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
11 * 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
17 * completely. Insertions are performed at each input character, whereas
18 * string matches are performed only when the previous match ends. So it
19 * is preferable to spend more time in matches to allow very fast string
20 * insertions and avoid deletions. The matching algorithm for small
21 * strings is inspired from that of Rabin & Karp. A brute force approach
22 * is used to find longer strings when a small match has been found.
23 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
24 * (by Leonid Broukhis).
25 * A previous version of this file used a more sophisticated algorithm
26 * (by Fiala and Greene) which is guaranteed to run in linear amortized
27 * time, but has a larger average cost, uses more memory and is patented.
28 * 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.
33 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
34 * I found it in 'freeze' written by Leonid Broukhis.
35 * Thanks to many people for bug reports and testing.
39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40 * Available in http://tools.ietf.org/html/rfc1951
42 * A description of the Rabin and Karp algorithm is given in the book
43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
45 * Fiala,E.R., and Greene,D.H.
46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
54 const char deflate_copyright[] =
55 " deflate 1.2.8.1 Copyright 1995-2013 Jean-loup Gailly and Mark Adler ";
57 If you use the zlib library in a product, an acknowledgment is welcome
58 in the documentation of your product. If for some reason you cannot
59 include such an acknowledgment, I would appreciate that you keep this
60 copyright string in the executable of your product.
63 /* ===========================================================================
64 * Function prototypes.
67 need_more, /* block not completed, need more input or more output */
68 block_done, /* block flush performed */
69 finish_started, /* finish started, need only more output at next deflate */
70 finish_done /* finish done, accept no more input or output */
73 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74 /* Compression function. Returns the block state after the call. */
76 local int deflateStateCheck OF((z_streamp strm));
77 local void fill_window OF((deflate_state *s));
78 local block_state deflate_stored OF((deflate_state *s, int flush));
79 local block_state deflate_fast OF((deflate_state *s, int flush));
81 local block_state deflate_slow OF((deflate_state *s, int flush));
83 local block_state deflate_rle OF((deflate_state *s, int flush));
84 local block_state deflate_huff OF((deflate_state *s, int flush));
85 local void lm_init OF((deflate_state *s));
86 local void putShortMSB OF((deflate_state *s, uInt b));
87 local void flush_pending OF((z_streamp strm));
88 local unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
90 void match_init OF((void)); /* asm code initialization */
91 uInt longest_match OF((deflate_state *s, IPos cur_match));
93 local uInt longest_match OF((deflate_state *s, IPos cur_match));
97 local void check_match OF((deflate_state *s, IPos start, IPos match,
101 /* ===========================================================================
106 /* Tail of hash chains */
109 # define TOO_FAR 4096
111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
113 /* Values for max_lazy_match, good_match and max_chain_length, depending on
114 * the desired pack level (0..9). The values given below have been tuned to
115 * exclude worst case performance for pathological files. Better values may be
116 * found for specific files.
118 typedef struct config_s {
119 ush good_length; /* reduce lazy search above this match length */
120 ush max_lazy; /* do not perform lazy search above this match length */
121 ush nice_length; /* quit search above this match length */
127 local const config configuration_table[2] = {
128 /* good lazy nice chain */
129 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
130 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
132 local const config configuration_table[10] = {
133 /* good lazy nice chain */
134 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
135 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
136 /* 2 */ {4, 5, 16, 8, deflate_fast},
137 /* 3 */ {4, 6, 32, 32, deflate_fast},
139 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
140 /* 5 */ {8, 16, 32, 32, deflate_slow},
141 /* 6 */ {8, 16, 128, 128, deflate_slow},
142 /* 7 */ {8, 32, 128, 256, deflate_slow},
143 /* 8 */ {32, 128, 258, 1024, deflate_slow},
144 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
147 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
148 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
152 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
153 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0))
155 /* ===========================================================================
156 * Update a hash value with the given input byte
157 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
158 * input characters, so that a running hash key can be computed from the
159 * previous key instead of complete recalculation each time.
161 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
164 /* ===========================================================================
165 * Insert string str in the dictionary and set match_head to the previous head
166 * of the hash chain (the most recent string with same hash key). Return
167 * the previous length of the hash chain.
168 * If this file is compiled with -DFASTEST, the compression level is forced
169 * to 1, and no hash chains are maintained.
170 * IN assertion: all calls to to INSERT_STRING are made with consecutive
171 * input characters and the first MIN_MATCH bytes of str are valid
172 * (except for the last MIN_MATCH-1 bytes of the input file).
175 #define INSERT_STRING(s, str, match_head) \
176 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
177 match_head = s->head[s->ins_h], \
178 s->head[s->ins_h] = (Pos)(str))
180 #define INSERT_STRING(s, str, match_head) \
181 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
182 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
183 s->head[s->ins_h] = (Pos)(str))
186 /* ===========================================================================
187 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
188 * prev[] will be initialized on the fly.
190 #define CLEAR_HASH(s) \
191 s->head[s->hash_size-1] = NIL; \
192 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
194 /* ========================================================================= */
195 int ZEXPORT deflateInit_(strm, level, version, stream_size)
201 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
202 Z_DEFAULT_STRATEGY, version, stream_size);
203 /* To do: ignore strm->next_in if we use it as window */
206 /* ========================================================================= */
207 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
208 version, stream_size)
220 static const char my_version[] = ZLIB_VERSION;
223 /* We overlay pending_buf and d_buf+l_buf. This works since the average
224 * output size for (length,distance) codes is <= 24 bits.
