648db22b |
1 | /* |
2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
3 | * All rights reserved. |
4 | * |
5 | * This source code is licensed under both the BSD-style license (found in the |
6 | * LICENSE file in the root directory of this source tree) and the GPLv2 (found |
7 | * in the COPYING file in the root directory of this source tree). |
8 | * You may select, at your option, one of the above-listed licenses. |
9 | */ |
10 | |
11 | #include "zstd_compress_internal.h" |
12 | #include "zstd_lazy.h" |
13 | #include "../common/bits.h" /* ZSTD_countTrailingZeros64 */ |
14 | |
f535537f |
15 | #if !defined(ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR) \ |
16 | || !defined(ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR) \ |
17 | || !defined(ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR) \ |
18 | || !defined(ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR) |
19 | |
648db22b |
20 | #define kLazySkippingStep 8 |
21 | |
22 | |
23 | /*-************************************* |
24 | * Binary Tree search |
25 | ***************************************/ |
26 | |
f535537f |
27 | static |
28 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
29 | void ZSTD_updateDUBT(ZSTD_matchState_t* ms, |
648db22b |
30 | const BYTE* ip, const BYTE* iend, |
31 | U32 mls) |
32 | { |
33 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
34 | U32* const hashTable = ms->hashTable; |
35 | U32 const hashLog = cParams->hashLog; |
36 | |
37 | U32* const bt = ms->chainTable; |
38 | U32 const btLog = cParams->chainLog - 1; |
39 | U32 const btMask = (1 << btLog) - 1; |
40 | |
41 | const BYTE* const base = ms->window.base; |
42 | U32 const target = (U32)(ip - base); |
43 | U32 idx = ms->nextToUpdate; |
44 | |
45 | if (idx != target) |
46 | DEBUGLOG(7, "ZSTD_updateDUBT, from %u to %u (dictLimit:%u)", |
47 | idx, target, ms->window.dictLimit); |
48 | assert(ip + 8 <= iend); /* condition for ZSTD_hashPtr */ |
49 | (void)iend; |
50 | |
51 | assert(idx >= ms->window.dictLimit); /* condition for valid base+idx */ |
52 | for ( ; idx < target ; idx++) { |
53 | size_t const h = ZSTD_hashPtr(base + idx, hashLog, mls); /* assumption : ip + 8 <= iend */ |
54 | U32 const matchIndex = hashTable[h]; |
55 | |
56 | U32* const nextCandidatePtr = bt + 2*(idx&btMask); |
57 | U32* const sortMarkPtr = nextCandidatePtr + 1; |
58 | |
59 | DEBUGLOG(8, "ZSTD_updateDUBT: insert %u", idx); |
60 | hashTable[h] = idx; /* Update Hash Table */ |
61 | *nextCandidatePtr = matchIndex; /* update BT like a chain */ |
62 | *sortMarkPtr = ZSTD_DUBT_UNSORTED_MARK; |
63 | } |
64 | ms->nextToUpdate = target; |
65 | } |
66 | |
67 | |
68 | /** ZSTD_insertDUBT1() : |
69 | * sort one already inserted but unsorted position |
70 | * assumption : curr >= btlow == (curr - btmask) |
71 | * doesn't fail */ |
f535537f |
72 | static |
73 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
74 | void ZSTD_insertDUBT1(const ZSTD_matchState_t* ms, |
648db22b |
75 | U32 curr, const BYTE* inputEnd, |
76 | U32 nbCompares, U32 btLow, |
77 | const ZSTD_dictMode_e dictMode) |
78 | { |
79 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
80 | U32* const bt = ms->chainTable; |
81 | U32 const btLog = cParams->chainLog - 1; |
82 | U32 const btMask = (1 << btLog) - 1; |
83 | size_t commonLengthSmaller=0, commonLengthLarger=0; |
84 | const BYTE* const base = ms->window.base; |
85 | const BYTE* const dictBase = ms->window.dictBase; |
86 | const U32 dictLimit = ms->window.dictLimit; |
87 | const BYTE* const ip = (curr>=dictLimit) ? base + curr : dictBase + curr; |
88 | const BYTE* const iend = (curr>=dictLimit) ? inputEnd : dictBase + dictLimit; |
89 | const BYTE* const dictEnd = dictBase + dictLimit; |
90 | const BYTE* const prefixStart = base + dictLimit; |
91 | const BYTE* match; |
92 | U32* smallerPtr = bt + 2*(curr&btMask); |
93 | U32* largerPtr = smallerPtr + 1; |
94 | 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) */ |
95 | U32 dummy32; /* to be nullified at the end */ |
96 | U32 const windowValid = ms->window.lowLimit; |
97 | U32 const maxDistance = 1U << cParams->windowLog; |
98 | U32 const windowLow = (curr - windowValid > maxDistance) ? curr - maxDistance : windowValid; |
99 | |
100 | |
101 | DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)", |
102 | curr, dictLimit, windowLow); |
103 | assert(curr >= btLow); |
104 | assert(ip < iend); /* condition for ZSTD_count */ |
105 | |
106 | for (; nbCompares && (matchIndex > windowLow); --nbCompares) { |
107 | U32* const nextPtr = bt + 2*(matchIndex & btMask); |
108 | size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ |
109 | assert(matchIndex < curr); |
110 | /* note : all candidates are now supposed sorted, |
111 | * but it's still possible to have nextPtr[1] == ZSTD_DUBT_UNSORTED_MARK |
112 | * when a real index has the same value as ZSTD_DUBT_UNSORTED_MARK */ |
113 | |
114 | if ( (dictMode != ZSTD_extDict) |
115 | || (matchIndex+matchLength >= dictLimit) /* both in current segment*/ |
116 | || (curr < dictLimit) /* both in extDict */) { |
117 | const BYTE* const mBase = ( (dictMode != ZSTD_extDict) |
118 | || (matchIndex+matchLength >= dictLimit)) ? |
119 | base : dictBase; |
120 | assert( (matchIndex+matchLength >= dictLimit) /* might be wrong if extDict is incorrectly set to 0 */ |
121 | || (curr < dictLimit) ); |
122 | match = mBase + matchIndex; |
123 | matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); |
124 | } else { |
125 | match = dictBase + matchIndex; |
126 | matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); |
127 | if (matchIndex+matchLength >= dictLimit) |
128 | match = base + matchIndex; /* preparation for next read of match[matchLength] */ |
129 | } |
130 | |
131 | DEBUGLOG(8, "ZSTD_insertDUBT1: comparing %u with %u : found %u common bytes ", |
132 | curr, matchIndex, (U32)matchLength); |
133 | |
134 | if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ |
135 | break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree */ |
136 | } |
137 | |
138 | if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */ |
139 | /* match is smaller than current */ |
140 | *smallerPtr = matchIndex; /* update smaller idx */ |
141 | commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ |
142 | if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop searching */ |
143 | DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is smaller : next => %u", |
144 | matchIndex, btLow, nextPtr[1]); |
145 | smallerPtr = nextPtr+1; /* new "candidate" => larger than match, which was smaller than target */ |
146 | matchIndex = nextPtr[1]; /* new matchIndex, larger than previous and closer to current */ |
147 | } else { |
148 | /* match is larger than current */ |
149 | *largerPtr = matchIndex; |
150 | commonLengthLarger = matchLength; |
151 | if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop searching */ |
152 | DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is larger => %u", |
153 | matchIndex, btLow, nextPtr[0]); |
154 | largerPtr = nextPtr; |
155 | matchIndex = nextPtr[0]; |
156 | } } |
157 | |
158 | *smallerPtr = *largerPtr = 0; |
159 | } |
160 | |
161 | |
f535537f |
162 | static |
163 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
164 | size_t ZSTD_DUBT_findBetterDictMatch ( |
648db22b |
165 | const ZSTD_matchState_t* ms, |
166 | const BYTE* const ip, const BYTE* const iend, |
167 | size_t* offsetPtr, |
168 | size_t bestLength, |
169 | U32 nbCompares, |
170 | U32 const mls, |
171 | const ZSTD_dictMode_e dictMode) |
172 | { |
173 | const ZSTD_matchState_t * const dms = ms->dictMatchState; |
174 | const ZSTD_compressionParameters* const dmsCParams = &dms->cParams; |
175 | const U32 * const dictHashTable = dms->hashTable; |
176 | U32 const hashLog = dmsCParams->hashLog; |
177 | size_t const h = ZSTD_hashPtr(ip, hashLog, mls); |
178 | U32 dictMatchIndex = dictHashTable[h]; |
179 | |
180 | const BYTE* const base = ms->window.base; |
181 | const BYTE* const prefixStart = base + ms->window.dictLimit; |
182 | U32 const curr = (U32)(ip-base); |
183 | const BYTE* const dictBase = dms->window.base; |
184 | const BYTE* const dictEnd = dms->window.nextSrc; |
185 | U32 const dictHighLimit = (U32)(dms->window.nextSrc - dms->window.base); |
186 | U32 const dictLowLimit = dms->window.lowLimit; |
187 | U32 const dictIndexDelta = ms->window.lowLimit - dictHighLimit; |
188 | |
189 | U32* const dictBt = dms->chainTable; |
190 | U32 const btLog = dmsCParams->chainLog - 1; |
191 | U32 const btMask = (1 << btLog) - 1; |
192 | U32 const btLow = (btMask >= dictHighLimit - dictLowLimit) ? dictLowLimit : dictHighLimit - btMask; |
193 | |
194 | size_t commonLengthSmaller=0, commonLengthLarger=0; |
195 | |
196 | (void)dictMode; |
197 | assert(dictMode == ZSTD_dictMatchState); |
198 | |
199 | for (; nbCompares && (dictMatchIndex > dictLowLimit); --nbCompares) { |
200 | U32* const nextPtr = dictBt + 2*(dictMatchIndex & btMask); |
201 | size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ |
202 | const BYTE* match = dictBase + dictMatchIndex; |
203 | matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); |
204 | if (dictMatchIndex+matchLength >= dictHighLimit) |
205 | match = base + dictMatchIndex + dictIndexDelta; /* to prepare for next usage of match[matchLength] */ |
206 | |
207 | if (matchLength > bestLength) { |
208 | U32 matchIndex = dictMatchIndex + dictIndexDelta; |
209 | if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr-matchIndex+1) - ZSTD_highbit32((U32)offsetPtr[0]+1)) ) { |
210 | DEBUGLOG(9, "ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> %u (dictMatchIndex %u, matchIndex %u)", |
211 | curr, (U32)bestLength, (U32)matchLength, (U32)*offsetPtr, OFFSET_TO_OFFBASE(curr - matchIndex), dictMatchIndex, matchIndex); |
212 | bestLength = matchLength, *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex); |
213 | } |
214 | 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 */ |
215 | break; /* drop, to guarantee consistency (miss a little bit of compression) */ |
216 | } |
217 | } |
218 | |
219 | if (match[matchLength] < ip[matchLength]) { |
220 | if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */ |
221 | commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ |
222 | dictMatchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ |
223 | } else { |
224 | /* match is larger than current */ |
225 | if (dictMatchIndex <= btLow) { break; } /* beyond tree size, stop the search */ |
226 | commonLengthLarger = matchLength; |
227 | dictMatchIndex = nextPtr[0]; |
228 | } |
229 | } |
230 | |
231 | if (bestLength >= MINMATCH) { |
232 | U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offsetPtr); (void)mIndex; |
233 | DEBUGLOG(8, "ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)", |
234 | curr, (U32)bestLength, (U32)*offsetPtr, mIndex); |
235 | } |
236 | return bestLength; |
237 | |
238 | } |
239 | |
240 | |
f535537f |
241 | static |
242 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
243 | size_t ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms, |
648db22b |
244 | const BYTE* const ip, const BYTE* const iend, |
245 | size_t* offBasePtr, |
246 | U32 const mls, |
247 | const ZSTD_dictMode_e dictMode) |
248 | { |
249 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
250 | U32* const hashTable = ms->hashTable; |
251 | U32 const hashLog = cParams->hashLog; |
252 | size_t const h = ZSTD_hashPtr(ip, hashLog, mls); |
253 | U32 matchIndex = hashTable[h]; |
254 | |
255 | const BYTE* const base = ms->window.base; |
256 | U32 const curr = (U32)(ip-base); |
257 | U32 const windowLow = ZSTD_getLowestMatchIndex(ms, curr, cParams->windowLog); |
258 | |
259 | U32* const bt = ms->chainTable; |
260 | U32 const btLog = cParams->chainLog - 1; |
261 | U32 const btMask = (1 << btLog) - 1; |
262 | U32 const btLow = (btMask >= curr) ? 0 : curr - btMask; |
263 | U32 const unsortLimit = MAX(btLow, windowLow); |
264 | |
265 | U32* nextCandidate = bt + 2*(matchIndex&btMask); |
266 | U32* unsortedMark = bt + 2*(matchIndex&btMask) + 1; |
267 | U32 nbCompares = 1U << cParams->searchLog; |
268 | U32 nbCandidates = nbCompares; |
269 | U32 previousCandidate = 0; |
270 | |
271 | DEBUGLOG(7, "ZSTD_DUBT_findBestMatch (%u) ", curr); |
272 | assert(ip <= iend-8); /* required for h calculation */ |
273 | assert(dictMode != ZSTD_dedicatedDictSearch); |
274 | |
275 | /* reach end of unsorted candidates list */ |
276 | while ( (matchIndex > unsortLimit) |
277 | && (*unsortedMark == ZSTD_DUBT_UNSORTED_MARK) |
278 | && (nbCandidates > 1) ) { |
