1 /* 2 * Copyright (c) Yann Collet, Facebook, Inc. 3 * All rights reserved. 4 * 5 * This source code is licensed under both the BSD-style license (found in the 6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found 7 * in the COPYING file in the root directory of this source tree). 8 * You may select, at your option, one of the above-listed licenses. 9 */ 10 11 #include "zstd_compress_internal.h" 12 #include "zstd_lazy.h" 13 14 15 /*-************************************* 16 * Binary Tree search 17 ***************************************/ 18 19 static void 20 ZSTD_updateDUBT(ZSTD_matchState_t* ms, 21 const BYTE* ip, const BYTE* iend, 22 U32 mls) 23 { 24 const ZSTD_compressionParameters* const cParams = &ms->cParams; 25 U32* const hashTable = ms->hashTable; 26 U32 const hashLog = cParams->hashLog; 27 28 U32* const bt = ms->chainTable; 29 U32 const btLog = cParams->chainLog - 1; 30 U32 const btMask = (1 << btLog) - 1; 31 32 const BYTE* const base = ms->window.base; 33 U32 const target = (U32)(ip - base); 34 U32 idx = ms->nextToUpdate; 35 36 if (idx != target) 37 DEBUGLOG(7, "ZSTD_updateDUBT, from %u to %u (dictLimit:%u)", 38 idx, target, ms->window.dictLimit); 39 assert(ip + 8 <= iend); /* condition for ZSTD_hashPtr */ 40 (void)iend; 41 42 assert(idx >= ms->window.dictLimit); /* condition for valid base+idx */ 43 for ( ; idx < target ; idx++) { 44 size_t const h = ZSTD_hashPtr(base + idx, hashLog, mls); /* assumption : ip + 8 <= iend */ 45 U32 const matchIndex = hashTable[h]; 46 47 U32* const nextCandidatePtr = bt + 2*(idx&btMask); 48 U32* const sortMarkPtr = nextCandidatePtr + 1; 49 50 DEBUGLOG(8, "ZSTD_updateDUBT: insert %u", idx); 51 hashTable[h] = idx; /* Update Hash Table */ 52 *nextCandidatePtr = matchIndex; /* update BT like a chain */ 53 *sortMarkPtr = ZSTD_DUBT_UNSORTED_MARK; 54 } 55 ms->nextToUpdate = target; 56 } 57 58 59 /* ZSTD_insertDUBT1() : 60 * sort one already inserted but unsorted position 61 * assumption : curr >= btlow == (curr - btmask) 62 * doesn't fail */ 63 static void 64 ZSTD_insertDUBT1(const ZSTD_matchState_t* ms, 65 U32 curr, const BYTE* inputEnd, 66 U32 nbCompares, U32 btLow, 67 const ZSTD_dictMode_e dictMode) 68 { 69 const ZSTD_compressionParameters* const cParams = &ms->cParams; 70 U32* const bt = ms->chainTable; 71 U32 const btLog = cParams->chainLog - 1; 72 U32 const btMask = (1 << btLog) - 1; 73 size_t commonLengthSmaller=0, commonLengthLarger=0; 74 const BYTE* const base = ms->window.base; 75 const BYTE* const dictBase = ms->window.dictBase; 76 const U32 dictLimit = ms->window.dictLimit; 77 const BYTE* const ip = (curr>=dictLimit) ? base + curr : dictBase + curr; 78 const BYTE* const iend = (curr>=dictLimit) ? inputEnd : dictBase + dictLimit; 79 const BYTE* const dictEnd = dictBase + dictLimit; 80 const BYTE* const prefixStart = base + dictLimit; 81 const BYTE* match; 82 U32* smallerPtr = bt + 2*(curr&btMask); 83 U32* largerPtr = smallerPtr + 1; 84 U32 matchIndex = *smallerPtr; /* this candidate is unsorted : next sorted candidate is reached through *smallerPtr, while *largerPtr contains previous unsorted candidate (which is already saved and can be overwritten) */ 85 U32 dummy32; /* to be nullified at the end */ 86 U32 const windowValid = ms->window.lowLimit; 87 U32 const maxDistance = 1U << cParams->windowLog; 88 U32 const windowLow = (curr - windowValid > maxDistance) ? curr - maxDistance : windowValid; 89 90 91 DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)", 92 curr, dictLimit, windowLow); 93 assert(curr >= btLow); 94 assert(ip < iend); /* condition for ZSTD_count */ 95 96 for (; nbCompares && (matchIndex > windowLow); --nbCompares) { 97 U32* const nextPtr = bt + 2*(matchIndex & btMask); 98 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 99 assert(matchIndex < curr); 100 /* note : all candidates are now supposed sorted, 101 * but it's still possible to have nextPtr[1] == ZSTD_DUBT_UNSORTED_MARK 102 * when a real index has the same value as ZSTD_DUBT_UNSORTED_MARK */ 103 104 if ( (dictMode != ZSTD_extDict) 105 || (matchIndex+matchLength >= dictLimit) /* both in current segment*/ 106 || (curr < dictLimit) /* both in extDict */) { 107 const BYTE* const mBase = ( (dictMode != ZSTD_extDict) 108 || (matchIndex+matchLength >= dictLimit)) ? 109 base : dictBase; 110 assert( (matchIndex+matchLength >= dictLimit) /* might be wrong if extDict is incorrectly set to 0 */ 111 || (curr < dictLimit) ); 112 match = mBase + matchIndex; 113 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); 114 } else { 115 match = dictBase + matchIndex; 116 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); 117 if (matchIndex+matchLength >= dictLimit) 118 match = base + matchIndex; /* preparation for next read of match[matchLength] */ 119 } 120 121 DEBUGLOG(8, "ZSTD_insertDUBT1: comparing %u with %u : found %u common bytes ", 122 curr, matchIndex, (U32)matchLength); 123 124 if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ 125 break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */ 126 } 127 128 if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */ 129 /* match is smaller than current */ 130 *smallerPtr = matchIndex; /* update smaller idx */ 131 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 132 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */ 133 DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is smaller : next => %u", 134 matchIndex, btLow, nextPtr[1]); 135 smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */ 136 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */ 137 } else { 138 /* match is larger than current */ 139 *largerPtr = matchIndex; 140 commonLengthLarger = matchLength; 141 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */ 142 DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is larger => %u", 143 matchIndex, btLow, nextPtr[0]); 144 largerPtr = nextPtr; 145 matchIndex = nextPtr[0]; 146 } } 147 148 *smallerPtr = *largerPtr = 0; 149 } 150 151 152 static size_t 153 ZSTD_DUBT_findBetterDictMatch ( 154 const ZSTD_matchState_t* ms, 155 const BYTE* const ip, const BYTE* const iend, 156 size_t* offsetPtr, 157 size_t bestLength, 158 U32 nbCompares, 159 U32 const mls, 160 const ZSTD_dictMode_e dictMode) 161 { 162 const ZSTD_matchState_t * const dms = ms->dictMatchState; 163 const ZSTD_compressionParameters* const dmsCParams = &dms->cParams; 164 const U32 * const dictHashTable = dms->hashTable; 165 U32 const hashLog = dmsCParams->hashLog; 166 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 167 U32 dictMatchIndex = dictHashTable[h]; 168 169 const BYTE* const base = ms->window.base; 170 const BYTE* const prefixStart = base + ms->window.dictLimit; 171 U32 const curr = (U32)(ip-base); 172 const BYTE* const dictBase = dms->window.base; 173 const BYTE* const dictEnd = dms->window.nextSrc; 174 U32 const dictHighLimit = (U32)(dms->window.nextSrc - dms->window.base); 175 U32 const dictLowLimit = dms->window.lowLimit; 176 U32 const dictIndexDelta = ms->window.lowLimit - dictHighLimit; 177 178 U32* const dictBt = dms->chainTable; 179 U32 const btLog = dmsCParams->chainLog - 1; 180 U32 const btMask = (1 << btLog) - 1; 181 U32 const btLow = (btMask >= dictHighLimit - dictLowLimit) ? dictLowLimit : dictHighLimit - btMask; 182 183 size_t commonLengthSmaller=0, commonLengthLarger=0; 184 185 (void)dictMode; 186 assert(dictMode == ZSTD_dictMatchState); 187 188 for (; nbCompares && (dictMatchIndex > dictLowLimit); --nbCompares) { 189 U32* const nextPtr = dictBt + 2*(dictMatchIndex & btMask); 190 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 191 const BYTE* match = dictBase + dictMatchIndex; 192 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); 193 if (dictMatchIndex+matchLength >= dictHighLimit) 194 match = base + dictMatchIndex + dictIndexDelta; /* to prepare for next usage of match[matchLength] */ 195 196 if (matchLength > bestLength) { 197 U32 matchIndex = dictMatchIndex + dictIndexDelta; 198 if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) ) { 199 DEBUGLOG(9, "ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u)", 200 curr, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, STORE_OFFSET(curr - matchIndex), dictMatchIndex, matchIndex); 201 bestLength = matchLength, *offsetPtr = STORE_OFFSET(curr - matchIndex); 202 } 203 if (ip+matchLength == iend) { /* reached end of input : ip[matchLength] is not valid, no way to know if it's larger or smaller than match */ 204 break; /* drop, to guarantee consistency (miss a little bit of compression) */ 205 } 206 } 207 208 if (match[matchLength] < ip[matchLength]) { 209 if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */ 210 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 211 dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ 212 } else { 213 /* match is larger than current */ 214 if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */ 215 commonLengthLarger = matchLength; 216 dictMatchIndex = nextPtr[0]; 217 } 218 } 219 220 if (bestLength >= MINMATCH) { 221 U32 const mIndex = curr - (U32)STORED_OFFSET(*offsetPtr); (void)mIndex; 222 DEBUGLOG(8, "ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)", 223 curr, (U32)bestLength, (U32)*offsetPtr, mIndex); 224 } 225 return bestLength; 226 227 } 228 229 230 static size_t 231 ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms, 232 const BYTE* const ip, const BYTE* const iend, 233 size_t* offsetPtr, 234 U32 const mls, 235 const ZSTD_dictMode_e dictMode) 236 { 237 const ZSTD_compressionParameters* const cParams = &ms->cParams; 238 U32* const hashTable = ms->hashTable; 239 U32 const hashLog = cParams->hashLog; 240 size_t const h = ZSTD_hashPtr(ip, hashLog, mls); 241 U32 matchIndex = hashTable[h]; 242 243 const BYTE* const base = ms->window.base; 244 U32 const curr = (U32)(ip-base); 245 U32 const windowLow = ZSTD_getLowestMatchIndex(ms, curr, cParams->windowLog); 246 247 U32* const bt = ms->chainTable; 248 U32 const btLog = cParams->chainLog - 1; 249 U32 const btMask = (1 << btLog) - 1; 250 U32 const btLow = (btMask >= curr) ? 