1 /* 2 * Copyright (c) Przemyslaw Skibinski, 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 /* 12 * Disable inlining for the optimal parser for the kernel build. 13 * It is unlikely to be used in the kernel, and where it is used 14 * latency shouldn't matter because it is very slow to begin with. 15 * We prefer a ~180KB binary size win over faster optimal parsing. 16 * 17 * TODO(https://github.com/facebook/zstd/issues/2862): 18 * Improve the code size of the optimal parser in general, so we 19 * don't need this hack for the kernel build. 20 */ 21 #define ZSTD_NO_INLINE 1 22 23 #include "zstd_compress_internal.h" 24 #include "hist.h" 25 #include "zstd_opt.h" 26 27 28 #define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats */ 29 #define ZSTD_FREQ_DIV 4 /* log factor when using previous stats to init next stats */ 30 #define ZSTD_MAX_PRICE (1<<30) 31 32 #define ZSTD_PREDEF_THRESHOLD 1024 /* if srcSize < ZSTD_PREDEF_THRESHOLD, symbols' cost is assumed static, directly determined by pre-defined distributions */ 33 34 35 /*-************************************* 36 * Price functions for optimal parser 37 ***************************************/ 38 39 #if 0 /* approximation at bit level */ 40 # define BITCOST_ACCURACY 0 41 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) 42 # define WEIGHT(stat) ((void)opt, ZSTD_bitWeight(stat)) 43 #elif 0 /* fractional bit accuracy */ 44 # define BITCOST_ACCURACY 8 45 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) 46 # define WEIGHT(stat,opt) ((void)opt, ZSTD_fracWeight(stat)) 47 #else /* opt==approx, ultra==accurate */ 48 # define BITCOST_ACCURACY 8 49 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) 50 # define WEIGHT(stat,opt) (opt ? ZSTD_fracWeight(stat) : ZSTD_bitWeight(stat)) 51 #endif 52 53 MEM_STATIC U32 ZSTD_bitWeight(U32 stat) 54 { 55 return (ZSTD_highbit32(stat+1) * BITCOST_MULTIPLIER); 56 } 57 58 MEM_STATIC U32 ZSTD_fracWeight(U32 rawStat) 59 { 60 U32 const stat = rawStat + 1; 61 U32 const hb = ZSTD_highbit32(stat); 62 U32 const BWeight = hb * BITCOST_MULTIPLIER; 63 U32 const FWeight = (stat << BITCOST_ACCURACY) >> hb; 64 U32 const weight = BWeight + FWeight; 65 assert(hb + BITCOST_ACCURACY < 31); 66 return weight; 67 } 68 69 #if (DEBUGLEVEL>=2) 70 /* debugging function, 71 * @return price in bytes as fractional value 72 * for debug messages only */ 73 MEM_STATIC double ZSTD_fCost(U32 price) 74 { 75 return (double)price / (BITCOST_MULTIPLIER*8); 76 } 77 #endif 78 79 static int ZSTD_compressedLiterals(optState_t const* const optPtr) 80 { 81 return optPtr->literalCompressionMode != ZSTD_lcm_uncompressed; 82 } 83 84 static void ZSTD_setBasePrices(optState_t* optPtr, int optLevel) 85 { 86 if (ZSTD_compressedLiterals(optPtr)) 87 optPtr->litSumBasePrice = WEIGHT(optPtr->litSum, optLevel); 88 optPtr->litLengthSumBasePrice = WEIGHT(optPtr->litLengthSum, optLevel); 89 optPtr->matchLengthSumBasePrice = WEIGHT(optPtr->matchLengthSum, optLevel); 90 optPtr->offCodeSumBasePrice = WEIGHT(optPtr->offCodeSum, optLevel); 91 } 92 93 94 /* ZSTD_downscaleStat() : 95 * reduce all elements in table by a factor 2^(ZSTD_FREQ_DIV+malus) 96 * return the resulting sum of elements */ 97 static U32 ZSTD_downscaleStat(unsigned* table, U32 lastEltIndex, int malus) 98 { 99 U32 s, sum=0; 100 DEBUGLOG(5, "ZSTD_downscaleStat (nbElts=%u)", (unsigned)lastEltIndex+1); 101 assert(ZSTD_FREQ_DIV+malus > 0 && ZSTD_FREQ_DIV+malus < 31); 102 for (s=0; s<lastEltIndex+1; s++) { 103 table[s] = 1 + (table[s] >> (ZSTD_FREQ_DIV+malus)); 104 sum += table[s]; 105 } 106 return sum; 107 } 108 109 /* ZSTD_rescaleFreqs() : 110 * if first block (detected by optPtr->litLengthSum == 0) : init statistics 111 * take hints from dictionary if there is one 112 * or init from zero, using src for literals stats, or flat 1 for match symbols 113 * otherwise downscale existing stats, to be used as seed for next block. 114 */ 115 static void 116 ZSTD_rescaleFreqs(optState_t* const optPtr, 117 const BYTE* const src, size_t const srcSize, 118 int const optLevel) 119 { 120 int const compressedLiterals = ZSTD_compressedLiterals(optPtr); 121 DEBUGLOG(5, "ZSTD_rescaleFreqs (srcSize=%u)", (unsigned)srcSize); 122 optPtr->priceType = zop_dynamic; 123 124 if (optPtr->litLengthSum == 0) { /* first block : init */ 125 if (srcSize <= ZSTD_PREDEF_THRESHOLD) { /* heuristic */ 126 DEBUGLOG(5, "(srcSize <= ZSTD_PREDEF_THRESHOLD) => zop_predef"); 127 optPtr->priceType = zop_predef; 128 } 129 130 assert(optPtr->symbolCosts != NULL); 131 if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid) { 132 /* huffman table presumed generated by dictionary */ 133 optPtr->priceType = zop_dynamic; 134 135 if (compressedLiterals) { 136 unsigned lit; 137 assert(optPtr->litFreq != NULL); 138 optPtr->litSum = 0; 139 for (lit=0; lit<=MaxLit; lit++) { 140 U32 const scaleLog = 11; /* scale to 2K */ 141 U32 const bitCost = HUF_getNbBits(optPtr->symbolCosts->huf.CTable, lit); 142 assert(bitCost <= scaleLog); 143 optPtr->litFreq[lit] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; 144 optPtr->litSum += optPtr->litFreq[lit]; 145 } } 146 147 { unsigned ll; 148 FSE_CState_t llstate; 149 FSE_initCState(&llstate, optPtr->symbolCosts->fse.litlengthCTable); 150 optPtr->litLengthSum = 0; 151 for (ll=0; ll<=MaxLL; ll++) { 152 U32 const scaleLog = 10; /* scale to 1K */ 153 U32 const bitCost = FSE_getMaxNbBits(llstate.symbolTT, ll); 154 assert(bitCost < scaleLog); 155 optPtr->litLengthFreq[ll] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; 156 optPtr->litLengthSum += optPtr->litLengthFreq[ll]; 157 } } 158 159 { unsigned ml; 160 FSE_CState_t mlstate; 161 FSE_initCState(&mlstate, optPtr->symbolCosts->fse.matchlengthCTable); 162 optPtr->matchLengthSum = 0; 163 for (ml=0; ml<=MaxML; ml++) { 164 U32 const scaleLog = 10; 165 U32 const bitCost = FSE_getMaxNbBits(mlstate.symbolTT, ml); 166 assert(bitCost < scaleLog); 167 optPtr->matchLengthFreq[ml] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; 168 optPtr->matchLengthSum += optPtr->matchLengthFreq[ml]; 169 } } 170 171 { unsigned of; 172 FSE_CState_t ofstate; 173 FSE_initCState(&ofstate, optPtr->symbolCosts->fse.offcodeCTable); 174 optPtr->offCodeSum = 0; 175 for (of=0; of<=MaxOff; of++) { 176 U32 const scaleLog = 10; 177 U32 const bitCost = FSE_getMaxNbBits(ofstate.symbolTT, of); 178 assert(bitCost < scaleLog); 179 optPtr->offCodeFreq[of] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; 180 optPtr->offCodeSum += optPtr->offCodeFreq[of]; 181 } } 182 183 } else { /* not a dictionary */ 184 185 assert(optPtr->litFreq != NULL); 186 if (compressedLiterals) { 187 unsigned lit = MaxLit; 188 HIST_count_simple(optPtr->litFreq, &lit, src, srcSize); /* use raw first block to init statistics */ 189 optPtr->litSum = ZSTD_downscaleStat(optPtr->litFreq, MaxLit, 1); 190 } 191 192 { unsigned ll; 193 for (ll=0; ll<=MaxLL; ll++) 194 optPtr->litLengthFreq[ll] = 1; 195 } 196 optPtr->litLengthSum = MaxLL+1; 197 198 { unsigned ml; 199 for (ml=0; ml<=MaxML; ml++) 200 optPtr->matchLengthFreq[ml] = 1; 201 } 202 optPtr->matchLengthSum = MaxML+1; 203 204 { unsigned of; 205 for (of=0; of<=MaxOff; of++) 206 optPtr->offCodeFreq[of] = 1; 207 } 208 optPtr->offCodeSum = MaxOff+1; 209 210 } 211 212 } else { /* new block : re-use previous statistics, scaled down */ 213 214 if (compressedLiterals) 215 optPtr->litSum = ZSTD_downscaleStat(optPtr->litFreq, MaxLit, 1); 216 optPtr->litLengthSum = ZSTD_downscaleStat(optPtr->litLengthFreq, MaxLL, 0); 217 optPtr->matchLengthSum = ZSTD_downscaleStat(optPtr->matchLengthFreq, MaxML, 0); 218 optPtr->offCodeSum = ZSTD_downscaleStat(optPtr->offCodeFreq, MaxOff, 0); 219 } 220 221 ZSTD_setBasePrices(optPtr, optLevel); 222 } 223 224 /* ZSTD_rawLiteralsCost() : 225 * price of literals (only) in specified segment (which length can be 0). 