279 | DEBUGLOG(8, "ZSTD_DUBT_findBestMatch: candidate %u is unsorted", |
280 | matchIndex); |
281 | *unsortedMark = previousCandidate; /* the unsortedMark becomes a reversed chain, to move up back to original position */ |
282 | previousCandidate = matchIndex; |
283 | matchIndex = *nextCandidate; |
284 | nextCandidate = bt + 2*(matchIndex&btMask); |
285 | unsortedMark = bt + 2*(matchIndex&btMask) + 1; |
286 | nbCandidates --; |
287 | } |
288 | |
289 | /* nullify last candidate if it's still unsorted |
290 | * simplification, detrimental to compression ratio, beneficial for speed */ |
291 | if ( (matchIndex > unsortLimit) |
292 | && (*unsortedMark==ZSTD_DUBT_UNSORTED_MARK) ) { |
293 | DEBUGLOG(7, "ZSTD_DUBT_findBestMatch: nullify last unsorted candidate %u", |
294 | matchIndex); |
295 | *nextCandidate = *unsortedMark = 0; |
296 | } |
297 | |
298 | /* batch sort stacked candidates */ |
299 | matchIndex = previousCandidate; |
300 | while (matchIndex) { /* will end on matchIndex == 0 */ |
301 | U32* const nextCandidateIdxPtr = bt + 2*(matchIndex&btMask) + 1; |
302 | U32 const nextCandidateIdx = *nextCandidateIdxPtr; |
303 | ZSTD_insertDUBT1(ms, matchIndex, iend, |
304 | nbCandidates, unsortLimit, dictMode); |
305 | matchIndex = nextCandidateIdx; |
306 | nbCandidates++; |
307 | } |
308 | |
309 | /* find longest match */ |
310 | { size_t commonLengthSmaller = 0, commonLengthLarger = 0; |
311 | const BYTE* const dictBase = ms->window.dictBase; |
312 | const U32 dictLimit = ms->window.dictLimit; |
313 | const BYTE* const dictEnd = dictBase + dictLimit; |
314 | const BYTE* const prefixStart = base + dictLimit; |
315 | U32* smallerPtr = bt + 2*(curr&btMask); |
316 | U32* largerPtr = bt + 2*(curr&btMask) + 1; |
317 | U32 matchEndIdx = curr + 8 + 1; |
318 | U32 dummy32; /* to be nullified at the end */ |
319 | size_t bestLength = 0; |
320 | |
321 | matchIndex = hashTable[h]; |
322 | hashTable[h] = curr; /* Update Hash Table */ |
323 | |
324 | for (; nbCompares && (matchIndex > windowLow); --nbCompares) { |
325 | U32* const nextPtr = bt + 2*(matchIndex & btMask); |
326 | size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */ |
327 | const BYTE* match; |
328 | |
329 | if ((dictMode != ZSTD_extDict) || (matchIndex+matchLength >= dictLimit)) { |
330 | match = base + matchIndex; |
331 | matchLength += ZSTD_count(ip+matchLength, match+matchLength, iend); |
332 | } else { |
333 | match = dictBase + matchIndex; |
334 | matchLength += ZSTD_count_2segments(ip+matchLength, match+matchLength, iend, dictEnd, prefixStart); |
335 | if (matchIndex+matchLength >= dictLimit) |
336 | match = base + matchIndex; /* to prepare for next usage of match[matchLength] */ |
337 | } |
338 | |
339 | if (matchLength > bestLength) { |
340 | if (matchLength > matchEndIdx - matchIndex) |
341 | matchEndIdx = matchIndex + (U32)matchLength; |
342 | if ( (4*(int)(matchLength-bestLength)) > (int)(ZSTD_highbit32(curr - matchIndex + 1) - ZSTD_highbit32((U32)*offBasePtr)) ) |
343 | bestLength = matchLength, *offBasePtr = OFFSET_TO_OFFBASE(curr - matchIndex); |
344 | if (ip+matchLength == iend) { /* equal : no way to know if inf or sup */ |
345 | if (dictMode == ZSTD_dictMatchState) { |
346 | nbCompares = 0; /* in addition to avoiding checking any |
347 | * further in this loop, make sure we |
348 | * skip checking in the dictionary. */ |
349 | } |
350 | break; /* drop, to guarantee consistency (miss a little bit of compression) */ |
351 | } |
352 | } |
353 | |
354 | if (match[matchLength] < ip[matchLength]) { |
355 | /* match is smaller than current */ |
356 | *smallerPtr = matchIndex; /* update smaller idx */ |
357 | commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */ |
358 | if (matchIndex <= btLow) { smallerPtr=&dummy32; break; } /* beyond tree size, stop the search */ |
359 | smallerPtr = nextPtr+1; /* new "smaller" => larger of match */ |
360 | matchIndex = nextPtr[1]; /* new matchIndex larger than previous (closer to current) */ |
361 | } else { |
362 | /* match is larger than current */ |
363 | *largerPtr = matchIndex; |
364 | commonLengthLarger = matchLength; |
365 | if (matchIndex <= btLow) { largerPtr=&dummy32; break; } /* beyond tree size, stop the search */ |
366 | largerPtr = nextPtr; |
367 | matchIndex = nextPtr[0]; |
368 | } } |
369 | |
370 | *smallerPtr = *largerPtr = 0; |
371 | |
372 | assert(nbCompares <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ |
373 | if (dictMode == ZSTD_dictMatchState && nbCompares) { |
374 | bestLength = ZSTD_DUBT_findBetterDictMatch( |
375 | ms, ip, iend, |
376 | offBasePtr, bestLength, nbCompares, |
377 | mls, dictMode); |
378 | } |
379 | |
380 | assert(matchEndIdx > curr+8); /* ensure nextToUpdate is increased */ |
381 | ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */ |
382 | if (bestLength >= MINMATCH) { |
383 | U32 const mIndex = curr - (U32)OFFBASE_TO_OFFSET(*offBasePtr); (void)mIndex; |
384 | DEBUGLOG(8, "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)", |
385 | curr, (U32)bestLength, (U32)*offBasePtr, mIndex); |
386 | } |
387 | return bestLength; |
388 | } |
389 | } |
390 | |
391 | |
392 | /** ZSTD_BtFindBestMatch() : Tree updater, providing best match */ |
f535537f |
393 | FORCE_INLINE_TEMPLATE |
394 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
395 | size_t ZSTD_BtFindBestMatch( ZSTD_matchState_t* ms, |
648db22b |
396 | const BYTE* const ip, const BYTE* const iLimit, |
397 | size_t* offBasePtr, |
398 | const U32 mls /* template */, |
399 | const ZSTD_dictMode_e dictMode) |
400 | { |
401 | DEBUGLOG(7, "ZSTD_BtFindBestMatch"); |
402 | if (ip < ms->window.base + ms->nextToUpdate) return 0; /* skipped area */ |
403 | ZSTD_updateDUBT(ms, ip, iLimit, mls); |
404 | return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offBasePtr, mls, dictMode); |
405 | } |
406 | |
407 | /*********************************** |
408 | * Dedicated dict search |
409 | ***********************************/ |
410 | |
411 | void ZSTD_dedicatedDictSearch_lazy_loadDictionary(ZSTD_matchState_t* ms, const BYTE* const ip) |
412 | { |
413 | const BYTE* const base = ms->window.base; |
414 | U32 const target = (U32)(ip - base); |
415 | U32* const hashTable = ms->hashTable; |
416 | U32* const chainTable = ms->chainTable; |
417 | U32 const chainSize = 1 << ms->cParams.chainLog; |
418 | U32 idx = ms->nextToUpdate; |
419 | U32 const minChain = chainSize < target - idx ? target - chainSize : idx; |
420 | U32 const bucketSize = 1 << ZSTD_LAZY_DDSS_BUCKET_LOG; |
421 | U32 const cacheSize = bucketSize - 1; |
422 | U32 const chainAttempts = (1 << ms->cParams.searchLog) - cacheSize; |
423 | U32 const chainLimit = chainAttempts > 255 ? 255 : chainAttempts; |
424 | |
425 | /* We know the hashtable is oversized by a factor of `bucketSize`. |
426 | * We are going to temporarily pretend `bucketSize == 1`, keeping only a |
427 | * single entry. We will use the rest of the space to construct a temporary |
428 | * chaintable. |
429 | */ |
430 | U32 const hashLog = ms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG; |
431 | U32* const tmpHashTable = hashTable; |
432 | U32* const tmpChainTable = hashTable + ((size_t)1 << hashLog); |
433 | U32 const tmpChainSize = (U32)((1 << ZSTD_LAZY_DDSS_BUCKET_LOG) - 1) << hashLog; |
434 | U32 const tmpMinChain = tmpChainSize < target ? target - tmpChainSize : idx; |
435 | U32 hashIdx; |
436 | |
437 | assert(ms->cParams.chainLog <= 24); |
438 | assert(ms->cParams.hashLog > ms->cParams.chainLog); |
439 | assert(idx != 0); |
440 | assert(tmpMinChain <= minChain); |
441 | |
442 | /* fill conventional hash table and conventional chain table */ |
443 | for ( ; idx < target; idx++) { |
444 | U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch); |
445 | if (idx >= tmpMinChain) { |
446 | tmpChainTable[idx - tmpMinChain] = hashTable[h]; |
447 | } |
448 | tmpHashTable[h] = idx; |
449 | } |
450 | |
451 | /* sort chains into ddss chain table */ |
452 | { |
453 | U32 chainPos = 0; |
454 | for (hashIdx = 0; hashIdx < (1U << hashLog); hashIdx++) { |
455 | U32 count; |
456 | U32 countBeyondMinChain = 0; |
457 | U32 i = tmpHashTable[hashIdx]; |
458 | for (count = 0; i >= tmpMinChain && count < cacheSize; count++) { |
459 | /* skip through the chain to the first position that won't be |
460 | * in the hash cache bucket */ |
461 | if (i < minChain) { |
462 | countBeyondMinChain++; |
463 | } |
464 | i = tmpChainTable[i - tmpMinChain]; |
465 | } |
466 | if (count == cacheSize) { |
467 | for (count = 0; count < chainLimit;) { |
468 | if (i < minChain) { |
469 | if (!i || ++countBeyondMinChain > cacheSize) { |
470 | /* only allow pulling `cacheSize` number of entries |
471 | * into the cache or chainTable beyond `minChain`, |
472 | * to replace the entries pulled out of the |
473 | * chainTable into the cache. This lets us reach |
474 | * back further without increasing the total number |
475 | * of entries in the chainTable, guaranteeing the |
476 | * DDSS chain table will fit into the space |
477 | * allocated for the regular one. */ |
478 | break; |
479 | } |
480 | } |
481 | chainTable[chainPos++] = i; |
482 | count++; |
483 | if (i < tmpMinChain) { |
484 | break; |
485 | } |
486 | i = tmpChainTable[i - tmpMinChain]; |
487 | } |
488 | } else { |
489 | count = 0; |
490 | } |
491 | if (count) { |
492 | tmpHashTable[hashIdx] = ((chainPos - count) << 8) + count; |
493 | } else { |
494 | tmpHashTable[hashIdx] = 0; |
495 | } |
496 | } |
497 | assert(chainPos <= chainSize); /* I believe this is guaranteed... */ |
498 | } |
499 | |
500 | /* move chain pointers into the last entry of each hash bucket */ |
501 | for (hashIdx = (1 << hashLog); hashIdx; ) { |
502 | U32 const bucketIdx = --hashIdx << ZSTD_LAZY_DDSS_BUCKET_LOG; |
503 | U32 const chainPackedPointer = tmpHashTable[hashIdx]; |
504 | U32 i; |
505 | for (i = 0; i < cacheSize; i++) { |
506 | hashTable[bucketIdx + i] = 0; |
507 | } |
508 | hashTable[bucketIdx + bucketSize - 1] = chainPackedPointer; |
509 | } |
510 | |
511 | /* fill the buckets of the hash table */ |
512 | for (idx = ms->nextToUpdate; idx < target; idx++) { |
513 | U32 const h = (U32)ZSTD_hashPtr(base + idx, hashLog, ms->cParams.minMatch) |
514 | << ZSTD_LAZY_DDSS_BUCKET_LOG; |
515 | U32 i; |
516 | /* Shift hash cache down 1. */ |
517 | for (i = cacheSize - 1; i; i--) |
518 | hashTable[h + i] = hashTable[h + i - 1]; |
519 | hashTable[h] = idx; |
520 | } |
521 | |
522 | ms->nextToUpdate = target; |
523 | } |
524 | |
525 | /* Returns the longest match length found in the dedicated dict search structure. |
526 | * If none are longer than the argument ml, then ml will be returned. |
527 | */ |
528 | FORCE_INLINE_TEMPLATE |
529 | size_t ZSTD_dedicatedDictSearch_lazy_search(size_t* offsetPtr, size_t ml, U32 nbAttempts, |
530 | const ZSTD_matchState_t* const dms, |
531 | const BYTE* const ip, const BYTE* const iLimit, |
532 | const BYTE* const prefixStart, const U32 curr, |
533 | const U32 dictLimit, const size_t ddsIdx) { |
534 | const U32 ddsLowestIndex = dms->window.dictLimit; |
535 | const BYTE* const ddsBase = dms->window.base; |
536 | const BYTE* const ddsEnd = dms->window.nextSrc; |
537 | const U32 ddsSize = (U32)(ddsEnd - ddsBase); |
538 | const U32 ddsIndexDelta = dictLimit - ddsSize; |
539 | const U32 bucketSize = (1 << ZSTD_LAZY_DDSS_BUCKET_LOG); |
540 | const U32 bucketLimit = nbAttempts < bucketSize - 1 ? nbAttempts : bucketSize - 1; |
541 | U32 ddsAttempt; |
542 | U32 matchIndex; |
543 | |
544 | for (ddsAttempt = 0; ddsAttempt < bucketSize - 1; ddsAttempt++) { |
545 | PREFETCH_L1(ddsBase + dms->hashTable[ddsIdx + ddsAttempt]); |
546 | } |
547 | |
548 | { |
549 | U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1]; |
550 | U32 const chainIndex = chainPackedPointer >> 8; |
551 | |
552 | PREFETCH_L1(&dms->chainTable[chainIndex]); |
553 | } |
554 | |
555 | for (ddsAttempt = 0; ddsAttempt < bucketLimit; ddsAttempt++) { |
556 | size_t currentMl=0; |
557 | const BYTE* match; |
558 | matchIndex = dms->hashTable[ddsIdx + ddsAttempt]; |
559 | match = ddsBase + matchIndex; |
560 | |
561 | if (!matchIndex) { |
562 | return ml; |
563 | } |
564 | |
565 | /* guaranteed by table construction */ |
566 | (void)ddsLowestIndex; |
567 | assert(matchIndex >= ddsLowestIndex); |
568 | assert(match+4 <= ddsEnd); |
569 | if (MEM_read32(match) == MEM_read32(ip)) { |
570 | /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
571 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4; |
572 | } |
573 | |
574 | /* save best solution */ |
575 | if (currentMl > ml) { |
576 | ml = currentMl; |
