+#define SIMDUTF_ICELAKE_BITMANIPULATION_H
+
+namespace simdutf {
+namespace icelake {
+namespace {
+
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+simdutf_really_inline unsigned __int64 count_ones(uint64_t input_num) {
+  // note: we do not support legacy 32-bit Windows
+  return __popcnt64(input_num);// Visual Studio wants two underscores
+}
+#else
+simdutf_really_inline long long int count_ones(uint64_t input_num) {
+  return _popcnt64(input_num);
+}
+#endif
+
+} // unnamed namespace
+} // namespace icelake
+} // namespace simdutf
+
+#endif // SIMDUTF_ICELAKE_BITMANIPULATION_H
+/* end file src/simdutf/icelake/bitmanipulation.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/icelake/end.h
+/* begin file src/simdutf/icelake/end.h */
+SIMDUTF_UNTARGET_REGION
+/* end file src/simdutf/icelake/end.h */
+
+
+
+#endif // SIMDUTF_IMPLEMENTATION_ICELAKE
+#endif // SIMDUTF_ICELAKE_H
+/* end file src/simdutf/icelake.h */
+
+namespace simdutf {
+bool implementation::supported_by_runtime_system() const {
+  uint32_t required_instruction_sets = this->required_instruction_sets();
+  uint32_t supported_instruction_sets = internal::detect_supported_architectures();
+  return ((supported_instruction_sets & required_instruction_sets) == required_instruction_sets);
+}
+
+simdutf_warn_unused encoding_type implementation::autodetect_encoding(const char * input, size_t length) const noexcept {
+    // If there is a BOM, then we trust it.
+    auto bom_encoding = simdutf::BOM::check_bom(input, length);
+    if(bom_encoding != encoding_type::unspecified) { return bom_encoding; }
+    // UTF8 is common, it includes ASCII, and is commonly represented
+    // without a BOM, so if it fits, go with that. Note that it is still
+    // possible to get it wrong, we are only 'guessing'. If some has UTF-16
+    // data without a BOM, it could pass as UTF-8.
+    //
+    // An interesting twist might be to check for UTF-16 ASCII first (every
+    // other byte is zero).
+    if(validate_utf8(input, length)) { return encoding_type::UTF8; }
+    // The next most common encoding that might appear without BOM is probably
+    // UTF-16LE, so try that next.
+    if((length % 2) == 0) {
+      // important: we need to divide by two
+      if(validate_utf16le(reinterpret_cast<const char16_t*>(input), length/2)) { return encoding_type::UTF16_LE; }
+    }
+    if((length % 4) == 0) {
+      if(validate_utf32(reinterpret_cast<const char32_t*>(input), length/4)) { return encoding_type::UTF32_LE; }
+    }
+    return encoding_type::unspecified;
+}
+
+namespace internal {
+
+// Static array of known implementations. We're hoping these get baked into the executable
+// without requiring a static initializer.
+
+
+#if SIMDUTF_IMPLEMENTATION_ICELAKE
+const icelake::implementation icelake_singleton{};
+#endif
+#if SIMDUTF_IMPLEMENTATION_HASWELL
+const haswell::implementation haswell_singleton{};
+#endif
+#if SIMDUTF_IMPLEMENTATION_WESTMERE
+const westmere::implementation westmere_singleton{};
+#endif
+#if SIMDUTF_IMPLEMENTATION_ARM64
+const arm64::implementation arm64_singleton{};
+#endif
+#if SIMDUTF_IMPLEMENTATION_PPC64
+const ppc64::implementation ppc64_singleton{};
+#endif
+#if SIMDUTF_IMPLEMENTATION_FALLBACK
+const fallback::implementation fallback_singleton{};
+#endif
+
+/**
+ * @private Detects best supported implementation on first use, and sets it
+ */
+class detect_best_supported_implementation_on_first_use final : public implementation {
+public:
+  const std::string &name() const noexcept final { return set_best()->name(); }
+  const std::string &description() const noexcept final { return set_best()->description(); }
+  uint32_t required_instruction_sets() const noexcept final { return set_best()->required_instruction_sets(); }
+
+  simdutf_warn_unused int detect_encodings(const char * input, size_t length) const noexcept override {
+    return set_best()->detect_encodings(input, length);
+  }
+
+  simdutf_warn_unused bool validate_utf8(const char * buf, size_t len) const noexcept final override {
+    return set_best()->validate_utf8(buf, len);
+  }
+
+  simdutf_warn_unused result validate_utf8_with_errors(const char * buf, size_t len) const noexcept final override {
+    return set_best()->validate_utf8_with_errors(buf, len);
+  }
+
+  simdutf_warn_unused bool validate_ascii(const char * buf, size_t len) const noexcept final override {
+    return set_best()->validate_ascii(buf, len);
+  }
+
+  simdutf_warn_unused result validate_ascii_with_errors(const char * buf, size_t len) const noexcept final override {
+    return set_best()->validate_ascii_with_errors(buf, len);
+  }
+
+  simdutf_warn_unused bool validate_utf16le(const char16_t * buf, size_t len) const noexcept final override {
+    return set_best()->validate_utf16le(buf, len);
+  }
+
+  simdutf_warn_unused bool validate_utf16be(const char16_t * buf, size_t len) const noexcept final override {
+    return set_best()->validate_utf16be(buf, len);
+  }
+
+  simdutf_warn_unused result validate_utf16le_with_errors(const char16_t * buf, size_t len) const noexcept final override {
+    return set_best()->validate_utf16le_with_errors(buf, len);
+  }
+
+  simdutf_warn_unused result validate_utf16be_with_errors(const char16_t * buf, size_t len) const noexcept final override {
+    return set_best()->validate_utf16be_with_errors(buf, len);
+  }
+
+  simdutf_warn_unused bool validate_utf32(const char32_t * buf, size_t len) const noexcept final override {
+    return set_best()->validate_utf32(buf, len);
+  }
+
+  simdutf_warn_unused result validate_utf32_with_errors(const char32_t * buf, size_t len) const noexcept final override {
+    return set_best()->validate_utf32_with_errors(buf, len);
+  }
+
+  simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_utf8_to_utf16le(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_utf8_to_utf16be(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_utf8_to_utf16le_with_errors(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_utf8_to_utf16be_with_errors(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_valid_utf8_to_utf16le(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_valid_utf8_to_utf16be(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_utf8_to_utf32(buf, len, utf32_output);
+  }
+
+  simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_utf8_to_utf32_with_errors(buf, len, utf32_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_valid_utf8_to_utf32(buf, len, utf32_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_utf16le_to_utf8(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_utf16be_to_utf8(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_utf16le_to_utf8_with_errors(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_utf16be_to_utf8_with_errors(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_valid_utf16le_to_utf8(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_valid_utf16be_to_utf8(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_utf32_to_utf8(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_utf32_to_utf8_with_errors(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_output) const noexcept final override {
+    return set_best()->convert_valid_utf32_to_utf8(buf, len, utf8_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_utf32_to_utf16le(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_utf32_to_utf16be(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_utf32_to_utf16le_with_errors(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_utf32_to_utf16be_with_errors(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_valid_utf32_to_utf16le(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_output) const noexcept final override {
+    return set_best()->convert_valid_utf32_to_utf16be(buf, len, utf16_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_utf16le_to_utf32(buf, len, utf32_output);
+  }
+
+  simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_utf16be_to_utf32(buf, len, utf32_output);
+  }
+
+  simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_utf16le_to_utf32_with_errors(buf, len, utf32_output);
+  }
+
+  simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_utf16be_to_utf32_with_errors(buf, len, utf32_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_valid_utf16le_to_utf32(buf, len, utf32_output);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_output) const noexcept final override {
+    return set_best()->convert_valid_utf16be_to_utf32(buf, len, utf32_output);
+  }
+
+  void change_endianness_utf16(const char16_t * buf, size_t len, char16_t * output) const noexcept final override {
+    set_best()->change_endianness_utf16(buf, len, output);
+  }
+
+  simdutf_warn_unused size_t count_utf16le(const char16_t * buf, size_t len) const noexcept final override {
+    return set_best()->count_utf16le(buf, len);
+  }
+
+  simdutf_warn_unused size_t count_utf16be(const char16_t * buf, size_t len) const noexcept final override {
+    return set_best()->count_utf16be(buf, len);
+  }
+
+  simdutf_warn_unused size_t count_utf8(const char * buf, size_t len) const noexcept final override {
+    return set_best()->count_utf8(buf, len);
+  }
+
+  simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * buf, size_t len) const noexcept override {
+    return set_best()->utf8_length_from_utf16le(buf, len);
+  }
+
+  simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * buf, size_t len) const noexcept override {
+    return set_best()->utf8_length_from_utf16be(buf, len);
+  }
+
+  simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * buf, size_t len) const noexcept override {
+    return set_best()->utf32_length_from_utf16le(buf, len);
+  }
+
+  simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * buf, size_t len) const noexcept override {
+    return set_best()->utf32_length_from_utf16be(buf, len);
+  }
+
+  simdutf_warn_unused size_t utf16_length_from_utf8(const char * buf, size_t len) const noexcept override {
+    return set_best()->utf16_length_from_utf8(buf, len);
+  }
+
+  simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * buf, size_t len) const noexcept override {
+    return set_best()->utf8_length_from_utf32(buf, len);
+  }
+
+  simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * buf, size_t len) const noexcept override {
+    return set_best()->utf16_length_from_utf32(buf, len);
+  }
+
+  simdutf_warn_unused size_t utf32_length_from_utf8(const char * buf, size_t len) const noexcept override {
+    return set_best()->utf32_length_from_utf8(buf, len);
+  }
+
+  simdutf_really_inline detect_best_supported_implementation_on_first_use() noexcept : implementation("best_supported_detector", "Detects the best supported implementation and sets it", 0) {}
+
+private:
+  const implementation *set_best() const noexcept;
+};
+
+const detect_best_supported_implementation_on_first_use detect_best_supported_implementation_on_first_use_singleton;
+
+const std::initializer_list<const implementation *> available_implementation_pointers {
+#if SIMDUTF_IMPLEMENTATION_ICELAKE
+  &icelake_singleton,
+#endif
+#if SIMDUTF_IMPLEMENTATION_HASWELL
+  &haswell_singleton,
+#endif
+#if SIMDUTF_IMPLEMENTATION_WESTMERE
+  &westmere_singleton,
+#endif
+#if SIMDUTF_IMPLEMENTATION_ARM64
+  &arm64_singleton,
+#endif
+#if SIMDUTF_IMPLEMENTATION_PPC64
+  &ppc64_singleton,
+#endif
+#if SIMDUTF_IMPLEMENTATION_FALLBACK
+  &fallback_singleton,
+#endif
+}; // available_implementation_pointers
+
+// So we can return UNSUPPORTED_ARCHITECTURE from the parser when there is no support
+class unsupported_implementation final : public implementation {
+public:
+  simdutf_warn_unused int detect_encodings(const char *, size_t) const noexcept override {
+    return encoding_type::unspecified;
+  }
+
+  simdutf_warn_unused bool validate_utf8(const char *, size_t) const noexcept final override {
+    return false; // Just refuse to validate. Given that we have a fallback implementation
+    // it seems unlikely that unsupported_implementation will ever be used. If it is used,
+    // then it will flag all strings as invalid. The alternative is to return an error_code
+    // from which the user has to figure out whether the string is valid UTF-8... which seems
+    // like a lot of work just to handle the very unlikely case that we have an unsupported
+    // implementation. And, when it does happen (that we have an unsupported implementation),
+    // what are the chances that the programmer has a fallback? Given that *we* provide the
+    // fallback, it implies that the programmer would need a fallback for our fallback.
+  }
+
+  simdutf_warn_unused result validate_utf8_with_errors(const char *, size_t) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused bool validate_ascii(const char *, size_t) const noexcept final override {
+    return false;
+  }
+
+  simdutf_warn_unused result validate_ascii_with_errors(const char *, size_t) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused bool validate_utf16le(const char16_t*, size_t) const noexcept final override {
+    return false;
+  }
+
+  simdutf_warn_unused bool validate_utf16be(const char16_t*, size_t) const noexcept final override {
+    return false;
+  }
+
+  simdutf_warn_unused result validate_utf16le_with_errors(const char16_t*, size_t) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused result validate_utf16be_with_errors(const char16_t*, size_t) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused bool validate_utf32(const char32_t*, size_t) const noexcept final override {
+    return false;
+  }
+
+  simdutf_warn_unused result validate_utf32_with_errors(const char32_t*, size_t) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused size_t convert_utf8_to_utf16le(const char*, size_t, char16_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf8_to_utf16be(const char*, size_t, char16_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char*, size_t, char16_t*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char*, size_t, char16_t*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char*, size_t, char16_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char*, size_t, char16_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf8_to_utf32(const char*, size_t, char32_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char*, size_t, char32_t*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char*, size_t, char32_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t*, size_t, char*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t*, size_t, char*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t*, size_t, char*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t*, size_t, char*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t*, size_t, char*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t*, size_t, char*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t*, size_t, char*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t*, size_t, char*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t*, size_t, char*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t*, size_t, char16_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t*, size_t, char16_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t*, size_t, char16_t*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t*, size_t, char16_t*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t*, size_t, char16_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t*, size_t, char16_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t*, size_t, char32_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t*, size_t, char32_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t*, size_t, char32_t*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t*, size_t, char32_t*) const noexcept final override {
+    return result(error_code::OTHER, 0);
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t*, size_t, char32_t*) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t*, size_t, char32_t*) const noexcept final override {
+    return 0;
+  }
+
+  void change_endianness_utf16(const char16_t *, size_t, char16_t *) const noexcept final override {
+
+  }
+
+  simdutf_warn_unused size_t count_utf16le(const char16_t *, size_t) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t count_utf16be(const char16_t *, size_t) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t count_utf8(const char *, size_t) const noexcept final override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t *, size_t) const noexcept override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t *, size_t) const noexcept override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t *, size_t) const noexcept override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t *, size_t) const noexcept override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t utf16_length_from_utf8(const char *, size_t) const noexcept override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t *, size_t) const noexcept override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t *, size_t) const noexcept override {
+    return 0;
+  }
+
+  simdutf_warn_unused size_t utf32_length_from_utf8(const char *, size_t) const noexcept override {
+    return 0;
+  }
+
+  unsupported_implementation() : implementation("unsupported", "Unsupported CPU (no detected SIMD instructions)", 0) {}
+};
+
+const unsupported_implementation unsupported_singleton{};
+
+size_t available_implementation_list::size() const noexcept {
+  return internal::available_implementation_pointers.size();
+}
+const implementation * const *available_implementation_list::begin() const noexcept {
+  return internal::available_implementation_pointers.begin();
+}
+const implementation * const *available_implementation_list::end() const noexcept {
+  return internal::available_implementation_pointers.end();
+}
+const implementation *available_implementation_list::detect_best_supported() const noexcept {
+  // They are prelisted in priority order, so we just go down the list
+  uint32_t supported_instruction_sets = internal::detect_supported_architectures();
+  for (const implementation *impl : internal::available_implementation_pointers) {
+    uint32_t required_instruction_sets = impl->required_instruction_sets();
+    if ((supported_instruction_sets & required_instruction_sets) == required_instruction_sets) { return impl; }
+  }
+  return &unsupported_singleton; // this should never happen?
+}
+
+const implementation *detect_best_supported_implementation_on_first_use::set_best() const noexcept {
+  SIMDUTF_PUSH_DISABLE_WARNINGS
+  SIMDUTF_DISABLE_DEPRECATED_WARNING // Disable CRT_SECURE warning on MSVC: manually verified this is safe
+  char *force_implementation_name = getenv("SIMDUTF_FORCE_IMPLEMENTATION");
+  SIMDUTF_POP_DISABLE_WARNINGS
+
+  if (force_implementation_name) {
+    auto force_implementation = available_implementations[force_implementation_name];
+    if (force_implementation) {
+      return active_implementation = force_implementation;
+    } else {
+      // Note: abort() and stderr usage within the library is forbidden.
+      return active_implementation = &unsupported_singleton;
+    }
+  }
+  return active_implementation = available_implementations.detect_best_supported();
+}
+
+} // namespace internal
+
+SIMDUTF_DLLIMPORTEXPORT const internal::available_implementation_list available_implementations{};
+SIMDUTF_DLLIMPORTEXPORT internal::atomic_ptr<const implementation> active_implementation{&internal::detect_best_supported_implementation_on_first_use_singleton};
+
+simdutf_warn_unused bool validate_utf8(const char *buf, size_t len) noexcept {
+  return active_implementation->validate_utf8(buf, len);
+}
+simdutf_warn_unused result validate_utf8_with_errors(const char *buf, size_t len) noexcept {
+  return active_implementation->validate_utf8_with_errors(buf, len);
+}
+simdutf_warn_unused bool validate_ascii(const char *buf, size_t len) noexcept {
+  return active_implementation->validate_ascii(buf, len);
+}
+simdutf_warn_unused result validate_ascii_with_errors(const char *buf, size_t len) noexcept {
+  return active_implementation->validate_ascii_with_errors(buf, len);
+}
+simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * input, size_t length, char16_t* utf16_output) noexcept {
+  return active_implementation->convert_utf8_to_utf16le(input, length, utf16_output);
+}
+simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * input, size_t length, char16_t* utf16_output) noexcept {
+  return active_implementation->convert_utf8_to_utf16be(input, length, utf16_output);
+}
+simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * input, size_t length, char16_t* utf16_output) noexcept {
+  return active_implementation->convert_utf8_to_utf16le_with_errors(input, length, utf16_output);
+}
+simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * input, size_t length, char16_t* utf16_output) noexcept {
+  return active_implementation->convert_utf8_to_utf16be_with_errors(input, length, utf16_output);
+}
+simdutf_warn_unused size_t convert_utf8_to_utf32(const char * input, size_t length, char32_t* utf32_output) noexcept {
+  return active_implementation->convert_utf8_to_utf32(input, length, utf32_output);
+}
+simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * input, size_t length, char32_t* utf32_output) noexcept {
+  return active_implementation->convert_utf8_to_utf32_with_errors(input, length, utf32_output);
+}
+simdutf_warn_unused bool validate_utf16le(const char16_t * buf, size_t len) noexcept {
+  return active_implementation->validate_utf16le(buf, len);
+}
+simdutf_warn_unused bool validate_utf16be(const char16_t * buf, size_t len) noexcept {
+  return active_implementation->validate_utf16be(buf, len);
+}
+simdutf_warn_unused result validate_utf16le_with_errors(const char16_t * buf, size_t len) noexcept {
+  return active_implementation->validate_utf16le_with_errors(buf, len);
+}
+simdutf_warn_unused result validate_utf16be_with_errors(const char16_t * buf, size_t len) noexcept {
+  return active_implementation->validate_utf16be_with_errors(buf, len);
+}
+simdutf_warn_unused bool validate_utf32(const char32_t * buf, size_t len) noexcept {
+  return active_implementation->validate_utf32(buf, len);
+}
+simdutf_warn_unused result validate_utf32_with_errors(const char32_t * buf, size_t len) noexcept {
+  return active_implementation->validate_utf32_with_errors(buf, len);
+}
+simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * input, size_t length, char16_t* utf16_buffer) noexcept {
+  return active_implementation->convert_valid_utf8_to_utf16le(input, length, utf16_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * input, size_t length, char16_t* utf16_buffer) noexcept {
+  return active_implementation->convert_valid_utf8_to_utf16be(input, length, utf16_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * input, size_t length, char32_t* utf32_buffer) noexcept {
+  return active_implementation->convert_valid_utf8_to_utf32(input, length, utf32_buffer);
+}
+simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_utf16le_to_utf8(buf, len, utf8_buffer);
+}
+simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_utf16be_to_utf8(buf, len, utf8_buffer);
+}
+simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_utf16le_to_utf8_with_errors(buf, len, utf8_buffer);
+}
+simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_utf16be_to_utf8_with_errors(buf, len, utf8_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_valid_utf16le_to_utf8(buf, len, utf8_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_valid_utf16be_to_utf8(buf, len, utf8_buffer);
+}
+simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_utf32_to_utf8(buf, len, utf8_buffer);
+}
+simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_utf32_to_utf8_with_errors(buf, len, utf8_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * buf, size_t len, char* utf8_buffer) noexcept {
+  return active_implementation->convert_valid_utf32_to_utf8(buf, len, utf8_buffer);
+}
+simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) noexcept {
+  return active_implementation->convert_utf32_to_utf16le(buf, len, utf16_buffer);
+}
+simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) noexcept {
+  return active_implementation->convert_utf32_to_utf16be(buf, len, utf16_buffer);
+}
+simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) noexcept {
+  return active_implementation->convert_utf32_to_utf16le_with_errors(buf, len, utf16_buffer);
+}
+simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * buf, size_t len, char16_t* utf16_buffer) noexcept {
+  return active_implementation->convert_utf32_to_utf16be_with_errors(buf, len, utf16_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * buf, size_t len, char16_t* utf16_buffer) noexcept {
+  return active_implementation->convert_valid_utf32_to_utf16le(buf, len, utf16_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * buf, size_t len, char16_t* utf16_buffer) noexcept {
+  return active_implementation->convert_valid_utf32_to_utf16be(buf, len, utf16_buffer);
+}
+simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) noexcept {
+  return active_implementation->convert_utf16le_to_utf32(buf, len, utf32_buffer);
+}
+simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) noexcept {
+  return active_implementation->convert_utf16be_to_utf32(buf, len, utf32_buffer);
+}
+simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) noexcept {
+  return active_implementation->convert_utf16le_to_utf32_with_errors(buf, len, utf32_buffer);
+}
+simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * buf, size_t len, char32_t* utf32_buffer) noexcept {
+  return active_implementation->convert_utf16be_to_utf32_with_errors(buf, len, utf32_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) noexcept {
+  return active_implementation->convert_valid_utf16le_to_utf32(buf, len, utf32_buffer);
+}
+simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * buf, size_t len, char32_t* utf32_buffer) noexcept {
+  return active_implementation->convert_valid_utf16be_to_utf32(buf, len, utf32_buffer);
+}
+void change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) noexcept {
+  active_implementation->change_endianness_utf16(input, length, output);
+}
+simdutf_warn_unused size_t count_utf16le(const char16_t * input, size_t length) noexcept {
+  return active_implementation->count_utf16le(input, length);
+}
+simdutf_warn_unused size_t count_utf16be(const char16_t * input, size_t length) noexcept {
+  return active_implementation->count_utf16be(input, length);
+}
+simdutf_warn_unused size_t count_utf8(const char * input, size_t length) noexcept {
+  return active_implementation->count_utf8(input, length);
+}
+simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * input, size_t length) noexcept {
+  return active_implementation->utf8_length_from_utf16le(input, length);
+}
+simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * input, size_t length) noexcept {
+  return active_implementation->utf8_length_from_utf16be(input, length);
+}
+simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * input, size_t length) noexcept {
+  return active_implementation->utf32_length_from_utf16le(input, length);
+}
+simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * input, size_t length) noexcept {
+  return active_implementation->utf32_length_from_utf16be(input, length);
+}
+simdutf_warn_unused size_t utf16_length_from_utf8(const char * input, size_t length) noexcept {
+  return active_implementation->utf16_length_from_utf8(input, length);
+}
+simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * input, size_t length) noexcept {
+  return active_implementation->utf8_length_from_utf32(input, length);
+}
+simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * input, size_t length) noexcept {
+  return active_implementation->utf16_length_from_utf32(input, length);
+}
+simdutf_warn_unused size_t utf32_length_from_utf8(const char * input, size_t length) noexcept {
+  return active_implementation->utf32_length_from_utf8(input, length);
+}
+simdutf_warn_unused simdutf::encoding_type autodetect_encoding(const char * buf, size_t length) noexcept {
+  return active_implementation->autodetect_encoding(buf, length);
+}
+simdutf_warn_unused int detect_encodings(const char * buf, size_t length) noexcept {
+  return active_implementation->detect_encodings(buf, length);
+}
+
+const implementation * builtin_implementation() {
+  static const implementation * builtin_impl = available_implementations[SIMDUTF_STRINGIFY(SIMDUTF_BUILTIN_IMPLEMENTATION)];
+  return builtin_impl;
+}
+
+
+} // namespace simdutf
+
+/* end file src/implementation.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=encoding_types.cpp
+/* begin file src/encoding_types.cpp */
+
+namespace simdutf {
+std::string to_string(encoding_type bom) {
+  switch (bom) {
+      case UTF16_LE:     return "UTF16 little-endian";
+      case UTF16_BE:     return "UTF16 big-endian";
+      case UTF32_LE:     return "UTF32 little-endian";
+      case UTF32_BE:     return "UTF32 big-endian";
+      case UTF8:         return "UTF8";
+      case unspecified:  return "unknown";
+      default:           return "error";
+  }
+}
+
+namespace BOM {
+// Note that BOM for UTF8 is discouraged.
+encoding_type check_bom(const uint8_t* byte, size_t length) {
+        if (length >= 2 && byte[0] == 0xff and byte[1] == 0xfe) {
+            if (length >= 4 && byte[2] == 0x00 and byte[3] == 0x0) {
+                return encoding_type::UTF32_LE;
+            } else {
+                return encoding_type::UTF16_LE;
+            }
+        } else if (length >= 2 && byte[0] == 0xfe and byte[1] == 0xff) {
+            return encoding_type::UTF16_BE;
+        } else if (length >= 4 && byte[0] == 0x00 and byte[1] == 0x00 and byte[2] == 0xfe and byte[3] == 0xff) {
+            return encoding_type::UTF32_BE;
+        } else if (length >= 4 && byte[0] == 0xef and byte[1] == 0xbb and byte[3] == 0xbf) {
+            return encoding_type::UTF8;
+        }
+        return encoding_type::unspecified;
+    }
+
+encoding_type check_bom(const char* byte, size_t length) {
+      return check_bom(reinterpret_cast<const uint8_t*>(byte), length);
+ }
+
+ size_t bom_byte_size(encoding_type bom) {
+        switch (bom) {
+            case UTF16_LE:     return 2;
+            case UTF16_BE:     return 2;
+            case UTF32_LE:     return 4;
+            case UTF32_BE:     return 4;
+            case UTF8:         return 3;
+            case unspecified:  return 0;
+            default:           return 0;
+        }
+}
+
+}
+}
+/* end file src/encoding_types.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=error.cpp
+/* begin file src/error.cpp */
+namespace simdutf {
+
+  simdutf_really_inline result::result() : error{error_code::SUCCESS}, count{0} {};
+
+  simdutf_really_inline result::result(error_code _err, size_t _pos) : error{_err}, count{_pos} {};
+
+}
+/* end file src/error.cpp */
+// The large tables should be included once and they
+// should not depend on a kernel.
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=tables/utf8_to_utf16_tables.h
+/* begin file src/tables/utf8_to_utf16_tables.h */
+#ifndef SIMDUTF_UTF8_TO_UTF16_TABLES_H
+#define SIMDUTF_UTF8_TO_UTF16_TABLES_H
+#include <cstdint>
+
+namespace simdutf {
+namespace {
+namespace tables {
+namespace utf8_to_utf16 {
+/**
+ * utf8bigindex uses about 8 kB
+ * shufutf8 uses about 3344 B
+ *
+ * So we use a bit over 11 kB. It would be
+ * easy to save about 4 kB by only
+ * storing the index in utf8bigindex, and
+ * deriving the consumed bytes otherwise.
+ * However, this may come at a significant (10% to 20%)
+ * performance penalty.
+ */
+
+const uint8_t shufutf8[209][16] =
+{	{0, 255, 1, 255, 2, 255, 3, 255, 4, 255, 5, 255, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 2, 255, 3, 255, 4, 255, 6, 5, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 2, 255, 3, 255, 5, 4, 6, 255, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 2, 255, 3, 255, 5, 4, 7, 6, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 2, 255, 4, 3, 5, 255, 6, 255, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 2, 255, 4, 3, 5, 255, 7, 6, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 2, 255, 4, 3, 6, 5, 7, 255, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 2, 255, 4, 3, 6, 5, 8, 7, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 3, 2, 4, 255, 5, 255, 6, 255, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 3, 2, 4, 255, 5, 255, 7, 6, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 3, 2, 4, 255, 6, 5, 7, 255, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 3, 2, 4, 255, 6, 5, 8, 7, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 3, 2, 5, 4, 6, 255, 7, 255, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 3, 2, 5, 4, 6, 255, 8, 7, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 3, 2, 5, 4, 7, 6, 8, 255, 0, 0, 0, 0},
+ 	{0, 255, 1, 255, 3, 2, 5, 4, 7, 6, 9, 8, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 3, 255, 4, 255, 5, 255, 6, 255, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 3, 255, 4, 255, 5, 255, 7, 6, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 3, 255, 4, 255, 6, 5, 7, 255, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 3, 255, 4, 255, 6, 5, 8, 7, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 3, 255, 5, 4, 6, 255, 7, 255, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 3, 255, 5, 4, 6, 255, 8, 7, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 3, 255, 5, 4, 7, 6, 8, 255, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 3, 255, 5, 4, 7, 6, 9, 8, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 4, 3, 5, 255, 6, 255, 7, 255, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 4, 3, 5, 255, 6, 255, 8, 7, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 4, 3, 5, 255, 7, 6, 8, 255, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 4, 3, 5, 255, 7, 6, 9, 8, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 4, 3, 6, 5, 7, 255, 8, 255, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 4, 3, 6, 5, 7, 255, 9, 8, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 4, 3, 6, 5, 8, 7, 9, 255, 0, 0, 0, 0},
+ 	{0, 255, 2, 1, 4, 3, 6, 5, 8, 7, 10, 9, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 3, 255, 4, 255, 5, 255, 6, 255, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 3, 255, 4, 255, 5, 255, 7, 6, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 3, 255, 4, 255, 6, 5, 7, 255, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 3, 255, 4, 255, 6, 5, 8, 7, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 3, 255, 5, 4, 6, 255, 7, 255, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 3, 255, 5, 4, 6, 255, 8, 7, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 3, 255, 5, 4, 7, 6, 8, 255, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 3, 255, 5, 4, 7, 6, 9, 8, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 4, 3, 5, 255, 6, 255, 7, 255, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 4, 3, 5, 255, 6, 255, 8, 7, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 4, 3, 5, 255, 7, 6, 8, 255, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 4, 3, 5, 255, 7, 6, 9, 8, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 4, 3, 6, 5, 7, 255, 8, 255, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 4, 3, 6, 5, 7, 255, 9, 8, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 4, 3, 6, 5, 8, 7, 9, 255, 0, 0, 0, 0},
+ 	{1, 0, 2, 255, 4, 3, 6, 5, 8, 7, 10, 9, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 4, 255, 5, 255, 6, 255, 7, 255, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 4, 255, 5, 255, 6, 255, 8, 7, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 4, 255, 5, 255, 7, 6, 8, 255, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 4, 255, 5, 255, 7, 6, 9, 8, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 4, 255, 6, 5, 7, 255, 8, 255, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 4, 255, 6, 5, 7, 255, 9, 8, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 4, 255, 6, 5, 8, 7, 9, 255, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 4, 255, 6, 5, 8, 7, 10, 9, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 5, 4, 6, 255, 7, 255, 8, 255, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 5, 4, 6, 255, 7, 255, 9, 8, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 5, 4, 6, 255, 8, 7, 9, 255, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 5, 4, 6, 255, 8, 7, 10, 9, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 5, 4, 7, 6, 8, 255, 9, 255, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 5, 4, 7, 6, 8, 255, 10, 9, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 10, 255, 0, 0, 0, 0},
+ 	{1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 2, 255, 255, 255, 3, 255, 255, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 2, 255, 255, 255, 4, 3, 255, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 2, 255, 255, 255, 5, 4, 3, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 3, 2, 255, 255, 4, 255, 255, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 3, 2, 255, 255, 5, 4, 255, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 3, 2, 255, 255, 6, 5, 4, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 4, 3, 2, 255, 5, 255, 255, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 4, 3, 2, 255, 6, 5, 255, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 4, 3, 2, 255, 7, 6, 5, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 3, 255, 255, 255, 4, 255, 255, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 3, 255, 255, 255, 5, 4, 255, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 3, 255, 255, 255, 6, 5, 4, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 4, 3, 255, 255, 5, 255, 255, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 4, 3, 255, 255, 6, 5, 255, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 4, 3, 255, 255, 7, 6, 5, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 5, 4, 3, 255, 6, 255, 255, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 5, 4, 3, 255, 7, 6, 255, 255},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 5, 4, 3, 255, 8, 7, 6, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 4, 255, 255, 255, 5, 255, 255, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 4, 255, 255, 255, 6, 5, 255, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 4, 255, 255, 255, 7, 6, 5, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 5, 4, 255, 255, 6, 255, 255, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 5, 4, 255, 255, 7, 6, 255, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 5, 4, 255, 255, 8, 7, 6, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 6, 5, 4, 255, 7, 255, 255, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 6, 5, 4, 255, 8, 7, 255, 255},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 6, 5, 4, 255, 9, 8, 7, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 3, 255, 255, 255, 4, 255, 255, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 3, 255, 255, 255, 5, 4, 255, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 3, 255, 255, 255, 6, 5, 4, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 4, 3, 255, 255, 5, 255, 255, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 4, 3, 255, 255, 6, 5, 255, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 4, 3, 255, 255, 7, 6, 5, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 5, 4, 3, 255, 6, 255, 255, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 5, 4, 3, 255, 7, 6, 255, 255},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 5, 4, 3, 255, 8, 7, 6, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 4, 255, 255, 255, 5, 255, 255, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 4, 255, 255, 255, 6, 5, 255, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 4, 255, 255, 255, 7, 6, 5, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 5, 4, 255, 255, 6, 255, 255, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 5, 4, 255, 255, 7, 6, 255, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 5, 4, 255, 255, 8, 7, 6, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 6, 5, 4, 255, 7, 255, 255, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 6, 5, 4, 255, 8, 7, 255, 255},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 6, 5, 4, 255, 9, 8, 7, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 5, 255, 255, 255, 6, 255, 255, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 5, 255, 255, 255, 7, 6, 255, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 5, 255, 255, 255, 8, 7, 6, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 6, 5, 255, 255, 7, 255, 255, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 6, 5, 255, 255, 8, 7, 255, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 6, 5, 255, 255, 9, 8, 7, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 7, 6, 5, 255, 8, 255, 255, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 7, 6, 5, 255, 9, 8, 255, 255},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 7, 6, 5, 255, 10, 9, 8, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 4, 255, 255, 255, 5, 255, 255, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 4, 255, 255, 255, 6, 5, 255, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 4, 255, 255, 255, 7, 6, 5, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 5, 4, 255, 255, 6, 255, 255, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 5, 4, 255, 255, 7, 6, 255, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 5, 4, 255, 255, 8, 7, 6, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 6, 5, 4, 255, 7, 255, 255, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 6, 5, 4, 255, 8, 7, 255, 255},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 6, 5, 4, 255, 9, 8, 7, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 5, 255, 255, 255, 6, 255, 255, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 5, 255, 255, 255, 7, 6, 255, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 5, 255, 255, 255, 8, 7, 6, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 6, 5, 255, 255, 7, 255, 255, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 6, 5, 255, 255, 8, 7, 255, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 6, 5, 255, 255, 9, 8, 7, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 7, 6, 5, 255, 8, 255, 255, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 7, 6, 5, 255, 9, 8, 255, 255},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 7, 6, 5, 255, 10, 9, 8, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 6, 255, 255, 255, 7, 255, 255, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 6, 255, 255, 255, 8, 7, 255, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 6, 255, 255, 255, 9, 8, 7, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 7, 6, 255, 255, 8, 255, 255, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 7, 6, 255, 255, 9, 8, 255, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 7, 6, 255, 255, 10, 9, 8, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 8, 7, 6, 255, 9, 255, 255, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 8, 7, 6, 255, 10, 9, 255, 255},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 8, 7, 6, 255, 11, 10, 9, 255},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 2, 255, 255, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 3, 2, 255, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 4, 3, 2, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 1, 255, 255, 255, 5, 4, 3, 2, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 3, 255, 255, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 4, 3, 255, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 5, 4, 3, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 2, 1, 255, 255, 6, 5, 4, 3, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 4, 255, 255, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 5, 4, 255, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 6, 5, 4, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 3, 2, 1, 255, 7, 6, 5, 4, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 4, 3, 2, 1, 5, 255, 255, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 4, 3, 2, 1, 6, 5, 255, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 4, 3, 2, 1, 7, 6, 5, 255, 0, 0, 0, 0},
+ 	{0, 255, 255, 255, 4, 3, 2, 1, 8, 7, 6, 5, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 3, 255, 255, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 4, 3, 255, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 5, 4, 3, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 2, 255, 255, 255, 6, 5, 4, 3, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 4, 255, 255, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 5, 4, 255, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 6, 5, 4, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 3, 2, 255, 255, 7, 6, 5, 4, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 5, 255, 255, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 6, 5, 255, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 7, 6, 5, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 4, 3, 2, 255, 8, 7, 6, 5, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 5, 4, 3, 2, 6, 255, 255, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 5, 4, 3, 2, 7, 6, 255, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 5, 4, 3, 2, 8, 7, 6, 255, 0, 0, 0, 0},
+ 	{1, 0, 255, 255, 5, 4, 3, 2, 9, 8, 7, 6, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 4, 255, 255, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 5, 4, 255, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 6, 5, 4, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 3, 255, 255, 255, 7, 6, 5, 4, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 5, 255, 255, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 6, 5, 255, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 7, 6, 5, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 4, 3, 255, 255, 8, 7, 6, 5, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 6, 255, 255, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 7, 6, 255, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 8, 7, 6, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 5, 4, 3, 255, 9, 8, 7, 6, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 6, 5, 4, 3, 7, 255, 255, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 6, 5, 4, 3, 8, 7, 255, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 6, 5, 4, 3, 9, 8, 7, 255, 0, 0, 0, 0},
+ 	{2, 1, 0, 255, 6, 5, 4, 3, 10, 9, 8, 7, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 4, 255, 255, 255, 5, 255, 255, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 4, 255, 255, 255, 6, 5, 255, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 4, 255, 255, 255, 7, 6, 5, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 4, 255, 255, 255, 8, 7, 6, 5, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 5, 4, 255, 255, 6, 255, 255, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 5, 4, 255, 255, 7, 6, 255, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 5, 4, 255, 255, 8, 7, 6, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 5, 4, 255, 255, 9, 8, 7, 6, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 6, 5, 4, 255, 7, 255, 255, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 6, 5, 4, 255, 8, 7, 255, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 6, 5, 4, 255, 9, 8, 7, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 6, 5, 4, 255, 10, 9, 8, 7, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 7, 6, 5, 4, 8, 255, 255, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 7, 6, 5, 4, 9, 8, 255, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 7, 6, 5, 4, 10, 9, 8, 255, 0, 0, 0, 0},
+ 	{3, 2, 1, 0, 7, 6, 5, 4, 11, 10, 9, 8, 0, 0, 0, 0}};
+/* number of two bytes : 64 */
+/* number of two + three bytes : 145 */
+/* number of two + three + four bytes : 209 */
+const uint8_t utf8bigindex[4096][2] =
+{	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{145, 3},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{146, 4},
+ 	{0, 12},
+ 	{149, 4},
+ 	{161, 4},
+ 	{64, 4},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{147, 5},
+ 	{0, 12},
+ 	{150, 5},
+ 	{162, 5},
+ 	{65, 5},
+ 	{0, 12},
+ 	{153, 5},
+ 	{165, 5},
+ 	{67, 5},
+ 	{177, 5},
+ 	{73, 5},
+ 	{91, 5},
+ 	{64, 4},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{148, 6},
+ 	{0, 12},
+ 	{151, 6},
+ 	{163, 6},
+ 	{66, 6},
+ 	{0, 12},
+ 	{154, 6},
+ 	{166, 6},
+ 	{68, 6},
+ 	{178, 6},
+ 	{74, 6},
+ 	{92, 6},
+ 	{64, 4},
+ 	{0, 12},
+ 	{157, 6},
+ 	{169, 6},
+ 	{70, 6},
+ 	{181, 6},
+ 	{76, 6},
+ 	{94, 6},
+ 	{65, 5},
+ 	{193, 6},
+ 	{82, 6},
+ 	{100, 6},
+ 	{67, 5},
+ 	{118, 6},
+ 	{73, 5},
+ 	{91, 5},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{152, 7},
+ 	{164, 7},
+ 	{145, 3},
+ 	{0, 12},
+ 	{155, 7},
+ 	{167, 7},
+ 	{69, 7},
+ 	{179, 7},
+ 	{75, 7},
+ 	{93, 7},
+ 	{64, 4},
+ 	{0, 12},
+ 	{158, 7},
+ 	{170, 7},
+ 	{71, 7},
+ 	{182, 7},
+ 	{77, 7},
+ 	{95, 7},
+ 	{65, 5},
+ 	{194, 7},
+ 	{83, 7},
+ 	{101, 7},
+ 	{67, 5},
+ 	{119, 7},
+ 	{73, 5},
+ 	{91, 5},
+ 	{1, 7},
+ 	{0, 12},
+ 	{0, 12},
+ 	{173, 7},
+ 	{148, 6},
+ 	{185, 7},
+ 	{79, 7},
+ 	{97, 7},
+ 	{66, 6},
+ 	{197, 7},
+ 	{85, 7},
+ 	{103, 7},
+ 	{68, 6},
+ 	{121, 7},
+ 	{74, 6},
+ 	{92, 6},
+ 	{2, 7},
+ 	{0, 12},
+ 	{157, 6},
+ 	{109, 7},
+ 	{70, 6},
+ 	{127, 7},
+ 	{76, 6},
+ 	{94, 6},
+ 	{4, 7},
+ 	{193, 6},
+ 	{82, 6},
+ 	{100, 6},
+ 	{8, 7},
+ 	{118, 6},
+ 	{16, 7},
+ 	{32, 7},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{145, 3},
+ 	{0, 12},
+ 	{156, 8},
+ 	{168, 8},
+ 	{146, 4},
+ 	{180, 8},
+ 	{149, 4},
+ 	{161, 4},
+ 	{64, 4},
+ 	{0, 12},
+ 	{159, 8},
+ 	{171, 8},
+ 	{72, 8},
+ 	{183, 8},
+ 	{78, 8},
+ 	{96, 8},
+ 	{65, 5},
+ 	{195, 8},
+ 	{84, 8},
+ 	{102, 8},
+ 	{67, 5},
+ 	{120, 8},
+ 	{73, 5},
+ 	{91, 5},
+ 	{64, 4},
+ 	{0, 12},
+ 	{0, 12},
+ 	{174, 8},
+ 	{148, 6},
+ 	{186, 8},
+ 	{80, 8},
+ 	{98, 8},
+ 	{66, 6},
+ 	{198, 8},
+ 	{86, 8},
+ 	{104, 8},
+ 	{68, 6},
+ 	{122, 8},
+ 	{74, 6},
+ 	{92, 6},
+ 	{3, 8},
+ 	{0, 12},
+ 	{157, 6},
+ 	{110, 8},
+ 	{70, 6},
+ 	{128, 8},
+ 	{76, 6},
+ 	{94, 6},
+ 	{5, 8},
+ 	{193, 6},
+ 	{82, 6},
+ 	{100, 6},
+ 	{9, 8},
+ 	{118, 6},
+ 	{17, 8},
+ 	{33, 8},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{189, 8},
+ 	{152, 7},
+ 	{164, 7},
+ 	{145, 3},
+ 	{201, 8},
+ 	{88, 8},
+ 	{106, 8},
+ 	{69, 7},
+ 	{124, 8},
+ 	{75, 7},
+ 	{93, 7},
+ 	{64, 4},
+ 	{0, 12},
+ 	{158, 7},
+ 	{112, 8},
+ 	{71, 7},
+ 	{130, 8},
+ 	{77, 7},
+ 	{95, 7},
+ 	{6, 8},
+ 	{194, 7},
+ 	{83, 7},
+ 	{101, 7},
+ 	{10, 8},
+ 	{119, 7},
+ 	{18, 8},
+ 	{34, 8},
+ 	{1, 7},
+ 	{0, 12},
+ 	{0, 12},
+ 	{173, 7},
+ 	{148, 6},
+ 	{136, 8},
+ 	{79, 7},
+ 	{97, 7},
+ 	{66, 6},
+ 	{197, 7},
+ 	{85, 7},
+ 	{103, 7},
+ 	{12, 8},
+ 	{121, 7},
+ 	{20, 8},
+ 	{36, 8},
+ 	{2, 7},
+ 	{0, 12},
+ 	{157, 6},
+ 	{109, 7},
+ 	{70, 6},
+ 	{127, 7},
+ 	{24, 8},
+ 	{40, 8},
+ 	{4, 7},
+ 	{193, 6},
+ 	{82, 6},
+ 	{48, 8},
+ 	{8, 7},
+ 	{118, 6},
+ 	{16, 7},
+ 	{32, 7},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{145, 3},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{146, 4},
+ 	{0, 12},
+ 	{149, 4},
+ 	{161, 4},
+ 	{64, 4},
+ 	{0, 12},
+ 	{160, 9},
+ 	{172, 9},
+ 	{147, 5},
+ 	{184, 9},
+ 	{150, 5},
+ 	{162, 5},
+ 	{65, 5},
+ 	{196, 9},
+ 	{153, 5},
+ 	{165, 5},
+ 	{67, 5},
+ 	{177, 5},
+ 	{73, 5},
+ 	{91, 5},
+ 	{64, 4},
+ 	{0, 12},
+ 	{0, 12},
+ 	{175, 9},
+ 	{148, 6},
+ 	{187, 9},
+ 	{81, 9},
+ 	{99, 9},
+ 	{66, 6},
+ 	{199, 9},
+ 	{87, 9},
+ 	{105, 9},
+ 	{68, 6},
+ 	{123, 9},
+ 	{74, 6},
+ 	{92, 6},
+ 	{64, 4},
+ 	{0, 12},
+ 	{157, 6},
+ 	{111, 9},
+ 	{70, 6},
+ 	{129, 9},
+ 	{76, 6},
+ 	{94, 6},
+ 	{65, 5},
+ 	{193, 6},
+ 	{82, 6},
+ 	{100, 6},
+ 	{67, 5},
+ 	{118, 6},
+ 	{73, 5},
+ 	{91, 5},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{190, 9},
+ 	{152, 7},
+ 	{164, 7},
+ 	{145, 3},
+ 	{202, 9},
+ 	{89, 9},
+ 	{107, 9},
+ 	{69, 7},
+ 	{125, 9},
+ 	{75, 7},
+ 	{93, 7},
+ 	{64, 4},
+ 	{0, 12},
+ 	{158, 7},
+ 	{113, 9},
+ 	{71, 7},
+ 	{131, 9},
+ 	{77, 7},
+ 	{95, 7},
+ 	{7, 9},
+ 	{194, 7},
+ 	{83, 7},
+ 	{101, 7},
+ 	{11, 9},
+ 	{119, 7},
+ 	{19, 9},
+ 	{35, 9},
+ 	{1, 7},
+ 	{0, 12},
+ 	{0, 12},
+ 	{173, 7},
+ 	{148, 6},
+ 	{137, 9},
+ 	{79, 7},
+ 	{97, 7},
+ 	{66, 6},
+ 	{197, 7},
+ 	{85, 7},
+ 	{103, 7},
+ 	{13, 9},
+ 	{121, 7},
+ 	{21, 9},
+ 	{37, 9},
+ 	{2, 7},
+ 	{0, 12},
+ 	{157, 6},
+ 	{109, 7},
+ 	{70, 6},
+ 	{127, 7},
+ 	{25, 9},
+ 	{41, 9},
+ 	{4, 7},
+ 	{193, 6},
+ 	{82, 6},
+ 	{49, 9},
+ 	{8, 7},
+ 	{118, 6},
+ 	{16, 7},
+ 	{32, 7},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{145, 3},
+ 	{205, 9},
+ 	{156, 8},
+ 	{168, 8},
+ 	{146, 4},
+ 	{180, 8},
+ 	{149, 4},
+ 	{161, 4},
+ 	{64, 4},
+ 	{0, 12},
+ 	{159, 8},
+ 	{115, 9},
+ 	{72, 8},
+ 	{133, 9},
+ 	{78, 8},
+ 	{96, 8},
+ 	{65, 5},
+ 	{195, 8},
+ 	{84, 8},
+ 	{102, 8},
+ 	{67, 5},
+ 	{120, 8},
+ 	{73, 5},
+ 	{91, 5},
+ 	{64, 4},
+ 	{0, 12},
+ 	{0, 12},
+ 	{174, 8},
+ 	{148, 6},
+ 	{139, 9},
+ 	{80, 8},
+ 	{98, 8},
+ 	{66, 6},
+ 	{198, 8},
+ 	{86, 8},
+ 	{104, 8},
+ 	{14, 9},
+ 	{122, 8},
+ 	{22, 9},
+ 	{38, 9},
+ 	{3, 8},
+ 	{0, 12},
+ 	{157, 6},
+ 	{110, 8},
+ 	{70, 6},
+ 	{128, 8},
+ 	{26, 9},
+ 	{42, 9},
+ 	{5, 8},
+ 	{193, 6},
+ 	{82, 6},
+ 	{50, 9},
+ 	{9, 8},
+ 	{118, 6},
+ 	{17, 8},
+ 	{33, 8},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{189, 8},
+ 	{152, 7},
+ 	{164, 7},
+ 	{145, 3},
+ 	{201, 8},
+ 	{88, 8},
+ 	{106, 8},
+ 	{69, 7},
+ 	{124, 8},
+ 	{75, 7},
+ 	{93, 7},
+ 	{64, 4},
+ 	{0, 12},
+ 	{158, 7},
+ 	{112, 8},
+ 	{71, 7},
+ 	{130, 8},
+ 	{28, 9},
+ 	{44, 9},
+ 	{6, 8},
+ 	{194, 7},
+ 	{83, 7},
+ 	{52, 9},
+ 	{10, 8},
+ 	{119, 7},
+ 	{18, 8},
+ 	{34, 8},
+ 	{1, 7},
+ 	{0, 12},
+ 	{0, 12},
+ 	{173, 7},
+ 	{148, 6},
+ 	{136, 8},
+ 	{79, 7},
+ 	{97, 7},
+ 	{66, 6},
+ 	{197, 7},
+ 	{85, 7},
+ 	{56, 9},
+ 	{12, 8},
+ 	{121, 7},
+ 	{20, 8},
+ 	{36, 8},
+ 	{2, 7},
+ 	{0, 12},
+ 	{157, 6},
+ 	{109, 7},
+ 	{70, 6},
+ 	{127, 7},
+ 	{24, 8},
+ 	{40, 8},
+ 	{4, 7},
+ 	{193, 6},
+ 	{82, 6},
+ 	{48, 8},
+ 	{8, 7},
+ 	{118, 6},
+ 	{16, 7},
+ 	{32, 7},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{145, 3},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{146, 4},
+ 	{0, 12},
+ 	{149, 4},
+ 	{161, 4},
+ 	{64, 4},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{147, 5},
+ 	{0, 12},
+ 	{150, 5},
+ 	{162, 5},
+ 	{65, 5},
+ 	{0, 12},
+ 	{153, 5},
+ 	{165, 5},
+ 	{67, 5},
+ 	{177, 5},
+ 	{73, 5},
+ 	{91, 5},
+ 	{64, 4},
+ 	{0, 12},
+ 	{0, 12},
+ 	{176, 10},
+ 	{148, 6},
+ 	{188, 10},
+ 	{151, 6},
+ 	{163, 6},
+ 	{66, 6},
+ 	{200, 10},
+ 	{154, 6},
+ 	{166, 6},
+ 	{68, 6},
+ 	{178, 6},
+ 	{74, 6},
+ 	{92, 6},
+ 	{64, 4},
+ 	{0, 12},
+ 	{157, 6},
+ 	{169, 6},
+ 	{70, 6},
+ 	{181, 6},
+ 	{76, 6},
+ 	{94, 6},
+ 	{65, 5},
+ 	{193, 6},
+ 	{82, 6},
+ 	{100, 6},
+ 	{67, 5},
+ 	{118, 6},
+ 	{73, 5},
+ 	{91, 5},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{191, 10},
+ 	{152, 7},
+ 	{164, 7},
+ 	{145, 3},
+ 	{203, 10},
+ 	{90, 10},
+ 	{108, 10},
+ 	{69, 7},
+ 	{126, 10},
+ 	{75, 7},
+ 	{93, 7},
+ 	{64, 4},
+ 	{0, 12},
+ 	{158, 7},
+ 	{114, 10},
+ 	{71, 7},
+ 	{132, 10},
+ 	{77, 7},
+ 	{95, 7},
+ 	{65, 5},
+ 	{194, 7},
+ 	{83, 7},
+ 	{101, 7},
+ 	{67, 5},
+ 	{119, 7},
+ 	{73, 5},
+ 	{91, 5},
+ 	{1, 7},
+ 	{0, 12},
+ 	{0, 12},
+ 	{173, 7},
+ 	{148, 6},
+ 	{138, 10},
+ 	{79, 7},
+ 	{97, 7},
+ 	{66, 6},
+ 	{197, 7},
+ 	{85, 7},
+ 	{103, 7},
+ 	{68, 6},
+ 	{121, 7},
+ 	{74, 6},
+ 	{92, 6},
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+ 	{111, 9},
+ 	{70, 6},
+ 	{129, 9},
+ 	{76, 6},
+ 	{94, 6},
+ 	{65, 5},
+ 	{193, 6},
+ 	{82, 6},
+ 	{100, 6},
+ 	{67, 5},
+ 	{118, 6},
+ 	{73, 5},
+ 	{91, 5},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{190, 9},
+ 	{152, 7},
+ 	{164, 7},
+ 	{145, 3},
+ 	{202, 9},
+ 	{89, 9},
+ 	{107, 9},
+ 	{69, 7},
+ 	{125, 9},
+ 	{75, 7},
+ 	{93, 7},
+ 	{64, 4},
+ 	{0, 12},
+ 	{158, 7},
+ 	{113, 9},
+ 	{71, 7},
+ 	{131, 9},
+ 	{30, 10},
+ 	{46, 10},
+ 	{7, 9},
+ 	{194, 7},
+ 	{83, 7},
+ 	{54, 10},
+ 	{11, 9},
+ 	{119, 7},
+ 	{19, 9},
+ 	{35, 9},
+ 	{1, 7},
+ 	{0, 12},
+ 	{0, 12},
+ 	{173, 7},
+ 	{148, 6},
+ 	{137, 9},
+ 	{79, 7},
+ 	{97, 7},
+ 	{66, 6},
+ 	{197, 7},
+ 	{85, 7},
+ 	{58, 10},
+ 	{13, 9},
+ 	{121, 7},
+ 	{21, 9},
+ 	{37, 9},
+ 	{2, 7},
+ 	{0, 12},
+ 	{157, 6},
+ 	{109, 7},
+ 	{70, 6},
+ 	{127, 7},
+ 	{25, 9},
+ 	{41, 9},
+ 	{4, 7},
+ 	{193, 6},
+ 	{82, 6},
+ 	{49, 9},
+ 	{8, 7},
+ 	{118, 6},
+ 	{16, 7},
+ 	{32, 7},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{145, 3},
+ 	{205, 9},
+ 	{156, 8},
+ 	{168, 8},
+ 	{146, 4},
+ 	{180, 8},
+ 	{149, 4},
+ 	{161, 4},
+ 	{64, 4},
+ 	{0, 12},
+ 	{159, 8},
+ 	{115, 9},
+ 	{72, 8},
+ 	{133, 9},
+ 	{78, 8},
+ 	{96, 8},
+ 	{65, 5},
+ 	{195, 8},
+ 	{84, 8},
+ 	{102, 8},
+ 	{67, 5},
+ 	{120, 8},
+ 	{73, 5},
+ 	{91, 5},
+ 	{64, 4},
+ 	{0, 12},
+ 	{0, 12},
+ 	{174, 8},
+ 	{148, 6},
+ 	{139, 9},
+ 	{80, 8},
+ 	{98, 8},
+ 	{66, 6},
+ 	{198, 8},
+ 	{86, 8},
+ 	{60, 10},
+ 	{14, 9},
+ 	{122, 8},
+ 	{22, 9},
+ 	{38, 9},
+ 	{3, 8},
+ 	{0, 12},
+ 	{157, 6},
+ 	{110, 8},
+ 	{70, 6},
+ 	{128, 8},
+ 	{26, 9},
+ 	{42, 9},
+ 	{5, 8},
+ 	{193, 6},
+ 	{82, 6},
+ 	{50, 9},
+ 	{9, 8},
+ 	{118, 6},
+ 	{17, 8},
+ 	{33, 8},
+ 	{0, 6},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{0, 12},
+ 	{189, 8},
+ 	{152, 7},
+ 	{164, 7},
+ 	{145, 3},
+ 	{201, 8},
+ 	{88, 8},
+ 	{106, 8},
+ 	{69, 7},
+ 	{124, 8},
+ 	{75, 7},
+ 	{93, 7},
+ 	{64, 4},
+ 	{0, 12},
+ 	{158, 7},
+ 	{112, 8},
+ 	{71, 7},
+ 	{130, 8},
+ 	{28, 9},
+ 	{44, 9},
+ 	{6, 8},
+ 	{194, 7},
+ 	{83, 7},
+ 	{52, 9},
+ 	{10, 8},
+ 	{119, 7},
+ 	{18, 8},
+ 	{34, 8},
+ 	{1, 7},
+ 	{0, 12},
+ 	{0, 12},
+ 	{173, 7},
+ 	{148, 6},
+ 	{136, 8},
+ 	{79, 7},
+ 	{97, 7},
+ 	{66, 6},
+ 	{197, 7},
+ 	{85, 7},
+ 	{56, 9},
+ 	{12, 8},
+ 	{121, 7},
+ 	{20, 8},
+ 	{36, 8},
+ 	{2, 7},
+ 	{0, 12},
+ 	{157, 6},
+ 	{109, 7},
+ 	{70, 6},
+ 	{127, 7},
+ 	{24, 8},
+ 	{40, 8},
+ 	{4, 7},
+ 	{193, 6},
+ 	{82, 6},
+ 	{48, 8},
+ 	{8, 7},
+ 	{118, 6},
+ 	{16, 7},
+ 	{32, 7},
+ 	{0, 6}};
+} // utf8_to_utf16 namespace
+} // tables namespace
+} // unnamed namespace
+} // namespace simdutf
+
+#endif // SIMDUTF_UTF8_TO_UTF16_TABLES_H
+/* end file src/tables/utf8_to_utf16_tables.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=tables/utf16_to_utf8_tables.h
+/* begin file src/tables/utf16_to_utf8_tables.h */
+// file generated by scripts/sse_convert_utf16_to_utf8.py
+#ifndef SIMDUTF_UTF16_TO_UTF8_TABLES_H
+#define SIMDUTF_UTF16_TO_UTF8_TABLES_H
+
+namespace simdutf {
+namespace {
+namespace tables {
+namespace utf16_to_utf8 {
+
+  // 1 byte for length, 16 bytes for mask
+  const uint8_t pack_1_2_utf8_bytes[256][17] = {
+    {16,1,0,3,2,5,4,7,6,9,8,11,10,13,12,15,14},
+    {15,0,3,2,5,4,7,6,9,8,11,10,13,12,15,14,0x80},
+    {15,1,0,3,2,5,4,7,6,8,11,10,13,12,15,14,0x80},
+    {14,0,3,2,5,4,7,6,8,11,10,13,12,15,14,0x80,0x80},
+    {15,1,0,2,5,4,7,6,9,8,11,10,13,12,15,14,0x80},
+    {14,0,2,5,4,7,6,9,8,11,10,13,12,15,14,0x80,0x80},
+    {14,1,0,2,5,4,7,6,8,11,10,13,12,15,14,0x80,0x80},
+    {13,0,2,5,4,7,6,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {15,1,0,3,2,5,4,7,6,9,8,10,13,12,15,14,0x80},
+    {14,0,3,2,5,4,7,6,9,8,10,13,12,15,14,0x80,0x80},
+    {14,1,0,3,2,5,4,7,6,8,10,13,12,15,14,0x80,0x80},
+    {13,0,3,2,5,4,7,6,8,10,13,12,15,14,0x80,0x80,0x80},
+    {14,1,0,2,5,4,7,6,9,8,10,13,12,15,14,0x80,0x80},
+    {13,0,2,5,4,7,6,9,8,10,13,12,15,14,0x80,0x80,0x80},
+    {13,1,0,2,5,4,7,6,8,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,2,5,4,7,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {15,1,0,3,2,4,7,6,9,8,11,10,13,12,15,14,0x80},
+    {14,0,3,2,4,7,6,9,8,11,10,13,12,15,14,0x80,0x80},
+    {14,1,0,3,2,4,7,6,8,11,10,13,12,15,14,0x80,0x80},
+    {13,0,3,2,4,7,6,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {14,1,0,2,4,7,6,9,8,11,10,13,12,15,14,0x80,0x80},
+    {13,0,2,4,7,6,9,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {13,1,0,2,4,7,6,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,2,4,7,6,8,11,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,4,7,6,9,8,10,13,12,15,14,0x80,0x80},
+    {13,0,3,2,4,7,6,9,8,10,13,12,15,14,0x80,0x80,0x80},
+    {13,1,0,3,2,4,7,6,8,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,4,7,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,4,7,6,9,8,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,2,4,7,6,9,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,7,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,7,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {15,1,0,3,2,5,4,7,6,9,8,11,10,12,15,14,0x80},
+    {14,0,3,2,5,4,7,6,9,8,11,10,12,15,14,0x80,0x80},
+    {14,1,0,3,2,5,4,7,6,8,11,10,12,15,14,0x80,0x80},
+    {13,0,3,2,5,4,7,6,8,11,10,12,15,14,0x80,0x80,0x80},
+    {14,1,0,2,5,4,7,6,9,8,11,10,12,15,14,0x80,0x80},
+    {13,0,2,5,4,7,6,9,8,11,10,12,15,14,0x80,0x80,0x80},
+    {13,1,0,2,5,4,7,6,8,11,10,12,15,14,0x80,0x80,0x80},
+    {12,0,2,5,4,7,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,5,4,7,6,9,8,10,12,15,14,0x80,0x80},
+    {13,0,3,2,5,4,7,6,9,8,10,12,15,14,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,7,6,8,10,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,7,6,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,5,4,7,6,9,8,10,12,15,14,0x80,0x80,0x80},
+    {12,0,2,5,4,7,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,7,6,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,7,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,4,7,6,9,8,11,10,12,15,14,0x80,0x80},
+    {13,0,3,2,4,7,6,9,8,11,10,12,15,14,0x80,0x80,0x80},
+    {13,1,0,3,2,4,7,6,8,11,10,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,4,7,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,4,7,6,9,8,11,10,12,15,14,0x80,0x80,0x80},
+    {12,0,2,4,7,6,9,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,7,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,7,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,4,7,6,9,8,10,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,4,7,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,7,6,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,7,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,7,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,7,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,7,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,7,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {15,1,0,3,2,5,4,6,9,8,11,10,13,12,15,14,0x80},
+    {14,0,3,2,5,4,6,9,8,11,10,13,12,15,14,0x80,0x80},
+    {14,1,0,3,2,5,4,6,8,11,10,13,12,15,14,0x80,0x80},
+    {13,0,3,2,5,4,6,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {14,1,0,2,5,4,6,9,8,11,10,13,12,15,14,0x80,0x80},
+    {13,0,2,5,4,6,9,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {13,1,0,2,5,4,6,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,2,5,4,6,8,11,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,5,4,6,9,8,10,13,12,15,14,0x80,0x80},
+    {13,0,3,2,5,4,6,9,8,10,13,12,15,14,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,6,8,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,5,4,6,9,8,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,2,5,4,6,9,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,4,6,9,8,11,10,13,12,15,14,0x80,0x80},
+    {13,0,3,2,4,6,9,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {13,1,0,3,2,4,6,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,4,6,8,11,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,4,6,9,8,11,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,2,4,6,9,8,11,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,6,8,11,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,6,8,11,10,13,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,4,6,9,8,10,13,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,4,6,9,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,6,9,8,10,13,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,6,9,8,10,13,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,6,8,10,13,12,15,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,5,4,6,9,8,11,10,12,15,14,0x80,0x80},
+    {13,0,3,2,5,4,6,9,8,11,10,12,15,14,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,6,8,11,10,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,5,4,6,9,8,11,10,12,15,14,0x80,0x80,0x80},
+    {12,0,2,5,4,6,9,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,6,9,8,10,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,5,4,6,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,5,4,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,5,4,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,5,4,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,4,6,9,8,11,10,12,15,14,0x80,0x80,0x80},
+    {12,0,3,2,4,6,9,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,6,9,8,11,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,6,9,8,11,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,6,8,11,10,12,15,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,3,2,4,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,3,2,4,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,6,9,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,1,0,2,4,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,0,2,4,6,8,10,12,15,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {15,1,0,3,2,5,4,7,6,9,8,11,10,13,12,14,0x80},
+    {14,0,3,2,5,4,7,6,9,8,11,10,13,12,14,0x80,0x80},
+    {14,1,0,3,2,5,4,7,6,8,11,10,13,12,14,0x80,0x80},
+    {13,0,3,2,5,4,7,6,8,11,10,13,12,14,0x80,0x80,0x80},
+    {14,1,0,2,5,4,7,6,9,8,11,10,13,12,14,0x80,0x80},
+    {13,0,2,5,4,7,6,9,8,11,10,13,12,14,0x80,0x80,0x80},
+    {13,1,0,2,5,4,7,6,8,11,10,13,12,14,0x80,0x80,0x80},
+    {12,0,2,5,4,7,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,5,4,7,6,9,8,10,13,12,14,0x80,0x80},
+    {13,0,3,2,5,4,7,6,9,8,10,13,12,14,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,7,6,8,10,13,12,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,7,6,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,5,4,7,6,9,8,10,13,12,14,0x80,0x80,0x80},
+    {12,0,2,5,4,7,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,7,6,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,7,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,4,7,6,9,8,11,10,13,12,14,0x80,0x80},
+    {13,0,3,2,4,7,6,9,8,11,10,13,12,14,0x80,0x80,0x80},
+    {13,1,0,3,2,4,7,6,8,11,10,13,12,14,0x80,0x80,0x80},
+    {12,0,3,2,4,7,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,4,7,6,9,8,11,10,13,12,14,0x80,0x80,0x80},
+    {12,0,2,4,7,6,9,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,7,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,7,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,4,7,6,9,8,10,13,12,14,0x80,0x80,0x80},
+    {12,0,3,2,4,7,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,7,6,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,7,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,7,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,7,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,7,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,7,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,5,4,7,6,9,8,11,10,12,14,0x80,0x80},
+    {13,0,3,2,5,4,7,6,9,8,11,10,12,14,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,7,6,8,11,10,12,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,7,6,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,5,4,7,6,9,8,11,10,12,14,0x80,0x80,0x80},
+    {12,0,2,5,4,7,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,7,6,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,7,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,7,6,9,8,10,12,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,7,6,9,8,10,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,5,4,7,6,8,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,5,4,7,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,7,6,9,8,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,7,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,5,4,7,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,5,4,7,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,4,7,6,9,8,11,10,12,14,0x80,0x80,0x80},
+    {12,0,3,2,4,7,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,7,6,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,7,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,7,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,7,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,7,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,7,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,7,6,9,8,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,7,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,3,2,4,7,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,3,2,4,7,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,7,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,7,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,1,0,2,4,7,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,0,2,4,7,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {14,1,0,3,2,5,4,6,9,8,11,10,13,12,14,0x80,0x80},
+    {13,0,3,2,5,4,6,9,8,11,10,13,12,14,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,6,8,11,10,13,12,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {13,1,0,2,5,4,6,9,8,11,10,13,12,14,0x80,0x80,0x80},
+    {12,0,2,5,4,6,9,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,6,9,8,10,13,12,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,5,4,6,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,5,4,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,5,4,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,5,4,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,4,6,9,8,11,10,13,12,14,0x80,0x80,0x80},
+    {12,0,3,2,4,6,9,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,4,6,9,8,11,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,4,6,9,8,11,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,6,8,11,10,13,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,3,2,4,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,3,2,4,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,6,9,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,1,0,2,4,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,0,2,4,6,8,10,13,12,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {13,1,0,3,2,5,4,6,9,8,11,10,12,14,0x80,0x80,0x80},
+    {12,0,3,2,5,4,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,5,4,6,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,5,4,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,2,5,4,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,2,5,4,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,5,4,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,5,4,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,5,4,6,9,8,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,5,4,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,3,2,5,4,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,3,2,5,4,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,5,4,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,5,4,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,1,0,2,5,4,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,0,2,5,4,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {12,1,0,3,2,4,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80},
+    {11,0,3,2,4,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,3,2,4,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,3,2,4,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,2,4,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,2,4,6,9,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,1,0,2,4,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,0,2,4,6,8,11,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,1,0,3,2,4,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80},
+    {10,0,3,2,4,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,1,0,3,2,4,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,0,3,2,4,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,1,0,2,4,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,0,2,4,6,9,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,1,0,2,4,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,0,2,4,6,8,10,12,14,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80}
+  };
+
+  // 1 byte for length, 16 bytes for mask
+  const uint8_t pack_1_2_3_utf8_bytes[256][17] = {
+    {12,2,3,1,6,7,5,10,11,9,14,15,13,0x80,0x80,0x80,0x80},
+    {9,6,7,5,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,3,1,6,7,5,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80},
+    {10,0,6,7,5,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,2,3,1,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,3,1,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,0,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,2,3,1,7,5,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80},
+    {8,7,5,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,3,1,7,5,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,0,7,5,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,2,3,1,4,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,4,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,3,1,4,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,0,4,10,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,2,3,1,6,7,5,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,6,7,5,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,3,1,6,7,5,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,0,6,7,5,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,2,3,1,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {3,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,3,1,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,0,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,2,3,1,7,5,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,7,5,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,3,1,7,5,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,0,7,5,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,2,3,1,4,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,4,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,3,1,4,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,0,4,14,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {11,2,3,1,6,7,5,11,9,14,15,13,0x80,0x80,0x80,0x80,0x80},
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+    {3,7,5,8,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {4,0,7,5,8,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {4,3,1,4,8,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {8,6,7,5,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {9,0,6,7,5,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,2,3,1,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,3,1,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,0,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,2,3,1,7,5,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,7,5,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,3,1,7,5,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,0,7,5,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,2,3,1,4,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {8,3,1,4,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,0,4,10,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,2,3,1,6,7,5,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,6,7,5,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,3,1,6,7,5,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,0,6,7,5,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,2,3,1,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {4,3,1,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {4,7,5,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,3,1,7,5,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,0,7,5,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {4,0,4,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,2,3,1,6,7,5,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {8,0,6,7,5,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,2,3,1,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
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+    {5,0,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,2,3,1,7,5,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,7,5,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,3,1,7,5,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,0,7,5,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,2,3,1,4,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,4,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,3,1,4,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,0,4,11,9,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,2,3,1,6,7,5,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,6,7,5,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,3,1,6,7,5,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,0,6,7,5,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,2,3,1,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {3,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,3,1,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,0,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,2,3,1,7,5,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,7,5,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,3,1,7,5,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,0,7,5,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,2,3,1,4,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,4,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,3,1,4,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,0,4,8,15,13,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {10,2,3,1,6,7,5,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,6,7,5,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,3,1,6,7,5,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,0,6,7,5,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,2,3,1,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,3,1,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,0,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,2,3,1,7,5,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,7,5,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,3,1,7,5,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,0,7,5,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,2,3,1,4,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,4,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,3,1,4,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,0,4,10,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,2,3,1,6,7,5,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,6,7,5,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,3,1,6,7,5,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,0,6,7,5,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,2,3,1,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {1,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {3,3,1,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {2,0,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,2,3,1,7,5,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {3,7,5,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,3,1,7,5,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,0,7,5,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,2,3,1,4,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {2,4,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,3,1,4,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {3,0,4,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {9,2,3,1,6,7,5,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,6,7,5,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,3,1,6,7,5,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,0,6,7,5,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,2,3,1,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {3,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,3,1,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,0,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,2,3,1,7,5,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,7,5,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,3,1,7,5,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,0,7,5,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,2,3,1,4,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,4,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,3,1,4,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,0,4,11,9,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {8,2,3,1,6,7,5,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,6,7,5,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,3,1,6,7,5,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,0,6,7,5,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,2,3,1,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {2,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,3,1,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {3,0,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {7,2,3,1,7,5,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,7,5,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,3,1,7,5,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,0,7,5,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {6,2,3,1,4,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {3,4,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {5,3,1,4,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80},
+    {4,0,4,8,12,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80,0x80}
+  };
+
+} // utf16_to_utf8 namespace
+} // tables namespace
+} // unnamed namespace
+} // namespace simdutf
+
+#endif // SIMDUTF_UTF16_TO_UTF8_TABLES_H
+/* end file src/tables/utf16_to_utf8_tables.h */
+// End of tables.
+
+// The scalar routines should be included once.
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/ascii.h
+/* begin file src/scalar/ascii.h */
+#ifndef SIMDUTF_ASCII_H
+#define SIMDUTF_ASCII_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace ascii {
+
+inline simdutf_warn_unused bool validate(const char *buf, size_t len) noexcept {
+    const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+    uint64_t pos = 0;
+    // process in blocks of 16 bytes when possible
+    for (;pos + 16 < len; pos += 16) {
+        uint64_t v1;
+        std::memcpy(&v1, data + pos, sizeof(uint64_t));
+        uint64_t v2;
+        std::memcpy(&v2, data + pos + sizeof(uint64_t), sizeof(uint64_t));
+        uint64_t v{v1 | v2};
+        if ((v & 0x8080808080808080) != 0) { return false; }
+    }
+    // process the tail byte-by-byte
+    for (;pos < len; pos ++) {
+        if (data[pos] >= 0b10000000) { return false; }
+    }
+    return true;
+}
+
+inline simdutf_warn_unused result validate_with_errors(const char *buf, size_t len) noexcept {
+    const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+    size_t pos = 0;
+    // process in blocks of 16 bytes when possible
+    for (;pos + 16 < len; pos += 16) {
+        uint64_t v1;
+        std::memcpy(&v1, data + pos, sizeof(uint64_t));
+        uint64_t v2;
+        std::memcpy(&v2, data + pos + sizeof(uint64_t), sizeof(uint64_t));
+        uint64_t v{v1 | v2};
+        if ((v & 0x8080808080808080) != 0) {
+            for (;pos < len; pos ++) {
+                if (data[pos] >= 0b10000000) { return result(error_code::TOO_LARGE, pos); }
+            }
+        }
+    }
+    // process the tail byte-by-byte
+    for (;pos < len; pos ++) {
+        if (data[pos] >= 0b10000000) { return result(error_code::TOO_LARGE, pos); }
+    }
+    return result(error_code::SUCCESS, pos);
+}
+
+} // ascii namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/ascii.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf8.h
+/* begin file src/scalar/utf8.h */
+#ifndef SIMDUTF_UTF8_H
+#define SIMDUTF_UTF8_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf8 {
+// credit: based on code from Google Fuchsia (Apache Licensed)
+inline simdutf_warn_unused bool validate(const char *buf, size_t len) noexcept {
+  const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+  uint64_t pos = 0;
+  uint32_t code_point = 0;
+  while (pos < len) {
+    // check of the next 8 bytes are ascii.
+    uint64_t next_pos = pos + 16;
+    if (next_pos <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v1;
+      std::memcpy(&v1, data + pos, sizeof(uint64_t));
+      uint64_t v2;
+      std::memcpy(&v2, data + pos + sizeof(uint64_t), sizeof(uint64_t));
+      uint64_t v{v1 | v2};
+      if ((v & 0x8080808080808080) == 0) {
+        pos = next_pos;
+        continue;
+      }
+    }
+    unsigned char byte = data[pos];
+
+    while (byte < 0b10000000) {
+      if (++pos == len) { return true; }
+      byte = data[pos];
+    }
+
+    if ((byte & 0b11100000) == 0b11000000) {
+      next_pos = pos + 2;
+      if (next_pos > len) { return false; }
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return false; }
+      // range check
+      code_point = (byte & 0b00011111) << 6 | (data[pos + 1] & 0b00111111);
+      if ((code_point < 0x80) || (0x7ff < code_point)) { return false; }
+    } else if ((byte & 0b11110000) == 0b11100000) {
+      next_pos = pos + 3;
+      if (next_pos > len) { return false; }
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return false; }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return false; }
+      // range check
+      code_point = (byte & 0b00001111) << 12 |
+                   (data[pos + 1] & 0b00111111) << 6 |
+                   (data[pos + 2] & 0b00111111);
+      if ((code_point < 0x800) || (0xffff < code_point) ||
+          (0xd7ff < code_point && code_point < 0xe000)) {
+        return false;
+      }
+    } else if ((byte & 0b11111000) == 0b11110000) { // 0b11110000
+      next_pos = pos + 4;
+      if (next_pos > len) { return false; }
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return false; }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return false; }
+      if ((data[pos + 3] & 0b11000000) != 0b10000000) { return false; }
+      // range check
+      code_point =
+          (byte & 0b00000111) << 18 | (data[pos + 1] & 0b00111111) << 12 |
+          (data[pos + 2] & 0b00111111) << 6 | (data[pos + 3] & 0b00111111);
+      if (code_point <= 0xffff || 0x10ffff < code_point) { return false; }
+    } else {
+      // we may have a continuation
+      return false;
+    }
+    pos = next_pos;
+  }
+  return true;
+}
+
+inline simdutf_warn_unused result validate_with_errors(const char *buf, size_t len) noexcept {
+  const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+  size_t pos = 0;
+  uint32_t code_point = 0;
+  while (pos < len) {
+    // check of the next 8 bytes are ascii.
+    uint64_t next_pos = pos + 16;
+    if (next_pos <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v1;
+      std::memcpy(&v1, data + pos, sizeof(uint64_t));
+      uint64_t v2;
+      std::memcpy(&v2, data + pos + sizeof(uint64_t), sizeof(uint64_t));
+      uint64_t v{v1 | v2};
+      if ((v & 0x8080808080808080) == 0) {
+        pos = next_pos;
+        continue;
+      }
+    }
+    unsigned char byte = data[pos];
+
+    while (byte < 0b10000000) {
+      if (++pos == len) { return result(error_code::SUCCESS, len); }
+      byte = data[pos];
+    }
+
+    if ((byte & 0b11100000) == 0b11000000) {
+      next_pos = pos + 2;
+      if (next_pos > len) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      // range check
+      code_point = (byte & 0b00011111) << 6 | (data[pos + 1] & 0b00111111);
+      if ((code_point < 0x80) || (0x7ff < code_point)) { return result(error_code::OVERLONG, pos); }
+    } else if ((byte & 0b11110000) == 0b11100000) {
+      next_pos = pos + 3;
+      if (next_pos > len) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      // range check
+      code_point = (byte & 0b00001111) << 12 |
+                   (data[pos + 1] & 0b00111111) << 6 |
+                   (data[pos + 2] & 0b00111111);
+      if ((code_point < 0x800) || (0xffff < code_point)) { return result(error_code::OVERLONG, pos);}
+      if (0xd7ff < code_point && code_point < 0xe000) { return result(error_code::SURROGATE, pos); }
+    } else if ((byte & 0b11111000) == 0b11110000) { // 0b11110000
+      next_pos = pos + 4;
+      if (next_pos > len) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 3] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      // range check
+      code_point =
+          (byte & 0b00000111) << 18 | (data[pos + 1] & 0b00111111) << 12 |
+          (data[pos + 2] & 0b00111111) << 6 | (data[pos + 3] & 0b00111111);
+      if (code_point <= 0xffff) { return result(error_code::OVERLONG, pos); }
+      if (0x10ffff < code_point) { return result(error_code::TOO_LARGE, pos); }
+    } else {
+      // we either have too many continuation bytes or an invalid leading byte
+      if ((byte & 0b11000000) == 0b10000000) { return result(error_code::TOO_LONG, pos); }
+      else { return result(error_code::HEADER_BITS, pos); }
+    }
+    pos = next_pos;
+  }
+  return result(error_code::SUCCESS, len);
+}
+
+// Finds the previous leading byte and validates with errors from there
+// Used to pinpoint the location of an error when an invalid chunk is detected
+inline simdutf_warn_unused result rewind_and_validate_with_errors(const char *buf, size_t len) noexcept {
+  size_t extra_len{0};
+  // A leading byte cannot be further than 4 bytes away
+  for(int i = 0; i < 5; i++) {
+    unsigned char byte = *buf;
+    if ((byte & 0b11000000) != 0b10000000) {
+      break;
+    } else {
+      buf--;
+      extra_len++;
+    }
+  }
+
+  result res = validate_with_errors(buf, len + extra_len);
+  res.count -= extra_len;
+  return res;
+}
+
+inline size_t count_code_points(const char* buf, size_t len) {
+    const int8_t * p = reinterpret_cast<const int8_t *>(buf);
+    size_t counter{0};
+    for(size_t i = 0; i < len; i++) {
+        // -65 is 0b10111111, anything larger in two-complement's should start a new code point.
+        if(p[i] > -65) { counter++; }
+    }
+    return counter;
+}
+
+inline size_t utf16_length_from_utf8(const char* buf, size_t len) {
+    const int8_t * p = reinterpret_cast<const int8_t *>(buf);
+    size_t counter{0};
+    for(size_t i = 0; i < len; i++) {
+        if(p[i] > -65) { counter++; }
+        if(uint8_t(p[i]) >= 240) { counter++; }
+    }
+    return counter;
+}
+
+inline size_t utf32_length_from_utf8(const char* buf, size_t len) {
+    const int8_t * p = reinterpret_cast<const int8_t *>(buf);
+    size_t counter{0};
+    for(size_t i = 0; i < len; i++) {
+        // -65 is 0b10111111, anything larger in two-complement's should start a new code point.
+        if(p[i] > -65) { counter++; }
+    }
+    return counter;
+}
+
+} // utf8 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf8.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf16.h
+/* begin file src/scalar/utf16.h */
+#ifndef SIMDUTF_UTF16_H
+#define SIMDUTF_UTF16_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf16 {
+
+inline simdutf_warn_unused uint16_t swap_bytes(const uint16_t word) {
+  return uint16_t((word >> 8) | (word << 8));
+}
+
+template <endianness big_endian>
+inline simdutf_warn_unused bool validate(const char16_t *buf, size_t len) noexcept {
+  const uint16_t *data = reinterpret_cast<const uint16_t *>(buf);
+  uint64_t pos = 0;
+  while (pos < len) {
+    uint16_t word = big_endian ? swap_bytes(data[pos]) : data[pos];
+    if((word &0xF800) == 0xD800) {
+        if(pos + 1 >= len) { return false; }
+        uint16_t diff = uint16_t(word - 0xD800);
+        if(diff > 0x3FF) { return false; }
+        uint16_t next_word = big_endian ? uint16_t((data[pos + 1] >> 8) | (data[pos + 1] << 8)) : data[pos + 1];
+        uint16_t diff2 = uint16_t(next_word - 0xDC00);
+        if(diff2 > 0x3FF) { return false; }
+        pos += 2;
+    } else {
+        pos++;
+    }
+  }
+  return true;
+}
+
+template <endianness big_endian>
+inline simdutf_warn_unused result validate_with_errors(const char16_t *buf, size_t len) noexcept {
+  const uint16_t *data = reinterpret_cast<const uint16_t *>(buf);
+  size_t pos = 0;
+  while (pos < len) {
+    uint16_t word = big_endian ? swap_bytes(data[pos]) : data[pos];
+    if((word & 0xF800) == 0xD800) {
+        if(pos + 1 >= len) { return result(error_code::SURROGATE, pos); }
+        uint16_t diff = uint16_t(word - 0xD800);
+        if(diff > 0x3FF) { return result(error_code::SURROGATE, pos); }
+        uint16_t next_word = big_endian ? uint16_t((data[pos + 1] >> 8) | (data[pos + 1] << 8)) : data[pos + 1];
+        uint16_t diff2 = uint16_t(next_word - 0xDC00);
+        if(diff2 > 0x3FF) { return result(error_code::SURROGATE, pos); }
+        pos += 2;
+    } else {
+        pos++;
+    }
+  }
+  return result(error_code::SUCCESS, pos);
+}
+
+template <endianness big_endian>
+inline size_t count_code_points(const char16_t* buf, size_t len) {
+  // We are not BOM aware.
+  const uint16_t * p = reinterpret_cast<const uint16_t *>(buf);
+  size_t counter{0};
+  for(size_t i = 0; i < len; i++) {
+    uint16_t word = big_endian ? swap_bytes(p[i]) : p[i];
+    counter += ((word & 0xFC00) != 0xDC00);
+  }
+  return counter;
+}
+
+template <endianness big_endian>
+inline size_t utf8_length_from_utf16(const char16_t* buf, size_t len) {
+  // We are not BOM aware.
+  const uint16_t * p = reinterpret_cast<const uint16_t *>(buf);
+  size_t counter{0};
+  for(size_t i = 0; i < len; i++) {
+    uint16_t word = big_endian ? swap_bytes(p[i]) : p[i];
+    /** ASCII **/
+    if(word <= 0x7F) { counter++; }
+    /** two-byte **/
+    else if (word <= 0x7FF) { counter += 2; }
+    /** three-byte **/
+    else if((word <= 0xD7FF) || (word >= 0xE000)) { counter += 3; }
+    /** surrogates -- 4 bytes **/
+    else { counter += 2; }
+  }
+  return counter;
+}
+
+template <endianness big_endian>
+inline size_t utf32_length_from_utf16(const char16_t* buf, size_t len) {
+  // We are not BOM aware.
+  const uint16_t * p = reinterpret_cast<const uint16_t *>(buf);
+  size_t counter{0};
+  for(size_t i = 0; i < len; i++) {
+    uint16_t word = big_endian ? swap_bytes(p[i]) : p[i];
+    counter += ((word & 0xFC00) != 0xDC00);
+  }
+  return counter;
+}
+
+simdutf_really_inline void change_endianness_utf16(const char16_t* in, size_t size, char16_t* out) {
+  const uint16_t * input = reinterpret_cast<const uint16_t *>(in);
+  uint16_t * output = reinterpret_cast<uint16_t *>(out);
+  for (size_t i = 0; i < size; i++) {
+    *output++ = uint16_t(input[i] >> 8 | input[i] << 8);
+  }
+}
+
+} // utf16 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf16.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf32.h
+/* begin file src/scalar/utf32.h */
+#ifndef SIMDUTF_UTF32_H
+#define SIMDUTF_UTF32_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf32 {
+
+inline simdutf_warn_unused bool validate(const char32_t *buf, size_t len) noexcept {
+  const uint32_t *data = reinterpret_cast<const uint32_t *>(buf);
+  uint64_t pos = 0;
+  for(;pos < len; pos++) {
+    uint32_t word = data[pos];
+    if(word > 0x10FFFF || (word >= 0xD800 && word <= 0xDFFF)) {
+        return false;
+    }
+  }
+  return true;
+}
+
+inline simdutf_warn_unused result validate_with_errors(const char32_t *buf, size_t len) noexcept {
+  const uint32_t *data = reinterpret_cast<const uint32_t *>(buf);
+  size_t pos = 0;
+  for(;pos < len; pos++) {
+    uint32_t word = data[pos];
+    if(word > 0x10FFFF) {
+        return result(error_code::TOO_LARGE, pos);
+    }
+    if(word >= 0xD800 && word <= 0xDFFF) {
+        return result(error_code::SURROGATE, pos);
+    }
+  }
+  return result(error_code::SUCCESS, pos);
+}
+
+inline size_t utf8_length_from_utf32(const char32_t* buf, size_t len) {
+  // We are not BOM aware.
+  const uint32_t * p = reinterpret_cast<const uint32_t *>(buf);
+  size_t counter{0};
+  for(size_t i = 0; i < len; i++) {
+    /** ASCII **/
+    if(p[i] <= 0x7F) { counter++; }
+    /** two-byte **/
+    else if(p[i] <= 0x7FF) { counter += 2; }
+    /** three-byte **/
+    else if(p[i] <= 0xFFFF) { counter += 3; }
+    /** four-bytes **/
+    else { counter += 4; }
+  }
+  return counter;
+}
+
+inline size_t utf16_length_from_utf32(const char32_t* buf, size_t len) {
+  // We are not BOM aware.