226 * does not include price of literalLength symbol */ 227 static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength, 228 const optState_t* const optPtr, 229 int optLevel) 230 { 231 if (litLength == 0) return 0; 232 233 if (!ZSTD_compressedLiterals(optPtr)) 234 return (litLength << 3) * BITCOST_MULTIPLIER; /* Uncompressed - 8 bytes per literal. */ 235 236 if (optPtr->priceType == zop_predef) 237 return (litLength*6) * BITCOST_MULTIPLIER; /* 6 bit per literal - no statistic used */ 238 239 /* dynamic statistics */ 240 { U32 price = litLength * optPtr->litSumBasePrice; 241 U32 u; 242 for (u=0; u < litLength; u++) { 243 assert(WEIGHT(optPtr->litFreq[literals[u]], optLevel) <= optPtr->litSumBasePrice); /* literal cost should never be negative */ 244 price -= WEIGHT(optPtr->litFreq[literals[u]], optLevel); 245 } 246 return price; 247 } 248 } 249 250 /* ZSTD_litLengthPrice() : 251 * cost of literalLength symbol */ 252 static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optPtr, int optLevel) 253 { 254 if (optPtr->priceType == zop_predef) return WEIGHT(litLength, optLevel); 255 256 /* dynamic statistics */ 257 { U32 const llCode = ZSTD_LLcode(litLength); 258 return (LL_bits[llCode] * BITCOST_MULTIPLIER) 259 + optPtr->litLengthSumBasePrice 260 - WEIGHT(optPtr->litLengthFreq[llCode], optLevel); 261 } 262 } 263 264 /* ZSTD_getMatchPrice() : 265 * Provides the cost of the match part (offset + matchLength) of a sequence 266 * Must be combined with ZSTD_fullLiteralsCost() to get the full cost of a sequence. 267 * optLevel: when <2, favors small offset for decompression speed (improved cache efficiency) */ 268 FORCE_INLINE_TEMPLATE U32 269 ZSTD_getMatchPrice(U32 const offset, 270 U32 const matchLength, 271 const optState_t* const optPtr, 272 int const optLevel) 273 { 274 U32 price; 275 U32 const offCode = ZSTD_highbit32(offset+1); 276 U32 const mlBase = matchLength - MINMATCH; 277 assert(matchLength >= MINMATCH); 278 279 if (optPtr->priceType == zop_predef) /* fixed scheme, do not use statistics */ 280 return WEIGHT(mlBase, optLevel) + ((16 + offCode) * BITCOST_MULTIPLIER); 281 282 /* dynamic statistics */ 283 price = (offCode * BITCOST_MULTIPLIER) + (optPtr->offCodeSumBasePrice - WEIGHT(optPtr->offCodeFreq[offCode], optLevel)); 284 if ((optLevel<2) /*static*/ && offCode >= 20) 285 price += (offCode-19)*2 * BITCOST_MULTIPLIER; /* handicap for long distance offsets, favor decompression speed */ 286 287 /* match Length */ 288 { U32 const mlCode = ZSTD_MLcode(mlBase); 289 price += (ML_bits[mlCode] * BITCOST_MULTIPLIER) + (optPtr->matchLengthSumBasePrice - WEIGHT(optPtr->matchLengthFreq[mlCode], optLevel)); 290 } 291 292 price += BITCOST_MULTIPLIER / 5; /* heuristic : make matches a bit more costly to favor less sequences -> faster decompression speed */ 293 294 DEBUGLOG(8, "ZSTD_getMatchPrice(ml:%u) = %u", matchLength, price); 295 return price; 296 } 297 298 /* ZSTD_updateStats() : 299 * assumption : literals + litLengtn <= iend */ 300 static void ZSTD_updateStats(optState_t* const optPtr, 301 U32 litLength, const BYTE* literals, 302 U32 offsetCode, U32 matchLength) 303 { 304 /* literals */ 305 if (ZSTD_compressedLiterals(optPtr)) { 306 U32 u; 307 for (u=0; u < litLength; u++) 308 optPtr->litFreq[literals[u]] += ZSTD_LITFREQ_ADD; 309 optPtr->litSum += litLength*ZSTD_LITFREQ_ADD; 310 } 311 312 /* literal Length */ 313 { U32 const llCode = ZSTD_LLcode(litLength); 314 optPtr->litLengthFreq[llCode]++; 315 optPtr->litLengthSum++; 316 } 317 318 /* match offset code (0-2=>repCode; 3+=>offset+2) */ 319 { U32 const offCode = ZSTD_highbit32(offsetCode+1); 320 assert(offCode <= MaxOff); 321 optPtr->offCodeFreq[offCode]++; 322 optPtr->offCodeSum++; 323 } 324 325 /* match Length */ 326 { U32 const mlBase = matchLength - MINMATCH; 327 U32 const mlCode = ZSTD_MLcode(mlBase); 328 optPtr->matchLengthFreq[mlCode]++; 329 optPtr->matchLengthSum++; 330 } 331 } 332 333 334 /* ZSTD_readMINMATCH() : 335 * function safe only for comparisons 336 * assumption : memPtr must be at least 4 bytes before end of buffer */ 337 MEM_STATIC U32 ZSTD_readMINMATCH(const void* memPtr, U32 length) 338 { 339 switch (length) 340 { 341 default : 342 case 4 : return MEM_read32(memPtr); 343 case 3 : if (MEM_isLittleEndian()) 344 return MEM_read32(memPtr)<<8; 345 else 346 return MEM_read32(memPtr)>>8; 347 } 348 } 349 350 351 /* Update hashTable3 up to ip (excluded) 352 Assumption : always within prefix (i.e. not within extDict) */ 353 static U32 ZSTD_insertAndFindFirstIndexHash3 (ZSTD_matchState_t* ms, 354 U32* nextToUpdate3, 355 const BYTE* const ip) 356 { 357 U32* const hashTable3 = ms->hashTable3; 358 U32 const hashLog3 = ms->hashLog3; 359 const BYTE* const base = ms->window.base; 360 U32 idx = *nextToUpdate3; 361 U32 const target = (U32)(ip - base); 362 size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3); 363 assert(hashLog3 > 0); 364 365 while(idx < target) { 366 hashTable3[ZSTD_hash3Ptr(base+idx, hashLog3)] = idx; 367 idx++; 368 } 369 370 *nextToUpdate3 = target; 371 return hashTable3[hash3]; 372 } 373 374 375 /*-************************************* 376 * Binary Tree search 377 ***************************************/ 378 /* ZSTD_insertBt1() : add one or multiple positions to tree. 379 * ip : assumed <= iend-8 . 380 * @return : nb of positions added */ 381 static U32 ZSTD_insertBt1( 382 ZSTD_matchState_t* ms, 383 const BYTE* const ip, const BYTE* const iend, 384 U32 const mls, const int extDict) 385 { 386 const ZSTD_compressionParameters* const cParams = &ms->cParams; 387 U32* const hashTable = ms->hashTable; 388 U32 const hashLog = cParams->hashLog; 389 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 390 U32* const bt = ms->chainTable; 391 U32 const btLog = cParams->chainLog - 1; 392 U32 const btMask = (1 << btLog) - 1; 393 U32 matchIndex = hashTable[h]; 394 size_t commonLengthSmaller=0, commonLengthLarger=0; 395 const BYTE* const base = ms->window.base; 396 const BYTE* const dictBase = ms->window.dictBase; 397 const U32 dictLimit = ms->window.dictLimit; 398 const BYTE* const dictEnd = dictBase + dictLimit; 399 const BYTE* const prefixStart = base + dictLimit; 400 const BYTE* match; 401 const U32 curr = (U32)(ip-base); 402 const U32 btLow = btMask >= curr ? 