1 /* 2 * Copyright (c) Yann Collet, Facebook, Inc. 3 * All rights reserved. 4 * 5 * This source code is licensed under both the BSD-style license (found in the 6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 7 * in the COPYING file in the root directory of this source tree). 8 * You may select, at your option, one of the above-listed licenses. 9 */ 10 11 /* zstd_decompress_block : 12 * this module takes care of decompressing _compressed_ block */ 13 14 /*-******************************************************* 15 * Dependencies 16 *********************************************************/ 17 #include "../common/zstd_deps.h" /* ZSTD_memcpy, ZSTD_memmove, ZSTD_memset */ 18 #include "../common/compiler.h" /* prefetch */ 19 #include "../common/cpu.h" /* bmi2 */ 20 #include "../common/mem.h" /* low level memory routines */ 21 #define FSE_STATIC_LINKING_ONLY 22 #include "../common/fse.h" 23 #define HUF_STATIC_LINKING_ONLY 24 #include "../common/huf.h" 25 #include "../common/zstd_internal.h" 26 #include "zstd_decompress_internal.h" /* ZSTD_DCtx */ 27 #include "zstd_ddict.h" /* ZSTD_DDictDictContent */ 28 #include "zstd_decompress_block.h" 29 30 /*_******************************************************* 31 * Macros 32 **********************************************************/ 33 34 /* These two optional macros force the use one way or another of the two 35 * ZSTD_decompressSequences implementations. You can't force in both directions 36 * at the same time. 37 */ 38 #if defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 39 defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 40 #error "Cannot force the use of the short and the long ZSTD_decompressSequences variants!" 41 #endif 42 43 44 /*_******************************************************* 45 * Memory operations 46 **********************************************************/ 47 static void ZSTD_copy4(void* dst, const void* src) { ZSTD_memcpy(dst, src, 4); } 48 49 50 /*-************************************************************* 51 * Block decoding 52 ***************************************************************/ 53 54 /*! ZSTD_getcBlockSize() : 55 * Provides the size of compressed block from block header `src` */ 56 size_t ZSTD_getcBlockSize(const void* src, size_t srcSize, 57 blockProperties_t* bpPtr) 58 { 59 RETURN_ERROR_IF(srcSize < ZSTD_blockHeaderSize, srcSize_wrong, ""); 60 61 { U32 const cBlockHeader = MEM_readLE24(src); 62 U32 const cSize = cBlockHeader >> 3; 63 bpPtr->lastBlock = cBlockHeader & 1; 64 bpPtr->blockType = (blockType_e)((cBlockHeader >> 1) & 3); 65 bpPtr->origSize = cSize; /* only useful for RLE */ 66 if (bpPtr->blockType == bt_rle) return 1; 67 RETURN_ERROR_IF(bpPtr->blockType == bt_reserved, corruption_detected, ""); 68 return cSize; 69 } 70 } 71 72 73 /* Hidden declaration for fullbench */ 74 size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx, 75 const void* src, size_t srcSize); 76 /*! ZSTD_decodeLiteralsBlock() : 77 * @return : nb of bytes read from src (< srcSize ) 78 * note : symbol not declared but exposed for fullbench */ 79 size_t ZSTD_decodeLiteralsBlock(ZSTD_DCtx* dctx, 80 const void* src, size_t srcSize) /* note : srcSize < BLOCKSIZE */ 81 { 82 DEBUGLOG(5, "ZSTD_decodeLiteralsBlock"); 83 RETURN_ERROR_IF(srcSize < MIN_CBLOCK_SIZE, corruption_detected, ""); 84 85 { const BYTE* const istart = (const BYTE*) src; 86 symbolEncodingType_e const litEncType = (symbolEncodingType_e)(istart[0] & 3); 87 88 switch(litEncType) 89 { 90 case set_repeat: 91 DEBUGLOG(5, "set_repeat flag : re-using stats from previous compressed literals block"); 92 RETURN_ERROR_IF(dctx->litEntropy==0, dictionary_corrupted, ""); 93 ZSTD_FALLTHROUGH; 94 95 case set_compressed: 96 RETURN_ERROR_IF(srcSize < 5, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need up to 5 for case 3"); 97 { size_t lhSize, litSize, litCSize; 98 U32 singleStream=0; 99 U32 const lhlCode = (istart[0] >> 2) & 3; 100 U32 const lhc = MEM_readLE32(istart); 101 size_t hufSuccess; 102 switch(lhlCode) 103 { 104 case 0: case 1: default: /* note : default is impossible, since lhlCode into [0..3] */ 105 /* 2 - 2 - 10 - 10 */ 106 singleStream = !lhlCode; 107 lhSize = 3; 108 litSize = (lhc >> 4) & 0x3FF; 109 litCSize = (lhc >> 14) & 0x3FF; 110 break; 111 case 2: 112 /* 2 - 2 - 14 - 14 */ 113 lhSize = 4; 114 litSize = (lhc >> 4) & 0x3FFF; 115 litCSize = lhc >> 18; 116 break; 117 case 3: 118 /* 2 - 2 - 18 - 18 */ 119 lhSize = 5; 120 litSize = (lhc >> 4) & 0x3FFFF; 121 litCSize = (lhc >> 22) + ((size_t)istart[4] << 10); 122 break; 123 } 124 RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, ""); 125 RETURN_ERROR_IF(litCSize + lhSize > srcSize, corruption_detected, ""); 126 127 /* prefetch huffman table if cold */ 128 if (dctx->ddictIsCold && (litSize > 768 /* heuristic */)) { 129 PREFETCH_AREA(dctx->HUFptr, sizeof(dctx->entropy.hufTable)); 130 } 131 132 if (litEncType==set_repeat) { 133 if (singleStream) { 134 hufSuccess = HUF_decompress1X_usingDTable_bmi2( 135 dctx->litBuffer, litSize, istart+lhSize, litCSize, 136 dctx->HUFptr, dctx->bmi2); 137 } else { 138 hufSuccess = HUF_decompress4X_usingDTable_bmi2( 139 dctx->litBuffer, litSize, istart+lhSize, litCSize, 140 dctx->HUFptr, dctx->bmi2); 141 } 142 } else { 143 if (singleStream) { 144 #if defined(HUF_FORCE_DECOMPRESS_X2) 145 hufSuccess = HUF_decompress1X_DCtx_wksp( 146 dctx->entropy.hufTable, dctx->litBuffer, litSize, 147 istart+lhSize, litCSize, dctx->workspace, 148 sizeof(dctx->workspace)); 149 #else 150 hufSuccess = HUF_decompress1X1_DCtx_wksp_bmi2( 151 dctx->entropy.hufTable, dctx->litBuffer, litSize, 152 istart+lhSize, litCSize, dctx->workspace, 153 sizeof(dctx->workspace), dctx->bmi2); 154 #endif 155 } else { 156 hufSuccess = HUF_decompress4X_hufOnly_wksp_bmi2( 157 dctx->entropy.hufTable, dctx->litBuffer, litSize, 158 istart+lhSize, litCSize, dctx->workspace, 159 sizeof(dctx->workspace), dctx->bmi2); 160 } 161 } 162 163 RETURN_ERROR_IF(HUF_isError(hufSuccess), corruption_detected, ""); 164 165 dctx->litPtr = dctx->litBuffer; 166 dctx->litSize = litSize; 167 dctx->litEntropy = 1; 168 if (litEncType==set_compressed) dctx->HUFptr = dctx->entropy.hufTable; 169 ZSTD_memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH); 170 return litCSize + lhSize; 171 } 172 173 case set_basic: 174 { size_t litSize, lhSize; 175 U32 const lhlCode = ((istart[0]) >> 2) & 3; 176 switch(lhlCode) 177 { 178 case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */ 179 lhSize = 1; 180 litSize = istart[0] >> 3; 181 break; 182 case 1: 183 lhSize = 2; 184 litSize = MEM_readLE16(istart) >> 4; 185 break; 186 case 3: 187 lhSize = 3; 188 litSize = MEM_readLE24(istart) >> 4; 189 break; 190 } 191 192 if (lhSize+litSize+WILDCOPY_OVERLENGTH > srcSize) { /* risk reading beyond src buffer with wildcopy */ 193 RETURN_ERROR_IF(litSize+lhSize > srcSize, corruption_detected, ""); 194 ZSTD_memcpy(dctx->litBuffer, istart+lhSize, litSize); 195 dctx->litPtr = dctx->litBuffer; 196 dctx->litSize = litSize; 197 ZSTD_memset(dctx->litBuffer + dctx->litSize, 0, WILDCOPY_OVERLENGTH); 198 return lhSize+litSize; 199 } 200 /* direct reference into compressed stream */ 201 dctx->litPtr = istart+lhSize; 202 dctx->litSize = litSize; 203 return lhSize+litSize; 204 } 205 206 case set_rle: 207 { U32 const lhlCode = ((istart[0]) >> 2) & 3; 208 size_t litSize, lhSize; 209 switch(lhlCode) 210 { 211 case 0: case 2: default: /* note : default is impossible, since lhlCode into [0..3] */ 212 lhSize = 1; 213 litSize = istart[0] >> 3; 214 break; 215 case 1: 216 lhSize = 2; 217 litSize = MEM_readLE16(istart) >> 4; 218 break; 219 case 3: 220 lhSize = 3; 221 litSize = MEM_readLE24(istart) >> 4; 222 RETURN_ERROR_IF(srcSize<4, corruption_detected, "srcSize >= MIN_CBLOCK_SIZE == 3; here we need lhSize+1 = 4"); 223 break; 224 } 225 RETURN_ERROR_IF(litSize > ZSTD_BLOCKSIZE_MAX, corruption_detected, ""); 226 ZSTD_memset(dctx->litBuffer, istart[lhSize], litSize + WILDCOPY_OVERLENGTH); 227 dctx->litPtr = dctx->litBuffer; 228 dctx->litSize = litSize; 229 return lhSize+1; 230 } 231 default: 232 RETURN_ERROR(corruption_detected, "impossible"); 233 } 234 } 235 } 236 237 /* Default FSE distribution tables. 