Noel Gordon | 17bbb3d | 2017-09-29 19:44:25 +0000 | [diff] [blame] | 1 | /* adler32_simd.c |
| 2 | * |
| 3 | * Copyright 2017 The Chromium Authors. All rights reserved. |
| 4 | * Use of this source code is governed by a BSD-style license that can be |
| 5 | * found in the Chromium source repository LICENSE file. |
| 6 | * |
| 7 | * Per http://en.wikipedia.org/wiki/Adler-32 the adler32 A value (aka s1) is |
| 8 | * the sum of N input data bytes D1 ... DN, |
| 9 | * |
| 10 | * A = A0 + D1 + D2 + ... + DN |
| 11 | * |
| 12 | * where A0 is the initial value. |
| 13 | * |
| 14 | * SSE2 _mm_sad_epu8() can be used for byte sums (see http://bit.ly/2wpUOeD, |
| 15 | * for example) and accumulating the byte sums can use SSE shuffle-adds (see |
| 16 | * the "Integer" section of http://bit.ly/2erPT8t for details). Arm NEON has |
| 17 | * similar instructions. |
| 18 | * |
| 19 | * The adler32 B value (aka s2) sums the A values from each step: |
| 20 | * |
| 21 | * B0 + (A0 + D1) + (A0 + D1 + D2) + ... + (A0 + D1 + D2 + ... + DN) or |
| 22 | * |
| 23 | * B0 + N.A0 + N.D1 + (N-1).D2 + (N-2).D3 + ... + (N-(N-1)).DN |
| 24 | * |
| 25 | * B0 being the initial value. For 32 bytes (ideal for garden-variety SIMD): |
| 26 | * |
| 27 | * B = B0 + 32.A0 + [D1 D2 D3 ... D32] x [32 31 30 ... 1]. |
| 28 | * |
| 29 | * Adjacent blocks of 32 input bytes can be iterated with the expressions to |
| 30 | * compute the adler32 s1 s2 of M >> 32 input bytes [1]. |
| 31 | * |
| 32 | * As M grows, the s1 s2 sums grow. If left unchecked, they would eventually |
| 33 | * overflow the precision of their integer representation (bad). However, s1 |
| 34 | * and s2 also need to be computed modulo the adler BASE value (reduced). If |
| 35 | * at most NMAX bytes are processed before a reduce, s1 s2 _cannot_ overflow |
| 36 | * a uint32_t type (the NMAX constraint) [2]. |
| 37 | * |
| 38 | * [1] the iterative equations for s2 contain constant factors; these can be |
| 39 | * hoisted from the n-blocks do loop of the SIMD code. |
| 40 | * |
| 41 | * [2] zlib adler32_z() uses this fact to implement NMAX-block-based updates |
| 42 | * of the adler s1 s2 of uint32_t type (see adler32.c). |
| 43 | */ |
| 44 | |
| 45 | #include "adler32_simd.h" |
| 46 | |
| 47 | /* Definitions from adler32.c: largest prime smaller than 65536 */ |
| 48 | #define BASE 65521U |
| 49 | /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */ |
| 50 | #define NMAX 5552 |
| 51 | |
| 52 | #if defined(ADLER32_SIMD_SSSE3) |
| 53 | |
| 54 | #include <tmmintrin.h> |
| 55 | |
| 56 | uint32_t ZLIB_INTERNAL adler32_simd_( /* SSSE3 */ |
| 57 | uint32_t adler, |
| 58 | const unsigned char *buf, |
| 59 | z_size_t len) |
| 60 | { |
| 61 | /* |
| 62 | * Split Adler-32 into component sums. |
| 63 | */ |
| 64 | uint32_t s1 = adler & 0xffff; |
| 65 | uint32_t s2 = adler >> 16; |
| 66 | |
| 67 | /* |
| 68 | * Process the data in blocks. |
| 69 | */ |
| 70 | const unsigned BLOCK_SIZE = 1 << 5; |
| 71 | |
| 72 | z_size_t blocks = len / BLOCK_SIZE; |
| 73 | len -= blocks * BLOCK_SIZE; |
| 74 | |
| 75 | while (blocks) |
