| 1 | /* |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 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 | #include "../common/bits.h" /* ZSTD_countTrailingZeros64 */ |
| 14 | |
| 15 | #define kLazySkippingStep 8 |
| 16 | |
| 17 | |
| 18 | /*-************************************* |
| 19 | * Binary Tree search |
| 20 | ***************************************/ |
| 21 | |
| 22 | static void |
| 23 | ZSTD_updateDUBT(ZSTD_matchState_t* ms, |
| 24 | const BYTE* ip, const BYTE* iend, |
| 25 | U32 mls) |
| 26 | { |
| 27 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| 28 | U32* const hashTable = ms->hashTable; |
| 29 | U32 const hashLog = cParams->hashLog; |
| 30 | |
| 31 | U32* const bt = ms->chainTable; |
| 32 | U32 const btLog = cParams->chainLog - 1; |
| 33 | U32 const btMask = (1 << btLog) - 1; |
| 34 | |
| 35 | const BYTE* const base = ms->window.base; |
| 36 | U32 const target = (U32)(ip - base); |
| 37 | U32 idx = ms->nextToUpdate; |
| 38 | |
| 39 | if (idx != target) |
| 40 | DEBUGLOG(7, "ZSTD_updateDUBT, from %u to %u (dictLimit:%u)", |
| 41 | idx, target, ms->window.dictLimit); |
| 42 | assert(ip + 8 <= iend); /* condition for ZSTD_hashPtr */ |
| 43 | (void)iend; |
| 44 | |
| 45 | assert(idx >= ms->window.dictLimit); /* condition for valid base+idx */ |
| 46 | for ( ; idx < target ; idx++) { |
| 47 | size_t const h = ZSTD_hashPtr(base + idx, hashLog, mls); /* assumption : ip + 8 <= iend */ |
| 48 | U32 const matchIndex = hashTable[h]; |
| 49 | |
| 50 | U32* const nextCandidatePtr = bt + 2*(idx&btMask); |
| 51 | U32* const sortMarkPtr = nextCandidatePtr + 1; |
| 52 | |
| 53 | DEBUGLOG(8, "ZSTD_updateDUBT: insert %u", idx); |
| 54 | hashTable[h] = idx; /* Update Hash Table */ |
| 55 | *nextCandidatePtr = matchIndex; /* update BT like a chain */ |
| 56 | *sortMarkPtr = ZSTD_DUBT_UNSORTED_MARK; |
| 57 | } |
| 58 | ms->nextToUpdate = target; |
| 59 | } |
| 60 | |
| 61 | |
| 62 | /** ZSTD_insertDUBT1() : |
| 63 | * sort one already inserted but unsorted position |
| 64 | * assumption : curr >= btlow == (curr - btmask) |
| 65 | * doesn't fail */ |
| 66 | static void |
| 67 | ZSTD_insertDUBT1(const ZSTD_matchState_t* ms, |
| 68 | U32 curr, const BYTE* inputEnd, |
| 69 | U32 nbCompares, U32 btLow, |
| 70 | const ZSTD_dictMode_e dictMode) |
| 71 | { |
| 72 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| 73 | U32* const bt = ms->chainTable; |
| 74 | U32 const btLog = cParams->chainLog - 1; |
| 75 | U32 const btMask = (1 << btLog) - 1; |
| 76 | size_t commonLengthSmaller=0, commonLengthLarger=0; |
| 77 | const BYTE* const base = ms->window.base; |
| 78 | const BYTE* const dictBase = ms->window.dictBase; |
| 79 | const U32 dictLimit = ms->window.dictLimit; |
| 80 | const BYTE* const ip = (curr>=dictLimit) ? base + curr : dictBase + curr; |
| 81 | const BYTE* const iend = (curr>=dictLimit) ? inputEnd : dictBase + dictLimit; |
| 82 | const BYTE* const dictEnd = dictBase + dictLimit; |
| 83 | const BYTE* const prefixStart = base + dictLimit; |
| 84 | const BYTE* match; |
| 85 | U32* smallerPtr = bt + 2*(curr&btMask); |
| 86 | U32* largerPtr = smallerPtr + 1; |
| 87 | 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) */ |
| 88 | U32 dummy32; /* to be nullified at the end */ |
| 89 | U32 const windowValid = ms->window.lowLimit; |
| 90 | U32 const maxDistance = 1U << cParams->windowLog; |
| 91 | U32 const windowLow = (curr - windowValid > maxDistance) ? curr - maxDistance : windowValid; |
| 92 | |
| 93 | |
| 94 | DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)", |
| 95 | curr, dictLimit, windowLow); |
| 96 | assert(curr >= btLow); |
| 97 | assert(ip < iend); /* condition for ZSTD_count */ |
| 98 | |
| 99 | for (; nbCompares && (matchIndex > windowLow); --nbCompares) { |
| 100 | U32* const nextPtr = bt + 2*(matchIndex & btMask); |
| 101 | size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ |
| 102 | assert(matchIndex < curr); |
| 103 | /* note : all candidates are now supposed sorted, |
| 104 | * but it's still possible to have nextPtr[1] == ZSTD_DUBT_UNSORTED_MARK |
| 105 | * when a real index has the same value as ZSTD_DUBT_UNSORTED_MARK */ |
| 106 | |
| 107 | if ( (dictMode != ZSTD_extDict) |
| 108 | || (matchIndex+matchLength >= dictLimit) /* both in current segment*/ |
| 109 | || (curr < dictLimit) /* both in extDict */) { |
| 110 | const BYTE* const mBase = ( (dictMode != ZSTD_extDict) |
| 111 | || (matchIndex+matchLength >= dictLimit)) ? |
| 112 | base : dictBase; |
| 113 | assert( (matchIndex+matchLength >= dictLimit) /* might be wrong if extDict is incorrectly set to 0 */ |
| 114 | || (curr < dictLimit) ); |
| 115 | match = mBase + matchIndex; |
| 116 | matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); |
| 117 | } else { |
| 118 | match = dictBase + matchIndex; |
| 119 | matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); |
| 120 | if (matchIndex+matchLength >= dictLimit) |
| 121 | match = base + matchIndex; /* preparation for next read of match[matchLength] */ |
| 122 | } |
| 123 | |
| 124 | DEBUGLOG(8, "ZSTD_insertDUBT1: comparing %u with %u : found %u common bytes ", |
| 125 | curr, matchIndex, (U32)matchLength); |
| 126 | |
| 127 | if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ |
| 128 | break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */ |
| 129 | } |
| 130 | |
| 131 | if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */ |
| 132 | /* match is smaller than current */ |
| 133 | *smallerPtr = matchIndex; /* update smaller idx */ |
| 134 | commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ |
| 135 | if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */ |
| 136 | DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is smaller : next => %u", |
| 137 | matchIndex, btLow, nextPtr[1]); |
| 138 | smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */ |
| 139 | matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */ |
| 140 | } else { |
| 141 | /* match is larger than current */ |
| 142 | *largerPtr = matchIndex; |
| 143 | commonLengthLarger = matchLength; |
| 144 | if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */ |
| 145 | DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is larger => %u", |
| 146 | matchIndex, btLow, nextPtr[0]); |
| 147 | largerPtr = nextPtr; |
| 148 | matchIndex = nextPtr[0]; |
| 149 | } } |
| 150 | |
| 151 | *smallerPtr = *largerPtr = 0; |
| 152 | } |
| 153 | |
| 154 | |
| 155 | static size_t |
| 156 | ZSTD_DUBT_findBetterDictMatch ( |
| 157 | const ZSTD_matchState_t* ms, |
| 158 | const BYTE* const ip, const BYTE* const iend, |
| 159 | size_t* offsetPtr, |
| 160 | size_t bestLength, |
| 161 | U32 nbCompares, |
| 162 | U32 const mls, |
| 163 | const ZSTD_dictMode_e dictMode) |
| 164 | { |
| 165 | const ZSTD_matchState_t * const dms = ms->dictMatchState; |
| 166 | const ZSTD_compressionParameters* const dmsCParams = &dms->cParams; |
| 167 | const U32 * const dictHashTable = dms->hashTable; |
| 168 | U32 const hashLog = dmsCParams->hashLog; |
| 169 | size_t const h = ZSTD_hashPtr(ip, hashLog, mls); |
| 170 | U32 dictMatchIndex = dictHashTable[h]; |
| 171 | |
| 172 | const BYTE* const base = ms->window.base; |
| 173 | const BYTE* const prefixStart = base + ms->window.dictLimit; |
| 174 | U32 const curr = (U32)(ip-base); |
| 175 | const BYTE* const dictBase = dms->window.base; |
| 176 | const BYTE* const dictEnd = dms->window.nextSrc; |
| 177 | U32 const dictHighLimit = (U32)(dms->window.nextSrc - dms->window.base); |
| 178 | U32 const dictLowLimit = dms->window.lowLimit; |
| 179 | U32 const dictIndexDelta = ms->window.lowLimit - dictHighLimit; |
| 180 | |
| 181 | U32* const dictBt = dms->chainTable; |
| 182 | U32 const btLog = dmsCParams->chainLog - 1; |
| 183 | U32 const btMask = (1 << btLog) - 1; |
| 184 | U32 const btLow = (btMask >= dictHighLimit - dictLowLimit) ? dictLowLimit : dictHighLimit - btMask; |
| 185 | |
| 186 | size_t commonLengthSmaller=0, commonLengthLarger=0; |
| 187 | |
| 188 | (void)dictMode; |
| 189 | assert(dictMode == ZSTD_dictMatchState); |
| 190 | |
| 191 | for (; nbCompares && (dictMatchIndex > dictLowLimit); --nbCompares) { |
| 192 | U32* const nextPtr = dictBt + 2*(dictMatchIndex & btMask); |
| 193 | size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ |
| 194 | const BYTE* match = dictBase + dictMatchIndex; |
| 195 | matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); |
| 196 | if (dictMatchIndex+matchLength >= dictHighLimit) |
| 197 | match = base + dictMatchIndex + dictIndexDelta; /* to prepare for next usage of match[matchLength] */ |
| 198 | |
| 199 | if (matchLength > bestLength) { |
| 200 | U32 matchIndex = dictMatchIndex + dictIndexDelta; |
| 201 | if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) ) { |
| 202 | DEBUGLOG(9, "ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u)", |
| 203 | curr, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, OFFSET_TO_OFFBASE(curr - matchIndex), dictMatchIndex, matchIndex); |
| 204 | bestLength = matchLength, *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex); |
| 205 | } |
| 206 | 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 */ |
| 207 | break; /* drop, to guarantee consistency (miss a little bit of compression) */ |
| 208 | } |
| 209 | } |
| 210 | |
| 211 | if (match[matchLength] < ip[matchLength]) { |
| 212 | if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */ |
| 213 | commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ |
| 214 | dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ |
| 215 | } else { |
| 216 | /* match is larger than current */ |
| 217 | if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */ |
| 218 | commonLengthLarger = matchLength; |
| 219 | dictMatchIndex = nextPtr[0]; |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | if (bestLength >= MINMATCH) { |
| 224 | U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offsetPtr); (void)mIndex; |
| 225 | DEBUGLOG(8, "ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)", |
| 226 | curr, (U32)bestLength, (U32)*offsetPtr, mIndex); |
| 227 | } |
| 228 | return bestLength; |
| 229 | |
| 230 | } |
| 231 | |
| 232 | |
| 233 | static size_t |
| 234 | ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms, |
| 235 | const BYTE* const ip, const BYTE* const iend, |
| 236 | size_t* offBasePtr, |
| 237 | U32 const mls, |
| 238 | const ZSTD_dictMode_e dictMode) |
| 239 | { |
| 240 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| 241 | U32* const hashTable = ms->hashTable; |
| 242 | U32 const hashLog = cParams->hashLog; |
| 243 | size_t const h = ZSTD_hashPtr(ip, hashLog, mls); |
| 244 | U32 matchIndex = hashTable[h]; |
| 245 | |
| 246 | const BYTE* const base = ms->window.base; |
| 247 | U32 const curr = (U32)(ip-base); |
| 248 | U32 const windowLow = ZSTD_getLowestMatchIndex(ms, curr, cParams->windowLog); |
| 249 | |
| 250 | U32* const bt = ms->chainTable; |
| 251 | U32 const btLog = cParams->chainLog - 1; |
| 252 | U32 const btMask = (1 << btLog) - 1; |
| 253 | U32 const btLow = (btMask >= curr) ? 0 : curr - btMask; |
| 254 | U32 const unsortLimit = MAX(btLow, windowLow); |
| 255 | |
| 256 | U32* nextCandidate = bt + 2*(matchIndex&btMask); |
| 257 | U32* unsortedMark = bt + 2*(matchIndex&btMask) + 1; |
| 258 | U32 nbCompares = 1U << cParams->searchLog; |
| 259 | U32 nbCandidates = nbCompares; |
| 260 | U32 previousCandidate = 0; |
| 261 | |
| 262 | DEBUGLOG(7, "ZSTD_DUBT_findBestMatch (%u) ", curr); |
| 263 | assert(ip <= iend-8); /* required for h calculation */ |
| 264 | assert(dictMode != ZSTD_dedicatedDictSearch); |
| 265 | |
| 266 | /* reach end of unsorted candidates list */ |
| 267 | while ( (matchIndex > unsortLimit) |
| 268 | && (*unsortedMark == ZSTD_DUBT_UNSORTED_MARK) |
| 269 | && (nbCandidates > 1) ) { |
| 270 | DEBUGLOG(8, "ZSTD_DUBT_findBestMatch: candidate %u is unsorted", |
| 271 | matchIndex); |
| 272 | *unsortedMark = previousCandidate; /* the unsortedMark becomes a reversed chain, to move up back to original position */ |
| 273 | previousCandidate = matchIndex; |
| 274 | matchIndex = *nextCandidate; |
| 275 | nextCandidate = bt + 2*(matchIndex&btMask); |
| 276 | unsortedMark = bt + 2*(matchIndex&btMask) + 1; |
| 277 | nbCandidates --; |
| 278 | } |
| 279 | |
| 280 | /* nullify last candidate if it's still unsorted |
| 281 | * simplification, detrimental to compression ratio, beneficial for speed */ |