577 | *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta)); |
578 | if (ip+currentMl == iLimit) { |
579 | /* best possible, avoids read overflow on next attempt */ |
580 | return ml; |
581 | } |
582 | } |
583 | } |
584 | |
585 | { |
586 | U32 const chainPackedPointer = dms->hashTable[ddsIdx + bucketSize - 1]; |
587 | U32 chainIndex = chainPackedPointer >> 8; |
588 | U32 const chainLength = chainPackedPointer & 0xFF; |
589 | U32 const chainAttempts = nbAttempts - ddsAttempt; |
590 | U32 const chainLimit = chainAttempts > chainLength ? chainLength : chainAttempts; |
591 | U32 chainAttempt; |
592 | |
593 | for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++) { |
594 | PREFETCH_L1(ddsBase + dms->chainTable[chainIndex + chainAttempt]); |
595 | } |
596 | |
597 | for (chainAttempt = 0 ; chainAttempt < chainLimit; chainAttempt++, chainIndex++) { |
598 | size_t currentMl=0; |
599 | const BYTE* match; |
600 | matchIndex = dms->chainTable[chainIndex]; |
601 | match = ddsBase + matchIndex; |
602 | |
603 | /* guaranteed by table construction */ |
604 | assert(matchIndex >= ddsLowestIndex); |
605 | assert(match+4 <= ddsEnd); |
606 | if (MEM_read32(match) == MEM_read32(ip)) { |
607 | /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
608 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, ddsEnd, prefixStart) + 4; |
609 | } |
610 | |
611 | /* save best solution */ |
612 | if (currentMl > ml) { |
613 | ml = currentMl; |
614 | *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + ddsIndexDelta)); |
615 | if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ |
616 | } |
617 | } |
618 | } |
619 | return ml; |
620 | } |
621 | |
622 | |
623 | /* ********************************* |
624 | * Hash Chain |
625 | ***********************************/ |
626 | #define NEXT_IN_CHAIN(d, mask) chainTable[(d) & (mask)] |
627 | |
628 | /* Update chains up to ip (excluded) |
629 | Assumption : always within prefix (i.e. not within extDict) */ |
f535537f |
630 | FORCE_INLINE_TEMPLATE |
631 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
632 | U32 ZSTD_insertAndFindFirstIndex_internal( |
648db22b |
633 | ZSTD_matchState_t* ms, |
634 | const ZSTD_compressionParameters* const cParams, |
635 | const BYTE* ip, U32 const mls, U32 const lazySkipping) |
636 | { |
637 | U32* const hashTable = ms->hashTable; |
638 | const U32 hashLog = cParams->hashLog; |
639 | U32* const chainTable = ms->chainTable; |
640 | const U32 chainMask = (1 << cParams->chainLog) - 1; |
641 | const BYTE* const base = ms->window.base; |
642 | const U32 target = (U32)(ip - base); |
643 | U32 idx = ms->nextToUpdate; |
644 | |
645 | while(idx < target) { /* catch up */ |
646 | size_t const h = ZSTD_hashPtr(base+idx, hashLog, mls); |
647 | NEXT_IN_CHAIN(idx, chainMask) = hashTable[h]; |
648 | hashTable[h] = idx; |
649 | idx++; |
650 | /* Stop inserting every position when in the lazy skipping mode. */ |
651 | if (lazySkipping) |
652 | break; |
653 | } |
654 | |
655 | ms->nextToUpdate = target; |
656 | return hashTable[ZSTD_hashPtr(ip, hashLog, mls)]; |
657 | } |
658 | |
659 | U32 ZSTD_insertAndFindFirstIndex(ZSTD_matchState_t* ms, const BYTE* ip) { |
660 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
661 | return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, ms->cParams.minMatch, /* lazySkipping*/ 0); |
662 | } |
663 | |
664 | /* inlining is important to hardwire a hot branch (template emulation) */ |
665 | FORCE_INLINE_TEMPLATE |
f535537f |
666 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
648db22b |
667 | size_t ZSTD_HcFindBestMatch( |
668 | ZSTD_matchState_t* ms, |
669 | const BYTE* const ip, const BYTE* const iLimit, |
670 | size_t* offsetPtr, |
671 | const U32 mls, const ZSTD_dictMode_e dictMode) |
672 | { |
673 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
674 | U32* const chainTable = ms->chainTable; |
675 | const U32 chainSize = (1 << cParams->chainLog); |
676 | const U32 chainMask = chainSize-1; |
677 | const BYTE* const base = ms->window.base; |
678 | const BYTE* const dictBase = ms->window.dictBase; |
679 | const U32 dictLimit = ms->window.dictLimit; |
680 | const BYTE* const prefixStart = base + dictLimit; |
681 | const BYTE* const dictEnd = dictBase + dictLimit; |
682 | const U32 curr = (U32)(ip-base); |
683 | const U32 maxDistance = 1U << cParams->windowLog; |
684 | const U32 lowestValid = ms->window.lowLimit; |
685 | const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid; |
686 | const U32 isDictionary = (ms->loadedDictEnd != 0); |
687 | const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance; |
688 | const U32 minChain = curr > chainSize ? curr - chainSize : 0; |
689 | U32 nbAttempts = 1U << cParams->searchLog; |
690 | size_t ml=4-1; |
691 | |
692 | const ZSTD_matchState_t* const dms = ms->dictMatchState; |
693 | const U32 ddsHashLog = dictMode == ZSTD_dedicatedDictSearch |
694 | ? dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG : 0; |
695 | const size_t ddsIdx = dictMode == ZSTD_dedicatedDictSearch |
696 | ? ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG : 0; |
697 | |
698 | U32 matchIndex; |
699 | |
700 | if (dictMode == ZSTD_dedicatedDictSearch) { |
701 | const U32* entry = &dms->hashTable[ddsIdx]; |
702 | PREFETCH_L1(entry); |
703 | } |
704 | |
705 | /* HC4 match finder */ |
706 | matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls, ms->lazySkipping); |
707 | |
708 | for ( ; (matchIndex>=lowLimit) & (nbAttempts>0) ; nbAttempts--) { |
709 | size_t currentMl=0; |
710 | if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { |
711 | const BYTE* const match = base + matchIndex; |
712 | assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */ |
713 | /* read 4B starting from (match + ml + 1 - sizeof(U32)) */ |
714 | if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */ |
715 | currentMl = ZSTD_count(ip, match, iLimit); |
716 | } else { |
717 | const BYTE* const match = dictBase + matchIndex; |
718 | assert(match+4 <= dictEnd); |
719 | if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
720 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4; |
721 | } |
722 | |
723 | /* save best solution */ |
724 | if (currentMl > ml) { |
725 | ml = currentMl; |
726 | *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex); |
727 | if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ |
728 | } |
729 | |
730 | if (matchIndex <= minChain) break; |
731 | matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask); |
732 | } |
733 | |
734 | assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ |
735 | if (dictMode == ZSTD_dedicatedDictSearch) { |
736 | ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts, dms, |
737 | ip, iLimit, prefixStart, curr, dictLimit, ddsIdx); |
738 | } else if (dictMode == ZSTD_dictMatchState) { |
739 | const U32* const dmsChainTable = dms->chainTable; |
740 | const U32 dmsChainSize = (1 << dms->cParams.chainLog); |
741 | const U32 dmsChainMask = dmsChainSize - 1; |
742 | const U32 dmsLowestIndex = dms->window.dictLimit; |
743 | const BYTE* const dmsBase = dms->window.base; |
744 | const BYTE* const dmsEnd = dms->window.nextSrc; |
745 | const U32 dmsSize = (U32)(dmsEnd - dmsBase); |
746 | const U32 dmsIndexDelta = dictLimit - dmsSize; |
747 | const U32 dmsMinChain = dmsSize > dmsChainSize ? dmsSize - dmsChainSize : 0; |
748 | |
749 | matchIndex = dms->hashTable[ZSTD_hashPtr(ip, dms->cParams.hashLog, mls)]; |
750 | |
751 | for ( ; (matchIndex>=dmsLowestIndex) & (nbAttempts>0) ; nbAttempts--) { |
752 | size_t currentMl=0; |
753 | const BYTE* const match = dmsBase + matchIndex; |
754 | assert(match+4 <= dmsEnd); |
755 | if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
756 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4; |
757 | |
758 | /* save best solution */ |
759 | if (currentMl > ml) { |
760 | ml = currentMl; |
761 | assert(curr > matchIndex + dmsIndexDelta); |
762 | *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta)); |
763 | if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ |
764 | } |
765 | |
766 | if (matchIndex <= dmsMinChain) break; |
767 | |
768 | matchIndex = dmsChainTable[matchIndex & dmsChainMask]; |
769 | } |
770 | } |
771 | |
772 | return ml; |
773 | } |
774 | |
775 | /* ********************************* |
776 | * (SIMD) Row-based matchfinder |
777 | ***********************************/ |
778 | /* Constants for row-based hash */ |
779 | #define ZSTD_ROW_HASH_TAG_MASK ((1u << ZSTD_ROW_HASH_TAG_BITS) - 1) |
780 | #define ZSTD_ROW_HASH_MAX_ENTRIES 64 /* absolute maximum number of entries per row, for all configurations */ |
781 | |
782 | #define ZSTD_ROW_HASH_CACHE_MASK (ZSTD_ROW_HASH_CACHE_SIZE - 1) |
783 | |
784 | typedef U64 ZSTD_VecMask; /* Clarifies when we are interacting with a U64 representing a mask of matches */ |
785 | |
786 | /* ZSTD_VecMask_next(): |
787 | * Starting from the LSB, returns the idx of the next non-zero bit. |
788 | * Basically counting the nb of trailing zeroes. |
789 | */ |
790 | MEM_STATIC U32 ZSTD_VecMask_next(ZSTD_VecMask val) { |
791 | return ZSTD_countTrailingZeros64(val); |
792 | } |
793 | |
794 | /* ZSTD_row_nextIndex(): |
795 | * Returns the next index to insert at within a tagTable row, and updates the "head" |
796 | * value to reflect the update. Essentially cycles backwards from [1, {entries per row}) |
797 | */ |
798 | FORCE_INLINE_TEMPLATE U32 ZSTD_row_nextIndex(BYTE* const tagRow, U32 const rowMask) { |
799 | U32 next = (*tagRow-1) & rowMask; |
800 | next += (next == 0) ? rowMask : 0; /* skip first position */ |
801 | *tagRow = (BYTE)next; |
802 | return next; |
803 | } |
804 | |
805 | /* ZSTD_isAligned(): |
806 | * Checks that a pointer is aligned to "align" bytes which must be a power of 2. |
807 | */ |
808 | MEM_STATIC int ZSTD_isAligned(void const* ptr, size_t align) { |
809 | assert((align & (align - 1)) == 0); |
810 | return (((size_t)ptr) & (align - 1)) == 0; |
811 | } |
812 | |
813 | /* ZSTD_row_prefetch(): |
814 | * Performs prefetching for the hashTable and tagTable at a given row. |
815 | */ |
816 | FORCE_INLINE_TEMPLATE void ZSTD_row_prefetch(U32 const* hashTable, BYTE const* tagTable, U32 const relRow, U32 const rowLog) { |
817 | PREFETCH_L1(hashTable + relRow); |
818 | if (rowLog >= 5) { |
819 | PREFETCH_L1(hashTable + relRow + 16); |
820 | /* Note: prefetching more of the hash table does not appear to be beneficial for 128-entry rows */ |
821 | } |
822 | PREFETCH_L1(tagTable + relRow); |
823 | if (rowLog == 6) { |
824 | PREFETCH_L1(tagTable + relRow + 32); |
825 | } |
826 | assert(rowLog == 4 || rowLog == 5 || rowLog == 6); |
827 | assert(ZSTD_isAligned(hashTable + relRow, 64)); /* prefetched hash row always 64-byte aligned */ |
828 | assert(ZSTD_isAligned(tagTable + relRow, (size_t)1 << rowLog)); /* prefetched tagRow sits on correct multiple of bytes (32,64,128) */ |
829 | } |
830 | |
831 | /* ZSTD_row_fillHashCache(): |
832 | * Fill up the hash cache starting at idx, prefetching up to ZSTD_ROW_HASH_CACHE_SIZE entries, |
833 | * but not beyond iLimit. |
834 | */ |
f535537f |
835 | FORCE_INLINE_TEMPLATE |
836 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
837 | void ZSTD_row_fillHashCache(ZSTD_matchState_t* ms, const BYTE* base, |
648db22b |
838 | U32 const rowLog, U32 const mls, |
839 | U32 idx, const BYTE* const iLimit) |
840 | { |
841 | U32 const* const hashTable = ms->hashTable; |
842 | BYTE const* const tagTable = ms->tagTable; |
843 | U32 const hashLog = ms->rowHashLog; |
844 | U32 const maxElemsToPrefetch = (base + idx) > iLimit ? 0 : (U32)(iLimit - (base + idx) + 1); |
845 | U32 const lim = idx + MIN(ZSTD_ROW_HASH_CACHE_SIZE, maxElemsToPrefetch); |
846 | |
847 | for (; idx < lim; ++idx) { |
848 | U32 const hash = (U32)ZSTD_hashPtrSalted(base + idx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt); |
849 | U32 const row = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
850 | ZSTD_row_prefetch(hashTable, tagTable, row, rowLog); |
851 | ms->hashCache[idx & ZSTD_ROW_HASH_CACHE_MASK] = hash; |
852 | } |
853 | |
854 | DEBUGLOG(6, "ZSTD_row_fillHashCache(): [%u %u %u %u %u %u %u %u]", ms->hashCache[0], ms->hashCache[1], |
855 | ms->hashCache[2], ms->hashCache[3], ms->hashCache[4], |
856 | ms->hashCache[5], ms->hashCache[6], ms->hashCache[7]); |
857 | } |
858 | |
859 | /* ZSTD_row_nextCachedHash(): |
860 | * Returns the hash of base + idx, and replaces the hash in the hash cache with the byte at |
861 | * base + idx + ZSTD_ROW_HASH_CACHE_SIZE. Also prefetches the appropriate rows from hashTable and tagTable. |
862 | */ |
