1
/* deflate.c -- compress data using the deflation algorithm
2
* Copyright (C) 1995-2013 Jean-loup Gailly and Mark Adler
3
* For conditions of distribution and use, see copyright notice in zlib.h
9
* The "deflation" process depends on being able to identify portions
10
* of the input text which are identical to earlier input (within a
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* sliding window trailing behind the input currently being processed).
13
* The most straightforward technique turns out to be the fastest for
14
* most input files: try all possible matches and select the longest.
15
* The key feature of this algorithm is that insertions into the string
16
* dictionary are very simple and thus fast, and deletions are avoided
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* completely. Insertions are performed at each input character, whereas
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* string matches are performed only when the previous match ends. So it
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* is preferable to spend more time in matches to allow very fast string
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* insertions and avoid deletions. The matching algorithm for small
21
* strings is inspired from that of Rabin & Karp. A brute force approach
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* is used to find longer strings when a small match has been found.
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* A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
24
* (by Leonid Broukhis).
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* A previous version of this file used a more sophisticated algorithm
26
* (by Fiala and Greene) which is guaranteed to run in linear amortized
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* time, but has a larger average cost, uses more memory and is patented.
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* However the F&G algorithm may be faster for some highly redundant
29
* files if the parameter max_chain_length (described below) is too large.
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* The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
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* I found it in 'freeze' written by Leonid Broukhis.
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* Thanks to many people for bug reports and testing.
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* Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
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* Available in http://tools.ietf.org/html/rfc1951
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* A description of the Rabin and Karp algorithm is given in the book
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* "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
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* Fiala,E.R., and Greene,D.H.
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* Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
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const char deflate_copyright[] =
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" deflate 1.2.8 Copyright 1995-2013 Jean-loup Gailly and Mark Adler ";
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If you use the zlib library in a product, an acknowledgment is welcome
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in the documentation of your product. If for some reason you cannot
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include such an acknowledgment, I would appreciate that you keep this
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copyright string in the executable of your product.
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/* ===========================================================================
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* Function prototypes.
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need_more, /* block not completed, need more input or more output */
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block_done, /* block flush performed */
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finish_started, /* finish started, need only more output at next deflate */
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finish_done /* finish done, accept no more input or output */
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typedef block_state (*compress_func) OF((deflate_state *s, int flush));
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/* Compression function. Returns the block state after the call. */
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local void fill_window OF((deflate_state *s));
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local block_state deflate_stored OF((deflate_state *s, int flush));
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local block_state deflate_fast OF((deflate_state *s, int flush));
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local block_state deflate_slow OF((deflate_state *s, int flush));
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local block_state deflate_rle OF((deflate_state *s, int flush));
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local block_state deflate_huff OF((deflate_state *s, int flush));
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local void lm_init OF((deflate_state *s));
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local void putShortMSB OF((deflate_state *s, uInt b));
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local void flush_pending OF((z_streamp strm));
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local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
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void match_init OF((void)); /* asm code initialization */
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uInt longest_match OF((deflate_state *s, IPos cur_match));
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local uInt longest_match OF((deflate_state *s, IPos cur_match));
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local void check_match OF((deflate_state *s, IPos start, IPos match,
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/* ===========================================================================
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/* Tail of hash chains */
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# define TOO_FAR 4096
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/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
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/* Values for max_lazy_match, good_match and max_chain_length, depending on
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* the desired pack level (0..9). The values given below have been tuned to
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* exclude worst case performance for pathological files. Better values may be
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* found for specific files.
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typedef struct config_s {
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ush good_length; /* reduce lazy search above this match length */
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ush max_lazy; /* do not perform lazy search above this match length */
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ush nice_length; /* quit search above this match length */
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local const config configuration_table[2] = {
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/* good lazy nice chain */
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/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
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/* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
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local const config configuration_table[10] = {
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/* good lazy nice chain */
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/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
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/* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
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/* 2 */ {4, 5, 16, 8, deflate_fast},
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/* 3 */ {4, 6, 32, 32, deflate_fast},
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/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
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/* 5 */ {8, 16, 32, 32, deflate_slow},
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/* 6 */ {8, 16, 128, 128, deflate_slow},
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/* 7 */ {8, 32, 128, 256, deflate_slow},
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/* 8 */ {32, 128, 258, 1024, deflate_slow},
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/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
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/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
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* For deflate_fast() (levels <= 3) good is ignored and lazy has a different
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/* result of memcmp for equal strings */
154
#ifndef NO_DUMMY_DECL
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struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
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/* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
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#define RANK(f) (((f) << 1) - ((f) > 4 ? 9 : 0))
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/* ===========================================================================
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* Update a hash value with the given input byte
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* IN assertion: all calls to to UPDATE_HASH are made with consecutive
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* input characters, so that a running hash key can be computed from the
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* previous key instead of complete recalculation each time.
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#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
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/* ===========================================================================
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* Insert string str in the dictionary and set match_head to the previous head
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* of the hash chain (the most recent string with same hash key). Return
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* the previous length of the hash chain.
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* If this file is compiled with -DFASTEST, the compression level is forced
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* to 1, and no hash chains are maintained.
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* IN assertion: all calls to to INSERT_STRING are made with consecutive
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* input characters and the first MIN_MATCH bytes of str are valid
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* (except for the last MIN_MATCH-1 bytes of the input file).
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#define INSERT_STRING(s, str, match_head) \
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(UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
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match_head = s->head[s->ins_h], \
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s->head[s->ins_h] = (Pos)(str))
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#define INSERT_STRING(s, str, match_head) \
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(UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
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match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
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s->head[s->ins_h] = (Pos)(str))
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/* ===========================================================================
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* Initialize the hash table (avoiding 64K overflow for 16 bit systems).
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* prev[] will be initialized on the fly.
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#define CLEAR_HASH(s) \
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s->head[s->hash_size-1] = NIL; \
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zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
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/* ========================================================================= */
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int ZEXPORT deflateInit_(strm, level, version, stream_size)
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return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
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Z_DEFAULT_STRATEGY, version, stream_size);
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/* To do: ignore strm->next_in if we use it as window */
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/* ========================================================================= */
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int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
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version, stream_size)
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static const char my_version[] = ZLIB_VERSION;
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/* We overlay pending_buf and d_buf+l_buf. This works since the average
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* output size for (length,distance) codes is <= 24 bits.