+  const uint32_t * p = reinterpret_cast<const uint32_t *>(buf);
+  size_t counter{0};
+  for(size_t i = 0; i < len; i++) {
+    /** non-surrogate word **/
+    if(p[i] <= 0xFFFF) { counter++; }
+    /** surrogate pair **/
+    else { counter += 2; }
+  }
+  return counter;
+}
+
+} // utf32 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf32.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf32_to_utf8/valid_utf32_to_utf8.h
+/* begin file src/scalar/utf32_to_utf8/valid_utf32_to_utf8.h */
+#ifndef SIMDUTF_VALID_UTF32_TO_UTF8_H
+#define SIMDUTF_VALID_UTF32_TO_UTF8_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf32_to_utf8 {
+
+inline size_t convert_valid(const char32_t* buf, size_t len, char* utf8_output) {
+	const uint32_t *data = reinterpret_cast<const uint32_t *>(buf);
+  size_t pos = 0;
+  char* start{utf8_output};
+  while (pos < len) {
+    // try to convert the next block of 2 ASCII characters
+    if (pos + 2 <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v;
+      ::memcpy(&v, data + pos, sizeof(uint64_t));
+      if ((v & 0xFFFFFF80FFFFFF80) == 0) {
+        *utf8_output++ = char(buf[pos]);
+				*utf8_output++ = char(buf[pos+1]);
+        pos += 2;
+        continue;
+      }
+    }
+    uint32_t word = data[pos];
+    if((word & 0xFFFFFF80)==0) {
+      // will generate one UTF-8 bytes
+      *utf8_output++ = char(word);
+      pos++;
+    } else if((word & 0xFFFFF800)==0) {
+      // will generate two UTF-8 bytes
+      // we have 0b110XXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>6) | 0b11000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else if((word & 0xFFFF0000)==0) {
+      // will generate three UTF-8 bytes
+      // we have 0b1110XXXX 0b10XXXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>12) | 0b11100000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else {
+      // will generate four UTF-8 bytes
+      // we have 0b11110XXX 0b10XXXXXX 0b10XXXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>18) | 0b11110000);
+      *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos ++;
+    }
+  }
+  return utf8_output - start;
+}
+
+} // utf32_to_utf8 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf32_to_utf8/valid_utf32_to_utf8.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf32_to_utf8/utf32_to_utf8.h
+/* begin file src/scalar/utf32_to_utf8/utf32_to_utf8.h */
+#ifndef SIMDUTF_UTF32_TO_UTF8_H
+#define SIMDUTF_UTF32_TO_UTF8_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf32_to_utf8 {
+
+inline size_t convert(const char32_t* buf, size_t len, char* utf8_output) {
+  const uint32_t *data = reinterpret_cast<const uint32_t *>(buf);
+  size_t pos = 0;
+  char* start{utf8_output};
+  while (pos < len) {
+    // try to convert the next block of 2 ASCII characters
+    if (pos + 2 <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v;
+      ::memcpy(&v, data + pos, sizeof(uint64_t));
+      if ((v & 0xFFFFFF80FFFFFF80) == 0) {
+        *utf8_output++ = char(buf[pos]);
+				*utf8_output++ = char(buf[pos+1]);
+        pos += 2;
+        continue;
+      }
+    }
+    uint32_t word = data[pos];
+    if((word & 0xFFFFFF80)==0) {
+      // will generate one UTF-8 bytes
+      *utf8_output++ = char(word);
+      pos++;
+    } else if((word & 0xFFFFF800)==0) {
+      // will generate two UTF-8 bytes
+      // we have 0b110XXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>6) | 0b11000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else if((word & 0xFFFF0000)==0) {
+      // will generate three UTF-8 bytes
+      // we have 0b1110XXXX 0b10XXXXXX 0b10XXXXXX
+			if (word >= 0xD800 && word <= 0xDFFF) { return 0; }
+      *utf8_output++ = char((word>>12) | 0b11100000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else {
+      // will generate four UTF-8 bytes
+      // we have 0b11110XXX 0b10XXXXXX 0b10XXXXXX 0b10XXXXXX
+			if (word > 0x10FFFF) { return 0; }
+      *utf8_output++ = char((word>>18) | 0b11110000);
+      *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos ++;
+    }
+  }
+  return utf8_output - start;
+}
+
+inline result convert_with_errors(const char32_t* buf, size_t len, char* utf8_output) {
+  const uint32_t *data = reinterpret_cast<const uint32_t *>(buf);
+  size_t pos = 0;
+  char* start{utf8_output};
+  while (pos < len) {
+    // try to convert the next block of 2 ASCII characters
+    if (pos + 2 <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v;
+      ::memcpy(&v, data + pos, sizeof(uint64_t));
+      if ((v & 0xFFFFFF80FFFFFF80) == 0) {
+        *utf8_output++ = char(buf[pos]);
+				*utf8_output++ = char(buf[pos+1]);
+        pos += 2;
+        continue;
+      }
+    }
+    uint32_t word = data[pos];
+    if((word & 0xFFFFFF80)==0) {
+      // will generate one UTF-8 bytes
+      *utf8_output++ = char(word);
+      pos++;
+    } else if((word & 0xFFFFF800)==0) {
+      // will generate two UTF-8 bytes
+      // we have 0b110XXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>6) | 0b11000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else if((word & 0xFFFF0000)==0) {
+      // will generate three UTF-8 bytes
+      // we have 0b1110XXXX 0b10XXXXXX 0b10XXXXXX
+			if (word >= 0xD800 && word <= 0xDFFF) { return result(error_code::SURROGATE, pos); }
+      *utf8_output++ = char((word>>12) | 0b11100000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else {
+      // will generate four UTF-8 bytes
+      // we have 0b11110XXX 0b10XXXXXX 0b10XXXXXX 0b10XXXXXX
+			if (word > 0x10FFFF) { return result(error_code::TOO_LARGE, pos); }
+      *utf8_output++ = char((word>>18) | 0b11110000);
+      *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos ++;
+    }
+  }
+  return result(error_code::SUCCESS, utf8_output - start);
+}
+
+} // utf32_to_utf8 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf32_to_utf8/utf32_to_utf8.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf32_to_utf16/valid_utf32_to_utf16.h
+/* begin file src/scalar/utf32_to_utf16/valid_utf32_to_utf16.h */
+#ifndef SIMDUTF_VALID_UTF32_TO_UTF16_H
+#define SIMDUTF_VALID_UTF32_TO_UTF16_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf32_to_utf16 {
+
+template <endianness big_endian>
+inline size_t convert_valid(const char32_t* buf, size_t len, char16_t* utf16_output) {
+  const uint32_t *data = reinterpret_cast<const uint32_t *>(buf);
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  while (pos < len) {
+    uint32_t word = data[pos];
+    if((word & 0xFFFF0000)==0) {
+      // will not generate a surrogate pair
+      *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(uint16_t(word))) : char16_t(word);
+      pos++;
+    } else {
+      // will generate a surrogate pair
+      word -= 0x10000;
+      uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+      uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+      if (big_endian) {
+        high_surrogate = utf16::swap_bytes(high_surrogate);
+        low_surrogate = utf16::swap_bytes(low_surrogate);
+      }
+      *utf16_output++ = char16_t(high_surrogate);
+      *utf16_output++ = char16_t(low_surrogate);
+      pos++;
+    }
+  }
+  return utf16_output - start;
+}
+
+} // utf32_to_utf16 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf32_to_utf16/valid_utf32_to_utf16.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf32_to_utf16/utf32_to_utf16.h
+/* begin file src/scalar/utf32_to_utf16/utf32_to_utf16.h */
+#ifndef SIMDUTF_UTF32_TO_UTF16_H
+#define SIMDUTF_UTF32_TO_UTF16_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf32_to_utf16 {
+
+template <endianness big_endian>
+inline size_t convert(const char32_t* buf, size_t len, char16_t* utf16_output) {
+  const uint32_t *data = reinterpret_cast<const uint32_t *>(buf);
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  while (pos < len) {
+    uint32_t word = data[pos];
+    if((word & 0xFFFF0000)==0) {
+      if (word >= 0xD800 && word <= 0xDFFF) { return 0; }
+      // will not generate a surrogate pair
+      *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(uint16_t(word))) : char16_t(word);
+    } else {
+      // will generate a surrogate pair
+      if (word > 0x10FFFF) { return 0; }
+      word -= 0x10000;
+      uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+      uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+      if (big_endian) {
+        high_surrogate = utf16::swap_bytes(high_surrogate);
+        low_surrogate = utf16::swap_bytes(low_surrogate);
+      }
+      *utf16_output++ = char16_t(high_surrogate);
+      *utf16_output++ = char16_t(low_surrogate);
+    }
+    pos++;
+  }
+  return utf16_output - start;
+}
+
+template <endianness big_endian>
+inline result convert_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) {
+  const uint32_t *data = reinterpret_cast<const uint32_t *>(buf);
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  while (pos < len) {
+    uint32_t word = data[pos];
+    if((word & 0xFFFF0000)==0) {
+      if (word >= 0xD800 && word <= 0xDFFF) { return result(error_code::SURROGATE, pos); }
+      // will not generate a surrogate pair
+      *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(uint16_t(word))) : char16_t(word);
+    } else {
+      // will generate a surrogate pair
+      if (word > 0x10FFFF) { return result(error_code::TOO_LARGE, pos); }
+      word -= 0x10000;
+      uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+      uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+      if (big_endian) {
+        high_surrogate = utf16::swap_bytes(high_surrogate);
+        low_surrogate = utf16::swap_bytes(low_surrogate);
+      }
+      *utf16_output++ = char16_t(high_surrogate);
+      *utf16_output++ = char16_t(low_surrogate);
+    }
+    pos++;
+  }
+  return result(error_code::SUCCESS, utf16_output - start);
+}
+
+} // utf32_to_utf16 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf32_to_utf16/utf32_to_utf16.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf16_to_utf8/valid_utf16_to_utf8.h
+/* begin file src/scalar/utf16_to_utf8/valid_utf16_to_utf8.h */
+#ifndef SIMDUTF_VALID_UTF16_TO_UTF8_H
+#define SIMDUTF_VALID_UTF16_TO_UTF8_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf16_to_utf8 {
+
+template <endianness big_endian>
+inline size_t convert_valid(const char16_t* buf, size_t len, char* utf8_output) {
+ const uint16_t *data = reinterpret_cast<const uint16_t *>(buf);
+  size_t pos = 0;
+  char* start{utf8_output};
+  while (pos < len) {
+    // try to convert the next block of 4 ASCII characters
+    if (pos + 4 <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v;
+      ::memcpy(&v, data + pos, sizeof(uint64_t));
+      if (big_endian) v = (v >> 8) | (v << (64 - 8));
+      if ((v & 0xFF80FF80FF80FF80) == 0) {
+        size_t final_pos = pos + 4;
+        while(pos < final_pos) {
+          *utf8_output++ = big_endian ? char(utf16::swap_bytes(buf[pos])) : char(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint16_t word = big_endian ? utf16::swap_bytes(data[pos]) : data[pos];
+    if((word & 0xFF80)==0) {
+      // will generate one UTF-8 bytes
+      *utf8_output++ = char(word);
+      pos++;
+    } else if((word & 0xF800)==0) {
+      // will generate two UTF-8 bytes
+      // we have 0b110XXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>6) | 0b11000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else if((word &0xF800 ) != 0xD800) {
+      // will generate three UTF-8 bytes
+      // we have 0b1110XXXX 0b10XXXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>12) | 0b11100000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else {
+      // must be a surrogate pair
+      uint16_t diff = uint16_t(word - 0xD800);
+      if(pos + 1 >= len) { return 0; } // minimal bound checking
+      uint16_t next_word = big_endian ? utf16::swap_bytes(data[pos + 1]) : data[pos + 1];
+      uint16_t diff2 = uint16_t(next_word - 0xDC00);
+      uint32_t value = (diff << 10) + diff2 + 0x10000;
+      // will generate four UTF-8 bytes
+      // we have 0b11110XXX 0b10XXXXXX 0b10XXXXXX 0b10XXXXXX
+      *utf8_output++ = char((value>>18) | 0b11110000);
+      *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+      *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((value & 0b111111) | 0b10000000);
+      pos += 2;
+    }
+  }
+  return utf8_output - start;
+}
+
+} // utf16_to_utf8 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf16_to_utf8/valid_utf16_to_utf8.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf16_to_utf8/utf16_to_utf8.h
+/* begin file src/scalar/utf16_to_utf8/utf16_to_utf8.h */
+#ifndef SIMDUTF_UTF16_TO_UTF8_H
+#define SIMDUTF_UTF16_TO_UTF8_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf16_to_utf8 {
+
+template <endianness big_endian>
+inline size_t convert(const char16_t* buf, size_t len, char* utf8_output) {
+ const uint16_t *data = reinterpret_cast<const uint16_t *>(buf);
+  size_t pos = 0;
+  char* start{utf8_output};
+  while (pos < len) {
+    // try to convert the next block of 8 ASCII characters
+    if (pos + 4 <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v;
+      ::memcpy(&v, data + pos, sizeof(uint64_t));
+      if (big_endian) v = (v >> 8) | (v << (64 - 8));
+      if ((v & 0xFF80FF80FF80FF80) == 0) {
+        size_t final_pos = pos + 4;
+        while(pos < final_pos) {
+          *utf8_output++ = big_endian ? char(utf16::swap_bytes(buf[pos])) : char(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint16_t word = big_endian ? utf16::swap_bytes(data[pos]) : data[pos];
+    if((word & 0xFF80)==0) {
+      // will generate one UTF-8 bytes
+      *utf8_output++ = char(word);
+      pos++;
+    } else if((word & 0xF800)==0) {
+      // will generate two UTF-8 bytes
+      // we have 0b110XXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>6) | 0b11000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else if((word &0xF800 ) != 0xD800) {
+      // will generate three UTF-8 bytes
+      // we have 0b1110XXXX 0b10XXXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>12) | 0b11100000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else {
+      // must be a surrogate pair
+      if(pos + 1 >= len) { return 0; }
+      uint16_t diff = uint16_t(word - 0xD800);
+      if(diff > 0x3FF) { return 0; }
+      uint16_t next_word = big_endian ? utf16::swap_bytes(data[pos + 1]) : data[pos + 1];
+      uint16_t diff2 = uint16_t(next_word - 0xDC00);
+      if(diff2 > 0x3FF) { return 0; }
+      uint32_t value = (diff << 10) + diff2 + 0x10000;
+      // will generate four UTF-8 bytes
+      // we have 0b11110XXX 0b10XXXXXX 0b10XXXXXX 0b10XXXXXX
+      *utf8_output++ = char((value>>18) | 0b11110000);
+      *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+      *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((value & 0b111111) | 0b10000000);
+      pos += 2;
+    }
+  }
+  return utf8_output - start;
+}
+
+template <endianness big_endian>
+inline result convert_with_errors(const char16_t* buf, size_t len, char* utf8_output) {
+ const uint16_t *data = reinterpret_cast<const uint16_t *>(buf);
+  size_t pos = 0;
+  char* start{utf8_output};
+  while (pos < len) {
+    // try to convert the next block of 8 ASCII characters
+    if (pos + 4 <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v;
+      ::memcpy(&v, data + pos, sizeof(uint64_t));
+      if (big_endian) v = (v >> 8) | (v << (64 - 8));
+      if ((v & 0xFF80FF80FF80FF80) == 0) {
+        size_t final_pos = pos + 4;
+        while(pos < final_pos) {
+          *utf8_output++ = big_endian ? char(utf16::swap_bytes(buf[pos])) : char(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint16_t word = big_endian ? utf16::swap_bytes(data[pos]) : data[pos];
+    if((word & 0xFF80)==0) {
+      // will generate one UTF-8 bytes
+      *utf8_output++ = char(word);
+      pos++;
+    } else if((word & 0xF800)==0) {
+      // will generate two UTF-8 bytes
+      // we have 0b110XXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>6) | 0b11000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else if((word &0xF800 ) != 0xD800) {
+      // will generate three UTF-8 bytes
+      // we have 0b1110XXXX 0b10XXXXXX 0b10XXXXXX
+      *utf8_output++ = char((word>>12) | 0b11100000);
+      *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((word & 0b111111) | 0b10000000);
+      pos++;
+    } else {
+      // must be a surrogate pair
+      if(pos + 1 >= len) { return result(error_code::SURROGATE, pos); }
+      uint16_t diff = uint16_t(word - 0xD800);
+      if(diff > 0x3FF) { return result(error_code::SURROGATE, pos); }
+      uint16_t next_word = big_endian ? utf16::swap_bytes(data[pos + 1]) : data[pos + 1];
+      uint16_t diff2 = uint16_t(next_word - 0xDC00);
+      if(diff2 > 0x3FF) { return result(error_code::SURROGATE, pos); }
+      uint32_t value = (diff << 10) + diff2 + 0x10000;
+      // will generate four UTF-8 bytes
+      // we have 0b11110XXX 0b10XXXXXX 0b10XXXXXX 0b10XXXXXX
+      *utf8_output++ = char((value>>18) | 0b11110000);
+      *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+      *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+      *utf8_output++ = char((value & 0b111111) | 0b10000000);
+      pos += 2;
+    }
+  }
+  return result(error_code::SUCCESS, utf8_output - start);
+}
+
+} // utf16_to_utf8 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf16_to_utf8/utf16_to_utf8.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf16_to_utf32/valid_utf16_to_utf32.h
+/* begin file src/scalar/utf16_to_utf32/valid_utf16_to_utf32.h */
+#ifndef SIMDUTF_VALID_UTF16_TO_UTF32_H
+#define SIMDUTF_VALID_UTF16_TO_UTF32_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf16_to_utf32 {
+
+template <endianness big_endian>
+inline size_t convert_valid(const char16_t* buf, size_t len, char32_t* utf32_output) {
+ const uint16_t *data = reinterpret_cast<const uint16_t *>(buf);
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  while (pos < len) {
+    uint16_t word = big_endian ? utf16::swap_bytes(data[pos]) : data[pos];
+    if((word &0xF800 ) != 0xD800) {
+      // No surrogate pair, extend 16-bit word to 32-bit word
+      *utf32_output++ = char32_t(word);
+      pos++;
+    } else {
+      // must be a surrogate pair
+      uint16_t diff = uint16_t(word - 0xD800);
+      if(pos + 1 >= len) { return 0; } // minimal bound checking
+      uint16_t next_word = big_endian ? utf16::swap_bytes(data[pos + 1]) : data[pos + 1];
+      uint16_t diff2 = uint16_t(next_word - 0xDC00);
+      uint32_t value = (diff << 10) + diff2 + 0x10000;
+      *utf32_output++ = char32_t(value);
+      pos += 2;
+    }
+  }
+  return utf32_output - start;
+}
+
+} // utf16_to_utf32 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf16_to_utf32/valid_utf16_to_utf32.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf16_to_utf32/utf16_to_utf32.h
+/* begin file src/scalar/utf16_to_utf32/utf16_to_utf32.h */
+#ifndef SIMDUTF_UTF16_TO_UTF32_H
+#define SIMDUTF_UTF16_TO_UTF32_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf16_to_utf32 {
+
+template <endianness big_endian>
+inline size_t convert(const char16_t* buf, size_t len, char32_t* utf32_output) {
+ const uint16_t *data = reinterpret_cast<const uint16_t *>(buf);
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  while (pos < len) {
+    uint16_t word = big_endian ? utf16::swap_bytes(data[pos]) : data[pos];
+    if((word &0xF800 ) != 0xD800) {
+      // No surrogate pair, extend 16-bit word to 32-bit word
+      *utf32_output++ = char32_t(word);
+      pos++;
+    } else {
+      // must be a surrogate pair
+      uint16_t diff = uint16_t(word - 0xD800);
+      if(diff > 0x3FF) { return 0; }
+      if(pos + 1 >= len) { return 0; } // minimal bound checking
+      uint16_t next_word = big_endian ? utf16::swap_bytes(data[pos + 1]) : data[pos + 1];
+      uint16_t diff2 = uint16_t(next_word - 0xDC00);
+      if(diff2 > 0x3FF) { return 0; }
+      uint32_t value = (diff << 10) + diff2 + 0x10000;
+      *utf32_output++ = char32_t(value);
+      pos += 2;
+    }
+  }
+  return utf32_output - start;
+}
+
+template <endianness big_endian>
+inline result convert_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) {
+ const uint16_t *data = reinterpret_cast<const uint16_t *>(buf);
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  while (pos < len) {
+    uint16_t word = big_endian ? utf16::swap_bytes(data[pos]) : data[pos];
+    if((word &0xF800 ) != 0xD800) {
+      // No surrogate pair, extend 16-bit word to 32-bit word
+      *utf32_output++ = char32_t(word);
+      pos++;
+    } else {
+      // must be a surrogate pair
+      uint16_t diff = uint16_t(word - 0xD800);
+      if(diff > 0x3FF) { return result(error_code::SURROGATE, pos); }
+      if(pos + 1 >= len) { return result(error_code::SURROGATE, pos); } // minimal bound checking
+      uint16_t next_word = big_endian ? utf16::swap_bytes(data[pos + 1]) : data[pos + 1];
+      uint16_t diff2 = uint16_t(next_word - 0xDC00);
+      if(diff2 > 0x3FF) { return result(error_code::SURROGATE, pos); }
+      uint32_t value = (diff << 10) + diff2 + 0x10000;
+      *utf32_output++ = char32_t(value);
+      pos += 2;
+    }
+  }
+  return result(error_code::SUCCESS, utf32_output - start);
+}
+
+} // utf16_to_utf32 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf16_to_utf32/utf16_to_utf32.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf8_to_utf16/valid_utf8_to_utf16.h
+/* begin file src/scalar/utf8_to_utf16/valid_utf8_to_utf16.h */
+#ifndef SIMDUTF_VALID_UTF8_TO_UTF16_H
+#define SIMDUTF_VALID_UTF8_TO_UTF16_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf8_to_utf16 {
+
+template <endianness big_endian>
+inline size_t convert_valid(const char* buf, size_t len, char16_t* utf16_output) {
+ const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  while (pos < len) {
+    // try to convert the next block of 8 ASCII bytes
+    if (pos + 8 <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v;
+      ::memcpy(&v, data + pos, sizeof(uint64_t));
+      if ((v & 0x8080808080808080) == 0) {
+        size_t final_pos = pos + 8;
+        while(pos < final_pos) {
+          *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(buf[pos])) : char16_t(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint8_t leading_byte = data[pos]; // leading byte
+    if (leading_byte < 0b10000000) {
+      // converting one ASCII byte !!!
+      *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(leading_byte)) : char16_t(leading_byte);
+      pos++;
+    } else if ((leading_byte & 0b11100000) == 0b11000000) {
+      // We have a two-byte UTF-8, it should become
+      // a single UTF-16 word.
+      if(pos + 1 >= len) { break; } // minimal bound checking
+      uint16_t code_point = uint16_t(((leading_byte &0b00011111) << 6) | (data[pos + 1] &0b00111111));
+      if (big_endian) {
+        code_point = utf16::swap_bytes(uint16_t(code_point));
+      }
+      *utf16_output++ = char16_t(code_point);
+      pos += 2;
+    } else if ((leading_byte & 0b11110000) == 0b11100000) {
+      // We have a three-byte UTF-8, it should become
+      // a single UTF-16 word.
+      if(pos + 2 >= len) { break; } // minimal bound checking
+      uint16_t code_point = uint16_t(((leading_byte &0b00001111) << 12) | ((data[pos + 1] &0b00111111) << 6) | (data[pos + 2] &0b00111111));
+      if (big_endian) {
+        code_point = utf16::swap_bytes(uint16_t(code_point));
+      }
+      *utf16_output++ = char16_t(code_point);
+      pos += 3;
+    } else if ((leading_byte & 0b11111000) == 0b11110000) { // 0b11110000
+      // we have a 4-byte UTF-8 word.
+      if(pos + 3 >= len) { break; } // minimal bound checking
+      uint32_t code_point = ((leading_byte & 0b00000111) << 18 )| ((data[pos + 1] &0b00111111) << 12)
+                           | ((data[pos + 2] &0b00111111) << 6) | (data[pos + 3] &0b00111111);
+      code_point -= 0x10000;
+      uint16_t high_surrogate = uint16_t(0xD800 + (code_point >> 10));
+      uint16_t low_surrogate = uint16_t(0xDC00 + (code_point & 0x3FF));
+      if (big_endian) {
+        high_surrogate = utf16::swap_bytes(high_surrogate);
+        low_surrogate = utf16::swap_bytes(low_surrogate);
+      }
+      *utf16_output++ = char16_t(high_surrogate);
+      *utf16_output++ = char16_t(low_surrogate);
+      pos += 4;
+    } else {
+      // we may have a continuation but we do not do error checking
+      return 0;
+    }
+  }
+  return utf16_output - start;
+}
+
+
+} // namespace utf8_to_utf16
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf8_to_utf16/valid_utf8_to_utf16.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf8_to_utf16/utf8_to_utf16.h
+/* begin file src/scalar/utf8_to_utf16/utf8_to_utf16.h */
+#ifndef SIMDUTF_UTF8_TO_UTF16_H
+#define SIMDUTF_UTF8_TO_UTF16_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf8_to_utf16 {
+
+template <endianness big_endian>
+inline size_t convert(const char* buf, size_t len, char16_t* utf16_output) {
+ const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  while (pos < len) {
+    // try to convert the next block of 16 ASCII bytes
+    if (pos + 16 <= len) { // if it is safe to read 16 more bytes, check that they are ascii
+      uint64_t v1;
+      ::memcpy(&v1, data + pos, sizeof(uint64_t));
+      uint64_t v2;
+      ::memcpy(&v2, data + pos + sizeof(uint64_t), sizeof(uint64_t));
+      uint64_t v{v1 | v2};
+      if ((v & 0x8080808080808080) == 0) {
+        size_t final_pos = pos + 16;
+        while(pos < final_pos) {
+          *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(buf[pos])) : char16_t(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint8_t leading_byte = data[pos]; // leading byte
+    if (leading_byte < 0b10000000) {
+      // converting one ASCII byte !!!
+      *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(leading_byte)): char16_t(leading_byte);
+      pos++;
+    } else if ((leading_byte & 0b11100000) == 0b11000000) {
+      // We have a two-byte UTF-8, it should become
+      // a single UTF-16 word.
+      if(pos + 1 >= len) { return 0; } // minimal bound checking
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return 0; }
+      // range check
+      uint32_t code_point = (leading_byte & 0b00011111) << 6 | (data[pos + 1] & 0b00111111);
+      if (code_point < 0x80 || 0x7ff < code_point) { return 0; }
+      if (big_endian) {
+        code_point = uint32_t(utf16::swap_bytes(uint16_t(code_point)));
+      }
+      *utf16_output++ = char16_t(code_point);
+      pos += 2;
+    } else if ((leading_byte & 0b11110000) == 0b11100000) {
+      // We have a three-byte UTF-8, it should become
+      // a single UTF-16 word.
+      if(pos + 2 >= len) { return 0; } // minimal bound checking
+
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return 0; }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return 0; }
+      // range check
+      uint32_t code_point = (leading_byte & 0b00001111) << 12 |
+                   (data[pos + 1] & 0b00111111) << 6 |
+                   (data[pos + 2] & 0b00111111);
+      if (code_point < 0x800 || 0xffff < code_point ||
+          (0xd7ff < code_point && code_point < 0xe000)) {
+        return 0;
+      }
+      if (big_endian) {
+        code_point = uint32_t(utf16::swap_bytes(uint16_t(code_point)));
+      }
+      *utf16_output++ = char16_t(code_point);
+      pos += 3;
+    } else if ((leading_byte & 0b11111000) == 0b11110000) { // 0b11110000
+      // we have a 4-byte UTF-8 word.
+      if(pos + 3 >= len) { return 0; } // minimal bound checking
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return 0; }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return 0; }
+      if ((data[pos + 3] & 0b11000000) != 0b10000000) { return 0; }
+
+      // range check
+      uint32_t code_point =
+          (leading_byte & 0b00000111) << 18 | (data[pos + 1] & 0b00111111) << 12 |
+          (data[pos + 2] & 0b00111111) << 6 | (data[pos + 3] & 0b00111111);
+      if (code_point <= 0xffff || 0x10ffff < code_point) { return 0; }
+      code_point -= 0x10000;
+      uint16_t high_surrogate = uint16_t(0xD800 + (code_point >> 10));
+      uint16_t low_surrogate = uint16_t(0xDC00 + (code_point & 0x3FF));
+      if (big_endian) {
+        high_surrogate = utf16::swap_bytes(high_surrogate);
+        low_surrogate = utf16::swap_bytes(low_surrogate);
+      }
+      *utf16_output++ = char16_t(high_surrogate);
+      *utf16_output++ = char16_t(low_surrogate);
+      pos += 4;
+    } else {
+      return 0;
+    }
+  }
+  return utf16_output - start;
+}
+
+template <endianness big_endian>
+inline result convert_with_errors(const char* buf, size_t len, char16_t* utf16_output) {
+ const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  while (pos < len) {
+    // try to convert the next block of 16 ASCII bytes
+    if (pos + 16 <= len) { // if it is safe to read 16 more bytes, check that they are ascii
+      uint64_t v1;
+      ::memcpy(&v1, data + pos, sizeof(uint64_t));
+      uint64_t v2;
+      ::memcpy(&v2, data + pos + sizeof(uint64_t), sizeof(uint64_t));
+      uint64_t v{v1 | v2};
+      if ((v & 0x8080808080808080) == 0) {
+        size_t final_pos = pos + 16;
+        while(pos < final_pos) {
+          *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(buf[pos])) : char16_t(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint8_t leading_byte = data[pos]; // leading byte
+    if (leading_byte < 0b10000000) {
+      // converting one ASCII byte !!!
+      *utf16_output++ = big_endian ? char16_t(utf16::swap_bytes(leading_byte)): char16_t(leading_byte);
+      pos++;
+    } else if ((leading_byte & 0b11100000) == 0b11000000) {
+      // We have a two-byte UTF-8, it should become
+      // a single UTF-16 word.
+      if(pos + 1 >= len) { return result(error_code::TOO_SHORT, pos); } // minimal bound checking
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      // range check
+      uint32_t code_point = (leading_byte & 0b00011111) << 6 | (data[pos + 1] & 0b00111111);
+      if (code_point < 0x80 || 0x7ff < code_point) { return result(error_code::OVERLONG, pos); }
+      if (big_endian) {
+        code_point = uint32_t(utf16::swap_bytes(uint16_t(code_point)));
+      }
+      *utf16_output++ = char16_t(code_point);
+      pos += 2;
+    } else if ((leading_byte & 0b11110000) == 0b11100000) {
+      // We have a three-byte UTF-8, it should become
+      // a single UTF-16 word.
+      if(pos + 2 >= len) { return result(error_code::TOO_SHORT, pos); } // minimal bound checking
+
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      // range check
+      uint32_t code_point = (leading_byte & 0b00001111) << 12 |
+                   (data[pos + 1] & 0b00111111) << 6 |
+                   (data[pos + 2] & 0b00111111);
+      if ((code_point < 0x800) || (0xffff < code_point)) { return result(error_code::OVERLONG, pos);}
+      if (0xd7ff < code_point && code_point < 0xe000) { return result(error_code::SURROGATE, pos); }
+      if (big_endian) {
+        code_point = uint32_t(utf16::swap_bytes(uint16_t(code_point)));
+      }
+      *utf16_output++ = char16_t(code_point);
+      pos += 3;
+    } else if ((leading_byte & 0b11111000) == 0b11110000) { // 0b11110000
+      // we have a 4-byte UTF-8 word.
+      if(pos + 3 >= len) { return result(error_code::TOO_SHORT, pos); } // minimal bound checking
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 3] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+
+      // range check
+      uint32_t code_point =
+          (leading_byte & 0b00000111) << 18 | (data[pos + 1] & 0b00111111) << 12 |
+          (data[pos + 2] & 0b00111111) << 6 | (data[pos + 3] & 0b00111111);
+      if (code_point <= 0xffff) { return result(error_code::OVERLONG, pos); }
+      if (0x10ffff < code_point) { return result(error_code::TOO_LARGE, pos); }
+      code_point -= 0x10000;
+      uint16_t high_surrogate = uint16_t(0xD800 + (code_point >> 10));
+      uint16_t low_surrogate = uint16_t(0xDC00 + (code_point & 0x3FF));
+      if (big_endian) {
+        high_surrogate = utf16::swap_bytes(high_surrogate);
+        low_surrogate = utf16::swap_bytes(low_surrogate);
+      }
+      *utf16_output++ = char16_t(high_surrogate);
+      *utf16_output++ = char16_t(low_surrogate);
+      pos += 4;
+    } else {
+      // we either have too many continuation bytes or an invalid leading byte
+      if ((leading_byte & 0b11000000) == 0b10000000) { return result(error_code::TOO_LONG, pos); }
+      else { return result(error_code::HEADER_BITS, pos); }
+    }
+  }
+  return result(error_code::SUCCESS, utf16_output - start);
+}
+
+template <endianness endian>
+inline result rewind_and_convert_with_errors(const char* buf, size_t len, char16_t* utf16_output) {
+  size_t extra_len{0};
+  // A leading byte cannot be further than 4 bytes away
+  for(int i = 0; i < 5; i++) {
+    unsigned char byte = *buf;
+    if ((byte & 0b11000000) != 0b10000000) {
+      break;
+    } else {
+      buf--;
+      extra_len++;
+    }
+  }
+
+  result res = convert_with_errors<endian>(buf, len + extra_len, utf16_output);
+  if (res.error) {
+    res.count -= extra_len;
+  }
+  return res;
+}
+
+} // utf8_to_utf16 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf8_to_utf16/utf8_to_utf16.h */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf8_to_utf32/valid_utf8_to_utf32.h
+/* begin file src/scalar/utf8_to_utf32/valid_utf8_to_utf32.h */
+#ifndef SIMDUTF_VALID_UTF8_TO_UTF32_H
+#define SIMDUTF_VALID_UTF8_TO_UTF32_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf8_to_utf32 {
+
+inline size_t convert_valid(const char* buf, size_t len, char32_t* utf32_output) {
+ const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  while (pos < len) {
+    // try to convert the next block of 8 ASCII bytes
+    if (pos + 8 <= len) { // if it is safe to read 8 more bytes, check that they are ascii
+      uint64_t v;
+      ::memcpy(&v, data + pos, sizeof(uint64_t));
+      if ((v & 0x8080808080808080) == 0) {
+        size_t final_pos = pos + 8;
+        while(pos < final_pos) {
+          *utf32_output++ = char32_t(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint8_t leading_byte = data[pos]; // leading byte
+    if (leading_byte < 0b10000000) {
+      // converting one ASCII byte !!!
+      *utf32_output++ = char32_t(leading_byte);
+      pos++;
+    } else if ((leading_byte & 0b11100000) == 0b11000000) {
+      // We have a two-byte UTF-8
+      if(pos + 1 >= len) { break; } // minimal bound checking
+      *utf32_output++ = char32_t(((leading_byte &0b00011111) << 6) | (data[pos + 1] &0b00111111));
+      pos += 2;
+    } else if ((leading_byte & 0b11110000) == 0b11100000) {
+      // We have a three-byte UTF-8
+      if(pos + 2 >= len) { break; } // minimal bound checking
+      *utf32_output++ = char32_t(((leading_byte &0b00001111) << 12) | ((data[pos + 1] &0b00111111) << 6) | (data[pos + 2] &0b00111111));
+      pos += 3;
+    } else if ((leading_byte & 0b11111000) == 0b11110000) { // 0b11110000
+      // we have a 4-byte UTF-8 word.
+      if(pos + 3 >= len) { break; } // minimal bound checking
+      uint32_t code_word = ((leading_byte & 0b00000111) << 18 )| ((data[pos + 1] &0b00111111) << 12)
+                           | ((data[pos + 2] &0b00111111) << 6) | (data[pos + 3] &0b00111111);
+      *utf32_output++ = char32_t(code_word);
+      pos += 4;
+    } else {
+      // we may have a continuation but we do not do error checking
+      return 0;
+    }
+  }
+  return utf32_output - start;
+}
+
+
+} // namespace utf8_to_utf32
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf8_to_utf32/valid_utf8_to_utf32.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=scalar/utf8_to_utf32/utf8_to_utf32.h
+/* begin file src/scalar/utf8_to_utf32/utf8_to_utf32.h */
+#ifndef SIMDUTF_UTF8_TO_UTF32_H
+#define SIMDUTF_UTF8_TO_UTF32_H
+
+namespace simdutf {
+namespace scalar {
+namespace {
+namespace utf8_to_utf32 {
+
+inline size_t convert(const char* buf, size_t len, char32_t* utf32_output) {
+ const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  while (pos < len) {
+    // try to convert the next block of 16 ASCII bytes
+    if (pos + 16 <= len) { // if it is safe to read 16 more bytes, check that they are ascii
+      uint64_t v1;
+      ::memcpy(&v1, data + pos, sizeof(uint64_t));
+      uint64_t v2;
+      ::memcpy(&v2, data + pos + sizeof(uint64_t), sizeof(uint64_t));
+      uint64_t v{v1 | v2};
+      if ((v & 0x8080808080808080) == 0) {
+        size_t final_pos = pos + 16;
+        while(pos < final_pos) {
+          *utf32_output++ = char32_t(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint8_t leading_byte = data[pos]; // leading byte
+    if (leading_byte < 0b10000000) {
+      // converting one ASCII byte !!!
+      *utf32_output++ = char32_t(leading_byte);
+      pos++;
+    } else if ((leading_byte & 0b11100000) == 0b11000000) {
+      // We have a two-byte UTF-8
+      if(pos + 1 >= len) { return 0; } // minimal bound checking
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return 0; }
+      // range check
+      uint32_t code_point = (leading_byte & 0b00011111) << 6 | (data[pos + 1] & 0b00111111);
+      if (code_point < 0x80 || 0x7ff < code_point) { return 0; }
+      *utf32_output++ = char32_t(code_point);
+      pos += 2;
+    } else if ((leading_byte & 0b11110000) == 0b11100000) {
+      // We have a three-byte UTF-8
+      if(pos + 2 >= len) { return 0; } // minimal bound checking
+
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return 0; }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return 0; }
+      // range check
+      uint32_t code_point = (leading_byte & 0b00001111) << 12 |
+                   (data[pos + 1] & 0b00111111) << 6 |
+                   (data[pos + 2] & 0b00111111);
+      if (code_point < 0x800 || 0xffff < code_point ||
+          (0xd7ff < code_point && code_point < 0xe000)) {
+        return 0;
+      }
+      *utf32_output++ = char32_t(code_point);
+      pos += 3;
+    } else if ((leading_byte & 0b11111000) == 0b11110000) { // 0b11110000
+      // we have a 4-byte UTF-8 word.
+      if(pos + 3 >= len) { return 0; } // minimal bound checking
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return 0; }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return 0; }
+      if ((data[pos + 3] & 0b11000000) != 0b10000000) { return 0; }
+
+      // range check
+      uint32_t code_point =
+          (leading_byte & 0b00000111) << 18 | (data[pos + 1] & 0b00111111) << 12 |
+          (data[pos + 2] & 0b00111111) << 6 | (data[pos + 3] & 0b00111111);
+      if (code_point <= 0xffff || 0x10ffff < code_point) { return 0; }
+      *utf32_output++ = char32_t(code_point);
+      pos += 4;
+    } else {
+      return 0;
+    }
+  }
+  return utf32_output - start;
+}
+
+inline result convert_with_errors(const char* buf, size_t len, char32_t* utf32_output) {
+ const uint8_t *data = reinterpret_cast<const uint8_t *>(buf);
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  while (pos < len) {
+    // try to convert the next block of 16 ASCII bytes
+    if (pos + 16 <= len) { // if it is safe to read 16 more bytes, check that they are ascii
+      uint64_t v1;
+      ::memcpy(&v1, data + pos, sizeof(uint64_t));
+      uint64_t v2;
+      ::memcpy(&v2, data + pos + sizeof(uint64_t), sizeof(uint64_t));
+      uint64_t v{v1 | v2};
+      if ((v & 0x8080808080808080) == 0) {
+        size_t final_pos = pos + 16;
+        while(pos < final_pos) {
+          *utf32_output++ = char32_t(buf[pos]);
+          pos++;
+        }
+        continue;
+      }
+    }
+    uint8_t leading_byte = data[pos]; // leading byte
+    if (leading_byte < 0b10000000) {
+      // converting one ASCII byte !!!
+      *utf32_output++ = char32_t(leading_byte);
+      pos++;
+    } else if ((leading_byte & 0b11100000) == 0b11000000) {
+      // We have a two-byte UTF-8
+      if(pos + 1 >= len) { return result(error_code::TOO_SHORT, pos); } // minimal bound checking
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      // range check
+      uint32_t code_point = (leading_byte & 0b00011111) << 6 | (data[pos + 1] & 0b00111111);
+      if (code_point < 0x80 || 0x7ff < code_point) { return result(error_code::OVERLONG, pos); }
+      *utf32_output++ = char32_t(code_point);
+      pos += 2;
+    } else if ((leading_byte & 0b11110000) == 0b11100000) {
+      // We have a three-byte UTF-8
+      if(pos + 2 >= len) { return result(error_code::TOO_SHORT, pos); } // minimal bound checking
+
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      // range check
+      uint32_t code_point = (leading_byte & 0b00001111) << 12 |
+                   (data[pos + 1] & 0b00111111) << 6 |
+                   (data[pos + 2] & 0b00111111);
+      if (code_point < 0x800 || 0xffff < code_point) { return result(error_code::OVERLONG, pos); }
+      if (0xd7ff < code_point && code_point < 0xe000) { return result(error_code::SURROGATE, pos); }
+      *utf32_output++ = char32_t(code_point);
+      pos += 3;
+    } else if ((leading_byte & 0b11111000) == 0b11110000) { // 0b11110000
+      // we have a 4-byte UTF-8 word.
+      if(pos + 3 >= len) { return result(error_code::TOO_SHORT, pos); } // minimal bound checking
+      if ((data[pos + 1] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos);}
+      if ((data[pos + 2] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+      if ((data[pos + 3] & 0b11000000) != 0b10000000) { return result(error_code::TOO_SHORT, pos); }
+
+      // range check
+      uint32_t code_point =
+          (leading_byte & 0b00000111) << 18 | (data[pos + 1] & 0b00111111) << 12 |
+          (data[pos + 2] & 0b00111111) << 6 | (data[pos + 3] & 0b00111111);
+      if (code_point <= 0xffff) { return result(error_code::OVERLONG, pos); }
+      if (0x10ffff < code_point) { return result(error_code::TOO_LARGE, pos); }
+      *utf32_output++ = char32_t(code_point);
+      pos += 4;
+    } else {
+      // we either have too many continuation bytes or an invalid leading byte
+      if ((leading_byte & 0b11000000) == 0b10000000) { return result(error_code::TOO_LONG, pos); }
+      else { return result(error_code::HEADER_BITS, pos); }
+    }
+  }
+  return result(error_code::SUCCESS, utf32_output - start);
+}
+
+inline result rewind_and_convert_with_errors(const char* buf, size_t len, char32_t* utf32_output) {
+  size_t extra_len{0};
+  // A leading byte cannot be further than 4 bytes away
+  for(int i = 0; i < 5; i++) {
+    unsigned char byte = *buf;
+    if ((byte & 0b11000000) != 0b10000000) {
+      break;
+    } else {
+      buf--;
+      extra_len++;
+    }
+  }
+
+  result res = convert_with_errors(buf, len + extra_len, utf32_output);
+  if (res.error) {
+    res.count -= extra_len;
+  }
+  return res;
+}
+
+} // utf8_to_utf32 namespace
+} // unnamed namespace
+} // namespace scalar
+} // namespace simdutf
+
+#endif
+/* end file src/scalar/utf8_to_utf32/utf8_to_utf32.h */
+//
+
+
+SIMDUTF_PUSH_DISABLE_WARNINGS
+SIMDUTF_DISABLE_UNDESIRED_WARNINGS
+
+
+#if SIMDUTF_IMPLEMENTATION_ARM64
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/implementation.cpp
+/* begin file src/arm64/implementation.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/begin.h
+/* begin file src/simdutf/arm64/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "arm64"
+// #define SIMDUTF_IMPLEMENTATION arm64
+/* end file src/simdutf/arm64/begin.h */
+namespace simdutf {
+namespace arm64 {
+namespace {
+#ifndef SIMDUTF_ARM64_H
+#error "arm64.h must be included"
+#endif
+using namespace simd;
+
+simdutf_really_inline bool is_ascii(const simd8x64<uint8_t>& input) {
+    simd8<uint8_t> bits = input.reduce_or();
+    return bits.max_val() < 0b10000000u;
+}
+
+simdutf_unused simdutf_really_inline simd8<bool> must_be_continuation(const simd8<uint8_t> prev1, const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
+    simd8<bool> is_second_byte = prev1 >= uint8_t(0b11000000u);
+    simd8<bool> is_third_byte  = prev2 >= uint8_t(0b11100000u);
+    simd8<bool> is_fourth_byte = prev3 >= uint8_t(0b11110000u);
+    // Use ^ instead of | for is_*_byte, because ^ is commutative, and the caller is using ^ as well.
+    // This will work fine because we only have to report errors for cases with 0-1 lead bytes.
+    // Multiple lead bytes implies 2 overlapping multibyte characters, and if that happens, there is
+    // guaranteed to be at least *one* lead byte that is part of only 1 other multibyte character.
+    // The error will be detected there.
+    return is_second_byte ^ is_third_byte ^ is_fourth_byte;
+}
+
+simdutf_really_inline simd8<bool> must_be_2_3_continuation(const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
+    simd8<bool> is_third_byte  = prev2 >= uint8_t(0b11100000u);
+    simd8<bool> is_fourth_byte = prev3 >= uint8_t(0b11110000u);
+    return is_third_byte ^ is_fourth_byte;
+}
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_detect_encodings.cpp
+/* begin file src/arm64/arm_detect_encodings.cpp */
+template<class checker>
+// len is known to be a multiple of 2 when this is called
+int arm_detect_encodings(const char * buf, size_t len) {
+    const char* start = buf;
+    const char* end = buf + len;
+
+    bool is_utf8 = true;
+    bool is_utf16 = true;
+    bool is_utf32 = true;
+
+    int out = 0;
+
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+
+    uint32x4_t currentmax = vmovq_n_u32(0x0);
+
+    checker check{};
+
+    while(buf + 64 <= end) {
+        uint16x8_t in = vld1q_u16(reinterpret_cast<const uint16_t*>(buf));
+        uint16x8_t secondin = vld1q_u16(reinterpret_cast<const uint16_t*>(buf) + simd16<uint16_t>::SIZE / sizeof(char16_t));
+        uint16x8_t thirdin = vld1q_u16(reinterpret_cast<const uint16_t*>(buf) + 2*simd16<uint16_t>::SIZE / sizeof(char16_t));
+        uint16x8_t fourthin = vld1q_u16(reinterpret_cast<const uint16_t*>(buf) + 3*simd16<uint16_t>::SIZE / sizeof(char16_t));
+
+        const auto u0 = simd16<uint16_t>(in);
+        const auto u1 = simd16<uint16_t>(secondin);
+        const auto u2 = simd16<uint16_t>(thirdin);
+        const auto u3 = simd16<uint16_t>(fourthin);
+
+        const auto v0 = u0.shr<8>();
+        const auto v1 = u1.shr<8>();
+        const auto v2 = u2.shr<8>();
+        const auto v3 = u3.shr<8>();
+
+        const auto in16 = simd16<uint16_t>::pack(v0, v1);
+        const auto nextin16 = simd16<uint16_t>::pack(v2, v3);
+
+        const uint64_t surrogates_wordmask0 = ((in16 & v_f8) == v_d8).to_bitmask64();
+        const uint64_t surrogates_wordmask1 = ((nextin16 & v_f8) == v_d8).to_bitmask64();
+
+        // Check for surrogates
+        if (surrogates_wordmask0 != 0 || surrogates_wordmask1 != 0) {
+            // Cannot be UTF8
+            is_utf8 = false;
+            // Can still be either UTF-16LE or UTF-32LE depending on the positions of the surrogates
+            // To be valid UTF-32LE, a surrogate cannot be in the two most significant bytes of any 32-bit word.
+            // On the other hand, to be valid UTF-16LE, at least one surrogate must be in the two most significant
+            // bytes of a 32-bit word since they always come in pairs in UTF-16LE.
+            // Note that we always proceed in multiple of 4 before this point so there is no offset in 32-bit words.
+
+            if (((surrogates_wordmask0 | surrogates_wordmask1) & 0xf0f0f0f0f0f0f0f0) != 0) {
+                is_utf32 = false;
+                // Code from arm_validate_utf16le.cpp
+                // Not efficient, we do not process surrogates_wordmask1
+                const char16_t * input = reinterpret_cast<const char16_t*>(buf);
+                const char16_t* end16 = reinterpret_cast<const char16_t*>(start) + len/2;
+
+                const auto v_fc = simd8<uint8_t>::splat(0xfc);
+                const auto v_dc = simd8<uint8_t>::splat(0xdc);
+
+                const uint64_t V0 = ~surrogates_wordmask0;
+
+                const auto vH0 = ((in16 & v_fc) ==  v_dc);
+                const uint64_t H0 = vH0.to_bitmask64();
+
+                const uint64_t L0 = ~H0 & surrogates_wordmask0;
+
+                const uint64_t a0 = L0 & (H0 >> 4);
+
+                const uint64_t b0 = a0 << 4;
+
+                const uint64_t c0 = V0 | a0 | b0;
+                if (c0 == ~0ull) {
+                    input += 16;
+                } else if (c0 == 0xfffffffffffffffull) {
+                    input += 15;
+                } else {
+                    is_utf16 = false;
+                    break;
+                }
+
+                while (input + 16 < end16) {
+                    const auto in0 = simd16<uint16_t>(input);
+                    const auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::SIZE / sizeof(char16_t));
+                    const auto t0 = in0.shr<8>();
+                    const auto t1 = in1.shr<8>();
+                    const simd8<uint8_t> in_16 = simd16<uint16_t>::pack(t0, t1);
+
+                    const uint64_t surrogates_wordmask = ((in_16 & v_f8) == v_d8).to_bitmask64();
+                    if(surrogates_wordmask == 0) {
+                        input += 16;
+                    } else {
+                        const uint64_t V = ~surrogates_wordmask;
+
+                        const auto vH = ((in_16 & v_fc) ==  v_dc);
+                        const uint64_t H = vH.to_bitmask64();
+
+                        const uint64_t L = ~H & surrogates_wordmask;
+
+                        const uint64_t a = L & (H >> 4);
+
+                        const uint64_t b = a << 4;
+
+                        const uint64_t c = V | a | b;
+                        if (c == ~0ull) {
+                            input += 16;
+                        } else if (c == 0xfffffffffffffffull) {
+                            input += 15;
+                        } else {
+                            is_utf16 = false;
+                            break;
+                        }
+                    }
+                }
+            } else {
+                is_utf16 = false;
+                // Check for UTF-32LE
+                if (len % 4 == 0) {
+                    const char32_t * input = reinterpret_cast<const char32_t*>(buf);
+                    const char32_t* end32 = reinterpret_cast<const char32_t*>(start) + len/4;
+
+                    // Must start checking for surrogates
+                    uint32x4_t currentoffsetmax = vmovq_n_u32(0x0);
+                    const uint32x4_t offset = vmovq_n_u32(0xffff2000);
+                    const uint32x4_t standardoffsetmax = vmovq_n_u32(0xfffff7ff);
+
+                    const uint32x4_t in32 =  vreinterpretq_u32_u16(in);
+                    const uint32x4_t secondin32 =  vreinterpretq_u32_u16(secondin);
+                    const uint32x4_t thirdin32 =  vreinterpretq_u32_u16(thirdin);
+                    const uint32x4_t fourthin32 =  vreinterpretq_u32_u16(fourthin);
+
+                    currentmax = vmaxq_u32(in32,currentmax);
+                    currentmax = vmaxq_u32(secondin32,currentmax);
+                    currentmax = vmaxq_u32(thirdin32,currentmax);
+                    currentmax = vmaxq_u32(fourthin32,currentmax);
+
+                    currentoffsetmax = vmaxq_u32(vaddq_u32(in32, offset), currentoffsetmax);
+                    currentoffsetmax = vmaxq_u32(vaddq_u32(secondin32, offset), currentoffsetmax);
+                    currentoffsetmax = vmaxq_u32(vaddq_u32(thirdin32, offset), currentoffsetmax);
+                    currentoffsetmax = vmaxq_u32(vaddq_u32(fourthin32, offset), currentoffsetmax);
+
+                    while (input + 4 < end32) {
+                        const uint32x4_t in_32 = vld1q_u32(reinterpret_cast<const uint32_t*>(input));
+                        currentmax = vmaxq_u32(in_32,currentmax);
+                        currentoffsetmax = vmaxq_u32(vaddq_u32(in_32, offset), currentoffsetmax);
+                        input += 4;
+                    }
+
+                    uint32x4_t forbidden_words = veorq_u32(vmaxq_u32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+                    if(vmaxvq_u32(forbidden_words) != 0) {
+                        is_utf32 = false;
+                    }
+                } else {
+                    is_utf32 = false;
+                }
+            }
+            break;
+        }
+        // If no surrogate, validate under other encodings as well
+
+        // UTF-32LE validation
+        currentmax = vmaxq_u32(vreinterpretq_u32_u16(in),currentmax);
+        currentmax = vmaxq_u32(vreinterpretq_u32_u16(secondin),currentmax);
+        currentmax = vmaxq_u32(vreinterpretq_u32_u16(thirdin),currentmax);
+        currentmax = vmaxq_u32(vreinterpretq_u32_u16(fourthin),currentmax);
+
+        // UTF-8 validation
+        // Relies on ../generic/utf8_validation/utf8_lookup4_algorithm.h
+        simd::simd8x64<uint8_t> in8(vreinterpretq_u8_u16(in), vreinterpretq_u8_u16(secondin), vreinterpretq_u8_u16(thirdin), vreinterpretq_u8_u16(fourthin));
+        check.check_next_input(in8);
+
+        buf += 64;
+    }
+
+    // Check which encodings are possible
+
+    if (is_utf8) {
+        if (static_cast<size_t>(buf - start) != len) {
+            uint8_t block[64]{};
+            std::memset(block, 0x20, 64);
+            std::memcpy(block, buf, len - (buf - start));
+            simd::simd8x64<uint8_t> in(block);
+            check.check_next_input(in);
+        }
+        if (!check.errors()) {
+            out |= simdutf::encoding_type::UTF8;
+        }
+    }
+
+    if (is_utf16 && scalar::utf16::validate<endianness::LITTLE>(reinterpret_cast<const char16_t*>(buf), (len - (buf - start))/2)) {
+        out |= simdutf::encoding_type::UTF16_LE;
+    }
+
+    if (is_utf32 && (len % 4 == 0)) {
+        const uint32x4_t standardmax = vmovq_n_u32(0x10ffff);
+        uint32x4_t is_zero = veorq_u32(vmaxq_u32(currentmax, standardmax), standardmax);
+        if (vmaxvq_u32(is_zero) == 0 && scalar::utf32::validate(reinterpret_cast<const char32_t*>(buf), (len - (buf - start))/4)) {
+            out |= simdutf::encoding_type::UTF32_LE;
+        }
+    }
+
+    return out;
+}
+/* end file src/arm64/arm_detect_encodings.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_validate_utf16.cpp
+/* begin file src/arm64/arm_validate_utf16.cpp */
+template <endianness big_endian>
+const char16_t* arm_validate_utf16(const char16_t* input, size_t size) {
+    const char16_t* end = input + size;
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+    const auto v_fc = simd8<uint8_t>::splat(0xfc);
+    const auto v_dc = simd8<uint8_t>::splat(0xdc);
+    while (input + 16 < end) {
+        // 0. Load data: since the validation takes into account only higher
+        //    byte of each word, we compress the two vectors into one which
+        //    consists only the higher bytes.
+        auto in0 = simd16<uint16_t>(input);
+        auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::SIZE / sizeof(char16_t));
+        if (big_endian) {
+            #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+            const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+            #else
+            const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+            #endif
+            in0 = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in0), swap));
+            in1 = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in1), swap));
+        }
+        const auto t0 = in0.shr<8>();
+        const auto t1 = in1.shr<8>();
+        const simd8<uint8_t> in = simd16<uint16_t>::pack(t0, t1);
+        // 1. Check whether we have any 0xD800..DFFF word (0b1101'1xxx'yyyy'yyyy).
+        const uint64_t surrogates_wordmask = ((in & v_f8) == v_d8).to_bitmask64();
+        if(surrogates_wordmask == 0) {
+            input += 16;
+        } else {
+            // 2. We have some surrogates that have to be distinguished:
+            //    - low  surrogates: 0b1101'10xx'yyyy'yyyy (0xD800..0xDBFF)
+            //    - high surrogates: 0b1101'11xx'yyyy'yyyy (0xDC00..0xDFFF)
+            //
+            //    Fact: high surrogate has 11th bit set (3rd bit in the higher word)
+
+            // V - non-surrogate words
+            //     V = not surrogates_wordmask
+            const uint64_t V = ~surrogates_wordmask;
+
+            // H - word-mask for high surrogates: the six highest bits are 0b1101'11
+            const auto vH = ((in & v_fc) ==  v_dc);
+            const uint64_t H = vH.to_bitmask64();
+
+            // L - word mask for low surrogates
+            //     L = not H and surrogates_wordmask
+            const uint64_t L = ~H & surrogates_wordmask;
+
+            const uint64_t a = L & (H >> 4); // A low surrogate must be followed by high one.
+                              // (A low surrogate placed in the 7th register's word
+                              // is an exception we handle.)
+            const uint64_t b = a << 4; // Just mark that the opposite fact is hold,
+                          // thanks to that we have only two masks for valid case.
+            const uint64_t c = V | a | b;      // Combine all the masks into the final one.
+            if (c == ~0ull) {
+                // The whole input register contains valid UTF-16, i.e.,
+                // either single words or proper surrogate pairs.
+                input += 16;
+            } else if (c == 0xfffffffffffffffull) {
+                // The 15 lower words of the input register contains valid UTF-16.
+                // The 15th word may be either a low or high surrogate. It the next
+                // iteration we 1) check if the low surrogate is followed by a high
+                // one, 2) reject sole high surrogate.
+                input += 15;
+            } else {
+                return nullptr;
+            }
+        }
+    }
+    return input;
+}
+
+
+template <endianness big_endian>
+const result arm_validate_utf16_with_errors(const char16_t* input, size_t size) {
+    const char16_t* start = input;
+    const char16_t* end = input + size;
+
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+    const auto v_fc = simd8<uint8_t>::splat(0xfc);
+    const auto v_dc = simd8<uint8_t>::splat(0xdc);
+    while (input + 16 < end) {
+        // 0. Load data: since the validation takes into account only higher
+        //    byte of each word, we compress the two vectors into one which
+        //    consists only the higher bytes.
+        auto in0 = simd16<uint16_t>(input);
+        auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::SIZE / sizeof(char16_t));
+
+        if (big_endian) {
+            #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+            const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+            #else
+            const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+            #endif
+            in0 = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in0), swap));
+            in1 = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in1), swap));
+        }
+        const auto t0 = in0.shr<8>();
+        const auto t1 = in1.shr<8>();
+        const simd8<uint8_t> in = simd16<uint16_t>::pack(t0, t1);
+        // 1. Check whether we have any 0xD800..DFFF word (0b1101'1xxx'yyyy'yyyy).
+        const uint64_t surrogates_wordmask = ((in & v_f8) == v_d8).to_bitmask64();
+        if(surrogates_wordmask == 0) {
+            input += 16;
+        } else {
+            // 2. We have some surrogates that have to be distinguished:
+            //    - low  surrogates: 0b1101'10xx'yyyy'yyyy (0xD800..0xDBFF)
+            //    - high surrogates: 0b1101'11xx'yyyy'yyyy (0xDC00..0xDFFF)
+            //
+            //    Fact: high surrogate has 11th bit set (3rd bit in the higher word)
+
+            // V - non-surrogate words
+            //     V = not surrogates_wordmask
+            const uint64_t V = ~surrogates_wordmask;
+
+            // H - word-mask for high surrogates: the six highest bits are 0b1101'11
+            const auto vH = ((in & v_fc) ==  v_dc);
+            const uint64_t H = vH.to_bitmask64();
+
+            // L - word mask for low surrogates
+            //     L = not H and surrogates_wordmask
+            const uint64_t L = ~H & surrogates_wordmask;
+
+            const uint64_t a = L & (H >> 4); // A low surrogate must be followed by high one.
+                              // (A low surrogate placed in the 7th register's word
+                              // is an exception we handle.)
+            const uint64_t b = a << 4; // Just mark that the opposite fact is hold,
+                          // thanks to that we have only two masks for valid case.
+            const uint64_t c = V | a | b;      // Combine all the masks into the final one.
+            if (c == ~0ull) {
+                // The whole input register contains valid UTF-16, i.e.,
+                // either single words or proper surrogate pairs.
+                input += 16;
+            } else if (c == 0xfffffffffffffffull) {
+                // The 15 lower words of the input register contains valid UTF-16.
+                // The 15th word may be either a low or high surrogate. It the next
+                // iteration we 1) check if the low surrogate is followed by a high
+                // one, 2) reject sole high surrogate.
+                input += 15;
+            } else {
+                return result(error_code::SURROGATE, input - start);
+            }
+        }
+    }
+    return result(error_code::SUCCESS, input - start);
+}
+/* end file src/arm64/arm_validate_utf16.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_validate_utf32le.cpp
+/* begin file src/arm64/arm_validate_utf32le.cpp */
+
+const char32_t* arm_validate_utf32le(const char32_t* input, size_t size) {
+    const char32_t* end = input + size;
+
+    const uint32x4_t standardmax = vmovq_n_u32(0x10ffff);
+    const uint32x4_t offset = vmovq_n_u32(0xffff2000);
+    const uint32x4_t standardoffsetmax = vmovq_n_u32(0xfffff7ff);
+    uint32x4_t currentmax = vmovq_n_u32(0x0);
+    uint32x4_t currentoffsetmax = vmovq_n_u32(0x0);
+
+    while (input + 4 < end) {
+        const uint32x4_t in = vld1q_u32(reinterpret_cast<const uint32_t*>(input));
+        currentmax = vmaxq_u32(in,currentmax);
+        currentoffsetmax = vmaxq_u32(vaddq_u32(in, offset), currentoffsetmax);
+        input += 4;
+    }
+
+    uint32x4_t is_zero = veorq_u32(vmaxq_u32(currentmax, standardmax), standardmax);
+    if(vmaxvq_u32(is_zero) != 0) {
+        return nullptr;
+    }
+
+    is_zero = veorq_u32(vmaxq_u32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+    if(vmaxvq_u32(is_zero) != 0) {
+        return nullptr;
+    }
+
+    return input;
+}
+
+
+const result arm_validate_utf32le_with_errors(const char32_t* input, size_t size) {
+    const char32_t* start = input;
+    const char32_t* end = input + size;
+
+    const uint32x4_t standardmax = vmovq_n_u32(0x10ffff);
+    const uint32x4_t offset = vmovq_n_u32(0xffff2000);
+    const uint32x4_t standardoffsetmax = vmovq_n_u32(0xfffff7ff);
+    uint32x4_t currentmax = vmovq_n_u32(0x0);
+    uint32x4_t currentoffsetmax = vmovq_n_u32(0x0);
+
+    while (input + 4 < end) {
+        const uint32x4_t in = vld1q_u32(reinterpret_cast<const uint32_t*>(input));
+        currentmax = vmaxq_u32(in,currentmax);
+        currentoffsetmax = vmaxq_u32(vaddq_u32(in, offset), currentoffsetmax);
+
+        uint32x4_t is_zero = veorq_u32(vmaxq_u32(currentmax, standardmax), standardmax);
+        if(vmaxvq_u32(is_zero) != 0) {
+            return result(error_code::TOO_LARGE, input - start);
+        }
+
+        is_zero = veorq_u32(vmaxq_u32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+        if(vmaxvq_u32(is_zero) != 0) {
+            return result(error_code::SURROGATE, input - start);
+        }
+
+        input += 4;
+    }
+
+    return result(error_code::SUCCESS, input - start);
+}
+/* end file src/arm64/arm_validate_utf32le.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_convert_utf8_to_utf16.cpp
+/* begin file src/arm64/arm_convert_utf8_to_utf16.cpp */
+// Convert up to 12 bytes from utf8 to utf16 using a mask indicating the
+// end of the code points. Only the least significant 12 bits of the mask
+// are accessed.
+// It returns how many bytes were consumed (up to 12).
+template <endianness big_endian>
+size_t convert_masked_utf8_to_utf16(const char *input,
+                           uint64_t utf8_end_of_code_point_mask,
+                           char16_t *&utf16_output) {
+  // we use an approach where we try to process up to 12 input bytes.
+  // Why 12 input bytes and not 16? Because we are concerned with the size of
+  // the lookup tables. Also 12 is nicely divisible by two and three.
+  //
+  #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+  const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+  #else
+  const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+  #endif
+  uint8x16_t in = vld1q_u8(reinterpret_cast<const uint8_t*>(input));
+  const uint16_t input_utf8_end_of_code_point_mask =
+      utf8_end_of_code_point_mask & 0xfff;
+  //
+  // Optimization note: our main path below is load-latency dependent. Thus it is maybe
+  // beneficial to have fast paths that depend on branch prediction but have less latency.
+  // This results in more instructions but, potentially, also higher speeds.
+  //
+  // We first try a few fast paths.
+  if((utf8_end_of_code_point_mask & 0xffff) == 0xffff) {
+    // We process in chunks of 16 bytes
+    uint16x8_t ascii_first = vmovl_u8(vget_low_u8 (in));
+    uint16x8_t ascii_second = vmovl_high_u8(in);
+    if (big_endian) {
+      ascii_first = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(ascii_first), swap));
+      ascii_second = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(ascii_second), swap));
+    }
+    vst1q_u16(reinterpret_cast<uint16_t*>(utf16_output), ascii_first);
+    vst1q_u16(reinterpret_cast<uint16_t*>(utf16_output) + 8, ascii_second);
+    utf16_output += 16; // We wrote 16 16-bit characters.
+    return 16; // We consumed 16 bytes.
+  }
+  if((utf8_end_of_code_point_mask & 0xffff) == 0xaaaa) {
+    // We want to take 8 2-byte UTF-8 words and turn them into 8 2-byte UTF-16 words.
+    // There is probably a more efficient sequence, but the following might do.
+    uint8x16_t perm = vqtbl1q_u8(in, swap);
+    uint8x16_t ascii = vandq_u8(perm, vreinterpretq_u8_u16(vmovq_n_u16(0x7f)));
+    uint8x16_t highbyte = vandq_u8(perm, vreinterpretq_u8_u16(vmovq_n_u16(0x1f00)));
+    uint8x16_t composed = vorrq_u8(ascii, vreinterpretq_u8_u16(vshrq_n_u16(vreinterpretq_u16_u8(highbyte), 2)));
+    if (big_endian) composed = vqtbl1q_u8(composed, swap);
+    vst1q_u8(reinterpret_cast<uint8_t*>(utf16_output), composed);
+    utf16_output += 8; // We wrote 16 bytes, 8 code points.
+    return 16;
+  }
+  if(input_utf8_end_of_code_point_mask == 0x924) {
+    // We want to take 4 3-byte UTF-8 words and turn them into 4 2-byte UTF-16 words.
+    // There is probably a more efficient sequence, but the following might do.
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+    const uint8x16_t sh = make_uint8x16_t(2, 1, 0, 255, 5, 4, 3, 255, 8, 7, 6, 255, 11, 10, 9, 255);
+#else
+    const uint8x16_t sh = {2, 1, 0, 255, 5, 4, 3, 255, 8, 7, 6, 255, 11, 10, 9, 255};
+#endif
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii =
+        vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x7f))); // 7 or 6 bits
+    uint8x16_t middlebyte =
+        vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x3f00))); // 5 or 6 bits
+    uint8x16_t middlebyte_shifted = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(middlebyte), 2));
+    uint32x4_t highbyte =
+        vreinterpretq_u32_u8(vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x0f0000)))); // 4 bits
+    uint32x4_t highbyte_shifted = vshrq_n_u32(highbyte, 4);
+    uint32x4_t composed =
+        vorrq_u32(vorrq_u32(vreinterpretq_u32_u8(ascii), vreinterpretq_u32_u8(middlebyte_shifted)), highbyte_shifted);
+    uint16x8_t composed_repacked = vmovn_high_u32(vmovn_u32(composed), composed);
+    if (big_endian) composed_repacked = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(composed_repacked), swap));
+    vst1q_u16(reinterpret_cast<uint16_t*>(utf16_output), composed_repacked);
+    utf16_output += 4;
+    return 12;
+  }
+  /// We do not have a fast path available, so we fallback.
+
+  const uint8_t idx =
+      simdutf::tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][0];
+  const uint8_t consumed =
+      simdutf::tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][1];
+
+
+  if (idx < 64) {
+    // SIX (6) input code-words
+    // this is a relatively easy scenario
+    // we process SIX (6) input code-words. The max length in bytes of six code
+    // words spanning between 1 and 2 bytes each is 12 bytes.
+    uint8x16_t sh = vld1q_u8(reinterpret_cast<const uint8_t*>(simdutf::tables::utf8_to_utf16::shufutf8[idx]));
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii = vandq_u8(perm, vreinterpretq_u8_u16(vmovq_n_u16(0x7f)));
+    uint8x16_t highbyte = vandq_u8(perm, vreinterpretq_u8_u16(vmovq_n_u16(0x1f00)));
+    uint8x16_t composed = vorrq_u8(ascii, vreinterpretq_u8_u16(vshrq_n_u16(vreinterpretq_u16_u8(highbyte), 2)));
+    if (big_endian) composed = vqtbl1q_u8(composed, swap);
+    vst1q_u8(reinterpret_cast<uint8_t*>(utf16_output), composed);
+    utf16_output += 6; // We wrote 12 bytes, 6 code points.
+  } else if (idx < 145) {
+    // FOUR (4) input code-words
+    uint8x16_t sh = vld1q_u8(reinterpret_cast<const uint8_t*>(simdutf::tables::utf8_to_utf16::shufutf8[idx]));
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii =
+        vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x7f))); // 7 or 6 bits
+    uint8x16_t middlebyte =
+        vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x3f00))); // 5 or 6 bits
+    uint8x16_t middlebyte_shifted = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(middlebyte), 2));
+    uint32x4_t highbyte =
+        vreinterpretq_u32_u8(vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x0f0000)))); // 4 bits
+    uint32x4_t highbyte_shifted = vshrq_n_u32(highbyte, 4);
+    uint32x4_t composed =
+        vorrq_u32(vorrq_u32(vreinterpretq_u32_u8(ascii), vreinterpretq_u32_u8(middlebyte_shifted)), highbyte_shifted);
+    uint16x8_t composed_repacked = vmovn_high_u32(vmovn_u32(composed), composed);
+    if (big_endian) composed_repacked = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(composed_repacked), swap));
+    vst1q_u16(reinterpret_cast<uint16_t*>(utf16_output), composed_repacked);
+    utf16_output += 4;
+  } else if (idx < 209) {
+    // TWO (2) input code-words
+    uint8x16_t sh = vld1q_u8(reinterpret_cast<const uint8_t*>(simdutf::tables::utf8_to_utf16::shufutf8[idx]));
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii = vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x7f)));
+    uint8x16_t middlebyte = vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x3f00)));
+    uint8x16_t middlebyte_shifted = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(middlebyte), 2));
+    uint8x16_t middlehighbyte = vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x3f0000)));
+    // correct for spurious high bit
+    uint8x16_t correct =
+        vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x400000)))), 1));
+    middlehighbyte = veorq_u8(correct, middlehighbyte);
+    uint8x16_t middlehighbyte_shifted = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(middlehighbyte), 4));
+    uint8x16_t highbyte = vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x07000000)));
+    uint8x16_t highbyte_shifted =vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(highbyte), 6));
+    uint8x16_t composed =
+        vorrq_u8(vorrq_u8(ascii, middlebyte_shifted),
+                     vorrq_u8(highbyte_shifted, middlehighbyte_shifted));
+    uint32x4_t composedminus =
+        vsubq_u32(vreinterpretq_u32_u8(composed), vmovq_n_u32(0x10000));
+    uint32x4_t lowtenbits =
+        vandq_u32(composedminus, vmovq_n_u32(0x3ff));
+    uint32x4_t hightenbits = vshrq_n_u32(composedminus, 10);
+    uint32x4_t lowtenbitsadd =
+        vaddq_u32(lowtenbits, vmovq_n_u32(0xDC00));
+    uint32x4_t hightenbitsadd =
+        vaddq_u32(hightenbits, vmovq_n_u32(0xD800));
+    uint32x4_t lowtenbitsaddshifted = vshlq_n_u32(lowtenbitsadd, 16);
+    uint32x4_t surrogates =
+        vorrq_u32(hightenbitsadd, lowtenbitsaddshifted);
+    uint32_t basic_buffer[4];
+    uint32_t basic_buffer_swap[4];
+    if (big_endian) {
+      vst1q_u32(basic_buffer_swap, vreinterpretq_u32_u8(vqtbl1q_u8(composed, swap)));
+      surrogates = vreinterpretq_u32_u8(vqtbl1q_u8(vreinterpretq_u8_u32(surrogates), swap));
+    }
+    vst1q_u32(basic_buffer, vreinterpretq_u32_u8(composed));
+    uint32_t surrogate_buffer[4];
+    vst1q_u32(surrogate_buffer, surrogates);
+    for (size_t i = 0; i < 3; i++) {
+      if (basic_buffer[i] < 65536) {
+        utf16_output[0] = big_endian ? uint16_t(basic_buffer_swap[i]) : uint16_t(basic_buffer[i]);
+        utf16_output++;
+      } else {
+        utf16_output[0] = uint16_t(surrogate_buffer[i] & 0xffff);
+        utf16_output[1] = uint16_t(surrogate_buffer[i] >> 16);
+        utf16_output += 2;
+      }
+    }
+  } else {
+    // here we know that there is an error but we do not handle errors
+  }
+  return consumed;
+}
+/* end file src/arm64/arm_convert_utf8_to_utf16.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_convert_utf8_to_utf32.cpp
+/* begin file src/arm64/arm_convert_utf8_to_utf32.cpp */
+// Convert up to 12 bytes from utf8 to utf32 using a mask indicating the
+// end of the code points. Only the least significant 12 bits of the mask
+// are accessed.
+// It returns how many bytes were consumed (up to 12).
+size_t convert_masked_utf8_to_utf32(const char *input,
+                           uint64_t utf8_end_of_code_point_mask,
+                           char32_t *&utf32_out) {
+  // we use an approach where we try to process up to 12 input bytes.
+  // Why 12 input bytes and not 16? Because we are concerned with the size of
+  // the lookup tables. Also 12 is nicely divisible by two and three.
+  //
+  uint32_t*& utf32_output = reinterpret_cast<uint32_t*&>(utf32_out);
+  uint8x16_t in = vld1q_u8(reinterpret_cast<const uint8_t*>(input));
+  const uint16_t input_utf8_end_of_code_point_mask =
+      utf8_end_of_code_point_mask & 0xFFF;
+  //
+  // Optimization note: our main path below is load-latency dependent. Thus it is maybe
+  // beneficial to have fast paths that depend on branch prediction but have less latency.
+  // This results in more instructions but, potentially, also higher speeds.
+  //
+  // We first try a few fast paths.
+  if((utf8_end_of_code_point_mask & 0xffff) == 0xffff) {
+    // We process in chunks of 16 bytes
+    vst1q_u32(utf32_output, vmovl_u16(vget_low_u16(vmovl_u8(vget_low_u8 (in)))));
+    vst1q_u32(utf32_output + 4, vmovl_high_u16(vmovl_u8(vget_low_u8 (in))));
+    vst1q_u32(utf32_output + 8, vmovl_u16(vget_low_u16(vmovl_high_u8(in))));
+    vst1q_u32(utf32_output + 12, vmovl_high_u16(vmovl_high_u8(in)));
+    utf32_output += 16; // We wrote 16 16-bit characters.
+    return 16; // We consumed 16 bytes.
+  }
+  if((utf8_end_of_code_point_mask & 0xffff) == 0xaaaa) {
+    // We want to take 8 2-byte UTF-8 words and turn them into 8 4-byte UTF-32 words.
+    // There is probably a more efficient sequence, but the following might do.
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+    const uint8x16_t sh = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+#else
+    //const uint8x16_t sh = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+    const uint8x16_t sh = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+#endif
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii = vandq_u8(perm, vreinterpretq_u8_u16(vmovq_n_u16(0x7f)));
+    uint8x16_t highbyte = vandq_u8(perm, vreinterpretq_u8_u16(vmovq_n_u16(0x1f00)));
+    uint8x16_t composed = vorrq_u8(ascii, vreinterpretq_u8_u16(vshrq_n_u16(vreinterpretq_u16_u8(highbyte), 2)));
+    vst1q_u32(utf32_output,  vmovl_u16(vget_low_u16(vreinterpretq_u16_u8(composed))));
+    vst1q_u32(utf32_output+4,  vmovl_high_u16(vreinterpretq_u16_u8(composed)));
+    utf32_output += 8; // We wrote 32 bytes, 8 code points.
+    return 16;
+  }
+  if(input_utf8_end_of_code_point_mask == 0x924) {
+    // We want to take 4 3-byte UTF-8 words and turn them into 4 4-byte UTF-32 words.
+    // There is probably a more efficient sequence, but the following might do.
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+    const uint8x16_t sh = make_uint8x16_t(2, 1, 0, 255, 5, 4, 3, 255, 8, 7, 6, 255, 11, 10, 9, 255);
+#else
+    const uint8x16_t sh = {2, 1, 0, 255, 5, 4, 3, 255, 8, 7, 6, 255, 11, 10, 9, 255};
+#endif
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii =
+        vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x7f))); // 7 or 6 bits
+    uint8x16_t middlebyte =
+        vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x3f00))); // 5 or 6 bits
+    uint8x16_t middlebyte_shifted = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(middlebyte), 2));
+    uint32x4_t highbyte =
+        vreinterpretq_u32_u8(vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x0f0000)))); // 4 bits
+    uint32x4_t highbyte_shifted = vshrq_n_u32(highbyte, 4);
+    uint32x4_t composed =
+        vorrq_u32(vorrq_u32(vreinterpretq_u32_u8(ascii), vreinterpretq_u32_u8(middlebyte_shifted)), highbyte_shifted);
+    vst1q_u32(utf32_output, composed);
+    utf32_output += 4;
+    return 12;
+  }
+  /// We do not have a fast path available, so we fallback.
+
+  const uint8_t idx =
+      simdutf::tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][0];
+  const uint8_t consumed =
+      simdutf::tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][1];
+
+
+  if (idx < 64) {
+    // SIX (6) input code-words
+    // this is a relatively easy scenario
+    // we process SIX (6) input code-words. The max length in bytes of six code
+    // words spanning between 1 and 2 bytes each is 12 bytes.
+    uint8x16_t sh = vld1q_u8(reinterpret_cast<const uint8_t*>(simdutf::tables::utf8_to_utf16::shufutf8[idx]));
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii = vandq_u8(perm, vreinterpretq_u8_u16(vmovq_n_u16(0x7f)));
+    uint8x16_t highbyte = vandq_u8(perm, vreinterpretq_u8_u16(vmovq_n_u16(0x1f00)));
+    uint8x16_t composed = vorrq_u8(ascii, vreinterpretq_u8_u16(vshrq_n_u16(vreinterpretq_u16_u8(highbyte), 2)));
+    vst1q_u32(utf32_output,  vmovl_u16(vget_low_u16(vreinterpretq_u16_u8(composed))));
+    vst1q_u32(utf32_output+4,  vmovl_high_u16(vreinterpretq_u16_u8(composed)));
+    utf32_output += 6; // We wrote 12 bytes, 6 code points.
+  } else if (idx < 145) {
+    // FOUR (4) input code-words
+    uint8x16_t sh = vld1q_u8(reinterpret_cast<const uint8_t*>(simdutf::tables::utf8_to_utf16::shufutf8[idx]));
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii =
+        vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x7f))); // 7 or 6 bits
+    uint8x16_t middlebyte =
+        vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x3f00))); // 5 or 6 bits
+    uint8x16_t middlebyte_shifted = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(middlebyte), 2));
+    uint32x4_t highbyte =
+        vreinterpretq_u32_u8(vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x0f0000)))); // 4 bits
+    uint32x4_t highbyte_shifted = vshrq_n_u32(highbyte, 4);
+    uint32x4_t composed =
+        vorrq_u32(vorrq_u32(vreinterpretq_u32_u8(ascii), vreinterpretq_u32_u8(middlebyte_shifted)), highbyte_shifted);
+    vst1q_u32(utf32_output, composed);
+    utf32_output += 4;
+  } else if (idx < 209) {
+    // TWO (2) input code-words
+    uint8x16_t sh = vld1q_u8(reinterpret_cast<const uint8_t*>(simdutf::tables::utf8_to_utf16::shufutf8[idx]));
+    uint8x16_t perm = vqtbl1q_u8(in, sh);
+    uint8x16_t ascii = vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x7f)));
+    uint8x16_t middlebyte = vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x3f00)));
+    uint8x16_t middlebyte_shifted = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(middlebyte), 2));
+    uint8x16_t middlehighbyte = vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x3f0000)));
+    // correct for spurious high bit
+    uint8x16_t correct =
+        vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x400000)))), 1));
+    middlehighbyte = veorq_u8(correct, middlehighbyte);
+    uint8x16_t middlehighbyte_shifted = vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(middlehighbyte), 4));
+    uint8x16_t highbyte = vandq_u8(perm, vreinterpretq_u8_u32(vmovq_n_u32(0x07000000)));
+    uint8x16_t highbyte_shifted =vreinterpretq_u8_u32(vshrq_n_u32(vreinterpretq_u32_u8(highbyte), 6));
+    uint8x16_t composed =
+        vorrq_u8(vorrq_u8(ascii, middlebyte_shifted),
+                     vorrq_u8(highbyte_shifted, middlehighbyte_shifted));
+    vst1q_u32(utf32_output, vreinterpretq_u32_u8(composed));
+    utf32_output += 3;
+  } else {
+    // here we know that there is an error but we do not handle errors
+  }
+  return consumed;
+}
+/* end file src/arm64/arm_convert_utf8_to_utf32.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_convert_utf16_to_utf8.cpp
+/* begin file src/arm64/arm_convert_utf16_to_utf8.cpp */
+/*
+    The vectorized algorithm works on single SSE register i.e., it
+    loads eight 16-bit words.
+
+    We consider three cases:
+    1. an input register contains no surrogates and each value
+       is in range 0x0000 .. 0x07ff.
+    2. an input register contains no surrogates and values are
+       is in range 0x0000 .. 0xffff.
+    3. an input register contains surrogates --- i.e. codepoints
+       can have 16 or 32 bits.
+
+    Ad 1.
+
+    When values are less than 0x0800, it means that a 16-bit words
+    can be converted into: 1) single UTF8 byte (when it's an ASCII
+    char) or 2) two UTF8 bytes.
+
+    For this case we do only some shuffle to obtain these 2-byte
+    codes and finally compress the whole SSE register with a single
+    shuffle.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+    Ad 2.
+
+    When values fit in 16-bit words, but are above 0x07ff, then
+    a single word may produce one, two or three UTF8 bytes.
+
+    We prepare data for all these three cases in two registers.
+    The first register contains lower two UTF8 bytes (used in all
+    cases), while the second one contains just the third byte for
+    the three-UTF8-bytes case.
+
+    Finally these two registers are interleaved forming eight-element
+    array of 32-bit values. The array spans two SSE registers.
+    The bytes from the registers are compressed using two shuffles.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+
+    To summarize:
+    - We need two 256-entry tables that have 8704 bytes in total.
+*/
+/*
+  Returns a pair: the first unprocessed byte from buf and utf8_output
+  A scalar routing should carry on the conversion of the tail.
+*/
+template <endianness big_endian>
+std::pair<const char16_t*, char*> arm_convert_utf16_to_utf8(const char16_t* buf, size_t len, char* utf8_out) {
+  uint8_t * utf8_output = reinterpret_cast<uint8_t*>(utf8_out);
+  const char16_t* end = buf + len;
+
+  const uint16x8_t v_f800 = vmovq_n_u16((uint16_t)0xf800);
+  const uint16x8_t v_d800 = vmovq_n_u16((uint16_t)0xd800);
+  const uint16x8_t v_c080 = vmovq_n_u16((uint16_t)0xc080);
+
+  while (buf + 16 <= end) {
+    uint16x8_t in = vld1q_u16(reinterpret_cast<const uint16_t *>(buf));
+    if (big_endian) {
+      #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+      const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+      #else
+      const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+      #endif
+      in = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in), swap));
+    }
+    if(vmaxvq_u16(in) <= 0x7F) { // ASCII fast path!!!!
+        // It is common enough that we have sequences of 16 consecutive ASCII characters.
+        uint16x8_t nextin = vld1q_u16(reinterpret_cast<const uint16_t *>(buf) + 8);
+        if (big_endian) {
+          #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+          const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+          #else
+          const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+          #endif
+          nextin = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(nextin), swap));
+        }
+        if(vmaxvq_u16(nextin) > 0x7F) {
+          // 1. pack the bytes
+          // obviously suboptimal.
+          uint8x8_t utf8_packed = vmovn_u16(in);
+          // 2. store (8 bytes)
+          vst1_u8(utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 8;
+          utf8_output += 8;
+          in = nextin;
+        } else {
+          // 1. pack the bytes
+          // obviously suboptimal.
+          uint8x16_t utf8_packed = vmovn_high_u16(vmovn_u16(in), nextin);
+          // 2. store (16 bytes)
+          vst1q_u8(utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 16;
+          utf8_output += 16;
+          continue; // we are done for this round!
+        }
+    }
+
+    if (vmaxvq_u16(in) <= 0x7FF) {
+          // 1. prepare 2-byte values
+          // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+          // expected output   : [110a|aaaa|10bb|bbbb] x 8
+          const uint16x8_t v_1f00 = vmovq_n_u16((int16_t)0x1f00);
+          const uint16x8_t v_003f = vmovq_n_u16((int16_t)0x003f);
+
+          // t0 = [000a|aaaa|bbbb|bb00]
+          const uint16x8_t t0 = vshlq_n_u16(in, 2);
+          // t1 = [000a|aaaa|0000|0000]
+          const uint16x8_t t1 = vandq_u16(t0, v_1f00);
+          // t2 = [0000|0000|00bb|bbbb]
+          const uint16x8_t t2 = vandq_u16(in, v_003f);
+          // t3 = [000a|aaaa|00bb|bbbb]
+          const uint16x8_t t3 = vorrq_u16(t1, t2);
+          // t4 = [110a|aaaa|10bb|bbbb]
+          const uint16x8_t t4 = vorrq_u16(t3, v_c080);
+          // 2. merge ASCII and 2-byte codewords
+          const uint16x8_t v_007f = vmovq_n_u16((uint16_t)0x007F);
+          const uint16x8_t one_byte_bytemask = vcleq_u16(in, v_007f);
+          const uint8x16_t utf8_unpacked = vreinterpretq_u8_u16(vbslq_u16(one_byte_bytemask, in, t4));
+          // 3. prepare bitmask for 8-bit lookup
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+          const uint16x8_t mask = make_uint16x8_t(0x0001, 0x0004,
+                                    0x0010, 0x0040,
+                                    0x0002, 0x0008,
+                                    0x0020, 0x0080);
+#else
+          const uint16x8_t mask = { 0x0001, 0x0004,
+                                    0x0010, 0x0040,
+                                    0x0002, 0x0008,
+                                    0x0020, 0x0080 };
+#endif
+          uint16_t m2 = vaddvq_u16(vandq_u16(one_byte_bytemask, mask));
+          // 4. pack the bytes
+          const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[m2][0];
+          const uint8x16_t shuffle = vld1q_u8(row + 1);
+          const uint8x16_t utf8_packed = vqtbl1q_u8(utf8_unpacked, shuffle);
+
+          // 5. store bytes
+          vst1q_u8(utf8_output, utf8_packed);
+
+          // 6. adjust pointers
+          buf += 8;
+          utf8_output += row[0];
+          continue;
+
+    }
+    const uint16x8_t surrogates_bytemask = vceqq_u16(vandq_u16(in, v_f800), v_d800);
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+      if (vmaxvq_u16(surrogates_bytemask) == 0) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+        const uint16x8_t dup_even = make_uint16x8_t(0x0000, 0x0202, 0x0404, 0x0606,
+                                     0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+#else
+        const uint16x8_t dup_even = {0x0000, 0x0202, 0x0404, 0x0606,
+                                     0x0808, 0x0a0a, 0x0c0c, 0x0e0e};
+#endif
+        /* In this branch we handle three cases:
+           1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+           2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+           3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+          We expand the input word (16-bit) into two words (32-bit), thus
+          we have room for four bytes. However, we need five distinct bit
+          layouts. Note that the last byte in cases #2 and #3 is the same.
+
+          We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+          in register t2.
+
+          We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+          either byte 1 for case #2 or byte 2 for case #3. Note that they
+          differ by exactly one bit.
+
+          Finally from these two words we build proper UTF-8 sequence, taking
+          into account the case (i.e, the number of bytes to write).
+        */
+        /**
+         * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+         * t2 => [0ccc|cccc] [10cc|cccc]
+         * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+         */
+#define vec(x) vmovq_n_u16(static_cast<uint16_t>(x))
+        // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+        const uint16x8_t t0 = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in), vreinterpretq_u8_u16(dup_even)));
+        // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+        const uint16x8_t t1 = vandq_u16(t0, vec(0b0011111101111111));
+        // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+        const uint16x8_t t2 = vorrq_u16 (t1, vec(0b1000000000000000));
+
+        // s0: [aaaa|bbbb|bbcc|cccc] => [0000|0000|0000|aaaa]
+        const uint16x8_t s0 = vshrq_n_u16(in, 12);
+        // s1: [aaaa|bbbb|bbcc|cccc] => [0000|bbbb|bb00|0000]
+        const uint16x8_t s1 = vandq_u16(in, vec(0b0000111111000000));
+        // [0000|bbbb|bb00|0000] => [00bb|bbbb|0000|0000]
+        const uint16x8_t s1s = vshlq_n_u16(s1, 2);
+        // [00bb|bbbb|0000|aaaa]
+        const uint16x8_t s2 = vorrq_u16(s0, s1s);
+        // s3: [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+        const uint16x8_t s3 = vorrq_u16(s2, vec(0b1100000011100000));
+        const uint16x8_t v_07ff = vmovq_n_u16((uint16_t)0x07FF);
+        const uint16x8_t one_or_two_bytes_bytemask = vcleq_u16(in, v_07ff);
+        const uint16x8_t m0 = vbicq_u16(vec(0b0100000000000000), one_or_two_bytes_bytemask);
+        const uint16x8_t s4 = veorq_u16(s3, m0);
+#undef vec
+
+        // 4. expand words 16-bit => 32-bit
+        const uint8x16_t out0 = vreinterpretq_u8_u16(vzip1q_u16(t2, s4));
+        const uint8x16_t out1 = vreinterpretq_u8_u16(vzip2q_u16(t2, s4));
+
+        // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+        const uint16x8_t v_007f = vmovq_n_u16((uint16_t)0x007F);
+        const uint16x8_t one_byte_bytemask = vcleq_u16(in, v_007f);
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+        const uint16x8_t onemask = make_uint16x8_t(0x0001, 0x0004,
+                                    0x0010, 0x0040,
+                                    0x0100, 0x0400,
+                                    0x1000, 0x4000 );
+        const uint16x8_t twomask = make_uint16x8_t(0x0002, 0x0008,
+                                    0x0020, 0x0080,
+                                    0x0200, 0x0800,
+                                    0x2000, 0x8000 );
+#else
+        const uint16x8_t onemask = { 0x0001, 0x0004,
+                                    0x0010, 0x0040,
+                                    0x0100, 0x0400,
+                                    0x1000, 0x4000 };
+        const uint16x8_t twomask = { 0x0002, 0x0008,
+                                    0x0020, 0x0080,
+                                    0x0200, 0x0800,
+                                    0x2000, 0x8000 };
+#endif
+        const uint16x8_t combined = vorrq_u16(vandq_u16(one_byte_bytemask, onemask), vandq_u16(one_or_two_bytes_bytemask, twomask));
+        const uint16_t mask = vaddvq_u16(combined);
+        // The following fast path may or may not be beneficial.
+        /*if(mask == 0) {
+          // We only have three-byte words. Use fast path.
+          const uint8x16_t shuffle = {2,3,1,6,7,5,10,11,9,14,15,13,0,0,0,0};
+          const uint8x16_t utf8_0 = vqtbl1q_u8(out0, shuffle);
+          const uint8x16_t utf8_1 = vqtbl1q_u8(out1, shuffle);
+          vst1q_u8(utf8_output, utf8_0);
+          utf8_output += 12;
+          vst1q_u8(utf8_output, utf8_1);
+          utf8_output += 12;
+          buf += 8;
+          continue;
+        }*/
+        const uint8_t mask0 = uint8_t(mask);
+
+        const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+        const uint8x16_t shuffle0 = vld1q_u8(row0 + 1);
+        const uint8x16_t utf8_0 = vqtbl1q_u8(out0, shuffle0);
+
+        const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+        const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+        const uint8x16_t shuffle1 = vld1q_u8(row1 + 1);
+        const uint8x16_t utf8_1 = vqtbl1q_u8(out1, shuffle1);
+
+        vst1q_u8(utf8_output, utf8_0);
+        utf8_output += row0[0];
+        vst1q_u8(utf8_output, utf8_1);
+        utf8_output += row1[0];
+
+        buf += 8;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word & 0xFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word &0xF800 ) != 0xD800) {
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k + 1]) : buf[k + 1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(nullptr, reinterpret_cast<char*>(utf8_output)); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf8_output++ = char((value>>18) | 0b11110000);
+          *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((value & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  return std::make_pair(buf, reinterpret_cast<char*>(utf8_output));
+}
+
+
+/*
+  Returns a pair: a result struct and utf8_output.
+  If there is an error, the count field of the result is the position of the error.
+  Otherwise, it is the position of the first unprocessed byte in buf (even if finished).
+  A scalar routing should carry on the conversion of the tail if needed.
+*/
+template <endianness big_endian>
+std::pair<result, char*> arm_convert_utf16_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_out) {
+  uint8_t * utf8_output = reinterpret_cast<uint8_t*>(utf8_out);
+    const char16_t* start = buf;
+  const char16_t* end = buf + len;
+
+  const uint16x8_t v_f800 = vmovq_n_u16((uint16_t)0xf800);
+  const uint16x8_t v_d800 = vmovq_n_u16((uint16_t)0xd800);
+  const uint16x8_t v_c080 = vmovq_n_u16((uint16_t)0xc080);
+
+  while (buf + 16 <= end) {
+    uint16x8_t in = vld1q_u16(reinterpret_cast<const uint16_t *>(buf));
+    if (big_endian) {
+      #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+      const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+      #else
+      const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+      #endif
+      in = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in), swap));
+    }
+    if(vmaxvq_u16(in) <= 0x7F) { // ASCII fast path!!!!
+        // It is common enough that we have sequences of 16 consecutive ASCII characters.
+        uint16x8_t nextin = vld1q_u16(reinterpret_cast<const uint16_t *>(buf) + 8);
+        if (big_endian) {
+          #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+          const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+          #else
+          const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+          #endif
+          nextin = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(nextin), swap));
+        }
+        if(vmaxvq_u16(nextin) > 0x7F) {
+          // 1. pack the bytes
+          // obviously suboptimal.
+          uint8x8_t utf8_packed = vmovn_u16(in);
+          // 2. store (8 bytes)
+          vst1_u8(utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 8;
+          utf8_output += 8;
+          in = nextin;
+        } else {
+          // 1. pack the bytes
+          // obviously suboptimal.
+          uint8x16_t utf8_packed = vmovn_high_u16(vmovn_u16(in), nextin);
+          // 2. store (16 bytes)
+          vst1q_u8(utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 16;
+          utf8_output += 16;
+          continue; // we are done for this round!
+        }
+    }
+
+    if (vmaxvq_u16(in) <= 0x7FF) {
+          // 1. prepare 2-byte values
+          // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+          // expected output   : [110a|aaaa|10bb|bbbb] x 8
+          const uint16x8_t v_1f00 = vmovq_n_u16((int16_t)0x1f00);
+          const uint16x8_t v_003f = vmovq_n_u16((int16_t)0x003f);
+
+          // t0 = [000a|aaaa|bbbb|bb00]
+          const uint16x8_t t0 = vshlq_n_u16(in, 2);
+          // t1 = [000a|aaaa|0000|0000]
+          const uint16x8_t t1 = vandq_u16(t0, v_1f00);
+          // t2 = [0000|0000|00bb|bbbb]
+          const uint16x8_t t2 = vandq_u16(in, v_003f);
+          // t3 = [000a|aaaa|00bb|bbbb]
+          const uint16x8_t t3 = vorrq_u16(t1, t2);
+          // t4 = [110a|aaaa|10bb|bbbb]
+          const uint16x8_t t4 = vorrq_u16(t3, v_c080);
+          // 2. merge ASCII and 2-byte codewords
+          const uint16x8_t v_007f = vmovq_n_u16((uint16_t)0x007F);
+          const uint16x8_t one_byte_bytemask = vcleq_u16(in, v_007f);
+          const uint8x16_t utf8_unpacked = vreinterpretq_u8_u16(vbslq_u16(one_byte_bytemask, in, t4));
+          // 3. prepare bitmask for 8-bit lookup
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+          const uint16x8_t mask = make_uint16x8_t(0x0001, 0x0004,
+                                    0x0010, 0x0040,
+                                    0x0002, 0x0008,
+                                    0x0020, 0x0080);
+#else
+          const uint16x8_t mask = { 0x0001, 0x0004,
+                                    0x0010, 0x0040,
+                                    0x0002, 0x0008,
+                                    0x0020, 0x0080 };
+#endif
+          uint16_t m2 = vaddvq_u16(vandq_u16(one_byte_bytemask, mask));
+          // 4. pack the bytes
+          const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[m2][0];
+          const uint8x16_t shuffle = vld1q_u8(row + 1);
+          const uint8x16_t utf8_packed = vqtbl1q_u8(utf8_unpacked, shuffle);
+
+          // 5. store bytes
+          vst1q_u8(utf8_output, utf8_packed);
+
+          // 6. adjust pointers
+          buf += 8;
+          utf8_output += row[0];
+          continue;
+
+    }
+    const uint16x8_t surrogates_bytemask = vceqq_u16(vandq_u16(in, v_f800), v_d800);
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+      if (vmaxvq_u16(surrogates_bytemask) == 0) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+        const uint16x8_t dup_even = make_uint16x8_t(0x0000, 0x0202, 0x0404, 0x0606,
+                                     0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+#else
+        const uint16x8_t dup_even = {0x0000, 0x0202, 0x0404, 0x0606,
+                                     0x0808, 0x0a0a, 0x0c0c, 0x0e0e};
+#endif
+        /* In this branch we handle three cases:
+           1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+           2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+           3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+          We expand the input word (16-bit) into two words (32-bit), thus
+          we have room for four bytes. However, we need five distinct bit
+          layouts. Note that the last byte in cases #2 and #3 is the same.
+
+          We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+          in register t2.
+
+          We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+          either byte 1 for case #2 or byte 2 for case #3. Note that they
+          differ by exactly one bit.
+
+          Finally from these two words we build proper UTF-8 sequence, taking
+          into account the case (i.e, the number of bytes to write).
+        */
+        /**
+         * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+         * t2 => [0ccc|cccc] [10cc|cccc]
+         * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+         */
+#define vec(x) vmovq_n_u16(static_cast<uint16_t>(x))
+        // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+        const uint16x8_t t0 = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in), vreinterpretq_u8_u16(dup_even)));
+        // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+        const uint16x8_t t1 = vandq_u16(t0, vec(0b0011111101111111));
+        // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+        const uint16x8_t t2 = vorrq_u16 (t1, vec(0b1000000000000000));
+
+        // s0: [aaaa|bbbb|bbcc|cccc] => [0000|0000|0000|aaaa]
+        const uint16x8_t s0 = vshrq_n_u16(in, 12);
+        // s1: [aaaa|bbbb|bbcc|cccc] => [0000|bbbb|bb00|0000]
+        const uint16x8_t s1 = vandq_u16(in, vec(0b0000111111000000));
+        // [0000|bbbb|bb00|0000] => [00bb|bbbb|0000|0000]
+        const uint16x8_t s1s = vshlq_n_u16(s1, 2);
+        // [00bb|bbbb|0000|aaaa]
+        const uint16x8_t s2 = vorrq_u16(s0, s1s);
+        // s3: [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+        const uint16x8_t s3 = vorrq_u16(s2, vec(0b1100000011100000));
+        const uint16x8_t v_07ff = vmovq_n_u16((uint16_t)0x07FF);
+        const uint16x8_t one_or_two_bytes_bytemask = vcleq_u16(in, v_07ff);
+        const uint16x8_t m0 = vbicq_u16(vec(0b0100000000000000), one_or_two_bytes_bytemask);
+        const uint16x8_t s4 = veorq_u16(s3, m0);
+#undef vec
+
+        // 4. expand words 16-bit => 32-bit
+        const uint8x16_t out0 = vreinterpretq_u8_u16(vzip1q_u16(t2, s4));
+        const uint8x16_t out1 = vreinterpretq_u8_u16(vzip2q_u16(t2, s4));
+
+        // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+        const uint16x8_t v_007f = vmovq_n_u16((uint16_t)0x007F);
+        const uint16x8_t one_byte_bytemask = vcleq_u16(in, v_007f);
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+        const uint16x8_t onemask = make_uint16x8_t(0x0001, 0x0004,
+                                    0x0010, 0x0040,
+                                    0x0100, 0x0400,
+                                    0x1000, 0x4000 );
+        const uint16x8_t twomask = make_uint16x8_t(0x0002, 0x0008,
+                                    0x0020, 0x0080,
+                                    0x0200, 0x0800,
+                                    0x2000, 0x8000 );
+#else
+        const uint16x8_t onemask = { 0x0001, 0x0004,
+                                    0x0010, 0x0040,
+                                    0x0100, 0x0400,
+                                    0x1000, 0x4000 };
+        const uint16x8_t twomask = { 0x0002, 0x0008,
+                                    0x0020, 0x0080,
+                                    0x0200, 0x0800,
+                                    0x2000, 0x8000 };
+#endif
+        const uint16x8_t combined = vorrq_u16(vandq_u16(one_byte_bytemask, onemask), vandq_u16(one_or_two_bytes_bytemask, twomask));
+        const uint16_t mask = vaddvq_u16(combined);
+        // The following fast path may or may not be beneficial.