0 : curr - btMask; 251 U32 const unsortLimit = MAX(btLow, windowLow); 252 253 U32* nextCandidate = bt + 2*(matchIndex&btMask); 254 U32* unsortedMark = bt + 2*(matchIndex&btMask) + 1; 255 U32 nbCompares = 1U << cParams->searchLog; 256 U32 nbCandidates = nbCompares; 257 U32 previousCandidate = 0; 258 259 DEBUGLOG(7, "ZSTD_DUBT_findBestMatch (%u) ", curr); 260 assert(ip <= iend-8); /* required for h calculation */ 261 assert(dictMode != ZSTD_dedicatedDictSearch); 262 263 /* reach end of unsorted candidates list */ 264 while ( (matchIndex > unsortLimit) 265 && (*unsortedMark == ZSTD_DUBT_UNSORTED_MARK) 266 && (nbCandidates > 1) ) { 267 DEBUGLOG(8, "ZSTD_DUBT_findBestMatch: candidate %u is unsorted", 268 matchIndex); 269 *unsortedMark = previousCandidate; /* the unsortedMark becomes a reversed chain, to move up back to original position */ 270 previousCandidate = matchIndex; 271 matchIndex = *nextCandidate; 272 nextCandidate = bt + 2*(matchIndex&btMask); 273 unsortedMark = bt + 2*(matchIndex&btMask) + 1; 274 nbCandidates --; 275 } 276 277 /* nullify last candidate if it's still unsorted 278 * simplification, detrimental to compression ratio, beneficial for speed */ 279 if ( (matchIndex > unsortLimit) 280 && (*unsortedMark==ZSTD_DUBT_UNSORTED_MARK) ) { 281 DEBUGLOG(7, "ZSTD_DUBT_findBestMatch: nullify last unsorted candidate %u", 282 matchIndex); 283 *nextCandidate = *unsortedMark = 0; 284 } 285 286 /* batch sort stacked candidates */ 287 matchIndex = previousCandidate; 288 while (matchIndex) { /* will end on matchIndex == 0 */ 289 U32* const nextCandidateIdxPtr = bt + 2*(matchIndex&btMask) + 1; 290 U32 const nextCandidateIdx = *nextCandidateIdxPtr; 291 ZSTD_insertDUBT1(ms, matchIndex, iend, 292 nbCandidates, unsortLimit, dictMode); 293 matchIndex = nextCandidateIdx; 294 nbCandidates++; 295 } 296 297 /* find longest match */ 298 { size_t commonLengthSmaller = 0, commonLengthLarger = 0; 299 const BYTE* const dictBase = ms->window.dictBase; 300 const U32 dictLimit = ms->window.dictLimit; 301 const BYTE* const dictEnd = dictBase + dictLimit; 302 const BYTE* const prefixStart = base + dictLimit; 303 U32* smallerPtr = bt + 2*(curr&btMask); 304 U32* largerPtr = bt + 2*(curr&btMask) + 1; 305 U32 matchEndIdx = curr + 8 + 1; 306 U32 dummy32; /* to be nullified at the end */ 307 size_t bestLength = 0; 308 309 matchIndex = hashTable[h]; 310 hashTable[h] = curr; /* Update Hash Table */ 311 312 for (; nbCompares && (matchIndex > windowLow); --nbCompares) { 313 U32* const nextPtr = bt + 2*(matchIndex & btMask); 314 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ 315 const BYTE* match; 316 317 if ((dictMode != ZSTD_extDict) || (matchIndex+matchLength >= dictLimit)) { 318 match = base + matchIndex; 319 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); 320 } else { 321 match = dictBase + matchIndex; 322 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); 323 if (matchIndex+matchLength >= dictLimit) 324 match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ 325 } 326 327 if (matchLength > bestLength) { 328 if (matchLength > matchEndIdx - matchIndex) 329 matchEndIdx = matchIndex + (U32)matchLength; 330 if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) ) 331 bestLength = matchLength, *offsetPtr = STORE_OFFSET(curr - matchIndex); 332 if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ 333 if (dictMode == ZSTD_dictMatchState) { 334 nbCompares = 0; /* in addition to avoiding checking any 335 * further in this loop, make sure we 336 * skip checking in the dictionary. */ 337 } 338 break; /* drop, to guarantee consistency (miss a little bit of compression) */ 339 } 340 } 341 342 if (match[matchLength] < ip[matchLength]) { 343 /* match is smaller than current */ 344 *smallerPtr = matchIndex; /* update smaller idx */ 345 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ 346 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 347 smallerPtr = nextPtr+1; /* new "smaller" => larger of match */ 348 matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ 349 } else { 350 /* match is larger than current */ 351 *largerPtr = matchIndex; 352 commonLengthLarger = matchLength; 353 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ 354 largerPtr = nextPtr; 355 matchIndex = nextPtr[0]; 356 } } 357 358 *smallerPtr = *largerPtr = 0; 359 360 assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ 361 if (dictMode == ZSTD_dictMatchState && nbCompares) { 362 bestLength = ZSTD_DUBT_findBetterDictMatch( 363 ms, ip, iend, 364 offsetPtr, bestLength, nbCompares, 365 mls, dictMode); 366 } 367 368 assert(matchEndIdx > curr+8); /* ensure nextToUpdate is increased */ 369 ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ 370 if (bestLength >= MINMATCH) { 371 U32 const mIndex = curr - (U32)STORED_OFFSET(*offsetPtr); (void)mIndex; 372 DEBUGLOG(8, "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)", 373 curr, (U32)bestLength, (U32)*offsetPtr, mIndex); 374 } 375 return bestLength; 376 } 377 } 378 379 380 /* ZSTD_BtFindBestMatch() : Tree updater, providing best match */ 381 FORCE_INLINE_TEMPLATE size_t 382 ZSTD_BtFindBestMatch( ZSTD_matchState_t* ms, 383 const BYTE* const ip, const BYTE* const iLimit, 384 size_t* offsetPtr, 385 const U32 mls /* template */, 386 const ZSTD_dictMode_e dictMode) 387 { 388 DEBUGLOG(7, "ZSTD_BtFindBestMatch"); 389 if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */ 390 ZSTD_updateDUBT(ms, ip, iLimit, mls); 391 return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offsetPtr, mls, dictMode); 392 } 393 394 /* ********************************* 395 * Dedicated dict search 396 ***********************************/ 397 398 void ZSTD_dedicatedDictSearch_lazy_loadDictionary(ZSTD_matchState_t* ms, const BYTE* const ip) 399 { 400 const BYTE* const base = ms->window.base; 401 U32 const target = (U32)(ip - base); 402 U32* const hashTable = ms->hashTable; 403 U32* const chainTable = ms->chainTable; 404 U32 const chainSize = 1 << ms->cParams.chainLog; 405 U32 idx = ms->nextToUpdate; 406 U32 const minChain = chainSize < target - idx ? target - chainSize : idx; 407 U32 const bucketSize = 1 << ZSTD_LAZY_DDSS_BUCKET_LOG; 408 U32 const cacheSize = bucketSize - 1; 409 U32 const chainAttempts = (1 << ms->cParams.searchLog) - cacheSize; 410 U32 const chainLimit = chainAttempts > 255 ? 255 : chainAttempts; 411 412 /* We know the hashtable is oversized by a factor of `bucketSize`. 413 * We are going to temporarily pretend `bucketSize == 1`, keeping only a 414 * single entry. We will use the rest of the space to construct a temporary 415 * chaintable. 416 */ 417 U32 const hashLog = ms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG; 418 U32* const tmpHashTable = hashTable; 419 U32* const tmpChainTable = hashTable + ((size_t)1 << hashLog); 420 U32 const tmpChainSize = (U32)((1 << ZSTD_LAZY_DDSS_BUCKET_LOG) - 1) << hashLog; 421 U32 const tmpMinChain = tmpChainSize < target ? target - tmpChainSize : idx; 422 U32 hashIdx; 423 424 assert(ms->cParams.chainLog <= 24); 425 assert(ms->cParams.hashLog > ms->cParams.chainLog); 426 assert(idx != 0); 427 assert(tmpMinChain <= minChain); 428 429 /* fill conventional hash table and conventional chain table */ 430 for ( ; idx < target; idx++) { 431 U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch); 432 if (idx >= tmpMinChain) { 433 tmpChainTable[idx - tmpMinChain] = hashTable[h]; 434 } 435 tmpHashTable[h] = idx; 436 } 437 438 /* sort chains into ddss chain table */ 439 { 440 U32 chainPos = 0; 441 for (hashIdx = 0; hashIdx < (1U << hashLog); hashIdx++) { 442 U32 count; 443 U32 countBeyondMinChain = 0; 444 U32 i = tmpHashTable[hashIdx]; 445 for (count = 0; i >= tmpMinChain && count < cacheSize; count++) { 446 /* skip through the chain to the first position that won't be 447 * in the hash cache bucket */ 448 if (i < minChain) { 449 countBeyondMinChain++; 450 } 451 i = tmpChainTable[i - tmpMinChain]; 452 } 453 if (count == cacheSize) { 454 for (count = 0; count < chainLimit;) { 455 if (i < minChain) { 456 if (!i || ++countBeyondMinChain > cacheSize) { 457 /* only allow pulling `cacheSize` number of entries 458 * into the cache or chainTable beyond `minChain`, 459 * to replace the entries pulled out of the 460 * chainTable into the cache. This lets us reach 461 * back further without increasing the total number 462 * of entries in the chainTable, guaranteeing the 463 * DDSS chain table will fit into the space 464 * allocated for the regular one. */ 465 break; 466 } 467 } 468 chainTable[chainPos++] = i; 469 count++; 470 if (i < tmpMinChain) { 471 break; 472 } 473 i = tmpChainTable[i - tmpMinChain]; 474 } 475 } else { 476 count = 0; 477 } 478 if (count) { 479 tmpHashTable[hashIdx] = ((chainPos - count) << 8) + count; 480 } else { 481 tmpHashTable[hashIdx] = 0; 482 } 483 } 484 assert(chainPos <= chainSize); /* I believe this is guaranteed... */ 485 } 486 487 /* move chain pointers into the last entry of each hash bucket */ 488 for (hashIdx = (1 << hashLog); hashIdx; ) { 489 U32 const bucketIdx = --hashIdx << ZSTD_LAZY_DDSS_BUCKET_LOG; 490 U32 const chainPackedPointer = tmpHashTable[hashIdx]; 491 U32 i; 492 for (i = 0; i < cacheSize; i++) { 493 hashTable[bucketIdx + i] = 0; 494 } 495 hashTable[bucketIdx + bucketSize - 1] = chainPackedPointer; 496 } 497 498 /* fill the buckets of the hash table */ 499 for (idx = ms->nextToUpdate; idx < target; idx++) { 500 U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch) 501 << ZSTD_LAZY_DDSS_BUCKET_LOG; 502 U32 i; 503 /* Shift hash cache down 1. */ 504 for (i = cacheSize - 1; i; i--) 505 hashTable[h + i] = hashTable[h + i - 1]; 506 hashTable[h] = idx; 507 } 508 509 ms->nextToUpdate = target; 510 } 511 512 /* Returns the longest match length found in the dedicated dict search structure. 513 * If none are longer than the argument ml, then ml will be returned. 