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if (version == Z_NULL || version[0] != my_version[0] ||
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stream_size != sizeof(z_stream)) {
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return Z_VERSION_ERROR;
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if (strm == Z_NULL) return Z_STREAM_ERROR;
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if (strm->zalloc == (alloc_func)0) {
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return Z_STREAM_ERROR;
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strm->zalloc = zcalloc;
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strm->opaque = (voidpf)0;
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if (strm->zfree == (free_func)0)
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return Z_STREAM_ERROR;
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strm->zfree = zcfree;
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if (level != 0) level = 1;
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if (level == Z_DEFAULT_COMPRESSION) level = 6;
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if (windowBits < 0) { /* suppress zlib wrapper */
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windowBits = -windowBits;
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else if (windowBits > 15) {
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wrap = 2; /* write gzip wrapper instead */
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if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
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windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
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strategy < 0 || strategy > Z_FIXED) {
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return Z_STREAM_ERROR;
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if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
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s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
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if (s == Z_NULL) return Z_MEM_ERROR;
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strm->state = (struct internal_state FAR *)s;
284
s->w_bits = windowBits;
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s->w_size = 1 << s->w_bits;
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s->w_mask = s->w_size - 1;
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s->hash_bits = memLevel + 7;
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s->hash_size = 1 << s->hash_bits;
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s->hash_mask = s->hash_size - 1;
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s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
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s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
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s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
295
s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
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s->high_water = 0; /* nothing written to s->window yet */
299
s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
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overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
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s->pending_buf = (uchf *) overlay;
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s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
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if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
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s->pending_buf == Z_NULL) {
307
s->status = FINISH_STATE;
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strm->msg = ERR_MSG(Z_MEM_ERROR);
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s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
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s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
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s->strategy = strategy;
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s->method = (Byte)method;
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return deflateReset(strm);
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/* ========================================================================= */
323
int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
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const Bytef *dictionary;
332
z_const unsigned char *next;
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if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL)
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return Z_STREAM_ERROR;
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if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
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return Z_STREAM_ERROR;
341
/* when using zlib wrappers, compute Adler-32 for provided dictionary */
343
strm->adler = adler32(strm->adler, dictionary, dictLength);
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s->wrap = 0; /* avoid computing Adler-32 in read_buf */
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/* if dictionary would fill window, just replace the history */
347
if (dictLength >= s->w_size) {
348
if (wrap == 0) { /* already empty otherwise */
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dictionary += dictLength - s->w_size; /* use the tail */
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dictLength = s->w_size;
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/* insert dictionary into window and hash */
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avail = strm->avail_in;
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next = strm->next_in;
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strm->avail_in = dictLength;
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strm->next_in = (z_const Bytef *)dictionary;
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while (s->lookahead >= MIN_MATCH) {
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n = s->lookahead - (MIN_MATCH-1);
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UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
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s->prev[str & s->w_mask] = s->head[s->ins_h];
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s->head[s->ins_h] = (Pos)str;
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s->lookahead = MIN_MATCH-1;
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s->strstart += s->lookahead;
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s->block_start = (long)s->strstart;
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s->insert = s->lookahead;
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s->match_length = s->prev_length = MIN_MATCH-1;
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s->match_available = 0;
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strm->next_in = next;
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strm->avail_in = avail;
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/* ========================================================================= */
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int ZEXPORT deflateResetKeep (strm)
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if (strm == Z_NULL || strm->state == Z_NULL ||
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strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
399
return Z_STREAM_ERROR;
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strm->total_in = strm->total_out = 0;
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strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
404
strm->data_type = Z_UNKNOWN;
406
s = (deflate_state *)strm->state;
408
s->pending_out = s->pending_buf;
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s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
413
s->status = s->wrap ? INIT_STATE : BUSY_STATE;
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s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
418
adler32(0L, Z_NULL, 0);
419
s->last_flush = Z_NO_FLUSH;
426
/* ========================================================================= */
427
int ZEXPORT deflateReset (strm)
432
ret = deflateResetKeep(strm);
434
lm_init(strm->state);
438
/* ========================================================================= */
439
int ZEXPORT deflateSetHeader (strm, head)
443
if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
444
if (strm->state->wrap != 2) return Z_STREAM_ERROR;
445
strm->state->gzhead = head;
449
/* ========================================================================= */
450
int ZEXPORT deflatePending (strm, pending, bits)
455
if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
456
if (pending != Z_NULL)
457
*pending = strm->state->pending;
459
*bits = strm->state->bi_valid;
463
/* ========================================================================= */
464
int ZEXPORT deflatePrime (strm, bits, value)
472
if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
474
if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
477
put = Buf_size - s->bi_valid;
480
s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
489
/* ========================================================================= */
490
int ZEXPORT deflateParams(strm, level, strategy)
499
if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
503
if (level != 0) level = 1;
505
if (level == Z_DEFAULT_COMPRESSION) level = 6;
507
if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
508
return Z_STREAM_ERROR;
510
func = configuration_table[s->level].func;
512
if ((strategy != s->strategy || func != configuration_table[level].func) &&
513
strm->total_in != 0) {
514
/* Flush the last buffer: */
515
err = deflate(strm, Z_BLOCK);
516
if (err == Z_BUF_ERROR && s->pending == 0)
519
if (s->level != level) {
521
s->max_lazy_match = configuration_table[level].max_lazy;
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s->good_match = configuration_table[level].good_length;
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s->nice_match = configuration_table[level].nice_length;
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s->max_chain_length = configuration_table[level].max_chain;
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s->strategy = strategy;
530
/* ========================================================================= */
531
int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
540
if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
542
s->good_match = good_length;
543
s->max_lazy_match = max_lazy;
544
s->nice_match = nice_length;
545
s->max_chain_length = max_chain;
549
/* =========================================================================
550
* For the default windowBits of 15 and memLevel of 8, this function returns
551
* a close to exact, as well as small, upper bound on the compressed size.
552
* They are coded as constants here for a reason--if the #define's are
553
* changed, then this function needs to be changed as well. The return
554
* value for 15 and 8 only works for those exact settings.
