1 /* 2 * Copyright (c) 2016-present, 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 #include "zstd_compress_internal.h" 12 #include "hist.h" 13 #include "zstd_opt.h" 14 15 16 #define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats */ 17 #define ZSTD_FREQ_DIV 4 /* log factor when using previous stats to init next stats */ 18 #define ZSTD_MAX_PRICE (1<<30) 19 20 #define ZSTD_PREDEF_THRESHOLD 1024 /* if srcSize < ZSTD_PREDEF_THRESHOLD, symbols' cost is assumed static, directly determined by pre-defined distributions */ 21 22 23 /*-************************************* 24 * Price functions for optimal parser 25 ***************************************/ 26 27 #if 0 /* approximation at bit level */ 28 # define BITCOST_ACCURACY 0 29 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) 30 # define WEIGHT(stat) ((void)opt, ZSTD_bitWeight(stat)) 31 #elif 0 /* fractional bit accuracy */ 32 # define BITCOST_ACCURACY 8 33 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) 34 # define WEIGHT(stat,opt) ((void)opt, ZSTD_fracWeight(stat)) 35 #else /* opt==approx, ultra==accurate */ 36 # define BITCOST_ACCURACY 8 37 # define BITCOST_MULTIPLIER (1 << BITCOST_ACCURACY) 38 # define WEIGHT(stat,opt) (opt ? ZSTD_fracWeight(stat) : ZSTD_bitWeight(stat)) 39 #endif 40 41 MEM_STATIC U32 ZSTD_bitWeight(U32 stat) 42 { 43 return (ZSTD_highbit32(stat+1) * BITCOST_MULTIPLIER); 44 } 45 46 MEM_STATIC U32 ZSTD_fracWeight(U32 rawStat) 47 { 48 U32 const stat = rawStat + 1; 49 U32 const hb = ZSTD_highbit32(stat); 50 U32 const BWeight = hb * BITCOST_MULTIPLIER; 51 U32 const FWeight = (stat << BITCOST_ACCURACY) >> hb; 52 U32 const weight = BWeight + FWeight; 53 assert(hb + BITCOST_ACCURACY < 31); 54 return weight; 55 } 56 57 #if (DEBUGLEVEL>=2) 58 /* debugging function, 59 * @return price in bytes as fractional value 60 * for debug messages only */ 61 MEM_STATIC double ZSTD_fCost(U32 price) 62 { 63 return (double)price / (BITCOST_MULTIPLIER*8); 64 } 65 #endif 66 67 static int ZSTD_compressedLiterals(optState_t const* const optPtr) 68 { 69 return optPtr->literalCompressionMode != ZSTD_lcm_uncompressed; 70 } 71 72 static void ZSTD_setBasePrices(optState_t* optPtr, int optLevel) 73 { 74 if (ZSTD_compressedLiterals(optPtr)) 75 optPtr->litSumBasePrice = WEIGHT(optPtr->litSum, optLevel); 76 optPtr->litLengthSumBasePrice = WEIGHT(optPtr->litLengthSum, optLevel); 77 optPtr->matchLengthSumBasePrice = WEIGHT(optPtr->matchLengthSum, optLevel); 78 optPtr->offCodeSumBasePrice = WEIGHT(optPtr->offCodeSum, optLevel); 79 } 80 81 82 /* ZSTD_downscaleStat() : 83 * reduce all elements in table by a factor 2^(ZSTD_FREQ_DIV+malus) 84 * return the resulting sum of elements */ 85 static U32 ZSTD_downscaleStat(unsigned* table, U32 lastEltIndex, int malus) 86 { 87 U32 s, sum=0; 88 DEBUGLOG(5, "ZSTD_downscaleStat (nbElts=%u)", (unsigned)lastEltIndex+1); 89 assert(ZSTD_FREQ_DIV+malus > 0 && ZSTD_FREQ_DIV+malus < 31); 90 for (s=0; s<lastEltIndex+1; s++) { 91 table[s] = 1 + (table[s] >> (ZSTD_FREQ_DIV+malus)); 92 sum += table[s]; 93 } 94 return sum; 95 } 96 97 /* ZSTD_rescaleFreqs() : 98 * if first block (detected by optPtr->litLengthSum == 0) : init statistics 99 * take hints from dictionary if there is one 100 * or init from zero, using src for literals stats, or flat 1 for match symbols 101 * otherwise downscale existing stats, to be used as seed for next block. 102 */ 103 static void 104 ZSTD_rescaleFreqs(optState_t* const optPtr, 105 const BYTE* const src, size_t const srcSize, 106 int const optLevel) 107 { 108 int const compressedLiterals = ZSTD_compressedLiterals(optPtr); 109 DEBUGLOG(5, "ZSTD_rescaleFreqs (srcSize=%u)", (unsigned)srcSize); 110 optPtr->priceType = zop_dynamic; 111 112 if (optPtr->litLengthSum == 0) { /* first block : init */ 113 if (srcSize <= ZSTD_PREDEF_THRESHOLD) { /* heuristic */ 114 DEBUGLOG(5, "(srcSize <= ZSTD_PREDEF_THRESHOLD) => zop_predef"); 115 optPtr->priceType = zop_predef; 116 } 117 118 assert(optPtr->symbolCosts != NULL); 119 if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid) { 120 /* huffman table presumed generated by dictionary */ 121 optPtr->priceType = zop_dynamic; 122 123 if (compressedLiterals) { 124 unsigned lit; 125 assert(optPtr->litFreq != NULL); 126 optPtr->litSum = 0; 127 for (lit=0; lit<=MaxLit; lit++) { 128 U32 const scaleLog = 11; /* scale to 2K */ 129 U32 const bitCost = HUF_getNbBits(optPtr->symbolCosts->huf.CTable, lit); 130 assert(bitCost <= scaleLog); 131 optPtr->litFreq[lit] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; 132 optPtr->litSum += optPtr->litFreq[lit]; 133 } } 134 135 { unsigned ll; 136 FSE_CState_t llstate; 137 FSE_initCState(&llstate, optPtr->symbolCosts->fse.litlengthCTable); 138 optPtr->litLengthSum = 0; 139 for (ll=0; ll<=MaxLL; ll++) { 140 U32 const scaleLog = 10; /* scale to 1K */ 141 U32 const bitCost = FSE_getMaxNbBits(llstate.symbolTT, ll); 142 assert(bitCost < scaleLog); 143 optPtr->litLengthFreq[ll] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; 144 optPtr->litLengthSum += optPtr->litLengthFreq[ll]; 145 } } 146 147 { unsigned ml; 148 FSE_CState_t mlstate; 149 FSE_initCState(&mlstate, optPtr->symbolCosts->fse.matchlengthCTable); 150 optPtr->matchLengthSum = 0; 151 for (ml=0; ml<=MaxML; ml++) { 152 U32 const scaleLog = 10; 153 U32 const bitCost = FSE_getMaxNbBits(mlstate.symbolTT, ml); 154 assert(bitCost < scaleLog); 155 optPtr->matchLengthFreq[ml] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; 156 optPtr->matchLengthSum += optPtr->matchLengthFreq[ml]; 157 } } 158 159 { unsigned of; 160 FSE_CState_t ofstate; 161 FSE_initCState(&ofstate, optPtr->symbolCosts->fse.offcodeCTable); 162 optPtr->offCodeSum = 0; 163 for (of=0; of<=MaxOff; of++) { 164 U32 const scaleLog = 10; 165 U32 const bitCost = FSE_getMaxNbBits(ofstate.symbolTT, of); 166 assert(bitCost < scaleLog); 167 optPtr->offCodeFreq[of] = bitCost ? 