0 : curr - btMask; 403 U32* smallerPtr = bt + 2*(curr&btMask); 404 U32* largerPtr = smallerPtr + 1; 405 U32 dummy32; /* to be nullified at the end */ 406 U32 const windowLow = ms->window.lowLimit; 407 U32 matchEndIdx = curr+8+1; 408 size_t bestLength = 8; 409 U32 nbCompares = 1U << cParams->searchLog; 410 #ifdef ZSTD_C_PREDICT 411 U32 predictedSmall = *(bt + 2*((curr-1)&btMask) + 0); 412 U32 predictedLarge = *(bt + 2*((curr-1)&btMask) + 1); 413 predictedSmall += (predictedSmall>0); 414 predictedLarge += (predictedLarge>0); 415 #endif /* ZSTD_C_PREDICT */ 416 417 DEBUGLOG(8, "ZSTD_insertBt1 (%u)", curr); 418 419 assert(ip <= iend-8); /* required for h calculation */ 420 hashTable[h] = curr; /* Update Hash Table */ 421 422 assert(windowLow > 0); 423 for (; nbCompares && (matchIndex >= windowLow); --nbCompares) { 424 U32* const nextPtr = bt + 2*(matchIndex & btMask); 425 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 426 assert(matchIndex < curr); 427 428 #ifdef ZSTD_C_PREDICT /* note : can create issues when hlog small <= 11 */ 429 const U32* predictPtr = bt + 2*((matchIndex-1) & btMask); /* written this way, as bt is a roll buffer */ 430 if (matchIndex == predictedSmall) { 431 /* no need to check length, result known */ 432 *smallerPtr = matchIndex; 433 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 434 smallerPtr = nextPtr+1; /* new "smaller" => larger of match */ 435 matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ 436 predictedSmall = predictPtr[1] + (predictPtr[1]>0); 437 continue; 438 } 439 if (matchIndex == predictedLarge) { 440 *largerPtr = matchIndex; 441 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 442 largerPtr = nextPtr; 443 matchIndex = nextPtr[0]; 444 predictedLarge = predictPtr[0] + (predictPtr[0]>0); 445 continue; 446 } 447 #endif 448 449 if (!extDict || (matchIndex+matchLength >= dictLimit)) { 450 assert(matchIndex+matchLength >= dictLimit); /* might be wrong if actually extDict */ 451 match = base + matchIndex; 452 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); 453 } else { 454 match = dictBase + matchIndex; 455 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); 456 if (matchIndex+matchLength >= dictLimit) 457 match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ 458 } 459 460 if (matchLength > bestLength) { 461 bestLength = matchLength; 462 if (matchLength > matchEndIdx - matchIndex) 463 matchEndIdx = matchIndex + (U32)matchLength; 464 } 465 466 if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ 467 break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */ 468 } 469 470 if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */ 471 /* match is smaller than current */ 472 *smallerPtr = matchIndex; /* update smaller idx */ 473 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 474 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */ 475 smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */ 476 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */ 477 } else { 478 /* match is larger than current */ 479 *largerPtr = matchIndex; 480 commonLengthLarger = matchLength; 481 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */ 482 largerPtr = nextPtr; 483 matchIndex = nextPtr[0]; 484 } } 485 486 *smallerPtr = *largerPtr = 0; 487 { U32 positions = 0; 488 if (bestLength > 384) positions = MIN(192, (U32)(bestLength - 384)); /* speed optimization */ 489 assert(matchEndIdx > curr + 8); 490 return MAX(positions, matchEndIdx - (curr + 8)); 491 } 492 } 493 494 FORCE_INLINE_TEMPLATE 495 void ZSTD_updateTree_internal( 496 ZSTD_matchState_t* ms, 497 const BYTE* const ip, const BYTE* const iend, 498 const U32 mls, const ZSTD_dictMode_e dictMode) 499 { 500 const BYTE* const base = ms->window.base; 501 U32 const target = (U32)(ip - base); 502 U32 idx = ms->nextToUpdate; 503 DEBUGLOG(6, "ZSTD_updateTree_internal, from %u to %u (dictMode:%u)", 504 idx, target, dictMode); 505 506 while(idx < target) { 507 U32 const forward = ZSTD_insertBt1(ms, base+idx, iend, mls, dictMode == ZSTD_extDict); 508 assert(idx < (U32)(idx + forward)); 509 idx += forward; 510 } 511 assert((size_t)(ip - base) <= (size_t)(U32)(-1)); 512 assert((size_t)(iend - base) <= (size_t)(U32)(-1)); 513 ms->nextToUpdate = target; 514 } 515 516 void ZSTD_updateTree(ZSTD_matchState_t* ms, const BYTE* ip, const BYTE* iend) { 517 ZSTD_updateTree_internal(ms, ip, iend, ms->cParams.minMatch, ZSTD_noDict); 518 } 519 520 FORCE_INLINE_TEMPLATE 521 U32 ZSTD_insertBtAndGetAllMatches ( 522 ZSTD_match_t* matches, /* store result (found matches) in this table (presumed large enough) */ 523 ZSTD_matchState_t* ms, 524 U32* nextToUpdate3, 525 const BYTE* const ip, const BYTE* const iLimit, const ZSTD_dictMode_e dictMode, 526 const U32 rep[ZSTD_REP_NUM], 527 U32 const ll0, /* tells if associated literal length is 0 or not. This value must be 0 or 1 */ 528 const U32 lengthToBeat, 529 U32 const mls /* template */) 530 { 531 const ZSTD_compressionParameters* const cParams = &ms->cParams; 532 U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); 533 const BYTE* const base = ms->window.base; 534 U32 const curr = (U32)(ip-base); 535 U32 const hashLog = cParams->hashLog; 536 U32 const minMatch = (mls==3) ? 3 : 4; 537 U32* const hashTable = ms->hashTable; 538 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 539 U32 matchIndex = hashTable[h]; 540 U32* const bt = ms->chainTable; 541 U32 const btLog = cParams->chainLog - 1; 542 U32 const btMask= (1U << btLog) - 1; 543 size_t commonLengthSmaller=0, commonLengthLarger=0; 544 const BYTE* const dictBase = ms->window.dictBase; 545 U32 const dictLimit = ms->window.dictLimit; 546 const BYTE* const dictEnd = dictBase + dictLimit; 547 const BYTE* const prefixStart = base + dictLimit; 548 U32 const btLow = (btMask >= curr) ? 