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/* deflate.c -- compress data using the deflation algorithm
* Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler
* 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 http://tools.ietf.org/html/rfc1951
*
* 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
*
*/
/* @(#) $Id$ */
#include <assert.h>
#include "deflate.h"
#include "x86.h"
#if defined(CRC32_SIMD_SSE42_PCLMUL)
#include <smmintrin.h>
#endif
#if (defined(__ARM_NEON__) || defined(__ARM_NEON)) || defined(STARBOARD)
#include "contrib/optimizations/slide_hash_neon.h"
#endif
/* We need crypto extension crc32 to implement optimized hash in
* insert_string.
*/
#if defined(CRC32_ARMV8_CRC32)
#include "arm_features.h"
#include "crc32_simd.h"
#endif
#if defined(STARBOARD)
#include "arm_features.h"
#endif
const char deflate_copyright[] =
" deflate 1.2.11 Copyright 1995-2017 Jean-loup Gailly and Mark Adler ";
/*
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
include such an acknowledgment, I would appreciate that you keep this
copyright string in the executable of your product.
*/
/* ===========================================================================
* 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) OF((deflate_state *s, int flush));
/* Compression function. Returns the block state after the call. */
local int deflateStateCheck OF((z_streamp strm));
local void slide_hash OF((deflate_state *s));
local void fill_window OF((deflate_state *s));
local block_state deflate_stored OF((deflate_state *s, int flush));
local block_state deflate_fast OF((deflate_state *s, int flush));
#ifndef FASTEST
local block_state deflate_slow OF((deflate_state *s, int flush));
#endif
local block_state deflate_rle OF((deflate_state *s, int flush));
local block_state deflate_huff OF((deflate_state *s, int flush));
local void lm_init OF((deflate_state *s));
local void putShortMSB OF((deflate_state *s, uInt b));
local void flush_pending OF((z_streamp strm));
unsigned ZLIB_INTERNAL deflate_read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
#ifdef ASMV
# pragma message("Assembler code may have bugs -- use at your own risk")
void match_init OF((void)); /* asm code initialization */
uInt longest_match OF((deflate_state *s, IPos cur_match));
#else
local uInt longest_match OF((deflate_state *s, IPos cur_match));
#endif
#ifdef ZLIB_DEBUG
local void check_match OF((deflate_state *s, IPos start, IPos match,
int length));
#endif
/* From crc32.c */
extern void ZLIB_INTERNAL crc_reset(deflate_state *const s);
extern void ZLIB_INTERNAL crc_finalize(deflate_state *const s);
extern void ZLIB_INTERNAL copy_with_crc(z_streamp strm, Bytef *dst, long size);
#ifdef _MSC_VER
#define INLINE __inline
#else
#define INLINE inline
#endif
/* Intel optimized insert_string. */
#if defined(CRC32_SIMD_SSE42_PCLMUL)
#if defined(__GNUC__) || defined(__clang__)
__attribute__((target("sse4.2")))
#endif
local INLINE Pos insert_string_sse(deflate_state *const s, const Pos str)
{
Pos ret;
unsigned *ip, val, h = 0;
ip = (unsigned *)&s->window[str];
val = *ip;
if (s->level >= 6)
val &= 0xFFFFFF;
h = _mm_crc32_u32(h, val);
ret = s->head[h & s->hash_mask];
s->head[h & s->hash_mask] = str;
s->prev[str & s->w_mask] = ret;
return ret;
}
#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 */
/* 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;
#ifdef FASTEST
local const config configuration_table[2] = {
/* good lazy nice chain */
/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
/* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
#else
local 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}, /* max 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}}; /* max compression */
#endif
/* 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.
*/
/* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
#define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0))
/* ===========================================================================
* 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.
* 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 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).
*/
local INLINE Pos insert_string_c(deflate_state *const s, const Pos str)
{
Pos ret;
UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]);
#ifdef FASTEST
ret = s->head[s->ins_h];
#else
ret = s->prev[str & s->w_mask] = s->head[s->ins_h];
#endif
s->head[s->ins_h] = str;
return ret;
}
local INLINE Pos insert_string(deflate_state *const s, const Pos str)
{
/* String dictionary insertion: faster symbol hashing has a positive impact
* on data compression speeds (around 20% on Intel and 36% on ARM Cortex big
* cores).
* A misfeature is that the generated compressed output will differ from
* vanilla zlib (even though it is still valid 'DEFLATE-d' content).
*
* We offer here a way to disable the optimization if there is the expectation
* that compressed content should match when compared to vanilla zlib.
*/
#if !defined(CHROMIUM_ZLIB_NO_CASTAGNOLI)
#if defined(CRC32_ARMV8_CRC32)
if (arm_cpu_enable_crc32)
return insert_string_arm(s, str);
#elif defined(CRC32_SIMD_SSE42_PCLMUL)
if (x86_cpu_enable_simd)
return insert_string_sse(s, str);
#endif
#endif
return insert_string_c(s, 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; \
zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
/* ===========================================================================
* Slide the hash table when sliding the window down (could be avoided with 32
* bit values at the expense of memory usage). We slide even when level == 0 to
* keep the hash table consistent if we switch back to level > 0 later.
*/
local void slide_hash(s)
deflate_state *s;
{
#if (defined(__ARM_NEON__) || defined(__ARM_NEON)) || defined(STARBOARD)
#if defined(STARBOARD)
if (arm_cpu_enable_neon) {
/* NEON based hash table rebase. */
neon_slide_hash(s->head, s->prev, s->w_size, s->hash_size);
return;
}
#else
/* NEON based hash table rebase. */
return neon_slide_hash(s->head, s->prev, s->w_size, s->hash_size);
#endif
#endif
unsigned n, m;
Posf *p;
uInt wsize = s->w_size;
n = s->hash_size;
p = &s->head[n];
do {
m = *--p;
*p = (Pos)(m >= wsize ? m - wsize : NIL);
} while (--n);
n = wsize;
#ifndef FASTEST
p = &s->prev[n];
do {
m = *--p;
*p = (Pos)(m >= wsize ? m - wsize : NIL);
/* If n is not on any hash chain, prev[n] is garbage but
* its value will never be used.
*/
} while (--n);
#endif
}
/* ========================================================================= */
int ZEXPORT deflateInit_(strm, level, version, stream_size)
z_streamp strm;
int level;
const char *version;
int stream_size;
{
return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
Z_DEFAULT_STRATEGY, version, stream_size);
/* To do: ignore strm->next_in if we use it as window */
}
/* ========================================================================= */
int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
version, stream_size)
z_streamp strm;
int level;
int method;
int windowBits;
int memLevel;
int strategy;
const char *version;
int stream_size;
{
unsigned window_padding = 8;
deflate_state *s;
int wrap = 1;
static const char my_version[] = ZLIB_VERSION;
// Needed to activate optimized insert_string() that helps compression
// for all wrapper formats (e.g. RAW, ZLIB, GZIP).