227 if (version == Z_NULL || version[0] != my_version[0] ||
228 stream_size != sizeof(z_stream)) {
229 return Z_VERSION_ERROR;
231 if (strm == Z_NULL) return Z_STREAM_ERROR;
234 if (strm->zalloc == (alloc_func)0) {
236 return Z_STREAM_ERROR;
238 strm->zalloc = zcalloc;
239 strm->opaque = (voidpf)0;
242 if (strm->zfree == (free_func)0)
244 return Z_STREAM_ERROR;
246 strm->zfree = zcfree;
250 if (level != 0) level = 1;
252 if (level == Z_DEFAULT_COMPRESSION) level = 6;
255 if (windowBits < 0) { /* suppress zlib wrapper */
257 windowBits = -windowBits;
260 else if (windowBits > 15) {
261 wrap = 2; /* write gzip wrapper instead */
265 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
266 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
267 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) {
268 return Z_STREAM_ERROR;
270 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
271 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
272 if (s == Z_NULL) return Z_MEM_ERROR;
273 strm->state = (struct internal_state FAR *)s;
275 s->status = INIT_STATE; /* to pass state test in deflateReset() */
279 s->w_bits = (uInt)windowBits;
280 s->w_size = 1 << s->w_bits;
281 s->w_mask = s->w_size - 1;
283 s->hash_bits = (uInt)memLevel + 7;
284 s->hash_size = 1 << s->hash_bits;
285 s->hash_mask = s->hash_size - 1;
286 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
288 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
289 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
290 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
292 s->high_water = 0; /* nothing written to s->window yet */
294 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
296 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
297 s->pending_buf = (uchf *) overlay;
298 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
300 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
301 s->pending_buf == Z_NULL) {
302 s->status = FINISH_STATE;
303 strm->msg = ERR_MSG(Z_MEM_ERROR);
307 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
308 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
311 s->strategy = strategy;
312 s->method = (Byte)method;
314 return deflateReset(strm);
317 /* =========================================================================
318 * Check for a valid deflate stream state. Return 0 if ok, 1 if not.
320 local int deflateStateCheck (strm)
324 if (strm == Z_NULL ||
325 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0)
328 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE &&
329 s->status != EXTRA_STATE &&
330 s->status != NAME_STATE &&
331 s->status != COMMENT_STATE &&
332 s->status != HCRC_STATE &&
333 s->status != BUSY_STATE &&
334 s->status != FINISH_STATE))
339 /* ========================================================================= */
340 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
342 const Bytef *dictionary;
349 z_const unsigned char *next;
351 if (deflateStateCheck(strm) || dictionary == Z_NULL)
352 return Z_STREAM_ERROR;
355 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
356 return Z_STREAM_ERROR;
358 /* when using zlib wrappers, compute Adler-32 for provided dictionary */
360 strm->adler = adler32(strm->adler, dictionary, dictLength);
361 s->wrap = 0; /* avoid computing Adler-32 in read_buf */
363 /* if dictionary would fill window, just replace the history */
364 if (dictLength >= s->w_size) {
365 if (wrap == 0) { /* already empty otherwise */
371 dictionary += dictLength - s->w_size; /* use the tail */
372 dictLength = s->w_size;
375 /* insert dictionary into window and hash */
376 avail = strm->avail_in;
377 next = strm->next_in;
378 strm->avail_in = dictLength;
379 strm->next_in = (z_const Bytef *)dictionary;
381 while (s->lookahead >= MIN_MATCH) {
383 n = s->lookahead - (MIN_MATCH-1);
385 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
387 s->prev[str & s->w_mask] = s->head[s->ins_h];
389 s->head[s->ins_h] = (Pos)str;
393 s->lookahead = MIN_MATCH-1;
396 s->strstart += s->lookahead;
397 s->block_start = (long)s->strstart;
398 s->insert = s->lookahead;
400 s->match_length = s->prev_length = MIN_MATCH-1;
401 s->match_available = 0;
402 strm->next_in = next;
403 strm->avail_in = avail;
408 /* ========================================================================= */
409 int ZEXPORT deflateResetKeep (strm)
414 if (deflateStateCheck(strm)) {
415 return Z_STREAM_ERROR;
418 strm->total_in = strm->total_out = 0;
419 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
420 strm->data_type = Z_UNKNOWN;
422 s = (deflate_state *)strm->state;
424 s->pending_out = s->pending_buf;
427 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
429 s->status = s->wrap ? INIT_STATE : BUSY_STATE;
432 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
434 adler32(0L, Z_NULL, 0);
435 s->last_flush = Z_NO_FLUSH;
442 /* ========================================================================= */
443 int ZEXPORT deflateReset (strm)
448 ret = deflateResetKeep(strm);
450 lm_init(strm->state);
454 /* ========================================================================= */
455 int ZEXPORT deflateSetHeader (strm, head)
459 if (deflateStateCheck(strm) || strm->state->wrap != 2)
460 return Z_STREAM_ERROR;
461 strm->state->gzhead = head;
465 /* ========================================================================= */
466 int ZEXPORT deflatePending (strm, pending, bits)
471 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
472 if (pending != Z_NULL)
473 *pending = strm->state->pending;
475 *bits = strm->state->bi_valid;
479 /* ========================================================================= */
480 int ZEXPORT deflatePrime (strm, bits, value)
488 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
490 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
493 put = Buf_size - s->bi_valid;
496 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
505 /* ========================================================================= */
506 int ZEXPORT deflateParams(strm, level, strategy)
515 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
519 if (level != 0) level = 1;
521 if (level == Z_DEFAULT_COMPRESSION) level = 6;
523 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
524 return Z_STREAM_ERROR;
526 func = configuration_table[s->level].func;
528 if ((strategy != s->strategy || func != configuration_table[level].func)) {
529 /* Flush the last buffer: */
530 err = deflate(strm, Z_BLOCK);
531 if (err == Z_BUF_ERROR && s->pending == 0)
534 if (s->level != level) {
536 s->max_lazy_match = configuration_table[level].max_lazy;
537 s->good_match = configuration_table[level].good_length;
538 s->nice_match = configuration_table[level].nice_length;
539 s->max_chain_length = configuration_table[level].max_chain;
541 s->strategy = strategy;
545 /* ========================================================================= */
546 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
555 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
557 s->good_match = (uInt)good_length;
558 s->max_lazy_match = (uInt)max_lazy;
559 s->nice_match = nice_length;
560 s->max_chain_length = (uInt)max_chain;
564 /* =========================================================================
565 * For the default windowBits of 15 and memLevel of 8, this function returns
566 * a close to exact, as well as small, upper bound on the compressed size.
