-
Notifications
You must be signed in to change notification settings - Fork 89
/
zstd_lazy.c
2202 lines (1973 loc) · 101 KB
/
zstd_lazy.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
#ifndef USE_EXTERNAL_ZSTD
/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
* All rights reserved.
*
* This source code is licensed under both the BSD-style license (found in the
* LICENSE file in the root directory of this source tree) and the GPLv2 (found
* in the COPYING file in the root directory of this source tree).
* You may select, at your option, one of the above-listed licenses.
*/
#include "zstd_compress_internal.h"
#include "zstd_lazy.h"
#include "bits.h" /* ZSTD_countTrailingZeros64 */
#if !defined(ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR) \
|| !defined(ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR) \
|| !defined(ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR) \
|| !defined(ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR)
#define kLazySkippingStep 8
/*-*************************************
* Binary Tree search
***************************************/
static
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
void ZSTD_updateDUBT(ZSTD_matchState_t* ms,
const BYTE* ip, const BYTE* iend,
U32 mls)
{
const ZSTD_compressionParameters* const cParams = &ms->cParams;
U32* const hashTable = ms->hashTable;
U32 const hashLog = cParams->hashLog;
U32* const bt = ms->chainTable;
U32 const btLog = cParams->chainLog - 1;
U32 const btMask = (1 << btLog) - 1;
const BYTE* const base = ms->window.base;
U32 const target = (U32)(ip - base);
U32 idx = ms->nextToUpdate;
if (idx != target)
DEBUGLOG(7, "ZSTD_updateDUBT, from %u to %u (dictLimit:%u)",
idx, target, ms->window.dictLimit);
assert(ip + 8 <= iend); /* condition for ZSTD_hashPtr */
(void)iend;
assert(idx >= ms->window.dictLimit); /* condition for valid base+idx */
for ( ; idx < target ; idx++) {
size_t const h = ZSTD_hashPtr(base + idx, hashLog, mls); /* assumption : ip + 8 <= iend */
U32 const matchIndex = hashTable[h];
U32* const nextCandidatePtr = bt + 2*(idx&btMask);
U32* const sortMarkPtr = nextCandidatePtr + 1;
DEBUGLOG(8, "ZSTD_updateDUBT: insert %u", idx);
hashTable[h] = idx; /* Update Hash Table */
*nextCandidatePtr = matchIndex; /* update BT like a chain */
*sortMarkPtr = ZSTD_DUBT_UNSORTED_MARK;
}
ms->nextToUpdate = target;
}
/** ZSTD_insertDUBT1() :
* sort one already inserted but unsorted position
* assumption : curr >= btlow == (curr - btmask)
* doesn't fail */
static
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
void ZSTD_insertDUBT1(const ZSTD_matchState_t* ms,
U32 curr, const BYTE* inputEnd,
U32 nbCompares, U32 btLow,
const ZSTD_dictMode_e dictMode)
{
const ZSTD_compressionParameters* const cParams = &ms->cParams;
U32* const bt = ms->chainTable;
U32 const btLog = cParams->chainLog - 1;
U32 const btMask = (1 << btLog) - 1;
size_t commonLengthSmaller=0, commonLengthLarger=0;
const BYTE* const base = ms->window.base;
const BYTE* const dictBase = ms->window.dictBase;
const U32 dictLimit = ms->window.dictLimit;
const BYTE* const ip = (curr>=dictLimit) ? base + curr : dictBase + curr;
const BYTE* const iend = (curr>=dictLimit) ? inputEnd : dictBase + dictLimit;
const BYTE* const dictEnd = dictBase + dictLimit;
const BYTE* const prefixStart = base + dictLimit;
const BYTE* match;
U32* smallerPtr = bt + 2*(curr&btMask);
U32* largerPtr = smallerPtr + 1;
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) */
U32 dummy32; /* to be nullified at the end */
U32 const windowValid = ms->window.lowLimit;
U32 const maxDistance = 1U << cParams->windowLog;
U32 const windowLow = (curr - windowValid > maxDistance) ? curr - maxDistance : windowValid;
DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)",
curr, dictLimit, windowLow);
assert(curr >= btLow);
assert(ip < iend); /* condition for ZSTD_count */
for (; nbCompares && (matchIndex > windowLow); --nbCompares) {
U32* const nextPtr = bt + 2*(matchIndex & btMask);
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
assert(matchIndex < curr);
/* note : all candidates are now supposed sorted,
* but it's still possible to have nextPtr[1] == ZSTD_DUBT_UNSORTED_MARK
* when a real index has the same value as ZSTD_DUBT_UNSORTED_MARK */
if ( (dictMode != ZSTD_extDict)
|| (matchIndex+matchLength >= dictLimit) /* both in current segment*/
|| (curr < dictLimit) /* both in extDict */) {
const BYTE* const mBase = ( (dictMode != ZSTD_extDict)
|| (matchIndex+matchLength >= dictLimit)) ?