| 282 | if ( (matchIndex > unsortLimit) |
| 283 | && (*unsortedMark==ZSTD_DUBT_UNSORTED_MARK) ) { |
| 284 | DEBUGLOG(7, "ZSTD_DUBT_findBestMatch: nullify last unsorted candidate %u", |
| 285 | matchIndex); |
| 286 | *nextCandidate = *unsortedMark = 0; |
| 287 | } |
| 288 | |
| 289 | /* batch sort stacked candidates */ |
| 290 | matchIndex = previousCandidate; |
| 291 | while (matchIndex) { /* will end on matchIndex == 0 */ |
| 292 | U32* const nextCandidateIdxPtr = bt + 2*(matchIndex&btMask) + 1; |
| 293 | U32 const nextCandidateIdx = *nextCandidateIdxPtr; |
| 294 | ZSTD_insertDUBT1(ms, matchIndex, iend, |
| 295 | nbCandidates, unsortLimit, dictMode); |
| 296 | matchIndex = nextCandidateIdx; |
| 297 | nbCandidates++; |
| 298 | } |
| 299 | |
| 300 | /* find longest match */ |
| 301 | { size_t commonLengthSmaller = 0, commonLengthLarger = 0; |
| 302 | const BYTE* const dictBase = ms->window.dictBase; |
| 303 | const U32 dictLimit = ms->window.dictLimit; |
| 304 | const BYTE* const dictEnd = dictBase + dictLimit; |
| 305 | const BYTE* const prefixStart = base + dictLimit; |
| 306 | U32* smallerPtr = bt + 2*(curr&btMask); |
| 307 | U32* largerPtr = bt + 2*(curr&btMask) + 1; |
| 308 | U32 matchEndIdx = curr + 8 + 1; |
| 309 | U32 dummy32; /* to be nullified at the end */ |
| 310 | size_t bestLength = 0; |
| 311 | |
| 312 | matchIndex = hashTable[h]; |
| 313 | hashTable[h] = curr; /* Update Hash Table */ |
| 314 | |
| 315 | for (; nbCompares && (matchIndex > windowLow); --nbCompares) { |
| 316 | U32* const nextPtr = bt + 2*(matchIndex & btMask); |
| 317 | size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ |
| 318 | const BYTE* match; |
| 319 | |
| 320 | if ((dictMode != ZSTD_extDict) || (matchIndex+matchLength >= dictLimit)) { |
| 321 | match = base + matchIndex; |
| 322 | matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); |
| 323 | } else { |
| 324 | match = dictBase + matchIndex; |
| 325 | matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); |
| 326 | if (matchIndex+matchLength >= dictLimit) |
| 327 | match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ |
| 328 | } |
| 329 | |
| 330 | if (matchLength > bestLength) { |
| 331 | if (matchLength > matchEndIdx - matchIndex) |
| 332 | matchEndIdx = matchIndex + (U32)matchLength; |
| 333 | if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr - matchIndex + 1) - ZSTD_highbit32((U32)*offBasePtr)) ) |
| 334 | bestLength = matchLength, *offBasePtr = OFFSET_TO_OFFBASE(curr - matchIndex); |
| 335 | if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ |
| 336 | if (dictMode == ZSTD_dictMatchState) { |
| 337 | nbCompares = 0; /* in addition to avoiding checking any |
| 338 | * further in this loop, make sure we |
| 339 | * skip checking in the dictionary. */ |
| 340 | } |
| 341 | break; /* drop, to guarantee consistency (miss a little bit of compression) */ |
| 342 | } |
| 343 | } |
| 344 | |
| 345 | if (match[matchLength] < ip[matchLength]) { |
| 346 | /* match is smaller than current */ |
| 347 | *smallerPtr = matchIndex; /* update smaller idx */ |
| 348 | commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ |
| 349 | if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ |
| 350 | smallerPtr = nextPtr+1; /* new "smaller" => larger of match */ |
| 351 | matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ |
| 352 | } else { |
| 353 | /* match is larger than current */ |
| 354 | *largerPtr = matchIndex; |
| 355 | commonLengthLarger = matchLength; |
| 356 | if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ |
| 357 | largerPtr = nextPtr; |
| 358 | matchIndex = nextPtr[0]; |
| 359 | } } |
| 360 | |
| 361 | *smallerPtr = *largerPtr = 0; |
| 362 | |
| 363 | assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ |
| 364 | if (dictMode == ZSTD_dictMatchState && nbCompares) { |
| 365 | bestLength = ZSTD_DUBT_findBetterDictMatch( |
| 366 | ms, ip, iend, |
| 367 | offBasePtr, bestLength, nbCompares, |
| 368 | mls, dictMode); |
| 369 | } |
| 370 | |
| 371 | assert(matchEndIdx > curr+8); /* ensure nextToUpdate is increased */ |
| 372 | ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ |
| 373 | if (bestLength >= MINMATCH) { |
| 374 | U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offBasePtr); (void)mIndex; |
| 375 | DEBUGLOG(8, "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)", |
| 376 | curr, (U32)bestLength, (U32)*offBasePtr, mIndex); |
| 377 | } |
| 378 | return bestLength; |
| 379 | } |
| 380 | } |
| 381 | |
| 382 | |
| 383 | /** ZSTD_BtFindBestMatch() : Tree updater, providing best match */ |
| 384 | FORCE_INLINE_TEMPLATE size_t |
| 385 | ZSTD_BtFindBestMatch( ZSTD_matchState_t* ms, |
| 386 | const BYTE* const ip, const BYTE* const iLimit, |
| 387 | size_t* offBasePtr, |
| 388 | const U32 mls /* template */, |
| 389 | const ZSTD_dictMode_e dictMode) |
| 390 | { |
| 391 | DEBUGLOG(7, "ZSTD_BtFindBestMatch"); |
| 392 | if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */ |
| 393 | ZSTD_updateDUBT(ms, ip, iLimit, mls); |
| 394 | return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offBasePtr, mls, dictMode); |
| 395 | } |
| 396 | |
| 397 | /*********************************** |
| 398 | * Dedicated dict search |
| 399 | ***********************************/ |
| 400 | |
| 401 | void ZSTD_dedicatedDictSearch_lazy_loadDictionary(ZSTD_matchState_t* ms, const BYTE* const ip) |
| 402 | { |
| 403 | const BYTE* const base = ms->window.base; |
| 404 | U32 const target = (U32)(ip - base); |
| 405 | U32* const hashTable = ms->hashTable; |
| 406 | U32* const chainTable = ms->chainTable; |
| 407 | U32 const chainSize = 1 << ms->cParams.chainLog; |
| 408 | U32 idx = ms->nextToUpdate; |
| 409 | U32 const minChain = chainSize < target - idx ? target - chainSize : idx; |
| 410 | U32 const bucketSize = 1 << ZSTD_LAZY_DDSS_BUCKET_LOG; |
| 411 | U32 const cacheSize = bucketSize - 1; |
| 412 | U32 const chainAttempts = (1 << ms->cParams.searchLog) - cacheSize; |
| 413 | U32 const chainLimit = chainAttempts > 255 ? 255 : chainAttempts; |
| 414 | |
| 415 | /* We know the hashtable is oversized by a factor of `bucketSize`. |
| 416 | * We are going to temporarily pretend `bucketSize == 1`, keeping only a |
| 417 | * single entry. We will use the rest of the space to construct a temporary |
| 418 | * chaintable. |
| 419 | */ |
| 420 | U32 const hashLog = ms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG; |
| 421 | U32* const tmpHashTable = hashTable; |
| 422 | U32* const tmpChainTable = hashTable + ((size_t)1 << hashLog); |
| 423 | U32 const tmpChainSize = (U32)((1 << ZSTD_LAZY_DDSS_BUCKET_LOG) - 1) << hashLog; |
| 424 | U32 const tmpMinChain = tmpChainSize < target ? target - tmpChainSize : idx; |
| 425 | U32 hashIdx; |
| 426 | |
| 427 | assert(ms->cParams.chainLog <= 24); |
| 428 | assert(ms->cParams.hashLog > ms->cParams.chainLog); |
| 429 | assert(idx != 0); |
| 430 | assert(tmpMinChain <= minChain); |
| 431 | |
| 432 | /* fill conventional hash table and conventional chain table */ |
| 433 | for ( ; idx < target; idx++) { |
| 434 | U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch); |
| 435 | if (idx >= tmpMinChain) { |
| 436 | tmpChainTable[idx - tmpMinChain] = hashTable[h]; |
| 437 | } |
| 438 | tmpHashTable[h] = idx; |
| 439 | } |
| 440 | |
| 441 | /* sort chains into ddss chain table */ |
| 442 | { |
| 443 | U32 chainPos = 0; |
| 444 | for (hashIdx = 0; hashIdx < (1U << hashLog); hashIdx++) { |
| 445 | U32 count; |
| 446 | U32 countBeyondMinChain = 0; |
| 447 | U32 i = tmpHashTable[hashIdx]; |
| 448 | for (count = 0; i >= tmpMinChain && count < cacheSize; count++) { |
| 449 | /* skip through the chain to the first position that won't be |
| 450 | * in the hash cache bucket */ |
| 451 | if (i < minChain) { |
| 452 | countBeyondMinChain++; |
| 453 | } |
| 454 | i = tmpChainTable[i - tmpMinChain]; |
| 455 | } |
| 456 | if (count == cacheSize) { |
| 457 | for (count = 0; count < chainLimit;) { |
| 458 | if (i < minChain) { |
| 459 | if (!i || ++countBeyondMinChain > cacheSize) { |
| 460 | /* only allow pulling `cacheSize` number of entries |
| 461 | * into the cache or chainTable beyond `minChain`, |
| 462 | * to replace the entries pulled out of the |
| 463 | * chainTable into the cache. This lets us reach |
| 464 | * back further without increasing the total number |
| 465 | * of entries in the chainTable, guaranteeing the |
| 466 | * DDSS chain table will fit into the space |
| 467 | * allocated for the regular one. */ |
| 468 | break; |
| 469 | } |
| 470 | } |
| 471 | chainTable[chainPos++] = i; |
| 472 | count++; |
| 473 | if (i < tmpMinChain) { |
| 474 | break; |
| 475 | } |
| 476 | i = tmpChainTable[i - tmpMinChain]; |
| 477 | } |
| 478 | } else { |
| 479 | count = 0; |
| 480 | } |
| 481 | if (count) { |
| 482 | tmpHashTable[hashIdx] = ((chainPos - count) << 8) + count; |
| 483 | } else { |
| 484 | tmpHashTable[hashIdx] = 0; |
| 485 | } |
| 486 | } |
| 487 | assert(chainPos <= chainSize); /* I believe this is guaranteed... */ |
| 488 | } |
| 489 | |
| 490 | /* move chain pointers into the last entry of each hash bucket */ |
| 491 | for (hashIdx = (1 << hashLog); hashIdx; ) { |
| 492 | U32 const bucketIdx = --hashIdx << ZSTD_LAZY_DDSS_BUCKET_LOG; |
| 493 | U32 const chainPackedPointer = tmpHashTable[hashIdx]; |
| 494 | U32 i; |
| 495 | for (i = 0; i < cacheSize; i++) { |
| 496 | hashTable[bucketIdx + i] = 0; |
| 497 | } |
| 498 | hashTable[bucketIdx + bucketSize - 1] = chainPackedPointer; |
| 499 | } |
| 500 | |
| 501 | /* fill the buckets of the hash table */ |
| 502 | for (idx = ms->nextToUpdate; idx < target; idx++) { |
| 503 | U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch) |
| 504 | << ZSTD_LAZY_DDSS_BUCKET_LOG; |
| 505 | U32 i; |
| 506 | /* Shift hash cache down 1. */ |
| 507 | for (i = cacheSize - 1; i; i--) |
| 508 | hashTable[h + i] = hashTable[h + i - 1]; |
| 509 | hashTable[h] = idx; |
| 510 | } |
| 511 | |
| 512 | ms->nextToUpdate = target; |
| 513 | } |
| 514 | |
| 515 | /* Returns the longest match length found in the dedicated dict search structure. |
| 516 | * If none are longer than the argument ml, then ml will be returned. |
| 517 | */ |
| 518 | FORCE_INLINE_TEMPLATE |
| 519 | size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nbAttempts, |
| 520 | const ZSTD_matchState_t* const dms, |
| 521 | const BYTE* const ip, const BYTE* const iLimit, |
| 522 | const BYTE* const prefixStart, const U32 curr, |
| 523 | const U32 dictLimit, const size_t ddsIdx) { |
| 524 | const U32 ddsLowestIndex = dms->window.dictLimit; |
| 525 | const BYTE* const ddsBase = dms->window.base; |
| 526 | const BYTE* const ddsEnd = dms->window.nextSrc; |
| 527 | const U32 ddsSize = (U32)(ddsEnd - ddsBase); |
| 528 | const U32 ddsIndexDelta = dictLimit - ddsSize; |
| 529 | const U32 bucketSize = (1 << ZSTD_LAZY_DDSS_BUCKET_LOG); |
| 530 | const U32 bucketLimit = nbAttempts < bucketSize - 1 ? nbAttempts : bucketSize - 1; |
| 531 | U32 ddsAttempt; |
| 532 | U32 matchIndex; |
| 533 | |
| 534 | for (ddsAttempt = 0; ddsAttempt < bucketSize - 1; ddsAttempt++) { |
| 535 | PREFETCH_L1(ddsBase + dms->hashTable[ddsIdx + ddsAttempt]); |
| 536 | } |
| 537 | |
| 538 | { |
| 539 | U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1]; |
| 540 | U32 const chainIndex = chainPackedPointer >> 8; |
| 541 | |
| 542 | PREFETCH_L1(&dms->chainTable[chainIndex]); |
| 543 | } |
| 544 | |
| 545 | for (ddsAttempt = 0; ddsAttempt < bucketLimit; ddsAttempt++) { |
| 546 | size_t currentMl=0; |
| 547 | const BYTE* match; |
| 548 | matchIndex = dms->hashTable[ddsIdx + ddsAttempt]; |
| 549 | match = ddsBase + matchIndex; |
| 550 | |
| 551 | if (!matchIndex) { |
| 552 | return ml; |
| 553 | } |
| 554 | |
| 555 | /* guaranteed by table construction */ |
| 556 | (void)ddsLowestIndex; |
| 557 | assert(matchIndex >= ddsLowestIndex); |
| 558 | assert(match+4 <= ddsEnd); |
| 559 | if (MEM_read32(match) == MEM_read32(ip)) { |
| 560 | /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
| 561 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4; |
| 562 | } |
| 563 | |
| 564 | /* save best solution */ |
| 565 | if (currentMl > ml) { |
| 566 | ml = currentMl; |
| 567 | *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta)); |
| 568 | if (ip+currentMl == iLimit) { |
| 569 | /* best possible, avoids read overflow on next attempt */ |