+        /*if(mask == 0) {
+          // We only have three-byte words. Use fast path.
+          const uint8x16_t shuffle = {2,3,1,6,7,5,10,11,9,14,15,13,0,0,0,0};
+          const uint8x16_t utf8_0 = vqtbl1q_u8(out0, shuffle);
+          const uint8x16_t utf8_1 = vqtbl1q_u8(out1, shuffle);
+          vst1q_u8(utf8_output, utf8_0);
+          utf8_output += 12;
+          vst1q_u8(utf8_output, utf8_1);
+          utf8_output += 12;
+          buf += 8;
+          continue;
+        }*/
+        const uint8_t mask0 = uint8_t(mask);
+
+        const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+        const uint8x16_t shuffle0 = vld1q_u8(row0 + 1);
+        const uint8x16_t utf8_0 = vqtbl1q_u8(out0, shuffle0);
+
+        const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+        const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+        const uint8x16_t shuffle1 = vld1q_u8(row1 + 1);
+        const uint8x16_t utf8_1 = vqtbl1q_u8(out1, shuffle1);
+
+        vst1q_u8(utf8_output, utf8_0);
+        utf8_output += row0[0];
+        vst1q_u8(utf8_output, utf8_1);
+        utf8_output += row1[0];
+
+        buf += 8;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word & 0xFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word &0xF800 ) != 0xD800) {
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k + 1]) : buf[k + 1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(result(error_code::SURROGATE, buf - start + k - 1), reinterpret_cast<char*>(utf8_output)); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf8_output++ = char((value>>18) | 0b11110000);
+          *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((value & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), reinterpret_cast<char*>(utf8_output));
+}
+/* end file src/arm64/arm_convert_utf16_to_utf8.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_convert_utf16_to_utf32.cpp
+/* begin file src/arm64/arm_convert_utf16_to_utf32.cpp */
+/*
+    The vectorized algorithm works on single SSE register i.e., it
+    loads eight 16-bit words.
+
+    We consider three cases:
+    1. an input register contains no surrogates and each value
+       is in range 0x0000 .. 0x07ff.
+    2. an input register contains no surrogates and values are
+       is in range 0x0000 .. 0xffff.
+    3. an input register contains surrogates --- i.e. codepoints
+       can have 16 or 32 bits.
+
+    Ad 1.
+
+    When values are less than 0x0800, it means that a 16-bit words
+    can be converted into: 1) single UTF8 byte (when it's an ASCII
+    char) or 2) two UTF8 bytes.
+
+    For this case we do only some shuffle to obtain these 2-byte
+    codes and finally compress the whole SSE register with a single
+    shuffle.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+    Ad 2.
+
+    When values fit in 16-bit words, but are above 0x07ff, then
+    a single word may produce one, two or three UTF8 bytes.
+
+    We prepare data for all these three cases in two registers.
+    The first register contains lower two UTF8 bytes (used in all
+    cases), while the second one contains just the third byte for
+    the three-UTF8-bytes case.
+
+    Finally these two registers are interleaved forming eight-element
+    array of 32-bit values. The array spans two SSE registers.
+    The bytes from the registers are compressed using two shuffles.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+
+    To summarize:
+    - We need two 256-entry tables that have 8704 bytes in total.
+*/
+/*
+  Returns a pair: the first unprocessed byte from buf and utf8_output
+  A scalar routing should carry on the conversion of the tail.
+*/
+template <endianness big_endian>
+std::pair<const char16_t*, char32_t*> arm_convert_utf16_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_out) {
+  uint32_t * utf32_output = reinterpret_cast<uint32_t*>(utf32_out);
+  const char16_t* end = buf + len;
+
+  const uint16x8_t v_f800 = vmovq_n_u16((uint16_t)0xf800);
+  const uint16x8_t v_d800 = vmovq_n_u16((uint16_t)0xd800);
+
+  while (buf + 16 <= end) {
+    uint16x8_t in = vld1q_u16(reinterpret_cast<const uint16_t *>(buf));
+    if (big_endian) {
+      #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+      const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+      #else
+      const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+      #endif
+      in = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in), swap));
+    }
+
+    const uint16x8_t surrogates_bytemask = vceqq_u16(vandq_u16(in, v_f800), v_d800);
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+      if (vmaxvq_u16(surrogates_bytemask) == 0) {
+      // case: no surrogate pairs, extend all 16-bit words to 32-bit words
+      vst1q_u32(utf32_output,  vmovl_u16(vget_low_u16(in)));
+      vst1q_u32(utf32_output+4,  vmovl_high_u16(in));
+      utf32_output += 8;
+      buf += 8;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word &0xF800 ) != 0xD800) {
+          *utf32_output++ = char32_t(word);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k + 1]) : buf[k + 1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(nullptr, reinterpret_cast<char32_t*>(utf32_output)); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf32_output++ = char32_t(value);
+        }
+      }
+      buf += k;
+    }
+  } // while
+  return std::make_pair(buf, reinterpret_cast<char32_t*>(utf32_output));
+}
+
+
+/*
+  Returns a pair: a result struct and utf8_output.
+  If there is an error, the count field of the result is the position of the error.
+  Otherwise, it is the position of the first unprocessed byte in buf (even if finished).
+  A scalar routing should carry on the conversion of the tail if needed.
+*/
+template <endianness big_endian>
+std::pair<result, char32_t*> arm_convert_utf16_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_out) {
+  uint32_t * utf32_output = reinterpret_cast<uint32_t*>(utf32_out);
+  const char16_t* start = buf;
+  const char16_t* end = buf + len;
+
+  const uint16x8_t v_f800 = vmovq_n_u16((uint16_t)0xf800);
+  const uint16x8_t v_d800 = vmovq_n_u16((uint16_t)0xd800);
+
+  while (buf + 16 <= end) {
+    uint16x8_t in = vld1q_u16(reinterpret_cast<const uint16_t *>(buf));
+    if (big_endian) {
+      #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+      const uint8x16_t swap = make_uint8x16_t(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+      #else
+      const uint8x16_t swap = {1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14};
+      #endif
+      in = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(in), swap));
+    }
+
+    const uint16x8_t surrogates_bytemask = vceqq_u16(vandq_u16(in, v_f800), v_d800);
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+      if (vmaxvq_u16(surrogates_bytemask) == 0) {
+      // case: no surrogate pairs, extend all 16-bit words to 32-bit words
+      vst1q_u32(utf32_output,  vmovl_u16(vget_low_u16(in)));
+      vst1q_u32(utf32_output+4,  vmovl_high_u16(in));
+      utf32_output += 8;
+      buf += 8;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word &0xF800 ) != 0xD800) {
+          *utf32_output++ = char32_t(word);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k + 1]) : buf[k + 1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(result(error_code::SURROGATE, buf - start + k - 1), reinterpret_cast<char32_t*>(utf32_output)); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf32_output++ = char32_t(value);
+        }
+      }
+      buf += k;
+    }
+  } // while
+  return std::make_pair(result(error_code::SUCCESS, buf - start), reinterpret_cast<char32_t*>(utf32_output));
+}
+/* end file src/arm64/arm_convert_utf16_to_utf32.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_convert_utf32_to_utf8.cpp
+/* begin file src/arm64/arm_convert_utf32_to_utf8.cpp */
+std::pair<const char32_t*, char*> arm_convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_out) {
+  uint8_t * utf8_output = reinterpret_cast<uint8_t*>(utf8_out);
+  const char32_t* end = buf + len;
+
+  const uint16x8_t v_c080 = vmovq_n_u16((uint16_t)0xc080);
+
+  uint16x8_t forbidden_bytemask = vmovq_n_u16(0x0);
+
+  while (buf + 16 <= end) {
+    uint32x4_t in = vld1q_u32(reinterpret_cast<const uint32_t *>(buf));
+    uint32x4_t nextin = vld1q_u32(reinterpret_cast<const uint32_t *>(buf+4));
+
+    // Check if no bits set above 16th
+    if(vmaxvq_u32(vorrq_u32(in, nextin)) <= 0xFFFF) {
+      // Pack UTF-32 to UTF-16 safely (without surrogate pairs)
+      // Apply UTF-16 => UTF-8 routine (arm_convert_utf16_to_utf8.cpp)
+      uint16x8_t utf16_packed = vcombine_u16(vmovn_u32(in), vmovn_u32(nextin));
+      if(vmaxvq_u16(utf16_packed) <= 0x7F) { // ASCII fast path!!!!
+          // 1. pack the bytes
+          // obviously suboptimal.
+          uint8x8_t utf8_packed = vmovn_u16(utf16_packed);
+          // 2. store (8 bytes)
+          vst1_u8(utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 8;
+          utf8_output += 8;
+          continue; // we are done for this round!
+      }
+
+      if (vmaxvq_u16(utf16_packed) <= 0x7FF) {
+            // 1. prepare 2-byte values
+            // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+            // expected output   : [110a|aaaa|10bb|bbbb] x 8
+            const uint16x8_t v_1f00 = vmovq_n_u16((int16_t)0x1f00);
+            const uint16x8_t v_003f = vmovq_n_u16((int16_t)0x003f);
+
+            // t0 = [000a|aaaa|bbbb|bb00]
+            const uint16x8_t t0 = vshlq_n_u16(utf16_packed, 2);
+            // t1 = [000a|aaaa|0000|0000]
+            const uint16x8_t t1 = vandq_u16(t0, v_1f00);
+            // t2 = [0000|0000|00bb|bbbb]
+            const uint16x8_t t2 = vandq_u16(utf16_packed, v_003f);
+            // t3 = [000a|aaaa|00bb|bbbb]
+            const uint16x8_t t3 = vorrq_u16(t1, t2);
+            // t4 = [110a|aaaa|10bb|bbbb]
+            const uint16x8_t t4 = vorrq_u16(t3, v_c080);
+            // 2. merge ASCII and 2-byte codewords
+            const uint16x8_t v_007f = vmovq_n_u16((uint16_t)0x007F);
+            const uint16x8_t one_byte_bytemask = vcleq_u16(utf16_packed, v_007f);
+            const uint8x16_t utf8_unpacked = vreinterpretq_u8_u16(vbslq_u16(one_byte_bytemask, utf16_packed, t4));
+            // 3. prepare bitmask for 8-bit lookup
+  #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+            const uint16x8_t mask = make_uint16x8_t(0x0001, 0x0004,
+                                      0x0010, 0x0040,
+                                      0x0002, 0x0008,
+                                      0x0020, 0x0080);
+  #else
+            const uint16x8_t mask = { 0x0001, 0x0004,
+                                      0x0010, 0x0040,
+                                      0x0002, 0x0008,
+                                      0x0020, 0x0080 };
+  #endif
+            uint16_t m2 = vaddvq_u16(vandq_u16(one_byte_bytemask, mask));
+            // 4. pack the bytes
+            const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[m2][0];
+            const uint8x16_t shuffle = vld1q_u8(row + 1);
+            const uint8x16_t utf8_packed = vqtbl1q_u8(utf8_unpacked, shuffle);
+
+            // 5. store bytes
+            vst1q_u8(utf8_output, utf8_packed);
+
+            // 6. adjust pointers
+            buf += 8;
+            utf8_output += row[0];
+            continue;
+
+      } else {
+        // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+        const uint16x8_t v_d800 = vmovq_n_u16((uint16_t)0xd800);
+        const uint16x8_t v_dfff = vmovq_n_u16((uint16_t)0xdfff);
+        forbidden_bytemask = vorrq_u16(vandq_u16(vcleq_u16(utf16_packed, v_dfff), vcgeq_u16(utf16_packed, v_d800)), forbidden_bytemask);
+
+  #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+          const uint16x8_t dup_even = make_uint16x8_t(0x0000, 0x0202, 0x0404, 0x0606,
+                                      0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+  #else
+          const uint16x8_t dup_even = {0x0000, 0x0202, 0x0404, 0x0606,
+                                      0x0808, 0x0a0a, 0x0c0c, 0x0e0e};
+  #endif
+          /* In this branch we handle three cases:
+            1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+            2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+            3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+            We expand the input word (16-bit) into two words (32-bit), thus
+            we have room for four bytes. However, we need five distinct bit
+            layouts. Note that the last byte in cases #2 and #3 is the same.
+
+            We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+            in register t2.
+
+            We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+            either byte 1 for case #2 or byte 2 for case #3. Note that they
+            differ by exactly one bit.
+
+            Finally from these two words we build proper UTF-8 sequence, taking
+            into account the case (i.e, the number of bytes to write).
+          */
+          /**
+           * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+           * t2 => [0ccc|cccc] [10cc|cccc]
+           * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+           */
+  #define vec(x) vmovq_n_u16(static_cast<uint16_t>(x))
+          // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+          const uint16x8_t t0 = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(utf16_packed), vreinterpretq_u8_u16(dup_even)));
+          // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+          const uint16x8_t t1 = vandq_u16(t0, vec(0b0011111101111111));
+          // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+          const uint16x8_t t2 = vorrq_u16 (t1, vec(0b1000000000000000));
+
+          // s0: [aaaa|bbbb|bbcc|cccc] => [0000|0000|0000|aaaa]
+          const uint16x8_t s0 = vshrq_n_u16(utf16_packed, 12);
+          // s1: [aaaa|bbbb|bbcc|cccc] => [0000|bbbb|bb00|0000]
+          const uint16x8_t s1 = vandq_u16(utf16_packed, vec(0b0000111111000000));
+          // [0000|bbbb|bb00|0000] => [00bb|bbbb|0000|0000]
+          const uint16x8_t s1s = vshlq_n_u16(s1, 2);
+          // [00bb|bbbb|0000|aaaa]
+          const uint16x8_t s2 = vorrq_u16(s0, s1s);
+          // s3: [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+          const uint16x8_t s3 = vorrq_u16(s2, vec(0b1100000011100000));
+          const uint16x8_t v_07ff = vmovq_n_u16((uint16_t)0x07FF);
+          const uint16x8_t one_or_two_bytes_bytemask = vcleq_u16(utf16_packed, v_07ff);
+          const uint16x8_t m0 = vbicq_u16(vec(0b0100000000000000), one_or_two_bytes_bytemask);
+          const uint16x8_t s4 = veorq_u16(s3, m0);
+  #undef vec
+
+          // 4. expand words 16-bit => 32-bit
+          const uint8x16_t out0 = vreinterpretq_u8_u16(vzip1q_u16(t2, s4));
+          const uint8x16_t out1 = vreinterpretq_u8_u16(vzip2q_u16(t2, s4));
+
+          // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+          const uint16x8_t v_007f = vmovq_n_u16((uint16_t)0x007F);
+          const uint16x8_t one_byte_bytemask = vcleq_u16(utf16_packed, v_007f);
+  #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+          const uint16x8_t onemask = make_uint16x8_t(0x0001, 0x0004,
+                                      0x0010, 0x0040,
+                                      0x0100, 0x0400,
+                                      0x1000, 0x4000 );
+          const uint16x8_t twomask = make_uint16x8_t(0x0002, 0x0008,
+                                      0x0020, 0x0080,
+                                      0x0200, 0x0800,
+                                      0x2000, 0x8000 );
+  #else
+          const uint16x8_t onemask = { 0x0001, 0x0004,
+                                      0x0010, 0x0040,
+                                      0x0100, 0x0400,
+                                      0x1000, 0x4000 };
+          const uint16x8_t twomask = { 0x0002, 0x0008,
+                                      0x0020, 0x0080,
+                                      0x0200, 0x0800,
+                                      0x2000, 0x8000 };
+  #endif
+          const uint16x8_t combined = vorrq_u16(vandq_u16(one_byte_bytemask, onemask), vandq_u16(one_or_two_bytes_bytemask, twomask));
+          const uint16_t mask = vaddvq_u16(combined);
+          // The following fast path may or may not be beneficial.
+          /*if(mask == 0) {
+            // We only have three-byte words. Use fast path.
+            const uint8x16_t shuffle = {2,3,1,6,7,5,10,11,9,14,15,13,0,0,0,0};
+            const uint8x16_t utf8_0 = vqtbl1q_u8(out0, shuffle);
+            const uint8x16_t utf8_1 = vqtbl1q_u8(out1, shuffle);
+            vst1q_u8(utf8_output, utf8_0);
+            utf8_output += 12;
+            vst1q_u8(utf8_output, utf8_1);
+            utf8_output += 12;
+            buf += 8;
+            continue;
+          }*/
+          const uint8_t mask0 = uint8_t(mask);
+
+          const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+          const uint8x16_t shuffle0 = vld1q_u8(row0 + 1);
+          const uint8x16_t utf8_0 = vqtbl1q_u8(out0, shuffle0);
+
+          const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+          const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+          const uint8x16_t shuffle1 = vld1q_u8(row1 + 1);
+          const uint8x16_t utf8_1 = vqtbl1q_u8(out1, shuffle1);
+
+          vst1q_u8(utf8_output, utf8_0);
+          utf8_output += row0[0];
+          vst1q_u8(utf8_output, utf8_1);
+          utf8_output += row1[0];
+
+          buf += 8;
+      }
+    // At least one 32-bit word will produce a surrogate pair in UTF-16 <=> will produce four UTF-8 bytes.
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFFFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xFFFFF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word & 0xFFFF0000)==0) {
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(nullptr, reinterpret_cast<char*>(utf8_output)); }
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          if (word > 0x10FFFF) { return std::make_pair(nullptr, reinterpret_cast<char*>(utf8_output)); }
+          *utf8_output++ = char((word>>18) | 0b11110000);
+          *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  // check for invalid input
+  if (vmaxvq_u16(forbidden_bytemask) != 0) {
+    return std::make_pair(nullptr, reinterpret_cast<char*>(utf8_output));
+  }
+  return std::make_pair(buf, reinterpret_cast<char*>(utf8_output));
+}
+
+
+std::pair<result, char*> arm_convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_out) {
+  uint8_t * utf8_output = reinterpret_cast<uint8_t*>(utf8_out);
+  const char32_t* start = buf;
+  const char32_t* end = buf + len;
+
+  const uint16x8_t v_c080 = vmovq_n_u16((uint16_t)0xc080);
+
+  while (buf + 16 <= end) {
+    uint32x4_t in = vld1q_u32(reinterpret_cast<const uint32_t *>(buf));
+    uint32x4_t nextin = vld1q_u32(reinterpret_cast<const uint32_t *>(buf+4));
+
+    // Check if no bits set above 16th
+    if(vmaxvq_u32(vorrq_u32(in, nextin)) <= 0xFFFF) {
+      // Pack UTF-32 to UTF-16 safely (without surrogate pairs)
+      // Apply UTF-16 => UTF-8 routine (arm_convert_utf16_to_utf8.cpp)
+      uint16x8_t utf16_packed = vcombine_u16(vmovn_u32(in), vmovn_u32(nextin));
+      if(vmaxvq_u16(utf16_packed) <= 0x7F) { // ASCII fast path!!!!
+          // 1. pack the bytes
+          // obviously suboptimal.
+          uint8x8_t utf8_packed = vmovn_u16(utf16_packed);
+          // 2. store (8 bytes)
+          vst1_u8(utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 8;
+          utf8_output += 8;
+          continue; // we are done for this round!
+      }
+
+      if (vmaxvq_u16(utf16_packed) <= 0x7FF) {
+            // 1. prepare 2-byte values
+            // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+            // expected output   : [110a|aaaa|10bb|bbbb] x 8
+            const uint16x8_t v_1f00 = vmovq_n_u16((int16_t)0x1f00);
+            const uint16x8_t v_003f = vmovq_n_u16((int16_t)0x003f);
+
+            // t0 = [000a|aaaa|bbbb|bb00]
+            const uint16x8_t t0 = vshlq_n_u16(utf16_packed, 2);
+            // t1 = [000a|aaaa|0000|0000]
+            const uint16x8_t t1 = vandq_u16(t0, v_1f00);
+            // t2 = [0000|0000|00bb|bbbb]
+            const uint16x8_t t2 = vandq_u16(utf16_packed, v_003f);
+            // t3 = [000a|aaaa|00bb|bbbb]
+            const uint16x8_t t3 = vorrq_u16(t1, t2);
+            // t4 = [110a|aaaa|10bb|bbbb]
+            const uint16x8_t t4 = vorrq_u16(t3, v_c080);
+            // 2. merge ASCII and 2-byte codewords
+            const uint16x8_t v_007f = vmovq_n_u16((uint16_t)0x007F);
+            const uint16x8_t one_byte_bytemask = vcleq_u16(utf16_packed, v_007f);
+            const uint8x16_t utf8_unpacked = vreinterpretq_u8_u16(vbslq_u16(one_byte_bytemask, utf16_packed, t4));
+            // 3. prepare bitmask for 8-bit lookup
+  #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+            const uint16x8_t mask = make_uint16x8_t(0x0001, 0x0004,
+                                      0x0010, 0x0040,
+                                      0x0002, 0x0008,
+                                      0x0020, 0x0080);
+  #else
+            const uint16x8_t mask = { 0x0001, 0x0004,
+                                      0x0010, 0x0040,
+                                      0x0002, 0x0008,
+                                      0x0020, 0x0080 };
+  #endif
+            uint16_t m2 = vaddvq_u16(vandq_u16(one_byte_bytemask, mask));
+            // 4. pack the bytes
+            const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[m2][0];
+            const uint8x16_t shuffle = vld1q_u8(row + 1);
+            const uint8x16_t utf8_packed = vqtbl1q_u8(utf8_unpacked, shuffle);
+
+            // 5. store bytes
+            vst1q_u8(utf8_output, utf8_packed);
+
+            // 6. adjust pointers
+            buf += 8;
+            utf8_output += row[0];
+            continue;
+
+      } else {
+        // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+
+        // check for invalid input
+        const uint16x8_t v_d800 = vmovq_n_u16((uint16_t)0xd800);
+        const uint16x8_t v_dfff = vmovq_n_u16((uint16_t)0xdfff);
+        const uint16x8_t forbidden_bytemask = vandq_u16(vcleq_u16(utf16_packed, v_dfff), vcgeq_u16(utf16_packed, v_d800));
+        if (vmaxvq_u16(forbidden_bytemask) != 0) {
+          return std::make_pair(result(error_code::SURROGATE, buf - start), reinterpret_cast<char*>(utf8_output));
+        }
+
+  #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+          const uint16x8_t dup_even = make_uint16x8_t(0x0000, 0x0202, 0x0404, 0x0606,
+                                      0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+  #else
+          const uint16x8_t dup_even = {0x0000, 0x0202, 0x0404, 0x0606,
+                                      0x0808, 0x0a0a, 0x0c0c, 0x0e0e};
+  #endif
+          /* In this branch we handle three cases:
+            1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+            2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+            3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+            We expand the input word (16-bit) into two words (32-bit), thus
+            we have room for four bytes. However, we need five distinct bit
+            layouts. Note that the last byte in cases #2 and #3 is the same.
+
+            We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+            in register t2.
+
+            We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+            either byte 1 for case #2 or byte 2 for case #3. Note that they
+            differ by exactly one bit.
+
+            Finally from these two words we build proper UTF-8 sequence, taking
+            into account the case (i.e, the number of bytes to write).
+          */
+          /**
+           * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+           * t2 => [0ccc|cccc] [10cc|cccc]
+           * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+           */
+  #define vec(x) vmovq_n_u16(static_cast<uint16_t>(x))
+          // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+          const uint16x8_t t0 = vreinterpretq_u16_u8(vqtbl1q_u8(vreinterpretq_u8_u16(utf16_packed), vreinterpretq_u8_u16(dup_even)));
+          // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+          const uint16x8_t t1 = vandq_u16(t0, vec(0b0011111101111111));
+          // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+          const uint16x8_t t2 = vorrq_u16 (t1, vec(0b1000000000000000));
+
+          // s0: [aaaa|bbbb|bbcc|cccc] => [0000|0000|0000|aaaa]
+          const uint16x8_t s0 = vshrq_n_u16(utf16_packed, 12);
+          // s1: [aaaa|bbbb|bbcc|cccc] => [0000|bbbb|bb00|0000]
+          const uint16x8_t s1 = vandq_u16(utf16_packed, vec(0b0000111111000000));
+          // [0000|bbbb|bb00|0000] => [00bb|bbbb|0000|0000]
+          const uint16x8_t s1s = vshlq_n_u16(s1, 2);
+          // [00bb|bbbb|0000|aaaa]
+          const uint16x8_t s2 = vorrq_u16(s0, s1s);
+          // s3: [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+          const uint16x8_t s3 = vorrq_u16(s2, vec(0b1100000011100000));
+          const uint16x8_t v_07ff = vmovq_n_u16((uint16_t)0x07FF);
+          const uint16x8_t one_or_two_bytes_bytemask = vcleq_u16(utf16_packed, v_07ff);
+          const uint16x8_t m0 = vbicq_u16(vec(0b0100000000000000), one_or_two_bytes_bytemask);
+          const uint16x8_t s4 = veorq_u16(s3, m0);
+  #undef vec
+
+          // 4. expand words 16-bit => 32-bit
+          const uint8x16_t out0 = vreinterpretq_u8_u16(vzip1q_u16(t2, s4));
+          const uint8x16_t out1 = vreinterpretq_u8_u16(vzip2q_u16(t2, s4));
+
+          // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+          const uint16x8_t v_007f = vmovq_n_u16((uint16_t)0x007F);
+          const uint16x8_t one_byte_bytemask = vcleq_u16(utf16_packed, v_007f);
+  #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+          const uint16x8_t onemask = make_uint16x8_t(0x0001, 0x0004,
+                                      0x0010, 0x0040,
+                                      0x0100, 0x0400,
+                                      0x1000, 0x4000 );
+          const uint16x8_t twomask = make_uint16x8_t(0x0002, 0x0008,
+                                      0x0020, 0x0080,
+                                      0x0200, 0x0800,
+                                      0x2000, 0x8000 );
+  #else
+          const uint16x8_t onemask = { 0x0001, 0x0004,
+                                      0x0010, 0x0040,
+                                      0x0100, 0x0400,
+                                      0x1000, 0x4000 };
+          const uint16x8_t twomask = { 0x0002, 0x0008,
+                                      0x0020, 0x0080,
+                                      0x0200, 0x0800,
+                                      0x2000, 0x8000 };
+  #endif
+          const uint16x8_t combined = vorrq_u16(vandq_u16(one_byte_bytemask, onemask), vandq_u16(one_or_two_bytes_bytemask, twomask));
+          const uint16_t mask = vaddvq_u16(combined);
+          // The following fast path may or may not be beneficial.
+          /*if(mask == 0) {
+            // We only have three-byte words. Use fast path.
+            const uint8x16_t shuffle = {2,3,1,6,7,5,10,11,9,14,15,13,0,0,0,0};
+            const uint8x16_t utf8_0 = vqtbl1q_u8(out0, shuffle);
+            const uint8x16_t utf8_1 = vqtbl1q_u8(out1, shuffle);
+            vst1q_u8(utf8_output, utf8_0);
+            utf8_output += 12;
+            vst1q_u8(utf8_output, utf8_1);
+            utf8_output += 12;
+            buf += 8;
+            continue;
+          }*/
+          const uint8_t mask0 = uint8_t(mask);
+
+          const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+          const uint8x16_t shuffle0 = vld1q_u8(row0 + 1);
+          const uint8x16_t utf8_0 = vqtbl1q_u8(out0, shuffle0);
+
+          const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+          const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+          const uint8x16_t shuffle1 = vld1q_u8(row1 + 1);
+          const uint8x16_t utf8_1 = vqtbl1q_u8(out1, shuffle1);
+
+          vst1q_u8(utf8_output, utf8_0);
+          utf8_output += row0[0];
+          vst1q_u8(utf8_output, utf8_1);
+          utf8_output += row1[0];
+
+          buf += 8;
+      }
+    // At least one 32-bit word will produce a surrogate pair in UTF-16 <=> will produce four UTF-8 bytes.
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFFFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xFFFFF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word & 0xFFFF0000)==0) {
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(result(error_code::SURROGATE, buf - start + k), reinterpret_cast<char*>(utf8_output)); }
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          if (word > 0x10FFFF) { return std::make_pair(result(error_code::TOO_LARGE, buf - start + k), reinterpret_cast<char*>(utf8_output)); }
+          *utf8_output++ = char((word>>18) | 0b11110000);
+          *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), reinterpret_cast<char*>(utf8_output));
+}
+/* end file src/arm64/arm_convert_utf32_to_utf8.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=arm64/arm_convert_utf32_to_utf16.cpp
+/* begin file src/arm64/arm_convert_utf32_to_utf16.cpp */
+template <endianness big_endian>
+std::pair<const char32_t*, char16_t*> arm_convert_utf32_to_utf16(const char32_t* buf, size_t len, char16_t* utf16_out) {
+  uint16_t * utf16_output = reinterpret_cast<uint16_t*>(utf16_out);
+  const char32_t* end = buf + len;
+
+  uint16x4_t forbidden_bytemask = vmov_n_u16(0x0);
+
+  while(buf + 4 <= end) {
+    uint32x4_t in = vld1q_u32(reinterpret_cast<const uint32_t *>(buf));
+
+    // Check if no bits set above 16th
+    if(vmaxvq_u32(in) <= 0xFFFF) {
+      uint16x4_t utf16_packed = vmovn_u32(in);
+
+      const uint16x4_t v_d800 = vmov_n_u16((uint16_t)0xd800);
+      const uint16x4_t v_dfff = vmov_n_u16((uint16_t)0xdfff);
+      forbidden_bytemask = vorr_u16(vand_u16(vcle_u16(utf16_packed, v_dfff), vcge_u16(utf16_packed, v_d800)), forbidden_bytemask);
+
+      if (big_endian) {
+        #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+        const uint8x8_t swap = make_uint8x8_t(1, 0, 3, 2, 5, 4, 7, 6);
+        #else
+        const uint8x8_t swap = {1, 0, 3, 2, 5, 4, 7, 6};
+        #endif
+        utf16_packed = vreinterpret_u16_u8(vtbl1_u8(vreinterpret_u8_u16(utf16_packed), swap));
+      }
+      vst1_u16(utf16_output, utf16_packed);
+      utf16_output += 4;
+      buf += 4;
+    } else {
+      size_t forward = 3;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFF0000)==0) {
+          // will not generate a surrogate pair
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(nullptr, reinterpret_cast<char16_t*>(utf16_output)); }
+          *utf16_output++ = big_endian ? char16_t(word >> 8 | word << 8) : char16_t(word);
+        } else {
+          // will generate a surrogate pair
+          if (word > 0x10FFFF) { return std::make_pair(nullptr, reinterpret_cast<char16_t*>(utf16_output)); }
+          word -= 0x10000;
+          uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+          uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+          if (big_endian) {
+            high_surrogate = uint16_t(high_surrogate >> 8 | high_surrogate << 8);
+            low_surrogate = uint16_t(low_surrogate << 8 | low_surrogate >> 8);
+          }
+          *utf16_output++ = char16_t(high_surrogate);
+          *utf16_output++ = char16_t(low_surrogate);
+        }
+      }
+      buf += k;
+    }
+  }
+
+  // check for invalid input
+  if (vmaxv_u16(forbidden_bytemask) != 0) {
+    return std::make_pair(nullptr, reinterpret_cast<char16_t*>(utf16_output));
+  }
+
+  return std::make_pair(buf, reinterpret_cast<char16_t*>(utf16_output));
+}
+
+
+template <endianness big_endian>
+std::pair<result, char16_t*> arm_convert_utf32_to_utf16_with_errors(const char32_t* buf, size_t len, char16_t* utf16_out) {
+  uint16_t * utf16_output = reinterpret_cast<uint16_t*>(utf16_out);
+  const char32_t* start = buf;
+  const char32_t* end = buf + len;
+
+  while(buf + 4 <= end) {
+    uint32x4_t in = vld1q_u32(reinterpret_cast<const uint32_t *>(buf));
+
+    // Check if no bits set above 16th
+    if(vmaxvq_u32(in) <= 0xFFFF) {
+      uint16x4_t utf16_packed = vmovn_u32(in);
+
+      const uint16x4_t v_d800 = vmov_n_u16((uint16_t)0xd800);
+      const uint16x4_t v_dfff = vmov_n_u16((uint16_t)0xdfff);
+      const uint16x4_t forbidden_bytemask = vand_u16(vcle_u16(utf16_packed, v_dfff), vcge_u16(utf16_packed, v_d800));
+      if (vmaxv_u16(forbidden_bytemask) != 0) {
+        return std::make_pair(result(error_code::SURROGATE, buf - start), reinterpret_cast<char16_t*>(utf16_output));
+      }
+
+      if (big_endian) {
+        #ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+        const uint8x8_t swap = make_uint8x8_t(1, 0, 3, 2, 5, 4, 7, 6);
+        #else
+        const uint8x8_t swap = {1, 0, 3, 2, 5, 4, 7, 6};
+        #endif
+        utf16_packed = vreinterpret_u16_u8(vtbl1_u8(vreinterpret_u8_u16(utf16_packed), swap));
+      }
+      vst1_u16(utf16_output, utf16_packed);
+      utf16_output += 4;
+      buf += 4;
+    } else {
+      size_t forward = 3;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFF0000)==0) {
+          // will not generate a surrogate pair
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(result(error_code::SURROGATE, buf - start + k), reinterpret_cast<char16_t*>(utf16_output)); }
+          *utf16_output++ = big_endian ? char16_t(word >> 8 | word << 8) : char16_t(word);
+        } else {
+          // will generate a surrogate pair
+          if (word > 0x10FFFF) { return std::make_pair(result(error_code::TOO_LARGE, buf - start + k), reinterpret_cast<char16_t*>(utf16_output)); }
+          word -= 0x10000;
+          uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+          uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+          if (big_endian) {
+            high_surrogate = uint16_t(high_surrogate >> 8 | high_surrogate << 8);
+            low_surrogate = uint16_t(low_surrogate << 8 | low_surrogate >> 8);
+          }
+          *utf16_output++ = char16_t(high_surrogate);
+          *utf16_output++ = char16_t(low_surrogate);
+        }
+      }
+      buf += k;
+    }
+  }
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), reinterpret_cast<char16_t*>(utf16_output));
+}
+/* end file src/arm64/arm_convert_utf32_to_utf16.cpp */
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/buf_block_reader.h
+/* begin file src/generic/buf_block_reader.h */
+namespace simdutf {
+namespace arm64 {
+namespace {
+
+// Walks through a buffer in block-sized increments, loading the last part with spaces
+template<size_t STEP_SIZE>
+struct buf_block_reader {
+public:
+  simdutf_really_inline buf_block_reader(const uint8_t *_buf, size_t _len);
+  simdutf_really_inline size_t block_index();
+  simdutf_really_inline bool has_full_block() const;
+  simdutf_really_inline const uint8_t *full_block() const;
+  /**
+   * Get the last block, padded with spaces.
+   *
+   * There will always be a last block, with at least 1 byte, unless len == 0 (in which case this
+   * function fills the buffer with spaces and returns 0. In particular, if len == STEP_SIZE there
+   * will be 0 full_blocks and 1 remainder block with STEP_SIZE bytes and no spaces for padding.
+   *
+   * @return the number of effective characters in the last block.
+   */
+  simdutf_really_inline size_t get_remainder(uint8_t *dst) const;
+  simdutf_really_inline void advance();
+private:
+  const uint8_t *buf;
+  const size_t len;
+  const size_t lenminusstep;
+  size_t idx;
+};
+
+// Routines to print masks and text for debugging bitmask operations
+simdutf_unused static char * format_input_text_64(const uint8_t *text) {
+  static char *buf = reinterpret_cast<char*>(malloc(sizeof(simd8x64<uint8_t>) + 1));
+  for (size_t i=0; i<sizeof(simd8x64<uint8_t>); i++) {
+    buf[i] = int8_t(text[i]) < ' ' ? '_' : int8_t(text[i]);
+  }
+  buf[sizeof(simd8x64<uint8_t>)] = '\0';
+  return buf;
+}
+
+// Routines to print masks and text for debugging bitmask operations
+simdutf_unused static char * format_input_text(const simd8x64<uint8_t>& in) {
+  static char *buf = reinterpret_cast<char*>(malloc(sizeof(simd8x64<uint8_t>) + 1));
+  in.store(reinterpret_cast<uint8_t*>(buf));
+  for (size_t i=0; i<sizeof(simd8x64<uint8_t>); i++) {
+    if (buf[i] < ' ') { buf[i] = '_'; }
+  }
+  buf[sizeof(simd8x64<uint8_t>)] = '\0';
+  return buf;
+}
+
+simdutf_unused static char * format_mask(uint64_t mask) {
+  static char *buf = reinterpret_cast<char*>(malloc(64 + 1));
+  for (size_t i=0; i<64; i++) {
+    buf[i] = (mask & (size_t(1) << i)) ? 'X' : ' ';
+  }
+  buf[64] = '\0';
+  return buf;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline buf_block_reader<STEP_SIZE>::buf_block_reader(const uint8_t *_buf, size_t _len) : buf{_buf}, len{_len}, lenminusstep{len < STEP_SIZE ? 0 : len - STEP_SIZE}, idx{0} {}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline size_t buf_block_reader<STEP_SIZE>::block_index() { return idx; }
+
+template<size_t STEP_SIZE>
+simdutf_really_inline bool buf_block_reader<STEP_SIZE>::has_full_block() const {
+  return idx < lenminusstep;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline const uint8_t *buf_block_reader<STEP_SIZE>::full_block() const {
+  return &buf[idx];
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline size_t buf_block_reader<STEP_SIZE>::get_remainder(uint8_t *dst) const {
+  if(len == idx) { return 0; } // memcpy(dst, null, 0) will trigger an error with some sanitizers
+  std::memset(dst, 0x20, STEP_SIZE); // std::memset STEP_SIZE because it's more efficient to write out 8 or 16 bytes at once.
+  std::memcpy(dst, buf + idx, len - idx);
+  return len - idx;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline void buf_block_reader<STEP_SIZE>::advance() {
+  idx += STEP_SIZE;
+}
+
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/buf_block_reader.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_validation/utf8_lookup4_algorithm.h
+/* begin file src/generic/utf8_validation/utf8_lookup4_algorithm.h */
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace utf8_validation {
+
+using namespace simd;
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+  //
+  // Return nonzero if there are incomplete multibyte characters at the end of the block:
+  // e.g. if there is a 4-byte character, but it's 3 bytes from the end.
+  //
+  simdutf_really_inline simd8<uint8_t> is_incomplete(const simd8<uint8_t> input) {
+    // If the previous input's last 3 bytes match this, they're too short (they ended at EOF):
+    // ... 1111____ 111_____ 11______
+    static const uint8_t max_array[32] = {
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 0b11110000u-1, 0b11100000u-1, 0b11000000u-1
+    };
+    const simd8<uint8_t> max_value(&max_array[sizeof(max_array)-sizeof(simd8<uint8_t>)]);
+    return input.gt_bits(max_value);
+  }
+
+  struct utf8_checker {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+    // The last input we received
+    simd8<uint8_t> prev_input_block;
+    // Whether the last input we received was incomplete (used for ASCII fast path)
+    simd8<uint8_t> prev_incomplete;
+
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+    // The only problem that can happen at EOF is that a multibyte character is too short
+    // or a byte value too large in the last bytes: check_special_cases only checks for bytes
+    // too large in the first of two bytes.
+    simdutf_really_inline void check_eof() {
+      // If the previous block had incomplete UTF-8 characters at the end, an ASCII block can't
+      // possibly finish them.
+      this->error |= this->prev_incomplete;
+    }
+
+    simdutf_really_inline void check_next_input(const simd8x64<uint8_t>& input) {
+      if(simdutf_likely(is_ascii(input))) {
+        this->error |= this->prev_incomplete;
+      } else {
+        // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+        static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+            "We support either two or four chunks per 64-byte block.");
+        if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+          this->check_utf8_bytes(input.chunks[0], this->prev_input_block);
+          this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+        } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+          this->check_utf8_bytes(input.chunks[0], this->prev_input_block);
+          this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+          this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+        }
+        this->prev_incomplete = is_incomplete(input.chunks[simd8x64<uint8_t>::NUM_CHUNKS-1]);
+        this->prev_input_block = input.chunks[simd8x64<uint8_t>::NUM_CHUNKS-1];
+
+      }
+    }
+
+    // do not forget to call check_eof!
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // namespace utf8_validation
+
+using utf8_validation::utf8_checker;
+
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/utf8_validation/utf8_lookup4_algorithm.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_validation/utf8_validator.h
+/* begin file src/generic/utf8_validation/utf8_validator.h */
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace utf8_validation {
+
+/**
+ * Validates that the string is actual UTF-8.
+ */
+template<class checker>
+bool generic_validate_utf8(const uint8_t * input, size_t length) {
+    checker c{};
+    buf_block_reader<64> reader(input, length);
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      c.check_next_input(in);
+      reader.advance();
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    c.check_next_input(in);
+    reader.advance();
+    c.check_eof();
+    return !c.errors();
+}
+
+bool generic_validate_utf8(const char * input, size_t length) {
+  return generic_validate_utf8<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+/**
+ * Validates that the string is actual UTF-8 and stops on errors.
+ */
+template<class checker>
+result generic_validate_utf8_with_errors(const uint8_t * input, size_t length) {
+    checker c{};
+    buf_block_reader<64> reader(input, length);
+    size_t count{0};
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      c.check_next_input(in);
+      if(c.errors()) {
+        if (count != 0) { count--; } // Sometimes the error is only detected in the next chunk
+        result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+        res.count += count;
+        return res;
+      }
+      reader.advance();
+      count += 64;
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    c.check_next_input(in);
+    reader.advance();
+    c.check_eof();
+    if (c.errors()) {
+      result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(input) + count, length - count);
+      res.count += count;
+      return res;
+    } else {
+      return result(error_code::SUCCESS, length);
+    }
+}
+
+result generic_validate_utf8_with_errors(const char * input, size_t length) {
+  return generic_validate_utf8_with_errors<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+template<class checker>
+bool generic_validate_ascii(const uint8_t * input, size_t length) {
+    buf_block_reader<64> reader(input, length);
+    uint8_t blocks[64]{};
+    simd::simd8x64<uint8_t> running_or(blocks);
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      running_or |= in;
+      reader.advance();
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    running_or |= in;
+    return running_or.is_ascii();
+}
+
+bool generic_validate_ascii(const char * input, size_t length) {
+  return generic_validate_ascii<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+template<class checker>
+result generic_validate_ascii_with_errors(const uint8_t * input, size_t length) {
+  buf_block_reader<64> reader(input, length);
+  size_t count{0};
+  while (reader.has_full_block()) {
+    simd::simd8x64<uint8_t> in(reader.full_block());
+    if (!in.is_ascii()) {
+      result res = scalar::ascii::validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+      return result(res.error, count + res.count);
+    }
+    reader.advance();
+
+    count += 64;
+  }
+  uint8_t block[64]{};
+  reader.get_remainder(block);
+  simd::simd8x64<uint8_t> in(block);
+  if (!in.is_ascii()) {
+    result res = scalar::ascii::validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+    return result(res.error, count + res.count);
+  } else {
+    return result(error_code::SUCCESS, length);
+  }
+}
+
+result generic_validate_ascii_with_errors(const char * input, size_t length) {
+  return generic_validate_ascii_with_errors<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+} // namespace utf8_validation
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/utf8_validation/utf8_validator.h */
+// transcoding from UTF-8 to UTF-16
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf16/valid_utf8_to_utf16.h
+/* begin file src/generic/utf8_to_utf16/valid_utf8_to_utf16.h */
+
+
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace utf8_to_utf16 {
+
+using namespace simd;
+
+template <endianness endian>
+simdutf_warn_unused size_t convert_valid(const char* input, size_t size,
+    char16_t* utf16_output) noexcept {
+  // The implementation is not specific to haswell and should be moved to the generic directory.
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  const size_t safety_margin = 16; // to avoid overruns!
+  while(pos + 64 + safety_margin <= size) {
+    // this loop could be unrolled further. For example, we could process the mask
+    // far more than 64 bytes.
+    simd8x64<int8_t> in(reinterpret_cast<const int8_t *>(input + pos));
+    if(in.is_ascii()) {
+      in.store_ascii_as_utf16<endian>(utf16_output);
+      utf16_output += 64;
+      pos += 64;
+    } else {
+      // Slow path. We hope that the compiler will recognize that this is a slow path.
+      // Anything that is not a continuation mask is a 'leading byte', that is, the
+      // start of a new code point.
+      uint64_t utf8_continuation_mask = in.lt(-65 + 1);
+      // -65 is 0b10111111 in two-complement's, so largest possible continuation byte
+      uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+      // The *start* of code points is not so useful, rather, we want the *end* of code points.
+      uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+      // We process in blocks of up to 12 bytes except possibly
+      // for fast paths which may process up to 16 bytes. For the
+      // slow path to work, we should have at least 12 input bytes left.
+      size_t max_starting_point = (pos + 64) - 12;
+      // Next loop is going to run at least five times when using solely
+      // the slow/regular path, and at least four times if there are fast paths.
+      while(pos < max_starting_point) {
+        // Performance note: our ability to compute 'consumed' and
+        // then shift and recompute is critical. If there is a
+        // latency of, say, 4 cycles on getting 'consumed', then
+        // the inner loop might have a total latency of about 6 cycles.
+        // Yet we process between 6 to 12 inputs bytes, thus we get
+        // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+        // for this section of the code. Hence, there is a limit
+        // to how much we can further increase this latency before
+        // it seriously harms performance.
+        //
+        // Thus we may allow convert_masked_utf8_to_utf16 to process
+        // more bytes at a time under a fast-path mode where 16 bytes
+        // are consumed at once (e.g., when encountering ASCII).
+        size_t consumed = convert_masked_utf8_to_utf16<endian>(input + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+        pos += consumed;
+        utf8_end_of_code_point_mask >>= consumed;
+      }
+      // At this point there may remain between 0 and 12 bytes in the
+      // 64-byte block.These bytes will be processed again. So we have an
+      // 80% efficiency (in the worst case). In practice we expect an
+      // 85% to 90% efficiency.
+    }
+  }
+  utf16_output += scalar::utf8_to_utf16::convert_valid<endian>(input + pos, size - pos, utf16_output);
+  return utf16_output - start;
+}
+
+} // namespace utf8_to_utf16
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf16/valid_utf8_to_utf16.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf16/utf8_to_utf16.h
+/* begin file src/generic/utf8_to_utf16/utf8_to_utf16.h */
+
+
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace utf8_to_utf16 {
+using namespace simd;
+
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+
+  struct validating_transcoder {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+
+    validating_transcoder() : error(uint8_t(0)) {}
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+
+    template <endianness endian>
+    simdutf_really_inline size_t convert(const char* in, size_t size, char16_t* utf16_output) {
+      size_t pos = 0;
+      char16_t* start{utf16_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf16<endian>(utf16_output);
+          utf16_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf16<endian>(in + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) { return 0; }
+      if(pos < size) {
+        size_t howmany  = scalar::utf8_to_utf16::convert<endian>(in + pos, size - pos, utf16_output);
+        if(howmany == 0) { return 0; }
+        utf16_output += howmany;
+      }
+      return utf16_output - start;
+    }
+
+    template <endianness endian>
+    simdutf_really_inline result convert_with_errors(const char* in, size_t size, char16_t* utf16_output) {
+      size_t pos = 0;
+      char16_t* start{utf16_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf16<endian>(utf16_output);
+          utf16_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          if (errors()) {
+            result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+            res.count += pos;
+            return res;
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf16<endian>(in + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) {
+        result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+        res.count += pos;
+        return res;
+      }
+      if(pos < size) {
+        result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+        if (res.error) {    // In case of error, we want the error position
+          res.count += pos;
+          return res;
+        } else {    // In case of success, we want the number of word written
+          utf16_output += res.count;
+        }
+      }
+      return result(error_code::SUCCESS, utf16_output - start);
+    }
+
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // utf8_to_utf16 namespace
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf16/utf8_to_utf16.h */
+// transcoding from UTF-8 to UTF-32
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf32/valid_utf8_to_utf32.h
+/* begin file src/generic/utf8_to_utf32/valid_utf8_to_utf32.h */
+
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace utf8_to_utf32 {
+
+using namespace simd;
+
+
+simdutf_warn_unused size_t convert_valid(const char* input, size_t size,
+    char32_t* utf32_output) noexcept {
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  const size_t safety_margin = 16; // to avoid overruns!
+  while(pos + 64 + safety_margin <= size) {
+    simd8x64<int8_t> in(reinterpret_cast<const int8_t *>(input + pos));
+    if(in.is_ascii()) {
+      in.store_ascii_as_utf32(utf32_output);
+      utf32_output += 64;
+      pos += 64;
+    } else {
+    // -65 is 0b10111111 in two-complement's, so largest possible continuation byte
+    uint64_t utf8_continuation_mask = in.lt(-65 + 1);
+    uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+    uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+    size_t max_starting_point = (pos + 64) - 12;
+    while(pos < max_starting_point) {
+      size_t consumed = convert_masked_utf8_to_utf32(input + pos,
+                          utf8_end_of_code_point_mask, utf32_output);
+      pos += consumed;
+      utf8_end_of_code_point_mask >>= consumed;
+      }
+    }
+  }
+  utf32_output += scalar::utf8_to_utf32::convert_valid(input + pos, size - pos, utf32_output);
+  return utf32_output - start;
+}
+
+
+} // namespace utf8_to_utf32
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf32/valid_utf8_to_utf32.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf32/utf8_to_utf32.h
+/* begin file src/generic/utf8_to_utf32/utf8_to_utf32.h */
+
+
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace utf8_to_utf32 {
+using namespace simd;
+
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+
+  struct validating_transcoder {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+
+    validating_transcoder() : error(uint8_t(0)) {}
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+
+
+    simdutf_really_inline size_t convert(const char* in, size_t size, char32_t* utf32_output) {
+      size_t pos = 0;
+      char32_t* start{utf32_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf32(utf32_output);
+          utf32_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf32(in + pos,
+                            utf8_end_of_code_point_mask, utf32_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) { return 0; }
+      if(pos < size) {
+        size_t howmany  = scalar::utf8_to_utf32::convert(in + pos, size - pos, utf32_output);
+        if(howmany == 0) { return 0; }
+        utf32_output += howmany;
+      }
+      return utf32_output - start;
+    }
+
+    simdutf_really_inline result convert_with_errors(const char* in, size_t size, char32_t* utf32_output) {
+      size_t pos = 0;
+      char32_t* start{utf32_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf32(utf32_output);
+          utf32_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          if (errors()) {
+            result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+            res.count += pos;
+            return res;
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf32(in + pos,
+                            utf8_end_of_code_point_mask, utf32_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) {
+        result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+        res.count += pos;
+        return res;
+      }
+      if(pos < size) {
+        result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+        if (res.error) {    // In case of error, we want the error position
+          res.count += pos;
+          return res;
+        } else {    // In case of success, we want the number of word written
+          utf32_output += res.count;
+        }
+      }
+      return result(error_code::SUCCESS, utf32_output - start);
+    }
+
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // utf8_to_utf32 namespace
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf32/utf8_to_utf32.h */
+// other functions
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8.h
+/* begin file src/generic/utf8.h */
+
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace utf8 {
+
+using namespace simd;
+
+simdutf_really_inline size_t count_code_points(const char* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    for(;pos + 64 <= size; pos += 64) {
+      simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+      uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+      count += 64 - count_ones(utf8_continuation_mask);
+    }
+    return count + scalar::utf8::count_code_points(in + pos, size - pos);
+}
+
+
+simdutf_really_inline size_t utf16_length_from_utf8(const char* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 64 <= size; pos += 64) {
+      simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+      uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+      // We count one word for anything that is not a continuation (so
+      // leading bytes).
+      count += 64 - count_ones(utf8_continuation_mask);
+      int64_t utf8_4byte = input.gteq_unsigned(240);
+      count += count_ones(utf8_4byte);
+    }
+    return count + scalar::utf8::utf16_length_from_utf8(in + pos, size - pos);
+}
+
+
+simdutf_really_inline size_t utf32_length_from_utf8(const char* in, size_t size) {
+    return count_code_points(in, size);
+}
+} // utf8 namespace
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/utf8.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf16.h
+/* begin file src/generic/utf16.h */
+namespace simdutf {
+namespace arm64 {
+namespace {
+namespace utf16 {
+
+template <endianness big_endian>
+simdutf_really_inline size_t count_code_points(const char16_t* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    for(;pos + 32 <= size; pos += 32) {
+      simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+      if (big_endian) input.swap_bytes();
+      uint64_t not_pair = input.not_in_range(0xDC00, 0xDFFF);
+      count += count_ones(not_pair) / 2;
+    }
+    return count + scalar::utf16::count_code_points<big_endian>(in + pos, size - pos);
+}
+
+template <endianness big_endian>
+simdutf_really_inline size_t utf8_length_from_utf16(const char16_t* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 32 <= size; pos += 32) {
+      simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+      if (big_endian) input.swap_bytes();
+      uint64_t ascii_mask = input.lteq(0x7F);
+      uint64_t twobyte_mask = input.lteq(0x7FF);
+      uint64_t not_pair_mask = input.not_in_range(0xD800, 0xDFFF);
+
+      size_t ascii_count = count_ones(ascii_mask) / 2;
+      size_t twobyte_count = count_ones(twobyte_mask & ~ ascii_mask) / 2;
+      size_t threebyte_count = count_ones(not_pair_mask & ~ twobyte_mask) / 2;
+      size_t fourbyte_count = 32 - count_ones(not_pair_mask) / 2;
+      count += 2 * fourbyte_count + 3 * threebyte_count + 2 * twobyte_count + ascii_count;
+    }
+    return count + scalar::utf16::utf8_length_from_utf16<big_endian>(in + pos, size - pos);
+}
+
+template <endianness big_endian>
+simdutf_really_inline size_t utf32_length_from_utf16(const char16_t* in, size_t size) {
+    return count_code_points<big_endian>(in, size);
+}
+
+simdutf_really_inline void change_endianness_utf16(const char16_t* in, size_t size, char16_t* output) {
+  size_t pos = 0;
+
+  while (pos + 32 <= size) {
+    simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+    input.swap_bytes();
+    input.store(reinterpret_cast<uint16_t *>(output));
+    pos += 32;
+    output += 32;
+  }
+
+  scalar::utf16::change_endianness_utf16(in + pos, size - pos, output);
+}
+
+} // utf16
+} // unnamed namespace
+} // namespace arm64
+} // namespace simdutf
+/* end file src/generic/utf16.h */
+//
+// Implementation-specific overrides
+//
+namespace simdutf {
+namespace arm64 {
+
+simdutf_warn_unused int implementation::detect_encodings(const char * input, size_t length) const noexcept {
+  // If there is a BOM, then we trust it.
+  auto bom_encoding = simdutf::BOM::check_bom(input, length);
+  if(bom_encoding != encoding_type::unspecified) { return bom_encoding; }
+  if (length % 2 == 0) {
+    return arm_detect_encodings<utf8_validation::utf8_checker>(input, length);
+  } else {
+    if (implementation::validate_utf8(input, length)) {
+      return simdutf::encoding_type::UTF8;
+    } else {
+      return simdutf::encoding_type::unspecified;
+    }
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf8(const char *buf, size_t len) const noexcept {
+  return arm64::utf8_validation::generic_validate_utf8(buf,len);
+}
+
+simdutf_warn_unused result implementation::validate_utf8_with_errors(const char *buf, size_t len) const noexcept {
+  return arm64::utf8_validation::generic_validate_utf8_with_errors(buf,len);
+}
+
+simdutf_warn_unused bool implementation::validate_ascii(const char *buf, size_t len) const noexcept {
+  return arm64::utf8_validation::generic_validate_ascii(buf,len);
+}
+
+simdutf_warn_unused result implementation::validate_ascii_with_errors(const char *buf, size_t len) const noexcept {
+  return arm64::utf8_validation::generic_validate_ascii_with_errors(buf,len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf16le(const char16_t *buf, size_t len) const noexcept {
+  const char16_t* tail = arm_validate_utf16<endianness::LITTLE>(buf, len);
+  if (tail) {
+    return scalar::utf16::validate<endianness::LITTLE>(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf16be(const char16_t *buf, size_t len) const noexcept {
+  const char16_t* tail = arm_validate_utf16<endianness::BIG>(buf, len);
+  if (tail) {
+    return scalar::utf16::validate<endianness::BIG>(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept {
+  result res = arm_validate_utf16_with_errors<endianness::LITTLE>(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf16::validate_with_errors<endianness::LITTLE>(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept {
+  result res = arm_validate_utf16_with_errors<endianness::BIG>(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf16::validate_with_errors<endianness::BIG>(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf32(const char32_t *buf, size_t len) const noexcept {
+  const char32_t* tail = arm_validate_utf32le(buf, len);
+  if (tail) {
+    return scalar::utf32::validate(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept {
+  result res = arm_validate_utf32le_with_errors(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf32::validate_with_errors(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16le(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16be(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16le_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16be_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert_with_errors<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16le(const char* input, size_t size,
+    char16_t* utf16_output) const noexcept {
+  return utf8_to_utf16::convert_valid<endianness::LITTLE>(input, size,  utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16be(const char* input, size_t size,
+    char16_t* utf16_output) const noexcept {
+  return utf8_to_utf16::convert_valid<endianness::BIG>(input, size,  utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf32(const char* buf, size_t len, char32_t* utf32_output) const noexcept {
+  utf8_to_utf32::validating_transcoder converter;
+  return converter.convert(buf, len, utf32_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf32_with_errors(const char* buf, size_t len, char32_t* utf32_output) const noexcept {
+  utf8_to_utf32::validating_transcoder converter;
+  return converter.convert_with_errors(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf32(const char* input, size_t size,
+    char32_t* utf32_output) const noexcept {
+  return utf8_to_utf32::convert_valid(input, size,  utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char16_t*, char*> ret = arm_convert_utf16_to_utf8<endianness::LITTLE>(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf8::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char16_t*, char*> ret = arm_convert_utf16_to_utf8<endianness::BIG>(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf8::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = arm_convert_utf16_to_utf8_with_errors<endianness::LITTLE>(buf, len, utf8_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf8::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = arm_convert_utf16_to_utf8_with_errors<endianness::BIG>(buf, len, utf8_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf8::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf16le_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf16be_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char32_t*, char*> ret = arm_convert_utf32_to_utf8(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf8::convert(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = arm_convert_utf32_to_utf8_with_errors(buf, len, utf8_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf8::convert_with_errors(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::pair<const char16_t*, char32_t*> ret = arm_convert_utf16_to_utf32<endianness::LITTLE>(buf, len, utf32_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf32_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::pair<const char16_t*, char32_t*> ret = arm_convert_utf16_to_utf32<endianness::BIG>(buf, len, utf32_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf32_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char32_t*> ret = arm_convert_utf16_to_utf32_with_errors<endianness::LITTLE>(buf, len, utf32_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf32_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char32_t*> ret = arm_convert_utf16_to_utf32_with_errors<endianness::BIG>(buf, len, utf32_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf32_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf32_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  std::pair<const char32_t*, char16_t*> ret = arm_convert_utf32_to_utf16<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf16_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf16::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  std::pair<const char32_t*, char16_t*> ret = arm_convert_utf32_to_utf16<endianness::BIG>(buf, len, utf16_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf16_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf16::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16le_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char16_t*> ret = arm_convert_utf32_to_utf16_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf16::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf16_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16be_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char16_t*> ret = arm_convert_utf32_to_utf16_with_errors<endianness::BIG>(buf, len, utf16_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf16::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf16_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return convert_utf32_to_utf16le(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return convert_utf32_to_utf16be(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return convert_utf16le_to_utf32(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return convert_utf16be_to_utf32(buf, len, utf32_output);
+}
+
+void implementation::change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) const noexcept {
+  utf16::change_endianness_utf16(input, length, output);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::count_code_points<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::count_code_points<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf8(const char * input, size_t length) const noexcept {
+  return utf8::count_code_points(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf8_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf8_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf32_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf32_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf8(const char * input, size_t length) const noexcept {
+  return utf8::utf16_length_from_utf8(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  const uint32x4_t v_7f = vmovq_n_u32((uint32_t)0x7f);
+  const uint32x4_t v_7ff = vmovq_n_u32((uint32_t)0x7ff);
+  const uint32x4_t v_ffff = vmovq_n_u32((uint32_t)0xffff);
+  const uint32x4_t v_1 = vmovq_n_u32((uint32_t)0x1);
+  size_t pos = 0;
+  size_t count = 0;
+  for(;pos + 4 <= length; pos += 4) {
+    uint32x4_t in = vld1q_u32(reinterpret_cast<const uint32_t *>(input + pos));
+    const uint32x4_t ascii_bytes_bytemask = vcleq_u32(in, v_7f);
+    const uint32x4_t one_two_bytes_bytemask = vcleq_u32(in, v_7ff);
+    const uint32x4_t two_bytes_bytemask = veorq_u32(one_two_bytes_bytemask, ascii_bytes_bytemask);
+    const uint32x4_t three_bytes_bytemask = veorq_u32(vcleq_u32(in, v_ffff), one_two_bytes_bytemask);
+
+    const uint16x8_t reduced_ascii_bytes_bytemask = vreinterpretq_u16_u32(vandq_u32(ascii_bytes_bytemask, v_1));
+    const uint16x8_t reduced_two_bytes_bytemask = vreinterpretq_u16_u32(vandq_u32(two_bytes_bytemask, v_1));
+    const uint16x8_t reduced_three_bytes_bytemask = vreinterpretq_u16_u32(vandq_u32(three_bytes_bytemask, v_1));
+
+    const uint16x8_t compressed_bytemask0 = vpaddq_u16(reduced_ascii_bytes_bytemask, reduced_two_bytes_bytemask);
+    const uint16x8_t compressed_bytemask1 = vpaddq_u16(reduced_three_bytes_bytemask, reduced_three_bytes_bytemask);
+
+    size_t ascii_count = count_ones(vgetq_lane_u64(vreinterpretq_u64_u16(compressed_bytemask0), 0));
+    size_t two_bytes_count = count_ones(vgetq_lane_u64(vreinterpretq_u64_u16(compressed_bytemask0), 1));
+    size_t three_bytes_count = count_ones(vgetq_lane_u64(vreinterpretq_u64_u16(compressed_bytemask1), 0));
+
+    count += 16 - 3*ascii_count - 2*two_bytes_count - three_bytes_count;
+  }
+  return count + scalar::utf32::utf8_length_from_utf32(input + pos, length - pos);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  const uint32x4_t v_ffff = vmovq_n_u32((uint32_t)0xffff);
+  const uint32x4_t v_1 = vmovq_n_u32((uint32_t)0x1);
+  size_t pos = 0;
+  size_t count = 0;
+  for(;pos + 4 <= length; pos += 4) {
+    uint32x4_t in = vld1q_u32(reinterpret_cast<const uint32_t *>(input + pos));
+    const uint32x4_t surrogate_bytemask = vcgtq_u32(in, v_ffff);
+    const uint16x8_t reduced_bytemask = vreinterpretq_u16_u32(vandq_u32(surrogate_bytemask, v_1));
+    const uint16x8_t compressed_bytemask = vpaddq_u16(reduced_bytemask, reduced_bytemask);
+    size_t surrogate_count = count_ones(vgetq_lane_u64(vreinterpretq_u64_u16(compressed_bytemask), 0));
+    count += 4 + surrogate_count;
+  }
+  return count + scalar::utf32::utf16_length_from_utf32(input + pos, length - pos);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf8(const char * input, size_t length) const noexcept {
+  return utf8::utf32_length_from_utf8(input, length);
+}
+
+} // namespace arm64
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/arm64/end.h
+/* begin file src/simdutf/arm64/end.h */
+/* end file src/simdutf/arm64/end.h */
+/* end file src/arm64/implementation.cpp */
+#endif
+#if SIMDUTF_IMPLEMENTATION_FALLBACK
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=fallback/implementation.cpp
+/* begin file src/fallback/implementation.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/fallback/begin.h
+/* begin file src/simdutf/fallback/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "fallback"
+// #define SIMDUTF_IMPLEMENTATION fallback
+/* end file src/simdutf/fallback/begin.h */
+
+
+
+
+
+
+
+
+namespace simdutf {
+namespace fallback {
+
+simdutf_warn_unused int implementation::detect_encodings(const char * input, size_t length) const noexcept {
+  // If there is a BOM, then we trust it.
+  auto bom_encoding = simdutf::BOM::check_bom(input, length);
+  if(bom_encoding != encoding_type::unspecified) { return bom_encoding; }
+  int out = 0;
+  if(validate_utf8(input, length)) { out |= encoding_type::UTF8; }
+  if((length % 2) == 0) {
+    if(validate_utf16le(reinterpret_cast<const char16_t*>(input), length/2)) { out |= encoding_type::UTF16_LE; }
+  }
+  if((length % 4) == 0) {
+    if(validate_utf32(reinterpret_cast<const char32_t*>(input), length/4)) { out |= encoding_type::UTF32_LE; }
+  }
+
+  return out;
+}
+
+simdutf_warn_unused bool implementation::validate_utf8(const char *buf, size_t len) const noexcept {
+    return scalar::utf8::validate(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf8_with_errors(const char *buf, size_t len) const noexcept {
+    return scalar::utf8::validate_with_errors(buf, len);
+}
+
+simdutf_warn_unused bool implementation::validate_ascii(const char *buf, size_t len) const noexcept {
+    return scalar::ascii::validate(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_ascii_with_errors(const char *buf, size_t len) const noexcept {
+    return scalar::ascii::validate_with_errors(buf, len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf16le(const char16_t *buf, size_t len) const noexcept {
+    return scalar::utf16::validate<endianness::LITTLE>(buf, len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf16be(const char16_t *buf, size_t len) const noexcept {
+    return scalar::utf16::validate<endianness::BIG>(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept {
+    return scalar::utf16::validate_with_errors<endianness::LITTLE>(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept {
+    return scalar::utf16::validate_with_errors<endianness::BIG>(buf, len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf32(const char32_t *buf, size_t len) const noexcept {
+    return scalar::utf32::validate(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept {
+    return scalar::utf32::validate_with_errors(buf, len);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16le(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+   return scalar::utf8_to_utf16::convert<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16be(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+   return scalar::utf8_to_utf16::convert<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16le_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+   return scalar::utf8_to_utf16::convert_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16be_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+   return scalar::utf8_to_utf16::convert_with_errors<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16le(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+   return scalar::utf8_to_utf16::convert_valid<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16be(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+   return scalar::utf8_to_utf16::convert_valid<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf32(const char* buf, size_t len, char32_t* utf32_output) const noexcept {
+   return scalar::utf8_to_utf32::convert(buf, len, utf32_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf32_with_errors(const char* buf, size_t len, char32_t* utf32_output) const noexcept {
+   return scalar::utf8_to_utf32::convert_with_errors(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf32(const char* input, size_t size,
+    char32_t* utf32_output) const noexcept {
+  return scalar::utf8_to_utf32::convert_valid(input, size,  utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert<endianness::LITTLE>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert<endianness::BIG>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert_with_errors<endianness::LITTLE>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert_with_errors<endianness::BIG>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert_valid<endianness::LITTLE>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert_valid<endianness::BIG>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf32_to_utf8::convert(buf, len, utf8_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf32_to_utf8::convert_with_errors(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf32_to_utf8::convert_valid(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16le_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16be_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert_with_errors<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert_valid<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert_valid<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert<endianness::LITTLE>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert<endianness::BIG>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert_with_errors<endianness::LITTLE>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert_with_errors<endianness::BIG>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert_valid<endianness::LITTLE>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert_valid<endianness::BIG>(buf, len, utf32_output);
+}
+
+void implementation::change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) const noexcept {
+  scalar::utf16::change_endianness_utf16(input, length, output);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16le(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::count_code_points<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16be(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::count_code_points<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf8(const char * input, size_t length) const noexcept {
+  return scalar::utf8::count_code_points(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::utf8_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::utf8_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::utf32_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::utf32_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf8(const char * input, size_t length) const noexcept {
+  return scalar::utf8::utf16_length_from_utf8(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  return scalar::utf32::utf8_length_from_utf32(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  return scalar::utf32::utf16_length_from_utf32(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf8(const char * input, size_t length) const noexcept {
+  return scalar::utf8::utf32_length_from_utf8(input, length);
+}
+
+} // namespace fallback
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/fallback/end.h
+/* begin file src/simdutf/fallback/end.h */
+/* end file src/simdutf/fallback/end.h */
+/* end file src/fallback/implementation.cpp */
+#endif
+#if SIMDUTF_IMPLEMENTATION_ICELAKE
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/implementation.cpp
+/* begin file src/icelake/implementation.cpp */
+
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/icelake/begin.h
+/* begin file src/simdutf/icelake/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "icelake"
+// #define SIMDUTF_IMPLEMENTATION icelake
+SIMDUTF_TARGET_ICELAKE
+
+/* end file src/simdutf/icelake/begin.h */
+namespace simdutf {
+namespace icelake {
+namespace {
+#ifndef SIMDUTF_ICELAKE_H
+#error "icelake.h must be included"
+#endif
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_utf8_common.inl.cpp
+/* begin file src/icelake/icelake_utf8_common.inl.cpp */
+// Common procedures for both validating and non-validating conversions from UTF-8.
+enum block_processing_mode { SIMDUTF_FULL, SIMDUTF_TAIL};
+
+using utf8_to_utf16_result = std::pair<const char*, char16_t*>;
+using utf8_to_utf32_result = std::pair<const char*, uint32_t*>;
+
+/*
+    process_block_utf8_to_utf16 converts up to 64 bytes from 'in' from UTF-8
+    to UTF-16. When tail = SIMDUTF_FULL, then the full input buffer (64 bytes)
+    might be used. When tail = SIMDUTF_TAIL, we take into account 'gap' which
+    indicates how many input bytes are relevant.
+
+    Returns true when the result is correct, otherwise it returns false.
+
+    The provided in and out pointers are advanced according to how many input
+    bytes have been processed, upon success.
+*/
+template <block_processing_mode tail, endianness big_endian>
+simdutf_really_inline bool process_block_utf8_to_utf16(const char *&in, char16_t *&out, size_t gap) {
+  // constants
+  __m512i mask_identity = _mm512_set_epi8(63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0);
+  __m512i mask_c0c0c0c0 = _mm512_set1_epi32(0xc0c0c0c0);
+  __m512i mask_80808080 = _mm512_set1_epi32(0x80808080);
+  __m512i mask_f0f0f0f0 = _mm512_set1_epi32(0xf0f0f0f0);
+  __m512i mask_e0e0e0e0 = _mm512_set1_epi32(0xe0e0e0e0);
+  __m512i mask_c2c2c2c2 = _mm512_set1_epi32(0xc2c2c2c2);
+  __m512i mask_ffffffff = _mm512_set1_epi32(0xffffffff);
+  __m512i mask_d7c0d7c0 = _mm512_set1_epi32(0xd7c0d7c0);
+  __m512i mask_dc00dc00 = _mm512_set1_epi32(0xdc00dc00);
+  __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+  // Note that 'tail' is a compile-time constant !
+  __mmask64 b = (tail == SIMDUTF_FULL) ? 0xFFFFFFFFFFFFFFFF : (uint64_t(1) << gap) - 1;
+  __m512i input = (tail == SIMDUTF_FULL) ? _mm512_loadu_si512(in) : _mm512_maskz_loadu_epi8(b, in);
+  __mmask64 m1 = (tail == SIMDUTF_FULL) ? _mm512_cmplt_epu8_mask(input, mask_80808080) : _mm512_mask_cmplt_epu8_mask(b, input, mask_80808080);
+  if (m1 == b) { // all ASCII
+    if (tail == SIMDUTF_FULL) {
+      // we convert a full 64-byte block, writing 128 bytes.
+      __m512i input1 = _mm512_cvtepu8_epi16(_mm512_castsi512_si256(input));
+      if(big_endian) { input1 = _mm512_shuffle_epi8(input1, byteflip); }
+      _mm512_storeu_si512(out, input1);
+      out += 32;
+      __m512i input2 = _mm512_cvtepu8_epi16(_mm512_extracti64x4_epi64(input, 1));
+      if(big_endian) { input2 = _mm512_shuffle_epi8(input2, byteflip); }
+      _mm512_storeu_si512(out, input2);
+      out += 32;
+      in += 64;          // consumed 64 bytes
+      return true; // we are done
+    } else {
+      if (gap <= 32) {
+        __m512i input1 = _mm512_cvtepu8_epi16(_mm512_castsi512_si256(input));
+        if(big_endian) { input1 = _mm512_shuffle_epi8(input1, byteflip); }
+        _mm512_mask_storeu_epi16(out, __mmask32((uint64_t(1) << (gap)) - 1), input1);
+        out += gap;
+        in += gap;
+      } else {
+        __m512i input1 = _mm512_cvtepu8_epi16(_mm512_castsi512_si256(input));
+        if(big_endian) { input1 = _mm512_shuffle_epi8(input1, byteflip); }
+        _mm512_storeu_si512(out, input1);
+        out += 32;
+        __m512i input2 = _mm512_cvtepu8_epi16(_mm512_extracti64x4_epi64(input, 1));
+        if(big_endian) { input2 = _mm512_shuffle_epi8(input2, byteflip); }
+        _mm512_mask_storeu_epi16(out, __mmask32((uint32_t(1) << (gap - 32)) - 1), input2);
+        out += gap - 32;
+        in += gap;
+      }
+      return true;; // we are done
+    }
+  }
+  // classify characters further
+  __mmask64 m234 = _mm512_cmp_epu8_mask(mask_c0c0c0c0, input,
+                                        _MM_CMPINT_LE); // 0xc0 <= input, 2, 3, or 4 leading byte
+  __mmask64 m34 = _mm512_cmp_epu8_mask(mask_e0e0e0e0, input,
+                                       _MM_CMPINT_LE); // 0xe0 <= input,  3 or 4 leading byte
+
+  __mmask64 milltwobytes = _mm512_mask_cmp_epu8_mask(m234, input, mask_c2c2c2c2,
+                                                     _MM_CMPINT_LT); // 0xc0 <= input < 0xc2 (illegal two byte sequence)
+                                                                     // Overlong 2-byte sequence
+  if (_ktestz_mask64_u8(milltwobytes, milltwobytes) == 0) {
+    // Overlong 2-byte sequence
+    return false;
+  }
+  if (_ktestz_mask64_u8(m34, m34) == 0) {
+    // We have a 3-byte sequence and/or a 2-byte sequence
+    __mmask64 m4 = _mm512_cmp_epu8_mask(input, mask_f0f0f0f0,
+                                        _MM_CMPINT_NLT); // 0xf0 <= zmm0 (4 byte start bytes)
+
+    __mmask64 mask_not_ascii = (tail == SIMDUTF_FULL) ? _knot_mask64(m1) : _kand_mask64(_knot_mask64(m1), b);
+
+    __mmask64 mp1 = _kshiftli_mask64(m234, 1);
+    __mmask64 mp2 = _kshiftli_mask64(m34, 2);
+    if (m4 == 0) {
+      // Fast path with 1,2,3 bytes
+      __mmask64 mc = _kor_mask64(mp1, mp2); // expected continuation bytes
+      __mmask64 m1234 = _kor_mask64(m1, m234);
+      // mismatched continuation bytes:
+      __mmask64 bxorm1234 = _kxor_mask64(b, m1234);
+      if (mc != bxorm1234) { return false; }
+
+      // mend: identifying the last bytes of each sequence to be decoded
+      __mmask64 mend = _kshiftri_mask64(m1234, 1);
+      if (tail != SIMDUTF_FULL) {
+        mend = _kor_mask64(mend, (uint64_t(1) << (gap - 1)));
+      }
+      __m512i last_and_third = _mm512_maskz_compress_epi8(mend, mask_identity);
+      __m512i last_and_thirdu16 = _mm512_cvtepu8_epi16(_mm512_castsi512_si256(last_and_third));
+
+      __m512i nonasciitags = _mm512_maskz_mov_epi8(mask_not_ascii, mask_c0c0c0c0); // ASCII: 00000000  other: 11000000
+      __m512i clearedbytes = _mm512_andnot_si512(nonasciitags, input);             // high two bits cleared where not ASCII
+      __m512i lastbytes = _mm512_maskz_permutexvar_epi8(0x5555555555555555, last_and_thirdu16,
+                                                        clearedbytes); // the last byte of each character
+
+      __mmask64 mask_before_non_ascii = _kshiftri_mask64(mask_not_ascii, 1);               // bytes that precede non-ASCII bytes
+      __m512i indexofsecondlastbytes = _mm512_add_epi16(mask_ffffffff, last_and_thirdu16); // indices of the second last bytes
+      __m512i beforeasciibytes = _mm512_maskz_mov_epi8(mask_before_non_ascii, clearedbytes);
+      __m512i secondlastbytes = _mm512_maskz_permutexvar_epi8(0x5555555555555555, indexofsecondlastbytes,
+                                                              beforeasciibytes); // the second last bytes (of two, three byte seq,
+                                                                                 // surrogates)
+      secondlastbytes = _mm512_slli_epi16(secondlastbytes, 6);                   // shifted into position
+      __m512i secondandlastbytes = _mm512_add_epi16(secondlastbytes, lastbytes);
+
+      __mmask64 mask_thirdlastbytes = _kand_mask64(m34, 0x3fffffffffffffff); // bytes that could be third-last bytes
+                                                                             // (LEAD34 sans wrap around)
+      __m512i indexofthirdlastbytes = _mm512_add_epi16(mask_ffffffff,
+                                                       indexofsecondlastbytes); // indices of the second last bytes
+      __m512i thirdlastbyte = _mm512_maskz_mov_epi8(mask_thirdlastbytes,
+                                                    clearedbytes); // only those that are the third last byte of a sequece
+      __m512i thirdlastbytes = _mm512_maskz_permutexvar_epi8(0x5555555555555555, indexofthirdlastbytes,
+                                                             thirdlastbyte); // the third last bytes (of three byte sequences, hi
+                                                                             // surrogate)
+      thirdlastbytes = _mm512_slli_epi16(thirdlastbytes, 12);                // shifted into position
+      __m512i thirdsecondandlastbytes = _mm512_add_epi16(secondandlastbytes, thirdlastbytes);
+      __m512i Wout = thirdsecondandlastbytes;
+      // the elements of Wout excluding the last element if it happens to be a high surrogate:
+
+      __mmask64 mprocessed = (tail == SIMDUTF_FULL) ? _pdep_u64(0xFFFFFFFF, mend) : _pdep_u64(0xFFFFFFFF, _kand_mask64(mend, b)); // we adjust mend at the end of the output.
+
+      int64_t nout = _mm_popcnt_u64(mprocessed);
+      int64_t nin = 64 - _lzcnt_u64(mprocessed);
+
+      // Encodings out of range...
+      {
+        // the location of 3-byte sequence start bytes in the input
+        __mmask64 m3 = m34 & (b ^ m4);
+        // words in Wout corresponding to 3-byte sequences.
+        __mmask32 M3 = __mmask32(_pext_u64(m3 << 2, mend));
+        __m512i mask_08000800 = _mm512_set1_epi32(0x08000800);
+        __mmask32 Msmall800 = _mm512_mask_cmplt_epu16_mask(M3, Wout, mask_08000800);
+        __m512i mask_d800d800 = _mm512_set1_epi32(0xd800d800);
+        __m512i Moutminusd800 = _mm512_sub_epi16(Wout, mask_d800d800);
+        __mmask32 M3s = _mm512_mask_cmplt_epu16_mask(M3, Moutminusd800, mask_08000800);
+        if (_kor_mask32(Msmall800, M3s)) { return false; }
+      }
+      if(big_endian) { Wout = _mm512_shuffle_epi8(Wout, byteflip); }
+      _mm512_mask_storeu_epi16(out, __mmask32((uint64_t(1) << nout) - 1), Wout);
+      out += nout;
+      in += nin;
+      return true; // ok
+    }
+    //
+    // We have a 4-byte sequence, this is the general case.
+    // Slow!
+    __mmask64 mp3 = _kshiftli_mask64(m4, 3);
+    __mmask64 mc = _kor_mask64(_kor_mask64(mp1, mp2), mp3); // expected continuation bytes
+    __mmask64 m1234 = _kor_mask64(m1, m234);
+
+    // mend: identifying the last bytes of each sequence to be decoded
+    __mmask64 mend = _kor_mask64(_kshiftri_mask64(_kor_mask64(mp3, m1234), 1), mp3);
+    if (tail != SIMDUTF_FULL) {
+      mend = _kor_mask64(mend, __mmask64(uint64_t(1) << (gap - 1)));
+    }
+    __m512i last_and_third = _mm512_maskz_compress_epi8(mend, mask_identity);
+    __m512i last_and_thirdu16 = _mm512_cvtepu8_epi16(_mm512_castsi512_si256(last_and_third));
+
+    __m512i nonasciitags = _mm512_maskz_mov_epi8(mask_not_ascii, mask_c0c0c0c0); // ASCII: 00000000  other: 11000000
+    __m512i clearedbytes = _mm512_andnot_si512(nonasciitags, input);             // high two bits cleared where not ASCII
+    __m512i lastbytes = _mm512_maskz_permutexvar_epi8(0x5555555555555555, last_and_thirdu16,
+                                                      clearedbytes); // the last byte of each character
+
+    __mmask64 mask_before_non_ascii = _kshiftri_mask64(mask_not_ascii, 1);               // bytes that precede non-ASCII bytes
+    __m512i indexofsecondlastbytes = _mm512_add_epi16(mask_ffffffff, last_and_thirdu16); // indices of the second last bytes
+    __m512i beforeasciibytes = _mm512_maskz_mov_epi8(mask_before_non_ascii, clearedbytes);
+    __m512i secondlastbytes = _mm512_maskz_permutexvar_epi8(0x5555555555555555, indexofsecondlastbytes,
+                                                            beforeasciibytes); // the second last bytes (of two, three byte seq,
+                                                                               // surrogates)
+    secondlastbytes = _mm512_slli_epi16(secondlastbytes, 6);                   // shifted into position
+    __m512i secondandlastbytes = _mm512_add_epi16(secondlastbytes, lastbytes);
+
+    __mmask64 mask_thirdlastbytes = _kand_mask64(m34, 0x3fffffffffffffff); // bytes that could be third-last bytes
+                                                                           // (LEAD34 sans wrap around)
+    __m512i indexofthirdlastbytes = _mm512_add_epi16(mask_ffffffff,
+                                                     indexofsecondlastbytes); // indices of the second last bytes
+    __m512i thirdlastbyte = _mm512_maskz_mov_epi8(mask_thirdlastbytes,
+                                                  clearedbytes); // only those that are the third last byte of a sequece
+    __m512i thirdlastbytes = _mm512_maskz_permutexvar_epi8(0x5555555555555555, indexofthirdlastbytes,
+                                                           thirdlastbyte); // the third last bytes (of three byte sequences, hi
+                                                                           // surrogate)
+    thirdlastbytes = _mm512_slli_epi16(thirdlastbytes, 12);                // shifted into position
+    __m512i thirdsecondandlastbytes = _mm512_add_epi16(secondandlastbytes, thirdlastbytes);
+    uint64_t Mlo_uint64 = _pext_u64(mp3, mend);
+    __mmask32 Mlo = __mmask32(Mlo_uint64);
+    __mmask32 Mhi = __mmask32(Mlo_uint64 >> 1);
+    __m512i lo_surr_mask = _mm512_maskz_mov_epi16(Mlo,
+                                                  mask_dc00dc00); // lo surr: 1101110000000000, other:  0000000000000000
+    __m512i shifted4_thirdsecondandlastbytes = _mm512_srli_epi16(thirdsecondandlastbytes,
+                                                                 4); // hi surr: 00000WVUTSRQPNML  vuts = WVUTS - 1
+    __m512i tagged_lo_surrogates = _mm512_or_si512(thirdsecondandlastbytes,
+                                                   lo_surr_mask); // lo surr: 110111KJHGFEDCBA, other:  unchanged
+    __m512i Wout = _mm512_mask_add_epi16(tagged_lo_surrogates, Mhi, shifted4_thirdsecondandlastbytes,
+                                         mask_d7c0d7c0); // hi sur: 110110vutsRQPNML, other:  unchanged
+    // the elements of Wout excluding the last element if it happens to be a high surrogate:
+    __mmask32 Mout = ~(Mhi & 0x80000000);
+    __mmask64 mprocessed = (tail == SIMDUTF_FULL) ? _pdep_u64(Mout, mend) : _pdep_u64(Mout, _kand_mask64(mend, b)); // we adjust mend at the end of the output.
+
+    int64_t nout = _mm_popcnt_u64(mprocessed);
+    int64_t nin = 64 - _lzcnt_u64(mprocessed);
+
+    // mismatched continuation bytes:
+    __mmask64 bxorm1234 = _kxor_mask64(b, m1234);
+    if (mc != bxorm1234) { return false; }
+    // Encodings out of range...
+    {
+      // the location of 3-byte sequence start bytes in the input
+      __mmask64 m3 = m34 & (b ^ m4);
+      // words in Wout corresponding to 3-byte sequences.
+      __mmask32 M3 = __mmask32(_pext_u64(m3 << 2, mend));
+      __m512i mask_08000800 = _mm512_set1_epi32(0x08000800);
+      __mmask32 Msmall800 = _mm512_mask_cmplt_epu16_mask(M3, Wout, mask_08000800);
+      __m512i mask_d800d800 = _mm512_set1_epi32(0xd800d800);
+      __m512i Moutminusd800 = _mm512_sub_epi16(Wout, mask_d800d800);
+      __mmask32 M3s = _mm512_mask_cmplt_epu16_mask(M3, Moutminusd800, mask_08000800);
+      __m512i mask_04000400 = _mm512_set1_epi32(0x04000400);
+      __mmask32 M4s = _mm512_mask_cmpge_epu16_mask(Mhi, Moutminusd800, mask_04000400);
+      if (!_kortestz_mask32_u8(M4s, _kor_mask32(Msmall800, M3s))) { return false; }
+    }
+    if(big_endian) { Wout = _mm512_shuffle_epi8(Wout, byteflip); }
+    _mm512_mask_storeu_epi16(out, __mmask32((uint64_t(1) << nout) - 1), Wout);
+    out += nout;
+    in += nin;
+    return true; // ok
+  }
+  // Fast path 2: all ASCII or 2 byte
+  // on top of -0xc0 we substract -2 which we get back later of the
+  // continuation byte tags
+  __m512i leading2byte = _mm512_maskz_sub_epi8(m234, input, mask_c2c2c2c2);
+  __mmask64 leading = tail == (tail == SIMDUTF_FULL) ? _kor_mask64(m1, m234) : _kand_mask64(_kor_mask64(m1, m234), b); // first bytes of each sequence
+  __mmask64 continuation_or_ascii = (tail == SIMDUTF_FULL) ? _knot_mask64(m234) : _kand_mask64(_knot_mask64(m234), b);
+  __mmask64 bxorleading = _kxor_mask64(b, leading);
+  if (_kshiftli_mask64(m234, 1) != bxorleading) { return false; }
+  __m512i lead = _mm512_maskz_compress_epi8(leading, leading2byte);          // will contain zero for ascii, and the data
+  lead = _mm512_cvtepu8_epi16(_mm512_castsi512_si256(lead));                 // ... zero extended into words
+  __m512i follow = _mm512_maskz_compress_epi8(continuation_or_ascii, input); // the last bytes of each sequence
+  follow = _mm512_cvtepu8_epi16(_mm512_castsi512_si256(follow));             // ... zero extended into words
+  lead = _mm512_slli_epi16(lead, 6);                                         // shifted into position
+  __m512i final = _mm512_add_epi16(follow, lead);                            // combining lead and follow
+  int64_t nout, nin;
+  if (tail == SIMDUTF_FULL) {
+    // Next part is UTF-16 specific and can be generalized to UTF-32.
+    if(big_endian) { final = _mm512_shuffle_epi8(final, byteflip); }
+    _mm512_storeu_si512(out, final);
+    nout = 32;
+    nin = 64 - _lzcnt_u64(_pdep_u64(0xFFFFFFFF, continuation_or_ascii));
+  } else {
+    nout = _mm_popcnt_u64(_pdep_u64(0xFFFFFFFF, leading));
+    nin = 64 - _lzcnt_u64(_pdep_u64(0xFFFFFFFF, continuation_or_ascii));
+    if(big_endian) { final = _mm512_shuffle_epi8(final, byteflip); }
+    _mm512_mask_storeu_epi16(out, __mmask32((uint64_t(1) << nout) - 1), final);
+  }
+  out += nout; // UTF-8 to UTF-16 is only expansionary in this case.
+  // computing the consumed input is more fun:
+  in += nin;
+  return true; // we are fine.
+}
+
+
+
+
+/*
+    utf32_to_utf16_masked converts `count` lower UTF-32 words
+    from input `utf32` into UTF-16. It differs from utf32_to_utf16
+    in that it 'masks' the writes.
+
+    Returns how many 16-bit words were stored.
+
+    byteflip is used for flipping 16-bit words, and it should be
+        __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+    We pass it to the (always inlined) function to encourage the compiler to
+    keep the value in a (constant) register.
+*/
+template <endianness big_endian>
+simdutf_really_inline size_t utf32_to_utf16_masked(const __m512i byteflip, __m512i utf32, unsigned int count, char16_t* output) {
+
+    const __mmask16 valid = uint16_t((1 << count) - 1);
+    // 1. check if we have any surrogate pairs
+    const __m512i v_0000_ffff = _mm512_set1_epi32(0x0000ffff);
+    const __mmask16 sp_mask = _mm512_mask_cmpgt_epu32_mask(valid, utf32, v_0000_ffff);
+
+    if (sp_mask == 0) {
+        if(big_endian) {
+          _mm256_mask_storeu_epi16((__m256i*)output, valid, _mm256_shuffle_epi8(_mm512_cvtepi32_epi16(utf32), _mm512_castsi512_si256(byteflip)));
+
+        } else {
+          _mm256_mask_storeu_epi16((__m256i*)output, valid, _mm512_cvtepi32_epi16(utf32));
+        }
+        return count;
+    }
+
+    {
+        // build surrogate pair words in 32-bit lanes
+
+        //    t0 = 8 x [000000000000aaaa|aaaaaabbbbbbbbbb]
+        const __m512i v_0001_0000 = _mm512_set1_epi32(0x00010000);
+        const __m512i t0 = _mm512_sub_epi32(utf32, v_0001_0000);
+
+        //    t1 = 8 x [000000aaaaaaaaaa|bbbbbbbbbb000000]
+        const __m512i t1 = _mm512_slli_epi32(t0, 6);
+
+        //    t2 = 8 x [000000aaaaaaaaaa|aaaaaabbbbbbbbbb] -- copy hi word from t1 to t0
+        //         0xe4 = (t1 and v_ffff_0000) or (t0 and not v_ffff_0000)
+        const __m512i v_ffff_0000 = _mm512_set1_epi32(0xffff0000);
+        const __m512i t2 = _mm512_ternarylogic_epi32(t1, t0, v_ffff_0000, 0xe4);
+
+        //    t2 = 8 x [110110aaaaaaaaaa|110111bbbbbbbbbb] -- copy hi word from t1 to t0
+        //         0xba = (t2 and not v_fc00_fc000) or v_d800_dc00
+        const __m512i v_fc00_fc00 = _mm512_set1_epi32(0xfc00fc00);
+        const __m512i v_d800_dc00 = _mm512_set1_epi32(0xd800dc00);
+        const __m512i t3 = _mm512_ternarylogic_epi32(t2, v_fc00_fc00, v_d800_dc00, 0xba);
+        const __m512i t4 = _mm512_mask_blend_epi32(sp_mask, utf32, t3);
+        __m512i t5 = _mm512_ror_epi32(t4, 16);
+        // Here we want to trim all of the upper 16-bit words from the 2-byte
+        // characters represented as 4-byte values. We can compute it from
+        // sp_mask or the following... It can be more optimized!
+        const  __mmask32 nonzero = _kor_mask32(0xaaaaaaaa,_mm512_cmpneq_epi16_mask(t5, _mm512_setzero_si512()));
+        const  __mmask32 nonzero_masked = _kand_mask32(nonzero, __mmask32((uint64_t(1) << (2*count)) - 1));
+        if(big_endian) { t5 = _mm512_shuffle_epi8(t5, byteflip); }
+        // we deliberately avoid _mm512_mask_compressstoreu_epi16 for portability (zen4)
+        __m512i compressed = _mm512_maskz_compress_epi16(nonzero_masked, t5);
+        _mm512_mask_storeu_epi16(output, (1<<(count + static_cast<unsigned int>(count_ones(sp_mask)))) - 1, compressed);
+        //_mm512_mask_compressstoreu_epi16(output, nonzero_masked, t5);
+    }
+
+    return count + static_cast<unsigned int>(count_ones(sp_mask));
+}
+
+/*
+    utf32_to_utf16 converts `count` lower UTF-32 words
+    from input `utf32` into UTF-16. It may overflow.
+
+    Returns how many 16-bit words were stored.
+
+    byteflip is used for flipping 16-bit words, and it should be
+        __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+    We pass it to the (always inlined) function to encourage the compiler to
+    keep the value in a (constant) register.