base : dictBase;
assert( (matchIndex+matchLength >= dictLimit) /* might be wrong if extDict is incorrectly set to 0 */
|| (curr < dictLimit) );
match = mBase + matchIndex;
matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend);
} else {
match = dictBase + matchIndex;
matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
if (matchIndex+matchLength >= dictLimit)
match = base + matchIndex; /* preparation for next read of match[matchLength] */
}
DEBUGLOG(8, "ZSTD_insertDUBT1: comparing %u with %u : found %u common bytes ",
curr, matchIndex, (U32)matchLength);
if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */
break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */
}
if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */
/* match is smaller than current */
*smallerPtr = matchIndex; /* update smaller idx */
commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */
DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is smaller : next => %u",
matchIndex, btLow, nextPtr[1]);
smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */
matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */
} else {
/* match is larger than current */
*largerPtr = matchIndex;
commonLengthLarger = matchLength;
if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */
DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is larger => %u",
matchIndex, btLow, nextPtr[0]);
largerPtr = nextPtr;
matchIndex = nextPtr[0];
} }
*smallerPtr = *largerPtr = 0;
}
static
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
size_t 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)
{
const ZSTD_matchState_t * const dms = ms->dictMatchState;
const ZSTD_compressionParameters* const dmsCParams = &dms->cParams;
const U32 * const dictHashTable = dms->hashTable;
U32 const hashLog = dmsCParams->hashLog;
size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
U32 dictMatchIndex = dictHashTable[h];
const BYTE* const base = ms->window.base;
const BYTE* const prefixStart = base + ms->window.dictLimit;
U32 const curr = (U32)(ip-base);
const BYTE* const dictBase = dms->window.base;
const BYTE* const dictEnd = dms->window.nextSrc;
U32 const dictHighLimit = (U32)(dms->window.nextSrc - dms->window.base);
U32 const dictLowLimit = dms->window.lowLimit;
U32 const dictIndexDelta = ms->window.lowLimit - dictHighLimit;
U32* const dictBt = dms->chainTable;
U32 const btLog = dmsCParams->chainLog - 1;
U32 const btMask = (1 << btLog) - 1;
U32 const btLow = (btMask >= dictHighLimit - dictLowLimit) ? dictLowLimit : dictHighLimit - btMask;
size_t commonLengthSmaller=0, commonLengthLarger=0;
(void)dictMode;
assert(dictMode == ZSTD_dictMatchState);
for (; nbCompares && (dictMatchIndex > dictLowLimit); --nbCompares) {
U32* const nextPtr = dictBt + 2*(dictMatchIndex & btMask);
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
const BYTE* match = dictBase + dictMatchIndex;
matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
if (dictMatchIndex+matchLength >= dictHighLimit)
match = base + dictMatchIndex + dictIndexDelta; /* to prepare for next usage of match[matchLength] */
if (matchLength > bestLength) {
U32 matchIndex = dictMatchIndex + dictIndexDelta;
if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) ) {
DEBUGLOG(9, "ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u)",
curr, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, OFFSET_TO_OFFBASE(curr - matchIndex), dictMatchIndex, matchIndex);
bestLength = matchLength, *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex);
}
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 */
break; /* drop, to guarantee consistency (miss a little bit of compression) */
}
}
if (match[matchLength] < ip[matchLength]) {
if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */
commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */
} else {
/* match is larger than current */
if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */
commonLengthLarger = matchLength;
dictMatchIndex = nextPtr[0];
}
}
if (bestLength >= MINMATCH) {
U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offsetPtr); (void)mIndex;
DEBUGLOG(8, "ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
curr, (U32)bestLength, (U32)*offsetPtr, mIndex);
}
return bestLength;
}
static
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
size_t 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)
{
const ZSTD_compressionParameters* const cParams = &ms->cParams;
U32* const hashTable = ms->hashTable;
U32 const hashLog = cParams->hashLog;
size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