| 570 | return ml; |
| 571 | } |
| 572 | } |
| 573 | } |
| 574 | |
| 575 | { |
| 576 | U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1]; |
| 577 | U32 chainIndex = chainPackedPointer >> 8; |
| 578 | U32 const chainLength = chainPackedPointer & 0xFF; |
| 579 | U32 const chainAttempts = nbAttempts - ddsAttempt; |
| 580 | U32 const chainLimit = chainAttempts > chainLength ? chainLength : chainAttempts; |
| 581 | U32 chainAttempt; |
| 582 | |
| 583 | for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++) { |
| 584 | PREFETCH_L1(ddsBase + dms->chainTable[chainIndex + chainAttempt]); |
| 585 | } |
| 586 | |
| 587 | for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++, chainIndex++) { |
| 588 | size_t currentMl=0; |
| 589 | const BYTE* match; |
| 590 | matchIndex = dms->chainTable[chainIndex]; |
| 591 | match = ddsBase + matchIndex; |
| 592 | |
| 593 | /* guaranteed by table construction */ |
| 594 | assert(matchIndex >= ddsLowestIndex); |
| 595 | assert(match+4 <= ddsEnd); |
| 596 | if (MEM_read32(match) == MEM_read32(ip)) { |
| 597 | /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
| 598 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4; |
| 599 | } |
| 600 | |
| 601 | /* save best solution */ |
| 602 | if (currentMl > ml) { |
| 603 | ml = currentMl; |
| 604 | *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta)); |
| 605 | if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ |
| 606 | } |
| 607 | } |
| 608 | } |
| 609 | return ml; |
| 610 | } |
| 611 | |
| 612 | |
| 613 | /* ********************************* |
| 614 | * Hash Chain |
| 615 | ***********************************/ |
| 616 | #define NEXT_IN_CHAIN(d, mask) chainTable[(d) & (mask)] |
| 617 | |
| 618 | /* Update chains up to ip (excluded) |
| 619 | Assumption : always within prefix (i.e. not within extDict) */ |
| 620 | FORCE_INLINE_TEMPLATE U32 ZSTD_insertAndFindFirstIndex_internal( |
| 621 | ZSTD_matchState_t* ms, |
| 622 | const ZSTD_compressionParameters* const cParams, |
| 623 | const BYTE* ip, U32 const mls, U32 const lazySkipping) |
| 624 | { |
| 625 | U32* const hashTable = ms->hashTable; |
| 626 | const U32 hashLog = cParams->hashLog; |
| 627 | U32* const chainTable = ms->chainTable; |
| 628 | const U32 chainMask = (1 << cParams->chainLog) - 1; |
| 629 | const BYTE* const base = ms->window.base; |
| 630 | const U32 target = (U32)(ip - base); |
| 631 | U32 idx = ms->nextToUpdate; |
| 632 | |
| 633 | while(idx < target) { /* catch up */ |
| 634 | size_t const h = ZSTD_hashPtr(base+idx, hashLog, mls); |
| 635 | NEXT_IN_CHAIN(idx, chainMask) = hashTable[h]; |
| 636 | hashTable[h] = idx; |
| 637 | idx++; |
| 638 | /* Stop inserting every position when in the lazy skipping mode. */ |
| 639 | if (lazySkipping) |
| 640 | break; |
| 641 | } |
| 642 | |
| 643 | ms->nextToUpdate = target; |
| 644 | return hashTable[ZSTD_hashPtr(ip, hashLog, mls)]; |
| 645 | } |
| 646 | |
| 647 | U32 ZSTD_insertAndFindFirstIndex(ZSTD_matchState_t* ms, const BYTE* ip) { |
| 648 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| 649 | return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, ms->cParams.minMatch, /* lazySkipping*/ 0); |
| 650 | } |
| 651 | |
| 652 | /* inlining is important to hardwire a hot branch (template emulation) */ |
| 653 | FORCE_INLINE_TEMPLATE |
| 654 | size_t ZSTD_HcFindBestMatch( |
| 655 | ZSTD_matchState_t* ms, |
| 656 | const BYTE* const ip, const BYTE* const iLimit, |
| 657 | size_t* offsetPtr, |
| 658 | const U32 mls, const ZSTD_dictMode_e dictMode) |
| 659 | { |
| 660 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| 661 | U32* const chainTable = ms->chainTable; |
| 662 | const U32 chainSize = (1 << cParams->chainLog); |
| 663 | const U32 chainMask = chainSize-1; |
| 664 | const BYTE* const base = ms->window.base; |
| 665 | const BYTE* const dictBase = ms->window.dictBase; |
| 666 | const U32 dictLimit = ms->window.dictLimit; |
| 667 | const BYTE* const prefixStart = base + dictLimit; |
| 668 | const BYTE* const dictEnd = dictBase + dictLimit; |
| 669 | const U32 curr = (U32)(ip-base); |
| 670 | const U32 maxDistance = 1U << cParams->windowLog; |
| 671 | const U32 lowestValid = ms->window.lowLimit; |
| 672 | const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid; |
| 673 | const U32 isDictionary = (ms->loadedDictEnd != 0); |
| 674 | const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance; |
| 675 | const U32 minChain = curr > chainSize ? curr - chainSize : 0; |
| 676 | U32 nbAttempts = 1U << cParams->searchLog; |
| 677 | size_t ml=4-1; |
| 678 | |
| 679 | const ZSTD_matchState_t* const dms = ms->dictMatchState; |
| 680 | const U32 ddsHashLog = dictMode == ZSTD_dedicatedDictSearch |
| 681 | ? dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG : 0; |
| 682 | const size_t ddsIdx = dictMode == ZSTD_dedicatedDictSearch |
| 683 | ? ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG : 0; |
| 684 | |
| 685 | U32 matchIndex; |
| 686 | |
| 687 | if (dictMode == ZSTD_dedicatedDictSearch) { |
| 688 | const U32* entry = &dms->hashTable[ddsIdx]; |
| 689 | PREFETCH_L1(entry); |
| 690 | } |
| 691 | |
| 692 | /* HC4 match finder */ |
| 693 | matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls, ms->lazySkipping); |
| 694 | |
| 695 | for ( ; (matchIndex>=lowLimit) & (nbAttempts>0) ; nbAttempts--) { |
| 696 | size_t currentMl=0; |
| 697 | if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { |
| 698 | const BYTE* const match = base + matchIndex; |
| 699 | assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */ |
| 700 | /* read 4B starting from (match + ml + 1 - sizeof(U32)) */ |
| 701 | if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */ |
| 702 | currentMl = ZSTD_count(ip, match, iLimit); |
| 703 | } else { |
| 704 | const BYTE* const match = dictBase + matchIndex; |
| 705 | assert(match+4 <= dictEnd); |
| 706 | if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
| 707 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4; |
| 708 | } |
| 709 | |
| 710 | /* save best solution */ |
| 711 | if (currentMl > ml) { |
| 712 | ml = currentMl; |
| 713 | *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex); |
| 714 | if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ |
| 715 | } |
| 716 | |
| 717 | if (matchIndex <= minChain) break; |
| 718 | matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask); |
| 719 | } |
| 720 | |
| 721 | assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ |
| 722 | if (dictMode == ZSTD_dedicatedDictSearch) { |
| 723 | ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts, dms, |
| 724 | ip, iLimit, prefixStart, curr, dictLimit, ddsIdx); |
| 725 | } else if (dictMode == ZSTD_dictMatchState) { |
| 726 | const U32* const dmsChainTable = dms->chainTable; |
| 727 | const U32 dmsChainSize = (1 << dms->cParams.chainLog); |
| 728 | const U32 dmsChainMask = dmsChainSize - 1; |
| 729 | const U32 dmsLowestIndex = dms->window.dictLimit; |
| 730 | const BYTE* const dmsBase = dms->window.base; |
| 731 | const BYTE* const dmsEnd = dms->window.nextSrc; |
| 732 | const U32 dmsSize = (U32)(dmsEnd - dmsBase); |
| 733 | const U32 dmsIndexDelta = dictLimit - dmsSize; |
| 734 | const U32 dmsMinChain = dmsSize > dmsChainSize ? dmsSize - dmsChainSize : 0; |
| 735 | |
| 736 | matchIndex = dms->hashTable[ZSTD_hashPtr(ip, dms->cParams.hashLog, mls)]; |
| 737 | |
| 738 | for ( ; (matchIndex>=dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--) { |
| 739 | size_t currentMl=0; |
| 740 | const BYTE* const match = dmsBase + matchIndex; |
| 741 | assert(match+4 <= dmsEnd); |
| 742 | if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
| 743 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4; |
| 744 | |
| 745 | /* save best solution */ |
| 746 | if (currentMl > ml) { |
| 747 | ml = currentMl; |
| 748 | assert(curr > matchIndex + dmsIndexDelta); |
| 749 | *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta)); |
| 750 | if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ |
| 751 | } |
| 752 | |
| 753 | if (matchIndex <= dmsMinChain) break; |
| 754 | |
| 755 | matchIndex = dmsChainTable[matchIndex & dmsChainMask]; |
| 756 | } |
| 757 | } |
| 758 | |
| 759 | return ml; |
| 760 | } |
| 761 | |
| 762 | /* ********************************* |
| 763 | * (SIMD) Row-based matchfinder |
| 764 | ***********************************/ |
| 765 | /* Constants for row-based hash */ |
| 766 | #define ZSTD_ROW_HASH_TAG_MASK ((1u << ZSTD_ROW_HASH_TAG_BITS) - 1) |
| 767 | #define ZSTD_ROW_HASH_MAX_ENTRIES 64 /* absolute maximum number of entries per row, for all configurations */ |
| 768 | |
| 769 | #define ZSTD_ROW_HASH_CACHE_MASK (ZSTD_ROW_HASH_CACHE_SIZE - 1) |
| 770 | |
| 771 | typedef U64 ZSTD_VecMask; /* Clarifies when we are interacting with a U64 representing a mask of matches */ |
| 772 | |
| 773 | /* ZSTD_VecMask_next(): |
| 774 | * Starting from the LSB, returns the idx of the next non-zero bit. |
| 775 | * Basically counting the nb of trailing zeroes. |
| 776 | */ |
| 777 | MEM_STATIC U32 ZSTD_VecMask_next(ZSTD_VecMask val) { |
| 778 | return ZSTD_countTrailingZeros64(val); |
| 779 | } |
| 780 | |
| 781 | /* ZSTD_row_nextIndex(): |
| 782 | * Returns the next index to insert at within a tagTable row, and updates the "head" |
| 783 | * value to reflect the update. Essentially cycles backwards from [1, {entries per row}) |
| 784 | */ |
| 785 | FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextIndex(BYTE* const tagRow, U32 const rowMask) { |
| 786 | U32 next = (*tagRow-1) & rowMask; |
| 787 | next += (next == 0) ? rowMask : 0; /* skip first position */ |
| 788 | *tagRow = (BYTE)next; |
| 789 | return next; |
| 790 | } |
| 791 | |
| 792 | /* ZSTD_isAligned(): |
| 793 | * Checks that a pointer is aligned to "align" bytes which must be a power of 2. |
| 794 | */ |
| 795 | MEM_STATIC int ZSTD_isAligned(void const* ptr, size_t align) { |
| 796 | assert((align & (align - 1)) == 0); |
| 797 | return (((size_t)ptr) & (align - 1)) == 0; |
| 798 | } |
| 799 | |
| 800 | /* ZSTD_row_prefetch(): |
| 801 | * Performs prefetching for the hashTable and tagTable at a given row. |
| 802 | */ |
| 803 | FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, BYTE const* tagTable, U32 const relRow, U32 const rowLog) { |
| 804 | PREFETCH_L1(hashTable + relRow); |
| 805 | if (rowLog >= 5) { |
| 806 | PREFETCH_L1(hashTable + relRow + 16); |
| 807 | /* Note: prefetching more of the hash table does not appear to be beneficial for 128-entry rows */ |
| 808 | } |
| 809 | PREFETCH_L1(tagTable + relRow); |
| 810 | if (rowLog == 6) { |
| 811 | PREFETCH_L1(tagTable + relRow + 32); |
| 812 | } |
| 813 | assert(rowLog == 4 || rowLog == 5 || rowLog == 6); |
| 814 | assert(ZSTD_isAligned(hashTable + relRow, 64)); /* prefetched hash row always 64-byte aligned */ |
| 815 | assert(ZSTD_isAligned(tagTable + relRow, (size_t)1 << rowLog)); /* prefetched tagRow sits on correct multiple of bytes (32,64,128) */ |
| 816 | } |
| 817 | |
| 818 | /* ZSTD_row_fillHashCache(): |
| 819 | * Fill up the hash cache starting at idx, prefetching up to ZSTD_ROW_HASH_CACHE_SIZE entries, |
| 820 | * but not beyond iLimit. |
| 821 | */ |
| 822 | FORCE_INLINE_TEMPLATE void ZSTD_row_fillHashCache(ZSTD_matchState_t* ms, const BYTE* base, |
| 823 | U32 const rowLog, U32 const mls, |
| 824 | U32 idx, const BYTE* const iLimit) |
| 825 | { |
| 826 | U32 const* const hashTable = ms->hashTable; |
| 827 | BYTE const* const tagTable = ms->tagTable; |
| 828 | U32 const hashLog = ms->rowHashLog; |
| 829 | U32 const maxElemsToPrefetch = (base + idx) > iLimit ? 0 : (U32)(iLimit - (base + idx) + 1); |
| 830 | U32 const lim = idx + MIN(ZSTD_ROW_HASH_CACHE_SIZE, maxElemsToPrefetch); |
| 831 | |
| 832 | for (; idx < lim; ++idx) { |
| 833 | U32 const hash = (U32)ZSTD_hashPtrSalted(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt); |
| 834 | U32 const row = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
| 835 | ZSTD_row_prefetch(hashTable, tagTable, row, rowLog); |
| 836 | ms->hashCache[idx & ZSTD_ROW_HASH_CACHE_MASK] = hash; |
| 837 | } |
| 838 | |
| 839 | DEBUGLOG(6, "ZSTD_row_fillHashCache(): [%u %u %u %u %u %u %u %u]", ms->hashCache[0], ms->hashCache[1], |
| 840 | ms->hashCache[2], ms->hashCache[3], ms->hashCache[4], |
| 841 | ms->hashCache[5], ms->hashCache[6], ms->hashCache[7]); |
| 842 | } |
| 843 | |