556
* For any setting other than those defaults for windowBits and memLevel,
557
* the value returned is a conservative worst case for the maximum expansion
558
* resulting from using fixed blocks instead of stored blocks, which deflate
559
* can emit on compressed data for some combinations of the parameters.
561
* This function could be more sophisticated to provide closer upper bounds for
562
* every combination of windowBits and memLevel. But even the conservative
563
* upper bound of about 14% expansion does not seem onerous for output buffer
566
uLong ZEXPORT deflateBound(strm, sourceLen)
571
uLong complen, wraplen;
574
/* conservative upper bound for compressed data */
575
complen = sourceLen +
576
((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
578
/* if can't get parameters, return conservative bound plus zlib wrapper */
579
if (strm == Z_NULL || strm->state == Z_NULL)
582
/* compute wrapper length */
585
case 0: /* raw deflate */
588
case 1: /* zlib wrapper */
589
wraplen = 6 + (s->strstart ? 4 : 0);
591
case 2: /* gzip wrapper */
593
if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
594
if (s->gzhead->extra != Z_NULL)
595
wraplen += 2 + s->gzhead->extra_len;
596
str = s->gzhead->name;
601
str = s->gzhead->comment;
610
default: /* for compiler happiness */
614
/* if not default parameters, return conservative bound */
615
if (s->w_bits != 15 || s->hash_bits != 8 + 7)
616
return complen + wraplen;
618
/* default settings: return tight bound for that case */
619
return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
620
(sourceLen >> 25) + 13 - 6 + wraplen;
623
/* =========================================================================
624
* Put a short in the pending buffer. The 16-bit value is put in MSB order.
625
* IN assertion: the stream state is correct and there is enough room in
628
local void putShortMSB (s, b)
632
put_byte(s, (Byte)(b >> 8));
633
put_byte(s, (Byte)(b & 0xff));
636
/* =========================================================================
637
* Flush as much pending output as possible. All deflate() output goes
638
* through this function so some applications may wish to modify it
639
* to avoid allocating a large strm->next_out buffer and copying into it.
640
* (See also read_buf()).
642
local void flush_pending(strm)
646
deflate_state *s = strm->state;
650
if (len > strm->avail_out) len = strm->avail_out;
651
if (len == 0) return;
653
zmemcpy(strm->next_out, s->pending_out, len);
654
strm->next_out += len;
655
s->pending_out += len;
656
strm->total_out += len;
657
strm->avail_out -= len;
659
if (s->pending == 0) {
660
s->pending_out = s->pending_buf;
664
/* ========================================================================= */
665
int ZEXPORT deflate (strm, flush)
669
int old_flush; /* value of flush param for previous deflate call */
672
if (strm == Z_NULL || strm->state == Z_NULL ||
673
flush > Z_BLOCK || flush < 0) {
674
return Z_STREAM_ERROR;
678
if (strm->next_out == Z_NULL ||
679
(strm->next_in == Z_NULL && strm->avail_in != 0) ||
680
(s->status == FINISH_STATE && flush != Z_FINISH)) {
681
ERR_RETURN(strm, Z_STREAM_ERROR);
683
if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
685
s->strm = strm; /* just in case */
686
old_flush = s->last_flush;
687
s->last_flush = flush;
689
/* Write the header */
690
if (s->status == INIT_STATE) {
693
strm->adler = crc32(0L, Z_NULL, 0);
697
if (s->gzhead == Z_NULL) {
703
put_byte(s, s->level == 9 ? 2 :
704
(s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
706
put_byte(s, OS_CODE);
707
s->status = BUSY_STATE;
710
put_byte(s, (s->gzhead->text ? 1 : 0) +
711
(s->gzhead->hcrc ? 2 : 0) +
712
(s->gzhead->extra == Z_NULL ? 0 : 4) +
713
(s->gzhead->name == Z_NULL ? 0 : 8) +
714
(s->gzhead->comment == Z_NULL ? 0 : 16)
716
put_byte(s, (Byte)(s->gzhead->time & 0xff));
717
put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
718
put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
719
put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
720
put_byte(s, s->level == 9 ? 2 :
721
(s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
723
put_byte(s, s->gzhead->os & 0xff);
724
if (s->gzhead->extra != Z_NULL) {
725
put_byte(s, s->gzhead->extra_len & 0xff);
726
put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
729
strm->adler = crc32(strm->adler, s->pending_buf,
732
s->status = EXTRA_STATE;
738
uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
741
if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
743
else if (s->level < 6)
745
else if (s->level == 6)
749
header |= (level_flags << 6);
750
if (s->strstart != 0) header |= PRESET_DICT;
751
header += 31 - (header % 31);
753
s->status = BUSY_STATE;
754
putShortMSB(s, header);
756
/* Save the adler32 of the preset dictionary: */
757
if (s->strstart != 0) {
758
putShortMSB(s, (uInt)(strm->adler >> 16));
759
putShortMSB(s, (uInt)(strm->adler & 0xffff));
761
strm->adler = adler32(0L, Z_NULL, 0);
765
if (s->status == EXTRA_STATE) {
766
if (s->gzhead->extra != Z_NULL) {
767
uInt beg = s->pending; /* start of bytes to update crc */
769
while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
770
if (s->pending == s->pending_buf_size) {
771
if (s->gzhead->hcrc && s->pending > beg)
772
strm->adler = crc32(strm->adler, s->pending_buf + beg,
776
if (s->pending == s->pending_buf_size)
779
put_byte(s, s->gzhead->extra[s->gzindex]);
782
if (s->gzhead->hcrc && s->pending > beg)
783
strm->adler = crc32(strm->adler, s->pending_buf + beg,
785
if (s->gzindex == s->gzhead->extra_len) {
787
s->status = NAME_STATE;
791
s->status = NAME_STATE;
793
if (s->status == NAME_STATE) {
794
if (s->gzhead->name != Z_NULL) {
795
uInt beg = s->pending; /* start of bytes to update crc */
799
if (s->pending == s->pending_buf_size) {
800
if (s->gzhead->hcrc && s->pending > beg)
801
strm->adler = crc32(strm->adler, s->pending_buf + beg,
805
if (s->pending == s->pending_buf_size) {
810
val = s->gzhead->name[s->gzindex++];
813
if (s->gzhead->hcrc && s->pending > beg)
814
strm->adler = crc32(strm->adler, s->pending_buf + beg,
818
s->status = COMMENT_STATE;
822
s->status = COMMENT_STATE;
824
if (s->status == COMMENT_STATE) {
825
if (s->gzhead->comment != Z_NULL) {
826
uInt beg = s->pending; /* start of bytes to update crc */
830
if (s->pending == s->pending_buf_size) {
831
if (s->gzhead->hcrc && s->pending > beg)
832
strm->adler = crc32(strm->adler, s->pending_buf + beg,
836
if (s->pending == s->pending_buf_size) {
841
val = s->gzhead->comment[s->gzindex++];
844