U32 matchIndex = hashTable[h];
const BYTE* const base = ms->window.base;
U32 const curr = (U32)(ip-base);
U32 const windowLow = ZSTD_getLowestMatchIndex(ms, curr, cParams->windowLog);
U32* const bt = ms->chainTable;
U32 const btLog = cParams->chainLog - 1;
U32 const btMask = (1 << btLog) - 1;
U32 const btLow = (btMask >= curr) ? 0 : curr - btMask;
U32 const unsortLimit = MAX(btLow, windowLow);
U32* nextCandidate = bt + 2*(matchIndex&btMask);
U32* unsortedMark = bt + 2*(matchIndex&btMask) + 1;
U32 nbCompares = 1U << cParams->searchLog;
U32 nbCandidates = nbCompares;
U32 previousCandidate = 0;
DEBUGLOG(7, "ZSTD_DUBT_findBestMatch (%u) ", curr);
assert(ip <= iend-8); /* required for h calculation */
assert(dictMode != ZSTD_dedicatedDictSearch);
/* reach end of unsorted candidates list */
while ( (matchIndex > unsortLimit)
&& (*unsortedMark == ZSTD_DUBT_UNSORTED_MARK)
&& (nbCandidates > 1) ) {
DEBUGLOG(8, "ZSTD_DUBT_findBestMatch: candidate %u is unsorted",
matchIndex);
*unsortedMark = previousCandidate; /* the unsortedMark becomes a reversed chain, to move up back to original position */
previousCandidate = matchIndex;
matchIndex = *nextCandidate;
nextCandidate = bt + 2*(matchIndex&btMask);
unsortedMark = bt + 2*(matchIndex&btMask) + 1;
nbCandidates --;
}
/* nullify last candidate if it's still unsorted
* simplification, detrimental to compression ratio, beneficial for speed */
if ( (matchIndex > unsortLimit)
&& (*unsortedMark==ZSTD_DUBT_UNSORTED_MARK) ) {
DEBUGLOG(7, "ZSTD_DUBT_findBestMatch: nullify last unsorted candidate %u",
matchIndex);
*nextCandidate = *unsortedMark = 0;
}
/* batch sort stacked candidates */
matchIndex = previousCandidate;
while (matchIndex) { /* will end on matchIndex == 0 */
U32* const nextCandidateIdxPtr = bt + 2*(matchIndex&btMask) + 1;
U32 const nextCandidateIdx = *nextCandidateIdxPtr;
ZSTD_insertDUBT1(ms, matchIndex, iend,
nbCandidates, unsortLimit, dictMode);
matchIndex = nextCandidateIdx;
nbCandidates++;
}
/* find longest match */
{ size_t commonLengthSmaller = 0, commonLengthLarger = 0;
const BYTE* const dictBase = ms->window.dictBase;
const U32 dictLimit = ms->window.dictLimit;
const BYTE* const dictEnd = dictBase + dictLimit;
const BYTE* const prefixStart = base + dictLimit;
U32* smallerPtr = bt + 2*(curr&btMask);
U32* largerPtr = bt + 2*(curr&btMask) + 1;
U32 matchEndIdx = curr + 8 + 1;
U32 dummy32; /* to be nullified at the end */
size_t bestLength = 0;
matchIndex = hashTable[h];
hashTable[h] = curr; /* Update Hash Table */
for (; nbCompares && (matchIndex > windowLow); --nbCompares) {
U32* const nextPtr = bt + 2*(matchIndex & btMask);
size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
const BYTE* match;
if ((dictMode != ZSTD_extDict) || (matchIndex+matchLength >= dictLimit)) {
match = base + matchIndex;
matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend);
} else {
match = dictBase + matchIndex;
matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart);
if (matchIndex+matchLength >= dictLimit)
match = base + matchIndex; /* to prepare for next usage of match[matchLength] */
}
if (matchLength > bestLength) {
if (matchLength > matchEndIdx - matchIndex)
matchEndIdx = matchIndex + (U32)matchLength;
if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr - matchIndex + 1) - ZSTD_highbit32((U32)*offBasePtr)) )
bestLength = matchLength, *offBasePtr = OFFSET_TO_OFFBASE(curr - matchIndex);
if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */
if (dictMode == ZSTD_dictMatchState) {
nbCompares = 0; /* in addition to avoiding checking any
* further in this loop, make sure we
* skip checking in the dictionary. */
}
break; /* drop, to guarantee consistency (miss a little bit of compression) */
}
}
if (match[matchLength] < ip[matchLength]) {
/* match is smaller than current */
*smallerPtr = matchIndex; /* update smaller idx */
commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */
smallerPtr = nextPtr+1; /* new "smaller" => larger of match */
matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */
} else {
/* match is larger than current */
*largerPtr = matchIndex;
commonLengthLarger = matchLength;
if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */
largerPtr = nextPtr;
matchIndex = nextPtr[0];
} }
*smallerPtr = *largerPtr = 0;
assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
if (dictMode == ZSTD_dictMatchState && nbCompares) {
bestLength = ZSTD_DUBT_findBetterDictMatch(
ms, ip, iend,
offBasePtr, bestLength, nbCompares,
mls, dictMode);
}
assert(matchEndIdx > curr+8); /* ensure nextToUpdate is increased */
ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */
