1 // SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
2 /*
3 * Copyright (c) Meta Platforms, Inc. and affiliates.
4 * All rights reserved.
5 *
6 * This source code is licensed under both the BSD-style license (found in the
7 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
8 * in the COPYING file in the root directory of this source tree).
9 * You may select, at your option, one of the above-listed licenses.
10 */
11
12 #include "zstd_compress_internal.h"
13 #include "zstd_lazy.h"
14 #include "../common/bits.h" /* ZSTD_countTrailingZeros64 */
15
16 #if !defined(ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR) \
17 || !defined(ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR) \
18 || !defined(ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR) \
19 || !defined(ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR)
20
21 #define kLazySkippingStep 8
22
23
24 /*-*************************************
25 * Binary Tree search
26 ***************************************/
27
28 static
29 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_updateDUBT(ZSTD_MatchState_t * ms,const BYTE * ip,const BYTE * iend,U32 mls)30 void ZSTD_updateDUBT(ZSTD_MatchState_t* ms,
31 const BYTE* ip, const BYTE* iend,
32 U32 mls)
33 {
34 const ZSTD_compressionParameters* const cParams = &ms->cParams;
35 U32* const hashTable = ms->hashTable;
36 U32 const hashLog = cParams->hashLog;
37
38 U32* const bt = ms->chainTable;
39 U32 const btLog = cParams->chainLog - 1;
40 U32 const btMask = (1 << btLog) - 1;
41
42 const BYTE* const base = ms->window.base;
43 U32 const target = (U32)(ip - base);
44 U32 idx = ms->nextToUpdate;
45
46 if (idx != target)
47 DEBUGLOG(7, "ZSTD_updateDUBT, from %u to %u (dictLimit:%u)",
48 idx, target, ms->window.dictLimit);
49 assert(ip + 8 <= iend); /* condition for ZSTD_hashPtr */
50 (void)iend;
51
52 assert(idx >= ms->window.dictLimit); /* condition for valid base+idx */
53 for ( ; idx < target ; idx++) {
54 size_t const h = ZSTD_hashPtr(base + idx, hashLog, mls); /* assumption : ip + 8 <= iend */
55 U32 const matchIndex = hashTable[h];
56
57 U32* const nextCandidatePtr = bt + 2*(idx&btMask);
58 U32* const sortMarkPtr = nextCandidatePtr + 1;
59
60 DEBUGLOG(8, "ZSTD_updateDUBT: insert %u", idx);
61 hashTable[h] = idx; /* Update Hash Table */
62 *nextCandidatePtr = matchIndex; /* update BT like a chain */
63 *sortMarkPtr = ZSTD_DUBT_UNSORTED_MARK;
64 }
65 ms->nextToUpdate = target;
66 }
67
68
69 /* ZSTD_insertDUBT1() :
70 * sort one already inserted but unsorted position
71 * assumption : curr >= btlow == (curr - btmask)
72 * doesn't fail */
73 static
74 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_insertDUBT1(const ZSTD_MatchState_t * ms,U32 curr,const BYTE * inputEnd,U32 nbCompares,U32 btLow,const ZSTD_dictMode_e dictMode)75 void ZSTD_insertDUBT1(const ZSTD_MatchState_t* ms,
76 U32 curr, const BYTE* inputEnd,
77 U32 nbCompares, U32 btLow,
78 const ZSTD_dictMode_e dictMode)
79 {
80 const ZSTD_compressionParameters* const cParams = &ms->cParams;
81 U32* const bt = ms->chainTable;
82 U32 const btLog = cParams->chainLog - 1;
83 U32 const btMask = (1 << btLog) - 1;
84 size_t commonLengthSmaller=0, commonLengthLarger=0;
85 const BYTE* const base = ms->window.base;
86 const BYTE* const dictBase = ms->window.dictBase;
87 const U32 dictLimit = ms->window.dictLimit;
88 const BYTE* const ip = (curr>=dictLimit) ? base + curr : dictBase + curr;
89 const BYTE* const iend = (curr>=dictLimit) ? inputEnd : dictBase + dictLimit;
90 const BYTE* const dictEnd = dictBase + dictLimit;
91 const BYTE* const prefixStart = base + dictLimit;
92 const BYTE* match;
93 U32* smallerPtr = bt + 2*(curr&btMask);
94 U32* largerPtr = smallerPtr + 1;
95 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) */
96 U32 dummy32; /* to be nullified at the end */
97 U32 const windowValid = ms->window.lowLimit;
98 U32 const maxDistance = 1U << cParams->windowLog;
99 U32 const windowLow = (curr - windowValid > maxDistance) ? curr - maxDistance : windowValid;
100
101
102 DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)",
103 curr, dictLimit, windowLow);
104 assert(curr >= btLow);
105 assert(ip < iend); /* condition for ZSTD_count */
106
107 for (; nbCompares && (matchIndex > windowLow); --nbCompares) {
108 U32* const nextPtr = bt + 2*(matchIndex & btMask);
109 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
110 assert(matchIndex < curr);
111 /* note : all candidates are now supposed sorted,
112 * but it's still possible to have nextPtr[1] == ZSTD_DUBT_UNSORTED_MARK
113 * when a real index has the same value as ZSTD_DUBT_UNSORTED_MARK */
114
115 if ( (dictMode != ZSTD_extDict)
116 || (matchIndex+matchLength >= dictLimit) /* both in current segment*/
117 || (curr < dictLimit) /* both in extDict */) {
118 const BYTE* const mBase = ( (dictMode != ZSTD_extDict)
119 || (matchIndex+matchLength >= dictLimit)) ?
120 base : dictBase;
121 assert( (matchIndex+matchLength >= dictLimit) /* might be wrong if extDict is incorrectly set to 0 */
122 || (curr < dictLimit) );
123 match = mBase + matchIndex;
124 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend);
125 } else {
126 match = dictBase + matchIndex;
127 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
128 if (matchIndex+matchLength >= dictLimit)
129 match = base + matchIndex; /* preparation for next read of match[matchLength] */
130 }
131
132 DEBUGLOG(8, "ZSTD_insertDUBT1: comparing %u with %u : found %u common bytes ",
133 curr, matchIndex, (U32)matchLength);
134
135 if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */
136 break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */
137 }
138
139 if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */
140 /* match is smaller than current */
141 *smallerPtr = matchIndex; /* update smaller idx */
142 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
143 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */
144 DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is smaller : next => %u",
145 matchIndex, btLow, nextPtr[1]);
146 smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */
147 matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */
148 } else {
149 /* match is larger than current */
150 *largerPtr = matchIndex;
151 commonLengthLarger = matchLength;
152 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */
153 DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is larger => %u",
154 matchIndex, btLow, nextPtr[0]);
155 largerPtr = nextPtr;
156 matchIndex = nextPtr[0];
157 } }
158
159 *smallerPtr = *largerPtr = 0;
160 }
161
162
163 static
164 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_DUBT_findBetterDictMatch(const ZSTD_MatchState_t * ms,const BYTE * const ip,const BYTE * const iend,size_t * offsetPtr,size_t bestLength,U32 nbCompares,U32 const mls,const ZSTD_dictMode_e dictMode)165 size_t ZSTD_DUBT_findBetterDictMatch (
166 const ZSTD_MatchState_t* ms,
167 const BYTE* const ip, const BYTE* const iend,
168 size_t* offsetPtr,
169 size_t bestLength,
170 U32 nbCompares,
171 U32 const mls,
172 const ZSTD_dictMode_e dictMode)
173 {
174 const ZSTD_MatchState_t * const dms = ms->dictMatchState;
175 const ZSTD_compressionParameters* const dmsCParams = &dms->cParams;
176 const U32 * const dictHashTable = dms->hashTable;
177 U32 const hashLog = dmsCParams->hashLog;
178 size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
179 U32 dictMatchIndex = dictHashTable[h];
180
181 const BYTE* const base = ms->window.base;
182 const BYTE* const prefixStart = base + ms->window.dictLimit;
183 U32 const curr = (U32)(ip-base);
184 const BYTE* const dictBase = dms->window.base;
185 const BYTE* const dictEnd = dms->window.nextSrc;
186 U32 const dictHighLimit = (U32)(dms->window.nextSrc - dms->window.base);
187 U32 const dictLowLimit = dms->window.lowLimit;
188 U32 const dictIndexDelta = ms->window.lowLimit - dictHighLimit;
189
190 U32* const dictBt = dms->chainTable;
191 U32 const btLog = dmsCParams->chainLog - 1;
192 U32 const btMask = (1 << btLog) - 1;
193 U32 const btLow = (btMask >= dictHighLimit - dictLowLimit) ? dictLowLimit : dictHighLimit - btMask;
194
195 size_t commonLengthSmaller=0, commonLengthLarger=0;
196
197 (void)dictMode;
198 assert(dictMode == ZSTD_dictMatchState);
199
200 for (; nbCompares && (dictMatchIndex > dictLowLimit); --nbCompares) {
201 U32* const nextPtr = dictBt + 2*(dictMatchIndex & btMask);
202 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
203 const BYTE* match = dictBase + dictMatchIndex;
204 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
205 if (dictMatchIndex+matchLength >= dictHighLimit)
206 match = base + dictMatchIndex + dictIndexDelta; /* to prepare for next usage of match[matchLength] */
207
208 if (matchLength > bestLength) {
209 U32 matchIndex = dictMatchIndex + dictIndexDelta;
210 if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) ) {
211 DEBUGLOG(9, "ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u)",
212 curr, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, OFFSET_TO_OFFBASE(curr - matchIndex), dictMatchIndex, matchIndex);
213 bestLength = matchLength, *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex);
214 }
215 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 */
216 break; /* drop, to guarantee consistency (miss a little bit of compression) */
217 }
218 }
219
220 if (match[matchLength] < ip[matchLength]) {
221 if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */
222 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
223 dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */
224 } else {
225 /* match is larger than current */
226 if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */
227 commonLengthLarger = matchLength;
228 dictMatchIndex = nextPtr[0];
229 }
230 }
231
232 if (bestLength >= MINMATCH) {
233 U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offsetPtr); (void)mIndex;
234 DEBUGLOG(8, "ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
235 curr, (U32)bestLength, (U32)*offsetPtr, mIndex);
236 }
237 return bestLength;
238
239 }
240
241
242 static
243 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_DUBT_findBestMatch(ZSTD_MatchState_t * ms,const BYTE * const ip,const BYTE * const iend,size_t * offBasePtr,U32 const mls,const ZSTD_dictMode_e dictMode)244 size_t ZSTD_DUBT_findBestMatch(ZSTD_MatchState_t* ms,
245 const BYTE* const ip, const BYTE* const iend,
246 size_t* offBasePtr,
247 U32 const mls,
248 const ZSTD_dictMode_e dictMode)
249 {
250 const ZSTD_compressionParameters* const cParams = &ms->cParams;
251 U32* const hashTable = ms->hashTable;
252 U32 const hashLog = cParams->hashLog;
