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 (int)WEIGHT(litLength, optLevel); 259 260 /* dynamic statistics */ 261 { U32 const llCode = ZSTD_LLcode(litLength); 262 int const contribution = (int)(LL_bits[llCode] * BITCOST_MULTIPLIER) 263 + (int)WEIGHT(optPtr->litLengthFreq[0], optLevel) /* note: log2litLengthSum cancel out */ 264 - (int)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 = (int)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, 376 U32* nextToUpdate3, 377 const BYTE* const ip) 378 { 379 U32* const hashTable3 = ms->hashTable3; 380 U32 const hashLog3 = ms->hashLog3; 381 const BYTE* const base = ms->window.base; 382 U32 idx = *nextToUpdate3; 383 U32 const target = (U32)(ip - base); 384 size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3); 385 assert(hashLog3 > 0); 386 387 while(idx < target) { 388 hashTable3[ZSTD_hash3Ptr(base+idx, hashLog3)] = idx; 389 idx++; 390 } 391 392 *nextToUpdate3 = target; 393 return hashTable3[hash3]; 394 } 395 396 397 /*-************************************* 398 * Binary Tree search 399 ***************************************/ 400 /** ZSTD_insertBt1() : add one or multiple positions to tree. 401 * ip : assumed <= iend-8 . 402 * @return : nb of positions added */ 403 static U32 ZSTD_insertBt1( 404 ZSTD_matchState_t* ms, 405 const BYTE* const ip, const BYTE* const iend, 406 U32 const mls, const int extDict) 407 { 408 const ZSTD_compressionParameters* const cParams = &ms->cParams; 409 U32* const hashTable = ms->hashTable; 410 U32 const hashLog = cParams->hashLog; 411 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 412 U32* const bt = ms->chainTable; 413 U32 const btLog = cParams->chainLog - 1; 414 U32 const btMask = (1 << btLog) - 1; 415 U32 matchIndex = hashTable[h]; 416 size_t commonLengthSmaller=0, commonLengthLarger=0; 417 const BYTE* const base = ms->window.base; 418 const BYTE* const dictBase = ms->window.dictBase; 419 const U32 dictLimit = ms->window.dictLimit; 420 const BYTE* const dictEnd = dictBase + dictLimit; 421 const BYTE* const prefixStart = base + dictLimit; 422 const BYTE* match; 423 const U32 current = (U32)(ip-base); 424 const U32 btLow = btMask >= current ? 0 : current - btMask; 425 U32* smallerPtr = bt + 2*(current&btMask); 426 U32* largerPtr = smallerPtr + 1; 427 U32 dummy32; /* to be nullified at the end */ 428 U32 const windowLow = ms->window.lowLimit; 429 U32 matchEndIdx = current+8+1; 430 size_t bestLength = 8; 431 U32 nbCompares = 1U << cParams->searchLog; 432 #ifdef ZSTD_C_PREDICT 433 U32 predictedSmall = *(bt + 2*((current-1)&btMask) + 0); 434 U32 predictedLarge = *(bt + 2*((current-1)&btMask) + 1); 435 predictedSmall += (predictedSmall>0); 436 predictedLarge += (predictedLarge>0); 437 #endif /* ZSTD_C_PREDICT */ 438 439 DEBUGLOG(8, "ZSTD_insertBt1 (%u)", current); 440 441 assert(ip <= iend-8); /* required for h calculation */ 442 hashTable[h] = current; /* Update Hash Table */ 443 444 assert(windowLow > 0); 445 while (nbCompares-- && (matchIndex >= windowLow)) { 446 U32* const nextPtr = bt + 2*(matchIndex & btMask); 447 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 448 assert(matchIndex < current); 449 450 #ifdef ZSTD_C_PREDICT /* note : can create issues when hlog small <= 11 */ 451 const U32* predictPtr = bt + 2*((matchIndex-1) & btMask); /* written this way, as bt is a roll buffer */ 452 if (matchIndex == predictedSmall) { 453 /* no need to check length, result known */ 454 *smallerPtr = matchIndex; 455 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 456 smallerPtr = nextPtr+1; /* new "smaller" => larger of match */ 457 matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ 458 predictedSmall = predictPtr[1] + (predictPtr[1]>0); 459 continue; 460 } 461 if (matchIndex == predictedLarge) { 462 *largerPtr = matchIndex; 463 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 464 largerPtr = nextPtr; 465 matchIndex = nextPtr[0]; 466 predictedLarge = predictPtr[0] + (predictPtr[0]>0); 467 continue; 468 } 469 #endif 470 471 if (!extDict || (matchIndex+matchLength >= dictLimit)) { 472 assert(matchIndex+matchLength >= dictLimit); /* might be wrong if actually extDict */ 473 match = base + matchIndex; 474 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); 475 } else { 476 match = dictBase + matchIndex; 477 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); 478 if (matchIndex+matchLength >= dictLimit) 479 match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ 480 } 481 482 if (matchLength > bestLength) { 483 