if (bestLength >= MINMATCH) {
U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offBasePtr); (void)mIndex;
DEBUGLOG(8, "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
curr, (U32)bestLength, (U32)*offBasePtr, mIndex);
}
return bestLength;
}
}
/** ZSTD_BtFindBestMatch() : Tree updater, providing best match */
FORCE_INLINE_TEMPLATE
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
size_t ZSTD_BtFindBestMatch( ZSTD_matchState_t* ms,
const BYTE* const ip, const BYTE* const iLimit,
size_t* offBasePtr,
const U32 mls /* template */,
const ZSTD_dictMode_e dictMode)
{
DEBUGLOG(7, "ZSTD_BtFindBestMatch");
if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */
ZSTD_updateDUBT(ms, ip, iLimit, mls);
return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offBasePtr, mls, dictMode);
}
/***********************************
* Dedicated dict search
***********************************/
void ZSTD_dedicatedDictSearch_lazy_loadDictionary(ZSTD_matchState_t* ms, const BYTE* const ip)
{
const BYTE* const base = ms->window.base;
U32 const target = (U32)(ip - base);
U32* const hashTable = ms->hashTable;
U32* const chainTable = ms->chainTable;
U32 const chainSize = 1 << ms->cParams.chainLog;
U32 idx = ms->nextToUpdate;
U32 const minChain = chainSize < target - idx ? target - chainSize : idx;
U32 const bucketSize = 1 << ZSTD_LAZY_DDSS_BUCKET_LOG;
U32 const cacheSize = bucketSize - 1;
U32 const chainAttempts = (1 << ms->cParams.searchLog) - cacheSize;
U32 const chainLimit = chainAttempts > 255 ? 255 : chainAttempts;
/* We know the hashtable is oversized by a factor of `bucketSize`.
* We are going to temporarily pretend `bucketSize == 1`, keeping only a
* single entry. We will use the rest of the space to construct a temporary
* chaintable.
*/
U32 const hashLog = ms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG;
U32* const tmpHashTable = hashTable;
U32* const tmpChainTable = hashTable + ((size_t)1 << hashLog);
U32 const tmpChainSize = (U32)((1 << ZSTD_LAZY_DDSS_BUCKET_LOG) - 1) << hashLog;
U32 const tmpMinChain = tmpChainSize < target ? target - tmpChainSize : idx;
U32 hashIdx;
assert(ms->cParams.chainLog <= 24);
assert(ms->cParams.hashLog > ms->cParams.chainLog);
assert(idx != 0);
assert(tmpMinChain <= minChain);
/* fill conventional hash table and conventional chain table */
for ( ; idx < target; idx++) {
U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch);
if (idx >= tmpMinChain) {
tmpChainTable[idx - tmpMinChain] = hashTable[h];
}
tmpHashTable[h] = idx;
}
/* sort chains into ddss chain table */
{
U32 chainPos = 0;
for (hashIdx = 0; hashIdx < (1U << hashLog); hashIdx++) {
U32 count;
U32 countBeyondMinChain = 0;
U32 i = tmpHashTable[hashIdx];
for (count = 0; i >= tmpMinChain && count < cacheSize; count++) {
/* skip through the chain to the first position that won't be
* in the hash cache bucket */
if (i < minChain) {
countBeyondMinChain++;
}
i = tmpChainTable[i - tmpMinChain];
}
if (count == cacheSize) {
for (count = 0; count < chainLimit;) {
if (i < minChain) {
if (!i || ++countBeyondMinChain > cacheSize) {
/* only allow pulling `cacheSize` number of entries
* into the cache or chainTable beyond `minChain`,
* to replace the entries pulled out of the
* chainTable into the cache. This lets us reach
* back further without increasing the total number
* of entries in the chainTable, guaranteeing the
* DDSS chain table will fit into the space
* allocated for the regular one. */
break;
}
}
chainTable[chainPos++] = i;
count++;
if (i < tmpMinChain) {
break;
}
i = tmpChainTable[i - tmpMinChain];
}
} else {
count = 0;
}
if (count) {
tmpHashTable[hashIdx] = ((chainPos - count) << 8) + count;
} else {
tmpHashTable[hashIdx] = 0;
}
}
assert(chainPos <= chainSize); /* I believe this is guaranteed... */
}
/* move chain pointers into the last entry of each hash bucket */
for (hashIdx = (1 << hashLog); hashIdx; ) {
U32 const bucketIdx = --hashIdx << ZSTD_LAZY_DDSS_BUCKET_LOG;
U32 const chainPackedPointer = tmpHashTable[hashIdx];
U32 i;
for (i = 0; i < cacheSize; i++) {
hashTable[bucketIdx + i] = 0;
}
hashTable[bucketIdx + bucketSize - 1] = chainPackedPointer;
}
/* fill the buckets of the hash table */
for (idx = ms->nextToUpdate; idx < target; idx++) {
U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch)
<< ZSTD_LAZY_DDSS_BUCKET_LOG;
U32 i;
/* Shift hash cache down 1. */
for (i = cacheSize - 1; i; i--)
hashTable[h + i] = hashTable[h + i - 1];
hashTable[h] = idx;
}
ms->nextToUpdate = target;
}
/* Returns the longest match length found in the dedicated dict search structure.