// Feature detection is not triggered while using RAW mode (i.e. we never
// call crc32() with a NULL buffer).
#if defined(CRC32_ARMV8_CRC32)
arm_check_features();
#elif defined(CRC32_SIMD_SSE42_PCLMUL)
x86_check_features();
#endif
if (version == Z_NULL || version[0] != my_version[0] ||
stream_size != sizeof(z_stream)) {
return Z_VERSION_ERROR;
}
if (strm == Z_NULL) return Z_STREAM_ERROR;
strm->msg = Z_NULL;
if (strm->zalloc == (alloc_func)0) {
#ifdef Z_SOLO
return Z_STREAM_ERROR;
#else
strm->zalloc = zcalloc;
strm->opaque = (voidpf)0;
#endif
}
if (strm->zfree == (free_func)0)
#ifdef Z_SOLO
return Z_STREAM_ERROR;
#else
strm->zfree = zcfree;
#endif
#ifdef FASTEST
if (level != 0) level = 1;
#else
if (level == Z_DEFAULT_COMPRESSION) level = 6;
#endif
if (windowBits < 0) { /* suppress zlib wrapper */
wrap = 0;
windowBits = -windowBits;
}
#ifdef GZIP
else if (windowBits > 15) {
wrap = 2; /* write gzip wrapper instead */
windowBits -= 16;
}
#endif
if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) {
return Z_STREAM_ERROR;
}
if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
if (s == Z_NULL) return Z_MEM_ERROR;
strm->state = (struct internal_state FAR *)s;
s->strm = strm;
s->status = INIT_STATE; /* to pass state test in deflateReset() */
s->wrap = wrap;
s->gzhead = Z_NULL;
s->w_bits = (uInt)windowBits;
s->w_size = 1 << s->w_bits;
s->w_mask = s->w_size - 1;
if (x86_cpu_enable_simd) {
s->hash_bits = 15;
} else {
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 = (Bytef *) ZALLOC(strm,
s->w_size + window_padding,
2*sizeof(Byte));
s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
s->high_water = 0; /* nothing written to s->window yet */
s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
/* We overlay pending_buf and sym_buf. This works since the average size
* for length/distance pairs over any compressed block is assured to be 31
* bits or less.
*
* Analysis: The longest fixed codes are a length code of 8 bits plus 5
* extra bits, for lengths 131 to 257. The longest fixed distance codes are
* 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest
* possible fixed-codes length/distance pair is then 31 bits total.
*
* sym_buf starts one-fourth of the way into pending_buf. So there are
* three bytes in sym_buf for every four bytes in pending_buf. Each symbol
* in sym_buf is three bytes -- two for the distance and one for the
* literal/length. As each symbol is consumed, the pointer to the next
* sym_buf value to read moves forward three bytes. From that symbol, up to
* 31 bits are written to pending_buf. The closest the written pending_buf
* bits gets to the next sym_buf symbol to read is just before the last
* code is written. At that time, 31*(n-2) bits have been written, just
* after 24*(n-2) bits have been consumed from sym_buf. sym_buf starts at
* 8*n bits into pending_buf. (Note that the symbol buffer fills when n-1
* symbols are written.) The closest the writing gets to what is unread is
* then n+14 bits. Here n is lit_bufsize, which is 16384 by default, and
* can range from 128 to 32768.
*
* Therefore, at a minimum, there are 142 bits of space between what is
* written and what is read in the overlain buffers, so the symbols cannot
* be overwritten by the compressed data. That space is actually 139 bits,
* due to the three-bit fixed-code block header.
*
* That covers the case where either Z_FIXED is specified, forcing fixed
* codes, or when the use of fixed codes is chosen, because that choice
* results in a smaller compressed block than dynamic codes. That latter
* condition then assures that the above analysis also covers all dynamic
* blocks. A dynamic-code block will only be chosen to be emitted if it has
* fewer bits than a fixed-code block would for the same set of symbols.
* Therefore its average symbol length is assured to be less than 31. So
* the compressed data for a dynamic block also cannot overwrite the
* symbols from which it is being constructed.
*/
s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4);
s->pending_buf_size = (ulg)s->lit_bufsize * 4;
if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
s->pending_buf == Z_NULL) {
s->status = FINISH_STATE;
strm->msg = ERR_MSG(Z_MEM_ERROR);
deflateEnd (strm);
return Z_MEM_ERROR;
}
s->sym_buf = s->pending_buf + s->lit_bufsize;
s->sym_end = (s->lit_bufsize - 1) * 3;
/* We avoid equality with lit_bufsize*3 because of wraparound at 64K
* on 16 bit machines and because stored blocks are restricted to
* 64K-1 bytes.
*/
s->level = level;
s->strategy = strategy;
s->method = (Byte)method;
return deflateReset(strm);
}
/* =========================================================================
* Check for a valid deflate stream state. Return 0 if ok, 1 if not.