if (s->gzhead->hcrc && s->pending > beg)
845
strm->adler = crc32(strm->adler, s->pending_buf + beg,
848
s->status = HCRC_STATE;
851
s->status = HCRC_STATE;
853
if (s->status == HCRC_STATE) {
854
if (s->gzhead->hcrc) {
855
if (s->pending + 2 > s->pending_buf_size)
857
if (s->pending + 2 <= s->pending_buf_size) {
858
put_byte(s, (Byte)(strm->adler & 0xff));
859
put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
860
strm->adler = crc32(0L, Z_NULL, 0);
861
s->status = BUSY_STATE;
865
s->status = BUSY_STATE;
869
/* Flush as much pending output as possible */
870
if (s->pending != 0) {
872
if (strm->avail_out == 0) {
873
/* Since avail_out is 0, deflate will be called again with
874
* more output space, but possibly with both pending and
875
* avail_in equal to zero. There won't be anything to do,
876
* but this is not an error situation so make sure we
877
* return OK instead of BUF_ERROR at next call of deflate:
883
/* Make sure there is something to do and avoid duplicate consecutive
884
* flushes. For repeated and useless calls with Z_FINISH, we keep
885
* returning Z_STREAM_END instead of Z_BUF_ERROR.
887
} else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
889
ERR_RETURN(strm, Z_BUF_ERROR);
892
/* User must not provide more input after the first FINISH: */
893
if (s->status == FINISH_STATE && strm->avail_in != 0) {
894
ERR_RETURN(strm, Z_BUF_ERROR);
897
/* Start a new block or continue the current one.
899
if (strm->avail_in != 0 || s->lookahead != 0 ||
900
(flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
903
bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
904
(s->strategy == Z_RLE ? deflate_rle(s, flush) :
905
(*(configuration_table[s->level].func))(s, flush));
907
if (bstate == finish_started || bstate == finish_done) {
908
s->status = FINISH_STATE;
910
if (bstate == need_more || bstate == finish_started) {
911
if (strm->avail_out == 0) {
912
s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
915
/* If flush != Z_NO_FLUSH && avail_out == 0, the next call
916
* of deflate should use the same flush parameter to make sure
917
* that the flush is complete. So we don't have to output an
918
* empty block here, this will be done at next call. This also
919
* ensures that for a very small output buffer, we emit at most
923
if (bstate == block_done) {
924
if (flush == Z_PARTIAL_FLUSH) {
926
} else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
927
_tr_stored_block(s, (char*)0, 0L, 0);
928
/* For a full flush, this empty block will be recognized
929
* as a special marker by inflate_sync().
931
if (flush == Z_FULL_FLUSH) {
932
CLEAR_HASH(s); /* forget history */
933
if (s->lookahead == 0) {
941
if (strm->avail_out == 0) {
942
s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
947
Assert(strm->avail_out > 0, "bug2");
949
if (flush != Z_FINISH) return Z_OK;
950
if (s->wrap <= 0) return Z_STREAM_END;
952
/* Write the trailer */
955
put_byte(s, (Byte)(strm->adler & 0xff));
956
put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
957
put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
958
put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
959
put_byte(s, (Byte)(strm->total_in & 0xff));
960
put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
961
put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
962
put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
967
putShortMSB(s, (uInt)(strm->adler >> 16));
968
putShortMSB(s, (uInt)(strm->adler & 0xffff));
971
/* If avail_out is zero, the application will call deflate again
974
if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
975
return s->pending != 0 ? Z_OK : Z_STREAM_END;
978
/* ========================================================================= */
979
int ZEXPORT deflateEnd (strm)
984
if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
986
status = strm->state->status;
987
if (status != INIT_STATE &&
988
status != EXTRA_STATE &&
989
status != NAME_STATE &&
990
status != COMMENT_STATE &&
991
status != HCRC_STATE &&
992
status != BUSY_STATE &&
993
status != FINISH_STATE) {
994
return Z_STREAM_ERROR;
997
/* Deallocate in reverse order of allocations: */
998
TRY_FREE(strm, strm->state->pending_buf);
999
TRY_FREE(strm, strm->state->head);
1000
TRY_FREE(strm, strm->state->prev);
1001
TRY_FREE(strm, strm->state->window);
1003
ZFREE(strm, strm->state);
1004
strm->state = Z_NULL;
1006
return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1009
/* =========================================================================
1010
* Copy the source state to the destination state.
1011
* To simplify the source, this is not supported for 16-bit MSDOS (which
1012
* doesn't have enough memory anyway to duplicate compression states).
1014
int ZEXPORT deflateCopy (dest, source)
1019
return Z_STREAM_ERROR;
1026
if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
1027
return Z_STREAM_ERROR;
1032
zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1034
ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1035
if (ds == Z_NULL) return Z_MEM_ERROR;
1036
dest->state = (struct internal_state FAR *) ds;
1037
zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1040
ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1041
ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1042
ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1043
overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1044
ds->pending_buf = (uchf *) overlay;
1046
if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1047
ds->pending_buf == Z_NULL) {
1051
/* following zmemcpy do not work for 16-bit MSDOS */
1052
zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1053
zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1054
zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1055
zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1057
ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1058
ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1059
ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1061
ds->l_desc.dyn_tree = ds->dyn_ltree;
1062
ds->d_desc.dyn_tree = ds->dyn_dtree;
1063
ds->bl_desc.dyn_tree = ds->bl_tree;
1066
#endif /* MAXSEG_64K */
1069
/* ===========================================================================
1070
* Read a new buffer from the current input stream, update the adler32
1071
* and total number of bytes read. All deflate() input goes through
1072
* this function so some applications may wish to modify it to avoid
1073
* allocating a large strm->next_in buffer and copying from it.
