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2957f5084d
* Update zlibng * Set cmake path more directly in zlibng to hopefully fix an issue with the build on drone * I'm dumb, missing / in path * Mackal helps with a dumb gitignore issue * Adding all the files, not sure what's ignoring them and im tired of looking * Some tweaks to zlibng build to hopefully get it to build properly. works on msvc now
107 lines
4.1 KiB
C
107 lines
4.1 KiB
C
/* deflate_fast.c -- compress data using the fast strategy of deflation algorithm
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*
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* Copyright (C) 1995-2013 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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#include "zbuild.h"
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#include "deflate.h"
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#include "deflate_p.h"
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#include "functable.h"
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/* ===========================================================================
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* Compress as much as possible from the input stream, return the current
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* block state.
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* This function does not perform lazy evaluation of matches and inserts
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* new strings in the dictionary only for unmatched strings or for short
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* matches. It is used only for the fast compression options.
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*/
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Z_INTERNAL block_state deflate_fast(deflate_state *s, int flush) {
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Pos hash_head; /* head of the hash chain */
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int bflush = 0; /* set if current block must be flushed */
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int64_t dist;
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uint32_t match_len = 0;
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for (;;) {
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/* Make sure that we always have enough lookahead, except
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* at the end of the input file. We need MAX_MATCH bytes
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* for the next match, plus MIN_MATCH bytes to insert the
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* string following the next match.
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*/
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if (s->lookahead < MIN_LOOKAHEAD) {
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fill_window(s);
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if (UNLIKELY(s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH)) {
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return need_more;
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}
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if (UNLIKELY(s->lookahead == 0))
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break; /* flush the current block */
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}
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/* Insert the string window[strstart .. strstart+2] in the
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* dictionary, and set hash_head to the head of the hash chain:
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*/
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if (s->lookahead >= MIN_MATCH) {
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hash_head = functable.quick_insert_string(s, s->strstart);
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dist = (int64_t)s->strstart - hash_head;
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/* Find the longest match, discarding those <= prev_length.
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* At this point we have always match length < MIN_MATCH
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*/
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if (dist <= MAX_DIST(s) && dist > 0) {
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/* To simplify the code, we prevent matches with the string
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* of window index 0 (in particular we have to avoid a match
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* of the string with itself at the start of the input file).
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*/
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match_len = functable.longest_match(s, hash_head);
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/* longest_match() sets match_start */
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}
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}
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if (match_len >= MIN_MATCH) {
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check_match(s, s->strstart, s->match_start, match_len);
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bflush = zng_tr_tally_dist(s, s->strstart - s->match_start, match_len - MIN_MATCH);
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s->lookahead -= match_len;
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/* Insert new strings in the hash table only if the match length
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* is not too large. This saves time but degrades compression.
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*/
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if (match_len <= s->max_insert_length && s->lookahead >= MIN_MATCH) {
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match_len--; /* string at strstart already in table */
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s->strstart++;
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functable.insert_string(s, s->strstart, match_len);
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s->strstart += match_len;
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} else {
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s->strstart += match_len;
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#if MIN_MATCH != 3
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functable.insert_string(s, s->strstart + 2 - MIN_MATCH, MIN_MATCH - 2);
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#else
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functable.quick_insert_string(s, s->strstart + 2 - MIN_MATCH);
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#endif
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/* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
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* matter since it will be recomputed at next deflate call.
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*/
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}
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match_len = 0;
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} else {
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/* No match, output a literal byte */
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bflush = zng_tr_tally_lit(s, s->window[s->strstart]);
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s->lookahead--;
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s->strstart++;
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}
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if (UNLIKELY(bflush))
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FLUSH_BLOCK(s, 0);
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}
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s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
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if (UNLIKELY(flush == Z_FINISH)) {
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FLUSH_BLOCK(s, 1);
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return finish_done;
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}
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if (UNLIKELY(s->sym_next))
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FLUSH_BLOCK(s, 0);
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return block_done;
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}
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