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 /* adler32_simd.c * * Copyright 2017 The Chromium Authors. All rights reserved. * Use of this source code is governed by a BSD-style license that can be * found in the Chromium source repository LICENSE file. * * Per http://en.wikipedia.org/wiki/Adler-32 the adler32 A value (aka s1) is * the sum of N input data bytes D1 ... DN, * * A = A0 + D1 + D2 + ... + DN * * where A0 is the initial value. * * SSE2 _mm_sad_epu8() can be used for byte sums (see http://bit.ly/2wpUOeD, * for example) and accumulating the byte sums can use SSE shuffle-adds (see * the "Integer" section of http://bit.ly/2erPT8t for details). Arm NEON has * similar instructions. * * The adler32 B value (aka s2) sums the A values from each step: * * B0 + (A0 + D1) + (A0 + D1 + D2) + ... + (A0 + D1 + D2 + ... + DN) or * * B0 + N.A0 + N.D1 + (N-1).D2 + (N-2).D3 + ... + (N-(N-1)).DN * * B0 being the initial value. For 32 bytes (ideal for garden-variety SIMD): * * B = B0 + 32.A0 + [D1 D2 D3 ... D32] x [32 31 30 ... 1]. * * Adjacent blocks of 32 input bytes can be iterated with the expressions to * compute the adler32 s1 s2 of M >> 32 input bytes [1]. * * As M grows, the s1 s2 sums grow. If left unchecked, they would eventually * overflow the precision of their integer representation (bad). However, s1 * and s2 also need to be computed modulo the adler BASE value (reduced). If * at most NMAX bytes are processed before a reduce, s1 s2 _cannot_ overflow * a uint32_t type (the NMAX constraint) [2]. * * [1] the iterative equations for s2 contain constant factors; these can be * hoisted from the n-blocks do loop of the SIMD code. * * [2] zlib adler32_z() uses this fact to implement NMAX-block-based updates * of the adler s1 s2 of uint32_t type (see adler32.c). */ #include "adler32_simd.h" /* Definitions from adler32.c: largest prime smaller than 65536 */ #define BASE 65521U /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ #define NMAX 5552 #if defined(ADLER32_SIMD_SSSE3) #include uint32_t ZLIB_INTERNAL adler32_simd_( /* SSSE3 */ uint32_t adler, const unsigned char *buf, z_size_t len) { /* * Split Adler-32 into component sums. */ uint32_t s1 = adler & 0xffff; uint32_t s2 = adler >> 16; /* * Process the data in blocks. */ const unsigned BLOCK_SIZE = 1 << 5; z_size_t blocks = len / BLOCK_SIZE; len -= blocks * BLOCK_SIZE; while (blocks) { unsigned n = NMAX / BLOCK_SIZE; /* The NMAX constraint. */ if (n > blocks) n = (unsigned) blocks; blocks -= n; const __m128i tap1 = _mm_setr_epi8(32,31,30,29,28,27,26,25,24,23,22,21,20,19,18,17); const __m128i tap2 = _mm_setr_epi8(16,15,14,13,12,11,10, 9, 8, 7, 6, 5, 4, 3, 2, 1); const __m128i zero = _mm_setr_epi8( 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); const __m128i ones = _mm_set_epi16( 1, 1, 1, 1, 1, 1, 1, 1); /* * Process n blocks of data. At most NMAX data bytes can be * processed before s2 must be reduced modulo BASE. */ __m128i v_ps = _mm_set_epi32(0, 0, 0, s1 * n); __m128i v_s2 = _mm_set_epi32(0, 0, 0, s2); __m128i v_s1 = _mm_set_epi32(0, 0, 0, 0); do { /* * Load 32 input bytes. */ const __m128i bytes1 = _mm_loadu_si128((__m128i*)(buf)); const __m128i bytes2 = _mm_loadu_si128((__m128i*)(buf + 16)); /* * Add previous block byte sum to v_ps. */ v_ps = _mm_add_epi32(v_ps, v_s1); /* * Horizontally add the bytes for s1, multiply-adds the * bytes by [ 32, 31, 30, ... ] for s2. */ v_s1 = _mm_add_epi32(v_s1, _mm_sad_epu8(bytes1, zero)); const __m128i mad1 = _mm_maddubs_epi16(bytes1, tap1); v_s2 = _mm_add_epi32(v_s2, _mm_madd_epi16(mad1, ones)); v_s1 = _mm_add_epi32(v_s1, _mm_sad_epu8(bytes2, zero)); const __m128i mad2 = _mm_maddubs_epi16(bytes2, tap2); v_s2 = _mm_add_epi32(v_s2, _mm_madd_epi16(mad2, ones)); buf += BLOCK_SIZE; } while (--n); v_s2 = _mm_add_epi32(v_s2, _mm_slli_epi32(v_ps, 5)); /* * Sum epi32 ints v_s1(s2) and accumulate in s1(s2). */ #define S23O1 _MM_SHUFFLE(2,3,0,1) /* A B C D -> B A D C */ #define S1O32 _MM_SHUFFLE(1,0,3,2) /* A B C D -> C D A B */ v_s1 = _mm_add_epi32(v_s1, _mm_shuffle_epi32(v_s1, S23O1)); v_s1 = _mm_add_epi32(v_s1, _mm_shuffle_epi32(v_s1, S1O32)); s1 += _mm_cvtsi128_si32(v_s1); v_s2 = _mm_add_epi32(v_s2, _mm_shuffle_epi32(v_s2, S23O1)); v_s2 = _mm_add_epi32(v_s2, _mm_shuffle_epi32(v_s2, S1O32)); s2 = _mm_cvtsi128_si32(v_s2); #undef S23O1 #undef S1O32 /* * Reduce. */ s1 %= BASE; s2 %= BASE; } /* * Handle leftover data. */ if (len) { if (len >= 16) { s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); len -= 16; } while (len--) { s2 += (s1 += *buf++); } if (s1 >= BASE) s1 -= BASE; s2 %= BASE; } /* * Return the recombined sums. */ return s1 | (s2 << 16); } #elif defined(ADLER32_SIMD_NEON) #include uint32_t ZLIB_INTERNAL adler32_simd_( /* NEON */ uint32_t adler, const unsigned char *buf, z_size_t len) { /* * Split Adler-32 into component sums. */ uint32_t s1 = adler & 0xffff; uint32_t s2 = adler >> 16; /* * Serially compute s1 & s2, until the data is 16-byte aligned. */ if ((uintptr_t)buf & 15) { while ((uintptr_t)buf & 15) { s2 += (s1 += *buf++); --len; } if (s1 >= BASE) s1 -= BASE; s2 %= BASE; } /* * Process the data in blocks. */ const unsigned BLOCK_SIZE = 1 << 5; z_size_t blocks = len / BLOCK_SIZE; len -= blocks * BLOCK_SIZE; while (blocks) { unsigned n = NMAX / BLOCK_SIZE; /* The NMAX constraint. */ if (n > blocks) n = (unsigned) blocks; blocks -= n; /* * Process n blocks of data. At most NMAX data bytes can be * processed before s2 must be reduced modulo BASE. */ uint32x4_t v_s2 = (uint32x4_t) { 0, 0, 0, s1 * n }; uint32x4_t v_s1 = (uint32x4_t) { 0, 0, 0, 0 }; uint16x8_t v_column_sum_1 = vdupq_n_u16(0); uint16x8_t v_column_sum_2 = vdupq_n_u16(0); uint16x8_t v_column_sum_3 = vdupq_n_u16(0); uint16x8_t v_column_sum_4 = vdupq_n_u16(0); do { /* * Load 32 input bytes. */ const uint8x16_t bytes1 = vld1q_u8((uint8_t*)(buf)); const uint8x16_t bytes2 = vld1q_u8((uint8_t*)(buf + 16)); /* * Add previous block byte sum to v_s2. */ v_s2 = vaddq_u32(v_s2, v_s1); /* * Horizontally add the bytes for s1. */ v_s1 = vpadalq_u16(v_s1, vpadalq_u8(vpaddlq_u8(bytes1), bytes2)); /* * Vertically add the bytes for s2. */ v_column_sum_1 = vaddw_u8(v_column_sum_1, vget_low_u8 (bytes1)); v_column_sum_2 = vaddw_u8(v_column_sum_2, vget_high_u8(bytes1)); v_column_sum_3 = vaddw_u8(v_column_sum_3, vget_low_u8 (bytes2)); v_column_sum_4 = vaddw_u8(v_column_sum_4, vget_high_u8(bytes2)); buf += BLOCK_SIZE; } while (--n); v_s2 = vshlq_n_u32(v_s2, 5); /* * Multiply-add bytes by [ 32, 31, 30, ... ] for s2. */ v_s2 = vmlal_u16(v_s2, vget_low_u16 (v_column_sum_1), (uint16x4_t) { 32, 31, 30, 29 }); v_s2 = vmlal_u16(v_s2, vget_high_u16(v_column_sum_1), (uint16x4_t) { 28, 27, 26, 25 }); v_s2 = vmlal_u16(v_s2, vget_low_u16 (v_column_sum_2), (uint16x4_t) { 24, 23, 22, 21 }); v_s2 = vmlal_u16(v_s2, vget_high_u16(v_column_sum_2), (uint16x4_t) { 20, 19, 18, 17 }); v_s2 = vmlal_u16(v_s2, vget_low_u16 (v_column_sum_3), (uint16x4_t) { 16, 15, 14, 13 }); v_s2 = vmlal_u16(v_s2, vget_high_u16(v_column_sum_3), (uint16x4_t) { 12, 11, 10, 9 }); v_s2 = vmlal_u16(v_s2, vget_low_u16 (v_column_sum_4), (uint16x4_t) { 8, 7, 6, 5 }); v_s2 = vmlal_u16(v_s2, vget_high_u16(v_column_sum_4), (uint16x4_t) { 4, 3, 2, 1 }); /* * Sum epi32 ints v_s1(s2) and accumulate in s1(s2). */ uint32x2_t sum1 = vpadd_u32(vget_low_u32(v_s1), vget_high_u32(v_s1)); uint32x2_t sum2 = vpadd_u32(vget_low_u32(v_s2), vget_high_u32(v_s2)); uint32x2_t s1s2 = vpadd_u32(sum1, sum2); s1 += vget_lane_u32(s1s2, 0); s2 += vget_lane_u32(s1s2, 1); /* * Reduce. */ s1 %= BASE; s2 %= BASE; } /* * Handle leftover data. */ if (len) { if (len >= 16) { s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); s2 += (s1 += *buf++); len -= 16; } while (len--) { s2 += (s1 += *buf++); } if (s1 >= BASE) s1 -= BASE; s2 %= BASE; } /* * Return the recombined sums. */ return s1 | (s2 << 16); } #endif /* ADLER32_SIMD_SSSE3 */