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 "zstd_opt.h" 13 #include "zstd_lazy.h" /* ZSTD_updateTree, ZSTD_updateTree_extDict */ 14 15 16 #define ZSTD_LITFREQ_ADD 2 /* scaling factor for litFreq, so that frequencies adapt faster to new stats. Also used for matchSum (?) */ 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 21 /*-************************************* 22 * Price functions for optimal parser 23 ***************************************/ 24 static void ZSTD_setLog2Prices(optState_t* optPtr) 25 { 26 optPtr->log2litSum = ZSTD_highbit32(optPtr->litSum+1); 27 optPtr->log2litLengthSum = ZSTD_highbit32(optPtr->litLengthSum+1); 28 optPtr->log2matchLengthSum = ZSTD_highbit32(optPtr->matchLengthSum+1); 29 optPtr->log2offCodeSum = ZSTD_highbit32(optPtr->offCodeSum+1); 30 } 31 32 33 static void ZSTD_rescaleFreqs(optState_t* const optPtr, 34 const BYTE* const src, size_t const srcSize) 35 { 36 optPtr->staticPrices = 0; 37 38 if (optPtr->litLengthSum == 0) { /* first init */ 39 unsigned u; 40 if (srcSize <= 1024) optPtr->staticPrices = 1; 41 42 assert(optPtr->litFreq!=NULL); 43 for (u=0; u<=MaxLit; u++) 44 optPtr->litFreq[u] = 0; 45 for (u=0; u<srcSize; u++) 46 optPtr->litFreq[src[u]]++; 47 optPtr->litSum = 0; 48 for (u=0; u<=MaxLit; u++) { 49 optPtr->litFreq[u] = 1 + (optPtr->litFreq[u] >> ZSTD_FREQ_DIV); 50 optPtr->litSum += optPtr->litFreq[u]; 51 } 52 53 for (u=0; u<=MaxLL; u++) 54 optPtr->litLengthFreq[u] = 1; 55 optPtr->litLengthSum = MaxLL+1; 56 for (u=0; u<=MaxML; u++) 57 optPtr->matchLengthFreq[u] = 1; 58 optPtr->matchLengthSum = MaxML+1; 59 for (u=0; u<=MaxOff; u++) 60 optPtr->offCodeFreq[u] = 1; 61 optPtr->offCodeSum = (MaxOff+1); 62 63 } else { 64 unsigned u; 65 66 optPtr->litSum = 0; 67 for (u=0; u<=MaxLit; u++) { 68 optPtr->litFreq[u] = 1 + (optPtr->litFreq[u] >> (ZSTD_FREQ_DIV+1)); 69 optPtr->litSum += optPtr->litFreq[u]; 70 } 71 optPtr->litLengthSum = 0; 72 for (u=0; u<=MaxLL; u++) { 73 optPtr->litLengthFreq[u] = 1 + (optPtr->litLengthFreq[u]>>(ZSTD_FREQ_DIV+1)); 74 optPtr->litLengthSum += optPtr->litLengthFreq[u]; 75 } 76 optPtr->matchLengthSum = 0; 77 for (u=0; u<=MaxML; u++) { 78 optPtr->matchLengthFreq[u] = 1 + (optPtr->matchLengthFreq[u]>>ZSTD_FREQ_DIV); 79 optPtr->matchLengthSum += optPtr->matchLengthFreq[u]; 80 } 81 optPtr->offCodeSum = 0; 82 for (u=0; u<=MaxOff; u++) { 83 optPtr->offCodeFreq[u] = 1 + (optPtr->offCodeFreq[u]>>ZSTD_FREQ_DIV); 84 optPtr->offCodeSum += optPtr->offCodeFreq[u]; 85 } 86 } 87 88 ZSTD_setLog2Prices(optPtr); 89 } 90 91 92 /* ZSTD_rawLiteralsCost() : 93 * cost of literals (only) in given segment (which length can be null) 94 * does not include cost of literalLength symbol */ 95 static U32 ZSTD_rawLiteralsCost(const BYTE* const literals, U32 const litLength, 96 const optState_t* const optPtr) 97 { 98 if (optPtr->staticPrices) return (litLength*6); /* 6 bit per literal - no statistic used */ 99 if (litLength == 0) return 0; 100 101 /* literals */ 102 { U32 u; 103 U32 cost = litLength * optPtr->log2litSum; 104 for (u=0; u < litLength; u++) 105 cost -= ZSTD_highbit32(optPtr->litFreq[literals[u]]+1); 106 return cost; 107 } 108 } 109 110 /* ZSTD_litLengthPrice() : 111 * cost of literalLength symbol */ 112 static U32 ZSTD_litLengthPrice(U32 const litLength, const optState_t* const optPtr) 113 { 114 if (optPtr->staticPrices) return ZSTD_highbit32((U32)litLength+1); 115 116 /* literal Length */ 117 { U32 const llCode = ZSTD_LLcode(litLength); 118 U32 const price = LL_bits[llCode] + optPtr->log2litLengthSum - ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1); 119 