253 size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
254 U32 matchIndex = hashTable[h];
255
256 const BYTE* const base = ms->window.base;
257 U32 const curr = (U32)(ip-base);
258 U32 const windowLow = ZSTD_getLowestMatchIndex(ms, curr, cParams->windowLog);
259
260 U32* const bt = ms->chainTable;
261 U32 const btLog = cParams->chainLog - 1;
262 U32 const btMask = (1 << btLog) - 1;
263 U32 const btLow = (btMask >= curr) ? 0 : curr - btMask;
264 U32 const unsortLimit = MAX(btLow, windowLow);
265
266 U32* nextCandidate = bt + 2*(matchIndex&btMask);
267 U32* unsortedMark = bt + 2*(matchIndex&btMask) + 1;
268 U32 nbCompares = 1U << cParams->searchLog;
269 U32 nbCandidates = nbCompares;
270 U32 previousCandidate = 0;
271
272 DEBUGLOG(7, "ZSTD_DUBT_findBestMatch (%u) ", curr);
273 assert(ip <= iend-8); /* required for h calculation */
274 assert(dictMode != ZSTD_dedicatedDictSearch);
275
276 /* reach end of unsorted candidates list */
277 while ( (matchIndex > unsortLimit)
278 && (*unsortedMark == ZSTD_DUBT_UNSORTED_MARK)
279 && (nbCandidates > 1) ) {
280 DEBUGLOG(8, "ZSTD_DUBT_findBestMatch: candidate %u is unsorted",
281 matchIndex);
282 *unsortedMark = previousCandidate; /* the unsortedMark becomes a reversed chain, to move up back to original position */
283 previousCandidate = matchIndex;
284 matchIndex = *nextCandidate;
285 nextCandidate = bt + 2*(matchIndex&btMask);
286 unsortedMark = bt + 2*(matchIndex&btMask) + 1;
287 nbCandidates --;
288 }
289
290 /* nullify last candidate if it's still unsorted
291 * simplification, detrimental to compression ratio, beneficial for speed */
292 if ( (matchIndex > unsortLimit)
293 && (*unsortedMark==ZSTD_DUBT_UNSORTED_MARK) ) {
294 DEBUGLOG(7, "ZSTD_DUBT_findBestMatch: nullify last unsorted candidate %u",
295 matchIndex);
296 *nextCandidate = *unsortedMark = 0;
297 }
298
299 /* batch sort stacked candidates */
300 matchIndex = previousCandidate;
301 while (matchIndex) { /* will end on matchIndex == 0 */
302 U32* const nextCandidateIdxPtr = bt + 2*(matchIndex&btMask) + 1;
303 U32 const nextCandidateIdx = *nextCandidateIdxPtr;
304 ZSTD_insertDUBT1(ms, matchIndex, iend,
305 nbCandidates, unsortLimit, dictMode);
306 matchIndex = nextCandidateIdx;
307 nbCandidates++;
308 }
309
310 /* find longest match */
311 { size_t commonLengthSmaller = 0, commonLengthLarger = 0;
312 const BYTE* const dictBase = ms->window.dictBase;
313 const U32 dictLimit = ms->window.dictLimit;
314 const BYTE* const dictEnd = dictBase + dictLimit;
315 const BYTE* const prefixStart = base + dictLimit;
316 U32* smallerPtr = bt + 2*(curr&btMask);
317 U32* largerPtr = bt + 2*(curr&btMask) + 1;
318 U32 matchEndIdx = curr + 8 + 1;
319 U32 dummy32; /* to be nullified at the end */
320 size_t bestLength = 0;
321
322 matchIndex = hashTable[h];
323 hashTable[h] = curr; /* Update Hash Table */
324
325 for (; nbCompares && (matchIndex > windowLow); --nbCompares) {
326 U32* const nextPtr = bt + 2*(matchIndex & btMask);
327 size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
328 const BYTE* match;
329
330 if ((dictMode != ZSTD_extDict) || (matchIndex+matchLength >= dictLimit)) {
331 match = base + matchIndex;
332 matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend);
333 } else {
334 match = dictBase + matchIndex;
335 matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
336 if (matchIndex+matchLength >= dictLimit)
337 match = base + matchIndex; /* to prepare for next usage of match[matchLength] */
338 }
339
340 if (matchLength > bestLength) {
341 if (matchLength > matchEndIdx - matchIndex)
342 matchEndIdx = matchIndex + (U32)matchLength;
343 if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr - matchIndex + 1) - ZSTD_highbit32((U32)*offBasePtr)) )
344 bestLength = matchLength, *offBasePtr = OFFSET_TO_OFFBASE(curr - matchIndex);
345 if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */
346 if (dictMode == ZSTD_dictMatchState) {
347 nbCompares = 0; /* in addition to avoiding checking any
348 * further in this loop, make sure we
349 * skip checking in the dictionary. */
350 }
351 break; /* drop, to guarantee consistency (miss a little bit of compression) */
352 }
353 }
354
355 if (match[matchLength] < ip[matchLength]) {
356 /* match is smaller than current */
357 *smallerPtr = matchIndex; /* update smaller idx */
358 commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
359 if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */
360 smallerPtr = nextPtr+1; /* new "smaller" => larger of match */
361 matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */
362 } else {
363 /* match is larger than current */
364 *largerPtr = matchIndex;
365 commonLengthLarger = matchLength;
366 if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */
367 largerPtr = nextPtr;
368 matchIndex = nextPtr[0];
369 } }
370
371 *smallerPtr = *largerPtr = 0;
372
373 assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
374 if (dictMode == ZSTD_dictMatchState && nbCompares) {
375 bestLength = ZSTD_DUBT_findBetterDictMatch(
376 ms, ip, iend,
377 offBasePtr, bestLength, nbCompares,
378 mls, dictMode);
379 }
380
381 assert(matchEndIdx > curr+8); /* ensure nextToUpdate is increased */
382 ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */
383 if (bestLength >= MINMATCH) {
384 U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offBasePtr); (void)mIndex;
385 DEBUGLOG(8, "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
386 curr, (U32)bestLength, (U32)*offBasePtr, mIndex);
387 }
388 return bestLength;
389 }
390 }
391
392
393 /* ZSTD_BtFindBestMatch() : Tree updater, providing best match */
394 FORCE_INLINE_TEMPLATE
395 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_BtFindBestMatch(ZSTD_MatchState_t * ms,const BYTE * const ip,const BYTE * const iLimit,size_t * offBasePtr,const U32 mls,const ZSTD_dictMode_e dictMode)396 size_t ZSTD_BtFindBestMatch( ZSTD_MatchState_t* ms,
397 const BYTE* const ip, const BYTE* const iLimit,
398 size_t* offBasePtr,
399 const U32 mls /* template */,
400 const ZSTD_dictMode_e dictMode)
401 {
402 DEBUGLOG(7, "ZSTD_BtFindBestMatch");
403 if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */
404 ZSTD_updateDUBT(ms, ip, iLimit, mls);
405 return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offBasePtr, mls, dictMode);
406 }
407
408 /* *********************************
409 * Dedicated dict search
410 ***********************************/
411
ZSTD_dedicatedDictSearch_lazy_loadDictionary(ZSTD_MatchState_t * ms,const BYTE * const ip)412 void ZSTD_dedicatedDictSearch_lazy_loadDictionary(ZSTD_MatchState_t* ms, const BYTE* const ip)
413 {
414 const BYTE* const base = ms->window.base;
415 U32 const target = (U32)(ip - base);
416 U32* const hashTable = ms->hashTable;
417 U32* const chainTable = ms->chainTable;
418 U32 const chainSize = 1 << ms->cParams.chainLog;
419 U32 idx = ms->nextToUpdate;
420 U32 const minChain = chainSize < target - idx ? target - chainSize : idx;
421 U32 const bucketSize = 1 << ZSTD_LAZY_DDSS_BUCKET_LOG;
422 U32 const cacheSize = bucketSize - 1;
423 U32 const chainAttempts = (1 << ms->cParams.searchLog) - cacheSize;
424 U32 const chainLimit = chainAttempts > 255 ? 255 : chainAttempts;
425
426 /* We know the hashtable is oversized by a factor of `bucketSize`.
427 * We are going to temporarily pretend `bucketSize == 1`, keeping only a
428 * single entry. We will use the rest of the space to construct a temporary
429 * chaintable.
430 */
431 U32 const hashLog = ms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG;
432 U32* const tmpHashTable = hashTable;
433 U32* const tmpChainTable = hashTable + ((size_t)1 << hashLog);
434 U32 const tmpChainSize = (U32)((1 << ZSTD_LAZY_DDSS_BUCKET_LOG) - 1) << hashLog;
435 U32 const tmpMinChain = tmpChainSize < target ? target - tmpChainSize : idx;
436 U32 hashIdx;
437
438 assert(ms->cParams.chainLog <= 24);
439 assert(ms->cParams.hashLog > ms->cParams.chainLog);
440 assert(idx != 0);
441 assert(tmpMinChain <= minChain);
442
443 /* fill conventional hash table and conventional chain table */
444 for ( ; idx < target; idx++) {
445 U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch);
446 if (idx >= tmpMinChain) {
447 tmpChainTable[idx - tmpMinChain] = hashTable[h];
448 }
449 tmpHashTable[h] = idx;
450 }
451
452 /* sort chains into ddss chain table */
453 {
454 U32 chainPos = 0;
455 for (hashIdx = 0; hashIdx < (1U << hashLog); hashIdx++) {
456 U32 count;
457 U32 countBeyondMinChain = 0;
458 U32 i = tmpHashTable[hashIdx];
459 for (count = 0; i >= tmpMinChain && count < cacheSize; count++) {
460 /* skip through the chain to the first position that won't be
461 * in the hash cache bucket */
462 if (i < minChain) {
463 countBeyondMinChain++;
464 }
465 i = tmpChainTable[i - tmpMinChain];
466 }
467 if (count == cacheSize) {
468 for (count = 0; count < chainLimit;) {
469 if (i < minChain) {
470 if (!i || ++countBeyondMinChain > cacheSize) {
471 /* only allow pulling `cacheSize` number of entries
472 * into the cache or chainTable beyond `minChain`,
473 * to replace the entries pulled out of the
474 * chainTable into the cache. This lets us reach
475 * back further without increasing the total number
476 * of entries in the chainTable, guaranteeing the
477 * DDSS chain table will fit into the space
478 * allocated for the regular one. */
479 break;
480 }
481 }
482 chainTable[chainPos++] = i;
483 count++;
484 if (i < tmpMinChain) {
485 break;
486 }
487 i = tmpChainTable[i - tmpMinChain];
488 }
489 } else {
490 count = 0;
491 }
492 if (count) {
493 tmpHashTable[hashIdx] = ((chainPos - count) << 8) + count;
494 } else {
495 tmpHashTable[hashIdx] = 0;
496 }
497 }
498 assert(chainPos <= chainSize); /* I believe this is guaranteed... */
499 }
500
501 /* move chain pointers into the last entry of each hash bucket */
502 for (hashIdx = (1 << hashLog); hashIdx; ) {
503 U32 const bucketIdx = --hashIdx << ZSTD_LAZY_DDSS_BUCKET_LOG;
504 U32 const chainPackedPointer = tmpHashTable[hashIdx];
505 U32 i;
506 for (i = 0; i < cacheSize; i++) {
507 hashTable[bucketIdx + i] = 0;
508 }
509 hashTable[bucketIdx + bucketSize - 1] = chainPackedPointer;
510 }
511
512 /* fill the buckets of the hash table */
513 for (idx = ms->nextToUpdate; idx < target; idx++) {
514 U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch)
515 << ZSTD_LAZY_DDSS_BUCKET_LOG;
516 U32 i;
517 /* Shift hash cache down 1. */
518 for (i = cacheSize - 1; i; i--)
519 hashTable[h + i] = hashTable[h + i - 1];
520 hashTable[h] = idx;
521 }
522
523 ms->nextToUpdate = target;
524 }
525
526 /* Returns the longest match length found in the dedicated dict search structure.
527 * If none are longer than the argument ml, then ml will be returned.
