Release 4.12 lib/zlib_deflate/deflate.c
/* +++ deflate.c */
/* deflate.c -- compress data using the deflation algorithm
* Copyright (C) 1995-1996 Jean-loup Gailly.
* For conditions of distribution and use, see copyright notice in zlib.h
*/
/*
* ALGORITHM
*
* The "deflation" process depends on being able to identify portions
* of the input text which are identical to earlier input (within a
* sliding window trailing behind the input currently being processed).
*
* The most straightforward technique turns out to be the fastest for
* most input files: try all possible matches and select the longest.
* The key feature of this algorithm is that insertions into the string
* dictionary are very simple and thus fast, and deletions are avoided
* completely. Insertions are performed at each input character, whereas
* string matches are performed only when the previous match ends. So it
* is preferable to spend more time in matches to allow very fast string
* insertions and avoid deletions. The matching algorithm for small
* strings is inspired from that of Rabin & Karp. A brute force approach
* is used to find longer strings when a small match has been found.
* A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
* (by Leonid Broukhis).
* A previous version of this file used a more sophisticated algorithm
* (by Fiala and Greene) which is guaranteed to run in linear amortized
* time, but has a larger average cost, uses more memory and is patented.
* However the F&G algorithm may be faster for some highly redundant
* files if the parameter max_chain_length (described below) is too large.
*
* ACKNOWLEDGEMENTS
*
* The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
* I found it in 'freeze' written by Leonid Broukhis.
* Thanks to many people for bug reports and testing.
*
* REFERENCES
*
* Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
* Available in ftp://ds.internic.net/rfc/rfc1951.txt
*
* A description of the Rabin and Karp algorithm is given in the book
* "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
*
* Fiala,E.R., and Greene,D.H.
* Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
*
*/
#include <linux/module.h>
#include <linux/zutil.h>
#include "defutil.h"
/* ===========================================================================
* Function prototypes.
*/
typedef enum {
need_more, /* block not completed, need more input or more output */
block_done, /* block flush performed */
finish_started, /* finish started, need only more output at next deflate */
finish_done /* finish done, accept no more input or output */
} block_state;
typedef block_state (*compress_func) (deflate_state *s, int flush);
/* Compression function. Returns the block state after the call. */
static void fill_window (deflate_state *s);
static block_state deflate_stored (deflate_state *s, int flush);
static block_state deflate_fast (deflate_state *s, int flush);
static block_state deflate_slow (deflate_state *s, int flush);
static void lm_init (deflate_state *s);
static void putShortMSB (deflate_state *s, uInt b);
static void flush_pending (z_streamp strm);
static int read_buf (z_streamp strm, Byte *buf, unsigned size);
static uInt longest_match (deflate_state *s, IPos cur_match);
#ifdef DEBUG_ZLIB
static void check_match (deflate_state *s, IPos start, IPos match,
int length);
#endif
/* ===========================================================================
* Local data
*/
#define NIL 0
/* Tail of hash chains */
#ifndef TOO_FAR
# define TOO_FAR 4096
#endif
/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
/* Minimum amount of lookahead, except at the end of the input file.
* See deflate.c for comments about the MIN_MATCH+1.
*/
/* Values for max_lazy_match, good_match and max_chain_length, depending on
* the desired pack level (0..9). The values given below have been tuned to
* exclude worst case performance for pathological files. Better values may be
* found for specific files.
*/
typedef struct config_s {
ush good_length; /* reduce lazy search above this match length */
ush max_lazy; /* do not perform lazy search above this match length */
ush nice_length; /* quit search above this match length */
ush max_chain;
compress_func func;
} config;
static const config configuration_table[10] = {
/* good lazy nice chain */
/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
/* 1 */ {4, 4, 8, 4, deflate_fast}, /* maximum speed, no lazy matches */
/* 2 */ {4, 5, 16, 8, deflate_fast},
/* 3 */ {4, 6, 32, 32, deflate_fast},
/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
/* 5 */ {8, 16, 32, 32, deflate_slow},
/* 6 */ {8, 16, 128, 128, deflate_slow},
/* 7 */ {8, 32, 128, 256, deflate_slow},
/* 8 */ {32, 128, 258, 1024, deflate_slow},
/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* maximum compression */
/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
* For deflate_fast() (levels <= 3) good is ignored and lazy has a different
* meaning.