238 * These are pre-calculated FSE decoding tables using default distributions as defined in specification : 239 * https://github.com/facebook/zstd/blob/release/doc/zstd_compression_format.md#default-distributions 240 * They were generated programmatically with following method : 241 * - start from default distributions, present in /lib/common/zstd_internal.h 242 * - generate tables normally, using ZSTD_buildFSETable() 243 * - printout the content of tables 244 * - pretify output, report below, test with fuzzer to ensure it's correct */ 245 246 /* Default FSE distribution table for Literal Lengths */ 247 static const ZSTD_seqSymbol LL_defaultDTable[(1<<LL_DEFAULTNORMLOG)+1] = { 248 { 1, 1, 1, LL_DEFAULTNORMLOG}, /* header : fastMode, tableLog */ 249 /* nextState, nbAddBits, nbBits, baseVal */ 250 { 0, 0, 4, 0}, { 16, 0, 4, 0}, 251 { 32, 0, 5, 1}, { 0, 0, 5, 3}, 252 { 0, 0, 5, 4}, { 0, 0, 5, 6}, 253 { 0, 0, 5, 7}, { 0, 0, 5, 9}, 254 { 0, 0, 5, 10}, { 0, 0, 5, 12}, 255 { 0, 0, 6, 14}, { 0, 1, 5, 16}, 256 { 0, 1, 5, 20}, { 0, 1, 5, 22}, 257 { 0, 2, 5, 28}, { 0, 3, 5, 32}, 258 { 0, 4, 5, 48}, { 32, 6, 5, 64}, 259 { 0, 7, 5, 128}, { 0, 8, 6, 256}, 260 { 0, 10, 6, 1024}, { 0, 12, 6, 4096}, 261 { 32, 0, 4, 0}, { 0, 0, 4, 1}, 262 { 0, 0, 5, 2}, { 32, 0, 5, 4}, 263 { 0, 0, 5, 5}, { 32, 0, 5, 7}, 264 { 0, 0, 5, 8}, { 32, 0, 5, 10}, 265 { 0, 0, 5, 11}, { 0, 0, 6, 13}, 266 { 32, 1, 5, 16}, { 0, 1, 5, 18}, 267 { 32, 1, 5, 22}, { 0, 2, 5, 24}, 268 { 32, 3, 5, 32}, { 0, 3, 5, 40}, 269 { 0, 6, 4, 64}, { 16, 6, 4, 64}, 270 { 32, 7, 5, 128}, { 0, 9, 6, 512}, 271 { 0, 11, 6, 2048}, { 48, 0, 4, 0}, 272 { 16, 0, 4, 1}, { 32, 0, 5, 2}, 273 { 32, 0, 5, 3}, { 32, 0, 5, 5}, 274 { 32, 0, 5, 6}, { 32, 0, 5, 8}, 275 { 32, 0, 5, 9}, { 32, 0, 5, 11}, 276 { 32, 0, 5, 12}, { 0, 0, 6, 15}, 277 { 32, 1, 5, 18}, { 32, 1, 5, 20}, 278 { 32, 2, 5, 24}, { 32, 2, 5, 28}, 279 { 32, 3, 5, 40}, { 32, 4, 5, 48}, 280 { 0, 16, 6,65536}, { 0, 15, 6,32768}, 281 { 0, 14, 6,16384}, { 0, 13, 6, 8192}, 282 }; /* LL_defaultDTable */ 283 284 /* Default FSE distribution table for Offset Codes */ 285 static const ZSTD_seqSymbol OF_defaultDTable[(1<<OF_DEFAULTNORMLOG)+1] = { 286 { 1, 1, 1, OF_DEFAULTNORMLOG}, /* header : fastMode, tableLog */ 287 /* nextState, nbAddBits, nbBits, baseVal */ 288 { 0, 0, 5, 0}, { 0, 6, 4, 61}, 289 { 0, 9, 5, 509}, { 0, 15, 5,32765}, 290 { 0, 21, 5,2097149}, { 0, 3, 5, 5}, 291 { 0, 7, 4, 125}, { 0, 12, 5, 4093}, 292 { 0, 18, 5,262141}, { 0, 23, 5,8388605}, 293 { 0, 5, 5, 29}, { 0, 8, 4, 253}, 294 { 0, 14, 5,16381}, { 0, 20, 5,1048573}, 295 { 0, 2, 5, 1}, { 16, 7, 4, 125}, 296 { 0, 11, 5, 2045}, { 0, 17, 5,131069}, 297 { 0, 22, 5,4194301}, { 0, 4, 5, 13}, 298 { 16, 8, 4, 253}, { 0, 13, 5, 8189}, 299 { 0, 19, 5,524285}, { 0, 1, 5, 1}, 300 { 16, 6, 4, 61}, { 0, 10, 5, 1021}, 301 { 0, 16, 5,65533}, { 0, 28, 5,268435453}, 302 { 0, 27, 5,134217725}, { 0, 26, 5,67108861}, 303 { 0, 25, 5,33554429}, { 0, 24, 5,16777213}, 304 }; /* OF_defaultDTable */ 305 306 307 /* Default FSE distribution table for Match Lengths */ 308 static const ZSTD_seqSymbol ML_defaultDTable[(1<<ML_DEFAULTNORMLOG)+1] = { 309 { 1, 1, 1, ML_DEFAULTNORMLOG}, /* header : fastMode, tableLog */ 310 /* nextState, nbAddBits, nbBits, baseVal */ 311 { 0, 0, 6, 3}, { 0, 0, 4, 4}, 312 { 32, 0, 5, 5}, { 0, 0, 5, 6}, 313 { 0, 0, 5, 8}, { 0, 0, 5, 9}, 314 { 0, 0, 5, 11}, { 0, 0, 6, 13}, 315 { 0, 0, 6, 16}, { 0, 0, 6, 19}, 316 { 0, 0, 6, 22}, { 0, 0, 6, 25}, 317 { 0, 0, 6, 28}, { 0, 0, 6, 31}, 318 { 0, 0, 6, 34}, { 0, 1, 6, 37}, 319 { 0, 1, 6, 41}, { 0, 2, 6, 47}, 320 { 0, 3, 6, 59}, { 0, 4, 6, 83}, 321 { 0, 7, 6, 131}, { 0, 9, 6, 515}, 322 { 16, 0, 4, 4}, { 0, 0, 4, 5}, 323 { 32, 0, 5, 6}, { 0, 0, 5, 7}, 324 { 32, 0, 5, 9}, { 0, 0, 5, 10}, 325 { 0, 0, 6, 12}, { 0, 0, 6, 15}, 326 { 0, 0, 6, 18}, { 0, 0, 6, 21}, 327 { 0, 0, 6, 24}, { 0, 0, 6, 27}, 328 { 0, 0, 6, 30}, { 0, 0, 6, 33}, 329 { 0, 1, 6, 35}, { 0, 1, 6, 39}, 330 { 0, 2, 6, 43}, { 0, 3, 6, 51}, 331 { 0, 4, 6, 67}, { 0, 5, 6, 99}, 332 { 0, 8, 6, 259}, { 32, 0, 4, 4}, 333 { 48, 0, 4, 4}, { 16, 0, 4, 5}, 334 { 32, 0, 5, 7}, { 32, 0, 5, 8}, 335 { 32, 0, 5, 10}, { 32, 0, 5, 11}, 336 { 0, 0, 6, 14}, { 0, 0, 6, 17}, 337 { 0, 0, 6, 20}, { 0, 0, 6, 23}, 338 { 0, 0, 6, 26}, { 0, 0, 6, 29}, 339 { 0, 0, 6, 32}, { 0, 16, 6,65539}, 340 { 0, 15, 6,32771}, { 0, 14, 6,16387}, 341 { 0, 13, 6, 8195}, { 0, 12, 6, 4099}, 342 { 0, 11, 6, 2051}, { 0, 10, 6, 1027}, 343 }; /* ML_defaultDTable */ 344 345 346 static void ZSTD_buildSeqTable_rle(ZSTD_seqSymbol* dt, U32 baseValue, U32 nbAddBits) 347 { 348 void* ptr = dt; 349 ZSTD_seqSymbol_header* const DTableH = (ZSTD_seqSymbol_header*)ptr; 350 ZSTD_seqSymbol* const cell = dt + 1; 351 352 DTableH->tableLog = 0; 353 DTableH->fastMode = 0; 354 355 cell->nbBits = 0; 356 cell->nextState = 0; 357 assert(nbAddBits < 255); 358 cell->nbAdditionalBits = (BYTE)nbAddBits; 359 cell->baseValue = baseValue; 360 } 361 362 363 /* ZSTD_buildFSETable() : 364 * generate FSE decoding table for one symbol (ll, ml or off) 365 * cannot fail if input is valid => 366 * all inputs are presumed validated at this stage */ 367 FORCE_INLINE_TEMPLATE 368 void ZSTD_buildFSETable_body(ZSTD_seqSymbol* dt, 369 const short* normalizedCounter, unsigned maxSymbolValue, 370 const U32* baseValue, const U32* nbAdditionalBits, 371 unsigned tableLog, void* wksp, size_t wkspSize) 372 { 373 ZSTD_seqSymbol* const tableDecode = dt+1; 374 U32 const maxSV1 = maxSymbolValue + 1; 375 U32 const tableSize = 1 << tableLog; 376 377 U16* symbolNext = (U16*)wksp; 378 BYTE* spread = (BYTE*)(symbolNext + MaxSeq + 1); 379 U32 highThreshold = tableSize - 1; 380 381 382 /* Sanity Checks */ 383 assert(maxSymbolValue <= MaxSeq); 384 assert(tableLog <= MaxFSELog); 385 assert(wkspSize >= ZSTD_BUILD_FSE_TABLE_WKSP_SIZE); 386 (void)wkspSize; 387 /* Init, lay down lowprob symbols */ 388 { ZSTD_seqSymbol_header DTableH; 389 DTableH.tableLog = tableLog; 390 DTableH.fastMode = 1; 391 { S16 const largeLimit= (S16)(1 << (tableLog-1)); 392 U32 s; 393 for (s=0; s<maxSV1; s++) { 394 if (normalizedCounter[s]==-1) { 395 tableDecode[highThreshold--].baseValue = s; 396 symbolNext[s] = 1; 397 } else { 398 if (normalizedCounter[s] >= largeLimit) DTableH.fastMode=0; 399 assert(normalizedCounter[s]>=0); 400 symbolNext[s] = (U16)normalizedCounter[s]; 401 } } } 402 ZSTD_memcpy(dt, &DTableH, sizeof(DTableH)); 403 } 404 405 /* Spread symbols */ 406 assert(tableSize <= 512); 407 /* Specialized symbol spreading for the case when there are 408 * no low probability (-1 count) symbols. When compressing 409 * small blocks we avoid low probability symbols to hit this 410 * case, since header decoding speed matters more. 411 */ 412 if (highThreshold == tableSize - 1) { 413 size_t const tableMask = tableSize-1; 414 size_t const step = FSE_TABLESTEP(tableSize); 415 /* First lay down the symbols in order. 