528 */
529 FORCE_INLINE_TEMPLATE
ZSTD_dedicatedDictSearch_lazy_search(size_t * offsetPtr,size_t ml,U32 nbAttempts,const ZSTD_MatchState_t * const dms,const BYTE * const ip,const BYTE * const iLimit,const BYTE * const prefixStart,const U32 curr,const U32 dictLimit,const size_t ddsIdx)530 size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nbAttempts,
531 const ZSTD_MatchState_t* const dms,
532 const BYTE* const ip, const BYTE* const iLimit,
533 const BYTE* const prefixStart, const U32 curr,
534 const U32 dictLimit, const size_t ddsIdx) {
535 const U32 ddsLowestIndex = dms->window.dictLimit;
536 const BYTE* const ddsBase = dms->window.base;
537 const BYTE* const ddsEnd = dms->window.nextSrc;
538 const U32 ddsSize = (U32)(ddsEnd - ddsBase);
539 const U32 ddsIndexDelta = dictLimit - ddsSize;
540 const U32 bucketSize = (1 << ZSTD_LAZY_DDSS_BUCKET_LOG);
541 const U32 bucketLimit = nbAttempts < bucketSize - 1 ? nbAttempts : bucketSize - 1;
542 U32 ddsAttempt;
543 U32 matchIndex;
544
545 for (ddsAttempt = 0; ddsAttempt < bucketSize - 1; ddsAttempt++) {
546 PREFETCH_L1(ddsBase + dms->hashTable[ddsIdx + ddsAttempt]);
547 }
548
549 {
550 U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1];
551 U32 const chainIndex = chainPackedPointer >> 8;
552
553 PREFETCH_L1(&dms->chainTable[chainIndex]);
554 }
555
556 for (ddsAttempt = 0; ddsAttempt < bucketLimit; ddsAttempt++) {
557 size_t currentMl=0;
558 const BYTE* match;
559 matchIndex = dms->hashTable[ddsIdx + ddsAttempt];
560 match = ddsBase + matchIndex;
561
562 if (!matchIndex) {
563 return ml;
564 }
565
566 /* guaranteed by table construction */
567 (void)ddsLowestIndex;
568 assert(matchIndex >= ddsLowestIndex);
569 assert(match+4 <= ddsEnd);
570 if (MEM_read32(match) == MEM_read32(ip)) {
571 /* assumption : matchIndex <= dictLimit-4 (by table construction) */
572 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4;
573 }
574
575 /* save best solution */
576 if (currentMl > ml) {
577 ml = currentMl;
578 *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta));
579 if (ip+currentMl == iLimit) {
580 /* best possible, avoids read overflow on next attempt */
581 return ml;
582 }
583 }
584 }
585
586 {
587 U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1];
588 U32 chainIndex = chainPackedPointer >> 8;
589 U32 const chainLength = chainPackedPointer & 0xFF;
590 U32 const chainAttempts = nbAttempts - ddsAttempt;
591 U32 const chainLimit = chainAttempts > chainLength ? chainLength : chainAttempts;
592 U32 chainAttempt;
593
594 for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++) {
595 PREFETCH_L1(ddsBase + dms->chainTable[chainIndex + chainAttempt]);
596 }
597
598 for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++, chainIndex++) {
599 size_t currentMl=0;
600 const BYTE* match;
601 matchIndex = dms->chainTable[chainIndex];
602 match = ddsBase + matchIndex;
603
604 /* guaranteed by table construction */
605 assert(matchIndex >= ddsLowestIndex);
606 assert(match+4 <= ddsEnd);
607 if (MEM_read32(match) == MEM_read32(ip)) {
608 /* assumption : matchIndex <= dictLimit-4 (by table construction) */
609 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4;
610 }
611
612 /* save best solution */
613 if (currentMl > ml) {
614 ml = currentMl;
615 *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta));
616 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
617 }
618 }
619 }
620 return ml;
621 }
622
623
624 /* *********************************
625 * Hash Chain
626 ***********************************/
627 #define NEXT_IN_CHAIN(d, mask) chainTable[(d) & (mask)]
628
629 /* Update chains up to ip (excluded)
630 Assumption : always within prefix (i.e. not within extDict) */
631 FORCE_INLINE_TEMPLATE
632 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_insertAndFindFirstIndex_internal(ZSTD_MatchState_t * ms,const ZSTD_compressionParameters * const cParams,const BYTE * ip,U32 const mls,U32 const lazySkipping)633 U32 ZSTD_insertAndFindFirstIndex_internal(
634 ZSTD_MatchState_t* ms,
635 const ZSTD_compressionParameters* const cParams,
636 const BYTE* ip, U32 const mls, U32 const lazySkipping)
637 {
638 U32* const hashTable = ms->hashTable;
639 const U32 hashLog = cParams->hashLog;
640 U32* const chainTable = ms->chainTable;
641 const U32 chainMask = (1 << cParams->chainLog) - 1;
642 const BYTE* const base = ms->window.base;
643 const U32 target = (U32)(ip - base);
644 U32 idx = ms->nextToUpdate;
645
646 while(idx < target) { /* catch up */
647 size_t const h = ZSTD_hashPtr(base+idx, hashLog, mls);
648 NEXT_IN_CHAIN(idx, chainMask) = hashTable[h];
649 hashTable[h] = idx;
650 idx++;
651 /* Stop inserting every position when in the lazy skipping mode. */
652 if (lazySkipping)
653 break;
654 }
655
656 ms->nextToUpdate = target;
657 return hashTable[ZSTD_hashPtr(ip, hashLog, mls)];
658 }
659
ZSTD_insertAndFindFirstIndex(ZSTD_MatchState_t * ms,const BYTE * ip)660 U32 ZSTD_insertAndFindFirstIndex(ZSTD_MatchState_t* ms, const BYTE* ip) {
661 const ZSTD_compressionParameters* const cParams = &ms->cParams;
662 return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, ms->cParams.minMatch, /* lazySkipping*/ 0);
663 }
664
665 /* inlining is important to hardwire a hot branch (template emulation) */
666 FORCE_INLINE_TEMPLATE
667 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_HcFindBestMatch(ZSTD_MatchState_t * ms,const BYTE * const ip,const BYTE * const iLimit,size_t * offsetPtr,const U32 mls,const ZSTD_dictMode_e dictMode)668 size_t ZSTD_HcFindBestMatch(
669 ZSTD_MatchState_t* ms,
670 const BYTE* const ip, const BYTE* const iLimit,
671 size_t* offsetPtr,
672 const U32 mls, const ZSTD_dictMode_e dictMode)
673 {
674 const ZSTD_compressionParameters* const cParams = &ms->cParams;
675 U32* const chainTable = ms->chainTable;
676 const U32 chainSize = (1 << cParams->chainLog);
677 const U32 chainMask = chainSize-1;
678 const BYTE* const base = ms->window.base;
679 const BYTE* const dictBase = ms->window.dictBase;
680 const U32 dictLimit = ms->window.dictLimit;
681 const BYTE* const prefixStart = base + dictLimit;
682 const BYTE* const dictEnd = dictBase + dictLimit;
683 const U32 curr = (U32)(ip-base);
684 const U32 maxDistance = 1U << cParams->windowLog;
685 const U32 lowestValid = ms->window.lowLimit;
686 const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid;
687 const U32 isDictionary = (ms->loadedDictEnd != 0);
688 const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance;
689 const U32 minChain = curr > chainSize ? curr - chainSize : 0;
690 U32 nbAttempts = 1U << cParams->searchLog;
691 size_t ml=4-1;
692
693 const ZSTD_MatchState_t* const dms = ms->dictMatchState;
694 const U32 ddsHashLog = dictMode == ZSTD_dedicatedDictSearch
695 ? dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG : 0;
696 const size_t ddsIdx = dictMode == ZSTD_dedicatedDictSearch
697 ? ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG : 0;
698
699 U32 matchIndex;
700
701 if (dictMode == ZSTD_dedicatedDictSearch) {
702 const U32* entry = &dms->hashTable[ddsIdx];
703 PREFETCH_L1(entry);
704 }
705
706 /* HC4 match finder */
707 matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls, ms->lazySkipping);
708
709 for ( ; (matchIndex>=lowLimit) & (nbAttempts>0) ; nbAttempts--) {
710 size_t currentMl=0;
711 if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) {
712 const BYTE* const match = base + matchIndex;
713 assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */
714 /* read 4B starting from (match + ml + 1 - sizeof(U32)) */
715 if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */
716 currentMl = ZSTD_count(ip, match, iLimit);
717 } else {
718 const BYTE* const match = dictBase + matchIndex;
719 assert(match+4 <= dictEnd);
720 if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
721 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4;
722 }
723
724 /* save best solution */
725 if (currentMl > ml) {
726 ml = currentMl;
727 *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex);
728 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
729 }
730
731 if (matchIndex <= minChain) break;
732 matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
733 }
734
735 assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
736 if (dictMode == ZSTD_dedicatedDictSearch) {
737 ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts, dms,
738 ip, iLimit, prefixStart, curr, dictLimit, ddsIdx);
739 } else if (dictMode == ZSTD_dictMatchState) {
740 const U32* const dmsChainTable = dms->chainTable;
741 const U32 dmsChainSize = (1 << dms->cParams.chainLog);
742 const U32 dmsChainMask = dmsChainSize - 1;
743 const U32 dmsLowestIndex = dms->window.dictLimit;
744 const BYTE* const dmsBase = dms->window.base;
745 const BYTE* const dmsEnd = dms->window.nextSrc;
746 const U32 dmsSize = (U32)(dmsEnd - dmsBase);
747 const U32 dmsIndexDelta = dictLimit - dmsSize;
748 const U32 dmsMinChain = dmsSize > dmsChainSize ? dmsSize - dmsChainSize : 0;
749
750 matchIndex = dms->hashTable[ZSTD_hashPtr(ip, dms->cParams.hashLog, mls)];
751
752 for ( ; (matchIndex>=dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--) {
753 size_t currentMl=0;
754 const BYTE* const match = dmsBase + matchIndex;
755 assert(match+4 <= dmsEnd);
756 if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
757 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4;
758
759 /* save best solution */
760 if (currentMl > ml) {
761 ml = currentMl;
762 assert(curr > matchIndex + dmsIndexDelta);
763 *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta));
764 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
765 }
766
767 if (matchIndex <= dmsMinChain) break;
768
769 matchIndex = dmsChainTable[matchIndex & dmsChainMask];
770 }
771 }
772
773 return ml;
774 }
775
776 /* *********************************
777 * (SIMD) Row-based matchfinder
778 ***********************************/
779 /* Constants for row-based hash */
780 #define ZSTD_ROW_HASH_TAG_MASK ((1u << ZSTD_ROW_HASH_TAG_BITS) - 1)
781 #define ZSTD_ROW_HASH_MAX_ENTRIES 64 /* absolute maximum number of entries per row, for all configurations */
782
783 #define ZSTD_ROW_HASH_CACHE_MASK (ZSTD_ROW_HASH_CACHE_SIZE - 1)
784
785 typedef U64 ZSTD_VecMask; /* Clarifies when we are interacting with a U64 representing a mask of matches */
786
787 /* ZSTD_VecMask_next():
788 * Starting from the LSB, returns the idx of the next non-zero bit.
789 * Basically counting the nb of trailing zeroes.
790 */
ZSTD_VecMask_next(ZSTD_VecMask val)791 MEM_STATIC U32 ZSTD_VecMask_next(ZSTD_VecMask val) {
792 return ZSTD_countTrailingZeros64(val);
793 }
794
795 /* ZSTD_row_nextIndex():
796 * Returns the next index to insert at within a tagTable row, and updates the "head"
797 * value to reflect the update. Essentially cycles backwards from [1, {entries per row})
798 */
ZSTD_row_nextIndex(BYTE * const tagRow,U32 const rowMask)799 FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextIndex(BYTE* const tagRow, U32 const rowMask) {
800 U32 next = (*tagRow-1) & rowMask;
801 next += (next == 0) ? rowMask : 0; /* skip first position */
802 *tagRow = (BYTE)next;
803 return next;
804 }
805
806 /* ZSTD_isAligned():
807 * Checks that a pointer is aligned to "align" bytes which must be a power of 2.
808 */
ZSTD_isAligned(void const * ptr,size_t align)809 MEM_STATIC int ZSTD_isAligned(void const* ptr, size_t align) {
810 assert((align & (align - 1)) == 0);
811 return (((size_t)ptr) & (align - 1)) == 0;
812 }
813
814 /* ZSTD_row_prefetch():
815 * Performs prefetching for the hashTable and tagTable at a given row.
816 */
ZSTD_row_prefetch(U32 const * hashTable,BYTE const * tagTable,U32 const relRow,U32 const rowLog)817 FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, BYTE const* tagTable, U32 const relRow, U32 const rowLog) {
818 PREFETCH_L1(hashTable + relRow);
819 if (rowLog >= 5) {
820 PREFETCH_L1(hashTable + relRow + 16);
821 /* Note: prefetching more of the hash table does not appear to be beneficial for 128-entry rows */
822 }
823 PREFETCH_L1(tagTable + relRow);
824 if (rowLog == 6) {
825 PREFETCH_L1(tagTable + relRow + 32);
826 }
827 assert(rowLog == 4 || rowLog == 5 || rowLog == 6);
828 assert(ZSTD_isAligned(hashTable + relRow, 64)); /* prefetched hash row always 64-byte aligned */
829 assert(ZSTD_isAligned(tagTable + relRow, (size_t)1 << rowLog)); /* prefetched tagRow sits on correct multiple of bytes (32,64,128) */
830 }
831
832 /* ZSTD_row_fillHashCache():
833 * Fill up the hash cache starting at idx, prefetching up to ZSTD_ROW_HASH_CACHE_SIZE entries,
834 * but not beyond iLimit.
835 */
836 FORCE_INLINE_TEMPLATE
837 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_row_fillHashCache(ZSTD_MatchState_t * ms,const BYTE * base,U32 const rowLog,U32 const mls,U32 idx,const BYTE * const iLimit)838 void ZSTD_row_fillHashCache(ZSTD_MatchState_t* ms, const BYTE* base,
839 U32 const rowLog, U32 const mls,
840 U32 idx, const BYTE* const iLimit)
841 {
842 U32 const* const hashTable = ms->hashTable;
843 BYTE const* const tagTable = ms->tagTable;
844 U32 const hashLog = ms->rowHashLog;
845 U32 const maxElemsToPrefetch = (base + idx) > iLimit ? 0 : (U32)(iLimit - (base + idx) + 1);
846 U32 const lim = idx + MIN(ZSTD_ROW_HASH_CACHE_SIZE, maxElemsToPrefetch);
847
848 for (; idx < lim; ++idx) {
849 U32 const hash = (U32)ZSTD_hashPtrSalted(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt);
850 U32 const row = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
851 ZSTD_row_prefetch(hashTable, tagTable, row, rowLog);
852 ms->hashCache[idx & ZSTD_ROW_HASH_CACHE_MASK] = hash;
853 }
854
855 DEBUGLOG(6, "ZSTD_row_fillHashCache(): [%u %u %u %u %u %u %u %u]", ms->hashCache[0], ms->hashCache[1],
856 ms->hashCache[2], ms->hashCache[3], ms->hashCache[4],
857 ms->hashCache[5], ms->hashCache[6], ms->hashCache[7]);
858 }
859
860 /* ZSTD_row_nextCachedHash():
861 * Returns the hash of base + idx, and replaces the hash in the hash cache with the byte at
862 * base + idx + ZSTD_ROW_HASH_CACHE_SIZE. Also prefetches the appropriate rows from hashTable and tagTable.