return price; 120 } 121 } 122 123 /* ZSTD_litLengthPrice() : 124 * cost of the literal part of a sequence, 125 * including literals themselves, and literalLength symbol */ 126 static U32 ZSTD_fullLiteralsCost(const BYTE* const literals, U32 const litLength, 127 const optState_t* const optPtr) 128 { 129 return ZSTD_rawLiteralsCost(literals, litLength, optPtr) 130 + ZSTD_litLengthPrice(litLength, optPtr); 131 } 132 133 /* ZSTD_litLengthContribution() : 134 * @return ( cost(litlength) - cost(0) ) 135 * this value can then be added to rawLiteralsCost() 136 * to provide a cost which is directly comparable to a match ending at same position */ 137 static int ZSTD_litLengthContribution(U32 const litLength, const optState_t* const optPtr) 138 { 139 if (optPtr->staticPrices) return ZSTD_highbit32(litLength+1); 140 141 /* literal Length */ 142 { U32 const llCode = ZSTD_LLcode(litLength); 143 int const contribution = LL_bits[llCode] 144 + ZSTD_highbit32(optPtr->litLengthFreq[0]+1) 145 - ZSTD_highbit32(optPtr->litLengthFreq[llCode]+1); 146 #if 1 147 return contribution; 148 #else 149 return MAX(0, contribution); /* sometimes better, sometimes not ... */ 150 #endif 151 } 152 } 153 154 /* ZSTD_literalsContribution() : 155 * creates a fake cost for the literals part of a sequence 156 * which can be compared to the ending cost of a match 157 * should a new match start at this position */ 158 static int ZSTD_literalsContribution(const BYTE* const literals, U32 const litLength, 159 const optState_t* const optPtr) 160 { 161 int const contribution = ZSTD_rawLiteralsCost(literals, litLength, optPtr) 162 + ZSTD_litLengthContribution(litLength, optPtr); 163 return contribution; 164 } 165 166 /* ZSTD_getMatchPrice() : 167 * Provides the cost of the match part (offset + matchLength) of a sequence 168 * Must be combined with ZSTD_fullLiteralsCost() to get the full cost of a sequence. 169 * optLevel: when <2, favors small offset for decompression speed (improved cache efficiency) */ 170 FORCE_INLINE_TEMPLATE U32 ZSTD_getMatchPrice( 171 U32 const offset, U32 const matchLength, 172 const optState_t* const optPtr, 173 int const optLevel) 174 { 175 U32 price; 176 U32 const offCode = ZSTD_highbit32(offset+1); 177 U32 const mlBase = matchLength - MINMATCH; 178 assert(matchLength >= MINMATCH); 179 180 if (optPtr->staticPrices) /* fixed scheme, do not use statistics */ 181 return ZSTD_highbit32((U32)mlBase+1) + 16 + offCode; 182 183 price = offCode + optPtr->log2offCodeSum - ZSTD_highbit32(optPtr->offCodeFreq[offCode]+1); 184 if ((optLevel<2) /*static*/ && offCode >= 20) price += (offCode-19)*2; /* handicap for long distance offsets, favor decompression speed */ 185 186 /* match Length */ 187 { U32 const mlCode = ZSTD_MLcode(mlBase); 188 price += ML_bits[mlCode] + optPtr->log2matchLengthSum - ZSTD_highbit32(optPtr->matchLengthFreq[mlCode]+1); 189 } 190 191 DEBUGLOG(8, "ZSTD_getMatchPrice(ml:%u) = %u", matchLength, price); 192 return price; 193 } 194 195 static void ZSTD_updateStats(optState_t* const optPtr, 196 U32 litLength, const BYTE* literals, 197 U32 offsetCode, U32 matchLength) 198 { 199 /* literals */ 200 { U32 u; 201 for (u=0; u < litLength; u++) 202 optPtr->litFreq[literals[u]] += ZSTD_LITFREQ_ADD; 203 optPtr->litSum += litLength*ZSTD_LITFREQ_ADD; 204 } 205 206 /* literal Length */ 207 { U32 const llCode = ZSTD_LLcode(litLength); 208 optPtr->litLengthFreq[llCode]++; 209 optPtr->litLengthSum++; 210 } 211 212 /* match offset code (0-2=>repCode; 3+=>offset+2) */ 213 { U32 const offCode = ZSTD_highbit32(offsetCode+1); 214 assert(offCode <= MaxOff); 