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zlib 1.1.0

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This commit is contained in:
Mark Adler
2011-09-09 23:19:55 -07:00
parent b8c9ecb076
commit 965fe72aed
17 changed files with 262 additions and 68 deletions
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93
deflate.c
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@@ -52,7 +52,7 @@
#include "deflate.h"
const char deflate_copyright[] =
" deflate 1.0.9 Copyright 1995-1998 Jean-loup Gailly ";
" deflate 1.1.0 Copyright 1995-1998 Jean-loup Gailly ";
/*
If you use the zlib library in a product, an acknowledgment is welcome
in the documentation of your product. If for some reason you cannot
@@ -160,14 +160,23 @@ struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
* Insert string str in the dictionary and set match_head to the previous head
* of the hash chain (the most recent string with same hash key). Return
* the previous length of the hash chain.
* If this file is compiled with -DFASTEST, the compression level is forced
* to 1, and no hash chains are maintained.
* IN assertion: all calls to to INSERT_STRING are made with consecutive
* input characters and the first MIN_MATCH bytes of str are valid
* (except for the last MIN_MATCH-1 bytes of the input file).
*/
#ifdef FASTEST
#define INSERT_STRING(s, str, match_head) \
(UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
match_head = s->head[s->ins_h], \
s->head[s->ins_h] = (Pos)(str))
#else
#define INSERT_STRING(s, str, match_head) \
(UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
s->prev[(str) & s->w_mask] = match_head = s->head[s->ins_h], \
s->head[s->ins_h] = (Pos)(str))
#endif
/* ===========================================================================
* Initialize the hash table (avoiding 64K overflow for 16 bit systems).
@@ -224,6 +233,9 @@ int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
if (strm->zfree == Z_NULL) strm->zfree = zcfree;
if (level == Z_DEFAULT_COMPRESSION) level = 6;
#ifdef FASTEST
level = 1;
#endif
if (windowBits < 0) { /* undocumented feature: suppress zlib header */
noheader = 1;
@@ -708,6 +720,7 @@ local void lm_init (s)
/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
* match.S. The code will be functionally equivalent.
*/
#ifndef FASTEST
local uInt longest_match(s, cur_match)
deflate_state *s;
IPos cur_match; /* current match */
@@ -845,6 +858,64 @@ local uInt longest_match(s, cur_match)
if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
return s->lookahead;
}
#else /* FASTEST */
/* ---------------------------------------------------------------------------
* Optimized version for level == 1 only
*/
local uInt longest_match(s, cur_match)
deflate_state *s;
IPos cur_match; /* current match */
{
register Bytef *scan = s->window + s->strstart; /* current string */
register Bytef *match; /* matched string */
register int len; /* length of current match */
register Bytef *strend = s->window + s->strstart + MAX_MATCH;
/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
* It is easy to get rid of this optimization if necessary.
*/
Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
Assert(cur_match < s->strstart, "no future");
match = s->window + cur_match;
/* Return failure if the match length is less than 2:
*/
if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
/* The check at best_len-1 can be removed because it will be made
* again later. (This heuristic is not always a win.)
* It is not necessary to compare scan[2] and match[2] since they
* are always equal when the other bytes match, given that
* the hash keys are equal and that HASH_BITS >= 8.
*/
scan += 2, match += 2;
Assert(*scan == *match, "match[2]?");
/* We check for insufficient lookahead only every 8th comparison;
* the 256th check will be made at strstart+258.
*/
do {
} while (*++scan == *++match && *++scan == *++match &&
*++scan == *++match && *++scan == *++match &&
*++scan == *++match && *++scan == *++match &&
*++scan == *++match && *++scan == *++match &&
scan < strend);
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
len = MAX_MATCH - (int)(strend - scan);
if (len < MIN_MATCH) return MIN_MATCH - 1;
s->match_start = cur_match;
return len <= s->lookahead ? len : s->lookahead;
}
#endif /* FASTEST */
#endif /* ASMV */
#ifdef DEBUG
@@ -930,6 +1001,7 @@ local void fill_window(s)
} while (--n);
n = wsize;
#ifndef FASTEST
p = &s->prev[n];
do {
m = *--p;
@@ -938,6 +1010,7 @@ local void fill_window(s)
* its value will never be used.
*/
} while (--n);
#endif
more += wsize;
}
if (s->strm->avail_in == 0) return;
@@ -1105,14 +1178,15 @@ local block_state deflate_fast(s, flush)
if (s->match_length >= MIN_MATCH) {
check_match(s, s->strstart, s->match_start, s->match_length);
bflush = _tr_tally(s, s->strstart - s->match_start,
s->match_length - MIN_MATCH);
_tr_tally_dist(s, s->strstart - s->match_start,
s->match_length - MIN_MATCH, bflush);
s->lookahead -= s->match_length;
/* Insert new strings in the hash table only if the match length
* is not too large. This saves time but degrades compression.
*/
#ifndef FASTEST
if (s->match_length <= s->max_insert_length &&
s->lookahead >= MIN_MATCH) {
s->match_length--; /* string at strstart already in hash table */
@@ -1124,7 +1198,9 @@ local block_state deflate_fast(s, flush)
*/
} while (--s->match_length != 0);
s->strstart++;
} else {
} else
#endif
{
s->strstart += s->match_length;
s->match_length = 0;
s->ins_h = s->window[s->strstart];
@@ -1139,7 +1215,7 @@ local block_state deflate_fast(s, flush)
} else {
/* No match, output a literal byte */
Tracevv((stderr,"%c", s->window[s->strstart]));
bflush = _tr_tally (s, 0, s->window[s->strstart]);
_tr_tally_lit (s, s->window[s->strstart], bflush);
s->lookahead--;
s->strstart++;
}
@@ -1219,7 +1295,7 @@ local block_state deflate_slow(s, flush)
check_match(s, s->strstart-1, s->prev_match, s->prev_length);
bflush = _tr_tally(s, s->strstart -1 - s->prev_match,
s->prev_length - MIN_MATCH);
s->prev_length - MIN_MATCH);
/* Insert in hash table all strings up to the end of the match.
* strstart-1 and strstart are already inserted. If there is not
@@ -1245,7 +1321,8 @@ local block_state deflate_slow(s, flush)
* is longer, truncate the previous match to a single literal.
*/
Tracevv((stderr,"%c", s->window[s->strstart-1]));
if (_tr_tally (s, 0, s->window[s->strstart-1])) {
_tr_tally_lit(s, s->window[s->strstart-1], bflush);
if (bflush) {
FLUSH_BLOCK_ONLY(s, 0);
}
s->strstart++;
@@ -1263,7 +1340,7 @@ local block_state deflate_slow(s, flush)
Assert (flush != Z_NO_FLUSH, "no flush?");
if (s->match_available) {
Tracevv((stderr,"%c", s->window[s->strstart-1]));
_tr_tally (s, 0, s->window[s->strstart-1]);
_tr_tally_lit(s, s->window[s->strstart-1], bflush);
s->match_available = 0;
}
FLUSH_BLOCK(s, flush == Z_FINISH);