567 * They are coded as constants here for a reason--if the #define's are
568 * changed, then this function needs to be changed as well. The return
569 * value for 15 and 8 only works for those exact settings.
571 * For any setting other than those defaults for windowBits and memLevel,
572 * the value returned is a conservative worst case for the maximum expansion
573 * resulting from using fixed blocks instead of stored blocks, which deflate
574 * can emit on compressed data for some combinations of the parameters.
576 * This function could be more sophisticated to provide closer upper bounds for
577 * every combination of windowBits and memLevel. But even the conservative
578 * upper bound of about 14% expansion does not seem onerous for output buffer
581 uLong ZEXPORT deflateBound(strm, sourceLen)
586 uLong complen, wraplen;
589 /* conservative upper bound for compressed data */
590 complen = sourceLen +
591 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
593 /* if can't get parameters, return conservative bound plus zlib wrapper */
594 if (deflateStateCheck(strm))
597 /* compute wrapper length */
600 case 0: /* raw deflate */
603 case 1: /* zlib wrapper */
604 wraplen = 6 + (s->strstart ? 4 : 0);
606 case 2: /* gzip wrapper */
608 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
609 if (s->gzhead->extra != Z_NULL)
610 wraplen += 2 + s->gzhead->extra_len;
611 str = s->gzhead->name;
616 str = s->gzhead->comment;
625 default: /* for compiler happiness */
629 /* if not default parameters, return conservative bound */
630 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
631 return complen + wraplen;
633 /* default settings: return tight bound for that case */
634 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
635 (sourceLen >> 25) + 13 - 6 + wraplen;
638 /* =========================================================================
639 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
640 * IN assertion: the stream state is correct and there is enough room in
643 local void putShortMSB (s, b)
647 put_byte(s, (Byte)(b >> 8));
648 put_byte(s, (Byte)(b & 0xff));
651 /* =========================================================================
652 * Flush as much pending output as possible. All deflate() output goes
653 * through this function so some applications may wish to modify it
654 * to avoid allocating a large strm->next_out buffer and copying into it.
655 * (See also read_buf()).
657 local void flush_pending(strm)
661 deflate_state *s = strm->state;
665 if (len > strm->avail_out) len = strm->avail_out;
666 if (len == 0) return;
668 zmemcpy(strm->next_out, s->pending_out, len);
669 strm->next_out += len;
670 s->pending_out += len;
671 strm->total_out += len;
672 strm->avail_out -= len;
674 if (s->pending == 0) {
675 s->pending_out = s->pending_buf;
679 /* ========================================================================= */
680 int ZEXPORT deflate (strm, flush)
684 int old_flush; /* value of flush param for previous deflate call */
687 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) {
688 return Z_STREAM_ERROR;
692 if (strm->next_out == Z_NULL ||
693 (strm->avail_in != 0 && strm->next_in == Z_NULL) ||
694 (s->status == FINISH_STATE && flush != Z_FINISH)) {
695 ERR_RETURN(strm, Z_STREAM_ERROR);
697 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
699 s->strm = strm; /* just in case */
700 old_flush = s->last_flush;
701 s->last_flush = flush;
703 /* Write the header */
704 if (s->status == INIT_STATE) {
707 strm->adler = crc32(0L, Z_NULL, 0);
711 if (s->gzhead == Z_NULL) {
717 put_byte(s, s->level == 9 ? 2 :
718 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
720 put_byte(s, OS_CODE);
721 s->status = BUSY_STATE;
724 put_byte(s, (s->gzhead->text ? 1 : 0) +
725 (s->gzhead->hcrc ? 2 : 0) +
726 (s->gzhead->extra == Z_NULL ? 0 : 4) +
727 (s->gzhead->name == Z_NULL ? 0 : 8) +
728 (s->gzhead->comment == Z_NULL ? 0 : 16)
730 put_byte(s, (Byte)(s->gzhead->time & 0xff));
731 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
732 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
733 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
734 put_byte(s, s->level == 9 ? 2 :
735 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
737 put_byte(s, s->gzhead->os & 0xff);
738 if (s->gzhead->extra != Z_NULL) {
739 put_byte(s, s->gzhead->extra_len & 0xff);
740 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
743 strm->adler = crc32(strm->adler, s->pending_buf,
746 s->status = EXTRA_STATE;
752 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
755 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
757 else if (s->level < 6)
759 else if (s->level == 6)
763 header |= (level_flags << 6);
764 if (s->strstart != 0) header |= PRESET_DICT;
765 header += 31 - (header % 31);
767 s->status = BUSY_STATE;
768 putShortMSB(s, header);
770 /* Save the adler32 of the preset dictionary: */
771 if (s->strstart != 0) {
772 putShortMSB(s, (uInt)(strm->adler >> 16));
773 putShortMSB(s, (uInt)(strm->adler & 0xffff));
775 strm->adler = adler32(0L, Z_NULL, 0);
779 if (s->status == EXTRA_STATE) {
780 if (s->gzhead->extra != Z_NULL) {
781 uInt beg = s->pending; /* start of bytes to update crc */
783 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
784 if (s->pending == s->pending_buf_size) {
785 if (s->gzhead->hcrc && s->pending > beg)
786 strm->adler = crc32(strm->adler, s->pending_buf + beg,
790 if (s->pending == s->pending_buf_size)
793 put_byte(s, s->gzhead->extra[s->gzindex]);
796 if (s->gzhead->hcrc && s->pending > beg)
797 strm->adler = crc32(strm->adler, s->pending_buf + beg,
799 if (s->gzindex == s->gzhead->extra_len) {
801 s->status = NAME_STATE;
805 s->status = NAME_STATE;
807 if (s->status == NAME_STATE) {
808 if (s->gzhead->name != Z_NULL) {
809 uInt beg = s->pending; /* start of bytes to update crc */
813 if (s->pending == s->pending_buf_size) {
814 if (s->gzhead->hcrc && s->pending > beg)
815 strm->adler = crc32(strm->adler, s->pending_buf + beg,
819 if (s->pending == s->pending_buf_size) {
824 val = s->gzhead->name[s->gzindex++];
827 if (s->gzhead->hcrc && s->pending > beg)
828 strm->adler = crc32(strm->adler, s->pending_buf + beg,
832 s->status = COMMENT_STATE;
836 s->status = COMMENT_STATE;
838 if (s->status == COMMENT_STATE) {
839 if (s->gzhead->comment != Z_NULL) {
840 uInt beg = s->pending; /* start of bytes to update crc */
844 if (s->pending == s->pending_buf_size) {