| 76 | { |
| 77 | unsigned n = NMAX / BLOCK_SIZE; /* The NMAX constraint. */ |
| 78 | if (n > blocks) |
Noel Gordon | e1769ae | 2017-12-20 07:42:57 +0000 | [diff] [blame] | 79 | n = (unsigned) blocks; |
Noel Gordon | 17bbb3d | 2017-09-29 19:44:25 +0000 | [diff] [blame] | 80 | blocks -= n; |
| 81 | |
| 82 | const __m128i tap1 = |
| 83 | _mm_setr_epi8(32,31,30,29,28,27,26,25,24,23,22,21,20,19,18,17); |
| 84 | const __m128i tap2 = |
| 85 | _mm_setr_epi8(16,15,14,13,12,11,10, 9, 8, 7, 6, 5, 4, 3, 2, 1); |
| 86 | const __m128i zero = |
| 87 | _mm_setr_epi8( 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0); |
| 88 | const __m128i ones = |
| 89 | _mm_set_epi16( 1, 1, 1, 1, 1, 1, 1, 1); |
| 90 | |
| 91 | /* |
| 92 | * Process n blocks of data. At most NMAX data bytes can be |
| 93 | * processed before s2 must be reduced modulo BASE. |
| 94 | */ |
| 95 | __m128i v_ps = _mm_set_epi32(0, 0, 0, s1 * n); |
| 96 | __m128i v_s2 = _mm_set_epi32(0, 0, 0, s2); |
| 97 | __m128i v_s1 = _mm_set_epi32(0, 0, 0, 0); |
| 98 | |
| 99 | do { |
| 100 | /* |
| 101 | * Load 32 input bytes. |
| 102 | */ |
| 103 | const __m128i bytes1 = _mm_loadu_si128((__m128i*)(buf)); |
| 104 | const __m128i bytes2 = _mm_loadu_si128((__m128i*)(buf + 16)); |
| 105 | |
| 106 | /* |
| 107 | * Add previous block byte sum to v_ps. |
| 108 | */ |
| 109 | v_ps = _mm_add_epi32(v_ps, v_s1); |
| 110 | |
| 111 | /* |
| 112 | * Horizontally add the bytes for s1, multiply-adds the |
| 113 | * bytes by [ 32, 31, 30, ... ] for s2. |
| 114 | */ |
| 115 | v_s1 = _mm_add_epi32(v_s1, _mm_sad_epu8(bytes1, zero)); |
| 116 | const __m128i mad1 = _mm_maddubs_epi16(bytes1, tap1); |
| 117 | v_s2 = _mm_add_epi32(v_s2, _mm_madd_epi16(mad1, ones)); |
| 118 | |
| 119 | v_s1 = _mm_add_epi32(v_s1, _mm_sad_epu8(bytes2, zero)); |
| 120 | const __m128i mad2 = _mm_maddubs_epi16(bytes2, tap2); |
| 121 | v_s2 = _mm_add_epi32(v_s2, _mm_madd_epi16(mad2, ones)); |
| 122 | |
| 123 | buf += BLOCK_SIZE; |
| 124 | |
| 125 | } while (--n); |
| 126 | |
| 127 | v_s2 = _mm_add_epi32(v_s2, _mm_slli_epi32(v_ps, 5)); |
| 128 | |
| 129 | /* |
| 130 | * Sum epi32 ints v_s1(s2) and accumulate in s1(s2). |
| 131 | */ |
| 132 | |
| 133 | #define S23O1 _MM_SHUFFLE(2,3,0,1) /* A B C D -> B A D C */ |
| 134 | #define S1O32 _MM_SHUFFLE(1,0,3,2) /* A B C D -> C D A B */ |
| 135 | |
| 136 | v_s1 = _mm_add_epi32(v_s1, _mm_shuffle_epi32(v_s1, S23O1)); |
| 137 | v_s1 = _mm_add_epi32(v_s1, _mm_shuffle_epi32(v_s1, S1O32)); |
| 138 | |
| 139 | s1 += _mm_cvtsi128_si32(v_s1); |
| 140 | |
| 141 | v_s2 = _mm_add_epi32(v_s2, _mm_shuffle_epi32(v_s2, S23O1)); |
| 142 | v_s2 = _mm_add_epi32(v_s2, _mm_shuffle_epi32(v_s2, S1O32)); |
| 143 | |
| 144 | s2 = _mm_cvtsi128_si32(v_s2); |
| 145 | |
| 146 | #undef S23O1 |
| 147 | #undef S1O32 |
| 148 | |
| 149 | /* |
| 150 | * Reduce. |
| 151 | */ |
| 152 | s1 %= BASE; |
| 153 | s2 %= BASE; |
| 154 | } |
| 155 | |
| 156 | /* |
| 157 | * Handle leftover data. |
| 158 | */ |
| 159 | if (len) { |
| 160 | if (len >= 16) { |
| 161 | s2 += (s1 += *buf++); |
| 162 | s2 += (s1 += *buf++); |