1 << (scaleLog-bitCost) : 1 /*minimum to calculate cost*/; 168 optPtr->offCodeSum += optPtr->offCodeFreq[of]; 169 } } 170 171 } else { /* not a dictionary */ 172 173 assert(optPtr->litFreq != NULL); 174 if (compressedLiterals) { 175 unsigned lit = MaxLit; 176 HIST_count_simple(optPtr->litFreq, &lit, src, srcSize); /* use raw first block to init statistics */ 177 optPtr->litSum = ZSTD_downscaleStat(optPtr->litFreq, MaxLit, 1); 178 } 179 180 { unsigned ll; 181 for (ll=0; ll<=MaxLL; ll++) 182 optPtr->litLengthFreq[ll] = 1; 183 } 184 optPtr->litLengthSum = MaxLL+1; 185 186 { unsigned ml; 187 for (ml=0; ml<=MaxML; ml++) 188 optPtr->matchLengthFreq[ml] = 1; 189 } 190 optPtr->matchLengthSum = MaxML+1; 191 192 { unsigned of; 193 for (of=0; of<=MaxOff; of++) 194 optPtr->offCodeFreq[of] = 1; 195 } 196 optPtr->offCodeSum = MaxOff+1; 197 198 } 199 200 } else { /* new block : re-use previous statistics, scaled down */ 201 202 if (compressedLiterals) 203 optPtr->litSum = ZSTD_downscaleStat(optPtr->litFreq, MaxLit, 1); 204 optPtr->litLengthSum = ZSTD_downscaleStat(optPtr->litLengthFreq, MaxLL, 0); 205 optPtr->matchLengthSum = ZSTD_downscaleStat(optPtr->matchLengthFreq, MaxML, 0); 206 optPtr->offCodeSum = ZSTD_downscaleStat(optPtr->offCodeFreq, MaxOff, 0); 207 } 208 209 ZSTD_setBasePrices(optPtr, optLevel); 210 } 211 212 /* ZSTD_rawLiteralsCost() : 213 * price of literals (only) in specified segment (which length can be 0). 214 * does not include price of literalLength symbol */ 215 static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength, 216 const optState_t* const optPtr, 217 int optLevel) 218 { 219 if (litLength == 0) return 0; 220 221 if (!ZSTD_compressedLiterals(optPtr)) 222 return (litLength << 3) * BITCOST_MULTIPLIER; /* Uncompressed - 8 bytes per literal. */ 223 224 if (optPtr->priceType == zop_predef) 225 return (litLength*6) * BITCOST_MULTIPLIER; /* 6 bit per literal - no statistic used */ 226 227 /* dynamic statistics */ 228 { U32 price = litLength * optPtr->litSumBasePrice; 229 U32 u; 230 for (u=0; u < litLength; u++) { 231 assert(WEIGHT(optPtr->litFreq[literals[u]], optLevel) <= optPtr->litSumBasePrice); /* literal cost should never be negative */ 232 price -= WEIGHT(optPtr->litFreq[literals[u]], optLevel); 233 } 234 return price; 235 } 236 } 237 238 /* ZSTD_litLengthPrice() : 239 * cost of literalLength symbol */ 240 static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optPtr, int optLevel) 241 { 242 if (optPtr->priceType == zop_predef) return WEIGHT(litLength, optLevel); 243 244 /* dynamic statistics */ 245 { U32 const llCode = ZSTD_LLcode(litLength); 246 return (LL_bits[llCode] * BITCOST_MULTIPLIER) 247 + optPtr->litLengthSumBasePrice 248 - WEIGHT(optPtr->litLengthFreq[llCode], optLevel); 249 } 250 } 251 252 /* ZSTD_litLengthContribution() : 253 * @return ( cost(litlength) - cost(0) ) 254 * this value can then be added to rawLiteralsCost() 255 * to provide a cost which is directly comparable to a match ending at same position */ 256 static int ZSTD_litLengthContribution(U32 const litLength, const optState_t* const optPtr, int optLevel) 257 { 258 if (optPtr->priceType >= zop_predef) return WEIGHT(litLength, optLevel); 259 260 /* dynamic statistics */ 261 { U32 const llCode = ZSTD_LLcode(litLength); 262 int const contribution = (LL_bits[llCode] * BITCOST_MULTIPLIER) 263 + WEIGHT(optPtr->litLengthFreq[0], optLevel) /* note: log2litLengthSum cancel out */ 264 - WEIGHT(optPtr->litLengthFreq[llCode], optLevel); 265 #if 1 266 return contribution; 267 #else 268 return MAX(0, contribution); /* sometimes better, sometimes not ... */ 269 #endif 270 } 271 } 272 273 /* ZSTD_literalsContribution() : 274 * creates a fake cost for the literals part of a sequence 275 * which can be compared to the ending cost of a match 276 * should a new match start at this position */ 277 static int ZSTD_literalsContribution(const BYTE* const literals, U32 const litLength, 278 const optState_t* const optPtr, 279 int optLevel) 280 { 281 int const contribution = ZSTD_rawLiteralsCost(literals, litLength, optPtr, optLevel) 282 + ZSTD_litLengthContribution(litLength, optPtr, optLevel); 283 return contribution; 284 } 285 286 /* ZSTD_getMatchPrice() : 287 * Provides the cost of the match part (offset + matchLength) of a sequence 288 * Must be combined with ZSTD_fullLiteralsCost() to get the full cost of a sequence. 289 * optLevel: when <2, favors small offset for decompression speed (improved cache efficiency) */ 290 FORCE_INLINE_TEMPLATE U32 291 ZSTD_getMatchPrice(U32 const offset, 292 U32 const matchLength, 293 const optState_t* const optPtr, 294 int const optLevel) 295 { 296 U32 price; 297 U32 const offCode = ZSTD_highbit32(offset+1); 298 U32 const mlBase = matchLength - MINMATCH; 299 assert(matchLength >= MINMATCH); 300 301 if (optPtr->priceType == zop_predef) /* fixed scheme, do not use statistics */ 302 return WEIGHT(mlBase, optLevel) + ((16 + offCode) * BITCOST_MULTIPLIER); 303 304 /* dynamic statistics */ 305 price = (offCode * BITCOST_MULTIPLIER) + (optPtr->offCodeSumBasePrice - WEIGHT(optPtr->offCodeFreq[offCode], optLevel)); 306 if ((optLevel<2) /*static*/ && offCode >= 20) 307 price += (offCode-19)*2 * BITCOST_MULTIPLIER; /* handicap for long distance offsets, favor decompression speed */ 308 309 /* match Length */ 310 { U32 const mlCode = ZSTD_MLcode(mlBase); 311 price += (ML_bits[mlCode] * BITCOST_MULTIPLIER) + (optPtr->matchLengthSumBasePrice - WEIGHT(optPtr->matchLengthFreq[mlCode], optLevel)); 312 } 313 314 price += BITCOST_MULTIPLIER / 5; /* heuristic : make matches a bit more costly to favor less sequences -> faster decompression speed */ 315 316 DEBUGLOG(8, "ZSTD_getMatchPrice(ml:%u) = %u", matchLength, price); 317 return price; 318 } 319 320 /* ZSTD_updateStats() : 321 * assumption : literals + litLengtn <= iend */ 322 static void ZSTD_updateStats(optState_t* const optPtr, 323 U32 litLength, const BYTE* literals, 324 U32 offsetCode, U32 matchLength) 325 { 326 /* literals */ 327 if (ZSTD_compressedLiterals(optPtr)) { 328 U32 u; 329 for (u=0; u < litLength; u++) 330 optPtr->litFreq[literals[u]] += ZSTD_LITFREQ_ADD; 331 optPtr->litSum += litLength*ZSTD_LITFREQ_ADD; 332 } 333 334 /* literal Length */ 335 { U32 const llCode = ZSTD_LLcode(litLength); 336 optPtr->litLengthFreq[llCode]++; 337 optPtr->litLengthSum++; 338 } 339 340 /* match offset code (0-2=>repCode; 3+=>offset+2) */ 341 { U32 const offCode = ZSTD_highbit32(offsetCode+1); 342 assert(offCode <= MaxOff); 343 optPtr->offCodeFreq[offCode]++; 344 optPtr->offCodeSum++; 345 } 346 347 /* match Length */ 348 { U32 const mlBase = matchLength - MINMATCH; 349 U32 const mlCode = ZSTD_MLcode(mlBase); 350 optPtr->matchLengthFreq[mlCode]++; 351 optPtr->matchLengthSum++; 352 } 353 } 354 355 356 /* ZSTD_readMINMATCH() : 357 * function safe only for comparisons 358 * assumption : memPtr must be at least 4 bytes before end of buffer */ 359 MEM_STATIC U32 ZSTD_readMINMATCH(const void* memPtr, U32 length) 360 { 361 switch (length) 362 { 363 default : 364 case 4 : return MEM_read32(memPtr); 365 case 3 : if (MEM_isLittleEndian()) 366 return MEM_read32(memPtr)<<8; 367 else 368 return MEM_read32(memPtr)>>8; 369 } 370 } 371 372 373 /* Update hashTable3 up to ip (excluded) 374 Assumption : always within prefix (i.e. not within extDict) */ 375 static U32 ZSTD_insertAndFindFirstIndexHash3 (ZSTD_matchState_t* ms, const BYTE* const ip) 376 { 377 U32* const hashTable3 = ms->hashTable3; 378 U32 const hashLog3 = ms->hashLog3; 379 const BYTE* const base = ms->window.base; 380 U32 idx = ms->nextToUpdate3; 381 U32 const target = ms->nextToUpdate3 = (U32)(ip - base); 382 size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3); 383 assert(hashLog3 > 0); 384 385 while(idx < target) { 386 hashTable3[ZSTD_hash3Ptr(base+idx, hashLog3)] = idx; 387 idx++; 388 } 389 390 return hashTable3[hash3]; 391 } 392 393 394 /*-************************************* 395 * Binary Tree search 396 ***************************************/ 397 /** ZSTD_insertBt1() : add one or multiple positions to tree. 398 * ip : assumed <= iend-8 . 399 * @return : nb of positions added */ 400 static U32 ZSTD_insertBt1( 401 ZSTD_matchState_t* ms, 402 const BYTE* const ip, const BYTE* const iend, 403 U32 const mls, const int extDict) 404 { 405 const ZSTD_compressionParameters* const cParams = &ms->cParams; 406 U32* const hashTable = ms->hashTable; 407 U32 const hashLog = cParams->hashLog; 408 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 409 U32* const bt = ms->chainTable; 410 U32 const btLog = cParams->chainLog - 1; 411 U32 const btMask = (1 << btLog) - 1; 412 U32 matchIndex = hashTable[h]; 413 size_t commonLengthSmaller=0, commonLengthLarger=0; 414 const BYTE* const base = ms->window.base; 415 const BYTE* const dictBase = ms->window.dictBase; 416 const U32 dictLimit = ms->window.dictLimit; 417 const BYTE* const dictEnd = dictBase + dictLimit; 418 const BYTE* const prefixStart = base + dictLimit; 419 const BYTE* match; 420 const U32 current = (U32)(ip-base); 421 const U32 btLow = btMask >= current ? 0 : current - btMask; 422 U32* smallerPtr = bt + 2*(current&btMask); 423 U32* largerPtr = smallerPtr + 1; 424 U32 dummy32; /* to be nullified at the end */ 425 U32 const windowLow = ms->window.lowLimit; 426 U32 matchEndIdx = current+8+1; 427 size_t bestLength = 8; 428 U32 nbCompares = 1U << cParams->searchLog; 429 #ifdef ZSTD_C_PREDICT 430 U32 predictedSmall = *(bt + 2*((current-1)&btMask) + 0); 431 U32 predictedLarge = *(bt + 2*((current-1)&btMask) + 1); 432 predictedSmall += (predictedSmall>0); 433 predictedLarge += (predictedLarge>0); 434 #endif /* ZSTD_C_PREDICT */ 435 436 DEBUGLOG(8, "ZSTD_insertBt1 (%u)", current); 437 438 assert(ip <= iend-8); /* required for h calculation */ 439 hashTable[h] = current; /* Update Hash Table */ 440 441 assert(windowLow > 0); 442 while (nbCompares-- && (matchIndex >= windowLow)) { 443 U32* const nextPtr = bt + 2*(matchIndex & btMask); 444 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 445 assert(matchIndex < current); 446 447 #ifdef ZSTD_C_PREDICT /* note : can create issues when hlog small <= 11 */ 448 const U32* predictPtr = bt + 2*((matchIndex-1) & btMask); /* written this way, as bt is a roll buffer */ 449 if (matchIndex == predictedSmall) { 450 /* no need to check length, result known */ 451 *smallerPtr = matchIndex; 452 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 453 smallerPtr = nextPtr+1; /* new "smaller" => larger of match */ 454 matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ 455 predictedSmall = predictPtr[1] + (predictPtr[1]>0); 456 continue; 457 } 458 if (matchIndex == predictedLarge) { 459 *largerPtr = matchIndex; 460 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 461 largerPtr = nextPtr; 462 matchIndex = nextPtr[0]; 463 predictedLarge = predictPtr[0] + (predictPtr[0]>0); 464 continue; 465 } 466 #endif 467 468 if (!extDict || (matchIndex+matchLength >= dictLimit)) { 469 assert(matchIndex+matchLength >= dictLimit); /* might be wrong if actually extDict */ 470 match = base + matchIndex; 471 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); 472 } else { 473 match = dictBase + matchIndex; 474 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); 475 if (matchIndex+matchLength >= dictLimit) 476 match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ 477 } 478 479 if (matchLength > bestLength) { 480 bestLength = matchLength; 481 if (matchLength > matchEndIdx - matchIndex) 482 matchEndIdx = matchIndex + (U32)matchLength; 483 } 484 485 if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ 486 break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */ 487 } 488 489 if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */ 490 /* match is smaller than current */ 491 *smallerPtr = matchIndex; /* update smaller idx */ 492 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 493 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */ 494 smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */ 495 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */ 496 } else { 497 /* match is larger than current */ 498 *largerPtr = matchIndex; 499 commonLengthLarger = matchLength; 