514 */ 515 FORCE_INLINE_TEMPLATE 516 size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nbAttempts, 517 const ZSTD_matchState_t* const dms, 518 const BYTE* const ip, const BYTE* const iLimit, 519 const BYTE* const prefixStart, const U32 curr, 520 const U32 dictLimit, const size_t ddsIdx) { 521 const U32 ddsLowestIndex = dms->window.dictLimit; 522 const BYTE* const ddsBase = dms->window.base; 523 const BYTE* const ddsEnd = dms->window.nextSrc; 524 const U32 ddsSize = (U32)(ddsEnd - ddsBase); 525 const U32 ddsIndexDelta = dictLimit - ddsSize; 526 const U32 bucketSize = (1 << ZSTD_LAZY_DDSS_BUCKET_LOG); 527 const U32 bucketLimit = nbAttempts < bucketSize - 1 ? nbAttempts : bucketSize - 1; 528 U32 ddsAttempt; 529 U32 matchIndex; 530 531 for (ddsAttempt = 0; ddsAttempt < bucketSize - 1; ddsAttempt++) { 532 PREFETCH_L1(ddsBase + dms->hashTable[ddsIdx + ddsAttempt]); 533 } 534 535 { 536 U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1]; 537 U32 const chainIndex = chainPackedPointer >> 8; 538 539 PREFETCH_L1(&dms->chainTable[chainIndex]); 540 } 541 542 for (ddsAttempt = 0; ddsAttempt < bucketLimit; ddsAttempt++) { 543 size_t currentMl=0; 544 const BYTE* match; 545 matchIndex = dms->hashTable[ddsIdx + ddsAttempt]; 546 match = ddsBase + matchIndex; 547 548 if (!matchIndex) { 549 return ml; 550 } 551 552 /* guaranteed by table construction */ 553 (void)ddsLowestIndex; 554 assert(matchIndex >= ddsLowestIndex); 555 assert(match+4 <= ddsEnd); 556 if (MEM_read32(match) == MEM_read32(ip)) { 557 /* assumption : matchIndex <= dictLimit-4 (by table construction) */ 558 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4; 559 } 560 561 /* save best solution */ 562 if (currentMl > ml) { 563 ml = currentMl; 564 *offsetPtr = STORE_OFFSET(curr - (matchIndex + ddsIndexDelta)); 565 if (ip+currentMl == iLimit) { 566 /* best possible, avoids read overflow on next attempt */ 567 return ml; 568 } 569 } 570 } 571 572 { 573 U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1]; 574 U32 chainIndex = chainPackedPointer >> 8; 575 U32 const chainLength = chainPackedPointer & 0xFF; 576 U32 const chainAttempts = nbAttempts - ddsAttempt; 577 U32 const chainLimit = chainAttempts > chainLength ? chainLength : chainAttempts; 578 U32 chainAttempt; 579 580 for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++) { 581 PREFETCH_L1(ddsBase + dms->chainTable[chainIndex + chainAttempt]); 582 } 583 584 for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++, chainIndex++) { 585 size_t currentMl=0; 586 const BYTE* match; 587 matchIndex = dms->chainTable[chainIndex]; 588 match = ddsBase + matchIndex; 589 590 /* guaranteed by table construction */ 591 assert(matchIndex >= ddsLowestIndex); 592 assert(match+4 <= ddsEnd); 593 if (MEM_read32(match) == MEM_read32(ip)) { 594 /* assumption : matchIndex <= dictLimit-4 (by table construction) */ 595 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4; 596 } 597 598 /* save best solution */ 599 if (currentMl > ml) { 600 ml = currentMl; 601 *offsetPtr = STORE_OFFSET(curr - (matchIndex + ddsIndexDelta)); 602 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ 603 } 604 } 605 } 606 return ml; 607 } 608 609 610 /* ********************************* 611 * Hash Chain 612 ***********************************/ 613 #define NEXT_IN_CHAIN(d, mask) chainTable[(d) & (mask)] 614 615 /* Update chains up to ip (excluded) 616 Assumption : always within prefix (i.e. not within extDict) */ 617 FORCE_INLINE_TEMPLATE U32 ZSTD_insertAndFindFirstIndex_internal( 618 ZSTD_matchState_t* ms, 619 const ZSTD_compressionParameters* const cParams, 620 const BYTE* ip, U32 const mls) 621 { 622 U32* const hashTable = ms->hashTable; 623 const U32 hashLog = cParams->hashLog; 624 U32* const chainTable = ms->chainTable; 625 const U32 chainMask = (1 << cParams->chainLog) - 1; 626 const BYTE* const base = ms->window.base; 627 const U32 target = (U32)(ip - base); 628 U32 idx = ms->nextToUpdate; 629 630 while(idx < target) { /* catch up */ 631 size_t const h = ZSTD_hashPtr(base+idx, hashLog, mls); 632 NEXT_IN_CHAIN(idx, chainMask) = hashTable[h]; 633 hashTable[h] = idx; 634 idx++; 635 } 636 637 ms->nextToUpdate = target; 638 return hashTable[ZSTD_hashPtr(ip, hashLog, mls)]; 639 } 640 641 U32 ZSTD_insertAndFindFirstIndex(ZSTD_matchState_t* ms, const BYTE* ip) { 642 const ZSTD_compressionParameters* const cParams = &ms->cParams; 643 return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, ms->cParams.minMatch); 644 } 645 646 /* inlining is important to hardwire a hot branch (template emulation) */ 647 FORCE_INLINE_TEMPLATE 648 size_t ZSTD_HcFindBestMatch( 649 ZSTD_matchState_t* ms, 650 const BYTE* const ip, const BYTE* const iLimit, 651 size_t* offsetPtr, 652 const U32 mls, const ZSTD_dictMode_e dictMode) 653 { 654 const ZSTD_compressionParameters* const cParams = &ms->cParams; 655 U32* const chainTable = ms->chainTable; 656 const U32 chainSize = (1 << cParams->chainLog); 657 const U32 chainMask = chainSize-1; 658 const BYTE* const base = ms->window.base; 659 const BYTE* const dictBase = ms->window.dictBase; 660 const U32 dictLimit = ms->window.dictLimit; 661 const BYTE* const prefixStart = base + dictLimit; 662 const BYTE* const dictEnd = dictBase + dictLimit; 663 const U32 curr = (U32)(ip-base); 664 const U32 maxDistance = 1U << cParams->windowLog; 665 const U32 lowestValid = ms->window.lowLimit; 666 const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid; 667 const U32 isDictionary = (ms->loadedDictEnd != 0); 668 const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance; 669 const U32 minChain = curr > chainSize ? curr - chainSize : 0; 670 U32 nbAttempts = 1U << cParams->searchLog; 671 size_t ml=4-1; 672 673 const ZSTD_matchState_t* const dms = ms->dictMatchState; 674 const U32 ddsHashLog = dictMode == ZSTD_dedicatedDictSearch 675 ? dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG : 0; 676 const size_t ddsIdx = dictMode == ZSTD_dedicatedDictSearch 677 ? ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG : 0; 678 679 U32 matchIndex; 680 681 if (dictMode == ZSTD_dedicatedDictSearch) { 682 const U32* entry = &dms->hashTable[ddsIdx]; 683 PREFETCH_L1(entry); 684 } 685 686 /* HC4 match finder */ 687 matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls); 688 689 for ( ; (matchIndex>=lowLimit) & (nbAttempts>0) ; nbAttempts--) { 690 size_t currentMl=0; 691 if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { 692 const BYTE* const match = base + matchIndex; 693 assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */ 694 if (match[ml] == ip[ml]) /* potentially better */ 695 currentMl = ZSTD_count(ip, match, iLimit); 696 } else { 697 const BYTE* const match = dictBase + matchIndex; 698 assert(match+4 <= dictEnd); 699 if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ 700 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4; 701 } 702 703 /* save best solution */ 704 if (currentMl > ml) { 705 ml = currentMl; 706 *offsetPtr = STORE_OFFSET(curr - matchIndex); 707 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ 708 } 709 710 if (matchIndex <= minChain) break; 711 matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask); 712 } 713 714 assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ 715 if (dictMode == ZSTD_dedicatedDictSearch) { 716 ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts, dms, 717 ip, iLimit, prefixStart, curr, dictLimit, ddsIdx); 718 } else if (dictMode == ZSTD_dictMatchState) { 719 const U32* const dmsChainTable = dms->chainTable; 720 const U32 dmsChainSize = (1 << dms->cParams.chainLog); 721 const U32 dmsChainMask = dmsChainSize - 1; 722 const U32 dmsLowestIndex = dms->window.dictLimit; 723 const BYTE* const dmsBase = dms->window.base; 724 const BYTE* const dmsEnd = dms->window.nextSrc; 725 const U32 dmsSize = (U32)(dmsEnd - dmsBase); 726 const U32 dmsIndexDelta = dictLimit - dmsSize; 727 const U32 dmsMinChain = dmsSize > dmsChainSize ? dmsSize - dmsChainSize : 0; 728 729 matchIndex = dms->hashTable[ZSTD_hashPtr(ip, dms->cParams.hashLog, mls)]; 730 731 for ( ; (matchIndex>=dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--) { 732 size_t currentMl=0; 733 const BYTE* const match = dmsBase + matchIndex; 734 assert(match+4 <= dmsEnd); 735 if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ 736 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4; 737 738 /* save best solution */ 739 if (currentMl > ml) { 740 ml = currentMl; 741 assert(curr > matchIndex + dmsIndexDelta); 742 *offsetPtr = STORE_OFFSET(curr - (matchIndex + dmsIndexDelta)); 743 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ 744 } 745 746 if (matchIndex <= dmsMinChain) break; 747 748 matchIndex = dmsChainTable[matchIndex & dmsChainMask]; 749 } 750 } 751 752 return ml; 753 } 754 755 /* ********************************* 756 * (SIMD) Row-based matchfinder 757 ***********************************/ 758 /* Constants for row-based hash */ 759 #define ZSTD_ROW_HASH_TAG_OFFSET 16 /* byte offset of hashes in the match state's tagTable from the beginning of a row */ 760 #define ZSTD_ROW_HASH_TAG_BITS 8 /* nb bits to use for the tag */ 761 #define ZSTD_ROW_HASH_TAG_MASK ((1u << ZSTD_ROW_HASH_TAG_BITS) - 1) 762 #define ZSTD_ROW_HASH_MAX_ENTRIES 64 /* absolute maximum number of entries per row, for all configurations */ 763 764 #define ZSTD_ROW_HASH_CACHE_MASK (ZSTD_ROW_HASH_CACHE_SIZE - 1) 765 766 typedef U64 ZSTD_VecMask; /* Clarifies when we are interacting with a U64 representing a mask of matches */ 767 768 /* ZSTD_VecMask_next(): 769 * Starting from the LSB, returns the idx of the next non-zero bit. 770 * Basically counting the nb of trailing zeroes. 771 */ 772 static U32 ZSTD_VecMask_next(ZSTD_VecMask val) { 773 assert(val != 0); 774 # if (defined(__GNUC__) && ((__GNUC__ > 3) || ((__GNUC__ == 3) && (__GNUC_MINOR__ >= 4)))) 775 if (sizeof(size_t) == 4) { 776 U32 mostSignificantWord = (U32)(val >> 32); 777 U32 leastSignificantWord = (U32)val; 778 if (leastSignificantWord == 0) { 779 return 32 + (U32)__builtin_ctz(mostSignificantWord); 780 } else { 781 return (U32)__builtin_ctz(leastSignificantWord); 782 } 783 } else { 784 return (U32)__builtin_ctzll(val); 785 } 786 # else 787 /* Software ctz version: http://aggregate.org/MAGIC/#Trailing%20Zero%20Count 788 * and: https://stackoverflow.com/questions/2709430/count-number-of-bits-in-a-64-bit-long-big-integer 789 */ 790 val = ~val & (val - 1ULL); /* Lowest set bit mask */ 791 val = val - ((val >> 1) & 0x5555555555555555); 792 val = (val & 0x3333333333333333ULL) + ((val >> 2) & 0x3333333333333333ULL); 793 return (U32)((((val + (val >> 4)) & 0xF0F0F0F0F0F0F0FULL) * 0x101010101010101ULL) >> 56); 794 # endif 795 } 796 797 /* ZSTD_rotateRight_*(): 798 * Rotates a bitfield to the right by "count" bits. 799 * https://en.wikipedia.org/w/index.php?title=Circular_shift&oldid=991635599#Implementing_circular_shifts 800 */ 801 FORCE_INLINE_TEMPLATE 802 U64 ZSTD_rotateRight_U64(U64 const value, U32 count) { 803 assert(count < 64); 804 count &= 0x3F; /* for fickle pattern recognition */ 805 return (value >> count) | (U64)(value << ((0U - count) & 0x3F)); 806 } 807 808 FORCE_INLINE_TEMPLATE 809 U32 ZSTD_rotateRight_U32(U32 const value, U32 count) { 810 assert(count < 32); 811 count &= 0x1F; /* for fickle pattern recognition */ 812 return (value >> count) | (U32)(value << ((0U - count) & 0x1F)); 813 } 814 815 FORCE_INLINE_TEMPLATE 816 U16 ZSTD_rotateRight_U16(U16 const value, U32 count) { 817 assert(count < 16); 818 count &= 0x0F; /* for fickle pattern recognition */ 819 return (value >> count) | (U16)(value << ((0U - count) & 0x0F)); 820 } 821 822 /* ZSTD_row_nextIndex(): 823 * Returns the next index to insert at within a tagTable row, and updates the "head" 824 * value to reflect the update. Essentially cycles backwards from [0, {entries per row}) 825 */ 826 FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextIndex(BYTE* const tagRow, U32 const rowMask) { 827 U32 const next = (*tagRow - 1) & rowMask; 828 *tagRow = (BYTE)next; 829 return next; 830 } 831 832 /* ZSTD_isAligned(): 833 * Checks that a pointer is aligned to "align" bytes which must be a power of 2. 