| 844 | /* ZSTD_row_nextCachedHash(): |
| 845 | * Returns the hash of base + idx, and replaces the hash in the hash cache with the byte at |
| 846 | * base + idx + ZSTD_ROW_HASH_CACHE_SIZE. Also prefetches the appropriate rows from hashTable and tagTable. |
| 847 | */ |
| 848 | FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextCachedHash(U32* cache, U32 const* hashTable, |
| 849 | BYTE const* tagTable, BYTE const* base, |
| 850 | U32 idx, U32 const hashLog, |
| 851 | U32 const rowLog, U32 const mls, |
| 852 | U64 const hashSalt) |
| 853 | { |
| 854 | U32 const newHash = (U32)ZSTD_hashPtrSalted(base+idx+ZSTD_ROW_HASH_CACHE_SIZE, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt); |
| 855 | U32 const row = (newHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
| 856 | ZSTD_row_prefetch(hashTable, tagTable, row, rowLog); |
| 857 | { U32 const hash = cache[idx & ZSTD_ROW_HASH_CACHE_MASK]; |
| 858 | cache[idx & ZSTD_ROW_HASH_CACHE_MASK] = newHash; |
| 859 | return hash; |
| 860 | } |
| 861 | } |
| 862 | |
| 863 | /* ZSTD_row_update_internalImpl(): |
| 864 | * Updates the hash table with positions starting from updateStartIdx until updateEndIdx. |
| 865 | */ |
| 866 | FORCE_INLINE_TEMPLATE void ZSTD_row_update_internalImpl(ZSTD_matchState_t* ms, |
| 867 | U32 updateStartIdx, U32 const updateEndIdx, |
| 868 | U32 const mls, U32 const rowLog, |
| 869 | U32 const rowMask, U32 const useCache) |
| 870 | { |
| 871 | U32* const hashTable = ms->hashTable; |
| 872 | BYTE* const tagTable = ms->tagTable; |
| 873 | U32 const hashLog = ms->rowHashLog; |
| 874 | const BYTE* const base = ms->window.base; |
| 875 | |
| 876 | DEBUGLOG(6, "ZSTD_row_update_internalImpl(): updateStartIdx=%u, updateEndIdx=%u", updateStartIdx, updateEndIdx); |
| 877 | for (; updateStartIdx < updateEndIdx; ++updateStartIdx) { |
| 878 | U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, updateStartIdx, hashLog, rowLog, mls, ms->hashSalt) |
| 879 | : (U32)ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt); |
| 880 | U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
| 881 | U32* const row = hashTable + relRow; |
| 882 | BYTE* tagRow = tagTable + relRow; |
| 883 | U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask); |
| 884 | |
| 885 | assert(hash == ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt)); |
| 886 | tagRow[pos] = hash & ZSTD_ROW_HASH_TAG_MASK; |
| 887 | row[pos] = updateStartIdx; |
| 888 | } |
| 889 | } |
| 890 | |
| 891 | /* ZSTD_row_update_internal(): |
| 892 | * Inserts the byte at ip into the appropriate position in the hash table, and updates ms->nextToUpdate. |
| 893 | * Skips sections of long matches as is necessary. |
| 894 | */ |
| 895 | FORCE_INLINE_TEMPLATE void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const BYTE* ip, |
| 896 | U32 const mls, U32 const rowLog, |
| 897 | U32 const rowMask, U32 const useCache) |
| 898 | { |
| 899 | U32 idx = ms->nextToUpdate; |
| 900 | const BYTE* const base = ms->window.base; |
| 901 | const U32 target = (U32)(ip - base); |
| 902 | const U32 kSkipThreshold = 384; |
| 903 | const U32 kMaxMatchStartPositionsToUpdate = 96; |
| 904 | const U32 kMaxMatchEndPositionsToUpdate = 32; |
| 905 | |
| 906 | if (useCache) { |
| 907 | /* Only skip positions when using hash cache, i.e. |
| 908 | * if we are loading a dict, don't skip anything. |
| 909 | * If we decide to skip, then we only update a set number |
| 910 | * of positions at the beginning and end of the match. |
| 911 | */ |
| 912 | if (UNLIKELY(target - idx > kSkipThreshold)) { |
| 913 | U32 const bound = idx + kMaxMatchStartPositionsToUpdate; |
| 914 | ZSTD_row_update_internalImpl(ms, idx, bound, mls, rowLog, rowMask, useCache); |
| 915 | idx = target - kMaxMatchEndPositionsToUpdate; |
| 916 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, idx, ip+1); |
| 917 | } |
| 918 | } |
| 919 | assert(target >= idx); |
| 920 | ZSTD_row_update_internalImpl(ms, idx, target, mls, rowLog, rowMask, useCache); |
| 921 | ms->nextToUpdate = target; |
| 922 | } |
| 923 | |
| 924 | /* ZSTD_row_update(): |
| 925 | * External wrapper for ZSTD_row_update_internal(). Used for filling the hashtable during dictionary |
| 926 | * processing. |
| 927 | */ |
| 928 | void ZSTD_row_update(ZSTD_matchState_t* const ms, const BYTE* ip) { |
| 929 | const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); |
| 930 | const U32 rowMask = (1u << rowLog) - 1; |
| 931 | const U32 mls = MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */); |
| 932 | |
| 933 | DEBUGLOG(5, "ZSTD_row_update(), rowLog=%u", rowLog); |
| 934 | ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 0 /* don't use cache */); |
| 935 | } |
| 936 | |
| 937 | /* Returns the mask width of bits group of which will be set to 1. Given not all |
| 938 | * architectures have easy movemask instruction, this helps to iterate over |
| 939 | * groups of bits easier and faster. |
| 940 | */ |
| 941 | FORCE_INLINE_TEMPLATE U32 |
| 942 | ZSTD_row_matchMaskGroupWidth(const U32 rowEntries) |
| 943 | { |
| 944 | assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64); |
| 945 | assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES); |
| 946 | (void)rowEntries; |
| 947 | #if defined(ZSTD_ARCH_ARM_NEON) |
| 948 | /* NEON path only works for little endian */ |
| 949 | if (!MEM_isLittleEndian()) { |
| 950 | return 1; |
| 951 | } |
| 952 | if (rowEntries == 16) { |
| 953 | return 4; |
| 954 | } |
| 955 | if (rowEntries == 32) { |
| 956 | return 2; |
| 957 | } |
| 958 | if (rowEntries == 64) { |
| 959 | return 1; |
| 960 | } |
| 961 | #endif |
| 962 | return 1; |
| 963 | } |
| 964 | |
| 965 | #if defined(ZSTD_ARCH_X86_SSE2) |
| 966 | FORCE_INLINE_TEMPLATE ZSTD_VecMask |
| 967 | ZSTD_row_getSSEMask(int nbChunks, const BYTE* const src, const BYTE tag, const U32 head) |
| 968 | { |
| 969 | const __m128i comparisonMask = _mm_set1_epi8((char)tag); |
| 970 | int matches[4] = {0}; |
| 971 | int i; |
| 972 | assert(nbChunks == 1 || nbChunks == 2 || nbChunks == 4); |
| 973 | for (i=0; i<nbChunks; i++) { |
| 974 | const __m128i chunk = _mm_loadu_si128((const __m128i*)(const void*)(src + 16*i)); |
| 975 | const __m128i equalMask = _mm_cmpeq_epi8(chunk, comparisonMask); |
| 976 | matches[i] = _mm_movemask_epi8(equalMask); |
| 977 | } |
| 978 | if (nbChunks == 1) return ZSTD_rotateRight_U16((U16)matches[0], head); |
| 979 | if (nbChunks == 2) return ZSTD_rotateRight_U32((U32)matches[1] << 16 | (U32)matches[0], head); |
| 980 | assert(nbChunks == 4); |
| 981 | return ZSTD_rotateRight_U64((U64)matches[3] << 48 | (U64)matches[2] << 32 | (U64)matches[1] << 16 | (U64)matches[0], head); |
| 982 | } |
| 983 | #endif |
| 984 | |
| 985 | #if defined(ZSTD_ARCH_ARM_NEON) |
| 986 | FORCE_INLINE_TEMPLATE ZSTD_VecMask |
| 987 | ZSTD_row_getNEONMask(const U32 rowEntries, const BYTE* const src, const BYTE tag, const U32 headGrouped) |
| 988 | { |
| 989 | assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64); |
| 990 | if (rowEntries == 16) { |
| 991 | /* vshrn_n_u16 shifts by 4 every u16 and narrows to 8 lower bits. |
| 992 | * After that groups of 4 bits represent the equalMask. We lower |
| 993 | * all bits except the highest in these groups by doing AND with |
| 994 | * 0x88 = 0b10001000. |
| 995 | */ |
| 996 | const uint8x16_t chunk = vld1q_u8(src); |
| 997 | const uint16x8_t equalMask = vreinterpretq_u16_u8(vceqq_u8(chunk, vdupq_n_u8(tag))); |
| 998 | const uint8x8_t res = vshrn_n_u16(equalMask, 4); |
| 999 | const U64 matches = vget_lane_u64(vreinterpret_u64_u8(res), 0); |
| 1000 | return ZSTD_rotateRight_U64(matches, headGrouped) & 0x8888888888888888ull; |
| 1001 | } else if (rowEntries == 32) { |
| 1002 | /* Same idea as with rowEntries == 16 but doing AND with |
| 1003 | * 0x55 = 0b01010101. |
| 1004 | */ |
| 1005 | const uint16x8x2_t chunk = vld2q_u16((const uint16_t*)(const void*)src); |
| 1006 | const uint8x16_t chunk0 = vreinterpretq_u8_u16(chunk.val[0]); |
| 1007 | const uint8x16_t chunk1 = vreinterpretq_u8_u16(chunk.val[1]); |
| 1008 | const uint8x16_t dup = vdupq_n_u8(tag); |
| 1009 | const uint8x8_t t0 = vshrn_n_u16(vreinterpretq_u16_u8(vceqq_u8(chunk0, dup)), 6); |
| 1010 | const uint8x8_t t1 = vshrn_n_u16(vreinterpretq_u16_u8(vceqq_u8(chunk1, dup)), 6); |
| 1011 | const uint8x8_t res = vsli_n_u8(t0, t1, 4); |
| 1012 | const U64 matches = vget_lane_u64(vreinterpret_u64_u8(res), 0) ; |
| 1013 | return ZSTD_rotateRight_U64(matches, headGrouped) & 0x5555555555555555ull; |
| 1014 | } else { /* rowEntries == 64 */ |
| 1015 | const uint8x16x4_t chunk = vld4q_u8(src); |
| 1016 | const uint8x16_t dup = vdupq_n_u8(tag); |
| 1017 | const uint8x16_t cmp0 = vceqq_u8(chunk.val[0], dup); |
| 1018 | const uint8x16_t cmp1 = vceqq_u8(chunk.val[1], dup); |
| 1019 | const uint8x16_t cmp2 = vceqq_u8(chunk.val[2], dup); |
| 1020 | const uint8x16_t cmp3 = vceqq_u8(chunk.val[3], dup); |
| 1021 | |
| 1022 | const uint8x16_t t0 = vsriq_n_u8(cmp1, cmp0, 1); |
| 1023 | const uint8x16_t t1 = vsriq_n_u8(cmp3, cmp2, 1); |
| 1024 | const uint8x16_t t2 = vsriq_n_u8(t1, t0, 2); |
| 1025 | const uint8x16_t t3 = vsriq_n_u8(t2, t2, 4); |
| 1026 | const uint8x8_t t4 = vshrn_n_u16(vreinterpretq_u16_u8(t3), 4); |
| 1027 | const U64 matches = vget_lane_u64(vreinterpret_u64_u8(t4), 0); |
| 1028 | return ZSTD_rotateRight_U64(matches, headGrouped); |
| 1029 | } |
| 1030 | } |
| 1031 | #endif |
| 1032 | |
| 1033 | /* Returns a ZSTD_VecMask (U64) that has the nth group (determined by |
| 1034 | * ZSTD_row_matchMaskGroupWidth) of bits set to 1 if the newly-computed "tag" |
| 1035 | * matches the hash at the nth position in a row of the tagTable. |
| 1036 | * Each row is a circular buffer beginning at the value of "headGrouped". So we |
| 1037 | * must rotate the "matches" bitfield to match up with the actual layout of the |
| 1038 | * entries within the hashTable */ |
| 1039 | FORCE_INLINE_TEMPLATE ZSTD_VecMask |
| 1040 | ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 headGrouped, const U32 rowEntries) |
| 1041 | { |
| 1042 | const BYTE* const src = tagRow; |
| 1043 | assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64); |
| 1044 | assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES); |
| 1045 | assert(ZSTD_row_matchMaskGroupWidth(rowEntries) * rowEntries <= sizeof(ZSTD_VecMask) * 8); |
| 1046 | |
| 1047 | #if defined(ZSTD_ARCH_X86_SSE2) |
| 1048 | |
| 1049 | return ZSTD_row_getSSEMask(rowEntries / 16, src, tag, headGrouped); |
| 1050 | |
| 1051 | #else /* SW or NEON-LE */ |
| 1052 | |
| 1053 | # if defined(ZSTD_ARCH_ARM_NEON) |
| 1054 | /* This NEON path only works for little endian - otherwise use SWAR below */ |
| 1055 | if (MEM_isLittleEndian()) { |
| 1056 | return ZSTD_row_getNEONMask(rowEntries, src, tag, headGrouped); |
| 1057 | } |
| 1058 | # endif /* ZSTD_ARCH_ARM_NEON */ |
| 1059 | /* SWAR */ |
| 1060 | { const int chunkSize = sizeof(size_t); |
| 1061 | const size_t shiftAmount = ((chunkSize * 8) - chunkSize); |
| 1062 | const size_t xFF = ~((size_t)0); |
| 1063 | const size_t x01 = xFF / 0xFF; |
| 1064 | const size_t x80 = x01 << 7; |
| 1065 | const size_t splatChar = tag * x01; |
| 1066 | ZSTD_VecMask matches = 0; |
| 1067 | int i = rowEntries - chunkSize; |
| 1068 | assert((sizeof(size_t) == 4) || (sizeof(size_t) == 8)); |
| 1069 | if (MEM_isLittleEndian()) { /* runtime check so have two loops */ |
| 1070 | const size_t extractMagic = (xFF / 0x7F) >> chunkSize; |
| 1071 | do { |
| 1072 | size_t chunk = MEM_readST(&src[i]); |
| 1073 | chunk ^= splatChar; |
| 1074 | chunk = (((chunk | x80) - x01) | chunk) & x80; |
| 1075 | matches <<= chunkSize; |
| 1076 | matches |= (chunk * extractMagic) >> shiftAmount; |
| 1077 | i -= chunkSize; |
| 1078 | } while (i >= 0); |
| 1079 | } else { /* big endian: reverse bits during extraction */ |
| 1080 | const size_t msb = xFF ^ (xFF >> 1); |
| 1081 | const size_t extractMagic = (msb / 0x1FF) | msb; |
| 1082 | do { |
| 1083 | size_t chunk = MEM_readST(&src[i]); |
| 1084 | chunk ^= splatChar; |
| 1085 | chunk = (((chunk | x80) - x01) | chunk) & x80; |
| 1086 | matches <<= chunkSize; |
| 1087 | matches |= ((chunk >> 7) * extractMagic) >> shiftAmount; |
| 1088 | i -= chunkSize; |
| 1089 | } while (i >= 0); |
| 1090 | } |
| 1091 | matches = ~matches; |
| 1092 | if (rowEntries == 16) { |
| 1093 | return ZSTD_rotateRight_U16((U16)matches, headGrouped); |