0 : curr - btMask; 549 U32 const windowLow = ZSTD_getLowestMatchIndex(ms, curr, cParams->windowLog); 550 U32 const matchLow = windowLow ? windowLow : 1; 551 U32* smallerPtr = bt + 2*(curr&btMask); 552 U32* largerPtr = bt + 2*(curr&btMask) + 1; 553 U32 matchEndIdx = curr+8+1; /* farthest referenced position of any match => detects repetitive patterns */ 554 U32 dummy32; /* to be nullified at the end */ 555 U32 mnum = 0; 556 U32 nbCompares = 1U << cParams->searchLog; 557 558 const ZSTD_matchState_t* dms = dictMode == ZSTD_dictMatchState ? ms->dictMatchState : NULL; 559 const ZSTD_compressionParameters* const dmsCParams = 560 dictMode == ZSTD_dictMatchState ? &dms->cParams : NULL; 561 const BYTE* const dmsBase = dictMode == ZSTD_dictMatchState ? dms->window.base : NULL; 562 const BYTE* const dmsEnd = dictMode == ZSTD_dictMatchState ? dms->window.nextSrc : NULL; 563 U32 const dmsHighLimit = dictMode == ZSTD_dictMatchState ? (U32)(dmsEnd - dmsBase) : 0; 564 U32 const dmsLowLimit = dictMode == ZSTD_dictMatchState ? dms->window.lowLimit : 0; 565 U32 const dmsIndexDelta = dictMode == ZSTD_dictMatchState ? windowLow - dmsHighLimit : 0; 566 U32 const dmsHashLog = dictMode == ZSTD_dictMatchState ? dmsCParams->hashLog : hashLog; 567 U32 const dmsBtLog = dictMode == ZSTD_dictMatchState ? dmsCParams->chainLog - 1 : btLog; 568 U32 const dmsBtMask = dictMode == ZSTD_dictMatchState ? (1U << dmsBtLog) - 1 : 0; 569 U32 const dmsBtLow = dictMode == ZSTD_dictMatchState && dmsBtMask < dmsHighLimit - dmsLowLimit ? dmsHighLimit - dmsBtMask : dmsLowLimit; 570 571 size_t bestLength = lengthToBeat-1; 572 DEBUGLOG(8, "ZSTD_insertBtAndGetAllMatches: current=%u", curr); 573 574 /* check repCode */ 575 assert(ll0 <= 1); /* necessarily 1 or 0 */ 576 { U32 const lastR = ZSTD_REP_NUM + ll0; 577 U32 repCode; 578 for (repCode = ll0; repCode < lastR; repCode++) { 579 U32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 580 U32 const repIndex = curr - repOffset; 581 U32 repLen = 0; 582 assert(curr >= dictLimit); 583 if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < curr-dictLimit) { /* equivalent to `curr > repIndex >= dictLimit` */ 584 /* We must validate the repcode offset because when we're using a dictionary the 585 * valid offset range shrinks when the dictionary goes out of bounds. 586 */ 587 if ((repIndex >= windowLow) & (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch))) { 588 repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch; 589 } 590 } else { /* repIndex < dictLimit || repIndex >= curr */ 591 const BYTE* const repMatch = dictMode == ZSTD_dictMatchState ? 592 dmsBase + repIndex - dmsIndexDelta : 593 dictBase + repIndex; 594 assert(curr >= windowLow); 595 if ( dictMode == ZSTD_extDict 596 && ( ((repOffset-1) /*intentional overflow*/ < curr - windowLow) /* equivalent to `curr > repIndex >= windowLow` */ 597 & (((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */) 598 && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { 599 repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch; 600 } 601 if (dictMode == ZSTD_dictMatchState 602 && ( ((repOffset-1) /*intentional overflow*/ < curr - (dmsLowLimit + dmsIndexDelta)) /* equivalent to `curr > repIndex >= dmsLowLimit` */ 603 & ((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */ 604 && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { 605 repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dmsEnd, prefixStart) + minMatch; 606 } } 607 /* save longer solution */ 608 if (repLen > bestLength) { 609 DEBUGLOG(8, "found repCode %u (ll0:%u, offset:%u) of length %u", 610 repCode, ll0, repOffset, repLen); 611 bestLength = repLen; 612 matches[mnum].off = repCode - ll0; 613 matches[mnum].len = (U32)repLen; 614 mnum++; 615 if ( (repLen > sufficient_len) 616 | (ip+repLen == iLimit) ) { /* best possible */ 617 return mnum; 618 } } } } 619 620 /* HC3 match finder */ 621 if ((mls == 3) /*static*/ && (bestLength < mls)) { 622 U32 const matchIndex3 = ZSTD_insertAndFindFirstIndexHash3(ms, nextToUpdate3, ip); 623 if ((matchIndex3 >= matchLow) 624 & (curr - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) { 625 size_t mlen; 626 if ((dictMode == ZSTD_noDict) /*static*/ || (dictMode == ZSTD_dictMatchState) /*static*/ || (matchIndex3 >= dictLimit)) { 627 const BYTE* const match = base + matchIndex3; 628 mlen = ZSTD_count(ip, match, iLimit); 629 } else { 630 const BYTE* const match = dictBase + matchIndex3; 631 mlen = ZSTD_count_2segments(ip, match, iLimit, dictEnd, prefixStart); 632 } 633 634 /* save best solution */ 635 if (mlen >= mls /* == 3 > bestLength */) { 636 DEBUGLOG(8, "found small match with hlog3, of length %u", 637 (U32)mlen); 638 bestLength = mlen; 639 assert(curr > matchIndex3); 640 assert(mnum==0); /* no prior solution */ 641 matches[0].off = (curr - matchIndex3) + ZSTD_REP_MOVE; 642 matches[0].len = (U32)mlen; 643 mnum = 1; 644 if ( (mlen > sufficient_len) | 645 (ip+mlen == iLimit) ) { /* best possible length */ 646 ms->nextToUpdate = curr+1; /* skip insertion */ 647 return 1; 648 } } } 649 /* no dictMatchState lookup: dicts don't have a populated HC3 table */ 650 } 651 652 hashTable[h] = curr; /* Update Hash Table */ 653 654 for (; nbCompares && (matchIndex >= matchLow); --nbCompares) { 655 U32* const nextPtr = bt + 2*(matchIndex & btMask); 656 const BYTE* match; 657 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 658 assert(curr > matchIndex); 659 660 if ((dictMode == ZSTD_noDict) || (dictMode == ZSTD_dictMatchState) || (matchIndex+matchLength >= dictLimit)) { 661 assert(matchIndex+matchLength >= dictLimit); /* ensure the condition is correct when !extDict */ 662 match = base + matchIndex; 663 if (matchIndex >= dictLimit) assert(memcmp(match, ip, matchLength) == 0); /* ensure early section of match is equal as expected */ 664 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit); 665 } else { 666 match = dictBase + matchIndex; 667 assert(memcmp(match, ip, matchLength) == 0); /* ensure early section of match is equal as expected */ 668 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart); 669 if (matchIndex+matchLength >= dictLimit) 670 match = base + matchIndex; /* prepare for match[matchLength] read */ 671 } 672 673 if (matchLength > bestLength) { 674 DEBUGLOG(8, "found match of length %u at distance %u (offCode=%u)", 675 (U32)matchLength, curr - matchIndex, curr - matchIndex + ZSTD_REP_MOVE); 676 assert(matchEndIdx > matchIndex); 677 if (matchLength > matchEndIdx - matchIndex) 678 matchEndIdx = matchIndex + (U32)matchLength; 679 bestLength = matchLength; 680 matches[mnum].off = (curr - matchIndex) + ZSTD_REP_MOVE; 681 matches[mnum].len = (U32)matchLength; 682 mnum++; 683 if ( (matchLength > ZSTD_OPT_NUM) 684 | (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) { 685 if (dictMode == ZSTD_dictMatchState) nbCompares = 0; /* break should also skip searching dms */ 686 break; /* drop, to preserve bt consistency (miss a little bit of compression) */ 687 } 688 } 689 690 if (match[matchLength] < ip[matchLength]) { 691 /* match smaller than current */ 692 *smallerPtr = matchIndex; /* update smaller idx */ 693 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 694 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 695 smallerPtr = nextPtr+1; /* new candidate => larger than match, which was smaller than current */ 696 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous, closer to current */ 697 } else { 