1 /*
2 * Copyright (c) Yann Collet, Facebook, Inc.
3 * All rights reserved.
4 *
5 * This source code is licensed under both the BSD-style license (found in the
6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
7 * in the COPYING file in the root directory of this source tree).
8 * You may select, at your option, one of the above-listed licenses.
9 */
10
11 #include "zstd_compress_internal.h" /* ZSTD_hashPtr, ZSTD_count, ZSTD_storeSeq */
12 #include "zstd_fast.h"
13
14
15 void ZSTD_fillHashTable(ZSTD_matchState_t* ms,
16 const void* const end,
17 ZSTD_dictTableLoadMethod_e dtlm)
18 {
19 const ZSTD_compressionParameters* const cParams = &ms->cParams;
20 U32* const hashTable = ms->hashTable;
21 U32 const hBits = cParams->hashLog;
22 U32 const mls = cParams->minMatch;
23 const BYTE* const base = ms->window.base;
24 const BYTE* ip = base + ms->nextToUpdate;
25 const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;
26 const U32 fastHashFillStep = 3;
27
28 /* Always insert every fastHashFillStep position into the hash table.
29 * Insert the other positions if their hash entry is empty.
30 */
31 for ( ; ip + fastHashFillStep < iend + 2; ip += fastHashFillStep) {
32 U32 const curr = (U32)(ip - base);
33 size_t const hash0 = ZSTD_hashPtr(ip, hBits, mls);
34 hashTable[hash0] = curr;
35 if (dtlm == ZSTD_dtlm_fast) continue;
36 /* Only load extra positions for ZSTD_dtlm_full */
37 { U32 p;
38 for (p = 1; p < fastHashFillStep; ++p) {
39 size_t const hash = ZSTD_hashPtr(ip + p, hBits, mls);
40 if (hashTable[hash] == 0) { /* not yet filled */
41 hashTable[hash] = curr + p;
42 } } } }
43 }
44
45
46 /*
47 * If you squint hard enough (and ignore repcodes), the search operation at any
48 * given position is broken into 4 stages:
49 *
50 * 1. Hash (map position to hash value via input read)
51 * 2. Lookup (map hash val to index via hashtable read)
52 * 3. Load (map index to value at that position via input read)
53 * 4. Compare
54 *
55 * Each of these steps involves a memory read at an address which is computed
56 * from the previous step. This means these steps must be sequenced and their
57 * latencies are cumulative.
58 *
59 * Rather than do 1->2->3->4 sequentially for a single position before moving
60 * onto the next, this implementation interleaves these operations across the
61 * next few positions:
62 *
63 * R = Repcode Read & Compare
64 * H = Hash
65 * T = Table Lookup
66 * M = Match Read & Compare
67 *
68 * Pos | Time -->
69 * ----+-------------------
70 * N | ... M
71 * N+1 | ... TM
72 * N+2 | R H T M
73 * N+3 | H TM
74 * N+4 | R H T M
75 * N+5 | H ...
76 * N+6 | R ...
77 *
78 * This is very much analogous to the pipelining of execution in a CPU. And just
79 * like a CPU, we have to dump the pipeline when we find a match (i.e., take a
80 * branch).
81 *
82 * When this happens, we throw away our current state, and do the following prep
83 * to re-enter the loop:
84 *
85 * Pos | Time -->
86 * ----+-------------------
87 * N | H T
88 * N+1 | H
89 *
90 * This is also the work we do at the beginning to enter the loop initially.