+*/
+template <endianness big_endian>
+simdutf_really_inline size_t utf32_to_utf16(const __m512i byteflip, __m512i utf32, unsigned int count, char16_t* output) {
+    // check if we have any surrogate pairs
+    const __m512i v_0000_ffff = _mm512_set1_epi32(0x0000ffff);
+    const __mmask16 sp_mask = _mm512_cmpgt_epu32_mask(utf32, v_0000_ffff);
+
+    if (sp_mask == 0) {
+        // technically, it should be _mm256_storeu_epi16
+        if(big_endian) {
+          _mm256_storeu_si256((__m256i*)output, _mm256_shuffle_epi8(_mm512_cvtepi32_epi16(utf32),_mm512_castsi512_si256(byteflip)));
+        } else {
+          _mm256_storeu_si256((__m256i*)output, _mm512_cvtepi32_epi16(utf32));
+        }
+        return count;
+    }
+
+    {
+        // build surrogate pair words in 32-bit lanes
+
+        //    t0 = 8 x [000000000000aaaa|aaaaaabbbbbbbbbb]
+        const __m512i v_0001_0000 = _mm512_set1_epi32(0x00010000);
+        const __m512i t0 = _mm512_sub_epi32(utf32, v_0001_0000);
+
+        //    t1 = 8 x [000000aaaaaaaaaa|bbbbbbbbbb000000]
+        const __m512i t1 = _mm512_slli_epi32(t0, 6);
+
+        //    t2 = 8 x [000000aaaaaaaaaa|aaaaaabbbbbbbbbb] -- copy hi word from t1 to t0
+        //         0xe4 = (t1 and v_ffff_0000) or (t0 and not v_ffff_0000)
+        const __m512i v_ffff_0000 = _mm512_set1_epi32(0xffff0000);
+        const __m512i t2 = _mm512_ternarylogic_epi32(t1, t0, v_ffff_0000, 0xe4);
+
+        //    t2 = 8 x [110110aaaaaaaaaa|110111bbbbbbbbbb] -- copy hi word from t1 to t0
+        //         0xba = (t2 and not v_fc00_fc000) or v_d800_dc00
+        const __m512i v_fc00_fc00 = _mm512_set1_epi32(0xfc00fc00);
+        const __m512i v_d800_dc00 = _mm512_set1_epi32(0xd800dc00);
+        const __m512i t3 = _mm512_ternarylogic_epi32(t2, v_fc00_fc00, v_d800_dc00, 0xba);
+        const __m512i t4 = _mm512_mask_blend_epi32(sp_mask, utf32, t3);
+        __m512i t5 = _mm512_ror_epi32(t4, 16);
+        const  __mmask32 nonzero = _kor_mask32(0xaaaaaaaa,_mm512_cmpneq_epi16_mask(t5, _mm512_setzero_si512()));
+        if(big_endian) { t5 = _mm512_shuffle_epi8(t5, byteflip); }
+        // we deliberately avoid _mm512_mask_compressstoreu_epi16 for portability (zen4)
+        __m512i compressed = _mm512_maskz_compress_epi16(nonzero, t5);
+        _mm512_mask_storeu_epi16(output, (1<<(count + static_cast<unsigned int>(count_ones(sp_mask)))) - 1, compressed);
+        //_mm512_mask_compressstoreu_epi16(output, nonzero, t5);
+    }
+
+    return count + static_cast<unsigned int>(count_ones(sp_mask));
+}
+
+/**
+ * Store the last N bytes of previous followed by 512-N bytes from input.
+ */
+template <int N>
+__m512i prev(__m512i input, __m512i previous) {
+    static_assert(N<=32, "N must be no larger than 32");
+    const __m512i movemask = _mm512_setr_epi32(28,29,30,31,0,1,2,3,4,5,6,7,8,9,10,11);
+    const __m512i rotated = _mm512_permutex2var_epi32(input, movemask, previous);
+#if SIMDUTF_GCC8
+    constexpr int shift = 16-N; // workaround for GCC8
+    return _mm512_alignr_epi8(input, rotated, shift);
+#else
+    return _mm512_alignr_epi8(input, rotated, 16-N);
+#endif // SIMDUTF_GCC8
+}
+
+template <unsigned idx0, unsigned idx1, unsigned idx2, unsigned idx3>
+__m512i shuffle_epi128(__m512i v) {
+    static_assert((idx0 >= 0 && idx0 <= 3), "idx0 must be in range 0..3");
+    static_assert((idx1 >= 0 && idx1 <= 3), "idx1 must be in range 0..3");
+    static_assert((idx2 >= 0 && idx2 <= 3), "idx2 must be in range 0..3");
+    static_assert((idx3 >= 0 && idx3 <= 3), "idx3 must be in range 0..3");
+
+    constexpr unsigned shuffle = idx0 | (idx1 << 2) | (idx2 << 4) | (idx3 << 6);
+    return _mm512_shuffle_i32x4(v, v, shuffle);
+}
+
+template <unsigned idx>
+constexpr __m512i broadcast_epi128(__m512i v) {
+    return shuffle_epi128<idx, idx, idx, idx>(v);
+}
+
+/**
+ * Current unused.
+ */
+template <int N>
+__m512i rotate_by_N_epi8(const __m512i input) {
+
+    // lanes order: 1, 2, 3, 0 => 0b00_11_10_01
+    const __m512i permuted = _mm512_shuffle_i32x4(input, input, 0x39);
+
+    return _mm512_alignr_epi8(permuted, input, N);
+}
+
+/*
+    expanded_utf8_to_utf32 converts expanded UTF-8 characters (`utf8`)
+    stored at separate 32-bit lanes.
+
+    For each lane we have also a character class (`char_class), given in form
+    0x8080800N, where N is 4 higest bits from the leading byte; 0x80 resets
+    corresponding bytes during pshufb.
+*/
+simdutf_really_inline __m512i expanded_utf8_to_utf32(__m512i char_class, __m512i utf8) {
+    /*
+        Input:
+        - utf8: bytes stored at separate 32-bit words
+        - valid: which words have valid UTF-8 characters
+
+        Bit layout of single word. We show 4 cases for each possible
+        UTF-8 character encoding. The `?` denotes bits we must not
+        assume their value.
+
+        |10dd.dddd|10cc.cccc|10bb.bbbb|1111.0aaa| 4-byte char
+        |????.????|10cc.cccc|10bb.bbbb|1110.aaaa| 3-byte char
+        |????.????|????.????|10bb.bbbb|110a.aaaa| 2-byte char
+        |????.????|????.????|????.????|0aaa.aaaa| ASCII char
+          byte 3    byte 2    byte 1     byte 0
+    */
+
+    /* 1. Reset control bits of continuation bytes and the MSB
+          of the leading byte; this makes all bytes unsigned (and
+          does not alter ASCII char).
+
+        |00dd.dddd|00cc.cccc|00bb.bbbb|0111.0aaa| 4-byte char
+        |00??.????|00cc.cccc|00bb.bbbb|0110.aaaa| 3-byte char
+        |00??.????|00??.????|00bb.bbbb|010a.aaaa| 2-byte char
+        |00??.????|00??.????|00??.????|0aaa.aaaa| ASCII char
+         ^^        ^^        ^^        ^
+    */
+    __m512i values;
+    const __m512i v_3f3f_3f7f = _mm512_set1_epi32(0x3f3f3f7f);
+    values = _mm512_and_si512(utf8, v_3f3f_3f7f);
+
+    /* 2. Swap and join fields A-B and C-D
+
+        |0000.cccc|ccdd.dddd|0001.110a|aabb.bbbb| 4-byte char
+        |0000.cccc|cc??.????|0001.10aa|aabb.bbbb| 3-byte char
+        |0000.????|????.????|0001.0aaa|aabb.bbbb| 2-byte char
+        |0000.????|????.????|000a.aaaa|aa??.????| ASCII char */
+    const __m512i v_0140_0140 = _mm512_set1_epi32(0x01400140);
+    values = _mm512_maddubs_epi16(values, v_0140_0140);
+
+    /* 3. Swap and join fields AB & CD
+
+        |0000.0001|110a.aabb|bbbb.cccc|ccdd.dddd| 4-byte char
+        |0000.0001|10aa.aabb|bbbb.cccc|cc??.????| 3-byte char
+        |0000.0001|0aaa.aabb|bbbb.????|????.????| 2-byte char
+        |0000.000a|aaaa.aa??|????.????|????.????| ASCII char */
+    const __m512i v_0001_1000 = _mm512_set1_epi32(0x00011000);
+    values = _mm512_madd_epi16(values, v_0001_1000);
+
+    /* 4. Shift left the values by variable amounts to reset highest UTF-8 bits
+        |aaab.bbbb|bccc.cccd|dddd.d000|0000.0000| 4-byte char -- by 11
+        |aaaa.bbbb|bbcc.cccc|????.??00|0000.0000| 3-byte char -- by 10
+        |aaaa.abbb|bbb?.????|????.???0|0000.0000| 2-byte char -- by 9
+        |aaaa.aaa?|????.????|????.????|?000.0000| ASCII char -- by 7 */
+    {
+        /** pshufb
+
+        continuation = 0
+        ascii    = 7
+        _2_bytes = 9
+        _3_bytes = 10
+        _4_bytes = 11
+
+        shift_left_v3 = 4 * [
+            ascii, # 0000
+            ascii, # 0001
+            ascii, # 0010
+            ascii, # 0011
+            ascii, # 0100
+            ascii, # 0101
+            ascii, # 0110
+            ascii, # 0111
+            continuation, # 1000
+            continuation, # 1001
+            continuation, # 1010
+            continuation, # 1011
+            _2_bytes, # 1100
+            _2_bytes, # 1101
+            _3_bytes, # 1110
+            _4_bytes, # 1111
+        ] */
+        const __m512i shift_left_v3 = _mm512_setr_epi64(
+            0x0707070707070707,
+            0x0b0a090900000000,
+            0x0707070707070707,
+            0x0b0a090900000000,
+            0x0707070707070707,
+            0x0b0a090900000000,
+            0x0707070707070707,
+            0x0b0a090900000000
+        );
+
+        const __m512i shift = _mm512_shuffle_epi8(shift_left_v3, char_class);
+        values = _mm512_sllv_epi32(values, shift);
+    }
+
+    /* 5. Shift right the values by variable amounts to reset lowest bits
+        |0000.0000|000a.aabb|bbbb.cccc|ccdd.dddd| 4-byte char -- by 11
+        |0000.0000|0000.0000|aaaa.bbbb|bbcc.cccc| 3-byte char -- by 16
+        |0000.0000|0000.0000|0000.0aaa|aabb.bbbb| 2-byte char -- by 21
+        |0000.0000|0000.0000|0000.0000|0aaa.aaaa| ASCII char -- by 25 */
+    {
+        // 4 * [25, 25, 25, 25, 25, 25, 25, 25, 0, 0, 0, 0, 21, 21, 16, 11]
+        const __m512i shift_right = _mm512_setr_epi64(
+            0x1919191919191919,
+            0x0b10151500000000,
+            0x1919191919191919,
+            0x0b10151500000000,
+            0x1919191919191919,
+            0x0b10151500000000,
+            0x1919191919191919,
+            0x0b10151500000000
+        );
+
+        const __m512i shift = _mm512_shuffle_epi8(shift_right, char_class);
+        values = _mm512_srlv_epi32(values, shift);
+    }
+
+    return values;
+}
+
+
+simdutf_really_inline __m512i expand_and_identify(__m512i lane0, __m512i lane1, int &count) {
+    const __m512i merged = _mm512_mask_mov_epi32(lane0, 0x1000, lane1);
+    const __m512i expand_ver2 = _mm512_setr_epi64(
+                0x0403020103020100,
+                0x0605040305040302,
+                0x0807060507060504,
+                0x0a09080709080706,
+                0x0c0b0a090b0a0908,
+                0x0e0d0c0b0d0c0b0a,
+                0x000f0e0d0f0e0d0c,
+                0x0201000f01000f0e
+    );
+    const __m512i input = _mm512_shuffle_epi8(merged, expand_ver2);
+    const __m512i v_0000_00c0 = _mm512_set1_epi32(0xc0);
+    const __m512i t0 = _mm512_and_si512(input, v_0000_00c0);
+    const __m512i v_0000_0080 = _mm512_set1_epi32(0x80);
+    const __mmask16 leading_bytes = _mm512_cmpneq_epu32_mask(t0, v_0000_0080);
+    count = static_cast<int>(count_ones(leading_bytes));
+    return  _mm512_mask_compress_epi32(_mm512_setzero_si512(), leading_bytes, input);
+}
+
+simdutf_really_inline __m512i expand_utf8_to_utf32(__m512i input) {
+    __m512i char_class = _mm512_srli_epi32(input, 4);
+    /*  char_class = ((input >> 4) & 0x0f) | 0x80808000 */
+    const __m512i v_0000_000f = _mm512_set1_epi32(0x0f);
+    const __m512i v_8080_8000 = _mm512_set1_epi32(0x80808000);
+    char_class = _mm512_ternarylogic_epi32(char_class, v_0000_000f, v_8080_8000, 0xea);
+    return expanded_utf8_to_utf32(char_class, input);
+}
+/* end file src/icelake/icelake_utf8_common.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_macros.inl.cpp
+/* begin file src/icelake/icelake_macros.inl.cpp */
+
+/*
+    This upcoming macro (SIMDUTF_ICELAKE_TRANSCODE16) takes 16 + 4 bytes (of a UTF-8 string)
+    and loads all possible 4-byte substring into an AVX512 register.
+
+    For example if we have bytes abcdefgh... we create following 32-bit lanes
+
+    [abcd|bcde|cdef|defg|efgh|...]
+     ^                          ^
+     byte 0 of reg              byte 63 of reg
+*/
+/** pshufb
+        # lane{0,1,2} have got bytes: [  0,  1,  2,  3,  4,  5,  6,  8,  9, 10, 11, 12, 13, 14, 15]
+        # lane3 has got bytes:        [ 16, 17, 18, 19,  4,  5,  6,  8,  9, 10, 11, 12, 13, 14, 15]
+
+        expand_ver2 = [
+            # lane 0:
+            0, 1, 2, 3,
+            1, 2, 3, 4,
+            2, 3, 4, 5,
+            3, 4, 5, 6,
+
+            # lane 1:
+            4, 5, 6, 7,
+            5, 6, 7, 8,
+            6, 7, 8, 9,
+            7, 8, 9, 10,
+
+            # lane 2:
+             8,  9, 10, 11,
+             9, 10, 11, 12,
+            10, 11, 12, 13,
+            11, 12, 13, 14,
+
+            # lane 3 order: 13, 14, 15, 16 14, 15, 16, 17, 15, 16, 17, 18, 16, 17, 18, 19
+            12, 13, 14, 15,
+            13, 14, 15,  0,
+            14, 15,  0,  1,
+            15,  0,  1,  2,
+        ]
+*/
+
+#define SIMDUTF_ICELAKE_TRANSCODE16(LANE0, LANE1, MASKED)                                                    \
+        {                                                                                                    \
+            const __m512i merged = _mm512_mask_mov_epi32(LANE0, 0x1000, LANE1);                              \
+            const __m512i expand_ver2 = _mm512_setr_epi64(                                                   \
+                0x0403020103020100,                                                                          \
+                0x0605040305040302,                                                                          \
+                0x0807060507060504,                                                                          \
+                0x0a09080709080706,                                                                          \
+                0x0c0b0a090b0a0908,                                                                          \
+                0x0e0d0c0b0d0c0b0a,                                                                          \
+                0x000f0e0d0f0e0d0c,                                                                          \
+                0x0201000f01000f0e                                                                           \
+            );                                                                                               \
+            const __m512i input = _mm512_shuffle_epi8(merged, expand_ver2);                                  \
+                                                                                                             \
+            __mmask16 leading_bytes;                                                                         \
+            const __m512i v_0000_00c0 = _mm512_set1_epi32(0xc0);                                             \
+            const __m512i t0 = _mm512_and_si512(input, v_0000_00c0);                                         \
+            const __m512i v_0000_0080 = _mm512_set1_epi32(0x80);                                             \
+            leading_bytes = _mm512_cmpneq_epu32_mask(t0, v_0000_0080);                                       \
+                                                                                                             \
+            __m512i char_class;                                                                              \
+            char_class = _mm512_srli_epi32(input, 4);                                                        \
+            /*  char_class = ((input >> 4) & 0x0f) | 0x80808000 */                                           \
+            const __m512i v_0000_000f = _mm512_set1_epi32(0x0f);                                             \
+            const __m512i v_8080_8000 = _mm512_set1_epi32(0x80808000);                                       \
+            char_class = _mm512_ternarylogic_epi32(char_class, v_0000_000f, v_8080_8000, 0xea);              \
+                                                                                                             \
+            const int valid_count = static_cast<int>(count_ones(leading_bytes));                             \
+            const __m512i utf32 = expanded_utf8_to_utf32(char_class, input);                                 \
+                                                                                                             \
+            const __m512i out = _mm512_mask_compress_epi32(_mm512_setzero_si512(), leading_bytes, utf32);    \
+                                                                                                             \
+            if (UTF32) {                                                                                     \
+                if(MASKED) {                                                                                 \
+                    const __mmask16 valid = uint16_t((1 << valid_count) - 1);                                \
+                    _mm512_mask_storeu_epi32((__m512i*)output, valid, out);                                  \
+                } else {                                                                                     \
+                    _mm512_storeu_si512((__m512i*)output, out);                                              \
+                }                                                                                            \
+                output += valid_count;                                                                       \
+            } else {                                                                                         \
+                if(MASKED) {                                                                                 \
+                    output += utf32_to_utf16_masked<big_endian>(byteflip, out, valid_count, reinterpret_cast<char16_t *>(output)); \
+                } else {                                                                                     \
+                    output += utf32_to_utf16<big_endian>(byteflip, out, valid_count, reinterpret_cast<char16_t *>(output));        \
+                }                                                                                            \
+            }                                                                                                \
+        }
+
+#define SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(INPUT, VALID_COUNT, MASKED)                                    \
+{                                                                                                           \
+    if (UTF32) {                                                                                            \
+        if(MASKED) {                                                                                        \
+            const __mmask16 valid_mask = uint16_t((1 << VALID_COUNT) - 1);                                  \
+            _mm512_mask_storeu_epi32((__m512i*)output, valid_mask, INPUT);                                  \
+        } else {                                                                                            \
+            _mm512_storeu_si512((__m512i*)output, INPUT);                                              \
+        }                                                                                                   \
+        output += VALID_COUNT;                                                                              \
+    } else {                                                                                                \
+        if(MASKED) {                                                                                        \
+            output += utf32_to_utf16_masked<big_endian>(byteflip, INPUT, VALID_COUNT, reinterpret_cast<char16_t *>(output));      \
+        } else {                                                                                            \
+            output += utf32_to_utf16<big_endian>(byteflip, INPUT, VALID_COUNT, reinterpret_cast<char16_t *>(output));             \
+        }                                                                                                   \
+    }                                                                                                       \
+}
+
+
+#define SIMDUTF_ICELAKE_STORE_ASCII(UTF32, utf8, output)                                  \
+        if (UTF32) {                                                                      \
+                const __m128i t0 = _mm512_castsi512_si128(utf8);                          \
+                const __m128i t1 = _mm512_extracti32x4_epi32(utf8, 1);                    \
+                const __m128i t2 = _mm512_extracti32x4_epi32(utf8, 2);                    \
+                const __m128i t3 = _mm512_extracti32x4_epi32(utf8, 3);                    \
+                _mm512_storeu_si512((__m512i*)(output + 0*16), _mm512_cvtepu8_epi32(t0)); \
+                _mm512_storeu_si512((__m512i*)(output + 1*16), _mm512_cvtepu8_epi32(t1)); \
+                _mm512_storeu_si512((__m512i*)(output + 2*16), _mm512_cvtepu8_epi32(t2)); \
+                _mm512_storeu_si512((__m512i*)(output + 3*16), _mm512_cvtepu8_epi32(t3)); \
+        } else {                                                                          \
+                const __m256i h0 = _mm512_castsi512_si256(utf8);                          \
+                const __m256i h1 = _mm512_extracti64x4_epi64(utf8, 1);                    \
+                if(big_endian) {                                                          \
+                _mm512_storeu_si512((__m512i*)(output + 0*16), _mm512_shuffle_epi8(_mm512_cvtepu8_epi16(h0), byteflip)); \
+                _mm512_storeu_si512((__m512i*)(output + 2*16), _mm512_shuffle_epi8(_mm512_cvtepu8_epi16(h1), byteflip)); \
+                } else {                                                                  \
+                _mm512_storeu_si512((__m512i*)(output + 0*16), _mm512_cvtepu8_epi16(h0)); \
+                _mm512_storeu_si512((__m512i*)(output + 2*16), _mm512_cvtepu8_epi16(h1)); \
+                }                                                                         \
+        }
+/* end file src/icelake/icelake_macros.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_from_valid_utf8.inl.cpp
+/* begin file src/icelake/icelake_from_valid_utf8.inl.cpp */
+// file included directly
+
+// File contains conversion procedure from VALID UTF-8 strings.
+
+/*
+    valid_utf8_to_fixed_length converts a valid UTF-8 string into UTF-32.
+
+    The `OUTPUT` template type decides what to do with UTF-32: store
+    it directly or convert into UTF-16 (with AVX512).
+
+    Input:
+    - str           - valid UTF-8 string
+    - len           - string length
+    - out_buffer    - output buffer
+
+    Result:
+    - pair.first    - the first unprocessed input byte
+    - pair.second   - the first unprocessed output word
+*/
+template <endianness big_endian, typename OUTPUT>
+std::pair<const char*, OUTPUT*> valid_utf8_to_fixed_length(const char* str, size_t len, OUTPUT* dwords) {
+    constexpr bool UTF32 = std::is_same<OUTPUT, uint32_t>::value;
+    constexpr bool UTF16 = std::is_same<OUTPUT, char16_t>::value;
+    static_assert(UTF32 or UTF16, "output type has to be uint32_t (for UTF-32) or char16_t (for UTF-16)");
+    static_assert(!(UTF32 and big_endian), "we do not currently support big-endian UTF-32");
+
+    __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+    const char* ptr = str;
+    const char* end = ptr + len;
+
+    OUTPUT* output = dwords;
+    /**
+     * In the main loop, we consume 64 bytes per iteration,
+     * but we access 64 + 4 bytes.
+     * We check for ptr + 64 + 64 <= end because
+     * we want to be do maskless writes without overruns.
+     */
+    while (ptr + 64 + 64 <= end) {
+        const __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+        const __m512i v_80 = _mm512_set1_epi8(char(0x80));
+        const __mmask64 ascii = _mm512_test_epi8_mask(utf8, v_80);
+        if(ascii == 0) {
+            SIMDUTF_ICELAKE_STORE_ASCII(UTF32, utf8, output)
+            output += 64;
+            ptr += 64;
+            continue;
+        }
+
+        const __m512i lane0 = broadcast_epi128<0>(utf8);
+        const __m512i lane1 = broadcast_epi128<1>(utf8);
+        int valid_count0;
+        __m512i vec0 = expand_and_identify(lane0, lane1, valid_count0);
+        const __m512i lane2 = broadcast_epi128<2>(utf8);
+        int valid_count1;
+        __m512i vec1 = expand_and_identify(lane1, lane2, valid_count1);
+        if(valid_count0 + valid_count1 <= 16) {
+            vec0 = _mm512_mask_expand_epi32(vec0, __mmask16(((1<<valid_count1)-1)<<valid_count0), vec1);
+            valid_count0 += valid_count1;
+            vec0 = expand_utf8_to_utf32(vec0);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, false)
+        } else {
+            vec0 = expand_utf8_to_utf32(vec0);
+            vec1 = expand_utf8_to_utf32(vec1);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, false)
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec1, valid_count1, false)
+        }
+        const __m512i lane3 = broadcast_epi128<3>(utf8);
+        int valid_count2;
+        __m512i vec2 = expand_and_identify(lane2, lane3, valid_count2);
+        uint32_t tmp1;
+        ::memcpy(&tmp1, ptr + 64, sizeof(tmp1));
+        const __m512i lane4 = _mm512_set1_epi32(tmp1);
+        int valid_count3;
+        __m512i vec3 = expand_and_identify(lane3, lane4, valid_count3);
+        if(valid_count2 + valid_count3 <= 16) {
+            vec2 = _mm512_mask_expand_epi32(vec2, __mmask16(((1<<valid_count3)-1)<<valid_count2), vec3);
+            valid_count2 += valid_count3;
+            vec2 = expand_utf8_to_utf32(vec2);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec2, valid_count2, false)
+        } else {
+            vec2 = expand_utf8_to_utf32(vec2);
+            vec3 = expand_utf8_to_utf32(vec3);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec2, valid_count2, false)
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec3, valid_count3, false)
+        }
+        ptr += 4*16;
+    }
+
+    if (ptr + 64 <= end) {
+        const __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+        const __m512i v_80 = _mm512_set1_epi8(char(0x80));
+        const __mmask64 ascii = _mm512_test_epi8_mask(utf8, v_80);
+        if(ascii == 0) {
+            SIMDUTF_ICELAKE_STORE_ASCII(UTF32, utf8, output)
+            output += 64;
+            ptr += 64;
+        } else {
+            const __m512i lane0 = broadcast_epi128<0>(utf8);
+            const __m512i lane1 = broadcast_epi128<1>(utf8);
+            int valid_count0;
+            __m512i vec0 = expand_and_identify(lane0, lane1, valid_count0);
+            const __m512i lane2 = broadcast_epi128<2>(utf8);
+            int valid_count1;
+            __m512i vec1 = expand_and_identify(lane1, lane2, valid_count1);
+            if(valid_count0 + valid_count1 <= 16) {
+                vec0 = _mm512_mask_expand_epi32(vec0, __mmask16(((1<<valid_count1)-1)<<valid_count0), vec1);
+                valid_count0 += valid_count1;
+                vec0 = expand_utf8_to_utf32(vec0);
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, true)
+            } else {
+                vec0 = expand_utf8_to_utf32(vec0);
+                vec1 = expand_utf8_to_utf32(vec1);
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, true)
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec1, valid_count1, true)
+            }
+
+            const __m512i lane3 = broadcast_epi128<3>(utf8);
+            SIMDUTF_ICELAKE_TRANSCODE16(lane2, lane3, true)
+
+            ptr += 3*16;
+        }
+    }
+    return {ptr, output};
+}
+
+
+using utf8_to_utf16_result = std::pair<const char*, char16_t*>;
+/* end file src/icelake/icelake_from_valid_utf8.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_utf8_validation.inl.cpp
+/* begin file src/icelake/icelake_utf8_validation.inl.cpp */
+// file included directly
+
+
+simdutf_really_inline __m512i check_special_cases(__m512i input, const __m512i prev1) {
+  __m512i mask1 = _mm512_setr_epi64(
+        0x0202020202020202,
+        0x4915012180808080,
+        0x0202020202020202,
+        0x4915012180808080,
+        0x0202020202020202,
+        0x4915012180808080,
+        0x0202020202020202,
+        0x4915012180808080);
+    const __m512i v_0f = _mm512_set1_epi8(0x0f);
+    __m512i index1 = _mm512_and_si512(_mm512_srli_epi16(prev1, 4), v_0f);
+
+    __m512i byte_1_high = _mm512_shuffle_epi8(mask1, index1);
+    __m512i mask2 = _mm512_setr_epi64(
+        0xcbcbcb8b8383a3e7,
+        0xcbcbdbcbcbcbcbcb,
+        0xcbcbcb8b8383a3e7,
+        0xcbcbdbcbcbcbcbcb,
+        0xcbcbcb8b8383a3e7,
+        0xcbcbdbcbcbcbcbcb,
+        0xcbcbcb8b8383a3e7,
+        0xcbcbdbcbcbcbcbcb);
+     __m512i index2 = _mm512_and_si512(prev1, v_0f);
+
+    __m512i byte_1_low = _mm512_shuffle_epi8(mask2, index2);
+    __m512i mask3 = _mm512_setr_epi64(
+        0x101010101010101,
+        0x1010101babaaee6,
+        0x101010101010101,
+        0x1010101babaaee6,
+        0x101010101010101,
+        0x1010101babaaee6,
+        0x101010101010101,
+        0x1010101babaaee6
+    );
+    __m512i index3 = _mm512_and_si512(_mm512_srli_epi16(input, 4), v_0f);
+    __m512i byte_2_high = _mm512_shuffle_epi8(mask3, index3);
+    return _mm512_ternarylogic_epi64(byte_1_high, byte_1_low, byte_2_high, 128);
+  }
+
+  simdutf_really_inline __m512i check_multibyte_lengths(const __m512i input,
+      const __m512i prev_input, const __m512i sc) {
+    __m512i prev2 = prev<2>(input, prev_input);
+    __m512i prev3 = prev<3>(input, prev_input);
+    __m512i is_third_byte  = _mm512_subs_epu8(prev2, _mm512_set1_epi8(0b11100000u-1)); // Only 111_____ will be > 0
+    __m512i is_fourth_byte  = _mm512_subs_epu8(prev3, _mm512_set1_epi8(0b11110000u-1)); // Only 1111____ will be > 0
+    __m512i is_third_or_fourth_byte = _mm512_or_si512(is_third_byte, is_fourth_byte);
+    const __m512i v_7f = _mm512_set1_epi8(char(0x7f));
+    is_third_or_fourth_byte = _mm512_adds_epu8(v_7f, is_third_or_fourth_byte);
+    // We want to compute (is_third_or_fourth_byte AND v80) XOR sc.
+    const __m512i v_80 = _mm512_set1_epi8(char(0x80));
+    return _mm512_ternarylogic_epi32(is_third_or_fourth_byte, v_80, sc, 0b1101010);
+    //__m512i is_third_or_fourth_byte_mask = _mm512_and_si512(is_third_or_fourth_byte, v_80);
+    //return _mm512_xor_si512(is_third_or_fourth_byte_mask, sc);
+  }
+  //
+  // Return nonzero if there are incomplete multibyte characters at the end of the block:
+  // e.g. if there is a 4-byte character, but it's 3 bytes from the end.
+  //
+  simdutf_really_inline __m512i is_incomplete(const __m512i input) {
+    // If the previous input's last 3 bytes match this, they're too short (they ended at EOF):
+    // ... 1111____ 111_____ 11______
+    __m512i max_value = _mm512_setr_epi64(
+        0xffffffffffffffff,
+        0xffffffffffffffff,
+        0xffffffffffffffff,
+        0xffffffffffffffff,
+        0xffffffffffffffff,
+        0xffffffffffffffff,
+        0xffffffffffffffff,
+        0xbfdfefffffffffff);
+    return _mm512_subs_epu8(input, max_value);
+  }
+
+  struct avx512_utf8_checker {
+    // If this is nonzero, there has been a UTF-8 error.
+    __m512i error{};
+
+    // The last input we received
+    __m512i prev_input_block{};
+    // Whether the last input we received was incomplete (used for ASCII fast path)
+    __m512i prev_incomplete{};
+
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const __m512i input, const __m512i prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      __m512i prev1 = prev<1>(input, prev_input);
+      __m512i sc = check_special_cases(input, prev1);
+      this->error = _mm512_or_si512(check_multibyte_lengths(input, prev_input, sc), this->error);
+    }
+
+    // The only problem that can happen at EOF is that a multibyte character is too short
+    // or a byte value too large in the last bytes: check_special_cases only checks for bytes
+    // too large in the first of two bytes.
+    simdutf_really_inline void check_eof() {
+      // If the previous block had incomplete UTF-8 characters at the end, an ASCII block can't
+      // possibly finish them.
+      this->error = _mm512_or_si512(this->error, this->prev_incomplete);
+    }
+
+    // returns true if ASCII.
+    simdutf_really_inline bool check_next_input(const __m512i input) {
+      const __m512i v_80 = _mm512_set1_epi8(char(0x80));
+      const __mmask64 ascii = _mm512_test_epi8_mask(input, v_80);
+      if(ascii == 0) {
+        this->error = _mm512_or_si512(this->error, this->prev_incomplete);
+        return true;
+      } else {
+        this->check_utf8_bytes(input, this->prev_input_block);
+        this->prev_incomplete = is_incomplete(input);
+        this->prev_input_block = input;
+        return false;
+      }
+    }
+    // do not forget to call check_eof!
+    simdutf_really_inline bool errors() const {
+        return _mm512_test_epi8_mask(this->error, this->error) != 0;
+    }
+
+  }; // struct avx512_utf8_checker
+/* end file src/icelake/icelake_utf8_validation.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_from_utf8.inl.cpp
+/* begin file src/icelake/icelake_from_utf8.inl.cpp */
+// file included directly
+
+// File contains conversion procedure from possibly invalid UTF-8 strings.
+
+/**
+ * Attempts to convert up to len 1-byte words from in (in UTF-8 format) to
+ * out.
+ * Returns the position of the input and output after the processing is
+ * completed. Upon error, the output is set to null.
+ */
+template <endianness big_endian>
+utf8_to_utf16_result fast_avx512_convert_utf8_to_utf16(const char *in, size_t len, char16_t *out) {
+  const char *const final_in = in + len;
+  bool result = true;
+  while (result) {
+    if (in + 64 <= final_in) {
+        result = process_block_utf8_to_utf16<SIMDUTF_FULL, big_endian>(in, out, final_in - in);
+    } else if(in < final_in) {
+        result = process_block_utf8_to_utf16<SIMDUTF_TAIL, big_endian>(in, out, final_in - in);
+    } else { break; }
+  }
+  if(!result) { out = nullptr; }
+  return std::make_pair(in, out);
+}
+
+template <endianness big_endian>
+simdutf::result fast_avx512_convert_utf8_to_utf16_with_errors(const char *in, size_t len, char16_t *out) {
+  const char *const init_in = in;
+  const char16_t *const init_out = out;
+  const char *const final_in = in + len;
+  bool  result = true;
+  while (result) {
+    if (in + 64 <= final_in) {
+        result = process_block_utf8_to_utf16<SIMDUTF_FULL, big_endian>(in, out, final_in - in);
+    } else if(in < final_in) {
+        result = process_block_utf8_to_utf16<SIMDUTF_TAIL, big_endian>(in, out, final_in - in);
+    } else { break; }
+  }
+  if(!result) {
+    simdutf::result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<big_endian>(in, final_in - in, out);
+    res.count += (in - init_in);
+    return res;
+  } else {
+    return simdutf::result(error_code::SUCCESS,out - init_out);
+  }
+}
+
+
+template <endianness big_endian, typename OUTPUT>
+std::pair<const char*, OUTPUT*> validating_utf8_to_fixed_length(const char* str, size_t len, OUTPUT* dwords) {
+    constexpr bool UTF32 = std::is_same<OUTPUT, uint32_t>::value;
+    constexpr bool UTF16 = std::is_same<OUTPUT, char16_t>::value;
+    static_assert(UTF32 or UTF16, "output type has to be uint32_t (for UTF-32) or char16_t (for UTF-16)");
+    static_assert(!(UTF32 and big_endian), "we do not currently support big-endian UTF-32");
+
+    const char* ptr = str;
+    const char* end = ptr + len;
+    __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+    OUTPUT* output = dwords;
+    avx512_utf8_checker checker{};
+    /**
+     * In the main loop, we consume 64 bytes per iteration,
+     * but we access 64 + 4 bytes.
+     * We check for ptr + 64 + 64 <= end because
+     * we want to be do maskless writes without overruns.
+     */
+    while (ptr + 64 + 64 <= end) {
+        const __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+        if(checker.check_next_input(utf8)) {
+            SIMDUTF_ICELAKE_STORE_ASCII(UTF32, utf8, output)
+            output += 64;
+            ptr += 64;
+            continue;
+        }
+        const __m512i lane0 = broadcast_epi128<0>(utf8);
+        const __m512i lane1 = broadcast_epi128<1>(utf8);
+        int valid_count0;
+        __m512i vec0 = expand_and_identify(lane0, lane1, valid_count0);
+        const __m512i lane2 = broadcast_epi128<2>(utf8);
+        int valid_count1;
+        __m512i vec1 = expand_and_identify(lane1, lane2, valid_count1);
+        if(valid_count0 + valid_count1 <= 16) {
+            vec0 = _mm512_mask_expand_epi32(vec0, __mmask16(((1<<valid_count1)-1)<<valid_count0), vec1);
+            valid_count0 += valid_count1;
+            vec0 = expand_utf8_to_utf32(vec0);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, false)
+        } else {
+            vec0 = expand_utf8_to_utf32(vec0);
+            vec1 = expand_utf8_to_utf32(vec1);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, false)
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec1, valid_count1, false)
+        }
+        const __m512i lane3 = broadcast_epi128<3>(utf8);
+        int valid_count2;
+        __m512i vec2 = expand_and_identify(lane2, lane3, valid_count2);
+        uint32_t tmp1;
+        ::memcpy(&tmp1, ptr + 64, sizeof(tmp1));
+        const __m512i lane4 = _mm512_set1_epi32(tmp1);
+        int valid_count3;
+        __m512i vec3 = expand_and_identify(lane3, lane4, valid_count3);
+        if(valid_count2 + valid_count3 <= 16) {
+            vec2 = _mm512_mask_expand_epi32(vec2, __mmask16(((1<<valid_count3)-1)<<valid_count2), vec3);
+            valid_count2 += valid_count3;
+            vec2 = expand_utf8_to_utf32(vec2);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec2, valid_count2, false)
+        } else {
+            vec2 = expand_utf8_to_utf32(vec2);
+            vec3 = expand_utf8_to_utf32(vec3);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec2, valid_count2, false)
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec3, valid_count3, false)
+        }
+        ptr += 4*16;
+    }
+    const char* validatedptr = ptr; // validated up to ptr
+
+    // For the final pass, we validate 64 bytes, but we only transcode
+    // 3*16 bytes, so we may end up double-validating 16 bytes.
+    if (ptr + 64 <= end) {
+        const __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+        if(checker.check_next_input(utf8)) {
+            SIMDUTF_ICELAKE_STORE_ASCII(UTF32, utf8, output)
+            output += 64;
+            ptr += 64;
+        } else {
+            const __m512i lane0 = broadcast_epi128<0>(utf8);
+            const __m512i lane1 = broadcast_epi128<1>(utf8);
+            int valid_count0;
+            __m512i vec0 = expand_and_identify(lane0, lane1, valid_count0);
+            const __m512i lane2 = broadcast_epi128<2>(utf8);
+            int valid_count1;
+            __m512i vec1 = expand_and_identify(lane1, lane2, valid_count1);
+            if(valid_count0 + valid_count1 <= 16) {
+                vec0 = _mm512_mask_expand_epi32(vec0, __mmask16(((1<<valid_count1)-1)<<valid_count0), vec1);
+                valid_count0 += valid_count1;
+                vec0 = expand_utf8_to_utf32(vec0);
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, true)
+            } else {
+                vec0 = expand_utf8_to_utf32(vec0);
+                vec1 = expand_utf8_to_utf32(vec1);
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, true)
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec1, valid_count1, true)
+            }
+
+            const __m512i lane3 = broadcast_epi128<3>(utf8);
+            SIMDUTF_ICELAKE_TRANSCODE16(lane2, lane3, true)
+
+            ptr += 3*16;
+        }
+        validatedptr += 4*16;
+    }
+    {
+       const __m512i utf8 = _mm512_maskz_loadu_epi8((1ULL<<(end - validatedptr))-1, (const __m512i*)validatedptr);
+       checker.check_next_input(utf8);
+    }
+    checker.check_eof();
+    if(checker.errors()) {
+        return {ptr, nullptr}; // We found an error.
+    }
+    return {ptr, output};
+}
+
+// Like validating_utf8_to_fixed_length but returns as soon as an error is identified
+template <endianness big_endian, typename OUTPUT>
+std::tuple<const char*, OUTPUT*, bool> validating_utf8_to_fixed_length_with_constant_checks(const char* str, size_t len, OUTPUT* dwords) {
+    constexpr bool UTF32 = std::is_same<OUTPUT, uint32_t>::value;
+    constexpr bool UTF16 = std::is_same<OUTPUT, char16_t>::value;
+    static_assert(UTF32 or UTF16, "output type has to be uint32_t (for UTF-32) or char16_t (for UTF-16)");
+    static_assert(!(UTF32 and big_endian), "we do not currently support big-endian UTF-32");
+
+    const char* ptr = str;
+    const char* end = ptr + len;
+    __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+    OUTPUT* output = dwords;
+    avx512_utf8_checker checker{};
+    /**
+     * In the main loop, we consume 64 bytes per iteration,
+     * but we access 64 + 4 bytes.
+     * We check for ptr + 64 + 64 <= end because
+     * we want to be do maskless writes without overruns.
+     */
+    while (ptr + 64 + 64 <= end) {
+        const __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+        if(checker.check_next_input(utf8)) {
+            SIMDUTF_ICELAKE_STORE_ASCII(UTF32, utf8, output)
+            output += 64;
+            ptr += 64;
+            continue;
+        }
+        if(checker.errors()) {
+            return {ptr, output, false}; // We found an error.
+        }
+        const __m512i lane0 = broadcast_epi128<0>(utf8);
+        const __m512i lane1 = broadcast_epi128<1>(utf8);
+        int valid_count0;
+        __m512i vec0 = expand_and_identify(lane0, lane1, valid_count0);
+        const __m512i lane2 = broadcast_epi128<2>(utf8);
+        int valid_count1;
+        __m512i vec1 = expand_and_identify(lane1, lane2, valid_count1);
+        if(valid_count0 + valid_count1 <= 16) {
+            vec0 = _mm512_mask_expand_epi32(vec0, __mmask16(((1<<valid_count1)-1)<<valid_count0), vec1);
+            valid_count0 += valid_count1;
+            vec0 = expand_utf8_to_utf32(vec0);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, false)
+        } else {
+            vec0 = expand_utf8_to_utf32(vec0);
+            vec1 = expand_utf8_to_utf32(vec1);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, false)
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec1, valid_count1, false)
+        }
+        const __m512i lane3 = broadcast_epi128<3>(utf8);
+        int valid_count2;
+        __m512i vec2 = expand_and_identify(lane2, lane3, valid_count2);
+        uint32_t tmp1;
+        ::memcpy(&tmp1, ptr + 64, sizeof(tmp1));
+        const __m512i lane4 = _mm512_set1_epi32(tmp1);
+        int valid_count3;
+        __m512i vec3 = expand_and_identify(lane3, lane4, valid_count3);
+        if(valid_count2 + valid_count3 <= 16) {
+            vec2 = _mm512_mask_expand_epi32(vec2, __mmask16(((1<<valid_count3)-1)<<valid_count2), vec3);
+            valid_count2 += valid_count3;
+            vec2 = expand_utf8_to_utf32(vec2);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec2, valid_count2, false)
+        } else {
+            vec2 = expand_utf8_to_utf32(vec2);
+            vec3 = expand_utf8_to_utf32(vec3);
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec2, valid_count2, false)
+            SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec3, valid_count3, false)
+        }
+        ptr += 4*16;
+    }
+    const char* validatedptr = ptr; // validated up to ptr
+
+    // For the final pass, we validate 64 bytes, but we only transcode
+    // 3*16 bytes, so we may end up double-validating 16 bytes.
+    if (ptr + 64 <= end) {
+        const __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+        if(checker.check_next_input(utf8)) {
+            SIMDUTF_ICELAKE_STORE_ASCII(UTF32, utf8, output)
+            output += 64;
+            ptr += 64;
+        } else if(checker.errors()) {
+            return {ptr, output, false}; // We found an error.
+        } else {
+            const __m512i lane0 = broadcast_epi128<0>(utf8);
+            const __m512i lane1 = broadcast_epi128<1>(utf8);
+            int valid_count0;
+            __m512i vec0 = expand_and_identify(lane0, lane1, valid_count0);
+            const __m512i lane2 = broadcast_epi128<2>(utf8);
+            int valid_count1;
+            __m512i vec1 = expand_and_identify(lane1, lane2, valid_count1);
+            if(valid_count0 + valid_count1 <= 16) {
+                vec0 = _mm512_mask_expand_epi32(vec0, __mmask16(((1<<valid_count1)-1)<<valid_count0), vec1);
+                valid_count0 += valid_count1;
+                vec0 = expand_utf8_to_utf32(vec0);
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, true)
+            } else {
+                vec0 = expand_utf8_to_utf32(vec0);
+                vec1 = expand_utf8_to_utf32(vec1);
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec0, valid_count0, true)
+                SIMDUTF_ICELAKE_WRITE_UTF16_OR_UTF32(vec1, valid_count1, true)
+            }
+
+            const __m512i lane3 = broadcast_epi128<3>(utf8);
+            SIMDUTF_ICELAKE_TRANSCODE16(lane2, lane3, true)
+
+            ptr += 3*16;
+        }
+        validatedptr += 4*16;
+    }
+    {
+       const __m512i utf8 = _mm512_maskz_loadu_epi8((1ULL<<(end - validatedptr))-1, (const __m512i*)validatedptr);
+       checker.check_next_input(utf8);
+    }
+    checker.check_eof();
+    if(checker.errors()) {
+        return {ptr, output, false}; // We found an error.
+    }
+    return {ptr, output, true};
+}
+/* end file src/icelake/icelake_from_utf8.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_convert_utf16_to_utf32.inl.cpp
+/* begin file src/icelake/icelake_convert_utf16_to_utf32.inl.cpp */
+// file included directly
+
+/*
+  Returns a pair: the first unprocessed byte from buf and utf32_output
+  A scalar routing should carry on the conversion of the tail.
+*/
+template <endianness big_endian>
+std::tuple<const char16_t*, char32_t*, bool> convert_utf16_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) {
+  const char16_t* end = buf + len;
+  const __m512i v_fc00 = _mm512_set1_epi16((uint16_t)0xfc00);
+  const __m512i v_d800 = _mm512_set1_epi16((uint16_t)0xd800);
+  const __m512i v_dc00 = _mm512_set1_epi16((uint16_t)0xdc00);
+  __mmask32 carry{0};
+  const __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+  while (buf + 32 <= end) {
+    // Always safe because buf + 32 <= end so that end - buf >= 32 bytes:
+    __m512i in = _mm512_loadu_si512((__m512i*)buf);
+    if(big_endian) { in = _mm512_shuffle_epi8(in, byteflip); }
+
+    // H - bitmask for high surrogates
+    const __mmask32 H = _mm512_cmpeq_epi16_mask(_mm512_and_si512(in, v_fc00), v_d800);
+    // H - bitmask for low surrogates
+    const __mmask32 L = _mm512_cmpeq_epi16_mask(_mm512_and_si512(in, v_fc00), v_dc00);
+
+    if ((H|L)) {
+      // surrogate pair(s) in a register
+      const __mmask32 V = (L ^ (carry | (H << 1)));   // A high surrogate must be followed by low one and a low one must be preceded by a high one.
+                                                      // If valid, V should be equal to 0
+
+      if(V == 0) {
+        // valid case
+        /*
+            Input surrogate pair:
+            |1101.11aa.aaaa.aaaa|1101.10bb.bbbb.bbbb|
+                low surrogate      high surrogate
+        */
+        /*  1. Expand all words to 32-bit words
+            in  |0000.0000.0000.0000.1101.11aa.aaaa.aaaa|0000.0000.0000.0000.1101.10bb.bbbb.bbbb|
+        */
+        const __m512i first = _mm512_cvtepu16_epi32(_mm512_castsi512_si256(in));
+        const __m512i second = _mm512_cvtepu16_epi32(_mm512_extracti32x8_epi32(in,1));
+
+        /*  2. Shift by one 16-bit word to align low surrogates with high surrogates
+            in      |0000.0000.0000.0000.1101.11aa.aaaa.aaaa|0000.0000.0000.0000.1101.10bb.bbbb.bbbb|
+            shifted |????.????.????.????.????.????.????.????|0000.0000.0000.0000.1101.11aa.aaaa.aaaa|
+        */
+        const __m512i shifted_first = _mm512_alignr_epi32(second, first, 1);
+        const __m512i shifted_second = _mm512_alignr_epi32(_mm512_setzero_si512(), second, 1);
+
+        /*  3. Align all high surrogates in first and second by shifting to the left by 10 bits
+            |0000.0000.0000.0000.1101.11aa.aaaa.aaaa|0000.0011.0110.bbbb.bbbb.bb00.0000.0000|
+        */
+        const __m512i aligned_first = _mm512_mask_slli_epi32(first, (__mmask16)H, first, 10);
+        const __m512i aligned_second = _mm512_mask_slli_epi32(second, (__mmask16)(H>>16), second, 10);
+
+        /*  4. Remove surrogate prefixes and add offset 0x10000 by adding in, shifted and constant
+            in      |0000.0000.0000.0000.1101.11aa.aaaa.aaaa|0000.0011.0110.bbbb.bbbb.bb00.0000.0000|
+            shifted |????.????.????.????.????.????.????.????|0000.0000.0000.0000.1101.11aa.aaaa.aaaa|
+            constant|1111.1100.1010.0000.0010.0100.0000.0000|1111.1100.1010.0000.0010.0100.0000.0000|
+        */
+        const __m512i constant = _mm512_set1_epi32((uint32_t)0xfca02400);
+        const __m512i added_first = _mm512_mask_add_epi32(aligned_first, (__mmask16)H, aligned_first, shifted_first);
+        const __m512i utf32_first = _mm512_mask_add_epi32(added_first, (__mmask16)H, added_first, constant);
+
+        const __m512i added_second = _mm512_mask_add_epi32(aligned_second, (__mmask16)(H>>16), aligned_second, shifted_second);
+        const __m512i utf32_second = _mm512_mask_add_epi32(added_second, (__mmask16)(H>>16), added_second, constant);
+
+        //  5. Store all valid UTF-32 words (low surrogate positions and 32nd word are invalid)
+        const __mmask32 valid = ~L & 0x7fffffff;
+        // We deliberately do a _mm512_maskz_compress_epi32 followed by storeu_epi32
+        // to ease performance portability to Zen 4.
+        const __m512i compressed_first = _mm512_maskz_compress_epi32((__mmask16)(valid), utf32_first);
+        const size_t howmany1 = count_ones((uint16_t)(valid));
+        _mm512_storeu_si512((__m512i *) utf32_output,  compressed_first);
+        utf32_output += howmany1;
+        const __m512i compressed_second = _mm512_maskz_compress_epi32((__mmask16)(valid >> 16), utf32_second);
+        const size_t howmany2 = count_ones((uint16_t)(valid >> 16));
+        // The following could be unsafe in some cases?
+        //_mm512_storeu_epi32((__m512i *) utf32_output, compressed_second);
+        _mm512_mask_storeu_epi32((__m512i *) utf32_output, __mmask16((1<<howmany2)-1), compressed_second);
+        utf32_output += howmany2;
+        // Only process 31 words, but keep track if the 31st word is a high surrogate as a carry
+        buf += 31;
+        carry = (H >> 30) & 0x1;
+      } else {
+        // invalid case
+        return std::make_tuple(buf+carry, utf32_output, false);
+      }
+    } else {
+      // no surrogates
+      // extend all thirty-two 16-bit words to thirty-two 32-bit words
+      _mm512_storeu_si512((__m512i *)(utf32_output), _mm512_cvtepu16_epi32(_mm512_castsi512_si256(in)));
+      _mm512_storeu_si512((__m512i *)(utf32_output) + 1, _mm512_cvtepu16_epi32(_mm512_extracti32x8_epi32(in,1)));
+      utf32_output += 32;
+      buf += 32;
+      carry = 0;
+    }
+  } // while
+  return std::make_tuple(buf+carry, utf32_output, true);
+}
+/* end file src/icelake/icelake_convert_utf16_to_utf32.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_convert_utf32_to_utf8.inl.cpp
+/* begin file src/icelake/icelake_convert_utf32_to_utf8.inl.cpp */
+// file included directly
+
+// Todo: currently, this is just the haswell code, optimize for icelake kernel.
+std::pair<const char32_t*, char*> avx512_convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) {
+  const char32_t* end = buf + len;
+  const __m256i v_0000 = _mm256_setzero_si256();
+  const __m256i v_ffff0000 = _mm256_set1_epi32((uint32_t)0xffff0000);
+  const __m256i v_ff80 = _mm256_set1_epi16((uint16_t)0xff80);
+  const __m256i v_f800 = _mm256_set1_epi16((uint16_t)0xf800);
+  const __m256i v_c080 = _mm256_set1_epi16((uint16_t)0xc080);
+  const __m256i v_7fffffff = _mm256_set1_epi32((uint32_t)0x7fffffff);
+  __m256i running_max = _mm256_setzero_si256();
+  __m256i forbidden_bytemask = _mm256_setzero_si256();
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+    __m256i nextin = _mm256_loadu_si256((__m256i*)buf+1);
+    running_max = _mm256_max_epu32(_mm256_max_epu32(in, running_max), nextin);
+
+    // Pack 32-bit UTF-32 words to 16-bit UTF-16 words with unsigned saturation
+    __m256i in_16 = _mm256_packus_epi32(_mm256_and_si256(in, v_7fffffff), _mm256_and_si256(nextin, v_7fffffff));
+    in_16 = _mm256_permute4x64_epi64(in_16, 0b11011000);
+
+    // Try to apply UTF-16 => UTF-8 routine on 256 bits (haswell/avx2_convert_utf16_to_utf8.cpp)
+
+    if(_mm256_testz_si256(in_16, v_ff80)) { // ASCII fast path!!!!
+      // 1. pack the bytes
+      const __m128i utf8_packed = _mm_packus_epi16(_mm256_castsi256_si128(in_16),_mm256_extractf128_si256(in_16,1));
+      // 2. store (16 bytes)
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+      // 3. adjust pointers
+      buf += 16;
+      utf8_output += 16;
+      continue; // we are done for this round!
+    }
+    // no bits set above 7th bit
+    const __m256i one_byte_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_ff80), v_0000);
+    const uint32_t one_byte_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m256i one_or_two_bytes_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_f800), v_0000);
+    const uint32_t one_or_two_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_or_two_bytes_bytemask));
+    if (one_or_two_bytes_bitmask == 0xffffffff) {
+      // 1. prepare 2-byte values
+      // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+      // expected output   : [110a|aaaa|10bb|bbbb] x 8
+      const __m256i v_1f00 = _mm256_set1_epi16((int16_t)0x1f00);
+      const __m256i v_003f = _mm256_set1_epi16((int16_t)0x003f);
+
+      // t0 = [000a|aaaa|bbbb|bb00]
+      const __m256i t0 = _mm256_slli_epi16(in_16, 2);
+      // t1 = [000a|aaaa|0000|0000]
+      const __m256i t1 = _mm256_and_si256(t0, v_1f00);
+      // t2 = [0000|0000|00bb|bbbb]
+      const __m256i t2 = _mm256_and_si256(in_16, v_003f);
+      // t3 = [000a|aaaa|00bb|bbbb]
+      const __m256i t3 = _mm256_or_si256(t1, t2);
+      // t4 = [110a|aaaa|10bb|bbbb]
+      const __m256i t4 = _mm256_or_si256(t3, v_c080);
+
+      // 2. merge ASCII and 2-byte codewords
+      const __m256i utf8_unpacked = _mm256_blendv_epi8(t4, in_16, one_byte_bytemask);
+
+      // 3. prepare bitmask for 8-bit lookup
+      const uint32_t M0 = one_byte_bitmask & 0x55555555;
+      const uint32_t M1 = M0 >> 7;
+      const uint32_t M2 = (M1 | M0)  & 0x00ff00ff;
+      // 4. pack the bytes
+
+      const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2)][0];
+      const uint8_t* row_2 = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2>>16)][0];
+
+      const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+      const __m128i shuffle_2 = _mm_loadu_si128((__m128i*)(row_2 + 1));
+
+      const __m256i utf8_packed = _mm256_shuffle_epi8(utf8_unpacked, _mm256_setr_m128i(shuffle,shuffle_2));
+      // 5. store bytes
+      _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_packed));
+      utf8_output += row[0];
+      _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_packed,1));
+      utf8_output += row_2[0];
+
+      // 6. adjust pointers
+      buf += 16;
+      continue;
+    }
+    // Must check for overflow in packing
+    const __m256i saturation_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(_mm256_or_si256(in, nextin), v_ffff0000), v_0000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(saturation_bytemask));
+    if (saturation_bitmask == 0xffffffff) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+      const __m256i v_d800 = _mm256_set1_epi16((uint16_t)0xd800);
+      forbidden_bytemask = _mm256_or_si256(forbidden_bytemask, _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_f800), v_d800));
+
+      const __m256i dup_even = _mm256_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e,
+                                              0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+      /* In this branch we handle three cases:
+        1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+        2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+        3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+        We expand the input word (16-bit) into two words (32-bit), thus
+        we have room for four bytes. However, we need five distinct bit
+        layouts. Note that the last byte in cases #2 and #3 is the same.
+
+        We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+        in register t2.
+
+        We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+        either byte 1 for case #2 or byte 2 for case #3. Note that they
+        differ by exactly one bit.
+
+        Finally from these two words we build proper UTF-8 sequence, taking
+        into account the case (i.e, the number of bytes to write).
+      */
+      /**
+       * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+       * t2 => [0ccc|cccc] [10cc|cccc]
+       * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+       */
+#define vec(x) _mm256_set1_epi16(static_cast<uint16_t>(x))
+      // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+      const __m256i t0 = _mm256_shuffle_epi8(in_16, dup_even);
+      // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+      const __m256i t1 = _mm256_and_si256(t0, vec(0b0011111101111111));
+      // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+      const __m256i t2 = _mm256_or_si256 (t1, vec(0b1000000000000000));
+
+      // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+      const __m256i s0 = _mm256_srli_epi16(in_16, 4);
+      // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+      const __m256i s1 = _mm256_and_si256(s0, vec(0b0000111111111100));
+      // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+      const __m256i s2 = _mm256_maddubs_epi16(s1, vec(0x0140));
+      // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+      const __m256i s3 = _mm256_or_si256(s2, vec(0b1100000011100000));
+      const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+      const __m256i s4 = _mm256_xor_si256(s3, m0);
+#undef vec
+
+      // 4. expand words 16-bit => 32-bit
+      const __m256i out0 = _mm256_unpacklo_epi16(t2, s4);
+      const __m256i out1 = _mm256_unpackhi_epi16(t2, s4);
+
+      // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+      const uint32_t mask = (one_byte_bitmask & 0x55555555) |
+                            (one_or_two_bytes_bitmask & 0xaaaaaaaa);
+      // Due to the wider registers, the following path is less likely to be useful.
+      /*if(mask == 0) {
+        // We only have three-byte words. Use fast path.
+        const __m256i shuffle = _mm256_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1, 2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+        const __m256i utf8_0 = _mm256_shuffle_epi8(out0, shuffle);
+        const __m256i utf8_1 = _mm256_shuffle_epi8(out1, shuffle);
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_0));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_1));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_0,1));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_1,1));
+        utf8_output += 12;
+        buf += 16;
+        continue;
+      }*/
+      const uint8_t mask0 = uint8_t(mask);
+      const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+      const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+      const __m128i utf8_0 = _mm_shuffle_epi8(_mm256_castsi256_si128(out0), shuffle0);
+
+      const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+      const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+      const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+      const __m128i utf8_1 = _mm_shuffle_epi8(_mm256_castsi256_si128(out1), shuffle1);
+
+      const uint8_t mask2 = static_cast<uint8_t>(mask >> 16);
+      const uint8_t* row2 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask2][0];
+      const __m128i shuffle2 = _mm_loadu_si128((__m128i*)(row2 + 1));
+      const __m128i utf8_2 = _mm_shuffle_epi8(_mm256_extractf128_si256(out0,1), shuffle2);
+
+
+      const uint8_t mask3 = static_cast<uint8_t>(mask >> 24);
+      const uint8_t* row3 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask3][0];
+      const __m128i shuffle3 = _mm_loadu_si128((__m128i*)(row3 + 1));
+      const __m128i utf8_3 = _mm_shuffle_epi8(_mm256_extractf128_si256(out1,1), shuffle3);
+
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+      utf8_output += row0[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+      utf8_output += row1[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_2);
+      utf8_output += row2[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_3);
+      utf8_output += row3[0];
+      buf += 16;
+    } else {
+      // case: at least one 32-bit word is larger than 0xFFFF <=> it will produce four UTF-8 bytes.
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // may require large, non-trivial tables?
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFFFF80)==0) {  // 1-byte (ASCII)
+          *utf8_output++ = char(word);
+        } else if((word & 0xFFFFF800)==0) { // 2-byte
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word & 0xFFFF0000 )==0) {  // 3-byte
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(nullptr, utf8_output); }
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {  // 4-byte
+          if (word > 0x10FFFF) { return std::make_pair(nullptr, utf8_output); }
+          *utf8_output++ = char((word>>18) | 0b11110000);
+          *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  // check for invalid input
+  const __m256i v_10ffff = _mm256_set1_epi32((uint32_t)0x10ffff);
+  if(static_cast<uint32_t>(_mm256_movemask_epi8(_mm256_cmpeq_epi32(_mm256_max_epu32(running_max, v_10ffff), v_10ffff))) != 0xffffffff) {
+    return std::make_pair(nullptr, utf8_output);
+  }
+
+  if (static_cast<uint32_t>(_mm256_movemask_epi8(forbidden_bytemask)) != 0) { return std::make_pair(nullptr, utf8_output); }
+
+  return std::make_pair(buf, utf8_output);
+}
+
+// Todo: currently, this is just the haswell code, optimize for icelake kernel.
+std::pair<result, char*> avx512_convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) {
+  const char32_t* end = buf + len;
+  const char32_t* start = buf;
+
+  const __m256i v_0000 = _mm256_setzero_si256();
+  const __m256i v_ffff0000 = _mm256_set1_epi32((uint32_t)0xffff0000);
+  const __m256i v_ff80 = _mm256_set1_epi16((uint16_t)0xff80);
+  const __m256i v_f800 = _mm256_set1_epi16((uint16_t)0xf800);
+  const __m256i v_c080 = _mm256_set1_epi16((uint16_t)0xc080);
+  const __m256i v_7fffffff = _mm256_set1_epi32((uint32_t)0x7fffffff);
+  const __m256i v_10ffff = _mm256_set1_epi32((uint32_t)0x10ffff);
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+    __m256i nextin = _mm256_loadu_si256((__m256i*)buf+1);
+    // Check for too large input
+    const __m256i max_input = _mm256_max_epu32(_mm256_max_epu32(in, nextin), v_10ffff);
+    if(static_cast<uint32_t>(_mm256_movemask_epi8(_mm256_cmpeq_epi32(max_input, v_10ffff))) != 0xffffffff) {
+      return std::make_pair(result(error_code::TOO_LARGE, buf - start), utf8_output);
+    }
+
+    // Pack 32-bit UTF-32 words to 16-bit UTF-16 words with unsigned saturation
+    __m256i in_16 = _mm256_packus_epi32(_mm256_and_si256(in, v_7fffffff), _mm256_and_si256(nextin, v_7fffffff));
+    in_16 = _mm256_permute4x64_epi64(in_16, 0b11011000);
+
+    // Try to apply UTF-16 => UTF-8 routine on 256 bits (haswell/avx2_convert_utf16_to_utf8.cpp)
+
+    if(_mm256_testz_si256(in_16, v_ff80)) { // ASCII fast path!!!!
+      // 1. pack the bytes
+      const __m128i utf8_packed = _mm_packus_epi16(_mm256_castsi256_si128(in_16),_mm256_extractf128_si256(in_16,1));
+      // 2. store (16 bytes)
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+      // 3. adjust pointers
+      buf += 16;
+      utf8_output += 16;
+      continue; // we are done for this round!
+    }
+    // no bits set above 7th bit
+    const __m256i one_byte_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_ff80), v_0000);
+    const uint32_t one_byte_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m256i one_or_two_bytes_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_f800), v_0000);
+    const uint32_t one_or_two_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_or_two_bytes_bytemask));
+    if (one_or_two_bytes_bitmask == 0xffffffff) {
+      // 1. prepare 2-byte values
+      // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+      // expected output   : [110a|aaaa|10bb|bbbb] x 8
+      const __m256i v_1f00 = _mm256_set1_epi16((int16_t)0x1f00);
+      const __m256i v_003f = _mm256_set1_epi16((int16_t)0x003f);
+
+      // t0 = [000a|aaaa|bbbb|bb00]
+      const __m256i t0 = _mm256_slli_epi16(in_16, 2);
+      // t1 = [000a|aaaa|0000|0000]
+      const __m256i t1 = _mm256_and_si256(t0, v_1f00);
+      // t2 = [0000|0000|00bb|bbbb]
+      const __m256i t2 = _mm256_and_si256(in_16, v_003f);
+      // t3 = [000a|aaaa|00bb|bbbb]
+      const __m256i t3 = _mm256_or_si256(t1, t2);
+      // t4 = [110a|aaaa|10bb|bbbb]
+      const __m256i t4 = _mm256_or_si256(t3, v_c080);
+
+      // 2. merge ASCII and 2-byte codewords
+      const __m256i utf8_unpacked = _mm256_blendv_epi8(t4, in_16, one_byte_bytemask);
+
+      // 3. prepare bitmask for 8-bit lookup
+      const uint32_t M0 = one_byte_bitmask & 0x55555555;
+      const uint32_t M1 = M0 >> 7;
+      const uint32_t M2 = (M1 | M0)  & 0x00ff00ff;
+      // 4. pack the bytes
+
+      const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2)][0];
+      const uint8_t* row_2 = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2>>16)][0];
+
+      const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+      const __m128i shuffle_2 = _mm_loadu_si128((__m128i*)(row_2 + 1));
+
+      const __m256i utf8_packed = _mm256_shuffle_epi8(utf8_unpacked, _mm256_setr_m128i(shuffle,shuffle_2));
+      // 5. store bytes
+      _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_packed));
+      utf8_output += row[0];
+      _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_packed,1));
+      utf8_output += row_2[0];
+
+      // 6. adjust pointers
+      buf += 16;
+      continue;
+    }
+    // Must check for overflow in packing
+    const __m256i saturation_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(_mm256_or_si256(in, nextin), v_ffff0000), v_0000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(saturation_bytemask));
+    if (saturation_bitmask == 0xffffffff) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+
+      // Check for illegal surrogate words
+      const __m256i v_d800 = _mm256_set1_epi16((uint16_t)0xd800);
+      const __m256i forbidden_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_f800), v_d800);
+      if (static_cast<uint32_t>(_mm256_movemask_epi8(forbidden_bytemask)) != 0x0) {
+        return std::make_pair(result(error_code::SURROGATE, buf - start), utf8_output);
+      }
+
+      const __m256i dup_even = _mm256_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e,
+                                              0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+      /* In this branch we handle three cases:
+        1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+        2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+        3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+        We expand the input word (16-bit) into two words (32-bit), thus
+        we have room for four bytes. However, we need five distinct bit
+        layouts. Note that the last byte in cases #2 and #3 is the same.
+
+        We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+        in register t2.
+
+        We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+        either byte 1 for case #2 or byte 2 for case #3. Note that they
+        differ by exactly one bit.
+
+        Finally from these two words we build proper UTF-8 sequence, taking
+        into account the case (i.e, the number of bytes to write).
+      */
+      /**
+       * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+       * t2 => [0ccc|cccc] [10cc|cccc]
+       * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+       */
+#define vec(x) _mm256_set1_epi16(static_cast<uint16_t>(x))
+      // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+      const __m256i t0 = _mm256_shuffle_epi8(in_16, dup_even);
+      // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+      const __m256i t1 = _mm256_and_si256(t0, vec(0b0011111101111111));
+      // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+      const __m256i t2 = _mm256_or_si256 (t1, vec(0b1000000000000000));
+
+      // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+      const __m256i s0 = _mm256_srli_epi16(in_16, 4);
+      // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+      const __m256i s1 = _mm256_and_si256(s0, vec(0b0000111111111100));
+      // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+      const __m256i s2 = _mm256_maddubs_epi16(s1, vec(0x0140));
+      // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+      const __m256i s3 = _mm256_or_si256(s2, vec(0b1100000011100000));
+      const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+      const __m256i s4 = _mm256_xor_si256(s3, m0);
+#undef vec
+
+      // 4. expand words 16-bit => 32-bit
+      const __m256i out0 = _mm256_unpacklo_epi16(t2, s4);
+      const __m256i out1 = _mm256_unpackhi_epi16(t2, s4);
+
+      // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+      const uint32_t mask = (one_byte_bitmask & 0x55555555) |
+                            (one_or_two_bytes_bitmask & 0xaaaaaaaa);
+      // Due to the wider registers, the following path is less likely to be useful.
+      /*if(mask == 0) {
+        // We only have three-byte words. Use fast path.
+        const __m256i shuffle = _mm256_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1, 2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+        const __m256i utf8_0 = _mm256_shuffle_epi8(out0, shuffle);
+        const __m256i utf8_1 = _mm256_shuffle_epi8(out1, shuffle);
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_0));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_1));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_0,1));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_1,1));
+        utf8_output += 12;
+        buf += 16;
+        continue;
+      }*/
+      const uint8_t mask0 = uint8_t(mask);
+      const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+      const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+      const __m128i utf8_0 = _mm_shuffle_epi8(_mm256_castsi256_si128(out0), shuffle0);
+
+      const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+      const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+      const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+      const __m128i utf8_1 = _mm_shuffle_epi8(_mm256_castsi256_si128(out1), shuffle1);
+
+      const uint8_t mask2 = static_cast<uint8_t>(mask >> 16);
+      const uint8_t* row2 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask2][0];
+      const __m128i shuffle2 = _mm_loadu_si128((__m128i*)(row2 + 1));
+      const __m128i utf8_2 = _mm_shuffle_epi8(_mm256_extractf128_si256(out0,1), shuffle2);
+
+
+      const uint8_t mask3 = static_cast<uint8_t>(mask >> 24);
+      const uint8_t* row3 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask3][0];
+      const __m128i shuffle3 = _mm_loadu_si128((__m128i*)(row3 + 1));
+      const __m128i utf8_3 = _mm_shuffle_epi8(_mm256_extractf128_si256(out1,1), shuffle3);
+
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+      utf8_output += row0[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+      utf8_output += row1[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_2);
+      utf8_output += row2[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_3);
+      utf8_output += row3[0];
+      buf += 16;
+    } else {
+      // case: at least one 32-bit word is larger than 0xFFFF <=> it will produce four UTF-8 bytes.
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // may require large, non-trivial tables?
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFFFF80)==0) {  // 1-byte (ASCII)
+          *utf8_output++ = char(word);
+        } else if((word & 0xFFFFF800)==0) { // 2-byte
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word & 0xFFFF0000 )==0) {  // 3-byte
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(result(error_code::SURROGATE, buf - start + k), utf8_output); }
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {  // 4-byte
+          if (word > 0x10FFFF) { return std::make_pair(result(error_code::TOO_LARGE, buf - start + k), utf8_output); }
+          *utf8_output++ = char((word>>18) | 0b11110000);
+          *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf8_output);
+}
+/* end file src/icelake/icelake_convert_utf32_to_utf8.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_convert_utf32_to_utf16.inl.cpp
+/* begin file src/icelake/icelake_convert_utf32_to_utf16.inl.cpp */
+// file included directly
+
+// Todo: currently, this is just the haswell code, optimize for icelake kernel.
+template <endianness big_endian>
+std::pair<const char32_t*, char16_t*> avx512_convert_utf32_to_utf16(const char32_t* buf, size_t len, char16_t* utf16_output) {
+  const char32_t* end = buf + len;
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+  __m256i forbidden_bytemask = _mm256_setzero_si256();
+
+
+  while (buf + 8 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+
+    const __m256i v_00000000 = _mm256_setzero_si256();
+    const __m256i v_ffff0000 = _mm256_set1_epi32((int32_t)0xffff0000);
+
+    // no bits set above 16th bit <=> can pack to UTF16 without surrogate pairs
+    const __m256i saturation_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_ffff0000), v_00000000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(saturation_bytemask));
+
+    if (saturation_bitmask == 0xffffffff) {
+      const __m256i v_f800 = _mm256_set1_epi32((uint32_t)0xf800);
+      const __m256i v_d800 = _mm256_set1_epi32((uint32_t)0xd800);
+      forbidden_bytemask = _mm256_or_si256(forbidden_bytemask, _mm256_cmpeq_epi32(_mm256_and_si256(in, v_f800), v_d800));
+
+      __m128i utf16_packed = _mm_packus_epi32(_mm256_castsi256_si128(in),_mm256_extractf128_si256(in,1));
+      if (big_endian) {
+        const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+        utf16_packed = _mm_shuffle_epi8(utf16_packed, swap);
+      }
+      _mm_storeu_si128((__m128i*)utf16_output, utf16_packed);
+      utf16_output += 8;
+      buf += 8;
+    } else {
+      size_t forward = 7;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFF0000)==0) {
+          // will not generate a surrogate pair
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(nullptr, utf16_output); }
+          *utf16_output++ = big_endian ? char16_t((uint16_t(word) >> 8) | (uint16_t(word) << 8)) : char16_t(word);
+        } else {
+          // will generate a surrogate pair
+          if (word > 0x10FFFF) { return std::make_pair(nullptr, utf16_output); }
+          word -= 0x10000;
+          uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+          uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+          if (big_endian) {
+            high_surrogate = uint16_t((high_surrogate >> 8) | (high_surrogate << 8));
+            low_surrogate = uint16_t((low_surrogate >> 8) | (low_surrogate << 8));
+          }
+          *utf16_output++ = char16_t(high_surrogate);
+          *utf16_output++ = char16_t(low_surrogate);
+        }
+      }
+      buf += k;
+    }
+  }
+
+  // check for invalid input
+  if (static_cast<uint32_t>(_mm256_movemask_epi8(forbidden_bytemask)) != 0) { return std::make_pair(nullptr, utf16_output); }
+
+  return std::make_pair(buf, utf16_output);
+}
+
+// Todo: currently, this is just the haswell code, optimize for icelake kernel.
+template <endianness big_endian>
+std::pair<result, char16_t*> avx512_convert_utf32_to_utf16_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) {
+  const char32_t* start = buf;
+  const char32_t* end = buf + len;
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 8 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+
+    const __m256i v_00000000 = _mm256_setzero_si256();
+    const __m256i v_ffff0000 = _mm256_set1_epi32((int32_t)0xffff0000);
+
+    // no bits set above 16th bit <=> can pack to UTF16 without surrogate pairs
+    const __m256i saturation_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_ffff0000), v_00000000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(saturation_bytemask));
+
+    if (saturation_bitmask == 0xffffffff) {
+      const __m256i v_f800 = _mm256_set1_epi32((uint32_t)0xf800);
+      const __m256i v_d800 = _mm256_set1_epi32((uint32_t)0xd800);
+      const __m256i forbidden_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_f800), v_d800);
+      if (static_cast<uint32_t>(_mm256_movemask_epi8(forbidden_bytemask)) != 0x0) {
+        return std::make_pair(result(error_code::SURROGATE, buf - start), utf16_output);
+      }
+
+      __m128i utf16_packed = _mm_packus_epi32(_mm256_castsi256_si128(in),_mm256_extractf128_si256(in,1));
+      if (big_endian) {
+        const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+        utf16_packed = _mm_shuffle_epi8(utf16_packed, swap);
+      }
+      _mm_storeu_si128((__m128i*)utf16_output, utf16_packed);
+      utf16_output += 8;
+      buf += 8;
+    } else {
+      size_t forward = 7;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFF0000)==0) {
+          // will not generate a surrogate pair
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(result(error_code::SURROGATE, buf - start + k), utf16_output); }
+          *utf16_output++ = big_endian ? char16_t((uint16_t(word) >> 8) | (uint16_t(word) << 8)) : char16_t(word);
+        } else {
+          // will generate a surrogate pair
+          if (word > 0x10FFFF) { return std::make_pair(result(error_code::TOO_LARGE, buf - start + k), utf16_output); }
+          word -= 0x10000;
+          uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+          uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+          if (big_endian) {
+            high_surrogate = uint16_t((high_surrogate >> 8) | (high_surrogate << 8));
+            low_surrogate = uint16_t((low_surrogate >> 8) | (low_surrogate << 8));
+          }
+          *utf16_output++ = char16_t(high_surrogate);
+          *utf16_output++ = char16_t(low_surrogate);
+        }
+      }
+      buf += k;
+    }
+  }
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf16_output);
+}
+/* end file src/icelake/icelake_convert_utf32_to_utf16.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_ascii_validation.inl.cpp
+/* begin file src/icelake/icelake_ascii_validation.inl.cpp */
+// file included directly
+
+const char* validate_ascii(const char* buf, size_t len) {
+  const char* end = buf + len;
+  const __m512i ascii = _mm512_set1_epi8((uint8_t)0x80);
+  __m512i running_or = _mm512_setzero_si512();
+  for (; buf + 64 <= end; buf += 64) {
+    const __m512i utf8 = _mm512_loadu_si512((const __m512i*)buf);
+    running_or = _mm512_ternarylogic_epi32(running_or, utf8, ascii, 0xf8); // running_or | (utf8 & ascii)
+  }
+  if (_mm512_test_epi8_mask(running_or, running_or) != 0) {
+    return nullptr;
+  } else {
+    return buf;
+  }
+}
+/* end file src/icelake/icelake_ascii_validation.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_utf32_validation.inl.cpp
+/* begin file src/icelake/icelake_utf32_validation.inl.cpp */
+// file included directly
+
+const char32_t* validate_utf32(const char32_t* buf, size_t len) {
+    const char32_t* end = len >= 16 ? buf + len - 16 : nullptr;
+
+    const __m512i offset = _mm512_set1_epi32((uint32_t)0xffff2000);
+    __m512i currentmax = _mm512_setzero_si512();
+    __m512i currentoffsetmax = _mm512_setzero_si512();
+
+    while (buf <= end) {
+      __m512i utf32 = _mm512_loadu_si512((const __m512i*)buf);
+      buf += 16;
+      currentoffsetmax = _mm512_max_epu32(_mm512_add_epi32(utf32, offset), currentoffsetmax);
+      currentmax = _mm512_max_epu32(utf32, currentmax);
+    }
+
+    const __m512i standardmax = _mm512_set1_epi32((uint32_t)0x10ffff);
+    const __m512i standardoffsetmax = _mm512_set1_epi32((uint32_t)0xfffff7ff);
+    __m512i is_zero = _mm512_xor_si512(_mm512_max_epu32(currentmax, standardmax), standardmax);
+    if (_mm512_test_epi8_mask(is_zero, is_zero) != 0) {
+      return nullptr;
+    }
+    is_zero = _mm512_xor_si512(_mm512_max_epu32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+    if (_mm512_test_epi8_mask(is_zero, is_zero) != 0) {
+      return nullptr;
+    }
+
+    return buf;
+}
+/* end file src/icelake/icelake_utf32_validation.inl.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=icelake/icelake_convert_utf16_to_utf8.inl.cpp
+/* begin file src/icelake/icelake_convert_utf16_to_utf8.inl.cpp */
+// file included directly
+
+/**
+ * This function converts the input (inbuf, inlen), assumed to be valid
+ * UTF16 (little endian) into UTF-8 (to outbuf). The number of words written
+ * is written to 'outlen' and the function reports the number of input word
+ * consumed.
+ */
+
+ template <endianness big_endian>
+ size_t utf16_to_utf8_avx512i(const char16_t *inbuf, size_t inlen,
+                               unsigned char *outbuf, size_t *outlen) {
+  __m512i in;
+  __mmask32 inmask = _cvtu32_mask32(0x7fffffff);
+  __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+  const char16_t * const inbuf_orig = inbuf;
+  const unsigned char * const outbuf_orig = outbuf;
+  size_t adjust = 0;
+  int carry = 0;
+
+  while (inlen >= 32) {
+    in = _mm512_loadu_si512(inbuf);
+    if(big_endian) { in = _mm512_shuffle_epi8(in, byteflip); }
+    inlen -= 31;
+  lastiteration:
+    inbuf += 31;
+
+  failiteration:
+    const __mmask32 is234byte = _mm512_mask_cmp_epu16_mask(
+      inmask, in, _mm512_set1_epi16(0x0080), _MM_CMPINT_NLT);
+
+    if (_ktestz_mask32_u8(inmask, is234byte)) {
+      // fast path for ASCII only
+      _mm512_mask_cvtepi16_storeu_epi8(outbuf, inmask, in);
+      outbuf += 31;
+      carry = 0;
+
+      if (inlen < 32) {
+        goto tail;
+      } else {
+        continue;
+      }
+    }
+
+    const __mmask32 is12byte =
+        _mm512_cmp_epu16_mask(in, _mm512_set1_epi16(0x0800), _MM_CMPINT_LT);
+
+    if (_ktestc_mask32_u8(is12byte, inmask)) {
+      // fast path for 1 and 2 byte only
+
+      const __m512i twobytes = _mm512_ternarylogic_epi32(
+          _mm512_slli_epi16(in, 8), _mm512_srli_epi16(in, 6),
+          _mm512_set1_epi16(0x3f3f), 0xa8); // (A|B)&C
+      in = _mm512_mask_add_epi16(in, is234byte, twobytes,
+                                 _mm512_set1_epi16(int16_t(0x80c0)));
+      const __m512i cmpmask =
+          _mm512_mask_blend_epi16(inmask, _mm512_set1_epi16(int16_t(0xffff)),
+                                  _mm512_set1_epi16(0x0800));
+      const __mmask64 smoosh = _mm512_cmp_epu8_mask(in, cmpmask, _MM_CMPINT_NLT);
+      const __m512i out = _mm512_maskz_compress_epi8(smoosh, in);
+      _mm512_mask_storeu_epi8(outbuf, _cvtu64_mask64(_pext_u64(_cvtmask64_u64(smoosh), _cvtmask64_u64(smoosh))),
+                              out);
+      outbuf += 31 + _mm_popcnt_u32(_cvtmask32_u32(is234byte));
+      carry = 0;
+
+      if (inlen < 32) {
+        goto tail;
+      } else {
+        continue;
+      }
+    }
+    __m512i lo = _mm512_cvtepu16_epi32(_mm512_castsi512_si256(in));
+    __m512i hi = _mm512_cvtepu16_epi32(_mm512_extracti32x8_epi32(in, 1));
+
+
+    __m512i taglo = _mm512_set1_epi32(0x8080e000);
+    __m512i taghi = taglo;
+
+    const __m512i fc00masked = _mm512_and_epi32(in, _mm512_set1_epi16(int16_t(0xfc00)));
+    const __mmask32 hisurr = _mm512_mask_cmp_epu16_mask(
+        inmask, fc00masked, _mm512_set1_epi16(int16_t(0xd800)), _MM_CMPINT_EQ);
+    const __mmask32 losurr = _mm512_cmp_epu16_mask(
+        fc00masked, _mm512_set1_epi16(int16_t(0xdc00)), _MM_CMPINT_EQ);
+
+    int carryout = 0;
+    if (!_kortestz_mask32_u8(hisurr, losurr)) {
+      // handle surrogates
+
+      __m512i los = _mm512_alignr_epi32(hi, lo, 1);
+      __m512i his = _mm512_alignr_epi32(lo, hi, 1);
+
+      const __mmask32 hisurrhi = _kshiftri_mask32(hisurr, 16);
+      taglo =
+          _mm512_mask_mov_epi32(taglo,__mmask16(hisurr), _mm512_set1_epi32(0x808080f0));
+      taghi =
+          _mm512_mask_mov_epi32(taghi, __mmask16(hisurrhi), _mm512_set1_epi32(0x808080f0));
+
+      lo = _mm512_mask_slli_epi32(lo, __mmask16(hisurr), lo, 10);
+      hi = _mm512_mask_slli_epi32(hi, __mmask16(hisurrhi), hi, 10);
+      los = _mm512_add_epi32(los, _mm512_set1_epi32(0xfca02400));
+      his = _mm512_add_epi32(his, _mm512_set1_epi32(0xfca02400));
+      lo = _mm512_mask_add_epi32(lo, __mmask16(hisurr), lo, los);
+      hi = _mm512_mask_add_epi32(hi, __mmask16(hisurrhi), hi, his);
+
+      carryout = _cvtu32_mask32(_kshiftri_mask32(hisurr, 30));
+
+      const uint32_t  h = _cvtmask32_u32(hisurr);
+      const uint32_t  l = _cvtmask32_u32(losurr);
+      // check for mismatched surrogates
+      if ((h + h + carry) ^ l) {
+        const uint32_t lonohi = l & ~(h + h + carry);
+        const uint32_t hinolo = h & ~(l >> 1);
+        inlen = _tzcnt_u32(hinolo | lonohi);
+        inmask = __mmask32(0x7fffffff & ((1 << inlen) - 1));
+        in = _mm512_maskz_mov_epi16(inmask, in);
+        adjust = (int)inlen - 31;
+        inlen = 0;
+        goto failiteration;
+      }
+    }
+
+    hi = _mm512_maskz_mov_epi32(_cvtu32_mask16(0x7fff),hi);
+    carry = carryout;
+
+    __m512i mslo =
+        _mm512_multishift_epi64_epi8(_mm512_set1_epi64(0x20262c3200060c12), lo);
+
+    __m512i mshi =
+        _mm512_multishift_epi64_epi8(_mm512_set1_epi64(0x20262c3200060c12), hi);
+
+    const __mmask32 outmask = __mmask32(_kandn_mask64(losurr, inmask));
+    const __mmask64 outmhi = _kshiftri_mask64(outmask, 16);
+
+    const __mmask32 is1byte = __mmask32(_knot_mask64(is234byte));
+    const __mmask64 is1bhi = _kshiftri_mask64(is1byte, 16);
+    const __mmask64 is12bhi = _kshiftri_mask64(is12byte, 16);
+
+    taglo =
+        _mm512_mask_mov_epi32(taglo, __mmask16(is12byte), _mm512_set1_epi32(0x80c00000));
+    taghi =
+        _mm512_mask_mov_epi32(taghi, __mmask16(is12bhi), _mm512_set1_epi32(0x80c00000));
+    __m512i magiclo = _mm512_mask_blend_epi32(__mmask16(outmask), _mm512_set1_epi32(0xffffffff),
+                                      _mm512_set1_epi32(0x00010101));
+    __m512i magichi = _mm512_mask_blend_epi32(__mmask16(outmhi), _mm512_set1_epi32(0xffffffff),
+                                      _mm512_set1_epi32(0x00010101));
+
+
+    magiclo = _mm512_mask_blend_epi32(__mmask16(outmask), _mm512_set1_epi32(0xffffffff),
+                                      _mm512_set1_epi32(0x00010101));
+    magichi = _mm512_mask_blend_epi32(__mmask16(outmhi), _mm512_set1_epi32(0xffffffff),
+                                      _mm512_set1_epi32(0x00010101));
+
+    mslo = _mm512_ternarylogic_epi32(mslo, _mm512_set1_epi32(0x3f3f3f3f), taglo,
+                                     0xea); // A&B|C
+    mshi = _mm512_ternarylogic_epi32(mshi, _mm512_set1_epi32(0x3f3f3f3f), taghi,
+                                     0xea);
+    mslo = _mm512_mask_slli_epi32(mslo, __mmask16(is1byte), lo, 24);
+
+    mshi = _mm512_mask_slli_epi32(mshi, __mmask16(is1bhi), hi, 24);
+
+    const __mmask64 wantlo = _mm512_cmp_epu8_mask(mslo, magiclo, _MM_CMPINT_NLT);
+    const __mmask64 wanthi = _mm512_cmp_epu8_mask(mshi, magichi, _MM_CMPINT_NLT);
+    const __m512i outlo = _mm512_maskz_compress_epi8(wantlo, mslo);
+    const __m512i outhi = _mm512_maskz_compress_epi8(wanthi, mshi);
+    const uint64_t wantlo_uint64 = _cvtmask64_u64(wantlo);
+    const uint64_t wanthi_uint64 = _cvtmask64_u64(wanthi);
+
+    uint64_t advlo = _mm_popcnt_u64(wantlo_uint64);
+    uint64_t advhi = _mm_popcnt_u64(wanthi_uint64);
+
+    _mm512_mask_storeu_epi8(outbuf, _cvtu64_mask64(_pext_u64(wantlo_uint64, wantlo_uint64)), outlo);
+    _mm512_mask_storeu_epi8(outbuf + advlo, _cvtu64_mask64(_pext_u64(wanthi_uint64, wanthi_uint64)), outhi);
+    outbuf += advlo + advhi;
+  }
+  outbuf -= adjust;
+
+tail:
+  if (inlen != 0) {
+    // We must have inlen < 31.
+    inmask = _cvtu32_mask32((1 << inlen) - 1);
+    in = _mm512_maskz_loadu_epi16(inmask, inbuf);
+    if(big_endian) { in = _mm512_shuffle_epi8(in, byteflip); }
+    adjust = inlen - 31;
+    inlen = 0;
+    goto lastiteration;
+  }
+  *outlen = (outbuf - outbuf_orig) + adjust;
+  return ((inbuf - inbuf_orig) + adjust);
+}
+/* end file src/icelake/icelake_convert_utf16_to_utf8.inl.cpp */
+
+} // namespace
+} // namespace icelake
+} // namespace simdutf
+
+namespace simdutf {
+namespace icelake {
+
+
+simdutf_warn_unused int
+implementation::detect_encodings(const char *input,
+                                 size_t length) const noexcept {
+  // If there is a BOM, then we trust it.
+  auto bom_encoding = simdutf::BOM::check_bom(input, length);
+  if(bom_encoding != encoding_type::unspecified) { return bom_encoding; }
+  if (length % 2 == 0) {
+    const char *buf = input;
+
+    const char *start = buf;
+    const char *end = input + length;
+
+    bool is_utf8 = true;
+    bool is_utf16 = true;
+    bool is_utf32 = true;
+
+    int out = 0;
+
+    avx512_utf8_checker checker{};
+    __m512i currentmax = _mm512_setzero_si512();
+    while (buf + 64 <= end) {
+      __m512i in = _mm512_loadu_si512((__m512i *)buf);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates =
+          _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if (surrogates) {
+        is_utf8 = false;
+
+        // Can still be either UTF-16LE or UTF-32LE depending on the positions
+        // of the surrogates To be valid UTF-32LE, a surrogate cannot be in the
+        // two most significant bytes of any 32-bit word. On the other hand, to
+        // be valid UTF-16LE, at least one surrogate must be in the two most
+        // significant bytes of a 32-bit word since they always come in pairs in
+        // UTF-16LE. Note that we always proceed in multiple of 4 before this
+        // point so there is no offset in 32-bit words.
+
+        if ((surrogates & 0xaaaaaaaa) != 0) {
+          is_utf32 = false;
+          __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(
+              diff, _mm512_set1_epi16(uint16_t(0x0400)));
+          __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+          // high must be followed by low
+          if ((highsurrogates << 1) != lowsurrogates) {
+            return simdutf::encoding_type::unspecified;
+          }
+
+          bool ends_with_high = ((highsurrogates & 0x80000000) != 0);
+          if (ends_with_high) {
+            buf +=
+                31 *
+                sizeof(char16_t); // advance only by 31 words so that we start
+                                  // with the high surrogate on the next round.
+          } else {
+            buf += 32 * sizeof(char16_t);
+          }
+          is_utf16 = validate_utf16le(reinterpret_cast<const char16_t *>(buf),
+                                      (end - buf) / sizeof(char16_t));
+          if (!is_utf16) {
+            return simdutf::encoding_type::unspecified;
+
+          } else {
+            return simdutf::encoding_type::UTF16_LE;
+          }
+
+        } else {
+          is_utf16 = false;
+          // Check for UTF-32LE
+          if (length % 4 == 0) {
+            const char32_t *input32 = reinterpret_cast<const char32_t *>(buf);
+            const char32_t *end32 =
+                reinterpret_cast<const char32_t *>(start) + length / 4;
+            if (validate_utf32(input32, end32 - input32)) {
+              return simdutf::encoding_type::UTF32_LE;
+            }
+          }
+          return simdutf::encoding_type::unspecified;
+        }
+        break;
+      }
+      // If no surrogate, validate under other encodings as well
+
+      // UTF-32LE validation
+      currentmax = _mm512_max_epu32(in, currentmax);
+
+      // UTF-8 validation
+      checker.check_next_input(in);
+
+      buf += 64;
+    }
+
+    // Check which encodings are possible
+
+    if (is_utf8) {
+      size_t current_length = static_cast<size_t>(buf - start);
+      if (current_length != length) {
+        const __m512i utf8 = _mm512_maskz_loadu_epi8(
+            (1ULL << (length - current_length)) - 1, (const __m512i *)buf);
+        checker.check_next_input(utf8);
+      }
+      checker.check_eof();
+      if (!checker.errors()) {
+        out |= simdutf::encoding_type::UTF8;
+      }
+    }
+
+    if (is_utf16 && scalar::utf16::validate<endianness::LITTLE>(
+                        reinterpret_cast<const char16_t *>(buf),
+                        (length - (buf - start)) / 2)) {
+      out |= simdutf::encoding_type::UTF16_LE;
+    }
+
+    if (is_utf32 && (length % 4 == 0)) {
+      currentmax = _mm512_max_epu32(
+          _mm512_maskz_loadu_epi8(
+              (1ULL << (length - static_cast<size_t>(buf - start))) - 1,
+              (const __m512i *)buf),
+          currentmax);
+      __mmask16 outside_range = _mm512_cmp_epu32_mask(currentmax, _mm512_set1_epi32(0x10ffff),
+                                _MM_CMPINT_GT);
+      if (outside_range == 0) {
+        out |= simdutf::encoding_type::UTF32_LE;
+      }
+    }
+
+    return out;
+  } else if (implementation::validate_utf8(input, length)) {
+    return simdutf::encoding_type::UTF8;
+  } else {
+    return simdutf::encoding_type::unspecified;
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf8(const char *buf, size_t len) const noexcept {
+    avx512_utf8_checker checker{};
+    const char* ptr = buf;
+    const char* end = ptr + len;
+    for (; ptr + 64 <= end; ptr += 64) {
+        const __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+        checker.check_next_input(utf8);
+    }
+    {
+       const __m512i utf8 = _mm512_maskz_loadu_epi8((1ULL<<(end - ptr))-1, (const __m512i*)ptr);
+       checker.check_next_input(utf8);
+    }
+    checker.check_eof();
+    return ! checker.errors();
+}
+
+simdutf_warn_unused result implementation::validate_utf8_with_errors(const char *buf, size_t len) const noexcept {
+    avx512_utf8_checker checker{};
+    const char* ptr = buf;
+    const char* end = ptr + len;
+    size_t count{0};
+    for (; ptr + 64 <= end; ptr += 64) {
+      const __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+      checker.check_next_input(utf8);
+      if(checker.errors()) {
+        if (count != 0) { count--; } // Sometimes the error is only detected in the next chunk
+        result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(buf + count), len - count);
+        res.count += count;
+        return res;
+      }
+      count += 64;
+    }
+    {
+      const __m512i utf8 = _mm512_maskz_loadu_epi8((1ULL<<(end - ptr))-1, (const __m512i*)ptr);
+      checker.check_next_input(utf8);
+      if(checker.errors()) {
+        if (count != 0) { count--; } // Sometimes the error is only detected in the next chunk
+        result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(buf + count), len - count);
+        res.count += count;
+        return res;
+      } else {
+        return result(error_code::SUCCESS, len);
+      }
+    }
+}
+
+simdutf_warn_unused bool implementation::validate_ascii(const char *buf, size_t len) const noexcept {
+  const char* tail = icelake::validate_ascii(buf, len);
+  if (tail) {
+    return scalar::ascii::validate(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_ascii_with_errors(const char *buf, size_t len) const noexcept {
+  const char* buf_orig = buf;
+  const char* end = buf + len;
+  const __m512i ascii = _mm512_set1_epi8((uint8_t)0x80);
+  for (; buf + 64 <= end; buf += 64) {
+    const __m512i input = _mm512_loadu_si512((const __m512i*)buf);
+    __mmask64 notascii = _mm512_cmp_epu8_mask(input, ascii, _MM_CMPINT_NLT);
+    if(notascii) {
+      return result(error_code::TOO_LARGE, buf - buf_orig + _tzcnt_u64(notascii));
+    }
+  }
+  {
+    const __m512i input = _mm512_maskz_loadu_epi8((1ULL<<(end - buf))-1, (const __m512i*)buf);
+    __mmask64 notascii = _mm512_cmp_epu8_mask(input, ascii, _MM_CMPINT_NLT);
+    if(notascii) {
+      return result(error_code::TOO_LARGE, buf - buf_orig + _tzcnt_u64(notascii));
+    }
+  }
+  return result(error_code::SUCCESS, len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf16le(const char16_t *buf, size_t len) const noexcept {
+    const char16_t *end = buf + len;
+
+    for(;buf + 32 <= end; ) {
+      __m512i in = _mm512_loadu_si512((__m512i*)buf);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if(surrogates) {
+        __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0400)));
+        __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+        // high must be followed by low
+        if ((highsurrogates << 1) != lowsurrogates) {
+           return false;
+        }
+        bool ends_with_high = ((highsurrogates & 0x80000000) != 0);
+        if(ends_with_high) {
+          buf += 31; // advance only by 31 words so that we start with the high surrogate on the next round.