f535537f |
863 | FORCE_INLINE_TEMPLATE |
864 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
865 | U32 ZSTD_row_nextCachedHash(U32* cache, U32 const* hashTable, |
648db22b |
866 | BYTE const* tagTable, BYTE const* base, |
867 | U32 idx, U32 const hashLog, |
868 | U32 const rowLog, U32 const mls, |
869 | U64 const hashSalt) |
870 | { |
871 | U32 const newHash = (U32)ZSTD_hashPtrSalted(base+idx+ZSTD_ROW_HASH_CACHE_SIZE, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt); |
872 | U32 const row = (newHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
873 | ZSTD_row_prefetch(hashTable, tagTable, row, rowLog); |
874 | { U32 const hash = cache[idx & ZSTD_ROW_HASH_CACHE_MASK]; |
875 | cache[idx & ZSTD_ROW_HASH_CACHE_MASK] = newHash; |
876 | return hash; |
877 | } |
878 | } |
879 | |
880 | /* ZSTD_row_update_internalImpl(): |
881 | * Updates the hash table with positions starting from updateStartIdx until updateEndIdx. |
882 | */ |
f535537f |
883 | FORCE_INLINE_TEMPLATE |
884 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
885 | void ZSTD_row_update_internalImpl(ZSTD_matchState_t* ms, |
886 | U32 updateStartIdx, U32 const updateEndIdx, |
887 | U32 const mls, U32 const rowLog, |
888 | U32 const rowMask, U32 const useCache) |
648db22b |
889 | { |
890 | U32* const hashTable = ms->hashTable; |
891 | BYTE* const tagTable = ms->tagTable; |
892 | U32 const hashLog = ms->rowHashLog; |
893 | const BYTE* const base = ms->window.base; |
894 | |
895 | DEBUGLOG(6, "ZSTD_row_update_internalImpl(): updateStartIdx=%u, updateEndIdx=%u", updateStartIdx, updateEndIdx); |
896 | for (; updateStartIdx < updateEndIdx; ++updateStartIdx) { |
897 | U32 const hash = useCache ? ZSTD_row_nextCachedHash(ms->hashCache, hashTable, tagTable, base, updateStartIdx, hashLog, rowLog, mls, ms->hashSalt) |
898 | : (U32)ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt); |
899 | U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
900 | U32* const row = hashTable + relRow; |
901 | BYTE* tagRow = tagTable + relRow; |
902 | U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask); |
903 | |
904 | assert(hash == ZSTD_hashPtrSalted(base + updateStartIdx, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, ms->hashSalt)); |
905 | tagRow[pos] = hash & ZSTD_ROW_HASH_TAG_MASK; |
906 | row[pos] = updateStartIdx; |
907 | } |
908 | } |
909 | |
910 | /* ZSTD_row_update_internal(): |
911 | * Inserts the byte at ip into the appropriate position in the hash table, and updates ms->nextToUpdate. |
912 | * Skips sections of long matches as is necessary. |
913 | */ |
f535537f |
914 | FORCE_INLINE_TEMPLATE |
915 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
916 | void ZSTD_row_update_internal(ZSTD_matchState_t* ms, const BYTE* ip, |
917 | U32 const mls, U32 const rowLog, |
918 | U32 const rowMask, U32 const useCache) |
648db22b |
919 | { |
920 | U32 idx = ms->nextToUpdate; |
921 | const BYTE* const base = ms->window.base; |
922 | const U32 target = (U32)(ip - base); |
923 | const U32 kSkipThreshold = 384; |
924 | const U32 kMaxMatchStartPositionsToUpdate = 96; |
925 | const U32 kMaxMatchEndPositionsToUpdate = 32; |
926 | |
927 | if (useCache) { |
928 | /* Only skip positions when using hash cache, i.e. |
929 | * if we are loading a dict, don't skip anything. |
930 | * If we decide to skip, then we only update a set number |
931 | * of positions at the beginning and end of the match. |
932 | */ |
933 | if (UNLIKELY(target - idx > kSkipThreshold)) { |
934 | U32 const bound = idx + kMaxMatchStartPositionsToUpdate; |
935 | ZSTD_row_update_internalImpl(ms, idx, bound, mls, rowLog, rowMask, useCache); |
936 | idx = target - kMaxMatchEndPositionsToUpdate; |
937 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, idx, ip+1); |
938 | } |
939 | } |
940 | assert(target >= idx); |
941 | ZSTD_row_update_internalImpl(ms, idx, target, mls, rowLog, rowMask, useCache); |
942 | ms->nextToUpdate = target; |
943 | } |
944 | |
945 | /* ZSTD_row_update(): |
946 | * External wrapper for ZSTD_row_update_internal(). Used for filling the hashtable during dictionary |
947 | * processing. |
948 | */ |
949 | void ZSTD_row_update(ZSTD_matchState_t* const ms, const BYTE* ip) { |
950 | const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); |
951 | const U32 rowMask = (1u << rowLog) - 1; |
952 | const U32 mls = MIN(ms->cParams.minMatch, 6 /* mls caps out at 6 */); |
953 | |
954 | DEBUGLOG(5, "ZSTD_row_update(), rowLog=%u", rowLog); |
955 | ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 0 /* don't use cache */); |
956 | } |
957 | |
958 | /* Returns the mask width of bits group of which will be set to 1. Given not all |
959 | * architectures have easy movemask instruction, this helps to iterate over |
960 | * groups of bits easier and faster. |
961 | */ |
962 | FORCE_INLINE_TEMPLATE U32 |
963 | ZSTD_row_matchMaskGroupWidth(const U32 rowEntries) |
964 | { |
965 | assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64); |
966 | assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES); |
967 | (void)rowEntries; |
968 | #if defined(ZSTD_ARCH_ARM_NEON) |
969 | /* NEON path only works for little endian */ |
970 | if (!MEM_isLittleEndian()) { |
971 | return 1; |
972 | } |
973 | if (rowEntries == 16) { |
974 | return 4; |
975 | } |
976 | if (rowEntries == 32) { |
977 | return 2; |
978 | } |
979 | if (rowEntries == 64) { |
980 | return 1; |
981 | } |
982 | #endif |
983 | return 1; |
984 | } |
985 | |
986 | #if defined(ZSTD_ARCH_X86_SSE2) |
987 | FORCE_INLINE_TEMPLATE ZSTD_VecMask |
988 | ZSTD_row_getSSEMask(int nbChunks, const BYTE* const src, const BYTE tag, const U32 head) |
989 | { |
990 | const __m128i comparisonMask = _mm_set1_epi8((char)tag); |
991 | int matches[4] = {0}; |
992 | int i; |
993 | assert(nbChunks == 1 || nbChunks == 2 || nbChunks == 4); |
994 | for (i=0; i<nbChunks; i++) { |
995 | const __m128i chunk = _mm_loadu_si128((const __m128i*)(const void*)(src + 16*i)); |
996 | const __m128i equalMask = _mm_cmpeq_epi8(chunk, comparisonMask); |
997 | matches[i] = _mm_movemask_epi8(equalMask); |
998 | } |
999 | if (nbChunks == 1) return ZSTD_rotateRight_U16((U16)matches[0], head); |
1000 | if (nbChunks == 2) return ZSTD_rotateRight_U32((U32)matches[1] << 16 | (U32)matches[0], head); |
1001 | assert(nbChunks == 4); |
1002 | return ZSTD_rotateRight_U64((U64)matches[3] << 48 | (U64)matches[2] << 32 | (U64)matches[1] << 16 | (U64)matches[0], head); |
1003 | } |
1004 | #endif |
1005 | |
1006 | #if defined(ZSTD_ARCH_ARM_NEON) |
1007 | FORCE_INLINE_TEMPLATE ZSTD_VecMask |
1008 | ZSTD_row_getNEONMask(const U32 rowEntries, const BYTE* const src, const BYTE tag, const U32 headGrouped) |
1009 | { |
1010 | assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64); |
1011 | if (rowEntries == 16) { |
1012 | /* vshrn_n_u16 shifts by 4 every u16 and narrows to 8 lower bits. |
1013 | * After that groups of 4 bits represent the equalMask. We lower |
1014 | * all bits except the highest in these groups by doing AND with |
1015 | * 0x88 = 0b10001000. |
1016 | */ |
1017 | const uint8x16_t chunk = vld1q_u8(src); |
1018 | const uint16x8_t equalMask = vreinterpretq_u16_u8(vceqq_u8(chunk, vdupq_n_u8(tag))); |
1019 | const uint8x8_t res = vshrn_n_u16(equalMask, 4); |
1020 | const U64 matches = vget_lane_u64(vreinterpret_u64_u8(res), 0); |
1021 | return ZSTD_rotateRight_U64(matches, headGrouped) & 0x8888888888888888ull; |
1022 | } else if (rowEntries == 32) { |
1023 | /* Same idea as with rowEntries == 16 but doing AND with |
1024 | * 0x55 = 0b01010101. |
1025 | */ |
1026 | const uint16x8x2_t chunk = vld2q_u16((const uint16_t*)(const void*)src); |
1027 | const uint8x16_t chunk0 = vreinterpretq_u8_u16(chunk.val[0]); |
1028 | const uint8x16_t chunk1 = vreinterpretq_u8_u16(chunk.val[1]); |
1029 | const uint8x16_t dup = vdupq_n_u8(tag); |
1030 | const uint8x8_t t0 = vshrn_n_u16(vreinterpretq_u16_u8(vceqq_u8(chunk0, dup)), 6); |
1031 | const uint8x8_t t1 = vshrn_n_u16(vreinterpretq_u16_u8(vceqq_u8(chunk1, dup)), 6); |
1032 | const uint8x8_t res = vsli_n_u8(t0, t1, 4); |
1033 | const U64 matches = vget_lane_u64(vreinterpret_u64_u8(res), 0) ; |
1034 | return ZSTD_rotateRight_U64(matches, headGrouped) & 0x5555555555555555ull; |
1035 | } else { /* rowEntries == 64 */ |
1036 | const uint8x16x4_t chunk = vld4q_u8(src); |
1037 | const uint8x16_t dup = vdupq_n_u8(tag); |
1038 | const uint8x16_t cmp0 = vceqq_u8(chunk.val[0], dup); |
1039 | const uint8x16_t cmp1 = vceqq_u8(chunk.val[1], dup); |
1040 | const uint8x16_t cmp2 = vceqq_u8(chunk.val[2], dup); |
1041 | const uint8x16_t cmp3 = vceqq_u8(chunk.val[3], dup); |
1042 | |
1043 | const uint8x16_t t0 = vsriq_n_u8(cmp1, cmp0, 1); |
1044 | const uint8x16_t t1 = vsriq_n_u8(cmp3, cmp2, 1); |
1045 | const uint8x16_t t2 = vsriq_n_u8(t1, t0, 2); |
1046 | const uint8x16_t t3 = vsriq_n_u8(t2, t2, 4); |
1047 | const uint8x8_t t4 = vshrn_n_u16(vreinterpretq_u16_u8(t3), 4); |
1048 | const U64 matches = vget_lane_u64(vreinterpret_u64_u8(t4), 0); |
1049 | return ZSTD_rotateRight_U64(matches, headGrouped); |
1050 | } |
1051 | } |
1052 | #endif |
1053 | |
1054 | /* Returns a ZSTD_VecMask (U64) that has the nth group (determined by |
1055 | * ZSTD_row_matchMaskGroupWidth) of bits set to 1 if the newly-computed "tag" |
1056 | * matches the hash at the nth position in a row of the tagTable. |
1057 | * Each row is a circular buffer beginning at the value of "headGrouped". So we |
1058 | * must rotate the "matches" bitfield to match up with the actual layout of the |
1059 | * entries within the hashTable */ |
1060 | FORCE_INLINE_TEMPLATE ZSTD_VecMask |
1061 | ZSTD_row_getMatchMask(const BYTE* const tagRow, const BYTE tag, const U32 headGrouped, const U32 rowEntries) |
1062 | { |
1063 | const BYTE* const src = tagRow; |
1064 | assert((rowEntries == 16) || (rowEntries == 32) || rowEntries == 64); |
1065 | assert(rowEntries <= ZSTD_ROW_HASH_MAX_ENTRIES); |
1066 | assert(ZSTD_row_matchMaskGroupWidth(rowEntries) * rowEntries <= sizeof(ZSTD_VecMask) * 8); |
1067 | |
1068 | #if defined(ZSTD_ARCH_X86_SSE2) |
1069 | |
1070 | return ZSTD_row_getSSEMask(rowEntries / 16, src, tag, headGrouped); |
1071 | |
1072 | #else /* SW or NEON-LE */ |
1073 | |
1074 | # if defined(ZSTD_ARCH_ARM_NEON) |
1075 | /* This NEON path only works for little endian - otherwise use SWAR below */ |
1076 | if (MEM_isLittleEndian()) { |
1077 | return ZSTD_row_getNEONMask(rowEntries, src, tag, headGrouped); |
1078 | } |
1079 | # endif /* ZSTD_ARCH_ARM_NEON */ |
1080 | /* SWAR */ |
1081 | { const int chunkSize = sizeof(size_t); |
1082 | const size_t shiftAmount = ((chunkSize * 8) - chunkSize); |
1083 | const size_t xFF = ~((size_t)0); |
1084 | const size_t x01 = xFF / 0xFF; |
1085 | const size_t x80 = x01 << 7; |
1086 | const size_t splatChar = tag * x01; |
1087 | ZSTD_VecMask matches = 0; |
1088 | int i = rowEntries - chunkSize; |
1089 | assert((sizeof(size_t) == 4) || (sizeof(size_t) == 8)); |
1090 | if (MEM_isLittleEndian()) { /* runtime check so have two loops */ |
1091 | const size_t extractMagic = (xFF / 0x7F) >> chunkSize; |
1092 | do { |
1093 | size_t chunk = MEM_readST(&src[i]); |
1094 | chunk ^= splatChar; |
1095 | chunk = (((chunk | x80) - x01) | chunk) & x80; |
1096 | matches <<= chunkSize; |
1097 | matches |= (chunk * extractMagic) >> shiftAmount; |
1098 | i -= chunkSize; |
1099 | } while (i >= 0); |
1100 | } else { /* big endian: reverse bits during extraction */ |
1101 | const size_t msb = xFF ^ (xFF >> 1); |
1102 | const size_t extractMagic = (msb / 0x1FF) | msb; |
1103 | do { |
1104 | size_t chunk = MEM_readST(&src[i]); |
1105 | chunk ^= splatChar; |
1106 | chunk = (((chunk | x80) - x01) | chunk) & x80; |
1107 | matches <<= chunkSize; |
1108 | matches |= ((chunk >> 7) * extractMagic) >> shiftAmount; |
1109 | i -= chunkSize; |
1110 | } while (i >= 0); |
1111 | } |
1112 | matches = ~matches; |
1113 | if (rowEntries == 16) { |
1114 | return ZSTD_rotateRight_U16((U16)matches, headGrouped); |
1115 | } else if (rowEntries == 32) { |
1116 | return ZSTD_rotateRight_U32((U32)matches, headGrouped); |
1117 | } else { |
1118 | return ZSTD_rotateRight_U64((U64)matches, headGrouped); |
1119 | } |
1120 | } |
1121 | #endif |
1122 | } |
1123 | |
1124 | /* The high-level approach of the SIMD row based match finder is as follows: |
1125 | * - Figure out where to insert the new entry: |
f535537f |
1126 | * - Generate a hash for current input posistion and split it into a one byte of tag and `rowHashLog` bits of index. |
1127 | * - The hash is salted by a value that changes on every contex reset, so when the same table is used |
