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85923c8f30
Update zlib-ng to 2.2.1 #26113 Release: https://github.com/zlib-ng/zlib-ng/releases/tag/2.2.1 ARM diagnostics patch: https://github.com/zlib-ng/zlib-ng/pull/1774 ### Pull Request Readiness Checklist See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [x] I agree to contribute to the project under Apache 2 License. - [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV - [x] The PR is proposed to the proper branch - [ ] There is a reference to the original bug report and related work - [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable Patch to opencv_extra has the same branch name. - [ ] The feature is well documented and sample code can be built with the project CMake
285 lines
9.6 KiB
C
285 lines
9.6 KiB
C
/* match_tpl.h -- find longest match template for compare256 variants
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*
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* Copyright (C) 1995-2024 Jean-loup Gailly and Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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*
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* Portions copyright (C) 2014-2021 Konstantin Nosov
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* Fast-zlib optimized longest_match
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* https://github.com/gildor2/fast_zlib
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*/
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#ifndef MATCH_TPL_H
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#define MATCH_TPL_H
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#define EARLY_EXIT_TRIGGER_LEVEL 5
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#endif
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/* Set match_start to the longest match starting at the given string and
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* return its length. Matches shorter or equal to prev_length are discarded,
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* in which case the result is equal to prev_length and match_start is garbage.
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*
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* IN assertions: cur_match is the head of the hash chain for the current
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* string (strstart) and its distance is <= MAX_DIST, and prev_length >=1
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* OUT assertion: the match length is not greater than s->lookahead
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*/
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Z_INTERNAL uint32_t LONGEST_MATCH(deflate_state *const s, Pos cur_match) {
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unsigned int strstart = s->strstart;
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const unsigned wmask = s->w_mask;
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unsigned char *window = s->window;
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unsigned char *scan = window + strstart;
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Z_REGISTER unsigned char *mbase_start = window;
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Z_REGISTER unsigned char *mbase_end;
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const Pos *prev = s->prev;
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Pos limit;
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#ifdef LONGEST_MATCH_SLOW
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Pos limit_base;
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#else
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int32_t early_exit;
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#endif
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uint32_t chain_length, nice_match, best_len, offset;
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uint32_t lookahead = s->lookahead;
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Pos match_offset = 0;
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#ifdef UNALIGNED_OK
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uint8_t scan_start[8];
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#endif
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uint8_t scan_end[8];
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#define GOTO_NEXT_CHAIN \
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if (--chain_length && (cur_match = prev[cur_match & wmask]) > limit) \
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continue; \
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return best_len;
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/* The code is optimized for STD_MAX_MATCH-2 multiple of 16. */
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Assert(STD_MAX_MATCH == 258, "Code too clever");
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best_len = s->prev_length ? s->prev_length : STD_MIN_MATCH-1;
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/* Calculate read offset which should only extend an extra byte
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* to find the next best match length.
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*/
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offset = best_len-1;
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#ifdef UNALIGNED_OK
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if (best_len >= sizeof(uint32_t)) {
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offset -= 2;
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#ifdef UNALIGNED64_OK
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if (best_len >= sizeof(uint64_t))
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offset -= 4;
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#endif
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}
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#endif
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#ifdef UNALIGNED64_OK
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memcpy(scan_start, scan, sizeof(uint64_t));
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memcpy(scan_end, scan+offset, sizeof(uint64_t));
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#elif defined(UNALIGNED_OK)
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memcpy(scan_start, scan, sizeof(uint32_t));
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memcpy(scan_end, scan+offset, sizeof(uint32_t));
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#else
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scan_end[0] = *(scan+offset);
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scan_end[1] = *(scan+offset+1);
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#endif
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mbase_end = (mbase_start+offset);
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/* Do not waste too much time if we already have a good match */
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chain_length = s->max_chain_length;
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if (best_len >= s->good_match)
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chain_length >>= 2;
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nice_match = (uint32_t)s->nice_match;
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/* Stop when cur_match becomes <= limit. To simplify the code,
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* we prevent matches with the string of window index 0
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*/
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limit = strstart > MAX_DIST(s) ? (Pos)(strstart - MAX_DIST(s)) : 0;
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#ifdef LONGEST_MATCH_SLOW
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limit_base = limit;
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if (best_len >= STD_MIN_MATCH) {
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/* We're continuing search (lazy evaluation). */
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uint32_t i, hash;
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Pos pos;
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/* Find a most distant chain starting from scan with index=1 (index=0 corresponds
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* to cur_match). We cannot use s->prev[strstart+1,...] immediately, because
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* these strings are not yet inserted into the hash table.
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*/
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hash = s->update_hash(0, scan[1]);
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hash = s->update_hash(hash, scan[2]);
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for (i = 3; i <= best_len; i++) {
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hash = s->update_hash(hash, scan[i]);
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/* If we're starting with best_len >= 3, we can use offset search. */
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pos = s->head[hash];
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if (pos < cur_match) {
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match_offset = (Pos)(i - 2);
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cur_match = pos;
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}
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}
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/* Update offset-dependent variables */
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limit = limit_base+match_offset;
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if (cur_match <= limit)
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goto break_matching;
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mbase_start -= match_offset;
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mbase_end -= match_offset;
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}
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#else
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early_exit = s->level < EARLY_EXIT_TRIGGER_LEVEL;
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#endif
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Assert((unsigned long)strstart <= s->window_size - MIN_LOOKAHEAD, "need lookahead");
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for (;;) {
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if (cur_match >= strstart)
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break;
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/* Skip to next match if the match length cannot increase or if the match length is
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* less than 2. Note that the checks below for insufficient lookahead only occur
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* occasionally for performance reasons.