416 * We use a uint64_t to lay down 8 bytes at a time. This reduces branch 417 * misses since small blocks generally have small table logs, so nearly 418 * all symbols have counts <= 8. We ensure we have 8 bytes at the end of 419 * our buffer to handle the over-write. 420 */ 421 { 422 U64 const add = 0x0101010101010101ull; 423 size_t pos = 0; 424 U64 sv = 0; 425 U32 s; 426 for (s=0; s<maxSV1; ++s, sv += add) { 427 int i; 428 int const n = normalizedCounter[s]; 429 MEM_write64(spread + pos, sv); 430 for (i = 8; i < n; i += 8) { 431 MEM_write64(spread + pos + i, sv); 432 } 433 pos += n; 434 } 435 } 436 /* Now we spread those positions across the table. 437 * The benefit of doing it in two stages is that we avoid the the 438 * variable size inner loop, which caused lots of branch misses. 439 * Now we can run through all the positions without any branch misses. 440 * We unroll the loop twice, since that is what emperically worked best. 441 */ 442 { 443 size_t position = 0; 444 size_t s; 445 size_t const unroll = 2; 446 assert(tableSize % unroll == 0); /* FSE_MIN_TABLELOG is 5 */ 447 for (s = 0; s < (size_t)tableSize; s += unroll) { 448 size_t u; 449 for (u = 0; u < unroll; ++u) { 450 size_t const uPosition = (position + (u * step)) & tableMask; 451 tableDecode[uPosition].baseValue = spread[s + u]; 452 } 453 position = (position + (unroll * step)) & tableMask; 454 } 455 assert(position == 0); 456 } 457 } else { 458 U32 const tableMask = tableSize-1; 459 U32 const step = FSE_TABLESTEP(tableSize); 460 U32 s, position = 0; 461 for (s=0; s<maxSV1; s++) { 462 int i; 463 int const n = normalizedCounter[s]; 464 for (i=0; i<n; i++) { 465 tableDecode[position].baseValue = s; 466 position = (position + step) & tableMask; 467 while (position > highThreshold) position = (position + step) & tableMask; /* lowprob area */ 468 } } 469 assert(position == 0); /* position must reach all cells once, otherwise normalizedCounter is incorrect */ 470 } 471 472 /* Build Decoding table */ 473 { 474 U32 u; 475 for (u=0; u<tableSize; u++) { 476 U32 const symbol = tableDecode[u].baseValue; 477 U32 const nextState = symbolNext[symbol]++; 478 tableDecode[u].nbBits = (BYTE) (tableLog - BIT_highbit32(nextState) ); 479 tableDecode[u].nextState = (U16) ( (nextState << tableDecode[u].nbBits) - tableSize); 480 assert(nbAdditionalBits[symbol] < 255); 481 tableDecode[u].nbAdditionalBits = (BYTE)nbAdditionalBits[symbol]; 482 tableDecode[u].baseValue = baseValue[symbol]; 483 } 484 } 485 } 486 487 /* Avoids the FORCE_INLINE of the _body() function. */ 488 static void ZSTD_buildFSETable_body_default(ZSTD_seqSymbol* dt, 489 const short* normalizedCounter, unsigned maxSymbolValue, 490 const U32* baseValue, const U32* nbAdditionalBits, 491 unsigned tableLog, void* wksp, size_t wkspSize) 492 { 493 ZSTD_buildFSETable_body(dt, normalizedCounter, maxSymbolValue, 494 baseValue, nbAdditionalBits, tableLog, wksp, wkspSize); 495 } 496 497 #if DYNAMIC_BMI2 498 TARGET_ATTRIBUTE("bmi2") static void ZSTD_buildFSETable_body_bmi2(ZSTD_seqSymbol* dt, 499 const short* normalizedCounter, unsigned maxSymbolValue, 500 const U32* baseValue, const U32* nbAdditionalBits, 501 unsigned tableLog, void* wksp, size_t wkspSize) 502 { 503 ZSTD_buildFSETable_body(dt, normalizedCounter, maxSymbolValue, 504 baseValue, nbAdditionalBits, tableLog, wksp, wkspSize); 505 } 506 #endif 507 508 void ZSTD_buildFSETable(ZSTD_seqSymbol* dt, 509 const short* normalizedCounter, unsigned maxSymbolValue, 510 const U32* baseValue, const U32* nbAdditionalBits, 511 unsigned tableLog, void* wksp, size_t wkspSize, int bmi2) 512 { 513 #if DYNAMIC_BMI2 514 if (bmi2) { 515 ZSTD_buildFSETable_body_bmi2(dt, normalizedCounter, maxSymbolValue, 516 baseValue, nbAdditionalBits, tableLog, wksp, wkspSize); 517 return; 518 } 519 #endif 520 (void)bmi2; 521 ZSTD_buildFSETable_body_default(dt, normalizedCounter, maxSymbolValue, 522 baseValue, nbAdditionalBits, tableLog, wksp, wkspSize); 523 } 524 525 526 /*! ZSTD_buildSeqTable() : 527 * @return : nb bytes read from src, 528 * or an error code if it fails */ 529 static size_t ZSTD_buildSeqTable(ZSTD_seqSymbol* DTableSpace, const ZSTD_seqSymbol** DTablePtr, 530 symbolEncodingType_e type, unsigned max, U32 maxLog, 531 const void* src, size_t srcSize, 532 const U32* baseValue, const U32* nbAdditionalBits, 533 const ZSTD_seqSymbol* defaultTable, U32 flagRepeatTable, 534 int ddictIsCold, int nbSeq, U32* wksp, size_t wkspSize, 535 int bmi2) 536 { 537 switch(type) 538 { 539 case set_rle : 540 RETURN_ERROR_IF(!srcSize, srcSize_wrong, ""); 541 RETURN_ERROR_IF((*(const BYTE*)src) > max, corruption_detected, ""); 542 { U32 const symbol = *(const BYTE*)src; 543 U32 const baseline = baseValue[symbol]; 544 U32 const nbBits = nbAdditionalBits[symbol]; 545 ZSTD_buildSeqTable_rle(DTableSpace, baseline, nbBits); 546 } 547 *DTablePtr = DTableSpace; 548 return 1; 549 case set_basic : 550 *DTablePtr = defaultTable; 551 return 0; 552 case set_repeat: 553 RETURN_ERROR_IF(!flagRepeatTable, corruption_detected, ""); 554 /* prefetch FSE table if used */ 555 if (ddictIsCold && (nbSeq > 24 /* heuristic */)) { 556 const void* const pStart = *DTablePtr; 557 size_t const pSize = sizeof(ZSTD_seqSymbol) * (SEQSYMBOL_TABLE_SIZE(maxLog)); 558 PREFETCH_AREA(pStart, pSize); 559 } 560 return 0; 561 case set_compressed : 562 { unsigned tableLog; 563 S16 norm[MaxSeq+1]; 564 size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize); 565 RETURN_ERROR_IF(FSE_isError(headerSize), corruption_detected, ""); 566 RETURN_ERROR_IF(tableLog > maxLog, corruption_detected, ""); 567 ZSTD_buildFSETable(DTableSpace, norm, max, baseValue, nbAdditionalBits, tableLog, wksp, wkspSize, bmi2); 568 *DTablePtr = DTableSpace; 569 return headerSize; 570 } 571 default : 572 assert(0); 573 RETURN_ERROR(GENERIC, "impossible"); 574 } 575 } 576 577 size_t ZSTD_decodeSeqHeaders(ZSTD_DCtx* dctx, int* nbSeqPtr, 578 const void* src, size_t srcSize) 579 { 580 const BYTE* const istart = (const BYTE*)src; 581 const BYTE* const iend = istart + srcSize; 582 const BYTE* ip = istart; 583 int nbSeq; 584 DEBUGLOG(5, "ZSTD_decodeSeqHeaders"); 585 586 /* check */ 587 RETURN_ERROR_IF(srcSize < MIN_SEQUENCES_SIZE, srcSize_wrong, ""); 588 589 /* SeqHead */ 590 nbSeq = *ip++; 591 if (!nbSeq) { 592 *nbSeqPtr=0; 593 RETURN_ERROR_IF(srcSize != 1, srcSize_wrong, ""); 594 return 1; 595 } 596 if (nbSeq > 0x7F) { 597 if (nbSeq == 0xFF) { 598 RETURN_ERROR_IF(ip+2 > iend, srcSize_wrong, ""); 599 nbSeq = MEM_readLE16(ip) + LONGNBSEQ; 600 ip+=2; 601 } else { 602 RETURN_ERROR_IF(ip >= iend, srcSize_wrong, ""); 603 nbSeq = ((nbSeq-0x80)<<8) + *ip++; 604 } 605 } 606 *nbSeqPtr = nbSeq; 607 608 /* FSE table descriptors */ 609 RETURN_ERROR_IF(ip+1 > iend, srcSize_wrong, ""); /* minimum possible size: 1 byte for symbol encoding types */ 610 { symbolEncodingType_e const LLtype = (symbolEncodingType_e)(*ip >> 6); 611 symbolEncodingType_e const OFtype = (symbolEncodingType_e)((*ip >> 4) & 3); 612 symbolEncodingType_e const MLtype = (symbolEncodingType_e)((*ip >> 2) & 3); 613 ip++; 614 615 /* Build DTables */ 616 { size_t const llhSize = ZSTD_buildSeqTable(dctx->entropy.LLTable, &dctx->LLTptr, 617 LLtype, MaxLL, LLFSELog, 618 ip, iend-ip, 619 LL_base, LL_bits, 620 LL_defaultDTable, dctx->fseEntropy, 621 dctx->ddictIsCold, nbSeq, 