1128 | * we will avoid collisions that would otherwise slow us down by intorducing phantom matches. |
1129 | * - The hashTable is effectively split into groups or "rows" of 15 or 31 entries of U32, and the index determines |
648db22b |
1130 | * which row to insert into. |
f535537f |
1131 | * - Determine the correct position within the row to insert the entry into. Each row of 15 or 31 can |
1132 | * be considered as a circular buffer with a "head" index that resides in the tagTable (overall 16 or 32 bytes |
1133 | * per row). |
1134 | * - Use SIMD to efficiently compare the tags in the tagTable to the 1-byte tag calculated for the position and |
648db22b |
1135 | * generate a bitfield that we can cycle through to check the collisions in the hash table. |
1136 | * - Pick the longest match. |
f535537f |
1137 | * - Insert the tag into the equivalent row and position in the tagTable. |
648db22b |
1138 | */ |
1139 | FORCE_INLINE_TEMPLATE |
f535537f |
1140 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
648db22b |
1141 | size_t ZSTD_RowFindBestMatch( |
1142 | ZSTD_matchState_t* ms, |
1143 | const BYTE* const ip, const BYTE* const iLimit, |
1144 | size_t* offsetPtr, |
1145 | const U32 mls, const ZSTD_dictMode_e dictMode, |
1146 | const U32 rowLog) |
1147 | { |
1148 | U32* const hashTable = ms->hashTable; |
1149 | BYTE* const tagTable = ms->tagTable; |
1150 | U32* const hashCache = ms->hashCache; |
1151 | const U32 hashLog = ms->rowHashLog; |
1152 | const ZSTD_compressionParameters* const cParams = &ms->cParams; |
1153 | const BYTE* const base = ms->window.base; |
1154 | const BYTE* const dictBase = ms->window.dictBase; |
1155 | const U32 dictLimit = ms->window.dictLimit; |
1156 | const BYTE* const prefixStart = base + dictLimit; |
1157 | const BYTE* const dictEnd = dictBase + dictLimit; |
1158 | const U32 curr = (U32)(ip-base); |
1159 | const U32 maxDistance = 1U << cParams->windowLog; |
1160 | const U32 lowestValid = ms->window.lowLimit; |
1161 | const U32 withinMaxDistance = (curr - lowestValid > maxDistance) ? curr - maxDistance : lowestValid; |
1162 | const U32 isDictionary = (ms->loadedDictEnd != 0); |
1163 | const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance; |
1164 | const U32 rowEntries = (1U << rowLog); |
1165 | const U32 rowMask = rowEntries - 1; |
1166 | const U32 cappedSearchLog = MIN(cParams->searchLog, rowLog); /* nb of searches is capped at nb entries per row */ |
1167 | const U32 groupWidth = ZSTD_row_matchMaskGroupWidth(rowEntries); |
1168 | const U64 hashSalt = ms->hashSalt; |
1169 | U32 nbAttempts = 1U << cappedSearchLog; |
1170 | size_t ml=4-1; |
1171 | U32 hash; |
1172 | |
1173 | /* DMS/DDS variables that may be referenced laster */ |
1174 | const ZSTD_matchState_t* const dms = ms->dictMatchState; |
1175 | |
1176 | /* Initialize the following variables to satisfy static analyzer */ |
1177 | size_t ddsIdx = 0; |
1178 | U32 ddsExtraAttempts = 0; /* cctx hash tables are limited in searches, but allow extra searches into DDS */ |
1179 | U32 dmsTag = 0; |
1180 | U32* dmsRow = NULL; |
1181 | BYTE* dmsTagRow = NULL; |
1182 | |
1183 | if (dictMode == ZSTD_dedicatedDictSearch) { |
1184 | const U32 ddsHashLog = dms->cParams.hashLog - ZSTD_LAZY_DDSS_BUCKET_LOG; |
1185 | { /* Prefetch DDS hashtable entry */ |
1186 | ddsIdx = ZSTD_hashPtr(ip, ddsHashLog, mls) << ZSTD_LAZY_DDSS_BUCKET_LOG; |
1187 | PREFETCH_L1(&dms->hashTable[ddsIdx]); |
1188 | } |
1189 | ddsExtraAttempts = cParams->searchLog > rowLog ? 1U << (cParams->searchLog - rowLog) : 0; |
1190 | } |
1191 | |
1192 | if (dictMode == ZSTD_dictMatchState) { |
1193 | /* Prefetch DMS rows */ |
1194 | U32* const dmsHashTable = dms->hashTable; |
1195 | BYTE* const dmsTagTable = dms->tagTable; |
1196 | U32 const dmsHash = (U32)ZSTD_hashPtr(ip, dms->rowHashLog + ZSTD_ROW_HASH_TAG_BITS, mls); |
1197 | U32 const dmsRelRow = (dmsHash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
1198 | dmsTag = dmsHash & ZSTD_ROW_HASH_TAG_MASK; |
1199 | dmsTagRow = (BYTE*)(dmsTagTable + dmsRelRow); |
1200 | dmsRow = dmsHashTable + dmsRelRow; |
1201 | ZSTD_row_prefetch(dmsHashTable, dmsTagTable, dmsRelRow, rowLog); |
1202 | } |
1203 | |
1204 | /* Update the hashTable and tagTable up to (but not including) ip */ |
1205 | if (!ms->lazySkipping) { |
1206 | ZSTD_row_update_internal(ms, ip, mls, rowLog, rowMask, 1 /* useCache */); |
1207 | hash = ZSTD_row_nextCachedHash(hashCache, hashTable, tagTable, base, curr, hashLog, rowLog, mls, hashSalt); |
1208 | } else { |
1209 | /* Stop inserting every position when in the lazy skipping mode. |
1210 | * The hash cache is also not kept up to date in this mode. |
1211 | */ |
1212 | hash = (U32)ZSTD_hashPtrSalted(ip, hashLog + ZSTD_ROW_HASH_TAG_BITS, mls, hashSalt); |
1213 | ms->nextToUpdate = curr; |
1214 | } |
1215 | ms->hashSaltEntropy += hash; /* collect salt entropy */ |
1216 | |
1217 | { /* Get the hash for ip, compute the appropriate row */ |
1218 | U32 const relRow = (hash >> ZSTD_ROW_HASH_TAG_BITS) << rowLog; |
1219 | U32 const tag = hash & ZSTD_ROW_HASH_TAG_MASK; |
1220 | U32* const row = hashTable + relRow; |
1221 | BYTE* tagRow = (BYTE*)(tagTable + relRow); |
1222 | U32 const headGrouped = (*tagRow & rowMask) * groupWidth; |
1223 | U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES]; |
1224 | size_t numMatches = 0; |
1225 | size_t currMatch = 0; |
1226 | ZSTD_VecMask matches = ZSTD_row_getMatchMask(tagRow, (BYTE)tag, headGrouped, rowEntries); |
1227 | |
1228 | /* Cycle through the matches and prefetch */ |
1229 | for (; (matches > 0) && (nbAttempts > 0); matches &= (matches - 1)) { |
1230 | U32 const matchPos = ((headGrouped + ZSTD_VecMask_next(matches)) / groupWidth) & rowMask; |
1231 | U32 const matchIndex = row[matchPos]; |
1232 | if(matchPos == 0) continue; |
1233 | assert(numMatches < rowEntries); |
1234 | if (matchIndex < lowLimit) |
1235 | break; |
1236 | if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { |
1237 | PREFETCH_L1(base + matchIndex); |
1238 | } else { |
1239 | PREFETCH_L1(dictBase + matchIndex); |
1240 | } |
1241 | matchBuffer[numMatches++] = matchIndex; |
1242 | --nbAttempts; |
1243 | } |
1244 | |
1245 | /* Speed opt: insert current byte into hashtable too. This allows us to avoid one iteration of the loop |
1246 | in ZSTD_row_update_internal() at the next search. */ |
1247 | { |
1248 | U32 const pos = ZSTD_row_nextIndex(tagRow, rowMask); |
1249 | tagRow[pos] = (BYTE)tag; |
1250 | row[pos] = ms->nextToUpdate++; |
1251 | } |
1252 | |
1253 | /* Return the longest match */ |
1254 | for (; currMatch < numMatches; ++currMatch) { |
1255 | U32 const matchIndex = matchBuffer[currMatch]; |
1256 | size_t currentMl=0; |
1257 | assert(matchIndex < curr); |
1258 | assert(matchIndex >= lowLimit); |
1259 | |
1260 | if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) { |
1261 | const BYTE* const match = base + matchIndex; |
1262 | assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */ |
1263 | /* read 4B starting from (match + ml + 1 - sizeof(U32)) */ |
1264 | if (MEM_read32(match + ml - 3) == MEM_read32(ip + ml - 3)) /* potentially better */ |
1265 | currentMl = ZSTD_count(ip, match, iLimit); |
1266 | } else { |
1267 | const BYTE* const match = dictBase + matchIndex; |
1268 | assert(match+4 <= dictEnd); |
1269 | if (MEM_read32(match) == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */ |
1270 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dictEnd, prefixStart) + 4; |
1271 | } |
1272 | |
1273 | /* Save best solution */ |
1274 | if (currentMl > ml) { |
1275 | ml = currentMl; |
1276 | *offsetPtr = OFFSET_TO_OFFBASE(curr - matchIndex); |
1277 | if (ip+currentMl == iLimit) break; /* best possible, avoids read overflow on next attempt */ |
1278 | } |
1279 | } |
1280 | } |
1281 | |
1282 | assert(nbAttempts <= (1U << ZSTD_SEARCHLOG_MAX)); /* Check we haven't underflowed. */ |
1283 | if (dictMode == ZSTD_dedicatedDictSearch) { |
1284 | ml = ZSTD_dedicatedDictSearch_lazy_search(offsetPtr, ml, nbAttempts + ddsExtraAttempts, dms, |
1285 | ip, iLimit, prefixStart, curr, dictLimit, ddsIdx); |
1286 | } else if (dictMode == ZSTD_dictMatchState) { |
1287 | /* TODO: Measure and potentially add prefetching to DMS */ |
1288 | const U32 dmsLowestIndex = dms->window.dictLimit; |
1289 | const BYTE* const dmsBase = dms->window.base; |
1290 | const BYTE* const dmsEnd = dms->window.nextSrc; |
1291 | const U32 dmsSize = (U32)(dmsEnd - dmsBase); |
1292 | const U32 dmsIndexDelta = dictLimit - dmsSize; |
1293 | |
1294 | { U32 const headGrouped = (*dmsTagRow & rowMask) * groupWidth; |
1295 | U32 matchBuffer[ZSTD_ROW_HASH_MAX_ENTRIES]; |
1296 | size_t numMatches = 0; |
1297 | size_t currMatch = 0; |
1298 | ZSTD_VecMask matches = ZSTD_row_getMatchMask(dmsTagRow, (BYTE)dmsTag, headGrouped, rowEntries); |
1299 | |
1300 | for (; (matches > 0) && (nbAttempts > 0); matches &= (matches - 1)) { |
1301 | U32 const matchPos = ((headGrouped + ZSTD_VecMask_next(matches)) / groupWidth) & rowMask; |
1302 | U32 const matchIndex = dmsRow[matchPos]; |
1303 | if(matchPos == 0) continue; |
1304 | if (matchIndex < dmsLowestIndex) |
1305 | break; |
1306 | PREFETCH_L1(dmsBase + matchIndex); |
1307 | matchBuffer[numMatches++] = matchIndex; |
1308 | --nbAttempts; |
1309 | } |
1310 | |
1311 | /* Return the longest match */ |
1312 | for (; currMatch < numMatches; ++currMatch) { |
1313 | U32 const matchIndex = matchBuffer[currMatch]; |
1314 | size_t currentMl=0; |
1315 | assert(matchIndex >= dmsLowestIndex); |
1316 | assert(matchIndex < curr); |
1317 | |
1318 | { const BYTE* const match = dmsBase + matchIndex; |
1319 | assert(match+4 <= dmsEnd); |
1320 | if (MEM_read32(match) == MEM_read32(ip)) |
1321 | currentMl = ZSTD_count_2segments(ip+4, match+4, iLimit, dmsEnd, prefixStart) + 4; |
1322 | } |
1323 | |
1324 | if (currentMl > ml) { |
1325 | ml = currentMl; |
1326 | assert(curr > matchIndex + dmsIndexDelta); |
1327 | *offsetPtr = OFFSET_TO_OFFBASE(curr - (matchIndex + dmsIndexDelta)); |
1328 | if (ip+currentMl == iLimit) break; |
1329 | } |
1330 | } |
1331 | } |
1332 | } |
1333 | return ml; |
1334 | } |
1335 | |
1336 | |
1337 | /** |
1338 | * Generate search functions templated on (dictMode, mls, rowLog). |
1339 | * These functions are outlined for code size & compilation time. |
1340 | * ZSTD_searchMax() dispatches to the correct implementation function. |
1341 | * |
1342 | * TODO: The start of the search function involves loading and calculating a |
1343 | * bunch of constants from the ZSTD_matchState_t. These computations could be |
1344 | * done in an initialization function, and saved somewhere in the match state. |
1345 | * Then we could pass a pointer to the saved state instead of the match state, |
1346 | * and avoid duplicate computations. |
1347 | * |
1348 | * TODO: Move the match re-winding into searchMax. This improves compression |
1349 | * ratio, and unlocks further simplifications with the next TODO. |
1350 | * |
1351 | * TODO: Try moving the repcode search into searchMax. After the re-winding |
1352 | * and repcode search are in searchMax, there is no more logic in the match |
1353 | * finder loop that requires knowledge about the dictMode. So we should be |
1354 | * able to avoid force inlining it, and we can join the extDict loop with |
1355 | * the single segment loop. It should go in searchMax instead of its own |
1356 | * function to avoid having multiple virtual function calls per search. |
1357 | */ |
1358 | |
1359 | #define ZSTD_BT_SEARCH_FN(dictMode, mls) ZSTD_BtFindBestMatch_##dictMode##_##mls |
1360 | #define ZSTD_HC_SEARCH_FN(dictMode, mls) ZSTD_HcFindBestMatch_##dictMode##_##mls |
1361 | #define ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog) ZSTD_RowFindBestMatch_##dictMode##_##mls##_##rowLog |
1362 | |
1363 | #define ZSTD_SEARCH_FN_ATTRS FORCE_NOINLINE |
1364 | |
1365 | #define GEN_ZSTD_BT_SEARCH_FN(dictMode, mls) \ |
1366 | ZSTD_SEARCH_FN_ATTRS size_t ZSTD_BT_SEARCH_FN(dictMode, mls)( \ |
1367 | ZSTD_matchState_t* ms, \ |
1368 | const BYTE* ip, const BYTE* const iLimit, \ |
1369 | size_t* offBasePtr) \ |
1370 | { \ |
1371 | assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ |
1372 | return ZSTD_BtFindBestMatch(ms, ip, iLimit, offBasePtr, mls, ZSTD_##dictMode); \ |
1373 | } \ |
1374 | |
1375 | #define GEN_ZSTD_HC_SEARCH_FN(dictMode, mls) \ |
1376 | ZSTD_SEARCH_FN_ATTRS size_t ZSTD_HC_SEARCH_FN(dictMode, mls)( \ |
1377 | ZSTD_matchState_t* ms, \ |
1378 | const BYTE* ip, const BYTE* const iLimit, \ |
1379 | size_t* offsetPtr) \ |