845 if (s->gzhead->hcrc && s->pending > beg)
846 strm->adler = crc32(strm->adler, s->pending_buf + beg,
850 if (s->pending == s->pending_buf_size) {
855 val = s->gzhead->comment[s->gzindex++];
858 if (s->gzhead->hcrc && s->pending > beg)
859 strm->adler = crc32(strm->adler, s->pending_buf + beg,
862 s->status = HCRC_STATE;
865 s->status = HCRC_STATE;
867 if (s->status == HCRC_STATE) {
868 if (s->gzhead->hcrc) {
869 if (s->pending + 2 > s->pending_buf_size)
871 if (s->pending + 2 <= s->pending_buf_size) {
872 put_byte(s, (Byte)(strm->adler & 0xff));
873 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
874 strm->adler = crc32(0L, Z_NULL, 0);
875 s->status = BUSY_STATE;
879 s->status = BUSY_STATE;
883 /* Flush as much pending output as possible */
884 if (s->pending != 0) {
886 if (strm->avail_out == 0) {
887 /* Since avail_out is 0, deflate will be called again with
888 * more output space, but possibly with both pending and
889 * avail_in equal to zero. There won't be anything to do,
890 * but this is not an error situation so make sure we
891 * return OK instead of BUF_ERROR at next call of deflate:
897 /* Make sure there is something to do and avoid duplicate consecutive
898 * flushes. For repeated and useless calls with Z_FINISH, we keep
899 * returning Z_STREAM_END instead of Z_BUF_ERROR.
901 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
903 ERR_RETURN(strm, Z_BUF_ERROR);
906 /* User must not provide more input after the first FINISH: */
907 if (s->status == FINISH_STATE && strm->avail_in != 0) {
908 ERR_RETURN(strm, Z_BUF_ERROR);
911 /* Start a new block or continue the current one.
913 if (strm->avail_in != 0 || s->lookahead != 0 ||
914 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
917 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
918 (s->strategy == Z_RLE ? deflate_rle(s, flush) :
919 (*(configuration_table[s->level].func))(s, flush));
921 if (bstate == finish_started || bstate == finish_done) {
922 s->status = FINISH_STATE;
924 if (bstate == need_more || bstate == finish_started) {
925 if (strm->avail_out == 0) {
926 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
929 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
930 * of deflate should use the same flush parameter to make sure
931 * that the flush is complete. So we don't have to output an
932 * empty block here, this will be done at next call. This also
933 * ensures that for a very small output buffer, we emit at most
937 if (bstate == block_done) {
938 if (flush == Z_PARTIAL_FLUSH) {
940 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
941 _tr_stored_block(s, (char*)0, 0L, 0);
942 /* For a full flush, this empty block will be recognized
943 * as a special marker by inflate_sync().
945 if (flush == Z_FULL_FLUSH) {
946 CLEAR_HASH(s); /* forget history */
947 if (s->lookahead == 0) {
955 if (strm->avail_out == 0) {
956 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
961 Assert(strm->avail_out > 0, "bug2");
963 if (flush != Z_FINISH) return Z_OK;
964 if (s->wrap <= 0) return Z_STREAM_END;
966 /* Write the trailer */
969 put_byte(s, (Byte)(strm->adler & 0xff));
970 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
971 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
972 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
973 put_byte(s, (Byte)(strm->total_in & 0xff));
974 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
975 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
976 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
981 putShortMSB(s, (uInt)(strm->adler >> 16));
982 putShortMSB(s, (uInt)(strm->adler & 0xffff));
985 /* If avail_out is zero, the application will call deflate again
988 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
989 return s->pending != 0 ? Z_OK : Z_STREAM_END;
992 /* ========================================================================= */
993 int ZEXPORT deflateEnd (strm)
998 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
1000 status = strm->state->status;
1002 /* Deallocate in reverse order of allocations: */
1003 TRY_FREE(strm, strm->state->pending_buf);
1004 TRY_FREE(strm, strm->state->head);
1005 TRY_FREE(strm, strm->state->prev);
1006 TRY_FREE(strm, strm->state->window);
1008 ZFREE(strm, strm->state);
1009 strm->state = Z_NULL;
1011 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1014 /* =========================================================================
1015 * Copy the source state to the destination state.
1016 * To simplify the source, this is not supported for 16-bit MSDOS (which
1017 * doesn't have enough memory anyway to duplicate compression states).
1019 int ZEXPORT deflateCopy (dest, source)
1024 return Z_STREAM_ERROR;
1031 if (deflateStateCheck(source) || dest == Z_NULL) {
1032 return Z_STREAM_ERROR;
1037 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1039 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1040 if (ds == Z_NULL) return Z_MEM_ERROR;
1041 dest->state = (struct internal_state FAR *) ds;
1042 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1045 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1046 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1047 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1048 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1049 ds->pending_buf = (uchf *) overlay;
1051 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1052 ds->pending_buf == Z_NULL) {
1056 /* following zmemcpy do not work for 16-bit MSDOS */
1057 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1058 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1059 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1060 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1062 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1063 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1064 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1066 ds->l_desc.dyn_tree = ds->dyn_ltree;
1067 ds->d_desc.dyn_tree = ds->dyn_dtree;
1068 ds->bl_desc.dyn_tree = ds->bl_tree;
1071 #endif /* MAXSEG_64K */
1074 /* ===========================================================================
1075 * Read a new buffer from the current input stream, update the adler32
1076 * and total number of bytes read. All deflate() input goes through
1077 * this function so some applications may wish to modify it to avoid
1078 * allocating a large strm->next_in buffer and copying from it.