*/
local int deflateStateCheck (strm)
z_streamp strm;
{
deflate_state *s;
if (strm == Z_NULL ||
strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0)
return 1;
s = strm->state;
if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE &&
#ifdef GZIP
s->status != GZIP_STATE &&
#endif
s->status != EXTRA_STATE &&
s->status != NAME_STATE &&
s->status != COMMENT_STATE &&
s->status != HCRC_STATE &&
s->status != BUSY_STATE &&
s->status != FINISH_STATE))
return 1;
return 0;
}
/* ========================================================================= */
int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
z_streamp strm;
const Bytef *dictionary;
uInt dictLength;
{
deflate_state *s;
uInt str, n;
int wrap;
unsigned avail;
z_const unsigned char *next;
if (deflateStateCheck(strm) || dictionary == Z_NULL)
return Z_STREAM_ERROR;
s = strm->state;
wrap = s->wrap;
if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
return Z_STREAM_ERROR;
/* when using zlib wrappers, compute Adler-32 for provided dictionary */
if (wrap == 1)
strm->adler = adler32(strm->adler, dictionary, dictLength);
s->wrap = 0; /* avoid computing Adler-32 in deflate_read_buf */
/* if dictionary would fill window, just replace the history */
if (dictLength >= s->w_size) {
if (wrap == 0) { /* already empty otherwise */
CLEAR_HASH(s);
s->strstart = 0;
s->block_start = 0L;
s->insert = 0;
}
dictionary += dictLength - s->w_size; /* use the tail */
dictLength = s->w_size;
}
/* insert dictionary into window and hash */
avail = strm->avail_in;
next = strm->next_in;
strm->avail_in = dictLength;
strm->next_in = (z_const Bytef *)dictionary;
fill_window(s);
while (s->lookahead >= MIN_MATCH) {
str = s->strstart;
n = s->lookahead - (MIN_MATCH-1);
do {
insert_string(s, str);
str++;
} while (--n);
s->strstart = str;
s->lookahead = MIN_MATCH-1;
fill_window(s);
}
s->strstart += s->lookahead;
s->block_start = (long)s->strstart;
s->insert = s->lookahead;
s->lookahead = 0;
s->match_length = s->prev_length = MIN_MATCH-1;
s->match_available = 0;
strm->next_in = next;
strm->avail_in = avail;
s->wrap = wrap;
return Z_OK;
}
/* ========================================================================= */
int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength)
z_streamp strm;
Bytef *dictionary;
uInt *dictLength;
{
deflate_state *s;
uInt len;
if (deflateStateCheck(strm))
return Z_STREAM_ERROR;
s = strm->state;
len = s->strstart + s->lookahead;
if (len > s->w_size)
len = s->w_size;
if (dictionary != Z_NULL && len)
zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len);
if (dictLength != Z_NULL)
*dictLength = len;
return Z_OK;
}
/* ========================================================================= */
int ZEXPORT deflateResetKeep (strm)
z_streamp strm;
{
deflate_state *s;
if (deflateStateCheck(strm)) {
return Z_STREAM_ERROR;
}
strm->total_in = strm->total_out = 0;
strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
strm->data_type = Z_UNKNOWN;
s = (deflate_state *)strm->state;
s->pending = 0;
s->pending_out = s->pending_buf;
if (s->wrap < 0) {
s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
}
s->status =
#ifdef GZIP
s->wrap == 2 ? GZIP_STATE :
#endif
s->wrap ? INIT_STATE : BUSY_STATE;
strm->adler =
#ifdef GZIP
s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
#endif
adler32(0L, Z_NULL, 0);
s->last_flush = Z_NO_FLUSH;
_tr_init(s);
return Z_OK;
}
/* ========================================================================= */
int ZEXPORT deflateReset (strm)
z_streamp strm;
{
int ret;
ret = deflateResetKeep(strm);
if (ret == Z_OK)
lm_init(strm->state);
return ret;
}
/* ========================================================================= */
int ZEXPORT deflateSetHeader (strm, head)
z_streamp strm;
gz_headerp head;
{
if (deflateStateCheck(strm) || strm->state->wrap != 2)
return Z_STREAM_ERROR;
strm->state->gzhead = head;
return Z_OK;
}
/* ========================================================================= */
int ZEXPORT deflatePending (strm, pending, bits)
unsigned *pending;
int *bits;
z_streamp strm;
{
if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
if (pending != Z_NULL)
*pending = strm->state->pending;
if (bits != Z_NULL)
*bits = strm->state->bi_valid;
return Z_OK;
}
/* ========================================================================= */
int ZEXPORT deflatePrime (strm, bits, value)
z_streamp strm;
int bits;
int value;
{
deflate_state *s;
int put;
if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
s = strm->state;
if (s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3))
return Z_BUF_ERROR;
do {
put = Buf_size - s->bi_valid;
if (put > bits)
put = bits;
s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
s->bi_valid += put;
_tr_flush_bits(s);
value >>= put;
bits -= put;
} while (bits);
return Z_OK;
}
/* ========================================================================= */
int ZEXPORT deflateParams(strm, level, strategy)
z_streamp strm;
int level;
int strategy;
{
deflate_state *s;
compress_func func;
if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
s = strm->state;
#ifdef FASTEST
if (level != 0) level = 1;
#else
if (level == Z_DEFAULT_COMPRESSION) level = 6;
#endif
if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
return Z_STREAM_ERROR;
}
func = configuration_table[s->level].func;
if ((strategy != s->strategy || func != configuration_table[level].func) &&
s->high_water) {
/* Flush the last buffer: */
int err = deflate(strm, Z_BLOCK);
if (err == Z_STREAM_ERROR)
return err;
if (strm->avail_out == 0)
return Z_BUF_ERROR;
}
if (s->level != level) {
if (s->level == 0 && s->matches != 0) {
if (s->matches == 1)
slide_hash(s);
else
CLEAR_HASH(s);
s->matches = 0;
}
s->level = level;
s->max_lazy_match = configuration_table[level].max_lazy;
s->good_match = configuration_table[level].good_length;
s->nice_match = configuration_table[level].nice_length;
s->max_chain_length = configuration_table[level].max_chain;
}
s->strategy = strategy;
return Z_OK;
}
/* ========================================================================= */
int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
z_streamp strm;
int good_length;
int max_lazy;
int nice_length;
int max_chain;
{
deflate_state *s;
if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
s = strm->state;
s->good_match = (uInt)good_length;
s->max_lazy_match = (uInt)max_lazy;
s->nice_match = nice_length;
s->max_chain_length = (uInt)max_chain;
return Z_OK;
}
/* =========================================================================
* For the default windowBits of 15 and memLevel of 8, this function returns
* a close to exact, as well as small, upper bound on the compressed size.
* They are coded as constants here for a reason--if the #define's are
* changed, then this function needs to be changed as well. The return
* value for 15 and 8 only works for those exact settings.
*
* For any setting other than those defaults for windowBits and memLevel,
* the value returned is a conservative worst case for the maximum expansion
* resulting from using fixed blocks instead of stored blocks, which deflate
* can emit on compressed data for some combinations of the parameters.
*
* This function could be more sophisticated to provide closer upper bounds for
* every combination of windowBits and memLevel. But even the conservative
* upper bound of about 14% expansion does not seem onerous for output buffer
* allocation.
*/
uLong ZEXPORT deflateBound(strm, sourceLen)
z_streamp strm;
uLong sourceLen;
{
deflate_state *s;
uLong complen, wraplen;
/* conservative upper bound for compressed data */
complen = sourceLen +
((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
/* if can't get parameters, return conservative bound plus zlib wrapper */
if (deflateStateCheck(strm))
return complen + 6;
/* compute wrapper length */
s = strm->state;
switch (s->wrap) {
case 0: /* raw deflate */
wraplen = 0;
break;
case 1: /* zlib wrapper */
wraplen = 6 + (s->strstart ? 4 : 0);
break;
#ifdef GZIP
case 2: /* gzip wrapper */
wraplen = 18;
if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
Bytef *str;
if (s->gzhead->extra != Z_NULL)
wraplen += 2 + s->gzhead->extra_len;
str = s->gzhead->name;
if (str != Z_NULL)
do {
wraplen++;
} while (*str++);
str = s->gzhead->comment;
if (str != Z_NULL)
do {
wraplen++;
} while (*str++);
if (s->gzhead->hcrc)
wraplen += 2;
}
break;
#endif
default: /* for compiler happiness */
wraplen = 6;
}
/* if not default parameters, return conservative bound */
if (s->w_bits != 15 || s->hash_bits != 8 + 7)
return complen + wraplen;
/* default settings: return tight bound for that case */
return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
(sourceLen >> 25) + 13 - 6 + wraplen;
}
/* =========================================================================
* 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.