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* Therefore uninitialized memory will be accessed and conditional jumps will be made
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* that depend on those values. However the length of the match is limited to the
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* lookahead, so the output of deflate is not affected by the uninitialized values.
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*/
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#ifdef UNALIGNED_OK
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if (best_len < sizeof(uint32_t)) {
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for (;;) {
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if (zng_memcmp_2(mbase_end+cur_match, scan_end) == 0 &&
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zng_memcmp_2(mbase_start+cur_match, scan_start) == 0)
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break;
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GOTO_NEXT_CHAIN;
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}
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# ifdef UNALIGNED64_OK
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} else if (best_len >= sizeof(uint64_t)) {
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for (;;) {
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if (zng_memcmp_8(mbase_end+cur_match, scan_end) == 0 &&
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zng_memcmp_8(mbase_start+cur_match, scan_start) == 0)
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break;
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GOTO_NEXT_CHAIN;
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}
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# endif
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} else {
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for (;;) {
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if (zng_memcmp_4(mbase_end+cur_match, scan_end) == 0 &&
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zng_memcmp_4(mbase_start+cur_match, scan_start) == 0)
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break;
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GOTO_NEXT_CHAIN;
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}
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}
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#else
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for (;;) {
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if (mbase_end[cur_match] == scan_end[0] && mbase_end[cur_match+1] == scan_end[1] &&
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mbase_start[cur_match] == scan[0] && mbase_start[cur_match+1] == scan[1])
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break;
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GOTO_NEXT_CHAIN;
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}
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#endif
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uint32_t len = COMPARE256(scan+2, mbase_start+cur_match+2) + 2;
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Assert(scan+len <= window+(unsigned)(s->window_size-1), "wild scan");
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if (len > best_len) {
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uint32_t match_start = cur_match - match_offset;
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s->match_start = match_start;
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/* Do not look for matches beyond the end of the input. */
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if (len > lookahead)
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return lookahead;
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best_len = len;
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if (best_len >= nice_match)
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return best_len;
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offset = best_len-1;
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#ifdef UNALIGNED_OK
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if (best_len >= sizeof(uint32_t)) {
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offset -= 2;
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#ifdef UNALIGNED64_OK
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if (best_len >= sizeof(uint64_t))
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offset -= 4;
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#endif
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}
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#endif
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#ifdef UNALIGNED64_OK
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memcpy(scan_end, scan+offset, sizeof(uint64_t));
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#elif defined(UNALIGNED_OK)
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memcpy(scan_end, scan+offset, sizeof(uint32_t));
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#else
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scan_end[0] = *(scan+offset);
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scan_end[1] = *(scan+offset+1);
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#endif
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#ifdef LONGEST_MATCH_SLOW
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/* Look for a better string offset */
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if (UNLIKELY(len > STD_MIN_MATCH && match_start + len < strstart)) {
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Pos pos, next_pos;
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uint32_t i, hash;
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unsigned char *scan_endstr;
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/* Go back to offset 0 */
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cur_match -= match_offset;
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match_offset = 0;
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next_pos = cur_match;
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for (i = 0; i <= len - STD_MIN_MATCH; i++) {
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pos = prev[(cur_match + i) & wmask];
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if (pos < next_pos) {
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/* Hash chain is more distant, use it */
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if (pos <= limit_base + i)
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goto break_matching;
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next_pos = pos;
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match_offset = (Pos)i;
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}
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}
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/* Switch cur_match to next_pos chain */
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cur_match = next_pos;
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/* Try hash head at len-(STD_MIN_MATCH-1) position to see if we could get
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* a better cur_match at the end of string. Using (STD_MIN_MATCH-1) lets
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* us include one more byte into hash - the byte which will be checked
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* in main loop now, and which allows to grow match by 1.
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*/
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scan_endstr = scan + len - (STD_MIN_MATCH+1);
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hash = s->update_hash(0, scan_endstr[0]);
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hash = s->update_hash(hash, scan_endstr[1]);
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hash = s->update_hash(hash, scan_endstr[2]);
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pos = s->head[hash];
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if (pos < cur_match) {
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match_offset = (Pos)(len - (STD_MIN_MATCH+1));
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if (pos <= limit_base + match_offset)
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goto break_matching;
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cur_match = pos;
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}
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/* Update offset-dependent variables */
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limit = limit_base+match_offset;
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mbase_start = window-match_offset;
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mbase_end = (mbase_start+offset);
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continue;
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}
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#endif
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mbase_end = (mbase_start+offset);
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}
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#ifndef LONGEST_MATCH_SLOW
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else if (UNLIKELY(early_exit)) {
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/* The probability of finding a match later if we here is pretty low, so for
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* performance it's best to outright stop here for the lower compression levels
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*/
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break;
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}
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#endif
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GOTO_NEXT_CHAIN;
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}
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return best_len;
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#ifdef LONGEST_MATCH_SLOW
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break_matching:
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if (best_len < s->lookahead)
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return best_len;
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return s->lookahead;
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#endif
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}
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#undef LONGEST_MATCH_SLOW
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#undef LONGEST_MATCH
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#undef COMPARE256
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