*/
#define EQUAL 0
/* result of memcmp for equal strings */
/* ===========================================================================
* Update a hash value with the given input byte
* IN assertion: all calls to UPDATE_HASH are made with consecutive
* input characters, so that a running hash key can be computed from the
* previous key instead of complete recalculation each time.
*/
#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
/* ===========================================================================
* 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.
* IN assertion: all calls 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).
*/
#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))
/* ===========================================================================
* Initialize the hash table (avoiding 64K overflow for 16 bit systems).
* prev[] will be initialized on the fly.
*/
#define CLEAR_HASH(s) \
s->head[s->hash_size-1] = NIL; \
memset((char *)s->head, 0, (unsigned)(s->hash_size-1)*sizeof(*s->head));
/* ========================================================================= */
int zlib_deflateInit2(
z_streamp strm,
int level,
int method,
int windowBits,
int memLevel,
int strategy
)
{
deflate_state *s;
int noheader = 0;
deflate_workspace *mem;
char *next;
ush *overlay;
/* We overlay pending_buf and d_buf+l_buf. This works since the average
* output size for (length,distance) codes is <= 24 bits.
*/
if (strm == NULL) return Z_STREAM_ERROR;
strm->msg = NULL;
if (level == Z_DEFAULT_COMPRESSION) level = 6;
mem = (deflate_workspace *) strm->workspace;
if (windowBits < 0) { /* undocumented feature: suppress zlib header */
noheader = 1;
windowBits = -windowBits;
}
if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
windowBits < 9 || windowBits > 15 || level < 0 || level > 9 ||
strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
return Z_STREAM_ERROR;
}
/*
* Direct the workspace's pointers to the chunks that were allocated
* along with the deflate_workspace struct.
*/
next = (char *) mem;
next += sizeof(*mem);
mem->window_memory = (Byte *) next;
next += zlib_deflate_window_memsize(windowBits);
mem->prev_memory = (Pos *) next;
next += zlib_deflate_prev_memsize(windowBits);
mem->head_memory = (Pos *) next;
next += zlib_deflate_head_memsize(memLevel);
mem->overlay_memory = next;
s = (deflate_state *) &(mem->deflate_memory);
strm->state = (struct internal_state *)s;
s->strm = strm;
s->noheader = noheader;
s->w_bits = windowBits;
s->w_size = 1 << s->w_bits;
s->w_mask = s->w_size - 1;
s->hash_bits = memLevel + 7;
s->hash_size = 1 << s->hash_bits;
s->hash_mask = s->hash_size - 1;
s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
s->window = (Byte *) mem->window_memory;
s->prev = (Pos *) mem->prev_memory;
s->head = (Pos *) mem->head_memory;
s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
overlay = (ush *) mem->overlay_memory;
s->pending_buf = (uch *) overlay;
s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
s->level = level;
s->strategy = strategy;
s->method = (Byte)method;
return zlib_deflateReset(strm);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 381 | 80.21% | 1 | 14.29% |
| James Keniston | 78 | 16.42% | 1 | 14.29% |
| Jörn Engel | 9 | 1.89% | 3 | 42.86% |
| Steven Cole | 6 | 1.26% | 1 | 14.29% |
| Richard Purdie | 1 | 0.21% | 1 | 14.29% |
| Total | 475 | 100.00% | 7 | 100.00% |
/* ========================================================================= */
int zlib_deflateReset(
z_streamp strm
)
{
deflate_state *s;
if (strm == NULL || strm->state == NULL)
return Z_STREAM_ERROR;
strm->total_in = strm->total_out = 0;
strm->msg = NULL;
strm->data_type = Z_UNKNOWN;
s = (deflate_state *)strm->state;
s->pending = 0;
s->pending_out = s->pending_buf;
if (s->noheader < 0) {
s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
}
s->status = s->noheader ? BUSY_STATE : INIT_STATE;
strm->adler = 1;
s->last_flush = Z_NO_FLUSH;
zlib_tr_init(s);
lm_init(s);
return Z_OK;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 123 | 96.85% | 1 | 33.33% |
| Jörn Engel | 3 | 2.36% | 1 | 33.33% |
| Steven Cole | 1 | 0.79% | 1 | 33.33% |
| Total | 127 | 100.00% | 3 | 100.00% |
/* =========================================================================
* Put a short in the pending buffer. The 16-bit value is put in MSB order.
* IN assertion: the stream state is correct and there is enough room in
* pending_buf.