91 */
92 FORCE_INLINE_TEMPLATE size_t
93 ZSTD_compressBlock_fast_noDict_generic(
94 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
95 void const* src, size_t srcSize,
96 U32 const mls, U32 const hasStep)
97 {
98 const ZSTD_compressionParameters* const cParams = &ms->cParams;
99 U32* const hashTable = ms->hashTable;
100 U32 const hlog = cParams->hashLog;
101 /* support stepSize of 0 */
102 size_t const stepSize = hasStep ? (cParams->targetLength + !(cParams->targetLength) + 1) : 2;
103 const BYTE* const base = ms->window.base;
104 const BYTE* const istart = (const BYTE*)src;
105 const U32 endIndex = (U32)((size_t)(istart - base) + srcSize);
106 const U32 prefixStartIndex = ZSTD_getLowestPrefixIndex(ms, endIndex, cParams->windowLog);
107 const BYTE* const prefixStart = base + prefixStartIndex;
108 const BYTE* const iend = istart + srcSize;
109 const BYTE* const ilimit = iend - HASH_READ_SIZE;
110
111 const BYTE* anchor = istart;
112 const BYTE* ip0 = istart;
113 const BYTE* ip1;
114 const BYTE* ip2;
115 const BYTE* ip3;
116 U32 current0;
117
118 U32 rep_offset1 = rep[0];
119 U32 rep_offset2 = rep[1];
120 U32 offsetSaved = 0;
121
122 size_t hash0; /* hash for ip0 */
123 size_t hash1; /* hash for ip1 */
124 U32 idx; /* match idx for ip0 */
125 U32 mval; /* src value at match idx */
126
127 U32 offcode;
128 const BYTE* match0;
129 size_t mLength;
130
131 /* ip0 and ip1 are always adjacent. The targetLength skipping and
132 * uncompressibility acceleration is applied to every other position,
133 * matching the behavior of #1562. step therefore represents the gap
134 * between pairs of positions, from ip0 to ip2 or ip1 to ip3. */
135 size_t step;
136 const BYTE* nextStep;
137 const size_t kStepIncr = (1 << (kSearchStrength - 1));
138
139 DEBUGLOG(5, "ZSTD_compressBlock_fast_generic");
140 ip0 += (ip0 == prefixStart);
141 { U32 const curr = (U32)(ip0 - base);
142 U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, cParams->windowLog);
143 U32 const maxRep = curr - windowLow;
144 if (rep_offset2 > maxRep) offsetSaved = rep_offset2, rep_offset2 = 0;
145 if (rep_offset1 > maxRep) offsetSaved = rep_offset1, rep_offset1 = 0;
146 }
147
148 /* start each op */
149 _start: /* Requires: ip0 */
150
151 step = stepSize;
152 nextStep = ip0 + kStepIncr;
153
154 /* calculate positions, ip0 - anchor == 0, so we skip step calc */
155 ip1 = ip0 + 1;
156 ip2 = ip0 + step;
157 ip3 = ip2 + 1;
158
159 if (ip3 >= ilimit) {
160 goto _cleanup;
161 }
162
163 hash0 = ZSTD_hashPtr(ip0, hlog, mls);
164 hash1 = ZSTD_hashPtr(ip1, hlog, mls);
165
166 idx = hashTable[hash0];
167
168 do {
169 /* load repcode match for ip[2]*/
170 const U32 rval = MEM_read32(ip2 - rep_offset1);
171
172 /* write back hash table entry */
173 current0 = (U32)(ip0 - base);
174 hashTable[hash0] = current0;
175
176 /* check repcode at ip[2] */
177 if ((MEM_read32(ip2) == rval) & (rep_offset1 > 0)) {
178 ip0 = ip2;
179 match0 = ip0 - rep_offset1;
180 mLength = ip0[-1] == match0[-1];
181 ip0 -= mLength;
182 match0 -= mLength;
183 offcode = STORE_REPCODE_1;
184 mLength += 4;
185 goto _match;
186 }
187
188 /* load match for ip[0] */
189 if (idx >= prefixStartIndex) {
190 mval = MEM_read32(base + idx);
191 } else {
192 mval = MEM_read32(ip0) ^ 1; /* guaranteed to not match. */
193 }
194
195 /* check match at ip[0] */
196 if (MEM_read32(ip0) == mval) {
197 /* found a match! */
198 goto _offset;
199 }
200
201 /* lookup ip[1] */
202 idx = hashTable[hash1];
203
204 /* hash ip[2] */
205 hash0 = hash1;
206 hash1 = ZSTD_hashPtr(ip2, hlog, mls);
207
208 /* advance to next positions */
209 ip0 = ip1;
210 ip1 = ip2;
211 ip2 = ip3;
212
213 /* write back hash table entry */
214 current0 = (U32)(ip0 - base);
215 hashTable[hash0] = current0;
216
217 /* load match for ip[0] */
218 if (idx >= prefixStartIndex) {
219 mval = MEM_read32(base + idx);
220 } else {
221 mval = MEM_read32(ip0) ^ 1; /* guaranteed to not match. */
222 }
223
224 /* check match at ip[0] */
225 if (MEM_read32(ip0) == mval) {
226 /* found a match! */
227 goto _offset;
228 }
229
230 /* lookup ip[1] */
231 idx = hashTable[hash1];
232
233 /* hash ip[2] */
234 hash0 = hash1;
235 hash1 = ZSTD_hashPtr(ip2, hlog, mls);
236
237 /* advance to next positions */
238 ip0 = ip1;
239 ip1 = ip2;
240 ip2 = ip0 + step;
241 ip3 = ip1 + step;
242
243 /* calculate step */
244 if (ip2 >= nextStep) {
245 step++;
246 PREFETCH_L1(ip1 + 64);
247 PREFETCH_L1(ip1 + 128);
248 nextStep += kStepIncr;
249 }
250 } while (ip3 < ilimit);
251
252 _cleanup:
253 /* Note that there are probably still a couple positions we could search.