863 */
864 FORCE_INLINE_TEMPLATE
865 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_row_nextCachedHash(U32 * cache,U32 const * hashTable,BYTE const * tagTable,BYTE const * base,U32 idx,U32 const hashLog,U32 const rowLog,U32 const mls,U64 const hashSalt)866 U32 ZSTD_row_nextCachedHash(U32* cache, U32 const* hashTable,
867 BYTE const* tagTable, BYTE const* base,
868 U32 idx, U32 const hashLog,
869 U32 const rowLog, U32 const mls,
870 U64 const hashSalt)
871 {
872 U32 const newHash = (U32)ZSTD_hashPtrSalted(base+idx+ZSTD_ROW_HASH_CACHE_SIZE, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt);
873 U32 const row = (newHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
874 ZSTD_row_prefetch(hashTable, tagTable, row, rowLog);
875 { U32 const hash = cache[idx & ZSTD_ROW_HASH_CACHE_MASK];
876 cache[idx & ZSTD_ROW_HASH_CACHE_MASK] = newHash;
877 return hash;
878 }
879 }
880
881 /* ZSTD_row_update_internalImpl():
882 * Updates the hash table with positions starting from updateStartIdx until updateEndIdx.
883 */
884 FORCE_INLINE_TEMPLATE
885 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_row_update_internalImpl(ZSTD_MatchState_t * ms,U32 updateStartIdx,U32 const updateEndIdx,U32 const mls,U32 const rowLog,U32 const rowMask,U32 const useCache)886 void ZSTD_row_update_internalImpl(ZSTD_MatchState_t* ms,
887 U32 updateStartIdx, U32 const updateEndIdx,
888 U32 const mls, U32 const rowLog,
889 U32 const rowMask, U32 const useCache)
890 {
891 U32* const hashTable = ms->hashTable;
892 BYTE* const tagTable = ms->tagTable;
893 U32 const hashLog = ms->rowHashLog;
894 const BYTE* const base = ms->window.base;
895
896 DEBUGLOG(6, "ZSTD_row_update_internalImpl(): updateStartIdx=%u, updateEndIdx=%u", updateStartIdx, updateEndIdx);
897 for (; updateStartIdx < updateEndIdx; ++updateStartIdx) {
898 U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, updateStartIdx, hashLog, rowLog, mls, ms->hashSalt)
899 : (U32)ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt);
900 U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
901 U32* const row = hashTable + relRow;
902 BYTE* tagRow = tagTable + relRow;
903 U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask);
904
905 assert(hash == ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt));
906 tagRow[pos] = hash & ZSTD_ROW_HASH_TAG_MASK;
907 row[pos] = updateStartIdx;
908 }
909 }
910
911 /* ZSTD_row_update_internal():
912 * Inserts the byte at ip into the appropriate position in the hash table, and updates ms->nextToUpdate.
913 * Skips sections of long matches as is necessary.
914 */
915 FORCE_INLINE_TEMPLATE
916 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_row_update_internal(ZSTD_MatchState_t * ms,const BYTE * ip,U32 const mls,U32 const rowLog,U32 const rowMask,U32 const useCache)917 void ZSTD_row_update_internal(ZSTD_MatchState_t* ms, const BYTE* ip,
918 U32 const mls, U32 const rowLog,
919 U32 const rowMask, U32 const useCache)
920 {
921 U32 idx = ms->nextToUpdate;
922 const BYTE* const base = ms->window.base;
923 const U32 target = (U32)(ip - base);
924 const U32 kSkipThreshold = 384;
925 const U32 kMaxMatchStartPositionsToUpdate = 96;
926 const U32 kMaxMatchEndPositionsToUpdate = 32;
927
928 if (useCache) {
929 /* Only skip positions when using hash cache, i.e.
930 * if we are loading a dict, don't skip anything.
931 * If we decide to skip, then we only update a set number
932 * of positions at the beginning and end of the match.
933 */
934 if (UNLIKELY(target - idx > kSkipThreshold)) {
935 U32 const bound = idx + kMaxMatchStartPositionsToUpdate;
936 ZSTD_row_update_internalImpl(ms, idx, bound, mls, rowLog, rowMask, useCache);
937 idx = target - kMaxMatchEndPositionsToUpdate;
938 ZSTD_row_fillHashCache(ms, base, rowLog, mls, idx, ip+1);
939 }
940 }
941 assert(target >= idx);
942 ZSTD_row_update_internalImpl(ms, idx, target, mls, rowLog, rowMask, useCache);
943 ms->nextToUpdate = target;
944 }
945
946 /* ZSTD_row_update():
947 * External wrapper for ZSTD_row_update_internal(). Used for filling the hashtable during dictionary
948 * processing.
949 */
ZSTD_row_update(ZSTD_MatchState_t * const ms,const BYTE * ip)950 void ZSTD_row_update(ZSTD_MatchState_t* const ms, const BYTE* ip) {
951 const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6);
952 const U32 rowMask = (1u << rowLog) - 1;
953 const U32 mls = MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */);
954
955 DEBUGLOG(5, "ZSTD_row_update(), rowLog=%u", rowLog);
956 ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 0 /* don't use cache */);
957 }
958
959 /* Returns the mask width of bits group of which will be set to 1. Given not all
960 * architectures have easy movemask instruction, this helps to iterate over
961 * groups of bits easier and faster.
962 */
963 FORCE_INLINE_TEMPLATE U32
ZSTD_row_matchMaskGroupWidth(const U32 rowEntries)964 ZSTD_row_matchMaskGroupWidth(const U32 rowEntries)
965 {
966 assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64);
967 assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES);
968 (void)rowEntries;
969 #if defined(ZSTD_ARCH_ARM_NEON)
970 /* NEON path only works for little endian */
971 if (!MEM_isLittleEndian()) {
972 return 1;
973 }
974 if (rowEntries == 16) {
975 return 4;
976 }
977 if (rowEntries == 32) {
978 return 2;
979 }
980 if (rowEntries == 64) {
981 return 1;
982 }
983 #endif
984 return 1;
985 }
986
987 #if defined(ZSTD_ARCH_X86_SSE2)
988 FORCE_INLINE_TEMPLATE ZSTD_VecMask
ZSTD_row_getSSEMask(int nbChunks,const BYTE * const src,const BYTE tag,const U32 head)989 ZSTD_row_getSSEMask(int nbChunks, const BYTE* const src, const BYTE tag, const U32 head)
990 {
991 const __m128i comparisonMask = _mm_set1_epi8((char)tag);
992 int matches[4] = {0};
993 int i;
994 assert(nbChunks == 1 || nbChunks == 2 || nbChunks == 4);
995 for (i=0; i<nbChunks; i++) {
996 const __m128i chunk = _mm_loadu_si128((const __m128i*)(const void*)(src + 16*i));
997 const __m128i equalMask = _mm_cmpeq_epi8(chunk, comparisonMask);
998 matches[i] = _mm_movemask_epi8(equalMask);
999 }
1000 if (nbChunks == 1) return ZSTD_rotateRight_U16((U16)matches[0], head);
1001 if (nbChunks == 2) return ZSTD_rotateRight_U32((U32)matches[1] << 16 | (U32)matches[0], head);
1002 assert(nbChunks == 4);
1003 return ZSTD_rotateRight_U64((U64)matches[3] << 48 | (U64)matches[2] << 32 | (U64)matches[1] << 16 | (U64)matches[0], head);
1004 }
1005 #endif
1006
1007 #if defined(ZSTD_ARCH_ARM_NEON)
1008 FORCE_INLINE_TEMPLATE ZSTD_VecMask
ZSTD_row_getNEONMask(const U32 rowEntries,const BYTE * const src,const BYTE tag,const U32 headGrouped)1009 ZSTD_row_getNEONMask(const U32 rowEntries, const BYTE* const src, const BYTE tag, const U32 headGrouped)
1010 {
1011 assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64);
1012 if (rowEntries == 16) {
1013 /* vshrn_n_u16 shifts by 4 every u16 and narrows to 8 lower bits.
1014 * After that groups of 4 bits represent the equalMask. We lower
1015 * all bits except the highest in these groups by doing AND with
1016 * 0x88 = 0b10001000.
1017 */
1018 const uint8x16_t chunk = vld1q_u8(src);
1019 const uint16x8_t equalMask = vreinterpretq_u16_u8(vceqq_u8(chunk, vdupq_n_u8(tag)));
1020 const uint8x8_t res = vshrn_n_u16(equalMask, 4);
1021 const U64 matches = vget_lane_u64(vreinterpret_u64_u8(res), 0);
1022 return ZSTD_rotateRight_U64(matches, headGrouped) & 0x8888888888888888ull;
1023 } else if (rowEntries == 32) {
1024 /* Same idea as with rowEntries == 16 but doing AND with
1025 * 0x55 = 0b01010101.
1026 */
1027 const uint16x8x2_t chunk = vld2q_u16((const uint16_t*)(const void*)src);
1028 const uint8x16_t chunk0 = vreinterpretq_u8_u16(chunk.val[0]);
1029 const uint8x16_t chunk1 = vreinterpretq_u8_u16(chunk.val[1]);
1030 const uint8x16_t dup = vdupq_n_u8(tag);
1031 const uint8x8_t t0 = vshrn_n_u16(vreinterpretq_u16_u8(vceqq_u8(chunk0, dup)), 6);
1032 const uint8x8_t t1 = vshrn_n_u16(vreinterpretq_u16_u8(vceqq_u8(chunk1, dup)), 6);
1033 const uint8x8_t res = vsli_n_u8(t0, t1, 4);
1034 const U64 matches = vget_lane_u64(vreinterpret_u64_u8(res), 0) ;
1035 return ZSTD_rotateRight_U64(matches, headGrouped) & 0x5555555555555555ull;
1036 } else { /* rowEntries == 64 */
1037 const uint8x16x4_t chunk = vld4q_u8(src);
1038 const uint8x16_t dup = vdupq_n_u8(tag);
1039 const uint8x16_t cmp0 = vceqq_u8(chunk.val[0], dup);
1040 const uint8x16_t cmp1 = vceqq_u8(chunk.val[1], dup);
1041 const uint8x16_t cmp2 = vceqq_u8(chunk.val[2], dup);
1042 const uint8x16_t cmp3 = vceqq_u8(chunk.val[3], dup);
1043
1044 const uint8x16_t t0 = vsriq_n_u8(cmp1, cmp0, 1);
1045 const uint8x16_t t1 = vsriq_n_u8(cmp3, cmp2, 1);
1046 const uint8x16_t t2 = vsriq_n_u8(t1, t0, 2);
1047 const uint8x16_t t3 = vsriq_n_u8(t2, t2, 4);
1048 const uint8x8_t t4 = vshrn_n_u16(vreinterpretq_u16_u8(t3), 4);
1049 const U64 matches = vget_lane_u64(vreinterpret_u64_u8(t4), 0);
1050 return ZSTD_rotateRight_U64(matches, headGrouped);
1051 }
1052 }
1053 #endif
1054
1055 /* Returns a ZSTD_VecMask (U64) that has the nth group (determined by
1056 * ZSTD_row_matchMaskGroupWidth) of bits set to 1 if the newly-computed "tag"
1057 * matches the hash at the nth position in a row of the tagTable.
