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Diffstat (limited to '')
| -rw-r--r-- | src/base64/neonbase64.cc | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/src/base64/neonbase64.cc b/src/base64/neonbase64.cc new file mode 100644 index 000000000..a1249d21b --- /dev/null +++ b/src/base64/neonbase64.cc @@ -0,0 +1,120 @@ +// clang-format off +#if defined (__GNUC__) && defined(__ARM_NEON__) + +#include <arm_neon.h> +#include <cstddef> +#include "chromiumbase64.h" +#define MODP_B64_ERROR ((size_t)-1) + +#include <iostream> + + +extern "C" int neon_base64_decode(char *out, const char *src, size_t srclen, size_t *outlen); + + +// The input consists of six character sets in the Base64 alphabet, +// which we need to map back to the 6-bit values they represent. +// There are three ranges, two singles, and then there's the rest. +// +// # From To Add Characters +// 1 [43] [62] +19 + +// 2 [47] [63] +16 / +// 3 [48..57] [52..61] +4 0..9 +// 4 [65..90] [0..25] -65 A..Z +// 5 [97..122] [26..51] -71 a..z +// (6) Everything else => invalid input + +int neon_base64_decode(char *out, const char *src, size_t srclen, size_t *outlen) { + char *out_orig = out; + const uint8x16_t lut_lo = {0x15, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, + 0x11, 0x11, 0x13, 0x1A, 0x1B, 0x1B, 0x1B, 0x1A}; + const uint8x16_t lut_hi = {0x10, 0x10, 0x01, 0x02, 0x04, 0x08, 0x04, 0x08, + 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10}; + const uint8x16_t lut_roll = {0, 16, 19, 4, 191, 191, 185, 185, + 0, 0, 0, 0, 0, 0, 0, 0}; + const uint8x16_t zero8 = vdupq_n_u8(0); + const uint16x8_t zero16 = vdupq_n_u16(0); + const uint8x16_t k2f = vdupq_n_u8(0x2f); + const uint8x16_t kf = vdupq_n_u8(0xf); + const uint8x8_t cst = {0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40}; + const uint16x4_t cst1 = {0x1000, 0x1000, 0x1000, 0x1000}; + + const uint8x8_t shuf0 = {2, 1, 0, 6, 5, 4, 2 + 8, 1 + 8}; + const uint8x8_t shuf1 = {0 + 8, 6 + 8, 5 + 8, 4 + 8, + 2 + 16, 1 + 16, 0 + 16, 6 + 16}; + const uint8x8_t shuf2 = {5 + 16, 4 + 16, 2 + 24, 1 + 24, + 0 + 24, 6 + 24, 5 + 24, 4 + 24}; + + uint8x8x4_t pack; + uint8x8_t res[3]; + uint8x16_t str[2]; + + while (srclen >= 8 * 4) { + __builtin_memcpy(str, src, 8 * 4); + + uint8x16_t in0 = str[0]; + uint8x16_t in1 = str[1]; + uint8x16_t lo_nibbles0 = vandq_u8(in0, kf); + uint8x16_t lo_nibbles1 = vandq_u8(in1, kf); + uint8x16_t hi_nibbles0 = vshrq_n_u8(in0, 4); + uint8x16_t hi_nibbles1 = vshrq_n_u8(in1, 4); + + uint8x16_t lo0 = vqtbl1q_u8(lut_lo, lo_nibbles0); + uint8x16_t lo1 = vqtbl1q_u8(lut_lo, lo_nibbles1); + uint8x16_t hi0 = vqtbl1q_u8(lut_hi, hi_nibbles0); + uint8x16_t hi1 = vqtbl1q_u8(lut_hi, hi_nibbles1); + uint8x16_t test0 = vtstq_u8(lo0, hi0); + uint8x16_t test1 = vtstq_u8(lo1, hi1); + uint8x16_t orr0 = vorrq_u8(test0, test1); + uint8x8_t orr1 = vorr_u8(vget_low_u8(orr0), vget_high_u8(orr0)); + if ((uint64_t)orr1) + break; + + uint8x16_t eq_2F0 = vceqq_u8(in0, k2f); + uint8x16_t eq_2F1 = vceqq_u8(in1, k2f); + uint8x16_t add0 = vaddq_u8(eq_2F0, hi_nibbles0); + uint8x16_t add1 = vaddq_u8(eq_2F1, hi_nibbles1); + uint8x16_t roll0 = vqtbl1q_u8(lut_roll, add0); + uint8x16_t roll1 = vqtbl1q_u8(lut_roll, add1); + uint8x16_t rolled0 = vaddq_u8(in0, roll0); + uint8x16_t rolled1 = vaddq_u8(in1, roll1); + + // Step 1: swap and merge adjacent 6-bit fields. + uint8x16x2_t unzip8 = vuzpq_u8(rolled0, rolled1); + uint8x16x2_t zip8 = vzipq_u8(unzip8.val[1], zero8); + uint16x8_t mul0 = vmlal_u8(vreinterpretq_u16_u8(zip8.val[0]), + vget_low_u8(unzip8.val[0]), cst); + uint16x8_t mul1 = vmlal_u8(vreinterpretq_u16_u8(zip8.val[1]), + vget_high_u8(unzip8.val[0]), cst); + + // Step 2: swap and merge 12-bit words into a 24-bit word. + uint16x8x2_t unzip16 = vuzpq_u16(mul0, mul1); + uint16x8x2_t zip16 = vzipq_u16(unzip16.val[1], zero16); + uint32x4_t merge0 = vmlal_u16(vreinterpretq_u32_u16(zip16.val[0]), + vget_low_u16(unzip16.val[0]), cst1); + uint32x4_t merge1 = vmlal_u16(vreinterpretq_u32_u16(zip16.val[1]), + vget_high_u16(unzip16.val[0]), cst1); + pack.val[0] = vget_low_u8(vreinterpretq_u8_u32(merge0)); + pack.val[1] = vget_high_u8(vreinterpretq_u8_u32(merge0)); + pack.val[2] = vget_low_u8(vreinterpretq_u8_u32(merge1)); + pack.val[3] = vget_high_u8(vreinterpretq_u8_u32(merge1)); + + res[0] = vtbl4_u8(pack, shuf0); + res[1] = vtbl4_u8(pack, shuf1); + res[2] = vtbl4_u8(pack, shuf2); + __builtin_memcpy(out, res, 6 * 4); + + out += 6 * 4; + srclen -= 8 * 4; + src += 8 * 4; + } + +// std::cout << "Chromium? " << (out - out_orig) << std::endl; + size_t scalarret = chromium_base64_decode(out, src, srclen, outlen); + *outlen += (out - out_orig); + if (scalarret == MODP_B64_ERROR) + return (int)MODP_B64_ERROR; + return (out - out_orig) + scalarret; +} + +#endif
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