*/
local void putShortMSB (s, b)
deflate_state *s;
uInt b;
{
put_byte(s, (Byte)(b >> 8));
put_byte(s, (Byte)(b & 0xff));
}
/* =========================================================================
* Flush as much pending output as possible. All deflate() output, except for
* some deflate_stored() 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 deflate_read_buf()).
*/
local void flush_pending(strm)
z_streamp strm;
{
unsigned len;
deflate_state *s = strm->state;
_tr_flush_bits(s);
len = s->pending;
if (len > strm->avail_out) len = strm->avail_out;
if (len == 0) return;
zmemcpy(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;
}
}
/* ===========================================================================
* Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1].
*/
#define HCRC_UPDATE(beg) \
do { \
if (s->gzhead->hcrc && s->pending > (beg)) \
strm->adler = crc32(strm->adler, s->pending_buf + (beg), \
s->pending - (beg)); \
} while (0)
/* ========================================================================= */
int ZEXPORT deflate (strm, flush)
z_streamp strm;
int flush;
{
int old_flush; /* value of flush param for previous deflate call */
deflate_state *s;
if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) {
return Z_STREAM_ERROR;
}
s = strm->state;
if (strm->next_out == Z_NULL ||
(strm->avail_in != 0 && strm->next_in == Z_NULL) ||
(s->status == FINISH_STATE && flush != Z_FINISH)) {
ERR_RETURN(strm, Z_STREAM_ERROR);
}
if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
old_flush = s->last_flush;
s->last_flush = flush;
/* 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_BUF_ERROR.
*/
} else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
flush != Z_FINISH) {
ERR_RETURN(strm, Z_BUF_ERROR);
}
/* User must not provide more input after the first FINISH: */
if (s->status == FINISH_STATE && strm->avail_in != 0) {
ERR_RETURN(strm, Z_BUF_ERROR);
}
/* Write the header */
if (s->status == INIT_STATE) {
/* zlib header */
uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
uInt level_flags;
if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
level_flags = 0;
else if (s->level < 6)
level_flags = 1;
else if (s->level == 6)
level_flags = 2;
else
level_flags = 3;
header |= (level_flags << 6);
if (s->strstart != 0) header |= PRESET_DICT;
header += 31 - (header % 31);
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 = adler32(0L, Z_NULL, 0);
s->status = BUSY_STATE;
/* Compression must start with an empty pending buffer */
flush_pending(strm);
if (s->pending != 0) {
s->last_flush = -1;
return Z_OK;
}
}
#ifdef GZIP
if (s->status == GZIP_STATE) {
/* gzip header */
crc_reset(s);
put_byte(s, 31);
put_byte(s, 139);
put_byte(s, 8);
if (s->gzhead == Z_NULL) {
put_byte(s, 0);
put_byte(s, 0);
put_byte(s, 0);
put_byte(s, 0);
put_byte(s, 0);
put_byte(s, s->level == 9 ? 2 :
(s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
4 : 0));
put_byte(s, OS_CODE);
s->status = BUSY_STATE;
/* Compression must start with an empty pending buffer */
flush_pending(strm);
if (s->pending != 0) {
s->last_flush = -1;
return Z_OK;
}
}
else {
put_byte(s, (s->gzhead->text ? 1 : 0) +
(s->gzhead->hcrc ? 2 : 0) +
(s->gzhead->extra == Z_NULL ? 0 : 4) +
(s->gzhead->name == Z_NULL ? 0 : 8) +
(s->gzhead->comment == Z_NULL ? 0 : 16)
);
put_byte(s, (Byte)(s->gzhead->time & 0xff));
put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
put_byte(s, s->level == 9 ? 2 :
(s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
4 : 0));
put_byte(s, s->gzhead->os & 0xff);
if (s->gzhead->extra != Z_NULL) {
put_byte(s, s->gzhead->extra_len & 0xff);
put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
}
if (s->gzhead->hcrc)
strm->adler = crc32(strm->adler, s->pending_buf,
s->pending);
s->gzindex = 0;
s->status = EXTRA_STATE;
}
}
if (s->status == EXTRA_STATE) {
if (s->gzhead->extra != Z_NULL) {
ulg beg = s->pending; /* start of bytes to update crc */
uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex;
while (s->pending + left > s->pending_buf_size) {
uInt copy = s->pending_buf_size - s->pending;
zmemcpy(s->pending_buf + s->pending,
s->gzhead->extra + s->gzindex, copy);
s->pending = s->pending_buf_size;
HCRC_UPDATE(beg);
s->gzindex += copy;
flush_pending(strm);
if (s->pending != 0) {
s->last_flush = -1;
return Z_OK;
}
beg = 0;
left -= copy;
}
zmemcpy(s->pending_buf + s->pending,
s->gzhead->extra + s->gzindex, left);
s->pending += left;
HCRC_UPDATE(beg);
s->gzindex = 0;
}
s->status = NAME_STATE;
}
if (s->status == NAME_STATE) {
if (s->gzhead->name != Z_NULL) {
ulg beg = s->pending; /* start of bytes to update crc */
int val;
do {
if (s->pending == s->pending_buf_size) {
HCRC_UPDATE(beg);
flush_pending(strm);
if (s->pending != 0) {
s->last_flush = -1;
return Z_OK;
}
beg = 0;
}
val = s->gzhead->name[s->gzindex++];
put_byte(s, val);
} while (val != 0);
HCRC_UPDATE(beg);
s->gzindex = 0;
}
s->status = COMMENT_STATE;
}
if (s->status == COMMENT_STATE) {
if (s->gzhead->comment != Z_NULL) {
ulg beg = s->pending; /* start of bytes to update crc */
int val;
do {
if (s->pending == s->pending_buf_size) {
HCRC_UPDATE(beg);
flush_pending(strm);
if (s->pending != 0) {
s->last_flush = -1;
return Z_OK;
}
beg = 0;
}
val = s->gzhead->comment[s->gzindex++];
put_byte(s, val);
} while (val != 0);
HCRC_UPDATE(beg);
}
s->status = HCRC_STATE;
}
if (s->status == HCRC_STATE) {
if (s->gzhead->hcrc) {
if (s->pending + 2 > s->pending_buf_size) {
flush_pending(strm);
if (s->pending != 0) {
s->last_flush = -1;
return Z_OK;
}
}
put_byte(s, (Byte)(strm->adler & 0xff));
put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
strm->adler = crc32(0L, Z_NULL, 0);
}
s->status = BUSY_STATE;
/* Compression must start with an empty pending buffer */
flush_pending(strm);
if (s->pending != 0) {
s->last_flush = -1;
return Z_OK;
}
}
#endif
/* 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 = s->level == 0 ? deflate_stored(s, flush) :
s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
s->strategy == Z_RLE ? deflate_rle(s, flush) :
(*(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) {
_tr_align(s);
} else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
_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 */
if (s->lookahead == 0) {
s->strstart = 0;
s->block_start = 0L;
s->insert = 0;
}
}
}
flush_pending(strm);
if (strm->avail_out == 0) {
s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
return Z_OK;
}
}
}
if (flush != Z_FINISH) return Z_OK;
if (s->wrap <= 0) return Z_STREAM_END;
/* Write the trailer */
#ifdef GZIP
if (s->wrap == 2) {
crc_finalize(s);
put_byte(s, (Byte)(strm->adler & 0xff));
put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
put_byte(s, (Byte)(strm->total_in & 0xff));
put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
}
else
#endif
{
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.