500 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */ 501 largerPtr = nextPtr; 502 matchIndex = nextPtr[0]; 503 } } 504 505 *smallerPtr = *largerPtr = 0; 506 if (bestLength > 384) return MIN(192, (U32)(bestLength - 384)); /* speed optimization */ 507 assert(matchEndIdx > current + 8); 508 return matchEndIdx - (current + 8); 509 } 510 511 FORCE_INLINE_TEMPLATE 512 void ZSTD_updateTree_internal( 513 ZSTD_matchState_t* ms, 514 const BYTE* const ip, const BYTE* const iend, 515 const U32 mls, const ZSTD_dictMode_e dictMode) 516 { 517 const BYTE* const base = ms->window.base; 518 U32 const target = (U32)(ip - base); 519 U32 idx = ms->nextToUpdate; 520 DEBUGLOG(6, "ZSTD_updateTree_internal, from %u to %u (dictMode:%u)", 521 idx, target, dictMode); 522 523 while(idx < target) 524 idx += ZSTD_insertBt1(ms, base+idx, iend, mls, dictMode == ZSTD_extDict); 525 ms->nextToUpdate = target; 526 } 527 528 void ZSTD_updateTree(ZSTD_matchState_t* ms, const BYTE* ip, const BYTE* iend) { 529 ZSTD_updateTree_internal(ms, ip, iend, ms->cParams.minMatch, ZSTD_noDict); 530 } 531 532 FORCE_INLINE_TEMPLATE 533 U32 ZSTD_insertBtAndGetAllMatches ( 534 ZSTD_matchState_t* ms, 535 const BYTE* const ip, const BYTE* const iLimit, const ZSTD_dictMode_e dictMode, 536 U32 rep[ZSTD_REP_NUM], 537 U32 const ll0, /* tells if associated literal length is 0 or not. This value must be 0 or 1 */ 538 ZSTD_match_t* matches, 539 const U32 lengthToBeat, 540 U32 const mls /* template */) 541 { 542 const ZSTD_compressionParameters* const cParams = &ms->cParams; 543 U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); 544 const BYTE* const base = ms->window.base; 545 U32 const current = (U32)(ip-base); 546 U32 const hashLog = cParams->hashLog; 547 U32 const minMatch = (mls==3) ? 3 : 4; 548 U32* const hashTable = ms->hashTable; 549 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 550 U32 matchIndex = hashTable[h]; 551 U32* const bt = ms->chainTable; 552 U32 const btLog = cParams->chainLog - 1; 553 U32 const btMask= (1U << btLog) - 1; 554 size_t commonLengthSmaller=0, commonLengthLarger=0; 555 const BYTE* const dictBase = ms->window.dictBase; 556 U32 const dictLimit = ms->window.dictLimit; 557 const BYTE* const dictEnd = dictBase + dictLimit; 558 const BYTE* const prefixStart = base + dictLimit; 559 U32 const btLow = btMask >= current ? 0 : current - btMask; 560 U32 const windowLow = ms->window.lowLimit; 561 U32 const matchLow = windowLow ? windowLow : 1; 562 U32* smallerPtr = bt + 2*(current&btMask); 563 U32* largerPtr = bt + 2*(current&btMask) + 1; 564 U32 matchEndIdx = current+8+1; /* farthest referenced position of any match => detects repetitive patterns */ 565 U32 dummy32; /* to be nullified at the end */ 566 U32 mnum = 0; 567 U32 nbCompares = 1U << cParams->searchLog; 568 569 const ZSTD_matchState_t* dms = dictMode == ZSTD_dictMatchState ? ms->dictMatchState : NULL; 570 const ZSTD_compressionParameters* const dmsCParams = 571 dictMode == ZSTD_dictMatchState ? &dms->cParams : NULL; 572 const BYTE* const dmsBase = dictMode == ZSTD_dictMatchState ? dms->window.base : NULL; 573 const BYTE* const dmsEnd = dictMode == ZSTD_dictMatchState ? dms->window.nextSrc : NULL; 574 U32 const dmsHighLimit = dictMode == ZSTD_dictMatchState ? (U32)(dmsEnd - dmsBase) : 0; 575 U32 const dmsLowLimit = dictMode == ZSTD_dictMatchState ? dms->window.lowLimit : 0; 576 U32 const dmsIndexDelta = dictMode == ZSTD_dictMatchState ? windowLow - dmsHighLimit : 0; 577 U32 const dmsHashLog = dictMode == ZSTD_dictMatchState ? dmsCParams->hashLog : hashLog; 578 U32 const dmsBtLog = dictMode == ZSTD_dictMatchState ? dmsCParams->chainLog - 1 : btLog; 579 U32 const dmsBtMask = dictMode == ZSTD_dictMatchState ? (1U << dmsBtLog) - 1 : 0; 580 U32 const dmsBtLow = dictMode == ZSTD_dictMatchState && dmsBtMask < dmsHighLimit - dmsLowLimit ? dmsHighLimit - dmsBtMask : dmsLowLimit; 581 582 size_t bestLength = lengthToBeat-1; 583 DEBUGLOG(8, "ZSTD_insertBtAndGetAllMatches: current=%u", current); 584 585 /* check repCode */ 586 assert(ll0 <= 1); /* necessarily 1 or 0 */ 587 { U32 const lastR = ZSTD_REP_NUM + ll0; 588 U32 repCode; 589 for (repCode = ll0; repCode < lastR; repCode++) { 590 U32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 591 U32 const repIndex = current - repOffset; 592 U32 repLen = 0; 593 assert(current >= dictLimit); 594 if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < current-dictLimit) { /* equivalent to `current > repIndex >= dictLimit` */ 595 if (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch)) { 596 repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch; 597 } 598 } else { /* repIndex < dictLimit || repIndex >= current */ 599 const BYTE* const repMatch = dictMode == ZSTD_dictMatchState ? 600 dmsBase + repIndex - dmsIndexDelta : 601 dictBase + repIndex; 602 assert(current >= windowLow); 603 if ( dictMode == ZSTD_extDict 604 && ( ((repOffset-1) /*intentional overflow*/ < current - windowLow) /* equivalent to `current > repIndex >= windowLow` */ 605 & (((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */) 606 && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { 607 repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch; 608 } 609 if (dictMode == ZSTD_dictMatchState 610 && ( ((repOffset-1) /*intentional overflow*/ < current - (dmsLowLimit + dmsIndexDelta)) /* equivalent to `current > repIndex >= dmsLowLimit` */ 611 & ((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */ 612 && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { 613 repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dmsEnd, prefixStart) + minMatch; 614 } } 615 /* save longer solution */ 616 if (repLen > bestLength) { 617 DEBUGLOG(8, "found repCode %u (ll0:%u, offset:%u) of length %u", 618 repCode, ll0, repOffset, repLen); 619 bestLength = repLen; 620 matches[mnum].off = repCode - ll0; 621 matches[mnum].len = (U32)repLen; 622 mnum++; 623 if ( (repLen > sufficient_len) 624 | (ip+repLen == iLimit) ) { /* best possible */ 625 return mnum; 626 } } } } 627 