834 */ 835 MEM_STATIC int ZSTD_isAligned(void const* ptr, size_t align) { 836 assert((align & (align - 1)) == 0); 837 return (((size_t)ptr) & (align - 1)) == 0; 838 } 839 840 /* ZSTD_row_prefetch(): 841 * Performs prefetching for the hashTable and tagTable at a given row. 842 */ 843 FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, U16 const* tagTable, U32 const relRow, U32 const rowLog) { 844 PREFETCH_L1(hashTable + relRow); 845 if (rowLog >= 5) { 846 PREFETCH_L1(hashTable + relRow + 16); 847 /* Note: prefetching more of the hash table does not appear to be beneficial for 128-entry rows */ 848 } 849 PREFETCH_L1(tagTable + relRow); 850 if (rowLog == 6) { 851 PREFETCH_L1(tagTable + relRow + 32); 852 } 853 assert(rowLog == 4 || rowLog == 5 || rowLog == 6); 854 assert(ZSTD_isAligned(hashTable + relRow, 64)); /* prefetched hash row always 64-byte aligned */ 855 assert(ZSTD_isAligned(tagTable + relRow, (size_t)1 << rowLog)); /* prefetched tagRow sits on correct multiple of bytes (32,64,128) */ 856 } 857 858 /* ZSTD_row_fillHashCache(): 859 * Fill up the hash cache starting at idx, prefetching up to ZSTD_ROW_HASH_CACHE_SIZE entries, 860 * but not beyond iLimit. 861 */ 862 FORCE_INLINE_TEMPLATE void ZSTD_row_fillHashCache(ZSTD_matchState_t* ms, const BYTE* base, 863 U32 const rowLog, U32 const mls, 864 U32 idx, const BYTE* const iLimit) 865 { 866 U32 const* const hashTable = ms->hashTable; 867 U16 const* const tagTable = ms->tagTable; 868 U32 const hashLog = ms->rowHashLog; 869 U32 const maxElemsToPrefetch = (base + idx) > iLimit ? 0 : (U32)(iLimit - (base + idx) + 1); 870 U32 const lim = idx + MIN(ZSTD_ROW_HASH_CACHE_SIZE, maxElemsToPrefetch); 871 872 for (; idx < lim; ++idx) { 873 U32 const hash = (U32)ZSTD_hashPtr(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls); 874 U32 const row = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; 875 ZSTD_row_prefetch(hashTable, tagTable, row, rowLog); 876 ms->hashCache[idx & ZSTD_ROW_HASH_CACHE_MASK] = hash; 877 } 878 879 DEBUGLOG(6, "ZSTD_row_fillHashCache(): [%u %u %u %u %u %u %u %u]", ms->hashCache[0], ms->hashCache[1], 880 ms->hashCache[2], ms->hashCache[3], ms->hashCache[4], 881 ms->hashCache[5], ms->hashCache[6], ms->hashCache[7]); 882 } 883 884 /* ZSTD_row_nextCachedHash(): 885 * Returns the hash of base + idx, and replaces the hash in the hash cache with the byte at 886 * base + idx + ZSTD_ROW_HASH_CACHE_SIZE. Also prefetches the appropriate rows from hashTable and tagTable. 887 */ 888 FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextCachedHash(U32* cache, U32 const* hashTable, 889 U16 const* tagTable, BYTE const* base, 890 U32 idx, U32 const hashLog, 891 U32 const rowLog, U32 const mls) 892 { 893 U32 const newHash = (U32)ZSTD_hashPtr(base+idx+ZSTD_ROW_HASH_CACHE_SIZE, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls); 894 U32 const row = (newHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; 895 ZSTD_row_prefetch(hashTable, tagTable, row, rowLog); 896 { U32 const hash = cache[idx & ZSTD_ROW_HASH_CACHE_MASK]; 897 cache[idx & ZSTD_ROW_HASH_CACHE_MASK] = newHash; 898 return hash; 899 } 900 } 901 902 /* ZSTD_row_update_internalImpl(): 903 * Updates the hash table with positions starting from updateStartIdx until updateEndIdx. 904 */ 905 FORCE_INLINE_TEMPLATE void ZSTD_row_update_internalImpl(ZSTD_matchState_t* ms, 906 U32 updateStartIdx, U32 const updateEndIdx, 907 U32 const mls, U32 const rowLog, 908 U32 const rowMask, U32 const useCache) 909 { 910 U32* const hashTable = ms->hashTable; 911 U16* const tagTable = ms->tagTable; 912 U32 const hashLog = ms->rowHashLog; 913 const BYTE* const base = ms->window.base; 914 915 DEBUGLOG(6, "ZSTD_row_update_internalImpl(): updateStartIdx=%u, updateEndIdx=%u", updateStartIdx, updateEndIdx); 916 for (; updateStartIdx < updateEndIdx; ++updateStartIdx) { 917 U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, updateStartIdx, hashLog, rowLog, mls) 918 : (U32)ZSTD_hashPtr(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls); 919 U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; 920 U32* const row = hashTable + relRow; 921 BYTE* tagRow = (BYTE*)(tagTable + relRow); /* Though tagTable is laid out as a table of U16, each tag is only 1 byte. 922 Explicit cast allows us to get exact desired position within each row */ 923 U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask); 924 925 assert(hash == ZSTD_hashPtr(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls)); 926 ((BYTE*)tagRow)[pos + ZSTD_ROW_HASH_TAG_OFFSET] = hash & ZSTD_ROW_HASH_TAG_MASK; 927 row[pos] = updateStartIdx; 928 } 929 } 930 931 /* ZSTD_row_update_internal(): 932 * Inserts the byte at ip into the appropriate position in the hash table, and updates ms->nextToUpdate. 933 * Skips sections of long matches as is necessary. 934 */ 935 FORCE_INLINE_TEMPLATE void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const BYTE* ip, 936 U32 const mls, U32 const rowLog, 937 U32 const rowMask, U32 const useCache) 938 { 939 U32 idx = ms->nextToUpdate; 940 const BYTE* const base = ms->window.base; 941 const U32 target = (U32)(ip - base); 942 const U32 kSkipThreshold = 384; 943 const U32 kMaxMatchStartPositionsToUpdate = 96; 944 const U32 kMaxMatchEndPositionsToUpdate = 32; 945 946 if (useCache) { 947 /* Only skip positions when using hash cache, i.e. 948 * if we are loading a dict, don't skip anything. 949 * If we decide to skip, then we only update a set number 950 * of positions at the beginning and end of the match. 951 */ 952 if (UNLIKELY(target - idx > kSkipThreshold)) { 953 U32 const bound = idx + kMaxMatchStartPositionsToUpdate; 954 ZSTD_row_update_internalImpl(ms, idx, bound, mls, rowLog, rowMask, useCache); 955 idx = target - kMaxMatchEndPositionsToUpdate; 956 ZSTD_row_fillHashCache(ms, base, rowLog, mls, idx, ip+1); 957 } 958 } 959 assert(target >= idx); 960 ZSTD_row_update_internalImpl(ms, idx, target, mls, rowLog, rowMask, useCache); 961 ms->nextToUpdate = target; 962 } 963 964 /* ZSTD_row_update(): 965 * External wrapper for ZSTD_row_update_internal(). Used for filling the hashtable during dictionary 966 * processing. 967 */ 968 void ZSTD_row_update(ZSTD_matchState_t* const ms, const BYTE* ip) { 969 const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); 970 const U32 rowMask = (1u << rowLog) - 1; 971 const U32 mls = MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */); 972 973 DEBUGLOG(5, "ZSTD_row_update(), rowLog=%u", rowLog); 974 ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 0 /* dont use cache */); 975 } 976 977 #if defined(ZSTD_ARCH_X86_SSE2) 978 FORCE_INLINE_TEMPLATE ZSTD_VecMask 979 ZSTD_row_getSSEMask(int nbChunks, const BYTE* const src, const BYTE tag, const U32 head) 980 { 981 const __m128i comparisonMask = _mm_set1_epi8((char)tag); 982 int matches[4] = {0}; 983 int i; 984 assert(nbChunks == 1 || nbChunks == 2 || nbChunks == 4); 985 for (i=0; i<nbChunks; i++) { 986 const __m128i chunk = _mm_loadu_si128((const __m128i*)(const void*)(src + 16*i)); 987 const __m128i equalMask = _mm_cmpeq_epi8(chunk, comparisonMask); 988 matches[i] = _mm_movemask_epi8(equalMask); 989 } 990 if (nbChunks == 1) return ZSTD_rotateRight_U16((U16)matches[0], head); 991 if (nbChunks == 2) return ZSTD_rotateRight_U32((U32)matches[1] << 16 | (U32)matches[0], head); 992 assert(nbChunks == 4); 993 return ZSTD_rotateRight_U64((U64)matches[3] << 48 | (U64)matches[2] << 32 | (U64)matches[1] << 16 | (U64)matches[0], head); 994 } 995 #endif 996 997 /* Returns a ZSTD_VecMask (U32) that has the nth bit set to 1 if the newly-computed "tag" matches 998 * the hash at the nth position in a row of the tagTable. 999 * Each row is a circular buffer beginning at the value of "head". So we must rotate the "matches" bitfield 1000 * to match up with the actual layout of the entries within the hashTable */ 1001 FORCE_INLINE_TEMPLATE ZSTD_VecMask 1002 ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 head, const U32 rowEntries) 1003 { 1004 const BYTE* const src = tagRow + ZSTD_ROW_HASH_TAG_OFFSET; 1005 assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64); 1006 assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES); 1007 1008 #if defined(ZSTD_ARCH_X86_SSE2) 1009 1010 return ZSTD_row_getSSEMask(rowEntries / 16, src, tag, head); 1011 1012 #else /* SW or NEON-LE */ 1013 1014 # if defined(ZSTD_ARCH_ARM_NEON) 1015 /* This NEON path only works for little endian - otherwise use SWAR below */ 1016 if (MEM_isLittleEndian()) { 1017 if (rowEntries == 16) { 1018 const uint8x16_t chunk = vld1q_u8(src); 1019 const uint16x8_t equalMask = vreinterpretq_u16_u8(vceqq_u8(chunk, vdupq_n_u8(tag))); 1020 const uint16x8_t t0 = vshlq_n_u16(equalMask, 7); 1021 const uint32x4_t t1 = vreinterpretq_u32_u16(vsriq_n_u16(t0, t0, 14)); 1022 const uint64x2_t t2 = vreinterpretq_u64_u32(vshrq_n_u32(t1, 14)); 1023 const uint8x16_t t3 = vreinterpretq_u8_u64(vsraq_n_u64(t2, t2, 28)); 1024 const U16 hi = (U16)vgetq_lane_u8(t3, 8); 1025 const U16 lo = (U16)vgetq_lane_u8(t3, 0); 1026 return ZSTD_rotateRight_U16((hi << 8) | lo, head); 1027 } else if (rowEntries == 32) { 1028 const uint16x8x2_t chunk = vld2q_u16((const U16*)(const void*)src); 1029 const uint8x16_t chunk0 = vreinterpretq_u8_u16(chunk.val[0]); 1030 const uint8x16_t chunk1 = vreinterpretq_u8_u16(chunk.val[1]); 1031 const uint8x16_t equalMask0 = vceqq_u8(chunk0, vdupq_n_u8(tag)); 1032 const uint8x16_t equalMask1 = vceqq_u8(chunk1, vdupq_n_u8(tag)); 1033 const int8x8_t pack0 = vqmovn_s16(vreinterpretq_s16_u8(equalMask0)); 1034 const int8x8_t pack1 = vqmovn_s16(vreinterpretq_s16_u8(equalMask1)); 1035 const uint8x8_t t0 = vreinterpret_u8_s8(pack0); 1036 const uint8x8_t t1 = vreinterpret_u8_s8(pack1); 1037 const uint8x8_t t2 = vsri_n_u8(t1, t0, 2); 1038 const uint8x8x2_t t3 = vuzp_u8(t2, t0); 1039 const uint8x8_t t4 = vsri_n_u8(t3.val[1], t3.val[0], 4); 1040 const U32 matches = vget_lane_u32(vreinterpret_u32_u8(t4), 0); 1041 return ZSTD_rotateRight_U32(matches, head); 1042 } else { /* rowEntries == 64 */ 1043 const uint8x16x4_t chunk = vld4q_u8(src); 1044 const uint8x16_t dup = vdupq_n_u8(tag); 1045 const uint8x16_t cmp0 = vceqq_u8(chunk.val[0], dup); 1046 const uint8x16_t cmp1 = vceqq_u8(chunk.val[1], dup); 1047 const uint8x16_t cmp2 = vceqq_u8(chunk.val[2], dup); 1048 const uint8x16_t cmp3 = vceqq_u8(chunk.val[3], dup); 1049 1050 const uint8x16_t t0 = vsriq_n_u8(cmp1, cmp0, 1); 1051 const uint8x16_t t1 = vsriq_n_u8(cmp3, cmp2, 1); 1052 const