1058 * Each row is a circular buffer beginning at the value of "headGrouped". So we
1059 * must rotate the "matches" bitfield to match up with the actual layout of the
1060 * entries within the hashTable */
1061 FORCE_INLINE_TEMPLATE ZSTD_VecMask
ZSTD_row_getMatchMask(const BYTE * const tagRow,const BYTE tag,const U32 headGrouped,const U32 rowEntries)1062 ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 headGrouped, const U32 rowEntries)
1063 {
1064 const BYTE* const src = tagRow;
1065 assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64);
1066 assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES);
1067 assert(ZSTD_row_matchMaskGroupWidth(rowEntries) * rowEntries <= sizeof(ZSTD_VecMask) * 8);
1068
1069 #if defined(ZSTD_ARCH_X86_SSE2)
1070
1071 return ZSTD_row_getSSEMask(rowEntries / 16, src, tag, headGrouped);
1072
1073 #else /* SW or NEON-LE */
1074
1075 # if defined(ZSTD_ARCH_ARM_NEON)
1076 /* This NEON path only works for little endian - otherwise use SWAR below */
1077 if (MEM_isLittleEndian()) {
1078 return ZSTD_row_getNEONMask(rowEntries, src, tag, headGrouped);
1079 }
1080 # endif /* ZSTD_ARCH_ARM_NEON */
1081 /* SWAR */
1082 { const int chunkSize = sizeof(size_t);
1083 const size_t shiftAmount = ((chunkSize * 8) - chunkSize);
1084 const size_t xFF = ~((size_t)0);
1085 const size_t x01 = xFF / 0xFF;
1086 const size_t x80 = x01 << 7;
1087 const size_t splatChar = tag * x01;
1088 ZSTD_VecMask matches = 0;
1089 int i = rowEntries - chunkSize;
1090 assert((sizeof(size_t) == 4) || (sizeof(size_t) == 8));
1091 if (MEM_isLittleEndian()) { /* runtime check so have two loops */
1092 const size_t extractMagic = (xFF / 0x7F) >> chunkSize;
1093 do {
1094 size_t chunk = MEM_readST(&src[i]);
1095 chunk ^= splatChar;
1096 chunk = (((chunk | x80) - x01) | chunk) & x80;
1097 matches <<= chunkSize;
1098 matches |= (chunk * extractMagic) >> shiftAmount;
1099 i -= chunkSize;
1100 } while (i >= 0);
1101 } else { /* big endian: reverse bits during extraction */
1102 const size_t msb = xFF ^ (xFF >> 1);
1103 const size_t extractMagic = (msb / 0x1FF) | msb;
1104 do {
1105 size_t chunk = MEM_readST(&src[i]);
1106 chunk ^= splatChar;
1107 chunk = (((chunk | x80) - x01) | chunk) & x80;
1108 matches <<= chunkSize;
1109 matches |= ((chunk >> 7) * extractMagic) >> shiftAmount;
1110 i -= chunkSize;
1111 } while (i >= 0);
1112 }
1113 matches = ~matches;
1114 if (rowEntries == 16) {
1115 return ZSTD_rotateRight_U16((U16)matches, headGrouped);
1116 } else if (rowEntries == 32) {
1117 return ZSTD_rotateRight_U32((U32)matches, headGrouped);
1118 } else {
1119 return ZSTD_rotateRight_U64((U64)matches, headGrouped);
1120 }
1121 }
1122 #endif
1123 }
1124
1125 /* The high-level approach of the SIMD row based match finder is as follows:
1126 * - Figure out where to insert the new entry:
1127 * - Generate a hash for current input position and split it into a one byte of tag and `rowHashLog` bits of index.
1128 * - The hash is salted by a value that changes on every context reset, so when the same table is used
1129 * we will avoid collisions that would otherwise slow us down by introducing phantom matches.
1130 * - The hashTable is effectively split into groups or "rows" of 15 or 31 entries of U32, and the index determines
1131 * which row to insert into.
1132 * - Determine the correct position within the row to insert the entry into. Each row of 15 or 31 can
1133 * be considered as a circular buffer with a "head" index that resides in the tagTable (overall 16 or 32 bytes
1134 * per row).
1135 * - Use SIMD to efficiently compare the tags in the tagTable to the 1-byte tag calculated for the position and
1136 * generate a bitfield that we can cycle through to check the collisions in the hash table.
1137 * - Pick the longest match.
1138 * - Insert the tag into the equivalent row and position in the tagTable.
1139 */
1140 FORCE_INLINE_TEMPLATE
1141 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_RowFindBestMatch(ZSTD_MatchState_t * ms,const BYTE * const ip,const BYTE * const iLimit,size_t * offsetPtr,const U32 mls,const ZSTD_dictMode_e dictMode,const U32 rowLog)1142 size_t ZSTD_RowFindBestMatch(
1143 ZSTD_MatchState_t* ms,
1144 const BYTE* const ip, const BYTE* const iLimit,
1145 size_t* offsetPtr,
1146 const U32 mls, const ZSTD_dictMode_e dictMode,
1147 const U32 rowLog)
1148 {
1149 U32* const hashTable = ms->hashTable;
1150 BYTE* const tagTable = ms->tagTable;
1151 U32* const hashCache = ms->hashCache;
1152 const U32 hashLog = ms->rowHashLog;
1153 const ZSTD_compressionParameters* const cParams = &ms->cParams;
1154 const BYTE* const base = ms->window.base;
1155 const BYTE* const dictBase = ms->window.dictBase;
1156 const U32 dictLimit = ms->window.dictLimit;
1157 const BYTE* const prefixStart = base + dictLimit;
1158 const BYTE* const dictEnd = dictBase + dictLimit;
1159 const U32 curr = (U32)(ip-base);
1160 const U32 maxDistance = 1U << cParams->windowLog;
1161 const U32 lowestValid = ms->window.lowLimit;
1162 const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid;
1163 const U32 isDictionary = (ms->loadedDictEnd != 0);
1164 const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance;
1165 const U32 rowEntries = (1U << rowLog);
1166 const U32 rowMask = rowEntries - 1;
1167 const U32 cappedSearchLog = MIN(cParams->searchLog, rowLog); /* nb of searches is capped at nb entries per row */
1168 const U32 groupWidth = ZSTD_row_matchMaskGroupWidth(rowEntries);
1169 const U64 hashSalt = ms->hashSalt;
1170 U32 nbAttempts = 1U << cappedSearchLog;
1171 size_t ml=4-1;
1172 U32 hash;
1173
1174 /* DMS/DDS variables that may be referenced laster */
1175 const ZSTD_MatchState_t* const dms = ms->dictMatchState;
1176
1177 /* Initialize the following variables to satisfy static analyzer */
1178 size_t ddsIdx = 0;
1179 U32 ddsExtraAttempts = 0; /* cctx hash tables are limited in searches, but allow extra searches into DDS */
1180 U32 dmsTag = 0;
1181 U32* dmsRow = NULL;
1182 BYTE* dmsTagRow = NULL;
1183
1184 if (dictMode == ZSTD_dedicatedDictSearch) {
1185 const U32 ddsHashLog = dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG;
1186 { /* Prefetch DDS hashtable entry */
1187 ddsIdx = ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG;
1188 PREFETCH_L1(&dms->hashTable[ddsIdx]);
1189 }
1190 ddsExtraAttempts = cParams->searchLog > rowLog ? 1U << (cParams->searchLog - rowLog) : 0;
1191 }
1192
1193 if (dictMode == ZSTD_dictMatchState) {
1194 /* Prefetch DMS rows */
1195 U32* const dmsHashTable = dms->hashTable;
1196 BYTE* const dmsTagTable = dms->tagTable;
1197 U32 const dmsHash = (U32)ZSTD_hashPtr(ip, dms->rowHashLog + ZSTD_ROW_HASH_TAG_BITS, mls);
1198 U32 const dmsRelRow = (dmsHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
1199 dmsTag = dmsHash & ZSTD_ROW_HASH_TAG_MASK;
1200 dmsTagRow = (BYTE*)(dmsTagTable + dmsRelRow);
1201 dmsRow = dmsHashTable + dmsRelRow;
1202 ZSTD_row_prefetch(dmsHashTable, dmsTagTable, dmsRelRow, rowLog);
1203 }
1204
1205 /* Update the hashTable and tagTable up to (but not including) ip */
1206 if (!ms->lazySkipping) {
1207 ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 1 /* useCache */);
1208 hash = ZSTD_row_nextCachedHash(hashCache, hashTable, tagTable, base, curr, hashLog, rowLog, mls, hashSalt);
1209 } else {
1210 /* Stop inserting every position when in the lazy skipping mode.
1211 * The hash cache is also not kept up to date in this mode.
1212 */
1213 hash = (U32)ZSTD_hashPtrSalted(ip, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt);
1214 ms->nextToUpdate = curr;
1215 }
1216 ms->hashSaltEntropy += hash; /* collect salt entropy */
1217
1218 { /* Get the hash for ip, compute the appropriate row */
1219 U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
1220 U32 const tag = hash & ZSTD_ROW_HASH_TAG_MASK;
1221 U32* const row = hashTable + relRow;
1222 BYTE* tagRow = (BYTE*)(tagTable + relRow);
1223 U32 const headGrouped = (*tagRow & rowMask) * groupWidth;
1224 U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES];
1225 size_t numMatches = 0;
1226 size_t currMatch = 0;
1227 ZSTD_VecMask matches = ZSTD_row_getMatchMask(tagRow, (BYTE)tag, headGrouped, rowEntries);
1228
1229 /* Cycle through the matches and prefetch */
1230 for (; (matches > 0) && (nbAttempts > 0); matches &= (matches - 1)) {
1231 U32 const matchPos = ((headGrouped + ZSTD_VecMask_next(matches)) / groupWidth) & rowMask;
1232 U32 const matchIndex = row[matchPos];
1233 if(matchPos == 0) continue;
1234 assert(numMatches < rowEntries);
1235 if (matchIndex < lowLimit)
1236 break;
1237 if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) {
1238 PREFETCH_L1(base + matchIndex);
1239 } else {
1240 PREFETCH_L1(dictBase + matchIndex);
1241 }
1242 matchBuffer[numMatches++] = matchIndex;
1243 --nbAttempts;
1244 }
1245
1246 /* Speed opt: insert current byte into hashtable too. This allows us to avoid one iteration of the loop
1247 in ZSTD_row_update_internal() at the next search. */
1248 {
1249 U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask);
1250 tagRow[pos] = (BYTE)tag;
1251 row[pos] = ms->nextToUpdate++;
1252 }
1253
1254 /* Return the longest match */
1255 for (; currMatch < numMatches; ++currMatch) {
1256 U32 const matchIndex = matchBuffer[currMatch];
1257 size_t currentMl=0;
1258 assert(matchIndex < curr);
1259 assert(matchIndex >= lowLimit);
1260
1261 if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) {
1262 const BYTE* const match = base + matchIndex;
1263 assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */
1264 /* read 4B starting from (match + ml + 1 - sizeof(U32)) */
1265 if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */
1266 currentMl = ZSTD_count(ip, match, iLimit);
1267 } else {
1268 const BYTE* const match = dictBase + matchIndex;
1269 assert(match+4 <= dictEnd);
1270 if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
1271 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4;
1272 }
1273
1274 /* Save best solution */
1275 if (currentMl > ml) {
1276 ml = currentMl;
1277 *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex);
1278 if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
1279 }
1280 }
1281 }
1282
1283 assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
1284 if (dictMode == ZSTD_dedicatedDictSearch) {
1285 ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts + ddsExtraAttempts, dms,
1286 ip, iLimit, prefixStart, curr, dictLimit, ddsIdx);
1287 } else if (dictMode == ZSTD_dictMatchState) {
1288 /* TODO: Measure and potentially add prefetching to DMS */
1289 const U32 dmsLowestIndex = dms->window.dictLimit;
1290 const BYTE* const dmsBase = dms->window.base;
1291 const BYTE* const dmsEnd = dms->window.nextSrc;
1292 const U32 dmsSize = (U32)(dmsEnd - dmsBase);
1293 const U32 dmsIndexDelta = dictLimit - dmsSize;
1294
1295 { U32 const headGrouped = (*dmsTagRow & rowMask) * groupWidth;
1296 U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES];
1297 size_t numMatches = 0;
1298 size_t currMatch = 0;
1299 ZSTD_VecMask matches = ZSTD_row_getMatchMask(dmsTagRow, (BYTE)dmsTag, headGrouped, rowEntries);
1300
1301 for (; (matches > 0) && (nbAttempts > 0); matches &= (matches - 1)) {
1302 U32 const matchPos = ((headGrouped + ZSTD_VecMask_next(matches)) / groupWidth) & rowMask;
1303 U32 const matchIndex = dmsRow[matchPos];
1304 if(matchPos == 0) continue;
1305 if (matchIndex < dmsLowestIndex)
1306 break;
1307 PREFETCH_L1(dmsBase + matchIndex);
1308 matchBuffer[numMatches++] = matchIndex;
1309 --nbAttempts;
1310 }
1311
1312 /* Return the longest match */
1313 for (; currMatch < numMatches; ++currMatch) {
1314 U32 const matchIndex = matchBuffer[currMatch];
1315 size_t currentMl=0;
1316 assert(matchIndex >= dmsLowestIndex);
1317 assert(matchIndex < curr);
1318
1319 { const BYTE* const match = dmsBase + matchIndex;
1320 assert(match+4 <= dmsEnd);
1321 if (MEM_read32(match) == MEM_read32(ip))
1322 currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4;
1323 }
1324
1325 if (currentMl > ml) {
1326 ml = currentMl;
1327 assert(curr > matchIndex + dmsIndexDelta);
1328 *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta));
1329 if (ip+currentMl == iLimit) break;
1330 }
1331 }
1332 }
1333 }
1334 return ml;
1335 }
1336
1337
1338 /*
1339 * Generate search functions templated on (dictMode, mls, rowLog).