622 dctx->workspace, sizeof(dctx->workspace), 623 dctx->bmi2); 624 RETURN_ERROR_IF(ZSTD_isError(llhSize), corruption_detected, "ZSTD_buildSeqTable failed"); 625 ip += llhSize; 626 } 627 628 { size_t const ofhSize = ZSTD_buildSeqTable(dctx->entropy.OFTable, &dctx->OFTptr, 629 OFtype, MaxOff, OffFSELog, 630 ip, iend-ip, 631 OF_base, OF_bits, 632 OF_defaultDTable, dctx->fseEntropy, 633 dctx->ddictIsCold, nbSeq, 634 dctx->workspace, sizeof(dctx->workspace), 635 dctx->bmi2); 636 RETURN_ERROR_IF(ZSTD_isError(ofhSize), corruption_detected, "ZSTD_buildSeqTable failed"); 637 ip += ofhSize; 638 } 639 640 { size_t const mlhSize = ZSTD_buildSeqTable(dctx->entropy.MLTable, &dctx->MLTptr, 641 MLtype, MaxML, MLFSELog, 642 ip, iend-ip, 643 ML_base, ML_bits, 644 ML_defaultDTable, dctx->fseEntropy, 645 dctx->ddictIsCold, nbSeq, 646 dctx->workspace, sizeof(dctx->workspace), 647 dctx->bmi2); 648 RETURN_ERROR_IF(ZSTD_isError(mlhSize), corruption_detected, "ZSTD_buildSeqTable failed"); 649 ip += mlhSize; 650 } 651 } 652 653 return ip-istart; 654 } 655 656 657 typedef struct { 658 size_t litLength; 659 size_t matchLength; 660 size_t offset; 661 const BYTE* match; 662 } seq_t; 663 664 typedef struct { 665 size_t state; 666 const ZSTD_seqSymbol* table; 667 } ZSTD_fseState; 668 669 typedef struct { 670 BIT_DStream_t DStream; 671 ZSTD_fseState stateLL; 672 ZSTD_fseState stateOffb; 673 ZSTD_fseState stateML; 674 size_t prevOffset[ZSTD_REP_NUM]; 675 const BYTE* prefixStart; 676 const BYTE* dictEnd; 677 size_t pos; 678 } seqState_t; 679 680 /*! ZSTD_overlapCopy8() : 681 * Copies 8 bytes from ip to op and updates op and ip where ip <= op. 682 * If the offset is < 8 then the offset is spread to at least 8 bytes. 683 * 684 * Precondition: *ip <= *op 685 * Postcondition: *op - *op >= 8 686 */ 687 HINT_INLINE void ZSTD_overlapCopy8(BYTE** op, BYTE const** ip, size_t offset) { 688 assert(*ip <= *op); 689 if (offset < 8) { 690 /* close range match, overlap */ 691 static const U32 dec32table[] = { 0, 1, 2, 1, 4, 4, 4, 4 }; /* added */ 692 static const int dec64table[] = { 8, 8, 8, 7, 8, 9,10,11 }; /* subtracted */ 693 int const sub2 = dec64table[offset]; 694 (*op)[0] = (*ip)[0]; 695 (*op)[1] = (*ip)[1]; 696 (*op)[2] = (*ip)[2]; 697 (*op)[3] = (*ip)[3]; 698 *ip += dec32table[offset]; 699 ZSTD_copy4(*op+4, *ip); 700 *ip -= sub2; 701 } else { 702 ZSTD_copy8(*op, *ip); 703 } 704 *ip += 8; 705 *op += 8; 706 assert(*op - *ip >= 8); 707 } 708 709 /*! ZSTD_safecopy() : 710 * Specialized version of memcpy() that is allowed to READ up to WILDCOPY_OVERLENGTH past the input buffer 711 * and write up to 16 bytes past oend_w (op >= oend_w is allowed). 712 * This function is only called in the uncommon case where the sequence is near the end of the block. It 713 * should be fast for a single long sequence, but can be slow for several short sequences. 714 * 715 * @param ovtype controls the overlap detection 716 * - ZSTD_no_overlap: The source and destination are guaranteed to be at least WILDCOPY_VECLEN bytes apart. 717 * - ZSTD_overlap_src_before_dst: The src and dst may overlap and may be any distance apart. 718 * The src buffer must be before the dst buffer. 719 */ 720 static void ZSTD_safecopy(BYTE* op, BYTE* const oend_w, BYTE const* ip, ptrdiff_t length, ZSTD_overlap_e ovtype) { 721 ptrdiff_t const diff = op - ip; 722 BYTE* const oend = op + length; 723 724 assert((ovtype == ZSTD_no_overlap && (diff <= -8 || diff >= 8 || op >= oend_w)) || 725 (ovtype == ZSTD_overlap_src_before_dst && diff >= 0)); 726 727 if (length < 8) { 728 /* Handle short lengths. */ 729 while (op < oend) *op++ = *ip++; 730 return; 731 } 732 if (ovtype == ZSTD_overlap_src_before_dst) { 733 /* Copy 8 bytes and ensure the offset >= 8 when there can be overlap. */ 734 assert(length >= 8); 735 ZSTD_overlapCopy8(&op, &ip, diff); 736 assert(op - ip >= 8); 737 assert(op <= oend); 738 } 739 740 if (oend <= oend_w) { 741 /* No risk of overwrite. */ 742 ZSTD_wildcopy(op, ip, length, ovtype); 743 return; 744 } 745 if (op <= oend_w) { 746 /* Wildcopy until we get close to the end. */ 747 assert(oend > oend_w); 748 ZSTD_wildcopy(op, ip, oend_w - op, ovtype); 749 ip += oend_w - op; 750 op = oend_w; 751 } 752 /* Handle the leftovers. */ 753 while (op < oend) *op++ = *ip++; 754 } 755 756 /* ZSTD_execSequenceEnd(): 757 * This version handles cases that are near the end of the output buffer. It requires 758 * more careful checks to make sure there is no overflow. By separating out these hard 759 * and unlikely cases, we can speed up the common cases. 760 * 761 * NOTE: This function needs to be fast for a single long sequence, but doesn't need 762 * to be optimized for many small sequences, since those fall into ZSTD_execSequence(). 763 */ 764 FORCE_NOINLINE 765 size_t ZSTD_execSequenceEnd(BYTE* op, 766 BYTE* const oend, seq_t sequence, 767 const BYTE** litPtr, const BYTE* const litLimit, 768 const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd) 769 { 770 BYTE* const oLitEnd = op + sequence.litLength; 771 size_t const sequenceLength = sequence.litLength + sequence.matchLength; 772 const BYTE* const iLitEnd = *litPtr + sequence.litLength; 773 const BYTE* match = oLitEnd - sequence.offset; 774 BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; 775 776 /* bounds checks : careful of address space overflow in 32-bit mode */ 777 RETURN_ERROR_IF(sequenceLength > (size_t)(oend - op), dstSize_tooSmall, "last match must fit within dstBuffer"); 778 RETURN_ERROR_IF(sequence.litLength > (size_t)(litLimit - *litPtr), corruption_detected, "try to read beyond literal buffer"); 779 assert(op < op + sequenceLength); 780 assert(oLitEnd < op + sequenceLength); 781 782 /* copy literals */ 783 ZSTD_safecopy(op, oend_w, *litPtr, sequence.litLength, ZSTD_no_overlap); 784 op = oLitEnd; 785 *litPtr = iLitEnd; 786 787 /* copy Match */ 788 if (sequence.offset > (size_t)(oLitEnd - prefixStart)) { 789 /* offset beyond prefix */ 790 RETURN_ERROR_IF(sequence.offset > (size_t)(oLitEnd - virtualStart), corruption_detected, ""); 791 match = dictEnd - (prefixStart-match); 792 if (match + sequence.matchLength <= dictEnd) { 793 ZSTD_memmove(oLitEnd, match, sequence.matchLength); 794 return sequenceLength; 795 } 796 /* span extDict & currentPrefixSegment */ 797 { size_t const length1 = dictEnd - match; 798 ZSTD_memmove(oLitEnd, match, length1); 799 op = oLitEnd + length1; 800 sequence.matchLength -= length1; 801 match = prefixStart; 802 } } 803 ZSTD_safecopy(op, oend_w, match, sequence.matchLength, ZSTD_overlap_src_before_dst); 804 return sequenceLength; 805 } 806 807 HINT_INLINE 808 size_t ZSTD_execSequence(BYTE* op, 809 BYTE* const oend, seq_t sequence, 810 const BYTE** litPtr, const BYTE* const litLimit, 811 const BYTE* const prefixStart, const BYTE* const virtualStart, const BYTE* const dictEnd) 812 { 813 BYTE* const oLitEnd = op + sequence.litLength; 814 size_t const sequenceLength = sequence.litLength + sequence.matchLength; 815 BYTE* const oMatchEnd = op + sequenceLength; /* risk : address space overflow (32-bits) */ 816 BYTE* const oend_w = oend - WILDCOPY_OVERLENGTH; /* risk : address space underflow on oend=NULL */ 817 const BYTE* const iLitEnd = *litPtr + sequence.litLength; 818 const BYTE* match = oLitEnd - sequence.offset; 819 820 assert(op != NULL /* Precondition */); 821 assert(oend_w < oend /* No underflow */); 822 /* Handle edge cases in a slow path: 823 * - Read beyond end of literals 824 * - Match end is within WILDCOPY_OVERLIMIT of oend 825 * - 32-bit mode and the match length overflows 826 */ 827 if (UNLIKELY( 828 iLitEnd > litLimit || 829 oMatchEnd > oend_w || 830 (MEM_32bits() && (size_t)(oend - op) < sequenceLength + WILDCOPY_OVERLENGTH))) 831 return ZSTD_execSequenceEnd(op, oend, sequence, litPtr, litLimit, prefixStart, virtualStart, dictEnd); 832 833 /* Assumptions (everything else goes into ZSTD_execSequenceEnd()) */ 834 assert(op <= oLitEnd /* No overflow */); 835 assert(oLitEnd < oMatchEnd /* Non-zero match & no overflow */); 836 assert(oMatchEnd <= oend /* No underflow */); 837 assert(iLitEnd <= litLimit /* Literal length is in bounds */); 838 assert(oLitEnd <= oend_w /* Can wildcopy literals */); 839 assert(oMatchEnd <= oend_w /* Can wildcopy matches */); 840 841 /* Copy Literals: 842 * Split out litLength <= 16 since it is nearly always true. +1.6% on gcc-9. 