1380 | { \ |
1381 | assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ |
1382 | return ZSTD_HcFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode); \ |
1383 | } \ |
1384 | |
1385 | #define GEN_ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog) \ |
1386 | ZSTD_SEARCH_FN_ATTRS size_t ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog)( \ |
1387 | ZSTD_matchState_t* ms, \ |
1388 | const BYTE* ip, const BYTE* const iLimit, \ |
1389 | size_t* offsetPtr) \ |
1390 | { \ |
1391 | assert(MAX(4, MIN(6, ms->cParams.minMatch)) == mls); \ |
1392 | assert(MAX(4, MIN(6, ms->cParams.searchLog)) == rowLog); \ |
1393 | return ZSTD_RowFindBestMatch(ms, ip, iLimit, offsetPtr, mls, ZSTD_##dictMode, rowLog); \ |
1394 | } \ |
1395 | |
1396 | #define ZSTD_FOR_EACH_ROWLOG(X, dictMode, mls) \ |
1397 | X(dictMode, mls, 4) \ |
1398 | X(dictMode, mls, 5) \ |
1399 | X(dictMode, mls, 6) |
1400 | |
1401 | #define ZSTD_FOR_EACH_MLS_ROWLOG(X, dictMode) \ |
1402 | ZSTD_FOR_EACH_ROWLOG(X, dictMode, 4) \ |
1403 | ZSTD_FOR_EACH_ROWLOG(X, dictMode, 5) \ |
1404 | ZSTD_FOR_EACH_ROWLOG(X, dictMode, 6) |
1405 | |
1406 | #define ZSTD_FOR_EACH_MLS(X, dictMode) \ |
1407 | X(dictMode, 4) \ |
1408 | X(dictMode, 5) \ |
1409 | X(dictMode, 6) |
1410 | |
1411 | #define ZSTD_FOR_EACH_DICT_MODE(X, ...) \ |
1412 | X(__VA_ARGS__, noDict) \ |
1413 | X(__VA_ARGS__, extDict) \ |
1414 | X(__VA_ARGS__, dictMatchState) \ |
1415 | X(__VA_ARGS__, dedicatedDictSearch) |
1416 | |
1417 | /* Generate row search fns for each combination of (dictMode, mls, rowLog) */ |
1418 | ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS_ROWLOG, GEN_ZSTD_ROW_SEARCH_FN) |
1419 | /* Generate binary Tree search fns for each combination of (dictMode, mls) */ |
1420 | ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_BT_SEARCH_FN) |
1421 | /* Generate hash chain search fns for each combination of (dictMode, mls) */ |
1422 | ZSTD_FOR_EACH_DICT_MODE(ZSTD_FOR_EACH_MLS, GEN_ZSTD_HC_SEARCH_FN) |
1423 | |
1424 | typedef enum { search_hashChain=0, search_binaryTree=1, search_rowHash=2 } searchMethod_e; |
1425 | |
1426 | #define GEN_ZSTD_CALL_BT_SEARCH_FN(dictMode, mls) \ |
1427 | case mls: \ |
1428 | return ZSTD_BT_SEARCH_FN(dictMode, mls)(ms, ip, iend, offsetPtr); |
1429 | #define GEN_ZSTD_CALL_HC_SEARCH_FN(dictMode, mls) \ |
1430 | case mls: \ |
1431 | return ZSTD_HC_SEARCH_FN(dictMode, mls)(ms, ip, iend, offsetPtr); |
1432 | #define GEN_ZSTD_CALL_ROW_SEARCH_FN(dictMode, mls, rowLog) \ |
1433 | case rowLog: \ |
1434 | return ZSTD_ROW_SEARCH_FN(dictMode, mls, rowLog)(ms, ip, iend, offsetPtr); |
1435 | |
1436 | #define ZSTD_SWITCH_MLS(X, dictMode) \ |
1437 | switch (mls) { \ |
1438 | ZSTD_FOR_EACH_MLS(X, dictMode) \ |
1439 | } |
1440 | |
1441 | #define ZSTD_SWITCH_ROWLOG(dictMode, mls) \ |
1442 | case mls: \ |
1443 | switch (rowLog) { \ |
1444 | ZSTD_FOR_EACH_ROWLOG(GEN_ZSTD_CALL_ROW_SEARCH_FN, dictMode, mls) \ |
1445 | } \ |
1446 | ZSTD_UNREACHABLE; \ |
1447 | break; |
1448 | |
1449 | #define ZSTD_SWITCH_SEARCH_METHOD(dictMode) \ |
1450 | switch (searchMethod) { \ |
1451 | case search_hashChain: \ |
1452 | ZSTD_SWITCH_MLS(GEN_ZSTD_CALL_HC_SEARCH_FN, dictMode) \ |
1453 | break; \ |
1454 | case search_binaryTree: \ |
1455 | ZSTD_SWITCH_MLS(GEN_ZSTD_CALL_BT_SEARCH_FN, dictMode) \ |
1456 | break; \ |
1457 | case search_rowHash: \ |
1458 | ZSTD_SWITCH_MLS(ZSTD_SWITCH_ROWLOG, dictMode) \ |
1459 | break; \ |
1460 | } \ |
1461 | ZSTD_UNREACHABLE; |
1462 | |
1463 | /** |
1464 | * Searches for the longest match at @p ip. |
1465 | * Dispatches to the correct implementation function based on the |
1466 | * (searchMethod, dictMode, mls, rowLog). We use switch statements |
1467 | * here instead of using an indirect function call through a function |
1468 | * pointer because after Spectre and Meltdown mitigations, indirect |
1469 | * function calls can be very costly, especially in the kernel. |
1470 | * |
1471 | * NOTE: dictMode and searchMethod should be templated, so those switch |
1472 | * statements should be optimized out. Only the mls & rowLog switches |
1473 | * should be left. |
1474 | * |
1475 | * @param ms The match state. |
1476 | * @param ip The position to search at. |
1477 | * @param iend The end of the input data. |
1478 | * @param[out] offsetPtr Stores the match offset into this pointer. |
1479 | * @param mls The minimum search length, in the range [4, 6]. |
1480 | * @param rowLog The row log (if applicable), in the range [4, 6]. |
1481 | * @param searchMethod The search method to use (templated). |
1482 | * @param dictMode The dictMode (templated). |
1483 | * |
1484 | * @returns The length of the longest match found, or < mls if no match is found. |
1485 | * If a match is found its offset is stored in @p offsetPtr. |
1486 | */ |
1487 | FORCE_INLINE_TEMPLATE size_t ZSTD_searchMax( |
1488 | ZSTD_matchState_t* ms, |
1489 | const BYTE* ip, |
1490 | const BYTE* iend, |
1491 | size_t* offsetPtr, |
1492 | U32 const mls, |
1493 | U32 const rowLog, |
1494 | searchMethod_e const searchMethod, |
1495 | ZSTD_dictMode_e const dictMode) |
1496 | { |
1497 | if (dictMode == ZSTD_noDict) { |
1498 | ZSTD_SWITCH_SEARCH_METHOD(noDict) |
1499 | } else if (dictMode == ZSTD_extDict) { |
1500 | ZSTD_SWITCH_SEARCH_METHOD(extDict) |
1501 | } else if (dictMode == ZSTD_dictMatchState) { |
1502 | ZSTD_SWITCH_SEARCH_METHOD(dictMatchState) |
1503 | } else if (dictMode == ZSTD_dedicatedDictSearch) { |
1504 | ZSTD_SWITCH_SEARCH_METHOD(dedicatedDictSearch) |
1505 | } |
1506 | ZSTD_UNREACHABLE; |
1507 | return 0; |
1508 | } |
1509 | |
1510 | /* ******************************* |
1511 | * Common parser - lazy strategy |
1512 | *********************************/ |
1513 | |
f535537f |
1514 | FORCE_INLINE_TEMPLATE |
1515 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
1516 | size_t ZSTD_compressBlock_lazy_generic( |
648db22b |
1517 | ZSTD_matchState_t* ms, seqStore_t* seqStore, |
1518 | U32 rep[ZSTD_REP_NUM], |
1519 | const void* src, size_t srcSize, |
1520 | const searchMethod_e searchMethod, const U32 depth, |
1521 | ZSTD_dictMode_e const dictMode) |
1522 | { |
1523 | const BYTE* const istart = (const BYTE*)src; |
1524 | const BYTE* ip = istart; |
1525 | const BYTE* anchor = istart; |
1526 | const BYTE* const iend = istart + srcSize; |
1527 | const BYTE* const ilimit = (searchMethod == search_rowHash) ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8; |
1528 | const BYTE* const base = ms->window.base; |
1529 | const U32 prefixLowestIndex = ms->window.dictLimit; |
1530 | const BYTE* const prefixLowest = base + prefixLowestIndex; |
1531 | const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6); |
1532 | const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); |
1533 | |
1534 | U32 offset_1 = rep[0], offset_2 = rep[1]; |
1535 | U32 offsetSaved1 = 0, offsetSaved2 = 0; |
1536 | |
1537 | const int isDMS = dictMode == ZSTD_dictMatchState; |
1538 | const int isDDS = dictMode == ZSTD_dedicatedDictSearch; |
1539 | const int isDxS = isDMS || isDDS; |
1540 | const ZSTD_matchState_t* const dms = ms->dictMatchState; |
1541 | const U32 dictLowestIndex = isDxS ? dms->window.dictLimit : 0; |
1542 | const BYTE* const dictBase = isDxS ? dms->window.base : NULL; |
1543 | const BYTE* const dictLowest = isDxS ? dictBase + dictLowestIndex : NULL; |
1544 | const BYTE* const dictEnd = isDxS ? dms->window.nextSrc : NULL; |
1545 | const U32 dictIndexDelta = isDxS ? |
1546 | prefixLowestIndex - (U32)(dictEnd - dictBase) : |
1547 | 0; |
1548 | const U32 dictAndPrefixLength = (U32)((ip - prefixLowest) + (dictEnd - dictLowest)); |
1549 | |
1550 | DEBUGLOG(5, "ZSTD_compressBlock_lazy_generic (dictMode=%u) (searchFunc=%u)", (U32)dictMode, (U32)searchMethod); |
1551 | ip += (dictAndPrefixLength == 0); |
1552 | if (dictMode == ZSTD_noDict) { |
1553 | U32 const curr = (U32)(ip - base); |
1554 | U32 const windowLow = ZSTD_getLowestPrefixIndex(ms, curr, ms->cParams.windowLog); |
1555 | U32 const maxRep = curr - windowLow; |
1556 | if (offset_2 > maxRep) offsetSaved2 = offset_2, offset_2 = 0; |
1557 | if (offset_1 > maxRep) offsetSaved1 = offset_1, offset_1 = 0; |
1558 | } |
1559 | if (isDxS) { |
1560 | /* dictMatchState repCode checks don't currently handle repCode == 0 |
1561 | * disabling. */ |
1562 | assert(offset_1 <= dictAndPrefixLength); |
1563 | assert(offset_2 <= dictAndPrefixLength); |
1564 | } |
1565 | |
1566 | /* Reset the lazy skipping state */ |
1567 | ms->lazySkipping = 0; |
1568 | |
1569 | if (searchMethod == search_rowHash) { |
1570 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit); |
1571 | } |
1572 | |
1573 | /* Match Loop */ |
1574 | #if defined(__GNUC__) && defined(__x86_64__) |
1575 | /* I've measured random a 5% speed loss on levels 5 & 6 (greedy) when the |
1576 | * code alignment is perturbed. To fix the instability align the loop on 32-bytes. |
1577 | */ |
1578 | __asm__(".p2align 5"); |
1579 | #endif |
1580 | while (ip < ilimit) { |
1581 | size_t matchLength=0; |
1582 | size_t offBase = REPCODE1_TO_OFFBASE; |
1583 | const BYTE* start=ip+1; |
1584 | DEBUGLOG(7, "search baseline (depth 0)"); |
1585 | |
1586 | /* check repCode */ |
1587 | if (isDxS) { |
1588 | const U32 repIndex = (U32)(ip - base) + 1 - offset_1; |
1589 | const BYTE* repMatch = ((dictMode == ZSTD_dictMatchState || dictMode == ZSTD_dedicatedDictSearch) |
1590 | && repIndex < prefixLowestIndex) ? |
1591 | dictBase + (repIndex - dictIndexDelta) : |
1592 | base + repIndex; |
1593 | if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) |
1594 | && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) { |
1595 | const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; |
1596 | matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; |
1597 | if (depth==0) goto _storeSequence; |
1598 | } |
1599 | } |
1600 | if ( dictMode == ZSTD_noDict |
1601 | && ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) { |
1602 | matchLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4; |
1603 | if (depth==0) goto _storeSequence; |
1604 | } |
1605 | |
1606 | /* first search (depth 0) */ |
1607 | { size_t offbaseFound = 999999999; |
1608 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &offbaseFound, mls, rowLog, searchMethod, dictMode); |
1609 | if (ml2 > matchLength) |
1610 | matchLength = ml2, start = ip, offBase = offbaseFound; |
1611 | } |
1612 | |
1613 | if (matchLength < 4) { |
1614 | size_t const step = ((size_t)(ip-anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */; |
1615 | ip += step; |
1616 | /* Enter the lazy skipping mode once we are skipping more than 8 bytes at a time. |
1617 | * In this mode we stop inserting every position into our tables, and only insert |
1618 | * positions that we search, which is one in step positions. |
1619 | * The exact cutoff is flexible, I've just chosen a number that is reasonably high, |
1620 | * so we minimize the compression ratio loss in "normal" scenarios. This mode gets |
1621 | * triggered once we've gone 2KB without finding any matches. |
1622 | */ |
1623 | ms->lazySkipping = step > kLazySkippingStep; |
1624 | continue; |
1625 | } |
1626 | |
1627 | /* let's try to find a better solution */ |
1628 | if (depth>=1) |
1629 | while (ip<ilimit) { |
1630 | DEBUGLOG(7, "search depth 1"); |
1631 | ip ++; |
1632 | if ( (dictMode == ZSTD_noDict) |
1633 | && (offBase) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) { |
1634 | size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4; |
1635 | int const gain2 = (int)(mlRep * 3); |
1636 | int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1); |
1637 | if ((mlRep >= 4) && (gain2 > gain1)) |
1638 | matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip; |
1639 | } |
1640 | if (isDxS) { |
1641 | const U32 repIndex = (U32)(ip - base) - offset_1; |
1642 | const BYTE* repMatch = repIndex < prefixLowestIndex ? |
1643 | dictBase + (repIndex - dictIndexDelta) : |
1644 | base + repIndex; |
1645 | if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) |
1646 | && (MEM_read32(repMatch) == MEM_read32(ip)) ) { |
1647 | const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; |
1648 | size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; |
1649 | int const gain2 = (int)(mlRep * 3); |
1650 | int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1); |
1651 | if ((mlRep >= 4) && (gain2 > gain1)) |
1652 | matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip; |
1653 | } |
1654 | } |
1655 | { size_t ofbCandidate=999999999; |
1656 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, dictMode); |