698 *largerPtr = matchIndex; 699 commonLengthLarger = matchLength; 700 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 701 largerPtr = nextPtr; 702 matchIndex = nextPtr[0]; 703 } } 704 705 *smallerPtr = *largerPtr = 0; 706 707 assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ 708 if (dictMode == ZSTD_dictMatchState && nbCompares) { 709 size_t const dmsH = ZSTD_hashPtr(ip, dmsHashLog, mls); 710 U32 dictMatchIndex = dms->hashTable[dmsH]; 711 const U32* const dmsBt = dms->chainTable; 712 commonLengthSmaller = commonLengthLarger = 0; 713 for (; nbCompares && (dictMatchIndex > dmsLowLimit); --nbCompares) { 714 const U32* const nextPtr = dmsBt + 2*(dictMatchIndex & dmsBtMask); 715 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 716 const BYTE* match = dmsBase + dictMatchIndex; 717 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dmsEnd, prefixStart); 718 if (dictMatchIndex+matchLength >= dmsHighLimit) 719 match = base + dictMatchIndex + dmsIndexDelta; /* to prepare for next usage of match[matchLength] */ 720 721 if (matchLength > bestLength) { 722 matchIndex = dictMatchIndex + dmsIndexDelta; 723 DEBUGLOG(8, "found dms match of length %u at distance %u (offCode=%u)", 724 (U32)matchLength, curr - matchIndex, curr - matchIndex + ZSTD_REP_MOVE); 725 if (matchLength > matchEndIdx - matchIndex) 726 matchEndIdx = matchIndex + (U32)matchLength; 727 bestLength = matchLength; 728 matches[mnum].off = (curr - matchIndex) + ZSTD_REP_MOVE; 729 matches[mnum].len = (U32)matchLength; 730 mnum++; 731 if ( (matchLength > ZSTD_OPT_NUM) 732 | (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) { 733 break; /* drop, to guarantee consistency (miss a little bit of compression) */ 734 } 735 } 736 737 if (dictMatchIndex <= dmsBtLow) { break; } /* beyond tree size, stop the search */ 738 if (match[matchLength] < ip[matchLength]) { 739 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 740 dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ 741 } else { 742 /* match is larger than current */ 743 commonLengthLarger = matchLength; 744 dictMatchIndex = nextPtr[0]; 745 } 746 } 747 } 748 749 assert(matchEndIdx > curr+8); 750 ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ 751 return mnum; 752 } 753 754 755 FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches ( 756 ZSTD_match_t* matches, /* store result (match found, increasing size) in this table */ 757 ZSTD_matchState_t* ms, 758 U32* nextToUpdate3, 759 const BYTE* ip, const BYTE* const iHighLimit, const ZSTD_dictMode_e dictMode, 760 const U32 rep[ZSTD_REP_NUM], 761 U32 const ll0, 762 U32 const lengthToBeat) 763 { 764 const ZSTD_compressionParameters* const cParams = &ms->cParams; 765 U32 const matchLengthSearch = cParams->minMatch; 766 DEBUGLOG(8, "ZSTD_BtGetAllMatches"); 767 if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */ 768 ZSTD_updateTree_internal(ms, ip, iHighLimit, matchLengthSearch, dictMode); 769 switch(matchLengthSearch) 770 { 771 case 3 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 3); 772 default : 773 case 4 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 4); 774 case 5 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 5); 775 case 7 : 776 case 6 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 6); 777 } 778 } 779 780 /* *********************** 781 * LDM helper functions * 782 *************************/ 783 784 /* Struct containing info needed to make decision about ldm inclusion */ 785 typedef struct { 786 rawSeqStore_t seqStore; /* External match candidates store for this block */ 787 U32 startPosInBlock; /* Start position of the current match candidate */ 788 U32 endPosInBlock; /* End position of the current match candidate */ 789 U32 offset; /* Offset of the match candidate */ 790 } ZSTD_optLdm_t; 791 792 /* ZSTD_optLdm_skipRawSeqStoreBytes(): 793 * Moves forward in rawSeqStore by nbBytes, which will update the fields 'pos' and 'posInSequence'. 794 */ 795 static void ZSTD_optLdm_skipRawSeqStoreBytes(rawSeqStore_t* rawSeqStore, size_t nbBytes) { 796 U32 currPos = (U32)(rawSeqStore->posInSequence + nbBytes); 797 while (currPos && rawSeqStore->pos < rawSeqStore->size) { 798 rawSeq currSeq = rawSeqStore->seq[rawSeqStore->pos]; 799 if (currPos >= currSeq.litLength + currSeq.matchLength) { 800 currPos -= currSeq.litLength + currSeq.matchLength; 801 rawSeqStore->pos++; 802 } else { 803 rawSeqStore->posInSequence = currPos; 804 break; 805 } 806 } 807 if (currPos == 0 || rawSeqStore->pos == rawSeqStore->size) { 808 rawSeqStore->posInSequence = 0; 809 } 810 } 811 812 /* ZSTD_opt_getNextMatchAndUpdateSeqStore(): 813 * Calculates the beginning and end of the next match in the current block. 814 * Updates 'pos' and 'posInSequence' of the ldmSeqStore. 815 */ 816 static void ZSTD_opt_getNextMatchAndUpdateSeqStore(ZSTD_optLdm_t* optLdm, U32 currPosInBlock, 817 U32 blockBytesRemaining) { 818 rawSeq currSeq; 819 U32 currBlockEndPos; 820 U32 literalsBytesRemaining; 821 U32 matchBytesRemaining; 822 823 /* Setting match end position to MAX to ensure we never use an LDM during this block */ 824 if (optLdm->seqStore.size == 0 || optLdm->seqStore.pos >= optLdm->seqStore.size) { 825 optLdm->startPosInBlock = UINT_MAX; 826 optLdm->endPosInBlock = UINT_MAX; 827 return; 828 } 829 /* Calculate appropriate bytes left in matchLength and litLength after adjusting 830 based on ldmSeqStore->posInSequence */ 831 currSeq = optLdm->seqStore.seq[optLdm->seqStore.pos]; 832 assert(optLdm->seqStore.posInSequence <= currSeq.litLength + currSeq.matchLength); 833 currBlockEndPos = currPosInBlock + blockBytesRemaining; 834 literalsBytesRemaining = (optLdm->seqStore.posInSequence < currSeq.litLength) ? 835 currSeq.litLength - (U32)optLdm->seqStore.posInSequence : 836 0; 837 matchBytesRemaining = (literalsBytesRemaining == 0) ? 