254 * However, it seems to be a meaningful performance hit to try to search
255 * them. So let's not. */
256
257 /* save reps for next block */
258 rep[0] = rep_offset1 ? rep_offset1 : offsetSaved;
259 rep[1] = rep_offset2 ? rep_offset2 : offsetSaved;
260
261 /* Return the last literals size */
262 return (size_t)(iend - anchor);
263
264 _offset: /* Requires: ip0, idx */
265
266 /* Compute the offset code. */
267 match0 = base + idx;
268 rep_offset2 = rep_offset1;
269 rep_offset1 = (U32)(ip0-match0);
270 offcode = STORE_OFFSET(rep_offset1);
271 mLength = 4;
272
273 /* Count the backwards match length. */
274 while (((ip0>anchor) & (match0>prefixStart)) && (ip0[-1] == match0[-1])) {
275 ip0--;
276 match0--;
277 mLength++;
278 }
279
280 _match: /* Requires: ip0, match0, offcode */
281
282 /* Count the forward length. */
283 mLength += ZSTD_count(ip0 + mLength, match0 + mLength, iend);
284
285 ZSTD_storeSeq(seqStore, (size_t)(ip0 - anchor), anchor, iend, offcode, mLength);
286
287 ip0 += mLength;
288 anchor = ip0;
289
290 /* write next hash table entry */
291 if (ip1 < ip0) {
292 hashTable[hash1] = (U32)(ip1 - base);
293 }
294
295 /* Fill table and check for immediate repcode. */
296 if (ip0 <= ilimit) {
297 /* Fill Table */
298 assert(base+current0+2 > istart); /* check base overflow */
299 hashTable[ZSTD_hashPtr(base+current0+2, hlog, mls)] = current0+2; /* here because current+2 could be > iend-8 */
300 hashTable[ZSTD_hashPtr(ip0-2, hlog, mls)] = (U32)(ip0-2-base);
301
302 if (rep_offset2 > 0) { /* rep_offset2==0 means rep_offset2 is invalidated */
303 while ( (ip0 <= ilimit) && (MEM_read32(ip0) == MEM_read32(ip0 - rep_offset2)) ) {
304 /* store sequence */
305 size_t const rLength = ZSTD_count(ip0+4, ip0+4-rep_offset2, iend) + 4;
306 { U32 const tmpOff = rep_offset2; rep_offset2 = rep_offset1; rep_offset1 = tmpOff; } /* swap rep_offset2 <=> rep_offset1 */
307 hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = (U32)(ip0-base);
308 ip0 += rLength;
309 ZSTD_storeSeq(seqStore, 0 /*litLen*/, anchor, iend, STORE_REPCODE_1, rLength);
310 anchor = ip0;
311 continue; /* faster when present (confirmed on gcc-8) ... (?) */
312 } } }
313
314 goto _start;
315 }
316
317 #define ZSTD_GEN_FAST_FN(dictMode, mls, step) \
318 static size_t ZSTD_compressBlock_fast_##dictMode##_##mls##_##step( \
319 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], \
320 void const* src, size_t srcSize) \
321 { \
322 return ZSTD_compressBlock_fast_##dictMode##_generic(ms, seqStore, rep, src, srcSize, mls, step); \
323 }
324
325 ZSTD_GEN_FAST_FN(noDict, 4, 1)
326 ZSTD_GEN_FAST_FN(noDict, 5, 1)
327 ZSTD_GEN_FAST_FN(noDict, 6, 1)
328 ZSTD_GEN_FAST_FN(noDict, 7, 1)
329
330 ZSTD_GEN_FAST_FN(noDict, 4, 0)
331 ZSTD_GEN_FAST_FN(noDict, 5, 0)
332 ZSTD_GEN_FAST_FN(noDict, 6, 0)
333 ZSTD_GEN_FAST_FN(noDict, 7, 0)
334
335 size_t ZSTD_compressBlock_fast(
336 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
337 void const* src, size_t srcSize)
338 {
339 U32 const mls = ms->cParams.minMatch;
340 assert(ms->dictMatchState == NULL);
341 if (ms->cParams.targetLength > 1) {
342 switch(mls)
343 {
344 default: /* includes case 3 */
345 case 4 :
346 return ZSTD_compressBlock_fast_noDict_4_1(ms, seqStore, rep, src, srcSize);
347 case 5 :
348 return ZSTD_compressBlock_fast_noDict_5_1(ms, seqStore, rep, src, srcSize);
349 case 6 :
350 return ZSTD_compressBlock_fast_noDict_6_1(ms, seqStore, rep, src, srcSize);
351 case 7 :