215 optPtr->offCodeFreq[offCode]++; 216 optPtr->offCodeSum++; 217 } 218 219 /* match Length */ 220 { U32 const mlBase = matchLength - MINMATCH; 221 U32 const mlCode = ZSTD_MLcode(mlBase); 222 optPtr->matchLengthFreq[mlCode]++; 223 optPtr->matchLengthSum++; 224 } 225 } 226 227 228 /* ZSTD_readMINMATCH() : 229 * function safe only for comparisons 230 * assumption : memPtr must be at least 4 bytes before end of buffer */ 231 MEM_STATIC U32 ZSTD_readMINMATCH(const void* memPtr, U32 length) 232 { 233 switch (length) 234 { 235 default : 236 case 4 : return MEM_read32(memPtr); 237 case 3 : if (MEM_isLittleEndian()) 238 return MEM_read32(memPtr)<<8; 239 else 240 return MEM_read32(memPtr)>>8; 241 } 242 } 243 244 245 /* Update hashTable3 up to ip (excluded) 246 Assumption : always within prefix (i.e. not within extDict) */ 247 static U32 ZSTD_insertAndFindFirstIndexHash3 (ZSTD_CCtx* const cctx, const BYTE* const ip) 248 { 249 U32* const hashTable3 = cctx->hashTable3; 250 U32 const hashLog3 = cctx->hashLog3; 251 const BYTE* const base = cctx->base; 252 U32 idx = cctx->nextToUpdate3; 253 U32 const target = cctx->nextToUpdate3 = (U32)(ip - base); 254 size_t const hash3 = ZSTD_hash3Ptr(ip, hashLog3); 255 256 while(idx < target) { 257 hashTable3[ZSTD_hash3Ptr(base+idx, hashLog3)] = idx; 258 idx++; 259 } 260 261 return hashTable3[hash3]; 262 } 263 264 265 /*-************************************* 266 * Binary Tree search 267 ***************************************/ 268 FORCE_INLINE_TEMPLATE 269 U32 ZSTD_insertBtAndGetAllMatches ( 270 ZSTD_CCtx* zc, 271 const BYTE* const ip, const BYTE* const iLimit, int const extDict, 272 U32 nbCompares, U32 const mls, U32 const sufficient_len, 273 U32 rep[ZSTD_REP_NUM], U32 const ll0, 274 ZSTD_match_t* matches, const U32 lengthToBeat) 275 { 276 const BYTE* const base = zc->base; 277 U32 const current = (U32)(ip-base); 278 U32 const hashLog = zc->appliedParams.cParams.hashLog; 279 U32 const minMatch = (mls==3) ? 3 : 4; 280 U32* const hashTable = zc->hashTable; 281 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 282 U32 matchIndex = hashTable[h]; 283 U32* const bt = zc->chainTable; 284 U32 const btLog = zc->appliedParams.cParams.chainLog - 1; 285 U32 const btMask= (1U << btLog) - 1; 286 size_t commonLengthSmaller=0, commonLengthLarger=0; 287 const BYTE* const dictBase = zc->dictBase; 288 U32 const dictLimit = zc->dictLimit; 289 const BYTE* const dictEnd = dictBase + dictLimit; 290 const BYTE* const prefixStart = base + dictLimit; 291 U32 const btLow = btMask >= current ? 0 : current - btMask; 292 U32 const windowLow = zc->lowLimit; 293 U32* smallerPtr = bt + 2*(current&btMask); 294 U32* largerPtr = bt + 2*(current&btMask) + 1; 295 U32 matchEndIdx = current+8+1; /* farthest referenced position of any match => detects repetitive patterns */ 296 U32 dummy32; /* to be nullified at the end */ 297 U32 mnum = 0; 298 299 size_t bestLength = lengthToBeat-1; 300 DEBUGLOG(7, "ZSTD_insertBtAndGetAllMatches"); 301 302 /* check repCode */ 303 { U32 const lastR = ZSTD_REP_NUM + ll0; 304 U32 repCode; 305 for (repCode = ll0; repCode < lastR; repCode++) { 306 U32 const repOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 307 U32 const repIndex = current - repOffset; 308 U32 repLen = 0; 309 assert(current >= dictLimit); 310 if (repOffset-1 /* intentional overflow, discards 0 and -1 */ < current-dictLimit) { /* equivalent to `current > repIndex >= dictLimit` */ 311 if (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(ip - repOffset, minMatch)) { 312 repLen = (U32)ZSTD_count(ip+minMatch, ip+minMatch-repOffset, iLimit) + minMatch; 