1657 | int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */ |
1658 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 4); |
1659 | if ((ml2 >= 4) && (gain2 > gain1)) { |
1660 | matchLength = ml2, offBase = ofbCandidate, start = ip; |
1661 | continue; /* search a better one */ |
1662 | } } |
1663 | |
1664 | /* let's find an even better one */ |
1665 | if ((depth==2) && (ip<ilimit)) { |
1666 | DEBUGLOG(7, "search depth 2"); |
1667 | ip ++; |
1668 | if ( (dictMode == ZSTD_noDict) |
1669 | && (offBase) && ((offset_1>0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) { |
1670 | size_t const mlRep = ZSTD_count(ip+4, ip+4-offset_1, iend) + 4; |
1671 | int const gain2 = (int)(mlRep * 4); |
1672 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1); |
1673 | if ((mlRep >= 4) && (gain2 > gain1)) |
1674 | matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip; |
1675 | } |
1676 | if (isDxS) { |
1677 | const U32 repIndex = (U32)(ip - base) - offset_1; |
1678 | const BYTE* repMatch = repIndex < prefixLowestIndex ? |
1679 | dictBase + (repIndex - dictIndexDelta) : |
1680 | base + repIndex; |
1681 | if (((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */) |
1682 | && (MEM_read32(repMatch) == MEM_read32(ip)) ) { |
1683 | const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend; |
1684 | size_t const mlRep = ZSTD_count_2segments(ip+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4; |
1685 | int const gain2 = (int)(mlRep * 4); |
1686 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1); |
1687 | if ((mlRep >= 4) && (gain2 > gain1)) |
1688 | matchLength = mlRep, offBase = REPCODE1_TO_OFFBASE, start = ip; |
1689 | } |
1690 | } |
1691 | { size_t ofbCandidate=999999999; |
1692 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, dictMode); |
1693 | int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */ |
1694 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 7); |
1695 | if ((ml2 >= 4) && (gain2 > gain1)) { |
1696 | matchLength = ml2, offBase = ofbCandidate, start = ip; |
1697 | continue; |
1698 | } } } |
1699 | break; /* nothing found : store previous solution */ |
1700 | } |
1701 | |
1702 | /* NOTE: |
1703 | * Pay attention that `start[-value]` can lead to strange undefined behavior |
1704 | * notably if `value` is unsigned, resulting in a large positive `-value`. |
1705 | */ |
1706 | /* catch up */ |
1707 | if (OFFBASE_IS_OFFSET(offBase)) { |
1708 | if (dictMode == ZSTD_noDict) { |
1709 | while ( ((start > anchor) & (start - OFFBASE_TO_OFFSET(offBase) > prefixLowest)) |
1710 | && (start[-1] == (start-OFFBASE_TO_OFFSET(offBase))[-1]) ) /* only search for offset within prefix */ |
1711 | { start--; matchLength++; } |
1712 | } |
1713 | if (isDxS) { |
1714 | U32 const matchIndex = (U32)((size_t)(start-base) - OFFBASE_TO_OFFSET(offBase)); |
1715 | const BYTE* match = (matchIndex < prefixLowestIndex) ? dictBase + matchIndex - dictIndexDelta : base + matchIndex; |
1716 | const BYTE* const mStart = (matchIndex < prefixLowestIndex) ? dictLowest : prefixLowest; |
1717 | while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */ |
1718 | } |
1719 | offset_2 = offset_1; offset_1 = (U32)OFFBASE_TO_OFFSET(offBase); |
1720 | } |
1721 | /* store sequence */ |
1722 | _storeSequence: |
1723 | { size_t const litLength = (size_t)(start - anchor); |
1724 | ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offBase, matchLength); |
1725 | anchor = ip = start + matchLength; |
1726 | } |
1727 | if (ms->lazySkipping) { |
1728 | /* We've found a match, disable lazy skipping mode, and refill the hash cache. */ |
1729 | if (searchMethod == search_rowHash) { |
1730 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit); |
1731 | } |
1732 | ms->lazySkipping = 0; |
1733 | } |
1734 | |
1735 | /* check immediate repcode */ |
1736 | if (isDxS) { |
1737 | while (ip <= ilimit) { |
1738 | U32 const current2 = (U32)(ip-base); |
1739 | U32 const repIndex = current2 - offset_2; |
1740 | const BYTE* repMatch = repIndex < prefixLowestIndex ? |
1741 | dictBase - dictIndexDelta + repIndex : |
1742 | base + repIndex; |
1743 | if ( ((U32)((prefixLowestIndex-1) - (U32)repIndex) >= 3 /* intentional overflow */) |
1744 | && (MEM_read32(repMatch) == MEM_read32(ip)) ) { |
1745 | const BYTE* const repEnd2 = repIndex < prefixLowestIndex ? dictEnd : iend; |
1746 | matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd2, prefixLowest) + 4; |
1747 | offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap offset_2 <=> offset_1 */ |
1748 | ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength); |
1749 | ip += matchLength; |
1750 | anchor = ip; |
1751 | continue; |
1752 | } |
1753 | break; |
1754 | } |
1755 | } |
1756 | |
1757 | if (dictMode == ZSTD_noDict) { |
1758 | while ( ((ip <= ilimit) & (offset_2>0)) |
1759 | && (MEM_read32(ip) == MEM_read32(ip - offset_2)) ) { |
1760 | /* store sequence */ |
1761 | matchLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4; |
1762 | offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap repcodes */ |
1763 | ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength); |
1764 | ip += matchLength; |
1765 | anchor = ip; |
1766 | continue; /* faster when present ... (?) */ |
1767 | } } } |
1768 | |
1769 | /* If offset_1 started invalid (offsetSaved1 != 0) and became valid (offset_1 != 0), |
1770 | * rotate saved offsets. See comment in ZSTD_compressBlock_fast_noDict for more context. */ |
1771 | offsetSaved2 = ((offsetSaved1 != 0) && (offset_1 != 0)) ? offsetSaved1 : offsetSaved2; |
1772 | |
1773 | /* save reps for next block */ |
1774 | rep[0] = offset_1 ? offset_1 : offsetSaved1; |
1775 | rep[1] = offset_2 ? offset_2 : offsetSaved2; |
1776 | |
1777 | /* Return the last literals size */ |
1778 | return (size_t)(iend - anchor); |
1779 | } |
f535537f |
1780 | #endif /* build exclusions */ |
648db22b |
1781 | |
1782 | |
f535537f |
1783 | #ifndef ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR |
1784 | size_t ZSTD_compressBlock_greedy( |
648db22b |
1785 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1786 | void const* src, size_t srcSize) |
1787 | { |
f535537f |
1788 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_noDict); |
648db22b |
1789 | } |
1790 | |
f535537f |
1791 | size_t ZSTD_compressBlock_greedy_dictMatchState( |
648db22b |
1792 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1793 | void const* src, size_t srcSize) |
1794 | { |
f535537f |
1795 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dictMatchState); |
648db22b |
1796 | } |
1797 | |
f535537f |
1798 | size_t ZSTD_compressBlock_greedy_dedicatedDictSearch( |
648db22b |
1799 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1800 | void const* src, size_t srcSize) |
1801 | { |
f535537f |
1802 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dedicatedDictSearch); |
648db22b |
1803 | } |
1804 | |
f535537f |
1805 | size_t ZSTD_compressBlock_greedy_row( |
648db22b |
1806 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1807 | void const* src, size_t srcSize) |
1808 | { |
f535537f |
1809 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_noDict); |
648db22b |
1810 | } |
1811 | |
f535537f |
1812 | size_t ZSTD_compressBlock_greedy_dictMatchState_row( |
648db22b |
1813 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1814 | void const* src, size_t srcSize) |
1815 | { |
f535537f |
1816 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_dictMatchState); |
648db22b |
1817 | } |
1818 | |
f535537f |
1819 | size_t ZSTD_compressBlock_greedy_dedicatedDictSearch_row( |
648db22b |
1820 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1821 | void const* src, size_t srcSize) |
1822 | { |
f535537f |
1823 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0, ZSTD_dedicatedDictSearch); |
648db22b |
1824 | } |
f535537f |
1825 | #endif |
648db22b |
1826 | |
f535537f |
1827 | #ifndef ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR |
1828 | size_t ZSTD_compressBlock_lazy( |
648db22b |
1829 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1830 | void const* src, size_t srcSize) |
1831 | { |
f535537f |
1832 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_noDict); |
648db22b |
1833 | } |
1834 | |
f535537f |
1835 | size_t ZSTD_compressBlock_lazy_dictMatchState( |
648db22b |
1836 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1837 | void const* src, size_t srcSize) |
1838 | { |
f535537f |
1839 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dictMatchState); |
648db22b |
1840 | } |
1841 | |
f535537f |
1842 | size_t ZSTD_compressBlock_lazy_dedicatedDictSearch( |
648db22b |
1843 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1844 | void const* src, size_t srcSize) |
1845 | { |
f535537f |
1846 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dedicatedDictSearch); |
648db22b |
1847 | } |
1848 | |
f535537f |
1849 | size_t ZSTD_compressBlock_lazy_row( |
648db22b |
1850 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1851 | void const* src, size_t srcSize) |
1852 | { |
f535537f |
1853 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_noDict); |
648db22b |
1854 | } |
1855 | |
f535537f |
1856 | size_t ZSTD_compressBlock_lazy_dictMatchState_row( |
648db22b |
1857 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1858 | void const* src, size_t srcSize) |
1859 | { |
f535537f |
1860 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_dictMatchState); |
648db22b |
1861 | } |
1862 | |
f535537f |
1863 | size_t ZSTD_compressBlock_lazy_dedicatedDictSearch_row( |
648db22b |
1864 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1865 | void const* src, size_t srcSize) |
1866 | { |
f535537f |
1867 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1, ZSTD_dedicatedDictSearch); |
648db22b |
1868 | } |
f535537f |
1869 | #endif |
648db22b |
1870 | |
f535537f |
1871 | #ifndef ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR |
1872 | size_t ZSTD_compressBlock_lazy2( |
648db22b |
1873 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1874 | void const* src, size_t srcSize) |
1875 | { |
f535537f |
1876 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_noDict); |
648db22b |
1877 | } |
1878 | |
f535537f |
1879 | size_t ZSTD_compressBlock_lazy2_dictMatchState( |
648db22b |
1880 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1881 | void const* src, size_t srcSize) |
1882 | { |
f535537f |
1883 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dictMatchState); |
648db22b |
1884 | } |
1885 | |
f535537f |
1886 | size_t ZSTD_compressBlock_lazy2_dedicatedDictSearch( |
648db22b |
1887 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1888 | void const* src, size_t srcSize) |
1889 | { |
f535537f |
1890 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dedicatedDictSearch); |
648db22b |
1891 | } |
1892 | |
f535537f |
1893 | size_t ZSTD_compressBlock_lazy2_row( |
648db22b |
1894 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1895 | void const* src, size_t srcSize) |
1896 | { |
f535537f |
1897 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_noDict); |
648db22b |
1898 | } |
1899 | |
f535537f |
1900 | size_t ZSTD_compressBlock_lazy2_dictMatchState_row( |
648db22b |
1901 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1902 | void const* src, size_t srcSize) |
1903 | { |
f535537f |
1904 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_dictMatchState); |
648db22b |
1905 | } |
1906 | |
648db22b |
1907 | size_t ZSTD_compressBlock_lazy2_dedicatedDictSearch_row( |
1908 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1909 | void const* src, size_t srcSize) |
1910 | { |
1911 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2, ZSTD_dedicatedDictSearch); |
1912 | } |
f535537f |
1913 | #endif |
648db22b |
1914 | |
f535537f |
1915 | #ifndef ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR |
1916 | size_t ZSTD_compressBlock_btlazy2( |
648db22b |
1917 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1918 | void const* src, size_t srcSize) |
1919 | { |
f535537f |
1920 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_noDict); |
648db22b |
1921 | } |
1922 | |
f535537f |
1923 | size_t ZSTD_compressBlock_btlazy2_dictMatchState( |
648db22b |
1924 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
1925 | void const* src, size_t srcSize) |
1926 | { |
f535537f |
1927 | return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_dictMatchState); |
648db22b |
1928 | } |
f535537f |
1929 | #endif |
648db22b |
1930 | |
f535537f |
1931 | #if !defined(ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR) \ |