uint8x16_t t2 = vsriq_n_u8(t1, t0, 2); 1053 const uint8x16_t t3 = vsriq_n_u8(t2, t2, 4); 1054 const uint8x8_t t4 = vshrn_n_u16(vreinterpretq_u16_u8(t3), 4); 1055 const U64 matches = vget_lane_u64(vreinterpret_u64_u8(t4), 0); 1056 return ZSTD_rotateRight_U64(matches, head); 1057 } 1058 } 1059 # endif /* ZSTD_ARCH_ARM_NEON */ 1060 /* SWAR */ 1061 { const size_t chunkSize = sizeof(size_t); 1062 const size_t shiftAmount = ((chunkSize * 8) - chunkSize); 1063 const size_t xFF = ~((size_t)0); 1064 const size_t x01 = xFF / 0xFF; 1065 const size_t x80 = x01 << 7; 1066 const size_t splatChar = tag * x01; 1067 ZSTD_VecMask matches = 0; 1068 int i = rowEntries - chunkSize; 1069 assert((sizeof(size_t) == 4) || (sizeof(size_t) == 8)); 1070 if (MEM_isLittleEndian()) { /* runtime check so have two loops */ 1071 const size_t extractMagic = (xFF / 0x7F) >> chunkSize; 1072 do { 1073 size_t chunk = MEM_readST(&src[i]); 1074 chunk ^= splatChar; 1075 chunk = (((chunk | x80) - x01) | chunk) & x80; 1076 matches <<= chunkSize; 1077 matches |= (chunk * extractMagic) >> shiftAmount; 1078 i -= chunkSize; 1079 } while (i >= 0); 1080 } else { /* big endian: reverse bits during extraction */ 1081 const size_t msb = xFF ^ (xFF >> 1); 1082 const size_t extractMagic = (msb / 0x1FF) | msb; 1083 do { 1084 size_t chunk = MEM_readST(&src[i]); 1085 chunk ^= splatChar; 1086 chunk = (((chunk | x80) - x01) | chunk) & x80; 1087 matches <<= chunkSize; 1088 matches |= ((chunk >> 7) * extractMagic) >> shiftAmount; 1089 i -= chunkSize; 1090 } while (i >= 0); 1091 } 1092 matches = ~matches; 1093 if (rowEntries == 16) { 1094 return ZSTD_rotateRight_U16((U16)matches, head); 1095 } else if (rowEntries == 32) { 1096 return ZSTD_rotateRight_U32((U32)matches, head); 1097 } else { 1098 return ZSTD_rotateRight_U64((U64)matches, head); 1099 } 1100 } 1101 #endif 1102 } 1103 1104 /* The high-level approach of the SIMD row based match finder is as follows: 1105 * - Figure out where to insert the new entry: 1106 * - Generate a hash from a byte along with an additional 1-byte "short hash". The additional byte is our "tag" 1107 * - The hashTable is effectively split into groups or "rows" of 16 or 32 entries of U32, and the hash determines 1108 * which row to insert into. 1109 * - Determine the correct position within the row to insert the entry into. Each row of 16 or 32 can 1110 * be considered as a circular buffer with a "head" index that resides in the tagTable. 1111 * - Also insert the "tag" into the equivalent row and position in the tagTable. 1112 * - Note: The tagTable has 17 or 33 1-byte entries per row, due to 16 or 32 tags, and 1 "head" entry. 1113 * The 17 or 33 entry rows are spaced out to occur every 32 or 64 bytes, respectively, 1114 * for alignment/performance reasons, leaving some bytes unused. 1115 * - Use SIMD to efficiently compare the tags in the tagTable to the 1-byte "short hash" and 1116 * generate a bitfield that we can cycle through to check the collisions in the hash table. 1117 * - Pick the longest match. 1118 */ 1119 FORCE_INLINE_TEMPLATE 1120 size_t ZSTD_RowFindBestMatch( 1121 ZSTD_matchState_t* ms, 1122 const BYTE* const ip, const BYTE* const iLimit, 1123 size_t* offsetPtr, 1124 const U32 mls, const ZSTD_dictMode_e dictMode, 1125 const U32 rowLog) 1126 { 1127 U32* const hashTable = ms->hashTable; 1128 U16* const tagTable = ms->tagTable; 1129 U32* const hashCache = ms->hashCache; 1130 const U32 hashLog = ms->rowHashLog; 1131 const ZSTD_compressionParameters* const cParams = &ms->cParams; 1132 const BYTE* const base = ms->window.base; 1133 const BYTE* const dictBase = ms->window.dictBase; 1134 const U32 dictLimit = ms->window.dictLimit; 1135 const BYTE* const prefixStart = base + dictLimit; 1136 const BYTE* const dictEnd = dictBase + dictLimit; 1137 const U32 curr = (U32)(ip-base); 1138 const U32 maxDistance = 1U << cParams->windowLog; 1139 const U32 lowestValid = ms->window.lowLimit; 1140 const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid; 1141 const U32 isDictionary = (ms->loadedDictEnd != 0); 1142 const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance; 1143 const U32 rowEntries = (1U << rowLog); 1144 const U32 rowMask = rowEntries - 1; 1145 const U32 cappedSearchLog = MIN(cParams->searchLog, rowLog); /* nb of searches is capped at nb entries per row */ 1146 U32 nbAttempts = 1U << cappedSearchLog; 1147 size_t ml=4-1; 1148 1149 /* DMS/DDS variables that may be referenced laster */ 1150 const ZSTD_matchState_t* const dms = ms->dictMatchState; 1151 1152 /* Initialize the following variables to satisfy static analyzer */ 1153 size_t ddsIdx = 0; 1154 U32 ddsExtraAttempts = 0; /* cctx hash tables are limited in searches, but allow extra searches into DDS */ 1155 U32 dmsTag = 0; 1156 U32* dmsRow = NULL; 1157 BYTE* dmsTagRow = NULL; 1158 1159 if (dictMode == ZSTD_dedicatedDictSearch) { 1160 const U32 ddsHashLog = dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG; 1161 { /* Prefetch DDS hashtable entry */ 1162 ddsIdx = ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG; 1163 PREFETCH_L1(&dms->hashTable[ddsIdx]); 1164 } 1165 ddsExtraAttempts = cParams->searchLog > rowLog ? 1U << (cParams->searchLog - rowLog) : 0; 1166 } 1167 1168 if (dictMode == ZSTD_dictMatchState) { 1169 /* Prefetch DMS rows */ 1170 U32* const dmsHashTable = dms->hashTable; 1171 U16* const dmsTagTable = dms->tagTable; 1172 U32 const dmsHash = (U32)ZSTD_hashPtr(ip, dms->rowHashLog + ZSTD_ROW_HASH_TAG_BITS, mls); 1173 U32 const dmsRelRow = (dmsHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; 1174 dmsTag = dmsHash & ZSTD_ROW_HASH_TAG_MASK; 1175 dmsTagRow = (BYTE*)(dmsTagTable + dmsRelRow); 1176 dmsRow = dmsHashTable + dmsRelRow; 1177 ZSTD_row_prefetch(dmsHashTable, dmsTagTable, dmsRelRow, rowLog); 1178 } 1179 1180 /* Update the hashTable and tagTable up to (but not including) ip */ 1181 ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 1 /* useCache */); 1182 { /* Get the hash for ip, compute the appropriate row */ 1183 U32 const hash = ZSTD_row_nextCachedHash(hashCache, hashTable, tagTable, base, curr, hashLog, rowLog, mls); 1184 U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; 1185 U32 const tag = hash & ZSTD_ROW_HASH_TAG_MASK; 1186 U32* const row = hashTable + relRow; 1187 BYTE* tagRow = (BYTE*)(tagTable + relRow); 1188 U32 const head = *tagRow & rowMask; 1189 U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES]; 1190 size_t numMatches = 0; 1191 size_t currMatch = 0; 1192 ZSTD_VecMask matches = ZSTD_row_getMatchMask(tagRow, (BYTE)tag, head, rowEntries); 1193 1194 /* Cycle through the matches and prefetch */ 1195 for (; (matches > 0) && (nbAttempts > 0); --nbAttempts, matches &= (matches - 1)) { 1196 U32 const matchPos = (head + ZSTD_VecMask_next(matches)) & rowMask; 1197 U32 const matchIndex = row[matchPos]; 1198 assert(numMatches < rowEntries); 1199 if (matchIndex < lowLimit) 1200 break; 1201 if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { 1202 PREFETCH_L1(base + matchIndex); 1203 } else { 1204 PREFETCH_L1(dictBase + matchIndex); 1205 } 1206 matchBuffer[numMatches++] = matchIndex; 1207 } 1208 1209 /* Speed opt: insert current byte into hashtable too. This allows us to avoid one iteration of the loop 1210 in ZSTD_row_update_internal() at the next search. */ 1211 { 1212 U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask); 1213 tagRow[pos + ZSTD_ROW_HASH_TAG_OFFSET] = (BYTE)tag; 1214 row[pos] = ms->nextToUpdate++; 1215 } 1216 1217 /* Return the longest match */ 1218 for (; currMatch < numMatches; ++currMatch) { 1219 U32 const matchIndex = matchBuffer[currMatch]; 1220 size_t currentMl=0; 1221 assert(matchIndex < curr); 1222 assert(matchIndex >= lowLimit); 1223 1224 if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { 1225 const BYTE* const match = base + matchIndex; 1226 assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */ 1227 if (match[ml] == ip[ml]) /* potentially better */ 1228 currentMl = ZSTD_count(ip, match, iLimit); 1229 } else { 1230 const BYTE* const match = dictBase + matchIndex; 1231 assert(match+4 <= dictEnd); 1232 if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ 1233 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4; 1234 } 1235 1236 /* Save best solution */ 1237 if (currentMl > ml) { 1238 ml = currentMl; 1239 *offsetPtr = STORE_OFFSET(curr - matchIndex); 1240 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ 1241 } 1242 } 1243 } 1244 1245 assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ 1246 if (dictMode == ZSTD_dedicatedDictSearch) { 1247 ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts + ddsExtraAttempts, dms, 1248 ip, iLimit, prefixStart, curr, dictLimit, ddsIdx); 1249 } else if (dictMode == ZSTD_dictMatchState) { 1250 /* TODO: Measure and potentially add prefetching to DMS */ 1251 const U32 dmsLowestIndex = dms->window.dictLimit; 1252 const BYTE* const dmsBase = dms->window.base; 1253 const BYTE* const dmsEnd = dms->window.nextSrc; 1254 const U32 dmsSize = (U32)(dmsEnd - dmsBase); 1255 const U32 dmsIndexDelta = dictLimit - dmsSize; 1256 1257 { U32 const head = *dmsTagRow & rowMask; 1258 U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES]; 1259 size_t numMatches = 0; 1260 size_t currMatch = 0; 1261 ZSTD_VecMask matches = ZSTD_row_getMatchMask(dmsTagRow, (BYTE)dmsTag, head, rowEntries); 1262 1263 for (; (matches > 0) && (nbAttempts > 0); --nbAttempts, matches &= (matches - 1)) { 1264 U32 const matchPos = (head + ZSTD_VecMask_next(matches)) & rowMask; 1265 U32 const matchIndex = dmsRow[matchPos]; 1266 if (matchIndex < dmsLowestIndex) 1267 break; 1268 PREFETCH_L1(dmsBase + matchIndex); 1269 matchBuffer[numMatches++] = matchIndex; 1270 } 1271 1272 /* Return the longest match */ 1273 for (; currMatch < numMatches; ++currMatch) { 1274 U32 const matchIndex = matchBuffer[currMatch]; 1275 size_t currentMl=0; 1276 assert(matchIndex >= dmsLowestIndex); 1277 assert(matchIndex < curr); 1278 1279 { const BYTE* const match = dmsBase + matchIndex; 1280 assert(match+4 <= dmsEnd); 1281 if (MEM_read32(match) == MEM_read32(ip)) 1282 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4; 1283 } 1284 1285 if (currentMl > ml) { 1286 ml = currentMl; 1287 assert(curr > matchIndex + dmsIndexDelta); 1288 *offsetPtr = STORE_OFFSET(curr - (matchIndex + dmsIndexDelta)); 1289 if (ip+currentMl == iLimit) break; 1290 } 1291 } 1292 } 1293 } 1294 return ml; 1295 } 1296 1297 1298 /* 1299 * Generate search functions templated on (dictMode, mls, rowLog). 1300 * These functions are outlined for code size & compilation time. 1301 * ZSTD_searchMax() dispatches to the correct implementation function. 