* If none are longer than the argument ml, then ml will be returned.
*/
FORCE_INLINE_TEMPLATE
size_t 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) {
const U32 ddsLowestIndex = dms->window.dictLimit;
const BYTE* const ddsBase = dms->window.base;
const BYTE* const ddsEnd = dms->window.nextSrc;
const U32 ddsSize = (U32)(ddsEnd - ddsBase);
const U32 ddsIndexDelta = dictLimit - ddsSize;
const U32 bucketSize = (1 << ZSTD_LAZY_DDSS_BUCKET_LOG);
const U32 bucketLimit = nbAttempts < bucketSize - 1 ? nbAttempts : bucketSize - 1;
U32 ddsAttempt;
U32 matchIndex;
for (ddsAttempt = 0; ddsAttempt < bucketSize - 1; ddsAttempt++) {
PREFETCH_L1(ddsBase + dms->hashTable[ddsIdx + ddsAttempt]);
}
{
U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1];
U32 const chainIndex = chainPackedPointer >> 8;
PREFETCH_L1(&dms->chainTable[chainIndex]);
}
for (ddsAttempt = 0; ddsAttempt < bucketLimit; ddsAttempt++) {
size_t currentMl=0;
const BYTE* match;
matchIndex = dms->hashTable[ddsIdx + ddsAttempt];
match = ddsBase + matchIndex;
if (!matchIndex) {
return ml;
}
/* guaranteed by table construction */
(void)ddsLowestIndex;
assert(matchIndex >= ddsLowestIndex);
assert(match+4 <= ddsEnd);
if (MEM_read32(match) == MEM_read32(ip)) {
/* assumption : matchIndex <= dictLimit-4 (by table construction) */
currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4;
}
/* save best solution */
if (currentMl > ml) {
ml = currentMl;
*offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta));
if (ip+currentMl == iLimit) {
/* best possible, avoids read overflow on next attempt */
return ml;
}
}
}
{
U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1];
U32 chainIndex = chainPackedPointer >> 8;
U32 const chainLength = chainPackedPointer & 0xFF;
U32 const chainAttempts = nbAttempts - ddsAttempt;
U32 const chainLimit = chainAttempts > chainLength ? chainLength : chainAttempts;
U32 chainAttempt;
for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++) {
PREFETCH_L1(ddsBase + dms->chainTable[chainIndex + chainAttempt]);
}
for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++, chainIndex++) {
size_t currentMl=0;
const BYTE* match;
matchIndex = dms->chainTable[chainIndex];
match = ddsBase + matchIndex;
/* guaranteed by table construction */
assert(matchIndex >= ddsLowestIndex);
assert(match+4 <= ddsEnd);
if (MEM_read32(match) == MEM_read32(ip)) {
/* assumption : matchIndex <= dictLimit-4 (by table construction) */
currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4;
}
/* save best solution */
if (currentMl > ml) {
ml = currentMl;
*offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta));
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
}
}
}
return ml;
}
/* *********************************
* Hash Chain
***********************************/
#define NEXT_IN_CHAIN(d, mask) chainTable[(d) & (mask)]
/* Update chains up to ip (excluded)
Assumption : always within prefix (i.e. not within extDict) */
FORCE_INLINE_TEMPLATE
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
U32 ZSTD_insertAndFindFirstIndex_internal(
ZSTD_matchState_t* ms,
const ZSTD_compressionParameters* const cParams,
const BYTE* ip, U32 const mls, U32 const lazySkipping)
{
U32* const hashTable = ms->hashTable;
const U32 hashLog = cParams->hashLog;
U32* const chainTable = ms->chainTable;
const U32 chainMask = (1 << cParams->chainLog) - 1;
const BYTE* const base = ms->window.base;
const U32 target = (U32)(ip - base);
U32 idx = ms->nextToUpdate;
while(idx < target) { /* catch up */
size_t const h = ZSTD_hashPtr(base+idx, hashLog, mls);
NEXT_IN_CHAIN(idx, chainMask) = hashTable[h];
hashTable[h] = idx;
idx++;
/* Stop inserting every position when in the lazy skipping mode. */
if (lazySkipping)
break;
}
ms->nextToUpdate = target;
return hashTable[ZSTD_hashPtr(ip, hashLog, mls)];
}
U32 ZSTD_insertAndFindFirstIndex(ZSTD_matchState_t* ms, const BYTE* ip) {
const ZSTD_compressionParameters* const cParams = &ms->cParams;
return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, ms->cParams.minMatch, /* lazySkipping*/ 0);
}
/* inlining is important to hardwire a hot branch (template emulation) */
FORCE_INLINE_TEMPLATE
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