+        } else {
+          buf += 32;
+        }
+      } else {
+        buf += 32;
+      }
+    }
+    if(buf < end) {
+      __m512i in = _mm512_maskz_loadu_epi16((1<<(end-buf))-1,(__m512i*)buf);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if(surrogates) {
+        __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0400)));
+        __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+        // high must be followed by low
+        if ((highsurrogates << 1) != lowsurrogates) {
+           return false;
+        }
+      }
+    }
+    return true;
+}
+
+simdutf_warn_unused bool implementation::validate_utf16be(const char16_t *buf, size_t len) const noexcept {
+   const char16_t *end = buf + len;
+   const __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+    for(;buf + 32 <= end; ) {
+      __m512i in = _mm512_shuffle_epi8(_mm512_loadu_si512((__m512i*)buf), byteflip);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if(surrogates) {
+        __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0400)));
+        __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+        // high must be followed by low
+        if ((highsurrogates << 1) != lowsurrogates) {
+           return false;
+        }
+        bool ends_with_high = ((highsurrogates & 0x80000000) != 0);
+        if(ends_with_high) {
+          buf += 31; // advance only by 31 words so that we start with the high surrogate on the next round.
+        } else {
+          buf += 32;
+        }
+      } else {
+        buf += 32;
+      }
+    }
+    if(buf < end) {
+      __m512i in = _mm512_shuffle_epi8(_mm512_maskz_loadu_epi16((1<<(end-buf))-1,(__m512i*)buf), byteflip);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if(surrogates) {
+        __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0400)));
+        __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+        // high must be followed by low
+        if ((highsurrogates << 1) != lowsurrogates) {
+           return false;
+        }
+      }
+    }
+    return true;
+}
+
+simdutf_warn_unused result implementation::validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept {
+    const char16_t *start_buf = buf;
+    const char16_t *end = buf + len;
+    for(;buf + 32 <= end; ) {
+      __m512i in = _mm512_loadu_si512((__m512i*)buf);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if(surrogates) {
+        __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0400)));
+        __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+        // high must be followed by low
+        if ((highsurrogates << 1) != lowsurrogates) {
+          uint32_t extra_low = _tzcnt_u32(lowsurrogates &~(highsurrogates << 1));
+          uint32_t extra_high = _tzcnt_u32(highsurrogates &~(lowsurrogates >> 1));
+          return result(error_code::SURROGATE, (buf - start_buf) + (extra_low < extra_high ? extra_low : extra_high));
+        }
+        bool ends_with_high = ((highsurrogates & 0x80000000) != 0);
+        if(ends_with_high) {
+          buf += 31; // advance only by 31 words so that we start with the high surrogate on the next round.
+        } else {
+          buf += 32;
+        }
+      } else {
+        buf += 32;
+      }
+    }
+    if(buf < end) {
+      __m512i in = _mm512_maskz_loadu_epi16((1<<(end-buf))-1,(__m512i*)buf);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if(surrogates) {
+        __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0400)));
+        __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+        // high must be followed by low
+        if ((highsurrogates << 1) != lowsurrogates) {
+          uint32_t extra_low = _tzcnt_u32(lowsurrogates &~(highsurrogates << 1));
+          uint32_t extra_high = _tzcnt_u32(highsurrogates &~(lowsurrogates >> 1));
+          return result(error_code::SURROGATE, (buf - start_buf) + (extra_low < extra_high ? extra_low : extra_high));
+        }
+      }
+    }
+    return result(error_code::SUCCESS, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept {
+    const char16_t *start_buf = buf;
+    const char16_t *end = buf + len;
+    const __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+    for(;buf + 32 <= end; ) {
+      __m512i in = _mm512_shuffle_epi8(_mm512_loadu_si512((__m512i*)buf), byteflip);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if(surrogates) {
+        __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0400)));
+        __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+        // high must be followed by low
+        if ((highsurrogates << 1) != lowsurrogates) {
+          uint32_t extra_low = _tzcnt_u32(lowsurrogates &~(highsurrogates << 1));
+          uint32_t extra_high = _tzcnt_u32(highsurrogates &~(lowsurrogates >> 1));
+          return result(error_code::SURROGATE, (buf - start_buf) + (extra_low < extra_high ? extra_low : extra_high));
+        }
+        bool ends_with_high = ((highsurrogates & 0x80000000) != 0);
+        if(ends_with_high) {
+          buf += 31; // advance only by 31 words so that we start with the high surrogate on the next round.
+        } else {
+          buf += 32;
+        }
+      } else {
+        buf += 32;
+      }
+    }
+    if(buf < end) {
+      __m512i in = _mm512_shuffle_epi8(_mm512_maskz_loadu_epi16((1<<(end-buf))-1,(__m512i*)buf), byteflip);
+      __m512i diff = _mm512_sub_epi16(in, _mm512_set1_epi16(uint16_t(0xD800)));
+      __mmask32 surrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0800)));
+      if(surrogates) {
+        __mmask32 highsurrogates = _mm512_cmplt_epu16_mask(diff, _mm512_set1_epi16(uint16_t(0x0400)));
+        __mmask32 lowsurrogates = surrogates ^ highsurrogates;
+        // high must be followed by low
+        if ((highsurrogates << 1) != lowsurrogates) {
+          uint32_t extra_low = _tzcnt_u32(lowsurrogates &~(highsurrogates << 1));
+          uint32_t extra_high = _tzcnt_u32(highsurrogates &~(lowsurrogates >> 1));
+          return result(error_code::SURROGATE, (buf - start_buf) + (extra_low < extra_high ? extra_low : extra_high));
+        }
+      }
+    }
+    return result(error_code::SUCCESS, len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf32(const char32_t *buf, size_t len) const noexcept {
+  const char32_t * tail = icelake::validate_utf32(buf, len);
+  if (tail) {
+    return scalar::utf32::validate(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept {
+
+    const char32_t* end = len >= 16 ? buf + len - 16 : nullptr;
+    const char32_t* buf_orig = buf;
+    while (buf <= end) {
+      __m512i utf32 = _mm512_loadu_si512((const __m512i*)buf);
+      __mmask16 outside_range = _mm512_cmp_epu32_mask(utf32, _mm512_set1_epi32(0x10ffff),
+                                _MM_CMPINT_GT);
+      if (outside_range) {
+        return result(error_code::TOO_LARGE, buf - buf_orig + _tzcnt_u32(outside_range));
+      }
+
+      __m512i utf32_off = _mm512_add_epi32(utf32, _mm512_set1_epi32(0xffff2000));
+
+      __mmask16 surrogate_range = _mm512_cmp_epu32_mask(utf32_off, _mm512_set1_epi32(0xfffff7ff),
+                                _MM_CMPINT_GT);
+      if (surrogate_range) {
+        return result(error_code::SURROGATE, buf - buf_orig + _tzcnt_u32(surrogate_range));
+      }
+      buf += 16;
+    }
+    if(buf < buf_orig + len) {
+      __m512i utf32 = _mm512_maskz_loadu_epi32(__mmask16((1<<(buf_orig + len - buf))-1),(const __m512i*)buf);
+      __mmask16 outside_range = _mm512_cmp_epu32_mask(utf32, _mm512_set1_epi32(0x10ffff),
+                                _MM_CMPINT_GT);
+      if (outside_range) {
+        return result(error_code::TOO_LARGE, buf - buf_orig + _tzcnt_u32(outside_range));
+      }
+      __m512i utf32_off = _mm512_add_epi32(utf32, _mm512_set1_epi32(0xffff2000));
+
+      __mmask16 surrogate_range = _mm512_cmp_epu32_mask(utf32_off, _mm512_set1_epi32(0xfffff7ff),
+                                _MM_CMPINT_GT);
+      if (surrogate_range) {
+        return result(error_code::SURROGATE, buf - buf_orig + _tzcnt_u32(surrogate_range));
+      }
+    }
+
+    return result(error_code::SUCCESS, len);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16le(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16_result ret = fast_avx512_convert_utf8_to_utf16<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.second == nullptr) {
+    return 0;
+  }
+  return ret.second - utf16_output;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16be(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16_result ret = fast_avx512_convert_utf8_to_utf16<endianness::BIG>(buf, len, utf16_output);
+  if (ret.second == nullptr) {
+    return 0;
+  }
+  return ret.second - utf16_output;
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16le_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+   return fast_avx512_convert_utf8_to_utf16_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16be_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+   return fast_avx512_convert_utf8_to_utf16_with_errors<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16le(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16_result ret = icelake::valid_utf8_to_fixed_length<endianness::LITTLE, char16_t>(buf, len, utf16_output);
+  size_t saved_bytes = ret.second - utf16_output;
+  const char* end = buf + len;
+  if (ret.first == end) {
+    return saved_bytes;
+  }
+
+  // Note: AVX512 procedure looks up 4 bytes forward, and
+  //       correctly converts multi-byte chars even if their
+  //       continuation bytes lie outsiede 16-byte window.
+  //       It meas, we have to skip continuation bytes from
+  //       the beginning ret.first, as they were already consumed.
+  while (ret.first != end && ((uint8_t(*ret.first) & 0xc0) == 0x80)) {
+      ret.first += 1;
+  }
+
+  if (ret.first != end) {
+    const size_t scalar_saved_bytes = scalar::utf8_to_utf16::convert_valid<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16be(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16_result ret = icelake::valid_utf8_to_fixed_length<endianness::BIG, char16_t>(buf, len, utf16_output);
+  size_t saved_bytes = ret.second - utf16_output;
+  const char* end = buf + len;
+  if (ret.first == end) {
+    return saved_bytes;
+  }
+
+  // Note: AVX512 procedure looks up 4 bytes forward, and
+  //       correctly converts multi-byte chars even if their
+  //       continuation bytes lie outsiede 16-byte window.
+  //       It meas, we have to skip continuation bytes from
+  //       the beginning ret.first, as they were already consumed.
+  while (ret.first != end && ((uint8_t(*ret.first) & 0xc0) == 0x80)) {
+      ret.first += 1;
+  }
+
+  if (ret.first != end) {
+    const size_t scalar_saved_bytes = scalar::utf8_to_utf16::convert_valid<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+
+  return saved_bytes;
+}
+
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf32(const char* buf, size_t len, char32_t* utf32_out) const noexcept {
+  uint32_t * utf32_output = reinterpret_cast<uint32_t *>(utf32_out);
+  utf8_to_utf32_result ret = icelake::validating_utf8_to_fixed_length<endianness::LITTLE, uint32_t>(buf, len, utf32_output);
+  if (ret.second == nullptr)
+    return 0;
+
+  size_t saved_bytes = ret.second - utf32_output;
+  const char* end = buf + len;
+  if (ret.first == end) {
+    return saved_bytes;
+  }
+
+  // Note: the AVX512 procedure looks up 4 bytes forward, and
+  //       correctly converts multi-byte chars even if their
+  //       continuation bytes lie outside 16-byte window.
+  //       It means, we have to skip continuation bytes from
+  //       the beginning ret.first, as they were already consumed.
+  while (ret.first != end and ((uint8_t(*ret.first) & 0xc0) == 0x80)) {
+      ret.first += 1;
+  }
+
+  if (ret.first != end) {
+    const size_t scalar_saved_bytes = scalar::utf8_to_utf32::convert(
+                                        ret.first, len - (ret.first - buf), utf32_out + saved_bytes);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf32_with_errors(const char* buf, size_t len, char32_t* utf32) const noexcept {
+  uint32_t * utf32_output = reinterpret_cast<uint32_t *>(utf32);
+  auto ret = icelake::validating_utf8_to_fixed_length_with_constant_checks<endianness::LITTLE, uint32_t>(buf, len, utf32_output);
+  if (!std::get<2>(ret)) {
+    result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(std::get<0>(ret), len - (std::get<0>(ret) - buf), reinterpret_cast<char32_t *>(std::get<1>(ret)));
+    res.count += (std::get<0>(ret) - buf);
+    return res;
+  }
+  size_t saved_bytes = std::get<1>(ret) - utf32_output;
+  const char* end = buf + len;
+  if (std::get<0>(ret) == end) {
+    return {simdutf::SUCCESS, saved_bytes};
+  }
+
+  // Note: the AVX512 procedure looks up 4 bytes forward, and
+  //       correctly converts multi-byte chars even if their
+  //       continuation bytes lie outside 16-byte window.
+  //       It means, we have to skip continuation bytes from
+  //       the beginning ret.first, as they were already consumed.
+  while (std::get<0>(ret) != end and ((uint8_t(*std::get<0>(ret)) & 0xc0) == 0x80)) {
+      std::get<0>(ret) += 1;
+  }
+
+  if (std::get<0>(ret) != end) {
+    auto scalar_result = scalar::utf8_to_utf32::convert_with_errors(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), reinterpret_cast<char32_t *>(utf32_output) + saved_bytes);
+    if (scalar_result.error != simdutf::SUCCESS) {
+      scalar_result.count +=  (std::get<0>(ret) - buf);
+    } else {
+      scalar_result.count += saved_bytes;
+    }
+    return scalar_result;
+  }
+
+  return {simdutf::SUCCESS, size_t(std::get<1>(ret) - utf32_output)};
+}
+
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf32(const char* buf, size_t len, char32_t* utf32_out) const noexcept {
+  uint32_t * utf32_output = reinterpret_cast<uint32_t *>(utf32_out);
+  utf8_to_utf32_result ret = icelake::valid_utf8_to_fixed_length<endianness::LITTLE, uint32_t>(buf, len, utf32_output);
+  size_t saved_bytes = ret.second - utf32_output;
+  const char* end = buf + len;
+  if (ret.first == end) {
+    return saved_bytes;
+  }
+
+  // Note: AVX512 procedure looks up 4 bytes forward, and
+  //       correctly converts multi-byte chars even if their
+  //       continuation bytes lie outsiede 16-byte window.
+  //       It meas, we have to skip continuation bytes from
+  //       the beginning ret.first, as they were already consumed.
+  while (ret.first != end && ((uint8_t(*ret.first) & 0xc0) == 0x80)) {
+      ret.first += 1;
+  }
+
+  if (ret.first != end) {
+    const size_t scalar_saved_bytes = scalar::utf8_to_utf32::convert_valid(
+                                        ret.first, len - (ret.first - buf), utf32_out + saved_bytes);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  size_t outlen;
+  size_t inlen = utf16_to_utf8_avx512i<endianness::LITTLE>(buf, len, (unsigned char*)utf8_output, &outlen);
+  if(inlen != len) { return 0; }
+  return outlen;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  size_t outlen;
+  size_t inlen = utf16_to_utf8_avx512i<endianness::BIG>(buf, len, (unsigned char*)utf8_output, &outlen);
+  if(inlen != len) { return 0; }
+  return outlen;
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  size_t outlen;
+  size_t inlen = utf16_to_utf8_avx512i<endianness::LITTLE>(buf, len, (unsigned char*)utf8_output, &outlen);
+  if(inlen != len) {
+    result res = scalar::utf16_to_utf8::convert_with_errors<endianness::LITTLE>(buf + inlen, len - outlen, utf8_output + outlen);
+    res.count += inlen;
+    return res;
+  }
+  return {simdutf::SUCCESS, outlen};
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  size_t outlen;
+  size_t inlen = utf16_to_utf8_avx512i<endianness::BIG>(buf, len, (unsigned char*)utf8_output, &outlen);
+  if(inlen != len) {
+    result res = scalar::utf16_to_utf8::convert_with_errors<endianness::BIG>(buf + inlen, len - outlen, utf8_output + outlen);
+    res.count += inlen;
+    return res;
+  }
+  return {simdutf::SUCCESS, outlen};
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf16le_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf16be_to_utf8(buf, len, utf8_output);
+}
+
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char32_t*, char*> ret = avx512_convert_utf32_to_utf8(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf8::convert(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = icelake::avx512_convert_utf32_to_utf8_with_errors(buf, len, utf8_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf8::convert_with_errors(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf32_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  std::pair<const char32_t*, char16_t*> ret = avx512_convert_utf32_to_utf16<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf16_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf16::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  std::pair<const char32_t*, char16_t*> ret = avx512_convert_utf32_to_utf16<endianness::BIG>(buf, len, utf16_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf16_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf16::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16le_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char16_t*> ret = avx512_convert_utf32_to_utf16_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf16::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf16_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16be_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char16_t*> ret = avx512_convert_utf32_to_utf16_with_errors<endianness::BIG>(buf, len, utf16_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf16::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf16_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return convert_utf32_to_utf16le(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return convert_utf32_to_utf16be(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::tuple<const char16_t*, char32_t*, bool> ret = icelake::convert_utf16_to_utf32<endianness::LITTLE>(buf, len, utf32_output);
+  if (!std::get<2>(ret)) { return 0; }
+  size_t saved_bytes = std::get<1>(ret) - utf32_output;
+  if (std::get<0>(ret) != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::LITTLE>(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), std::get<1>(ret));
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::tuple<const char16_t*, char32_t*, bool> ret = icelake::convert_utf16_to_utf32<endianness::BIG>(buf, len, utf32_output);
+  if (!std::get<2>(ret)) { return 0; }
+  size_t saved_bytes = std::get<1>(ret) - utf32_output;
+  if (std::get<0>(ret) != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::BIG>(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), std::get<1>(ret));
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::tuple<const char16_t*, char32_t*, bool> ret = icelake::convert_utf16_to_utf32<endianness::LITTLE>(buf, len, utf32_output);
+  if (!std::get<2>(ret)) {
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::LITTLE>(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), std::get<1>(ret));
+    scalar_res.count += (std::get<0>(ret) - buf);
+    return scalar_res;
+  }
+  size_t saved_bytes = std::get<1>(ret) - utf32_output;
+  if (std::get<0>(ret) != buf + len) {
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::LITTLE>(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), std::get<1>(ret));
+    if (scalar_res.error) {
+      scalar_res.count += (std::get<0>(ret) - buf);
+      return scalar_res;
+    } else {
+      scalar_res.count += saved_bytes;
+      return scalar_res;
+    }
+  }
+  return simdutf::result(simdutf::SUCCESS, saved_bytes);
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::tuple<const char16_t*, char32_t*, bool> ret = icelake::convert_utf16_to_utf32<endianness::BIG>(buf, len, utf32_output);
+  if (!std::get<2>(ret)) {
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::BIG>(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), std::get<1>(ret));
+    scalar_res.count += (std::get<0>(ret) - buf);
+    return scalar_res;
+  }
+  size_t saved_bytes = std::get<1>(ret) - utf32_output;
+  if (std::get<0>(ret) != buf + len) {
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::BIG>(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), std::get<1>(ret));
+    if (scalar_res.error) {
+      scalar_res.count += (std::get<0>(ret) - buf);
+      return scalar_res;
+    } else {
+      scalar_res.count += saved_bytes;
+      return scalar_res;
+    }
+  }
+  return simdutf::result(simdutf::SUCCESS, saved_bytes);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::tuple<const char16_t*, char32_t*, bool> ret = icelake::convert_utf16_to_utf32<endianness::LITTLE>(buf, len, utf32_output);
+  if (!std::get<2>(ret)) { return 0; }
+  size_t saved_bytes = std::get<1>(ret) - utf32_output;
+  if (std::get<0>(ret) != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::LITTLE>(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), std::get<1>(ret));
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::tuple<const char16_t*, char32_t*, bool> ret = icelake::convert_utf16_to_utf32<endianness::BIG>(buf, len, utf32_output);
+  if (!std::get<2>(ret)) { return 0; }
+  size_t saved_bytes = std::get<1>(ret) - utf32_output;
+  if (std::get<0>(ret) != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::BIG>(
+                                        std::get<0>(ret), len - (std::get<0>(ret) - buf), std::get<1>(ret));
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+void implementation::change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) const noexcept {
+  size_t pos = 0;
+  const __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+  while (pos + 32 <= length) {
+    __m512i utf16 = _mm512_loadu_si512((const __m512i*)(input + pos));
+    utf16 = _mm512_shuffle_epi8(utf16, byteflip);
+    _mm512_storeu_si512(output + pos, utf16);
+    pos += 32;
+  }
+  if(pos < length) {
+    __mmask32 m((1<< (length - pos))-1);
+    __m512i utf16 = _mm512_maskz_loadu_epi16(m, (const __m512i*)(input + pos));
+    utf16 = _mm512_shuffle_epi8(utf16, byteflip);
+    _mm512_mask_storeu_epi16(output + pos, m, utf16);
+  }
+}
+
+
+simdutf_warn_unused size_t implementation::count_utf16le(const char16_t * input, size_t length) const noexcept {
+  const char16_t* end = length >= 32 ? input + length - 32 : nullptr;
+  const char16_t* ptr = input;
+
+  const __m512i low = _mm512_set1_epi16((uint16_t)0xdc00);
+  const __m512i high = _mm512_set1_epi16((uint16_t)0xdfff);
+
+  size_t count{0};
+
+  while (ptr <= end) {
+    __m512i utf16 = _mm512_loadu_si512((const __m512i*)ptr);
+    ptr += 32;
+    uint64_t not_high_surrogate = static_cast<uint64_t>(_mm512_cmpgt_epu16_mask(utf16, high) | _mm512_cmplt_epu16_mask(utf16, low));
+    count += count_ones(not_high_surrogate);
+  }
+
+  return count + scalar::utf16::count_code_points<endianness::LITTLE>(ptr, length - (ptr - input));
+}
+
+simdutf_warn_unused size_t implementation::count_utf16be(const char16_t * input, size_t length) const noexcept {
+  const char16_t* end = length >= 32 ? input + length - 32 : nullptr;
+  const char16_t* ptr = input;
+
+  const __m512i low = _mm512_set1_epi16((uint16_t)0xdc00);
+  const __m512i high = _mm512_set1_epi16((uint16_t)0xdfff);
+
+  size_t count{0};
+  const __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+  while (ptr <= end) {
+    __m512i utf16 = _mm512_shuffle_epi8(_mm512_loadu_si512((__m512i*)ptr), byteflip);
+    ptr += 32;
+    uint64_t not_high_surrogate = static_cast<uint64_t>(_mm512_cmpgt_epu16_mask(utf16, high) | _mm512_cmplt_epu16_mask(utf16, low));
+    count += count_ones(not_high_surrogate);
+  }
+
+  return count + scalar::utf16::count_code_points<endianness::BIG>(ptr, length - (ptr - input));
+}
+
+
+simdutf_warn_unused size_t implementation::count_utf8(const char * input, size_t length) const noexcept {
+  const char* end = length >= 64 ? input + length - 64 : nullptr;
+  const char* ptr = input;
+
+  const __m512i continuation = _mm512_set1_epi8(char(0b10111111));
+
+  size_t count{0};
+
+  while (ptr <= end) {
+    __m512i utf8 = _mm512_loadu_si512((const __m512i*)ptr);
+    ptr += 64;
+    uint64_t continuation_bitmask = static_cast<uint64_t>(_mm512_cmple_epi8_mask(utf8, continuation));
+    count += 64 - count_ones(continuation_bitmask);
+  }
+
+  return count + scalar::utf8::count_code_points(ptr, length - (ptr - input));
+}
+
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  const char16_t* end = length >= 32 ? input + length - 32 : nullptr;
+  const char16_t* ptr = input;
+
+  const __m512i v_007f = _mm512_set1_epi16((uint16_t)0x007f);
+  const __m512i v_07ff = _mm512_set1_epi16((uint16_t)0x07ff);
+  const __m512i v_dfff = _mm512_set1_epi16((uint16_t)0xdfff);
+  const __m512i v_d800 = _mm512_set1_epi16((uint16_t)0xd800);
+
+  size_t count{0};
+
+  while (ptr <= end) {
+    __m512i utf16 = _mm512_loadu_si512((const __m512i*)ptr);
+    ptr += 32;
+    __mmask32 ascii_bitmask = _mm512_cmple_epu16_mask(utf16, v_007f);
+    __mmask32 two_bytes_bitmask = _mm512_mask_cmple_epu16_mask(~ascii_bitmask, utf16, v_07ff);
+    __mmask32 not_one_two_bytes = ~(ascii_bitmask | two_bytes_bitmask);
+    __mmask32 surrogates_bitmask = _mm512_mask_cmple_epu16_mask(not_one_two_bytes, utf16, v_dfff) & _mm512_mask_cmpge_epu16_mask(not_one_two_bytes, utf16, v_d800);
+
+    size_t ascii_count = count_ones(ascii_bitmask);
+    size_t two_bytes_count = count_ones(two_bytes_bitmask);
+    size_t surrogate_bytes_count = count_ones(surrogates_bitmask);
+    size_t three_bytes_count = 32 - ascii_count - two_bytes_count - surrogate_bytes_count;
+
+    count += ascii_count + 2*two_bytes_count + 3*three_bytes_count + 2*surrogate_bytes_count;
+  }
+
+  return count + scalar::utf16::utf8_length_from_utf16<endianness::LITTLE>(ptr, length - (ptr - input));
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  const char16_t* end = length >= 32 ? input + length - 32 : nullptr;
+  const char16_t* ptr = input;
+
+  const __m512i v_007f = _mm512_set1_epi16((uint16_t)0x007f);
+  const __m512i v_07ff = _mm512_set1_epi16((uint16_t)0x07ff);
+  const __m512i v_dfff = _mm512_set1_epi16((uint16_t)0xdfff);
+  const __m512i v_d800 = _mm512_set1_epi16((uint16_t)0xd800);
+
+  size_t count{0};
+  const __m512i byteflip = _mm512_setr_epi64(
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809,
+            0x0607040502030001,
+            0x0e0f0c0d0a0b0809
+        );
+  while (ptr <= end) {
+    __m512i utf16 = _mm512_loadu_si512((const __m512i*)ptr);
+    utf16 = _mm512_shuffle_epi8(utf16, byteflip);
+    ptr += 32;
+    __mmask32 ascii_bitmask = _mm512_cmple_epu16_mask(utf16, v_007f);
+    __mmask32 two_bytes_bitmask = _mm512_mask_cmple_epu16_mask(~ascii_bitmask, utf16, v_07ff);
+    __mmask32 not_one_two_bytes = ~(ascii_bitmask | two_bytes_bitmask);
+    __mmask32 surrogates_bitmask = _mm512_mask_cmple_epu16_mask(not_one_two_bytes, utf16, v_dfff) & _mm512_mask_cmpge_epu16_mask(not_one_two_bytes, utf16, v_d800);
+
+    size_t ascii_count = count_ones(ascii_bitmask);
+    size_t two_bytes_count = count_ones(two_bytes_bitmask);
+    size_t surrogate_bytes_count = count_ones(surrogates_bitmask);
+    size_t three_bytes_count = 32 - ascii_count - two_bytes_count - surrogate_bytes_count;
+    count += ascii_count + 2*two_bytes_count + 3*three_bytes_count + 2*surrogate_bytes_count;
+  }
+
+  return count + scalar::utf16::utf8_length_from_utf16<endianness::BIG>(ptr, length - (ptr - input));
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return implementation::count_utf16le(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return implementation::count_utf16be(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf8(const char * input, size_t length) const noexcept {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 64 <= length; pos += 64) {
+      __m512i utf8 = _mm512_loadu_si512((const __m512i*)(input+pos));
+      uint64_t utf8_continuation_mask = _mm512_cmple_epi8_mask(utf8, _mm512_set1_epi8(-65+1));
+      // We count one word for anything that is not a continuation (so
+      // leading bytes).
+      count += 64 - count_ones(utf8_continuation_mask);
+      uint64_t utf8_4byte = _mm512_cmpge_epu8_mask(utf8, _mm512_set1_epi8(int8_t(240)));
+      count += count_ones(utf8_4byte);
+    }
+    return count + scalar::utf8::utf16_length_from_utf8(input + pos, length - pos);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  const char32_t* end = length >= 16 ? input + length - 16 : nullptr;
+  const char32_t* ptr = input;
+
+  const __m512i v_0000_007f = _mm512_set1_epi32((uint32_t)0x7f);
+  const __m512i v_0000_07ff = _mm512_set1_epi32((uint32_t)0x7ff);
+  const __m512i v_0000_ffff = _mm512_set1_epi32((uint32_t)0x0000ffff);
+
+  size_t count{0};
+
+  while (ptr <= end) {
+    __m512i utf32 = _mm512_loadu_si512((const __m512i*)ptr);
+    ptr += 16;
+    __mmask16 ascii_bitmask = _mm512_cmple_epu32_mask(utf32, v_0000_007f);
+    __mmask16 two_bytes_bitmask = _mm512_mask_cmple_epu32_mask(_knot_mask16(ascii_bitmask), utf32, v_0000_07ff);
+    __mmask16 three_bytes_bitmask = _mm512_mask_cmple_epu32_mask(_knot_mask16(_mm512_kor(ascii_bitmask, two_bytes_bitmask)), utf32, v_0000_ffff);
+
+    size_t ascii_count = count_ones(ascii_bitmask);
+    size_t two_bytes_count = count_ones(two_bytes_bitmask);
+    size_t three_bytes_count = count_ones(three_bytes_bitmask);
+    size_t four_bytes_count = 16 - ascii_count - two_bytes_count - three_bytes_count;
+    count += ascii_count + 2*two_bytes_count + 3*three_bytes_count + 4*four_bytes_count;
+  }
+
+  return count + scalar::utf32::utf8_length_from_utf32(ptr, length - (ptr - input));
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  const char32_t* end = length >= 16 ? input + length - 16 : nullptr;
+  const char32_t* ptr = input;
+
+  const __m512i v_0000_ffff = _mm512_set1_epi32((uint32_t)0x0000ffff);
+
+  size_t count{0};
+
+  while (ptr <= end) {
+    __m512i utf32 = _mm512_loadu_si512((const __m512i*)ptr);
+    ptr += 16;
+    __mmask16 surrogates_bitmask = _mm512_cmpgt_epu32_mask(utf32, v_0000_ffff);
+
+    count += 16 + count_ones(surrogates_bitmask);
+  }
+
+  return count + scalar::utf32::utf16_length_from_utf32(ptr, length - (ptr - input));
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf8(const char * input, size_t length) const noexcept {
+  return implementation::count_utf8(input, length);
+}
+
+} // namespace icelake
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/icelake/end.h
+/* begin file src/simdutf/icelake/end.h */
+SIMDUTF_UNTARGET_REGION
+/* end file src/simdutf/icelake/end.h */
+/* end file src/icelake/implementation.cpp */
+#endif
+#if SIMDUTF_IMPLEMENTATION_HASWELL
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/implementation.cpp
+/* begin file src/haswell/implementation.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/begin.h
+/* begin file src/simdutf/haswell/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "haswell"
+// #define SIMDUTF_IMPLEMENTATION haswell
+SIMDUTF_TARGET_HASWELL
+/* end file src/simdutf/haswell/begin.h */
+namespace simdutf {
+namespace haswell {
+namespace {
+#ifndef SIMDUTF_HASWELL_H
+#error "haswell.h must be included"
+#endif
+using namespace simd;
+
+
+simdutf_really_inline bool is_ascii(const simd8x64<uint8_t>& input) {
+  return input.reduce_or().is_ascii();
+}
+
+simdutf_unused simdutf_really_inline simd8<bool> must_be_continuation(const simd8<uint8_t> prev1, const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
+  simd8<uint8_t> is_second_byte = prev1.saturating_sub(0b11000000u-1); // Only 11______ will be > 0
+  simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0b11100000u-1); // Only 111_____ will be > 0
+  simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0b11110000u-1); // Only 1111____ will be > 0
+  // Caller requires a bool (all 1's). All values resulting from the subtraction will be <= 64, so signed comparison is fine.
+  return simd8<int8_t>(is_second_byte | is_third_byte | is_fourth_byte) > int8_t(0);
+}
+
+simdutf_really_inline simd8<bool> must_be_2_3_continuation(const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
+  simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0b11100000u-1); // Only 111_____ will be > 0
+  simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0b11110000u-1); // Only 1111____ will be > 0
+  // Caller requires a bool (all 1's). All values resulting from the subtraction will be <= 64, so signed comparison is fine.
+  return simd8<int8_t>(is_third_byte | is_fourth_byte) > int8_t(0);
+}
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_detect_encodings.cpp
+/* begin file src/haswell/avx2_detect_encodings.cpp */
+template<class checker>
+// len is known to be a multiple of 2 when this is called
+int avx2_detect_encodings(const char * buf, size_t len) {
+    const char* start = buf;
+    const char* end = buf + len;
+
+    bool is_utf8 = true;
+    bool is_utf16 = true;
+    bool is_utf32 = true;
+
+    int out = 0;
+
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+
+    __m256i currentmax = _mm256_setzero_si256();
+
+    checker check{};
+
+    while(buf + 64 <= end) {
+        __m256i in = _mm256_loadu_si256((__m256i*)buf);
+        __m256i nextin = _mm256_loadu_si256((__m256i*)buf+1);
+
+        const auto u0 = simd16<uint16_t>(in);
+        const auto u1 = simd16<uint16_t>(nextin);
+
+        const auto v0 = u0.shr<8>();
+        const auto v1 = u1.shr<8>();
+
+        const auto in16 = simd16<uint16_t>::pack(v0, v1);
+
+        const auto surrogates_wordmask0 = (in16 & v_f8) == v_d8;
+        uint32_t surrogates_bitmask0 = surrogates_wordmask0.to_bitmask();
+
+        // Check for surrogates
+        if (surrogates_bitmask0 != 0x0) {
+            // Cannot be UTF8
+            is_utf8 = false;
+            // Can still be either UTF-16LE or UTF-32LE depending on the positions of the surrogates
+            // To be valid UTF-32LE, a surrogate cannot be in the two most significant bytes of any 32-bit word.
+            // On the other hand, to be valid UTF-16LE, at least one surrogate must be in the two most significant
+            // bytes of a 32-bit word since they always come in pairs in UTF-16LE.
+            // Note that we always proceed in multiple of 4 before this point so there is no offset in 32-bit words.
+
+            if ((surrogates_bitmask0 & 0xaaaaaaaa) != 0) {
+                is_utf32 = false;
+                // Code from avx2_validate_utf16le.cpp
+                const char16_t * input = reinterpret_cast<const char16_t*>(buf);
+                const char16_t* end16 = reinterpret_cast<const char16_t*>(start) + len/2;
+
+                const auto v_fc = simd8<uint8_t>::splat(0xfc);
+                const auto v_dc = simd8<uint8_t>::splat(0xdc);
+
+                const uint32_t V0 = ~surrogates_bitmask0;
+
+                const auto    vH0 = (in16 & v_fc) == v_dc;
+                const uint32_t H0 = vH0.to_bitmask();
+
+                const uint32_t L0 = ~H0 & surrogates_bitmask0;
+
+                const uint32_t a0 = L0 & (H0 >> 1);
+                const uint32_t b0 = a0 << 1;
+                const uint32_t c0 = V0 | a0 | b0;
+
+                if (c0 == 0xffffffff) {
+                    input += simd16<uint16_t>::ELEMENTS * 2;
+                } else if (c0 == 0x7fffffff) {
+                    input += simd16<uint16_t>::ELEMENTS * 2 - 1;
+                } else {
+                    return simdutf::encoding_type::unspecified;
+                }
+
+                while (input + simd16<uint16_t>::ELEMENTS * 2 < end16) {
+                    const auto in0 = simd16<uint16_t>(input);
+                    const auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::ELEMENTS);
+
+                    const auto t0 = in0.shr<8>();
+                    const auto t1 = in1.shr<8>();
+
+                    const auto in_16 = simd16<uint16_t>::pack(t0, t1);
+
+                    const auto surrogates_wordmask = (in_16 & v_f8) == v_d8;
+                    const uint32_t surrogates_bitmask = surrogates_wordmask.to_bitmask();
+                    if (surrogates_bitmask == 0x0) {
+                        input += simd16<uint16_t>::ELEMENTS * 2;
+                    } else {
+                        const uint32_t V = ~surrogates_bitmask;
+
+                        const auto    vH = (in_16 & v_fc) == v_dc;
+                        const uint32_t H = vH.to_bitmask();
+
+                        const uint32_t L = ~H & surrogates_bitmask;
+
+                        const uint32_t a = L & (H >> 1);
+
+                        const uint32_t b = a << 1;
+
+                        const uint32_t c = V | a | b;
+
+                        if (c == 0xffffffff) {
+                            input += simd16<uint16_t>::ELEMENTS * 2;
+                        } else if (c == 0x7fffffff) {
+                            input += simd16<uint16_t>::ELEMENTS * 2 - 1;
+                        } else {
+                            return simdutf::encoding_type::unspecified;
+                        }
+                    }
+                }
+            } else {
+                is_utf16 = false;
+                // Check for UTF-32LE
+                if (len % 4 == 0) {
+                    const char32_t * input = reinterpret_cast<const char32_t*>(buf);
+                    const char32_t* end32 = reinterpret_cast<const char32_t*>(start) + len/4;
+
+                    // Must start checking for surrogates
+                    __m256i currentoffsetmax = _mm256_setzero_si256();
+                    const __m256i offset = _mm256_set1_epi32(0xffff2000);
+                    const __m256i standardoffsetmax = _mm256_set1_epi32(0xfffff7ff);
+
+                    currentmax = _mm256_max_epu32(in, currentmax);
+                    currentmax = _mm256_max_epu32(nextin, currentmax);
+
+                    currentoffsetmax = _mm256_max_epu32(_mm256_add_epi32(in, offset), currentoffsetmax);
+                    currentoffsetmax = _mm256_max_epu32(_mm256_add_epi32(nextin, offset), currentoffsetmax);
+
+                    while (input + 8 < end32) {
+                        const __m256i in32 = _mm256_loadu_si256((__m256i *)input);
+                        currentmax = _mm256_max_epu32(in32,currentmax);
+                        currentoffsetmax = _mm256_max_epu32(_mm256_add_epi32(in32, offset), currentoffsetmax);
+                        input += 8;
+                    }
+
+                    __m256i forbidden_words = _mm256_xor_si256(_mm256_max_epu32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+                    if(_mm256_testz_si256(forbidden_words, forbidden_words) == 0) {
+                        return simdutf::encoding_type::unspecified;
+                    }
+                } else {
+                    return simdutf::encoding_type::unspecified;
+                }
+            }
+            break;
+        }
+        // If no surrogate, validate under other encodings as well
+
+        // UTF-32LE validation
+        currentmax = _mm256_max_epu32(in, currentmax);
+        currentmax = _mm256_max_epu32(nextin, currentmax);
+
+        // UTF-8 validation
+        // Relies on ../generic/utf8_validation/utf8_lookup4_algorithm.h
+        simd::simd8x64<uint8_t> in8(in, nextin);
+        check.check_next_input(in8);
+
+        buf += 64;
+    }
+
+    // Check which encodings are possible
+
+    if (is_utf8) {
+        if (static_cast<size_t>(buf - start) != len) {
+            uint8_t block[64]{};
+            std::memset(block, 0x20, 64);
+            std::memcpy(block, buf, len - (buf - start));
+            simd::simd8x64<uint8_t> in(block);
+            check.check_next_input(in);
+        }
+        if (!check.errors()) {
+            out |= simdutf::encoding_type::UTF8;
+        }
+    }
+
+    if (is_utf16 && scalar::utf16::validate<endianness::LITTLE>(reinterpret_cast<const char16_t*>(buf), (len - (buf - start))/2)) {
+        out |= simdutf::encoding_type::UTF16_LE;
+    }
+
+    if (is_utf32 && (len % 4 == 0)) {
+        const __m256i standardmax = _mm256_set1_epi32(0x10ffff);
+        __m256i is_zero = _mm256_xor_si256(_mm256_max_epu32(currentmax, standardmax), standardmax);
+        if (_mm256_testz_si256(is_zero, is_zero) == 1 && scalar::utf32::validate(reinterpret_cast<const char32_t*>(buf), (len - (buf - start))/4)) {
+            out |= simdutf::encoding_type::UTF32_LE;
+        }
+    }
+
+    return out;
+}
+/* end file src/haswell/avx2_detect_encodings.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_validate_utf16.cpp
+/* begin file src/haswell/avx2_validate_utf16.cpp */
+/*
+    In UTF-16 words in range 0xD800 to 0xDFFF have special meaning.
+
+    In a vectorized algorithm we want to examine the most significant
+    nibble in order to select a fast path. If none of highest nibbles
+    are 0xD (13), than we are sure that UTF-16 chunk in a vector
+    register is valid.
+
+    Let us analyze what we need to check if the nibble is 0xD. The
+    value of the preceding nibble determines what we have:
+
+    0xd000 .. 0xd7ff - a valid word
+    0xd800 .. 0xdbff - low surrogate
+    0xdc00 .. 0xdfff - high surrogate
+
+    Other constraints we have to consider:
+    - there must not be two consecutive low surrogates (0xd800 .. 0xdbff)
+    - there must not be two consecutive high surrogates (0xdc00 .. 0xdfff)
+    - there must not be sole low surrogate nor high surrogate
+
+    We're going to build three bitmasks based on the 3rd nibble:
+    - V = valid word,
+    - L = low surrogate (0xd800 .. 0xdbff)
+    - H = high surrogate (0xdc00 .. 0xdfff)
+
+      0   1   2   3   4   5   6   7    <--- word index
+    [ V | L | H | L | H | V | V | L ]
+      1   0   0   0   0   1   1   0     - V = valid masks
+      0   1   0   1   0   0   0   1     - L = low surrogate
+      0   0   1   0   1   0   0   0     - H high surrogate
+
+
+      1   0   0   0   0   1   1   0   V = valid masks
+      0   1   0   1   0   0   0   0   a = L & (H >> 1)
+      0   0   1   0   1   0   0   0   b = a << 1
+      1   1   1   1   1   1   1   0   c = V | a | b
+                                  ^
+                                  the last bit can be zero, we just consume 7 words
+                                  and recheck this word in the next iteration
+*/
+
+/* Returns:
+   - pointer to the last unprocessed character (a scalar fallback should check the rest);
+   - nullptr if an error was detected.
+*/
+template <endianness big_endian>
+const char16_t* avx2_validate_utf16(const char16_t* input, size_t size) {
+    const char16_t* end = input + size;
+
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+    const auto v_fc = simd8<uint8_t>::splat(0xfc);
+    const auto v_dc = simd8<uint8_t>::splat(0xdc);
+
+    while (input + simd16<uint16_t>::ELEMENTS * 2 < end) {
+        // 0. Load data: since the validation takes into account only higher
+        //    byte of each word, we compress the two vectors into one which
+        //    consists only the higher bytes.
+        auto in0 = simd16<uint16_t>(input);
+        auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::ELEMENTS);
+
+        if (big_endian) {
+            in0 = in0.swap_bytes();
+            in1 = in1.swap_bytes();
+        }
+
+        const auto t0 = in0.shr<8>();
+        const auto t1 = in1.shr<8>();
+
+        const auto in = simd16<uint16_t>::pack(t0, t1);
+
+        // 1. Check whether we have any 0xD800..DFFF word (0b1101'1xxx'yyyy'yyyy).
+        const auto surrogates_wordmask = (in & v_f8) == v_d8;
+        const uint32_t surrogates_bitmask = surrogates_wordmask.to_bitmask();
+        if (surrogates_bitmask == 0x0) {
+            input += simd16<uint16_t>::ELEMENTS * 2;
+        } else {
+            // 2. We have some surrogates that have to be distinguished:
+            //    - low  surrogates: 0b1101'10xx'yyyy'yyyy (0xD800..0xDBFF)
+            //    - high surrogates: 0b1101'11xx'yyyy'yyyy (0xDC00..0xDFFF)
+            //
+            //    Fact: high surrogate has 11th bit set (3rd bit in the higher word)
+
+            // V - non-surrogate words
+            //     V = not surrogates_wordmask
+            const uint32_t V = ~surrogates_bitmask;
+
+            // H - word-mask for high surrogates: the six highest bits are 0b1101'11
+            const auto    vH = (in & v_fc) == v_dc;
+            const uint32_t H = vH.to_bitmask();
+
+            // L - word mask for low surrogates
+            //     L = not H and surrogates_wordmask
+            const uint32_t L = ~H & surrogates_bitmask;
+
+            const uint32_t a = L & (H >> 1);  // A low surrogate must be followed by high one.
+                                              // (A low surrogate placed in the 7th register's word
+                                              // is an exception we handle.)
+            const uint32_t b = a << 1;        // Just mark that the opposite fact is hold,
+                                              // thanks to that we have only two masks for valid case.
+            const uint32_t c = V | a | b;     // Combine all the masks into the final one.
+
+            if (c == 0xffffffff) {
+                // The whole input register contains valid UTF-16, i.e.,
+                // either single words or proper surrogate pairs.
+                input += simd16<uint16_t>::ELEMENTS * 2;
+            } else if (c == 0x7fffffff) {
+                // The 31 lower words of the input register contains valid UTF-16.
+                // The 31 word may be either a low or high surrogate. It the next
+                // iteration we 1) check if the low surrogate is followed by a high
+                // one, 2) reject sole high surrogate.
+                input += simd16<uint16_t>::ELEMENTS * 2 - 1;
+            } else {
+                return nullptr;
+            }
+        }
+    }
+
+    return input;
+}
+
+
+template <endianness big_endian>
+const result avx2_validate_utf16_with_errors(const char16_t* input, size_t size) {
+    const char16_t* start = input;
+    const char16_t* end = input + size;
+
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+    const auto v_fc = simd8<uint8_t>::splat(0xfc);
+    const auto v_dc = simd8<uint8_t>::splat(0xdc);
+
+    while (input + simd16<uint16_t>::ELEMENTS * 2 < end) {
+        // 0. Load data: since the validation takes into account only higher
+        //    byte of each word, we compress the two vectors into one which
+        //    consists only the higher bytes.
+        auto in0 = simd16<uint16_t>(input);
+        auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::ELEMENTS);
+
+        if (big_endian) {
+            in0 = in0.swap_bytes();
+            in1 = in1.swap_bytes();
+        }
+
+        const auto t0 = in0.shr<8>();
+        const auto t1 = in1.shr<8>();
+
+        const auto in = simd16<uint16_t>::pack(t0, t1);
+
+        // 1. Check whether we have any 0xD800..DFFF word (0b1101'1xxx'yyyy'yyyy).
+        const auto surrogates_wordmask = (in & v_f8) == v_d8;
+        const uint32_t surrogates_bitmask = surrogates_wordmask.to_bitmask();
+        if (surrogates_bitmask == 0x0) {
+            input += simd16<uint16_t>::ELEMENTS * 2;
+        } else {
+            // 2. We have some surrogates that have to be distinguished:
+            //    - low  surrogates: 0b1101'10xx'yyyy'yyyy (0xD800..0xDBFF)
+            //    - high surrogates: 0b1101'11xx'yyyy'yyyy (0xDC00..0xDFFF)
+            //
+            //    Fact: high surrogate has 11th bit set (3rd bit in the higher word)
+
+            // V - non-surrogate words
+            //     V = not surrogates_wordmask
+            const uint32_t V = ~surrogates_bitmask;
+
+            // H - word-mask for high surrogates: the six highest bits are 0b1101'11
+            const auto    vH = (in & v_fc) == v_dc;
+            const uint32_t H = vH.to_bitmask();
+
+            // L - word mask for low surrogates
+            //     L = not H and surrogates_wordmask
+            const uint32_t L = ~H & surrogates_bitmask;
+
+            const uint32_t a = L & (H >> 1);  // A low surrogate must be followed by high one.
+                                              // (A low surrogate placed in the 7th register's word
+                                              // is an exception we handle.)
+            const uint32_t b = a << 1;        // Just mark that the opposite fact is hold,
+                                              // thanks to that we have only two masks for valid case.
+            const uint32_t c = V | a | b;     // Combine all the masks into the final one.
+
+            if (c == 0xffffffff) {
+                // The whole input register contains valid UTF-16, i.e.,
+                // either single words or proper surrogate pairs.
+                input += simd16<uint16_t>::ELEMENTS * 2;
+            } else if (c == 0x7fffffff) {
+                // The 31 lower words of the input register contains valid UTF-16.
+                // The 31 word may be either a low or high surrogate. It the next
+                // iteration we 1) check if the low surrogate is followed by a high
+                // one, 2) reject sole high surrogate.
+                input += simd16<uint16_t>::ELEMENTS * 2 - 1;
+            } else {
+                return result(error_code::SURROGATE, input - start);
+            }
+        }
+    }
+
+    return result(error_code::SUCCESS, input - start);
+}
+/* end file src/haswell/avx2_validate_utf16.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_validate_utf32le.cpp
+/* begin file src/haswell/avx2_validate_utf32le.cpp */
+/* Returns:
+   - pointer to the last unprocessed character (a scalar fallback should check the rest);
+   - nullptr if an error was detected.
+*/
+const char32_t* avx2_validate_utf32le(const char32_t* input, size_t size) {
+    const char32_t* end = input + size;
+
+    const __m256i standardmax = _mm256_set1_epi32(0x10ffff);
+    const __m256i offset = _mm256_set1_epi32(0xffff2000);
+    const __m256i standardoffsetmax = _mm256_set1_epi32(0xfffff7ff);
+    __m256i currentmax = _mm256_setzero_si256();
+    __m256i currentoffsetmax = _mm256_setzero_si256();
+
+    while (input + 8 < end) {
+        const __m256i in = _mm256_loadu_si256((__m256i *)input);
+        currentmax = _mm256_max_epu32(in,currentmax);
+        currentoffsetmax = _mm256_max_epu32(_mm256_add_epi32(in, offset), currentoffsetmax);
+        input += 8;
+    }
+    __m256i is_zero = _mm256_xor_si256(_mm256_max_epu32(currentmax, standardmax), standardmax);
+    if(_mm256_testz_si256(is_zero, is_zero) == 0) {
+        return nullptr;
+    }
+
+    is_zero = _mm256_xor_si256(_mm256_max_epu32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+    if(_mm256_testz_si256(is_zero, is_zero) == 0) {
+        return nullptr;
+    }
+
+    return input;
+}
+
+
+const result avx2_validate_utf32le_with_errors(const char32_t* input, size_t size) {
+    const char32_t* start = input;
+    const char32_t* end = input + size;
+
+    const __m256i standardmax = _mm256_set1_epi32(0x10ffff);
+    const __m256i offset = _mm256_set1_epi32(0xffff2000);
+    const __m256i standardoffsetmax = _mm256_set1_epi32(0xfffff7ff);
+    __m256i currentmax = _mm256_setzero_si256();
+    __m256i currentoffsetmax = _mm256_setzero_si256();
+
+    while (input + 8 < end) {
+        const __m256i in = _mm256_loadu_si256((__m256i *)input);
+        currentmax = _mm256_max_epu32(in,currentmax);
+        currentoffsetmax = _mm256_max_epu32(_mm256_add_epi32(in, offset), currentoffsetmax);
+
+        __m256i is_zero = _mm256_xor_si256(_mm256_max_epu32(currentmax, standardmax), standardmax);
+        if(_mm256_testz_si256(is_zero, is_zero) == 0) {
+            return result(error_code::TOO_LARGE, input - start);
+        }
+
+        is_zero = _mm256_xor_si256(_mm256_max_epu32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+        if(_mm256_testz_si256(is_zero, is_zero) == 0) {
+            return result(error_code::SURROGATE, input - start);
+        }
+        input += 8;
+    }
+
+    return result(error_code::SUCCESS, input - start);
+}
+/* end file src/haswell/avx2_validate_utf32le.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_convert_utf8_to_utf16.cpp
+/* begin file src/haswell/avx2_convert_utf8_to_utf16.cpp */
+// depends on "tables/utf8_to_utf16_tables.h"
+
+
+// Convert up to 12 bytes from utf8 to utf16 using a mask indicating the
+// end of the code points. Only the least significant 12 bits of the mask
+// are accessed.
+// It returns how many bytes were consumed (up to 12).
+template <endianness big_endian>
+size_t convert_masked_utf8_to_utf16(const char *input,
+                           uint64_t utf8_end_of_code_point_mask,
+                           char16_t *&utf16_output) {
+  // we use an approach where we try to process up to 12 input bytes.
+  // Why 12 input bytes and not 16? Because we are concerned with the size of
+  // the lookup tables. Also 12 is nicely divisible by two and three.
+  //
+  //
+  // Optimization note: our main path below is load-latency dependent. Thus it is maybe
+  // beneficial to have fast paths that depend on branch prediction but have less latency.
+  // This results in more instructions but, potentially, also higher speeds.
+  //
+  // We first try a few fast paths.
+  const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+  const __m128i in = _mm_loadu_si128((__m128i *)input);
+  const uint16_t input_utf8_end_of_code_point_mask =
+      utf8_end_of_code_point_mask & 0xfff;
+  if(((utf8_end_of_code_point_mask & 0xffff) == 0xffff)) {
+    // We process the data in chunks of 16 bytes.
+    __m256i ascii = _mm256_cvtepu8_epi16(in);
+    if (big_endian) {
+      const __m256i swap256 = _mm256_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14,
+                                  17, 16, 19, 18, 21, 20, 23, 22, 25, 24, 27, 26, 29, 28, 31, 30);
+      ascii = _mm256_shuffle_epi8(ascii, swap256);
+    }
+    _mm256_storeu_si256(reinterpret_cast<__m256i *>(utf16_output), ascii);
+    utf16_output += 16; // We wrote 16 16-bit characters.
+    return 16; // We consumed 16 bytes.
+  }
+  if(((utf8_end_of_code_point_mask & 0xffff) == 0xaaaa)) {
+    // We want to take 8 2-byte UTF-8 words and turn them into 8 2-byte UTF-16 words.
+    // There is probably a more efficient sequence, but the following might do.
+    const __m128i sh = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi16(0x7f));
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi16(0x1f00));
+    __m128i composed = _mm_or_si128(ascii, _mm_srli_epi16(highbyte, 2));
+    if (big_endian) composed = _mm_shuffle_epi8(composed, swap);
+    _mm_storeu_si128((__m128i *)utf16_output, composed);
+    utf16_output += 8; // We wrote 16 bytes, 8 code points.
+    return 16;
+  }
+  if(input_utf8_end_of_code_point_mask == 0x924) {
+    // We want to take 4 3-byte UTF-8 words and turn them into 4 2-byte UTF-16 words.
+    // There is probably a more efficient sequence, but the following might do.
+    const __m128i sh = _mm_setr_epi8(2, 1, 0, -1, 5, 4, 3, -1, 8, 7, 6, -1, 11, 10, 9, -1);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii =
+        _mm_and_si128(perm, _mm_set1_epi32(0x7f)); // 7 or 6 bits
+    const __m128i middlebyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x3f00)); // 5 or 6 bits
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    const __m128i highbyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x0f0000)); // 4 bits
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 4);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted), highbyte_shifted);
+    __m128i composed_repacked = _mm_packus_epi32(composed, composed);
+    if (big_endian) composed_repacked = _mm_shuffle_epi8(composed_repacked, swap);
+    _mm_storeu_si128((__m128i *)utf16_output, composed_repacked);
+    utf16_output += 4;
+    return 12;
+  }
+
+  const uint8_t idx =
+      simdutf::tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][0];
+  const uint8_t consumed =
+      simdutf::tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][1];
+  if (idx < 64) {
+    // SIX (6) input code-words
+    // this is a relatively easy scenario
+    // we process SIX (6) input code-words. The max length in bytes of six code
+    // words spanning between 1 and 2 bytes each is 12 bytes. On processors
+    // where pdep/pext is fast, we might be able to use a small lookup table.
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)simdutf::tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi16(0x7f));
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi16(0x1f00));
+    __m128i composed = _mm_or_si128(ascii, _mm_srli_epi16(highbyte, 2));
+    if (big_endian) composed = _mm_shuffle_epi8(composed, swap);
+    _mm_storeu_si128((__m128i *)utf16_output, composed);
+    utf16_output += 6; // We wrote 12 bytes, 6 code points.
+  } else if (idx < 145) {
+    // FOUR (4) input code-words
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)simdutf::tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii =
+        _mm_and_si128(perm, _mm_set1_epi32(0x7f)); // 7 or 6 bits
+    const __m128i middlebyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x3f00)); // 5 or 6 bits
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    const __m128i highbyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x0f0000)); // 4 bits
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 4);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted), highbyte_shifted);
+    __m128i composed_repacked = _mm_packus_epi32(composed, composed);
+    if (big_endian) composed_repacked = _mm_shuffle_epi8(composed_repacked, swap);
+    _mm_storeu_si128((__m128i *)utf16_output, composed_repacked);
+    utf16_output += 4;
+  } else if (idx < 209) {
+    // TWO (2) input code-words
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)simdutf::tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi32(0x7f));
+    const __m128i middlebyte = _mm_and_si128(perm, _mm_set1_epi32(0x3f00));
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    __m128i middlehighbyte = _mm_and_si128(perm, _mm_set1_epi32(0x3f0000));
+    // correct for spurious high bit
+    const __m128i correct =
+        _mm_srli_epi32(_mm_and_si128(perm, _mm_set1_epi32(0x400000)), 1);
+    middlehighbyte = _mm_xor_si128(correct, middlehighbyte);
+    const __m128i middlehighbyte_shifted = _mm_srli_epi32(middlehighbyte, 4);
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi32(0x07000000));
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 6);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted),
+                     _mm_or_si128(highbyte_shifted, middlehighbyte_shifted));
+    const __m128i composedminus =
+        _mm_sub_epi32(composed, _mm_set1_epi32(0x10000));
+    const __m128i lowtenbits =
+        _mm_and_si128(composedminus, _mm_set1_epi32(0x3ff));
+    const __m128i hightenbits = _mm_srli_epi32(composedminus, 10);
+    const __m128i lowtenbitsadd =
+        _mm_add_epi32(lowtenbits, _mm_set1_epi32(0xDC00));
+    const __m128i hightenbitsadd =
+        _mm_add_epi32(hightenbits, _mm_set1_epi32(0xD800));
+    const __m128i lowtenbitsaddshifted = _mm_slli_epi32(lowtenbitsadd, 16);
+    __m128i surrogates =
+        _mm_or_si128(hightenbitsadd, lowtenbitsaddshifted);
+    uint32_t basic_buffer[4];
+    uint32_t basic_buffer_swap[4];
+    if (big_endian) {
+      _mm_storeu_si128((__m128i *)basic_buffer_swap, _mm_shuffle_epi8(composed, swap));
+      surrogates = _mm_shuffle_epi8(surrogates, swap);
+    }
+    _mm_storeu_si128((__m128i *)basic_buffer, composed);
+    uint32_t surrogate_buffer[4];
+    _mm_storeu_si128((__m128i *)surrogate_buffer, surrogates);
+    for (size_t i = 0; i < 3; i++) {
+      if (basic_buffer[i] < 65536) {
+        utf16_output[0] = big_endian ? uint16_t(basic_buffer_swap[i]) : uint16_t(basic_buffer[i]);
+        utf16_output++;
+      } else {
+        utf16_output[0] = uint16_t(surrogate_buffer[i] & 0xffff);
+        utf16_output[1] = uint16_t(surrogate_buffer[i] >> 16);
+        utf16_output += 2;
+      }
+    }
+  } else {
+    // here we know that there is an error but we do not handle errors
+  }
+  return consumed;
+}
+/* end file src/haswell/avx2_convert_utf8_to_utf16.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_convert_utf8_to_utf32.cpp
+/* begin file src/haswell/avx2_convert_utf8_to_utf32.cpp */
+// depends on "tables/utf8_to_utf16_tables.h"
+
+
+// Convert up to 12 bytes from utf8 to utf32 using a mask indicating the
+// end of the code points. Only the least significant 12 bits of the mask
+// are accessed.
+// It returns how many bytes were consumed (up to 12).
+size_t convert_masked_utf8_to_utf32(const char *input,
+                           uint64_t utf8_end_of_code_point_mask,
+                           char32_t *&utf32_output) {
+  // we use an approach where we try to process up to 12 input bytes.
+  // Why 12 input bytes and not 16? Because we are concerned with the size of
+  // the lookup tables. Also 12 is nicely divisible by two and three.
+  //
+  //
+  // Optimization note: our main path below is load-latency dependent. Thus it is maybe
+  // beneficial to have fast paths that depend on branch prediction but have less latency.
+  // This results in more instructions but, potentially, also higher speeds.
+  //
+  // We first try a few fast paths.
+  const __m128i in = _mm_loadu_si128((__m128i *)input);
+  const uint16_t input_utf8_end_of_code_point_mask =
+      utf8_end_of_code_point_mask & 0xfff;
+  if(((utf8_end_of_code_point_mask & 0xffff) == 0xffff)) {
+    // We process the data in chunks of 16 bytes.
+    _mm256_storeu_si256(reinterpret_cast<__m256i *>(utf32_output), _mm256_cvtepu8_epi32(in));
+    _mm256_storeu_si256(reinterpret_cast<__m256i *>(utf32_output+8), _mm256_cvtepu8_epi32(_mm_srli_si128(in,8)));
+    utf32_output += 16; // We wrote 16 32-bit characters.
+    return 16; // We consumed 16 bytes.
+  }
+  if(((utf8_end_of_code_point_mask & 0xffff) == 0xaaaa)) {
+    // We want to take 8 2-byte UTF-8 words and turn them into 8 4-byte UTF-32 words.
+    // There is probably a more efficient sequence, but the following might do.
+    const __m128i sh = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi16(0x7f));
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi16(0x1f00));
+    const __m128i composed = _mm_or_si128(ascii, _mm_srli_epi16(highbyte, 2));
+    _mm256_storeu_si256((__m256i *)utf32_output, _mm256_cvtepu16_epi32(composed));
+    utf32_output += 8; // We wrote 16 bytes, 8 code points.
+    return 16;
+  }
+  if(input_utf8_end_of_code_point_mask == 0x924) {
+    // We want to take 4 3-byte UTF-8 words and turn them into 4 4-byte UTF-32 words.
+    // There is probably a more efficient sequence, but the following might do.
+    const __m128i sh = _mm_setr_epi8(2, 1, 0, -1, 5, 4, 3, -1, 8, 7, 6, -1, 11, 10, 9, -1);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii =
+        _mm_and_si128(perm, _mm_set1_epi32(0x7f)); // 7 or 6 bits
+    const __m128i middlebyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x3f00)); // 5 or 6 bits
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    const __m128i highbyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x0f0000)); // 4 bits
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 4);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted), highbyte_shifted);
+    _mm_storeu_si128((__m128i *)utf32_output, composed);
+    utf32_output += 4;
+    return 12;
+  }
+  /// We do not have a fast path available, so we fallback.
+
+  const uint8_t idx =
+      tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][0];
+  const uint8_t consumed =
+      tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][1];
+  if (idx < 64) {
+    // SIX (6) input code-words
+    // this is a relatively easy scenario
+    // we process SIX (6) input code-words. The max length in bytes of six code
+    // words spanning between 1 and 2 bytes each is 12 bytes. On processors
+    // where pdep/pext is fast, we might be able to use a small lookup table.
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi16(0x7f));
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi16(0x1f00));
+    const __m128i composed = _mm_or_si128(ascii, _mm_srli_epi16(highbyte, 2));
+    _mm256_storeu_si256((__m256i *)utf32_output, _mm256_cvtepu16_epi32(composed));
+    utf32_output += 6; // We wrote 12 bytes, 6 code points.
+  } else if (idx < 145) {
+    // FOUR (4) input code-words
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii =
+        _mm_and_si128(perm, _mm_set1_epi32(0x7f)); // 7 or 6 bits
+    const __m128i middlebyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x3f00)); // 5 or 6 bits
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    const __m128i highbyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x0f0000)); // 4 bits
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 4);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted), highbyte_shifted);
+    _mm_storeu_si128((__m128i *)utf32_output, composed);
+    utf32_output += 4;
+  } else if (idx < 209) {
+    // TWO (2) input code-words
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi32(0x7f));
+    const __m128i middlebyte = _mm_and_si128(perm, _mm_set1_epi32(0x3f00));
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    __m128i middlehighbyte = _mm_and_si128(perm, _mm_set1_epi32(0x3f0000));
+    // correct for spurious high bit
+    const __m128i correct =
+        _mm_srli_epi32(_mm_and_si128(perm, _mm_set1_epi32(0x400000)), 1);
+    middlehighbyte = _mm_xor_si128(correct, middlehighbyte);
+    const __m128i middlehighbyte_shifted = _mm_srli_epi32(middlehighbyte, 4);
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi32(0x07000000));
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 6);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted),
+                     _mm_or_si128(highbyte_shifted, middlehighbyte_shifted));
+    _mm_storeu_si128((__m128i *)utf32_output, composed);
+    utf32_output += 3;
+  } else {
+    // here we know that there is an error but we do not handle errors
+  }
+  return consumed;
+}
+/* end file src/haswell/avx2_convert_utf8_to_utf32.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_convert_utf16_to_utf8.cpp
+/* begin file src/haswell/avx2_convert_utf16_to_utf8.cpp */
+/*
+    The vectorized algorithm works on single SSE register i.e., it
+    loads eight 16-bit words.
+
+    We consider three cases:
+    1. an input register contains no surrogates and each value
+       is in range 0x0000 .. 0x07ff.
+    2. an input register contains no surrogates and values are
+       is in range 0x0000 .. 0xffff.
+    3. an input register contains surrogates --- i.e. codepoints
+       can have 16 or 32 bits.
+
+    Ad 1.
+
+    When values are less than 0x0800, it means that a 16-bit words
+    can be converted into: 1) single UTF8 byte (when it's an ASCII
+    char) or 2) two UTF8 bytes.
+
+    For this case we do only some shuffle to obtain these 2-byte
+    codes and finally compress the whole SSE register with a single
+    shuffle.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+    Ad 2.
+
+    When values fit in 16-bit words, but are above 0x07ff, then
+    a single word may produce one, two or three UTF8 bytes.
+
+    We prepare data for all these three cases in two registers.
+    The first register contains lower two UTF8 bytes (used in all
+    cases), while the second one contains just the third byte for
+    the three-UTF8-bytes case.
+
+    Finally these two registers are interleaved forming eight-element
+    array of 32-bit values. The array spans two SSE registers.
+    The bytes from the registers are compressed using two shuffles.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+
+    To summarize:
+    - We need two 256-entry tables that have 8704 bytes in total.
+*/
+
+
+/*
+  Returns a pair: the first unprocessed byte from buf and utf8_output
+  A scalar routing should carry on the conversion of the tail.
+*/
+template <endianness big_endian>
+std::pair<const char16_t*, char*> avx2_convert_utf16_to_utf8(const char16_t* buf, size_t len, char* utf8_output) {
+  const char16_t* end = buf + len;
+  const __m256i v_0000 = _mm256_setzero_si256();
+  const __m256i v_f800 = _mm256_set1_epi16((int16_t)0xf800);
+  const __m256i v_d800 = _mm256_set1_epi16((int16_t)0xd800);
+  const __m256i v_c080 = _mm256_set1_epi16((int16_t)0xc080);
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+    if (big_endian) {
+      const __m256i swap = _mm256_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14,
+                                  17, 16, 19, 18, 21, 20, 23, 22, 25, 24, 27, 26, 29, 28, 31, 30);
+      in = _mm256_shuffle_epi8(in, swap);
+    }
+    // a single 16-bit UTF-16 word can yield 1, 2 or 3 UTF-8 bytes
+    const __m256i v_ff80 = _mm256_set1_epi16((int16_t)0xff80);
+    if(_mm256_testz_si256(in, v_ff80)) { // ASCII fast path!!!!
+        // 1. pack the bytes
+        const __m128i utf8_packed = _mm_packus_epi16(_mm256_castsi256_si128(in),_mm256_extractf128_si256(in,1));
+        // 2. store (16 bytes)
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+        // 3. adjust pointers
+        buf += 16;
+        utf8_output += 16;
+        continue; // we are done for this round!
+    }
+    // no bits set above 7th bit
+    const __m256i one_byte_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in, v_ff80), v_0000);
+    const uint32_t one_byte_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m256i one_or_two_bytes_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in, v_f800), v_0000);
+    const uint32_t one_or_two_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_or_two_bytes_bytemask));
+    if (one_or_two_bytes_bitmask == 0xffffffff) {
+
+          // 1. prepare 2-byte values
+          // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+          // expected output   : [110a|aaaa|10bb|bbbb] x 8
+          const __m256i v_1f00 = _mm256_set1_epi16((int16_t)0x1f00);
+          const __m256i v_003f = _mm256_set1_epi16((int16_t)0x003f);
+
+          // t0 = [000a|aaaa|bbbb|bb00]
+          const __m256i t0 = _mm256_slli_epi16(in, 2);
+          // t1 = [000a|aaaa|0000|0000]
+          const __m256i t1 = _mm256_and_si256(t0, v_1f00);
+          // t2 = [0000|0000|00bb|bbbb]
+          const __m256i t2 = _mm256_and_si256(in, v_003f);
+          // t3 = [000a|aaaa|00bb|bbbb]
+          const __m256i t3 = _mm256_or_si256(t1, t2);
+          // t4 = [110a|aaaa|10bb|bbbb]
+          const __m256i t4 = _mm256_or_si256(t3, v_c080);
+
+          // 2. merge ASCII and 2-byte codewords
+          const __m256i utf8_unpacked = _mm256_blendv_epi8(t4, in, one_byte_bytemask);
+
+          // 3. prepare bitmask for 8-bit lookup
+          const uint32_t M0 = one_byte_bitmask & 0x55555555;
+          const uint32_t M1 = M0 >> 7;
+          const uint32_t M2 = (M1 | M0)  & 0x00ff00ff;
+          // 4. pack the bytes
+
+          const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2)][0];
+          const uint8_t* row_2 = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2>>16)][0];
+
+          const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+          const __m128i shuffle_2 = _mm_loadu_si128((__m128i*)(row_2 + 1));
+
+          const __m256i utf8_packed = _mm256_shuffle_epi8(utf8_unpacked, _mm256_setr_m128i(shuffle,shuffle_2));
+          // 5. store bytes
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_packed));
+          utf8_output += row[0];
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_packed,1));
+          utf8_output += row_2[0];
+
+          // 6. adjust pointers
+          buf += 16;
+          continue;
+    }
+    // 1. Check if there are any surrogate word in the input chunk.
+    //    We have also deal with situation when there is a surrogate word
+    //    at the end of a chunk.
+    const __m256i surrogates_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in, v_f800), v_d800);
+
+    // bitmask = 0x0000 if there are no surrogates
+    //         = 0xc000 if the last word is a surrogate
+    const uint32_t surrogates_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(surrogates_bytemask));
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+    if (surrogates_bitmask == 0x00000000) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+        const __m256i dup_even = _mm256_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                                0x0808, 0x0a0a, 0x0c0c, 0x0e0e,
+                                                0x0000, 0x0202, 0x0404, 0x0606,
+                                                0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+        /* In this branch we handle three cases:
+           1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+           2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+           3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+          We expand the input word (16-bit) into two words (32-bit), thus
+          we have room for four bytes. However, we need five distinct bit
+          layouts. Note that the last byte in cases #2 and #3 is the same.
+
+          We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+          in register t2.
+
+          We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+          either byte 1 for case #2 or byte 2 for case #3. Note that they
+          differ by exactly one bit.
+
+          Finally from these two words we build proper UTF-8 sequence, taking
+          into account the case (i.e, the number of bytes to write).
+        */
+        /**
+         * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+         * t2 => [0ccc|cccc] [10cc|cccc]
+         * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+         */
+#define vec(x) _mm256_set1_epi16(static_cast<uint16_t>(x))
+        // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+        const __m256i t0 = _mm256_shuffle_epi8(in, dup_even);
+        // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+        const __m256i t1 = _mm256_and_si256(t0, vec(0b0011111101111111));
+        // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+        const __m256i t2 = _mm256_or_si256 (t1, vec(0b1000000000000000));
+
+        // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+        const __m256i s0 = _mm256_srli_epi16(in, 4);
+        // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+        const __m256i s1 = _mm256_and_si256(s0, vec(0b0000111111111100));
+        // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+        const __m256i s2 = _mm256_maddubs_epi16(s1, vec(0x0140));
+        // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+        const __m256i s3 = _mm256_or_si256(s2, vec(0b1100000011100000));
+        const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+        const __m256i s4 = _mm256_xor_si256(s3, m0);
+#undef vec
+
+        // 4. expand words 16-bit => 32-bit
+        const __m256i out0 = _mm256_unpacklo_epi16(t2, s4);
+        const __m256i out1 = _mm256_unpackhi_epi16(t2, s4);
+
+        // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+        const uint32_t mask = (one_byte_bitmask & 0x55555555) |
+                              (one_or_two_bytes_bitmask & 0xaaaaaaaa);
+        // Due to the wider registers, the following path is less likely to be useful.
+        /*if(mask == 0) {
+          // We only have three-byte words. Use fast path.
+          const __m256i shuffle = _mm256_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1, 2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+          const __m256i utf8_0 = _mm256_shuffle_epi8(out0, shuffle);
+          const __m256i utf8_1 = _mm256_shuffle_epi8(out1, shuffle);
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_0));
+          utf8_output += 12;
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_1));
+          utf8_output += 12;
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_0,1));
+          utf8_output += 12;
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_1,1));
+          utf8_output += 12;
+          buf += 16;
+          continue;
+        }*/
+        const uint8_t mask0 = uint8_t(mask);
+        const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+        const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+        const __m128i utf8_0 = _mm_shuffle_epi8(_mm256_castsi256_si128(out0), shuffle0);
+
+        const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+        const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+        const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+        const __m128i utf8_1 = _mm_shuffle_epi8(_mm256_castsi256_si128(out1), shuffle1);
+
+        const uint8_t mask2 = static_cast<uint8_t>(mask >> 16);
+        const uint8_t* row2 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask2][0];
+        const __m128i shuffle2 = _mm_loadu_si128((__m128i*)(row2 + 1));
+        const __m128i utf8_2 = _mm_shuffle_epi8(_mm256_extractf128_si256(out0,1), shuffle2);
+
+
+        const uint8_t mask3 = static_cast<uint8_t>(mask >> 24);
+        const uint8_t* row3 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask3][0];
+        const __m128i shuffle3 = _mm_loadu_si128((__m128i*)(row3 + 1));
+        const __m128i utf8_3 = _mm_shuffle_epi8(_mm256_extractf128_si256(out1,1), shuffle3);
+
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+        utf8_output += row0[0];
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+        utf8_output += row1[0];
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_2);
+        utf8_output += row2[0];
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_3);
+        utf8_output += row3[0];
+        buf += 16;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word & 0xFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word &0xF800 ) != 0xD800) {
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k+1]) : buf[k+1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(nullptr, utf8_output); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf8_output++ = char((value>>18) | 0b11110000);
+          *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((value & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+  return std::make_pair(buf, utf8_output);
+}
+
+
+/*
+  Returns a pair: a result struct and utf8_output.
+  If there is an error, the count field of the result is the position of the error.
+  Otherwise, it is the position of the first unprocessed byte in buf (even if finished).
+  A scalar routing should carry on the conversion of the tail if needed.
+*/
+template <endianness big_endian>
+std::pair<result, char*> avx2_convert_utf16_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) {
+  const char16_t* start = buf;
+  const char16_t* end = buf + len;
+
+  const __m256i v_0000 = _mm256_setzero_si256();
+  const __m256i v_f800 = _mm256_set1_epi16((int16_t)0xf800);
+  const __m256i v_d800 = _mm256_set1_epi16((int16_t)0xd800);
+  const __m256i v_c080 = _mm256_set1_epi16((int16_t)0xc080);
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+    if (big_endian) {
+      const __m256i swap = _mm256_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14,
+                                  17, 16, 19, 18, 21, 20, 23, 22, 25, 24, 27, 26, 29, 28, 31, 30);
+      in = _mm256_shuffle_epi8(in, swap);
+    }
+    // a single 16-bit UTF-16 word can yield 1, 2 or 3 UTF-8 bytes
+    const __m256i v_ff80 = _mm256_set1_epi16((int16_t)0xff80);
+    if(_mm256_testz_si256(in, v_ff80)) { // ASCII fast path!!!!
+        // 1. pack the bytes
+        const __m128i utf8_packed = _mm_packus_epi16(_mm256_castsi256_si128(in),_mm256_extractf128_si256(in,1));
+        // 2. store (16 bytes)
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+        // 3. adjust pointers
+        buf += 16;
+        utf8_output += 16;
+        continue; // we are done for this round!
+    }
+    // no bits set above 7th bit
+    const __m256i one_byte_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in, v_ff80), v_0000);
+    const uint32_t one_byte_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m256i one_or_two_bytes_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in, v_f800), v_0000);
+    const uint32_t one_or_two_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_or_two_bytes_bytemask));
+    if (one_or_two_bytes_bitmask == 0xffffffff) {
+
+          // 1. prepare 2-byte values
+          // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+          // expected output   : [110a|aaaa|10bb|bbbb] x 8
+          const __m256i v_1f00 = _mm256_set1_epi16((int16_t)0x1f00);
+          const __m256i v_003f = _mm256_set1_epi16((int16_t)0x003f);
+
+          // t0 = [000a|aaaa|bbbb|bb00]
+          const __m256i t0 = _mm256_slli_epi16(in, 2);
+          // t1 = [000a|aaaa|0000|0000]
+          const __m256i t1 = _mm256_and_si256(t0, v_1f00);
+          // t2 = [0000|0000|00bb|bbbb]
+          const __m256i t2 = _mm256_and_si256(in, v_003f);
+          // t3 = [000a|aaaa|00bb|bbbb]
+          const __m256i t3 = _mm256_or_si256(t1, t2);
+          // t4 = [110a|aaaa|10bb|bbbb]
+          const __m256i t4 = _mm256_or_si256(t3, v_c080);
+
+          // 2. merge ASCII and 2-byte codewords
+          const __m256i utf8_unpacked = _mm256_blendv_epi8(t4, in, one_byte_bytemask);
+
+          // 3. prepare bitmask for 8-bit lookup
+          const uint32_t M0 = one_byte_bitmask & 0x55555555;
+          const uint32_t M1 = M0 >> 7;
+          const uint32_t M2 = (M1 | M0)  & 0x00ff00ff;
+          // 4. pack the bytes
+
+          const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2)][0];
+          const uint8_t* row_2 = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2>>16)][0];
+
+          const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+          const __m128i shuffle_2 = _mm_loadu_si128((__m128i*)(row_2 + 1));
+
+          const __m256i utf8_packed = _mm256_shuffle_epi8(utf8_unpacked, _mm256_setr_m128i(shuffle,shuffle_2));
+          // 5. store bytes
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_packed));
+          utf8_output += row[0];
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_packed,1));
+          utf8_output += row_2[0];
+
+          // 6. adjust pointers
+          buf += 16;
+          continue;
+    }
+    // 1. Check if there are any surrogate word in the input chunk.
+    //    We have also deal with situation when there is a surrogate word
+    //    at the end of a chunk.
+    const __m256i surrogates_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in, v_f800), v_d800);
+
+    // bitmask = 0x0000 if there are no surrogates
+    //         = 0xc000 if the last word is a surrogate
+    const uint32_t surrogates_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(surrogates_bytemask));
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+    if (surrogates_bitmask == 0x00000000) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+        const __m256i dup_even = _mm256_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                                0x0808, 0x0a0a, 0x0c0c, 0x0e0e,
+                                                0x0000, 0x0202, 0x0404, 0x0606,
+                                                0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+        /* In this branch we handle three cases:
+           1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+           2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+           3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+          We expand the input word (16-bit) into two words (32-bit), thus
+          we have room for four bytes. However, we need five distinct bit
+          layouts. Note that the last byte in cases #2 and #3 is the same.
+
+          We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+          in register t2.
+
+          We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+          either byte 1 for case #2 or byte 2 for case #3. Note that they
+          differ by exactly one bit.
+
+          Finally from these two words we build proper UTF-8 sequence, taking
+          into account the case (i.e, the number of bytes to write).
+        */
+        /**
+         * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+         * t2 => [0ccc|cccc] [10cc|cccc]
+         * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+         */
+#define vec(x) _mm256_set1_epi16(static_cast<uint16_t>(x))
+        // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+        const __m256i t0 = _mm256_shuffle_epi8(in, dup_even);
+        // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+        const __m256i t1 = _mm256_and_si256(t0, vec(0b0011111101111111));
+        // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+        const __m256i t2 = _mm256_or_si256 (t1, vec(0b1000000000000000));
+
+        // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+        const __m256i s0 = _mm256_srli_epi16(in, 4);
+        // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+        const __m256i s1 = _mm256_and_si256(s0, vec(0b0000111111111100));
+        // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+        const __m256i s2 = _mm256_maddubs_epi16(s1, vec(0x0140));
+        // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+        const __m256i s3 = _mm256_or_si256(s2, vec(0b1100000011100000));
+        const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+        const __m256i s4 = _mm256_xor_si256(s3, m0);
+#undef vec
+
+        // 4. expand words 16-bit => 32-bit
+        const __m256i out0 = _mm256_unpacklo_epi16(t2, s4);
+        const __m256i out1 = _mm256_unpackhi_epi16(t2, s4);
+
+        // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+        const uint32_t mask = (one_byte_bitmask & 0x55555555) |
+                              (one_or_two_bytes_bitmask & 0xaaaaaaaa);
+        // Due to the wider registers, the following path is less likely to be useful.
+        /*if(mask == 0) {
+          // We only have three-byte words. Use fast path.
+          const __m256i shuffle = _mm256_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1, 2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+          const __m256i utf8_0 = _mm256_shuffle_epi8(out0, shuffle);
+          const __m256i utf8_1 = _mm256_shuffle_epi8(out1, shuffle);
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_0));
+          utf8_output += 12;
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_1));
+          utf8_output += 12;
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_0,1));
+          utf8_output += 12;
+          _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_1,1));
+          utf8_output += 12;
+          buf += 16;
+          continue;
+        }*/
+        const uint8_t mask0 = uint8_t(mask);
+        const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+        const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+        const __m128i utf8_0 = _mm_shuffle_epi8(_mm256_castsi256_si128(out0), shuffle0);
+
+        const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+        const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+        const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+        const __m128i utf8_1 = _mm_shuffle_epi8(_mm256_castsi256_si128(out1), shuffle1);
+
+        const uint8_t mask2 = static_cast<uint8_t>(mask >> 16);
+        const uint8_t* row2 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask2][0];
+        const __m128i shuffle2 = _mm_loadu_si128((__m128i*)(row2 + 1));
+        const __m128i utf8_2 = _mm_shuffle_epi8(_mm256_extractf128_si256(out0,1), shuffle2);
+
+
+        const uint8_t mask3 = static_cast<uint8_t>(mask >> 24);
+        const uint8_t* row3 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask3][0];
+        const __m128i shuffle3 = _mm_loadu_si128((__m128i*)(row3 + 1));
+        const __m128i utf8_3 = _mm_shuffle_epi8(_mm256_extractf128_si256(out1,1), shuffle3);
+
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+        utf8_output += row0[0];
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+        utf8_output += row1[0];
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_2);
+        utf8_output += row2[0];
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_3);
+        utf8_output += row3[0];
+        buf += 16;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word & 0xFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word &0xF800 ) != 0xD800) {
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k+1]) : buf[k+1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(result(error_code::SURROGATE, buf - start + k - 1), utf8_output); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf8_output++ = char((value>>18) | 0b11110000);
+          *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((value & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf8_output);
+}
+/* end file src/haswell/avx2_convert_utf16_to_utf8.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_convert_utf16_to_utf32.cpp
+/* begin file src/haswell/avx2_convert_utf16_to_utf32.cpp */
+/*
+    The vectorized algorithm works on single SSE register i.e., it
+    loads eight 16-bit words.
+
+    We consider three cases:
+    1. an input register contains no surrogates and each value
+       is in range 0x0000 .. 0x07ff.
+    2. an input register contains no surrogates and values are
+       is in range 0x0000 .. 0xffff.
+    3. an input register contains surrogates --- i.e. codepoints
+       can have 16 or 32 bits.
+
+    Ad 1.
+
+    When values are less than 0x0800, it means that a 16-bit words
+    can be converted into: 1) single UTF8 byte (when it's an ASCII
+    char) or 2) two UTF8 bytes.
+
+    For this case we do only some shuffle to obtain these 2-byte
+    codes and finally compress the whole SSE register with a single
+    shuffle.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+    Ad 2.
+
+    When values fit in 16-bit words, but are above 0x07ff, then
+    a single word may produce one, two or three UTF8 bytes.
+
+    We prepare data for all these three cases in two registers.
+    The first register contains lower two UTF8 bytes (used in all
+    cases), while the second one contains just the third byte for
+    the three-UTF8-bytes case.
+
+    Finally these two registers are interleaved forming eight-element
+    array of 32-bit values. The array spans two SSE registers.
+    The bytes from the registers are compressed using two shuffles.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+
+    To summarize:
+    - We need two 256-entry tables that have 8704 bytes in total.
+*/
+
+
+/*
+  Returns a pair: the first unprocessed byte from buf and utf32_output
+  A scalar routing should carry on the conversion of the tail.
+*/
+template <endianness big_endian>
+std::pair<const char16_t*, char32_t*> avx2_convert_utf16_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) {
+  const char16_t* end = buf + len;
+  const __m256i v_f800 = _mm256_set1_epi16((int16_t)0xf800);
+  const __m256i v_d800 = _mm256_set1_epi16((int16_t)0xd800);
+
+  while (buf + 16 <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+    if (big_endian) {
+      const __m256i swap = _mm256_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14,
+                                  17, 16, 19, 18, 21, 20, 23, 22, 25, 24, 27, 26, 29, 28, 31, 30);
+      in = _mm256_shuffle_epi8(in, swap);
+    }
+
+    // 1. Check if there are any surrogate word in the input chunk.
+    //    We have also deal with situation when there is a surrogate word
+    //    at the end of a chunk.
+    const __m256i surrogates_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in, v_f800), v_d800);
+
+    // bitmask = 0x0000 if there are no surrogates
+    //         = 0xc000 if the last word is a surrogate
+    const uint32_t surrogates_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(surrogates_bytemask));
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+    if (surrogates_bitmask == 0x00000000) {
+      // case: we extend all sixteen 16-bit words to sixteen 32-bit words
+        _mm256_storeu_si256(reinterpret_cast<__m256i *>(utf32_output), _mm256_cvtepu16_epi32(_mm256_castsi256_si128(in)));
+        _mm256_storeu_si256(reinterpret_cast<__m256i *>(utf32_output + 8), _mm256_cvtepu16_epi32(_mm256_extractf128_si256(in,1)));
+        utf32_output += 16;
+        buf += 16;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word &0xF800 ) != 0xD800) {
+          // No surrogate pair
+          *utf32_output++ = char32_t(word);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k+1]) : buf[k+1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(nullptr, utf32_output); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf32_output++ = char32_t(value);
+        }
+      }
+      buf += k;
+    }
+  } // while
+  return std::make_pair(buf, utf32_output);
+}
+
+
+/*
+  Returns a pair: a result struct and utf8_output.
+  If there is an error, the count field of the result is the position of the error.
+  Otherwise, it is the position of the first unprocessed byte in buf (even if finished).
+  A scalar routing should carry on the conversion of the tail if needed.
+*/
+template <endianness big_endian>
+std::pair<result, char32_t*> avx2_convert_utf16_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) {
+  const char16_t* start = buf;
+  const char16_t* end = buf + len;
+  const __m256i v_f800 = _mm256_set1_epi16((int16_t)0xf800);
+  const __m256i v_d800 = _mm256_set1_epi16((int16_t)0xd800);
+
+  while (buf + 16 <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+    if (big_endian) {
+      const __m256i swap = _mm256_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14,
+                                  17, 16, 19, 18, 21, 20, 23, 22, 25, 24, 27, 26, 29, 28, 31, 30);
+      in = _mm256_shuffle_epi8(in, swap);
+    }
+
+    // 1. Check if there are any surrogate word in the input chunk.
+    //    We have also deal with situation when there is a surrogate word
+    //    at the end of a chunk.
+    const __m256i surrogates_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in, v_f800), v_d800);
+
+    // bitmask = 0x0000 if there are no surrogates
+    //         = 0xc000 if the last word is a surrogate
+    const uint32_t surrogates_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(surrogates_bytemask));
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+    if (surrogates_bitmask == 0x00000000) {
+      // case: we extend all sixteen 16-bit words to sixteen 32-bit words
+        _mm256_storeu_si256(reinterpret_cast<__m256i *>(utf32_output), _mm256_cvtepu16_epi32(_mm256_castsi256_si128(in)));
+        _mm256_storeu_si256(reinterpret_cast<__m256i *>(utf32_output + 8), _mm256_cvtepu16_epi32(_mm256_extractf128_si256(in,1)));
+        utf32_output += 16;
+        buf += 16;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word &0xF800 ) != 0xD800) {
+          // No surrogate pair
+          *utf32_output++ = char32_t(word);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k+1]) : buf[k+1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(result(error_code::SURROGATE, buf - start + k - 1), utf32_output); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf32_output++ = char32_t(value);
+        }
+      }
+      buf += k;
+    }
+  } // while
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf32_output);
+}
+/* end file src/haswell/avx2_convert_utf16_to_utf32.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_convert_utf32_to_utf8.cpp
+/* begin file src/haswell/avx2_convert_utf32_to_utf8.cpp */
+std::pair<const char32_t*, char*> avx2_convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) {
+  const char32_t* end = buf + len;
+  const __m256i v_0000 = _mm256_setzero_si256();
+  const __m256i v_ffff0000 = _mm256_set1_epi32((uint32_t)0xffff0000);
+  const __m256i v_ff80 = _mm256_set1_epi16((uint16_t)0xff80);
+  const __m256i v_f800 = _mm256_set1_epi16((uint16_t)0xf800);
+  const __m256i v_c080 = _mm256_set1_epi16((uint16_t)0xc080);
+  const __m256i v_7fffffff = _mm256_set1_epi32((uint32_t)0x7fffffff);
+  __m256i running_max = _mm256_setzero_si256();
+  __m256i forbidden_bytemask = _mm256_setzero_si256();
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+    __m256i nextin = _mm256_loadu_si256((__m256i*)buf+1);
+    running_max = _mm256_max_epu32(_mm256_max_epu32(in, running_max), nextin);
+
+    // Pack 32-bit UTF-32 words to 16-bit UTF-16 words with unsigned saturation
+    __m256i in_16 = _mm256_packus_epi32(_mm256_and_si256(in, v_7fffffff), _mm256_and_si256(nextin, v_7fffffff));
+    in_16 = _mm256_permute4x64_epi64(in_16, 0b11011000);
+
+    // Try to apply UTF-16 => UTF-8 routine on 256 bits (haswell/avx2_convert_utf16_to_utf8.cpp)
+
+    if(_mm256_testz_si256(in_16, v_ff80)) { // ASCII fast path!!!!
+      // 1. pack the bytes
+      const __m128i utf8_packed = _mm_packus_epi16(_mm256_castsi256_si128(in_16),_mm256_extractf128_si256(in_16,1));
+      // 2. store (16 bytes)
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+      // 3. adjust pointers
+      buf += 16;
+      utf8_output += 16;
+      continue; // we are done for this round!
+    }
+    // no bits set above 7th bit
+    const __m256i one_byte_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_ff80), v_0000);
+    const uint32_t one_byte_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m256i one_or_two_bytes_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_f800), v_0000);
+    const uint32_t one_or_two_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_or_two_bytes_bytemask));
+    if (one_or_two_bytes_bitmask == 0xffffffff) {
+      // 1. prepare 2-byte values
+      // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+      // expected output   : [110a|aaaa|10bb|bbbb] x 8
+      const __m256i v_1f00 = _mm256_set1_epi16((int16_t)0x1f00);
+      const __m256i v_003f = _mm256_set1_epi16((int16_t)0x003f);
+
+      // t0 = [000a|aaaa|bbbb|bb00]
+      const __m256i t0 = _mm256_slli_epi16(in_16, 2);
+      // t1 = [000a|aaaa|0000|0000]
+      const __m256i t1 = _mm256_and_si256(t0, v_1f00);
+      // t2 = [0000|0000|00bb|bbbb]
+      const __m256i t2 = _mm256_and_si256(in_16, v_003f);
+      // t3 = [000a|aaaa|00bb|bbbb]
+      const __m256i t3 = _mm256_or_si256(t1, t2);
+      // t4 = [110a|aaaa|10bb|bbbb]
+      const __m256i t4 = _mm256_or_si256(t3, v_c080);
+
+      // 2. merge ASCII and 2-byte codewords
+      const __m256i utf8_unpacked = _mm256_blendv_epi8(t4, in_16, one_byte_bytemask);
+
+      // 3. prepare bitmask for 8-bit lookup
+      const uint32_t M0 = one_byte_bitmask & 0x55555555;
+      const uint32_t M1 = M0 >> 7;
+      const uint32_t M2 = (M1 | M0)  & 0x00ff00ff;
+      // 4. pack the bytes
+
+      const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2)][0];
+      const uint8_t* row_2 = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2>>16)][0];
+
+      const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+      const __m128i shuffle_2 = _mm_loadu_si128((__m128i*)(row_2 + 1));
+
+      const __m256i utf8_packed = _mm256_shuffle_epi8(utf8_unpacked, _mm256_setr_m128i(shuffle,shuffle_2));
+      // 5. store bytes
+      _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_packed));
+      utf8_output += row[0];
+      _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_packed,1));
+      utf8_output += row_2[0];
+
+      // 6. adjust pointers
+      buf += 16;
+      continue;
+    }
+    // Must check for overflow in packing
+    const __m256i saturation_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(_mm256_or_si256(in, nextin), v_ffff0000), v_0000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(saturation_bytemask));
+    if (saturation_bitmask == 0xffffffff) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+      const __m256i v_d800 = _mm256_set1_epi16((uint16_t)0xd800);
+      forbidden_bytemask = _mm256_or_si256(forbidden_bytemask, _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_f800), v_d800));
+
+      const __m256i dup_even = _mm256_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e,
+                                              0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+      /* In this branch we handle three cases:
+        1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+        2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+        3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+        We expand the input word (16-bit) into two words (32-bit), thus
+        we have room for four bytes. However, we need five distinct bit
+        layouts. Note that the last byte in cases #2 and #3 is the same.
+
+        We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+        in register t2.
+
+        We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+        either byte 1 for case #2 or byte 2 for case #3. Note that they
+        differ by exactly one bit.
+
+        Finally from these two words we build proper UTF-8 sequence, taking
+        into account the case (i.e, the number of bytes to write).
+      */
+      /**
+       * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+       * t2 => [0ccc|cccc] [10cc|cccc]
+       * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+       */
+#define vec(x) _mm256_set1_epi16(static_cast<uint16_t>(x))
+      // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+      const __m256i t0 = _mm256_shuffle_epi8(in_16, dup_even);
+      // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+      const __m256i t1 = _mm256_and_si256(t0, vec(0b0011111101111111));
+      // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+      const __m256i t2 = _mm256_or_si256 (t1, vec(0b1000000000000000));
+
+      // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+      const __m256i s0 = _mm256_srli_epi16(in_16, 4);
+      // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+      const __m256i s1 = _mm256_and_si256(s0, vec(0b0000111111111100));
+      // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+      const __m256i s2 = _mm256_maddubs_epi16(s1, vec(0x0140));
+      // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+      const __m256i s3 = _mm256_or_si256(s2, vec(0b1100000011100000));
+      const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+      const __m256i s4 = _mm256_xor_si256(s3, m0);
+#undef vec
+
+      // 4. expand words 16-bit => 32-bit
+      const __m256i out0 = _mm256_unpacklo_epi16(t2, s4);
+      const __m256i out1 = _mm256_unpackhi_epi16(t2, s4);
+
+      // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+      const uint32_t mask = (one_byte_bitmask & 0x55555555) |
+                            (one_or_two_bytes_bitmask & 0xaaaaaaaa);
+      // Due to the wider registers, the following path is less likely to be useful.