628 /* HC3 match finder */ 629 if ((mls == 3) /*static*/ && (bestLength < mls)) { 630 U32 const matchIndex3 = ZSTD_insertAndFindFirstIndexHash3(ms, ip); 631 if ((matchIndex3 >= matchLow) 632 & (current - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) { 633 size_t mlen; 634 if ((dictMode == ZSTD_noDict) /*static*/ || (dictMode == ZSTD_dictMatchState) /*static*/ || (matchIndex3 >= dictLimit)) { 635 const BYTE* const match = base + matchIndex3; 636 mlen = ZSTD_count(ip, match, iLimit); 637 } else { 638 const BYTE* const match = dictBase + matchIndex3; 639 mlen = ZSTD_count_2segments(ip, match, iLimit, dictEnd, prefixStart); 640 } 641 642 /* save best solution */ 643 if (mlen >= mls /* == 3 > bestLength */) { 644 DEBUGLOG(8, "found small match with hlog3, of length %u", 645 (U32)mlen); 646 bestLength = mlen; 647 assert(current > matchIndex3); 648 assert(mnum==0); /* no prior solution */ 649 matches[0].off = (current - matchIndex3) + ZSTD_REP_MOVE; 650 matches[0].len = (U32)mlen; 651 mnum = 1; 652 if ( (mlen > sufficient_len) | 653 (ip+mlen == iLimit) ) { /* best possible length */ 654 ms->nextToUpdate = current+1; /* skip insertion */ 655 return 1; 656 } 657 } 658 } 659 /* no dictMatchState lookup: dicts don't have a populated HC3 table */ 660 } 661 662 hashTable[h] = current; /* Update Hash Table */ 663 664 while (nbCompares-- && (matchIndex >= matchLow)) { 665 U32* const nextPtr = bt + 2*(matchIndex & btMask); 666 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 667 const BYTE* match; 668 assert(current > matchIndex); 669 670 if ((dictMode == ZSTD_noDict) || (dictMode == ZSTD_dictMatchState) || (matchIndex+matchLength >= dictLimit)) { 671 assert(matchIndex+matchLength >= dictLimit); /* ensure the condition is correct when !extDict */ 672 match = base + matchIndex; 673 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit); 674 } else { 675 match = dictBase + matchIndex; 676 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart); 677 if (matchIndex+matchLength >= dictLimit) 678 match = base + matchIndex; /* prepare for match[matchLength] */ 679 } 680 681 if (matchLength > bestLength) { 682 DEBUGLOG(8, "found match of length %u at distance %u (offCode=%u)", 683 (U32)matchLength, current - matchIndex, current - matchIndex + ZSTD_REP_MOVE); 684 assert(matchEndIdx > matchIndex); 685 if (matchLength > matchEndIdx - matchIndex) 686 matchEndIdx = matchIndex + (U32)matchLength; 687 bestLength = matchLength; 688 matches[mnum].off = (current - matchIndex) + ZSTD_REP_MOVE; 689 matches[mnum].len = (U32)matchLength; 690 mnum++; 691 if ( (matchLength > ZSTD_OPT_NUM) 692 | (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) { 693 if (dictMode == ZSTD_dictMatchState) nbCompares = 0; /* break should also skip searching dms */ 694 break; /* drop, to preserve bt consistency (miss a little bit of compression) */ 695 } 696 } 697 698 if (match[matchLength] < ip[matchLength]) { 699 /* match smaller than current */ 700 *smallerPtr = matchIndex; /* update smaller idx */ 701 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 702 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 703 smallerPtr = nextPtr+1; /* new candidate => larger than match, which was smaller than current */ 704 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous, closer to current */ 705 } else { 706 *largerPtr = matchIndex; 707 commonLengthLarger = matchLength; 708 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 709 largerPtr = nextPtr; 710 matchIndex = nextPtr[0]; 711 } } 712 713 *smallerPtr = *largerPtr = 0; 714 715 if (dictMode == ZSTD_dictMatchState && nbCompares) { 716 size_t const dmsH = ZSTD_hashPtr(ip, dmsHashLog, mls); 717 U32 dictMatchIndex = dms->hashTable[dmsH]; 718 const U32* const dmsBt = dms->chainTable; 719 commonLengthSmaller = commonLengthLarger = 0; 720 while (nbCompares-- && (dictMatchIndex > dmsLowLimit)) { 721 const U32* const nextPtr = dmsBt + 2*(dictMatchIndex & dmsBtMask); 722 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 723 const BYTE* match = dmsBase + dictMatchIndex; 724 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dmsEnd, prefixStart); 725 if (dictMatchIndex+matchLength >= dmsHighLimit) 726 match = base + dictMatchIndex + dmsIndexDelta; /* to prepare for next usage of match[matchLength] */ 727 728 if (matchLength > bestLength) { 729 matchIndex = dictMatchIndex + dmsIndexDelta; 730 DEBUGLOG(8, "found dms match of length %u at distance %u (offCode=%u)", 731 (U32)matchLength, current - matchIndex, current - matchIndex + ZSTD_REP_MOVE); 732 if (matchLength > matchEndIdx - matchIndex) 733 matchEndIdx = matchIndex + (U32)matchLength; 734 bestLength = matchLength; 735 matches[mnum].off = (current - matchIndex) + ZSTD_REP_MOVE; 736 matches[mnum].len = (U32)matchLength; 737 mnum++; 738 if ( (matchLength > ZSTD_OPT_NUM) 739 | (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) { 740 break; /* drop, to guarantee consistency (miss a little bit of compression) */ 741 } 742 } 743 744 if (dictMatchIndex <= dmsBtLow) { break; } /* beyond tree size, stop the search */ 745 if (match[matchLength] < ip[matchLength]) { 746 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 747 dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ 748 } else { 749 /* match is larger than current */ 750 commonLengthLarger = matchLength; 751 dictMatchIndex = nextPtr[0]; 752 } 753 } 754 } 755 756 assert(matchEndIdx > current+8); 757 ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ 758 return mnum; 759 } 760 761 762 FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches ( 763 ZSTD_matchState_t* ms, 764 const BYTE* ip, const BYTE* const iHighLimit, const ZSTD_dictMode_e dictMode, 765 U32 rep[ZSTD_REP_NUM], U32 const ll0, 766 ZSTD_match_t* matches, U32 const lengthToBeat) 767 { 768 const ZSTD_compressionParameters* const cParams = &ms->cParams; 769 U32 const matchLengthSearch = cParams->minMatch; 770 DEBUGLOG(8, "ZSTD_BtGetAllMatches"); 771 if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */ 772 