size_t 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)
{
const ZSTD_compressionParameters* const cParams = &ms->cParams;
U32* const chainTable = ms->chainTable;
const U32 chainSize = (1 << cParams->chainLog);
const U32 chainMask = chainSize-1;
const BYTE* const base = ms->window.base;
const BYTE* const dictBase = ms->window.dictBase;
const U32 dictLimit = ms->window.dictLimit;
const BYTE* const prefixStart = base + dictLimit;
const BYTE* const dictEnd = dictBase + dictLimit;
const U32 curr = (U32)(ip-base);
const U32 maxDistance = 1U << cParams->windowLog;
const U32 lowestValid = ms->window.lowLimit;
const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid;
const U32 isDictionary = (ms->loadedDictEnd != 0);
const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance;
const U32 minChain = curr > chainSize ? curr - chainSize : 0;
U32 nbAttempts = 1U << cParams->searchLog;
size_t ml=4-1;
const ZSTD_matchState_t* const dms = ms->dictMatchState;
const U32 ddsHashLog = dictMode == ZSTD_dedicatedDictSearch
? dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG : 0;
const size_t ddsIdx = dictMode == ZSTD_dedicatedDictSearch
? ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG : 0;
U32 matchIndex;
if (dictMode == ZSTD_dedicatedDictSearch) {
const U32* entry = &dms->hashTable[ddsIdx];
PREFETCH_L1(entry);
}
/* HC4 match finder */
matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls, ms->lazySkipping);
for ( ; (matchIndex>=lowLimit) & (nbAttempts>0) ; nbAttempts--) {
size_t currentMl=0;
if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) {
const BYTE* const match = base + matchIndex;
assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */
/* read 4B starting from (match + ml + 1 - sizeof(U32)) */
if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */
currentMl = ZSTD_count(ip, match, iLimit);
} else {
const BYTE* const match = dictBase + matchIndex;
assert(match+4 <= dictEnd);
if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4;
}
/* save best solution */
if (currentMl > ml) {
ml = currentMl;
*offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex);
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
}
if (matchIndex <= minChain) break;
matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
}
assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */
if (dictMode == ZSTD_dedicatedDictSearch) {
ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts, dms,
ip, iLimit, prefixStart, curr, dictLimit, ddsIdx);
} else if (dictMode == ZSTD_dictMatchState) {
const U32* const dmsChainTable = dms->chainTable;
const U32 dmsChainSize = (1 << dms->cParams.chainLog);
const U32 dmsChainMask = dmsChainSize - 1;
const U32 dmsLowestIndex = dms->window.dictLimit;
const BYTE* const dmsBase = dms->window.base;
const BYTE* const dmsEnd = dms->window.nextSrc;
const U32 dmsSize = (U32)(dmsEnd - dmsBase);
const U32 dmsIndexDelta = dictLimit - dmsSize;
const U32 dmsMinChain = dmsSize > dmsChainSize ? dmsSize - dmsChainSize : 0;
matchIndex = dms->hashTable[ZSTD_hashPtr(ip, dms->cParams.hashLog, mls)];
for ( ; (matchIndex>=dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--) {
size_t currentMl=0;
const BYTE* const match = dmsBase + matchIndex;
assert(match+4 <= dmsEnd);
if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4;
/* save best solution */
if (currentMl > ml) {
ml = currentMl;
assert(curr > matchIndex + dmsIndexDelta);
*offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta));
if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */
}
if (matchIndex <= dmsMinChain) break;
matchIndex = dmsChainTable[matchIndex & dmsChainMask];
}
}
return ml;
}
/* *********************************
* (SIMD) Row-based matchfinder
***********************************/
/* Constants for row-based hash */
#define ZSTD_ROW_HASH_TAG_MASK ((1u << ZSTD_ROW_HASH_TAG_BITS) - 1)
#define ZSTD_ROW_HASH_MAX_ENTRIES 64 /* absolute maximum number of entries per row, for all configurations */
#define ZSTD_ROW_HASH_CACHE_MASK (ZSTD_ROW_HASH_CACHE_SIZE - 1)
typedef U64 ZSTD_VecMask; /* Clarifies when we are interacting with a U64 representing a mask of matches */
/* ZSTD_VecMask_next():
* Starting from the LSB, returns the idx of the next non-zero bit.