1340 * These functions are outlined for code size & compilation time.
1341 * ZSTD_searchMax() dispatches to the correct implementation function.
1342 *
1343 * TODO: The start of the search function involves loading and calculating a
1344 * bunch of constants from the ZSTD_MatchState_t. These computations could be
1345 * done in an initialization function, and saved somewhere in the match state.
1346 * Then we could pass a pointer to the saved state instead of the match state,
1347 * and avoid duplicate computations.
1348 *
1349 * TODO: Move the match re-winding into searchMax. This improves compression
1350 * ratio, and unlocks further simplifications with the next TODO.
1351 *
1352 * TODO: Try moving the repcode search into searchMax. After the re-winding
1353 * and repcode search are in searchMax, there is no more logic in the match
1354 * finder loop that requires knowledge about the dictMode. So we should be
1355 * able to avoid force inlining it, and we can join the extDict loop with
1356 * the single segment loop. It should go in searchMax instead of its own
1357 * function to avoid having multiple virtual function calls per search.
1358 */
1359
1360 #define ZSTD_BT_SEARCH_FN(dictMode, mls) ZSTD_BtFindBestMatch_##dictMode##_##mls
1361 #define ZSTD_HC_SEARCH_FN(dictMode, mls) ZSTD_HcFindBestMatch_##dictMode##_##mls
1362 #define ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog) ZSTD_RowFindBestMatch_##dictMode##_##mls##_##rowLog
1363
1364 #define ZSTD_SEARCH_FN_ATTRS FORCE_NOINLINE
1365
1366 #define GEN_ZSTD_BT_SEARCH_FN(dictMode, mls) \
1367 ZSTD_SEARCH_FN_ATTRS size_t ZSTD_BT_SEARCH_FN(dictMode, mls)( \
1368 ZSTD_MatchState_t* ms, \
1369 const BYTE* ip, const BYTE* const iLimit, \
1370 size_t* offBasePtr) \
1371 { \
1372 assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \
1373 return ZSTD_BtFindBestMatch(ms, ip, iLimit, offBasePtr, mls, ZSTD_##dictMode); \
1374 } \
1375
1376 #define GEN_ZSTD_HC_SEARCH_FN(dictMode, mls) \
1377 ZSTD_SEARCH_FN_ATTRS size_t ZSTD_HC_SEARCH_FN(dictMode, mls)( \
1378 ZSTD_MatchState_t* ms, \
1379 const BYTE* ip, const BYTE* const iLimit, \
1380 size_t* offsetPtr) \
1381 { \
1382 assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \
1383 return ZSTD_HcFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode); \
1384 } \
1385
1386 #define GEN_ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog) \
1387 ZSTD_SEARCH_FN_ATTRS size_t ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog)( \
1388 ZSTD_MatchState_t* ms, \
1389 const BYTE* ip, const BYTE* const iLimit, \
1390 size_t* offsetPtr) \
1391 { \
1392 assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \
1393 assert(MAX(4, MIN(6, ms->cParams.searchLog)) == rowLog); \
1394 return ZSTD_RowFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode, rowLog); \
1395 } \
1396
1397 #define ZSTD_FOR_EACH_ROWLOG(X, dictMode, mls) \
1398 X(dictMode, mls, 4) \
1399 X(dictMode, mls, 5) \
1400 X(dictMode, mls, 6)
1401
1402 #define ZSTD_FOR_EACH_MLS_ROWLOG(X, dictMode) \
1403 ZSTD_FOR_EACH_ROWLOG(X, dictMode, 4) \
1404 ZSTD_FOR_EACH_ROWLOG(X, dictMode, 5) \
1405 ZSTD_FOR_EACH_ROWLOG(X, dictMode, 6)
1406
1407 #define ZSTD_FOR_EACH_MLS(X, dictMode) \
1408 X(dictMode, 4) \
1409 X(dictMode, 5) \
1410 X(dictMode, 6)
1411
1412 #define ZSTD_FOR_EACH_DICT_MODE(X, ...) \
1413 X(__VA_ARGS__, noDict) \
1414 X(__VA_ARGS__, extDict) \
1415 X(__VA_ARGS__, dictMatchState) \
1416 X(__VA_ARGS__, dedicatedDictSearch)
1417
1418 /* Generate row search fns for each combination of (dictMode, mls, rowLog) */
1419 ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS_ROWLOG, GEN_ZSTD_ROW_SEARCH_FN)
1420 /* Generate binary Tree search fns for each combination of (dictMode, mls) */
1421 ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_BT_SEARCH_FN)
1422 /* Generate hash chain search fns for each combination of (dictMode, mls) */
1423 ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_HC_SEARCH_FN)
1424
1425 typedef enum { search_hashChain=0, search_binaryTree=1, search_rowHash=2 } searchMethod_e;
1426
1427 #define GEN_ZSTD_CALL_BT_SEARCH_FN(dictMode, mls) \
1428 case mls: \
1429 return ZSTD_BT_SEARCH_FN(dictMode, mls)(ms, ip, iend, offsetPtr);
1430 #define GEN_ZSTD_CALL_HC_SEARCH_FN(dictMode, mls) \
1431 case mls: \
1432 return ZSTD_HC_SEARCH_FN(dictMode, mls)(ms, ip, iend, offsetPtr);
1433 #define GEN_ZSTD_CALL_ROW_SEARCH_FN(dictMode, mls, rowLog) \
1434 case rowLog: \
1435 return ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog)(ms, ip, iend, offsetPtr);
1436
1437 #define ZSTD_SWITCH_MLS(X, dictMode) \
1438 switch (mls) { \
1439 ZSTD_FOR_EACH_MLS(X, dictMode) \
1440 }
1441
1442 #define ZSTD_SWITCH_ROWLOG(dictMode, mls) \
1443 case mls: \
1444 switch (rowLog) { \
1445 ZSTD_FOR_EACH_ROWLOG(GEN_ZSTD_CALL_ROW_SEARCH_FN, dictMode, mls) \
1446 } \
1447 ZSTD_UNREACHABLE; \
1448 break;
1449
1450 #define ZSTD_SWITCH_SEARCH_METHOD(dictMode) \
1451 switch (searchMethod) { \
1452 case search_hashChain: \
1453 ZSTD_SWITCH_MLS(GEN_ZSTD_CALL_HC_SEARCH_FN, dictMode) \
1454 break; \
1455 case search_binaryTree: \
1456 ZSTD_SWITCH_MLS(GEN_ZSTD_CALL_BT_SEARCH_FN, dictMode) \
1457 break; \
1458 case search_rowHash: \
1459 ZSTD_SWITCH_MLS(ZSTD_SWITCH_ROWLOG, dictMode) \
1460 break; \
1461 } \
1462 ZSTD_UNREACHABLE;
1463
1464 /*
1465 * Searches for the longest match at @p ip.
1466 * Dispatches to the correct implementation function based on the
1467 * (searchMethod, dictMode, mls, rowLog). We use switch statements
1468 * here instead of using an indirect function call through a function
1469 * pointer because after Spectre and Meltdown mitigations, indirect
1470 * function calls can be very costly, especially in the kernel.
1471 *
1472 * NOTE: dictMode and searchMethod should be templated, so those switch
1473 * statements should be optimized out. Only the mls & rowLog switches
1474 * should be left.
1475 *
1476 * @param ms The match state.
1477 * @param ip The position to search at.
1478 * @param iend The end of the input data.
1479 * @param[out] offsetPtr Stores the match offset into this pointer.
1480 * @param mls The minimum search length, in the range [4, 6].
1481 * @param rowLog The row log (if applicable), in the range [4, 6].
1482 * @param searchMethod The search method to use (templated).
1483 * @param dictMode The dictMode (templated).
1484 *
1485 * @returns The length of the longest match found, or < mls if no match is found.
1486 * If a match is found its offset is stored in @p offsetPtr.
1487 */
ZSTD_searchMax(ZSTD_MatchState_t * ms,const BYTE * ip,const BYTE * iend,size_t * offsetPtr,U32 const mls,U32 const rowLog,searchMethod_e const searchMethod,ZSTD_dictMode_e const dictMode)1488 FORCE_INLINE_TEMPLATE size_t ZSTD_searchMax(
1489 ZSTD_MatchState_t* ms,
1490 const BYTE* ip,
1491 const BYTE* iend,
1492 size_t* offsetPtr,
1493 U32 const mls,
1494 U32 const rowLog,
1495 searchMethod_e const searchMethod,
1496 ZSTD_dictMode_e const dictMode)
1497 {
1498 if (dictMode == ZSTD_noDict) {
1499 ZSTD_SWITCH_SEARCH_METHOD(noDict)
1500 } else if (dictMode == ZSTD_extDict) {
1501 ZSTD_SWITCH_SEARCH_METHOD(extDict)
1502 } else if (dictMode == ZSTD_dictMatchState) {
1503 ZSTD_SWITCH_SEARCH_METHOD(dictMatchState)
1504 } else if (dictMode == ZSTD_dedicatedDictSearch) {
1505 ZSTD_SWITCH_SEARCH_METHOD(dedicatedDictSearch)
1506 }
1507 ZSTD_UNREACHABLE;
1508 return 0;
1509 }
1510
1511 /* *******************************
1512 * Common parser - lazy strategy
1513 *********************************/
1514
1515 FORCE_INLINE_TEMPLATE
1516 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_compressBlock_lazy_generic(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],const void * src,size_t srcSize,const searchMethod_e searchMethod,const U32 depth,ZSTD_dictMode_e const dictMode)1517 size_t ZSTD_compressBlock_lazy_generic(
1518 ZSTD_MatchState_t* ms, SeqStore_t* seqStore,
1519 U32 rep[ZSTD_REP_NUM],
1520 const void* src, size_t srcSize,
1521 const searchMethod_e searchMethod, const U32 depth,
1522 ZSTD_dictMode_e const dictMode)
1523 {
1524 const BYTE* const istart = (const BYTE*)src;
1525 const BYTE* ip = istart;
1526 const BYTE* anchor = istart;
1527 const BYTE* const iend = istart + srcSize;
1528 const BYTE* const ilimit = (searchMethod == search_rowHash) ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8;
1529 const BYTE* const base = ms->window.base;
1530 const U32 prefixLowestIndex = ms->window.dictLimit;
1531 const BYTE* const prefixLowest = base + prefixLowestIndex;
1532 const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6);
1533 const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6);
1534
1535 U32 offset_1 = rep[0], offset_2 = rep[1];
1536 U32 offsetSaved1 = 0, offsetSaved2 = 0;
1537
1538 const int isDMS = dictMode == ZSTD_dictMatchState;
1539 const int isDDS = dictMode == ZSTD_dedicatedDictSearch;
1540 const int isDxS = isDMS || isDDS;
1541 const ZSTD_MatchState_t* const dms = ms->dictMatchState;
1542 const U32 dictLowestIndex = isDxS ? dms->window.dictLimit : 0;
1543 const BYTE* const dictBase = isDxS ? dms->window.base : NULL;
1544 const BYTE* const dictLowest = isDxS ? dictBase + dictLowestIndex : NULL;
1545 const BYTE* const dictEnd = isDxS ? dms->window.nextSrc : NULL;
1546 const U32 dictIndexDelta = isDxS ?