*/
if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
return s->pending != 0 ? Z_OK : Z_STREAM_END;
}
/* ========================================================================= */
int ZEXPORT deflateEnd (strm)
z_streamp strm;
{
int status;
if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
status = strm->state->status;
/* Deallocate in reverse order of allocations: */
TRY_FREE(strm, strm->state->pending_buf);
TRY_FREE(strm, strm->state->head);
TRY_FREE(strm, strm->state->prev);
TRY_FREE(strm, strm->state->window);
ZFREE(strm, strm->state);
strm->state = Z_NULL;
return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
}
/* =========================================================================
* Copy the source state to the destination state.
* To simplify the source, this is not supported for 16-bit MSDOS (which
* doesn't have enough memory anyway to duplicate compression states).
*/
int ZEXPORT deflateCopy (dest, source)
z_streamp dest;
z_streamp source;
{
#ifdef MAXSEG_64K
return Z_STREAM_ERROR;
#else
deflate_state *ds;
deflate_state *ss;
if (deflateStateCheck(source) || dest == Z_NULL) {
return Z_STREAM_ERROR;
}
ss = source->state;
zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
if (ds == Z_NULL) return Z_MEM_ERROR;
dest->state = (struct internal_state FAR *) ds;
zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
ds->strm = dest;
ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4);
if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
ds->pending_buf == Z_NULL) {
deflateEnd (dest);
return Z_MEM_ERROR;
}
/* following zmemcpy do not work for 16-bit MSDOS */
zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
ds->sym_buf = ds->pending_buf + ds->lit_bufsize;
ds->l_desc.dyn_tree = ds->dyn_ltree;
ds->d_desc.dyn_tree = ds->dyn_dtree;
ds->bl_desc.dyn_tree = ds->bl_tree;
return Z_OK;
#endif /* MAXSEG_64K */
}
/* ===========================================================================
* 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()).
*/
ZLIB_INTERNAL unsigned deflate_read_buf(strm, buf, size)
z_streamp strm;
Bytef *buf;
unsigned size;
{
unsigned len = strm->avail_in;
if (len > size) len = size;
if (len == 0) return 0;
strm->avail_in -= len;
#ifdef GZIP
if (strm->state->wrap == 2)
copy_with_crc(strm, buf, len);
else
#endif
{
zmemcpy(buf, strm->next_in, len);
if (strm->state->wrap == 1)
strm->adler = adler32(strm->adler, buf, len);
}
strm->next_in += len;
strm->total_in += len;
return len;
}
/* ===========================================================================
* Initialize the "longest match" routines for a new zlib stream
*/
local void lm_init (s)
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->insert = 0;
s->match_length = s->prev_length = MIN_MATCH-1;
s->match_available = 0;
s->ins_h = 0;
#ifndef FASTEST
#ifdef ASMV
match_init(); /* initialize the asm code */
#endif
#endif
}
#ifndef FASTEST
/* ===========================================================================
* 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.
*/
#ifndef ASMV
/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
* match.S. The code will be functionally equivalent.
*/
local uInt longest_match(s, cur_match)
deflate_state *s;
IPos cur_match; /* current match */
{
unsigned chain_length = s->max_chain_length;/* max hash chain length */
register Bytef *scan = s->window + s->strstart; /* current string */
register Bytef *match; /* matched string */
register int len; /* length of current match */
int best_len = (int)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.
*/
Posf *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 Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
register ush scan_start = *(ushf*)scan;
register ush scan_end = *(ushf*)(scan+best_len-1);
#else
register Bytef *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 = (int)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. Note that the checks below
* for insufficient lookahead only occur occasionally for performance
* reasons. Therefore uninitialized memory will be accessed, and
* conditional jumps will be made that depend on those values.
* However the length of the match is limited to the lookahead, so
* the output of deflate is not affected by the uninitialized values.
*/
#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 (*(ushf*)(match+best_len-1) != scan_end ||
*(ushf*)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 (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
*(ushf*)(scan+=2) == *(ushf*)(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 = *(ushf*)(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 (uInt)best_len;
return s->lookahead;
}
#endif /* ASMV */
#else /* FASTEST */
/* ---------------------------------------------------------------------------
* Optimized version for FASTEST 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 (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
}
#endif /* FASTEST */
#ifdef ZLIB_DEBUG
#define EQUAL 0
/* result of memcmp for equal strings */
/* ===========================================================================
* Check that the match at match_start is indeed a match.
*/
local void check_match(s, start, match, length)
deflate_state *s;
IPos start, match;
int length;
{
/* check that the match is indeed a match */
if (zmemcmp(s->window + match,
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++]);
} while (--length != 0);
z_error("invalid match");
}
if (z_verbose > 1) {
fprintf(stderr,"\\[%d,%d]", start-match, length);
do { putc(s->window[start++], stderr); } while (--length != 0);
}
}
#else
# define check_match(s, start, match, length)
#endif /* ZLIB_DEBUG */
/* ===========================================================================
* Fill the window when the lookahead becomes insufficient.
* Updates strstart and lookahead.
*
* IN assertion: lookahead < MIN_LOOKAHEAD
* OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
* At least one byte has been read, or avail_in == 0; reads are
* performed for at least two bytes (required for the zip translate_eol
* option -- not supported here).