* Basically counting the nb of trailing zeroes.
*/
MEM_STATIC U32 ZSTD_VecMask_next(ZSTD_VecMask val) {
return ZSTD_countTrailingZeros64(val);
}
/* ZSTD_row_nextIndex():
* Returns the next index to insert at within a tagTable row, and updates the "head"
* value to reflect the update. Essentially cycles backwards from [1, {entries per row})
*/
FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextIndex(BYTE* const tagRow, U32 const rowMask) {
U32 next = (*tagRow-1) & rowMask;
next += (next == 0) ? rowMask : 0; /* skip first position */
*tagRow = (BYTE)next;
return next;
}
/* ZSTD_isAligned():
* Checks that a pointer is aligned to "align" bytes which must be a power of 2.
*/
MEM_STATIC int ZSTD_isAligned(void const* ptr, size_t align) {
assert((align & (align - 1)) == 0);
return (((size_t)ptr) & (align - 1)) == 0;
}
/* ZSTD_row_prefetch():
* Performs prefetching for the hashTable and tagTable at a given row.
*/
FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, BYTE const* tagTable, U32 const relRow, U32 const rowLog) {
PREFETCH_L1(hashTable + relRow);
if (rowLog >= 5) {
PREFETCH_L1(hashTable + relRow + 16);
/* Note: prefetching more of the hash table does not appear to be beneficial for 128-entry rows */
}
PREFETCH_L1(tagTable + relRow);
if (rowLog == 6) {
PREFETCH_L1(tagTable + relRow + 32);
}
assert(rowLog == 4 || rowLog == 5 || rowLog == 6);
assert(ZSTD_isAligned(hashTable + relRow, 64)); /* prefetched hash row always 64-byte aligned */
assert(ZSTD_isAligned(tagTable + relRow, (size_t)1 << rowLog)); /* prefetched tagRow sits on correct multiple of bytes (32,64,128) */
}
/* ZSTD_row_fillHashCache():
* Fill up the hash cache starting at idx, prefetching up to ZSTD_ROW_HASH_CACHE_SIZE entries,
* but not beyond iLimit.
*/
FORCE_INLINE_TEMPLATE
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
void ZSTD_row_fillHashCache(ZSTD_matchState_t* ms, const BYTE* base,
U32 const rowLog, U32 const mls,
U32 idx, const BYTE* const iLimit)
{
U32 const* const hashTable = ms->hashTable;
BYTE const* const tagTable = ms->tagTable;
U32 const hashLog = ms->rowHashLog;
U32 const maxElemsToPrefetch = (base + idx) > iLimit ? 0 : (U32)(iLimit - (base + idx) + 1);
U32 const lim = idx + MIN(ZSTD_ROW_HASH_CACHE_SIZE, maxElemsToPrefetch);
for (; idx < lim; ++idx) {
U32 const hash = (U32)ZSTD_hashPtrSalted(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt);
U32 const row = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
ZSTD_row_prefetch(hashTable, tagTable, row, rowLog);
ms->hashCache[idx & ZSTD_ROW_HASH_CACHE_MASK] = hash;
}
DEBUGLOG(6, "ZSTD_row_fillHashCache(): [%u %u %u %u %u %u %u %u]", ms->hashCache[0], ms->hashCache[1],
ms->hashCache[2], ms->hashCache[3], ms->hashCache[4],
ms->hashCache[5], ms->hashCache[6], ms->hashCache[7]);
}
/* ZSTD_row_nextCachedHash():
* Returns the hash of base + idx, and replaces the hash in the hash cache with the byte at
* base + idx + ZSTD_ROW_HASH_CACHE_SIZE. Also prefetches the appropriate rows from hashTable and tagTable.
*/
FORCE_INLINE_TEMPLATE
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
U32 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)
{
U32 const newHash = (U32)ZSTD_hashPtrSalted(base+idx+ZSTD_ROW_HASH_CACHE_SIZE, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt);
U32 const row = (newHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
ZSTD_row_prefetch(hashTable, tagTable, row, rowLog);
{ U32 const hash = cache[idx & ZSTD_ROW_HASH_CACHE_MASK];
cache[idx & ZSTD_ROW_HASH_CACHE_MASK] = newHash;
return hash;
}
}
/* ZSTD_row_update_internalImpl():
* Updates the hash table with positions starting from updateStartIdx until updateEndIdx.