352 return ZSTD_compressBlock_fast_noDict_7_1(ms, seqStore, rep, src, srcSize);
353 }
354 } else {
355 switch(mls)
356 {
357 default: /* includes case 3 */
358 case 4 :
359 return ZSTD_compressBlock_fast_noDict_4_0(ms, seqStore, rep, src, srcSize);
360 case 5 :
361 return ZSTD_compressBlock_fast_noDict_5_0(ms, seqStore, rep, src, srcSize);
362 case 6 :
363 return ZSTD_compressBlock_fast_noDict_6_0(ms, seqStore, rep, src, srcSize);
364 case 7 :
365 return ZSTD_compressBlock_fast_noDict_7_0(ms, seqStore, rep, src, srcSize);
366 }
367
368 }
369 }
370
371 FORCE_INLINE_TEMPLATE
372 size_t ZSTD_compressBlock_fast_dictMatchState_generic(
373 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
374 void const* src, size_t srcSize, U32 const mls, U32 const hasStep)
375 {
376 const ZSTD_compressionParameters* const cParams = &ms->cParams;
377 U32* const hashTable = ms->hashTable;
378 U32 const hlog = cParams->hashLog;
379 /* support stepSize of 0 */
380 U32 const stepSize = cParams->targetLength + !(cParams->targetLength);
381 const BYTE* const base = ms->window.base;
382 const BYTE* const istart = (const BYTE*)src;
383 const BYTE* ip = istart;
384 const BYTE* anchor = istart;
385 const U32 prefixStartIndex = ms->window.dictLimit;
386 const BYTE* const prefixStart = base + prefixStartIndex;
387 const BYTE* const iend = istart + srcSize;
388 const BYTE* const ilimit = iend - HASH_READ_SIZE;
389 U32 offset_1=rep[0], offset_2=rep[1];
390 U32 offsetSaved = 0;
391
392 const ZSTD_matchState_t* const dms = ms->dictMatchState;
393 const ZSTD_compressionParameters* const dictCParams = &dms->cParams ;
394 const U32* const dictHashTable = dms->hashTable;
395 const U32 dictStartIndex = dms->window.dictLimit;
396 const BYTE* const dictBase = dms->window.base;
397 const BYTE* const dictStart = dictBase + dictStartIndex;
398 const BYTE* const dictEnd = dms->window.nextSrc;
399 const U32 dictIndexDelta = prefixStartIndex - (U32)(dictEnd - dictBase);
400 const U32 dictAndPrefixLength = (U32)(ip - prefixStart + dictEnd - dictStart);
401 const U32 dictHLog = dictCParams->hashLog;
402
403 /* if a dictionary is still attached, it necessarily means that
404 * it is within window size. So we just check it. */
405 const U32 maxDistance = 1U << cParams->windowLog;
406 const U32 endIndex = (U32)((size_t)(ip - base) + srcSize);
407 assert(endIndex - prefixStartIndex <= maxDistance);
408 (void)maxDistance; (void)endIndex; /* these variables are not used when assert() is disabled */
409
410 (void)hasStep; /* not currently specialized on whether it's accelerated */
411
412 /* ensure there will be no underflow
413 * when translating a dict index into a local index */
414 assert(prefixStartIndex >= (U32)(dictEnd - dictBase));
415
416 /* init */
417 DEBUGLOG(5, "ZSTD_compressBlock_fast_dictMatchState_generic");
418 ip += (dictAndPrefixLength == 0);
419 /* dictMatchState repCode checks don't currently handle repCode == 0
420 * disabling. */
421 assert(offset_1 <= dictAndPrefixLength);
422 assert(offset_2 <= dictAndPrefixLength);
423
424 /* Main Search Loop */
425 while (ip < ilimit) { /* < instead of <=, because repcode check at (ip+1) */
426 size_t mLength;
427 size_t const h = ZSTD_hashPtr(ip, hlog, mls);
428 U32 const curr = (U32)(ip-base);
429 U32 const matchIndex = hashTable[h];
430 const BYTE* match = base + matchIndex;
431 const U32 repIndex = curr + 1 - offset_1;
432 const BYTE* repMatch = (repIndex < prefixStartIndex) ?