+      /*if(mask == 0) {
+        // We only have three-byte words. Use fast path.
+        const __m256i shuffle = _mm256_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1, 2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+        const __m256i utf8_0 = _mm256_shuffle_epi8(out0, shuffle);
+        const __m256i utf8_1 = _mm256_shuffle_epi8(out1, shuffle);
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_0));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_1));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_0,1));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_1,1));
+        utf8_output += 12;
+        buf += 16;
+        continue;
+      }*/
+      const uint8_t mask0 = uint8_t(mask);
+      const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+      const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+      const __m128i utf8_0 = _mm_shuffle_epi8(_mm256_castsi256_si128(out0), shuffle0);
+
+      const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+      const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+      const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+      const __m128i utf8_1 = _mm_shuffle_epi8(_mm256_castsi256_si128(out1), shuffle1);
+
+      const uint8_t mask2 = static_cast<uint8_t>(mask >> 16);
+      const uint8_t* row2 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask2][0];
+      const __m128i shuffle2 = _mm_loadu_si128((__m128i*)(row2 + 1));
+      const __m128i utf8_2 = _mm_shuffle_epi8(_mm256_extractf128_si256(out0,1), shuffle2);
+
+
+      const uint8_t mask3 = static_cast<uint8_t>(mask >> 24);
+      const uint8_t* row3 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask3][0];
+      const __m128i shuffle3 = _mm_loadu_si128((__m128i*)(row3 + 1));
+      const __m128i utf8_3 = _mm_shuffle_epi8(_mm256_extractf128_si256(out1,1), shuffle3);
+
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+      utf8_output += row0[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+      utf8_output += row1[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_2);
+      utf8_output += row2[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_3);
+      utf8_output += row3[0];
+      buf += 16;
+    } else {
+      // case: at least one 32-bit word is larger than 0xFFFF <=> it will produce four UTF-8 bytes.
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // may require large, non-trivial tables?
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFFFF80)==0) {  // 1-byte (ASCII)
+          *utf8_output++ = char(word);
+        } else if((word & 0xFFFFF800)==0) { // 2-byte
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word & 0xFFFF0000 )==0) {  // 3-byte
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(nullptr, utf8_output); }
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {  // 4-byte
+          if (word > 0x10FFFF) { return std::make_pair(nullptr, utf8_output); }
+          *utf8_output++ = char((word>>18) | 0b11110000);
+          *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  // check for invalid input
+  const __m256i v_10ffff = _mm256_set1_epi32((uint32_t)0x10ffff);
+  if(static_cast<uint32_t>(_mm256_movemask_epi8(_mm256_cmpeq_epi32(_mm256_max_epu32(running_max, v_10ffff), v_10ffff))) != 0xffffffff) {
+    return std::make_pair(nullptr, utf8_output);
+  }
+
+  if (static_cast<uint32_t>(_mm256_movemask_epi8(forbidden_bytemask)) != 0) { return std::make_pair(nullptr, utf8_output); }
+
+  return std::make_pair(buf, utf8_output);
+}
+
+
+std::pair<result, char*> avx2_convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) {
+  const char32_t* end = buf + len;
+  const char32_t* start = buf;
+
+  const __m256i v_0000 = _mm256_setzero_si256();
+  const __m256i v_ffff0000 = _mm256_set1_epi32((uint32_t)0xffff0000);
+  const __m256i v_ff80 = _mm256_set1_epi16((uint16_t)0xff80);
+  const __m256i v_f800 = _mm256_set1_epi16((uint16_t)0xf800);
+  const __m256i v_c080 = _mm256_set1_epi16((uint16_t)0xc080);
+  const __m256i v_7fffffff = _mm256_set1_epi32((uint32_t)0x7fffffff);
+  const __m256i v_10ffff = _mm256_set1_epi32((uint32_t)0x10ffff);
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+    __m256i nextin = _mm256_loadu_si256((__m256i*)buf+1);
+    // Check for too large input
+    const __m256i max_input = _mm256_max_epu32(_mm256_max_epu32(in, nextin), v_10ffff);
+    if(static_cast<uint32_t>(_mm256_movemask_epi8(_mm256_cmpeq_epi32(max_input, v_10ffff))) != 0xffffffff) {
+      return std::make_pair(result(error_code::TOO_LARGE, buf - start), utf8_output);
+    }
+
+    // Pack 32-bit UTF-32 words to 16-bit UTF-16 words with unsigned saturation
+    __m256i in_16 = _mm256_packus_epi32(_mm256_and_si256(in, v_7fffffff), _mm256_and_si256(nextin, v_7fffffff));
+    in_16 = _mm256_permute4x64_epi64(in_16, 0b11011000);
+
+    // Try to apply UTF-16 => UTF-8 routine on 256 bits (haswell/avx2_convert_utf16_to_utf8.cpp)
+
+    if(_mm256_testz_si256(in_16, v_ff80)) { // ASCII fast path!!!!
+      // 1. pack the bytes
+      const __m128i utf8_packed = _mm_packus_epi16(_mm256_castsi256_si128(in_16),_mm256_extractf128_si256(in_16,1));
+      // 2. store (16 bytes)
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+      // 3. adjust pointers
+      buf += 16;
+      utf8_output += 16;
+      continue; // we are done for this round!
+    }
+    // no bits set above 7th bit
+    const __m256i one_byte_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_ff80), v_0000);
+    const uint32_t one_byte_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m256i one_or_two_bytes_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_f800), v_0000);
+    const uint32_t one_or_two_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(one_or_two_bytes_bytemask));
+    if (one_or_two_bytes_bitmask == 0xffffffff) {
+      // 1. prepare 2-byte values
+      // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+      // expected output   : [110a|aaaa|10bb|bbbb] x 8
+      const __m256i v_1f00 = _mm256_set1_epi16((int16_t)0x1f00);
+      const __m256i v_003f = _mm256_set1_epi16((int16_t)0x003f);
+
+      // t0 = [000a|aaaa|bbbb|bb00]
+      const __m256i t0 = _mm256_slli_epi16(in_16, 2);
+      // t1 = [000a|aaaa|0000|0000]
+      const __m256i t1 = _mm256_and_si256(t0, v_1f00);
+      // t2 = [0000|0000|00bb|bbbb]
+      const __m256i t2 = _mm256_and_si256(in_16, v_003f);
+      // t3 = [000a|aaaa|00bb|bbbb]
+      const __m256i t3 = _mm256_or_si256(t1, t2);
+      // t4 = [110a|aaaa|10bb|bbbb]
+      const __m256i t4 = _mm256_or_si256(t3, v_c080);
+
+      // 2. merge ASCII and 2-byte codewords
+      const __m256i utf8_unpacked = _mm256_blendv_epi8(t4, in_16, one_byte_bytemask);
+
+      // 3. prepare bitmask for 8-bit lookup
+      const uint32_t M0 = one_byte_bitmask & 0x55555555;
+      const uint32_t M1 = M0 >> 7;
+      const uint32_t M2 = (M1 | M0)  & 0x00ff00ff;
+      // 4. pack the bytes
+
+      const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2)][0];
+      const uint8_t* row_2 = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[uint8_t(M2>>16)][0];
+
+      const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+      const __m128i shuffle_2 = _mm_loadu_si128((__m128i*)(row_2 + 1));
+
+      const __m256i utf8_packed = _mm256_shuffle_epi8(utf8_unpacked, _mm256_setr_m128i(shuffle,shuffle_2));
+      // 5. store bytes
+      _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_packed));
+      utf8_output += row[0];
+      _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_packed,1));
+      utf8_output += row_2[0];
+
+      // 6. adjust pointers
+      buf += 16;
+      continue;
+    }
+    // Must check for overflow in packing
+    const __m256i saturation_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(_mm256_or_si256(in, nextin), v_ffff0000), v_0000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(saturation_bytemask));
+    if (saturation_bitmask == 0xffffffff) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+
+      // Check for illegal surrogate words
+      const __m256i v_d800 = _mm256_set1_epi16((uint16_t)0xd800);
+      const __m256i forbidden_bytemask = _mm256_cmpeq_epi16(_mm256_and_si256(in_16, v_f800), v_d800);
+      if (static_cast<uint32_t>(_mm256_movemask_epi8(forbidden_bytemask)) != 0x0) {
+        return std::make_pair(result(error_code::SURROGATE, buf - start), utf8_output);
+      }
+
+      const __m256i dup_even = _mm256_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e,
+                                              0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+      /* In this branch we handle three cases:
+        1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+        2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+        3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+        We expand the input word (16-bit) into two words (32-bit), thus
+        we have room for four bytes. However, we need five distinct bit
+        layouts. Note that the last byte in cases #2 and #3 is the same.
+
+        We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+        in register t2.
+
+        We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+        either byte 1 for case #2 or byte 2 for case #3. Note that they
+        differ by exactly one bit.
+
+        Finally from these two words we build proper UTF-8 sequence, taking
+        into account the case (i.e, the number of bytes to write).
+      */
+      /**
+       * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+       * t2 => [0ccc|cccc] [10cc|cccc]
+       * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+       */
+#define vec(x) _mm256_set1_epi16(static_cast<uint16_t>(x))
+      // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+      const __m256i t0 = _mm256_shuffle_epi8(in_16, dup_even);
+      // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+      const __m256i t1 = _mm256_and_si256(t0, vec(0b0011111101111111));
+      // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+      const __m256i t2 = _mm256_or_si256 (t1, vec(0b1000000000000000));
+
+      // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+      const __m256i s0 = _mm256_srli_epi16(in_16, 4);
+      // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+      const __m256i s1 = _mm256_and_si256(s0, vec(0b0000111111111100));
+      // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+      const __m256i s2 = _mm256_maddubs_epi16(s1, vec(0x0140));
+      // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+      const __m256i s3 = _mm256_or_si256(s2, vec(0b1100000011100000));
+      const __m256i m0 = _mm256_andnot_si256(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+      const __m256i s4 = _mm256_xor_si256(s3, m0);
+#undef vec
+
+      // 4. expand words 16-bit => 32-bit
+      const __m256i out0 = _mm256_unpacklo_epi16(t2, s4);
+      const __m256i out1 = _mm256_unpackhi_epi16(t2, s4);
+
+      // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+      const uint32_t mask = (one_byte_bitmask & 0x55555555) |
+                            (one_or_two_bytes_bitmask & 0xaaaaaaaa);
+      // Due to the wider registers, the following path is less likely to be useful.
+      /*if(mask == 0) {
+        // We only have three-byte words. Use fast path.
+        const __m256i shuffle = _mm256_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1, 2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+        const __m256i utf8_0 = _mm256_shuffle_epi8(out0, shuffle);
+        const __m256i utf8_1 = _mm256_shuffle_epi8(out1, shuffle);
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_0));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_castsi256_si128(utf8_1));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_0,1));
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, _mm256_extractf128_si256(utf8_1,1));
+        utf8_output += 12;
+        buf += 16;
+        continue;
+      }*/
+      const uint8_t mask0 = uint8_t(mask);
+      const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+      const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+      const __m128i utf8_0 = _mm_shuffle_epi8(_mm256_castsi256_si128(out0), shuffle0);
+
+      const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+      const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+      const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+      const __m128i utf8_1 = _mm_shuffle_epi8(_mm256_castsi256_si128(out1), shuffle1);
+
+      const uint8_t mask2 = static_cast<uint8_t>(mask >> 16);
+      const uint8_t* row2 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask2][0];
+      const __m128i shuffle2 = _mm_loadu_si128((__m128i*)(row2 + 1));
+      const __m128i utf8_2 = _mm_shuffle_epi8(_mm256_extractf128_si256(out0,1), shuffle2);
+
+
+      const uint8_t mask3 = static_cast<uint8_t>(mask >> 24);
+      const uint8_t* row3 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask3][0];
+      const __m128i shuffle3 = _mm_loadu_si128((__m128i*)(row3 + 1));
+      const __m128i utf8_3 = _mm_shuffle_epi8(_mm256_extractf128_si256(out1,1), shuffle3);
+
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+      utf8_output += row0[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+      utf8_output += row1[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_2);
+      utf8_output += row2[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_3);
+      utf8_output += row3[0];
+      buf += 16;
+    } else {
+      // case: at least one 32-bit word is larger than 0xFFFF <=> it will produce four UTF-8 bytes.
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // may require large, non-trivial tables?
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFFFF80)==0) {  // 1-byte (ASCII)
+          *utf8_output++ = char(word);
+        } else if((word & 0xFFFFF800)==0) { // 2-byte
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word & 0xFFFF0000 )==0) {  // 3-byte
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(result(error_code::SURROGATE, buf - start + k), utf8_output); }
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {  // 4-byte
+          if (word > 0x10FFFF) { return std::make_pair(result(error_code::TOO_LARGE, buf - start + k), utf8_output); }
+          *utf8_output++ = char((word>>18) | 0b11110000);
+          *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf8_output);
+}
+/* end file src/haswell/avx2_convert_utf32_to_utf8.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=haswell/avx2_convert_utf32_to_utf16.cpp
+/* begin file src/haswell/avx2_convert_utf32_to_utf16.cpp */
+template <endianness big_endian>
+std::pair<const char32_t*, char16_t*> avx2_convert_utf32_to_utf16(const char32_t* buf, size_t len, char16_t* utf16_output) {
+  const char32_t* end = buf + len;
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+  __m256i forbidden_bytemask = _mm256_setzero_si256();
+
+
+  while (buf + 8 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+
+    const __m256i v_00000000 = _mm256_setzero_si256();
+    const __m256i v_ffff0000 = _mm256_set1_epi32((int32_t)0xffff0000);
+
+    // no bits set above 16th bit <=> can pack to UTF16 without surrogate pairs
+    const __m256i saturation_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_ffff0000), v_00000000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(saturation_bytemask));
+
+    if (saturation_bitmask == 0xffffffff) {
+      const __m256i v_f800 = _mm256_set1_epi32((uint32_t)0xf800);
+      const __m256i v_d800 = _mm256_set1_epi32((uint32_t)0xd800);
+      forbidden_bytemask = _mm256_or_si256(forbidden_bytemask, _mm256_cmpeq_epi32(_mm256_and_si256(in, v_f800), v_d800));
+
+      __m128i utf16_packed = _mm_packus_epi32(_mm256_castsi256_si128(in),_mm256_extractf128_si256(in,1));
+      if (big_endian) {
+        const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+        utf16_packed = _mm_shuffle_epi8(utf16_packed, swap);
+      }
+      _mm_storeu_si128((__m128i*)utf16_output, utf16_packed);
+      utf16_output += 8;
+      buf += 8;
+    } else {
+      size_t forward = 7;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFF0000)==0) {
+          // will not generate a surrogate pair
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(nullptr, utf16_output); }
+          *utf16_output++ = big_endian ? char16_t((uint16_t(word) >> 8) | (uint16_t(word) << 8)) : char16_t(word);
+        } else {
+          // will generate a surrogate pair
+          if (word > 0x10FFFF) { return std::make_pair(nullptr, utf16_output); }
+          word -= 0x10000;
+          uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+          uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+          if (big_endian) {
+            high_surrogate = uint16_t((high_surrogate >> 8) | (high_surrogate << 8));
+            low_surrogate = uint16_t((low_surrogate >> 8) | (low_surrogate << 8));
+          }
+          *utf16_output++ = char16_t(high_surrogate);
+          *utf16_output++ = char16_t(low_surrogate);
+        }
+      }
+      buf += k;
+    }
+  }
+
+  // check for invalid input
+  if (static_cast<uint32_t>(_mm256_movemask_epi8(forbidden_bytemask)) != 0) { return std::make_pair(nullptr, utf16_output); }
+
+  return std::make_pair(buf, utf16_output);
+}
+
+
+template <endianness big_endian>
+std::pair<result, char16_t*> avx2_convert_utf32_to_utf16_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) {
+  const char32_t* start = buf;
+  const char32_t* end = buf + len;
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 8 + safety_margin <= end) {
+    __m256i in = _mm256_loadu_si256((__m256i*)buf);
+
+    const __m256i v_00000000 = _mm256_setzero_si256();
+    const __m256i v_ffff0000 = _mm256_set1_epi32((int32_t)0xffff0000);
+
+    // no bits set above 16th bit <=> can pack to UTF16 without surrogate pairs
+    const __m256i saturation_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_ffff0000), v_00000000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(saturation_bytemask));
+
+    if (saturation_bitmask == 0xffffffff) {
+      const __m256i v_f800 = _mm256_set1_epi32((uint32_t)0xf800);
+      const __m256i v_d800 = _mm256_set1_epi32((uint32_t)0xd800);
+      const __m256i forbidden_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_f800), v_d800);
+      if (static_cast<uint32_t>(_mm256_movemask_epi8(forbidden_bytemask)) != 0x0) {
+        return std::make_pair(result(error_code::SURROGATE, buf - start), utf16_output);
+      }
+
+      __m128i utf16_packed = _mm_packus_epi32(_mm256_castsi256_si128(in),_mm256_extractf128_si256(in,1));
+      if (big_endian) {
+        const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+        utf16_packed = _mm_shuffle_epi8(utf16_packed, swap);
+      }
+      _mm_storeu_si128((__m128i*)utf16_output, utf16_packed);
+      utf16_output += 8;
+      buf += 8;
+    } else {
+      size_t forward = 7;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFF0000)==0) {
+          // will not generate a surrogate pair
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(result(error_code::SURROGATE, buf - start + k), utf16_output); }
+          *utf16_output++ = big_endian ? char16_t((uint16_t(word) >> 8) | (uint16_t(word) << 8)) : char16_t(word);
+        } else {
+          // will generate a surrogate pair
+          if (word > 0x10FFFF) { return std::make_pair(result(error_code::TOO_LARGE, buf - start + k), utf16_output); }
+          word -= 0x10000;
+          uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+          uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+          if (big_endian) {
+            high_surrogate = uint16_t((high_surrogate >> 8) | (high_surrogate << 8));
+            low_surrogate = uint16_t((low_surrogate >> 8) | (low_surrogate << 8));
+          }
+          *utf16_output++ = char16_t(high_surrogate);
+          *utf16_output++ = char16_t(low_surrogate);
+        }
+      }
+      buf += k;
+    }
+  }
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf16_output);
+}
+/* end file src/haswell/avx2_convert_utf32_to_utf16.cpp */
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/buf_block_reader.h
+/* begin file src/generic/buf_block_reader.h */
+namespace simdutf {
+namespace haswell {
+namespace {
+
+// Walks through a buffer in block-sized increments, loading the last part with spaces
+template<size_t STEP_SIZE>
+struct buf_block_reader {
+public:
+  simdutf_really_inline buf_block_reader(const uint8_t *_buf, size_t _len);
+  simdutf_really_inline size_t block_index();
+  simdutf_really_inline bool has_full_block() const;
+  simdutf_really_inline const uint8_t *full_block() const;
+  /**
+   * Get the last block, padded with spaces.
+   *
+   * There will always be a last block, with at least 1 byte, unless len == 0 (in which case this
+   * function fills the buffer with spaces and returns 0. In particular, if len == STEP_SIZE there
+   * will be 0 full_blocks and 1 remainder block with STEP_SIZE bytes and no spaces for padding.
+   *
+   * @return the number of effective characters in the last block.
+   */
+  simdutf_really_inline size_t get_remainder(uint8_t *dst) const;
+  simdutf_really_inline void advance();
+private:
+  const uint8_t *buf;
+  const size_t len;
+  const size_t lenminusstep;
+  size_t idx;
+};
+
+// Routines to print masks and text for debugging bitmask operations
+simdutf_unused static char * format_input_text_64(const uint8_t *text) {
+  static char *buf = reinterpret_cast<char*>(malloc(sizeof(simd8x64<uint8_t>) + 1));
+  for (size_t i=0; i<sizeof(simd8x64<uint8_t>); i++) {
+    buf[i] = int8_t(text[i]) < ' ' ? '_' : int8_t(text[i]);
+  }
+  buf[sizeof(simd8x64<uint8_t>)] = '\0';
+  return buf;
+}
+
+// Routines to print masks and text for debugging bitmask operations
+simdutf_unused static char * format_input_text(const simd8x64<uint8_t>& in) {
+  static char *buf = reinterpret_cast<char*>(malloc(sizeof(simd8x64<uint8_t>) + 1));
+  in.store(reinterpret_cast<uint8_t*>(buf));
+  for (size_t i=0; i<sizeof(simd8x64<uint8_t>); i++) {
+    if (buf[i] < ' ') { buf[i] = '_'; }
+  }
+  buf[sizeof(simd8x64<uint8_t>)] = '\0';
+  return buf;
+}
+
+simdutf_unused static char * format_mask(uint64_t mask) {
+  static char *buf = reinterpret_cast<char*>(malloc(64 + 1));
+  for (size_t i=0; i<64; i++) {
+    buf[i] = (mask & (size_t(1) << i)) ? 'X' : ' ';
+  }
+  buf[64] = '\0';
+  return buf;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline buf_block_reader<STEP_SIZE>::buf_block_reader(const uint8_t *_buf, size_t _len) : buf{_buf}, len{_len}, lenminusstep{len < STEP_SIZE ? 0 : len - STEP_SIZE}, idx{0} {}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline size_t buf_block_reader<STEP_SIZE>::block_index() { return idx; }
+
+template<size_t STEP_SIZE>
+simdutf_really_inline bool buf_block_reader<STEP_SIZE>::has_full_block() const {
+  return idx < lenminusstep;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline const uint8_t *buf_block_reader<STEP_SIZE>::full_block() const {
+  return &buf[idx];
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline size_t buf_block_reader<STEP_SIZE>::get_remainder(uint8_t *dst) const {
+  if(len == idx) { return 0; } // memcpy(dst, null, 0) will trigger an error with some sanitizers
+  std::memset(dst, 0x20, STEP_SIZE); // std::memset STEP_SIZE because it's more efficient to write out 8 or 16 bytes at once.
+  std::memcpy(dst, buf + idx, len - idx);
+  return len - idx;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline void buf_block_reader<STEP_SIZE>::advance() {
+  idx += STEP_SIZE;
+}
+
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/buf_block_reader.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_validation/utf8_lookup4_algorithm.h
+/* begin file src/generic/utf8_validation/utf8_lookup4_algorithm.h */
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace utf8_validation {
+
+using namespace simd;
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+  //
+  // Return nonzero if there are incomplete multibyte characters at the end of the block:
+  // e.g. if there is a 4-byte character, but it's 3 bytes from the end.
+  //
+  simdutf_really_inline simd8<uint8_t> is_incomplete(const simd8<uint8_t> input) {
+    // If the previous input's last 3 bytes match this, they're too short (they ended at EOF):
+    // ... 1111____ 111_____ 11______
+    static const uint8_t max_array[32] = {
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 0b11110000u-1, 0b11100000u-1, 0b11000000u-1
+    };
+    const simd8<uint8_t> max_value(&max_array[sizeof(max_array)-sizeof(simd8<uint8_t>)]);
+    return input.gt_bits(max_value);
+  }
+
+  struct utf8_checker {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+    // The last input we received
+    simd8<uint8_t> prev_input_block;
+    // Whether the last input we received was incomplete (used for ASCII fast path)
+    simd8<uint8_t> prev_incomplete;
+
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+    // The only problem that can happen at EOF is that a multibyte character is too short
+    // or a byte value too large in the last bytes: check_special_cases only checks for bytes
+    // too large in the first of two bytes.
+    simdutf_really_inline void check_eof() {
+      // If the previous block had incomplete UTF-8 characters at the end, an ASCII block can't
+      // possibly finish them.
+      this->error |= this->prev_incomplete;
+    }
+
+    simdutf_really_inline void check_next_input(const simd8x64<uint8_t>& input) {
+      if(simdutf_likely(is_ascii(input))) {
+        this->error |= this->prev_incomplete;
+      } else {
+        // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+        static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+            "We support either two or four chunks per 64-byte block.");
+        if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+          this->check_utf8_bytes(input.chunks[0], this->prev_input_block);
+          this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+        } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+          this->check_utf8_bytes(input.chunks[0], this->prev_input_block);
+          this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+          this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+        }
+        this->prev_incomplete = is_incomplete(input.chunks[simd8x64<uint8_t>::NUM_CHUNKS-1]);
+        this->prev_input_block = input.chunks[simd8x64<uint8_t>::NUM_CHUNKS-1];
+
+      }
+    }
+
+    // do not forget to call check_eof!
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // namespace utf8_validation
+
+using utf8_validation::utf8_checker;
+
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/utf8_validation/utf8_lookup4_algorithm.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_validation/utf8_validator.h
+/* begin file src/generic/utf8_validation/utf8_validator.h */
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace utf8_validation {
+
+/**
+ * Validates that the string is actual UTF-8.
+ */
+template<class checker>
+bool generic_validate_utf8(const uint8_t * input, size_t length) {
+    checker c{};
+    buf_block_reader<64> reader(input, length);
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      c.check_next_input(in);
+      reader.advance();
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    c.check_next_input(in);
+    reader.advance();
+    c.check_eof();
+    return !c.errors();
+}
+
+bool generic_validate_utf8(const char * input, size_t length) {
+  return generic_validate_utf8<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+/**
+ * Validates that the string is actual UTF-8 and stops on errors.
+ */
+template<class checker>
+result generic_validate_utf8_with_errors(const uint8_t * input, size_t length) {
+    checker c{};
+    buf_block_reader<64> reader(input, length);
+    size_t count{0};
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      c.check_next_input(in);
+      if(c.errors()) {
+        if (count != 0) { count--; } // Sometimes the error is only detected in the next chunk
+        result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+        res.count += count;
+        return res;
+      }
+      reader.advance();
+      count += 64;
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    c.check_next_input(in);
+    reader.advance();
+    c.check_eof();
+    if (c.errors()) {
+      result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(input) + count, length - count);
+      res.count += count;
+      return res;
+    } else {
+      return result(error_code::SUCCESS, length);
+    }
+}
+
+result generic_validate_utf8_with_errors(const char * input, size_t length) {
+  return generic_validate_utf8_with_errors<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+template<class checker>
+bool generic_validate_ascii(const uint8_t * input, size_t length) {
+    buf_block_reader<64> reader(input, length);
+    uint8_t blocks[64]{};
+    simd::simd8x64<uint8_t> running_or(blocks);
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      running_or |= in;
+      reader.advance();
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    running_or |= in;
+    return running_or.is_ascii();
+}
+
+bool generic_validate_ascii(const char * input, size_t length) {
+  return generic_validate_ascii<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+template<class checker>
+result generic_validate_ascii_with_errors(const uint8_t * input, size_t length) {
+  buf_block_reader<64> reader(input, length);
+  size_t count{0};
+  while (reader.has_full_block()) {
+    simd::simd8x64<uint8_t> in(reader.full_block());
+    if (!in.is_ascii()) {
+      result res = scalar::ascii::validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+      return result(res.error, count + res.count);
+    }
+    reader.advance();
+
+    count += 64;
+  }
+  uint8_t block[64]{};
+  reader.get_remainder(block);
+  simd::simd8x64<uint8_t> in(block);
+  if (!in.is_ascii()) {
+    result res = scalar::ascii::validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+    return result(res.error, count + res.count);
+  } else {
+    return result(error_code::SUCCESS, length);
+  }
+}
+
+result generic_validate_ascii_with_errors(const char * input, size_t length) {
+  return generic_validate_ascii_with_errors<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+} // namespace utf8_validation
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/utf8_validation/utf8_validator.h */
+// transcoding from UTF-8 to UTF-16
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf16/valid_utf8_to_utf16.h
+/* begin file src/generic/utf8_to_utf16/valid_utf8_to_utf16.h */
+
+
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace utf8_to_utf16 {
+
+using namespace simd;
+
+template <endianness endian>
+simdutf_warn_unused size_t convert_valid(const char* input, size_t size,
+    char16_t* utf16_output) noexcept {
+  // The implementation is not specific to haswell and should be moved to the generic directory.
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  const size_t safety_margin = 16; // to avoid overruns!
+  while(pos + 64 + safety_margin <= size) {
+    // this loop could be unrolled further. For example, we could process the mask
+    // far more than 64 bytes.
+    simd8x64<int8_t> in(reinterpret_cast<const int8_t *>(input + pos));
+    if(in.is_ascii()) {
+      in.store_ascii_as_utf16<endian>(utf16_output);
+      utf16_output += 64;
+      pos += 64;
+    } else {
+      // Slow path. We hope that the compiler will recognize that this is a slow path.
+      // Anything that is not a continuation mask is a 'leading byte', that is, the
+      // start of a new code point.
+      uint64_t utf8_continuation_mask = in.lt(-65 + 1);
+      // -65 is 0b10111111 in two-complement's, so largest possible continuation byte
+      uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+      // The *start* of code points is not so useful, rather, we want the *end* of code points.
+      uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+      // We process in blocks of up to 12 bytes except possibly
+      // for fast paths which may process up to 16 bytes. For the
+      // slow path to work, we should have at least 12 input bytes left.
+      size_t max_starting_point = (pos + 64) - 12;
+      // Next loop is going to run at least five times when using solely
+      // the slow/regular path, and at least four times if there are fast paths.
+      while(pos < max_starting_point) {
+        // Performance note: our ability to compute 'consumed' and
+        // then shift and recompute is critical. If there is a
+        // latency of, say, 4 cycles on getting 'consumed', then
+        // the inner loop might have a total latency of about 6 cycles.
+        // Yet we process between 6 to 12 inputs bytes, thus we get
+        // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+        // for this section of the code. Hence, there is a limit
+        // to how much we can further increase this latency before
+        // it seriously harms performance.
+        //
+        // Thus we may allow convert_masked_utf8_to_utf16 to process
+        // more bytes at a time under a fast-path mode where 16 bytes
+        // are consumed at once (e.g., when encountering ASCII).
+        size_t consumed = convert_masked_utf8_to_utf16<endian>(input + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+        pos += consumed;
+        utf8_end_of_code_point_mask >>= consumed;
+      }
+      // At this point there may remain between 0 and 12 bytes in the
+      // 64-byte block.These bytes will be processed again. So we have an
+      // 80% efficiency (in the worst case). In practice we expect an
+      // 85% to 90% efficiency.
+    }
+  }
+  utf16_output += scalar::utf8_to_utf16::convert_valid<endian>(input + pos, size - pos, utf16_output);
+  return utf16_output - start;
+}
+
+} // namespace utf8_to_utf16
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf16/valid_utf8_to_utf16.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf16/utf8_to_utf16.h
+/* begin file src/generic/utf8_to_utf16/utf8_to_utf16.h */
+
+
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace utf8_to_utf16 {
+using namespace simd;
+
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+
+  struct validating_transcoder {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+
+    validating_transcoder() : error(uint8_t(0)) {}
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+
+    template <endianness endian>
+    simdutf_really_inline size_t convert(const char* in, size_t size, char16_t* utf16_output) {
+      size_t pos = 0;
+      char16_t* start{utf16_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf16<endian>(utf16_output);
+          utf16_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf16<endian>(in + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) { return 0; }
+      if(pos < size) {
+        size_t howmany  = scalar::utf8_to_utf16::convert<endian>(in + pos, size - pos, utf16_output);
+        if(howmany == 0) { return 0; }
+        utf16_output += howmany;
+      }
+      return utf16_output - start;
+    }
+
+    template <endianness endian>
+    simdutf_really_inline result convert_with_errors(const char* in, size_t size, char16_t* utf16_output) {
+      size_t pos = 0;
+      char16_t* start{utf16_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf16<endian>(utf16_output);
+          utf16_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          if (errors()) {
+            result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+            res.count += pos;
+            return res;
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf16<endian>(in + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) {
+        result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+        res.count += pos;
+        return res;
+      }
+      if(pos < size) {
+        result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+        if (res.error) {    // In case of error, we want the error position
+          res.count += pos;
+          return res;
+        } else {    // In case of success, we want the number of word written
+          utf16_output += res.count;
+        }
+      }
+      return result(error_code::SUCCESS, utf16_output - start);
+    }
+
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // utf8_to_utf16 namespace
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf16/utf8_to_utf16.h */
+// transcoding from UTF-8 to UTF-32
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf32/valid_utf8_to_utf32.h
+/* begin file src/generic/utf8_to_utf32/valid_utf8_to_utf32.h */
+
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace utf8_to_utf32 {
+
+using namespace simd;
+
+
+simdutf_warn_unused size_t convert_valid(const char* input, size_t size,
+    char32_t* utf32_output) noexcept {
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  const size_t safety_margin = 16; // to avoid overruns!
+  while(pos + 64 + safety_margin <= size) {
+    simd8x64<int8_t> in(reinterpret_cast<const int8_t *>(input + pos));
+    if(in.is_ascii()) {
+      in.store_ascii_as_utf32(utf32_output);
+      utf32_output += 64;
+      pos += 64;
+    } else {
+    // -65 is 0b10111111 in two-complement's, so largest possible continuation byte
+    uint64_t utf8_continuation_mask = in.lt(-65 + 1);
+    uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+    uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+    size_t max_starting_point = (pos + 64) - 12;
+    while(pos < max_starting_point) {
+      size_t consumed = convert_masked_utf8_to_utf32(input + pos,
+                          utf8_end_of_code_point_mask, utf32_output);
+      pos += consumed;
+      utf8_end_of_code_point_mask >>= consumed;
+      }
+    }
+  }
+  utf32_output += scalar::utf8_to_utf32::convert_valid(input + pos, size - pos, utf32_output);
+  return utf32_output - start;
+}
+
+
+} // namespace utf8_to_utf32
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf32/valid_utf8_to_utf32.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf32/utf8_to_utf32.h
+/* begin file src/generic/utf8_to_utf32/utf8_to_utf32.h */
+
+
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace utf8_to_utf32 {
+using namespace simd;
+
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+
+  struct validating_transcoder {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+
+    validating_transcoder() : error(uint8_t(0)) {}
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+
+
+    simdutf_really_inline size_t convert(const char* in, size_t size, char32_t* utf32_output) {
+      size_t pos = 0;
+      char32_t* start{utf32_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf32(utf32_output);
+          utf32_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf32(in + pos,
+                            utf8_end_of_code_point_mask, utf32_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) { return 0; }
+      if(pos < size) {
+        size_t howmany  = scalar::utf8_to_utf32::convert(in + pos, size - pos, utf32_output);
+        if(howmany == 0) { return 0; }
+        utf32_output += howmany;
+      }
+      return utf32_output - start;
+    }
+
+    simdutf_really_inline result convert_with_errors(const char* in, size_t size, char32_t* utf32_output) {
+      size_t pos = 0;
+      char32_t* start{utf32_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf32(utf32_output);
+          utf32_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          if (errors()) {
+            result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+            res.count += pos;
+            return res;
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf32(in + pos,
+                            utf8_end_of_code_point_mask, utf32_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) {
+        result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+        res.count += pos;
+        return res;
+      }
+      if(pos < size) {
+        result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+        if (res.error) {    // In case of error, we want the error position
+          res.count += pos;
+          return res;
+        } else {    // In case of success, we want the number of word written
+          utf32_output += res.count;
+        }
+      }
+      return result(error_code::SUCCESS, utf32_output - start);
+    }
+
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // utf8_to_utf32 namespace
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf32/utf8_to_utf32.h */
+// other functions
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8.h
+/* begin file src/generic/utf8.h */
+
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace utf8 {
+
+using namespace simd;
+
+simdutf_really_inline size_t count_code_points(const char* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    for(;pos + 64 <= size; pos += 64) {
+      simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+      uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+      count += 64 - count_ones(utf8_continuation_mask);
+    }
+    return count + scalar::utf8::count_code_points(in + pos, size - pos);
+}
+
+
+simdutf_really_inline size_t utf16_length_from_utf8(const char* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 64 <= size; pos += 64) {
+      simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+      uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+      // We count one word for anything that is not a continuation (so
+      // leading bytes).
+      count += 64 - count_ones(utf8_continuation_mask);
+      int64_t utf8_4byte = input.gteq_unsigned(240);
+      count += count_ones(utf8_4byte);
+    }
+    return count + scalar::utf8::utf16_length_from_utf8(in + pos, size - pos);
+}
+
+
+simdutf_really_inline size_t utf32_length_from_utf8(const char* in, size_t size) {
+    return count_code_points(in, size);
+}
+} // utf8 namespace
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/utf8.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf16.h
+/* begin file src/generic/utf16.h */
+namespace simdutf {
+namespace haswell {
+namespace {
+namespace utf16 {
+
+template <endianness big_endian>
+simdutf_really_inline size_t count_code_points(const char16_t* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    for(;pos + 32 <= size; pos += 32) {
+      simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+      if (big_endian) input.swap_bytes();
+      uint64_t not_pair = input.not_in_range(0xDC00, 0xDFFF);
+      count += count_ones(not_pair) / 2;
+    }
+    return count + scalar::utf16::count_code_points<big_endian>(in + pos, size - pos);
+}
+
+template <endianness big_endian>
+simdutf_really_inline size_t utf8_length_from_utf16(const char16_t* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 32 <= size; pos += 32) {
+      simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+      if (big_endian) input.swap_bytes();
+      uint64_t ascii_mask = input.lteq(0x7F);
+      uint64_t twobyte_mask = input.lteq(0x7FF);
+      uint64_t not_pair_mask = input.not_in_range(0xD800, 0xDFFF);
+
+      size_t ascii_count = count_ones(ascii_mask) / 2;
+      size_t twobyte_count = count_ones(twobyte_mask & ~ ascii_mask) / 2;
+      size_t threebyte_count = count_ones(not_pair_mask & ~ twobyte_mask) / 2;
+      size_t fourbyte_count = 32 - count_ones(not_pair_mask) / 2;
+      count += 2 * fourbyte_count + 3 * threebyte_count + 2 * twobyte_count + ascii_count;
+    }
+    return count + scalar::utf16::utf8_length_from_utf16<big_endian>(in + pos, size - pos);
+}
+
+template <endianness big_endian>
+simdutf_really_inline size_t utf32_length_from_utf16(const char16_t* in, size_t size) {
+    return count_code_points<big_endian>(in, size);
+}
+
+simdutf_really_inline void change_endianness_utf16(const char16_t* in, size_t size, char16_t* output) {
+  size_t pos = 0;
+
+  while (pos + 32 <= size) {
+    simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+    input.swap_bytes();
+    input.store(reinterpret_cast<uint16_t *>(output));
+    pos += 32;
+    output += 32;
+  }
+
+  scalar::utf16::change_endianness_utf16(in + pos, size - pos, output);
+}
+
+} // utf16
+} // unnamed namespace
+} // namespace haswell
+} // namespace simdutf
+/* end file src/generic/utf16.h */
+
+namespace simdutf {
+namespace haswell {
+
+simdutf_warn_unused int implementation::detect_encodings(const char * input, size_t length) const noexcept {
+  // If there is a BOM, then we trust it.
+  auto bom_encoding = simdutf::BOM::check_bom(input, length);
+  if(bom_encoding != encoding_type::unspecified) { return bom_encoding; }
+  if (length % 2 == 0) {
+    return avx2_detect_encodings<utf8_validation::utf8_checker>(input, length);
+  } else {
+    if (implementation::validate_utf8(input, length)) {
+      return simdutf::encoding_type::UTF8;
+    } else {
+      return simdutf::encoding_type::unspecified;
+    }
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf8(const char *buf, size_t len) const noexcept {
+  return haswell::utf8_validation::generic_validate_utf8(buf,len);
+}
+
+simdutf_warn_unused result implementation::validate_utf8_with_errors(const char *buf, size_t len) const noexcept {
+  return haswell::utf8_validation::generic_validate_utf8_with_errors(buf,len);
+}
+
+simdutf_warn_unused bool implementation::validate_ascii(const char *buf, size_t len) const noexcept {
+  return haswell::utf8_validation::generic_validate_ascii(buf,len);
+}
+
+simdutf_warn_unused result implementation::validate_ascii_with_errors(const char *buf, size_t len) const noexcept {
+  return haswell::utf8_validation::generic_validate_ascii_with_errors(buf,len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf16le(const char16_t *buf, size_t len) const noexcept {
+  const char16_t* tail = avx2_validate_utf16<endianness::LITTLE>(buf, len);
+  if (tail) {
+    return scalar::utf16::validate<endianness::LITTLE>(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf16be(const char16_t *buf, size_t len) const noexcept {
+  const char16_t* tail = avx2_validate_utf16<endianness::BIG>(buf, len);
+  if (tail) {
+    return scalar::utf16::validate<endianness::BIG>(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept {
+  result res = avx2_validate_utf16_with_errors<endianness::LITTLE>(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf16::validate_with_errors<endianness::LITTLE>(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept {
+  result res = avx2_validate_utf16_with_errors<endianness::BIG>(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf16::validate_with_errors<endianness::BIG>(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf32(const char32_t *buf, size_t len) const noexcept {
+  const char32_t* tail = avx2_validate_utf32le(buf, len);
+  if (tail) {
+    return scalar::utf32::validate(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept {
+  result res = avx2_validate_utf32le_with_errors(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf32::validate_with_errors(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16le(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16be(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16le_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16be_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert_with_errors<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16le(const char* input, size_t size,
+    char16_t* utf16_output) const noexcept {
+   return utf8_to_utf16::convert_valid<endianness::LITTLE>(input, size,  utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16be(const char* input, size_t size,
+    char16_t* utf16_output) const noexcept {
+   return utf8_to_utf16::convert_valid<endianness::BIG>(input, size,  utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf32(const char* buf, size_t len, char32_t* utf32_output) const noexcept {
+  utf8_to_utf32::validating_transcoder converter;
+  return converter.convert(buf, len, utf32_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf32_with_errors(const char* buf, size_t len, char32_t* utf32_output) const noexcept {
+  utf8_to_utf32::validating_transcoder converter;
+  return converter.convert_with_errors(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf32(const char* input, size_t size,
+    char32_t* utf32_output) const noexcept {
+  return utf8_to_utf32::convert_valid(input, size,  utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char16_t*, char*> ret = haswell::avx2_convert_utf16_to_utf8<endianness::LITTLE>(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf8::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char16_t*, char*> ret = haswell::avx2_convert_utf16_to_utf8<endianness::BIG>(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf8::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = haswell::avx2_convert_utf16_to_utf8_with_errors<endianness::LITTLE>(buf, len, utf8_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf8::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = haswell::avx2_convert_utf16_to_utf8_with_errors<endianness::BIG>(buf, len, utf8_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf8::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf16le_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf16be_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char32_t*, char*> ret = avx2_convert_utf32_to_utf8(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf8::convert(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = haswell::avx2_convert_utf32_to_utf8_with_errors(buf, len, utf8_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf8::convert_with_errors(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::pair<const char16_t*, char32_t*> ret = haswell::avx2_convert_utf16_to_utf32<endianness::LITTLE>(buf, len, utf32_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf32_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::pair<const char16_t*, char32_t*> ret = haswell::avx2_convert_utf16_to_utf32<endianness::BIG>(buf, len, utf32_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf32_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char32_t*> ret = haswell::avx2_convert_utf16_to_utf32_with_errors<endianness::LITTLE>(buf, len, utf32_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf32_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char32_t*> ret = haswell::avx2_convert_utf16_to_utf32_with_errors<endianness::BIG>(buf, len, utf32_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf32_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf32_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  std::pair<const char32_t*, char16_t*> ret = avx2_convert_utf32_to_utf16<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf16_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf16::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  std::pair<const char32_t*, char16_t*> ret = avx2_convert_utf32_to_utf16<endianness::BIG>(buf, len, utf16_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf16_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf16::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16le_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char16_t*> ret = haswell::avx2_convert_utf32_to_utf16_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf16::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf16_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16be_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char16_t*> ret = haswell::avx2_convert_utf32_to_utf16_with_errors<endianness::BIG>(buf, len, utf16_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf16::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf16_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return convert_utf32_to_utf16le(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return convert_utf32_to_utf16be(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return convert_utf16le_to_utf32(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return convert_utf16be_to_utf32(buf, len, utf32_output);
+}
+
+void implementation::change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) const noexcept {
+  utf16::change_endianness_utf16(input, length, output);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::count_code_points<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::count_code_points<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf8(const char * input, size_t length) const noexcept {
+  return utf8::count_code_points(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf8_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf8_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf32_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf32_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf8(const char * input, size_t length) const noexcept {
+  return utf8::utf16_length_from_utf8(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  const __m256i v_00000000 = _mm256_setzero_si256();
+  const __m256i v_ffffff80 = _mm256_set1_epi32((uint32_t)0xffffff80);
+  const __m256i v_fffff800 = _mm256_set1_epi32((uint32_t)0xfffff800);
+  const __m256i v_ffff0000 = _mm256_set1_epi32((uint32_t)0xffff0000);
+  size_t pos = 0;
+  size_t count = 0;
+  for(;pos + 8 <= length; pos += 8) {
+    __m256i in = _mm256_loadu_si256((__m256i*)(input + pos));
+    const __m256i ascii_bytes_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_ffffff80), v_00000000);
+    const __m256i one_two_bytes_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_fffff800), v_00000000);
+    const __m256i two_bytes_bytemask = _mm256_xor_si256(one_two_bytes_bytemask, ascii_bytes_bytemask);
+    const __m256i one_two_three_bytes_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_ffff0000), v_00000000);
+    const __m256i three_bytes_bytemask = _mm256_xor_si256(one_two_three_bytes_bytemask, one_two_bytes_bytemask);
+    const uint32_t ascii_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(ascii_bytes_bytemask));
+    const uint32_t two_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(two_bytes_bytemask));
+    const uint32_t three_bytes_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(three_bytes_bytemask));
+
+    size_t ascii_count = count_ones(ascii_bytes_bitmask) / 4;
+    size_t two_bytes_count = count_ones(two_bytes_bitmask) / 4;
+    size_t three_bytes_count = count_ones(three_bytes_bitmask) / 4;
+    count += 32 - 3*ascii_count - 2*two_bytes_count - three_bytes_count;
+  }
+  return count + scalar::utf32::utf8_length_from_utf32(input + pos, length - pos);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  const __m256i v_00000000 = _mm256_setzero_si256();
+  const __m256i v_ffff0000 = _mm256_set1_epi32((uint32_t)0xffff0000);
+  size_t pos = 0;
+  size_t count = 0;
+  for(;pos + 8 <= length; pos += 8) {
+    __m256i in = _mm256_loadu_si256((__m256i*)(input + pos));
+    const __m256i surrogate_bytemask = _mm256_cmpeq_epi32(_mm256_and_si256(in, v_ffff0000), v_00000000);
+    const uint32_t surrogate_bitmask = static_cast<uint32_t>(_mm256_movemask_epi8(surrogate_bytemask));
+    size_t surrogate_count = (32-count_ones(surrogate_bitmask))/4;
+    count += 8 + surrogate_count;
+  }
+  return count + scalar::utf32::utf16_length_from_utf32(input + pos, length - pos);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf8(const char * input, size_t length) const noexcept {
+  return utf8::utf32_length_from_utf8(input, length);
+}
+
+} // namespace haswell
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/haswell/end.h
+/* begin file src/simdutf/haswell/end.h */
+SIMDUTF_UNTARGET_REGION
+/* end file src/simdutf/haswell/end.h */
+/* end file src/haswell/implementation.cpp */
+#endif
+#if SIMDUTF_IMPLEMENTATION_PPC64
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=ppc64/implementation.cpp
+/* begin file src/ppc64/implementation.cpp */
+
+
+
+
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64/begin.h
+/* begin file src/simdutf/ppc64/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "ppc64"
+// #define SIMDUTF_IMPLEMENTATION ppc64
+/* end file src/simdutf/ppc64/begin.h */
+namespace simdutf {
+namespace ppc64 {
+namespace {
+#ifndef SIMDUTF_PPC64_H
+#error "ppc64.h must be included"
+#endif
+using namespace simd;
+
+
+simdutf_really_inline bool is_ascii(const simd8x64<uint8_t>& input) {
+  // careful: 0x80 is not ascii.
+  return input.reduce_or().saturating_sub(0b01111111u).bits_not_set_anywhere();
+}
+
+simdutf_unused simdutf_really_inline simd8<bool> must_be_continuation(const simd8<uint8_t> prev1, const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
+  simd8<uint8_t> is_second_byte = prev1.saturating_sub(0b11000000u-1); // Only 11______ will be > 0
+  simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0b11100000u-1); // Only 111_____ will be > 0
+  simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0b11110000u-1); // Only 1111____ will be > 0
+  // Caller requires a bool (all 1's). All values resulting from the subtraction will be <= 64, so signed comparison is fine.
+  return simd8<int8_t>(is_second_byte | is_third_byte | is_fourth_byte) > int8_t(0);
+}
+
+simdutf_really_inline simd8<bool> must_be_2_3_continuation(const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
+  simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0b11100000u-1); // Only 111_____ will be > 0
+  simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0b11110000u-1); // Only 1111____ will be > 0
+  // Caller requires a bool (all 1's). All values resulting from the subtraction will be <= 64, so signed comparison is fine.
+  return simd8<int8_t>(is_third_byte | is_fourth_byte) > int8_t(0);
+}
+
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/buf_block_reader.h
+/* begin file src/generic/buf_block_reader.h */
+namespace simdutf {
+namespace ppc64 {
+namespace {
+
+// Walks through a buffer in block-sized increments, loading the last part with spaces
+template<size_t STEP_SIZE>
+struct buf_block_reader {
+public:
+  simdutf_really_inline buf_block_reader(const uint8_t *_buf, size_t _len);
+  simdutf_really_inline size_t block_index();
+  simdutf_really_inline bool has_full_block() const;
+  simdutf_really_inline const uint8_t *full_block() const;
+  /**
+   * Get the last block, padded with spaces.
+   *
+   * There will always be a last block, with at least 1 byte, unless len == 0 (in which case this
+   * function fills the buffer with spaces and returns 0. In particular, if len == STEP_SIZE there
+   * will be 0 full_blocks and 1 remainder block with STEP_SIZE bytes and no spaces for padding.
+   *
+   * @return the number of effective characters in the last block.
+   */
+  simdutf_really_inline size_t get_remainder(uint8_t *dst) const;
+  simdutf_really_inline void advance();
+private:
+  const uint8_t *buf;
+  const size_t len;
+  const size_t lenminusstep;
+  size_t idx;
+};
+
+// Routines to print masks and text for debugging bitmask operations
+simdutf_unused static char * format_input_text_64(const uint8_t *text) {
+  static char *buf = reinterpret_cast<char*>(malloc(sizeof(simd8x64<uint8_t>) + 1));
+  for (size_t i=0; i<sizeof(simd8x64<uint8_t>); i++) {
+    buf[i] = int8_t(text[i]) < ' ' ? '_' : int8_t(text[i]);
+  }
+  buf[sizeof(simd8x64<uint8_t>)] = '\0';
+  return buf;
+}
+
+// Routines to print masks and text for debugging bitmask operations
+simdutf_unused static char * format_input_text(const simd8x64<uint8_t>& in) {
+  static char *buf = reinterpret_cast<char*>(malloc(sizeof(simd8x64<uint8_t>) + 1));
+  in.store(reinterpret_cast<uint8_t*>(buf));
+  for (size_t i=0; i<sizeof(simd8x64<uint8_t>); i++) {
+    if (buf[i] < ' ') { buf[i] = '_'; }
+  }
+  buf[sizeof(simd8x64<uint8_t>)] = '\0';
+  return buf;
+}
+
+simdutf_unused static char * format_mask(uint64_t mask) {
+  static char *buf = reinterpret_cast<char*>(malloc(64 + 1));
+  for (size_t i=0; i<64; i++) {
+    buf[i] = (mask & (size_t(1) << i)) ? 'X' : ' ';
+  }
+  buf[64] = '\0';
+  return buf;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline buf_block_reader<STEP_SIZE>::buf_block_reader(const uint8_t *_buf, size_t _len) : buf{_buf}, len{_len}, lenminusstep{len < STEP_SIZE ? 0 : len - STEP_SIZE}, idx{0} {}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline size_t buf_block_reader<STEP_SIZE>::block_index() { return idx; }
+
+template<size_t STEP_SIZE>
+simdutf_really_inline bool buf_block_reader<STEP_SIZE>::has_full_block() const {
+  return idx < lenminusstep;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline const uint8_t *buf_block_reader<STEP_SIZE>::full_block() const {
+  return &buf[idx];
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline size_t buf_block_reader<STEP_SIZE>::get_remainder(uint8_t *dst) const {
+  if(len == idx) { return 0; } // memcpy(dst, null, 0) will trigger an error with some sanitizers
+  std::memset(dst, 0x20, STEP_SIZE); // std::memset STEP_SIZE because it's more efficient to write out 8 or 16 bytes at once.
+  std::memcpy(dst, buf + idx, len - idx);
+  return len - idx;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline void buf_block_reader<STEP_SIZE>::advance() {
+  idx += STEP_SIZE;
+}
+
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/buf_block_reader.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_validation/utf8_lookup4_algorithm.h
+/* begin file src/generic/utf8_validation/utf8_lookup4_algorithm.h */
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace utf8_validation {
+
+using namespace simd;
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+  //
+  // Return nonzero if there are incomplete multibyte characters at the end of the block:
+  // e.g. if there is a 4-byte character, but it's 3 bytes from the end.
+  //
+  simdutf_really_inline simd8<uint8_t> is_incomplete(const simd8<uint8_t> input) {
+    // If the previous input's last 3 bytes match this, they're too short (they ended at EOF):
+    // ... 1111____ 111_____ 11______
+    static const uint8_t max_array[32] = {
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 0b11110000u-1, 0b11100000u-1, 0b11000000u-1
+    };
+    const simd8<uint8_t> max_value(&max_array[sizeof(max_array)-sizeof(simd8<uint8_t>)]);
+    return input.gt_bits(max_value);
+  }
+
+  struct utf8_checker {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+    // The last input we received
+    simd8<uint8_t> prev_input_block;
+    // Whether the last input we received was incomplete (used for ASCII fast path)
+    simd8<uint8_t> prev_incomplete;
+
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+    // The only problem that can happen at EOF is that a multibyte character is too short
+    // or a byte value too large in the last bytes: check_special_cases only checks for bytes
+    // too large in the first of two bytes.
+    simdutf_really_inline void check_eof() {
+      // If the previous block had incomplete UTF-8 characters at the end, an ASCII block can't
+      // possibly finish them.
+      this->error |= this->prev_incomplete;
+    }
+
+    simdutf_really_inline void check_next_input(const simd8x64<uint8_t>& input) {
+      if(simdutf_likely(is_ascii(input))) {
+        this->error |= this->prev_incomplete;
+      } else {
+        // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+        static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+            "We support either two or four chunks per 64-byte block.");
+        if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+          this->check_utf8_bytes(input.chunks[0], this->prev_input_block);
+          this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+        } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+          this->check_utf8_bytes(input.chunks[0], this->prev_input_block);
+          this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+          this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+        }
+        this->prev_incomplete = is_incomplete(input.chunks[simd8x64<uint8_t>::NUM_CHUNKS-1]);
+        this->prev_input_block = input.chunks[simd8x64<uint8_t>::NUM_CHUNKS-1];
+
+      }
+    }
+
+    // do not forget to call check_eof!
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // namespace utf8_validation
+
+using utf8_validation::utf8_checker;
+
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/utf8_validation/utf8_lookup4_algorithm.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_validation/utf8_validator.h
+/* begin file src/generic/utf8_validation/utf8_validator.h */
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace utf8_validation {
+
+/**
+ * Validates that the string is actual UTF-8.
+ */
+template<class checker>
+bool generic_validate_utf8(const uint8_t * input, size_t length) {
+    checker c{};
+    buf_block_reader<64> reader(input, length);
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      c.check_next_input(in);
+      reader.advance();
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    c.check_next_input(in);
+    reader.advance();
+    c.check_eof();
+    return !c.errors();
+}
+
+bool generic_validate_utf8(const char * input, size_t length) {
+  return generic_validate_utf8<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+/**
+ * Validates that the string is actual UTF-8 and stops on errors.
+ */
+template<class checker>
+result generic_validate_utf8_with_errors(const uint8_t * input, size_t length) {
+    checker c{};
+    buf_block_reader<64> reader(input, length);
+    size_t count{0};
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      c.check_next_input(in);
+      if(c.errors()) {
+        if (count != 0) { count--; } // Sometimes the error is only detected in the next chunk
+        result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+        res.count += count;
+        return res;
+      }
+      reader.advance();
+      count += 64;
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    c.check_next_input(in);
+    reader.advance();
+    c.check_eof();
+    if (c.errors()) {
+      result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(input) + count, length - count);
+      res.count += count;
+      return res;
+    } else {
+      return result(error_code::SUCCESS, length);
+    }
+}
+
+result generic_validate_utf8_with_errors(const char * input, size_t length) {
+  return generic_validate_utf8_with_errors<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+template<class checker>
+bool generic_validate_ascii(const uint8_t * input, size_t length) {
+    buf_block_reader<64> reader(input, length);
+    uint8_t blocks[64]{};
+    simd::simd8x64<uint8_t> running_or(blocks);
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      running_or |= in;
+      reader.advance();
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    running_or |= in;
+    return running_or.is_ascii();
+}
+
+bool generic_validate_ascii(const char * input, size_t length) {
+  return generic_validate_ascii<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+template<class checker>
+result generic_validate_ascii_with_errors(const uint8_t * input, size_t length) {
+  buf_block_reader<64> reader(input, length);
+  size_t count{0};
+  while (reader.has_full_block()) {
+    simd::simd8x64<uint8_t> in(reader.full_block());
+    if (!in.is_ascii()) {
+      result res = scalar::ascii::validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+      return result(res.error, count + res.count);
+    }
+    reader.advance();
+
+    count += 64;
+  }
+  uint8_t block[64]{};
+  reader.get_remainder(block);
+  simd::simd8x64<uint8_t> in(block);
+  if (!in.is_ascii()) {
+    result res = scalar::ascii::validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+    return result(res.error, count + res.count);
+  } else {
+    return result(error_code::SUCCESS, length);
+  }
+}
+
+result generic_validate_ascii_with_errors(const char * input, size_t length) {
+  return generic_validate_ascii_with_errors<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+} // namespace utf8_validation
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/utf8_validation/utf8_validator.h */
+// transcoding from UTF-8 to UTF-16
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf16/valid_utf8_to_utf16.h
+/* begin file src/generic/utf8_to_utf16/valid_utf8_to_utf16.h */
+
+
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace utf8_to_utf16 {
+
+using namespace simd;
+
+template <endianness endian>
+simdutf_warn_unused size_t convert_valid(const char* input, size_t size,
+    char16_t* utf16_output) noexcept {
+  // The implementation is not specific to haswell and should be moved to the generic directory.
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  const size_t safety_margin = 16; // to avoid overruns!
+  while(pos + 64 + safety_margin <= size) {
+    // this loop could be unrolled further. For example, we could process the mask
+    // far more than 64 bytes.
+    simd8x64<int8_t> in(reinterpret_cast<const int8_t *>(input + pos));
+    if(in.is_ascii()) {
+      in.store_ascii_as_utf16<endian>(utf16_output);
+      utf16_output += 64;
+      pos += 64;
+    } else {
+      // Slow path. We hope that the compiler will recognize that this is a slow path.
+      // Anything that is not a continuation mask is a 'leading byte', that is, the
+      // start of a new code point.
+      uint64_t utf8_continuation_mask = in.lt(-65 + 1);
+      // -65 is 0b10111111 in two-complement's, so largest possible continuation byte
+      uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+      // The *start* of code points is not so useful, rather, we want the *end* of code points.
+      uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+      // We process in blocks of up to 12 bytes except possibly
+      // for fast paths which may process up to 16 bytes. For the
+      // slow path to work, we should have at least 12 input bytes left.
+      size_t max_starting_point = (pos + 64) - 12;
+      // Next loop is going to run at least five times when using solely
+      // the slow/regular path, and at least four times if there are fast paths.
+      while(pos < max_starting_point) {
+        // Performance note: our ability to compute 'consumed' and
+        // then shift and recompute is critical. If there is a
+        // latency of, say, 4 cycles on getting 'consumed', then
+        // the inner loop might have a total latency of about 6 cycles.
+        // Yet we process between 6 to 12 inputs bytes, thus we get
+        // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+        // for this section of the code. Hence, there is a limit
+        // to how much we can further increase this latency before
+        // it seriously harms performance.
+        //
+        // Thus we may allow convert_masked_utf8_to_utf16 to process
+        // more bytes at a time under a fast-path mode where 16 bytes
+        // are consumed at once (e.g., when encountering ASCII).
+        size_t consumed = convert_masked_utf8_to_utf16<endian>(input + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+        pos += consumed;
+        utf8_end_of_code_point_mask >>= consumed;
+      }
+      // At this point there may remain between 0 and 12 bytes in the
+      // 64-byte block.These bytes will be processed again. So we have an
+      // 80% efficiency (in the worst case). In practice we expect an
+      // 85% to 90% efficiency.
+    }
+  }
+  utf16_output += scalar::utf8_to_utf16::convert_valid<endian>(input + pos, size - pos, utf16_output);
+  return utf16_output - start;
+}
+
+} // namespace utf8_to_utf16
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf16/valid_utf8_to_utf16.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf16/utf8_to_utf16.h
+/* begin file src/generic/utf8_to_utf16/utf8_to_utf16.h */
+
+
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace utf8_to_utf16 {
+using namespace simd;
+
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+
+  struct validating_transcoder {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+
+    validating_transcoder() : error(uint8_t(0)) {}
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+
+    template <endianness endian>
+    simdutf_really_inline size_t convert(const char* in, size_t size, char16_t* utf16_output) {
+      size_t pos = 0;
+      char16_t* start{utf16_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf16<endian>(utf16_output);
+          utf16_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf16<endian>(in + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) { return 0; }
+      if(pos < size) {
+        size_t howmany  = scalar::utf8_to_utf16::convert<endian>(in + pos, size - pos, utf16_output);
+        if(howmany == 0) { return 0; }
+        utf16_output += howmany;
+      }
+      return utf16_output - start;
+    }
+
+    template <endianness endian>
+    simdutf_really_inline result convert_with_errors(const char* in, size_t size, char16_t* utf16_output) {
+      size_t pos = 0;
+      char16_t* start{utf16_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf16<endian>(utf16_output);
+          utf16_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          if (errors()) {
+            result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+            res.count += pos;
+            return res;
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf16<endian>(in + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) {
+        result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+        res.count += pos;
+        return res;
+      }
+      if(pos < size) {
+        result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+        if (res.error) {    // In case of error, we want the error position
+          res.count += pos;
+          return res;
+        } else {    // In case of success, we want the number of word written
+          utf16_output += res.count;
+        }
+      }
+      return result(error_code::SUCCESS, utf16_output - start);
+    }
+
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // utf8_to_utf16 namespace
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf16/utf8_to_utf16.h */
+// transcoding from UTF-8 to UTF-32
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf32/valid_utf8_to_utf32.h
+/* begin file src/generic/utf8_to_utf32/valid_utf8_to_utf32.h */
+
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace utf8_to_utf32 {
+
+using namespace simd;
+
+
+simdutf_warn_unused size_t convert_valid(const char* input, size_t size,
+    char32_t* utf32_output) noexcept {
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  const size_t safety_margin = 16; // to avoid overruns!
+  while(pos + 64 + safety_margin <= size) {
+    simd8x64<int8_t> in(reinterpret_cast<const int8_t *>(input + pos));
+    if(in.is_ascii()) {
+      in.store_ascii_as_utf32(utf32_output);
+      utf32_output += 64;
+      pos += 64;
+    } else {
+    // -65 is 0b10111111 in two-complement's, so largest possible continuation byte
+    uint64_t utf8_continuation_mask = in.lt(-65 + 1);
+    uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+    uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+    size_t max_starting_point = (pos + 64) - 12;
+    while(pos < max_starting_point) {
+      size_t consumed = convert_masked_utf8_to_utf32(input + pos,
+                          utf8_end_of_code_point_mask, utf32_output);
+      pos += consumed;
+      utf8_end_of_code_point_mask >>= consumed;
+      }
+    }
+  }
+  utf32_output += scalar::utf8_to_utf32::convert_valid(input + pos, size - pos, utf32_output);
+  return utf32_output - start;
+}
+
+
+} // namespace utf8_to_utf32
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf32/valid_utf8_to_utf32.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf32/utf8_to_utf32.h
+/* begin file src/generic/utf8_to_utf32/utf8_to_utf32.h */
+
+
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace utf8_to_utf32 {
+using namespace simd;
+
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+
+  struct validating_transcoder {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+
+    validating_transcoder() : error(uint8_t(0)) {}
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+
+
+    simdutf_really_inline size_t convert(const char* in, size_t size, char32_t* utf32_output) {
+      size_t pos = 0;
+      char32_t* start{utf32_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf32(utf32_output);
+          utf32_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf32(in + pos,
+                            utf8_end_of_code_point_mask, utf32_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) { return 0; }
+      if(pos < size) {
+        size_t howmany  = scalar::utf8_to_utf32::convert(in + pos, size - pos, utf32_output);
+        if(howmany == 0) { return 0; }
+        utf32_output += howmany;
+      }
+      return utf32_output - start;
+    }
+
+    simdutf_really_inline result convert_with_errors(const char* in, size_t size, char32_t* utf32_output) {
+      size_t pos = 0;
+      char32_t* start{utf32_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf32(utf32_output);
+          utf32_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          if (errors()) {
+            result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+            res.count += pos;
+            return res;
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf32(in + pos,
+                            utf8_end_of_code_point_mask, utf32_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) {
+        result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+        res.count += pos;
+        return res;
+      }
+      if(pos < size) {
+        result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+        if (res.error) {    // In case of error, we want the error position
+          res.count += pos;
+          return res;
+        } else {    // In case of success, we want the number of word written
+          utf32_output += res.count;
+        }
+      }
+      return result(error_code::SUCCESS, utf32_output - start);
+    }
+
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // utf8_to_utf32 namespace
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf32/utf8_to_utf32.h */
+// other functions
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8.h
+/* begin file src/generic/utf8.h */
+
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace utf8 {
+
+using namespace simd;
+
+simdutf_really_inline size_t count_code_points(const char* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    for(;pos + 64 <= size; pos += 64) {
+      simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+      uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+      count += 64 - count_ones(utf8_continuation_mask);
+    }
+    return count + scalar::utf8::count_code_points(in + pos, size - pos);
+}
+
+
+simdutf_really_inline size_t utf16_length_from_utf8(const char* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 64 <= size; pos += 64) {
+      simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+      uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+      // We count one word for anything that is not a continuation (so
+      // leading bytes).
+      count += 64 - count_ones(utf8_continuation_mask);
+      int64_t utf8_4byte = input.gteq_unsigned(240);
+      count += count_ones(utf8_4byte);
+    }
+    return count + scalar::utf8::utf16_length_from_utf8(in + pos, size - pos);
+}
+
+
+simdutf_really_inline size_t utf32_length_from_utf8(const char* in, size_t size) {
+    return count_code_points(in, size);
+}
+} // utf8 namespace
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/utf8.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf16.h
+/* begin file src/generic/utf16.h */
+namespace simdutf {
+namespace ppc64 {
+namespace {
+namespace utf16 {
+
+template <endianness big_endian>
+simdutf_really_inline size_t count_code_points(const char16_t* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    for(;pos + 32 <= size; pos += 32) {
+      simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+      if (big_endian) input.swap_bytes();
+      uint64_t not_pair = input.not_in_range(0xDC00, 0xDFFF);
+      count += count_ones(not_pair) / 2;
+    }
+    return count + scalar::utf16::count_code_points<big_endian>(in + pos, size - pos);
+}
+
+template <endianness big_endian>
+simdutf_really_inline size_t utf8_length_from_utf16(const char16_t* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 32 <= size; pos += 32) {
+      simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+      if (big_endian) input.swap_bytes();
+      uint64_t ascii_mask = input.lteq(0x7F);
+      uint64_t twobyte_mask = input.lteq(0x7FF);
+      uint64_t not_pair_mask = input.not_in_range(0xD800, 0xDFFF);
+
+      size_t ascii_count = count_ones(ascii_mask) / 2;
+      size_t twobyte_count = count_ones(twobyte_mask & ~ ascii_mask) / 2;
+      size_t threebyte_count = count_ones(not_pair_mask & ~ twobyte_mask) / 2;
+      size_t fourbyte_count = 32 - count_ones(not_pair_mask) / 2;
+      count += 2 * fourbyte_count + 3 * threebyte_count + 2 * twobyte_count + ascii_count;
+    }
+    return count + scalar::utf16::utf8_length_from_utf16<big_endian>(in + pos, size - pos);
+}
+
+template <endianness big_endian>
+simdutf_really_inline size_t utf32_length_from_utf16(const char16_t* in, size_t size) {
+    return count_code_points<big_endian>(in, size);
+}
+
+simdutf_really_inline void change_endianness_utf16(const char16_t* in, size_t size, char16_t* output) {
+  size_t pos = 0;
+
+  while (pos + 32 <= size) {
+    simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+    input.swap_bytes();
+    input.store(reinterpret_cast<uint16_t *>(output));
+    pos += 32;
+    output += 32;
+  }
+
+  scalar::utf16::change_endianness_utf16(in + pos, size - pos, output);
+}
+
+} // utf16
+} // unnamed namespace
+} // namespace ppc64
+} // namespace simdutf
+/* end file src/generic/utf16.h */
+
+//
+// Implementation-specific overrides
+//
+namespace simdutf {
+namespace ppc64 {
+
+simdutf_warn_unused int implementation::detect_encodings(const char * input, size_t length) const noexcept {
+  // If there is a BOM, then we trust it.
+  auto bom_encoding = simdutf::BOM::check_bom(input, length);
+  if(bom_encoding != encoding_type::unspecified) { return bom_encoding; }
+  int out = 0;
+  if(validate_utf8(input, length)) { out |= encoding_type::UTF8; }
+  if((length % 2) == 0) {
+    if(validate_utf16(reinterpret_cast<const char16_t*>(input), length/2)) { out |= encoding_type::UTF16_LE; }
+  }
+  if((length % 4) == 0) {
+    if(validate_utf32(reinterpret_cast<const char32_t*>(input), length/4)) { out |= encoding_type::UTF32_LE; }
+  }
+
+  return out;
+}
+
+simdutf_warn_unused bool implementation::validate_utf8(const char *buf, size_t len) const noexcept {
+  return ppc64::utf8_validation::generic_validate_utf8(buf,len);
+}
+
+simdutf_warn_unused result implementation::validate_utf8_with_errors(const char *buf, size_t len) const noexcept {
+  return ppc64::utf8_validation::generic_validate_utf8_with_errors(buf,len);
+}
+
+simdutf_warn_unused bool implementation::validate_ascii(const char *buf, size_t len) const noexcept {
+  return ppc64::utf8_validation::generic_validate_ascii(buf,len);
+}
+
+simdutf_warn_unused result implementation::validate_ascii_with_errors(const char *buf, size_t len) const noexcept {
+  return ppc64::utf8_validation::generic_validate_ascii_with_errors(buf,len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf16le(const char16_t *buf, size_t len) const noexcept {
+  return scalar::utf16::validate<endianness::LITTLE>(buf, len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf16be(const char16_t *buf, size_t len) const noexcept {
+  return scalar::utf16::validate<endianness::BIG>(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept {
+  return scalar::utf16::validate_with_errors<endianness::LITTLE>(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept {
+  return scalar::utf16::validate_with_errors<endianness::BIG>(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept {
+  return scalar::utf32::validate_with_errors(buf, len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf32(const char16_t *buf, size_t len) const noexcept {
+  return scalar::utf32::validate(buf, len);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16le(const char* /*buf*/, size_t /*len*/, char16_t* /*utf16_output*/) const noexcept {
+  return 0; // stub
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16be(const char* /*buf*/, size_t /*len*/, char16_t* /*utf16_output*/) const noexcept {
+  return 0; // stub
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16le_with_errors(const char* /*buf*/, size_t /*len*/, char16_t* /*utf16_output*/) const noexcept {
+  return result(error_code::OTHER, 0); // stub
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16be_with_errors(const char* /*buf*/, size_t /*len*/, char16_t* /*utf16_output*/) const noexcept {
+  return result(error_code::OTHER, 0); // stub
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16le(const char* /*buf*/, size_t /*len*/, char16_t* /*utf16_output*/) const noexcept {
+  return 0; // stub
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16be(const char* /*buf*/, size_t /*len*/, char16_t* /*utf16_output*/) const noexcept {
+  return 0; // stub
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf32(const char* /*buf*/, size_t /*len*/, char32_t* /*utf16_output*/) const noexcept {
+  return 0; // stub
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf32_with_errors(const char* /*buf*/, size_t /*len*/, char32_t* /*utf16_output*/) const noexcept {
+  return result(error_code::OTHER, 0); // stub
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf32(const char* /*buf*/, size_t /*len*/, char32_t* /*utf16_output*/) const noexcept {
+  return 0; // stub
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert<endianness::LITTLE>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert<endianness::BIG>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert_with_errors<endianness::LITTLE>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert_with_errors<endianness::BIG>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert_valid<endianness::LITTLE>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf16_to_utf8::convert_valid<endianness::BIG>(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf32_to_utf8::convert(buf, len, utf8_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf32_to_utf8::convert_with_errors(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return scalar::utf32_to_utf8::convert_valid(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16le_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16be_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert_with_errors<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert_valid<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return scalar::utf32_to_utf16::convert_valid<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert<endianness::LITTLE>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert<endianness::BIG>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert_with_errors<endianness::LITTLE>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert_with_errors<endianness::BIG>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert_valid<endianness::LITTLE>(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return scalar::utf16_to_utf32::convert_valid<endianness::BIG>(buf, len, utf32_output);
+}
+
+void implementation::change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) const noexcept {
+  scalar::utf16::change_endianness_utf16(input, length, output);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16le(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::count_code_points<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16be(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::count_code_points<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf8(const char * input, size_t length) const noexcept {
+  return utf8::count_code_points(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::utf8_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::utf8_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::utf32_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return scalar::utf16::utf32_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf8(const char * input, size_t length) const noexcept {
+  return scalar::utf8::utf16_length_from_utf8(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  return scalar::utf32::utf8_length_from_utf32(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  return scalar::utf32::utf16_length_from_utf32(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf8(const char * input, size_t length) const noexcept {
+  return scalar::utf8::utf32_length_from_utf8(input, length);
+}
+
+} // namespace ppc64
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/ppc64/end.h
+/* begin file src/simdutf/ppc64/end.h */
+/* end file src/simdutf/ppc64/end.h */
+/* end file src/ppc64/implementation.cpp */
+#endif
+#if SIMDUTF_IMPLEMENTATION_WESTMERE
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/implementation.cpp
+/* begin file src/westmere/implementation.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/begin.h
+/* begin file src/simdutf/westmere/begin.h */
+// redefining SIMDUTF_IMPLEMENTATION to "westmere"
+// #define SIMDUTF_IMPLEMENTATION westmere
+SIMDUTF_TARGET_WESTMERE
+/* end file src/simdutf/westmere/begin.h */
+namespace simdutf {
+namespace westmere {
+namespace {
+#ifndef SIMDUTF_WESTMERE_H
+#error "westmere.h must be included"
+#endif
+using namespace simd;
+
+simdutf_really_inline bool is_ascii(const simd8x64<uint8_t>& input) {
+  return input.reduce_or().is_ascii();
+}
+
+simdutf_unused simdutf_really_inline simd8<bool> must_be_continuation(const simd8<uint8_t> prev1, const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
+  simd8<uint8_t> is_second_byte = prev1.saturating_sub(0b11000000u-1); // Only 11______ will be > 0
+  simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0b11100000u-1); // Only 111_____ will be > 0
+  simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0b11110000u-1); // Only 1111____ will be > 0
+  // Caller requires a bool (all 1's). All values resulting from the subtraction will be <= 64, so signed comparison is fine.
+  return simd8<int8_t>(is_second_byte | is_third_byte | is_fourth_byte) > int8_t(0);
+}
+
+simdutf_really_inline simd8<bool> must_be_2_3_continuation(const simd8<uint8_t> prev2, const simd8<uint8_t> prev3) {
+  simd8<uint8_t> is_third_byte  = prev2.saturating_sub(0b11100000u-1); // Only 111_____ will be > 0
+  simd8<uint8_t> is_fourth_byte = prev3.saturating_sub(0b11110000u-1); // Only 1111____ will be > 0
+  // Caller requires a bool (all 1's). All values resulting from the subtraction will be <= 64, so signed comparison is fine.
+  return simd8<int8_t>(is_third_byte | is_fourth_byte) > int8_t(0);
+}
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_detect_encodings.cpp
+/* begin file src/westmere/sse_detect_encodings.cpp */
+template<class checker>
+// len is known to be a multiple of 2 when this is called
+int sse_detect_encodings(const char * buf, size_t len) {
+    const char* start = buf;
+    const char* end = buf + len;
+
+    bool is_utf8 = true;
+    bool is_utf16 = true;
+    bool is_utf32 = true;
+
+    int out = 0;
+
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+
+    __m128i currentmax = _mm_setzero_si128();
+
+    checker check{};
+
+    while(buf + 64 <= end) {
+        __m128i in = _mm_loadu_si128((__m128i*)buf);
+        __m128i secondin = _mm_loadu_si128((__m128i*)buf+1);
+        __m128i thirdin = _mm_loadu_si128((__m128i*)buf+2);
+        __m128i fourthin = _mm_loadu_si128((__m128i*)buf+3);
+
+        const auto u0 = simd16<uint16_t>(in);
+        const auto u1 = simd16<uint16_t>(secondin);
+        const auto u2 = simd16<uint16_t>(thirdin);
+        const auto u3 = simd16<uint16_t>(fourthin);
+
+        const auto v0 = u0.shr<8>();
+        const auto v1 = u1.shr<8>();
+        const auto v2 = u2.shr<8>();
+        const auto v3 = u3.shr<8>();
+
+        const auto in16 = simd16<uint16_t>::pack(v0, v1);
+        const auto nextin16 = simd16<uint16_t>::pack(v2, v3);
+
+        const auto surrogates_wordmask0 = (in16 & v_f8) == v_d8;
+        const auto surrogates_wordmask1 = (nextin16 & v_f8) == v_d8;
+        uint16_t surrogates_bitmask0 = static_cast<uint16_t>(surrogates_wordmask0.to_bitmask());
+        uint16_t surrogates_bitmask1 = static_cast<uint16_t>(surrogates_wordmask1.to_bitmask());
+
+        // Check for surrogates
+        if (surrogates_bitmask0 != 0x0 || surrogates_bitmask1 != 0x0) {
+            // Cannot be UTF8
+            is_utf8 = false;
+            // Can still be either UTF-16LE or UTF-32LE depending on the positions of the surrogates
+            // To be valid UTF-32LE, a surrogate cannot be in the two most significant bytes of any 32-bit word.
+            // On the other hand, to be valid UTF-16LE, at least one surrogate must be in the two most significant
+            // bytes of a 32-bit word since they always come in pairs in UTF-16LE.
+            // Note that we always proceed in multiple of 4 before this point so there is no offset in 32-bit words.
+
+            if (((surrogates_bitmask0 | surrogates_bitmask1) & 0xaaaa) != 0) {
+                is_utf32 = false;
+                // Code from sse_validate_utf16le.cpp
+                // Not efficient, we do not process surrogates_bitmask1
+                const char16_t * input = reinterpret_cast<const char16_t*>(buf);
+                const char16_t* end16 = reinterpret_cast<const char16_t*>(start) + len/2;
+
+                const auto v_fc = simd8<uint8_t>::splat(0xfc);
+                const auto v_dc = simd8<uint8_t>::splat(0xdc);
+
+                const uint16_t V0 = static_cast<uint16_t>(~surrogates_bitmask0);
+
+                const auto    vH0 = (in16 & v_fc) == v_dc;
+                const uint16_t H0 = static_cast<uint16_t>(vH0.to_bitmask());
+
+                const uint16_t L0 = static_cast<uint16_t>(~H0 & surrogates_bitmask0);
+
+                const uint16_t a0 = static_cast<uint16_t>(L0 & (H0 >> 1));
+
+                const uint16_t b0 = static_cast<uint16_t>(a0 << 1);
+
+                const uint16_t c0 = static_cast<uint16_t>(V0 | a0 | b0);
+
+                if (c0 == 0xffff) {
+                    input += 16;
+                } else if (c0 == 0x7fff) {
+                    input += 15;
+                } else {
+                    is_utf16 = false;
+                    break;
+                }
+
+                while (input + simd16<uint16_t>::SIZE * 2 < end16) {
+                    const auto in0 = simd16<uint16_t>(input);
+                    const auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::SIZE / sizeof(char16_t));
+
+                    const auto t0 = in0.shr<8>();
+                    const auto t1 = in1.shr<8>();
+
+                    const auto in_16 = simd16<uint16_t>::pack(t0, t1);
+
+                    const auto surrogates_wordmask = (in_16 & v_f8) == v_d8;
+                    const uint16_t surrogates_bitmask = static_cast<uint16_t>(surrogates_wordmask.to_bitmask());
+                    if (surrogates_bitmask == 0x0) {
+                        input += 16;
+                    } else {
+                        const uint16_t V = static_cast<uint16_t>(~surrogates_bitmask);
+
+                        const auto    vH = (in_16 & v_fc) == v_dc;
+                        const uint16_t H = static_cast<uint16_t>(vH.to_bitmask());
+
+                        const uint16_t L = static_cast<uint16_t>(~H & surrogates_bitmask);
+
+                        const uint16_t a = static_cast<uint16_t>(L & (H >> 1));
+
+                        const uint16_t b = static_cast<uint16_t>(a << 1);
+
+                        const uint16_t c = static_cast<uint16_t>(V | a | b);
+
+                        if (c == 0xffff) {
+                            input += 16;
+                        } else if (c == 0x7fff) {
+                            input += 15;
+                        } else {
+                            is_utf16 = false;
+                            break;
+                        }
+                    }
+                }
+            } else {
+                is_utf16 = false;
+                // Check for UTF-32LE
+                if (len % 4 == 0) {
+                    const char32_t * input = reinterpret_cast<const char32_t*>(buf);
+                    const char32_t* end32 = reinterpret_cast<const char32_t*>(start) + len/4;
+
+                    // Must start checking for surrogates
+                    __m128i currentoffsetmax = _mm_setzero_si128();
+                    const __m128i offset = _mm_set1_epi32(0xffff2000);
+                    const __m128i standardoffsetmax = _mm_set1_epi32(0xfffff7ff);
+
+                    currentmax = _mm_max_epu32(in, currentmax);
+                    currentmax = _mm_max_epu32(secondin, currentmax);
+                    currentmax = _mm_max_epu32(thirdin, currentmax);
+                    currentmax = _mm_max_epu32(fourthin, currentmax);
+
+                    currentoffsetmax = _mm_max_epu32(_mm_add_epi32(in, offset), currentoffsetmax);
+                    currentoffsetmax = _mm_max_epu32(_mm_add_epi32(secondin, offset), currentoffsetmax);
+                    currentoffsetmax = _mm_max_epu32(_mm_add_epi32(thirdin, offset), currentoffsetmax);
+                    currentoffsetmax = _mm_max_epu32(_mm_add_epi32(fourthin, offset), currentoffsetmax);
+
+                    while (input + 4 < end32) {
+                        const __m128i in32 = _mm_loadu_si128((__m128i *)input);
+                        currentmax = _mm_max_epu32(in32,currentmax);
+                        currentoffsetmax = _mm_max_epu32(_mm_add_epi32(in32, offset), currentoffsetmax);
+                        input += 4;
+                    }
+
+                    __m128i forbidden_words = _mm_xor_si128(_mm_max_epu32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+                    if(_mm_testz_si128(forbidden_words, forbidden_words) == 0) {
+                        is_utf32 = false;
+                    }
+                } else {
+                    is_utf32 = false;
+                }
+            }
+            break;
+        }
+        // If no surrogate, validate under other encodings as well
+
+        // UTF-32LE validation
+        currentmax = _mm_max_epu32(in, currentmax);
+        currentmax = _mm_max_epu32(secondin, currentmax);
+        currentmax = _mm_max_epu32(thirdin, currentmax);
+        currentmax = _mm_max_epu32(fourthin, currentmax);
+
+        // UTF-8 validation
+        // Relies on ../generic/utf8_validation/utf8_lookup4_algorithm.h
+        simd::simd8x64<uint8_t> in8(in, secondin, thirdin, fourthin);
+        check.check_next_input(in8);
+
+        buf += 64;
+    }
+
+    // Check which encodings are possible
+
+    if (is_utf8) {
+        if (static_cast<size_t>(buf - start) != len) {
+            uint8_t block[64]{};
+            std::memset(block, 0x20, 64);
+            std::memcpy(block, buf, len - (buf - start));
+            simd::simd8x64<uint8_t> in(block);
+            check.check_next_input(in);
+        }
+        if (!check.errors()) {
+            out |= simdutf::encoding_type::UTF8;
+        }
+    }
+
+    if (is_utf16 && scalar::utf16::validate<endianness::LITTLE>(reinterpret_cast<const char16_t*>(buf), (len - (buf - start))/2)) {
+        out |= simdutf::encoding_type::UTF16_LE;
+    }
+
+    if (is_utf32 && (len % 4 == 0)) {
+        const __m128i standardmax = _mm_set1_epi32(0x10ffff);
+        __m128i is_zero = _mm_xor_si128(_mm_max_epu32(currentmax, standardmax), standardmax);
+        if (_mm_testz_si128(is_zero, is_zero) == 1 && scalar::utf32::validate(reinterpret_cast<const char32_t*>(buf), (len - (buf - start))/4)) {
+            out |= simdutf::encoding_type::UTF32_LE;
+        }
+    }
+
+    return out;
+}
+/* end file src/westmere/sse_detect_encodings.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_validate_utf16.cpp
+/* begin file src/westmere/sse_validate_utf16.cpp */
+/*
+    In UTF-16 words in range 0xD800 to 0xDFFF have special meaning.
+
+    In a vectorized algorithm we want to examine the most significant
+    nibble in order to select a fast path. If none of highest nibbles
+    are 0xD (13), than we are sure that UTF-16 chunk in a vector
+    register is valid.
+
+    Let us analyze what we need to check if the nibble is 0xD. The
+    value of the preceding nibble determines what we have:
+
+    0xd000 .. 0xd7ff - a valid word
+    0xd800 .. 0xdbff - low surrogate
+    0xdc00 .. 0xdfff - high surrogate
+
+    Other constraints we have to consider:
+    - there must not be two consecutive low surrogates (0xd800 .. 0xdbff)
+    - there must not be two consecutive high surrogates (0xdc00 .. 0xdfff)
+    - there must not be sole low surrogate nor high surrogate
+
+    We're going to build three bitmasks based on the 3rd nibble:
+    - V = valid word,
+    - L = low surrogate (0xd800 .. 0xdbff)
+    - H = high surrogate (0xdc00 .. 0xdfff)
+
+      0   1   2   3   4   5   6   7    <--- word index
+    [ V | L | H | L | H | V | V | L ]
+      1   0   0   0   0   1   1   0     - V = valid masks
+      0   1   0   1   0   0   0   1     - L = low surrogate
+      0   0   1   0   1   0   0   0     - H high surrogate
+
+
+      1   0   0   0   0   1   1   0   V = valid masks
+      0   1   0   1   0   0   0   0   a = L & (H >> 1)
+      0   0   1   0   1   0   0   0   b = a << 1
+      1   1   1   1   1   1   1   0   c = V | a | b
+                                  ^
+                                  the last bit can be zero, we just consume 7 words
+                                  and recheck this word in the next iteration
+*/
+
+/* Returns:
+   - pointer to the last unprocessed character (a scalar fallback should check the rest);
+   - nullptr if an error was detected.
+*/
+template <endianness big_endian>
+const char16_t* sse_validate_utf16(const char16_t* input, size_t size) {
+    const char16_t* end = input + size;
+
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+    const auto v_fc = simd8<uint8_t>::splat(0xfc);
+    const auto v_dc = simd8<uint8_t>::splat(0xdc);
+
+    while (input + simd16<uint16_t>::SIZE * 2 < end) {
+        // 0. Load data: since the validation takes into account only higher
+        //    byte of each word, we compress the two vectors into one which
+        //    consists only the higher bytes.
+        auto in0 = simd16<uint16_t>(input);
+        auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::SIZE / sizeof(char16_t));
+        if (big_endian) {
+            in0 = in0.swap_bytes();
+            in1 = in1.swap_bytes();
+        }
+
+        const auto t0 = in0.shr<8>();
+        const auto t1 = in1.shr<8>();
+
+        const auto in = simd16<uint16_t>::pack(t0, t1);
+
+        // 1. Check whether we have any 0xD800..DFFF word (0b1101'1xxx'yyyy'yyyy).
+        const auto surrogates_wordmask = (in & v_f8) == v_d8;
+        const uint16_t surrogates_bitmask = static_cast<uint16_t>(surrogates_wordmask.to_bitmask());
+        if (surrogates_bitmask == 0x0000) {
+            input += 16;
+        } else {
+            // 2. We have some surrogates that have to be distinguished:
+            //    - low  surrogates: 0b1101'10xx'yyyy'yyyy (0xD800..0xDBFF)
+            //    - high surrogates: 0b1101'11xx'yyyy'yyyy (0xDC00..0xDFFF)
+            //
+            //    Fact: high surrogate has 11th bit set (3rd bit in the higher word)
+
+            // V - non-surrogate words
+            //     V = not surrogates_wordmask
+            const uint16_t V = static_cast<uint16_t>(~surrogates_bitmask);
+
+            // H - word-mask for high surrogates: the six highest bits are 0b1101'11
+            const auto    vH = (in & v_fc) == v_dc;
+            const uint16_t H = static_cast<uint16_t>(vH.to_bitmask());
+
+            // L - word mask for low surrogates
+            //     L = not H and surrogates_wordmask
+            const uint16_t L = static_cast<uint16_t>(~H & surrogates_bitmask);
+
+            const uint16_t a = static_cast<uint16_t>(L & (H >> 1));  // A low surrogate must be followed by high one.
+                                              // (A low surrogate placed in the 7th register's word
+                                              // is an exception we handle.)
+            const uint16_t b = static_cast<uint16_t>(a << 1);        // Just mark that the opinput - startite fact is hold,
+                                              // thanks to that we have only two masks for valid case.
+            const uint16_t c = static_cast<uint16_t>(V | a | b);     // Combine all the masks into the final one.
+
+            if (c == 0xffff) {
+                // The whole input register contains valid UTF-16, i.e.,
+                // either single words or proper surrogate pairs.
+                input += 16;
+            } else if (c == 0x7fff) {
+                // The 15 lower words of the input register contains valid UTF-16.
+                // The 15th word may be either a low or high surrogate. It the next
+                // iteration we 1) check if the low surrogate is followed by a high
+                // one, 2) reject sole high surrogate.
+                input += 15;
+            } else {
+                return nullptr;
+            }
+        }
+    }
+
+    return input;
+}
+
+
+template <endianness big_endian>
+const result sse_validate_utf16_with_errors(const char16_t* input, size_t size) {
+    const char16_t* start = input;
+    const char16_t* end = input + size;
+
+    const auto v_d8 = simd8<uint8_t>::splat(0xd8);
+    const auto v_f8 = simd8<uint8_t>::splat(0xf8);
+    const auto v_fc = simd8<uint8_t>::splat(0xfc);
+    const auto v_dc = simd8<uint8_t>::splat(0xdc);
+
+    while (input + simd16<uint16_t>::SIZE * 2 < end) {
+        // 0. Load data: since the validation takes into account only higher
+        //    byte of each word, we compress the two vectors into one which
+        //    consists only the higher bytes.
+        auto in0 = simd16<uint16_t>(input);
+        auto in1 = simd16<uint16_t>(input + simd16<uint16_t>::SIZE / sizeof(char16_t));
+
+        if (big_endian) {
+            in0 = in0.swap_bytes();
+            in1 = in1.swap_bytes();
+        }
+
+        const auto t0 = in0.shr<8>();
+        const auto t1 = in1.shr<8>();
+
+        const auto in = simd16<uint16_t>::pack(t0, t1);
+
+        // 1. Check whether we have any 0xD800..DFFF word (0b1101'1xxx'yyyy'yyyy).
+        const auto surrogates_wordmask = (in & v_f8) == v_d8;
+        const uint16_t surrogates_bitmask = static_cast<uint16_t>(surrogates_wordmask.to_bitmask());
+        if (surrogates_bitmask == 0x0000) {
+            input += 16;
+        } else {
+            // 2. We have some surrogates that have to be distinguished:
+            //    - low  surrogates: 0b1101'10xx'yyyy'yyyy (0xD800..0xDBFF)
+            //    - high surrogates: 0b1101'11xx'yyyy'yyyy (0xDC00..0xDFFF)
+            //
+            //    Fact: high surrogate has 11th bit set (3rd bit in the higher word)
+
+            // V - non-surrogate words
+            //     V = not surrogates_wordmask
+            const uint16_t V = static_cast<uint16_t>(~surrogates_bitmask);
+
+            // H - word-mask for high surrogates: the six highest bits are 0b1101'11
+            const auto    vH = (in & v_fc) == v_dc;
+            const uint16_t H = static_cast<uint16_t>(vH.to_bitmask());
+
+            // L - word mask for low surrogates
+            //     L = not H and surrogates_wordmask
+            const uint16_t L = static_cast<uint16_t>(~H & surrogates_bitmask);
+
+            const uint16_t a = static_cast<uint16_t>(L & (H >> 1));  // A low surrogate must be followed by high one.
+                                              // (A low surrogate placed in the 7th register's word
+                                              // is an exception we handle.)
+            const uint16_t b = static_cast<uint16_t>(a << 1);        // Just mark that the opinput - startite fact is hold,
+                                              // thanks to that we have only two masks for valid case.
+            const uint16_t c = static_cast<uint16_t>(V | a | b);     // Combine all the masks into the final one.
+
+            if (c == 0xffff) {
+                // The whole input register contains valid UTF-16, i.e.,
+                // either single words or proper surrogate pairs.
+                input += 16;
+            } else if (c == 0x7fff) {
+                // The 15 lower words of the input register contains valid UTF-16.
+                // The 15th word may be either a low or high surrogate. It the next
+                // iteration we 1) check if the low surrogate is followed by a high
+                // one, 2) reject sole high surrogate.
+                input += 15;
+            } else {
+                return result(error_code::SURROGATE, input - start);
+            }
+        }
+    }
+
+    return result(error_code::SUCCESS, input - start);
+}
+/* end file src/westmere/sse_validate_utf16.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_validate_utf32le.cpp
+/* begin file src/westmere/sse_validate_utf32le.cpp */
+/* Returns:
+   - pointer to the last unprocessed character (a scalar fallback should check the rest);
+   - nullptr if an error was detected.