1074
* (See also flush_pending()).
1076
local int read_buf(strm, buf, size)
1081
unsigned len = strm->avail_in;
1083
if (len > size) len = size;
1084
if (len == 0) return 0;
1086
strm->avail_in -= len;
1088
zmemcpy(buf, strm->next_in, len);
1089
if (strm->state->wrap == 1) {
1090
strm->adler = adler32(strm->adler, buf, len);
1093
else if (strm->state->wrap == 2) {
1094
strm->adler = crc32(strm->adler, buf, len);
1097
strm->next_in += len;
1098
strm->total_in += len;
1103
/* ===========================================================================
1104
* Initialize the "longest match" routines for a new zlib stream
1106
local void lm_init (s)
1109
s->window_size = (ulg)2L*s->w_size;
1113
/* Set the default configuration parameters:
1115
s->max_lazy_match = configuration_table[s->level].max_lazy;
1116
s->good_match = configuration_table[s->level].good_length;
1117
s->nice_match = configuration_table[s->level].nice_length;
1118
s->max_chain_length = configuration_table[s->level].max_chain;
1121
s->block_start = 0L;
1124
s->match_length = s->prev_length = MIN_MATCH-1;
1125
s->match_available = 0;
1129
match_init(); /* initialize the asm code */
1135
/* ===========================================================================
1136
* Set match_start to the longest match starting at the given string and
1137
* return its length. Matches shorter or equal to prev_length are discarded,
1138
* in which case the result is equal to prev_length and match_start is
1140
* IN assertions: cur_match is the head of the hash chain for the current
1141
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1142
* OUT assertion: the match length is not greater than s->lookahead.
1145
/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1146
* match.S. The code will be functionally equivalent.
1148
local uInt longest_match(s, cur_match)
1150
IPos cur_match; /* current match */
1152
unsigned chain_length = s->max_chain_length;/* max hash chain length */
1153
register Bytef *scan = s->window + s->strstart; /* current string */
1154
register Bytef *match; /* matched string */
1155
register int len; /* length of current match */
1156
int best_len = s->prev_length; /* best match length so far */
1157
int nice_match = s->nice_match; /* stop if match long enough */
1158
IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1159
s->strstart - (IPos)MAX_DIST(s) : NIL;
1160
/* Stop when cur_match becomes <= limit. To simplify the code,
1161
* we prevent matches with the string of window index 0.
1163
Posf *prev = s->prev;
1164
uInt wmask = s->w_mask;
1167
/* Compare two bytes at a time. Note: this is not always beneficial.
1168
* Try with and without -DUNALIGNED_OK to check.
1170
register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1171
register ush scan_start = *(ushf*)scan;
1172
register ush scan_end = *(ushf*)(scan+best_len-1);
1174
register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1175
register Byte scan_end1 = scan[best_len-1];
1176
register Byte scan_end = scan[best_len];
1179
/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1180
* It is easy to get rid of this optimization if necessary.
1182
Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1184
/* Do not waste too much time if we already have a good match: */
1185
if (s->prev_length >= s->good_match) {
1188
/* Do not look for matches beyond the end of the input. This is necessary
1189
* to make deflate deterministic.
1191
if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1193
Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1196
Assert(cur_match < s->strstart, "no future");
1197
match = s->window + cur_match;
1199
/* Skip to next match if the match length cannot increase
1200
* or if the match length is less than 2. Note that the checks below
1201
* for insufficient lookahead only occur occasionally for performance
1202
* reasons. Therefore uninitialized memory will be accessed, and
1203
* conditional jumps will be made that depend on those values.
1204
* However the length of the match is limited to the lookahead, so
1205
* the output of deflate is not affected by the uninitialized values.
1207
#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1208
/* This code assumes sizeof(unsigned short) == 2. Do not use
1209
* UNALIGNED_OK if your compiler uses a different size.
1211
if (*(ushf*)(match+best_len-1) != scan_end ||
1212
*(ushf*)match != scan_start) continue;
1214
/* It is not necessary to compare scan[2] and match[2] since they are
1215
* always equal when the other bytes match, given that the hash keys
1216
* are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1217
* strstart+3, +5, ... up to strstart+257. We check for insufficient
1218
* lookahead only every 4th comparison; the 128th check will be made
1219
* at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1220
* necessary to put more guard bytes at the end of the window, or
1221
* to check more often for insufficient lookahead.
1223
Assert(scan[2] == match[2], "scan[2]?");
1226
} while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1227
*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1228
*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1229
*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1231
/* The funny "do {}" generates better code on most compilers */
1233
/* Here, scan <= window+strstart+257 */
1234
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1235
if (*scan == *match) scan++;
1237
len = (MAX_MATCH - 1) - (int)(strend-scan);
1238
scan = strend - (MAX_MATCH-1);
1240
#else /* UNALIGNED_OK */
1242
if (match[best_len] != scan_end ||
1243
match[best_len-1] != scan_end1 ||
1245
*++match != scan[1]) continue;
1247
/* The check at best_len-1 can be removed because it will be made
1248
* again later. (This heuristic is not always a win.)
1249
* It is not necessary to compare scan[2] and match[2] since they
1250
* are always equal when the other bytes match, given that
1251
* the hash keys are equal and that HASH_BITS >= 8.
1254
Assert(*scan == *match, "match[2]?");
1256
/* We check for insufficient lookahead only every 8th comparison;
1257
* the 256th check will be made at strstart+258.