bestLength = matchLength; 484 if (matchLength > matchEndIdx - matchIndex) 485 matchEndIdx = matchIndex + (U32)matchLength; 486 } 487 488 if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ 489 break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */ 490 } 491 492 if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */ 493 /* match is smaller than current */ 494 *smallerPtr = matchIndex; /* update smaller idx */ 495 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 496 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */ 497 smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */ 498 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */ 499 } else { 500 /* match is larger than current */ 501 *largerPtr = matchIndex; 502 commonLengthLarger = matchLength; 503 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */ 504 largerPtr = nextPtr; 505 matchIndex = nextPtr[0]; 506 } } 507 508 *smallerPtr = *largerPtr = 0; 509 { U32 positions = 0; 510 if (bestLength > 384) positions = MIN(192, (U32)(bestLength - 384)); /* speed optimization */ 511 assert(matchEndIdx > current + 8); 512 return MAX(positions, matchEndIdx - (current + 8)); 513 } 514 } 515 516 FORCE_INLINE_TEMPLATE 517 void ZSTD_updateTree_internal( 518 ZSTD_matchState_t* ms, 519 const BYTE* const ip, const BYTE* const iend, 520 const U32 mls, const ZSTD_dictMode_e dictMode) 521 { 522 const BYTE* const base = ms->window.base; 523 U32 const target = (U32)(ip - base); 524 U32 idx = ms->nextToUpdate; 525 DEBUGLOG(6, "ZSTD_updateTree_internal, from %u to %u (dictMode:%u)", 526 idx, target, dictMode); 527 528 while(idx < target) { 529 U32 const forward = ZSTD_insertBt1(ms, base+idx, iend, mls, dictMode == ZSTD_extDict); 530 assert(idx < (U32)(idx + forward)); 531 idx += forward; 532 } 533 assert((size_t)(ip - base) <= (size_t)(U32)(-1)); 534 assert((size_t)(iend - base) <= (size_t)(U32)(-1)); 535 ms->nextToUpdate = target; 536 } 537 538 void ZSTD_updateTree(ZSTD_matchState_t* ms, const BYTE* ip, const BYTE* iend) { 539 ZSTD_updateTree_internal(ms, ip, iend, ms->cParams.minMatch, ZSTD_noDict); 540 } 541 542 FORCE_INLINE_TEMPLATE 543 U32 ZSTD_insertBtAndGetAllMatches ( 544 ZSTD_match_t* matches, /* store result (found matches) in this table (presumed large enough) */ 545 ZSTD_matchState_t* ms, 546 U32* nextToUpdate3, 547 const BYTE* const ip, const BYTE* const iLimit, const ZSTD_dictMode_e dictMode, 548 const U32 rep[ZSTD_REP_NUM], 549 U32 const ll0, /* tells if associated literal length is 0 or not. This value must be 0 or 1 */ 550 const U32 lengthToBeat, 551 U32 const mls /* template */) 552 { 553 const ZSTD_compressionParameters* const cParams = &ms->cParams; 554 U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); 555 const BYTE* const base = ms->window.base; 556 U32 const current = (U32)(ip-base); 557 U32 const hashLog = cParams->hashLog; 558 U32 const minMatch = (mls==3) ? 3 : 4; 559 U32* const hashTable = ms->hashTable; 560 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 561 U32 matchIndex = hashTable[h]; 562 U32* const bt = ms->chainTable; 563 U32 const btLog = cParams->chainLog - 1; 564 U32 const btMask= (1U << btLog) - 1; 565 size_t commonLengthSmaller=0, commonLengthLarger=0; 566 const BYTE* const dictBase = ms->window.dictBase; 567 U32 const dictLimit = ms->window.dictLimit; 568 const BYTE* const dictEnd = dictBase + dictLimit; 569 const BYTE* const prefixStart = base + dictLimit; 570 U32 const btLow = (btMask >= current) ? 0 : current - btMask; 571 U32 const windowLow = ZSTD_getLowestMatchIndex(ms, current, cParams->windowLog); 572 U32 const matchLow = windowLow ? windowLow : 1; 573 U32* smallerPtr = bt + 2*(current&btMask); 574 U32* largerPtr = bt + 2*(current&btMask) + 1; 575 U32 matchEndIdx = current+8+1; /* farthest referenced position of any match => detects repetitive patterns */ 576 U32 dummy32; /* to be nullified at the end */ 577 U32 mnum = 0; 578 U32 nbCompares = 1U << cParams->searchLog; 579 580 const ZSTD_matchState_t* dms = dictMode == ZSTD_dictMatchState ? ms->dictMatchState : NULL; 581 const ZSTD_compressionParameters* const dmsCParams = 582 dictMode == ZSTD_dictMatchState ? &dms->cParams : NULL; 583 const BYTE* const dmsBase = dictMode == ZSTD_dictMatchState ? dms->window.base : NULL; 584 const BYTE* const dmsEnd = dictMode == ZSTD_dictMatchState ? dms->window.nextSrc : NULL; 585 U32 const dmsHighLimit = dictMode == ZSTD_dictMatchState ? (U32)(dmsEnd - dmsBase) : 0; 586 U32 const dmsLowLimit = dictMode == ZSTD_dictMatchState ? dms->window.lowLimit : 0; 587 U32 const dmsIndexDelta = dictMode == ZSTD_dictMatchState ? windowLow - dmsHighLimit : 0; 588 U32 const dmsHashLog = dictMode == ZSTD_dictMatchState ? dmsCParams->hashLog : hashLog; 589 U32 const dmsBtLog = dictMode == ZSTD_dictMatchState ? dmsCParams->chainLog - 1 : btLog; 590 U32 const dmsBtMask = dictMode == ZSTD_dictMatchState ? (1U << dmsBtLog) - 1 : 0; 591 U32 const dmsBtLow = dictMode == ZSTD_dictMatchState && dmsBtMask < dmsHighLimit - dmsLowLimit ? dmsHighLimit - dmsBtMask : dmsLowLimit; 592 593 size_t bestLength = lengthToBeat-1; 594 DEBUGLOG(8, "ZSTD_insertBtAndGetAllMatches: current=%u", current); 595 596 /* check repCode */ 597 assert(ll0 <= 1); /* necessarily 1 or 0 */ 598 { U32 const lastR = ZSTD_REP_NUM + ll0; 599 U32 repCode; 600 for (repCode = ll0; repCode < lastR; repCode++) { 601 U32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 602 U32 const repIndex = current - repOffset; 603 U32 repLen = 0; 604 assert(current >= dictLimit); 605 if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < current-dictLimit) { /* equivalent to `current > repIndex >= dictLimit` */ 606 if (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch)) { 607 repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch; 608 } 609 } else { /* repIndex < dictLimit || repIndex >= current */ 610 const BYTE* const repMatch = dictMode == ZSTD_dictMatchState ? 611 dmsBase + repIndex - dmsIndexDelta : 612 dictBase + repIndex; 613 assert(current >= windowLow); 614 if ( dictMode == ZSTD_extDict 615 && ( ((repOffset-1) /*intentional overflow*/ < current - windowLow) /* equivalent to `current > repIndex >= windowLow` */ 616 & (((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */) 617 && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { 618 repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch; 619 } 620 if (dictMode == ZSTD_dictMatchState 621 && ( ((repOffset-1) /*intentional overflow*/ < current - (dmsLowLimit + dmsIndexDelta)) /* equivalent to `current > repIndex >= dmsLowLimit` */ 622 & ((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */ 623 && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { 624 repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dmsEnd, prefixStart) + minMatch; 625 } } 626 /* save longer solution */ 627 if (repLen > bestLength) { 628 DEBUGLOG(8, "found repCode %u (ll0:%u, offset:%u) of length %u", 629 repCode, ll0, repOffset, repLen); 630 bestLength = repLen; 631 matches[mnum].off = repCode - ll0; 632 matches[mnum].len = (U32)repLen; 633 mnum++; 634 if ( (repLen > sufficient_len) 635 | (ip+repLen == iLimit) ) { /* best possible */ 636 return mnum; 637 } } } } 638 639 /* HC3 match finder */ 640 if ((mls == 3) /*static*/ && (bestLength < mls)) { 641 U32 const matchIndex3 = ZSTD_insertAndFindFirstIndexHash3(ms, nextToUpdate3, ip); 642 if ((matchIndex3 >= matchLow) 643 & (current - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) { 644 size_t mlen; 645 if ((dictMode == ZSTD_noDict) /*static*/ || (dictMode == ZSTD_dictMatchState) /*static*/ || (matchIndex3 >= dictLimit)) { 646 const BYTE* const match = base + matchIndex3; 647 mlen = ZSTD_count(ip, match, iLimit); 648 } else { 649 const BYTE* const match = dictBase + matchIndex3; 650 mlen = ZSTD_count_2segments(ip, match, iLimit, dictEnd, prefixStart); 651 } 652 653 /* save best solution */ 654 if (mlen >= mls /* == 3 > bestLength */) { 655 DEBUGLOG(8, "found small match with hlog3, of length %u", 656 (U32)mlen); 657 bestLength = mlen; 658 assert(current > matchIndex3); 659 assert(mnum==0); /* no prior solution */ 660 matches[0].off = (current - matchIndex3) + ZSTD_REP_MOVE; 661 matches[0].len = (U32)mlen; 662 mnum = 1; 663 if ( (mlen > sufficient_len) | 664 (ip+mlen == iLimit) ) { /* best possible length */ 665 ms->nextToUpdate = current+1; /* skip insertion */ 666 return 1; 667 } } } 668 /* no dictMatchState lookup: dicts don't have a populated HC3 table */ 669 } 670 671 hashTable[h] = current; /* Update Hash Table */ 672 673 while (nbCompares-- && (matchIndex >= matchLow)) { 674 U32* const nextPtr = bt + 2*(matchIndex & btMask); 675 const BYTE* match; 676 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 677 assert(current > matchIndex); 678 679 if ((dictMode == ZSTD_noDict) || (dictMode == ZSTD_dictMatchState) || (matchIndex+matchLength >= dictLimit)) { 680 assert(matchIndex+matchLength >= dictLimit); /* ensure the condition is correct when !extDict */ 681 match = base + matchIndex; 682 if (matchIndex >= dictLimit) assert(memcmp(match, ip, matchLength) == 0); /* ensure early section of match is equal as expected */ 683 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit); 684 } else { 685 match = dictBase + matchIndex; 686 assert(memcmp(match, ip, matchLength) == 0); /* ensure early section of match is equal as expected */ 687 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart); 688 if (matchIndex+matchLength >= dictLimit) 689 match = base + matchIndex; /* prepare for match[matchLength] read */ 690 } 691 692 if (matchLength > bestLength) { 693 DEBUGLOG(8, "found match of length %u at distance %u (offCode=%u)", 694 (U32)matchLength, current - matchIndex, current - matchIndex + ZSTD_REP_MOVE); 695 assert(matchEndIdx > matchIndex); 696 if (matchLength > matchEndIdx - matchIndex) 697 matchEndIdx = matchIndex + (U32)matchLength; 698 bestLength = matchLength; 699 matches[mnum].off = (current - matchIndex) + ZSTD_REP_MOVE; 700 matches[mnum].len = (U32)matchLength; 701 mnum++; 702 if ( (matchLength > ZSTD_OPT_NUM) 703 | (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) { 704 if (dictMode == ZSTD_dictMatchState) nbCompares = 0; /* break should also skip searching dms */ 705 break; /* drop, to preserve bt consistency (miss a little bit of compression) */ 706 } 707 } 708 709 if (match[matchLength] < ip[matchLength]) { 710 /* match smaller than current */ 711 *smallerPtr = matchIndex; /* update smaller idx */ 712 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 713 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 714 smallerPtr = nextPtr+1; /* new candidate => larger than match, which was smaller than current */ 715 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous, closer to current */ 716 } else { 717 *largerPtr = matchIndex; 718 commonLengthLarger = matchLength; 719 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 720 largerPtr = nextPtr; 721 matchIndex = nextPtr[0]; 722 } } 723 724 *smallerPtr = *largerPtr = 0; 725 726 if (dictMode == ZSTD_dictMatchState && nbCompares) { 727 size_t const dmsH = ZSTD_hashPtr(ip, dmsHashLog, mls); 728 U32 dictMatchIndex = dms->hashTable[dmsH]; 729 const U32* const dmsBt = dms->chainTable; 730 commonLengthSmaller = commonLengthLarger = 0; 731 while (nbCompares-- && (dictMatchIndex > dmsLowLimit)) { 732 const U32* const nextPtr = dmsBt + 2*(dictMatchIndex & dmsBtMask); 733 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 734 const BYTE* match = dmsBase + dictMatchIndex; 735 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dmsEnd, prefixStart); 736 if (dictMatchIndex+matchLength >= dmsHighLimit) 737 match = base + dictMatchIndex + dmsIndexDelta; /* to prepare for next usage of match[matchLength] */ 738 739 if (matchLength > bestLength) { 740 matchIndex = dictMatchIndex + dmsIndexDelta; 741 DEBUGLOG(8, "found dms match of length %u at distance %u (offCode=%u)", 742 (U32)matchLength, current - matchIndex, current - matchIndex + ZSTD_REP_MOVE); 743 if (matchLength > matchEndIdx - matchIndex) 744 matchEndIdx = matchIndex + (U32)matchLength; 745 bestLength = matchLength; 746 matches[mnum].off = (current - matchIndex) + ZSTD_REP_MOVE; 747 matches[mnum].len = (U32)matchLength; 748 mnum++; 749 if ( (matchLength > ZSTD_OPT_NUM) 750 | (ip+matchLength == iLimit) /* equal : no way to know if inf or sup */) { 751 break; /* drop, to guarantee consistency (miss a little bit of compression) */ 752 } 753 } 754 755 if (dictMatchIndex <= dmsBtLow) { break; } /* beyond tree size, stop the search */ 756 if (match[matchLength] < ip[matchLength]) { 757 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 758 dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ 759 } else { 760 /* match is larger than current */ 761 commonLengthLarger = matchLength; 762 dictMatchIndex = nextPtr[0]; 763 } 764 } 765 } 766 767 assert(matchEndIdx > current+8); 768 ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ 769 return mnum; 770 } 771 772 773 FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches ( 774 ZSTD_match_t* matches, /* store result (match found, increasing size) in this table */ 775 ZSTD_matchState_t* ms, 776 U32* nextToUpdate3, 777 const BYTE* ip, const BYTE* const iHighLimit, const ZSTD_dictMode_e dictMode, 778 const U32 rep[ZSTD_REP_NUM], 779 U32 const ll0, 780 U32 const lengthToBeat) 781 { 782 const ZSTD_compressionParameters* const cParams = &ms->cParams; 783 U32 const matchLengthSearch = cParams->minMatch; 784 DEBUGLOG(8, "ZSTD_BtGetAllMatches"); 785 if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */ 786 ZSTD_updateTree_internal(ms, ip, iHighLimit, matchLengthSearch, dictMode); 787 switch(matchLengthSearch) 788 { 789 case 3 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 3); 790 default : 791 case 4 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 4); 792 case 5 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 5); 793 case 7 : 794 case 6 : return ZSTD_insertBtAndGetAllMatches(matches, ms, nextToUpdate3, ip, iHighLimit, dictMode, rep, ll0, lengthToBeat, 6); 795 } 796 } 797 798 799 /*-******************************* 800 * Optimal parser 801 *********************************/ 802 typedef struct repcodes_s { 803 U32 rep[3]; 804 } repcodes_t; 805 806 static repcodes_t ZSTD_updateRep(U32 const rep[3], U32 const offset, U32 const ll0) 807 { 808 repcodes_t newReps; 809 if (offset >= ZSTD_REP_NUM) { /* full offset */ 810 newReps.rep[2] = rep[1]; 811 newReps.rep[1] = rep[0]; 812 newReps.rep[0] = offset - ZSTD_REP_MOVE; 813 } else { /* repcode */ 814 U32 const repCode = offset + ll0; 815 if (repCode > 0) { /* note : if repCode==0, no change */ 816 U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 817 newReps.rep[2] = (repCode >= 2) ? rep[1] : rep[2]; 818 newReps.rep[1] = rep[0]; 819 newReps.rep[0] = currentOffset; 820 } else { /* repCode == 0 */ 821 memcpy(&newReps, rep, sizeof(newReps)); 822 } 823 } 824 return newReps; 825 } 826 827 828 static U32 ZSTD_totalLen(ZSTD_optimal_t sol) 829 { 830 return sol.litlen + sol.mlen; 831 } 832 833 #if 0 /* debug */ 834 835 static void 836 listStats(const U32* table, int lastEltID) 837 { 838 int const nbElts = lastEltID + 1; 839 int enb; 840 for (enb=0; enb < nbElts; enb++) { 841 (void)table; 842 //RAWLOG(2, "%3i:%3i, ", enb, table[enb]); 843 RAWLOG(2, "%4i,", table[enb]); 844 } 845 RAWLOG(2, " \n"); 846 } 847 848 #endif 849 850 FORCE_INLINE_TEMPLATE size_t 851 ZSTD_compressBlock_opt_generic(ZSTD_matchState_t* ms, 852 seqStore_t* seqStore, 853 U32 rep[ZSTD_REP_NUM], 854 const void* src, size_t srcSize, 855 const int optLevel, 856 const ZSTD_dictMode_e dictMode) 857 { 858 optState_t* const optStatePtr = &ms->opt; 859 const BYTE* const istart = (const BYTE*)src; 860 const BYTE* ip = istart; 861 const BYTE* anchor = istart; 862 const BYTE* const iend = istart + srcSize; 863 const BYTE* const ilimit = iend - 8; 864 const BYTE* const base = ms->window.base; 865 const BYTE* const prefixStart = base + ms->window.dictLimit; 866 const ZSTD_compressionParameters* const cParams = &ms->cParams; 867 868 U32 const sufficient_len = MIN(cParams->targetLength, ZSTD_OPT_NUM -1); 869 U32 const minMatch = (cParams->minMatch == 3) ? 3 : 4; 870 U32 nextToUpdate3 = ms->nextToUpdate; 871 872 ZSTD_optimal_t* const opt = optStatePtr->priceTable; 873 ZSTD_match_t* const matches = optStatePtr->matchTable; 874 ZSTD_optimal_t lastSequence; 875 876 /* init */ 877 DEBUGLOG(5, "ZSTD_compressBlock_opt_generic: current=%u, prefix=%u, nextToUpdate=%u", 878 (U32)(ip - base), ms->window.dictLimit, ms->nextToUpdate); 879 assert(optLevel <= 2); 880 ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize, optLevel); 881 ip += (ip==prefixStart); 882 883 /* Match Loop */ 884 while (ip < ilimit) { 885 U32 cur, last_pos = 0; 886 887 /* find first match */ 888 { U32 const litlen = (U32)(ip - anchor); 889 U32 const ll0 = !litlen; 890 U32 const nbMatches = ZSTD_BtGetAllMatches(matches, ms, &nextToUpdate3, ip, iend, dictMode, rep, ll0, minMatch); 891 if (!nbMatches) { ip++; continue; } 892 893 /* initialize opt[0] */ 894 { U32 i ; for (i=0; i<ZSTD_REP_NUM; i++) opt[0].rep[i] = rep[i]; } 895 opt[0].mlen = 0; /* means is_a_literal */ 896 opt[0].litlen = litlen; 897 opt[0].price = ZSTD_literalsContribution(anchor, litlen, optStatePtr, optLevel); 898 899 /* large match -> immediate encoding */ 900 { U32 const maxML = matches[nbMatches-1].len; 901 U32 const maxOffset = matches[nbMatches-1].off; 902 DEBUGLOG(6, "found %u matches of maxLength=%u and maxOffCode=%u at cPos=%u => start new series", 903 nbMatches, maxML, maxOffset, (U32)(ip-prefixStart)); 904 905 if (maxML > sufficient_len) { 906 lastSequence.litlen = litlen; 907 lastSequence.mlen = maxML; 908 lastSequence.off = maxOffset; 909 DEBUGLOG(6, "large match (%u>%u), immediate encoding", 910 maxML, sufficient_len); 911 cur = 0; 912 last_pos = ZSTD_totalLen(lastSequence); 913 goto _shortestPath; 914 } } 915 916 /* set prices for first matches starting position == 0 */ 917 { U32 const literalsPrice = opt[0].price + ZSTD_litLengthPrice(0, optStatePtr, optLevel); 