+*/
+const char32_t* sse_validate_utf32le(const char32_t* input, size_t size) {
+    const char32_t* end = input + size;
+
+    const __m128i standardmax = _mm_set1_epi32(0x10ffff);
+    const __m128i offset = _mm_set1_epi32(0xffff2000);
+    const __m128i standardoffsetmax = _mm_set1_epi32(0xfffff7ff);
+    __m128i currentmax = _mm_setzero_si128();
+    __m128i currentoffsetmax = _mm_setzero_si128();
+
+    while (input + 4 < end) {
+        const __m128i in = _mm_loadu_si128((__m128i *)input);
+        currentmax = _mm_max_epu32(in,currentmax);
+        currentoffsetmax = _mm_max_epu32(_mm_add_epi32(in, offset), currentoffsetmax);
+        input += 4;
+    }
+    __m128i is_zero = _mm_xor_si128(_mm_max_epu32(currentmax, standardmax), standardmax);
+    if(_mm_test_all_zeros(is_zero, is_zero) == 0) {
+        return nullptr;
+    }
+
+    is_zero = _mm_xor_si128(_mm_max_epu32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+    if(_mm_test_all_zeros(is_zero, is_zero) == 0) {
+        return nullptr;
+    }
+
+    return input;
+}
+
+
+const result sse_validate_utf32le_with_errors(const char32_t* input, size_t size) {
+    const char32_t* start = input;
+    const char32_t* end = input + size;
+
+    const __m128i standardmax = _mm_set1_epi32(0x10ffff);
+    const __m128i offset = _mm_set1_epi32(0xffff2000);
+    const __m128i standardoffsetmax = _mm_set1_epi32(0xfffff7ff);
+    __m128i currentmax = _mm_setzero_si128();
+    __m128i currentoffsetmax = _mm_setzero_si128();
+
+    while (input + 4 < end) {
+        const __m128i in = _mm_loadu_si128((__m128i *)input);
+        currentmax = _mm_max_epu32(in,currentmax);
+        currentoffsetmax = _mm_max_epu32(_mm_add_epi32(in, offset), currentoffsetmax);
+
+        __m128i is_zero = _mm_xor_si128(_mm_max_epu32(currentmax, standardmax), standardmax);
+        if(_mm_test_all_zeros(is_zero, is_zero) == 0) {
+            return result(error_code::TOO_LARGE, input - start);
+        }
+
+        is_zero = _mm_xor_si128(_mm_max_epu32(currentoffsetmax, standardoffsetmax), standardoffsetmax);
+        if(_mm_test_all_zeros(is_zero, is_zero) == 0) {
+            return result(error_code::SURROGATE, input - start);
+        }
+        input += 4;
+    }
+
+    return result(error_code::SUCCESS, input - start);
+}
+/* end file src/westmere/sse_validate_utf32le.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_convert_utf8_to_utf16.cpp
+/* begin file src/westmere/sse_convert_utf8_to_utf16.cpp */
+// depends on "tables/utf8_to_utf16_tables.h"
+
+
+// Convert up to 12 bytes from utf8 to utf16 using a mask indicating the
+// end of the code points. Only the least significant 12 bits of the mask
+// are accessed.
+// It returns how many bytes were consumed (up to 12).
+template <endianness big_endian>
+size_t convert_masked_utf8_to_utf16(const char *input,
+                           uint64_t utf8_end_of_code_point_mask,
+                           char16_t *&utf16_output) {
+  // we use an approach where we try to process up to 12 input bytes.
+  // Why 12 input bytes and not 16? Because we are concerned with the size of
+  // the lookup tables. Also 12 is nicely divisible by two and three.
+  //
+  //
+  // Optimization note: our main path below is load-latency dependent. Thus it is maybe
+  // beneficial to have fast paths that depend on branch prediction but have less latency.
+  // This results in more instructions but, potentially, also higher speeds.
+  //
+  // We first try a few fast paths.
+  const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+  const __m128i in = _mm_loadu_si128((__m128i *)input);
+  const uint16_t input_utf8_end_of_code_point_mask =
+      utf8_end_of_code_point_mask & 0xfff;
+  if(((utf8_end_of_code_point_mask & 0xffff) == 0xffff)) {
+    // We process the data in chunks of 16 bytes.
+    __m128i ascii_first = _mm_cvtepu8_epi16(in);
+    __m128i ascii_second = _mm_cvtepu8_epi16(_mm_srli_si128(in,8));
+    if (big_endian) {
+      ascii_first = _mm_shuffle_epi8(ascii_first, swap);
+      ascii_second = _mm_shuffle_epi8(ascii_second, swap);
+    }
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf16_output), ascii_first);
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf16_output + 8), ascii_second);
+    utf16_output += 16; // We wrote 16 16-bit characters.
+    return 16; // We consumed 16 bytes.
+  }
+  if(((utf8_end_of_code_point_mask & 0xFFFF) == 0xaaaa)) {
+    // We want to take 8 2-byte UTF-8 words and turn them into 8 2-byte UTF-16 words.
+    // There is probably a more efficient sequence, but the following might do.
+    const __m128i sh = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi16(0x7f));
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi16(0x1f00));
+    __m128i composed = _mm_or_si128(ascii, _mm_srli_epi16(highbyte, 2));
+    if (big_endian) composed = _mm_shuffle_epi8(composed, swap);
+    _mm_storeu_si128((__m128i *)utf16_output, composed);
+    utf16_output += 8; // We wrote 16 bytes, 8 code points.
+    return 16;
+  }
+  if(input_utf8_end_of_code_point_mask == 0x924) {
+    // We want to take 4 3-byte UTF-8 words and turn them into 4 2-byte UTF-16 words.
+    // There is probably a more efficient sequence, but the following might do.
+    const __m128i sh = _mm_setr_epi8(2, 1, 0, -1, 5, 4, 3, -1, 8, 7, 6, -1, 11, 10, 9, -1);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii =
+        _mm_and_si128(perm, _mm_set1_epi32(0x7f)); // 7 or 6 bits
+    const __m128i middlebyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x3f00)); // 5 or 6 bits
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    const __m128i highbyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x0f0000)); // 4 bits
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 4);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted), highbyte_shifted);
+    __m128i composed_repacked = _mm_packus_epi32(composed, composed);
+    if (big_endian) composed_repacked = _mm_shuffle_epi8(composed_repacked, swap);
+    _mm_storeu_si128((__m128i *)utf16_output, composed_repacked);
+    utf16_output += 4;
+    return 12;
+  }
+  /// We do not have a fast path available, so we fallback.
+
+  const uint8_t idx =
+      tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][0];
+  const uint8_t consumed =
+      tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][1];
+  if (idx < 64) {
+    // SIX (6) input code-words
+    // this is a relatively easy scenario
+    // we process SIX (6) input code-words. The max length in bytes of six code
+    // words spanning between 1 and 2 bytes each is 12 bytes. On processors
+    // where pdep/pext is fast, we might be able to use a small lookup table.
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi16(0x7f));
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi16(0x1f00));
+    __m128i composed = _mm_or_si128(ascii, _mm_srli_epi16(highbyte, 2));
+    if (big_endian) composed = _mm_shuffle_epi8(composed, swap);
+    _mm_storeu_si128((__m128i *)utf16_output, composed);
+    utf16_output += 6; // We wrote 12 bytes, 6 code points.
+  } else if (idx < 145) {
+    // FOUR (4) input code-words
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii =
+        _mm_and_si128(perm, _mm_set1_epi32(0x7f)); // 7 or 6 bits
+    const __m128i middlebyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x3f00)); // 5 or 6 bits
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    const __m128i highbyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x0f0000)); // 4 bits
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 4);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted), highbyte_shifted);
+     __m128i composed_repacked = _mm_packus_epi32(composed, composed);
+    if (big_endian) composed_repacked = _mm_shuffle_epi8(composed_repacked, swap);
+    _mm_storeu_si128((__m128i *)utf16_output, composed_repacked);
+    utf16_output += 4;
+  } else if (idx < 209) {
+    // TWO (2) input code-words
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi32(0x7f));
+    const __m128i middlebyte = _mm_and_si128(perm, _mm_set1_epi32(0x3f00));
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    __m128i middlehighbyte = _mm_and_si128(perm, _mm_set1_epi32(0x3f0000));
+    // correct for spurious high bit
+    const __m128i correct =
+        _mm_srli_epi32(_mm_and_si128(perm, _mm_set1_epi32(0x400000)), 1);
+    middlehighbyte = _mm_xor_si128(correct, middlehighbyte);
+    const __m128i middlehighbyte_shifted = _mm_srli_epi32(middlehighbyte, 4);
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi32(0x07000000));
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 6);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted),
+                     _mm_or_si128(highbyte_shifted, middlehighbyte_shifted));
+    const __m128i composedminus =
+        _mm_sub_epi32(composed, _mm_set1_epi32(0x10000));
+    const __m128i lowtenbits =
+        _mm_and_si128(composedminus, _mm_set1_epi32(0x3ff));
+    const __m128i hightenbits = _mm_srli_epi32(composedminus, 10);
+    const __m128i lowtenbitsadd =
+        _mm_add_epi32(lowtenbits, _mm_set1_epi32(0xDC00));
+    const __m128i hightenbitsadd =
+        _mm_add_epi32(hightenbits, _mm_set1_epi32(0xD800));
+    const __m128i lowtenbitsaddshifted = _mm_slli_epi32(lowtenbitsadd, 16);
+    __m128i surrogates =
+        _mm_or_si128(hightenbitsadd, lowtenbitsaddshifted);
+    uint32_t basic_buffer[4];
+    uint32_t basic_buffer_swap[4];
+    if (big_endian) {
+      _mm_storeu_si128((__m128i *)basic_buffer_swap, _mm_shuffle_epi8(composed, swap));
+      surrogates = _mm_shuffle_epi8(surrogates, swap);
+    }
+    _mm_storeu_si128((__m128i *)basic_buffer, composed);
+    uint32_t surrogate_buffer[4];
+    _mm_storeu_si128((__m128i *)surrogate_buffer, surrogates);
+    for (size_t i = 0; i < 3; i++) {
+      if (basic_buffer[i] < 65536) {
+        utf16_output[0] = big_endian ? uint16_t(basic_buffer_swap[i]) : uint16_t(basic_buffer[i]);
+        utf16_output++;
+      } else {
+        utf16_output[0] = uint16_t(surrogate_buffer[i] & 0xffff);
+        utf16_output[1] = uint16_t(surrogate_buffer[i] >> 16);
+        utf16_output += 2;
+      }
+    }
+  } else {
+    // here we know that there is an error but we do not handle errors
+  }
+  return consumed;
+}
+/* end file src/westmere/sse_convert_utf8_to_utf16.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_convert_utf8_to_utf32.cpp
+/* begin file src/westmere/sse_convert_utf8_to_utf32.cpp */
+// depends on "tables/utf8_to_utf16_tables.h"
+
+
+// Convert up to 12 bytes from utf8 to utf32 using a mask indicating the
+// end of the code points. Only the least significant 12 bits of the mask
+// are accessed.
+// It returns how many bytes were consumed (up to 12).
+size_t convert_masked_utf8_to_utf32(const char *input,
+                           uint64_t utf8_end_of_code_point_mask,
+                           char32_t *&utf32_output) {
+  // we use an approach where we try to process up to 12 input bytes.
+  // Why 12 input bytes and not 16? Because we are concerned with the size of
+  // the lookup tables. Also 12 is nicely divisible by two and three.
+  //
+  //
+  // Optimization note: our main path below is load-latency dependent. Thus it is maybe
+  // beneficial to have fast paths that depend on branch prediction but have less latency.
+  // This results in more instructions but, potentially, also higher speeds.
+  //
+  // We first try a few fast paths.
+  const __m128i in = _mm_loadu_si128((__m128i *)input);
+  const uint16_t input_utf8_end_of_code_point_mask =
+      utf8_end_of_code_point_mask & 0xfff;
+  if(((utf8_end_of_code_point_mask & 0xffff) == 0xffff)) {
+    // We process the data in chunks of 16 bytes.
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output), _mm_cvtepu8_epi32(in));
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output+4), _mm_cvtepu8_epi32(_mm_srli_si128(in,4)));
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output+8), _mm_cvtepu8_epi32(_mm_srli_si128(in,8)));
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output+12), _mm_cvtepu8_epi32(_mm_srli_si128(in,12)));
+    utf32_output += 16; // We wrote 16 32-bit characters.
+    return 16; // We consumed 16 bytes.
+  }
+  if(((utf8_end_of_code_point_mask & 0xffff) == 0xaaaa)) {
+    // We want to take 8 2-byte UTF-8 words and turn them into 8 4-byte UTF-32 words.
+    // There is probably a more efficient sequence, but the following might do.
+    const __m128i sh = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi16(0x7f));
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi16(0x1f00));
+    const __m128i composed = _mm_or_si128(ascii, _mm_srli_epi16(highbyte, 2));
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output), _mm_cvtepu16_epi32(composed));
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output+4), _mm_cvtepu16_epi32(_mm_srli_si128(composed,8)));
+    utf32_output += 8; // We wrote 32 bytes, 8 code points.
+    return 16;
+  }
+  if(input_utf8_end_of_code_point_mask == 0x924) {
+    // We want to take 4 3-byte UTF-8 words and turn them into 4 4-byte UTF-32 words.
+    // There is probably a more efficient sequence, but the following might do.
+    const __m128i sh = _mm_setr_epi8(2, 1, 0, -1, 5, 4, 3, -1, 8, 7, 6, -1, 11, 10, 9, -1);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii =
+        _mm_and_si128(perm, _mm_set1_epi32(0x7f)); // 7 or 6 bits
+    const __m128i middlebyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x3f00)); // 5 or 6 bits
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    const __m128i highbyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x0f0000)); // 4 bits
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 4);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted), highbyte_shifted);
+    _mm_storeu_si128((__m128i *)utf32_output, composed);
+    utf32_output += 4;
+    return 12;
+  }
+  /// We do not have a fast path available, so we fallback.
+
+  const uint8_t idx =
+      tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][0];
+  const uint8_t consumed =
+      tables::utf8_to_utf16::utf8bigindex[input_utf8_end_of_code_point_mask][1];
+  if (idx < 64) {
+    // SIX (6) input code-words
+    // this is a relatively easy scenario
+    // we process SIX (6) input code-words. The max length in bytes of six code
+    // words spanning between 1 and 2 bytes each is 12 bytes. On processors
+    // where pdep/pext is fast, we might be able to use a small lookup table.
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi16(0x7f));
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi16(0x1f00));
+    const __m128i composed = _mm_or_si128(ascii, _mm_srli_epi16(highbyte, 2));
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output), _mm_cvtepu16_epi32(composed));
+    _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output+4), _mm_cvtepu16_epi32(_mm_srli_si128(composed,8)));
+    utf32_output += 6; // We wrote 12 bytes, 6 code points.
+  } else if (idx < 145) {
+    // FOUR (4) input code-words
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii =
+        _mm_and_si128(perm, _mm_set1_epi32(0x7f)); // 7 or 6 bits
+    const __m128i middlebyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x3f00)); // 5 or 6 bits
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    const __m128i highbyte =
+        _mm_and_si128(perm, _mm_set1_epi32(0x0f0000)); // 4 bits
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 4);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted), highbyte_shifted);
+    _mm_storeu_si128((__m128i *)utf32_output, composed);
+    utf32_output += 4;
+  } else if (idx < 209) {
+    // TWO (2) input code-words
+    const __m128i sh =
+        _mm_loadu_si128((const __m128i *)tables::utf8_to_utf16::shufutf8[idx]);
+    const __m128i perm = _mm_shuffle_epi8(in, sh);
+    const __m128i ascii = _mm_and_si128(perm, _mm_set1_epi32(0x7f));
+    const __m128i middlebyte = _mm_and_si128(perm, _mm_set1_epi32(0x3f00));
+    const __m128i middlebyte_shifted = _mm_srli_epi32(middlebyte, 2);
+    __m128i middlehighbyte = _mm_and_si128(perm, _mm_set1_epi32(0x3f0000));
+    // correct for spurious high bit
+    const __m128i correct =
+        _mm_srli_epi32(_mm_and_si128(perm, _mm_set1_epi32(0x400000)), 1);
+    middlehighbyte = _mm_xor_si128(correct, middlehighbyte);
+    const __m128i middlehighbyte_shifted = _mm_srli_epi32(middlehighbyte, 4);
+    const __m128i highbyte = _mm_and_si128(perm, _mm_set1_epi32(0x07000000));
+    const __m128i highbyte_shifted = _mm_srli_epi32(highbyte, 6);
+    const __m128i composed =
+        _mm_or_si128(_mm_or_si128(ascii, middlebyte_shifted),
+                     _mm_or_si128(highbyte_shifted, middlehighbyte_shifted));
+    _mm_storeu_si128((__m128i *)utf32_output, composed);
+    utf32_output += 3;
+  } else {
+    // here we know that there is an error but we do not handle errors
+  }
+  return consumed;
+}
+/* end file src/westmere/sse_convert_utf8_to_utf32.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_convert_utf16_to_utf8.cpp
+/* begin file src/westmere/sse_convert_utf16_to_utf8.cpp */
+/*
+    The vectorized algorithm works on single SSE register i.e., it
+    loads eight 16-bit words.
+
+    We consider three cases:
+    1. an input register contains no surrogates and each value
+       is in range 0x0000 .. 0x07ff.
+    2. an input register contains no surrogates and values are
+       is in range 0x0000 .. 0xffff.
+    3. an input register contains surrogates --- i.e. codepoints
+       can have 16 or 32 bits.
+
+    Ad 1.
+
+    When values are less than 0x0800, it means that a 16-bit words
+    can be converted into: 1) single UTF8 byte (when it's an ASCII
+    char) or 2) two UTF8 bytes.
+
+    For this case we do only some shuffle to obtain these 2-byte
+    codes and finally compress the whole SSE register with a single
+    shuffle.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+    Ad 2.
+
+    When values fit in 16-bit words, but are above 0x07ff, then
+    a single word may produce one, two or three UTF8 bytes.
+
+    We prepare data for all these three cases in two registers.
+    The first register contains lower two UTF8 bytes (used in all
+    cases), while the second one contains just the third byte for
+    the three-UTF8-bytes case.
+
+    Finally these two registers are interleaved forming eight-element
+    array of 32-bit values. The array spans two SSE registers.
+    The bytes from the registers are compressed using two shuffles.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+
+    To summarize:
+    - We need two 256-entry tables that have 8704 bytes in total.
+*/
+
+/*
+  Returns a pair: the first unprocessed byte from buf and utf8_output
+  A scalar routing should carry on the conversion of the tail.
+*/
+template <endianness big_endian>
+std::pair<const char16_t*, char*> sse_convert_utf16_to_utf8(const char16_t* buf, size_t len, char* utf8_output) {
+
+  const char16_t* end = buf + len;
+
+  const __m128i v_0000 = _mm_setzero_si128();
+  const __m128i v_f800 = _mm_set1_epi16((int16_t)0xf800);
+  const __m128i v_d800 = _mm_set1_epi16((int16_t)0xd800);
+  const __m128i v_c080 = _mm_set1_epi16((int16_t)0xc080);
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m128i in = _mm_loadu_si128((__m128i*)buf);
+    if (big_endian) {
+      const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+      in = _mm_shuffle_epi8(in, swap);
+    }
+    // a single 16-bit UTF-16 word can yield 1, 2 or 3 UTF-8 bytes
+    const __m128i v_ff80 = _mm_set1_epi16((int16_t)0xff80);
+    if(_mm_testz_si128(in, v_ff80)) { // ASCII fast path!!!!
+        __m128i nextin = _mm_loadu_si128((__m128i*)buf+1);
+        if (big_endian) {
+          const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+          nextin = _mm_shuffle_epi8(nextin, swap);
+        }
+        if(!_mm_testz_si128(nextin, v_ff80)) {
+          // 1. pack the bytes
+          // obviously suboptimal.
+          const __m128i utf8_packed = _mm_packus_epi16(in,in);
+          // 2. store (16 bytes)
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 8;
+          utf8_output += 8;
+          in = nextin;
+        } else {
+          // 1. pack the bytes
+          // obviously suboptimal.
+          const __m128i utf8_packed = _mm_packus_epi16(in,nextin);
+          // 2. store (16 bytes)
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 16;
+          utf8_output += 16;
+          continue; // we are done for this round!
+        }
+    }
+
+    // no bits set above 7th bit
+    const __m128i one_byte_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in, v_ff80), v_0000);
+    const uint16_t one_byte_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m128i one_or_two_bytes_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in, v_f800), v_0000);
+    const uint16_t one_or_two_bytes_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(one_or_two_bytes_bytemask));
+
+    if (one_or_two_bytes_bitmask == 0xffff) {
+          // 1. prepare 2-byte values
+          // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+          // expected output   : [110a|aaaa|10bb|bbbb] x 8
+          const __m128i v_1f00 = _mm_set1_epi16((int16_t)0x1f00);
+          const __m128i v_003f = _mm_set1_epi16((int16_t)0x003f);
+
+          // t0 = [000a|aaaa|bbbb|bb00]
+          const __m128i t0 = _mm_slli_epi16(in, 2);
+          // t1 = [000a|aaaa|0000|0000]
+          const __m128i t1 = _mm_and_si128(t0, v_1f00);
+          // t2 = [0000|0000|00bb|bbbb]
+          const __m128i t2 = _mm_and_si128(in, v_003f);
+          // t3 = [000a|aaaa|00bb|bbbb]
+          const __m128i t3 = _mm_or_si128(t1, t2);
+          // t4 = [110a|aaaa|10bb|bbbb]
+          const __m128i t4 = _mm_or_si128(t3, v_c080);
+
+          // 2. merge ASCII and 2-byte codewords
+          const __m128i utf8_unpacked = _mm_blendv_epi8(t4, in, one_byte_bytemask);
+
+          // 3. prepare bitmask for 8-bit lookup
+          //    one_byte_bitmask = hhggffeeddccbbaa -- the bits are doubled (h - MSB, a - LSB)
+          const uint16_t m0 = one_byte_bitmask & 0x5555;  // m0 = 0h0g0f0e0d0c0b0a
+          const uint16_t m1 = static_cast<uint16_t>(m0 >> 7);                    // m1 = 00000000h0g0f0e0
+          const uint8_t  m2 = static_cast<uint8_t>((m0 | m1) & 0xff);           // m2 =         hdgcfbea
+          // 4. pack the bytes
+          const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[m2][0];
+          const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+          const __m128i utf8_packed = _mm_shuffle_epi8(utf8_unpacked, shuffle);
+
+          // 5. store bytes
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+
+          // 6. adjust pointers
+          buf += 8;
+          utf8_output += row[0];
+          continue;
+
+    }
+
+    // 1. Check if there are any surrogate word in the input chunk.
+    //    We have also deal with situation when there is a surrogate word
+    //    at the end of a chunk.
+    const __m128i surrogates_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in, v_f800), v_d800);
+
+    // bitmask = 0x0000 if there are no surrogates
+    //         = 0xc000 if the last word is a surrogate
+    const uint16_t surrogates_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(surrogates_bytemask));
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+    if (surrogates_bitmask == 0x0000) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+        const __m128i dup_even = _mm_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                                0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+        /* In this branch we handle three cases:
+           1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+           2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+           3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+          We expand the input word (16-bit) into two words (32-bit), thus
+          we have room for four bytes. However, we need five distinct bit
+          layouts. Note that the last byte in cases #2 and #3 is the same.
+
+          We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+          in register t2.
+
+          We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+          either byte 1 for case #2 or byte 2 for case #3. Note that they
+          differ by exactly one bit.
+
+          Finally from these two words we build proper UTF-8 sequence, taking
+          into account the case (i.e, the number of bytes to write).
+        */
+        /**
+         * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+         * t2 => [0ccc|cccc] [10cc|cccc]
+         * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+         */
+#define vec(x) _mm_set1_epi16(static_cast<uint16_t>(x))
+        // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+        const __m128i t0 = _mm_shuffle_epi8(in, dup_even);
+        // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+        const __m128i t1 = _mm_and_si128(t0, vec(0b0011111101111111));
+        // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+        const __m128i t2 = _mm_or_si128 (t1, vec(0b1000000000000000));
+
+        // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+        const __m128i s0 = _mm_srli_epi16(in, 4);
+        // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+        const __m128i s1 = _mm_and_si128(s0, vec(0b0000111111111100));
+        // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+        const __m128i s2 = _mm_maddubs_epi16(s1, vec(0x0140));
+        // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+        const __m128i s3 = _mm_or_si128(s2, vec(0b1100000011100000));
+        const __m128i m0 = _mm_andnot_si128(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+        const __m128i s4 = _mm_xor_si128(s3, m0);
+#undef vec
+
+        // 4. expand words 16-bit => 32-bit
+        const __m128i out0 = _mm_unpacklo_epi16(t2, s4);
+        const __m128i out1 = _mm_unpackhi_epi16(t2, s4);
+
+        // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+        const uint16_t mask = (one_byte_bitmask & 0x5555) |
+                              (one_or_two_bytes_bitmask & 0xaaaa);
+        if(mask == 0) {
+          // We only have three-byte words. Use fast path.
+          const __m128i shuffle = _mm_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+          const __m128i utf8_0 = _mm_shuffle_epi8(out0, shuffle);
+          const __m128i utf8_1 = _mm_shuffle_epi8(out1, shuffle);
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+          utf8_output += 12;
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+          utf8_output += 12;
+          buf += 8;
+          continue;
+        }
+        const uint8_t mask0 = uint8_t(mask);
+
+        const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+        const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+        const __m128i utf8_0 = _mm_shuffle_epi8(out0, shuffle0);
+
+        const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+
+        const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+        const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+        const __m128i utf8_1 = _mm_shuffle_epi8(out1, shuffle1);
+
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+        utf8_output += row0[0];
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+        utf8_output += row1[0];
+
+        buf += 8;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word & 0xFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word &0xF800 ) != 0xD800) {
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k+1]) : buf[k+1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(nullptr, utf8_output); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf8_output++ = char((value>>18) | 0b11110000);
+          *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((value & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  return std::make_pair(buf, utf8_output);
+}
+
+
+/*
+  Returns a pair: a result struct and utf8_output.
+  If there is an error, the count field of the result is the position of the error.
+  Otherwise, it is the position of the first unprocessed byte in buf (even if finished).
+  A scalar routing should carry on the conversion of the tail if needed.
+*/
+template <endianness big_endian>
+std::pair<result, char*> sse_convert_utf16_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) {
+  const char16_t* start = buf;
+  const char16_t* end = buf + len;
+
+  const __m128i v_0000 = _mm_setzero_si128();
+  const __m128i v_f800 = _mm_set1_epi16((int16_t)0xf800);
+  const __m128i v_d800 = _mm_set1_epi16((int16_t)0xd800);
+  const __m128i v_c080 = _mm_set1_epi16((int16_t)0xc080);
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m128i in = _mm_loadu_si128((__m128i*)buf);
+    if (big_endian) {
+      const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+      in = _mm_shuffle_epi8(in, swap);
+    }
+    // a single 16-bit UTF-16 word can yield 1, 2 or 3 UTF-8 bytes
+    const __m128i v_ff80 = _mm_set1_epi16((int16_t)0xff80);
+    if(_mm_testz_si128(in, v_ff80)) { // ASCII fast path!!!!
+        __m128i nextin = _mm_loadu_si128((__m128i*)buf+1);
+        if (big_endian) {
+          const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+          nextin = _mm_shuffle_epi8(nextin, swap);
+        }
+        if(!_mm_testz_si128(nextin, v_ff80)) {
+          // 1. pack the bytes
+          // obviously suboptimal.
+          const __m128i utf8_packed = _mm_packus_epi16(in,in);
+          // 2. store (16 bytes)
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 8;
+          utf8_output += 8;
+          in = nextin;
+        } else {
+          // 1. pack the bytes
+          // obviously suboptimal.
+          const __m128i utf8_packed = _mm_packus_epi16(in,nextin);
+          // 2. store (16 bytes)
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+          // 3. adjust pointers
+          buf += 16;
+          utf8_output += 16;
+          continue; // we are done for this round!
+        }
+    }
+
+    // no bits set above 7th bit
+    const __m128i one_byte_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in, v_ff80), v_0000);
+    const uint16_t one_byte_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m128i one_or_two_bytes_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in, v_f800), v_0000);
+    const uint16_t one_or_two_bytes_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(one_or_two_bytes_bytemask));
+
+    if (one_or_two_bytes_bitmask == 0xffff) {
+          // 1. prepare 2-byte values
+          // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+          // expected output   : [110a|aaaa|10bb|bbbb] x 8
+          const __m128i v_1f00 = _mm_set1_epi16((int16_t)0x1f00);
+          const __m128i v_003f = _mm_set1_epi16((int16_t)0x003f);
+
+          // t0 = [000a|aaaa|bbbb|bb00]
+          const __m128i t0 = _mm_slli_epi16(in, 2);
+          // t1 = [000a|aaaa|0000|0000]
+          const __m128i t1 = _mm_and_si128(t0, v_1f00);
+          // t2 = [0000|0000|00bb|bbbb]
+          const __m128i t2 = _mm_and_si128(in, v_003f);
+          // t3 = [000a|aaaa|00bb|bbbb]
+          const __m128i t3 = _mm_or_si128(t1, t2);
+          // t4 = [110a|aaaa|10bb|bbbb]
+          const __m128i t4 = _mm_or_si128(t3, v_c080);
+
+          // 2. merge ASCII and 2-byte codewords
+          const __m128i utf8_unpacked = _mm_blendv_epi8(t4, in, one_byte_bytemask);
+
+          // 3. prepare bitmask for 8-bit lookup
+          //    one_byte_bitmask = hhggffeeddccbbaa -- the bits are doubled (h - MSB, a - LSB)
+          const uint16_t m0 = one_byte_bitmask & 0x5555;  // m0 = 0h0g0f0e0d0c0b0a
+          const uint16_t m1 = static_cast<uint16_t>(m0 >> 7);                    // m1 = 00000000h0g0f0e0
+          const uint8_t  m2 = static_cast<uint8_t>((m0 | m1) & 0xff);           // m2 =         hdgcfbea
+          // 4. pack the bytes
+          const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[m2][0];
+          const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+          const __m128i utf8_packed = _mm_shuffle_epi8(utf8_unpacked, shuffle);
+
+          // 5. store bytes
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+
+          // 6. adjust pointers
+          buf += 8;
+          utf8_output += row[0];
+          continue;
+
+    }
+
+    // 1. Check if there are any surrogate word in the input chunk.
+    //    We have also deal with situation when there is a surrogate word
+    //    at the end of a chunk.
+    const __m128i surrogates_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in, v_f800), v_d800);
+
+    // bitmask = 0x0000 if there are no surrogates
+    //         = 0xc000 if the last word is a surrogate
+    const uint16_t surrogates_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(surrogates_bytemask));
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+    if (surrogates_bitmask == 0x0000) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+        const __m128i dup_even = _mm_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                                0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+        /* In this branch we handle three cases:
+           1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+           2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+           3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+          We expand the input word (16-bit) into two words (32-bit), thus
+          we have room for four bytes. However, we need five distinct bit
+          layouts. Note that the last byte in cases #2 and #3 is the same.
+
+          We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+          in register t2.
+
+          We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+          either byte 1 for case #2 or byte 2 for case #3. Note that they
+          differ by exactly one bit.
+
+          Finally from these two words we build proper UTF-8 sequence, taking
+          into account the case (i.e, the number of bytes to write).
+        */
+        /**
+         * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+         * t2 => [0ccc|cccc] [10cc|cccc]
+         * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+         */
+#define vec(x) _mm_set1_epi16(static_cast<uint16_t>(x))
+        // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+        const __m128i t0 = _mm_shuffle_epi8(in, dup_even);
+        // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+        const __m128i t1 = _mm_and_si128(t0, vec(0b0011111101111111));
+        // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+        const __m128i t2 = _mm_or_si128 (t1, vec(0b1000000000000000));
+
+        // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+        const __m128i s0 = _mm_srli_epi16(in, 4);
+        // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+        const __m128i s1 = _mm_and_si128(s0, vec(0b0000111111111100));
+        // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+        const __m128i s2 = _mm_maddubs_epi16(s1, vec(0x0140));
+        // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+        const __m128i s3 = _mm_or_si128(s2, vec(0b1100000011100000));
+        const __m128i m0 = _mm_andnot_si128(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+        const __m128i s4 = _mm_xor_si128(s3, m0);
+#undef vec
+
+        // 4. expand words 16-bit => 32-bit
+        const __m128i out0 = _mm_unpacklo_epi16(t2, s4);
+        const __m128i out1 = _mm_unpackhi_epi16(t2, s4);
+
+        // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+        const uint16_t mask = (one_byte_bitmask & 0x5555) |
+                              (one_or_two_bytes_bitmask & 0xaaaa);
+        if(mask == 0) {
+          // We only have three-byte words. Use fast path.
+          const __m128i shuffle = _mm_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+          const __m128i utf8_0 = _mm_shuffle_epi8(out0, shuffle);
+          const __m128i utf8_1 = _mm_shuffle_epi8(out1, shuffle);
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+          utf8_output += 12;
+          _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+          utf8_output += 12;
+          buf += 8;
+          continue;
+        }
+        const uint8_t mask0 = uint8_t(mask);
+
+        const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+        const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+        const __m128i utf8_0 = _mm_shuffle_epi8(out0, shuffle0);
+
+        const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+
+        const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+        const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+        const __m128i utf8_1 = _mm_shuffle_epi8(out1, shuffle1);
+
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+        utf8_output += row0[0];
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+        utf8_output += row1[0];
+
+        buf += 8;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word & 0xFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word &0xF800 ) != 0xD800) {
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k+1]) : buf[k+1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(result(error_code::SURROGATE, buf - start + k - 1), utf8_output); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf8_output++ = char((value>>18) | 0b11110000);
+          *utf8_output++ = char(((value>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((value>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((value & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf8_output);
+}
+/* end file src/westmere/sse_convert_utf16_to_utf8.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_convert_utf16_to_utf32.cpp
+/* begin file src/westmere/sse_convert_utf16_to_utf32.cpp */
+/*
+    The vectorized algorithm works on single SSE register i.e., it
+    loads eight 16-bit words.
+
+    We consider three cases:
+    1. an input register contains no surrogates and each value
+       is in range 0x0000 .. 0x07ff.
+    2. an input register contains no surrogates and values are
+       is in range 0x0000 .. 0xffff.
+    3. an input register contains surrogates --- i.e. codepoints
+       can have 16 or 32 bits.
+
+    Ad 1.
+
+    When values are less than 0x0800, it means that a 16-bit words
+    can be converted into: 1) single UTF8 byte (when it's an ASCII
+    char) or 2) two UTF8 bytes.
+
+    For this case we do only some shuffle to obtain these 2-byte
+    codes and finally compress the whole SSE register with a single
+    shuffle.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+    Ad 2.
+
+    When values fit in 16-bit words, but are above 0x07ff, then
+    a single word may produce one, two or three UTF8 bytes.
+
+    We prepare data for all these three cases in two registers.
+    The first register contains lower two UTF8 bytes (used in all
+    cases), while the second one contains just the third byte for
+    the three-UTF8-bytes case.
+
+    Finally these two registers are interleaved forming eight-element
+    array of 32-bit values. The array spans two SSE registers.
+    The bytes from the registers are compressed using two shuffles.
+
+    We need 256-entry lookup table to get a compression pattern
+    and the number of output bytes in the compressed vector register.
+    Each entry occupies 17 bytes.
+
+
+    To summarize:
+    - We need two 256-entry tables that have 8704 bytes in total.
+*/
+
+/*
+  Returns a pair: the first unprocessed byte from buf and utf8_output
+  A scalar routing should carry on the conversion of the tail.
+*/
+template <endianness big_endian>
+std::pair<const char16_t*, char32_t*> sse_convert_utf16_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) {
+  const char16_t* end = buf + len;
+
+  const __m128i v_f800 = _mm_set1_epi16((int16_t)0xf800);
+  const __m128i v_d800 = _mm_set1_epi16((int16_t)0xd800);
+
+  while (buf + 16 <= end) {
+    __m128i in = _mm_loadu_si128((__m128i*)buf);
+
+    if (big_endian) {
+      const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+      in = _mm_shuffle_epi8(in, swap);
+    }
+
+    // 1. Check if there are any surrogate word in the input chunk.
+    //    We have also deal with situation when there is a surrogate word
+    //    at the end of a chunk.
+    const __m128i surrogates_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in, v_f800), v_d800);
+
+    // bitmask = 0x0000 if there are no surrogates
+    //         = 0xc000 if the last word is a surrogate
+    const uint16_t surrogates_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(surrogates_bytemask));
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+    if (surrogates_bitmask == 0x0000) {
+      // case: no surrogate pair, extend 16-bit words to 32-bit words
+        _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output), _mm_cvtepu16_epi32(in));
+        _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output+4), _mm_cvtepu16_epi32(_mm_srli_si128(in,8)));
+        utf32_output += 8;
+        buf += 8;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word &0xF800 ) != 0xD800) {
+          *utf32_output++ = char32_t(word);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k+1]) : buf[k+1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(nullptr, utf32_output); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf32_output++ = char32_t(value);
+        }
+      }
+      buf += k;
+    }
+  } // while
+  return std::make_pair(buf, utf32_output);
+}
+
+
+/*
+  Returns a pair: a result struct and utf8_output.
+  If there is an error, the count field of the result is the position of the error.
+  Otherwise, it is the position of the first unprocessed byte in buf (even if finished).
+  A scalar routing should carry on the conversion of the tail if needed.
+*/
+template <endianness big_endian>
+std::pair<result, char32_t*> sse_convert_utf16_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) {
+  const char16_t* start = buf;
+  const char16_t* end = buf + len;
+
+  const __m128i v_f800 = _mm_set1_epi16((int16_t)0xf800);
+  const __m128i v_d800 = _mm_set1_epi16((int16_t)0xd800);
+
+  while (buf + 16 <= end) {
+    __m128i in = _mm_loadu_si128((__m128i*)buf);
+
+    if (big_endian) {
+      const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+      in = _mm_shuffle_epi8(in, swap);
+    }
+
+    // 1. Check if there are any surrogate word in the input chunk.
+    //    We have also deal with situation when there is a surrogate word
+    //    at the end of a chunk.
+    const __m128i surrogates_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in, v_f800), v_d800);
+
+    // bitmask = 0x0000 if there are no surrogates
+    //         = 0xc000 if the last word is a surrogate
+    const uint16_t surrogates_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(surrogates_bytemask));
+    // It might seem like checking for surrogates_bitmask == 0xc000 could help. However,
+    // it is likely an uncommon occurrence.
+    if (surrogates_bitmask == 0x0000) {
+      // case: no surrogate pair, extend 16-bit words to 32-bit words
+        _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output), _mm_cvtepu16_epi32(in));
+        _mm_storeu_si128(reinterpret_cast<__m128i *>(utf32_output+4), _mm_cvtepu16_epi32(_mm_srli_si128(in,8)));
+        utf32_output += 8;
+        buf += 8;
+    // surrogate pair(s) in a register
+    } else {
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint16_t word = big_endian ? scalar::utf16::swap_bytes(buf[k]) : buf[k];
+        if((word &0xF800 ) != 0xD800) {
+          *utf32_output++ = char32_t(word);
+        } else {
+          // must be a surrogate pair
+          uint16_t diff = uint16_t(word - 0xD800);
+          uint16_t next_word = big_endian ? scalar::utf16::swap_bytes(buf[k+1]) : buf[k+1];
+          k++;
+          uint16_t diff2 = uint16_t(next_word - 0xDC00);
+          if((diff | diff2) > 0x3FF)  { return std::make_pair(result(error_code::SURROGATE, buf - start + k - 1), utf32_output); }
+          uint32_t value = (diff << 10) + diff2 + 0x10000;
+          *utf32_output++ = char32_t(value);
+        }
+      }
+      buf += k;
+    }
+  } // while
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf32_output);
+}
+/* end file src/westmere/sse_convert_utf16_to_utf32.cpp */
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_convert_utf32_to_utf8.cpp
+/* begin file src/westmere/sse_convert_utf32_to_utf8.cpp */
+std::pair<const char32_t*, char*> sse_convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) {
+
+  const char32_t* end = buf + len;
+
+  const __m128i v_0000 = _mm_setzero_si128();
+  const __m128i v_f800 = _mm_set1_epi16((uint16_t)0xf800);
+  const __m128i v_c080 = _mm_set1_epi16((uint16_t)0xc080);
+  const __m128i v_ff80 = _mm_set1_epi16((uint16_t)0xff80);
+  const __m128i v_ffff0000 = _mm_set1_epi32((uint32_t)0xffff0000);
+  const __m128i v_7fffffff = _mm_set1_epi32((uint32_t)0x7fffffff);
+  __m128i running_max = _mm_setzero_si128();
+  __m128i forbidden_bytemask = _mm_setzero_si128();
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m128i in = _mm_loadu_si128((__m128i*)buf);
+    __m128i nextin = _mm_loadu_si128((__m128i*)buf+1);
+    running_max = _mm_max_epu32(_mm_max_epu32(in, running_max), nextin);
+
+    // Pack 32-bit UTF-32 words to 16-bit UTF-16 words with unsigned saturation
+    __m128i in_16 = _mm_packus_epi32(_mm_and_si128(in, v_7fffffff), _mm_and_si128(nextin, v_7fffffff));
+
+    // Try to apply UTF-16 => UTF-8 from ./sse_convert_utf16_to_utf8.cpp
+
+    // Check for ASCII fast path
+    if(_mm_testz_si128(in_16, v_ff80)) { // ASCII fast path!!!!
+      __m128i thirdin = _mm_loadu_si128((__m128i*)buf+2);
+      __m128i fourthin = _mm_loadu_si128((__m128i*)buf+3);
+      running_max = _mm_max_epu32(_mm_max_epu32(thirdin, running_max), fourthin);
+      __m128i nextin_16 = _mm_packus_epi32(_mm_and_si128(thirdin, v_7fffffff), _mm_and_si128(fourthin, v_7fffffff));
+      if(!_mm_testz_si128(nextin_16, v_ff80)) {
+        // 1. pack the bytes
+        // obviously suboptimal.
+        const __m128i utf8_packed = _mm_packus_epi16(in_16,in_16);
+        // 2. store (16 bytes)
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+        // 3. adjust pointers
+        buf += 8;
+        utf8_output += 8;
+        // Proceed with next input
+        in_16 = nextin_16;
+      } else {
+        // 1. pack the bytes
+        const __m128i utf8_packed = _mm_packus_epi16(in_16, nextin_16);
+        // 2. store (16 bytes)
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+        // 3. adjust pointers
+        buf += 16;
+        utf8_output += 16;
+        continue; // we are done for this round!
+      }
+    }
+
+    // no bits set above 7th bit
+    const __m128i one_byte_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in_16, v_ff80), v_0000);
+    const uint16_t one_byte_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m128i one_or_two_bytes_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in_16, v_f800), v_0000);
+    const uint16_t one_or_two_bytes_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(one_or_two_bytes_bytemask));
+
+    if (one_or_two_bytes_bitmask == 0xffff) {
+      // case: all words either produce 1 or 2 UTF-8 bytes (at least one produces 2 bytes)
+      // 1. prepare 2-byte values
+      // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+      // expected output   : [110a|aaaa|10bb|bbbb] x 8
+      const __m128i v_1f00 = _mm_set1_epi16((int16_t)0x1f00);
+      const __m128i v_003f = _mm_set1_epi16((int16_t)0x003f);
+
+      // t0 = [000a|aaaa|bbbb|bb00]
+      const __m128i t0 = _mm_slli_epi16(in_16, 2);
+      // t1 = [000a|aaaa|0000|0000]
+      const __m128i t1 = _mm_and_si128(t0, v_1f00);
+      // t2 = [0000|0000|00bb|bbbb]
+      const __m128i t2 = _mm_and_si128(in_16, v_003f);
+      // t3 = [000a|aaaa|00bb|bbbb]
+      const __m128i t3 = _mm_or_si128(t1, t2);
+      // t4 = [110a|aaaa|10bb|bbbb]
+      const __m128i t4 = _mm_or_si128(t3, v_c080);
+
+      // 2. merge ASCII and 2-byte codewords
+      const __m128i utf8_unpacked = _mm_blendv_epi8(t4, in_16, one_byte_bytemask);
+
+      // 3. prepare bitmask for 8-bit lookup
+      //    one_byte_bitmask = hhggffeeddccbbaa -- the bits are doubled (h - MSB, a - LSB)
+      const uint16_t m0 = one_byte_bitmask & 0x5555;  // m0 = 0h0g0f0e0d0c0b0a
+      const uint16_t m1 = static_cast<uint16_t>(m0 >> 7);                    // m1 = 00000000h0g0f0e0
+      const uint8_t  m2 = static_cast<uint8_t>((m0 | m1) & 0xff);           // m2 =         hdgcfbea
+      // 4. pack the bytes
+      const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[m2][0];
+      const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+      const __m128i utf8_packed = _mm_shuffle_epi8(utf8_unpacked, shuffle);
+
+      // 5. store bytes
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+
+      // 6. adjust pointers
+      buf += 8;
+      utf8_output += row[0];
+      continue;
+    }
+
+
+    // Check for overflow in packing
+    const __m128i saturation_bytemask = _mm_cmpeq_epi32(_mm_and_si128(_mm_or_si128(in, nextin), v_ffff0000), v_0000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm_movemask_epi8(saturation_bytemask));
+
+    if (saturation_bitmask == 0xffff) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+      const __m128i v_d800 = _mm_set1_epi16((uint16_t)0xd800);
+      forbidden_bytemask = _mm_or_si128(forbidden_bytemask, _mm_cmpeq_epi16(_mm_and_si128(in_16, v_f800), v_d800));
+
+      const __m128i dup_even = _mm_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+      /* In this branch we handle three cases:
+          1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+          2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+          3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+        We expand the input word (16-bit) into two words (32-bit), thus
+        we have room for four bytes. However, we need five distinct bit
+        layouts. Note that the last byte in cases #2 and #3 is the same.
+
+        We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+        in register t2.
+
+        We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+        either byte 1 for case #2 or byte 2 for case #3. Note that they
+        differ by exactly one bit.
+
+        Finally from these two words we build proper UTF-8 sequence, taking
+        into account the case (i.e, the number of bytes to write).
+      */
+      /**
+       * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+       * t2 => [0ccc|cccc] [10cc|cccc]
+       * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+       */
+#define vec(x) _mm_set1_epi16(static_cast<uint16_t>(x))
+      // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+      const __m128i t0 = _mm_shuffle_epi8(in_16, dup_even);
+      // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+      const __m128i t1 = _mm_and_si128(t0, vec(0b0011111101111111));
+      // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+      const __m128i t2 = _mm_or_si128 (t1, vec(0b1000000000000000));
+
+      // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+      const __m128i s0 = _mm_srli_epi16(in_16, 4);
+      // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+      const __m128i s1 = _mm_and_si128(s0, vec(0b0000111111111100));
+      // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+      const __m128i s2 = _mm_maddubs_epi16(s1, vec(0x0140));
+      // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+      const __m128i s3 = _mm_or_si128(s2, vec(0b1100000011100000));
+      const __m128i m0 = _mm_andnot_si128(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+      const __m128i s4 = _mm_xor_si128(s3, m0);
+#undef vec
+
+      // 4. expand words 16-bit => 32-bit
+      const __m128i out0 = _mm_unpacklo_epi16(t2, s4);
+      const __m128i out1 = _mm_unpackhi_epi16(t2, s4);
+
+      // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+      const uint16_t mask = (one_byte_bitmask & 0x5555) |
+                            (one_or_two_bytes_bitmask & 0xaaaa);
+      if(mask == 0) {
+        // We only have three-byte words. Use fast path.
+        const __m128i shuffle = _mm_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+        const __m128i utf8_0 = _mm_shuffle_epi8(out0, shuffle);
+        const __m128i utf8_1 = _mm_shuffle_epi8(out1, shuffle);
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+        utf8_output += 12;
+        buf += 8;
+        continue;
+      }
+      const uint8_t mask0 = uint8_t(mask);
+
+      const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+      const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+      const __m128i utf8_0 = _mm_shuffle_epi8(out0, shuffle0);
+
+      const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+
+      const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+      const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+      const __m128i utf8_1 = _mm_shuffle_epi8(out1, shuffle1);
+
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+      utf8_output += row0[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+      utf8_output += row1[0];
+
+      buf += 8;
+    } else {
+      // case: at least one 32-bit word produce a surrogate pair in UTF-16 <=> will produce four UTF-8 bytes
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFFFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xFFFFF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word &0xFFFF0000 )==0) {
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(nullptr, utf8_output); }
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          if (word > 0x10FFFF) { return std::make_pair(nullptr, utf8_output); }
+          *utf8_output++ = char((word>>18) | 0b11110000);
+          *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  // check for invalid input
+  const __m128i v_10ffff = _mm_set1_epi32((uint32_t)0x10ffff);
+  if(static_cast<uint16_t>(_mm_movemask_epi8(_mm_cmpeq_epi32(_mm_max_epu32(running_max, v_10ffff), v_10ffff))) != 0xffff) {
+    return std::make_pair(nullptr, utf8_output);
+  }
+
+  if (static_cast<uint32_t>(_mm_movemask_epi8(forbidden_bytemask)) != 0) { return std::make_pair(nullptr, utf8_output); }
+
+  return std::make_pair(buf, utf8_output);
+}
+
+
+std::pair<result, char*> sse_convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) {
+
+  const char32_t* end = buf + len;
+  const char32_t* start = buf;
+
+  const __m128i v_0000 = _mm_setzero_si128();
+  const __m128i v_f800 = _mm_set1_epi16((uint16_t)0xf800);
+  const __m128i v_c080 = _mm_set1_epi16((uint16_t)0xc080);
+  const __m128i v_ff80 = _mm_set1_epi16((uint16_t)0xff80);
+  const __m128i v_ffff0000 = _mm_set1_epi32((uint32_t)0xffff0000);
+  const __m128i v_7fffffff = _mm_set1_epi32((uint32_t)0x7fffffff);
+  const __m128i v_10ffff = _mm_set1_epi32((uint32_t)0x10ffff);
+
+  const size_t safety_margin = 11; // to avoid overruns, see issue https://github.com/simdutf/simdutf/issues/92
+
+  while (buf + 16 + safety_margin <= end) {
+    __m128i in = _mm_loadu_si128((__m128i*)buf);
+    __m128i nextin = _mm_loadu_si128((__m128i*)buf+1);
+
+    // Check for too large input
+    __m128i max_input = _mm_max_epu32(_mm_max_epu32(in, nextin), v_10ffff);
+    if(static_cast<uint16_t>(_mm_movemask_epi8(_mm_cmpeq_epi32(max_input, v_10ffff))) != 0xffff) {
+      return std::make_pair(result(error_code::TOO_LARGE, buf - start), utf8_output);
+    }
+
+    // Pack 32-bit UTF-32 words to 16-bit UTF-16 words with unsigned saturation
+    __m128i in_16 = _mm_packus_epi32(_mm_and_si128(in, v_7fffffff), _mm_and_si128(nextin, v_7fffffff));
+
+    // Try to apply UTF-16 => UTF-8 from ./sse_convert_utf16_to_utf8.cpp
+
+    // Check for ASCII fast path
+    if(_mm_testz_si128(in_16, v_ff80)) { // ASCII fast path!!!!
+      __m128i thirdin = _mm_loadu_si128((__m128i*)buf+2);
+      __m128i fourthin = _mm_loadu_si128((__m128i*)buf+3);
+      __m128i nextin_16 = _mm_packus_epi32(_mm_and_si128(thirdin, v_7fffffff), _mm_and_si128(fourthin, v_7fffffff));
+      if(!_mm_testz_si128(nextin_16, v_ff80)) {
+        // 1. pack the bytes
+        // obviously suboptimal.
+        const __m128i utf8_packed = _mm_packus_epi16(in_16,in_16);
+        // 2. store (16 bytes)
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+        // 3. adjust pointers
+        buf += 8;
+        utf8_output += 8;
+        // Proceed with next input
+        in_16 = nextin_16;
+        __m128i next_max_input = _mm_max_epu32(_mm_max_epu32(thirdin, fourthin), v_10ffff);
+        if(static_cast<uint16_t>(_mm_movemask_epi8(_mm_cmpeq_epi32(next_max_input, v_10ffff))) != 0xffff) {
+          return std::make_pair(result(error_code::TOO_LARGE, buf - start), utf8_output);
+        }
+      } else {
+        // 1. pack the bytes
+        const __m128i utf8_packed = _mm_packus_epi16(in_16, nextin_16);
+        // 2. store (16 bytes)
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+        // 3. adjust pointers
+        buf += 16;
+        utf8_output += 16;
+        continue; // we are done for this round!
+      }
+    }
+
+    // no bits set above 7th bit
+    const __m128i one_byte_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in_16, v_ff80), v_0000);
+    const uint16_t one_byte_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(one_byte_bytemask));
+
+    // no bits set above 11th bit
+    const __m128i one_or_two_bytes_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in_16, v_f800), v_0000);
+    const uint16_t one_or_two_bytes_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(one_or_two_bytes_bytemask));
+
+    if (one_or_two_bytes_bitmask == 0xffff) {
+      // case: all words either produce 1 or 2 UTF-8 bytes (at least one produces 2 bytes)
+      // 1. prepare 2-byte values
+      // input 16-bit word : [0000|0aaa|aabb|bbbb] x 8
+      // expected output   : [110a|aaaa|10bb|bbbb] x 8
+      const __m128i v_1f00 = _mm_set1_epi16((int16_t)0x1f00);
+      const __m128i v_003f = _mm_set1_epi16((int16_t)0x003f);
+
+      // t0 = [000a|aaaa|bbbb|bb00]
+      const __m128i t0 = _mm_slli_epi16(in_16, 2);
+      // t1 = [000a|aaaa|0000|0000]
+      const __m128i t1 = _mm_and_si128(t0, v_1f00);
+      // t2 = [0000|0000|00bb|bbbb]
+      const __m128i t2 = _mm_and_si128(in_16, v_003f);
+      // t3 = [000a|aaaa|00bb|bbbb]
+      const __m128i t3 = _mm_or_si128(t1, t2);
+      // t4 = [110a|aaaa|10bb|bbbb]
+      const __m128i t4 = _mm_or_si128(t3, v_c080);
+
+      // 2. merge ASCII and 2-byte codewords
+      const __m128i utf8_unpacked = _mm_blendv_epi8(t4, in_16, one_byte_bytemask);
+
+      // 3. prepare bitmask for 8-bit lookup
+      //    one_byte_bitmask = hhggffeeddccbbaa -- the bits are doubled (h - MSB, a - LSB)
+      const uint16_t m0 = one_byte_bitmask & 0x5555;  // m0 = 0h0g0f0e0d0c0b0a
+      const uint16_t m1 = static_cast<uint16_t>(m0 >> 7);                    // m1 = 00000000h0g0f0e0
+      const uint8_t  m2 = static_cast<uint8_t>((m0 | m1) & 0xff);           // m2 =         hdgcfbea
+      // 4. pack the bytes
+      const uint8_t* row = &simdutf::tables::utf16_to_utf8::pack_1_2_utf8_bytes[m2][0];
+      const __m128i shuffle = _mm_loadu_si128((__m128i*)(row + 1));
+      const __m128i utf8_packed = _mm_shuffle_epi8(utf8_unpacked, shuffle);
+
+      // 5. store bytes
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_packed);
+
+      // 6. adjust pointers
+      buf += 8;
+      utf8_output += row[0];
+      continue;
+    }
+
+
+    // Check for overflow in packing
+    const __m128i saturation_bytemask = _mm_cmpeq_epi32(_mm_and_si128(_mm_or_si128(in, nextin), v_ffff0000), v_0000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm_movemask_epi8(saturation_bytemask));
+
+    if (saturation_bitmask == 0xffff) {
+      // case: words from register produce either 1, 2 or 3 UTF-8 bytes
+
+      // Check for illegal surrogate words
+      const __m128i v_d800 = _mm_set1_epi16((uint16_t)0xd800);
+      const __m128i forbidden_bytemask = _mm_cmpeq_epi16(_mm_and_si128(in_16, v_f800), v_d800);
+      if (static_cast<uint32_t>(_mm_movemask_epi8(forbidden_bytemask)) != 0) {
+        return std::make_pair(result(error_code::SURROGATE, buf - start), utf8_output);
+      }
+
+      const __m128i dup_even = _mm_setr_epi16(0x0000, 0x0202, 0x0404, 0x0606,
+                                              0x0808, 0x0a0a, 0x0c0c, 0x0e0e);
+
+      /* In this branch we handle three cases:
+          1. [0000|0000|0ccc|cccc] => [0ccc|cccc]                           - single UFT-8 byte
+          2. [0000|0bbb|bbcc|cccc] => [110b|bbbb], [10cc|cccc]              - two UTF-8 bytes
+          3. [aaaa|bbbb|bbcc|cccc] => [1110|aaaa], [10bb|bbbb], [10cc|cccc] - three UTF-8 bytes
+
+        We expand the input word (16-bit) into two words (32-bit), thus
+        we have room for four bytes. However, we need five distinct bit
+        layouts. Note that the last byte in cases #2 and #3 is the same.
+
+        We precompute byte 1 for case #1 and the common byte for cases #2 & #3
+        in register t2.
+
+        We precompute byte 1 for case #3 and -- **conditionally** -- precompute
+        either byte 1 for case #2 or byte 2 for case #3. Note that they
+        differ by exactly one bit.
+
+        Finally from these two words we build proper UTF-8 sequence, taking
+        into account the case (i.e, the number of bytes to write).
+      */
+      /**
+       * Given [aaaa|bbbb|bbcc|cccc] our goal is to produce:
+       * t2 => [0ccc|cccc] [10cc|cccc]
+       * s4 => [1110|aaaa] ([110b|bbbb] OR [10bb|bbbb])
+       */
+#define vec(x) _mm_set1_epi16(static_cast<uint16_t>(x))
+      // [aaaa|bbbb|bbcc|cccc] => [bbcc|cccc|bbcc|cccc]
+      const __m128i t0 = _mm_shuffle_epi8(in_16, dup_even);
+      // [bbcc|cccc|bbcc|cccc] => [00cc|cccc|0bcc|cccc]
+      const __m128i t1 = _mm_and_si128(t0, vec(0b0011111101111111));
+      // [00cc|cccc|0bcc|cccc] => [10cc|cccc|0bcc|cccc]
+      const __m128i t2 = _mm_or_si128 (t1, vec(0b1000000000000000));
+
+      // [aaaa|bbbb|bbcc|cccc] =>  [0000|aaaa|bbbb|bbcc]
+      const __m128i s0 = _mm_srli_epi16(in_16, 4);
+      // [0000|aaaa|bbbb|bbcc] => [0000|aaaa|bbbb|bb00]
+      const __m128i s1 = _mm_and_si128(s0, vec(0b0000111111111100));
+      // [0000|aaaa|bbbb|bb00] => [00bb|bbbb|0000|aaaa]
+      const __m128i s2 = _mm_maddubs_epi16(s1, vec(0x0140));
+      // [00bb|bbbb|0000|aaaa] => [11bb|bbbb|1110|aaaa]
+      const __m128i s3 = _mm_or_si128(s2, vec(0b1100000011100000));
+      const __m128i m0 = _mm_andnot_si128(one_or_two_bytes_bytemask, vec(0b0100000000000000));
+      const __m128i s4 = _mm_xor_si128(s3, m0);
+#undef vec
+
+      // 4. expand words 16-bit => 32-bit
+      const __m128i out0 = _mm_unpacklo_epi16(t2, s4);
+      const __m128i out1 = _mm_unpackhi_epi16(t2, s4);
+
+      // 5. compress 32-bit words into 1, 2 or 3 bytes -- 2 x shuffle
+      const uint16_t mask = (one_byte_bitmask & 0x5555) |
+                            (one_or_two_bytes_bitmask & 0xaaaa);
+      if(mask == 0) {
+        // We only have three-byte words. Use fast path.
+        const __m128i shuffle = _mm_setr_epi8(2,3,1,6,7,5,10,11,9,14,15,13,-1,-1,-1,-1);
+        const __m128i utf8_0 = _mm_shuffle_epi8(out0, shuffle);
+        const __m128i utf8_1 = _mm_shuffle_epi8(out1, shuffle);
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+        utf8_output += 12;
+        _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+        utf8_output += 12;
+        buf += 8;
+        continue;
+      }
+      const uint8_t mask0 = uint8_t(mask);
+
+      const uint8_t* row0 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask0][0];
+      const __m128i shuffle0 = _mm_loadu_si128((__m128i*)(row0 + 1));
+      const __m128i utf8_0 = _mm_shuffle_epi8(out0, shuffle0);
+
+      const uint8_t mask1 = static_cast<uint8_t>(mask >> 8);
+
+      const uint8_t* row1 = &simdutf::tables::utf16_to_utf8::pack_1_2_3_utf8_bytes[mask1][0];
+      const __m128i shuffle1 = _mm_loadu_si128((__m128i*)(row1 + 1));
+      const __m128i utf8_1 = _mm_shuffle_epi8(out1, shuffle1);
+
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_0);
+      utf8_output += row0[0];
+      _mm_storeu_si128((__m128i*)utf8_output, utf8_1);
+      utf8_output += row1[0];
+
+      buf += 8;
+    } else {
+      // case: at least one 32-bit word produce a surrogate pair in UTF-16 <=> will produce four UTF-8 bytes
+      // Let us do a scalar fallback.
+      // It may seem wasteful to use scalar code, but being efficient with SIMD
+      // in the presence of surrogate pairs may require non-trivial tables.
+      size_t forward = 15;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFFFF80)==0) {
+          *utf8_output++ = char(word);
+        } else if((word & 0xFFFFF800)==0) {
+          *utf8_output++ = char((word>>6) | 0b11000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else if((word &0xFFFF0000 )==0) {
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(result(error_code::SURROGATE, buf - start + k), utf8_output); }
+          *utf8_output++ = char((word>>12) | 0b11100000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        } else {
+          if (word > 0x10FFFF) { return std::make_pair(result(error_code::TOO_LARGE, buf- start + k), utf8_output); }
+          *utf8_output++ = char((word>>18) | 0b11110000);
+          *utf8_output++ = char(((word>>12) & 0b111111) | 0b10000000);
+          *utf8_output++ = char(((word>>6) & 0b111111) | 0b10000000);
+          *utf8_output++ = char((word & 0b111111) | 0b10000000);
+        }
+      }
+      buf += k;
+    }
+  } // while
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf8_output);
+}
+/* end file src/westmere/sse_convert_utf32_to_utf8.cpp */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=westmere/sse_convert_utf32_to_utf16.cpp
+/* begin file src/westmere/sse_convert_utf32_to_utf16.cpp */
+template <endianness big_endian>
+std::pair<const char32_t*, char16_t*> sse_convert_utf32_to_utf16(const char32_t* buf, size_t len, char16_t* utf16_output) {
+
+  const char32_t* end = buf + len;
+
+  const __m128i v_0000 = _mm_setzero_si128();
+  const __m128i v_ffff0000 = _mm_set1_epi32((int32_t)0xffff0000);
+  __m128i forbidden_bytemask = _mm_setzero_si128();
+
+  while (buf + 8 <= end) {
+    __m128i in = _mm_loadu_si128((__m128i*)buf);
+    __m128i nextin = _mm_loadu_si128((__m128i*)buf+1);
+    const __m128i saturation_bytemask = _mm_cmpeq_epi32(_mm_and_si128(_mm_or_si128(in, nextin), v_ffff0000), v_0000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm_movemask_epi8(saturation_bytemask));
+
+    // Check if no bits set above 16th
+    if (saturation_bitmask == 0xffff) {
+      // Pack UTF-32 to UTF-16
+      __m128i utf16_packed = _mm_packus_epi32(in, nextin);
+
+      const __m128i v_f800 = _mm_set1_epi16((uint16_t)0xf800);
+      const __m128i v_d800 = _mm_set1_epi16((uint16_t)0xd800);
+      forbidden_bytemask = _mm_or_si128(forbidden_bytemask, _mm_cmpeq_epi16(_mm_and_si128(utf16_packed, v_f800), v_d800));
+
+      if (big_endian) {
+        const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+        utf16_packed = _mm_shuffle_epi8(utf16_packed, swap);
+      }
+
+      _mm_storeu_si128((__m128i*)utf16_output, utf16_packed);
+      utf16_output += 8;
+      buf += 8;
+    } else {
+      size_t forward = 7;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFF0000)==0) {
+          // will not generate a surrogate pair
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(nullptr, utf16_output); }
+          *utf16_output++ = big_endian ? char16_t((uint16_t(word) >> 8) | (uint16_t(word) << 8)) : char16_t(word);
+        } else {
+          // will generate a surrogate pair
+          if (word > 0x10FFFF) { return std::make_pair(nullptr, utf16_output); }
+          word -= 0x10000;
+          uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+          uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+          if (big_endian) {
+            high_surrogate = uint16_t((high_surrogate >> 8) | (high_surrogate << 8));
+            low_surrogate = uint16_t((low_surrogate >> 8) | (low_surrogate << 8));
+          }
+          *utf16_output++ = char16_t(high_surrogate);
+          *utf16_output++ = char16_t(low_surrogate);
+        }
+      }
+      buf += k;
+    }
+  }
+
+  // check for invalid input
+  if (static_cast<uint32_t>(_mm_movemask_epi8(forbidden_bytemask)) != 0) { return std::make_pair(nullptr, utf16_output); }
+
+  return std::make_pair(buf, utf16_output);
+}
+
+
+template <endianness big_endian>
+std::pair<result, char16_t*> sse_convert_utf32_to_utf16_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) {
+  const char32_t* start = buf;
+  const char32_t* end = buf + len;
+
+  const __m128i v_0000 = _mm_setzero_si128();
+  const __m128i v_ffff0000 = _mm_set1_epi32((int32_t)0xffff0000);
+
+  while (buf + 8 <= end) {
+    __m128i in = _mm_loadu_si128((__m128i*)buf);
+    __m128i nextin = _mm_loadu_si128((__m128i*)buf+1);
+    const __m128i saturation_bytemask = _mm_cmpeq_epi32(_mm_and_si128(_mm_or_si128(in, nextin), v_ffff0000), v_0000);
+    const uint32_t saturation_bitmask = static_cast<uint32_t>(_mm_movemask_epi8(saturation_bytemask));
+
+    // Check if no bits set above 16th
+    if (saturation_bitmask == 0xffff) {
+      // Pack UTF-32 to UTF-16
+      __m128i utf16_packed = _mm_packus_epi32(in, nextin);
+
+      const __m128i v_f800 = _mm_set1_epi16((uint16_t)0xf800);
+      const __m128i v_d800 = _mm_set1_epi16((uint16_t)0xd800);
+      const __m128i forbidden_bytemask = _mm_cmpeq_epi16(_mm_and_si128(utf16_packed, v_f800), v_d800);
+      if (static_cast<uint32_t>(_mm_movemask_epi8(forbidden_bytemask)) != 0) {
+        return std::make_pair(result(error_code::SURROGATE, buf - start), utf16_output);
+      }
+
+      if (big_endian) {
+        const __m128i swap = _mm_setr_epi8(1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14);
+        utf16_packed = _mm_shuffle_epi8(utf16_packed, swap);
+      }
+
+      _mm_storeu_si128((__m128i*)utf16_output, utf16_packed);
+      utf16_output += 8;
+      buf += 8;
+    } else {
+      size_t forward = 7;
+      size_t k = 0;
+      if(size_t(end - buf) < forward + 1) { forward = size_t(end - buf - 1);}
+      for(; k < forward; k++) {
+        uint32_t word = buf[k];
+        if((word & 0xFFFF0000)==0) {
+          // will not generate a surrogate pair
+          if (word >= 0xD800 && word <= 0xDFFF) { return std::make_pair(result(error_code::SURROGATE, buf - start + k), utf16_output); }
+          *utf16_output++ = big_endian ? char16_t((uint16_t(word) >> 8) | (uint16_t(word) << 8)) : char16_t(word);
+        } else {
+          // will generate a surrogate pair
+          if (word > 0x10FFFF) { return std::make_pair(result(error_code::TOO_LARGE, buf - start + k), utf16_output); }
+          word -= 0x10000;
+          uint16_t high_surrogate = uint16_t(0xD800 + (word >> 10));
+          uint16_t low_surrogate = uint16_t(0xDC00 + (word & 0x3FF));
+          if (big_endian) {
+            high_surrogate = uint16_t((high_surrogate >> 8) | (high_surrogate << 8));
+            low_surrogate = uint16_t((low_surrogate >> 8) | (low_surrogate << 8));
+          }
+          *utf16_output++ = char16_t(high_surrogate);
+          *utf16_output++ = char16_t(low_surrogate);
+        }
+      }
+      buf += k;
+    }
+  }
+
+  return std::make_pair(result(error_code::SUCCESS, buf - start), utf16_output);
+}
+/* end file src/westmere/sse_convert_utf32_to_utf16.cpp */
+
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/buf_block_reader.h
+/* begin file src/generic/buf_block_reader.h */
+namespace simdutf {
+namespace westmere {
+namespace {
+
+// Walks through a buffer in block-sized increments, loading the last part with spaces
+template<size_t STEP_SIZE>
+struct buf_block_reader {
+public:
+  simdutf_really_inline buf_block_reader(const uint8_t *_buf, size_t _len);
+  simdutf_really_inline size_t block_index();
+  simdutf_really_inline bool has_full_block() const;
+  simdutf_really_inline const uint8_t *full_block() const;
+  /**
+   * Get the last block, padded with spaces.
+   *
+   * There will always be a last block, with at least 1 byte, unless len == 0 (in which case this
+   * function fills the buffer with spaces and returns 0. In particular, if len == STEP_SIZE there
+   * will be 0 full_blocks and 1 remainder block with STEP_SIZE bytes and no spaces for padding.
+   *
+   * @return the number of effective characters in the last block.
+   */
+  simdutf_really_inline size_t get_remainder(uint8_t *dst) const;
+  simdutf_really_inline void advance();
+private:
+  const uint8_t *buf;
+  const size_t len;
+  const size_t lenminusstep;
+  size_t idx;
+};
+
+// Routines to print masks and text for debugging bitmask operations
+simdutf_unused static char * format_input_text_64(const uint8_t *text) {
+  static char *buf = reinterpret_cast<char*>(malloc(sizeof(simd8x64<uint8_t>) + 1));
+  for (size_t i=0; i<sizeof(simd8x64<uint8_t>); i++) {
+    buf[i] = int8_t(text[i]) < ' ' ? '_' : int8_t(text[i]);
+  }
+  buf[sizeof(simd8x64<uint8_t>)] = '\0';
+  return buf;
+}
+
+// Routines to print masks and text for debugging bitmask operations
+simdutf_unused static char * format_input_text(const simd8x64<uint8_t>& in) {
+  static char *buf = reinterpret_cast<char*>(malloc(sizeof(simd8x64<uint8_t>) + 1));
+  in.store(reinterpret_cast<uint8_t*>(buf));
+  for (size_t i=0; i<sizeof(simd8x64<uint8_t>); i++) {
+    if (buf[i] < ' ') { buf[i] = '_'; }
+  }
+  buf[sizeof(simd8x64<uint8_t>)] = '\0';
+  return buf;
+}
+
+simdutf_unused static char * format_mask(uint64_t mask) {
+  static char *buf = reinterpret_cast<char*>(malloc(64 + 1));
+  for (size_t i=0; i<64; i++) {
+    buf[i] = (mask & (size_t(1) << i)) ? 'X' : ' ';
+  }
+  buf[64] = '\0';
+  return buf;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline buf_block_reader<STEP_SIZE>::buf_block_reader(const uint8_t *_buf, size_t _len) : buf{_buf}, len{_len}, lenminusstep{len < STEP_SIZE ? 0 : len - STEP_SIZE}, idx{0} {}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline size_t buf_block_reader<STEP_SIZE>::block_index() { return idx; }
+
+template<size_t STEP_SIZE>
+simdutf_really_inline bool buf_block_reader<STEP_SIZE>::has_full_block() const {
+  return idx < lenminusstep;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline const uint8_t *buf_block_reader<STEP_SIZE>::full_block() const {
+  return &buf[idx];
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline size_t buf_block_reader<STEP_SIZE>::get_remainder(uint8_t *dst) const {
+  if(len == idx) { return 0; } // memcpy(dst, null, 0) will trigger an error with some sanitizers
+  std::memset(dst, 0x20, STEP_SIZE); // std::memset STEP_SIZE because it's more efficient to write out 8 or 16 bytes at once.
+  std::memcpy(dst, buf + idx, len - idx);
+  return len - idx;
+}
+
+template<size_t STEP_SIZE>
+simdutf_really_inline void buf_block_reader<STEP_SIZE>::advance() {
+  idx += STEP_SIZE;
+}
+
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/buf_block_reader.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_validation/utf8_lookup4_algorithm.h
+/* begin file src/generic/utf8_validation/utf8_lookup4_algorithm.h */
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace utf8_validation {
+
+using namespace simd;
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+  //
+  // Return nonzero if there are incomplete multibyte characters at the end of the block:
+  // e.g. if there is a 4-byte character, but it's 3 bytes from the end.
+  //
+  simdutf_really_inline simd8<uint8_t> is_incomplete(const simd8<uint8_t> input) {
+    // If the previous input's last 3 bytes match this, they're too short (they ended at EOF):
+    // ... 1111____ 111_____ 11______
+    static const uint8_t max_array[32] = {
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 255, 255, 255,
+      255, 255, 255, 255, 255, 0b11110000u-1, 0b11100000u-1, 0b11000000u-1
+    };
+    const simd8<uint8_t> max_value(&max_array[sizeof(max_array)-sizeof(simd8<uint8_t>)]);
+    return input.gt_bits(max_value);
+  }
+
+  struct utf8_checker {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+    // The last input we received
+    simd8<uint8_t> prev_input_block;
+    // Whether the last input we received was incomplete (used for ASCII fast path)
+    simd8<uint8_t> prev_incomplete;
+
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+    // The only problem that can happen at EOF is that a multibyte character is too short
+    // or a byte value too large in the last bytes: check_special_cases only checks for bytes
+    // too large in the first of two bytes.
+    simdutf_really_inline void check_eof() {
+      // If the previous block had incomplete UTF-8 characters at the end, an ASCII block can't
+      // possibly finish them.
+      this->error |= this->prev_incomplete;
+    }
+
+    simdutf_really_inline void check_next_input(const simd8x64<uint8_t>& input) {
+      if(simdutf_likely(is_ascii(input))) {
+        this->error |= this->prev_incomplete;
+      } else {
+        // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+        static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+            "We support either two or four chunks per 64-byte block.");
+        if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+          this->check_utf8_bytes(input.chunks[0], this->prev_input_block);
+          this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+        } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+          this->check_utf8_bytes(input.chunks[0], this->prev_input_block);
+          this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+          this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+        }
+        this->prev_incomplete = is_incomplete(input.chunks[simd8x64<uint8_t>::NUM_CHUNKS-1]);
+        this->prev_input_block = input.chunks[simd8x64<uint8_t>::NUM_CHUNKS-1];
+
+      }
+    }
+
+    // do not forget to call check_eof!
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // namespace utf8_validation
+
+using utf8_validation::utf8_checker;
+
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/utf8_validation/utf8_lookup4_algorithm.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_validation/utf8_validator.h
+/* begin file src/generic/utf8_validation/utf8_validator.h */
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace utf8_validation {
+
+/**
+ * Validates that the string is actual UTF-8.
+ */
+template<class checker>
+bool generic_validate_utf8(const uint8_t * input, size_t length) {
+    checker c{};
+    buf_block_reader<64> reader(input, length);
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      c.check_next_input(in);
+      reader.advance();
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    c.check_next_input(in);
+    reader.advance();
+    c.check_eof();
+    return !c.errors();
+}
+
+bool generic_validate_utf8(const char * input, size_t length) {
+  return generic_validate_utf8<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+/**
+ * Validates that the string is actual UTF-8 and stops on errors.
+ */
+template<class checker>
+result generic_validate_utf8_with_errors(const uint8_t * input, size_t length) {
+    checker c{};
+    buf_block_reader<64> reader(input, length);
+    size_t count{0};
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      c.check_next_input(in);
+      if(c.errors()) {
+        if (count != 0) { count--; } // Sometimes the error is only detected in the next chunk
+        result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+        res.count += count;
+        return res;
+      }
+      reader.advance();
+      count += 64;
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    c.check_next_input(in);
+    reader.advance();
+    c.check_eof();
+    if (c.errors()) {
+      result res = scalar::utf8::rewind_and_validate_with_errors(reinterpret_cast<const char*>(input) + count, length - count);
+      res.count += count;
+      return res;
+    } else {
+      return result(error_code::SUCCESS, length);
+    }
+}
+
+result generic_validate_utf8_with_errors(const char * input, size_t length) {
+  return generic_validate_utf8_with_errors<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+template<class checker>
+bool generic_validate_ascii(const uint8_t * input, size_t length) {
+    buf_block_reader<64> reader(input, length);
+    uint8_t blocks[64]{};
+    simd::simd8x64<uint8_t> running_or(blocks);
+    while (reader.has_full_block()) {
+      simd::simd8x64<uint8_t> in(reader.full_block());
+      running_or |= in;
+      reader.advance();
+    }
+    uint8_t block[64]{};
+    reader.get_remainder(block);
+    simd::simd8x64<uint8_t> in(block);
+    running_or |= in;
+    return running_or.is_ascii();
+}
+
+bool generic_validate_ascii(const char * input, size_t length) {
+  return generic_validate_ascii<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+template<class checker>
+result generic_validate_ascii_with_errors(const uint8_t * input, size_t length) {
+  buf_block_reader<64> reader(input, length);
+  size_t count{0};
+  while (reader.has_full_block()) {
+    simd::simd8x64<uint8_t> in(reader.full_block());
+    if (!in.is_ascii()) {
+      result res = scalar::ascii::validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+      return result(res.error, count + res.count);
+    }
+    reader.advance();
+
+    count += 64;
+  }
+  uint8_t block[64]{};
+  reader.get_remainder(block);
+  simd::simd8x64<uint8_t> in(block);
+  if (!in.is_ascii()) {
+    result res = scalar::ascii::validate_with_errors(reinterpret_cast<const char*>(input + count), length - count);
+    return result(res.error, count + res.count);
+  } else {
+    return result(error_code::SUCCESS, length);
+  }
+}
+
+result generic_validate_ascii_with_errors(const char * input, size_t length) {
+  return generic_validate_ascii_with_errors<utf8_checker>(reinterpret_cast<const uint8_t *>(input),length);
+}
+
+} // namespace utf8_validation
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/utf8_validation/utf8_validator.h */
+// transcoding from UTF-8 to UTF-16
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf16/valid_utf8_to_utf16.h
+/* begin file src/generic/utf8_to_utf16/valid_utf8_to_utf16.h */
+
+
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace utf8_to_utf16 {
+
+using namespace simd;
+
+template <endianness endian>
+simdutf_warn_unused size_t convert_valid(const char* input, size_t size,
+    char16_t* utf16_output) noexcept {
+  // The implementation is not specific to haswell and should be moved to the generic directory.
+  size_t pos = 0;
+  char16_t* start{utf16_output};
+  const size_t safety_margin = 16; // to avoid overruns!
+  while(pos + 64 + safety_margin <= size) {
+    // this loop could be unrolled further. For example, we could process the mask
+    // far more than 64 bytes.
+    simd8x64<int8_t> in(reinterpret_cast<const int8_t *>(input + pos));
+    if(in.is_ascii()) {
+      in.store_ascii_as_utf16<endian>(utf16_output);
+      utf16_output += 64;
+      pos += 64;
+    } else {
+      // Slow path. We hope that the compiler will recognize that this is a slow path.
+      // Anything that is not a continuation mask is a 'leading byte', that is, the
+      // start of a new code point.
+      uint64_t utf8_continuation_mask = in.lt(-65 + 1);
+      // -65 is 0b10111111 in two-complement's, so largest possible continuation byte
+      uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+      // The *start* of code points is not so useful, rather, we want the *end* of code points.
+      uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+      // We process in blocks of up to 12 bytes except possibly
+      // for fast paths which may process up to 16 bytes. For the
+      // slow path to work, we should have at least 12 input bytes left.
+      size_t max_starting_point = (pos + 64) - 12;
+      // Next loop is going to run at least five times when using solely
+      // the slow/regular path, and at least four times if there are fast paths.
+      while(pos < max_starting_point) {
+        // Performance note: our ability to compute 'consumed' and
+        // then shift and recompute is critical. If there is a
+        // latency of, say, 4 cycles on getting 'consumed', then
+        // the inner loop might have a total latency of about 6 cycles.
+        // Yet we process between 6 to 12 inputs bytes, thus we get
+        // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+        // for this section of the code. Hence, there is a limit
+        // to how much we can further increase this latency before
+        // it seriously harms performance.
+        //
+        // Thus we may allow convert_masked_utf8_to_utf16 to process
+        // more bytes at a time under a fast-path mode where 16 bytes
+        // are consumed at once (e.g., when encountering ASCII).
+        size_t consumed = convert_masked_utf8_to_utf16<endian>(input + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+        pos += consumed;
+        utf8_end_of_code_point_mask >>= consumed;
+      }
+      // At this point there may remain between 0 and 12 bytes in the
+      // 64-byte block.These bytes will be processed again. So we have an
+      // 80% efficiency (in the worst case). In practice we expect an
+      // 85% to 90% efficiency.
+    }
+  }
+  utf16_output += scalar::utf8_to_utf16::convert_valid<endian>(input + pos, size - pos, utf16_output);
+  return utf16_output - start;
+}
+
+} // namespace utf8_to_utf16
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf16/valid_utf8_to_utf16.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf16/utf8_to_utf16.h
+/* begin file src/generic/utf8_to_utf16/utf8_to_utf16.h */
+
+
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace utf8_to_utf16 {
+using namespace simd;
+
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+
+  struct validating_transcoder {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+
+    validating_transcoder() : error(uint8_t(0)) {}
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+
+    template <endianness endian>
+    simdutf_really_inline size_t convert(const char* in, size_t size, char16_t* utf16_output) {
+      size_t pos = 0;
+      char16_t* start{utf16_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf16<endian>(utf16_output);
+          utf16_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf16<endian>(in + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) { return 0; }
+      if(pos < size) {
+        size_t howmany  = scalar::utf8_to_utf16::convert<endian>(in + pos, size - pos, utf16_output);
+        if(howmany == 0) { return 0; }
+        utf16_output += howmany;
+      }
+      return utf16_output - start;
+    }
+
+    template <endianness endian>
+    simdutf_really_inline result convert_with_errors(const char* in, size_t size, char16_t* utf16_output) {
+      size_t pos = 0;
+      char16_t* start{utf16_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf16<endian>(utf16_output);
+          utf16_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          if (errors()) {
+            result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+            res.count += pos;
+            return res;
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf16<endian>(in + pos,
+                            utf8_end_of_code_point_mask, utf16_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) {
+        result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+        res.count += pos;
+        return res;
+      }
+      if(pos < size) {
+        result res = scalar::utf8_to_utf16::rewind_and_convert_with_errors<endian>(in + pos, size - pos, utf16_output);
+        if (res.error) {    // In case of error, we want the error position
+          res.count += pos;
+          return res;
+        } else {    // In case of success, we want the number of word written
+          utf16_output += res.count;
+        }
+      }
+      return result(error_code::SUCCESS, utf16_output - start);
+    }
+
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // utf8_to_utf16 namespace
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf16/utf8_to_utf16.h */
+// transcoding from UTF-8 to UTF-32
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf32/valid_utf8_to_utf32.h
+/* begin file src/generic/utf8_to_utf32/valid_utf8_to_utf32.h */
+
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace utf8_to_utf32 {
+
+using namespace simd;
+
+
+simdutf_warn_unused size_t convert_valid(const char* input, size_t size,
+    char32_t* utf32_output) noexcept {
+  size_t pos = 0;
+  char32_t* start{utf32_output};
+  const size_t safety_margin = 16; // to avoid overruns!
+  while(pos + 64 + safety_margin <= size) {
+    simd8x64<int8_t> in(reinterpret_cast<const int8_t *>(input + pos));
+    if(in.is_ascii()) {
+      in.store_ascii_as_utf32(utf32_output);
+      utf32_output += 64;
+      pos += 64;
+    } else {
+    // -65 is 0b10111111 in two-complement's, so largest possible continuation byte
+    uint64_t utf8_continuation_mask = in.lt(-65 + 1);
+    uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+    uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+    size_t max_starting_point = (pos + 64) - 12;
+    while(pos < max_starting_point) {
+      size_t consumed = convert_masked_utf8_to_utf32(input + pos,
+                          utf8_end_of_code_point_mask, utf32_output);
+      pos += consumed;
+      utf8_end_of_code_point_mask >>= consumed;
+      }
+    }
+  }
+  utf32_output += scalar::utf8_to_utf32::convert_valid(input + pos, size - pos, utf32_output);
+  return utf32_output - start;
+}
+
+
+} // namespace utf8_to_utf32
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf32/valid_utf8_to_utf32.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8_to_utf32/utf8_to_utf32.h
+/* begin file src/generic/utf8_to_utf32/utf8_to_utf32.h */
+
+
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace utf8_to_utf32 {
+using namespace simd;
+
+
+  simdutf_really_inline simd8<uint8_t> check_special_cases(const simd8<uint8_t> input, const simd8<uint8_t> prev1) {
+// Bit 0 = Too Short (lead byte/ASCII followed by lead byte/ASCII)
+// Bit 1 = Too Long (ASCII followed by continuation)
+// Bit 2 = Overlong 3-byte
+// Bit 4 = Surrogate
+// Bit 5 = Overlong 2-byte
+// Bit 7 = Two Continuations
+    constexpr const uint8_t TOO_SHORT   = 1<<0; // 11______ 0_______
+                                                // 11______ 11______
+    constexpr const uint8_t TOO_LONG    = 1<<1; // 0_______ 10______
+    constexpr const uint8_t OVERLONG_3  = 1<<2; // 11100000 100_____
+    constexpr const uint8_t SURROGATE   = 1<<4; // 11101101 101_____
+    constexpr const uint8_t OVERLONG_2  = 1<<5; // 1100000_ 10______
+    constexpr const uint8_t TWO_CONTS   = 1<<7; // 10______ 10______
+    constexpr const uint8_t TOO_LARGE   = 1<<3; // 11110100 1001____
+                                                // 11110100 101_____
+                                                // 11110101 1001____
+                                                // 11110101 101_____
+                                                // 1111011_ 1001____
+                                                // 1111011_ 101_____
+                                                // 11111___ 1001____
+                                                // 11111___ 101_____
+    constexpr const uint8_t TOO_LARGE_1000 = 1<<6;
+                                                // 11110101 1000____
+                                                // 1111011_ 1000____
+                                                // 11111___ 1000____
+    constexpr const uint8_t OVERLONG_4  = 1<<6; // 11110000 1000____
+
+    const simd8<uint8_t> byte_1_high = prev1.shr<4>().lookup_16<uint8_t>(
+      // 0_______ ________ <ASCII in byte 1>
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      TOO_LONG, TOO_LONG, TOO_LONG, TOO_LONG,
+      // 10______ ________ <continuation in byte 1>
+      TWO_CONTS, TWO_CONTS, TWO_CONTS, TWO_CONTS,
+      // 1100____ ________ <two byte lead in byte 1>
+      TOO_SHORT | OVERLONG_2,
+      // 1101____ ________ <two byte lead in byte 1>
+      TOO_SHORT,
+      // 1110____ ________ <three byte lead in byte 1>
+      TOO_SHORT | OVERLONG_3 | SURROGATE,
+      // 1111____ ________ <four+ byte lead in byte 1>
+      TOO_SHORT | TOO_LARGE | TOO_LARGE_1000 | OVERLONG_4
+    );
+    constexpr const uint8_t CARRY = TOO_SHORT | TOO_LONG | TWO_CONTS; // These all have ____ in byte 1 .
+    const simd8<uint8_t> byte_1_low = (prev1 & 0x0F).lookup_16<uint8_t>(
+      // ____0000 ________
+      CARRY | OVERLONG_3 | OVERLONG_2 | OVERLONG_4,
+      // ____0001 ________
+      CARRY | OVERLONG_2,
+      // ____001_ ________
+      CARRY,
+      CARRY,
+
+      // ____0100 ________
+      CARRY | TOO_LARGE,
+      // ____0101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____011_ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+
+      // ____1___ ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      // ____1101 ________
+      CARRY | TOO_LARGE | TOO_LARGE_1000 | SURROGATE,
+      CARRY | TOO_LARGE | TOO_LARGE_1000,
+      CARRY | TOO_LARGE | TOO_LARGE_1000
+    );
+    const simd8<uint8_t> byte_2_high = input.shr<4>().lookup_16<uint8_t>(
+      // ________ 0_______ <ASCII in byte 2>
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT,
+
+      // ________ 1000____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE_1000 | OVERLONG_4,
+      // ________ 1001____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | OVERLONG_3 | TOO_LARGE,
+      // ________ 101_____
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+      TOO_LONG | OVERLONG_2 | TWO_CONTS | SURROGATE  | TOO_LARGE,
+
+      // ________ 11______
+      TOO_SHORT, TOO_SHORT, TOO_SHORT, TOO_SHORT
+    );
+    return (byte_1_high & byte_1_low & byte_2_high);
+  }
+  simdutf_really_inline simd8<uint8_t> check_multibyte_lengths(const simd8<uint8_t> input,
+      const simd8<uint8_t> prev_input, const simd8<uint8_t> sc) {
+    simd8<uint8_t> prev2 = input.prev<2>(prev_input);
+    simd8<uint8_t> prev3 = input.prev<3>(prev_input);
+    simd8<uint8_t> must23 = simd8<uint8_t>(must_be_2_3_continuation(prev2, prev3));
+    simd8<uint8_t> must23_80 = must23 & uint8_t(0x80);
+    return must23_80 ^ sc;
+  }
+
+
+  struct validating_transcoder {
+    // If this is nonzero, there has been a UTF-8 error.
+    simd8<uint8_t> error;
+
+    validating_transcoder() : error(uint8_t(0)) {}
+    //
+    // Check whether the current bytes are valid UTF-8.
+    //
+    simdutf_really_inline void check_utf8_bytes(const simd8<uint8_t> input, const simd8<uint8_t> prev_input) {
+      // Flip prev1...prev3 so we can easily determine if they are 2+, 3+ or 4+ lead bytes
+      // (2, 3, 4-byte leads become large positive numbers instead of small negative numbers)
+      simd8<uint8_t> prev1 = input.prev<1>(prev_input);
+      simd8<uint8_t> sc = check_special_cases(input, prev1);
+      this->error |= check_multibyte_lengths(input, prev_input, sc);
+    }
+
+
+
+    simdutf_really_inline size_t convert(const char* in, size_t size, char32_t* utf32_output) {
+      size_t pos = 0;
+      char32_t* start{utf32_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf32(utf32_output);
+          utf32_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf32(in + pos,
+                            utf8_end_of_code_point_mask, utf32_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) { return 0; }
+      if(pos < size) {
+        size_t howmany  = scalar::utf8_to_utf32::convert(in + pos, size - pos, utf32_output);
+        if(howmany == 0) { return 0; }
+        utf32_output += howmany;
+      }
+      return utf32_output - start;
+    }
+
+    simdutf_really_inline result convert_with_errors(const char* in, size_t size, char32_t* utf32_output) {
+      size_t pos = 0;
+      char32_t* start{utf32_output};
+      const size_t safety_margin = 16; // to avoid overruns!
+      while(pos + 64 + safety_margin <= size) {
+        simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+        if(input.is_ascii()) {
+          input.store_ascii_as_utf32(utf32_output);
+          utf32_output += 64;
+          pos += 64;
+        } else {
+          // you might think that a for-loop would work, but under Visual Studio, it is not good enough.
+          static_assert((simd8x64<uint8_t>::NUM_CHUNKS == 2) || (simd8x64<uint8_t>::NUM_CHUNKS == 4),
+              "We support either two or four chunks per 64-byte block.");
+          auto zero = simd8<uint8_t>{uint8_t(0)};
+          if(simd8x64<uint8_t>::NUM_CHUNKS == 2) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+          } else if(simd8x64<uint8_t>::NUM_CHUNKS == 4) {
+            this->check_utf8_bytes(input.chunks[0], zero);
+            this->check_utf8_bytes(input.chunks[1], input.chunks[0]);
+            this->check_utf8_bytes(input.chunks[2], input.chunks[1]);
+            this->check_utf8_bytes(input.chunks[3], input.chunks[2]);
+          }
+          if (errors()) {
+            result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+            res.count += pos;
+            return res;
+          }
+          uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+          uint64_t utf8_leading_mask = ~utf8_continuation_mask;
+          uint64_t utf8_end_of_code_point_mask = utf8_leading_mask>>1;
+          // We process in blocks of up to 12 bytes except possibly
+          // for fast paths which may process up to 16 bytes. For the
+          // slow path to work, we should have at least 12 input bytes left.
+          size_t max_starting_point = (pos + 64) - 12;
+          // Next loop is going to run at least five times.
+          while(pos < max_starting_point) {
+            // Performance note: our ability to compute 'consumed' and
+            // then shift and recompute is critical. If there is a
+            // latency of, say, 4 cycles on getting 'consumed', then
+            // the inner loop might have a total latency of about 6 cycles.
+            // Yet we process between 6 to 12 inputs bytes, thus we get
+            // a speed limit between 1 cycle/byte and 0.5 cycle/byte
+            // for this section of the code. Hence, there is a limit
+            // to how much we can further increase this latency before
+            // it seriously harms performance.
+            size_t consumed = convert_masked_utf8_to_utf32(in + pos,
+                            utf8_end_of_code_point_mask, utf32_output);
+            pos += consumed;
+            utf8_end_of_code_point_mask >>= consumed;
+          }
+          // At this point there may remain between 0 and 12 bytes in the
+          // 64-byte block.These bytes will be processed again. So we have an
+          // 80% efficiency (in the worst case). In practice we expect an
+          // 85% to 90% efficiency.
+        }
+      }
+      if(errors()) {
+        result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+        res.count += pos;
+        return res;
+      }
+      if(pos < size) {
+        result res = scalar::utf8_to_utf32::rewind_and_convert_with_errors(in + pos, size - pos, utf32_output);
+        if (res.error) {    // In case of error, we want the error position
+          res.count += pos;
+          return res;
+        } else {    // In case of success, we want the number of word written
+          utf32_output += res.count;
+        }
+      }
+      return result(error_code::SUCCESS, utf32_output - start);
+    }
+
+    simdutf_really_inline bool errors() const {
+      return this->error.any_bits_set_anywhere();
+    }
+
+  }; // struct utf8_checker
+} // utf8_to_utf32 namespace
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/utf8_to_utf32/utf8_to_utf32.h */
+// other functions
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf8.h
+/* begin file src/generic/utf8.h */
+
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace utf8 {
+
+using namespace simd;
+
+simdutf_really_inline size_t count_code_points(const char* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    for(;pos + 64 <= size; pos += 64) {
+      simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+      uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+      count += 64 - count_ones(utf8_continuation_mask);
+    }
+    return count + scalar::utf8::count_code_points(in + pos, size - pos);
+}
+
+
+simdutf_really_inline size_t utf16_length_from_utf8(const char* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 64 <= size; pos += 64) {
+      simd8x64<int8_t> input(reinterpret_cast<const int8_t *>(in + pos));
+      uint64_t utf8_continuation_mask = input.lt(-65 + 1);
+      // We count one word for anything that is not a continuation (so
+      // leading bytes).