*/
local void fill_window_c(deflate_state *s);
local void fill_window(deflate_state *s)
{
if (x86_cpu_enable_simd) {
fill_window_sse(s);
return;
}
fill_window_c(s);
}
local void fill_window_c(s)
deflate_state *s;
{
unsigned n;
unsigned more; /* Amount of free space at the end of the window. */
uInt wsize = s->w_size;
Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
do {
more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
/* Deal with !@#$% 64K limit: */
if (sizeof(int) <= 2) {
if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
more = wsize;
} else if (more == (unsigned)(-1)) {
/* Very unlikely, but possible on 16 bit machine if
* strstart == 0 && lookahead == 1 (input done a byte at time)
*/
more--;
}
}
/* If the window is almost full and there is insufficient lookahead,
* move the upper half to the lower one to make room in the upper half.
*/
if (s->strstart >= wsize+MAX_DIST(s)) {
zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more);
s->match_start -= wsize;
s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
s->block_start -= (long) wsize;
slide_hash(s);
more += wsize;
}
if (s->strm->avail_in == 0) break;
/* If there was no sliding:
* strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
* more == window_size - lookahead - strstart
* => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
* => more >= window_size - 2*WSIZE + 2
* In the BIG_MEM or MMAP case (not yet supported),
* window_size == input_size + MIN_LOOKAHEAD &&
* strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
* Otherwise, window_size == 2*WSIZE so more >= 2.
* If there was sliding, more >= WSIZE. So in all cases, more >= 2.
*/
Assert(more >= 2, "more < 2");
n = deflate_read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
s->lookahead += n;
/* Initialize the hash value now that we have some input: */
if (s->lookahead + s->insert >= MIN_MATCH) {
uInt str = s->strstart - s->insert;
s->ins_h = s->window[str];
UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
#if MIN_MATCH != 3
Call UPDATE_HASH() MIN_MATCH-3 more times
#endif
while (s->insert) {
UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
#ifndef FASTEST
s->prev[str & s->w_mask] = s->head[s->ins_h];
#endif
s->head[s->ins_h] = (Pos)str;
str++;
s->insert--;
if (s->lookahead + s->insert < MIN_MATCH)
break;
}
}
/* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
* but this is not important since only literal bytes will be emitted.
*/
} while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
/* If the WIN_INIT bytes after the end of the current data have never been
* written, then zero those bytes in order to avoid memory check reports of
* the use of uninitialized (or uninitialised as Julian writes) bytes by
* the longest match routines. Update the high water mark for the next
* time through here. WIN_INIT is set to MAX_MATCH since the longest match
* routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
*/
if (s->high_water < s->window_size) {
ulg curr = s->strstart + (ulg)(s->lookahead);
ulg init;
if (s->high_water < curr) {
/* Previous high water mark below current data -- zero WIN_INIT
* bytes or up to end of window, whichever is less.
*/
init = s->window_size - curr;
if (init > WIN_INIT)
init = WIN_INIT;
zmemzero(s->window + curr, (unsigned)init);
s->high_water = curr + init;
}
else if (s->high_water < (ulg)curr + WIN_INIT) {
/* High water mark at or above current data, but below current data
* plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
* to end of window, whichever is less.
*/
init = (ulg)curr + WIN_INIT - s->high_water;
if (init > s->window_size - s->high_water)
init = s->window_size - s->high_water;
zmemzero(s->window + s->high_water, (unsigned)init);
s->high_water += init;
}
}
Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
"not enough room for search");
}
/* ===========================================================================
* Flush the current block, with given end-of-file flag.
* IN assertion: strstart is set to the end of the current match.
*/
#define FLUSH_BLOCK_ONLY(s, last) { \
_tr_flush_block(s, (s->block_start >= 0L ? \
(charf *)&s->window[(unsigned)s->block_start] : \
(charf *)Z_NULL), \
(ulg)((long)s->strstart - s->block_start), \
(last)); \
s->block_start = s->strstart; \
flush_pending(s->strm); \
Tracev((stderr,"[FLUSH]")); \
}
/* Same but force premature exit if necessary. */
#define FLUSH_BLOCK(s, last) { \
FLUSH_BLOCK_ONLY(s, last); \
if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
}
/* Maximum stored block length in deflate format (not including header). */
#define MAX_STORED 65535
/* Minimum of a and b. */
#define MIN(a, b) ((a) > (b) ? (b) : (a))
/* ===========================================================================
* Copy without compression as much as possible from the input stream, return
* the current block state.
*
* In case deflateParams() is used to later switch to a non-zero compression
* level, s->matches (otherwise unused when storing) keeps track of the number
* of hash table slides to perform. If s->matches is 1, then one hash table
* slide will be done when switching. If s->matches is 2, the maximum value
* allowed here, then the hash table will be cleared, since two or more slides
* is the same as a clear.
*
* deflate_stored() is written to minimize the number of times an input byte is
* copied. It is most efficient with large input and output buffers, which
* maximizes the opportunites to have a single copy from next_in to next_out.
*/
local block_state deflate_stored(s, flush)
deflate_state *s;
int flush;
{
/* Smallest worthy block size when not flushing or finishing. By default
* this is 32K. This can be as small as 507 bytes for memLevel == 1. For
* large input and output buffers, the stored block size will be larger.
*/
unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size);
/* Copy as many min_block or larger stored blocks directly to next_out as
* possible. If flushing, copy the remaining available input to next_out as
* stored blocks, if there is enough space.
*/
unsigned len, left, have, last = 0;
unsigned used = s->strm->avail_in;
do {
/* Set len to the maximum size block that we can copy directly with the
* available input data and output space. Set left to how much of that
* would be copied from what's left in the window.
*/
len = MAX_STORED; /* maximum deflate stored block length */
have = (s->bi_valid + 42) >> 3; /* number of header bytes */
if (s->strm->avail_out < have) /* need room for header */
break;
/* maximum stored block length that will fit in avail_out: */
have = s->strm->avail_out - have;
left = s->strstart - s->block_start; /* bytes left in window */
if (len > (ulg)left + s->strm->avail_in)
len = left + s->strm->avail_in; /* limit len to the input */
if (len > have)
len = have; /* limit len to the output */
/* If the stored block would be less than min_block in length, or if
* unable to copy all of the available input when flushing, then try
* copying to the window and the pending buffer instead. Also don't
* write an empty block when flushing -- deflate() does that.
*/
if (len < min_block && ((len == 0 && flush != Z_FINISH) ||
flush == Z_NO_FLUSH ||
len != left + s->strm->avail_in))
break;
/* Make a dummy stored block in pending to get the header bytes,
* including any pending bits. This also updates the debugging counts.