1260
} while (*++scan == *++match && *++scan == *++match &&
1261
*++scan == *++match && *++scan == *++match &&
1262
*++scan == *++match && *++scan == *++match &&
1263
*++scan == *++match && *++scan == *++match &&
1266
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1268
len = MAX_MATCH - (int)(strend - scan);
1269
scan = strend - MAX_MATCH;
1271
#endif /* UNALIGNED_OK */
1273
if (len > best_len) {
1274
s->match_start = cur_match;
1276
if (len >= nice_match) break;
1278
scan_end = *(ushf*)(scan+best_len-1);
1280
scan_end1 = scan[best_len-1];
1281
scan_end = scan[best_len];
1284
} while ((cur_match = prev[cur_match & wmask]) > limit
1285
&& --chain_length != 0);
1287
if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1288
return s->lookahead;
1294
/* ---------------------------------------------------------------------------
1295
* Optimized version for FASTEST only
1297
local uInt longest_match(s, cur_match)
1299
IPos cur_match; /* current match */
1301
register Bytef *scan = s->window + s->strstart; /* current string */
1302
register Bytef *match; /* matched string */
1303
register int len; /* length of current match */
1304
register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1306
/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1307
* It is easy to get rid of this optimization if necessary.
1309
Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1311
Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1313
Assert(cur_match < s->strstart, "no future");
1315
match = s->window + cur_match;
1317
/* Return failure if the match length is less than 2:
1319
if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1321
/* The check at best_len-1 can be removed because it will be made
1322
* again later. (This heuristic is not always a win.)
1323
* It is not necessary to compare scan[2] and match[2] since they
1324
* are always equal when the other bytes match, given that
1325
* the hash keys are equal and that HASH_BITS >= 8.
1327
scan += 2, match += 2;
1328
Assert(*scan == *match, "match[2]?");
1330
/* We check for insufficient lookahead only every 8th comparison;
1331
* the 256th check will be made at strstart+258.
1334
} while (*++scan == *++match && *++scan == *++match &&
1335
*++scan == *++match && *++scan == *++match &&
1336
*++scan == *++match && *++scan == *++match &&
1337
*++scan == *++match && *++scan == *++match &&
1340
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1342
len = MAX_MATCH - (int)(strend - scan);
1344
if (len < MIN_MATCH) return MIN_MATCH - 1;
1346
s->match_start = cur_match;
1347
return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1350
#endif /* FASTEST */
1353
/* ===========================================================================
1354
* Check that the match at match_start is indeed a match.
1356
local void check_match(s, start, match, length)
1361
/* check that the match is indeed a match */
1362
if (zmemcmp(s->window + match,
1363
s->window + start, length) != EQUAL) {
1364
fprintf(stderr, " start %u, match %u, length %d\n",
1365
start, match, length);
1367
fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1368
} while (--length != 0);
1369
z_error("invalid match");
1371
if (z_verbose > 1) {
1372
fprintf(stderr,"\\[%d,%d]", start-match, length);
1373
do { putc(s->window[start++], stderr); } while (--length != 0);
1377
# define check_match(s, start, match, length)
1380
/* ===========================================================================
1381
* Fill the window when the lookahead becomes insufficient.
1382
* Updates strstart and lookahead.
1384
* IN assertion: lookahead < MIN_LOOKAHEAD
1385
* OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1386
* At least one byte has been read, or avail_in == 0; reads are
1387
* performed for at least two bytes (required for the zip translate_eol
1388
* option -- not supported here).
1390
local void fill_window(s)
1393
register unsigned n, m;
1395
unsigned more; /* Amount of free space at the end of the window. */
1396
uInt wsize = s->w_size;
1398
Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1401
more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1403
/* Deal with !@#$% 64K limit: */
1404
if (sizeof(int) <= 2) {
1405
if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1408
} else if (more == (unsigned)(-1)) {
1409
/* Very unlikely, but possible on 16 bit machine if
1410
* strstart == 0 && lookahead == 1 (input done a byte at time)
1416
/* If the window is almost full and there is insufficient lookahead,
1417
* move the upper half to the lower one to make room in the upper half.
1419
if (s->strstart >= wsize+MAX_DIST(s)) {
1421
zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1422
s->match_start -= wsize;
1423
s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1424
s->block_start -= (long) wsize;
1426
/* Slide the hash table (could be avoided with 32 bit values
1427
at the expense of memory usage). We slide even when level == 0
1428
to keep the hash table consistent if we switch back to level > 0
1429
later. (Using level 0 permanently is not an optimal usage of
1430
zlib, so we don't care about this pathological case.)
1436
*p = (Pos)(m >= wsize ? m-wsize : NIL);
1444
*p = (Pos)(m >= wsize ? m-wsize : NIL);
1445
/* If n is not on any hash chain, prev[n] is garbage but
1446
* its value will never be used.
1452
if (s->strm->avail_in == 0) break;
1454
/* If there was no sliding:
1455
* strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1456
* more == window_size - lookahead - strstart
1457
* => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1458
* => more >= window_size - 2*WSIZE + 2
1459
* In the BIG_MEM or MMAP case (not yet supported),
1460
* window_size == input_size + MIN_LOOKAHEAD &&
1461
* strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1462
* Otherwise, window_size == 2*WSIZE so more >= 2.
1463
* If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1465
Assert(more >= 2, "more < 2");
1467
n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1470
/* Initialize the hash value now that we have some input: */
1471
if (s->lookahead + s->insert >= MIN_MATCH) {
1472
uInt str = s->strstart - s->insert;
1473
s->ins_h = s->window[str];
1474
UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1476
Call UPDATE_HASH() MIN_MATCH-3 more times
1479
UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1481
s->prev[str & s->w_mask] = s->head[s->ins_h];
1483
s->head[s->ins_h] = (Pos)str;
1486
if (s->lookahead + s->insert < MIN_MATCH)
1490
/* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1491
* but this is not important since only literal bytes will be emitted.
1494
} while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1496
/* If the WIN_INIT bytes after the end of the current data have never been
1497
* written, then zero those bytes in order to avoid memory check reports of
1498
* the use of uninitialized (or uninitialised as Julian writes) bytes by
1499
* the longest match routines. Update the high water mark for the next
1500
* time through here. WIN_INIT is set to MAX_MATCH since the longest match
1501
* routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1503
if (s->high_water < s->window_size) {
1504
ulg curr = s->strstart + (ulg)(s->lookahead);
1507
if (s->high_water < curr) {
1508
/* Previous high water mark below current data -- zero WIN_INIT
1509
* bytes or up to end of window, whichever is less.