*/
static void putShortMSB(
deflate_state *s,
uInt b
)
{
put_byte(s, (Byte)(b >> 8));
put_byte(s, (Byte)(b & 0xff));
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 29 | 70.73% | 1 | 33.33% |
| Adrian Bunk | 10 | 24.39% | 1 | 33.33% |
| Steven Cole | 2 | 4.88% | 1 | 33.33% |
| Total | 41 | 100.00% | 3 | 100.00% |
/* =========================================================================
* Flush as much pending output as possible. All deflate() output goes
* through this function so some applications may wish to modify it
* to avoid allocating a large strm->next_out buffer and copying into it.
* (See also read_buf()).
*/
static void flush_pending(
z_streamp strm
)
{
deflate_state *s = (deflate_state *) strm->state;
unsigned len = s->pending;
if (len > strm->avail_out) len = strm->avail_out;
if (len == 0) return;
if (strm->next_out != NULL) {
memcpy(strm->next_out, s->pending_out, len);
strm->next_out += len;
}
s->pending_out += len;
strm->total_out += len;
strm->avail_out -= len;
s->pending -= len;
if (s->pending == 0) {
s->pending_out = s->pending_buf;
}
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 117 | 97.50% | 1 | 25.00% |
| Jörn Engel | 2 | 1.67% | 2 | 50.00% |
| Steven Cole | 1 | 0.83% | 1 | 25.00% |
| Total | 120 | 100.00% | 4 | 100.00% |
/* ========================================================================= */
int zlib_deflate(
z_streamp strm,
int flush
)
{
int old_flush; /* value of flush param for previous deflate call */
deflate_state *s;
if (strm == NULL || strm->state == NULL ||
flush > Z_FINISH || flush < 0) {
return Z_STREAM_ERROR;
}
s = (deflate_state *) strm->state;
if ((strm->next_in == NULL && strm->avail_in != 0) ||
(s->status == FINISH_STATE && flush != Z_FINISH)) {
return Z_STREAM_ERROR;
}
if (strm->avail_out == 0) return Z_BUF_ERROR;
s->strm = strm; /* just in case */
old_flush = s->last_flush;
s->last_flush = flush;
/* Write the zlib header */
if (s->status == INIT_STATE) {
uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
uInt level_flags = (s->level-1) >> 1;
if (level_flags > 3) level_flags = 3;
header |= (level_flags << 6);
if (s->strstart != 0) header |= PRESET_DICT;
header += 31 - (header % 31);
s->status = BUSY_STATE;
putShortMSB(s, header);
/* Save the adler32 of the preset dictionary: */
if (s->strstart != 0) {
putShortMSB(s, (uInt)(strm->adler >> 16));
putShortMSB(s, (uInt)(strm->adler & 0xffff));
}
strm->adler = 1L;
}
/* Flush as much pending output as possible */
if (s->pending != 0) {
flush_pending(strm);
if (strm->avail_out == 0) {
/* Since avail_out is 0, deflate will be called again with
* more output space, but possibly with both pending and
* avail_in equal to zero. There won't be anything to do,
* but this is not an error situation so make sure we
* return OK instead of BUF_ERROR at next call of deflate:
*/
s->last_flush = -1;
return Z_OK;
}
/* Make sure there is something to do and avoid duplicate consecutive
* flushes. For repeated and useless calls with Z_FINISH, we keep
* returning Z_STREAM_END instead of Z_BUFF_ERROR.
*/
} else if (strm->avail_in == 0 && flush <= old_flush &&
flush != Z_FINISH) {
return Z_BUF_ERROR;
}
/* User must not provide more input after the first FINISH: */
if (s->status == FINISH_STATE && strm->avail_in != 0) {
return Z_BUF_ERROR;
}
/* Start a new block or continue the current one.
*/
if (strm->avail_in != 0 || s->lookahead != 0 ||
(flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
block_state bstate;
bstate = (*(configuration_table[s->level].func))(s, flush);
if (bstate == finish_started || bstate == finish_done) {
s->status = FINISH_STATE;
}
if (bstate == need_more || bstate == finish_started) {
if (strm->avail_out == 0) {
s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
}
return Z_OK;
/* If flush != Z_NO_FLUSH && avail_out == 0, the next call
* of deflate should use the same flush parameter to make sure
* that the flush is complete. So we don't have to output an
* empty block here, this will be done at next call. This also
* ensures that for a very small output buffer, we emit at most
* one empty block.