838 currSeq.matchLength - ((U32)optLdm->seqStore.posInSequence - currSeq.litLength) : 839 currSeq.matchLength; 840 841 /* If there are more literal bytes than bytes remaining in block, no ldm is possible */ 842 if (literalsBytesRemaining >= blockBytesRemaining) { 843 optLdm->startPosInBlock = UINT_MAX; 844 optLdm->endPosInBlock = UINT_MAX; 845 ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, blockBytesRemaining); 846 return; 847 } 848 849 /* Matches may be < MINMATCH by this process. In that case, we will reject them 850 when we are deciding whether or not to add the ldm */ 851 optLdm->startPosInBlock = currPosInBlock + literalsBytesRemaining; 852 optLdm->endPosInBlock = optLdm->startPosInBlock + matchBytesRemaining; 853 optLdm->offset = currSeq.offset; 854 855 if (optLdm->endPosInBlock > currBlockEndPos) { 856 /* Match ends after the block ends, we can't use the whole match */ 857 optLdm->endPosInBlock = currBlockEndPos; 858 ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, currBlockEndPos - currPosInBlock); 859 } else { 860 /* Consume nb of bytes equal to size of sequence left */ 861 ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, literalsBytesRemaining + matchBytesRemaining); 862 } 863 } 864 865 /* ZSTD_optLdm_maybeAddMatch(): 866 * Adds a match if it's long enough, based on it's 'matchStartPosInBlock' 867 * and 'matchEndPosInBlock', into 'matches'. Maintains the correct ordering of 'matches' 868 */ 869 static void ZSTD_optLdm_maybeAddMatch(ZSTD_match_t* matches, U32* nbMatches, 870 ZSTD_optLdm_t* optLdm, U32 currPosInBlock) { 871 U32 posDiff = currPosInBlock - optLdm->startPosInBlock; 872 /* Note: ZSTD_match_t actually contains offCode and matchLength (before subtracting MINMATCH) */ 873 U32 candidateMatchLength = optLdm->endPosInBlock - optLdm->startPosInBlock - posDiff; 874 U32 candidateOffCode = optLdm->offset + ZSTD_REP_MOVE; 875 876 /* Ensure that current block position is not outside of the match */ 877 if (currPosInBlock < optLdm->startPosInBlock 878 || currPosInBlock >= optLdm->endPosInBlock 879 || candidateMatchLength < MINMATCH) { 880 return; 881 } 882 883 if (*nbMatches == 0 || ((candidateMatchLength > matches[*nbMatches-1].len) && *nbMatches < ZSTD_OPT_NUM)) { 884 DEBUGLOG(6, "ZSTD_optLdm_maybeAddMatch(): Adding ldm candidate match (offCode: %u matchLength %u) at block position=%u", 885 candidateOffCode, candidateMatchLength, currPosInBlock); 886 matches[*nbMatches].len = candidateMatchLength; 887 matches[*nbMatches].off = candidateOffCode; 888 (*nbMatches)++; 889 } 890 } 891 892 /* ZSTD_optLdm_processMatchCandidate(): 893 * Wrapper function to update ldm seq store and call ldm functions as necessary. 894 */ 895 static void ZSTD_optLdm_processMatchCandidate(ZSTD_optLdm_t* optLdm, ZSTD_match_t* matches, U32* nbMatches, 896 U32 currPosInBlock, U32 remainingBytes) { 897 if (optLdm->seqStore.size == 0 || optLdm->seqStore.pos >= optLdm->seqStore.size) { 898 return; 899 } 900 901 if (currPosInBlock >= optLdm->endPosInBlock) { 902 if (currPosInBlock > optLdm->endPosInBlock) { 903 /* The position at which ZSTD_optLdm_processMatchCandidate() is called is not necessarily 904 * at the end of a match from the ldm seq store, and will often be some bytes 905 * over beyond matchEndPosInBlock. As such, we need to correct for these "overshoots" 906 */ 907 U32 posOvershoot = currPosInBlock - optLdm->endPosInBlock; 908 ZSTD_optLdm_skipRawSeqStoreBytes(&optLdm->seqStore, posOvershoot); 909 } 910 ZSTD_opt_getNextMatchAndUpdateSeqStore(optLdm, currPosInBlock, remainingBytes); 911 } 912 ZSTD_optLdm_maybeAddMatch(matches, nbMatches, optLdm, currPosInBlock); 913 } 914 915 /*-******************************* 916 * Optimal parser 917 *********************************/ 918 919 920 static U32 ZSTD_totalLen(ZSTD_optimal_t sol) 921 { 922 return sol.litlen + sol.mlen; 923 } 924 925 #if 0 /* debug */ 926 927 static void 928 listStats(const U32* table, int lastEltID) 929 { 930 int const nbElts = lastEltID + 1; 931 int enb; 932 for (enb=0; enb < nbElts; enb++) { 933 (void)table; 934 /* RAWLOG(2, "%3i:%3i, ", enb, table[enb]); */ 935 RAWLOG(2, "%4i,", table[enb]); 936 } 937 RAWLOG(2, " \n"); 938 } 939 940 #endif 941 942 FORCE_INLINE_TEMPLATE size_t 943 ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms, 944 seqStore_t* seqStore, 945 U32 rep[ZSTD_REP_NUM], 946 const void* src, size_t srcSize, 947 const int optLevel, 948 const ZSTD_dictMode_e dictMode) 949 { 950 optState_t* const optStatePtr = &ms->opt; 951 const BYTE* const istart = (const BYTE*)src; 952 const BYTE* ip = istart; 953 const BYTE* anchor = istart; 954 const BYTE* const iend = istart + srcSize; 955 const BYTE* const ilimit = iend - 8; 956 const BYTE* const base = ms->window.base; 957 const BYTE* const prefixStart = base + ms->window.dictLimit; 958 const ZSTD_compressionParameters* const cParams = &ms->cParams; 959 960 U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); 961 U32 const minMatch = (cParams->minMatch == 3) ? 3 : 4; 962 U32 nextToUpdate3 = ms->nextToUpdate; 963 964 ZSTD_optimal_t* const opt = optStatePtr->priceTable; 965 ZSTD_match_t* const matches = optStatePtr->matchTable; 966 ZSTD_optimal_t lastSequence; 967 ZSTD_optLdm_t optLdm; 968 969 optLdm.seqStore = ms->ldmSeqStore ? *ms->ldmSeqStore : kNullRawSeqStore; 970 optLdm.endPosInBlock = optLdm.startPosInBlock = optLdm.offset = 0; 971 ZSTD_opt_getNextMatchAndUpdateSeqStore(&optLdm, (U32)(ip-istart), (U32)(iend-ip)); 972 973 /* init */ 974 DEBUGLOG(5, "ZSTD_compressBlock_opt_generic: current=%u, prefix=%u, nextToUpdate=%u", 975 (U32)(ip - base), ms->window.dictLimit, ms->nextToUpdate); 976 assert(optLevel <= 2); 977 ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize, optLevel); 978 ip += (ip==prefixStart); 979 980 /* Match Loop */ 981 while (ip < ilimit) { 982 U32 cur, last_pos = 0; 983 984 /* find first match */ 985 { U32 const litlen = (U32)(ip - anchor); 986 U32 const ll0 = !litlen; 987 U32 nbMatches = ZSTD_BtGetAllMatches(matches, ms, &nextToUpdate3, ip, iend, dictMode, rep, ll0, minMatch); 988 ZSTD_optLdm_processMatchCandidate(&optLdm, matches, &nbMatches, 989 (U32)(ip-istart), (U32)(iend - ip)); 990 if (!nbMatches) { ip++; continue; } 991 992 /* initialize opt[0] */ 993 { U32 i ; for (i=0; i<ZSTD_REP_NUM; i++) opt[0].rep[i] = rep[i]; } 994 opt[0].mlen = 0; /* means is_a_literal */ 995 opt[0].litlen = litlen; 996 /* We don't need to include the actual price of the literals because 997 * it is static for the duration of the forward pass, and is included 998 * in every price. We include the literal length to avoid negative 999 * prices when we subtract the previous literal length. 1000 */ 1001 opt[0].price = ZSTD_litLengthPrice(litlen, optStatePtr, optLevel); 1002 1003 /* large match -> immediate encoding */ 1004 { U32 const maxML = matches[nbMatches-1].len; 1005 U32 const maxOffset = matches[nbMatches-1].off; 1006 DEBUGLOG(6, "found %u matches of maxLength=%u and maxOffCode=%u at cPos=%u => start new series", 1007 nbMatches, maxML, maxOffset, (U32)(ip-prefixStart)); 1008 1009 if (maxML > sufficient_len) { 1010 lastSequence.litlen = litlen; 1011 lastSequence.mlen = maxML; 1012 lastSequence.off = maxOffset; 1013 DEBUGLOG(6, "large match (%u>%u), immediate encoding", 1014 maxML, sufficient_len); 1015 cur = 0; 1016 last_pos = ZSTD_totalLen(lastSequence); 1017 goto _shortestPath; 1018 } } 1019 1020 /* set prices for first matches starting position == 0 */ 1021 { U32 const literalsPrice = opt[0].price + ZSTD_litLengthPrice(0, optStatePtr, optLevel); 1022 U32 pos; 1023 U32 matchNb; 1024 for (pos = 1; pos < minMatch; pos++) { 1025 opt[pos].price = ZSTD_MAX_PRICE; /* mlen, litlen and price will be fixed during forward scanning */ 1026 } 1027 for (matchNb = 0; matchNb < nbMatches; matchNb++) { 1028 U32 const offset = matches[matchNb].off; 1029 U32 const