| 163 | s2 += (s1 += *buf++); |
| 164 | s2 += (s1 += *buf++); |
| 165 | |
| 166 | s2 += (s1 += *buf++); |
| 167 | s2 += (s1 += *buf++); |
| 168 | s2 += (s1 += *buf++); |
| 169 | s2 += (s1 += *buf++); |
| 170 | |
| 171 | s2 += (s1 += *buf++); |
| 172 | s2 += (s1 += *buf++); |
| 173 | s2 += (s1 += *buf++); |
| 174 | s2 += (s1 += *buf++); |
| 175 | |
| 176 | s2 += (s1 += *buf++); |
| 177 | s2 += (s1 += *buf++); |
| 178 | s2 += (s1 += *buf++); |
| 179 | s2 += (s1 += *buf++); |
| 180 | |
| 181 | len -= 16; |
| 182 | } |
| 183 | |
| 184 | while (len--) { |
| 185 | s2 += (s1 += *buf++); |
| 186 | } |
| 187 | |
| 188 | if (s1 >= BASE) |
| 189 | s1 -= BASE; |
| 190 | s2 %= BASE; |
| 191 | } |
| 192 | |
| 193 | /* |
| 194 | * Return the recombined sums. |
| 195 | */ |
| 196 | return s1 | (s2 << 16); |
| 197 | } |
| 198 | |
| 199 | #elif defined(ADLER32_SIMD_NEON) |
| 200 | |
| 201 | #include <arm_neon.h> |
| 202 | |
| 203 | uint32_t ZLIB_INTERNAL adler32_simd_( /* NEON */ |
| 204 | uint32_t adler, |
| 205 | const unsigned char *buf, |
| 206 | z_size_t len) |
| 207 | { |
| 208 | /* |
| 209 | * Split Adler-32 into component sums. |
| 210 | */ |
| 211 | uint32_t s1 = adler & 0xffff; |
| 212 | uint32_t s2 = adler >> 16; |
| 213 | |
| 214 | /* |
| 215 | * Serially compute s1 & s2, until the data is 16-byte aligned. |
| 216 | */ |
| 217 | if ((uintptr_t)buf & 15) { |
| 218 | while ((uintptr_t)buf & 15) { |
| 219 | s2 += (s1 += *buf++); |
| 220 | --len; |
| 221 | } |
| 222 | |
| 223 | if (s1 >= BASE) |
| 224 | s1 -= BASE; |
| 225 | s2 %= BASE; |
| 226 | } |
| 227 | |
| 228 | /* |
| 229 | * Process the data in blocks. |
| 230 | */ |
| 231 | const unsigned BLOCK_SIZE = 1 << 5; |
| 232 | |
| 233 | z_size_t blocks = len / BLOCK_SIZE; |
| 234 | len -= blocks * BLOCK_SIZE; |
| 235 | |
| 236 | while (blocks) |
| 237 | { |
| 238 | unsigned n = NMAX / BLOCK_SIZE; /* The NMAX constraint. */ |
| 239 | if (n > blocks) |
Noel Gordon | e1769ae | 2017-12-20 07:42:57 +0000 | [diff] [blame] | 240 | n = (unsigned) blocks; |
Noel Gordon | 17bbb3d | 2017-09-29 19:44:25 +0000 | [diff] [blame] | 241 | blocks -= n; |
| 242 | |
| 243 | /* |
| 244 | * Process n blocks of data. At most NMAX data bytes can be |
| 245 | * processed before s2 must be reduced modulo BASE. |
| 246 | */ |
| 247 | uint32x4_t v_s2 = (uint32x4_t) { 0, 0, 0, s1 * n }; |
| 248 | uint32x4_t v_s1 = (uint32x4_t) { 0, 0, 0, 0 }; |
| 249 | |
| 250 | uint16x8_t v_column_sum_1 = vdupq_n_u16(0); |
| 251 | uint16x8_t v_column_sum_2 = vdupq_n_u16(0); |
| 252 | uint16x8_t v_column_sum_3 = vdupq_n_u16(0); |
| 253 | uint16x8_t v_column_sum_4 = vdupq_n_u16(0); |
| 254 | |
| 255 | do { |
| 256 | /* |
| 257 | * Load 32 input bytes. |
| 258 | */ |
| 259 | const uint8x16_t bytes1 = vld1q_u8((uint8_t*)(buf)); |
| 260 | const uint8x16_t bytes2 = vld1q_u8((uint8_t*)(buf + 16)); |
| 261 | |
| 262 | /* |
| 263 | * Add previous block byte sum to v_s2. |
| 264 | */ |
| 265 | v_s2 = vaddq_u32(v_s2, v_s1); |
| 266 | |
| 267 | /* |
| 268 | * Horizontally add the bytes for s1. |
| 269 | */ |