1079 * (See also flush_pending()).
1081 local unsigned read_buf(strm, buf, size)
1086 unsigned len = strm->avail_in;
1088 if (len > size) len = size;
1089 if (len == 0) return 0;
1091 strm->avail_in -= len;
1093 zmemcpy(buf, strm->next_in, len);
1094 if (strm->state->wrap == 1) {
1095 strm->adler = adler32(strm->adler, buf, len);
1098 else if (strm->state->wrap == 2) {
1099 strm->adler = crc32(strm->adler, buf, len);
1102 strm->next_in += len;
1103 strm->total_in += len;
1108 /* ===========================================================================
1109 * Initialize the "longest match" routines for a new zlib stream
1111 local void lm_init (s)
1114 s->window_size = (ulg)2L*s->w_size;
1118 /* Set the default configuration parameters:
1120 s->max_lazy_match = configuration_table[s->level].max_lazy;
1121 s->good_match = configuration_table[s->level].good_length;
1122 s->nice_match = configuration_table[s->level].nice_length;
1123 s->max_chain_length = configuration_table[s->level].max_chain;
1126 s->block_start = 0L;
1129 s->match_length = s->prev_length = MIN_MATCH-1;
1130 s->match_available = 0;
1134 match_init(); /* initialize the asm code */
1140 /* ===========================================================================
1141 * Set match_start to the longest match starting at the given string and
1142 * return its length. Matches shorter or equal to prev_length are discarded,
1143 * in which case the result is equal to prev_length and match_start is
1145 * IN assertions: cur_match is the head of the hash chain for the current
1146 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1147 * OUT assertion: the match length is not greater than s->lookahead.
1150 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1151 * match.S. The code will be functionally equivalent.
1153 local uInt longest_match(s, cur_match)
1155 IPos cur_match; /* current match */
1157 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1158 register Bytef *scan = s->window + s->strstart; /* current string */
1159 register Bytef *match; /* matched string */
1160 register int len; /* length of current match */
1161 int best_len = (int)s->prev_length; /* best match length so far */
1162 int nice_match = s->nice_match; /* stop if match long enough */
1163 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1164 s->strstart - (IPos)MAX_DIST(s) : NIL;
1165 /* Stop when cur_match becomes <= limit. To simplify the code,
1166 * we prevent matches with the string of window index 0.
1168 Posf *prev = s->prev;
1169 uInt wmask = s->w_mask;
1172 /* Compare two bytes at a time. Note: this is not always beneficial.
1173 * Try with and without -DUNALIGNED_OK to check.
1175 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1176 register ush scan_start = *(ushf*)scan;
1177 register ush scan_end = *(ushf*)(scan+best_len-1);
1179 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1180 register Byte scan_end1 = scan[best_len-1];
1181 register Byte scan_end = scan[best_len];
1184 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1185 * It is easy to get rid of this optimization if necessary.
1187 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1189 /* Do not waste too much time if we already have a good match: */
1190 if (s->prev_length >= s->good_match) {
1193 /* Do not look for matches beyond the end of the input. This is necessary
1194 * to make deflate deterministic.
1196 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead;
1198 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1201 Assert(cur_match < s->strstart, "no future");
1202 match = s->window + cur_match;
1204 /* Skip to next match if the match length cannot increase
1205 * or if the match length is less than 2. Note that the checks below
1206 * for insufficient lookahead only occur occasionally for performance
1207 * reasons. Therefore uninitialized memory will be accessed, and
1208 * conditional jumps will be made that depend on those values.
1209 * However the length of the match is limited to the lookahead, so
1210 * the output of deflate is not affected by the uninitialized values.
1212 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1213 /* This code assumes sizeof(unsigned short) == 2. Do not use
1214 * UNALIGNED_OK if your compiler uses a different size.
1216 if (*(ushf*)(match+best_len-1) != scan_end ||
1217 *(ushf*)match != scan_start) continue;
1219 /* It is not necessary to compare scan[2] and match[2] since they are
1220 * always equal when the other bytes match, given that the hash keys
1221 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1222 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1223 * lookahead only every 4th comparison; the 128th check will be made
1224 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1225 * necessary to put more guard bytes at the end of the window, or
1226 * to check more often for insufficient lookahead.
1228 Assert(scan[2] == match[2], "scan[2]?");
1231 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1232 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1233 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1234 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1236 /* The funny "do {}" generates better code on most compilers */
1238 /* Here, scan <= window+strstart+257 */
1239 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1240 if (*scan == *match) scan++;
1242 len = (MAX_MATCH - 1) - (int)(strend-scan);
1243 scan = strend - (MAX_MATCH-1);
1245 #else /* UNALIGNED_OK */
1247 if (match[best_len] != scan_end ||
1248 match[best_len-1] != scan_end1 ||
1250 *++match != scan[1]) continue;
1252 /* The check at best_len-1 can be removed because it will be made
1253 * again later. (This heuristic is not always a win.)
1254 * It is not necessary to compare scan[2] and match[2] since they
1255 * are always equal when the other bytes match, given that
1256 * the hash keys are equal and that HASH_BITS >= 8.
1259 Assert(*scan == *match, "match[2]?");
1261 /* We check for insufficient lookahead only every 8th comparison;
1262 * the 256th check will be made at strstart+258.