| 1094 | } else if (rowEntries == 32) { |
| 1095 | return ZSTD_rotateRight_U32((U32)matches, headGrouped); |
| 1096 | } else { |
| 1097 | return ZSTD_rotateRight_U64((U64)matches, headGrouped); |
| 1098 | } |
| 1099 | } |
| 1100 | #endif |
| 1101 | } |
| 1102 | |
| 1103 | /* The high-level approach of the SIMD row based match finder is as follows: |
| 1104 | * - Figure out where to insert the new entry: |
| 1105 | * - Generate a hash from a byte along with an additional 1-byte "short hash". The additional byte is our "tag" |
| 1106 | * - The hashTable is effectively split into groups or "rows" of 16 or 32 entries of U32, and the hash determines |
| 1107 | * which row to insert into. |
| 1108 | * - Determine the correct position within the row to insert the entry into. Each row of 16 or 32 can |
| 1109 | * be considered as a circular buffer with a "head" index that resides in the tagTable. |
| 1110 | * - Also insert the "tag" into the equivalent row and position in the tagTable. |
| 1111 | * - Note: The tagTable has 17 or 33 1-byte entries per row, due to 16 or 32 tags, and 1 "head" entry. |
| 1112 | * The 17 or 33 entry rows are spaced out to occur every 32 or 64 bytes, respectively, |
| 1113 | * for alignment/performance reasons, leaving some bytes unused. |
| 1114 | * - Use SIMD to efficiently compare the tags in the tagTable to the 1-byte "short hash" and |
| 1115 | * generate a bitfield that we can cycle through to check the collisions in the hash table. |
| 1116 | * - Pick the longest match. |
| 1117 | */ |
| 1118 | FORCE_INLINE_TEMPLATE |
| 1119 | size_t ZSTD_RowFindBestMatch( |
| 1120 | ZSTD_matchState_t* ms, |
| 1121 | const BYTE* const ip, const BYTE* const iLimit, |
| 1122 | size_t* offsetPtr, |
| 1123 | const U32 mls, const ZSTD_dictMode_e dictMode, |
| 1124 | const U32 rowLog) |
| 1125 | { |
| 1126 | U32* const hashTable = ms->hashTable; |
| 1127 | BYTE* const tagTable = ms->tagTable; |
| 1128 | U32* const hashCache = ms->hashCache; |
| 1129 | const U32 hashLog = ms->rowHashLog; |
| 1130 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
| 1131 | const BYTE* const base = ms->window.base; |
| 1132 | const BYTE* const dictBase = ms->window.dictBase; |
| 1133 | const U32 dictLimit = ms->window.dictLimit; |
| 1134 | const BYTE* const prefixStart = base + dictLimit; |
| 1135 | const BYTE* const dictEnd = dictBase + dictLimit; |
| 1136 | const U32 curr = (U32)(ip-base); |
| 1137 | const U32 maxDistance = 1U << cParams->windowLog; |
| 1138 | const U32 lowestValid = ms->window.lowLimit; |
| 1139 | const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid; |
| 1140 | const U32 isDictionary = (ms->loadedDictEnd != 0); |
| 1141 | const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance; |
| 1142 | const U32 rowEntries = (1U << rowLog); |
| 1143 | const U32 rowMask = rowEntries - 1; |
| 1144 | const U32 cappedSearchLog = MIN(cParams->searchLog, rowLog); /* nb of searches is capped at nb entries per row */ |
| 1145 | const U32 groupWidth = ZSTD_row_matchMaskGroupWidth(rowEntries); |
| 1146 | const U64 hashSalt = ms->hashSalt; |
| 1147 | U32 nbAttempts = 1U << cappedSearchLog; |
| 1148 | size_t ml=4-1; |
| 1149 | U32 hash; |
| 1150 | |
| 1151 | /* DMS/DDS variables that may be referenced laster */ |
| 1152 | const ZSTD_matchState_t* const dms = ms->dictMatchState; |
| 1153 | |
| 1154 | /* Initialize the following variables to satisfy static analyzer */ |
| 1155 | size_t ddsIdx = 0; |
| 1156 | U32 ddsExtraAttempts = 0; /* cctx hash tables are limited in searches, but allow extra searches into DDS */ |
| 1157 | U32 dmsTag = 0; |
| 1158 | U32* dmsRow = NULL; |
| 1159 | BYTE* dmsTagRow = NULL; |
| 1160 | |
| 1161 | if (dictMode == ZSTD_dedicatedDictSearch) { |
| 1162 | const U32 ddsHashLog = dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG; |
| 1163 | { /* Prefetch DDS hashtable entry */ |
| 1164 | ddsIdx = ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG; |
| 1165 | PREFETCH_L1(&dms->hashTable[ddsIdx]); |
| 1166 | } |
| 1167 | ddsExtraAttempts = cParams->searchLog > rowLog ? 1U << (cParams->searchLog - rowLog) : 0; |
| 1168 | } |
| 1169 | |
| 1170 | if (dictMode == ZSTD_dictMatchState) { |
| 1171 | /* Prefetch DMS rows */ |
| 1172 | U32* const dmsHashTable = dms->hashTable; |
| 1173 | BYTE* const dmsTagTable = dms->tagTable; |
| 1174 | U32 const dmsHash = (U32)ZSTD_hashPtr(ip, dms->rowHashLog + ZSTD_ROW_HASH_TAG_BITS, mls); |
| 1175 | U32 const dmsRelRow = (dmsHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
| 1176 | dmsTag = dmsHash & ZSTD_ROW_HASH_TAG_MASK; |
| 1177 | dmsTagRow = (BYTE*)(dmsTagTable + dmsRelRow); |
| 1178 | dmsRow = dmsHashTable + dmsRelRow; |
| 1179 | ZSTD_row_prefetch(dmsHashTable, dmsTagTable, dmsRelRow, rowLog); |
| 1180 | } |
| 1181 | |
| 1182 | /* Update the hashTable and tagTable up to (but not including) ip */ |
| 1183 | if (!ms->lazySkipping) { |
| 1184 | ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 1 /* useCache */); |
| 1185 | hash = ZSTD_row_nextCachedHash(hashCache, hashTable, tagTable, base, curr, hashLog, rowLog, mls, hashSalt); |
| 1186 | } else { |
| 1187 | /* Stop inserting every position when in the lazy skipping mode. |
| 1188 | * The hash cache is also not kept up to date in this mode. |
| 1189 | */ |
| 1190 | hash = (U32)ZSTD_hashPtrSalted(ip, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt); |
| 1191 | ms->nextToUpdate = curr; |
| 1192 | } |
| 1193 | ms->hashSaltEntropy += hash; /* collect salt entropy */ |
| 1194 | |
| 1195 | { /* Get the hash for ip, compute the appropriate row */ |
| 1196 | U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
| 1197 | U32 const tag = hash & ZSTD_ROW_HASH_TAG_MASK; |
| 1198 | U32* const row = hashTable + relRow; |
| 1199 | BYTE* tagRow = (BYTE*)(tagTable + relRow); |
| 1200 | U32 const headGrouped = (*tagRow & rowMask) * groupWidth; |
| 1201 | U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES]; |
| 1202 | size_t numMatches = 0; |
| 1203 | size_t currMatch = 0; |
| 1204 | ZSTD_VecMask matches = ZSTD_row_getMatchMask(tagRow, (BYTE)tag, headGrouped, rowEntries); |
| 1205 | |
| 1206 | /* Cycle through the matches and prefetch */ |
| 1207 | for (; (matches > 0) && (nbAttempts > 0); matches &= (matches - 1)) { |
| 1208 | U32 const matchPos = ((headGrouped + ZSTD_VecMask_next(matches)) / groupWidth) & rowMask; |
| 1209 | U32 const matchIndex = row[matchPos]; |
| 1210 | if(matchPos == 0) continue; |
| 1211 | assert(numMatches < rowEntries); |
| 1212 | if (matchIndex < lowLimit) |
| 1213 | break; |
| 1214 | if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { |
| 1215 | PREFETCH_L1(base + matchIndex); |
| 1216 | } else { |
| 1217 | PREFETCH_L1(dictBase + matchIndex); |
| 1218 | } |
| 1219 | matchBuffer[numMatches++] = matchIndex; |
| 1220 | --nbAttempts; |
| 1221 | } |
| 1222 | |
| 1223 | /* Speed opt: insert current byte into hashtable too. This allows us to avoid one iteration of the loop |
| 1224 | in ZSTD_row_update_internal() at the next search. */ |
| 1225 | { |
| 1226 | U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask); |
| 1227 | tagRow[pos] = (BYTE)tag; |
| 1228 | row[pos] = ms->nextToUpdate++; |
| 1229 | } |
| 1230 | |
| 1231 | /* Return the longest match */ |
| 1232 | for (; currMatch < numMatches; ++currMatch) { |
| 1233 | U32 const matchIndex = matchBuffer[currMatch]; |
| 1234 | size_t currentMl=0; |
| 1235 | assert(matchIndex < curr); |
| 1236 | assert(matchIndex >= lowLimit); |
| 1237 | |
| 1238 | if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { |
| 1239 | const BYTE* const match = base + matchIndex; |
| 1240 | assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */ |
| 1241 | /* read 4B starting from (match + ml + 1 - sizeof(U32)) */ |
| 1242 | if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */ |
| 1243 | currentMl = ZSTD_count(ip, match, iLimit); |
| 1244 | } else { |
| 1245 | const BYTE* const match = dictBase + matchIndex; |
| 1246 | assert(match+4 <= dictEnd); |
| 1247 | if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
| 1248 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4; |
| 1249 | } |
| 1250 | |
| 1251 | /* Save best solution */ |
| 1252 | if (currentMl > ml) { |
| 1253 | ml = currentMl; |
| 1254 | *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex); |
| 1255 | if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ |
| 1256 | } |
| 1257 | } |
| 1258 | } |
| 1259 | |
| 1260 | assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ |
| 1261 | if (dictMode == ZSTD_dedicatedDictSearch) { |
| 1262 | ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts + ddsExtraAttempts, dms, |
| 1263 | ip, iLimit, prefixStart, curr, dictLimit, ddsIdx); |
| 1264 | } else if (dictMode == ZSTD_dictMatchState) { |
| 1265 | /* TODO: Measure and potentially add prefetching to DMS */ |
| 1266 | const U32 dmsLowestIndex = dms->window.dictLimit; |
| 1267 | const BYTE* const dmsBase = dms->window.base; |
| 1268 | const BYTE* const dmsEnd = dms->window.nextSrc; |
| 1269 | const U32 dmsSize = (U32)(dmsEnd - dmsBase); |
| 1270 | const U32 dmsIndexDelta = dictLimit - dmsSize; |
| 1271 | |
| 1272 | { U32 const headGrouped = (*dmsTagRow & rowMask) * groupWidth; |
| 1273 | U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES]; |
| 1274 | size_t numMatches = 0; |
| 1275 | size_t currMatch = 0; |
| 1276 | ZSTD_VecMask matches = ZSTD_row_getMatchMask(dmsTagRow, (BYTE)dmsTag, headGrouped, rowEntries); |
| 1277 | |
| 1278 | for (; (matches > 0) && (nbAttempts > 0); matches &= (matches - 1)) { |
| 1279 | U32 const matchPos = ((headGrouped + ZSTD_VecMask_next(matches)) / groupWidth) & rowMask; |
| 1280 | U32 const matchIndex = dmsRow[matchPos]; |
| 1281 | if(matchPos == 0) continue; |
| 1282 | if (matchIndex < dmsLowestIndex) |
| 1283 | break; |
| 1284 | PREFETCH_L1(dmsBase + matchIndex); |
| 1285 | matchBuffer[numMatches++] = matchIndex; |
| 1286 | --nbAttempts; |
| 1287 | } |
| 1288 | |
| 1289 | /* Return the longest match */ |
| 1290 | for (; currMatch < numMatches; ++currMatch) { |
| 1291 | U32 const matchIndex = matchBuffer[currMatch]; |
| 1292 | size_t currentMl=0; |
| 1293 | assert(matchIndex >= dmsLowestIndex); |
| 1294 | assert(matchIndex < curr); |
| 1295 | |
| 1296 | { const BYTE* const match = dmsBase + matchIndex; |
| 1297 | assert(match+4 <= dmsEnd); |
| 1298 | if (MEM_read32(match) == MEM_read32(ip)) |
| 1299 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4; |
| 1300 | } |
| 1301 | |
| 1302 | if (currentMl > ml) { |
| 1303 | ml = currentMl; |
| 1304 | assert(curr > matchIndex + dmsIndexDelta); |
| 1305 | *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta)); |
| 1306 | if (ip+currentMl == iLimit) break; |
| 1307 | } |
| 1308 | } |
| 1309 | } |
| 1310 | } |
| 1311 | return ml; |
| 1312 | } |
| 1313 | |
| 1314 | |
| 1315 | /** |
| 1316 | * Generate search functions templated on (dictMode, mls, rowLog). |
| 1317 | * These functions are outlined for code size & compilation time. |
| 1318 | * ZSTD_searchMax() dispatches to the correct implementation function. |
| 1319 | * |
| 1320 | * TODO: The start of the search function involves loading and calculating a |
| 1321 | * bunch of constants from the ZSTD_matchState_t. These computations could be |
| 1322 | * done in an initialization function, and saved somewhere in the match state. |
| 1323 | * Then we could pass a pointer to the saved state instead of the match state, |
| 1324 | * and avoid duplicate computations. |
| 1325 | * |
| 1326 | * TODO: Move the match re-winding into searchMax. This improves compression |
| 1327 | * ratio, and unlocks further simplifications with the next TODO. |
| 1328 | * |
| 1329 | * TODO: Try moving the repcode search into searchMax. After the re-winding |
| 1330 | * and repcode search are in searchMax, there is no more logic in the match |
| 1331 | * finder loop that requires knowledge about the dictMode. So we should be |
| 1332 | * able to avoid force inlining it, and we can join the extDict loop with |
| 1333 | * the single segment loop. It should go in searchMax instead of its own |
| 1334 | * function to avoid having multiple virtual function calls per search. |
| 1335 | */ |
| 1336 | |
| 1337 | #define ZSTD_BT_SEARCH_FN(dictMode, mls) ZSTD_BtFindBestMatch_##dictMode##_##mls |
| 1338 | #define ZSTD_HC_SEARCH_FN(dictMode, mls) ZSTD_HcFindBestMatch_##dictMode##_##mls |