*/
last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0;
_tr_stored_block(s, (char *)0, 0L, last);
/* Replace the lengths in the dummy stored block with len. */
s->pending_buf[s->pending - 4] = len;
s->pending_buf[s->pending - 3] = len >> 8;
s->pending_buf[s->pending - 2] = ~len;
s->pending_buf[s->pending - 1] = ~len >> 8;
/* Write the stored block header bytes. */
flush_pending(s->strm);
#ifdef ZLIB_DEBUG
/* Update debugging counts for the data about to be copied. */
s->compressed_len += len << 3;
s->bits_sent += len << 3;
#endif
/* Copy uncompressed bytes from the window to next_out. */
if (left) {
if (left > len)
left = len;
zmemcpy(s->strm->next_out, s->window + s->block_start, left);
s->strm->next_out += left;
s->strm->avail_out -= left;
s->strm->total_out += left;
s->block_start += left;
len -= left;
}
/* Copy uncompressed bytes directly from next_in to next_out, updating
* the check value.
*/
if (len) {
deflate_read_buf(s->strm, s->strm->next_out, len);
s->strm->next_out += len;
s->strm->avail_out -= len;
s->strm->total_out += len;
}
} while (last == 0);
/* Update the sliding window with the last s->w_size bytes of the copied
* data, or append all of the copied data to the existing window if less
* than s->w_size bytes were copied. Also update the number of bytes to
* insert in the hash tables, in the event that deflateParams() switches to
* a non-zero compression level.
*/
used -= s->strm->avail_in; /* number of input bytes directly copied */
if (used) {
/* If any input was used, then no unused input remains in the window,
* therefore s->block_start == s->strstart.
*/
if (used >= s->w_size) { /* supplant the previous history */
s->matches = 2; /* clear hash */
zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);
s->strstart = s->w_size;
}
else {
if (s->window_size - s->strstart <= used) {
/* Slide the window down. */
s->strstart -= s->w_size;
zmemcpy(s->window, s->window + s->w_size, s->strstart);
if (s->matches < 2)
s->matches++; /* add a pending slide_hash() */
}
zmemcpy(s->window + s->strstart, s->strm->next_in - used, used);
s->strstart += used;
}
s->block_start = s->strstart;
s->insert += MIN(used, s->w_size - s->insert);
}
if (s->high_water < s->strstart)
s->high_water = s->strstart;
/* If the last block was written to next_out, then done. */
if (last)
return finish_done;
/* If flushing and all input has been consumed, then done. */
if (flush != Z_NO_FLUSH && flush != Z_FINISH &&
s->strm->avail_in == 0 && (long)s->strstart == s->block_start)
return block_done;
/* Fill the window with any remaining input. */
have = s->window_size - s->strstart - 1;
if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) {
/* Slide the window down. */
s->block_start -= s->w_size;
s->strstart -= s->w_size;
zmemcpy(s->window, s->window + s->w_size, s->strstart);
if (s->matches < 2)
s->matches++; /* add a pending slide_hash() */
have += s->w_size; /* more space now */
}
if (have > s->strm->avail_in)
have = s->strm->avail_in;
if (have) {
deflate_read_buf(s->strm, s->window + s->strstart, have);
s->strstart += have;
}
if (s->high_water < s->strstart)
s->high_water = s->strstart;
/* There was not enough avail_out to write a complete worthy or flushed
* stored block to next_out. Write a stored block to pending instead, if we
* have enough input for a worthy block, or if flushing and there is enough
* room for the remaining input as a stored block in the pending buffer.
*/
have = (s->bi_valid + 42) >> 3; /* number of header bytes */
/* maximum stored block length that will fit in pending: */
have = MIN(s->pending_buf_size - have, MAX_STORED);
min_block = MIN(have, s->w_size);
left = s->strstart - s->block_start;
if (left >= min_block ||
((left || flush == Z_FINISH) && flush != Z_NO_FLUSH &&
s->strm->avail_in == 0 && left <= have)) {
len = MIN(left, have);
last = flush == Z_FINISH && s->strm->avail_in == 0 &&
len == left ? 1 : 0;
_tr_stored_block(s, (charf *)s->window + s->block_start, len, last);
s->block_start += len;
flush_pending(s->strm);
}
/* We've done all we can with the available input and output. */
return last ? finish_started : need_more;
}
/* ===========================================================================
* Compress as much as possible from the input stream, return the current
* block state.
* This function does not perform lazy evaluation of matches and inserts
* new strings in the dictionary only for unmatched strings or for short
* matches. It is used only for the fast compression options.
*/
local block_state deflate_fast(s, flush)
deflate_state *s;
int flush;
{
IPos hash_head; /* head of the hash chain */
int bflush; /* set if current block must be flushed */
for (;;) {
/* Make sure that we always have enough lookahead, except
* at the end of the input file. We need MAX_MATCH bytes
* for the next match, plus MIN_MATCH bytes to insert the
* string following the next match.
*/
if (s->lookahead < MIN_LOOKAHEAD) {
fill_window(s);
if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
return need_more;
}
if (s->lookahead == 0) break; /* flush the current block */
}
/* Insert the string window[strstart .. strstart+2] in the
* dictionary, and set hash_head to the head of the hash chain:
*/
hash_head = NIL;
if (s->lookahead >= MIN_MATCH) {
hash_head = insert_string(s, s->strstart);
}
/* Find the longest match, discarding those <= prev_length.
* At this point we have always match_length < MIN_MATCH
*/
if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
/* To simplify the code, we prevent matches with the string
* of window index 0 (in particular we have to avoid a match
* of the string with itself at the start of the input file).
*/
s->match_length = longest_match (s, hash_head);
/* longest_match() sets match_start */
}
if (s->match_length >= MIN_MATCH) {
check_match(s, s->strstart, s->match_start, s->match_length);
_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 table */
do {
s->strstart++;
hash_head = insert_string(s, s->strstart);
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
* always MIN_MATCH bytes ahead.
*/
} while (--s->match_length != 0);
s->strstart++;
} else
#endif
{
s->strstart += s->match_length;
s->match_length = 0;
s->ins_h = s->window[s->strstart];
UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
#if MIN_MATCH != 3
Call UPDATE_HASH() MIN_MATCH-3 more times
#endif
/* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
* matter since it will be recomputed at next deflate call.
*/
}
} else {
/* No match, output a literal byte */
Tracevv((stderr,"%c", s->window[s->strstart]));
_tr_tally_lit (s, s->window[s->strstart], bflush);
s->lookahead--;
s->strstart++;
}
if (bflush) FLUSH_BLOCK(s, 0);
}
s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
if (flush == Z_FINISH) {
FLUSH_BLOCK(s, 1);
return finish_done;
}
if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
#ifndef FASTEST
/* ===========================================================================
* Same as above, but achieves better compression. We use a lazy
* evaluation for matches: a match is finally adopted only if there is
* no better match at the next window position.