433 dictBase + (repIndex - dictIndexDelta) :
434 base + repIndex;
435 hashTable[h] = curr; /* update hash table */
436
437 if ( ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow : ensure repIndex isn't overlapping dict + prefix */
438 && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
439 const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
440 mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixStart) + 4;
441 ip++;
442 ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, STORE_REPCODE_1, mLength);
443 } else if ( (matchIndex <= prefixStartIndex) ) {
444 size_t const dictHash = ZSTD_hashPtr(ip, dictHLog, mls);
445 U32 const dictMatchIndex = dictHashTable[dictHash];
446 const BYTE* dictMatch = dictBase + dictMatchIndex;
447 if (dictMatchIndex <= dictStartIndex ||
448 MEM_read32(dictMatch) != MEM_read32(ip)) {
449 assert(stepSize >= 1);
450 ip += ((ip-anchor) >> kSearchStrength) + stepSize;
451 continue;
452 } else {
453 /* found a dict match */
454 U32 const offset = (U32)(curr-dictMatchIndex-dictIndexDelta);
455 mLength = ZSTD_count_2segments(ip+4, dictMatch+4, iend, dictEnd, prefixStart) + 4;
456 while (((ip>anchor) & (dictMatch>dictStart))
457 && (ip[-1] == dictMatch[-1])) {
458 ip--; dictMatch--; mLength++;
459 } /* catch up */
460 offset_2 = offset_1;
461 offset_1 = offset;
462 ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, STORE_OFFSET(offset), mLength);
463 }
464 } else if (MEM_read32(match) != MEM_read32(ip)) {
465 /* it's not a match, and we're not going to check the dictionary */
466 assert(stepSize >= 1);
467 ip += ((ip-anchor) >> kSearchStrength) + stepSize;
468 continue;
469 } else {
470 /* found a regular match */
471 U32 const offset = (U32)(ip-match);
472 mLength = ZSTD_count(ip+4, match+4, iend) + 4;
473 while (((ip>anchor) & (match>prefixStart))
474 && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
475 offset_2 = offset_1;
476 offset_1 = offset;
477 ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, STORE_OFFSET(offset), mLength);
478 }
479
480 /* match found */
481 ip += mLength;
482 anchor = ip;
483
484 if (ip <= ilimit) {
485 /* Fill Table */
486 assert(base+curr+2 > istart); /* check base overflow */
487 hashTable[ZSTD_hashPtr(base+curr+2, hlog, mls)] = curr+2; /* here because curr+2 could be > iend-8 */
488 hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);
489
490 /* check immediate repcode */
491 while (ip <= ilimit) {
492 U32 const current2 = (U32)(ip-base);
493 U32 const repIndex2 = current2 - offset_2;
494 const BYTE* repMatch2 = repIndex2 < prefixStartIndex ?