1302 * 1303 * TODO: The start of the search function involves loading and calculating a 1304 * bunch of constants from the ZSTD_matchState_t. These computations could be 1305 * done in an initialization function, and saved somewhere in the match state. 1306 * Then we could pass a pointer to the saved state instead of the match state, 1307 * and avoid duplicate computations. 1308 * 1309 * TODO: Move the match re-winding into searchMax. This improves compression 1310 * ratio, and unlocks further simplifications with the next TODO. 1311 * 1312 * TODO: Try moving the repcode search into searchMax. After the re-winding 1313 * and repcode search are in searchMax, there is no more logic in the match 1314 * finder loop that requires knowledge about the dictMode. So we should be 1315 * able to avoid force inlining it, and we can join the extDict loop with 1316 * the single segment loop. It should go in searchMax instead of its own 1317 * function to avoid having multiple virtual function calls per search. 1318 */ 1319 1320 #define ZSTD_BT_SEARCH_FN(dictMode, mls) ZSTD_BtFindBestMatch_##dictMode##_##mls 1321 #define ZSTD_HC_SEARCH_FN(dictMode, mls) ZSTD_HcFindBestMatch_##dictMode##_##mls 1322 #define ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog) ZSTD_RowFindBestMatch_##dictMode##_##mls##_##rowLog 1323 1324 #define ZSTD_SEARCH_FN_ATTRS FORCE_NOINLINE 1325 1326 #define GEN_ZSTD_BT_SEARCH_FN(dictMode, mls) \ 1327 ZSTD_SEARCH_FN_ATTRS size_t ZSTD_BT_SEARCH_FN(dictMode, mls)( \ 1328 ZSTD_matchState_t* ms, \ 1329 const BYTE* ip, const BYTE* const iLimit, \ 1330 size_t* offBasePtr) \ 1331 { \ 1332 assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ 1333 return ZSTD_BtFindBestMatch(ms, ip, iLimit, offBasePtr, mls, ZSTD_##dictMode); \ 1334 } \ 1335 1336 #define GEN_ZSTD_HC_SEARCH_FN(dictMode, mls) \ 1337 ZSTD_SEARCH_FN_ATTRS size_t ZSTD_HC_SEARCH_FN(dictMode, mls)( \ 1338 ZSTD_matchState_t* ms, \ 1339 const BYTE* ip, const BYTE* const iLimit, \ 1340 size_t* offsetPtr) \ 1341 { \ 1342 assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ 1343 return ZSTD_HcFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode); \ 1344 } \ 1345 1346 #define GEN_ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog) \ 1347 ZSTD_SEARCH_FN_ATTRS size_t ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog)( \ 1348 ZSTD_matchState_t* ms, \ 1349 const BYTE* ip, const BYTE* const iLimit, \ 1350 size_t* offsetPtr) \ 1351 { \ 1352 assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ 1353 assert(MAX(4, MIN(6, ms->cParams.searchLog)) == rowLog); \ 1354 return ZSTD_RowFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode, rowLog); \ 1355 } \ 1356 1357 #define ZSTD_FOR_EACH_ROWLOG(X, dictMode, mls) \ 1358 X(dictMode, mls, 4) \ 1359 X(dictMode, mls, 5) \ 1360 X(dictMode, mls, 6) 1361 1362 #define ZSTD_FOR_EACH_MLS_ROWLOG(X, dictMode) \ 1363 ZSTD_FOR_EACH_ROWLOG(X, dictMode, 4) \ 1364 ZSTD_FOR_EACH_ROWLOG(X, dictMode, 5) \ 1365 ZSTD_FOR_EACH_ROWLOG(X, dictMode, 6) 1366 1367 #define ZSTD_FOR_EACH_MLS(X, dictMode) \ 1368 X(dictMode, 4) \ 1369 X(dictMode, 5) \ 1370 X(dictMode, 6) 1371 1372 #define ZSTD_FOR_EACH_DICT_MODE(X, ...) \ 1373 X(__VA_ARGS__, noDict) \ 1374 X(__VA_ARGS__, extDict) \ 1375 X(__VA_ARGS__, dictMatchState) \ 1376 X(__VA_ARGS__, dedicatedDictSearch) 1377 1378 /* Generate row search fns for each combination of (dictMode, mls, rowLog) */ 1379 ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS_ROWLOG, GEN_ZSTD_ROW_SEARCH_FN) 1380 /* Generate binary Tree search fns for each combination of (dictMode, mls) */ 1381 ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_BT_SEARCH_FN) 1382 /* Generate hash chain search fns for each combination of (dictMode, mls) */ 1383 ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_HC_SEARCH_FN) 1384 1385 typedef enum { search_hashChain=0, search_binaryTree=1, search_rowHash=2 } searchMethod_e; 1386 1387 #define GEN_ZSTD_CALL_BT_SEARCH_FN(dictMode, mls) \ 1388 case mls: \ 1389 return ZSTD_BT_SEARCH_FN(dictMode, mls)(ms, ip, iend, offsetPtr); 1390 #define GEN_ZSTD_CALL_HC_SEARCH_FN(dictMode, mls) \ 1391 case mls: \ 1392 return ZSTD_HC_SEARCH_FN(dictMode, mls)(ms, ip, iend, offsetPtr); 1393 #define GEN_ZSTD_CALL_ROW_SEARCH_FN(dictMode, mls, rowLog) \ 1394 case rowLog: \ 1395 return ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog)(ms, ip, iend, offsetPtr); 1396 1397 #define ZSTD_SWITCH_MLS(X, dictMode) \ 1398 switch (mls) { \ 1399 ZSTD_FOR_EACH_MLS(X, dictMode) \ 1400 } 1401 1402 #define ZSTD_SWITCH_ROWLOG(dictMode, mls) \ 1403 case mls: \ 1404 switch (rowLog) { \ 1405 ZSTD_FOR_EACH_ROWLOG(GEN_ZSTD_CALL_ROW_SEARCH_FN, dictMode, mls) \ 1406 } \ 1407 ZSTD_UNREACHABLE; \ 1408 break; 1409 1410 #define ZSTD_SWITCH_SEARCH_METHOD(dictMode) \ 1411 switch (searchMethod) { \ 1412 case search_hashChain: \ 1413 ZSTD_SWITCH_MLS(GEN_ZSTD_CALL_HC_SEARCH_FN, dictMode) \ 1414 break; \ 1415 case search_binaryTree: \ 1416 ZSTD_SWITCH_MLS(GEN_ZSTD_CALL_BT_SEARCH_FN, dictMode) \ 1417 break; \ 1418 case search_rowHash: \ 1419 ZSTD_SWITCH_MLS(ZSTD_SWITCH_ROWLOG, dictMode) \ 1420 break; \ 1421 } \ 1422 ZSTD_UNREACHABLE; 1423 1424 /* 1425 * Searches for the longest match at @p ip. 1426 * Dispatches to the correct implementation function based on the 1427 * (searchMethod, dictMode, mls, rowLog). We use switch statements 1428 * here instead of using an indirect function call through a function 1429 * pointer because after Spectre and Meltdown mitigations, indirect 1430 * function calls can be very costly, especially in the kernel. 1431 * 1432 * NOTE: dictMode and searchMethod should be templated, so those switch 1433 * statements should be optimized out. Only the mls & rowLog switches 1434 * should be left. 1435 * 1436 * @param ms The match state. 1437 * @param ip The position to search at. 1438 * @param iend The end of the input data. 1439 * @param[out] offsetPtr Stores the match offset into this pointer. 1440 * @param mls The minimum search length, in the range [4, 6]. 1441 * @param rowLog The row log (if applicable), in the range [4, 6]. 1442 * @param searchMethod The search method to use (templated). 1443 * @param dictMode The dictMode (templated). 1444 * 1445 * @returns The length of the longest match found, or < mls if no match is found. 1446 * If a match is found its offset is stored in @p offsetPtr. 1447 */ 1448 FORCE_INLINE_TEMPLATE size_t ZSTD_searchMax( 1449 ZSTD_matchState_t* ms, 1450 const BYTE* ip, 1451 const BYTE* iend, 1452 size_t* offsetPtr, 1453 U32 const mls, 1454 U32 const rowLog, 1455 searchMethod_e const searchMethod, 1456 ZSTD_dictMode_e const dictMode) 1457 { 1458 if (dictMode == ZSTD_noDict) { 1459 ZSTD_SWITCH_SEARCH_METHOD(noDict) 1460 } else if (dictMode == ZSTD_extDict) { 1461 ZSTD_SWITCH_SEARCH_METHOD(extDict) 1462 } else if (dictMode == ZSTD_dictMatchState) { 1463 ZSTD_SWITCH_SEARCH_METHOD(dictMatchState) 1464 } else if (dictMode == ZSTD_dedicatedDictSearch) { 1465 ZSTD_SWITCH_SEARCH_METHOD(dedicatedDictSearch) 1466 } 1467 ZSTD_UNREACHABLE; 1468 return 0; 1469 } 1470 1471 /* ******************************* 1472 * Common parser - lazy strategy 1473 *********************************/ 1474 1475 FORCE_INLINE_TEMPLATE size_t 1476 ZSTD_compressBlock_lazy_generic( 1477 ZSTD_matchState_t* ms, seqStore_t* seqStore, 1478 U32 rep[ZSTD_REP_NUM], 1479 const void* src, size_t srcSize, 1480 const searchMethod_e searchMethod, const U32 depth, 1481 ZSTD_dictMode_e const dictMode) 1482 { 1483 const BYTE* const istart = (const BYTE*)src; 1484 const BYTE* ip = istart; 1485 const BYTE* anchor = istart; 1486 const BYTE* const iend = istart + srcSize; 1487 const BYTE* const ilimit = (searchMethod == search_rowHash) ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8; 1488 const BYTE* const base = ms->window.base; 1489 const U32 prefixLowestIndex = ms->window.dictLimit; 1490 const BYTE* const prefixLowest = base + prefixLowestIndex; 1491 const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6); 1492 const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); 1493 1494 U32 offset_1 = rep[0], offset_2 = rep[1], savedOffset=0; 1495 1496 const int isDMS = dictMode == ZSTD_dictMatchState; 1497 const int isDDS = dictMode == ZSTD_dedicatedDictSearch; 1498 const int isDxS = isDMS || isDDS; 1499 const ZSTD_matchState_t* const dms = ms->dictMatchState; 1500 const U32 dictLowestIndex = isDxS ? dms->window.dictLimit : 0; 1501 const BYTE* const dictBase = isDxS ? dms->window.base : NULL; 1502 const BYTE* const dictLowest = isDxS ? dictBase + dictLowestIndex : NULL; 1503 const BYTE* const dictEnd = isDxS ? dms->window.nextSrc : NULL; 1504 const U32 dictIndexDelta = isDxS ? 1505 prefixLowestIndex - (U32)(dictEnd - dictBase) : 1506 0; 1507 const U32 dictAndPrefixLength = (U32)((ip - prefixLowest) + (dictEnd - dictLowest)); 1508 1509 DEBUGLOG(5, "ZSTD_compressBlock_lazy_generic (dictMode=%u) (searchFunc=%u)", (U32)dictMode, (U32)searchMethod); 1510 ip += (dictAndPrefixLength == 0); 1511 if (dictMode == ZSTD_noDict) { 1512 U32 const curr = (U32)(ip - base); 1513 U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, ms->cParams.windowLog); 1514 U32 const maxRep = curr - windowLow; 1515 if (offset_2 > maxRep) savedOffset = offset_2, offset_2 = 0; 1516 if (offset_1 > maxRep) savedOffset = offset_1, offset_1 = 0; 1517 } 1518 if (isDxS) { 1519 /* dictMatchState repCode checks don't currently handle repCode == 0 1520 * disabling. */ 1521 assert(offset_1 <= dictAndPrefixLength); 1522 assert(offset_2 <= dictAndPrefixLength); 1523 } 1524 1525 if (searchMethod == search_rowHash) { 1526 ZSTD_row_fillHashCache(ms, base, rowLog, 1527 MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */), 1528 ms->nextToUpdate, ilimit); 1529 } 1530 1531 /* Match Loop */ 1532 #if defined(__x86_64__) 1533 /* I've measured random a 5% speed loss on levels 5 & 6 (greedy) when the 1534 * code alignment is perturbed. To fix the instability align the loop on 32-bytes. 1535 */ 1536 __asm__(".p2align 5"); 1537 #endif 1538 while (ip < ilimit) { 1539 size_t matchLength=0; 1540 size_t offcode=STORE_REPCODE_1; 1541 const BYTE* start=ip+1; 1542 DEBUGLOG(7, "search baseline (depth 0)"); 1543 1544 /* check repCode */ 1545 if (isDxS) { 1546 const U32 repIndex = (U32)(ip - base) + 1 - offset_1; 1547 const BYTE* repMatch = ((dictMode == ZSTD_dictMatchState || dictMode == ZSTD_dedicatedDictSearch) 1548 && repIndex < prefixLowestIndex) ? 