1265 } while (*++scan == *++match && *++scan == *++match &&
1266 *++scan == *++match && *++scan == *++match &&
1267 *++scan == *++match && *++scan == *++match &&
1268 *++scan == *++match && *++scan == *++match &&
1271 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1273 len = MAX_MATCH - (int)(strend - scan);
1274 scan = strend - MAX_MATCH;
1276 #endif /* UNALIGNED_OK */
1278 if (len > best_len) {
1279 s->match_start = cur_match;
1281 if (len >= nice_match) break;
1283 scan_end = *(ushf*)(scan+best_len-1);
1285 scan_end1 = scan[best_len-1];
1286 scan_end = scan[best_len];
1289 } while ((cur_match = prev[cur_match & wmask]) > limit
1290 && --chain_length != 0);
1292 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1293 return s->lookahead;
1299 /* ---------------------------------------------------------------------------
1300 * Optimized version for FASTEST only
1302 local uInt longest_match(s, cur_match)
1304 IPos cur_match; /* current match */
1306 register Bytef *scan = s->window + s->strstart; /* current string */
1307 register Bytef *match; /* matched string */
1308 register int len; /* length of current match */
1309 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1311 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1312 * It is easy to get rid of this optimization if necessary.
1314 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1316 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1318 Assert(cur_match < s->strstart, "no future");
1320 match = s->window + cur_match;
1322 /* Return failure if the match length is less than 2:
1324 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1326 /* The check at best_len-1 can be removed because it will be made
1327 * again later. (This heuristic is not always a win.)
1328 * It is not necessary to compare scan[2] and match[2] since they
1329 * are always equal when the other bytes match, given that
1330 * the hash keys are equal and that HASH_BITS >= 8.
1332 scan += 2, match += 2;
1333 Assert(*scan == *match, "match[2]?");
1335 /* We check for insufficient lookahead only every 8th comparison;
1336 * the 256th check will be made at strstart+258.
1339 } while (*++scan == *++match && *++scan == *++match &&
1340 *++scan == *++match && *++scan == *++match &&
1341 *++scan == *++match && *++scan == *++match &&
1342 *++scan == *++match && *++scan == *++match &&
1345 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1347 len = MAX_MATCH - (int)(strend - scan);
1349 if (len < MIN_MATCH) return MIN_MATCH - 1;
1351 s->match_start = cur_match;
1352 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1355 #endif /* FASTEST */
1360 /* result of memcmp for equal strings */
1362 /* ===========================================================================
1363 * Check that the match at match_start is indeed a match.
1365 local void check_match(s, start, match, length)
1370 /* check that the match is indeed a match */
1371 if (zmemcmp(s->window + match,
1372 s->window + start, length) != EQUAL) {
1373 fprintf(stderr, " start %u, match %u, length %d\n",
1374 start, match, length);
1376 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1377 } while (--length != 0);
1378 z_error("invalid match");
1380 if (z_verbose > 1) {
1381 fprintf(stderr,"\\[%d,%d]", start-match, length);
1382 do { putc(s->window[start++], stderr); } while (--length != 0);
1386 # define check_match(s, start, match, length)
1387 #endif /* ZLIB_DEBUG */
1389 /* ===========================================================================
1390 * Fill the window when the lookahead becomes insufficient.
1391 * Updates strstart and lookahead.
1393 * IN assertion: lookahead < MIN_LOOKAHEAD
1394 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1395 * At least one byte has been read, or avail_in == 0; reads are
1396 * performed for at least two bytes (required for the zip translate_eol
1397 * option -- not supported here).
1399 local void fill_window(s)
1402 register unsigned n, m;
1404 unsigned more; /* Amount of free space at the end of the window. */
1405 uInt wsize = s->w_size;
1407 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1410 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1412 /* Deal with !@#$% 64K limit: */
1413 if (sizeof(int) <= 2) {
1414 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1417 } else if (more == (unsigned)(-1)) {
1418 /* Very unlikely, but possible on 16 bit machine if
1419 * strstart == 0 && lookahead == 1 (input done a byte at time)
1425 /* If the window is almost full and there is insufficient lookahead,
1426 * move the upper half to the lower one to make room in the upper half.
1428 if (s->strstart >= wsize+MAX_DIST(s)) {
1430 zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1431 s->match_start -= wsize;
1432 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1433 s->block_start -= (long) wsize;
1435 /* Slide the hash table (could be avoided with 32 bit values
1436 at the expense of memory usage). We slide even when level == 0
1437 to keep the hash table consistent if we switch back to level > 0
1438 later. (Using level 0 permanently is not an optimal usage of
1439 zlib, so we don't care about this pathological case.)
1445 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1453 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1454 /* If n is not on any hash chain, prev[n] is garbage but
1455 * its value will never be used.
1461 if (s->strm->avail_in == 0) break;
1463 /* If there was no sliding:
1464 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1465 * more == window_size - lookahead - strstart
1466 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1467 * => more >= window_size - 2*WSIZE + 2
1468 * In the BIG_MEM or MMAP case (not yet supported),
1469 * window_size == input_size + MIN_LOOKAHEAD &&
1470 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1471 * Otherwise, window_size == 2*WSIZE so more >= 2.
1472 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1474 Assert(more >= 2, "more < 2");
1476 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1479 /* Initialize the hash value now that we have some input: */
1480 if (s->lookahead + s->insert >= MIN_MATCH) {
1481 uInt str = s->strstart - s->insert;
1482 s->ins_h = s->window[str];
1483 UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1485 Call UPDATE_HASH() MIN_MATCH-3 more times
1488 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1490 s->prev[str & s->w_mask] = s->head[s->ins_h];
1492 s->head[s->ins_h] = (Pos)str;
1495 if (s->lookahead + s->insert < MIN_MATCH)
1499 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1500 * but this is not important since only literal bytes will be emitted.
1503 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1505 /* If the WIN_INIT bytes after the end of the current data have never been
1506 * written, then zero those bytes in order to avoid memory check reports of
1507 * the use of uninitialized (or uninitialised as Julian writes) bytes by
1508 * the longest match routines. Update the high water mark for the next
1509 * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1510 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1512 if (s->high_water < s->window_size) {
1513 ulg curr = s->strstart + (ulg)(s->lookahead);
1516 if (s->high_water < curr) {
1517 /* Previous high water mark below current data -- zero WIN_INIT
1518 * bytes or up to end of window, whichever is less.