*/
}
if (bstate == block_done) {
if (flush == Z_PARTIAL_FLUSH) {
zlib_tr_align(s);
} else if (flush == Z_PACKET_FLUSH) {
/* Output just the 3-bit `stored' block type value,
but not a zero length. */
zlib_tr_stored_type_only(s);
} else { /* FULL_FLUSH or SYNC_FLUSH */
zlib_tr_stored_block(s, (char*)0, 0L, 0);
/* For a full flush, this empty block will be recognized
* as a special marker by inflate_sync().
*/
if (flush == Z_FULL_FLUSH) {
CLEAR_HASH(s); /* forget history */
}
}
flush_pending(strm);
if (strm->avail_out == 0) {
s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
return Z_OK;
}
}
}
Assert(strm->avail_out > 0, "bug2");
if (flush != Z_FINISH) return Z_OK;
if (s->noheader) return Z_STREAM_END;
/* Write the zlib trailer (adler32) */
putShortMSB(s, (uInt)(strm->adler >> 16));
putShortMSB(s, (uInt)(strm->adler & 0xffff));
flush_pending(strm);
/* If avail_out is zero, the application will call deflate again
* to flush the rest.
*/
s->noheader = -1; /* write the trailer only once! */
return s->pending != 0 ? Z_OK : Z_STREAM_END;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 627 | 99.21% | 1 | 33.33% |
| Jörn Engel | 3 | 0.47% | 1 | 33.33% |
| Steven Cole | 2 | 0.32% | 1 | 33.33% |
| Total | 632 | 100.00% | 3 | 100.00% |
/* ========================================================================= */
int zlib_deflateEnd(
z_streamp strm
)
{
int status;
deflate_state *s;
if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
s = (deflate_state *) strm->state;
status = s->status;
if (status != INIT_STATE && status != BUSY_STATE &&
status != FINISH_STATE) {
return Z_STREAM_ERROR;
}
strm->state = NULL;
return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 76 | 95.00% | 1 | 33.33% |
| Jörn Engel | 3 | 3.75% | 1 | 33.33% |
| Steven Cole | 1 | 1.25% | 1 | 33.33% |
| Total | 80 | 100.00% | 3 | 100.00% |
/* ===========================================================================
* Read a new buffer from the current input stream, update the adler32
* and total number of bytes read. All deflate() input goes through
* this function so some applications may wish to modify it to avoid
* allocating a large strm->next_in buffer and copying from it.
* (See also flush_pending()).
*/
static int read_buf(
z_streamp strm,
Byte *buf,
unsigned size
)
{
unsigned len = strm->avail_in;
if (len > size) len = size;
if (len == 0) return 0;
strm->avail_in -= len;
if (!((deflate_state *)(strm->state))->noheader) {
strm->adler = zlib_adler32(strm->adler, strm->next_in, len);
}
memcpy(buf, strm->next_in, len);
strm->next_in += len;
strm->total_in += len;
return (int)len;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 108 | 95.58% | 1 | 25.00% |
| Steven Cole | 3 | 2.65% | 1 | 25.00% |
| Jörn Engel | 2 | 1.77% | 2 | 50.00% |
| Total | 113 | 100.00% | 4 | 100.00% |
/* ===========================================================================
* Initialize the "longest match" routines for a new zlib stream
*/
static void lm_init(
deflate_state *s
)
{
s->window_size = (ulg)2L*s->w_size;
CLEAR_HASH(s);
/* Set the default configuration parameters:
*/
s->max_lazy_match = configuration_table[s->level].max_lazy;
s->good_match = configuration_table[s->level].good_length;
s->nice_match = configuration_table[s->level].nice_length;
s->max_chain_length = configuration_table[s->level].max_chain;
s->strstart = 0;
s->block_start = 0L;
s->lookahead = 0;
s->match_length = s->prev_length = MIN_MATCH-1;
s->match_available = 0;
s->ins_h = 0;
}
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| Linus Torvalds | 121 | 98.37% | 1 | 33.33% |
| Steven Cole | 1 | 0.81% | 1 | 33.33% |
| Jörn Engel | 1 | 0.81% | 1 | 33.33% |
| Total | 123 | 100.00% | 3 | 100.00% |
/* ===========================================================================
* Set match_start to the longest match starting at the given string and
* return its length. Matches shorter or equal to prev_length are discarded,
* in which case the result is equal to prev_length and match_start is
* garbage.
* IN assertions: cur_match is the head of the hash chain for the current
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
* OUT assertion: the match length is not greater than s->lookahead.