1932 | || !defined(ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR) \ |
1933 | || !defined(ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR) \ |
1934 | || !defined(ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR) |
648db22b |
1935 | FORCE_INLINE_TEMPLATE |
f535537f |
1936 | ZSTD_ALLOW_POINTER_OVERFLOW_ATTR |
648db22b |
1937 | size_t ZSTD_compressBlock_lazy_extDict_generic( |
1938 | ZSTD_matchState_t* ms, seqStore_t* seqStore, |
1939 | U32 rep[ZSTD_REP_NUM], |
1940 | const void* src, size_t srcSize, |
1941 | const searchMethod_e searchMethod, const U32 depth) |
1942 | { |
1943 | const BYTE* const istart = (const BYTE*)src; |
1944 | const BYTE* ip = istart; |
1945 | const BYTE* anchor = istart; |
1946 | const BYTE* const iend = istart + srcSize; |
1947 | const BYTE* const ilimit = searchMethod == search_rowHash ? iend - 8 - ZSTD_ROW_HASH_CACHE_SIZE : iend - 8; |
1948 | const BYTE* const base = ms->window.base; |
1949 | const U32 dictLimit = ms->window.dictLimit; |
1950 | const BYTE* const prefixStart = base + dictLimit; |
1951 | const BYTE* const dictBase = ms->window.dictBase; |
1952 | const BYTE* const dictEnd = dictBase + dictLimit; |
1953 | const BYTE* const dictStart = dictBase + ms->window.lowLimit; |
1954 | const U32 windowLog = ms->cParams.windowLog; |
1955 | const U32 mls = BOUNDED(4, ms->cParams.minMatch, 6); |
1956 | const U32 rowLog = BOUNDED(4, ms->cParams.searchLog, 6); |
1957 | |
1958 | U32 offset_1 = rep[0], offset_2 = rep[1]; |
1959 | |
1960 | DEBUGLOG(5, "ZSTD_compressBlock_lazy_extDict_generic (searchFunc=%u)", (U32)searchMethod); |
1961 | |
1962 | /* Reset the lazy skipping state */ |
1963 | ms->lazySkipping = 0; |
1964 | |
1965 | /* init */ |
1966 | ip += (ip == prefixStart); |
1967 | if (searchMethod == search_rowHash) { |
1968 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit); |
1969 | } |
1970 | |
1971 | /* Match Loop */ |
1972 | #if defined(__GNUC__) && defined(__x86_64__) |
1973 | /* I've measured random a 5% speed loss on levels 5 & 6 (greedy) when the |
1974 | * code alignment is perturbed. To fix the instability align the loop on 32-bytes. |
1975 | */ |
1976 | __asm__(".p2align 5"); |
1977 | #endif |
1978 | while (ip < ilimit) { |
1979 | size_t matchLength=0; |
1980 | size_t offBase = REPCODE1_TO_OFFBASE; |
1981 | const BYTE* start=ip+1; |
1982 | U32 curr = (U32)(ip-base); |
1983 | |
1984 | /* check repCode */ |
1985 | { const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr+1, windowLog); |
1986 | const U32 repIndex = (U32)(curr+1 - offset_1); |
1987 | const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; |
1988 | const BYTE* const repMatch = repBase + repIndex; |
1989 | if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow */ |
1990 | & (offset_1 <= curr+1 - windowLow) ) /* note: we are searching at curr+1 */ |
1991 | if (MEM_read32(ip+1) == MEM_read32(repMatch)) { |
1992 | /* repcode detected we should take it */ |
1993 | const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; |
1994 | matchLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repEnd, prefixStart) + 4; |
1995 | if (depth==0) goto _storeSequence; |
1996 | } } |
1997 | |
1998 | /* first search (depth 0) */ |
1999 | { size_t ofbCandidate = 999999999; |
2000 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict); |
2001 | if (ml2 > matchLength) |
2002 | matchLength = ml2, start = ip, offBase = ofbCandidate; |
2003 | } |
2004 | |
2005 | if (matchLength < 4) { |
2006 | size_t const step = ((size_t)(ip-anchor) >> kSearchStrength); |
2007 | ip += step + 1; /* jump faster over incompressible sections */ |
2008 | /* Enter the lazy skipping mode once we are skipping more than 8 bytes at a time. |
2009 | * In this mode we stop inserting every position into our tables, and only insert |
2010 | * positions that we search, which is one in step positions. |
2011 | * The exact cutoff is flexible, I've just chosen a number that is reasonably high, |
2012 | * so we minimize the compression ratio loss in "normal" scenarios. This mode gets |
2013 | * triggered once we've gone 2KB without finding any matches. |
2014 | */ |
2015 | ms->lazySkipping = step > kLazySkippingStep; |
2016 | continue; |
2017 | } |
2018 | |
2019 | /* let's try to find a better solution */ |
2020 | if (depth>=1) |
2021 | while (ip<ilimit) { |
2022 | ip ++; |
2023 | curr++; |
2024 | /* check repCode */ |
2025 | if (offBase) { |
2026 | const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog); |
2027 | const U32 repIndex = (U32)(curr - offset_1); |
2028 | const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; |
2029 | const BYTE* const repMatch = repBase + repIndex; |
2030 | if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ |
2031 | & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ |
2032 | if (MEM_read32(ip) == MEM_read32(repMatch)) { |
2033 | /* repcode detected */ |
2034 | const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; |
2035 | size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; |
2036 | int const gain2 = (int)(repLength * 3); |
2037 | int const gain1 = (int)(matchLength*3 - ZSTD_highbit32((U32)offBase) + 1); |
2038 | if ((repLength >= 4) && (gain2 > gain1)) |
2039 | matchLength = repLength, offBase = REPCODE1_TO_OFFBASE, start = ip; |
2040 | } } |
2041 | |
2042 | /* search match, depth 1 */ |
2043 | { size_t ofbCandidate = 999999999; |
2044 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict); |
2045 | int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */ |
2046 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 4); |
2047 | if ((ml2 >= 4) && (gain2 > gain1)) { |
2048 | matchLength = ml2, offBase = ofbCandidate, start = ip; |
2049 | continue; /* search a better one */ |
2050 | } } |
2051 | |
2052 | /* let's find an even better one */ |
2053 | if ((depth==2) && (ip<ilimit)) { |
2054 | ip ++; |
2055 | curr++; |
2056 | /* check repCode */ |
2057 | if (offBase) { |
2058 | const U32 windowLow = ZSTD_getLowestMatchIndex(ms, curr, windowLog); |
2059 | const U32 repIndex = (U32)(curr - offset_1); |
2060 | const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; |
2061 | const BYTE* const repMatch = repBase + repIndex; |
2062 | if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ |
2063 | & (offset_1 <= curr - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ |
2064 | if (MEM_read32(ip) == MEM_read32(repMatch)) { |
2065 | /* repcode detected */ |
2066 | const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; |
2067 | size_t const repLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; |
2068 | int const gain2 = (int)(repLength * 4); |
2069 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 1); |
2070 | if ((repLength >= 4) && (gain2 > gain1)) |
2071 | matchLength = repLength, offBase = REPCODE1_TO_OFFBASE, start = ip; |
2072 | } } |
2073 | |
2074 | /* search match, depth 2 */ |
2075 | { size_t ofbCandidate = 999999999; |
2076 | size_t const ml2 = ZSTD_searchMax(ms, ip, iend, &ofbCandidate, mls, rowLog, searchMethod, ZSTD_extDict); |
2077 | int const gain2 = (int)(ml2*4 - ZSTD_highbit32((U32)ofbCandidate)); /* raw approx */ |
2078 | int const gain1 = (int)(matchLength*4 - ZSTD_highbit32((U32)offBase) + 7); |
2079 | if ((ml2 >= 4) && (gain2 > gain1)) { |
2080 | matchLength = ml2, offBase = ofbCandidate, start = ip; |
2081 | continue; |
2082 | } } } |
2083 | break; /* nothing found : store previous solution */ |
2084 | } |
2085 | |
2086 | /* catch up */ |
2087 | if (OFFBASE_IS_OFFSET(offBase)) { |
2088 | U32 const matchIndex = (U32)((size_t)(start-base) - OFFBASE_TO_OFFSET(offBase)); |
2089 | const BYTE* match = (matchIndex < dictLimit) ? dictBase + matchIndex : base + matchIndex; |
2090 | const BYTE* const mStart = (matchIndex < dictLimit) ? dictStart : prefixStart; |
2091 | while ((start>anchor) && (match>mStart) && (start[-1] == match[-1])) { start--; match--; matchLength++; } /* catch up */ |
2092 | offset_2 = offset_1; offset_1 = (U32)OFFBASE_TO_OFFSET(offBase); |
2093 | } |
2094 | |
2095 | /* store sequence */ |
2096 | _storeSequence: |
2097 | { size_t const litLength = (size_t)(start - anchor); |
2098 | ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offBase, matchLength); |
2099 | anchor = ip = start + matchLength; |
2100 | } |
2101 | if (ms->lazySkipping) { |
2102 | /* We've found a match, disable lazy skipping mode, and refill the hash cache. */ |
2103 | if (searchMethod == search_rowHash) { |
2104 | ZSTD_row_fillHashCache(ms, base, rowLog, mls, ms->nextToUpdate, ilimit); |
2105 | } |
2106 | ms->lazySkipping = 0; |
2107 | } |
2108 | |
2109 | /* check immediate repcode */ |
2110 | while (ip <= ilimit) { |
2111 | const U32 repCurrent = (U32)(ip-base); |
2112 | const U32 windowLow = ZSTD_getLowestMatchIndex(ms, repCurrent, windowLog); |
2113 | const U32 repIndex = repCurrent - offset_2; |
2114 | const BYTE* const repBase = repIndex < dictLimit ? dictBase : base; |
2115 | const BYTE* const repMatch = repBase + repIndex; |
2116 | if ( ((U32)((dictLimit-1) - repIndex) >= 3) /* intentional overflow : do not test positions overlapping 2 memory segments */ |
2117 | & (offset_2 <= repCurrent - windowLow) ) /* equivalent to `curr > repIndex >= windowLow` */ |
2118 | if (MEM_read32(ip) == MEM_read32(repMatch)) { |
2119 | /* repcode detected we should take it */ |
2120 | const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend; |
2121 | matchLength = ZSTD_count_2segments(ip+4, repMatch+4, iend, repEnd, prefixStart) + 4; |
2122 | offBase = offset_2; offset_2 = offset_1; offset_1 = (U32)offBase; /* swap offset history */ |
2123 | ZSTD_storeSeq(seqStore, 0, anchor, iend, REPCODE1_TO_OFFBASE, matchLength); |
2124 | ip += matchLength; |
2125 | anchor = ip; |
2126 | continue; /* faster when present ... (?) */ |
2127 | } |
2128 | break; |
2129 | } } |
2130 | |
2131 | /* Save reps for next block */ |
2132 | rep[0] = offset_1; |
2133 | rep[1] = offset_2; |
2134 | |
2135 | /* Return the last literals size */ |
2136 | return (size_t)(iend - anchor); |
2137 | } |
f535537f |
2138 | #endif /* build exclusions */ |
648db22b |
2139 | |
f535537f |
2140 | #ifndef ZSTD_EXCLUDE_GREEDY_BLOCK_COMPRESSOR |
648db22b |
2141 | size_t ZSTD_compressBlock_greedy_extDict( |
2142 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
2143 | void const* src, size_t srcSize) |
2144 | { |
2145 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0); |
2146 | } |
2147 | |
f535537f |
2148 | size_t ZSTD_compressBlock_greedy_extDict_row( |
648db22b |
2149 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
2150 | void const* src, size_t srcSize) |
648db22b |
2151 | { |
f535537f |
2152 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 0); |
648db22b |
2153 | } |
f535537f |
2154 | #endif |
648db22b |
2155 | |
f535537f |
2156 | #ifndef ZSTD_EXCLUDE_LAZY_BLOCK_COMPRESSOR |
2157 | size_t ZSTD_compressBlock_lazy_extDict( |
648db22b |
2158 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
2159 | void const* src, size_t srcSize) |
2160 | |
2161 | { |
f535537f |
2162 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1); |
648db22b |
2163 | } |
2164 | |
f535537f |
2165 | size_t ZSTD_compressBlock_lazy_extDict_row( |
648db22b |
2166 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
2167 | void const* src, size_t srcSize) |
2168 | |
2169 | { |
f535537f |
2170 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 1); |
648db22b |
2171 | } |
f535537f |
2172 | #endif |
648db22b |
2173 | |
f535537f |
2174 | #ifndef ZSTD_EXCLUDE_LAZY2_BLOCK_COMPRESSOR |
2175 | size_t ZSTD_compressBlock_lazy2_extDict( |
648db22b |
2176 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
2177 | void const* src, size_t srcSize) |
f535537f |
2178 | |
648db22b |
2179 | { |
f535537f |
2180 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2); |
648db22b |
2181 | } |
2182 | |
f535537f |
2183 | size_t ZSTD_compressBlock_lazy2_extDict_row( |
648db22b |
2184 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
2185 | void const* src, size_t srcSize) |
648db22b |
2186 | { |
f535537f |
2187 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_rowHash, 2); |
648db22b |
2188 | } |
f535537f |
2189 | #endif |
648db22b |
2190 | |
f535537f |
2191 | #ifndef ZSTD_EXCLUDE_BTLAZY2_BLOCK_COMPRESSOR |
2192 | size_t ZSTD_compressBlock_btlazy2_extDict( |
648db22b |
2193 | ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM], |
2194 | void const* src, size_t srcSize) |
f535537f |
2195 | |
648db22b |
2196 | { |
f535537f |
2197 | return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2); |
648db22b |
2198 | } |
f535537f |
2199 | #endif |