1511
init = s->window_size - curr;
1512
if (init > WIN_INIT)
1514
zmemzero(s->window + curr, (unsigned)init);
1515
s->high_water = curr + init;
1517
else if (s->high_water < (ulg)curr + WIN_INIT) {
1518
/* High water mark at or above current data, but below current data
1519
* plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1520
* to end of window, whichever is less.
1522
init = (ulg)curr + WIN_INIT - s->high_water;
1523
if (init > s->window_size - s->high_water)
1524
init = s->window_size - s->high_water;
1525
zmemzero(s->window + s->high_water, (unsigned)init);
1526
s->high_water += init;
1530
Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1531
"not enough room for search");
1534
/* ===========================================================================
1535
* Flush the current block, with given end-of-file flag.
1536
* IN assertion: strstart is set to the end of the current match.
1538
#define FLUSH_BLOCK_ONLY(s, last) { \
1539
_tr_flush_block(s, (s->block_start >= 0L ? \
1540
(charf *)&s->window[(unsigned)s->block_start] : \
1542
(ulg)((long)s->strstart - s->block_start), \
1544
s->block_start = s->strstart; \
1545
flush_pending(s->strm); \
1546
Tracev((stderr,"[FLUSH]")); \
1549
/* Same but force premature exit if necessary. */
1550
#define FLUSH_BLOCK(s, last) { \
1551
FLUSH_BLOCK_ONLY(s, last); \
1552
if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1555
/* ===========================================================================
1556
* Copy without compression as much as possible from the input stream, return
1557
* the current block state.
1558
* This function does not insert new strings in the dictionary since
1559
* uncompressible data is probably not useful. This function is used
1560
* only for the level=0 compression option.
1561
* NOTE: this function should be optimized to avoid extra copying from
1562
* window to pending_buf.
1564
local block_state deflate_stored(s, flush)
1568
/* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1569
* to pending_buf_size, and each stored block has a 5 byte header:
1571
ulg max_block_size = 0xffff;
1574
if (max_block_size > s->pending_buf_size - 5) {
1575
max_block_size = s->pending_buf_size - 5;
1578
/* Copy as much as possible from input to output: */
1580
/* Fill the window as much as possible: */
1581
if (s->lookahead <= 1) {
1583
Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1584
s->block_start >= (long)s->w_size, "slide too late");
1587
if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1589
if (s->lookahead == 0) break; /* flush the current block */
1591
Assert(s->block_start >= 0L, "block gone");
1593
s->strstart += s->lookahead;
1596
/* Emit a stored block if pending_buf will be full: */
1597
max_start = s->block_start + max_block_size;
1598
if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1599
/* strstart == 0 is possible when wraparound on 16-bit machine */
1600
s->lookahead = (uInt)(s->strstart - max_start);
1601
s->strstart = (uInt)max_start;
1604
/* Flush if we may have to slide, otherwise block_start may become
1605
* negative and the data will be gone:
1607
if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1612
if (flush == Z_FINISH) {
1616
if ((long)s->strstart > s->block_start)
1621
/* ===========================================================================
1622
* Compress as much as possible from the input stream, return the current
1624
* This function does not perform lazy evaluation of matches and inserts
1625
* new strings in the dictionary only for unmatched strings or for short
1626
* matches. It is used only for the fast compression options.
1628
local block_state deflate_fast(s, flush)
1632
IPos hash_head; /* head of the hash chain */
1633
int bflush; /* set if current block must be flushed */
1636
/* Make sure that we always have enough lookahead, except
1637
* at the end of the input file. We need MAX_MATCH bytes
1638
* for the next match, plus MIN_MATCH bytes to insert the
1639
* string following the next match.
1641
if (s->lookahead < MIN_LOOKAHEAD) {
1643
if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1646
if (s->lookahead == 0) break; /* flush the current block */
1649
/* Insert the string window[strstart .. strstart+2] in the
1650
* dictionary, and set hash_head to the head of the hash chain:
1653
if (s->lookahead >= MIN_MATCH) {
1654
INSERT_STRING(s, s->strstart, hash_head);
1657
/* Find the longest match, discarding those <= prev_length.
1658
* At this point we have always match_length < MIN_MATCH
1660
if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1661
/* To simplify the code, we prevent matches with the string
1662
* of window index 0 (in particular we have to avoid a match
1663
* of the string with itself at the start of the input file).
1665
s->match_length = longest_match (s, hash_head);
1666
/* longest_match() sets match_start */
1668
if (s->match_length >= MIN_MATCH) {
1669
check_match(s, s->strstart, s->match_start, s->match_length);
1671
_tr_tally_dist(s, s->strstart - s->match_start,
1672
s->match_length - MIN_MATCH, bflush);
1674
s->lookahead -= s->match_length;
1676
/* Insert new strings in the hash table only if the match length
1677
* is not too large. This saves time but degrades compression.
1680
if (s->match_length <= s->max_insert_length &&
1681
s->lookahead >= MIN_MATCH) {
1682
s->match_length--; /* string at strstart already in table */
1685
INSERT_STRING(s, s->strstart, hash_head);
1686
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
1687
* always MIN_MATCH bytes ahead.
1689
} while (--s->match_length != 0);
1694
s->strstart += s->match_length;
1695
s->match_length = 0;
1696
s->ins_h = s->window[s->strstart];
1697
UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1699
Call UPDATE_HASH() MIN_MATCH-3 more times
1701
/* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1702
* matter since it will be recomputed at next deflate call.
1706
/* No match, output a literal byte */
1707
Tracevv((stderr,"%c", s->window[s->strstart]));
1708
_tr_tally_lit (s, s->window[s->strstart], bflush);
1712
if (bflush) FLUSH_BLOCK(s, 0);
1714
s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1715
if (flush == Z_FINISH) {
1725
/* ===========================================================================
1726
* Same as above, but achieves better compression. We use a lazy
1727
* evaluation for matches: a match is finally adopted only if there is
1728
* no better match at the next window position.
1730
local block_state deflate_slow(s, flush)
1734
IPos hash_head; /* head of hash chain */
1735
int bflush; /* set if current block must be flushed */
1737
/* Process the input block. */
1739
/* Make sure that we always have enough lookahead, except
1740
* at the end of the input file. We need MAX_MATCH bytes
1741
* for the next match, plus MIN_MATCH bytes to insert the
1742
* string following the next match.