*/
FORCE_INLINE_TEMPLATE
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
void 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)
{
U32* const hashTable = ms->hashTable;
BYTE* const tagTable = ms->tagTable;
U32 const hashLog = ms->rowHashLog;
const BYTE* const base = ms->window.base;
DEBUGLOG(6, "ZSTD_row_update_internalImpl(): updateStartIdx=%u, updateEndIdx=%u", updateStartIdx, updateEndIdx);
for (; updateStartIdx < updateEndIdx; ++updateStartIdx) {
U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, updateStartIdx, hashLog, rowLog, mls, ms->hashSalt)
: (U32)ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt);
U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog;
U32* const row = hashTable + relRow;
BYTE* tagRow = tagTable + relRow;
U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask);
assert(hash == ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt));
tagRow[pos] = hash & ZSTD_ROW_HASH_TAG_MASK;
row[pos] = updateStartIdx;
}
}
/* ZSTD_row_update_internal():
* Inserts the byte at ip into the appropriate position in the hash table, and updates ms->nextToUpdate.
* Skips sections of long matches as is necessary.
*/
FORCE_INLINE_TEMPLATE
ZSTD_ALLOW_POINTER_OVERFLOW_ATTR
void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const BYTE* ip,
U32 const mls, U32 const rowLog,
U32 const rowMask, U32 const useCache)
{
U32 idx = ms->nextToUpdate;
const BYTE* const base = ms->window.base;
const U32 target = (U32)(ip - base);
const U32 kSkipThreshold = 384;
const U32 kMaxMatchStartPositionsToUpdate = 96;
const U32 kMaxMatchEndPositionsToUpdate = 32;
if (useCache) {
/* Only skip positions when using hash cache, i.e.
* if we are loading a dict, don't skip anything.
* If we decide to skip, then we only update a set number
* of positions at the beginning and end of the match.
*/
if (UNLIKELY(target - idx > kSkipThreshold)) {
U32 const bound = idx + kMaxMatchStartPositionsToUpdate;
ZSTD_row_update_internalImpl(ms, idx, bound, mls, rowLog, rowMask, useCache);
idx = target - kMaxMatchEndPositionsToUpdate;
ZSTD_row_fillHashCache(ms, base, rowLog, mls, idx, ip+1);
}
}
assert(target >= idx);
ZSTD_row_update_internalImpl(ms, idx, target, mls, rowLog, rowMask, useCache);
ms->nextToUpdate = target;
}
/* ZSTD_row_update():
* External wrapper for ZSTD_row_update_internal(). Used for filling the hashtable during dictionary
* processing.
*/
void ZSTD_row_update(ZSTD_matchState_t* const ms, const BYTE* ip) {
const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6);
const U32 rowMask = (1u << rowLog) - 1;
const U32 mls = MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */);
DEBUGLOG(5, "ZSTD_row_update(), rowLog=%u", rowLog);
ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 0 /* don't use cache */);
}
/* Returns the mask width of bits group of which will be set to 1. Given not all
* architectures have easy movemask instruction, this helps to iterate over
* groups of bits easier and faster.
*/
FORCE_INLINE_TEMPLATE U32
ZSTD_row_matchMaskGroupWidth(const U32 rowEntries)
{
assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64);
assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES);
(void)rowEntries;
#if defined(ZSTD_ARCH_ARM_NEON)
/* NEON path only works for little endian */
if (!MEM_isLittleEndian()) {
return 1;
}
if (rowEntries == 16) {
return 4;
}
if (rowEntries == 32) {
return 2;
}
if (rowEntries == 64) {
return 1;
}
#endif
return 1;
}
#if defined(ZSTD_ARCH_X86_SSE2)
FORCE_INLINE_TEMPLATE ZSTD_VecMask
ZSTD_row_getSSEMask(int nbChunks, const BYTE* const src, const BYTE tag, const U32 head)
{
const __m128i comparisonMask = _mm_set1_epi8((char)tag);
int matches[4] = {0};
int i;
assert(nbChunks == 1 || nbChunks == 2 || nbChunks == 4);
for (i=0; i<nbChunks; i++) {
const __m128i chunk = _mm_loadu_si128((const __m128i*)(const void*)(src + 16*i));
const __m128i equalMask = _mm_cmpeq_epi8(chunk, comparisonMask);
matches[i] = _mm_movemask_epi8(equalMask);
}
if (nbChunks == 1) return ZSTD_rotateRight_U16((U16)matches[0], head);