| 270 | v_s1 = vpadalq_u16(v_s1, vpadalq_u8(vpaddlq_u8(bytes1), bytes2)); |
| 271 | |
| 272 | /* |
| 273 | * Vertically add the bytes for s2. |
| 274 | */ |
| 275 | v_column_sum_1 = vaddw_u8(v_column_sum_1, vget_low_u8 (bytes1)); |
| 276 | v_column_sum_2 = vaddw_u8(v_column_sum_2, vget_high_u8(bytes1)); |
| 277 | v_column_sum_3 = vaddw_u8(v_column_sum_3, vget_low_u8 (bytes2)); |
| 278 | v_column_sum_4 = vaddw_u8(v_column_sum_4, vget_high_u8(bytes2)); |
| 279 | |
| 280 | buf += BLOCK_SIZE; |
| 281 | |
| 282 | } while (--n); |
| 283 | |
| 284 | v_s2 = vshlq_n_u32(v_s2, 5); |
| 285 | |
| 286 | /* |
| 287 | * Multiply-add bytes by [ 32, 31, 30, ... ] for s2. |
| 288 | */ |
| 289 | v_s2 = vmlal_u16(v_s2, vget_low_u16 (v_column_sum_1), |
| 290 | (uint16x4_t) { 32, 31, 30, 29 }); |
| 291 | v_s2 = vmlal_u16(v_s2, vget_high_u16(v_column_sum_1), |
| 292 | (uint16x4_t) { 28, 27, 26, 25 }); |
| 293 | v_s2 = vmlal_u16(v_s2, vget_low_u16 (v_column_sum_2), |
| 294 | (uint16x4_t) { 24, 23, 22, 21 }); |
| 295 | v_s2 = vmlal_u16(v_s2, vget_high_u16(v_column_sum_2), |
| 296 | (uint16x4_t) { 20, 19, 18, 17 }); |
| 297 | v_s2 = vmlal_u16(v_s2, vget_low_u16 (v_column_sum_3), |
| 298 | (uint16x4_t) { 16, 15, 14, 13 }); |
| 299 | v_s2 = vmlal_u16(v_s2, vget_high_u16(v_column_sum_3), |
| 300 | (uint16x4_t) { 12, 11, 10, 9 }); |
| 301 | v_s2 = vmlal_u16(v_s2, vget_low_u16 (v_column_sum_4), |
| 302 | (uint16x4_t) { 8, 7, 6, 5 }); |
| 303 | v_s2 = vmlal_u16(v_s2, vget_high_u16(v_column_sum_4), |
| 304 | (uint16x4_t) { 4, 3, 2, 1 }); |
| 305 | |
| 306 | /* |
| 307 | * Sum epi32 ints v_s1(s2) and accumulate in s1(s2). |
| 308 | */ |
| 309 | uint32x2_t sum1 = vpadd_u32(vget_low_u32(v_s1), vget_high_u32(v_s1)); |
| 310 | uint32x2_t sum2 = vpadd_u32(vget_low_u32(v_s2), vget_high_u32(v_s2)); |
| 311 | uint32x2_t s1s2 = vpadd_u32(sum1, sum2); |
| 312 | |
| 313 | s1 += vget_lane_u32(s1s2, 0); |
| 314 | s2 += vget_lane_u32(s1s2, 1); |
| 315 | |
| 316 | /* |
| 317 | * Reduce. |
| 318 | */ |
| 319 | s1 %= BASE; |
| 320 | s2 %= BASE; |
| 321 | } |
| 322 | |
| 323 | /* |
| 324 | * Handle leftover data. |
| 325 | */ |
| 326 | if (len) { |
| 327 | if (len >= 16) { |
| 328 | s2 += (s1 += *buf++); |
| 329 | s2 += (s1 += *buf++); |
| 330 | s2 += (s1 += *buf++); |
| 331 | s2 += (s1 += *buf++); |
| 332 | |
| 333 | s2 += (s1 += *buf++); |
| 334 | s2 += (s1 += *buf++); |
| 335 | s2 += (s1 += *buf++); |
| 336 | s2 += (s1 += *buf++); |
| 337 | |
| 338 | s2 += (s1 += *buf++); |
| 339 | s2 += (s1 += *buf++); |
| 340 | s2 += (s1 += *buf++); |
| 341 | s2 += (s1 += *buf++); |
| 342 | |
| 343 | s2 += (s1 += *buf++); |
| 344 | s2 += (s1 += *buf++); |
| 345 | s2 += (s1 += *buf++); |
| 346 | s2 += (s1 += *buf++); |
| 347 | |
| 348 | len -= 16; |
| 349 | } |
| 350 | |
| 351 | while (len--) { |
| 352 | s2 += (s1 += *buf++); |
| 353 | } |
| 354 | |
| 355 | if (s1 >= BASE) |
| 356 | s1 -= BASE; |
| 357 | s2 %= BASE; |
| 358 | } |
| 359 | |
| 360 | /* |
| 361 | * Return the recombined sums. |
| 362 | */ |
| 363 | return s1 | (s2 << 16); |
| 364 | } |
| 365 | |
| 366 | #endif /* ADLER32_SIMD_SSSE3 */ |