918 U32 pos; 919 U32 matchNb; 920 for (pos = 1; pos < minMatch; pos++) { 921 opt[pos].price = ZSTD_MAX_PRICE; /* mlen, litlen and price will be fixed during forward scanning */ 922 } 923 for (matchNb = 0; matchNb < nbMatches; matchNb++) { 924 U32 const offset = matches[matchNb].off; 925 U32 const end = matches[matchNb].len; 926 repcodes_t const repHistory = ZSTD_updateRep(rep, offset, ll0); 927 for ( ; pos <= end ; pos++ ) { 928 U32 const matchPrice = ZSTD_getMatchPrice(offset, pos, optStatePtr, optLevel); 929 U32 const sequencePrice = literalsPrice + matchPrice; 930 DEBUGLOG(7, "rPos:%u => set initial price : %.2f", 931 pos, ZSTD_fCost(sequencePrice)); 932 opt[pos].mlen = pos; 933 opt[pos].off = offset; 934 opt[pos].litlen = litlen; 935 opt[pos].price = sequencePrice; 936 ZSTD_STATIC_ASSERT(sizeof(opt[pos].rep) == sizeof(repHistory)); 937 memcpy(opt[pos].rep, &repHistory, sizeof(repHistory)); 938 } } 939 last_pos = pos-1; 940 } 941 } 942 943 /* check further positions */ 944 for (cur = 1; cur <= last_pos; cur++) { 945 const BYTE* const inr = ip + cur; 946 assert(cur < ZSTD_OPT_NUM); 947 DEBUGLOG(7, "cPos:%zi==rPos:%u", inr-istart, cur) 948 949 /* Fix current position with one literal if cheaper */ 950 { U32 const litlen = (opt[cur-1].mlen == 0) ? opt[cur-1].litlen + 1 : 1; 951 int const price = opt[cur-1].price 952 + ZSTD_rawLiteralsCost(ip+cur-1, 1, optStatePtr, optLevel) 953 + ZSTD_litLengthPrice(litlen, optStatePtr, optLevel) 954 - ZSTD_litLengthPrice(litlen-1, optStatePtr, optLevel); 955 assert(price < 1000000000); /* overflow check */ 956 if (price <= opt[cur].price) { 957 DEBUGLOG(7, "cPos:%zi==rPos:%u : better price (%.2f<=%.2f) using literal (ll==%u) (hist:%u,%u,%u)", 958 inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), litlen, 959 opt[cur-1].rep[0], opt[cur-1].rep[1], opt[cur-1].rep[2]); 960 opt[cur].mlen = 0; 961 opt[cur].off = 0; 962 opt[cur].litlen = litlen; 963 opt[cur].price = price; 964 memcpy(opt[cur].rep, opt[cur-1].rep, sizeof(opt[cur].rep)); 965 } else { 966 DEBUGLOG(7, "cPos:%zi==rPos:%u : literal would cost more (%.2f>%.2f) (hist:%u,%u,%u)", 967 inr-istart, cur, ZSTD_fCost(price), ZSTD_fCost(opt[cur].price), 968 opt[cur].rep[0], opt[cur].rep[1], opt[cur].rep[2]); 969 } 970 } 971 972 /* last match must start at a minimum distance of 8 from oend */ 973 if (inr > ilimit) continue; 974 975 if (cur == last_pos) break; 976 977 if ( (optLevel==0) /*static_test*/ 978 && (opt[cur+1].price <= opt[cur].price + (BITCOST_MULTIPLIER/2)) ) { 979 DEBUGLOG(7, "move to next rPos:%u : price is <=", cur+1); 980 continue; /* skip unpromising positions; about ~+6% speed, -0.01 ratio */ 981 } 982 983 { U32 const ll0 = (opt[cur].mlen != 0); 984 U32 const litlen = (opt[cur].mlen == 0) ? opt[cur].litlen : 0; 985 U32 const previousPrice = opt[cur].price; 986 U32 const basePrice = previousPrice + ZSTD_litLengthPrice(0, optStatePtr, optLevel); 987 U32 const nbMatches = ZSTD_BtGetAllMatches(matches, ms, &nextToUpdate3, inr, iend, dictMode, opt[cur].rep, ll0, minMatch); 988 U32 matchNb; 989 if (!nbMatches) { 990 DEBUGLOG(7, "rPos:%u : no match found", cur); 991 continue; 992 } 993 994 { U32 const maxML = matches[nbMatches-1].len; 995 DEBUGLOG(7, "cPos:%zi==rPos:%u, found %u matches, of maxLength=%u", 996 inr-istart, cur, nbMatches, maxML); 997 998 if ( (maxML > sufficient_len) 999 || (cur + maxML >= ZSTD_OPT_NUM) ) { 1000 lastSequence.mlen = maxML; 1001 lastSequence.off = matches[nbMatches-1].off; 1002 lastSequence.litlen = litlen; 1003 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 */ 1004 last_pos = cur + ZSTD_totalLen(lastSequence); 1005 if (cur > ZSTD_OPT_NUM) cur = 0; /* underflow => first match */ 1006 goto _shortestPath; 1007 } } 1008 1009 /* set prices using matches found at position == cur */ 1010 for (matchNb = 0; matchNb < nbMatches; matchNb++) { 1011 U32 const offset = matches[matchNb].off; 1012 repcodes_t const repHistory = ZSTD_updateRep(opt[cur].rep, offset, ll0); 1013 U32 const lastML = matches[matchNb].len; 1014 U32 const startML = (matchNb>0) ? matches[matchNb-1].len+1 : minMatch; 1015 U32 mlen; 1016 1017 DEBUGLOG(7, "testing match %u => offCode=%4u, mlen=%2u, llen=%2u", 1018 matchNb, matches[matchNb].off, lastML, litlen); 1019 1020 for (mlen = lastML; mlen >= startML; mlen--) { /* scan downward */ 1021 U32 const pos = cur + mlen; 1022 int const price = basePrice + ZSTD_getMatchPrice(offset, mlen, optStatePtr, optLevel); 1023 1024 if ((pos > last_pos) || (price < opt[pos].price)) { 1025 