| 1339 | #define ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog) ZSTD_RowFindBestMatch_##dictMode##_##mls##_##rowLog |
| 1340 | |
| 1341 | #define ZSTD_SEARCH_FN_ATTRS FORCE_NOINLINE |
| 1342 | |
| 1343 | #define GEN_ZSTD_BT_SEARCH_FN(dictMode, mls) \ |
| 1344 | ZSTD_SEARCH_FN_ATTRS size_t ZSTD_BT_SEARCH_FN(dictMode, mls)( \ |
| 1345 | ZSTD_matchState_t* ms, \ |
| 1346 | const BYTE* ip, const BYTE* const iLimit, \ |
| 1347 | size_t* offBasePtr) \ |
| 1348 | { \ |
| 1349 | assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ |
| 1350 | return ZSTD_BtFindBestMatch(ms, ip, iLimit, offBasePtr, mls, ZSTD_##dictMode); \ |
| 1351 | } \ |
| 1352 | |
| 1353 | #define GEN_ZSTD_HC_SEARCH_FN(dictMode, mls) \ |
| 1354 | ZSTD_SEARCH_FN_ATTRS size_t ZSTD_HC_SEARCH_FN(dictMode, mls)( \ |
| 1355 | ZSTD_matchState_t* ms, \ |
| 1356 | const BYTE* ip, const BYTE* const iLimit, \ |
| 1357 | size_t* offsetPtr) \ |
| 1358 | { \ |
| 1359 | assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ |
| 1360 | return ZSTD_HcFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode); \ |
| 1361 | } \ |
| 1362 | |
| 1363 | #define GEN_ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog) \ |
| 1364 | ZSTD_SEARCH_FN_ATTRS size_t ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog)( \ |
| 1365 | ZSTD_matchState_t* ms, \ |
| 1366 | const BYTE* ip, const BYTE* const iLimit, \ |
| 1367 | size_t* offsetPtr) \ |
| 1368 | { \ |
| 1369 | assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ |
| 1370 | assert(MAX(4, MIN(6, ms->cParams.searchLog)) == rowLog); \ |
| 1371 | return ZSTD_RowFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode, rowLog); \ |
| 1372 | } \ |
| 1373 | |
| 1374 | #define ZSTD_FOR_EACH_ROWLOG(X, dictMode, mls) \ |
| 1375 | X(dictMode, mls, 4) \ |
| 1376 | X(dictMode, mls, 5) \ |
| 1377 | X(dictMode, mls, 6) |
| 1378 | |
| 1379 | #define ZSTD_FOR_EACH_MLS_ROWLOG(X, dictMode) \ |
| 1380 | ZSTD_FOR_EACH_ROWLOG(X, dictMode, 4) \ |
| 1381 | ZSTD_FOR_EACH_ROWLOG(X, dictMode, 5) \ |
| 1382 | ZSTD_FOR_EACH_ROWLOG(X, dictMode, 6) |
| 1383 | |
| 1384 | #define ZSTD_FOR_EACH_MLS(X, dictMode) \ |
| 1385 | X(dictMode, 4) \ |
| 1386 | X(dictMode, 5) \ |
| 1387 | X(dictMode, 6) |
| 1388 | |
| 1389 | #define ZSTD_FOR_EACH_DICT_MODE(X, ...) \ |
| 1390 | X(__VA_ARGS__, noDict) \ |
| 1391 | X(__VA_ARGS__, extDict) \ |
| 1392 | X(__VA_ARGS__, dictMatchState) \ |
| 1393 | X(__VA_ARGS__, dedicatedDictSearch) |
| 1394 | |
| 1395 | /* Generate row search fns for each combination of (dictMode, mls, rowLog) */ |
| 1396 | ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS_ROWLOG, GEN_ZSTD_ROW_SEARCH_FN) |
| 1397 | /* Generate binary Tree search fns for each combination of (dictMode, mls) */ |
| 1398 | ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_BT_SEARCH_FN) |
| 1399 | /* Generate hash chain search fns for each combination of (dictMode, mls) */ |
| 1400 | ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_HC_SEARCH_FN) |
| 1401 | |
| 1402 | typedef enum { search_hashChain=0, search_binaryTree=1, search_rowHash=2 } searchMethod_e; |
| 1403 | |
| 1404 | #define GEN_ZSTD_CALL_BT_SEARCH_FN(dictMode, mls) \ |
| 1405 | case mls: \ |
| 1406 | return ZSTD_BT_SEARCH_FN(dictMode, mls)(ms, ip, iend, offsetPtr); |
| 1407 | #define GEN_ZSTD_CALL_HC_SEARCH_FN(dictMode, mls) \ |
| 1408 | case mls: \ |
| 1409 | return ZSTD_HC_SEARCH_FN(dictMode, mls)(ms, ip, iend, offsetPtr); |
| 1410 | #define GEN_ZSTD_CALL_ROW_SEARCH_FN(dictMode, mls, rowLog) \ |
| 1411 | case rowLog: \ |
| 1412 | return ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog)(ms, ip, iend, offsetPtr); |
| 1413 | |
| 1414 | #define ZSTD_SWITCH_MLS(X, dictMode) \ |
| 1415 | switch (mls) { \ |
| 1416 | ZSTD_FOR_EACH_MLS(X, dictMode) \ |
| 1417 | } |
| 1418 | |
| 1419 | #define ZSTD_SWITCH_ROWLOG(dictMode, mls) \ |
| 1420 | case mls: \ |
| 1421 | switch (rowLog) { \ |
| 1422 | ZSTD_FOR_EACH_ROWLOG(GEN_ZSTD_CALL_ROW_SEARCH_FN, dictMode, mls) \ |
| 1423 | } \ |
| 1424 | ZSTD_UNREACHABLE; \ |
| 1425 | break; |
| 1426 | |
| 1427 | #define ZSTD_SWITCH_SEARCH_METHOD(dictMode) \ |
| 1428 | switch (searchMethod) { \ |
| 1429 | case search_hashChain: \ |
| 1430 | ZSTD_SWITCH_MLS(GEN_ZSTD_CALL_HC_SEARCH_FN, dictMode) \ |
| 1431 | break; \ |
| 1432 | case search_binaryTree: \ |
| 1433 | ZSTD_SWITCH_MLS(GEN_ZSTD_CALL_BT_SEARCH_FN, dictMode) \ |
| 1434 | break; \ |
| 1435 | case search_rowHash: \ |
| 1436 | ZSTD_SWITCH_MLS(ZSTD_SWITCH_ROWLOG, dictMode) \ |
| 1437 | break; \ |
| 1438 | } \ |
| 1439 | ZSTD_UNREACHABLE; |
| 1440 | |
| 1441 | /** |
| 1442 | * Searches for the longest match at @p ip. |
| 1443 | * Dispatches to the correct implementation function based on the |
| 1444 | * (searchMethod, dictMode, mls, rowLog). We use switch statements |
| 1445 | * here instead of using an indirect function call through a function |
| 1446 | * pointer because after Spectre and Meltdown mitigations, indirect |
| 1447 | * function calls can be very costly, especially in the kernel. |
| 1448 | * |
| 1449 | * NOTE: dictMode and searchMethod should be templated, so those switch |
| 1450 | * statements should be optimized out. Only the mls & rowLog switches |
| 1451 | * should be left. |
| 1452 | * |
| 1453 | * @param ms The match state. |
| 1454 | * @param ip The position to search at. |
| 1455 | * @param iend The end of the input data. |
| 1456 | * @param[out] offsetPtr Stores the match offset into this pointer. |
| 1457 | * @param mls The minimum search length, in the range [4, 6]. |
| 1458 | * @param rowLog The row log (if applicable), in the range [4, 6]. |
| 1459 | * @param searchMethod The search method to use (templated). |
| 1460 | * @param dictMode The dictMode (templated). |
| 1461 | * |
| 1462 | * @returns The length of the longest match found, or < mls if no match is found. |
| 1463 | * If a match is found its offset is stored in @p offsetPtr. |
| 1464 | */ |
| 1465 | FORCE_INLINE_TEMPLATE size_t ZSTD_searchMax( |
| 1466 | ZSTD_matchState_t* ms, |
| 1467 | const BYTE* ip, |
| 1468 | const BYTE* iend, |
| 1469 | size_t* offsetPtr, |
| 1470 | U32 const mls, |
| 1471 | U32 const rowLog, |
| 1472 | searchMethod_e const searchMethod, |
| 1473 | ZSTD_dictMode_e const dictMode) |
| 1474 | { |
| 1475 | if (dictMode == ZSTD_noDict) { |
| 1476 | ZSTD_SWITCH_SEARCH_METHOD(noDict) |
| 1477 | } else if (dictMode == ZSTD_extDict) { |
| 1478 | ZSTD_SWITCH_SEARCH_METHOD(extDict) |
| 1479 | } else if (dictMode == ZSTD_dictMatchState) { |
| 1480 | ZSTD_SWITCH_SEARCH_METHOD(dictMatchState) |
| 1481 | } else if (dictMode == ZSTD_dedicatedDictSearch) { |
| 1482 | ZSTD_SWITCH_SEARCH_METHOD(dedicatedDictSearch) |
| 1483 | } |
| 1484 | ZSTD_UNREACHABLE; |
| 1485 | return 0; |
| 1486 | } |
| 1487 | |
| 1488 | /* ******************************* |
| 1489 | * Common parser - lazy strategy |
| 1490 | *********************************/ |
| 1491 | |
| 1492 | FORCE_INLINE_TEMPLATE size_t |
| 1493 | ZSTD_compressBlock_lazy_generic( |
| 1494 | ZSTD_matchState_t* ms, seqStore_t* seqStore, |
| 1495 | U32 rep[ZSTD_REP_NUM], |
| 1496 | const void* src, size_t srcSize, |
| 1497 | const searchMethod_e searchMethod, const U32 depth, |
| 1498 | ZSTD_dictMode_e const dictMode) |
| 1499 | { |
| 1500 | const BYTE* const istart = (const BYTE*)src; |
| 1501 | const BYTE* ip = istart; |
| 1502 | const BYTE* anchor = istart; |
| 1503 | const BYTE* const iend = istart + srcSize; |
| 1504 | const BYTE* const ilimit = (searchMethod == search_rowHash) ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8; |
| 1505 | const BYTE* const base = ms->window.base; |
| 1506 | const U32 prefixLowestIndex = ms->window.dictLimit; |
| 1507 | const BYTE* const prefixLowest = base + prefixLowestIndex; |
| 1508 | const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6); |
| 1509 | const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); |
| 1510 | |
| 1511 | U32 offset_1 = rep[0], offset_2 = rep[1]; |
| 1512 | U32 offsetSaved1 = 0, offsetSaved2 = 0; |
| 1513 | |
| 1514 | const int isDMS = dictMode == ZSTD_dictMatchState; |
| 1515 | const int isDDS = dictMode == ZSTD_dedicatedDictSearch; |
| 1516 | const int isDxS = isDMS || isDDS; |
| 1517 | const ZSTD_matchState_t* const dms = ms->dictMatchState; |
| 1518 | const U32 dictLowestIndex = isDxS ? dms->window.dictLimit : 0; |
| 1519 | const BYTE* const dictBase = isDxS ? dms->window.base : NULL; |
| 1520 | const BYTE* const dictLowest = isDxS ? dictBase + dictLowestIndex : NULL; |
| 1521 | const BYTE* const dictEnd = isDxS ? dms->window.nextSrc : NULL; |
| 1522 | const U32 dictIndexDelta = isDxS ? |
| 1523 | prefixLowestIndex - (U32)(dictEnd - dictBase) : |
| 1524 | 0; |
| 1525 | const U32 dictAndPrefixLength = (U32)((ip - prefixLowest) + (dictEnd - dictLowest)); |
| 1526 | |
| 1527 | DEBUGLOG(5, "ZSTD_compressBlock_lazy_generic (dictMode=%u) (searchFunc=%u)", (U32)dictMode, (U32)searchMethod); |
| 1528 | ip += (dictAndPrefixLength == 0); |
| 1529 | if (dictMode == ZSTD_noDict) { |
| 1530 | U32 const curr = (U32)(ip - base); |
| 1531 | U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, ms->cParams.windowLog); |
| 1532 | U32 const maxRep = curr - windowLow; |
| 1533 | if (offset_2 > maxRep) offsetSaved2 = offset_2, offset_2 = 0; |
| 1534 | if (offset_1 > maxRep) offsetSaved1 = offset_1, offset_1 = 0; |
| 1535 | } |
| 1536 | if (isDxS) { |
| 1537 | /* dictMatchState repCode checks don't currently handle repCode == 0 |
| 1538 | * disabling. */ |
| 1539 | assert(offset_1 <= dictAndPrefixLength); |
| 1540 | assert(offset_2 <= dictAndPrefixLength); |
| 1541 | } |
| 1542 | |
| 1543 | /* Reset the lazy skipping state */ |
| 1544 | ms->lazySkipping = 0; |
| 1545 | |
| 1546 | if (searchMethod == search_rowHash) { |
| 1547 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit); |
| 1548 | } |
| 1549 | |
| 1550 | /* Match Loop */ |
| 1551 | #if defined(__GNUC__) && defined(__x86_64__) |
| 1552 | /* I've measured random a 5% speed loss on levels 5 & 6 (greedy) when the |
| 1553 | * code alignment is perturbed. To fix the instability align the loop on 32-bytes. |
| 1554 | */ |
| 1555 | __asm__(".p2align 5"); |
| 1556 | #endif |
| 1557 | while (ip < ilimit) { |
| 1558 | size_t matchLength=0; |
| 1559 | size_t offBase = REPCODE1_TO_OFFBASE; |
| 1560 | const BYTE* start=ip+1; |
| 1561 | DEBUGLOG(7, "search baseline (depth 0)"); |
| 1562 | |
| 1563 | /* check repCode */ |
| 1564 | if (isDxS) { |
| 1565 | const U32 repIndex = (U32)(ip - base) + 1 - offset_1; |
| 1566 | const BYTE* repMatch = ((dictMode == ZSTD_dictMatchState || dictMode == ZSTD_dedicatedDictSearch) |
| 1567 | && repIndex < prefixLowestIndex) ? |
| 1568 | dictBase + (repIndex - dictIndexDelta) : |
| 1569 | base + repIndex; |
| 1570 | if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) |
| 1571 | && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) { |
| 1572 | const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; |
| 1573 | matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; |
| 1574 | if (depth==0) goto _storeSequence; |
| 1575 | } |
| 1576 | } |
| 1577 | if ( dictMode == ZSTD_noDict |
| 1578 | && ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) { |
| 1579 | matchLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4; |
| 1580 | if (depth==0) goto _storeSequence; |
| 1581 | } |
| 1582 | |
| 1583 | /* first search (depth 0) */ |
| 1584 | { size_t offbaseFound = 999999999; |
| 1585 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offbaseFound, mls, rowLog, searchMethod, dictMode); |
| 1586 | if (ml2 > matchLength) |
| 1587 | matchLength = ml2, start = ip, offBase = offbaseFound; |
| 1588 | } |
| 1589 | |
| 1590 | if (matchLength < 4) { |
| 1591 | size_t const step = ((size_t)(ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */; |
| 1592 | ip += step; |
| 1593 | /* Enter the lazy skipping mode once we are skipping more than 8 bytes at a time. |
| 1594 | * In this mode we stop inserting every position into our tables, and only insert |
| 1595 | * positions that we search, which is one in step positions. |
| 1596 | * The exact cutoff is flexible, I've just chosen a number that is reasonably high, |
| 1597 | * so we minimize the compression ratio loss in "normal" scenarios. This mode gets |
| 1598 | * triggered once we've gone 2KB without finding any matches. |
| 1599 | */ |
| 1600 | ms->lazySkipping = step > kLazySkippingStep; |