end = matches[matchNb].len; 1030 for ( ; pos <= end ; pos++ ) { 1031 U32 const matchPrice = ZSTD_getMatchPrice(offset, pos, optStatePtr, optLevel); 1032 U32 const sequencePrice = literalsPrice + matchPrice; 1033 DEBUGLOG(7, "rPos:%u => set initial price : %.2f", 1034 pos, ZSTD_fCost(sequencePrice)); 1035 opt[pos].mlen = pos; 1036 opt[pos].off = offset; 1037 opt[pos].litlen = litlen; 1038 opt[pos].price = sequencePrice; 1039 } } 1040 last_pos = pos-1; 1041 } 1042 } 1043 1044 /* check further positions */ 1045 for (cur = 1; cur <= last_pos; cur++) { 1046 const BYTE* const inr = ip + cur; 1047 assert(cur < ZSTD_OPT_NUM); 1048 DEBUGLOG(7, "cPos:%zi==rPos:%u", inr-istart, cur) 1049 1050 /* Fix current position with one literal if cheaper */ 1051 { U32 const litlen = (opt[cur-1].mlen == 0) ? opt[cur-1].litlen + 1 : 1; 1052 int const price = opt[cur-1].price 1053 + ZSTD_rawLiteralsCost(ip+cur-1, 1, optStatePtr, optLevel) 1054 + ZSTD_litLengthPrice(litlen, optStatePtr, optLevel) 1055 - ZSTD_litLengthPrice(litlen-1, optStatePtr, optLevel); 1056 assert(price < 1000000000); /* overflow check */ 1057 if (price <= opt[cur].price) { 1058 DEBUGLOG(7, "cPos:%zi==rPos:%u : better price (%.2f<=%.2f) using literal (ll==%u) (hist:%u,%u,%u)", 1059 inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), litlen, 1060 opt[cur-1].rep[0], opt[cur-1].rep[1], opt[cur-1].rep[2]); 1061 opt[cur].mlen = 0; 1062 opt[cur].off = 0; 1063 opt[cur].litlen = litlen; 1064 opt[cur].price = price; 1065 } else { 1066 DEBUGLOG(7, "cPos:%zi==rPos:%u : literal would cost more (%.2f>%.2f) (hist:%u,%u,%u)", 1067 inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), 1068 opt[cur].rep[0], opt[cur].rep[1], opt[cur].rep[2]); 1069 } 1070 } 1071 1072 /* Set the repcodes of the current position. We must do it here 1073 * because we rely on the repcodes of the 2nd to last sequence being 1074 * correct to set the next chunks repcodes during the backward 1075 * traversal. 1076 */ 1077 ZSTD_STATIC_ASSERT(sizeof(opt[cur].rep) == sizeof(repcodes_t)); 1078 assert(cur >= opt[cur].mlen); 1079 if (opt[cur].mlen != 0) { 1080 U32 const prev = cur - opt[cur].mlen; 1081 repcodes_t newReps = ZSTD_updateRep(opt[prev].rep, opt[cur].off, opt[cur].litlen==0); 1082 ZSTD_memcpy(opt[cur].rep, &newReps, sizeof(repcodes_t)); 1083 } else { 1084 ZSTD_memcpy(opt[cur].rep, opt[cur - 1].rep, sizeof(repcodes_t)); 1085 } 1086 1087 /* last match must start at a minimum distance of 8 from oend */ 1088 if (inr > ilimit) continue; 1089 1090 if (cur == last_pos) break; 1091 1092 if ( (optLevel==0) /*static_test*/ 1093 && (opt[cur+1].price <= opt[cur].price + (BITCOST_MULTIPLIER/2)) ) { 1094 DEBUGLOG(7, "move to next rPos:%u : price is <=", cur+1); 1095 continue; /* skip unpromising positions; about ~+6% speed, -0.01 ratio */ 1096 } 1097 1098 { U32 const ll0 = (opt[cur].mlen != 0); 1099 U32 const litlen = (opt[cur].mlen == 0) ? opt[cur].litlen : 0; 1100 U32 const previousPrice = opt[cur].price; 1101 U32 const basePrice = previousPrice + ZSTD_litLengthPrice(0, optStatePtr, optLevel); 1102 U32 nbMatches = ZSTD_BtGetAllMatches(matches, ms, &nextToUpdate3, inr, iend, dictMode, opt[cur].rep, ll0, minMatch); 1103 U32 matchNb; 1104 1105 ZSTD_optLdm_processMatchCandidate(&optLdm, matches, &nbMatches, 1106 (U32)(inr-istart), (U32)(iend-inr)); 1107 1108 if (!nbMatches) { 1109 DEBUGLOG(7, "rPos:%u : no match found", cur); 1110 continue; 1111 } 1112 1113 { U32 const maxML = matches[nbMatches-1].len; 1114 DEBUGLOG(7, "cPos:%zi==rPos:%u, found %u matches, of maxLength=%u", 1115 inr-istart, cur, nbMatches, maxML); 1116 1117 if ( (maxML > sufficient_len) 1118 || (cur + maxML >= ZSTD_OPT_NUM) ) { 1119 lastSequence.mlen = maxML; 1120 lastSequence.off = matches[nbMatches-1].off; 1121 lastSequence.litlen = litlen; 1122 cur -= (opt[cur].mlen==0) ? opt[cur].litlen : 0; /* last sequence is actually only literals, fix cur to last match - note : may underflow, in which case, it's first sequence, and it's okay */ 1123 last_pos = cur + ZSTD_totalLen(lastSequence); 1124 if (cur > ZSTD_OPT_NUM) cur = 0; /* underflow => first match */ 1125 goto _shortestPath; 1126 } } 1127 1128 /* set prices using matches found at position == cur */ 1129 for (matchNb = 0; matchNb < nbMatches; matchNb++) { 1130 U32 const offset = matches[matchNb].off; 1131 U32 const lastML = matches[matchNb].len; 1132 U32 const startML = (matchNb>0) ? matches[matchNb-1].len+1 : minMatch; 1133 U32 mlen; 1134 1135 DEBUGLOG(7, "testing match %u => offCode=%4u, mlen=%2u, llen=%2u", 1136 matchNb, matches[matchNb].off, lastML, litlen); 1137 1138 for (mlen = lastML; mlen >= startML; mlen--) { /* scan downward */ 1139 U32 const pos = cur + mlen; 1140 int const price = basePrice + ZSTD_getMatchPrice(offset, mlen, optStatePtr, optLevel); 1141 1142 if ((pos > last_pos) || (price < opt[pos].price)) { 1143 DEBUGLOG(7, "rPos:%u (ml=%2u) => new better price (%.2f<%.2f)", 1144 pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price)); 1145 while (last_pos < pos) { opt[last_pos+1].price = ZSTD_MAX_PRICE; last_pos++; } /* fill empty positions */ 1146 opt[pos].mlen = mlen; 1147 opt[pos].off = offset; 1148 opt[pos].litlen = litlen; 1149 opt[pos].price = price; 1150 } else { 1151 DEBUGLOG(7, "rPos:%u (ml=%2u) => new price is worse (%.2f>=%.2f)", 1152 pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price)); 1153 if (optLevel==0) break; /* early update abort; gets ~+10% speed for about -0.01 ratio loss */ 1154 } 1155 } } } 1156 } /* for (cur = 1; cur <= last_pos; cur++) */ 1157 1158 lastSequence = opt[last_pos]; 1159 cur = last_pos > ZSTD_totalLen(lastSequence) ? last_pos - ZSTD_totalLen(lastSequence) : 0; /* single sequence, and it starts before `ip` */ 1160 assert(cur < ZSTD_OPT_NUM); /* control overflow*/ 1161 1162 _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */ 1163 assert(opt[0].mlen == 0); 1164 1165 /* Set the next chunk's repcodes based on the repcodes of the beginning 1166 * of the last match, and the last sequence. This avoids us having to 1167 * update them while traversing the sequences. 