DEBUGLOG(7, "rPos:%u (ml=%2u) => new better price (%.2f<%.2f)", 1026 pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price)); 1027 while (last_pos < pos) { opt[last_pos+1].price = ZSTD_MAX_PRICE; last_pos++; } /* fill empty positions */ 1028 opt[pos].mlen = mlen; 1029 opt[pos].off = offset; 1030 opt[pos].litlen = litlen; 1031 opt[pos].price = price; 1032 ZSTD_STATIC_ASSERT(sizeof(opt[pos].rep) == sizeof(repHistory)); 1033 memcpy(opt[pos].rep, &repHistory, sizeof(repHistory)); 1034 } else { 1035 DEBUGLOG(7, "rPos:%u (ml=%2u) => new price is worse (%.2f>=%.2f)", 1036 pos, mlen, ZSTD_fCost(price), ZSTD_fCost(opt[pos].price)); 1037 if (optLevel==0) break; /* early update abort; gets ~+10% speed for about -0.01 ratio loss */ 1038 } 1039 } } } 1040 } /* for (cur = 1; cur <= last_pos; cur++) */ 1041 1042 lastSequence = opt[last_pos]; 1043 cur = last_pos > ZSTD_totalLen(lastSequence) ? last_pos - ZSTD_totalLen(lastSequence) : 0; /* single sequence, and it starts before `ip` */ 1044 assert(cur < ZSTD_OPT_NUM); /* control overflow*/ 1045 1046 _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */ 1047 assert(opt[0].mlen == 0); 1048 1049 { U32 const storeEnd = cur + 1; 1050 U32 storeStart = storeEnd; 1051 U32 seqPos = cur; 1052 1053 DEBUGLOG(6, "start reverse traversal (last_pos:%u, cur:%u)", 1054 last_pos, cur); (void)last_pos; 1055 assert(storeEnd < ZSTD_OPT_NUM); 1056 DEBUGLOG(6, "last sequence copied into pos=%u (llen=%u,mlen=%u,ofc=%u)", 1057 storeEnd, lastSequence.litlen, lastSequence.mlen, lastSequence.off); 1058 opt[storeEnd] = lastSequence; 1059 while (seqPos > 0) { 1060 U32 const backDist = ZSTD_totalLen(opt[seqPos]); 1061 storeStart--; 1062 DEBUGLOG(6, "sequence from rPos=%u copied into pos=%u (llen=%u,mlen=%u,ofc=%u)", 1063 seqPos, storeStart, opt[seqPos].litlen, opt[seqPos].mlen, opt[seqPos].off); 1064 opt[storeStart] = opt[seqPos]; 1065 seqPos = (seqPos > backDist) ? seqPos - backDist : 0; 1066 } 1067 1068 /* save sequences */ 1069 DEBUGLOG(6, "sending selected sequences into seqStore") 1070 { U32 storePos; 1071 for (storePos=storeStart; storePos <= storeEnd; storePos++) { 1072 U32 const llen = opt[storePos].litlen; 1073 U32 const mlen = opt[storePos].mlen; 1074 U32 const offCode = opt[storePos].off; 1075 U32 const advance = llen + mlen; 1076 DEBUGLOG(6, "considering seq starting at %zi, llen=%u, mlen=%u", 1077 anchor - istart, (unsigned)llen, (unsigned)mlen); 1078 1079 if (mlen==0) { /* only literals => must be last "sequence", actually starting a new stream of sequences */ 1080 assert(storePos == storeEnd); /* must be last sequence */ 1081 ip = anchor + llen; /* last "sequence" is a bunch of literals => don't progress anchor */ 1082 continue; /* will finish */ 1083 } 1084 1085 /* repcodes update : like ZSTD_updateRep(), but update in place */ 1086 if (offCode >= ZSTD_REP_NUM) { /* full offset */ 1087 rep[2] = rep[1]; 1088 rep[1] = rep[0]; 1089 rep[0] = offCode - ZSTD_REP_MOVE; 1090 } else { /* repcode */ 1091 U32 const repCode = offCode + (llen==0); 1092 if (repCode) { /* note : if repCode==0, no change */ 1093 U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 1094 if (repCode >= 2) rep[2] = rep[1]; 1095 rep[1] = rep[0]; 1096 rep[0] = currentOffset; 1097 } } 1098 1099 assert(anchor + llen <= iend); 1100 ZSTD_updateStats(optStatePtr, llen, anchor, offCode, mlen); 1101 ZSTD_storeSeq(seqStore, llen, anchor, iend, offCode, mlen-MINMATCH); 1102 anchor += advance; 1103 ip = anchor; 1104 } } 1105 ZSTD_setBasePrices(optStatePtr, optLevel); 1106 } 1107 1108 } /* while (ip < ilimit) */ 1109 1110 /* Return the last literals size */ 1111 return (size_t)(iend - anchor); 1112 } 1113 1114 1115 size_t ZSTD_compressBlock_btopt( 1116 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1117 const void* src, size_t srcSize) 1118 { 1119 DEBUGLOG(5, "ZSTD_compressBlock_btopt"); 1120 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_noDict); 1121 } 1122 1123 1124 /* used in 2-pass strategy */ 1125 static U32 ZSTD_upscaleStat(unsigned* table, U32 lastEltIndex, int bonus) 1126 { 1127 U32 s, sum=0; 1128 assert(ZSTD_FREQ_DIV+bonus >= 0); 1129 for (s=0; s<lastEltIndex+1; s++) { 1130 table[s] <<= ZSTD_FREQ_DIV+bonus; 1131 table[s]--; 1132 sum += table[s]; 1133 } 1134 return sum; 1135 } 1136 1137 /* used in 2-pass strategy */ 1138 MEM_STATIC void ZSTD_upscaleStats(optState_t* optPtr) 1139 { 1140 if (ZSTD_compressedLiterals(optPtr)) 1141 optPtr->litSum = ZSTD_upscaleStat(optPtr->litFreq, MaxLit, 0); 1142 optPtr->litLengthSum = ZSTD_upscaleStat(optPtr->litLengthFreq, MaxLL, 0); 1143 optPtr->matchLengthSum = ZSTD_upscaleStat(optPtr->matchLengthFreq, MaxML, 0); 1144 optPtr->offCodeSum = ZSTD_upscaleStat(optPtr->offCodeFreq, MaxOff, 0); 1145 } 1146 1147 /* ZSTD_initStats_ultra(): 1148 * make a first compression pass, just to seed stats with more accurate starting values. 