| 1601 | continue; |
| 1602 | } |
| 1603 | |
| 1604 | /* let's try to find a better solution */ |
| 1605 | if (depth>=1) |
| 1606 | while (ip<ilimit) { |
| 1607 | DEBUGLOG(7, "search depth 1"); |
| 1608 | ip ++; |
| 1609 | if ( (dictMode == ZSTD_noDict) |
| 1610 | && (offBase) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) { |
| 1611 | size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4; |
| 1612 | int const gain2 = (int)(mlRep * 3); |
| 1613 | int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1); |
| 1614 | if ((mlRep >= 4) && (gain2 > gain1)) |
| 1615 | matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip; |
| 1616 | } |
| 1617 | if (isDxS) { |
| 1618 | const U32 repIndex = (U32)(ip - base) - offset_1; |
| 1619 | const BYTE* repMatch = repIndex < prefixLowestIndex ? |
| 1620 | dictBase + (repIndex - dictIndexDelta) : |
| 1621 | base + repIndex; |
| 1622 | if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) |
| 1623 | && (MEM_read32(repMatch) == MEM_read32(ip)) ) { |
| 1624 | const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; |
| 1625 | size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; |
| 1626 | int const gain2 = (int)(mlRep * 3); |
| 1627 | int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1); |
| 1628 | if ((mlRep >= 4) && (gain2 > gain1)) |
| 1629 | matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip; |
| 1630 | } |
| 1631 | } |
| 1632 | { size_t ofbCandidate=999999999; |
| 1633 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, dictMode); |
| 1634 | int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */ |
| 1635 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 4); |
| 1636 | if ((ml2 >= 4) && (gain2 > gain1)) { |
| 1637 | matchLength = ml2, offBase = ofbCandidate, start = ip; |
| 1638 | continue; /* search a better one */ |
| 1639 | } } |
| 1640 | |
| 1641 | /* let's find an even better one */ |
| 1642 | if ((depth==2) && (ip<ilimit)) { |
| 1643 | DEBUGLOG(7, "search depth 2"); |
| 1644 | ip ++; |
| 1645 | if ( (dictMode == ZSTD_noDict) |
| 1646 | && (offBase) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) { |
| 1647 | size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4; |
| 1648 | int const gain2 = (int)(mlRep * 4); |
| 1649 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1); |
| 1650 | if ((mlRep >= 4) && (gain2 > gain1)) |
| 1651 | matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip; |
| 1652 | } |
| 1653 | if (isDxS) { |
| 1654 | const U32 repIndex = (U32)(ip - base) - offset_1; |
| 1655 | const BYTE* repMatch = repIndex < prefixLowestIndex ? |
| 1656 | dictBase + (repIndex - dictIndexDelta) : |
| 1657 | base + repIndex; |
| 1658 | if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) |
| 1659 | && (MEM_read32(repMatch) == MEM_read32(ip)) ) { |
| 1660 | const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; |
| 1661 | size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; |
| 1662 | int const gain2 = (int)(mlRep * 4); |
| 1663 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1); |
| 1664 | if ((mlRep >= 4) && (gain2 > gain1)) |
| 1665 | matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip; |
| 1666 | } |
| 1667 | } |
| 1668 | { size_t ofbCandidate=999999999; |
| 1669 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, dictMode); |
| 1670 | int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */ |
| 1671 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 7); |
| 1672 | if ((ml2 >= 4) && (gain2 > gain1)) { |
| 1673 | matchLength = ml2, offBase = ofbCandidate, start = ip; |
| 1674 | continue; |
| 1675 | } } } |
| 1676 | break; /* nothing found : store previous solution */ |
| 1677 | } |
| 1678 | |
| 1679 | /* NOTE: |
| 1680 | * Pay attention that `start[-value]` can lead to strange undefined behavior |
| 1681 | * notably if `value` is unsigned, resulting in a large positive `-value`. |
| 1682 | */ |
| 1683 | /* catch up */ |
| 1684 | if (OFFBASE_IS_OFFSET(offBase)) { |
| 1685 | if (dictMode == ZSTD_noDict) { |
| 1686 | while ( ((start > anchor) & (start - OFFBASE_TO_OFFSET(offBase) > prefixLowest)) |
| 1687 | && (start[-1] == (start-OFFBASE_TO_OFFSET(offBase))[-1]) ) /* only search for offset within prefix */ |
| 1688 | { start--; matchLength++; } |
| 1689 | } |
| 1690 | if (isDxS) { |
| 1691 | U32 const matchIndex = (U32)((size_t)(start-base) - OFFBASE_TO_OFFSET(offBase)); |
| 1692 | const BYTE* match = (matchIndex < prefixLowestIndex) ? dictBase + matchIndex - dictIndexDelta : base + matchIndex; |
| 1693 | const BYTE* const mStart = (matchIndex < prefixLowestIndex) ? dictLowest : prefixLowest; |
| 1694 | while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */ |
| 1695 | } |
| 1696 | offset_2 = offset_1; offset_1 = (U32)OFFBASE_TO_OFFSET(offBase); |
| 1697 | } |
| 1698 | /* store sequence */ |
| 1699 | _storeSequence: |
| 1700 | { size_t const litLength = (size_t)(start - anchor); |
| 1701 | ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offBase, matchLength); |
| 1702 | anchor = ip = start + matchLength; |
| 1703 | } |
| 1704 | if (ms->lazySkipping) { |
| 1705 | /* We've found a match, disable lazy skipping mode, and refill the hash cache. */ |
| 1706 | if (searchMethod == search_rowHash) { |
| 1707 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit); |
| 1708 | } |
| 1709 | ms->lazySkipping = 0; |
| 1710 | } |
| 1711 | |
| 1712 | /* check immediate repcode */ |
| 1713 | if (isDxS) { |
| 1714 | while (ip <= ilimit) { |
| 1715 | U32 const current2 = (U32)(ip-base); |
| 1716 | U32 const repIndex = current2 - offset_2; |
| 1717 | const BYTE* repMatch = repIndex < prefixLowestIndex ? |
| 1718 | dictBase - dictIndexDelta + repIndex : |
| 1719 | base + repIndex; |
| 1720 | if ( ((U32)((prefixLowestIndex-1) - (U32)repIndex) >= 3 /* intentional overflow */) |
| 1721 | && (MEM_read32(repMatch) == MEM_read32(ip)) ) { |
| 1722 | const BYTE* const repEnd2 = repIndex < prefixLowestIndex ? dictEnd : iend; |
| 1723 | matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd2, prefixLowest) + 4; |
| 1724 | offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap offset_2 <=> offset_1 */ |
| 1725 | ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength); |
| 1726 | ip += matchLength; |
| 1727 | anchor = ip; |
| 1728 | continue; |
| 1729 | } |
| 1730 | break; |
| 1731 | } |
| 1732 | } |
| 1733 | |
| 1734 | if (dictMode == ZSTD_noDict) { |
| 1735 | while ( ((ip <= ilimit) & (offset_2>0)) |
| 1736 | && (MEM_read32(ip) == MEM_read32(ip - offset_2)) ) { |
| 1737 | /* store sequence */ |
| 1738 | matchLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4; |
| 1739 | offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap repcodes */ |
| 1740 | ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength); |
| 1741 | ip += matchLength; |
| 1742 | anchor = ip; |
| 1743 | continue; /* faster when present ... (?) */ |
| 1744 | } } } |
| 1745 | |
| 1746 | /* If offset_1 started invalid (offsetSaved1 != 0) and became valid (offset_1 != 0), |
| 1747 | * rotate saved offsets. See comment in ZSTD_compressBlock_fast_noDict for more context. */ |
| 1748 | offsetSaved2 = ((offsetSaved1 != 0) && (offset_1 != 0)) ? offsetSaved1 : offsetSaved2; |
| 1749 | |
| 1750 | /* save reps for next block */ |
| 1751 | rep[0] = offset_1 ? offset_1 : offsetSaved1; |
| 1752 | rep[1] = offset_2 ? offset_2 : offsetSaved2; |
| 1753 | |
| 1754 | /* Return the last literals size */ |
| 1755 | return (size_t)(iend - anchor); |
| 1756 | } |
| 1757 | |
| 1758 | |
| 1759 | size_t ZSTD_compressBlock_btlazy2( |
| 1760 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1761 | void const* src, size_t srcSize) |
| 1762 | { |
| 1763 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_noDict); |
| 1764 | } |
| 1765 | |
| 1766 | size_t ZSTD_compressBlock_lazy2( |
| 1767 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1768 | void const* src, size_t srcSize) |
| 1769 | { |
| 1770 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_noDict); |
| 1771 | } |
| 1772 | |
| 1773 | size_t ZSTD_compressBlock_lazy( |
| 1774 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1775 | void const* src, size_t srcSize) |
| 1776 | { |
| 1777 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_noDict); |
| 1778 | } |
| 1779 | |
| 1780 | size_t ZSTD_compressBlock_greedy( |
| 1781 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1782 | void const* src, size_t srcSize) |
| 1783 | { |
| 1784 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_noDict); |
| 1785 | } |
| 1786 | |
| 1787 | size_t ZSTD_compressBlock_btlazy2_dictMatchState( |
| 1788 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1789 | void const* src, size_t srcSize) |
| 1790 | { |
| 1791 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_dictMatchState); |
| 1792 | } |
| 1793 | |
| 1794 | size_t ZSTD_compressBlock_lazy2_dictMatchState( |
| 1795 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1796 | void const* src, size_t srcSize) |
| 1797 | { |
| 1798 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dictMatchState); |
| 1799 | } |
| 1800 | |
| 1801 | size_t ZSTD_compressBlock_lazy_dictMatchState( |
| 1802 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1803 | void const* src, size_t srcSize) |
| 1804 | { |
| 1805 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dictMatchState); |
| 1806 | } |
| 1807 | |
| 1808 | size_t ZSTD_compressBlock_greedy_dictMatchState( |
| 1809 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1810 | void const* src, size_t srcSize) |
| 1811 | { |
| 1812 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dictMatchState); |
| 1813 | } |
| 1814 | |
| 1815 | |
| 1816 | size_t ZSTD_compressBlock_lazy2_dedicatedDictSearch( |
| 1817 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1818 | void const* src, size_t srcSize) |
| 1819 | { |
| 1820 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dedicatedDictSearch); |
| 1821 | } |
| 1822 | |
| 1823 | size_t ZSTD_compressBlock_lazy_dedicatedDictSearch( |
| 1824 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1825 | void const* src, size_t srcSize) |
| 1826 | { |
| 1827 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dedicatedDictSearch); |
| 1828 | } |
| 1829 | |
| 1830 | size_t ZSTD_compressBlock_greedy_dedicatedDictSearch( |
| 1831 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1832 | void const* src, size_t srcSize) |
| 1833 | { |
| 1834 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dedicatedDictSearch); |
| 1835 | } |
| 1836 | |
| 1837 | /* Row-based matchfinder */ |
| 1838 | size_t ZSTD_compressBlock_lazy2_row( |
| 1839 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1840 | void const* src, size_t srcSize) |
| 1841 | { |
| 1842 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_noDict); |
| 1843 | } |
| 1844 | |
| 1845 | size_t ZSTD_compressBlock_lazy_row( |
| 1846 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1847 | void const* src, size_t srcSize) |
| 1848 | { |
| 1849 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_noDict); |
| 1850 | } |
| 1851 | |
| 1852 | size_t ZSTD_compressBlock_greedy_row( |
| 1853 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1854 | void const* src, size_t srcSize) |
| 1855 | { |
| 1856 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_noDict); |
| 1857 | } |
| 1858 | |
| 1859 | size_t ZSTD_compressBlock_lazy2_dictMatchState_row( |
| 1860 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1861 | void const* src, size_t srcSize) |
| 1862 | { |
| 1863 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_dictMatchState); |
| 1864 | } |
| 1865 | |
| 1866 | size_t ZSTD_compressBlock_lazy_dictMatchState_row( |
| 1867 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1868 | void const* src, size_t srcSize) |
| 1869 | { |
| 1870 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_dictMatchState); |
| 1871 | } |
| 1872 | |
| 1873 | size_t ZSTD_compressBlock_greedy_dictMatchState_row( |
| 1874 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1875 | void const* src, size_t srcSize) |
| 1876 | { |
| 1877 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_dictMatchState); |
| 1878 | } |
| 1879 | |
| 1880 | |
| 1881 | size_t ZSTD_compressBlock_lazy2_dedicatedDictSearch_row( |
| 1882 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1883 | void const* src, size_t srcSize) |