1520 init = s->window_size - curr;
1521 if (init > WIN_INIT)
1523 zmemzero(s->window + curr, (unsigned)init);
1524 s->high_water = curr + init;
1526 else if (s->high_water < (ulg)curr + WIN_INIT) {
1527 /* High water mark at or above current data, but below current data
1528 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1529 * to end of window, whichever is less.
1531 init = (ulg)curr + WIN_INIT - s->high_water;
1532 if (init > s->window_size - s->high_water)
1533 init = s->window_size - s->high_water;
1534 zmemzero(s->window + s->high_water, (unsigned)init);
1535 s->high_water += init;
1539 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1540 "not enough room for search");
1543 /* ===========================================================================
1544 * Flush the current block, with given end-of-file flag.
1545 * IN assertion: strstart is set to the end of the current match.
1547 #define FLUSH_BLOCK_ONLY(s, last) { \
1548 _tr_flush_block(s, (s->block_start >= 0L ? \
1549 (charf *)&s->window[(unsigned)s->block_start] : \
1551 (ulg)((long)s->strstart - s->block_start), \
1553 s->block_start = s->strstart; \
1554 flush_pending(s->strm); \
1555 Tracev((stderr,"[FLUSH]")); \
1558 /* Same but force premature exit if necessary. */
1559 #define FLUSH_BLOCK(s, last) { \
1560 FLUSH_BLOCK_ONLY(s, last); \
1561 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1564 /* ===========================================================================
1565 * Copy without compression as much as possible from the input stream, return
1566 * the current block state.
1567 * This function does not insert new strings in the dictionary since
1568 * uncompressible data is probably not useful. This function is used
1569 * only for the level=0 compression option.
1570 * NOTE: this function should be optimized to avoid extra copying from
1571 * window to pending_buf.
1573 local block_state deflate_stored(s, flush)
1577 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1578 * to pending_buf_size, and each stored block has a 5 byte header:
1580 ulg max_block_size = 0xffff;
1583 if (max_block_size > s->pending_buf_size - 5) {
1584 max_block_size = s->pending_buf_size - 5;
1587 /* Copy as much as possible from input to output: */
1589 /* Fill the window as much as possible: */
1590 if (s->lookahead <= 1) {
1592 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1593 s->block_start >= (long)s->w_size, "slide too late");
1596 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1598 if (s->lookahead == 0) break; /* flush the current block */
1600 Assert(s->block_start >= 0L, "block gone");
1602 s->strstart += s->lookahead;
1605 /* Emit a stored block if pending_buf will be full: */
1606 max_start = max_block_size + (ulg)s->block_start;
1607 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1608 /* strstart == 0 is possible when wraparound on 16-bit machine */
1609 s->lookahead = (uInt)(s->strstart - max_start);
1610 s->strstart = (uInt)max_start;
1613 /* Flush if we may have to slide, otherwise block_start may become
1614 * negative and the data will be gone:
1616 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1621 if (flush == Z_FINISH) {
1625 if ((long)s->strstart > s->block_start)
1630 /* ===========================================================================
1631 * Compress as much as possible from the input stream, return the current
1633 * This function does not perform lazy evaluation of matches and inserts
1634 * new strings in the dictionary only for unmatched strings or for short
1635 * matches. It is used only for the fast compression options.
1637 local block_state deflate_fast(s, flush)
1641 IPos hash_head; /* head of the hash chain */
1642 int bflush; /* set if current block must be flushed */
1645 /* Make sure that we always have enough lookahead, except
1646 * at the end of the input file. We need MAX_MATCH bytes
1647 * for the next match, plus MIN_MATCH bytes to insert the
1648 * string following the next match.
1650 if (s->lookahead < MIN_LOOKAHEAD) {
1652 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1655 if (s->lookahead == 0) break; /* flush the current block */
1658 /* Insert the string window[strstart .. strstart+2] in the
1659 * dictionary, and set hash_head to the head of the hash chain:
1662 if (s->lookahead >= MIN_MATCH) {
1663 INSERT_STRING(s, s->strstart, hash_head);
1666 /* Find the longest match, discarding those <= prev_length.
1667 * At this point we have always match_length < MIN_MATCH
1669 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1670 /* To simplify the code, we prevent matches with the string
1671 * of window index 0 (in particular we have to avoid a match
1672 * of the string with itself at the start of the input file).
1674 s->match_length = longest_match (s, hash_head);
1675 /* longest_match() sets match_start */
1677 if (s->match_length >= MIN_MATCH) {
1678 check_match(s, s->strstart, s->match_start, s->match_length);
1680 _tr_tally_dist(s, s->strstart - s->match_start,
1681 s->match_length - MIN_MATCH, bflush);
1683 s->lookahead -= s->match_length;
1685 /* Insert new strings in the hash table only if the match length
1686 * is not too large. This saves time but degrades compression.
1689 if (s->match_length <= s->max_insert_length &&
1690 s->lookahead >= MIN_MATCH) {
1691 s->match_length--; /* string at strstart already in table */
1694 INSERT_STRING(s, s->strstart, hash_head);
1695 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1696 * always MIN_MATCH bytes ahead.
1698 } while (--s->match_length != 0);
1703 s->strstart += s->match_length;
1704 s->match_length = 0;
1705 s->ins_h = s->window[s->strstart];
1706 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1708 Call UPDATE_HASH() MIN_MATCH-3 more times
1710 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1711 * matter since it will be recomputed at next deflate call.
1715 /* No match, output a literal byte */
1716 Tracevv((stderr,"%c", s->window[s->strstart]));
1717 _tr_tally_lit (s, s->window[s->strstart], bflush);
1721 if (bflush) FLUSH_BLOCK(s, 0);
1723 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1724 if (flush == Z_FINISH) {
1734 /* ===========================================================================
1735 * Same as above, but achieves better compression. We use a lazy
1736 * evaluation for matches: a match is finally adopted only if there is
1737 * no better match at the next window position.