843 * We likely don't need the full 32-byte wildcopy. 844 */ 845 assert(WILDCOPY_OVERLENGTH >= 16); 846 ZSTD_copy16(op, (*litPtr)); 847 if (UNLIKELY(sequence.litLength > 16)) { 848 ZSTD_wildcopy(op+16, (*litPtr)+16, sequence.litLength-16, ZSTD_no_overlap); 849 } 850 op = oLitEnd; 851 *litPtr = iLitEnd; /* update for next sequence */ 852 853 /* Copy Match */ 854 if (sequence.offset > (size_t)(oLitEnd - prefixStart)) { 855 /* offset beyond prefix -> go into extDict */ 856 RETURN_ERROR_IF(UNLIKELY(sequence.offset > (size_t)(oLitEnd - virtualStart)), corruption_detected, ""); 857 match = dictEnd + (match - prefixStart); 858 if (match + sequence.matchLength <= dictEnd) { 859 ZSTD_memmove(oLitEnd, match, sequence.matchLength); 860 return sequenceLength; 861 } 862 /* span extDict & currentPrefixSegment */ 863 { size_t const length1 = dictEnd - match; 864 ZSTD_memmove(oLitEnd, match, length1); 865 op = oLitEnd + length1; 866 sequence.matchLength -= length1; 867 match = prefixStart; 868 } } 869 /* Match within prefix of 1 or more bytes */ 870 assert(op <= oMatchEnd); 871 assert(oMatchEnd <= oend_w); 872 assert(match >= prefixStart); 873 assert(sequence.matchLength >= 1); 874 875 /* Nearly all offsets are >= WILDCOPY_VECLEN bytes, which means we can use wildcopy 876 * without overlap checking. 877 */ 878 if (LIKELY(sequence.offset >= WILDCOPY_VECLEN)) { 879 /* We bet on a full wildcopy for matches, since we expect matches to be 880 * longer than literals (in general). In silesia, ~10% of matches are longer 881 * than 16 bytes. 882 */ 883 ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength, ZSTD_no_overlap); 884 return sequenceLength; 885 } 886 assert(sequence.offset < WILDCOPY_VECLEN); 887 888 /* Copy 8 bytes and spread the offset to be >= 8. */ 889 ZSTD_overlapCopy8(&op, &match, sequence.offset); 890 891 /* If the match length is > 8 bytes, then continue with the wildcopy. */ 892 if (sequence.matchLength > 8) { 893 assert(op < oMatchEnd); 894 ZSTD_wildcopy(op, match, (ptrdiff_t)sequence.matchLength-8, ZSTD_overlap_src_before_dst); 895 } 896 return sequenceLength; 897 } 898 899 static void 900 ZSTD_initFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, const ZSTD_seqSymbol* dt) 901 { 902 const void* ptr = dt; 903 const ZSTD_seqSymbol_header* const DTableH = (const ZSTD_seqSymbol_header*)ptr; 904 DStatePtr->state = BIT_readBits(bitD, DTableH->tableLog); 905 DEBUGLOG(6, "ZSTD_initFseState : val=%u using %u bits", 906 (U32)DStatePtr->state, DTableH->tableLog); 907 BIT_reloadDStream(bitD); 908 DStatePtr->table = dt + 1; 909 } 910 911 FORCE_INLINE_TEMPLATE void 912 ZSTD_updateFseState(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD) 913 { 914 ZSTD_seqSymbol const DInfo = DStatePtr->table[DStatePtr->state]; 915 U32 const nbBits = DInfo.nbBits; 916 size_t const lowBits = BIT_readBits(bitD, nbBits); 917 DStatePtr->state = DInfo.nextState + lowBits; 918 } 919 920 FORCE_INLINE_TEMPLATE void 921 ZSTD_updateFseStateWithDInfo(ZSTD_fseState* DStatePtr, BIT_DStream_t* bitD, ZSTD_seqSymbol const DInfo) 922 { 923 U32 const nbBits = DInfo.nbBits; 924 size_t const lowBits = BIT_readBits(bitD, nbBits); 925 DStatePtr->state = DInfo.nextState + lowBits; 926 } 927 928 /* We need to add at most (ZSTD_WINDOWLOG_MAX_32 - 1) bits to read the maximum 929 * offset bits. But we can only read at most (STREAM_ACCUMULATOR_MIN_32 - 1) 930 * bits before reloading. This value is the maximum number of bytes we read 931 * after reloading when we are decoding long offsets. 932 */ 933 #define LONG_OFFSETS_MAX_EXTRA_BITS_32 \ 934 (ZSTD_WINDOWLOG_MAX_32 > STREAM_ACCUMULATOR_MIN_32 \ 935 ? ZSTD_WINDOWLOG_MAX_32 - STREAM_ACCUMULATOR_MIN_32 \ 936 : 0) 937 938 typedef enum { ZSTD_lo_isRegularOffset, ZSTD_lo_isLongOffset=1 } ZSTD_longOffset_e; 939 typedef enum { ZSTD_p_noPrefetch=0, ZSTD_p_prefetch=1 } ZSTD_prefetch_e; 940 941 FORCE_INLINE_TEMPLATE seq_t 942 ZSTD_decodeSequence(seqState_t* seqState, const ZSTD_longOffset_e longOffsets, const ZSTD_prefetch_e prefetch) 943 { 944 seq_t seq; 945 ZSTD_seqSymbol const llDInfo = seqState->stateLL.table[seqState->stateLL.state]; 946 ZSTD_seqSymbol const mlDInfo = seqState->stateML.table[seqState->stateML.state]; 947 ZSTD_seqSymbol const ofDInfo = seqState->stateOffb.table[seqState->stateOffb.state]; 948 U32 const llBase = llDInfo.baseValue; 949 U32 const mlBase = mlDInfo.baseValue; 950 U32 const ofBase = ofDInfo.baseValue; 951 BYTE const llBits = llDInfo.nbAdditionalBits; 952 BYTE const mlBits = mlDInfo.nbAdditionalBits; 953 BYTE const ofBits = ofDInfo.nbAdditionalBits; 954 BYTE const totalBits = llBits+mlBits+ofBits; 955 956 /* sequence */ 957 { size_t offset; 958 if (ofBits > 1) { 959 ZSTD_STATIC_ASSERT(ZSTD_lo_isLongOffset == 1); 960 ZSTD_STATIC_ASSERT(LONG_OFFSETS_MAX_EXTRA_BITS_32 == 5); 961 assert(ofBits <= MaxOff); 962 if (MEM_32bits() && longOffsets && (ofBits >= STREAM_ACCUMULATOR_MIN_32)) { 963 U32 const extraBits = ofBits - MIN(ofBits, 32 - seqState->DStream.bitsConsumed); 964 offset = ofBase + (BIT_readBitsFast(&seqState->DStream, ofBits - extraBits) << extraBits); 965 BIT_reloadDStream(&seqState->DStream); 966 if (extraBits) offset += BIT_readBitsFast(&seqState->DStream, extraBits); 967 assert(extraBits <= LONG_OFFSETS_MAX_EXTRA_BITS_32); /* to avoid another reload */ 968 } else { 969 offset = ofBase + BIT_readBitsFast(&seqState->DStream, ofBits/*>0*/); /* <= (ZSTD_WINDOWLOG_MAX-1) bits */ 970 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); 971 } 972 seqState->prevOffset[2] = seqState->prevOffset[1]; 973 seqState->prevOffset[1] = seqState->prevOffset[0]; 974 seqState->prevOffset[0] = offset; 975 } else { 976 U32 const ll0 = (llBase == 0); 977 if (LIKELY((ofBits == 0))) { 978 if (LIKELY(!ll0)) 979 offset = seqState->prevOffset[0]; 980 else { 981 offset = seqState->prevOffset[1]; 982 seqState->prevOffset[1] = seqState->prevOffset[0]; 983 seqState->prevOffset[0] = offset; 984 } 985 } else { 986 offset = ofBase + ll0 + BIT_readBitsFast(&seqState->DStream, 1); 987 { size_t temp = (offset==3) ? seqState->prevOffset[0] - 1 : seqState->prevOffset[offset]; 988 temp += !temp; /* 0 is not valid; input is corrupted; force offset to 1 */ 989 if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1]; 990 seqState->prevOffset[1] = seqState->prevOffset[0]; 991 seqState->prevOffset[0] = offset = temp; 992 } } } 993 seq.offset = offset; 994 } 995 996 seq.matchLength = mlBase; 997 if (mlBits > 0) 998 seq.matchLength += BIT_readBitsFast(&seqState->DStream, mlBits/*>0*/); 999 1000 if (MEM_32bits() && (mlBits+llBits >= STREAM_ACCUMULATOR_MIN_32-LONG_OFFSETS_MAX_EXTRA_BITS_32)) 1001 BIT_reloadDStream(&seqState->DStream); 1002 if (MEM_64bits() && UNLIKELY(totalBits >= STREAM_ACCUMULATOR_MIN_64-(LLFSELog+MLFSELog+OffFSELog))) 1003 BIT_reloadDStream(&seqState->DStream); 1004 /* Ensure there are enough bits to read the rest of data in 64-bit mode. */ 1005 ZSTD_STATIC_ASSERT(16+LLFSELog+MLFSELog+OffFSELog < STREAM_ACCUMULATOR_MIN_64); 1006 1007 seq.litLength = llBase; 1008 if (llBits > 0) 1009 seq.litLength += BIT_readBitsFast(&seqState->DStream, llBits/*>0*/); 1010 1011 if (MEM_32bits()) 1012 BIT_reloadDStream(&seqState->DStream); 1013 1014 DEBUGLOG(6, "seq: litL=%u, matchL=%u, offset=%u", 1015 (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset); 1016 1017 if (prefetch == ZSTD_p_prefetch) { 1018 size_t const pos = seqState->pos + seq.litLength; 1019 const BYTE* const matchBase = (seq.offset > pos) ? seqState->dictEnd : seqState->prefixStart; 1020 seq.match = matchBase + pos - seq.offset; /* note : this operation can overflow when seq.offset is really too large, which can only happen when input is corrupted. 