| 1884 | { |
| 1885 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_dedicatedDictSearch); |
| 1886 | } |
| 1887 | |
| 1888 | size_t ZSTD_compressBlock_lazy_dedicatedDictSearch_row( |
| 1889 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1890 | void const* src, size_t srcSize) |
| 1891 | { |
| 1892 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_dedicatedDictSearch); |
| 1893 | } |
| 1894 | |
| 1895 | size_t ZSTD_compressBlock_greedy_dedicatedDictSearch_row( |
| 1896 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 1897 | void const* src, size_t srcSize) |
| 1898 | { |
| 1899 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_dedicatedDictSearch); |
| 1900 | } |
| 1901 | |
| 1902 | FORCE_INLINE_TEMPLATE |
| 1903 | size_t ZSTD_compressBlock_lazy_extDict_generic( |
| 1904 | ZSTD_matchState_t* ms, seqStore_t* seqStore, |
| 1905 | U32 rep[ZSTD_REP_NUM], |
| 1906 | const void* src, size_t srcSize, |
| 1907 | const searchMethod_e searchMethod, const U32 depth) |
| 1908 | { |
| 1909 | const BYTE* const istart = (const BYTE*)src; |
| 1910 | const BYTE* ip = istart; |
| 1911 | const BYTE* anchor = istart; |
| 1912 | const BYTE* const iend = istart + srcSize; |
| 1913 | const BYTE* const ilimit = searchMethod == search_rowHash ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8; |
| 1914 | const BYTE* const base = ms->window.base; |
| 1915 | const U32 dictLimit = ms->window.dictLimit; |
| 1916 | const BYTE* const prefixStart = base + dictLimit; |
| 1917 | const BYTE* const dictBase = ms->window.dictBase; |
| 1918 | const BYTE* const dictEnd = dictBase + dictLimit; |
| 1919 | const BYTE* const dictStart = dictBase + ms->window.lowLimit; |
| 1920 | const U32 windowLog = ms->cParams.windowLog; |
| 1921 | const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6); |
| 1922 | const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); |
| 1923 | |
| 1924 | U32 offset_1 = rep[0], offset_2 = rep[1]; |
| 1925 | |
| 1926 | DEBUGLOG(5, "ZSTD_compressBlock_lazy_extDict_generic (searchFunc=%u)", (U32)searchMethod); |
| 1927 | |
| 1928 | /* Reset the lazy skipping state */ |
| 1929 | ms->lazySkipping = 0; |
| 1930 | |
| 1931 | /* init */ |
| 1932 | ip += (ip == prefixStart); |
| 1933 | if (searchMethod == search_rowHash) { |
| 1934 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit); |
| 1935 | } |
| 1936 | |
| 1937 | /* Match Loop */ |
| 1938 | #if defined(__GNUC__) && defined(__x86_64__) |
| 1939 | /* I've measured random a 5% speed loss on levels 5 & 6 (greedy) when the |
| 1940 | * code alignment is perturbed. To fix the instability align the loop on 32-bytes. |
| 1941 | */ |
| 1942 | __asm__(".p2align 5"); |
| 1943 | #endif |
| 1944 | while (ip < ilimit) { |
| 1945 | size_t matchLength=0; |
| 1946 | size_t offBase = REPCODE1_TO_OFFBASE; |
| 1947 | const BYTE* start=ip+1; |
| 1948 | U32 curr = (U32)(ip-base); |
| 1949 | |
| 1950 | /* check repCode */ |
| 1951 | { const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr+1, windowLog); |
| 1952 | const U32 repIndex = (U32)(curr+1 - offset_1); |
| 1953 | const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; |
| 1954 | const BYTE* const repMatch = repBase + repIndex; |
| 1955 | if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow */ |
| 1956 | & (offset_1 <= curr+1 - windowLow) ) /* note: we are searching at curr+1 */ |
| 1957 | if (MEM_read32(ip+1) == MEM_read32(repMatch)) { |
| 1958 | /* repcode detected we should take it */ |
| 1959 | const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; |
| 1960 | matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repEnd, prefixStart) + 4; |
| 1961 | if (depth==0) goto _storeSequence; |
| 1962 | } } |
| 1963 | |
| 1964 | /* first search (depth 0) */ |
| 1965 | { size_t ofbCandidate = 999999999; |
| 1966 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict); |
| 1967 | if (ml2 > matchLength) |
| 1968 | matchLength = ml2, start = ip, offBase = ofbCandidate; |
| 1969 | } |
| 1970 | |
| 1971 | if (matchLength < 4) { |
| 1972 | size_t const step = ((size_t)(ip-anchor) >> kSearchStrength); |
| 1973 | ip += step + 1; /* jump faster over incompressible sections */ |
| 1974 | /* Enter the lazy skipping mode once we are skipping more than 8 bytes at a time. |
| 1975 | * In this mode we stop inserting every position into our tables, and only insert |
| 1976 | * positions that we search, which is one in step positions. |
| 1977 | * The exact cutoff is flexible, I've just chosen a number that is reasonably high, |
| 1978 | * so we minimize the compression ratio loss in "normal" scenarios. This mode gets |
| 1979 | * triggered once we've gone 2KB without finding any matches. |
| 1980 | */ |
| 1981 | ms->lazySkipping = step > kLazySkippingStep; |
| 1982 | continue; |
| 1983 | } |
| 1984 | |
| 1985 | /* let's try to find a better solution */ |
| 1986 | if (depth>=1) |
| 1987 | while (ip<ilimit) { |
| 1988 | ip ++; |
| 1989 | curr++; |
| 1990 | /* check repCode */ |
| 1991 | if (offBase) { |
| 1992 | const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog); |
| 1993 | const U32 repIndex = (U32)(curr - offset_1); |
| 1994 | const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; |
| 1995 | const BYTE* const repMatch = repBase + repIndex; |
| 1996 | if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ |
| 1997 | & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ |
| 1998 | if (MEM_read32(ip) == MEM_read32(repMatch)) { |
| 1999 | /* repcode detected */ |
| 2000 | const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; |
| 2001 | size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; |
| 2002 | int const gain2 = (int)(repLength * 3); |
| 2003 | int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1); |
| 2004 | if ((repLength >= 4) && (gain2 > gain1)) |
| 2005 | matchLength = repLength, offBase = REPCODE1_TO_OFFBASE, start = ip; |
| 2006 | } } |
| 2007 | |
| 2008 | /* search match, depth 1 */ |
| 2009 | { size_t ofbCandidate = 999999999; |
| 2010 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict); |
| 2011 | int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */ |
| 2012 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 4); |
| 2013 | if ((ml2 >= 4) && (gain2 > gain1)) { |
| 2014 | matchLength = ml2, offBase = ofbCandidate, start = ip; |
| 2015 | continue; /* search a better one */ |
| 2016 | } } |
| 2017 | |
| 2018 | /* let's find an even better one */ |
| 2019 | if ((depth==2) && (ip<ilimit)) { |
| 2020 | ip ++; |
| 2021 | curr++; |
| 2022 | /* check repCode */ |
| 2023 | if (offBase) { |
| 2024 | const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog); |
| 2025 | const U32 repIndex = (U32)(curr - offset_1); |
| 2026 | const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; |
| 2027 | const BYTE* const repMatch = repBase + repIndex; |
| 2028 | if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ |
| 2029 | & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ |
| 2030 | if (MEM_read32(ip) == MEM_read32(repMatch)) { |
| 2031 | /* repcode detected */ |
| 2032 | const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; |
| 2033 | size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; |
| 2034 | int const gain2 = (int)(repLength * 4); |
| 2035 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1); |
| 2036 | if ((repLength >= 4) && (gain2 > gain1)) |
| 2037 | matchLength = repLength, offBase = REPCODE1_TO_OFFBASE, start = ip; |
| 2038 | } } |
| 2039 | |
| 2040 | /* search match, depth 2 */ |
| 2041 | { size_t ofbCandidate = 999999999; |
| 2042 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict); |
| 2043 | int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */ |
| 2044 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 7); |
| 2045 | if ((ml2 >= 4) && (gain2 > gain1)) { |
| 2046 | matchLength = ml2, offBase = ofbCandidate, start = ip; |
| 2047 | continue; |
| 2048 | } } } |
| 2049 | break; /* nothing found : store previous solution */ |
| 2050 | } |
| 2051 | |
| 2052 | /* catch up */ |
| 2053 | if (OFFBASE_IS_OFFSET(offBase)) { |
| 2054 | U32 const matchIndex = (U32)((size_t)(start-base) - OFFBASE_TO_OFFSET(offBase)); |
| 2055 | const BYTE* match = (matchIndex < dictLimit) ? dictBase + matchIndex : base + matchIndex; |
| 2056 | const BYTE* const mStart = (matchIndex < dictLimit) ? dictStart : prefixStart; |
| 2057 | while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */ |
| 2058 | offset_2 = offset_1; offset_1 = (U32)OFFBASE_TO_OFFSET(offBase); |
| 2059 | } |
| 2060 | |
| 2061 | /* store sequence */ |
| 2062 | _storeSequence: |
| 2063 | { size_t const litLength = (size_t)(start - anchor); |
| 2064 | ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offBase, matchLength); |
| 2065 | anchor = ip = start + matchLength; |
| 2066 | } |
| 2067 | if (ms->lazySkipping) { |
| 2068 | /* We've found a match, disable lazy skipping mode, and refill the hash cache. */ |
| 2069 | if (searchMethod == search_rowHash) { |
| 2070 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit); |
| 2071 | } |
| 2072 | ms->lazySkipping = 0; |
| 2073 | } |
| 2074 | |
| 2075 | /* check immediate repcode */ |
| 2076 | while (ip <= ilimit) { |
| 2077 | const U32 repCurrent = (U32)(ip-base); |
| 2078 | const U32 windowLow = ZSTD_getLowestMatchIndex(ms, repCurrent, windowLog); |
| 2079 | const U32 repIndex = repCurrent - offset_2; |
| 2080 | const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; |
| 2081 | const BYTE* const repMatch = repBase + repIndex; |
| 2082 | if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ |
| 2083 | & (offset_2 <= repCurrent - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ |
| 2084 | if (MEM_read32(ip) == MEM_read32(repMatch)) { |
| 2085 | /* repcode detected we should take it */ |
| 2086 | const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; |
| 2087 | matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; |
| 2088 | offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap offset history */ |
| 2089 | ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength); |
| 2090 | ip += matchLength; |
| 2091 | anchor = ip; |
| 2092 | continue; /* faster when present ... (?) */ |
| 2093 | } |
| 2094 | break; |
| 2095 | } } |
| 2096 | |
| 2097 | /* Save reps for next block */ |
| 2098 | rep[0] = offset_1; |
| 2099 | rep[1] = offset_2; |
| 2100 | |
| 2101 | /* Return the last literals size */ |
| 2102 | return (size_t)(iend - anchor); |
| 2103 | } |
| 2104 | |
| 2105 | |
| 2106 | size_t ZSTD_compressBlock_greedy_extDict( |
| 2107 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 2108 | void const* src, size_t srcSize) |
| 2109 | { |
| 2110 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0); |
| 2111 | } |
| 2112 | |
| 2113 | size_t ZSTD_compressBlock_lazy_extDict( |
| 2114 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 2115 | void const* src, size_t srcSize) |
| 2116 | |
| 2117 | { |
| 2118 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1); |
| 2119 | } |
| 2120 | |
| 2121 | size_t ZSTD_compressBlock_lazy2_extDict( |
| 2122 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 2123 | void const* src, size_t srcSize) |
| 2124 | |
| 2125 | { |
| 2126 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2); |
| 2127 | } |
| 2128 | |
| 2129 | size_t ZSTD_compressBlock_btlazy2_extDict( |
| 2130 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 2131 | void const* src, size_t srcSize) |
| 2132 | |
| 2133 | { |
| 2134 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2); |
| 2135 | } |
| 2136 | |
| 2137 | size_t ZSTD_compressBlock_greedy_extDict_row( |
| 2138 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 2139 | void const* src, size_t srcSize) |
| 2140 | { |
| 2141 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0); |
| 2142 | } |
| 2143 | |
| 2144 | size_t ZSTD_compressBlock_lazy_extDict_row( |
| 2145 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 2146 | void const* src, size_t srcSize) |
| 2147 | |
| 2148 | { |
| 2149 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1); |
| 2150 | } |
| 2151 | |
| 2152 | size_t ZSTD_compressBlock_lazy2_extDict_row( |
| 2153 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
| 2154 | void const* src, size_t srcSize) |
| 2155 | { |
| 2156 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2); |
| 2157 | } |