1149 * only works on first block, with no dictionary and no ldm. 1150 * this function cannot error, hence its contract must be respected. 1151 */ 1152 static void 1153 ZSTD_initStats_ultra(ZSTD_matchState_t* ms, 1154 seqStore_t* seqStore, 1155 U32 rep[ZSTD_REP_NUM], 1156 const void* src, size_t srcSize) 1157 { 1158 U32 tmpRep[ZSTD_REP_NUM]; /* updated rep codes will sink here */ 1159 memcpy(tmpRep, rep, sizeof(tmpRep)); 1160 1161 DEBUGLOG(4, "ZSTD_initStats_ultra (srcSize=%zu)", srcSize); 1162 assert(ms->opt.litLengthSum == 0); /* first block */ 1163 assert(seqStore->sequences == seqStore->sequencesStart); /* no ldm */ 1164 assert(ms->window.dictLimit == ms->window.lowLimit); /* no dictionary */ 1165 assert(ms->window.dictLimit - ms->nextToUpdate <= 1); /* no prefix (note: intentional overflow, defined as 2-complement) */ 1166 1167 ZSTD_compressBlock_opt_generic(ms, seqStore, tmpRep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); /* generate stats into ms->opt*/ 1168 1169 /* invalidate first scan from history */ 1170 ZSTD_resetSeqStore(seqStore); 1171 ms->window.base -= srcSize; 1172 ms->window.dictLimit += (U32)srcSize; 1173 ms->window.lowLimit = ms->window.dictLimit; 1174 ms->nextToUpdate = ms->window.dictLimit; 1175 1176 /* re-inforce weight of collected statistics */ 1177 ZSTD_upscaleStats(&ms->opt); 1178 } 1179 1180 size_t ZSTD_compressBlock_btultra( 1181 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1182 const void* src, size_t srcSize) 1183 { 1184 DEBUGLOG(5, "ZSTD_compressBlock_btultra (srcSize=%zu)", srcSize); 1185 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); 1186 } 1187 1188 size_t ZSTD_compressBlock_btultra2( 1189 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1190 const void* src, size_t srcSize) 1191 { 1192 U32 const current = (U32)((const BYTE*)src - ms->window.base); 1193 DEBUGLOG(5, "ZSTD_compressBlock_btultra2 (srcSize=%zu)", srcSize); 1194 1195 /* 2-pass strategy: 1196 * this strategy makes a first pass over first block to collect statistics 1197 * and seed next round's statistics with it. 1198 * After 1st pass, function forgets everything, and starts a new block. 1199 * Consequently, this can only work if no data has been previously loaded in tables, 1200 * aka, no dictionary, no prefix, no ldm preprocessing. 1201 * The compression ratio gain is generally small (~0.5% on first block), 1202 * the cost is 2x cpu time on first block. */ 1203 assert(srcSize <= ZSTD_BLOCKSIZE_MAX); 1204 if ( (ms->opt.litLengthSum==0) /* first block */ 1205 && (seqStore->sequences == seqStore->sequencesStart) /* no ldm */ 1206 && (ms->window.dictLimit == ms->window.lowLimit) /* no dictionary */ 1207 && (current == ms->window.dictLimit) /* start of frame, nothing already loaded nor skipped */ 1208 && (srcSize > ZSTD_PREDEF_THRESHOLD) 1209 ) { 1210 ZSTD_initStats_ultra(ms, seqStore, rep, src, srcSize); 1211 } 1212 1213 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_noDict); 1214 } 1215 1216 size_t ZSTD_compressBlock_btopt_dictMatchState( 1217 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1218 const void* src, size_t srcSize) 1219 { 1220 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_dictMatchState); 1221 } 1222 1223 size_t ZSTD_compressBlock_btultra_dictMatchState( 1224 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1225 const void* src, size_t srcSize) 1226 { 1227 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_dictMatchState); 1228 } 1229 1230 size_t ZSTD_compressBlock_btopt_extDict( 1231 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1232 const void* src, size_t srcSize) 1233 { 1234 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 0 /*optLevel*/, ZSTD_extDict); 1235 } 1236 1237 size_t ZSTD_compressBlock_btultra_extDict( 1238 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1239 const void* src, size_t srcSize) 1240 { 1241 return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, src, srcSize, 2 /*optLevel*/, ZSTD_extDict); 1242 } 1243 1244 /* note : no btultra2 variant for extDict nor dictMatchState, 1245 * because btultra2 is not meant to work with dictionaries 1246 * and is only specific for the first block (no prefix) */ 1247