1021 * No consequence though : no memory access will occur, offset is only used for prefetching */ 1022 seqState->pos = pos + seq.matchLength; 1023 } 1024 1025 /* ANS state update 1026 * gcc-9.0.0 does 2.5% worse with ZSTD_updateFseStateWithDInfo(). 1027 * clang-9.2.0 does 7% worse with ZSTD_updateFseState(). 1028 * Naturally it seems like ZSTD_updateFseStateWithDInfo() should be the 1029 * better option, so it is the default for other compilers. But, if you 1030 * measure that it is worse, please put up a pull request. 1031 */ 1032 { 1033 #if !defined(__clang__) 1034 const int kUseUpdateFseState = 1; 1035 #else 1036 const int kUseUpdateFseState = 0; 1037 #endif 1038 if (kUseUpdateFseState) { 1039 ZSTD_updateFseState(&seqState->stateLL, &seqState->DStream); /* <= 9 bits */ 1040 ZSTD_updateFseState(&seqState->stateML, &seqState->DStream); /* <= 9 bits */ 1041 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ 1042 ZSTD_updateFseState(&seqState->stateOffb, &seqState->DStream); /* <= 8 bits */ 1043 } else { 1044 ZSTD_updateFseStateWithDInfo(&seqState->stateLL, &seqState->DStream, llDInfo); /* <= 9 bits */ 1045 ZSTD_updateFseStateWithDInfo(&seqState->stateML, &seqState->DStream, mlDInfo); /* <= 9 bits */ 1046 if (MEM_32bits()) BIT_reloadDStream(&seqState->DStream); /* <= 18 bits */ 1047 ZSTD_updateFseStateWithDInfo(&seqState->stateOffb, &seqState->DStream, ofDInfo); /* <= 8 bits */ 1048 } 1049 } 1050 1051 return seq; 1052 } 1053 1054 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION 1055 MEM_STATIC int ZSTD_dictionaryIsActive(ZSTD_DCtx const* dctx, BYTE const* prefixStart, BYTE const* oLitEnd) 1056 { 1057 size_t const windowSize = dctx->fParams.windowSize; 1058 /* No dictionary used. */ 1059 if (dctx->dictContentEndForFuzzing == NULL) return 0; 1060 /* Dictionary is our prefix. */ 1061 if (prefixStart == dctx->dictContentBeginForFuzzing) return 1; 1062 /* Dictionary is not our ext-dict. */ 1063 if (dctx->dictEnd != dctx->dictContentEndForFuzzing) return 0; 1064 /* Dictionary is not within our window size. */ 1065 if ((size_t)(oLitEnd - prefixStart) >= windowSize) return 0; 1066 /* Dictionary is active. */ 1067 return 1; 1068 } 1069 1070 MEM_STATIC void ZSTD_assertValidSequence( 1071 ZSTD_DCtx const* dctx, 1072 BYTE const* op, BYTE const* oend, 1073 seq_t const seq, 1074 BYTE const* prefixStart, BYTE const* virtualStart) 1075 { 1076 #if DEBUGLEVEL >= 1 1077 size_t const windowSize = dctx->fParams.windowSize; 1078 size_t const sequenceSize = seq.litLength + seq.matchLength; 1079 BYTE const* const oLitEnd = op + seq.litLength; 1080 DEBUGLOG(6, "Checking sequence: litL=%u matchL=%u offset=%u", 1081 (U32)seq.litLength, (U32)seq.matchLength, (U32)seq.offset); 1082 assert(op <= oend); 1083 assert((size_t)(oend - op) >= sequenceSize); 1084 assert(sequenceSize <= ZSTD_BLOCKSIZE_MAX); 1085 if (ZSTD_dictionaryIsActive(dctx, prefixStart, oLitEnd)) { 1086 size_t const dictSize = (size_t)((char const*)dctx->dictContentEndForFuzzing - (char const*)dctx->dictContentBeginForFuzzing); 1087 /* Offset must be within the dictionary. */ 1088 assert(seq.offset <= (size_t)(oLitEnd - virtualStart)); 1089 assert(seq.offset <= windowSize + dictSize); 1090 } else { 1091 /* Offset must be within our window. */ 1092 assert(seq.offset <= windowSize); 1093 } 1094 #else 1095 (void)dctx, (void)op, (void)oend, (void)seq, (void)prefixStart, (void)virtualStart; 1096 #endif 1097 } 1098 #endif 1099 1100 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG 1101 FORCE_INLINE_TEMPLATE size_t 1102 DONT_VECTORIZE 1103 ZSTD_decompressSequences_body( ZSTD_DCtx* dctx, 1104 void* dst, size_t maxDstSize, 1105 const void* seqStart, size_t seqSize, int nbSeq, 1106 const ZSTD_longOffset_e isLongOffset, 1107 const int frame) 1108 { 1109 const BYTE* ip = (const BYTE*)seqStart; 1110 const BYTE* const iend = ip + seqSize; 1111 BYTE* const ostart = (BYTE*)dst; 1112 BYTE* const oend = ostart + maxDstSize; 1113 BYTE* op = ostart; 1114 const BYTE* litPtr = dctx->litPtr; 1115 const BYTE* const litEnd = litPtr + dctx->litSize; 1116 const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart); 1117 const BYTE* const vBase = (const BYTE*) (dctx->virtualStart); 1118 const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd); 1119 DEBUGLOG(5, "ZSTD_decompressSequences_body"); 1120 (void)frame; 1121 1122 /* Regen sequences */ 1123 if (nbSeq) { 1124 seqState_t seqState; 1125 size_t error = 0; 1126 dctx->fseEntropy = 1; 1127 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; } 1128 RETURN_ERROR_IF( 1129 ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)), 1130 corruption_detected, ""); 1131 ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr); 1132 ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr); 1133 ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr); 1134 assert(dst != NULL); 1135 1136 ZSTD_STATIC_ASSERT( 1137 BIT_DStream_unfinished < BIT_DStream_completed && 1138 BIT_DStream_endOfBuffer < BIT_DStream_completed && 1139 BIT_DStream_completed < BIT_DStream_overflow); 1140 1141 #if defined(__x86_64__) 1142 /* Align the decompression loop to 32 + 16 bytes. 1143 * 1144 * zstd compiled with gcc-9 on an Intel i9-9900k shows 10% decompression 1145 * speed swings based on the alignment of the decompression loop. This 1146 * performance swing is caused by parts of the decompression loop falling 1147 * out of the DSB. The entire decompression loop should fit in the DSB, 1148 * when it can't we get much worse performance. You can measure if you've 1149 * hit the good case or the bad case with this perf command for some 1150 * compressed file test.zst: 1151 * 1152 * perf stat -e cycles -e instructions -e idq.all_dsb_cycles_any_uops \ 1153 * -e idq.all_mite_cycles_any_uops -- ./zstd -tq test.zst 1154 * 1155 * If you see most cycles served out of the MITE you've hit the bad case. 1156 * If you see most cycles served out of the DSB you've hit the good case. 1157 * If it is pretty even then you may be in an okay case. 1158 * 1159 * I've been able to reproduce this issue on the following CPUs: 1160 * - Kabylake: Macbook Pro (15-inch, 2019) 2.4 GHz Intel Core i9 1161 * Use Instruments->Counters to get DSB/MITE cycles. 