1549 dictBase + (repIndex - dictIndexDelta) : 1550 base + repIndex; 1551 if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) 1552 && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) { 1553 const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; 1554 matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; 1555 if (depth==0) goto _storeSequence; 1556 } 1557 } 1558 if ( dictMode == ZSTD_noDict 1559 && ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) { 1560 matchLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4; 1561 if (depth==0) goto _storeSequence; 1562 } 1563 1564 /* first search (depth 0) */ 1565 { size_t offsetFound = 999999999; 1566 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offsetFound, mls, rowLog, searchMethod, dictMode); 1567 if (ml2 > matchLength) 1568 matchLength = ml2, start = ip, offcode=offsetFound; 1569 } 1570 1571 if (matchLength < 4) { 1572 ip += ((ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */ 1573 continue; 1574 } 1575 1576 /* let's try to find a better solution */ 1577 if (depth>=1) 1578 while (ip<ilimit) { 1579 DEBUGLOG(7, "search depth 1"); 1580 ip ++; 1581 if ( (dictMode == ZSTD_noDict) 1582 && (offcode) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) { 1583 size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4; 1584 int const gain2 = (int)(mlRep * 3); 1585 int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1); 1586 if ((mlRep >= 4) && (gain2 > gain1)) 1587 matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip; 1588 } 1589 if (isDxS) { 1590 const U32 repIndex = (U32)(ip - base) - offset_1; 1591 const BYTE* repMatch = repIndex < prefixLowestIndex ? 1592 dictBase + (repIndex - dictIndexDelta) : 1593 base + repIndex; 1594 if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) 1595 && (MEM_read32(repMatch) == MEM_read32(ip)) ) { 1596 const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; 1597 size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; 1598 int const gain2 = (int)(mlRep * 3); 1599 int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1); 1600 if ((mlRep >= 4) && (gain2 > gain1)) 1601 matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip; 1602 } 1603 } 1604 { size_t offset2=999999999; 1605 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offset2, mls, rowLog, searchMethod, dictMode); 1606 int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offset2))); /* raw approx */ 1607 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 4); 1608 if ((ml2 >= 4) && (gain2 > gain1)) { 1609 matchLength = ml2, offcode = offset2, start = ip; 1610 continue; /* search a better one */ 1611 } } 1612 1613 /* let's find an even better one */ 1614 if ((depth==2) && (ip<ilimit)) { 1615 DEBUGLOG(7, "search depth 2"); 1616 ip ++; 1617 if ( (dictMode == ZSTD_noDict) 1618 && (offcode) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) { 1619 size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4; 1620 int const gain2 = (int)(mlRep * 4); 1621 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1); 1622 if ((mlRep >= 4) && (gain2 > gain1)) 1623 matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip; 1624 } 1625 if (isDxS) { 1626 const U32 repIndex = (U32)(ip - base) - offset_1; 1627 const BYTE* repMatch = repIndex < prefixLowestIndex ? 1628 dictBase + (repIndex - dictIndexDelta) : 1629 base + repIndex; 1630 if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) 1631 && (MEM_read32(repMatch) == MEM_read32(ip)) ) { 1632 const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; 1633 size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; 1634 int const gain2 = (int)(mlRep * 4); 1635 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1); 1636 if ((mlRep >= 4) && (gain2 > gain1)) 1637 matchLength = mlRep, offcode = STORE_REPCODE_1, start = ip; 1638 } 1639 } 1640 { size_t offset2=999999999; 1641 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offset2, mls, rowLog, searchMethod, dictMode); 1642 int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offset2))); /* raw approx */ 1643 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 7); 1644 if ((ml2 >= 4) && (gain2 > gain1)) { 1645 matchLength = ml2, offcode = offset2, start = ip; 1646 continue; 1647 } } } 1648 break; /* nothing found : store previous solution */ 1649 } 1650 1651 /* NOTE: 1652 * Pay attention that `start[-value]` can lead to strange undefined behavior 1653 * notably if `value` is unsigned, resulting in a large positive `-value`. 1654 */ 1655 /* catch up */ 1656 if (STORED_IS_OFFSET(offcode)) { 1657 if (dictMode == ZSTD_noDict) { 1658 while ( ((start > anchor) & (start - STORED_OFFSET(offcode) > prefixLowest)) 1659 && (start[-1] == (start-STORED_OFFSET(offcode))[-1]) ) /* only search for offset within prefix */ 1660 { start--; matchLength++; } 1661 } 1662 if (isDxS) { 1663 U32 const matchIndex = (U32)((size_t)(start-base) - STORED_OFFSET(offcode)); 1664 const BYTE* match = (matchIndex < prefixLowestIndex) ? dictBase + matchIndex - dictIndexDelta : base + matchIndex; 1665 const BYTE* const mStart = (matchIndex < prefixLowestIndex) ? dictLowest : prefixLowest; 1666 while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */ 1667 } 1668 offset_2 = offset_1; offset_1 = (U32)STORED_OFFSET(offcode); 1669 } 1670 /* store sequence */ 1671 _storeSequence: 1672 { size_t const litLength = (size_t)(start - anchor); 1673 ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offcode, matchLength); 1674 anchor = ip = start + matchLength; 1675 } 1676 1677 /* check immediate repcode */ 1678 if (isDxS) { 1679 while (ip <= ilimit) { 1680 U32 const current2 = (U32)(ip-base); 1681 U32 const repIndex = current2 - offset_2; 1682 const BYTE* repMatch = repIndex < prefixLowestIndex ? 1683 dictBase - dictIndexDelta + repIndex : 1684 base + repIndex; 1685 if ( ((U32)((prefixLowestIndex-1) - (U32)repIndex) >= 3 /* intentional overflow */) 1686 && (MEM_read32(repMatch) == MEM_read32(ip)) ) { 1687 const BYTE* const repEnd2 = repIndex < prefixLowestIndex ? dictEnd : iend; 1688 matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd2, prefixLowest) + 4; 1689 offcode = offset_2; offset_2 = offset_1; offset_1 = (U32)offcode; /* swap offset_2 <=> offset_1 */ 1690 ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, matchLength); 1691 ip += matchLength; 1692 anchor = ip; 1693 continue; 1694 } 1695 break; 1696 } 1697 } 1698 1699 if (dictMode == ZSTD_noDict) { 1700 while ( ((ip <= ilimit) & (offset_2>0)) 1701 && (MEM_read32(ip) == MEM_read32(ip - offset_2)) ) { 1702 /* store sequence */ 1703 matchLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4; 1704 offcode = offset_2; offset_2 = offset_1; offset_1 = (U32)offcode; /* swap repcodes */ 1705 ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, matchLength); 1706 ip += matchLength; 1707 anchor = ip; 1708 continue; /* faster when present ... (?) */ 1709 } } } 1710 1711 /* Save reps for next block */ 1712 rep[0] = offset_1 ? offset_1 : savedOffset; 1713 rep[1] = offset_2 ? offset_2 : savedOffset; 1714 1715 /* Return the last literals size */ 1716 return (size_t)(iend - anchor); 1717 } 1718 1719 1720 size_t ZSTD_compressBlock_btlazy2( 1721 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1722 void const* src, size_t srcSize) 1723 { 1724 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_noDict); 1725 } 1726 1727 size_t ZSTD_compressBlock_lazy2( 1728 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1729 void const* src, size_t srcSize) 1730 { 1731 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_noDict); 1732 } 1733 1734 size_t ZSTD_compressBlock_lazy( 1735 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1736 void const* src, size_t srcSize) 1737 { 1738 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_noDict); 1739 } 1740 1741 size_t ZSTD_compressBlock_greedy( 1742 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1743 void const* src, size_t srcSize) 1744 { 1745 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_noDict); 1746 } 1747 1748 size_t ZSTD_compressBlock_btlazy2_dictMatchState( 1749 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1750 void const* src, size_t srcSize) 1751 { 1752 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_dictMatchState); 1753 } 1754 1755 size_t ZSTD_compressBlock_lazy2_dictMatchState( 1756 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1757 void const* src, size_t srcSize) 1758 { 1759 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dictMatchState); 1760 } 1761 1762 size_t ZSTD_compressBlock_lazy_dictMatchState( 1763 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1764 void const* src, size_t srcSize) 1765 { 1766 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dictMatchState); 1767 } 1768 1769 size_t ZSTD_compressBlock_greedy_dictMatchState( 1770 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1771 void const* src, size_t srcSize) 1772 { 1773 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dictMatchState); 1774 } 1775 1776 1777 size_t ZSTD_compressBlock_lazy2_dedicatedDictSearch( 1778 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1779 void const* src, size_t srcSize) 1780 { 1781 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dedicatedDictSearch); 1782 } 1783 1784 size_t ZSTD_compressBlock_lazy_dedicatedDictSearch( 1785 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1786 void const* src, size_t srcSize) 1787 { 1788 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dedicatedDictSearch); 1789 } 1790 1791 size_t ZSTD_compressBlock_greedy_dedicatedDictSearch( 1792 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1793 void const* src, size_t srcSize) 1794 { 1795 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dedicatedDictSearch); 1796 } 1797 1798 /* Row-based matchfinder */ 1799 size_t ZSTD_compressBlock_lazy2_row( 1800 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1801 void const* src, size_t srcSize) 1802 { 1803 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_noDict); 1804 } 1805 1806 size_t ZSTD_compressBlock_lazy_row( 1807 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1808 void const* src, size_t srcSize) 1809 { 1810 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_noDict); 1811 } 1812 1813 size_t ZSTD_compressBlock_greedy_row( 1814 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1815 void const* src, size_t srcSize) 1816 { 1817 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_noDict); 1818 } 1819 1820 size_t ZSTD_compressBlock_lazy2_dictMatchState_row( 1821 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1822 void const* src, size_t srcSize) 1823 { 1824 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_dictMatchState); 1825 } 1826 1827 size_t ZSTD_compressBlock_lazy_dictMatchState_row( 1828 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1829 