+      count += 64 - count_ones(utf8_continuation_mask);
+      int64_t utf8_4byte = input.gteq_unsigned(240);
+      count += count_ones(utf8_4byte);
+    }
+    return count + scalar::utf8::utf16_length_from_utf8(in + pos, size - pos);
+}
+
+
+simdutf_really_inline size_t utf32_length_from_utf8(const char* in, size_t size) {
+    return count_code_points(in, size);
+}
+} // utf8 namespace
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/utf8.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=generic/utf16.h
+/* begin file src/generic/utf16.h */
+namespace simdutf {
+namespace westmere {
+namespace {
+namespace utf16 {
+
+template <endianness big_endian>
+simdutf_really_inline size_t count_code_points(const char16_t* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    for(;pos + 32 <= size; pos += 32) {
+      simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+      if (big_endian) input.swap_bytes();
+      uint64_t not_pair = input.not_in_range(0xDC00, 0xDFFF);
+      count += count_ones(not_pair) / 2;
+    }
+    return count + scalar::utf16::count_code_points<big_endian>(in + pos, size - pos);
+}
+
+template <endianness big_endian>
+simdutf_really_inline size_t utf8_length_from_utf16(const char16_t* in, size_t size) {
+    size_t pos = 0;
+    size_t count = 0;
+    // This algorithm could no doubt be improved!
+    for(;pos + 32 <= size; pos += 32) {
+      simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+      if (big_endian) input.swap_bytes();
+      uint64_t ascii_mask = input.lteq(0x7F);
+      uint64_t twobyte_mask = input.lteq(0x7FF);
+      uint64_t not_pair_mask = input.not_in_range(0xD800, 0xDFFF);
+
+      size_t ascii_count = count_ones(ascii_mask) / 2;
+      size_t twobyte_count = count_ones(twobyte_mask & ~ ascii_mask) / 2;
+      size_t threebyte_count = count_ones(not_pair_mask & ~ twobyte_mask) / 2;
+      size_t fourbyte_count = 32 - count_ones(not_pair_mask) / 2;
+      count += 2 * fourbyte_count + 3 * threebyte_count + 2 * twobyte_count + ascii_count;
+    }
+    return count + scalar::utf16::utf8_length_from_utf16<big_endian>(in + pos, size - pos);
+}
+
+template <endianness big_endian>
+simdutf_really_inline size_t utf32_length_from_utf16(const char16_t* in, size_t size) {
+    return count_code_points<big_endian>(in, size);
+}
+
+simdutf_really_inline void change_endianness_utf16(const char16_t* in, size_t size, char16_t* output) {
+  size_t pos = 0;
+
+  while (pos + 32 <= size) {
+    simd16x32<uint16_t> input(reinterpret_cast<const uint16_t *>(in + pos));
+    input.swap_bytes();
+    input.store(reinterpret_cast<uint16_t *>(output));
+    pos += 32;
+    output += 32;
+  }
+
+  scalar::utf16::change_endianness_utf16(in + pos, size - pos, output);
+}
+
+} // utf16
+} // unnamed namespace
+} // namespace westmere
+} // namespace simdutf
+/* end file src/generic/utf16.h */
+//
+// Implementation-specific overrides
+//
+
+namespace simdutf {
+namespace westmere {
+
+simdutf_warn_unused int implementation::detect_encodings(const char * input, size_t length) const noexcept {
+  // If there is a BOM, then we trust it.
+  auto bom_encoding = simdutf::BOM::check_bom(input, length);
+  if(bom_encoding != encoding_type::unspecified) { return bom_encoding; }
+  if (length % 2 == 0) {
+    return sse_detect_encodings<utf8_validation::utf8_checker>(input, length);
+  } else {
+    if (implementation::validate_utf8(input, length)) {
+      return simdutf::encoding_type::UTF8;
+    } else {
+      return simdutf::encoding_type::unspecified;
+    }
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf8(const char *buf, size_t len) const noexcept {
+  return westmere::utf8_validation::generic_validate_utf8(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_utf8_with_errors(const char *buf, size_t len) const noexcept {
+  return westmere::utf8_validation::generic_validate_utf8_with_errors(buf, len);
+}
+
+simdutf_warn_unused bool implementation::validate_ascii(const char *buf, size_t len) const noexcept {
+  return westmere::utf8_validation::generic_validate_ascii(buf, len);
+}
+
+simdutf_warn_unused result implementation::validate_ascii_with_errors(const char *buf, size_t len) const noexcept {
+  return westmere::utf8_validation::generic_validate_ascii_with_errors(buf,len);
+}
+
+simdutf_warn_unused bool implementation::validate_utf16le(const char16_t *buf, size_t len) const noexcept {
+  const char16_t* tail = sse_validate_utf16<endianness::LITTLE>(buf, len);
+  if (tail) {
+    return scalar::utf16::validate<endianness::LITTLE>(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf16be(const char16_t *buf, size_t len) const noexcept {
+  const char16_t* tail = sse_validate_utf16<endianness::BIG>(buf, len);
+  if (tail) {
+    return scalar::utf16::validate<endianness::BIG>(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept {
+  result res = sse_validate_utf16_with_errors<endianness::LITTLE>(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf16::validate_with_errors<endianness::LITTLE>(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept {
+  result res = sse_validate_utf16_with_errors<endianness::BIG>(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf16::validate_with_errors<endianness::BIG>(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused bool implementation::validate_utf32(const char32_t *buf, size_t len) const noexcept {
+  const char32_t* tail = sse_validate_utf32le(buf, len);
+  if (tail) {
+    return scalar::utf32::validate(tail, len - (tail - buf));
+  } else {
+    return false;
+  }
+}
+
+simdutf_warn_unused result implementation::validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept {
+  result res = sse_validate_utf32le_with_errors(buf, len);
+  if (res.count != len) {
+    result scalar_res = scalar::utf32::validate_with_errors(buf + res.count, len - res.count);
+    return result(scalar_res.error, res.count + scalar_res.count);
+  } else {
+    return res;
+  }
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16le(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf16be(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert<endianness::BIG>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16le_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf16be_with_errors(const char* buf, size_t len, char16_t* utf16_output) const noexcept {
+  utf8_to_utf16::validating_transcoder converter;
+  return converter.convert_with_errors<endianness::BIG>(buf, len, utf16_output);
+}
+
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16le(const char* input, size_t size,
+    char16_t* utf16_output) const noexcept {
+  return utf8_to_utf16::convert_valid<endianness::LITTLE>(input, size,  utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf16be(const char* input, size_t size,
+    char16_t* utf16_output) const noexcept {
+  return utf8_to_utf16::convert_valid<endianness::BIG>(input, size,  utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf8_to_utf32(const char* buf, size_t len, char32_t* utf32_output) const noexcept {
+  utf8_to_utf32::validating_transcoder converter;
+  return converter.convert(buf, len, utf32_output);
+}
+
+simdutf_warn_unused result implementation::convert_utf8_to_utf32_with_errors(const char* buf, size_t len, char32_t* utf32_output) const noexcept {
+  utf8_to_utf32::validating_transcoder converter;
+  return converter.convert_with_errors(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf8_to_utf32(const char* input, size_t size,
+    char32_t* utf32_output) const noexcept {
+  return utf8_to_utf32::convert_valid(input, size,  utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char16_t*, char*> ret = sse_convert_utf16_to_utf8<endianness::LITTLE>(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf8::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char16_t*, char*> ret = sse_convert_utf16_to_utf8<endianness::BIG>(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf8::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = westmere::sse_convert_utf16_to_utf8_with_errors<endianness::LITTLE>(buf, len, utf8_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf8::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf8_with_errors(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = westmere::sse_convert_utf16_to_utf8_with_errors<endianness::BIG>(buf, len, utf8_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf8::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf16le_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf8(const char16_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf16be_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  std::pair<const char32_t*, char*> ret = sse_convert_utf32_to_utf8(buf, len, utf8_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf8_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf8::convert(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf8_with_errors(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char*> ret = westmere::sse_convert_utf32_to_utf8_with_errors(buf, len, utf8_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf8::convert_with_errors(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf8_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::pair<const char16_t*, char32_t*> ret = sse_convert_utf16_to_utf32<endianness::LITTLE>(buf, len, utf32_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf32_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  std::pair<const char16_t*, char32_t*> ret = sse_convert_utf16_to_utf32<endianness::BIG>(buf, len, utf32_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf32_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf16_to_utf32::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf16le_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char32_t*> ret = westmere::sse_convert_utf16_to_utf32_with_errors<endianness::LITTLE>(buf, len, utf32_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf32_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf16be_to_utf32_with_errors(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char32_t*> ret = westmere::sse_convert_utf16_to_utf32_with_errors<endianness::BIG>(buf, len, utf32_output);
+  if (ret.first.error) { return ret.first; }  // Can return directly since scalar fallback already found correct ret.first.count
+  if (ret.first.count != len) { // All good so far, but not finished
+    result scalar_res = scalar::utf16_to_utf32::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf32_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf8(const char32_t* buf, size_t len, char* utf8_output) const noexcept {
+  return convert_utf32_to_utf8(buf, len, utf8_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  std::pair<const char32_t*, char16_t*> ret = sse_convert_utf32_to_utf16<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf16_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf16::convert<endianness::LITTLE>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused size_t implementation::convert_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  std::pair<const char32_t*, char16_t*> ret = sse_convert_utf32_to_utf16<endianness::BIG>(buf, len, utf16_output);
+  if (ret.first == nullptr) { return 0; }
+  size_t saved_bytes = ret.second - utf16_output;
+  if (ret.first != buf + len) {
+    const size_t scalar_saved_bytes = scalar::utf32_to_utf16::convert<endianness::BIG>(
+                                        ret.first, len - (ret.first - buf), ret.second);
+    if (scalar_saved_bytes == 0) { return 0; }
+    saved_bytes += scalar_saved_bytes;
+  }
+  return saved_bytes;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16le_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char16_t*> ret = westmere::sse_convert_utf32_to_utf16_with_errors<endianness::LITTLE>(buf, len, utf16_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf16::convert_with_errors<endianness::LITTLE>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf16_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused result implementation::convert_utf32_to_utf16be_with_errors(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  // ret.first.count is always the position in the buffer, not the number of words written even if finished
+  std::pair<result, char16_t*> ret = westmere::sse_convert_utf32_to_utf16_with_errors<endianness::BIG>(buf, len, utf16_output);
+  if (ret.first.count != len) {
+    result scalar_res = scalar::utf32_to_utf16::convert_with_errors<endianness::BIG>(
+                                        buf + ret.first.count, len - ret.first.count, ret.second);
+    if (scalar_res.error) {
+      scalar_res.count += ret.first.count;
+      return scalar_res;
+    } else {
+      ret.second += scalar_res.count;
+    }
+  }
+  ret.first.count = ret.second - utf16_output;   // Set count to the number of 8-bit words written
+  return ret.first;
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16le(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return convert_utf32_to_utf16le(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf32_to_utf16be(const char32_t* buf, size_t len, char16_t* utf16_output) const noexcept {
+  return convert_utf32_to_utf16be(buf, len, utf16_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16le_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return convert_utf16le_to_utf32(buf, len, utf32_output);
+}
+
+simdutf_warn_unused size_t implementation::convert_valid_utf16be_to_utf32(const char16_t* buf, size_t len, char32_t* utf32_output) const noexcept {
+  return convert_utf16be_to_utf32(buf, len, utf32_output);
+}
+
+void implementation::change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) const noexcept {
+  utf16::change_endianness_utf16(input, length, output);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::count_code_points<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::count_code_points<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::count_utf8(const char * input, size_t length) const noexcept {
+  return utf8::count_code_points(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf8_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf8_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf32_length_from_utf16<endianness::LITTLE>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept {
+  return utf16::utf32_length_from_utf16<endianness::BIG>(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf8(const char * input, size_t length) const noexcept {
+  return utf8::utf16_length_from_utf8(input, length);
+}
+
+simdutf_warn_unused size_t implementation::utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  const __m128i v_00000000 = _mm_setzero_si128();
+  const __m128i v_ffffff80 = _mm_set1_epi32((uint32_t)0xffffff80);
+  const __m128i v_fffff800 = _mm_set1_epi32((uint32_t)0xfffff800);
+  const __m128i v_ffff0000 = _mm_set1_epi32((uint32_t)0xffff0000);
+  size_t pos = 0;
+  size_t count = 0;
+  for(;pos + 4 <= length; pos += 4) {
+    __m128i in = _mm_loadu_si128((__m128i*)(input + pos));
+    const __m128i ascii_bytes_bytemask = _mm_cmpeq_epi32(_mm_and_si128(in, v_ffffff80), v_00000000);
+    const __m128i one_two_bytes_bytemask = _mm_cmpeq_epi32(_mm_and_si128(in, v_fffff800), v_00000000);
+    const __m128i two_bytes_bytemask = _mm_xor_si128(one_two_bytes_bytemask, ascii_bytes_bytemask);
+    const __m128i one_two_three_bytes_bytemask = _mm_cmpeq_epi32(_mm_and_si128(in, v_ffff0000), v_00000000);
+    const __m128i three_bytes_bytemask = _mm_xor_si128(one_two_three_bytes_bytemask, one_two_bytes_bytemask);
+    const uint16_t ascii_bytes_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(ascii_bytes_bytemask));
+    const uint16_t two_bytes_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(two_bytes_bytemask));
+    const uint16_t three_bytes_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(three_bytes_bytemask));
+
+    size_t ascii_count = count_ones(ascii_bytes_bitmask) / 4;
+    size_t two_bytes_count = count_ones(two_bytes_bitmask) / 4;
+    size_t three_bytes_count = count_ones(three_bytes_bitmask) / 4;
+    count += 16 - 3*ascii_count - 2*two_bytes_count - three_bytes_count;
+  }
+  return count + scalar::utf32::utf8_length_from_utf32(input + pos, length - pos);
+}
+
+simdutf_warn_unused size_t implementation::utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept {
+  const __m128i v_00000000 = _mm_setzero_si128();
+  const __m128i v_ffff0000 = _mm_set1_epi32((uint32_t)0xffff0000);
+  size_t pos = 0;
+  size_t count = 0;
+  for(;pos + 4 <= length; pos += 4) {
+    __m128i in = _mm_loadu_si128((__m128i*)(input + pos));
+    const __m128i surrogate_bytemask = _mm_cmpeq_epi32(_mm_and_si128(in, v_ffff0000), v_00000000);
+    const uint16_t surrogate_bitmask = static_cast<uint16_t>(_mm_movemask_epi8(surrogate_bytemask));
+    size_t surrogate_count = (16-count_ones(surrogate_bitmask))/4;
+    count += 4 + surrogate_count;
+  }
+  return count + scalar::utf32::utf16_length_from_utf32(input + pos, length - pos);
+}
+
+simdutf_warn_unused size_t implementation::utf32_length_from_utf8(const char * input, size_t length) const noexcept {
+  return utf8::utf32_length_from_utf8(input, length);
+}
+
+} // namespace westmere
+} // namespace simdutf
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/src, filename=simdutf/westmere/end.h
+/* begin file src/simdutf/westmere/end.h */
+SIMDUTF_UNTARGET_REGION
+/* end file src/simdutf/westmere/end.h */
+/* end file src/westmere/implementation.cpp */
+#endif
+
+SIMDUTF_POP_DISABLE_WARNINGS
+/* end file src/simdutf.cpp */
diff --git a/src/bun.js/bindings/simdutf.h b/src/bun.js/bindings/simdutf.h
new file mode 100644
index 000000000..515c511a7
--- /dev/null
+++ b/src/bun.js/bindings/simdutf.h
@@ -0,0 +1,2435 @@
+/* auto-generated on 2022-11-22 11:39:54 -0500. Do not edit! */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf.h
+/* begin file include/simdutf.h */
+#ifndef SIMDUTF_H
+#define SIMDUTF_H
+#include <cstring>
+
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/compiler_check.h
+/* begin file include/simdutf/compiler_check.h */
+#ifndef SIMDUTF_COMPILER_CHECK_H
+#define SIMDUTF_COMPILER_CHECK_H
+
+#ifndef __cplusplus
+#error simdutf requires a C++ compiler
+#endif
+
+#ifndef SIMDUTF_CPLUSPLUS
+#if defined(_MSVC_LANG) && !defined(__clang__)
+#define SIMDUTF_CPLUSPLUS (_MSC_VER == 1900 ? 201103L : _MSVC_LANG)
+#else
+#define SIMDUTF_CPLUSPLUS __cplusplus
+#endif
+#endif
+
+// C++ 17
+#if !defined(SIMDUTF_CPLUSPLUS17) && (SIMDUTF_CPLUSPLUS >= 201703L)
+#define SIMDUTF_CPLUSPLUS17 1
+#endif
+
+// C++ 14
+#if !defined(SIMDUTF_CPLUSPLUS14) && (SIMDUTF_CPLUSPLUS >= 201402L)
+#define SIMDUTF_CPLUSPLUS14 1
+#endif
+
+// C++ 11
+#if !defined(SIMDUTF_CPLUSPLUS11) && (SIMDUTF_CPLUSPLUS >= 201103L)
+#define SIMDUTF_CPLUSPLUS11 1
+#endif
+
+#ifndef SIMDUTF_CPLUSPLUS11
+#error simdutf requires a compiler compliant with the C++11 standard
+#endif
+
+#endif // SIMDUTF_COMPILER_CHECK_H
+/* end file include/simdutf/compiler_check.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/common_defs.h
+/* begin file include/simdutf/common_defs.h */
+#ifndef SIMDUTF_COMMON_DEFS_H
+#define SIMDUTF_COMMON_DEFS_H
+
+#include <cassert>
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/portability.h
+/* begin file include/simdutf/portability.h */
+#ifndef SIMDUTF_PORTABILITY_H
+#define SIMDUTF_PORTABILITY_H
+
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <cfloat>
+#include <cassert>
+#ifndef _WIN32
+// strcasecmp, strncasecmp
+#include <strings.h>
+#endif
+
+#ifdef _MSC_VER
+#define SIMDUTF_VISUAL_STUDIO 1
+/**
+ * We want to differentiate carefully between
+ * clang under visual studio and regular visual
+ * studio.
+ *
+ * Under clang for Windows, we enable:
+ *  * target pragmas so that part and only part of the
+ *     code gets compiled for advanced instructions.
+ *
+ */
+#ifdef __clang__
+// clang under visual studio
+#define SIMDUTF_CLANG_VISUAL_STUDIO 1
+#else
+// just regular visual studio (best guess)
+#define SIMDUTF_REGULAR_VISUAL_STUDIO 1
+#endif // __clang__
+#endif // _MSC_VER
+
+#ifdef SIMDUTF_REGULAR_VISUAL_STUDIO
+// https://en.wikipedia.org/wiki/C_alternative_tokens
+// This header should have no effect, except maybe
+// under Visual Studio.
+#include <iso646.h>
+#endif
+
+#if defined(__x86_64__) || defined(_M_AMD64)
+#define SIMDUTF_IS_X86_64 1
+#elif defined(__aarch64__) || defined(_M_ARM64)
+#define SIMDUTF_IS_ARM64 1
+#elif defined(__PPC64__) || defined(_M_PPC64)
+//#define SIMDUTF_IS_PPC64 1
+#pragma message("The simdutf library does yet support SIMD acceleration under\
+POWER processors. Please see https://github.com/lemire/simdutf/issues/51")
+#else
+// The simdutf library is designed
+// for 64-bit processors and it seems that you are not
+// compiling for a known 64-bit platform. Please
+// use a 64-bit target such as x64 or 64-bit ARM for best performance.
+#define SIMDUTF_IS_32BITS 1
+
+// We do not support 32-bit platforms, but it can be
+// handy to identify them.
+#if defined(_M_IX86) || defined(__i386__)
+#define SIMDUTF_IS_X86_32BITS 1
+#elif defined(__arm__) || defined(_M_ARM)
+#define SIMDUTF_IS_ARM_32BITS 1
+#elif defined(__PPC__) || defined(_M_PPC)
+#define SIMDUTF_IS_PPC_32BITS 1
+#endif
+
+#endif // defined(__x86_64__) || defined(_M_AMD64)
+
+#ifdef SIMDUTF_IS_32BITS
+#ifndef SIMDUTF_NO_PORTABILITY_WARNING
+#pragma message("The simdutf library is designed \
+for 64-bit processors and it seems that you are not \
+compiling for a known 64-bit platform. All fast kernels \
+will be disabled and performance may be poor. Please \
+use a 64-bit target such as x64, 64-bit ARM or 64-bit PPC.")
+#endif // SIMDUTF_NO_PORTABILITY_WARNING
+#endif // SIMDUTF_IS_32BITS
+
+// this is almost standard?
+#define SIMDUTF_STRINGIFY_IMPLEMENTATION_(a) #a
+#define SIMDUTF_STRINGIFY(a) SIMDUTF_STRINGIFY_IMPLEMENTATION_(a)
+
+// Our fast kernels require 64-bit systems.
+//
+// On 32-bit x86, we lack 64-bit popcnt, lzcnt, blsr instructions.
+// Furthermore, the number of SIMD registers is reduced.
+//
+// On 32-bit ARM, we would have smaller registers.
+//
+// The simdutf users should still have the fallback kernel. It is
+// slower, but it should run everywhere.
+
+//
+// Enable valid runtime implementations, and select SIMDUTF_BUILTIN_IMPLEMENTATION
+//
+
+// We are going to use runtime dispatch.
+#ifdef SIMDUTF_IS_X86_64
+#ifdef __clang__
+// clang does not have GCC push pop
+// warning: clang attribute push can't be used within a namespace in clang up
+// til 8.0 so SIMDUTF_TARGET_REGION and SIMDUTF_UNTARGET_REGION must be *outside* of a
+// namespace.
+#define SIMDUTF_TARGET_REGION(T)                                                       \
+  _Pragma(SIMDUTF_STRINGIFY(                                                           \
+      clang attribute push(__attribute__((target(T))), apply_to = function)))
+#define SIMDUTF_UNTARGET_REGION _Pragma("clang attribute pop")
+#elif defined(__GNUC__)
+// GCC is easier
+#define SIMDUTF_TARGET_REGION(T)                                                       \
+  _Pragma("GCC push_options") _Pragma(SIMDUTF_STRINGIFY(GCC target(T)))
+#define SIMDUTF_UNTARGET_REGION _Pragma("GCC pop_options")
+#endif // clang then gcc
+
+#endif // x86
+
+// Default target region macros don't do anything.
+#ifndef SIMDUTF_TARGET_REGION
+#define SIMDUTF_TARGET_REGION(T)
+#define SIMDUTF_UNTARGET_REGION
+#endif
+
+// Is threading enabled?
+#if defined(_REENTRANT) || defined(_MT)
+#ifndef SIMDUTF_THREADS_ENABLED
+#define SIMDUTF_THREADS_ENABLED
+#endif
+#endif
+
+// workaround for large stack sizes under -O0.
+// https://github.com/simdutf/simdutf/issues/691
+#ifdef __APPLE__
+#ifndef __OPTIMIZE__
+// Apple systems have small stack sizes in secondary threads.
+// Lack of compiler optimization may generate high stack usage.
+// Users may want to disable threads for safety, but only when
+// in debug mode which we detect by the fact that the __OPTIMIZE__
+// macro is not defined.
+#undef SIMDUTF_THREADS_ENABLED
+#endif
+#endif
+
+#ifdef SIMDUTF_VISUAL_STUDIO
+// This is one case where we do not distinguish between
+// regular visual studio and clang under visual studio.
+// clang under Windows has _stricmp (like visual studio) but not strcasecmp (as clang normally has)
+#define simdutf_strcasecmp _stricmp
+#define simdutf_strncasecmp _strnicmp
+#else
+// The strcasecmp, strncasecmp, and strcasestr functions do not work with multibyte strings (e.g. UTF-8).
+// So they are only useful for ASCII in our context.
+// https://www.gnu.org/software/libunistring/manual/libunistring.html#char-_002a-strings
+#define simdutf_strcasecmp strcasecmp
+#define simdutf_strncasecmp strncasecmp
+#endif
+
+#ifdef NDEBUG
+
+#ifdef SIMDUTF_VISUAL_STUDIO
+#define SIMDUTF_UNREACHABLE() __assume(0)
+#define SIMDUTF_ASSUME(COND) __assume(COND)
+#else
+#define SIMDUTF_UNREACHABLE() __builtin_unreachable();
+#define SIMDUTF_ASSUME(COND) do { if (!(COND)) __builtin_unreachable(); } while (0)
+#endif
+
+#else // NDEBUG
+
+#define SIMDUTF_UNREACHABLE() assert(0);
+#define SIMDUTF_ASSUME(COND) assert(COND)
+
+#endif
+
+#endif // SIMDUTF_PORTABILITY_H
+/* end file include/simdutf/portability.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/avx512.h
+/* begin file include/simdutf/avx512.h */
+#ifndef SIMDUTF_AVX512_H_
+#define SIMDUTF_AVX512_H_
+
+/*
+    It's possible to override AVX512 settings with cmake DCMAKE_CXX_FLAGS.
+
+    All preprocessor directives has form `SIMDUTF_HAS_AVX512{feature}`,
+    where a feature is a code name for extensions.
+
+    Please see the listing below to find which are supported.
+*/
+
+#ifndef SIMDUTF_HAS_AVX512F
+# if defined(__AVX512F__) && __AVX512F__ == 1
+#   define SIMDUTF_HAS_AVX512F 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512DQ
+# if defined(__AVX512DQ__) && __AVX512DQ__ == 1
+#   define SIMDUTF_HAS_AVX512DQ 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512IFMA
+# if defined(__AVX512IFMA__) && __AVX512IFMA__ == 1
+#   define SIMDUTF_HAS_AVX512IFMA 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512CD
+# if defined(__AVX512CD__) && __AVX512CD__ == 1
+#   define SIMDUTF_HAS_AVX512CD 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512BW
+# if defined(__AVX512BW__) && __AVX512BW__ == 1
+#   define SIMDUTF_HAS_AVX512BW 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512VL
+# if defined(__AVX512VL__) && __AVX512VL__ == 1
+#   define SIMDUTF_HAS_AVX512VL 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512VBMI
+# if defined(__AVX512VBMI__) && __AVX512VBMI__ == 1
+#   define SIMDUTF_HAS_AVX512VBMI 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512VBMI2
+# if defined(__AVX512VBMI2__) && __AVX512VBMI2__ == 1
+#   define SIMDUTF_HAS_AVX512VBMI2 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512VNNI
+# if defined(__AVX512VNNI__) && __AVX512VNNI__ == 1
+#   define SIMDUTF_HAS_AVX512VNNI 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512BITALG
+# if defined(__AVX512BITALG__) && __AVX512BITALG__ == 1
+#   define SIMDUTF_HAS_AVX512BITALG 1
+# endif
+#endif
+
+#ifndef SIMDUTF_HAS_AVX512VPOPCNTDQ
+# if defined(__AVX512VPOPCNTDQ__) && __AVX512VPOPCNTDQ__ == 1
+#   define SIMDUTF_HAS_AVX512VPOPCNTDQ 1
+# endif
+#endif
+
+#endif // SIMDUTF_AVX512_H_
+/* end file include/simdutf/avx512.h */
+
+
+#if defined(__GNUC__)
+  // Marks a block with a name so that MCA analysis can see it.
+  #define SIMDUTF_BEGIN_DEBUG_BLOCK(name) __asm volatile("# LLVM-MCA-BEGIN " #name);
+  #define SIMDUTF_END_DEBUG_BLOCK(name) __asm volatile("# LLVM-MCA-END " #name);
+  #define SIMDUTF_DEBUG_BLOCK(name, block) BEGIN_DEBUG_BLOCK(name); block; END_DEBUG_BLOCK(name);
+#else
+  #define SIMDUTF_BEGIN_DEBUG_BLOCK(name)
+  #define SIMDUTF_END_DEBUG_BLOCK(name)
+  #define SIMDUTF_DEBUG_BLOCK(name, block)
+#endif
+
+// Align to N-byte boundary
+#define SIMDUTF_ROUNDUP_N(a, n) (((a) + ((n)-1)) & ~((n)-1))
+#define SIMDUTF_ROUNDDOWN_N(a, n) ((a) & ~((n)-1))
+
+#define SIMDUTF_ISALIGNED_N(ptr, n) (((uintptr_t)(ptr) & ((n)-1)) == 0)
+
+#if defined(SIMDUTF_REGULAR_VISUAL_STUDIO)
+
+  #define simdutf_really_inline __forceinline
+  #define simdutf_never_inline __declspec(noinline)
+
+  #define simdutf_unused
+  #define simdutf_warn_unused
+
+  #ifndef simdutf_likely
+  #define simdutf_likely(x) x
+  #endif
+  #ifndef simdutf_unlikely
+  #define simdutf_unlikely(x) x
+  #endif
+
+  #define SIMDUTF_PUSH_DISABLE_WARNINGS __pragma(warning( push ))
+  #define SIMDUTF_PUSH_DISABLE_ALL_WARNINGS __pragma(warning( push, 0 ))
+  #define SIMDUTF_DISABLE_VS_WARNING(WARNING_NUMBER) __pragma(warning( disable : WARNING_NUMBER ))
+  // Get rid of Intellisense-only warnings (Code Analysis)
+  // Though __has_include is C++17, it is supported in Visual Studio 2017 or better (_MSC_VER>=1910).
+  #ifdef __has_include
+  #if __has_include(<CppCoreCheck\Warnings.h>)
+  #include <CppCoreCheck\Warnings.h>
+  #define SIMDUTF_DISABLE_UNDESIRED_WARNINGS SIMDUTF_DISABLE_VS_WARNING(ALL_CPPCORECHECK_WARNINGS)
+  #endif
+  #endif
+
+  #ifndef SIMDUTF_DISABLE_UNDESIRED_WARNINGS
+  #define SIMDUTF_DISABLE_UNDESIRED_WARNINGS
+  #endif
+
+  #define SIMDUTF_DISABLE_DEPRECATED_WARNING SIMDUTF_DISABLE_VS_WARNING(4996)
+  #define SIMDUTF_DISABLE_STRICT_OVERFLOW_WARNING
+  #define SIMDUTF_POP_DISABLE_WARNINGS __pragma(warning( pop ))
+
+#else // SIMDUTF_REGULAR_VISUAL_STUDIO
+
+  #define simdutf_really_inline inline __attribute__((always_inline))
+  #define simdutf_never_inline inline __attribute__((noinline))
+
+  #define simdutf_unused __attribute__((unused))
+  #define simdutf_warn_unused __attribute__((warn_unused_result))
+
+  #ifndef simdutf_likely
+  #define simdutf_likely(x) __builtin_expect(!!(x), 1)
+  #endif
+  #ifndef simdutf_unlikely
+  #define simdutf_unlikely(x) __builtin_expect(!!(x), 0)
+  #endif
+
+  #define SIMDUTF_PUSH_DISABLE_WARNINGS _Pragma("GCC diagnostic push")
+  // gcc doesn't seem to disable all warnings with all and extra, add warnings here as necessary
+  #define SIMDUTF_PUSH_DISABLE_ALL_WARNINGS SIMDUTF_PUSH_DISABLE_WARNINGS \
+    SIMDUTF_DISABLE_GCC_WARNING(-Weffc++) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wall) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wconversion) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wextra) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wattributes) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wimplicit-fallthrough) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wnon-virtual-dtor) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wreturn-type) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wshadow) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wunused-parameter) \
+    SIMDUTF_DISABLE_GCC_WARNING(-Wunused-variable)
+  #define SIMDUTF_PRAGMA(P) _Pragma(#P)
+  #define SIMDUTF_DISABLE_GCC_WARNING(WARNING) SIMDUTF_PRAGMA(GCC diagnostic ignored #WARNING)
+  #if defined(SIMDUTF_CLANG_VISUAL_STUDIO)
+  #define SIMDUTF_DISABLE_UNDESIRED_WARNINGS SIMDUTF_DISABLE_GCC_WARNING(-Wmicrosoft-include)
+  #else
+  #define SIMDUTF_DISABLE_UNDESIRED_WARNINGS
+  #endif
+  #define SIMDUTF_DISABLE_DEPRECATED_WARNING SIMDUTF_DISABLE_GCC_WARNING(-Wdeprecated-declarations)
+  #define SIMDUTF_DISABLE_STRICT_OVERFLOW_WARNING SIMDUTF_DISABLE_GCC_WARNING(-Wstrict-overflow)
+  #define SIMDUTF_POP_DISABLE_WARNINGS _Pragma("GCC diagnostic pop")
+
+
+
+#endif // MSC_VER
+
+#if defined(SIMDUTF_VISUAL_STUDIO)
+    /**
+     * It does not matter here whether you are using
+     * the regular visual studio or clang under visual
+     * studio.
+     */
+    #if SIMDUTF_USING_LIBRARY
+    #define SIMDUTF_DLLIMPORTEXPORT __declspec(dllimport)
+    #else
+    #define SIMDUTF_DLLIMPORTEXPORT __declspec(dllexport)
+    #endif
+#else
+    #define SIMDUTF_DLLIMPORTEXPORT
+#endif
+
+/// If EXPR is an error, returns it.
+#define SIMDUTF_TRY(EXPR) { auto _err = (EXPR); if (_err) { return _err; } }
+
+
+#endif // SIMDUTF_COMMON_DEFS_H
+/* end file include/simdutf/common_defs.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/encoding_types.h
+/* begin file include/simdutf/encoding_types.h */
+#include <string>
+
+namespace simdutf {
+
+enum encoding_type {
+        UTF8 = 1,       // BOM 0xef 0xbb 0xbf
+        UTF16_LE = 2,   // BOM 0xff 0xfe
+        UTF16_BE = 4,   // BOM 0xfe 0xff
+        UTF32_LE = 8,   // BOM 0xff 0xfe 0x00 0x00
+        UTF32_BE = 16,   // BOM 0x00 0x00 0xfe 0xff
+
+        unspecified = 0
+};
+
+enum endianness {
+        LITTLE,
+        BIG
+};
+
+std::string to_string(encoding_type bom);
+
+// Note that BOM for UTF8 is discouraged.
+namespace BOM {
+
+/**
+ * Checks for a BOM. If not, returns unspecified
+ * @param input         the string to process
+ * @param length        the length of the string in words
+ * @return the corresponding encoding
+ */
+
+encoding_type check_bom(const uint8_t* byte, size_t length);
+encoding_type check_bom(const char* byte, size_t length);
+/**
+ * Returns the size, in bytes, of the BOM for a given encoding type.
+ * Note that UTF8 BOM are discouraged.
+ * @param bom         the encoding type
+ * @return the size in bytes of the corresponding BOM
+ */
+size_t bom_byte_size(encoding_type bom);
+
+} // BOM namespace
+} // simdutf namespace
+/* end file include/simdutf/encoding_types.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/error.h
+/* begin file include/simdutf/error.h */
+#ifndef ERROR_H
+#define ERROR_H
+namespace simdutf {
+
+enum error_code {
+  SUCCESS = 0,
+  HEADER_BITS,  // Any byte must have fewer than 5 header bits.
+  TOO_SHORT,    // The leading byte must be followed by N-1 continuation bytes, where N is the UTF-8 character length
+                // This is also the error when the input is truncated.
+  TOO_LONG,     // The leading byte must not be a continuation byte.
+  OVERLONG,     // The decoded character must be above U+7F for two-byte characters, U+7FF for three-byte characters,
+                // and U+FFFF for four-byte characters.
+  TOO_LARGE,    // The decoded character must be less than or equal to U+10FFFF OR less than or equal than U+7F for ASCII.
+  SURROGATE,    // The decoded character must be not be in U+D800...DFFF (UTF-8 or UTF-32) OR
+                // a high surrogate must be followed by a low surrogate and a low surrogate must be preceded by a high surrogate (UTF-16)
+  OTHER         // Not related to validation/transcoding.
+};
+
+struct result {
+  error_code error;
+  size_t count;     // In case of error, indicates the position of the error. In case of success, indicates the number of words validated/written.
+
+  simdutf_really_inline result();
+
+  simdutf_really_inline result(error_code, size_t);
+};
+
+}
+#endif
+/* end file include/simdutf/error.h */
+
+SIMDUTF_PUSH_DISABLE_WARNINGS
+SIMDUTF_DISABLE_UNDESIRED_WARNINGS
+
+// Public API
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/simdutf_version.h
+/* begin file include/simdutf/simdutf_version.h */
+// /include/simdutf/simdutf_version.h automatically generated by release.py,
+// do not change by hand
+#ifndef SIMDUTF_SIMDUTF_VERSION_H
+#define SIMDUTF_SIMDUTF_VERSION_H
+
+/** The version of simdutf being used (major.minor.revision) */
+#define SIMDUTF_VERSION 1.0.1
+
+namespace simdutf {
+enum {
+  /**
+   * The major version (MAJOR.minor.revision) of simdutf being used.
+   */
+  SIMDUTF_VERSION_MAJOR = 1,
+  /**
+   * The minor version (major.MINOR.revision) of simdutf being used.
+   */
+  SIMDUTF_VERSION_MINOR = 0,
+  /**
+   * The revision (major.minor.REVISION) of simdutf being used.
+   */
+  SIMDUTF_VERSION_REVISION = 1
+};
+} // namespace simdutf
+
+#endif // SIMDUTF_SIMDUTF_VERSION_H
+/* end file include/simdutf/simdutf_version.h */
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/implementation.h
+/* begin file include/simdutf/implementation.h */
+#ifndef SIMDUTF_IMPLEMENTATION_H
+#define SIMDUTF_IMPLEMENTATION_H
+#include <string>
+#if !defined(SIMDUTF_NO_THREADS)
+#include <atomic>
+#endif
+#include <vector>
+#include <tuple>
+// dofile: invoked with prepath=/Users/jarred/Build/simdutf/include, filename=simdutf/internal/isadetection.h
+/* begin file include/simdutf/internal/isadetection.h */
+/* From
+https://github.com/endorno/pytorch/blob/master/torch/lib/TH/generic/simd/simd.h
+Highly modified.
+
+Copyright (c) 2016-     Facebook, Inc            (Adam Paszke)
+Copyright (c) 2014-     Facebook, Inc            (Soumith Chintala)
+Copyright (c) 2011-2014 Idiap Research Institute (Ronan Collobert)
+Copyright (c) 2012-2014 Deepmind Technologies    (Koray Kavukcuoglu)
+Copyright (c) 2011-2012 NEC Laboratories America (Koray Kavukcuoglu)
+Copyright (c) 2011-2013 NYU                      (Clement Farabet)
+Copyright (c) 2006-2010 NEC Laboratories America (Ronan Collobert, Leon Bottou,
+Iain Melvin, Jason Weston) Copyright (c) 2006      Idiap Research Institute
+(Samy Bengio) Copyright (c) 2001-2004 Idiap Research Institute (Ronan Collobert,
+Samy Bengio, Johnny Mariethoz)
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+3. Neither the names of Facebook, Deepmind Technologies, NYU, NEC Laboratories
+America and IDIAP Research Institute nor the names of its contributors may be
+   used to endorse or promote products derived from this software without
+   specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef SIMDutf_INTERNAL_ISADETECTION_H
+#define SIMDutf_INTERNAL_ISADETECTION_H
+
+#include <cstdint>
+#include <cstdlib>
+#if defined(_MSC_VER)
+#include <intrin.h>
+#elif defined(HAVE_GCC_GET_CPUID) && defined(USE_GCC_GET_CPUID)
+#include <cpuid.h>
+#endif
+
+namespace simdutf {
+namespace internal {
+
+enum instruction_set {
+  DEFAULT = 0x0,
+  NEON = 0x1,
+  AVX2 = 0x4,
+  SSE42 = 0x8,
+  PCLMULQDQ = 0x10,
+  BMI1 = 0x20,
+  BMI2 = 0x40,
+  ALTIVEC = 0x80,
+  AVX512F = 0x100,
+  AVX512DQ = 0x200,
+  AVX512IFMA = 0x400,
+  AVX512PF = 0x800,
+  AVX512ER = 0x1000,
+  AVX512CD = 0x2000,
+  AVX512BW = 0x4000,
+  AVX512VL = 0x8000,
+  AVX512VBMI2 = 0x10000
+};
+
+#if defined(__PPC64__)
+
+static inline uint32_t detect_supported_architectures() {
+  return instruction_set::ALTIVEC;
+}
+
+#elif defined(__arm__) || defined(__aarch64__) // incl. armel, armhf, arm64
+
+#if defined(__ARM_NEON)
+
+static inline uint32_t detect_supported_architectures() {
+  return instruction_set::NEON;
+}
+
+#else // ARM without NEON
+
+static inline uint32_t detect_supported_architectures() {
+  return instruction_set::DEFAULT;
+}
+
+#endif
+
+#elif defined(__x86_64__) || defined(_M_AMD64) // x64
+
+
+namespace {
+namespace cpuid_bit {
+    // Can be found on Intel ISA Reference for CPUID
+
+    // EAX = 0x01
+    constexpr uint32_t pclmulqdq = uint32_t(1) << 1; ///< @private bit  1 of ECX for EAX=0x1
+    constexpr uint32_t sse42 = uint32_t(1) << 20;    ///< @private bit 20 of ECX for EAX=0x1
+
+    // EAX = 0x7f (Structured Extended Feature Flags), ECX = 0x00 (Sub-leaf)
+    // See: "Table 3-8. Information Returned by CPUID Instruction"
+    namespace ebx {
+      constexpr uint32_t bmi1 = uint32_t(1) << 3;
+      constexpr uint32_t avx2 = uint32_t(1) << 5;
+      constexpr uint32_t bmi2 = uint32_t(1) << 8;
+      constexpr uint32_t avx512f = uint32_t(1) << 16;
+      constexpr uint32_t avx512dq = uint32_t(1) << 17;
+      constexpr uint32_t avx512ifma = uint32_t(1) << 21;
+      constexpr uint32_t avx512cd = uint32_t(1) << 28;
+      constexpr uint32_t avx512bw = uint32_t(1) << 30;
+      constexpr uint32_t avx512vl = uint32_t(1) << 31;
+    }
+
+    namespace ecx {
+      constexpr uint32_t avx512vbmi = uint32_t(1) << 1;
+      constexpr uint32_t avx512vbmi2 = uint32_t(1) << 6;
+      constexpr uint32_t avx512vnni = uint32_t(1) << 11;
+      constexpr uint32_t avx512bitalg = uint32_t(1) << 12;
+      constexpr uint32_t avx512vpopcnt = uint32_t(1) << 14;
+    }
+    namespace edx {
+      constexpr uint32_t avx512vp2intersect = uint32_t(1) << 8;
+    }
+  }
+}
+
+
+
+static inline void cpuid(uint32_t *eax, uint32_t *ebx, uint32_t *ecx,
+                         uint32_t *edx) {
+#if defined(_MSC_VER)
+  int cpu_info[4];
+  __cpuid(cpu_info, *eax);
+  *eax = cpu_info[0];
+  *ebx = cpu_info[1];
+  *ecx = cpu_info[2];
+  *edx = cpu_info[3];
+#elif defined(HAVE_GCC_GET_CPUID) && defined(USE_GCC_GET_CPUID)
+  uint32_t level = *eax;
+  __get_cpuid(level, eax, ebx, ecx, edx);
+#else
+  uint32_t a = *eax, b, c = *ecx, d;
+  asm volatile("cpuid\n\t" : "+a"(a), "=b"(b), "+c"(c), "=d"(d));
+  *eax = a;
+  *ebx = b;
+  *ecx = c;
+  *edx = d;
+#endif
+}
+
+static inline uint32_t detect_supported_architectures() {
+  uint32_t eax;
+  uint32_t ebx = 0;
+  uint32_t ecx = 0;
+  uint32_t edx = 0;
+  uint32_t host_isa = 0x0;
+
+  // EBX for EAX=0x1
+  eax = 0x1;
+  cpuid(&eax, &ebx, &ecx, &edx);
+
+  if (ecx & cpuid_bit::sse42) {
+    host_isa |= instruction_set::SSE42;
+  }
+
+  if (ecx & cpuid_bit::pclmulqdq) {
+    host_isa |= instruction_set::PCLMULQDQ;
+  }
+
+  // ECX for EAX=0x7
+  eax = 0x7;
+  ecx = 0x0; // Sub-leaf = 0
+  cpuid(&eax, &ebx, &ecx, &edx);
+  if (ebx & cpuid_bit::ebx::avx2) {
+    host_isa |= instruction_set::AVX2;
+  }
+  if (ebx & cpuid_bit::ebx::bmi1) {
+    host_isa |= instruction_set::BMI1;
+  }
+  if (ebx & cpuid_bit::ebx::bmi2) {
+    host_isa |= instruction_set::BMI2;
+  }
+  if (ebx & cpuid_bit::ebx::avx512f) {
+    host_isa |= instruction_set::AVX512F;
+  }
+  if (ebx & cpuid_bit::ebx::avx512bw) {
+    host_isa |= instruction_set::AVX512BW;
+  }
+  if (ebx & cpuid_bit::ebx::avx512cd) {
+    host_isa |= instruction_set::AVX512CD;
+  }
+  if (ebx & cpuid_bit::ebx::avx512dq) {
+    host_isa |= instruction_set::AVX512DQ;
+  }
+  if (ebx & cpuid_bit::ebx::avx512vl) {
+    host_isa |= instruction_set::AVX512VL;
+  }
+  if (ecx & cpuid_bit::ecx::avx512vbmi2) {
+    host_isa |= instruction_set::AVX512VBMI2;
+  }
+  return host_isa;
+}
+#else // fallback
+
+
+static inline uint32_t detect_supported_architectures() {
+  return instruction_set::DEFAULT;
+}
+
+
+#endif // end SIMD extension detection code
+
+} // namespace internal
+} // namespace simdutf
+
+#endif // SIMDutf_INTERNAL_ISADETECTION_H
+/* end file include/simdutf/internal/isadetection.h */
+
+
+namespace simdutf {
+
+/**
+ * Autodetect the encoding of the input, a single encoding is recommended.
+ * E.g., the function might return simdutf::encoding_type::UTF8, 
+ * simdutf::encoding_type::UTF16_LE, simdutf::encoding_type::UTF16_BE, or
+ * simdutf::encoding_type::UTF32_LE.
+ *
+ * @param input the string to analyze.
+ * @param length the length of the string in bytes.
+ * @return the detected encoding type
+ */
+simdutf_warn_unused simdutf::encoding_type autodetect_encoding(const char * input, size_t length) noexcept;
+simdutf_really_inline simdutf_warn_unused simdutf::encoding_type autodetect_encoding(const uint8_t * input, size_t length) noexcept {
+  return autodetect_encoding(reinterpret_cast<const char *>(input), length);
+}
+
+/**
+ * Autodetect the possible encodings of the input in one pass.
+ * E.g., if the input might be UTF-16LE or UTF-8, this function returns
+ * the value (simdutf::encoding_type::UTF8 | simdutf::encoding_type::UTF16_LE).
+ *
+ * Overriden by each implementation.
+ *
+ * @param input the string to analyze.
+ * @param length the length of the string in bytes.
+ * @return the detected encoding type
+ */
+simdutf_warn_unused int detect_encodings(const char * input, size_t length) noexcept;
+simdutf_really_inline simdutf_warn_unused int detect_encodings(const uint8_t * input, size_t length) noexcept {
+  return detect_encodings(reinterpret_cast<const char *>(input), length);
+}
+
+
+/**
+ * Validate the UTF-8 string.
+ *
+ * Overridden by each implementation.
+ *
+ * @param buf the UTF-8 string to validate.
+ * @param len the length of the string in bytes.
+ * @return true if and only if the string is valid UTF-8.
+ */
+simdutf_warn_unused bool validate_utf8(const char *buf, size_t len) noexcept;
+
+/**
+ * Validate the UTF-8 string and stop on error.
+ *
+ * Overridden by each implementation.
+ *
+ * @param buf the UTF-8 string to validate.
+ * @param len the length of the string in bytes.
+ * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+ */
+simdutf_warn_unused result validate_utf8_with_errors(const char *buf, size_t len) noexcept;
+
+/**
+ * Validate the ASCII string.
+ *
+ * Overridden by each implementation.
+ *
+ * @param buf the ASCII string to validate.
+ * @param len the length of the string in bytes.
+ * @return true if and only if the string is valid ASCII.
+ */
+simdutf_warn_unused bool validate_ascii(const char *buf, size_t len) noexcept;
+
+/**
+ * Validate the ASCII string and stop on error.
+ *
+ * Overridden by each implementation.
+ *
+ * @param buf the ASCII string to validate.
+ * @param len the length of the string in bytes.
+ * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+ */
+simdutf_warn_unused result validate_ascii_with_errors(const char *buf, size_t len) noexcept;
+
+/**
+ * Validate the UTF-16LE string.
+ *
+ * Overridden by each implementation.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param buf the UTF-16LE string to validate.
+ * @param len the length of the string in number of 2-byte words (char16_t).
+ * @return true if and only if the string is valid UTF-16LE.
+ */
+simdutf_warn_unused bool validate_utf16le(const char16_t *buf, size_t len) noexcept;
+
+/**
+ * Validate the UTF-16BE string.
+ *
+ * Overridden by each implementation.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param buf the UTF-16BE string to validate.
+ * @param len the length of the string in number of 2-byte words (char16_t).
+ * @return true if and only if the string is valid UTF-16BE.
+ */
+simdutf_warn_unused bool validate_utf16be(const char16_t *buf, size_t len) noexcept;
+
+/**
+ * Validate the UTF-16LE string and stop on error.
+ *
+ * Overridden by each implementation.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param buf the UTF-16LE string to validate.
+ * @param len the length of the string in number of 2-byte words (char16_t).
+ * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+ */
+simdutf_warn_unused result validate_utf16le_with_errors(const char16_t *buf, size_t len) noexcept;
+
+/**
+ * Validate the UTF-16BE string and stop on error.
+ *
+ * Overridden by each implementation.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param buf the UTF-16BE string to validate.
+ * @param len the length of the string in number of 2-byte words (char16_t).
+ * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+ */
+simdutf_warn_unused result validate_utf16be_with_errors(const char16_t *buf, size_t len) noexcept;
+
+/**
+ * Validate the UTF-32LE string.
+ *
+ * Overridden by each implementation.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param buf the UTF-32LE string to validate.
+ * @param len the length of the string in number of 4-byte words (char32_t).
+ * @return true if and only if the string is valid UTF-32LE.
+ */
+simdutf_warn_unused bool validate_utf32(const char32_t *buf, size_t len) noexcept;
+
+/**
+ * Validate the UTF-32LE string and stop on error.
+ *
+ * Overridden by each implementation.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param buf the UTF-32LE string to validate.
+ * @param len the length of the string in number of 4-byte words (char32_t).
+ * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+ */
+simdutf_warn_unused result validate_utf32_with_errors(const char32_t *buf, size_t len) noexcept;
+
+/**
+ * Convert possibly broken UTF-8 string into UTF-16LE string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf16_buffer  the pointer to buffer that can hold conversion result
+ * @return the number of written char16_t; 0 if the input was not valid UTF-8 string
+ */
+simdutf_warn_unused size_t convert_utf8_to_utf16le(const char * input, size_t length, char16_t* utf16_output) noexcept;
+
+/**
+ * Convert possibly broken UTF-8 string into UTF-16BE string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf16_buffer  the pointer to buffer that can hold conversion result
+ * @return the number of written char16_t; 0 if the input was not valid UTF-8 string
+ */
+simdutf_warn_unused size_t convert_utf8_to_utf16be(const char * input, size_t length, char16_t* utf16_output) noexcept;
+
+/**
+ * Convert possibly broken UTF-8 string into UTF-16LE string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf16_buffer  the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char16_t written if successful.
+ */
+simdutf_warn_unused result convert_utf8_to_utf16le_with_errors(const char * input, size_t length, char16_t* utf16_output) noexcept;
+
+/**
+ * Convert possibly broken UTF-8 string into UTF-16BE string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf16_buffer  the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char16_t written if successful.
+ */
+simdutf_warn_unused result convert_utf8_to_utf16be_with_errors(const char * input, size_t length, char16_t* utf16_output) noexcept;
+
+/**
+ * Convert possibly broken UTF-8 string into UTF-32LE string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf32_buffer  the pointer to buffer that can hold conversion result
+ * @return the number of written char32_t; 0 if the input was not valid UTF-8 string
+ */
+simdutf_warn_unused size_t convert_utf8_to_utf32(const char * input, size_t length, char32_t* utf32_output) noexcept;
+
+/**
+ * Convert possibly broken UTF-8 string into UTF-32LE string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf32_buffer  the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char32_t written if successful.
+ */
+simdutf_warn_unused result convert_utf8_to_utf32_with_errors(const char * input, size_t length, char32_t* utf32_output) noexcept;
+
+/**
+ * Convert valid UTF-8 string into UTF-16LE string.
+ *
+ * This function assumes that the input string is valid UTF-8.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf16_buffer  the pointer to buffer that can hold conversion result
+ * @return the number of written char16_t
+ */
+simdutf_warn_unused size_t convert_valid_utf8_to_utf16le(const char * input, size_t length, char16_t* utf16_buffer) noexcept;
+
+/**
+ * Convert valid UTF-8 string into UTF-16BE string.
+ *
+ * This function assumes that the input string is valid UTF-8.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf16_buffer  the pointer to buffer that can hold conversion result
+ * @return the number of written char16_t
+ */
+simdutf_warn_unused size_t convert_valid_utf8_to_utf16be(const char * input, size_t length, char16_t* utf16_buffer) noexcept;
+
+/**
+ * Convert valid UTF-8 string into UTF-32LE string.
+ *
+ * This function assumes that the input string is valid UTF-8.
+ *
+ * @param input         the UTF-8 string to convert
+ * @param length        the length of the string in bytes
+ * @param utf32_buffer  the pointer to buffer that can hold conversion result
+ * @return the number of written char32_t
+ */
+simdutf_warn_unused size_t convert_valid_utf8_to_utf32(const char * input, size_t length, char32_t* utf32_buffer) noexcept;
+
+/**
+ * Compute the number of 2-byte words that this UTF-8 string would require in UTF-16LE format.
+ *
+ * This function does not validate the input.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-8 string to process
+ * @param length        the length of the string in bytes
+ * @return the number of char16_t words required to encode the UTF-8 string as UTF-16LE
+ */
+simdutf_warn_unused size_t utf16_length_from_utf8(const char * input, size_t length) noexcept;
+
+/**
+ * Compute the number of 4-byte words that this UTF-8 string would require in UTF-32LE format.
+ *
+ * This function is equivalent to count_utf8
+ *
+ * This function does not validate the input.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-8 string to process
+ * @param length        the length of the string in bytes
+ * @return the number of char32_t words required to encode the UTF-8 string as UTF-32LE
+ */
+simdutf_warn_unused size_t utf32_length_from_utf8(const char * input, size_t length) noexcept;
+
+/**
+ * Convert possibly broken UTF-16LE string into UTF-8 string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16LE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf8_buffer   the pointer to buffer that can hold conversion result
+ * @return number of written words; 0 if input is not a valid UTF-16LE string
+ */
+simdutf_warn_unused size_t convert_utf16le_to_utf8(const char16_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-16BE string into UTF-8 string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16BE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf8_buffer   the pointer to buffer that can hold conversion result
+ * @return number of written words; 0 if input is not a valid UTF-16LE string
+ */
+simdutf_warn_unused size_t convert_utf16be_to_utf8(const char16_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-16LE string into UTF-8 string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16LE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf8_buffer   the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char written if successful.
+ */
+simdutf_warn_unused result convert_utf16le_to_utf8_with_errors(const char16_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-16BE string into UTF-8 string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16BE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf8_buffer   the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char written if successful.
+ */
+simdutf_warn_unused result convert_utf16be_to_utf8_with_errors(const char16_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert valid UTF-16LE string into UTF-8 string.
+ *
+ * This function assumes that the input string is valid UTF-16LE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16LE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf8_buffer   the pointer to buffer that can hold the conversion result
+ * @return number of written words; 0 if conversion is not possible
+ */
+simdutf_warn_unused size_t convert_valid_utf16le_to_utf8(const char16_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert valid UTF-16BE string into UTF-8 string.
+ *
+ * This function assumes that the input string is valid UTF-16BE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16BE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf8_buffer   the pointer to buffer that can hold the conversion result
+ * @return number of written words; 0 if conversion is not possible
+ */
+simdutf_warn_unused size_t convert_valid_utf16be_to_utf8(const char16_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-16LE string into UTF-32LE string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16LE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf32_buffer   the pointer to buffer that can hold conversion result
+ * @return number of written words; 0 if input is not a valid UTF-16LE string
+ */
+simdutf_warn_unused size_t convert_utf16le_to_utf32(const char16_t * input, size_t length, char32_t* utf32_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-16BE string into UTF-32LE string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16BE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf32_buffer   the pointer to buffer that can hold conversion result
+ * @return number of written words; 0 if input is not a valid UTF-16LE string
+ */
+simdutf_warn_unused size_t convert_utf16be_to_utf32(const char16_t * input, size_t length, char32_t* utf32_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-16LE string into UTF-32LE string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16LE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf32_buffer   the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char32_t written if successful.
+ */
+simdutf_warn_unused result convert_utf16le_to_utf32_with_errors(const char16_t * input, size_t length, char32_t* utf32_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-16BE string into UTF-32LE string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16BE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf32_buffer   the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char32_t written if successful.
+ */
+simdutf_warn_unused result convert_utf16be_to_utf32_with_errors(const char16_t * input, size_t length, char32_t* utf32_buffer) noexcept;
+
+/**
+ * Convert valid UTF-16LE string into UTF-32LE string.
+ *
+ * This function assumes that the input string is valid UTF-16LE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16LE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf32_buffer   the pointer to buffer that can hold the conversion result
+ * @return number of written words; 0 if conversion is not possible
+ */
+simdutf_warn_unused size_t convert_valid_utf16le_to_utf32(const char16_t * input, size_t length, char32_t* utf32_buffer) noexcept;
+
+/**
+ * Convert valid UTF-16BE string into UTF-32LE string.
+ *
+ * This function assumes that the input string is valid UTF-16LE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16BE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param utf32_buffer   the pointer to buffer that can hold the conversion result
+ * @return number of written words; 0 if conversion is not possible
+ */
+simdutf_warn_unused size_t convert_valid_utf16be_to_utf32(const char16_t * input, size_t length, char32_t* utf32_buffer) noexcept;
+
+/**
+ * Compute the number of bytes that this UTF-16LE string would require in UTF-8 format.
+ *
+ * This function does not validate the input.
+ *
+ * @param input         the UTF-16LE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @return the number of bytes required to encode the UTF-16LE string as UTF-8
+ */
+simdutf_warn_unused size_t utf8_length_from_utf16le(const char16_t * input, size_t length) noexcept;
+
+/**
+ * Compute the number of bytes that this UTF-16BE string would require in UTF-8 format.
+ *
+ * This function does not validate the input.
+ *
+ * @param input         the UTF-16BE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @return the number of bytes required to encode the UTF-16BE string as UTF-8
+ */
+simdutf_warn_unused size_t utf8_length_from_utf16be(const char16_t * input, size_t length) noexcept;
+
+/**
+ * Convert possibly broken UTF-32LE string into UTF-8 string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf8_buffer   the pointer to buffer that can hold conversion result
+ * @return number of written words; 0 if input is not a valid UTF-32LE string
+ */
+simdutf_warn_unused size_t convert_utf32_to_utf8(const char32_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-32LE string into UTF-8 string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf8_buffer   the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char written if successful.
+ */
+simdutf_warn_unused result convert_utf32_to_utf8_with_errors(const char32_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert valid UTF-32LE string into UTF-8 string.
+ *
+ * This function assumes that the input string is valid UTF-32LE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf8_buffer   the pointer to buffer that can hold the conversion result
+ * @return number of written words; 0 if conversion is not possible
+ */
+simdutf_warn_unused size_t convert_valid_utf32_to_utf8(const char32_t * input, size_t length, char* utf8_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-32LE string into UTF-16LE string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf16_buffer   the pointer to buffer that can hold conversion result
+ * @return number of written words; 0 if input is not a valid UTF-32LE string
+ */
+simdutf_warn_unused size_t convert_utf32_to_utf16le(const char32_t * input, size_t length, char16_t* utf16_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-32LE string into UTF-16BE string.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf16_buffer   the pointer to buffer that can hold conversion result
+ * @return number of written words; 0 if input is not a valid UTF-32LE string
+ */
+simdutf_warn_unused size_t convert_utf32_to_utf16be(const char32_t * input, size_t length, char16_t* utf16_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-32LE string into UTF-16LE string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf16_buffer   the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char16_t written if successful.
+ */
+simdutf_warn_unused result convert_utf32_to_utf16le_with_errors(const char32_t * input, size_t length, char16_t* utf16_buffer) noexcept;
+
+/**
+ * Convert possibly broken UTF-32LE string into UTF-16BE string and stop on error.
+ *
+ * During the conversion also validation of the input string is done.
+ * This function is suitable to work with inputs from untrusted sources.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf16_buffer   the pointer to buffer that can hold conversion result
+ * @return a result pair struct with an error code and either the position of the error if any or the number of char16_t written if successful.
+ */
+simdutf_warn_unused result convert_utf32_to_utf16be_with_errors(const char32_t * input, size_t length, char16_t* utf16_buffer) noexcept;
+
+/**
+ * Convert valid UTF-32LE string into UTF-16LE string.
+ *
+ * This function assumes that the input string is valid UTF-32LE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf16_buffer   the pointer to buffer that can hold the conversion result
+ * @return number of written words; 0 if conversion is not possible
+ */
+simdutf_warn_unused size_t convert_valid_utf32_to_utf16le(const char32_t * input, size_t length, char16_t* utf16_buffer) noexcept;
+
+/**
+ * Convert valid UTF-32LE string into UTF-16BE string.
+ *
+ * This function assumes that the input string is valid UTF-32LE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @param utf16_buffer   the pointer to buffer that can hold the conversion result
+ * @return number of written words; 0 if conversion is not possible
+ */
+simdutf_warn_unused size_t convert_valid_utf32_to_utf16be(const char32_t * input, size_t length, char16_t* utf16_buffer) noexcept;
+
+/**
+ * Change the endianness of the input. Can be used to go from UTF-16LE to UTF-16BE or
+ * from UTF-16BE to UTF-16LE.
+ *
+ * This function does not validate the input.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16 string to process
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @param output        the pointer to buffer that can hold the conversion result
+ */
+void change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) noexcept;
+
+/**
+ * Compute the number of bytes that this UTF-32LE string would require in UTF-8 format.
+ *
+ * This function does not validate the input.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @return the number of bytes required to encode the UTF-32LE string as UTF-8
+ */
+simdutf_warn_unused size_t utf8_length_from_utf32(const char32_t * input, size_t length) noexcept;
+
+/**
+ * Compute the number of two-byte words that this UTF-32LE string would require in UTF-16 format.
+ *
+ * This function does not validate the input.
+ *
+ * @param input         the UTF-32LE string to convert
+ * @param length        the length of the string in 4-byte words (char32_t)
+ * @return the number of bytes required to encode the UTF-32LE string as UTF-16
+ */
+simdutf_warn_unused size_t utf16_length_from_utf32(const char32_t * input, size_t length) noexcept;
+
+/**
+ * Compute the number of bytes that this UTF-16LE string would require in UTF-32LE format.
+ *
+ * This function is equivalent to count_utf16le.
+ *
+ * This function does not validate the input.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16LE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @return the number of bytes required to encode the UTF-16LE string as UTF-32LE
+ */
+simdutf_warn_unused size_t utf32_length_from_utf16le(const char16_t * input, size_t length) noexcept;
+
+/**
+ * Compute the number of bytes that this UTF-16BE string would require in UTF-32LE format.
+ *
+ * This function is equivalent to count_utf16be.
+ *
+ * This function does not validate the input.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16BE string to convert
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @return the number of bytes required to encode the UTF-16BE string as UTF-32LE
+ */
+simdutf_warn_unused size_t utf32_length_from_utf16be(const char16_t * input, size_t length) noexcept;
+
+/**
+ * Count the number of code points (characters) in the string assuming that
+ * it is valid.
+ *
+ * This function assumes that the input string is valid UTF-16LE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16LE string to process
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @return number of code points
+ */
+simdutf_warn_unused size_t count_utf16le(const char16_t * input, size_t length) noexcept;
+
+/**
+ * Count the number of code points (characters) in the string assuming that
+ * it is valid.
+ *
+ * This function assumes that the input string is valid UTF-16BE.
+ *
+ * This function is not BOM-aware.
+ *
+ * @param input         the UTF-16BE string to process
+ * @param length        the length of the string in 2-byte words (char16_t)
+ * @return number of code points
+ */
+simdutf_warn_unused size_t count_utf16be(const char16_t * input, size_t length) noexcept;
+
+/**
+ * Count the number of code points (characters) in the string assuming that
+ * it is valid.
+ *
+ * This function assumes that the input string is valid UTF-8.
+ *
+ * @param input         the UTF-8 string to process
+ * @param length        the length of the string in bytes
+ * @return number of code points
+ */
+simdutf_warn_unused size_t count_utf8(const char * input, size_t length) noexcept;
+
+/**
+ * An implementation of simdutf for a particular CPU architecture.
+ *
+ * Also used to maintain the currently active implementation. The active implementation is
+ * automatically initialized on first use to the most advanced implementation supported by the host.
+ */
+class implementation {
+public:
+
+  /**
+   * The name of this implementation.
+   *
+   *     const implementation *impl = simdutf::active_implementation;
+   *     cout << "simdutf is optimized for " << impl->name() << "(" << impl->description() << ")" << endl;
+   *
+   * @return the name of the implementation, e.g. "haswell", "westmere", "arm64"
+   */
+  virtual const std::string &name() const { return _name; }
+
+  /**
+   * The description of this implementation.
+   *
+   *     const implementation *impl = simdutf::active_implementation;
+   *     cout << "simdutf is optimized for " << impl->name() << "(" << impl->description() << ")" << endl;
+   *
+   * @return the name of the implementation, e.g. "haswell", "westmere", "arm64"
+   */
+  virtual const std::string &description() const { return _description; }
+
+  /**
+   * The instruction sets this implementation is compiled against
+   * and the current CPU match. This function may poll the current CPU/system
+   * and should therefore not be called too often if performance is a concern.
+   *
+   *
+   * @return true if the implementation can be safely used on the current system (determined at runtime)
+   */
+  bool supported_by_runtime_system() const;
+
+  /**
+   * This function will try to detect the encoding
+   * @param input the string to identify
+   * @param length the length of the string in bytes.
+   * @return the encoding type detected
+   */
+  virtual encoding_type autodetect_encoding(const char * input, size_t length) const noexcept;
+
+  /**
+   * This function will try to detect the possible encodings in one pass
+   * @param input the string to identify
+   * @param length the length of the string in bytes.
+   * @return the encoding type detected
+   */
+  virtual int detect_encodings(const char * input, size_t length) const noexcept = 0;
+
+  /**
+   * @private For internal implementation use
+   *
+   * The instruction sets this implementation is compiled against.
+   *
+   * @return a mask of all required `internal::instruction_set::` values
+   */
+  virtual uint32_t required_instruction_sets() const { return _required_instruction_sets; };
+
+
+  /**
+   * Validate the UTF-8 string.
+   *
+   * Overridden by each implementation.
+   *
+   * @param buf the UTF-8 string to validate.
+   * @param len the length of the string in bytes.
+   * @return true if and only if the string is valid UTF-8.
+   */
+  simdutf_warn_unused virtual bool validate_utf8(const char *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the UTF-8 string and stop on errors.
+   *
+   * Overridden by each implementation.
+   *
+   * @param buf the UTF-8 string to validate.
+   * @param len the length of the string in bytes.
+   * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+   */
+  simdutf_warn_unused virtual result validate_utf8_with_errors(const char *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the ASCII string.
+   *
+   * Overridden by each implementation.
+   *
+   * @param buf the ASCII string to validate.
+   * @param len the length of the string in bytes.
+   * @return true if and only if the string is valid ASCII.
+   */
+  simdutf_warn_unused virtual bool validate_ascii(const char *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the ASCII string and stop on error.
+   *
+   * Overridden by each implementation.
+   *
+   * @param buf the ASCII string to validate.
+   * @param len the length of the string in bytes.
+   * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+   */
+  simdutf_warn_unused virtual result validate_ascii_with_errors(const char *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the UTF-16LE string.
+   *
+   * Overridden by each implementation.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param buf the UTF-16LE string to validate.
+   * @param len the length of the string in number of 2-byte words (char16_t).
+   * @return true if and only if the string is valid UTF-16LE.
+   */
+  simdutf_warn_unused virtual bool validate_utf16le(const char16_t *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the UTF-16BE string.
+   *
+   * Overridden by each implementation.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param buf the UTF-16BE string to validate.
+   * @param len the length of the string in number of 2-byte words (char16_t).
+   * @return true if and only if the string is valid UTF-16BE.
+   */
+  simdutf_warn_unused virtual bool validate_utf16be(const char16_t *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the UTF-16LE string and stop on error.
+   *
+   * Overridden by each implementation.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param buf the UTF-16LE string to validate.
+   * @param len the length of the string in number of 2-byte words (char16_t).
+   * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+   */
+  simdutf_warn_unused virtual result validate_utf16le_with_errors(const char16_t *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the UTF-16BE string and stop on error.
+   *
+   * Overridden by each implementation.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param buf the UTF-16BE string to validate.
+   * @param len the length of the string in number of 2-byte words (char16_t).
+   * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+   */
+  simdutf_warn_unused virtual result validate_utf16be_with_errors(const char16_t *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the UTF-32LE string.
+   *
+   * Overridden by each implementation.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param buf the UTF-32LE string to validate.
+   * @param len the length of the string in number of 4-byte words (char32_t).
+   * @return true if and only if the string is valid UTF-32LE.
+   */
+  simdutf_warn_unused virtual bool validate_utf32(const char32_t *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Validate the UTF-32LE string and stop on error.
+   *
+   * Overridden by each implementation.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param buf the UTF-32LE string to validate.
+   * @param len the length of the string in number of 4-byte words (char32_t).
+   * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+   */
+  simdutf_warn_unused virtual result validate_utf32_with_errors(const char32_t *buf, size_t len) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-8 string into UTF-16LE string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf16_buffer  the pointer to buffer that can hold conversion result
+   * @return the number of written char16_t; 0 if the input was not valid UTF-8 string
+   */
+  simdutf_warn_unused virtual size_t convert_utf8_to_utf16le(const char * input, size_t length, char16_t* utf16_output) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-8 string into UTF-16BE string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf16_buffer  the pointer to buffer that can hold conversion result
+   * @return the number of written char16_t; 0 if the input was not valid UTF-8 string
+   */
+  simdutf_warn_unused virtual size_t convert_utf8_to_utf16be(const char * input, size_t length, char16_t* utf16_output) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-8 string into UTF-16LE string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf16_buffer  the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf8_to_utf16le_with_errors(const char * input, size_t length, char16_t* utf16_output) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-8 string into UTF-16BE string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf16_buffer  the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of words validated if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf8_to_utf16be_with_errors(const char * input, size_t length, char16_t* utf16_output) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-8 string into UTF-32LE string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf32_buffer  the pointer to buffer that can hold conversion result
+   * @return the number of written char16_t; 0 if the input was not valid UTF-8 string
+   */
+  simdutf_warn_unused virtual size_t convert_utf8_to_utf32(const char * input, size_t length, char32_t* utf32_output) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-8 string into UTF-32LE string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf32_buffer  the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of char32_t written if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf8_to_utf32_with_errors(const char * input, size_t length, char32_t* utf32_output) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-8 string into UTF-16LE string.
+   *
+   * This function assumes that the input string is valid UTF-8.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf16_buffer  the pointer to buffer that can hold conversion result
+   * @return the number of written char16_t
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf8_to_utf16le(const char * input, size_t length, char16_t* utf16_buffer) const noexcept = 0;
+
+/**
+   * Convert valid UTF-8 string into UTF-16BE string.
+   *
+   * This function assumes that the input string is valid UTF-8.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf16_buffer  the pointer to buffer that can hold conversion result
+   * @return the number of written char16_t
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf8_to_utf16be(const char * input, size_t length, char16_t* utf16_buffer) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-8 string into UTF-32LE string.
+   *
+   * This function assumes that the input string is valid UTF-8.
+   *
+   * @param input         the UTF-8 string to convert
+   * @param length        the length of the string in bytes
+   * @param utf16_buffer  the pointer to buffer that can hold conversion result
+   * @return the number of written char32_t
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf8_to_utf32(const char * input, size_t length, char32_t* utf32_buffer) const noexcept = 0;
+
+  /**
+   * Compute the number of 2-byte words that this UTF-8 string would require in UTF-16LE format.
+   *
+   * This function does not validate the input.
+   *
+   * @param input         the UTF-8 string to process
+   * @param length        the length of the string in bytes
+   * @return the number of char16_t words required to encode the UTF-8 string as UTF-16LE
+   */
+  simdutf_warn_unused virtual size_t utf16_length_from_utf8(const char * input, size_t length) const noexcept = 0;
+
+   /**
+   * Compute the number of 4-byte words that this UTF-8 string would require in UTF-32LE format.
+   *
+   * This function is equivalent to count_utf8.
+   *
+   * This function does not validate the input.
+   *
+   * @param input         the UTF-8 string to process
+   * @param length        the length of the string in bytes
+   * @return the number of char32_t words required to encode the UTF-8 string as UTF-32LE
+   */
+  simdutf_warn_unused virtual size_t utf32_length_from_utf8(const char * input, size_t length) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-16LE string into UTF-8 string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf8_buffer   the pointer to buffer that can hold conversion result
+   * @return number of written words; 0 if input is not a valid UTF-16LE string
+   */
+  simdutf_warn_unused virtual size_t convert_utf16le_to_utf8(const char16_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-16BE string into UTF-8 string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf8_buffer   the pointer to buffer that can hold conversion result
+   * @return number of written words; 0 if input is not a valid UTF-16BE string
+   */
+  simdutf_warn_unused virtual size_t convert_utf16be_to_utf8(const char16_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-16LE string into UTF-8 string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf8_buffer   the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of char written if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf16le_to_utf8_with_errors(const char16_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-16BE string into UTF-8 string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf8_buffer   the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of char written if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf16be_to_utf8_with_errors(const char16_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-16LE string into UTF-8 string.
+   *
+   * This function assumes that the input string is valid UTF-16LE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf8_buffer   the pointer to buffer that can hold the conversion result
+   * @return number of written words; 0 if conversion is not possible
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf16le_to_utf8(const char16_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-16BE string into UTF-8 string.
+   *
+   * This function assumes that the input string is valid UTF-16BE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf8_buffer   the pointer to buffer that can hold the conversion result
+   * @return number of written words; 0 if conversion is not possible
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf16be_to_utf8(const char16_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-16LE string into UTF-32LE string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf32_buffer   the pointer to buffer that can hold conversion result
+   * @return number of written words; 0 if input is not a valid UTF-16LE string
+   */
+  simdutf_warn_unused virtual size_t convert_utf16le_to_utf32(const char16_t * input, size_t length, char32_t* utf32_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-16BE string into UTF-32LE string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf32_buffer   the pointer to buffer that can hold conversion result
+   * @return number of written words; 0 if input is not a valid UTF-16BE string
+   */
+  simdutf_warn_unused virtual size_t convert_utf16be_to_utf32(const char16_t * input, size_t length, char32_t* utf32_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-16LE string into UTF-32LE string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf32_buffer   the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of char32_t written if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf16le_to_utf32_with_errors(const char16_t * input, size_t length, char32_t* utf32_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-16BE string into UTF-32LE string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf32_buffer   the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of char32_t written if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf16be_to_utf32_with_errors(const char16_t * input, size_t length, char32_t* utf32_buffer) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-16LE string into UTF-32LE string.
+   *
+   * This function assumes that the input string is valid UTF-16LE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf32_buffer   the pointer to buffer that can hold the conversion result
+   * @return number of written words; 0 if conversion is not possible
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf16le_to_utf32(const char16_t * input, size_t length, char32_t* utf32_buffer) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-16LE string into UTF-32BE string.
+   *
+   * This function assumes that the input string is valid UTF-16BE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param utf32_buffer   the pointer to buffer that can hold the conversion result
+   * @return number of written words; 0 if conversion is not possible
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf16be_to_utf32(const char16_t * input, size_t length, char32_t* utf32_buffer) const noexcept = 0;
+
+  /**
+   * Compute the number of bytes that this UTF-16LE string would require in UTF-8 format.
+   *
+   * This function does not validate the input.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @return the number of bytes required to encode the UTF-16LE string as UTF-8
+   */
+  simdutf_warn_unused virtual size_t utf8_length_from_utf16le(const char16_t * input, size_t length) const noexcept = 0;
+
+  /**
+   * Compute the number of bytes that this UTF-16BE string would require in UTF-8 format.
+   *
+   * This function does not validate the input.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @return the number of bytes required to encode the UTF-16BE string as UTF-8
+   */
+  simdutf_warn_unused virtual size_t utf8_length_from_utf16be(const char16_t * input, size_t length) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-32LE string into UTF-8 string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf8_buffer   the pointer to buffer that can hold conversion result
+   * @return number of written words; 0 if input is not a valid UTF-32LE string
+   */
+  simdutf_warn_unused virtual size_t convert_utf32_to_utf8(const char32_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-32LE string into UTF-8 string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf8_buffer   the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of char written if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf32_to_utf8_with_errors(const char32_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-32LE string into UTF-8 string.
+   *
+   * This function assumes that the input string is valid UTF-32LE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf8_buffer   the pointer to buffer that can hold the conversion result
+   * @return number of written words; 0 if conversion is not possible
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf32_to_utf8(const char32_t * input, size_t length, char* utf8_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-32LE string into UTF-16LE string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf16_buffer   the pointer to buffer that can hold conversion result
+   * @return number of written words; 0 if input is not a valid UTF-32LE string
+   */
+  simdutf_warn_unused virtual size_t convert_utf32_to_utf16le(const char32_t * input, size_t length, char16_t* utf16_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-32LE string into UTF-16BE string.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf16_buffer   the pointer to buffer that can hold conversion result
+   * @return number of written words; 0 if input is not a valid UTF-32LE string
+   */
+  simdutf_warn_unused virtual size_t convert_utf32_to_utf16be(const char32_t * input, size_t length, char16_t* utf16_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-32LE string into UTF-16LE string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf16_buffer   the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of char16_t written if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf32_to_utf16le_with_errors(const char32_t * input, size_t length, char16_t* utf16_buffer) const noexcept = 0;
+
+  /**
+   * Convert possibly broken UTF-32LE string into UTF-16BE string and stop on error.
+   *
+   * During the conversion also validation of the input string is done.
+   * This function is suitable to work with inputs from untrusted sources.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf16_buffer   the pointer to buffer that can hold conversion result
+   * @return a result pair struct with an error code and either the position of the error if any or the number of char16_t written if successful.
+   */
+  simdutf_warn_unused virtual result convert_utf32_to_utf16be_with_errors(const char32_t * input, size_t length, char16_t* utf16_buffer) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-32LE string into UTF-16LE string.
+   *
+   * This function assumes that the input string is valid UTF-32LE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf16_buffer   the pointer to buffer that can hold the conversion result
+   * @return number of written words; 0 if conversion is not possible
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf32_to_utf16le(const char32_t * input, size_t length, char16_t* utf16_buffer) const noexcept = 0;
+
+  /**
+   * Convert valid UTF-32LE string into UTF-16BE string.
+   *
+   * This function assumes that the input string is valid UTF-32LE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @param utf16_buffer   the pointer to buffer that can hold the conversion result
+   * @return number of written words; 0 if conversion is not possible
+   */
+  simdutf_warn_unused virtual size_t convert_valid_utf32_to_utf16be(const char32_t * input, size_t length, char16_t* utf16_buffer) const noexcept = 0;
+
+  /**
+   * Change the endianness of the input. Can be used to go from UTF-16LE to UTF-16BE or
+   * from UTF-16BE to UTF-16LE.
+   *
+   * This function does not validate the input.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16 string to process
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @param output        the pointer to buffer that can hold the conversion result
+   */
+  virtual void change_endianness_utf16(const char16_t * input, size_t length, char16_t * output) const noexcept = 0;
+
+  /**
+   * Compute the number of bytes that this UTF-32LE string would require in UTF-8 format.
+   *
+   * This function does not validate the input.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @return the number of bytes required to encode the UTF-32LE string as UTF-8
+   */
+  simdutf_warn_unused virtual size_t utf8_length_from_utf32(const char32_t * input, size_t length) const noexcept = 0;
+
+  /**
+   * Compute the number of two-byte words that this UTF-32LE string would require in UTF-16 format.
+   *
+   * This function does not validate the input.
+   *
+   * @param input         the UTF-32LE string to convert
+   * @param length        the length of the string in 4-byte words (char32_t)
+   * @return the number of bytes required to encode the UTF-32LE string as UTF-16
+   */
+  simdutf_warn_unused virtual size_t utf16_length_from_utf32(const char32_t * input, size_t length) const noexcept = 0;
+
+  /*
+   * Compute the number of bytes that this UTF-16LE string would require in UTF-32LE format.
+   *
+   * This function is equivalent to count_utf16le.
+   *
+   * This function does not validate the input.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @return the number of bytes required to encode the UTF-16LE string as UTF-32LE
+   */
+  simdutf_warn_unused virtual size_t utf32_length_from_utf16le(const char16_t * input, size_t length) const noexcept = 0;
+
+  /*
+   * Compute the number of bytes that this UTF-16BE string would require in UTF-32LE format.
+   *
+   * This function is equivalent to count_utf16be.
+   *
+   * This function does not validate the input.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to convert
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @return the number of bytes required to encode the UTF-16BE string as UTF-32LE
+   */
+  simdutf_warn_unused virtual size_t utf32_length_from_utf16be(const char16_t * input, size_t length) const noexcept = 0;
+
+  /**
+   * Count the number of code points (characters) in the string assuming that
+   * it is valid.
+   *
+   * This function assumes that the input string is valid UTF-16LE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16LE string to process
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @return number of code points
+   */
+  simdutf_warn_unused virtual size_t count_utf16le(const char16_t * input, size_t length) const noexcept = 0;
+
+  /**
+   * Count the number of code points (characters) in the string assuming that
+   * it is valid.
+   *
+   * This function assumes that the input string is valid UTF-16BE.
+   *
+   * This function is not BOM-aware.
+   *
+   * @param input         the UTF-16BE string to process
+   * @param length        the length of the string in 2-byte words (char16_t)
+   * @return number of code points
+   */
+  simdutf_warn_unused virtual size_t count_utf16be(const char16_t * input, size_t length) const noexcept = 0;
+
+
+  /**
+   * Count the number of code points (characters) in the string assuming that
+   * it is valid.
+   *
+   * This function assumes that the input string is valid UTF-8.
+   *
+   * @param input         the UTF-8 string to process
+   * @param length        the length of the string in bytes
+   * @return number of code points
+   */
+  simdutf_warn_unused virtual size_t count_utf8(const char * input, size_t length) const noexcept = 0;
+
+
+
+protected:
+  /** @private Construct an implementation with the given name and description. For subclasses. */
+  simdutf_really_inline implementation(
+    std::string name,
+    std::string description,
+    uint32_t required_instruction_sets
+  ) :
+    _name(name),
+    _description(description),
+    _required_instruction_sets(required_instruction_sets)
+  {
+  }
+  virtual ~implementation()=default;
+
+private:
+  /**
+   * The name of this implementation.
+   */
+  const std::string _name;
+
+  /**
+   * The description of this implementation.
+   */
+  const std::string _description;
+
+  /**
+   * Instruction sets required for this implementation.
+   */
+  const uint32_t _required_instruction_sets;
+};
+
+/** @private */
+namespace internal {
+
+/**
+ * The list of available implementations compiled into simdutf.
+ */
+class available_implementation_list {
+public:
+  /** Get the list of available implementations compiled into simdutf */
+  simdutf_really_inline available_implementation_list() {}
+  /** Number of implementations */
+  size_t size() const noexcept;
+  /** STL const begin() iterator */
+  const implementation * const *begin() const noexcept;
+  /** STL const end() iterator */
+  const implementation * const *end() const noexcept;
+
+  /**
+   * Get the implementation with the given name.
+   *
+   * Case sensitive.
+   *
+   *     const implementation *impl = simdutf::available_implementations["westmere"];
+   *     if (!impl) { exit(1); }
+   *     if (!imp->supported_by_runtime_system()) { exit(1); }
+   *     simdutf::active_implementation = impl;
+   *
+   * @param name the implementation to find, e.g. "westmere", "haswell", "arm64"
+   * @return the implementation, or nullptr if the parse failed.
+   */
+  const implementation * operator[](const std::string &name) const noexcept {
+    for (const implementation * impl : *this) {
+      if (impl->name() == name) { return impl; }
+    }
+    return nullptr;
+  }
+
+  /**
+   * Detect the most advanced implementation supported by the current host.
+   *
+   * This is used to initialize the implementation on startup.
+   *
+   *     const implementation *impl = simdutf::available_implementation::detect_best_supported();
+   *     simdutf::active_implementation = impl;
+   *
+   * @return the most advanced supported implementation for the current host, or an
+   *         implementation that returns UNSUPPORTED_ARCHITECTURE if there is no supported
+   *         implementation. Will never return nullptr.
+   */
+  const implementation *detect_best_supported() const noexcept;
+};
+
+template<typename T>
+class atomic_ptr {
+public:
+  atomic_ptr(T *_ptr) : ptr{_ptr} {}
+
+#if defined(SIMDUTF_NO_THREADS)
+  operator const T*() const { return ptr; }
+  const T& operator*() const { return *ptr; }
+  const T* operator->() const { return ptr; }
+
+  operator T*() { return ptr; }
+  T& operator*() { return *ptr; }
+  T* operator->() { return ptr; }
+  atomic_ptr& operator=(T *_ptr) { ptr = _ptr; return *this; }
+
+#else
+  operator const T*() const { return ptr.load(); }
+  const T& operator*() const { return *ptr; }
+  const T* operator->() const { return ptr.load(); }
+
+  operator T*() { return ptr.load(); }
+  T& operator*() { return *ptr; }
+  T* operator->() { return ptr.load(); }
+  atomic_ptr& operator=(T *_ptr) { ptr = _ptr; return *this; }
+
+#endif
+
+private:
+#if defined(SIMDUTF_NO_THREADS)
+  T* ptr;
+#else
+  std::atomic<T*> ptr;
+#endif
+};
+
+} // namespace internal
+
+/**
+ * The list of available implementations compiled into simdutf.
+ */
+extern SIMDUTF_DLLIMPORTEXPORT const internal::available_implementation_list available_implementations;
+
+/**
+  * The active implementation.
+  *
+  * Automatically initialized on first use to the most advanced implementation supported by this hardware.
+  */
+extern SIMDUTF_DLLIMPORTEXPORT internal::atomic_ptr<const implementation> active_implementation;
+
+} // namespace simdutf
+
+#endif // SIMDUTF_IMPLEMENTATION_H
+/* end file include/simdutf/implementation.h */
+
+
+// Implementation-internal files (must be included before the implementations themselves, to keep
+// amalgamation working--otherwise, the first time a file is included, it might be put inside the
+// #ifdef SIMDUTF_IMPLEMENTATION_ARM64/FALLBACK/etc., which means the other implementations can't
+// compile unless that implementation is turned on).
+
+
+SIMDUTF_POP_DISABLE_WARNINGS
+
+#endif // SIMDUTF_H
+/* end file include/simdutf.h */
diff --git a/src/feature_flags.zig b/src/feature_flags.zig
index ef38ea447..f39f96a6e 100644
--- a/src/feature_flags.zig
+++ b/src/feature_flags.zig
@@ -111,3 +111,5 @@ pub const hardcode_localhost_to_127_0_0_1 = true;
 /// But it's very easy to end up importing it accidentally, causing an error at runtime
 /// so we just disable it
 pub const support_jsxs_in_jsx_transform = false;
+
+pub const use_simdutf = true;
diff --git a/src/global.zig b/src/global.zig
index d67f93fb7..2ebe4c58e 100644
--- a/src/global.zig
+++ b/src/global.zig
@@ -482,3 +482,5 @@ pub fn rangeOfSliceInBuffer(slice: []const u8, buffer: []const u8) ?[2]u32 {
 }
 
 pub const invalid_fd = std.math.maxInt(FileDescriptor);
+
+pub const simdutf = @import("./bun.js/bindings/bun-simdutf.zig");
diff --git a/src/string_immutable.zig b/src/string_immutable.zig
index 30e4948cb..598495efa 100644
--- a/src/string_immutable.zig
+++ b/src/string_immutable.zig
@@ -935,7 +935,36 @@ const strings = @This();
 /// If there are no non-ascii characters, this returns null
 /// This is intended to be used for strings that go to JavaScript
 pub fn toUTF16Alloc(allocator: std.mem.Allocator, bytes: []const u8, comptime fail_if_invalid: bool) !?[]u16 {
-    if (strings.firstNonASCII(bytes)) |i| {
+    var first_non_ascii: ?u32 = null;
+
+    if (bun.FeatureFlags.use_simdutf) {
+        if (bytes.len == 0)
+            return &[_]u16{};
+
+        if (bun.simdutf.validate.ascii(bytes))
+            return null;
+
+        const trimmed = bun.simdutf.trim.utf8(bytes);
+        const out_length = bun.simdutf.length.utf16.from.utf8.le(trimmed);
+        var out = try allocator.alloc(u16, out_length);
+
+        const result = bun.simdutf.convert.utf8.to.utf16.with_errors.le(trimmed, out);
+        switch (result.status) {
+            .success => {
+                return out;
+            },
+            else => {
+                if (fail_if_invalid) {
+                    allocator.free(out);
+                    return error.InvalidUTF8;
+                }
+
+                first_non_ascii = @truncate(u32, result.count);
+            },
+        }
+    }
+
+    if (first_non_ascii orelse strings.firstNonASCII(bytes)) |i| {
         const ascii = bytes[0..i];
         const chunk = bytes[i..];
         var output = try std.ArrayList(u16).initCapacity(allocator, ascii.len + 2);
@@ -1054,12 +1083,31 @@ pub fn utf16Codepoint(comptime Type: type, input: Type) UTF16Replacement {
 }
 
 pub fn toUTF8AllocWithType(allocator: std.mem.Allocator, comptime Type: type, utf16: Type) ![]u8 {
+    if (bun.FeatureFlags.use_simdutf and comptime Type == []const u16) {
+        const length = bun.simdutf.length.utf8.from.utf16.le(utf16);
+        const list = try std.ArrayList(u8).initCapacity(allocator, length);
+        list.items.len += bun.simdutf.convert.utf16.to.utf8.le(utf16, list.items.ptr[0..length]);
+        return list;
+    }
+
     var list = try std.ArrayList(u8).initCapacity(allocator, utf16.len);
     list = try toUTF8ListWithType(list, Type, utf16);
     return list.items;
 }
 
 pub fn toUTF8ListWithType(list_: std.ArrayList(u8), comptime Type: type, utf16: Type) !std.ArrayList(u8) {
+    if (bun.FeatureFlags.use_simdutf and comptime Type == []const u16) {
+        var list = list_;
+        const length = bun.simdutf.length.utf8.from.utf16.le(utf16);
+        try list.ensureTotalCapacityPrecise(length);
+        list.items.len += bun.simdutf.convert.utf16.to.utf8.le(utf16, list.items.ptr[0..length]);
+        return list;
+    }
+
+    return toUTF8ListWithTypeBun(list_, Type, utf16);
+}
+
+pub fn toUTF8ListWithTypeBun(list_: std.ArrayList(u8), comptime Type: type, utf16: Type) !std.ArrayList(u8) {
     var list = list_;
     var utf16_remaining = utf16;
 
@@ -2288,6 +2336,20 @@ pub fn copyUTF16IntoUTF8(buf: []u8, comptime Type: type, utf16: Type) EncodeInto
     var utf16_remaining = utf16;
     var ended_on_non_ascii = false;
 
+    if (comptime Type == []const u16) {
+        if (bun.FeatureFlags.use_simdutf) {
+            const trimmed = bun.simdutf.trim.utf16(utf16_remaining);
+            const out_len = bun.simdutf.length.utf8.from.utf16.le(trimmed);
+            if (remaining.len >= out_len) {
+                const result = bun.simdutf.convert.utf16.to.utf8.with_errors.le(trimmed, remaining[0..out_len]);
+                return EncodeIntoResult{
+                    .read = @truncate(u32, trimmed.len),
+                    .written = @truncate(u32, result.count),
+                };
+            }
+        }
+    }
+
     while (firstNonASCII16(Type, utf16_remaining)) |i| {
         const end = @minimum(i, remaining.len);
         if (end > 0) copyU16IntoU8(remaining, Type, utf16_remaining[0..end]);
@@ -2324,6 +2386,10 @@ pub fn copyUTF16IntoUTF8(buf: []u8, comptime Type: type, utf16: Type) EncodeInto
 }
 
 pub fn elementLengthUTF16IntoUTF8(comptime Type: type, utf16: Type) usize {
+    if (bun.FeatureFlags.use_simdutf) {
+        return bun.simdutf.length.utf8.from.utf16.le(utf16);
+    }
+
     var utf16_remaining = utf16;
     var count: usize = 0;
 
@@ -2345,6 +2411,10 @@ pub fn elementLengthUTF8IntoUTF16(comptime Type: type, utf8: Type) usize {
     var utf8_remaining = utf8;
     var count: usize = 0;
 
+    if (bun.FeatureFlags.use_simdutf) {
+        return bun.simdutf.length.utf16.from.utf8.le(utf8);
+    }
+
     while (firstNonASCII(utf8_remaining)) |i| {
         count += i;
 
diff --git a/test/bun.js/text-decoder.test.js b/test/bun.js/text-decoder.test.js
index 2a88a8bc8..bc10bf649 100644
--- a/test/bun.js/text-decoder.test.js
+++ b/test/bun.js/text-decoder.test.js
@@ -1,5 +1,5 @@
 import { expect, it, describe } from "bun:test";
-import { gc as gcTrace } from "./gc";
+import { gc as gcTrace, withoutAggressiveGC } from "./gc";
 
 const getByteLength = (str) => {
   // returns the byte length of an utf8 string
@@ -74,10 +74,12 @@ describe("TextDecoder", () => {
 
     it("DOMJIT call", () => {
       const array = new Uint8Array(bytes.buffer);
-      for (let i = 0; i < 100_000; i++) {
-        const decoded = decoder.decode(array);
-        expect(decoded).toBe(text);
-      }
+      withoutAggressiveGC(() => {
+        for (let i = 0; i < 100_000; i++) {
+          const decoded = decoder.decode(array);
+          expect(decoded).toBe(text);
+        }
+      });
     });
   });