*/
local block_state deflate_slow(s, flush)
deflate_state *s;
int flush;
{
IPos hash_head; /* head of hash chain */
int bflush; /* set if current block must be flushed */
/* Process the input block. */
for (;;) {
/* Make sure that we always have enough lookahead, except
* at the end of the input file. We need MAX_MATCH bytes
* for the next match, plus MIN_MATCH bytes to insert the
* string following the next match.
*/
if (s->lookahead < MIN_LOOKAHEAD) {
fill_window(s);
if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
return need_more;
}
if (s->lookahead == 0) break; /* flush the current block */
}
/* Insert the string window[strstart .. strstart+2] in the
* dictionary, and set hash_head to the head of the hash chain:
*/
hash_head = NIL;
if (s->lookahead >= MIN_MATCH) {
hash_head = insert_string(s, s->strstart);
}
/* Find the longest match, discarding those <= prev_length.
*/
s->prev_length = s->match_length, s->prev_match = s->match_start;
s->match_length = MIN_MATCH-1;
if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
s->strstart - hash_head <= MAX_DIST(s)) {
/* To simplify the code, we prevent matches with the string
* of window index 0 (in particular we have to avoid a match
* of the string with itself at the start of the input file).
*/
s->match_length = longest_match (s, hash_head);
/* longest_match() sets match_start */
if (s->match_length <= 5 && (s->strategy == Z_FILTERED
#if TOO_FAR <= 32767
|| (s->match_length == MIN_MATCH &&
s->strstart - s->match_start > TOO_FAR)
#endif
)) {
/* If prev_match is also MIN_MATCH, match_start is garbage
* but we will ignore the current match anyway.
*/
s->match_length = MIN_MATCH-1;
}
}
/* If there was a match at the previous step and the current
* match is not better, output the previous match:
*/
if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
/* Do not insert strings in hash table beyond this. */
check_match(s, s->strstart-1, s->prev_match, s->prev_length);
_tr_tally_dist(s, s->strstart -1 - s->prev_match,
s->prev_length - MIN_MATCH, bflush);
/* Insert in hash table all strings up to the end of the match.
* strstart-1 and strstart are already inserted. If there is not
* enough lookahead, the last two strings are not inserted in
* the hash table.
*/
s->lookahead -= s->prev_length-1;
s->prev_length -= 2;
do {
if (++s->strstart <= max_insert) {
hash_head = insert_string(s, s->strstart);
}
} while (--s->prev_length != 0);
s->match_available = 0;
s->match_length = MIN_MATCH-1;
s->strstart++;
if (bflush) FLUSH_BLOCK(s, 0);
} else if (s->match_available) {
/* If there was no match at the previous position, output a
* single literal. If there was a match but the current match
* is longer, truncate the previous match to a single literal.
*/
Tracevv((stderr,"%c", s->window[s->strstart-1]));
_tr_tally_lit(s, s->window[s->strstart-1], bflush);
if (bflush) {
FLUSH_BLOCK_ONLY(s, 0);
}
s->strstart++;
s->lookahead--;
if (s->strm->avail_out == 0) return need_more;
} else {
/* There is no previous match to compare with, wait for
* the next step to decide.
*/
s->match_available = 1;
s->strstart++;
s->lookahead--;
}
}
Assert (flush != Z_NO_FLUSH, "no flush?");
if (s->match_available) {
Tracevv((stderr,"%c", s->window[s->strstart-1]));
_tr_tally_lit(s, s->window[s->strstart-1], bflush);
s->match_available = 0;
}
s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
if (flush == Z_FINISH) {
FLUSH_BLOCK(s, 1);
return finish_done;
}
if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
#endif /* FASTEST */
/* ===========================================================================
* For Z_RLE, simply look for runs of bytes, generate matches only of distance
* one. Do not maintain a hash table. (It will be regenerated if this run of
* deflate switches away from Z_RLE.)
*/
local block_state deflate_rle(s, flush)
deflate_state *s;
int flush;
{
int bflush; /* set if current block must be flushed */
uInt prev; /* byte at distance one to match */
Bytef *scan, *strend; /* scan goes up to strend for length of run */
for (;;) {
/* Make sure that we always have enough lookahead, except
* at the end of the input file. We need MAX_MATCH bytes
* for the longest run, plus one for the unrolled loop.
*/
if (s->lookahead <= MAX_MATCH) {
fill_window(s);
if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
return need_more;
}
if (s->lookahead == 0) break; /* flush the current block */
}
/* See how many times the previous byte repeats */
s->match_length = 0;
if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
scan = s->window + s->strstart - 1;
prev = *scan;
if (prev == *++scan && prev == *++scan && prev == *++scan) {
strend = s->window + s->strstart + MAX_MATCH;
do {
} while (prev == *++scan && prev == *++scan &&
prev == *++scan && prev == *++scan &&
prev == *++scan && prev == *++scan &&
prev == *++scan && prev == *++scan &&
scan < strend);
s->match_length = MAX_MATCH - (uInt)(strend - scan);
if (s->match_length > s->lookahead)
s->match_length = s->lookahead;
}
Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
}
/* Emit match if have run of MIN_MATCH or longer, else emit literal */
if (s->match_length >= MIN_MATCH) {
check_match(s, s->strstart, s->strstart - 1, s->match_length);
_tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
s->lookahead -= s->match_length;
s->strstart += s->match_length;
s->match_length = 0;
} else {
/* No match, output a literal byte */
Tracevv((stderr,"%c", s->window[s->strstart]));
_tr_tally_lit (s, s->window[s->strstart], bflush);
s->lookahead--;
s->strstart++;
}
if (bflush) FLUSH_BLOCK(s, 0);
}
s->insert = 0;
if (flush == Z_FINISH) {
FLUSH_BLOCK(s, 1);
return finish_done;
}
if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}
/* ===========================================================================
* For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
* (It will be regenerated if this run of deflate switches away from Huffman.)
*/
local block_state deflate_huff(s, flush)
deflate_state *s;
int flush;
{
int bflush; /* set if current block must be flushed */
for (;;) {
/* Make sure that we have a literal to write. */
if (s->lookahead == 0) {
fill_window(s);
if (s->lookahead == 0) {
if (flush == Z_NO_FLUSH)
return need_more;
break; /* flush the current block */
}
}
/* Output a literal byte */
s->match_length = 0;
Tracevv((stderr,"%c", s->window[s->strstart]));
_tr_tally_lit (s, s->window[s->strstart], bflush);
s->lookahead--;
s->strstart++;
if (bflush) FLUSH_BLOCK(s, 0);
}
s->insert = 0;
if (flush == Z_FINISH) {
FLUSH_BLOCK(s, 1);
return finish_done;
}
if (s->sym_next)
FLUSH_BLOCK(s, 0);
return block_done;
}