1547 prefixLowestIndex - (U32)(dictEnd - dictBase) :
1548 0;
1549 const U32 dictAndPrefixLength = (U32)((ip - prefixLowest) + (dictEnd - dictLowest));
1550
1551 DEBUGLOG(5, "ZSTD_compressBlock_lazy_generic (dictMode=%u) (searchFunc=%u)", (U32)dictMode, (U32)searchMethod);
1552 ip += (dictAndPrefixLength == 0);
1553 if (dictMode == ZSTD_noDict) {
1554 U32 const curr = (U32)(ip - base);
1555 U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, ms->cParams.windowLog);
1556 U32 const maxRep = curr - windowLow;
1557 if (offset_2 > maxRep) offsetSaved2 = offset_2, offset_2 = 0;
1558 if (offset_1 > maxRep) offsetSaved1 = offset_1, offset_1 = 0;
1559 }
1560 if (isDxS) {
1561 /* dictMatchState repCode checks don't currently handle repCode == 0
1562 * disabling. */
1563 assert(offset_1 <= dictAndPrefixLength);
1564 assert(offset_2 <= dictAndPrefixLength);
1565 }
1566
1567 /* Reset the lazy skipping state */
1568 ms->lazySkipping = 0;
1569
1570 if (searchMethod == search_rowHash) {
1571 ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit);
1572 }
1573
1574 /* Match Loop */
1575 #if defined(__x86_64__)
1576 /* I've measured random a 5% speed loss on levels 5 & 6 (greedy) when the
1577 * code alignment is perturbed. To fix the instability align the loop on 32-bytes.
1578 */
1579 __asm__(".p2align 5");
1580 #endif
1581 while (ip < ilimit) {
1582 size_t matchLength=0;
1583 size_t offBase = REPCODE1_TO_OFFBASE;
1584 const BYTE* start=ip+1;
1585 DEBUGLOG(7, "search baseline (depth 0)");
1586
1587 /* check repCode */
1588 if (isDxS) {
1589 const U32 repIndex = (U32)(ip - base) + 1 - offset_1;
1590 const BYTE* repMatch = ((dictMode == ZSTD_dictMatchState || dictMode == ZSTD_dedicatedDictSearch)
1591 && repIndex < prefixLowestIndex) ?
1592 dictBase + (repIndex - dictIndexDelta) :
1593 base + repIndex;
1594 if ((ZSTD_index_overlap_check(prefixLowestIndex, repIndex))
1595 && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
1596 const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
1597 matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4;
1598 if (depth==0) goto _storeSequence;
1599 }
1600 }
1601 if ( dictMode == ZSTD_noDict
1602 && ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) {
1603 matchLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;
1604 if (depth==0) goto _storeSequence;
1605 }
1606
1607 /* first search (depth 0) */
1608 { size_t offbaseFound = 999999999;
1609 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offbaseFound, mls, rowLog, searchMethod, dictMode);
1610 if (ml2 > matchLength)
1611 matchLength = ml2, start = ip, offBase = offbaseFound;
1612 }
1613
1614 if (matchLength < 4) {
1615 size_t const step = ((size_t)(ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */;
1616 ip += step;
1617 /* Enter the lazy skipping mode once we are skipping more than 8 bytes at a time.
1618 * In this mode we stop inserting every position into our tables, and only insert
1619 * positions that we search, which is one in step positions.
1620 * The exact cutoff is flexible, I've just chosen a number that is reasonably high,
1621 * so we minimize the compression ratio loss in "normal" scenarios. This mode gets
1622 * triggered once we've gone 2KB without finding any matches.
1623 */
1624 ms->lazySkipping = step > kLazySkippingStep;
1625 continue;
1626 }
1627
1628 /* let's try to find a better solution */
1629 if (depth>=1)
1630 while (ip<ilimit) {
1631 DEBUGLOG(7, "search depth 1");
1632 ip ++;
1633 if ( (dictMode == ZSTD_noDict)
1634 && (offBase) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
1635 size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4;
1636 int const gain2 = (int)(mlRep * 3);
1637 int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1);
1638 if ((mlRep >= 4) && (gain2 > gain1))
1639 matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip;
1640 }
1641 if (isDxS) {
1642 const U32 repIndex = (U32)(ip - base) - offset_1;
1643 const BYTE* repMatch = repIndex < prefixLowestIndex ?
1644 dictBase + (repIndex - dictIndexDelta) :
1645 base + repIndex;
1646 if ((ZSTD_index_overlap_check(prefixLowestIndex, repIndex))
1647 && (MEM_read32(repMatch) == MEM_read32(ip)) ) {
1648 const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
1649 size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4;
1650 int const gain2 = (int)(mlRep * 3);
1651 int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1);
1652 if ((mlRep >= 4) && (gain2 > gain1))
1653 matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip;
1654 }
1655 }
1656 { size_t ofbCandidate=999999999;
1657 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, dictMode);
1658 int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */
1659 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 4);
1660 if ((ml2 >= 4) && (gain2 > gain1)) {
1661 matchLength = ml2, offBase = ofbCandidate, start = ip;
1662 continue; /* search a better one */
1663 } }
1664
1665 /* let's find an even better one */
1666 if ((depth==2) && (ip<ilimit)) {
1667 DEBUGLOG(7, "search depth 2");
1668 ip ++;
1669 if ( (dictMode == ZSTD_noDict)
1670 && (offBase) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
1671 size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4;
1672 int const gain2 = (int)(mlRep * 4);
1673 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1);
1674 if ((mlRep >= 4) && (gain2 > gain1))
1675 matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip;
1676 }
1677 if (isDxS) {
1678 const U32 repIndex = (U32)(ip - base) - offset_1;
1679 const BYTE* repMatch = repIndex < prefixLowestIndex ?
1680 dictBase + (repIndex - dictIndexDelta) :
1681 base + repIndex;
1682 if ((ZSTD_index_overlap_check(prefixLowestIndex, repIndex))
1683 && (MEM_read32(repMatch) == MEM_read32(ip)) ) {
1684 const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
1685 size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4;
1686 int const gain2 = (int)(mlRep * 4);
1687 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1);
1688 if ((mlRep >= 4) && (gain2 > gain1))
1689 matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip;
1690 }
1691 }
1692 { size_t ofbCandidate=999999999;
1693 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, dictMode);
1694 int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */
1695 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 7);
1696 if ((ml2 >= 4) && (gain2 > gain1)) {
1697 matchLength = ml2, offBase = ofbCandidate, start = ip;
1698 continue;
1699 } } }
1700 break; /* nothing found : store previous solution */
1701 }
1702
1703 /* NOTE:
1704 * Pay attention that `start[-value]` can lead to strange undefined behavior
1705 * notably if `value` is unsigned, resulting in a large positive `-value`.
1706 */
1707 /* catch up */
1708 if (OFFBASE_IS_OFFSET(offBase)) {
1709 if (dictMode == ZSTD_noDict) {
1710 while ( ((start > anchor) & (start - OFFBASE_TO_OFFSET(offBase) > prefixLowest))
1711 && (start[-1] == (start-OFFBASE_TO_OFFSET(offBase))[-1]) ) /* only search for offset within prefix */
1712 { start--; matchLength++; }
1713 }
1714 if (isDxS) {
1715 U32 const matchIndex = (U32)((size_t)(start-base) - OFFBASE_TO_OFFSET(offBase));
1716 const BYTE* match = (matchIndex < prefixLowestIndex) ? dictBase + matchIndex - dictIndexDelta : base + matchIndex;
1717 const BYTE* const mStart = (matchIndex < prefixLowestIndex) ? dictLowest : prefixLowest;
1718 while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */
1719 }
1720 offset_2 = offset_1; offset_1 = (U32)OFFBASE_TO_OFFSET(offBase);
1721 }
1722 /* store sequence */
1723 _storeSequence:
1724 { size_t const litLength = (size_t)(start - anchor);
1725 ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offBase, matchLength);
1726 anchor = ip = start + matchLength;
1727 }
1728 if (ms->lazySkipping) {
1729 /* We've found a match, disable lazy skipping mode, and refill the hash cache. */
1730 if (searchMethod == search_rowHash) {
1731 ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit);
1732 }
1733 ms->lazySkipping = 0;
1734 }
1735
1736 /* check immediate repcode */
1737 if (isDxS) {
1738 while (ip <= ilimit) {
1739 U32 const current2 = (U32)(ip-base);
1740 U32 const repIndex = current2 - offset_2;
1741 const BYTE* repMatch = repIndex < prefixLowestIndex ?
1742 dictBase - dictIndexDelta + repIndex :
1743 base + repIndex;
1744 if ( (ZSTD_index_overlap_check(prefixLowestIndex, repIndex))
1745 && (MEM_read32(repMatch) == MEM_read32(ip)) ) {
1746 const BYTE* const repEnd2 = repIndex < prefixLowestIndex ? dictEnd : iend;
1747 matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd2, prefixLowest) + 4;
1748 offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap offset_2 <=> offset_1 */
1749 ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength);
1750 ip += matchLength;
1751 anchor = ip;
1752 continue;
1753 }
1754 break;
1755 }
1756 }
1757
1758 if (dictMode == ZSTD_noDict) {
1759 while ( ((ip <= ilimit) & (offset_2>0))
1760 && (MEM_read32(ip) == MEM_read32(ip - offset_2)) ) {
1761 /* store sequence */
1762 matchLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;
1763 offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap repcodes */
1764 ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength);
1765 ip += matchLength;
1766 anchor = ip;
1767 continue; /* faster when present ... (?) */
1768 } } }
1769
1770 /* If offset_1 started invalid (offsetSaved1 != 0) and became valid (offset_1 != 0),
1771 * rotate saved offsets. See comment in ZSTD_compressBlock_fast_noDict for more context. */
1772 offsetSaved2 = ((offsetSaved1 != 0) && (offset_1 != 0)) ? offsetSaved1 : offsetSaved2;
1773
1774 /* save reps for next block */
1775 rep[0] = offset_1 ? offset_1 : offsetSaved1;
1776 rep[1] = offset_2 ? offset_2 : offsetSaved2;
1777
1778 /* Return the last literals size */
1779 return (size_t)(iend - anchor);
1780 }
1781 #endif /* build exclusions */
1782
1783
1784 #ifndef ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR
ZSTD_compressBlock_greedy(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1785 size_t ZSTD_compressBlock_greedy(
1786 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1787 void const* src, size_t srcSize)
1788 {
1789 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_noDict);
1790 }
1791
ZSTD_compressBlock_greedy_dictMatchState(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1792 size_t ZSTD_compressBlock_greedy_dictMatchState(
1793 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1794 void const* src, size_t srcSize)
1795 {
1796 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dictMatchState);
1797 }
1798
ZSTD_compressBlock_greedy_dedicatedDictSearch(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1799 size_t ZSTD_compressBlock_greedy_dedicatedDictSearch(
1800 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1801 void const* src, size_t srcSize)
1802 {
1803 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dedicatedDictSearch);
1804 }
1805
ZSTD_compressBlock_greedy_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1806 size_t ZSTD_compressBlock_greedy_row(
1807 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1808 void const* src, size_t srcSize)
1809 {
1810 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_noDict);
1811 }
1812
ZSTD_compressBlock_greedy_dictMatchState_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1813 size_t ZSTD_compressBlock_greedy_dictMatchState_row(
1814 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1815 void const* src, size_t srcSize)
1816 {
1817 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_dictMatchState);
1818 }
1819
ZSTD_compressBlock_greedy_dedicatedDictSearch_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1820 size_t ZSTD_compressBlock_greedy_dedicatedDictSearch_row(
1821 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1822 void const* src, size_t srcSize)
1823 {
1824 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_dedicatedDictSearch);
1825 }
1826 #endif
1827
1828 #ifndef ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR
ZSTD_compressBlock_lazy(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1829 size_t ZSTD_compressBlock_lazy(
1830 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1831 void const* src, size_t srcSize)
1832 {
1833 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_noDict);
1834 }
1835
ZSTD_compressBlock_lazy_dictMatchState(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1836 size_t ZSTD_compressBlock_lazy_dictMatchState(
1837 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1838 void const* src, size_t srcSize)
1839 {
1840 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dictMatchState);
1841 }
1842
ZSTD_compressBlock_lazy_dedicatedDictSearch(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1843 size_t ZSTD_compressBlock_lazy_dedicatedDictSearch(
1844 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1845 void const* src, size_t srcSize)
1846 {
1847 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dedicatedDictSearch);
1848 }
1849
ZSTD_compressBlock_lazy_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1850 size_t ZSTD_compressBlock_lazy_row(
1851 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1852 void const* src, size_t srcSize)
1853 {
1854 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_noDict);
1855 }
1856
ZSTD_compressBlock_lazy_dictMatchState_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1857 size_t ZSTD_compressBlock_lazy_dictMatchState_row(
1858 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1859 void const* src, size_t srcSize)
1860 {
1861 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_dictMatchState);
1862 }
1863
ZSTD_compressBlock_lazy_dedicatedDictSearch_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1864 size_t ZSTD_compressBlock_lazy_dedicatedDictSearch_row(
1865 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1866 void const* src, size_t srcSize)
1867 {
1868 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_dedicatedDictSearch);
1869 }
1870 #endif
1871
1872 #ifndef ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR
ZSTD_compressBlock_lazy2(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1873 size_t ZSTD_compressBlock_lazy2(