1168 */ 1169 if (lastSequence.mlen != 0) { 1170 repcodes_t reps = ZSTD_updateRep(opt[cur].rep, lastSequence.off, lastSequence.litlen==0); 1171 ZSTD_memcpy(rep, &reps, sizeof(reps)); 1172 } else { 1173 ZSTD_memcpy(rep, opt[cur].rep, sizeof(repcodes_t)); 1174 } 1175 1176 { U32 const storeEnd = cur + 1; 1177 U32 storeStart = storeEnd; 1178 U32 seqPos = cur; 1179 1180 DEBUGLOG(6, "start reverse traversal (last_pos:%u, cur:%u)", 1181 last_pos, cur); (void)last_pos; 1182 assert(storeEnd < ZSTD_OPT_NUM); 1183 DEBUGLOG(6, "last sequence copied into pos=%u (llen=%u,mlen=%u,ofc=%u)", 1184 storeEnd, lastSequence.litlen, lastSequence.mlen, lastSequence.off); 1185 opt[storeEnd] = lastSequence; 1186 while (seqPos > 0) { 1187 U32 const backDist = ZSTD_totalLen(opt[seqPos]); 1188 storeStart--; 1189 DEBUGLOG(6, "sequence from rPos=%u copied into pos=%u (llen=%u,mlen=%u,ofc=%u)", 1190 seqPos, storeStart, opt[seqPos].litlen, opt[seqPos].mlen, opt[seqPos].off); 1191 opt[storeStart] = opt[seqPos]; 1192 seqPos = (seqPos > backDist) ? seqPos - backDist : 0; 1193 } 1194 1195 /* save sequences */ 1196 DEBUGLOG(6, "sending selected sequences into seqStore") 1197 { U32 storePos; 1198 for (storePos=storeStart; storePos <= storeEnd; storePos++) { 1199 U32 const llen = opt[storePos].litlen; 1200 U32 const mlen = opt[storePos].mlen; 1201 U32 const offCode = opt[storePos].off; 1202 U32 const advance = llen + mlen; 1203 DEBUGLOG(6, "considering seq starting at %zi, llen=%u, mlen=%u", 1204 anchor - istart, (unsigned)llen, (unsigned)mlen); 1205 1206 if (mlen==0) { /* only literals => must be last "sequence", actually starting a new stream of sequences */ 1207 assert(storePos == storeEnd); /* must be last sequence */ 1208 ip = anchor + llen; /* last "sequence" is a bunch of literals => don't progress anchor */ 1209 continue; /* will finish */ 1210 } 1211 1212 assert(anchor + llen <= iend); 1213 ZSTD_updateStats(optStatePtr, llen, anchor, offCode, mlen); 1214 ZSTD_storeSeq(seqStore, llen, anchor, iend, offCode, mlen-MINMATCH); 1215 anchor += advance; 1216 ip = anchor; 1217 } } 1218 ZSTD_setBasePrices(optStatePtr, optLevel); 1219 } 1220 } /* while (ip < ilimit) */ 1221 1222 /* Return the last literals size */ 1223 return (size_t)(iend - anchor); 1224 } 1225 1226 1227 size_t ZSTD_compressBlock_btopt( 1228 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1229 const void* src, size_t srcSize) 1230 { 1231 DEBUGLOG(5, "ZSTD_compressBlock_btopt"); 1232 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_noDict); 1233 } 1234 1235 1236 /* used in 2-pass strategy */ 1237 static U32 ZSTD_upscaleStat(unsigned* table, U32 lastEltIndex, int bonus) 1238 { 1239 U32 s, sum=0; 1240 assert(ZSTD_FREQ_DIV+bonus >= 0); 1241 for (s=0; s<lastEltIndex+1; s++) { 1242 table[s] <<= ZSTD_FREQ_DIV+bonus; 1243 table[s]--; 1244 sum += table[s]; 1245 } 1246 return sum; 1247 } 1248 1249 /* used in 2-pass strategy */ 1250 MEM_STATIC void ZSTD_upscaleStats(optState_t* optPtr) 1251 { 1252 if (ZSTD_compressedLiterals(optPtr)) 1253 optPtr->litSum = ZSTD_upscaleStat(optPtr->litFreq, MaxLit, 0); 1254 optPtr->litLengthSum = ZSTD_upscaleStat(optPtr->litLengthFreq, MaxLL, 0); 1255 optPtr->matchLengthSum = ZSTD_upscaleStat(optPtr->matchLengthFreq, MaxML, 0); 1256 optPtr->offCodeSum = ZSTD_upscaleStat(optPtr->offCodeFreq, MaxOff, 0); 1257 } 1258 1259 /* ZSTD_initStats_ultra(): 1260 * make a first compression pass, just to seed stats with more accurate starting values. 1261 * only works on first block, with no dictionary and no ldm. 1262 * this function cannot error, hence its contract must be respected. 1263 */ 1264 static void 1265 ZSTD_initStats_ultra(ZSTD_matchState_t* ms, 1266 seqStore_t* seqStore, 1267 U32 rep[ZSTD_REP_NUM], 1268 const void* src, size_t srcSize) 1269 { 1270 U32 tmpRep[ZSTD_REP_NUM]; /* updated rep codes will sink here */ 1271 ZSTD_memcpy(tmpRep, rep, sizeof(tmpRep)); 1272 1273 DEBUGLOG(4, "ZSTD_initStats_ultra (srcSize=%zu)", srcSize); 1274 assert(ms->opt.litLengthSum == 0); /* first block */ 1275 assert(seqStore->sequences == seqStore->sequencesStart); /* no ldm */ 1276 assert(ms->window.dictLimit == ms->window.lowLimit); /* no dictionary */ 1277 assert(ms->window.dictLimit - ms->nextToUpdate <= 1); /* no prefix (note: intentional overflow, defined as 2-complement) */ 1278 1279 ZSTD_compressBlock_opt_generic(ms, seqStore, tmpRep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); /* generate stats into ms->opt*/ 1280 1281 /* invalidate first scan from history */ 1282 ZSTD_resetSeqStore(seqStore); 1283 ms->window.base -= srcSize; 1284 ms->window.dictLimit += (U32)srcSize; 1285 ms->window.lowLimit = ms->window.dictLimit; 1286 ms->nextToUpdate = ms->window.dictLimit; 1287 1288 /* re-inforce weight of collected statistics */ 1289 ZSTD_upscaleStats(&ms->opt); 1290 } 1291 1292 size_t ZSTD_compressBlock_btultra( 1293 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1294 const void* src, size_t srcSize) 1295 { 1296 DEBUGLOG(5, "ZSTD_compressBlock_btultra (srcSize=%zu)", srcSize); 1297 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); 1298 } 1299 1300 size_t ZSTD_compressBlock_btultra2( 1301 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1302 const void* src, size_t srcSize) 1303 { 1304 U32 const curr = (U32)((const BYTE*)src - ms->window.base); 1305 DEBUGLOG(5, "ZSTD_compressBlock_btultra2 (srcSize=%zu)", srcSize); 1306 1307 /* 2-pass strategy: 1308 * this strategy makes a first pass over first block to collect statistics 1309 * and seed next round's statistics with it. 1310 * After 1st pass, function forgets everything, and starts a new block. 1311 * Consequently, this can only work if no data has been previously loaded in tables, 1312 * aka, no dictionary, no prefix, no ldm preprocessing. 1313 * The compression ratio gain is generally small (~0.5% on first block), 1314 * the cost is 2x cpu time on first block. */ 1315 assert(srcSize <= ZSTD_BLOCKSIZE_MAX); 1316 if ( (ms->opt.litLengthSum==0) /* first block */ 1317 && (seqStore->sequences == seqStore->sequencesStart) /* no ldm */ 1318 && (ms->window.dictLimit == ms->window.lowLimit) /* no dictionary */ 1319 && (curr == ms->window.dictLimit) /* start of frame, nothing already loaded nor skipped */ 1320 && (srcSize > ZSTD_PREDEF_THRESHOLD) 1321 ) { 1322 ZSTD_initStats_ultra(ms, seqStore, rep, src, srcSize); 1323 } 1324 1325 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); 1326 } 1327 1328 size_t ZSTD_compressBlock_btopt_dictMatchState( 1329 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1330 const void* src, size_t srcSize) 1331 { 1332 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_dictMatchState); 1333 } 1334 1335 size_t ZSTD_compressBlock_btultra_dictMatchState( 1336 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1337 const void* src, size_t srcSize) 1338 { 1339 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_dictMatchState); 1340 } 1341 1342 size_t ZSTD_compressBlock_btopt_extDict( 1343 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1344 const void* src, size_t srcSize) 1345 { 1346 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_extDict); 1347 } 1348 1349 size_t ZSTD_compressBlock_btultra_extDict( 1350 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1351 const void* src, size_t srcSize) 1352 { 1353 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_extDict); 1354 } 1355 1356 /* note : no btultra2 variant for extDict nor dictMatchState, 1357 * because btultra2 is not meant to work with dictionaries 1358 * and is only specific for the first block (no prefix) */ 1359