313 } 314 } else { /* repIndex < dictLimit || repIndex >= current */ 315 const BYTE* const repMatch = dictBase + repIndex; 316 assert(current >= windowLow); 317 if ( extDict /* this case only valid in extDict mode */ 318 && ( ((repOffset-1) /*intentional overflow*/ < current - windowLow) /* equivalent to `current > repIndex >= windowLow` */ 319 & (((U32)((dictLimit-1) - repIndex) >= 3) ) /* intentional overflow : do not test positions overlapping 2 memory segments */) 320 && (ZSTD_readMINMATCH(ip, minMatch) == ZSTD_readMINMATCH(repMatch, minMatch)) ) { 321 repLen = (U32)ZSTD_count_2segments(ip+minMatch, repMatch+minMatch, iLimit, dictEnd, prefixStart) + minMatch; 322 } } 323 /* save longer solution */ 324 if (repLen > bestLength) { 325 DEBUGLOG(8, "found rep-match %u of length %u", 326 repCode - ll0, (U32)repLen); 327 bestLength = repLen; 328 matches[mnum].off = repCode - ll0; 329 matches[mnum].len = (U32)repLen; 330 mnum++; 331 if ( (repLen > sufficient_len) 332 | (ip+repLen == iLimit) ) { /* best possible */ 333 return mnum; 334 } } } } 335 336 /* HC3 match finder */ 337 if ((mls == 3) /*static*/ && (bestLength < mls)) { 338 U32 const matchIndex3 = ZSTD_insertAndFindFirstIndexHash3 (zc, ip); 339 if ((matchIndex3 > windowLow) 340 & (current - matchIndex3 < (1<<18)) /*heuristic : longer distance likely too expensive*/ ) { 341 size_t mlen; 342 if ((!extDict) /*static*/ || (matchIndex3 >= dictLimit)) { 343 const BYTE* const match = base + matchIndex3; 344 mlen = ZSTD_count(ip, match, iLimit); 345 } else { 346 const BYTE* const match = dictBase + matchIndex3; 347 mlen = ZSTD_count_2segments(ip, match, iLimit, dictEnd, prefixStart); 348 } 349 350 /* save best solution */ 351 if (mlen >= mls /* == 3 > bestLength */) { 352 DEBUGLOG(8, "found small match with hlog3, of length %u", 353 (U32)mlen); 354 bestLength = mlen; 355 assert(current > matchIndex3); 356 assert(mnum==0); /* no prior solution */ 357 matches[0].off = (current - matchIndex3) + ZSTD_REP_MOVE; 358 matches[0].len = (U32)mlen; 359 mnum = 1; 360 if ( (mlen > sufficient_len) | 361 (ip+mlen == iLimit) ) { /* best possible length */ 362 zc->nextToUpdate = current+1; /* skip insertion */ 363 return 1; 364 } } } } 365 366 hashTable[h] = current; /* Update Hash Table */ 367 368 while (nbCompares-- && (matchIndex > windowLow)) { 369 U32* const nextPtr = bt + 2*(matchIndex & btMask); 370 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 371 const BYTE* match; 372 assert(current > matchIndex); 373 374 if ((!extDict) || (matchIndex+matchLength >= dictLimit)) { 375 assert(matchIndex+matchLength >= dictLimit); /* ensure the condition is correct when !extDict */ 376 match = base + matchIndex; 377 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iLimit); 378 } else { 379 match = dictBase + matchIndex; 380 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iLimit, dictEnd, prefixStart); 381 if (matchIndex+matchLength >= dictLimit) 382 match = base + matchIndex; /* prepare for match[matchLength] */ 383 } 384 385 if (matchLength > bestLength) { 386 DEBUGLOG(8, "found match of length %u at distance %u", 387 (U32)matchLength, current - matchIndex); 388 assert(matchEndIdx > matchIndex); 389 if (matchLength > matchEndIdx - matchIndex) 390 matchEndIdx = matchIndex + (U32)matchLength; 391 bestLength = matchLength; 392 matches[mnum].off = (current - matchIndex) + ZSTD_REP_MOVE; 393 matches[mnum].len = (U32)matchLength; 394 mnum++; 395 if (matchLength > ZSTD_OPT_NUM) break; 396 if (ip+matchLength == iLimit) { /* equal : no way to know if inf or sup */ 397 