1162 * I never got performance swings, but I was able to 1163 * go from the good case of mostly DSB to half of the 1164 * cycles served from MITE. 1165 * - Coffeelake: Intel i9-9900k 1166 * 1167 * I haven't been able to reproduce the instability or DSB misses on any 1168 * of the following CPUS: 1169 * - Haswell 1170 * - Broadwell: Intel(R) Xeon(R) CPU E5-2680 v4 @ 2.40GH 1171 * - Skylake 1172 * 1173 * If you are seeing performance stability this script can help test. 1174 * It tests on 4 commits in zstd where I saw performance change. 1175 * 1176 * https://gist.github.com/terrelln/9889fc06a423fd5ca6e99351564473f4 1177 */ 1178 __asm__(".p2align 5"); 1179 __asm__("nop"); 1180 __asm__(".p2align 4"); 1181 #endif 1182 for ( ; ; ) { 1183 seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset, ZSTD_p_noPrefetch); 1184 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litEnd, prefixStart, vBase, dictEnd); 1185 #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) 1186 assert(!ZSTD_isError(oneSeqSize)); 1187 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequence, prefixStart, vBase); 1188 #endif 1189 DEBUGLOG(6, "regenerated sequence size : %u", (U32)oneSeqSize); 1190 BIT_reloadDStream(&(seqState.DStream)); 1191 op += oneSeqSize; 1192 /* gcc and clang both don't like early returns in this loop. 1193 * Instead break and check for an error at the end of the loop. 1194 */ 1195 if (UNLIKELY(ZSTD_isError(oneSeqSize))) { 1196 error = oneSeqSize; 1197 break; 1198 } 1199 if (UNLIKELY(!--nbSeq)) break; 1200 } 1201 1202 /* check if reached exact end */ 1203 DEBUGLOG(5, "ZSTD_decompressSequences_body: after decode loop, remaining nbSeq : %i", nbSeq); 1204 if (ZSTD_isError(error)) return error; 1205 RETURN_ERROR_IF(nbSeq, corruption_detected, ""); 1206 RETURN_ERROR_IF(BIT_reloadDStream(&seqState.DStream) < BIT_DStream_completed, corruption_detected, ""); 1207 /* save reps for next block */ 1208 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); } 1209 } 1210 1211 /* last literal segment */ 1212 { size_t const lastLLSize = litEnd - litPtr; 1213 RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, ""); 1214 if (op != NULL) { 1215 ZSTD_memcpy(op, litPtr, lastLLSize); 1216 op += lastLLSize; 1217 } 1218 } 1219 1220 return op-ostart; 1221 } 1222 1223 static size_t 1224 ZSTD_decompressSequences_default(ZSTD_DCtx* dctx, 1225 void* dst, size_t maxDstSize, 1226 const void* seqStart, size_t seqSize, int nbSeq, 1227 const ZSTD_longOffset_e isLongOffset, 1228 const int frame) 1229 { 1230 return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1231 } 1232 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ 1233 1234 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT 1235 FORCE_INLINE_TEMPLATE size_t 1236 ZSTD_decompressSequencesLong_body( 1237 ZSTD_DCtx* dctx, 1238 void* dst, size_t maxDstSize, 1239 const void* seqStart, size_t seqSize, int nbSeq, 1240 const ZSTD_longOffset_e isLongOffset, 1241 const int frame) 1242 { 1243 const BYTE* ip = (const BYTE*)seqStart; 1244 const BYTE* const iend = ip + seqSize; 1245 BYTE* const ostart = (BYTE*)dst; 1246 BYTE* const oend = ostart + maxDstSize; 1247 BYTE* op = ostart; 1248 const BYTE* litPtr = dctx->litPtr; 1249 const BYTE* const litEnd = litPtr + dctx->litSize; 1250 const BYTE* const prefixStart = (const BYTE*) (dctx->prefixStart); 1251 const BYTE* const dictStart = (const BYTE*) (dctx->virtualStart); 1252 const BYTE* const dictEnd = (const BYTE*) (dctx->dictEnd); 1253 (void)frame; 1254 1255 /* Regen sequences */ 1256 if (nbSeq) { 1257 #define STORED_SEQS 4 1258 #define STORED_SEQS_MASK (STORED_SEQS-1) 1259 #define ADVANCED_SEQS 4 1260 seq_t sequences[STORED_SEQS]; 1261 int const seqAdvance = MIN(nbSeq, ADVANCED_SEQS); 1262 seqState_t seqState; 1263 int seqNb; 1264 dctx->fseEntropy = 1; 1265 { int i; for (i=0; i<ZSTD_REP_NUM; i++) seqState.prevOffset[i] = dctx->entropy.rep[i]; } 1266 seqState.prefixStart = prefixStart; 1267 seqState.pos = (size_t)(op-prefixStart); 1268 seqState.dictEnd = dictEnd; 1269 assert(dst != NULL); 1270 assert(iend >= ip); 1271 RETURN_ERROR_IF( 1272 ERR_isError(BIT_initDStream(&seqState.DStream, ip, iend-ip)), 1273 corruption_detected, ""); 1274 ZSTD_initFseState(&seqState.stateLL, &seqState.DStream, dctx->LLTptr); 1275 ZSTD_initFseState(&seqState.stateOffb, &seqState.DStream, dctx->OFTptr); 1276 ZSTD_initFseState(&seqState.stateML, &seqState.DStream, dctx->MLTptr); 1277 1278 /* prepare in advance */ 1279 for (seqNb=0; (BIT_reloadDStream(&seqState.DStream) <= BIT_DStream_completed) && (seqNb<seqAdvance); seqNb++) { 1280 sequences[seqNb] = ZSTD_decodeSequence(&seqState, isLongOffset, ZSTD_p_prefetch); 1281 PREFETCH_L1(sequences[seqNb].match); PREFETCH_L1(sequences[seqNb].match + sequences[seqNb].matchLength - 1); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */ 1282 } 1283 RETURN_ERROR_IF(seqNb<seqAdvance, corruption_detected, ""); 1284 1285 /* decode and decompress */ 1286 for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && (seqNb<nbSeq) ; seqNb++) { 1287 seq_t const sequence = ZSTD_decodeSequence(&seqState, isLongOffset, ZSTD_p_prefetch); 1288 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd); 1289 #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) 1290 assert(!ZSTD_isError(oneSeqSize)); 1291 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], prefixStart, dictStart); 1292 #endif 1293 if (ZSTD_isError(oneSeqSize)) return oneSeqSize; 1294 PREFETCH_L1(sequence.match); PREFETCH_L1(sequence.match + sequence.matchLength - 1); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */ 1295 sequences[seqNb & STORED_SEQS_MASK] = sequence; 1296 op += oneSeqSize; 1297 } 1298 RETURN_ERROR_IF(seqNb<nbSeq, corruption_detected, ""); 1299 1300 /* finish queue */ 1301 seqNb -= seqAdvance; 1302 for ( ; seqNb<nbSeq ; seqNb++) { 1303 size_t const oneSeqSize = ZSTD_execSequence(op, oend, sequences[seqNb&STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd); 1304 #if defined(FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION) && defined(FUZZING_ASSERT_VALID_SEQUENCE) 1305 assert(!ZSTD_isError(oneSeqSize)); 1306 if (frame) ZSTD_assertValidSequence(dctx, op, oend, sequences[seqNb&STORED_SEQS_MASK], prefixStart, dictStart); 1307 #endif 1308 if (ZSTD_isError(oneSeqSize)) return oneSeqSize; 1309 op += oneSeqSize; 1310 } 1311 1312 /* save reps for next block */ 1313 { U32 i; for (i=0; i<ZSTD_REP_NUM; i++) dctx->entropy.rep[i] = (U32)(seqState.prevOffset[i]); } 1314 } 1315 1316 /* last literal segment */ 1317 { size_t const lastLLSize = litEnd - litPtr; 1318 RETURN_ERROR_IF(lastLLSize > (size_t)(oend-op), dstSize_tooSmall, ""); 1319 if (op != NULL) { 1320 ZSTD_memcpy(op, litPtr, lastLLSize); 1321 op += lastLLSize; 1322 } 1323 } 1324 1325 return op-ostart; 1326 } 1327 1328 static size_t 1329 ZSTD_decompressSequencesLong_default(ZSTD_DCtx* dctx, 1330 void* dst, size_t maxDstSize, 1331 const void* seqStart, size_t seqSize, int nbSeq, 1332 const ZSTD_longOffset_e isLongOffset, 1333 const int frame) 1334 { 1335 return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1336 } 1337 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ 1338 1339 1340 1341 #if DYNAMIC_BMI2 1342 1343 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG 1344 static TARGET_ATTRIBUTE("bmi2") size_t 1345 DONT_VECTORIZE 1346 ZSTD_decompressSequences_bmi2(ZSTD_DCtx* dctx, 1347 void* dst, size_t maxDstSize, 1348 const void* seqStart, size_t seqSize, int nbSeq, 1349 const ZSTD_longOffset_e isLongOffset, 1350 const int frame) 1351 { 1352 return ZSTD_decompressSequences_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1353 } 1354 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ 1355 1356 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT 1357 static TARGET_ATTRIBUTE("bmi2") size_t 1358 ZSTD_decompressSequencesLong_bmi2(ZSTD_DCtx* dctx, 1359 void* dst, size_t maxDstSize, 1360 const void* seqStart, size_t seqSize, int nbSeq, 1361 const ZSTD_longOffset_e isLongOffset, 1362 const int frame) 1363 { 1364 return ZSTD_decompressSequencesLong_body(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1365 } 1366 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ 1367 1368 #endif /* DYNAMIC_BMI2 */ 1369 1370 typedef size_t (*ZSTD_decompressSequences_t)( 1371 ZSTD_DCtx* dctx, 1372 void* dst, size_t maxDstSize, 1373 const void* seqStart, size_t seqSize, int nbSeq, 1374 const ZSTD_longOffset_e isLongOffset, 1375 const int frame); 1376 1377 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG 1378 static size_t 1379 ZSTD_decompressSequences(ZSTD_DCtx* dctx, void* dst, size_t maxDstSize, 1380 const void* seqStart, size_t seqSize, int nbSeq, 1381 const ZSTD_longOffset_e isLongOffset, 1382 const int frame) 1383 { 1384 DEBUGLOG(5, "ZSTD_decompressSequences"); 1385 #if DYNAMIC_BMI2 1386 if (dctx->bmi2) { 1387 return ZSTD_decompressSequences_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1388 } 1389 #endif 1390 return ZSTD_decompressSequences_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1391 } 1392 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG */ 1393 1394 1395 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT 1396 /* ZSTD_decompressSequencesLong() : 1397 * decompression function triggered when a minimum share of offsets is considered "long", 1398 * aka out of cache. 1399 * note : "long" definition seems overloaded here, sometimes meaning "wider than bitstream register", and sometimes meaning "farther than memory cache distance". 1400 * This function will try to mitigate main memory latency through the use of prefetching */ 1401 static size_t 1402 ZSTD_decompressSequencesLong(ZSTD_DCtx* dctx, 1403 void* dst, size_t maxDstSize, 1404 const void* seqStart, size_t seqSize, int nbSeq, 1405 const ZSTD_longOffset_e isLongOffset, 1406 const int frame) 1407 { 1408 DEBUGLOG(5, "ZSTD_decompressSequencesLong"); 1409 #if DYNAMIC_BMI2 1410 if (dctx->bmi2) { 1411 return ZSTD_decompressSequencesLong_bmi2(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1412 } 1413 #endif 1414 return ZSTD_decompressSequencesLong_default(dctx, dst, maxDstSize, seqStart, seqSize, nbSeq, isLongOffset, frame); 1415 } 1416 #endif /* ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT */ 1417 1418 1419 1420 #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 1421 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 1422 /* ZSTD_getLongOffsetsShare() : 1423 * condition : offTable must be valid 1424 * @return : "share" of long offsets (arbitrarily defined as > (1<<23)) 1425 * compared to maximum possible of (1<<OffFSELog) */ 1426 static unsigned 1427 ZSTD_getLongOffsetsShare(const ZSTD_seqSymbol* offTable) 1428 { 1429 const void* ptr = offTable; 1430 U32 const tableLog = ((const ZSTD_seqSymbol_header*)ptr)[0].tableLog; 1431 const ZSTD_seqSymbol* table = offTable + 1; 1432 U32 const max = 1 << tableLog; 1433 U32 u, total = 0; 1434 DEBUGLOG(5, "ZSTD_getLongOffsetsShare: (tableLog=%u)", tableLog); 1435 1436 assert(max <= (1 << OffFSELog)); /* max not too large */ 1437 for (u=0; u<max; u++) { 1438 if (table[u].nbAdditionalBits > 22) total += 1; 1439 } 1440 1441 assert(tableLog <= OffFSELog); 1442 total <<= (OffFSELog - tableLog); /* scale to OffFSELog */ 1443 1444 return total; 1445 } 1446 #endif 1447 1448 size_t 1449 ZSTD_decompressBlock_internal(ZSTD_DCtx* dctx, 1450 void* dst, size_t dstCapacity, 1451 const void* src, size_t srcSize, const int frame) 1452 { /* blockType == blockCompressed */ 1453 const BYTE* ip = (const BYTE*)src; 1454 /* isLongOffset must be true if there are long offsets. 1455 * Offsets are long if they are larger than 2^STREAM_ACCUMULATOR_MIN. 1456 * We don't expect that to be the case in 64-bit mode. 1457 * In block mode, window size is not known, so we have to be conservative. 1458 * (note: but it could be evaluated from current-lowLimit) 1459 */ 1460 ZSTD_longOffset_e const isLongOffset = (ZSTD_longOffset_e)(MEM_32bits() && (!frame || (dctx->fParams.windowSize > (1ULL << STREAM_ACCUMULATOR_MIN)))); 1461 DEBUGLOG(5, "ZSTD_decompressBlock_internal (size : %u)", (U32)srcSize); 1462 1463 RETURN_ERROR_IF(srcSize >= ZSTD_BLOCKSIZE_MAX, srcSize_wrong, ""); 1464 1465 /* Decode literals section */ 1466 { size_t const litCSize = ZSTD_decodeLiteralsBlock(dctx, src, srcSize); 1467 DEBUGLOG(5, "ZSTD_decodeLiteralsBlock : %u", (U32)litCSize); 1468 if (ZSTD_isError(litCSize)) return litCSize; 1469 ip += litCSize; 1470 srcSize -= litCSize; 1471 } 1472 1473 /* Build Decoding Tables */ 1474 { 1475 /* These macros control at build-time which decompressor implementation 1476 * we use. If neither is defined, we do some inspection and dispatch at 1477 * runtime. 1478 */ 1479 #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 1480 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 1481 int usePrefetchDecoder = dctx->ddictIsCold; 1482 #endif 1483 int nbSeq; 1484 size_t const seqHSize = ZSTD_decodeSeqHeaders(dctx, &nbSeq, ip, srcSize); 1485 if (ZSTD_isError(seqHSize)) return seqHSize; 1486 ip += seqHSize; 1487 srcSize -= seqHSize; 1488 1489 RETURN_ERROR_IF(dst == NULL && nbSeq > 0, dstSize_tooSmall, "NULL not handled"); 1490 1491 #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 1492 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 1493 if ( !usePrefetchDecoder 1494 && (!frame || (dctx->fParams.windowSize > (1<<24))) 1495 && (nbSeq>ADVANCED_SEQS) ) { /* could probably use a larger nbSeq limit */ 1496 U32 const shareLongOffsets = ZSTD_getLongOffsetsShare(dctx->OFTptr); 1497 U32 const minShare = MEM_64bits() ? 7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */ 1498 usePrefetchDecoder = (shareLongOffsets >= minShare); 1499 } 1500 #endif 1501 1502 dctx->ddictIsCold = 0; 1503 1504 #if !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT) && \ 1505 !defined(ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG) 1506 if (usePrefetchDecoder) 1507 #endif 1508 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_SHORT 1509 return ZSTD_decompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame); 1510 #endif 1511 1512 #ifndef ZSTD_FORCE_DECOMPRESS_SEQUENCES_LONG 1513 /* else */ 1514 return ZSTD_decompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset, frame); 1515 #endif 1516 } 1517 } 1518 1519 1520 void ZSTD_checkContinuity(ZSTD_DCtx* dctx, const void* dst, size_t dstSize) 1521 { 1522 if (dst != dctx->previousDstEnd && dstSize > 0) { /* not contiguous */ 1523 dctx->dictEnd = dctx->previousDstEnd; 1524 dctx->virtualStart = (const char*)dst - ((const char*)(dctx->previousDstEnd) - (const char*)(dctx->prefixStart)); 1525 dctx->prefixStart = dst; 1526 dctx->previousDstEnd = dst; 1527 } 1528 } 1529 1530 1531 size_t ZSTD_decompressBlock(ZSTD_DCtx* dctx, 1532 void* dst, size_t dstCapacity, 1533 const void* src, size_t srcSize) 1534 { 1535 size_t dSize; 1536 ZSTD_checkContinuity(dctx, dst, dstCapacity); 1537 dSize = ZSTD_decompressBlock_internal(dctx, dst, dstCapacity, src, srcSize, /* frame */ 0); 1538 dctx->previousDstEnd = (char*)dst + dSize; 1539 return dSize; 1540 } 1541