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Diffstat (limited to 'src/wyhash.zig')
| -rw-r--r-- | src/wyhash.zig | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/src/wyhash.zig b/src/wyhash.zig new file mode 100644 index 000000000..bd5cbf62b --- /dev/null +++ b/src/wyhash.zig @@ -0,0 +1,179 @@ +// +// this file is a copy of Wyhash from the zig standard library, version v0.11.0-dev.2609+5e19250a1 +// + +const std = @import("std"); +const mem = std.mem; + +const primes = [_]u64{ + 0xa0761d6478bd642f, + 0xe7037ed1a0b428db, + 0x8ebc6af09c88c6e3, + 0x589965cc75374cc3, + 0x1d8e4e27c47d124f, +}; + +fn read_bytes(comptime bytes: u8, data: []const u8) u64 { + const T = std.meta.Int(.unsigned, 8 * bytes); + return mem.readIntLittle(T, data[0..bytes]); +} + +fn read_8bytes_swapped(data: []const u8) u64 { + return (read_bytes(4, data) << 32 | read_bytes(4, data[4..])); +} + +fn mum(a: u64, b: u64) u64 { + var r = std.math.mulWide(u64, a, b); + r = (r >> 64) ^ r; + return @truncate(u64, r); +} + +fn mix0(a: u64, b: u64, seed: u64) u64 { + return mum(a ^ seed ^ primes[0], b ^ seed ^ primes[1]); +} + +fn mix1(a: u64, b: u64, seed: u64) u64 { + return mum(a ^ seed ^ primes[2], b ^ seed ^ primes[3]); +} + +// Wyhash version which does not store internal state for handling partial buffers. +// This is needed so that we can maximize the speed for the short key case, which will +// use the non-iterative api which the public Wyhash exposes. +const WyhashStateless = struct { + seed: u64, + msg_len: usize, + + pub fn init(seed: u64) WyhashStateless { + return WyhashStateless{ + .seed = seed, + .msg_len = 0, + }; + } + + inline fn round(self: *WyhashStateless, b: []const u8) void { + std.debug.assert(b.len == 32); + + self.seed = mix0( + read_bytes(8, b[0..]), + read_bytes(8, b[8..]), + self.seed, + ) ^ mix1( + read_bytes(8, b[16..]), + read_bytes(8, b[24..]), + self.seed, + ); + } + + pub inline fn update(self: *WyhashStateless, b: []const u8) void { + std.debug.assert(b.len % 32 == 0); + + var off: usize = 0; + while (off < b.len) : (off += 32) { + self.round(b[off .. off + 32]); + // @call(.always_inline, self.round, .{b[off .. off + 32]}); + } + + self.msg_len += b.len; + } + + pub inline fn final(self: *WyhashStateless, b: []const u8) u64 { + std.debug.assert(b.len < 32); + + const seed = self.seed; + const rem_len = @intCast(u5, b.len); + const rem_key = b[0..rem_len]; + + self.seed = switch (rem_len) { + 0 => seed, + 1 => mix0(read_bytes(1, rem_key), primes[4], seed), + 2 => mix0(read_bytes(2, rem_key), primes[4], seed), + 3 => mix0((read_bytes(2, rem_key) << 8) | read_bytes(1, rem_key[2..]), primes[4], seed), + 4 => mix0(read_bytes(4, rem_key), primes[4], seed), + 5 => mix0((read_bytes(4, rem_key) << 8) | read_bytes(1, rem_key[4..]), primes[4], seed), + 6 => mix0((read_bytes(4, rem_key) << 16) | read_bytes(2, rem_key[4..]), primes[4], seed), + 7 => mix0((read_bytes(4, rem_key) << 24) | (read_bytes(2, rem_key[4..]) << 8) | read_bytes(1, rem_key[6..]), primes[4], seed), + 8 => mix0(read_8bytes_swapped(rem_key), primes[4], seed), + 9 => mix0(read_8bytes_swapped(rem_key), read_bytes(1, rem_key[8..]), seed), + 10 => mix0(read_8bytes_swapped(rem_key), read_bytes(2, rem_key[8..]), seed), + 11 => mix0(read_8bytes_swapped(rem_key), (read_bytes(2, rem_key[8..]) << 8) | read_bytes(1, rem_key[10..]), seed), + 12 => mix0(read_8bytes_swapped(rem_key), read_bytes(4, rem_key[8..]), seed), + 13 => mix0(read_8bytes_swapped(rem_key), (read_bytes(4, rem_key[8..]) << 8) | read_bytes(1, rem_key[12..]), seed), + 14 => mix0(read_8bytes_swapped(rem_key), (read_bytes(4, rem_key[8..]) << 16) | read_bytes(2, rem_key[12..]), seed), + 15 => mix0(read_8bytes_swapped(rem_key), (read_bytes(4, rem_key[8..]) << 24) | (read_bytes(2, rem_key[12..]) << 8) | read_bytes(1, rem_key[14..]), seed), + 16 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed), + 17 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(1, rem_key[16..]), primes[4], seed), + 18 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(2, rem_key[16..]), primes[4], seed), + 19 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1((read_bytes(2, rem_key[16..]) << 8) | read_bytes(1, rem_key[18..]), primes[4], seed), + 20 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_bytes(4, rem_key[16..]), primes[4], seed), + 21 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1((read_bytes(4, rem_key[16..]) << 8) | read_bytes(1, rem_key[20..]), primes[4], seed), + 22 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1((read_bytes(4, rem_key[16..]) << 16) | read_bytes(2, rem_key[20..]), primes[4], seed), + 23 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1((read_bytes(4, rem_key[16..]) << 24) | (read_bytes(2, rem_key[20..]) << 8) | read_bytes(1, rem_key[22..]), primes[4], seed), + 24 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), primes[4], seed), + 25 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), read_bytes(1, rem_key[24..]), seed), + 26 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), read_bytes(2, rem_key[24..]), seed), + 27 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), (read_bytes(2, rem_key[24..]) << 8) | read_bytes(1, rem_key[26..]), seed), + 28 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), read_bytes(4, rem_key[24..]), seed), + 29 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), (read_bytes(4, rem_key[24..]) << 8) | read_bytes(1, rem_key[28..]), seed), + 30 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), (read_bytes(4, rem_key[24..]) << 16) | read_bytes(2, rem_key[28..]), seed), + 31 => mix0(read_8bytes_swapped(rem_key), read_8bytes_swapped(rem_key[8..]), seed) ^ mix1(read_8bytes_swapped(rem_key[16..]), (read_bytes(4, rem_key[24..]) << 24) | (read_bytes(2, rem_key[28..]) << 8) | read_bytes(1, rem_key[30..]), seed), + }; + + self.msg_len += b.len; + return mum(self.seed ^ self.msg_len, primes[4]); + } + + pub fn hash(seed: u64, input: []const u8) u64 { + const aligned_len = input.len - (input.len % 32); + + var c = WyhashStateless.init(seed); + c.update(input[0..aligned_len]); + // @call(.always_inline, c.update, .{input[0..aligned_len]}); + return c.final(input[aligned_len..]); + // return @call(.always_inline, c.final, .{input[aligned_len..]}); + } +}; + +/// Fast non-cryptographic 64bit hash function. +/// See https://github.com/wangyi-fudan/wyhash +pub const Wyhash = struct { + state: WyhashStateless, + + buf: [32]u8, + buf_len: usize, + + pub fn init(seed: u64) Wyhash { + return Wyhash{ + .state = WyhashStateless.init(seed), + .buf = undefined, + .buf_len = 0, + }; + } + + pub fn update(self: *Wyhash, b: []const u8) void { + var off: usize = 0; + + if (self.buf_len != 0 and self.buf_len + b.len >= 32) { + off += 32 - self.buf_len; + mem.copy(u8, self.buf[self.buf_len..], b[0..off]); + self.state.update(self.buf[0..]); + self.buf_len = 0; + } + + const remain_len = b.len - off; + const aligned_len = remain_len - (remain_len % 32); + self.state.update(b[off .. off + aligned_len]); + + mem.copy(u8, self.buf[self.buf_len..], b[off + aligned_len ..]); + self.buf_len += @intCast(u8, b[off + aligned_len ..].len); + } + + pub fn final(self: *Wyhash) u64 { + const rem_key = self.buf[0..self.buf_len]; + + return self.state.final(rem_key); + } + + pub fn hash(seed: u64, input: []const u8) u64 { + return WyhashStateless.hash(seed, input); + } +}; |