ZSTD_updateTree_internal(ms, ip, iHighLimit, matchLengthSearch, dictMode); 773 switch(matchLengthSearch) 774 { 775 case 3 : return ZSTD_insertBtAndGetAllMatches(ms, ip, iHighLimit, dictMode, rep, ll0, matches, lengthToBeat, 3); 776 default : 777 case 4 : return ZSTD_insertBtAndGetAllMatches(ms, ip, iHighLimit, dictMode, rep, ll0, matches, lengthToBeat, 4); 778 case 5 : return ZSTD_insertBtAndGetAllMatches(ms, ip, iHighLimit, dictMode, rep, ll0, matches, lengthToBeat, 5); 779 case 7 : 780 case 6 : return ZSTD_insertBtAndGetAllMatches(ms, ip, iHighLimit, dictMode, rep, ll0, matches, lengthToBeat, 6); 781 } 782 } 783 784 785 /*-******************************* 786 * Optimal parser 787 *********************************/ 788 typedef struct repcodes_s { 789 U32 rep[3]; 790 } repcodes_t; 791 792 static repcodes_t ZSTD_updateRep(U32 const rep[3], U32 const offset, U32 const ll0) 793 { 794 repcodes_t newReps; 795 if (offset >= ZSTD_REP_NUM) { /* full offset */ 796 newReps.rep[2] = rep[1]; 797 newReps.rep[1] = rep[0]; 798 newReps.rep[0] = offset - ZSTD_REP_MOVE; 799 } else { /* repcode */ 800 U32 const repCode = offset + ll0; 801 if (repCode > 0) { /* note : if repCode==0, no change */ 802 U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 803 newReps.rep[2] = (repCode >= 2) ? rep[1] : rep[2]; 804 newReps.rep[1] = rep[0]; 805 newReps.rep[0] = currentOffset; 806 } else { /* repCode == 0 */ 807 memcpy(&newReps, rep, sizeof(newReps)); 808 } 809 } 810 return newReps; 811 } 812 813 814 static U32 ZSTD_totalLen(ZSTD_optimal_t sol) 815 { 816 return sol.litlen + sol.mlen; 817 } 818 819 #if 0 /* debug */ 820 821 static void 822 listStats(const U32* table, int lastEltID) 823 { 824 int const nbElts = lastEltID + 1; 825 int enb; 826 for (enb=0; enb < nbElts; enb++) { 827 (void)table; 828 //RAWLOG(2, "%3i:%3i, ", enb, table[enb]); 829 RAWLOG(2, "%4i,", table[enb]); 830 } 831 RAWLOG(2, " \n"); 832 } 833 834 #endif 835 836 FORCE_INLINE_TEMPLATE size_t 837 ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms, 838 seqStore_t* seqStore, 839 U32 rep[ZSTD_REP_NUM], 840 const void* src, size_t srcSize, 841 const int optLevel, 842 const ZSTD_dictMode_e dictMode) 843 { 844 optState_t* const optStatePtr = &ms->opt; 845 const BYTE* const istart = (const BYTE*)src; 846 const BYTE* ip = istart; 847 const BYTE* anchor = istart; 848 const BYTE* const iend = istart + srcSize; 849 const BYTE* const ilimit = iend - 8; 850 const BYTE* const base = ms->window.base; 851 const BYTE* const prefixStart = base + ms->window.dictLimit; 852 const ZSTD_compressionParameters* const cParams = &ms->cParams; 853 854 U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); 855 U32 const minMatch = (cParams->minMatch == 3) ? 3 : 4; 856 857 ZSTD_optimal_t* const opt = optStatePtr->priceTable; 858 ZSTD_match_t* const matches = optStatePtr->matchTable; 859 ZSTD_optimal_t lastSequence; 860 861 /* init */ 862 DEBUGLOG(5, "ZSTD_compressBlock_opt_generic: current=%u, prefix=%u, nextToUpdate=%u", 863 (U32)(ip - base), ms->window.dictLimit, ms->nextToUpdate); 864 assert(optLevel <= 2); 865 ms->nextToUpdate3 = ms->nextToUpdate; 866 ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize, optLevel); 867 ip += (ip==prefixStart); 868 869 /* Match Loop */ 870 while (ip < ilimit) { 871 U32 cur, last_pos = 0; 872 873 /* find first match */ 874 { U32 const litlen = (U32)(ip - anchor); 875 U32 const ll0 = !litlen; 876 U32 const nbMatches = ZSTD_BtGetAllMatches(ms, ip, iend, dictMode, rep, ll0, matches, minMatch); 877 if (!nbMatches) { ip++; continue; } 878 879 /* initialize opt[0] */ 880 { U32 i ; for (i=0; i<ZSTD_REP_NUM; i++) opt[0].rep[i] = rep[i]; } 881 opt[0].mlen = 0; /* means is_a_literal */ 882 opt[0].litlen = litlen; 883 opt[0].price = ZSTD_literalsContribution(anchor, litlen, optStatePtr, optLevel); 884 885 /* large match -> immediate encoding */ 886 { U32 const maxML = matches[nbMatches-1].len; 887 U32 const maxOffset = matches[nbMatches-1].off; 888 DEBUGLOG(6, "found %u matches of maxLength=%u and maxOffCode=%u at cPos=%u => start new series", 889 nbMatches, maxML, maxOffset, (U32)(ip-prefixStart)); 890 891 if (maxML > sufficient_len) { 892 lastSequence.litlen = litlen; 893 lastSequence.mlen = maxML; 894 lastSequence.off = maxOffset; 895 DEBUGLOG(6, "large match (%u>%u), immediate encoding", 896 maxML, sufficient_len); 897 cur = 0; 898 last_pos = ZSTD_totalLen(lastSequence); 899 goto _shortestPath; 900 } } 901 902 /* set prices for first matches starting position == 0 */ 903 { U32 const literalsPrice = opt[0].price + ZSTD_litLengthPrice(0, optStatePtr, optLevel); 904 U32 pos; 905 U32 matchNb; 906 for (pos = 1; pos < minMatch; pos++) { 907 opt[pos].price = ZSTD_MAX_PRICE; /* mlen, litlen and price will be fixed during forward scanning */ 908 } 909 for (matchNb = 0; matchNb < nbMatches; matchNb++) { 910 U32 const offset = matches[matchNb].off; 911 U32 const end = matches[matchNb].len; 912 repcodes_t const repHistory = ZSTD_updateRep(rep, offset, ll0); 913 for ( ; pos <= end ; pos++ ) { 914 U32 const matchPrice = ZSTD_getMatchPrice(offset, pos, optStatePtr, optLevel); 915 U32 const sequencePrice = literalsPrice + matchPrice; 916 DEBUGLOG(7, "rPos:%u => set initial price : %.2f", 917 pos, ZSTD_fCost(sequencePrice)); 918 opt[pos].mlen = pos; 919 opt[pos].off = offset; 920 opt[pos].litlen = litlen; 921 opt[pos].price = sequencePrice; 922 ZSTD_STATIC_ASSERT(sizeof(opt[pos].rep) == sizeof(repHistory)); 923 memcpy(opt[pos].rep, &repHistory, sizeof(repHistory)); 924 } } 925 last_pos = pos-1; 926 } 927 } 928 929 /* check further positions */ 930 for (cur = 1; cur <= last_pos; cur++) { 931 const BYTE* const inr = ip + cur; 932 assert(cur < ZSTD_OPT_NUM); 933 DEBUGLOG(7, "cPos:%zi==rPos:%u", inr-istart, cur) 934 935 /* Fix current position with one literal if cheaper */ 936 { U32 const litlen = (opt[cur-1].mlen == 0) ? opt[cur-1].litlen + 1 : 1; 937 int const price = opt[cur-1].price 938 + ZSTD_rawLiteralsCost(ip+cur-1, 1, optStatePtr, optLevel) 939 + ZSTD_litLengthPrice(litlen, optStatePtr, optLevel) 940 - ZSTD_litLengthPrice(litlen-1, optStatePtr, optLevel); 941 assert(price < 1000000000); /* overflow check */ 942 if (price <= opt[cur].price) { 943 DEBUGLOG(7, "cPos:%zi==rPos:%u : better price (%.2f<=%.2f) using literal (ll==%u) (hist:%u,%u,%u)", 944 inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), litlen, 945 opt[cur-1].rep[0], opt[cur-1].rep[1], opt[cur-1].rep[2]); 946 opt[cur].mlen = 0; 947 opt[cur].off = 0; 948 opt[cur].litlen = litlen; 949 opt[cur].price = price; 950 memcpy(opt[cur].rep, opt[cur-1].rep, sizeof(opt[cur].rep)); 951 } else { 952 DEBUGLOG(7, "cPos:%zi==rPos:%u : literal would cost more (%.2f>%.2f) (hist:%u,%u,%u)", 953 inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), 954 opt[cur].rep[0], opt[cur].rep[1], opt[cur].rep[2]); 955 } 956 } 957 958 /* last match must start at a minimum distance of 8 from oend */ 959 if (inr > ilimit) continue; 960 961 if (cur == last_pos) break; 962 963 if ( (optLevel==0) /*static_test*/ 964 && (opt[cur+1].price <= opt[cur].price + (BITCOST_MULTIPLIER/2)) ) { 965 DEBUGLOG(7, "move to next rPos:%u : price is <=", cur+1); 966 continue; /* skip unpromising positions; about ~+6% speed, -0.01 ratio */ 967 } 968 969 { U32 const ll0 = (opt[cur].mlen != 0); 970 U32 const litlen = (opt[cur].mlen == 0) ? opt[cur].litlen : 0; 971 U32 const previousPrice = opt[cur].price; 972 U32 const basePrice = previousPrice + ZSTD_litLengthPrice(0, optStatePtr, optLevel); 973 U32 const nbMatches = ZSTD_BtGetAllMatches(ms, inr, iend, dictMode, opt[cur].rep, ll0, matches, minMatch); 974 U32 matchNb; 975 if (!nbMatches) { 976 DEBUGLOG(7, "rPos:%u : no match found", cur); 977 continue; 978 } 979 980 { U32 const maxML = matches[nbMatches-1].len; 981 DEBUGLOG(7, "cPos:%zi==rPos:%u, found %u matches, of maxLength=%u", 982 inr-istart, cur, nbMatches, maxML); 983 984 if ( (maxML > sufficient_len) 985 || (cur + maxML >= ZSTD_OPT_NUM) ) { 986 lastSequence.mlen = maxML; 987 lastSequence.off = matches[nbMatches-1].off; 988 lastSequence.litlen = litlen; 989 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 */ 990 last_pos = cur + ZSTD_totalLen(lastSequence); 991 if (cur > ZSTD_OPT_NUM) cur = 0; /* underflow => first match */ 992 goto _shortestPath; 993 } } 994 995 /* set prices using matches found at position == cur */ 996 for (matchNb = 0; matchNb < nbMatches; matchNb++) { 997 U32 const offset = matches[matchNb].off; 998 repcodes_t const repHistory = ZSTD_updateRep(opt[cur].rep, offset, ll0); 999 U32 const lastML = matches[matchNb].len; 1000 U32 const startML = (matchNb>0) ? matches[matchNb-1].len+1 : minMatch; 1001 U32 mlen; 1002 1003 DEBUGLOG(7, "testing match %u => offCode=%4u, mlen=%2u, llen=%2u", 1004 matchNb, matches[matchNb].off, lastML, litlen); 1005 1006 for (mlen = lastML; mlen >= startML; mlen--) { /* scan downward */ 1007 U32 const pos = cur + mlen; 1008 int const price = basePrice + ZSTD_getMatchPrice(offset, mlen, optStatePtr, optLevel); 1009 1010 if ((pos > last_pos) || (price < opt[pos].price)) { 1011 DEBUGLOG(7, "rPos:%u (ml=%2u) => new better price (%.2f<%.2f)", 1012 pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price)); 1013 while (last_pos < pos) { opt[last_pos+1].price = ZSTD_MAX_PRICE; last_pos++; } /* fill empty positions */ 1014 opt[pos].mlen = mlen; 1015 opt[pos].off = offset; 1016 opt[pos].litlen = litlen; 1017 opt[pos].price = price; 1018 ZSTD_STATIC_ASSERT(sizeof(opt[pos].rep) == sizeof(repHistory)); 1019 memcpy(opt[pos].rep, &repHistory, sizeof(repHistory)); 1020 } else { 1021 DEBUGLOG(7, "rPos:%u (ml=%2u) => new price is worse (%.2f>=%.2f)", 1022 pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price)); 1023 if (optLevel==0) break; /* early update abort; gets ~+10% speed for about -0.01 ratio loss */ 1024 } 1025 } } } 1026 } /* for (cur = 1; cur <= last_pos; cur++) */ 1027 1028 lastSequence = opt[last_pos]; 1029 cur = last_pos > ZSTD_totalLen(lastSequence) ? last_pos - ZSTD_totalLen(lastSequence) : 0; /* single sequence, and it starts before `ip` */ 1030 assert(cur < ZSTD_OPT_NUM); /* control overflow*/ 1031 1032 _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */ 1033 assert(opt[0].mlen == 0); 1034 1035 { U32 const storeEnd = cur + 1; 1036 U32 storeStart = storeEnd; 1037 U32 seqPos = cur; 1038 1039 DEBUGLOG(6, "start reverse traversal (last_pos:%u, cur:%u)", 1040 last_pos, cur); (void)last_pos; 1041 assert(storeEnd < ZSTD_OPT_NUM); 1042 DEBUGLOG(6, "last sequence copied into pos=%u (llen=%u,mlen=%u,ofc=%u)", 1043 storeEnd, lastSequence.litlen, lastSequence.mlen, lastSequence.off); 1044 opt[storeEnd] = lastSequence; 1045 while (seqPos > 0) { 1046 U32 const backDist = ZSTD_totalLen(opt[seqPos]); 1047 storeStart--; 1048 DEBUGLOG(6, "sequence from rPos=%u copied into pos=%u (llen=%u,mlen=%u,ofc=%u)", 1049 seqPos, storeStart, opt[seqPos].litlen, opt[seqPos].mlen, opt[seqPos].off); 1050 opt[storeStart] = opt[seqPos]; 1051 seqPos = (seqPos > backDist) ? seqPos - backDist : 0; 1052 } 1053 1054 /* save sequences */ 1055 DEBUGLOG(6, "sending selected sequences into seqStore") 1056 { U32 storePos; 1057 for (storePos=storeStart; storePos <= storeEnd; storePos++) { 1058 U32 const llen = opt[storePos].litlen; 1059 U32 const mlen = opt[storePos].mlen; 1060 U32 const offCode = opt[storePos].off; 1061 U32 const advance = llen + mlen; 1062 DEBUGLOG(6, "considering seq starting at %zi, llen=%u, mlen=%u", 1063 anchor - istart, (unsigned)llen, (unsigned)mlen); 1064 1065 if (mlen==0) { /* only literals => must be last "sequence", actually starting a new stream of sequences */ 1066 assert(storePos == storeEnd); /* must be last sequence */ 1067 ip = anchor + llen; /* last "sequence" is a bunch of literals => don't progress anchor */ 1068 continue; /* will finish */ 1069 } 1070 1071 /* repcodes update : like ZSTD_updateRep(), but update in place */ 1072 if (offCode >= ZSTD_REP_NUM) { /* full offset */ 1073 rep[2] = rep[1]; 1074 rep[1] = rep[0]; 1075 rep[0] = offCode - ZSTD_REP_MOVE; 1076 } else { /* repcode */ 1077 U32 