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_hashChain, 2, ZSTD_noDict);
1878 }
1879
ZSTD_compressBlock_lazy2_dictMatchState(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1880 size_t ZSTD_compressBlock_lazy2_dictMatchState(
1881 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1882 void const* src, size_t srcSize)
1883 {
1884 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dictMatchState);
1885 }
1886
ZSTD_compressBlock_lazy2_dedicatedDictSearch(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1887 size_t ZSTD_compressBlock_lazy2_dedicatedDictSearch(
1888 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1889 void const* src, size_t srcSize)
1890 {
1891 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dedicatedDictSearch);
1892 }
1893
ZSTD_compressBlock_lazy2_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1894 size_t ZSTD_compressBlock_lazy2_row(
1895 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1896 void const* src, size_t srcSize)
1897 {
1898 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_noDict);
1899 }
1900
ZSTD_compressBlock_lazy2_dictMatchState_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1901 size_t ZSTD_compressBlock_lazy2_dictMatchState_row(
1902 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1903 void const* src, size_t srcSize)
1904 {
1905 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_dictMatchState);
1906 }
1907
ZSTD_compressBlock_lazy2_dedicatedDictSearch_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1908 size_t ZSTD_compressBlock_lazy2_dedicatedDictSearch_row(
1909 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1910 void const* src, size_t srcSize)
1911 {
1912 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_dedicatedDictSearch);
1913 }
1914 #endif
1915
1916 #ifndef ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR
ZSTD_compressBlock_btlazy2(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1917 size_t ZSTD_compressBlock_btlazy2(
1918 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1919 void const* src, size_t srcSize)
1920 {
1921 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_noDict);
1922 }
1923
ZSTD_compressBlock_btlazy2_dictMatchState(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)1924 size_t ZSTD_compressBlock_btlazy2_dictMatchState(
1925 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
1926 void const* src, size_t srcSize)
1927 {
1928 return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_dictMatchState);
1929 }
1930 #endif
1931
1932 #if !defined(ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR) \
1933 || !defined(ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR) \
1934 || !defined(ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR) \
1935 || !defined(ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR)
1936 FORCE_INLINE_TEMPLATE
1937 ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
ZSTD_compressBlock_lazy_extDict_generic(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],const void * src,size_t srcSize,const searchMethod_e searchMethod,const U32 depth)1938 size_t ZSTD_compressBlock_lazy_extDict_generic(
1939 ZSTD_MatchState_t* ms, SeqStore_t* seqStore,
1940 U32 rep[ZSTD_REP_NUM],
1941 const void* src, size_t srcSize,
1942 const searchMethod_e searchMethod, const U32 depth)
1943 {
1944 const BYTE* const istart = (const BYTE*)src;
1945 const BYTE* ip = istart;
1946 const BYTE* anchor = istart;
1947 const BYTE* const iend = istart + srcSize;
1948 const BYTE* const ilimit = searchMethod == search_rowHash ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8;
1949 const BYTE* const base = ms->window.base;
1950 const U32 dictLimit = ms->window.dictLimit;
1951 const BYTE* const prefixStart = base + dictLimit;
1952 const BYTE* const dictBase = ms->window.dictBase;
1953 const BYTE* const dictEnd = dictBase + dictLimit;
1954 const BYTE* const dictStart = dictBase + ms->window.lowLimit;
1955 const U32 windowLog = ms->cParams.windowLog;
1956 const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6);
1957 const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6);
1958
1959 U32 offset_1 = rep[0], offset_2 = rep[1];
1960
1961 DEBUGLOG(5, "ZSTD_compressBlock_lazy_extDict_generic (searchFunc=%u)", (U32)searchMethod);
1962
1963 /* Reset the lazy skipping state */
1964 ms->lazySkipping = 0;
1965
1966 /* init */
1967 ip += (ip == prefixStart);
1968 if (searchMethod == search_rowHash) {
1969 ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit);
1970 }
1971
1972 /* Match Loop */
1973 #if defined(__x86_64__)
1974 /* I've measured random a 5% speed loss on levels 5 & 6 (greedy) when the
1975 * code alignment is perturbed. To fix the instability align the loop on 32-bytes.
1976 */
1977 __asm__(".p2align 5");
1978 #endif
1979 while (ip < ilimit) {
1980 size_t matchLength=0;
1981 size_t offBase = REPCODE1_TO_OFFBASE;
1982 const BYTE* start=ip+1;
1983 U32 curr = (U32)(ip-base);
1984
1985 /* check repCode */
1986 { const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr+1, windowLog);
1987 const U32 repIndex = (U32)(curr+1 - offset_1);
1988 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
1989 const BYTE* const repMatch = repBase + repIndex;
1990 if ( (ZSTD_index_overlap_check(dictLimit, repIndex))
1991 & (offset_1 <= curr+1 - windowLow) ) /* note: we are searching at curr+1 */
1992 if (MEM_read32(ip+1) == MEM_read32(repMatch)) {
1993 /* repcode detected we should take it */
1994 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
1995 matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repEnd, prefixStart) + 4;
1996 if (depth==0) goto _storeSequence;
1997 } }
1998
1999 /* first search (depth 0) */
2000 { size_t ofbCandidate = 999999999;
2001 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict);
2002 if (ml2 > matchLength)
2003 matchLength = ml2, start = ip, offBase = ofbCandidate;
2004 }
2005
2006 if (matchLength < 4) {
2007 size_t const step = ((size_t)(ip-anchor) >> kSearchStrength);
2008 ip += step + 1; /* jump faster over incompressible sections */
2009 /* Enter the lazy skipping mode once we are skipping more than 8 bytes at a time.
2010 * In this mode we stop inserting every position into our tables, and only insert
2011 * positions that we search, which is one in step positions.
2012 * The exact cutoff is flexible, I've just chosen a number that is reasonably high,
2013 * so we minimize the compression ratio loss in "normal" scenarios. This mode gets
2014 * triggered once we've gone 2KB without finding any matches.
2015 */
2016 ms->lazySkipping = step > kLazySkippingStep;
2017 continue;
2018 }
2019
2020 /* let's try to find a better solution */
2021 if (depth>=1)
2022 while (ip<ilimit) {
2023 ip ++;
2024 curr++;
2025 /* check repCode */
2026 if (offBase) {
2027 const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog);
2028 const U32 repIndex = (U32)(curr - offset_1);
2029 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
2030 const BYTE* const repMatch = repBase + repIndex;
2031 if ( (ZSTD_index_overlap_check(dictLimit, repIndex))
2032 & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
2033 if (MEM_read32(ip) == MEM_read32(repMatch)) {
2034 /* repcode detected */
2035 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
2036 size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
2037 int const gain2 = (int)(repLength * 3);
2038 int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1);
2039 if ((repLength >= 4) && (gain2 > gain1))
2040 matchLength = repLength, offBase = REPCODE1_TO_OFFBASE, start = ip;
2041 } }
2042
2043 /* search match, depth 1 */
2044 { size_t ofbCandidate = 999999999;
2045 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict);
2046 int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */
2047 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 4);
2048 if ((ml2 >= 4) && (gain2 > gain1)) {
2049 matchLength = ml2, offBase = ofbCandidate, start = ip;
2050 continue; /* search a better one */
2051 } }
2052
2053 /* let's find an even better one */
2054 if ((depth==2) && (ip<ilimit)) {
2055 ip ++;
2056 curr++;
2057 /* check repCode */
2058 if (offBase) {
2059 const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog);
2060 const U32 repIndex = (U32)(curr - offset_1);
2061 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
2062 const BYTE* const repMatch = repBase + repIndex;
2063 if ( (ZSTD_index_overlap_check(dictLimit, repIndex))
2064 & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
2065 if (MEM_read32(ip) == MEM_read32(repMatch)) {
2066 /* repcode detected */
2067 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
2068 size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
2069 int const gain2 = (int)(repLength * 4);
2070 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1);
2071 if ((repLength >= 4) && (gain2 > gain1))
2072 matchLength = repLength, offBase = REPCODE1_TO_OFFBASE, start = ip;
2073 } }
2074
2075 /* search match, depth 2 */
2076 { size_t ofbCandidate = 999999999;
2077 size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict);
2078 int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */
2079 int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 7);
2080 if ((ml2 >= 4) && (gain2 > gain1)) {
2081 matchLength = ml2, offBase = ofbCandidate, start = ip;
2082 continue;
2083 } } }
2084 break; /* nothing found : store previous solution */
2085 }
2086
2087 /* catch up */
2088 if (OFFBASE_IS_OFFSET(offBase)) {
2089 U32 const matchIndex = (U32)((size_t)(start-base) - OFFBASE_TO_OFFSET(offBase));
2090 const BYTE* match = (matchIndex < dictLimit) ? dictBase + matchIndex : base + matchIndex;
2091 const BYTE* const mStart = (matchIndex < dictLimit) ? dictStart : prefixStart;
2092 while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */
2093 offset_2 = offset_1; offset_1 = (U32)OFFBASE_TO_OFFSET(offBase);
2094 }
2095
2096 /* store sequence */
2097 _storeSequence:
2098 { size_t const litLength = (size_t)(start - anchor);
2099 ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offBase, matchLength);
2100 anchor = ip = start + matchLength;
2101 }
2102 if (ms->lazySkipping) {
2103 /* We've found a match, disable lazy skipping mode, and refill the hash cache. */
2104 if (searchMethod == search_rowHash) {
2105 ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit);
2106 }
2107 ms->lazySkipping = 0;
2108 }
2109
2110 /* check immediate repcode */
2111 while (ip <= ilimit) {
2112 const U32 repCurrent = (U32)(ip-base);
2113 const U32 windowLow = ZSTD_getLowestMatchIndex(ms, repCurrent, windowLog);
2114 const U32 repIndex = repCurrent - offset_2;
2115 const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
2116 const BYTE* const repMatch = repBase + repIndex;
2117 if ( (ZSTD_index_overlap_check(dictLimit, repIndex))
2118 & (offset_2 <= repCurrent - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */
2119 if (MEM_read32(ip) == MEM_read32(repMatch)) {
2120 /* repcode detected we should take it */
2121 const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
2122 matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4;
2123 offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap offset history */
2124 ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength);
2125 ip += matchLength;
2126 anchor = ip;
2127 continue; /* faster when present ... (?) */
2128 }
2129 break;
2130 } }
2131
2132 /* Save reps for next block */
2133 rep[0] = offset_1;
2134 rep[1] = offset_2;
2135
2136 /* Return the last literals size */
2137 return (size_t)(iend - anchor);
2138 }
2139 #endif /* build exclusions */
2140
2141 #ifndef ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR
ZSTD_compressBlock_greedy_extDict(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)2142 size_t ZSTD_compressBlock_greedy_extDict(
2143 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
2144 void const* src, size_t srcSize)
2145 {
2146 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0);
2147 }
2148
ZSTD_compressBlock_greedy_extDict_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)2149 size_t ZSTD_compressBlock_greedy_extDict_row(
2150 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
2151 void const* src, size_t srcSize)
2152 {
2153 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0);
2154 }
2155 #endif
2156
2157 #ifndef ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR
ZSTD_compressBlock_lazy_extDict(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)2158 size_t ZSTD_compressBlock_lazy_extDict(
2159 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
2160 void const* src, size_t srcSize)
2161
2162 {
2163 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1);
2164 }
2165
ZSTD_compressBlock_lazy_extDict_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)2166 size_t ZSTD_compressBlock_lazy_extDict_row(
2167 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
2168 void const* src, size_t srcSize)
2169
2170 {
2171 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1);
2172 }
2173 #endif
2174
2175 #ifndef ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR
ZSTD_compressBlock_lazy2_extDict(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)2176 size_t ZSTD_compressBlock_lazy2_extDict(
2177 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
2178 void const* src, size_t srcSize)
2179
2180 {
2181 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2);
2182 }
2183
ZSTD_compressBlock_lazy2_extDict_row(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)2184 size_t ZSTD_compressBlock_lazy2_extDict_row(
2185 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
2186 void const* src, size_t srcSize)
2187 {
2188 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2);
2189 }
2190 #endif
2191
2192 #ifndef ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR
ZSTD_compressBlock_btlazy2_extDict(ZSTD_MatchState_t * ms,SeqStore_t * seqStore,U32 rep[ZSTD_REP_NUM],void const * src,size_t srcSize)2193 size_t ZSTD_compressBlock_btlazy2_extDict(
2194 ZSTD_MatchState_t* ms, SeqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
2195 void const* src, size_t srcSize)
2196
2197 {
2198 return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2);
2199 }
2200 #endif
2201