1744
if (s->lookahead < MIN_LOOKAHEAD) {
1746
if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1749
if (s->lookahead == 0) break; /* flush the current block */
1752
/* Insert the string window[strstart .. strstart+2] in the
1753
* dictionary, and set hash_head to the head of the hash chain:
1756
if (s->lookahead >= MIN_MATCH) {
1757
INSERT_STRING(s, s->strstart, hash_head);
1760
/* Find the longest match, discarding those <= prev_length.
1762
s->prev_length = s->match_length, s->prev_match = s->match_start;
1763
s->match_length = MIN_MATCH-1;
1765
if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1766
s->strstart - hash_head <= MAX_DIST(s)) {
1767
/* To simplify the code, we prevent matches with the string
1768
* of window index 0 (in particular we have to avoid a match
1769
* of the string with itself at the start of the input file).
1771
s->match_length = longest_match (s, hash_head);
1772
/* longest_match() sets match_start */
1774
if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1775
#if TOO_FAR <= 32767
1776
|| (s->match_length == MIN_MATCH &&
1777
s->strstart - s->match_start > TOO_FAR)
1781
/* If prev_match is also MIN_MATCH, match_start is garbage
1782
* but we will ignore the current match anyway.
1784
s->match_length = MIN_MATCH-1;
1787
/* If there was a match at the previous step and the current
1788
* match is not better, output the previous match:
1790
if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1791
uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1792
/* Do not insert strings in hash table beyond this. */
1794
check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1796
_tr_tally_dist(s, s->strstart -1 - s->prev_match,
1797
s->prev_length - MIN_MATCH, bflush);
1799
/* Insert in hash table all strings up to the end of the match.
1800
* strstart-1 and strstart are already inserted. If there is not
1801
* enough lookahead, the last two strings are not inserted in
1804
s->lookahead -= s->prev_length-1;
1805
s->prev_length -= 2;
1807
if (++s->strstart <= max_insert) {
1808
INSERT_STRING(s, s->strstart, hash_head);
1810
} while (--s->prev_length != 0);
1811
s->match_available = 0;
1812
s->match_length = MIN_MATCH-1;
1815
if (bflush) FLUSH_BLOCK(s, 0);
1817
} else if (s->match_available) {
1818
/* If there was no match at the previous position, output a
1819
* single literal. If there was a match but the current match
1820
* is longer, truncate the previous match to a single literal.
1822
Tracevv((stderr,"%c", s->window[s->strstart-1]));
1823
_tr_tally_lit(s, s->window[s->strstart-1], bflush);
1825
FLUSH_BLOCK_ONLY(s, 0);
1829
if (s->strm->avail_out == 0) return need_more;
1831
/* There is no previous match to compare with, wait for
1832
* the next step to decide.
1834
s->match_available = 1;
1839
Assert (flush != Z_NO_FLUSH, "no flush?");
1840
if (s->match_available) {
1841
Tracevv((stderr,"%c", s->window[s->strstart-1]));
1842
_tr_tally_lit(s, s->window[s->strstart-1], bflush);
1843
s->match_available = 0;
1845
s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1846
if (flush == Z_FINISH) {
1854
#endif /* FASTEST */
1856
/* ===========================================================================
1857
* For Z_RLE, simply look for runs of bytes, generate matches only of distance
1858
* one. Do not maintain a hash table. (It will be regenerated if this run of
1859
* deflate switches away from Z_RLE.)
1861
local block_state deflate_rle(s, flush)
1865
int bflush; /* set if current block must be flushed */
1866
uInt prev; /* byte at distance one to match */
1867
Bytef *scan, *strend; /* scan goes up to strend for length of run */
1870
/* Make sure that we always have enough lookahead, except
1871
* at the end of the input file. We need MAX_MATCH bytes
1872
* for the longest run, plus one for the unrolled loop.
1874
if (s->lookahead <= MAX_MATCH) {
1876
if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
1879
if (s->lookahead == 0) break; /* flush the current block */
1882
/* See how many times the previous byte repeats */
1883
s->match_length = 0;
1884
if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
1885
scan = s->window + s->strstart - 1;
1887
if (prev == *++scan && prev == *++scan && prev == *++scan) {
1888
strend = s->window + s->strstart + MAX_MATCH;
1890
} while (prev == *++scan && prev == *++scan &&
1891
prev == *++scan && prev == *++scan &&
1892
prev == *++scan && prev == *++scan &&
1893
prev == *++scan && prev == *++scan &&
1895
s->match_length = MAX_MATCH - (int)(strend - scan);
1896
if (s->match_length > s->lookahead)
1897
s->match_length = s->lookahead;
1899
Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
1902
/* Emit match if have run of MIN_MATCH or longer, else emit literal */
1903
if (s->match_length >= MIN_MATCH) {
1904
check_match(s, s->strstart, s->strstart - 1, s->match_length);
1906
_tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
1908
s->lookahead -= s->match_length;
1909
s->strstart += s->match_length;
1910
s->match_length = 0;
1912
/* No match, output a literal byte */
1913
Tracevv((stderr,"%c", s->window[s->strstart]));
1914
_tr_tally_lit (s, s->window[s->strstart], bflush);
1918
if (bflush) FLUSH_BLOCK(s, 0);
1921
if (flush == Z_FINISH) {
1930
/* ===========================================================================
1931
* For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
1932
* (It will be regenerated if this run of deflate switches away from Huffman.)
1934
local block_state deflate_huff(s, flush)
1938
int bflush; /* set if current block must be flushed */
1941
/* Make sure that we have a literal to write. */
1942
if (s->lookahead == 0) {
1944
if (s->lookahead == 0) {
1945
if (flush == Z_NO_FLUSH)
1947
break; /* flush the current block */
1951
/* Output a literal byte */
1952
s->match_length = 0;
1953
Tracevv((stderr,"%c", s->window[s->strstart]));
1954
_tr_tally_lit (s, s->window[s->strstart], bflush);
1957
if (bflush) FLUSH_BLOCK(s, 0);
1960
if (flush == Z_FINISH) {