const repCode = offCode + (llen==0); 1078 if (repCode) { /* note : if repCode==0, no change */ 1079 U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 1080 if (repCode >= 2) rep[2] = rep[1]; 1081 rep[1] = rep[0]; 1082 rep[0] = currentOffset; 1083 } } 1084 1085 assert(anchor + llen <= iend); 1086 ZSTD_updateStats(optStatePtr, llen, anchor, offCode, mlen); 1087 ZSTD_storeSeq(seqStore, llen, anchor, offCode, mlen-MINMATCH); 1088 anchor += advance; 1089 ip = anchor; 1090 } } 1091 ZSTD_setBasePrices(optStatePtr, optLevel); 1092 } 1093 1094 } /* while (ip < ilimit) */ 1095 1096 /* Return the last literals size */ 1097 return iend - anchor; 1098 } 1099 1100 1101 size_t ZSTD_compressBlock_btopt( 1102 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1103 const void* src, size_t srcSize) 1104 { 1105 DEBUGLOG(5, "ZSTD_compressBlock_btopt"); 1106 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_noDict); 1107 } 1108 1109 1110 /* used in 2-pass strategy */ 1111 static U32 ZSTD_upscaleStat(unsigned* table, U32 lastEltIndex, int bonus) 1112 { 1113 U32 s, sum=0; 1114 assert(ZSTD_FREQ_DIV+bonus >= 0); 1115 for (s=0; s<lastEltIndex+1; s++) { 1116 table[s] <<= ZSTD_FREQ_DIV+bonus; 1117 table[s]--; 1118 sum += table[s]; 1119 } 1120 return sum; 1121 } 1122 1123 /* used in 2-pass strategy */ 1124 MEM_STATIC void ZSTD_upscaleStats(optState_t* optPtr) 1125 { 1126 if (ZSTD_compressedLiterals(optPtr)) 1127 optPtr->litSum = ZSTD_upscaleStat(optPtr->litFreq, MaxLit, 0); 1128 optPtr->litLengthSum = ZSTD_upscaleStat(optPtr->litLengthFreq, MaxLL, 0); 1129 optPtr->matchLengthSum = ZSTD_upscaleStat(optPtr->matchLengthFreq, MaxML, 0); 1130 optPtr->offCodeSum = ZSTD_upscaleStat(optPtr->offCodeFreq, MaxOff, 0); 1131 } 1132 1133 /* ZSTD_initStats_ultra(): 1134 * make a first compression pass, just to seed stats with more accurate starting values. 1135 * only works on first block, with no dictionary and no ldm. 1136 * this function cannot error, hence its contract must be respected. 1137 */ 1138 static void 1139 ZSTD_initStats_ultra(ZSTD_matchState_t* ms, 1140 seqStore_t* seqStore, 1141 U32 rep[ZSTD_REP_NUM], 1142 const void* src, size_t srcSize) 1143 { 1144 U32 tmpRep[ZSTD_REP_NUM]; /* updated rep codes will sink here */ 1145 memcpy(tmpRep, rep, sizeof(tmpRep)); 1146 1147 DEBUGLOG(4, "ZSTD_initStats_ultra (srcSize=%zu)", srcSize); 1148 assert(ms->opt.litLengthSum == 0); /* first block */ 1149 assert(seqStore->sequences == seqStore->sequencesStart); /* no ldm */ 1150 assert(ms->window.dictLimit == ms->window.lowLimit); /* no dictionary */ 1151 assert(ms->window.dictLimit - ms->nextToUpdate <= 1); /* no prefix (note: intentional overflow, defined as 2-complement) */ 1152 1153 ZSTD_compressBlock_opt_generic(ms, seqStore, tmpRep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); /* generate stats into ms->opt*/ 1154 1155 /* invalidate first scan from history */ 1156 ZSTD_resetSeqStore(seqStore); 1157 ms->window.base -= srcSize; 1158 ms->window.dictLimit += (U32)srcSize; 1159 ms->window.lowLimit = ms->window.dictLimit; 1160 ms->nextToUpdate = ms->window.dictLimit; 1161 ms->nextToUpdate3 = ms->window.dictLimit; 1162 1163 /* re-inforce weight of collected statistics */ 1164 ZSTD_upscaleStats(&ms->opt); 1165 } 1166 1167 size_t ZSTD_compressBlock_btultra( 1168 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1169 const void* src, size_t srcSize) 1170 { 1171 DEBUGLOG(5, "ZSTD_compressBlock_btultra (srcSize=%zu)", srcSize); 1172 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); 1173 } 1174 1175 size_t ZSTD_compressBlock_btultra2( 1176 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1177 const void* src, size_t srcSize) 1178 { 1179 U32 const current = (U32)((const BYTE*)src - ms->window.base); 1180 DEBUGLOG(5, "ZSTD_compressBlock_btultra2 (srcSize=%zu)", srcSize); 1181 1182 /* 2-pass strategy: 1183 * this strategy makes a first pass over first block to collect statistics 1184 * and seed next round's statistics with it. 1185 * After 1st pass, function forgets everything, and starts a new block. 1186 * Consequently, this can only work if no data has been previously loaded in tables, 1187 * aka, no dictionary, no prefix, no ldm preprocessing. 1188 * The compression ratio gain is generally small (~0.5% on first block), 1189 * the cost is 2x cpu time on first block. */ 1190 assert(srcSize <= ZSTD_BLOCKSIZE_MAX); 1191 if ( (ms->opt.litLengthSum==0) /* first block */ 1192 && (seqStore->sequences == seqStore->sequencesStart) /* no ldm */ 1193 && (ms->window.dictLimit == ms->window.lowLimit) /* no dictionary */ 1194 && (current == ms->window.dictLimit) /* start of frame, nothing already loaded nor skipped */ 1195 && (srcSize > ZSTD_PREDEF_THRESHOLD) 1196 ) { 1197 ZSTD_initStats_ultra(ms, seqStore, rep, src, srcSize); 1198 } 1199 1200 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); 1201 } 1202 1203 size_t ZSTD_compressBlock_btopt_dictMatchState( 1204 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1205 const void* src, size_t srcSize) 1206 { 1207 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_dictMatchState); 1208 } 1209 1210 size_t ZSTD_compressBlock_btultra_dictMatchState( 1211 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1212 const void* src, size_t srcSize) 1213 { 1214 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_dictMatchState); 1215 } 1216 1217 size_t ZSTD_compressBlock_btopt_extDict( 1218 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1219 const void* src, size_t srcSize) 1220 { 1221 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_extDict); 1222 } 1223 1224 size_t ZSTD_compressBlock_btultra_extDict( 1225 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1226 const void* src, size_t srcSize) 1227 { 1228 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_extDict); 1229 } 1230 1231 /* note : no btultra2 variant for extDict nor dictMatchState, 1232 * because btultra2 is not meant to work with dictionaries 1233 * and is only specific for the first block (no prefix) */ 1234