495 dictBase - dictIndexDelta + repIndex2 :
496 base + repIndex2;
497 if ( ((U32)((prefixStartIndex-1) - (U32)repIndex2) >= 3 /* intentional overflow */)
498 && (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
499 const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
500 size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
501 U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; /* swap offset_2 <=> offset_1 */
502 ZSTD_storeSeq(seqStore, 0, anchor, iend, STORE_REPCODE_1, repLength2);
503 hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
504 ip += repLength2;
505 anchor = ip;
506 continue;
507 }
508 break;
509 }
510 }
511 }
512
513 /* save reps for next block */
514 rep[0] = offset_1 ? offset_1 : offsetSaved;
515 rep[1] = offset_2 ? offset_2 : offsetSaved;
516
517 /* Return the last literals size */
518 return (size_t)(iend - anchor);
519 }
520
521
522 ZSTD_GEN_FAST_FN(dictMatchState, 4, 0)
523 ZSTD_GEN_FAST_FN(dictMatchState, 5, 0)
524 ZSTD_GEN_FAST_FN(dictMatchState, 6, 0)
525 ZSTD_GEN_FAST_FN(dictMatchState, 7, 0)
526
527 size_t ZSTD_compressBlock_fast_dictMatchState(
528 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
529 void const* src, size_t srcSize)
530 {
531 U32 const mls = ms->cParams.minMatch;
532 assert(ms->dictMatchState != NULL);
533 switch(mls)
534 {
535 default: /* includes case 3 */
536 case 4 :
537 return ZSTD_compressBlock_fast_dictMatchState_4_0(ms, seqStore, rep, src, srcSize);
538 case 5 :
539 return ZSTD_compressBlock_fast_dictMatchState_5_0(ms, seqStore, rep, src, srcSize);
540 case 6 :
541 return ZSTD_compressBlock_fast_dictMatchState_6_0(ms, seqStore, rep, src, srcSize);
542 case 7 :
543 return ZSTD_compressBlock_fast_dictMatchState_7_0(ms, seqStore, rep, src, srcSize);
544 }
545 }
546
547
548 static size_t ZSTD_compressBlock_fast_extDict_generic(
549 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
550 void const* src, size_t srcSize, U32 const mls, U32 const hasStep)
551 {
552 const ZSTD_compressionParameters* const cParams = &ms->cParams;
553 U32* const hashTable = ms->hashTable;
554 U32 const hlog = cParams->hashLog;
555 /* support stepSize of 0 */
556 U32 const stepSize = cParams->targetLength + !(cParams->targetLength);
557 const BYTE* const base = ms->window.base;
558 const BYTE* const dictBase = ms->window.dictBase;
559 const BYTE* const istart = (const BYTE*)src;
560 const BYTE* ip = istart;
561 const BYTE* anchor = istart;
562 const U32 endIndex = (U32)((size_t)(istart - base) + srcSize);
563 const U32 lowLimit = ZSTD_getLowestMatchIndex(ms, endIndex, cParams->windowLog);
564 const U32 dictStartIndex = lowLimit;
565 const BYTE* const dictStart = dictBase + dictStartIndex;
566 const U32 dictLimit = ms->window.dictLimit;
567 const U32 prefixStartIndex = dictLimit < lowLimit ? lowLimit : dictLimit;
568 const BYTE* const prefixStart = base + prefixStartIndex;
569 const BYTE* const dictEnd = dictBase + prefixStartIndex;
570 const BYTE* const iend = istart + srcSize;
571 const BYTE* const ilimit = iend - 8;
572 U32 offset_1=rep[0], offset_2=rep[1];
573
574 (void)hasStep; /* not currently specialized on whether it's accelerated */
575
576 DEBUGLOG(5, "ZSTD_compressBlock_fast_extDict_generic (offset_1=%u)", offset_1);
577
578 /* switch to "regular" variant if extDict is invalidated due to maxDistance */
579 if (prefixStartIndex == dictStartIndex)
580 return ZSTD_compressBlock_fast(ms, seqStore, rep, src, srcSize);
581
582 /* Search Loop */
583 while (ip < ilimit) { /* < instead of <=, because (ip+1) */
584 const size_t h = ZSTD_hashPtr(ip, hlog, mls);
585 const U32 matchIndex = hashTable[h];
586 const BYTE* const matchBase = matchIndex < prefixStartIndex ? dictBase : base;
587 const BYTE* match = matchBase + matchIndex;