break; /* drop, to preserve bt consistency (miss a little bit of compression) */ 398 } 399 } 400 401 if (match[matchLength] < ip[matchLength]) { 402 /* match smaller than current */ 403 *smallerPtr = matchIndex; /* update smaller idx */ 404 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 405 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 406 smallerPtr = nextPtr+1; /* new candidate => larger than match, which was smaller than current */ 407 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous, closer to current */ 408 } else { 409 *largerPtr = matchIndex; 410 commonLengthLarger = matchLength; 411 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 412 largerPtr = nextPtr; 413 matchIndex = nextPtr[0]; 414 } } 415 416 *smallerPtr = *largerPtr = 0; 417 418 assert(matchEndIdx > current+8); 419 zc->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ 420 return mnum; 421 } 422 423 424 FORCE_INLINE_TEMPLATE U32 ZSTD_BtGetAllMatches ( 425 ZSTD_CCtx* zc, /* Index table will be updated */ 426 const BYTE* ip, const BYTE* const iHighLimit, int const extDict, 427 U32 const maxNbAttempts, U32 const matchLengthSearch, U32 const sufficient_len, 428 U32 rep[ZSTD_REP_NUM], U32 const ll0, 429 ZSTD_match_t* matches, U32 const lengthToBeat) 430 { 431 DEBUGLOG(7, "ZSTD_BtGetAllMatches"); 432 if (ip < zc->base + zc->nextToUpdate) return 0; /* skipped area */ 433 if (extDict) ZSTD_updateTree_extDict(zc, ip, iHighLimit, maxNbAttempts, matchLengthSearch); 434 else ZSTD_updateTree(zc, ip, iHighLimit, maxNbAttempts, matchLengthSearch); 435 switch(matchLengthSearch) 436 { 437 case 3 : return ZSTD_insertBtAndGetAllMatches(zc, ip, iHighLimit, extDict, maxNbAttempts, 3, sufficient_len, rep, ll0, matches, lengthToBeat); 438 default : 439 case 4 : return ZSTD_insertBtAndGetAllMatches(zc, ip, iHighLimit, extDict, maxNbAttempts, 4, sufficient_len, rep, ll0, matches, lengthToBeat); 440 case 5 : return ZSTD_insertBtAndGetAllMatches(zc, ip, iHighLimit, extDict, maxNbAttempts, 5, sufficient_len, rep, ll0, matches, lengthToBeat); 441 case 7 : 442 case 6 : return ZSTD_insertBtAndGetAllMatches(zc, ip, iHighLimit, extDict, maxNbAttempts, 6, sufficient_len, rep, ll0, matches, lengthToBeat); 443 } 444 } 445 446 447 /*-******************************* 448 * Optimal parser 449 *********************************/ 450 typedef struct repcodes_s { 451 U32 rep[3]; 452 } repcodes_t; 453 454 repcodes_t ZSTD_updateRep(U32 const rep[3], U32 const offset, U32 const ll0) 455 { 456 repcodes_t newReps; 457 if (offset >= ZSTD_REP_NUM) { /* full offset */ 458 newReps.rep[2] = rep[1]; 459 newReps.rep[1] = rep[0]; 460 newReps.rep[0] = offset - ZSTD_REP_MOVE; 461 } else { /* repcode */ 462 U32 const repCode = offset + ll0; 463 if (repCode > 0) { /* note : if repCode==0, no change */ 464 U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 465 newReps.rep[2] = (repCode >= 2) ? rep[1] : rep[2]; 466 newReps.rep[1] = rep[0]; 467 newReps.rep[0] = currentOffset; 468 } else { /* repCode == 0 */ 469 memcpy(&newReps, rep, sizeof(newReps)); 470 } 471 } 472 return newReps; 473 } 474 475 476 typedef struct { 477 const BYTE* anchor; 478 U32 litlen; 479 U32 rawLitCost; 480 } cachedLiteralPrice_t; 481 482 static U32 ZSTD_rawLiteralsCost_cached( 483 cachedLiteralPrice_t* const cachedLitPrice, 484 const BYTE* const anchor, U32 const litlen, 485 const optState_t* const optStatePtr) 486 { 487 U32 startCost; 488 U32 remainingLength; 489 const BYTE* startPosition; 490 491 if (anchor == cachedLitPrice->anchor) { 492 startCost = cachedLitPrice->rawLitCost; 493 startPosition = anchor + cachedLitPrice->litlen; 494 assert(litlen >= cachedLitPrice->litlen); 495 remainingLength = litlen - cachedLitPrice->litlen; 496 } else { 497 startCost = 0; 498 startPosition = anchor; 499 remainingLength = litlen; 500 } 501 502 { U32 const rawLitCost = startCost + ZSTD_rawLiteralsCost(startPosition, remainingLength, optStatePtr); 503 cachedLitPrice->anchor = anchor; 504 cachedLitPrice->litlen = litlen; 505 cachedLitPrice->rawLitCost = rawLitCost; 506 return rawLitCost; 507 } 508 } 509 510 static U32 ZSTD_fullLiteralsCost_cached( 511 cachedLiteralPrice_t* const cachedLitPrice, 512 const BYTE* const anchor, U32 const litlen, 513 const optState_t* const optStatePtr) 514 { 515 return ZSTD_rawLiteralsCost_cached(cachedLitPrice, anchor, litlen, optStatePtr) 516 + ZSTD_litLengthPrice(litlen, optStatePtr); 517 } 518 519 static int ZSTD_literalsContribution_cached( 520 cachedLiteralPrice_t* const cachedLitPrice, 521 const BYTE* const anchor, U32 const litlen, 522 const optState_t* const optStatePtr) 523 { 524 int const contribution = ZSTD_rawLiteralsCost_cached(cachedLitPrice, anchor, litlen, optStatePtr) 525 + ZSTD_litLengthContribution(litlen, optStatePtr); 526 return contribution; 527 } 528 529 FORCE_INLINE_TEMPLATE 530 size_t ZSTD_compressBlock_opt_generic(ZSTD_CCtx* ctx, 531 const void* src, size_t srcSize, 532 const int optLevel, const int extDict) 533 { 534 seqStore_t* const seqStorePtr = &(ctx->seqStore); 535 optState_t* const optStatePtr = &(ctx->optState); 536 const BYTE* const istart = (const BYTE*)src; 537 const BYTE* ip = istart; 538 const BYTE* anchor = istart; 539 const BYTE* const iend = istart + srcSize; 540 const BYTE* const ilimit = iend - 8; 541 const BYTE* const base = ctx->base; 542 const BYTE* const prefixStart = base + ctx->dictLimit; 543 544 U32 const maxSearches = 1U << ctx->appliedParams.cParams.searchLog; 545 U32 const sufficient_len = MIN(ctx->appliedParams.cParams.targetLength, ZSTD_OPT_NUM -1); 546 U32 const mls = ctx->appliedParams.cParams.searchLength; 547 U32 const minMatch = (ctx->appliedParams.cParams.searchLength == 3) ? 3 : 4; 548 549 ZSTD_optimal_t* const opt = optStatePtr->priceTable; 550 ZSTD_match_t* const matches = optStatePtr->matchTable; 551 cachedLiteralPrice_t cachedLitPrice; 552 U32 rep[ZSTD_REP_NUM]; 553 554 /* init */ 555 DEBUGLOG(5, "ZSTD_compressBlock_opt_generic"); 556 ctx->nextToUpdate3 = ctx->nextToUpdate; 557 ZSTD_rescaleFreqs(optStatePtr, (const BYTE*)src, srcSize); 558 ip += (ip==prefixStart); 559 { int i; for (i=0; i<ZSTD_REP_NUM; i++) rep[i]=seqStorePtr->rep[i]; } 560 memset(&cachedLitPrice, 0, sizeof(cachedLitPrice)); 561 562 /* Match Loop */ 563 while (ip < ilimit) { 564 U32 cur, last_pos = 0; 565 U32 best_mlen, best_off; 566 567 /* find first match */ 568 { U32 const litlen = (U32)(ip - anchor); 569 U32 const ll0 = !litlen; 570 U32 const nbMatches = ZSTD_BtGetAllMatches(ctx, ip, iend, extDict, maxSearches, mls, sufficient_len, rep, ll0, matches, minMatch); 571 if (!nbMatches) { ip++; continue; } 572 573 /* initialize opt[0] */ 574 { U32 i ; for (i=0; i<ZSTD_REP_NUM; i++) opt[0].rep[i] = rep[i]; } 575 opt[0].mlen = 1; 576 opt[0].litlen = litlen; 577 578 /* large match -> immediate encoding */ 579 { U32 const maxML = matches[nbMatches-1].len; 580 DEBUGLOG(7, "found %u matches of maxLength=%u and offset=%u at cPos=%u => start new serie", 581 nbMatches, maxML, matches[nbMatches-1].off, (U32)(ip-prefixStart)); 582 583 if (maxML > sufficient_len) { 584 best_mlen = maxML; 585 best_off = matches[nbMatches-1].off; 586 DEBUGLOG(7, "large match (%u>%u), immediate encoding", 