void const* src, size_t srcSize) 1830 { 1831 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_dictMatchState); 1832 } 1833 1834 size_t ZSTD_compressBlock_greedy_dictMatchState_row( 1835 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1836 void const* src, size_t srcSize) 1837 { 1838 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_dictMatchState); 1839 } 1840 1841 1842 size_t ZSTD_compressBlock_lazy2_dedicatedDictSearch_row( 1843 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1844 void const* src, size_t srcSize) 1845 { 1846 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_dedicatedDictSearch); 1847 } 1848 1849 size_t ZSTD_compressBlock_lazy_dedicatedDictSearch_row( 1850 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1851 void const* src, size_t srcSize) 1852 { 1853 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_dedicatedDictSearch); 1854 } 1855 1856 size_t ZSTD_compressBlock_greedy_dedicatedDictSearch_row( 1857 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 1858 void const* src, size_t srcSize) 1859 { 1860 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_dedicatedDictSearch); 1861 } 1862 1863 FORCE_INLINE_TEMPLATE 1864 size_t ZSTD_compressBlock_lazy_extDict_generic( 1865 ZSTD_matchState_t* ms, seqStore_t* seqStore, 1866 U32 rep[ZSTD_REP_NUM], 1867 const void* src, size_t srcSize, 1868 const searchMethod_e searchMethod, const U32 depth) 1869 { 1870 const BYTE* const istart = (const BYTE*)src; 1871 const BYTE* ip = istart; 1872 const BYTE* anchor = istart; 1873 const BYTE* const iend = istart + srcSize; 1874 const BYTE* const ilimit = searchMethod == search_rowHash ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8; 1875 const BYTE* const base = ms->window.base; 1876 const U32 dictLimit = ms->window.dictLimit; 1877 const BYTE* const prefixStart = base + dictLimit; 1878 const BYTE* const dictBase = ms->window.dictBase; 1879 const BYTE* const dictEnd = dictBase + dictLimit; 1880 const BYTE* const dictStart = dictBase + ms->window.lowLimit; 1881 const U32 windowLog = ms->cParams.windowLog; 1882 const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6); 1883 const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); 1884 1885 U32 offset_1 = rep[0], offset_2 = rep[1]; 1886 1887 DEBUGLOG(5, "ZSTD_compressBlock_lazy_extDict_generic (searchFunc=%u)", (U32)searchMethod); 1888 1889 /* init */ 1890 ip += (ip == prefixStart); 1891 if (searchMethod == search_rowHash) { 1892 ZSTD_row_fillHashCache(ms, base, rowLog, 1893 MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */), 1894 ms->nextToUpdate, ilimit); 1895 } 1896 1897 /* Match Loop */ 1898 #if defined(__x86_64__) 1899 /* I've measured random a 5% speed loss on levels 5 & 6 (greedy) when the 1900 * code alignment is perturbed. To fix the instability align the loop on 32-bytes. 1901 */ 1902 __asm__(".p2align 5"); 1903 #endif 1904 while (ip < ilimit) { 1905 size_t matchLength=0; 1906 size_t offcode=STORE_REPCODE_1; 1907 const BYTE* start=ip+1; 1908 U32 curr = (U32)(ip-base); 1909 1910 /* check repCode */ 1911 { const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr+1, windowLog); 1912 const U32 repIndex = (U32)(curr+1 - offset_1); 1913 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; 1914 const BYTE* const repMatch = repBase + repIndex; 1915 if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow */ 1916 & (offset_1 <= curr+1 - windowLow) ) /* note: we are searching at curr+1 */ 1917 if (MEM_read32(ip+1) == MEM_read32(repMatch)) { 1918 /* repcode detected we should take it */ 1919 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; 1920 matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repEnd, prefixStart) + 4; 1921 if (depth==0) goto _storeSequence; 1922 } } 1923 1924 /* first search (depth 0) */ 1925 { size_t offsetFound = 999999999; 1926 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offsetFound, mls, rowLog, searchMethod, ZSTD_extDict); 1927 if (ml2 > matchLength) 1928 matchLength = ml2, start = ip, offcode=offsetFound; 1929 } 1930 1931 if (matchLength < 4) { 1932 ip += ((ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */ 1933 continue; 1934 } 1935 1936 /* let's try to find a better solution */ 1937 if (depth>=1) 1938 while (ip<ilimit) { 1939 ip ++; 1940 curr++; 1941 /* check repCode */ 1942 if (offcode) { 1943 const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog); 1944 const U32 repIndex = (U32)(curr - offset_1); 1945 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; 1946 const BYTE* const repMatch = repBase + repIndex; 1947 if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ 1948 & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ 1949 if (MEM_read32(ip) == MEM_read32(repMatch)) { 1950 /* repcode detected */ 1951 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; 1952 size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; 1953 int const gain2 = (int)(repLength * 3); 1954 int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1); 1955 if ((repLength >= 4) && (gain2 > gain1)) 1956 matchLength = repLength, offcode = STORE_REPCODE_1, start = ip; 1957 } } 1958 1959 /* search match, depth 1 */ 1960 { size_t offset2=999999999; 1961 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offset2, mls, rowLog, searchMethod, ZSTD_extDict); 1962 int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offset2))); /* raw approx */ 1963 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 4); 1964 if ((ml2 >= 4) && (gain2 > gain1)) { 1965 matchLength = ml2, offcode = offset2, start = ip; 1966 continue; /* search a better one */ 1967 } } 1968 1969 /* let's find an even better one */ 1970 if ((depth==2) && (ip<ilimit)) { 1971 ip ++; 1972 curr++; 1973 /* check repCode */ 1974 if (offcode) { 1975 const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog); 1976 const U32 repIndex = (U32)(curr - offset_1); 1977 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; 1978 const BYTE* const repMatch = repBase + repIndex; 1979 if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ 1980 & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ 1981 if (MEM_read32(ip) == MEM_read32(repMatch)) { 1982 /* repcode detected */ 1983 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; 1984 size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; 1985 int const gain2 = (int)(repLength * 4); 1986 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 1); 1987 if ((repLength >= 4) && (gain2 > gain1)) 1988 matchLength = repLength, offcode = STORE_REPCODE_1, start = ip; 1989 } } 1990 1991 /* search match, depth 2 */ 1992 { size_t offset2=999999999; 1993 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offset2, mls, rowLog, searchMethod, ZSTD_extDict); 1994 int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offset2))); /* raw approx */ 1995 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)STORED_TO_OFFBASE(offcode)) + 7); 1996 if ((ml2 >= 4) && (gain2 > gain1)) { 1997 matchLength = ml2, offcode = offset2, start = ip; 1998 continue; 1999 } } } 2000 break; /* nothing found : store previous solution */ 2001 } 2002 2003 /* catch up */ 2004 if (STORED_IS_OFFSET(offcode)) { 2005 U32 const matchIndex = (U32)((size_t)(start-base) - STORED_OFFSET(offcode)); 2006 const BYTE* match = (matchIndex < dictLimit) ? dictBase + matchIndex : base + matchIndex; 2007 const BYTE* const mStart = (matchIndex < dictLimit) ? dictStart : prefixStart; 2008 while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */ 2009 offset_2 = offset_1; offset_1 = (U32)STORED_OFFSET(offcode); 2010 } 2011 2012 /* store sequence */ 2013 _storeSequence: 2014 { size_t const litLength = (size_t)(start - anchor); 2015 ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offcode, matchLength); 2016 anchor = ip = start + matchLength; 2017 } 2018 2019 /* check immediate repcode */ 2020 while (ip <= ilimit) { 2021 const U32 repCurrent = (U32)(ip-base); 2022 const U32 windowLow = ZSTD_getLowestMatchIndex(ms, repCurrent, windowLog); 2023 const U32 repIndex = repCurrent - offset_2; 2024 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; 2025 const BYTE* const repMatch = repBase + repIndex; 2026 if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ 2027 & (offset_2 <= repCurrent - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ 2028 if (MEM_read32(ip) == MEM_read32(repMatch)) { 2029 /* repcode detected we should take it */ 2030 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; 2031 matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; 2032 offcode = offset_2; offset_2 = offset_1; offset_1 = (U32)offcode; /* swap offset history */ 2033 ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, matchLength); 2034 ip += matchLength; 2035 anchor = ip; 2036 continue; /* faster when present ... (?) */ 2037 } 2038 break; 2039 } } 2040 2041 /* Save reps for next block */ 2042 rep[0] = offset_1; 2043 rep[1] = offset_2; 2044 2045 /* Return the last literals size */ 2046 return (size_t)(iend - anchor); 2047 } 2048 2049 2050 size_t ZSTD_compressBlock_greedy_extDict( 2051 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 2052 void const* src, size_t srcSize) 2053 { 2054 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0); 2055 } 2056 2057 size_t ZSTD_compressBlock_lazy_extDict( 2058 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 2059 void const* src, size_t srcSize) 2060 2061 { 2062 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1); 2063 } 2064 2065 size_t ZSTD_compressBlock_lazy2_extDict( 2066 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 2067 void const* src, size_t srcSize) 2068 2069 { 2070 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2); 2071 } 2072 2073 size_t ZSTD_compressBlock_btlazy2_extDict( 2074 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 2075 void const* src, size_t srcSize) 2076 2077 { 2078 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2); 2079 } 2080 2081 size_t ZSTD_compressBlock_greedy_extDict_row( 2082 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 2083 void const* src, size_t srcSize) 2084 { 2085 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0); 2086 } 2087 2088 size_t ZSTD_compressBlock_lazy_extDict_row( 2089 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 2090 void const* src, size_t srcSize) 2091 2092 { 2093 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1); 2094 } 2095 2096 size_t ZSTD_compressBlock_lazy2_extDict_row( 2097 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], 2098 void const* src, size_t srcSize) 2099 2100 { 2101 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2); 2102 } 2103