588 const U32 curr = (U32)(ip-base);
589 const U32 repIndex = curr + 1 - offset_1;
590 const BYTE* const repBase = repIndex < prefixStartIndex ? dictBase : base;
591 const BYTE* const repMatch = repBase + repIndex;
592 hashTable[h] = curr; /* update hash table */
593 DEBUGLOG(7, "offset_1 = %u , curr = %u", offset_1, curr);
594
595 if ( ( ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow */
596 & (offset_1 <= curr+1 - dictStartIndex) ) /* note: we are searching at curr+1 */
597 && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {
598 const BYTE* const repMatchEnd = repIndex < prefixStartIndex ? dictEnd : iend;
599 size_t const rLength = ZSTD_count_2segments(ip+1 +4, repMatch +4, iend, repMatchEnd, prefixStart) + 4;
600 ip++;
601 ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, STORE_REPCODE_1, rLength);
602 ip += rLength;
603 anchor = ip;
604 } else {
605 if ( (matchIndex < dictStartIndex) ||
606 (MEM_read32(match) != MEM_read32(ip)) ) {
607 assert(stepSize >= 1);
608 ip += ((ip-anchor) >> kSearchStrength) + stepSize;
609 continue;
610 }
611 { const BYTE* const matchEnd = matchIndex < prefixStartIndex ? dictEnd : iend;
612 const BYTE* const lowMatchPtr = matchIndex < prefixStartIndex ? dictStart : prefixStart;
613 U32 const offset = curr - matchIndex;
614 size_t mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, prefixStart) + 4;
615 while (((ip>anchor) & (match>lowMatchPtr)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */
616 offset_2 = offset_1; offset_1 = offset; /* update offset history */
617 ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, STORE_OFFSET(offset), mLength);
618 ip += mLength;
619 anchor = ip;
620 } }
621
622 if (ip <= ilimit) {
623 /* Fill Table */
624 hashTable[ZSTD_hashPtr(base+curr+2, hlog, mls)] = curr+2;
625 hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);
626 /* check immediate repcode */
627 while (ip <= ilimit) {
628 U32 const current2 = (U32)(ip-base);
629 U32 const repIndex2 = current2 - offset_2;
630 const BYTE* const repMatch2 = repIndex2 < prefixStartIndex ? dictBase + repIndex2 : base + repIndex2;
631 if ( (((U32)((prefixStartIndex-1) - repIndex2) >= 3) & (offset_2 <= curr - dictStartIndex)) /* intentional overflow */
632 && (MEM_read32(repMatch2) == MEM_read32(ip)) ) {
633 const BYTE* const repEnd2 = repIndex2 < prefixStartIndex ? dictEnd : iend;
634 size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixStart) + 4;
635 { U32 const tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; } /* swap offset_2 <=> offset_1 */
636 ZSTD_storeSeq(seqStore, 0 /*litlen*/, anchor, iend, STORE_REPCODE_1, repLength2);
637 hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;
638 ip += repLength2;
639 anchor = ip;
640 continue;
641 }
642 break;
643 } } }
644
645 /* save reps for next block */
646 rep[0] = offset_1;
647 rep[1] = offset_2;
648
649 /* Return the last literals size */
650 return (size_t)(iend - anchor);
651 }
652
653 ZSTD_GEN_FAST_FN(extDict, 4, 0)
654 ZSTD_GEN_FAST_FN(extDict, 5, 0)
655 ZSTD_GEN_FAST_FN(extDict, 6, 0)
656 ZSTD_GEN_FAST_FN(extDict, 7, 0)
657
658 size_t ZSTD_compressBlock_fast_extDict(
659 ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],
660 void const* src, size_t srcSize)
661 {
662 U32 const mls = ms->cParams.minMatch;
663 switch(mls)
664 {
665 default: /* includes case 3 */
666 case 4 :
667 return ZSTD_compressBlock_fast_extDict_4_0(ms, seqStore, rep, src, srcSize);
668 case 5 :
669 return ZSTD_compressBlock_fast_extDict_5_0(ms, seqStore, rep, src, srcSize);
670 case 6 :
671 return ZSTD_compressBlock_fast_extDict_6_0(ms, seqStore, rep, src, srcSize);
672 case 7 :
673 return ZSTD_compressBlock_fast_extDict_7_0(ms, seqStore, rep, src, srcSize);
674 }
675 }
676
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