587 best_mlen, sufficient_len); 588 cur = 0; 589 last_pos = 1; 590 goto _shortestPath; 591 } } 592 593 /* set prices for first matches starting position == 0 */ 594 { U32 const literalsPrice = ZSTD_fullLiteralsCost_cached(&cachedLitPrice, anchor, litlen, optStatePtr); 595 U32 pos; 596 U32 matchNb; 597 for (pos = 0; pos < minMatch; pos++) { 598 opt[pos].mlen = 1; 599 opt[pos].price = ZSTD_MAX_PRICE; 600 } 601 for (matchNb = 0; matchNb < nbMatches; matchNb++) { 602 U32 const offset = matches[matchNb].off; 603 U32 const end = matches[matchNb].len; 604 repcodes_t const repHistory = ZSTD_updateRep(rep, offset, ll0); 605 for ( ; pos <= end ; pos++ ) { 606 U32 const matchPrice = literalsPrice + ZSTD_getMatchPrice(offset, pos, optStatePtr, optLevel); 607 DEBUGLOG(7, "rPos:%u => set initial price : %u", 608 pos, matchPrice); 609 opt[pos].mlen = pos; 610 opt[pos].off = offset; 611 opt[pos].litlen = litlen; 612 opt[pos].price = matchPrice; 613 memcpy(opt[pos].rep, &repHistory, sizeof(repHistory)); 614 } } 615 last_pos = pos-1; 616 } 617 } 618 619 /* check further positions */ 620 for (cur = 1; cur <= last_pos; cur++) { 621 const BYTE* const inr = ip + cur; 622 assert(cur < ZSTD_OPT_NUM); 623 624 /* Fix current position with one literal if cheaper */ 625 { U32 const litlen = (opt[cur-1].mlen == 1) ? opt[cur-1].litlen + 1 : 1; 626 int price; /* note : contribution can be negative */ 627 if (cur > litlen) { 628 price = opt[cur - litlen].price + ZSTD_literalsContribution(inr-litlen, litlen, optStatePtr); 629 } else { 630 price = ZSTD_literalsContribution_cached(&cachedLitPrice, anchor, litlen, optStatePtr); 631 } 632 assert(price < 1000000000); /* overflow check */ 633 if (price <= opt[cur].price) { 634 DEBUGLOG(7, "rPos:%u : better price (%u<%u) using literal", 635 cur, price, opt[cur].price); 636 opt[cur].mlen = 1; 637 opt[cur].off = 0; 638 opt[cur].litlen = litlen; 639 opt[cur].price = price; 640 memcpy(opt[cur].rep, opt[cur-1].rep, sizeof(opt[cur].rep)); 641 } } 642 643 /* last match must start at a minimum distance of 8 from oend */ 644 if (inr > ilimit) continue; 645 646 if (cur == last_pos) break; 647 648 if ( (optLevel==0) /*static*/ 649 && (opt[cur+1].price <= opt[cur].price) ) 650 continue; /* skip unpromising positions; about ~+6% speed, -0.01 ratio */ 651 652 { U32 const ll0 = (opt[cur].mlen != 1); 653 U32 const litlen = (opt[cur].mlen == 1) ? opt[cur].litlen : 0; 654 U32 const previousPrice = (cur > litlen) ? opt[cur-litlen].price : 0; 655 U32 const basePrice = previousPrice + ZSTD_fullLiteralsCost(inr-litlen, litlen, optStatePtr); 656 U32 const nbMatches = ZSTD_BtGetAllMatches(ctx, inr, iend, extDict, maxSearches, mls, sufficient_len, opt[cur].rep, ll0, matches, minMatch); 657 U32 matchNb; 658 if (!nbMatches) continue; 659 660 { U32 const maxML = matches[nbMatches-1].len; 661 DEBUGLOG(7, "rPos:%u, found %u matches, of maxLength=%u", 662 cur, nbMatches, maxML); 663 664 if ( (maxML > sufficient_len) 665 | (cur + maxML >= ZSTD_OPT_NUM) ) { 666 best_mlen = maxML; 667 best_off = matches[nbMatches-1].off; 668 last_pos = cur + 1; 669 goto _shortestPath; 670 } 671 } 672 673 /* set prices using matches found at position == cur */ 674 for (matchNb = 0; matchNb < nbMatches; matchNb++) { 675 U32 const offset = matches[matchNb].off; 676 repcodes_t const repHistory = ZSTD_updateRep(opt[cur].rep, offset, ll0); 677 U32 const lastML = matches[matchNb].len; 678 U32 const startML = (matchNb>0) ? matches[matchNb-1].len+1 : minMatch; 679 U32 mlen; 680 681 DEBUGLOG(7, "testing match %u => offCode=%u, mlen=%u, llen=%u", 682 