1739 local block_state deflate_slow(s, flush)
1743 IPos hash_head; /* head of hash chain */
1744 int bflush; /* set if current block must be flushed */
1746 /* Process the input block. */
1748 /* Make sure that we always have enough lookahead, except
1749 * at the end of the input file. We need MAX_MATCH bytes
1750 * for the next match, plus MIN_MATCH bytes to insert the
1751 * string following the next match.
1753 if (s->lookahead < MIN_LOOKAHEAD) {
1755 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1758 if (s->lookahead == 0) break; /* flush the current block */
1761 /* Insert the string window[strstart .. strstart+2] in the
1762 * dictionary, and set hash_head to the head of the hash chain:
1765 if (s->lookahead >= MIN_MATCH) {
1766 INSERT_STRING(s, s->strstart, hash_head);
1769 /* Find the longest match, discarding those <= prev_length.
1771 s->prev_length = s->match_length, s->prev_match = s->match_start;
1772 s->match_length = MIN_MATCH-1;
1774 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1775 s->strstart - hash_head <= MAX_DIST(s)) {
1776 /* To simplify the code, we prevent matches with the string
1777 * of window index 0 (in particular we have to avoid a match
1778 * of the string with itself at the start of the input file).
1780 s->match_length = longest_match (s, hash_head);
1781 /* longest_match() sets match_start */
1783 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1784 #if TOO_FAR <= 32767
1785 || (s->match_length == MIN_MATCH &&
1786 s->strstart - s->match_start > TOO_FAR)
1790 /* If prev_match is also MIN_MATCH, match_start is garbage
1791 * but we will ignore the current match anyway.
1793 s->match_length = MIN_MATCH-1;
1796 /* If there was a match at the previous step and the current
1797 * match is not better, output the previous match:
1799 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1800 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1801 /* Do not insert strings in hash table beyond this. */
1803 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1805 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1806 s->prev_length - MIN_MATCH, bflush);
1808 /* Insert in hash table all strings up to the end of the match.
1809 * strstart-1 and strstart are already inserted. If there is not
1810 * enough lookahead, the last two strings are not inserted in
1813 s->lookahead -= s->prev_length-1;
1814 s->prev_length -= 2;
1816 if (++s->strstart <= max_insert) {
1817 INSERT_STRING(s, s->strstart, hash_head);
1819 } while (--s->prev_length != 0);
1820 s->match_available = 0;
1821 s->match_length = MIN_MATCH-1;
1824 if (bflush) FLUSH_BLOCK(s, 0);
1826 } else if (s->match_available) {
1827 /* If there was no match at the previous position, output a
1828 * single literal. If there was a match but the current match
1829 * is longer, truncate the previous match to a single literal.
1831 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1832 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1834 FLUSH_BLOCK_ONLY(s, 0);
1838 if (s->strm->avail_out == 0) return need_more;
1840 /* There is no previous match to compare with, wait for
1841 * the next step to decide.
1843 s->match_available = 1;
1848 Assert (flush != Z_NO_FLUSH, "no flush?");
1849 if (s->match_available) {
1850 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1851 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1852 s->match_available = 0;
1854 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1855 if (flush == Z_FINISH) {
1863 #endif /* FASTEST */
1865 /* ===========================================================================
1866 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1867 * one. Do not maintain a hash table. (It will be regenerated if this run of
1868 * deflate switches away from Z_RLE.)
1870 local block_state deflate_rle(s, flush)
1874 int bflush; /* set if current block must be flushed */
1875 uInt prev; /* byte at distance one to match */
1876 Bytef *scan, *strend; /* scan goes up to strend for length of run */
1879 /* Make sure that we always have enough lookahead, except
1880 * at the end of the input file. We need MAX_MATCH bytes
1881 * for the longest run, plus one for the unrolled loop.
1883 if (s->lookahead <= MAX_MATCH) {
1885 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
1888 if (s->lookahead == 0) break; /* flush the current block */
1891 /* See how many times the previous byte repeats */
1892 s->match_length = 0;
1893 if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
1894 scan = s->window + s->strstart - 1;
1896 if (prev == *++scan && prev == *++scan && prev == *++scan) {
1897 strend = s->window + s->strstart + MAX_MATCH;
1899 } while (prev == *++scan && prev == *++scan &&
1900 prev == *++scan && prev == *++scan &&
1901 prev == *++scan && prev == *++scan &&
1902 prev == *++scan && prev == *++scan &&
1904 s->match_length = MAX_MATCH - (uInt)(strend - scan);
1905 if (s->match_length > s->lookahead)
1906 s->match_length = s->lookahead;
1908 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
1911 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1912 if (s->match_length >= MIN_MATCH) {
1913 check_match(s, s->strstart, s->strstart - 1, s->match_length);
1915 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
1917 s->lookahead -= s->match_length;
1918 s->strstart += s->match_length;
1919 s->match_length = 0;
1921 /* No match, output a literal byte */
1922 Tracevv((stderr,"%c", s->window[s->strstart]));
1923 _tr_tally_lit (s, s->window[s->strstart], bflush);
1927 if (bflush) FLUSH_BLOCK(s, 0);
1930 if (flush == Z_FINISH) {
1939 /* ===========================================================================
1940 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
1941 * (It will be regenerated if this run of deflate switches away from Huffman.)
1943 local block_state deflate_huff(s, flush)
1947 int bflush; /* set if current block must be flushed */
1950 /* Make sure that we have a literal to write. */
1951 if (s->lookahead == 0) {
1953 if (s->lookahead == 0) {
1954 if (flush == Z_NO_FLUSH)
1956 break; /* flush the current block */
1960 /* Output a literal byte */
1961 s->match_length = 0;
1962 Tracevv((stderr,"%c", s->window[s->strstart]));
1963 _tr_tally_lit (s, s->window[s->strstart], bflush);
1966 if (bflush) FLUSH_BLOCK(s, 0);
1969 if (flush == Z_FINISH) {