*/
/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
* match.S. The code will be functionally equivalent.
*/
static uInt longest_match(
deflate_state *s,
IPos cur_match /* current match */
)
{
unsigned chain_length = s->max_chain_length;/* max hash chain length */
register Byte *scan = s->window + s->strstart; /* current string */
register Byte *match; /* matched string */
register int len; /* length of current match */
int best_len = s->prev_length; /* best match length so far */
int nice_match = s->nice_match; /* stop if match long enough */
IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
s->strstart - (IPos)MAX_DIST(s) : NIL;
/* Stop when cur_match becomes <= limit. To simplify the code,
* we prevent matches with the string of window index 0.
*/
Pos *prev = s->prev;
uInt wmask = s->w_mask;
#ifdef UNALIGNED_OK
/* Compare two bytes at a time. Note: this is not always beneficial.
* Try with and without -DUNALIGNED_OK to check.
*/
register Byte *strend = s->window + s->strstart + MAX_MATCH - 1;
register ush scan_start = *(ush*)scan;
register ush scan_end = *(ush*)(scan+best_len-1);
#else
register Byte *strend = s->window + s->strstart + MAX_MATCH;
register Byte scan_end1 = scan[best_len-1];
register Byte scan_end = scan[best_len];
#endif
/* 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");
/* Do not waste too much time if we already have a good match: */
if (s->prev_length >= s->good_match) {
chain_length >>= 2;
}
/* Do not look for matches beyond the end of the input. This is necessary
* to make deflate deterministic.
*/
if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
do {
Assert(cur_match < s->strstart, "no future");
match = s->window + cur_match;
/* Skip to next match if the match length cannot increase
* or if the match length is less than 2:
*/
#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
/* This code assumes sizeof(unsigned short) == 2. Do not use
* UNALIGNED_OK if your compiler uses a different size.
*/
if (*(ush*)(match+best_len-1) != scan_end ||
*(ush*)match != scan_start) continue;
/* 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. Compare 2 bytes at a time at
* strstart+3, +5, ... up to strstart+257. We check for insufficient
* lookahead only every 4th comparison; the 128th check will be made
* at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
* necessary to put more guard bytes at the end of the window, or
* to check more often for insufficient lookahead.
*/
Assert(scan[2] == match[2], "scan[2]?");
scan++, match++;
do {
} while (*(ush*)(scan+=2) == *(ush*)(match+=2) &&
*(ush*)(scan+=2) == *(ush*)(match+=2) &&
*(ush*)(scan+=2) == *(ush*)(match+=2) &&
*(ush*)(scan+=2) == *(ush*)(match+=2) &&
scan < strend);
/* The funny "do {}" generates better code on most compilers */
/* Here, scan <= window+strstart+257 */
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
if (*scan == *match) scan++;
len = (MAX_MATCH - 1) - (int)(strend-scan);
scan = strend - (MAX_MATCH-1);
#else /* UNALIGNED_OK */
if (match[best_len] != scan_end ||
match[best_len-1] != scan_end1 ||
*match != *scan ||
*++match != scan[1]) continue;
/* 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++;
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);
scan = strend - MAX_MATCH;
#endif /* UNALIGNED_OK */
if (len > best_len) {
s->match_start = cur_match;
best_len = len;
if (len >= nice_match) break;
#ifdef UNALIGNED_OK
scan_end = *(ush*)(scan+best_len-1);
#else
scan_end1 = scan[best_len-1];
scan_end = scan[best_len];
#endif
}
} while ((cur_match = prev[cur_match & wmask]) > limit
&& --chain_length != 0);
if ((uInt)best_len <= s->lookahead) return best_len;
return s->lookahead;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Linus Torvalds | 765 | 97.33% | 1 | 25.00% |
| Jörn Engel | 19 | 2.42% | 2 | 50.00% |
| Steven Cole | 2 | 0.25% | 1 | 25.00% |
| Total | 786 | 100.00% | 4 | 100.00% |
#ifdef DEBUG_ZLIB
/* ===========================================================================
* Check that the match at match_start is indeed a match.
*/
static void check_match(
deflate_state *s,
IPos start,
IPos match,
int length
)
{
/* check that the match is indeed a match */
if (memcmp((char *)s->window + match,
(char *)s->window + start, length) != EQUAL) {
fprintf(stderr, " start %u, match %u, length %d\n",
start, match, length);
do {
fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
}