matchNb, matches[matchNb].off, lastML, litlen); 683 684 for (mlen = lastML; mlen >= startML; mlen--) { 685 U32 const pos = cur + mlen; 686 int const price = basePrice + ZSTD_getMatchPrice(offset, mlen, optStatePtr, optLevel); 687 688 if ((pos > last_pos) || (price < opt[pos].price)) { 689 DEBUGLOG(7, "rPos:%u => new better price (%u<%u)", 690 pos, price, opt[pos].price); 691 while (last_pos < pos) { opt[last_pos+1].price = ZSTD_MAX_PRICE; last_pos++; } 692 opt[pos].mlen = mlen; 693 opt[pos].off = offset; 694 opt[pos].litlen = litlen; 695 opt[pos].price = price; 696 memcpy(opt[pos].rep, &repHistory, sizeof(repHistory)); 697 } else { 698 if (optLevel==0) break; /* gets ~+10% speed for about -0.01 ratio loss */ 699 } 700 } } } 701 } /* for (cur = 1; cur <= last_pos; cur++) */ 702 703 best_mlen = opt[last_pos].mlen; 704 best_off = opt[last_pos].off; 705 cur = last_pos - best_mlen; 706 707 _shortestPath: /* cur, last_pos, best_mlen, best_off have to be set */ 708 assert(opt[0].mlen == 1); 709 710 /* reverse traversal */ 711 DEBUGLOG(7, "start reverse traversal (last_pos:%u, cur:%u)", 712 last_pos, cur); 713 { U32 selectedMatchLength = best_mlen; 714 U32 selectedOffset = best_off; 715 U32 pos = cur; 716 while (1) { 717 U32 const mlen = opt[pos].mlen; 718 U32 const off = opt[pos].off; 719 opt[pos].mlen = selectedMatchLength; 720 opt[pos].off = selectedOffset; 721 selectedMatchLength = mlen; 722 selectedOffset = off; 723 if (mlen > pos) break; 724 pos -= mlen; 725 } } 726 727 /* save sequences */ 728 { U32 pos; 729 for (pos=0; pos < last_pos; ) { 730 U32 const llen = (U32)(ip - anchor); 731 U32 const mlen = opt[pos].mlen; 732 U32 const offset = opt[pos].off; 733 if (mlen == 1) { ip++; pos++; continue; } /* literal position => move on */ 734 pos += mlen; ip += mlen; 735 736 /* repcodes update : like ZSTD_updateRep(), but update in place */ 737 if (offset >= ZSTD_REP_NUM) { /* full offset */ 738 rep[2] = rep[1]; 739 rep[1] = rep[0]; 740 rep[0] = offset - ZSTD_REP_MOVE; 741 } else { /* repcode */ 742 U32 const repCode = offset + (llen==0); 743 if (repCode) { /* note : if repCode==0, no change */ 744 U32 const currentOffset = (repCode==ZSTD_REP_NUM) ? (rep[0] - 1) : rep[repCode]; 745 if (repCode >= 2) rep[2] = rep[1]; 746 rep[1] = rep[0]; 747 rep[0] = currentOffset; 748 } 749 } 750 751 ZSTD_updateStats(optStatePtr, llen, anchor, offset, mlen); 752 ZSTD_storeSeq(seqStorePtr, llen, anchor, offset, mlen-MINMATCH); 753 anchor = ip; 754 } } 755 ZSTD_setLog2Prices(optStatePtr); 756 } /* while (ip < ilimit) */ 757 758 /* Save reps for next block */ 759 { int i; for (i=0; i<ZSTD_REP_NUM; i++) seqStorePtr->repToConfirm[i] = rep[i]; } 760 761 /* Return the last literals size */ 762 return iend - anchor; 763 } 764 765 766 size_t ZSTD_compressBlock_btopt(ZSTD_CCtx* ctx, const void* src, size_t srcSize) 767 { 768 DEBUGLOG(5, "ZSTD_compressBlock_btopt"); 769 return ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 0 /*optLevel*/, 0 /*extDict*/); 770 } 771 772 size_t ZSTD_compressBlock_btultra(ZSTD_CCtx* ctx, const void* src, size_t srcSize) 773 { 774 return ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 2 /*optLevel*/, 0 /*extDict*/); 775 } 776 777 size_t ZSTD_compressBlock_btopt_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize) 778 { 779 return ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 0 /*optLevel*/, 1 /*extDict*/); 780 } 781 782 size_t ZSTD_compressBlock_btultra_extDict(ZSTD_CCtx* ctx, const void* src, size_t srcSize) 783 { 784 return ZSTD_compressBlock_opt_generic(ctx, src, srcSize, 2 /*optLevel*/, 1 /*extDict*/); 785 } 786