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 void fill_window OF((deflate_state *s));
77 local block_state deflate_stored OF((deflate_state *s, int flush));
78 local block_state deflate_fast OF((deflate_state *s, int flush));
80 local block_state deflate_slow OF((deflate_state *s, int flush));
82 local block_state deflate_rle OF((deflate_state *s, int flush));
83 local block_state deflate_huff OF((deflate_state *s, int flush));
84 local void lm_init OF((deflate_state *s));
85 local void putShortMSB OF((deflate_state *s, uInt b));
86 local void flush_pending OF((z_streamp strm));
87 local unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
89 void match_init OF((void)); /* asm code initialization */
90 uInt longest_match OF((deflate_state *s, IPos cur_match));
92 local uInt longest_match OF((deflate_state *s, IPos cur_match));
96 local void check_match OF((deflate_state *s, IPos start, IPos match,
100 /* ===========================================================================
105 /* Tail of hash chains */
108 # define TOO_FAR 4096
110 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
112 /* Values for max_lazy_match, good_match and max_chain_length, depending on
113 * the desired pack level (0..9). The values given below have been tuned to
114 * exclude worst case performance for pathological files. Better values may be
115 * found for specific files.
117 typedef struct config_s {
118 ush good_length; /* reduce lazy search above this match length */
119 ush max_lazy; /* do not perform lazy search above this match length */
120 ush nice_length; /* quit search above this match length */
126 local const config configuration_table[2] = {
127 /* good lazy nice chain */
128 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
129 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
131 local const config configuration_table[10] = {
132 /* good lazy nice chain */
133 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
134 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
135 /* 2 */ {4, 5, 16, 8, deflate_fast},
136 /* 3 */ {4, 6, 32, 32, deflate_fast},
138 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
139 /* 5 */ {8, 16, 32, 32, deflate_slow},
140 /* 6 */ {8, 16, 128, 128, deflate_slow},
141 /* 7 */ {8, 32, 128, 256, deflate_slow},
142 /* 8 */ {32, 128, 258, 1024, deflate_slow},
143 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
146 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
147 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
151 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
152 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0))
154 /* ===========================================================================
155 * Update a hash value with the given input byte
156 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
157 * input characters, so that a running hash key can be computed from the
158 * previous key instead of complete recalculation each time.
160 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
163 /* ===========================================================================
164 * Insert string str in the dictionary and set match_head to the previous head
165 * of the hash chain (the most recent string with same hash key). Return
166 * the previous length of the hash chain.
167 * If this file is compiled with -DFASTEST, the compression level is forced
168 * to 1, and no hash chains are maintained.
169 * IN assertion: all calls to to INSERT_STRING are made with consecutive
170 * input characters and the first MIN_MATCH bytes of str are valid
171 * (except for the last MIN_MATCH-1 bytes of the input file).
174 #define INSERT_STRING(s, str, match_head) \
175 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
176 match_head = s->head[s->ins_h], \
177 s->head[s->ins_h] = (Pos)(str))
179 #define INSERT_STRING(s, str, match_head) \
180 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
181 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
182 s->head[s->ins_h] = (Pos)(str))
185 /* ===========================================================================
186 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
187 * prev[] will be initialized on the fly.
189 #define CLEAR_HASH(s) \
190 s->head[s->hash_size-1] = NIL; \
191 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
193 /* ========================================================================= */
194 int ZEXPORT deflateInit_(strm, level, version, stream_size)
200 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
201 Z_DEFAULT_STRATEGY, version, stream_size);
202 /* To do: ignore strm->next_in if we use it as window */
205 /* ========================================================================= */
206 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
207 version, stream_size)
219 static const char my_version[] = ZLIB_VERSION;
222 /* We overlay pending_buf and d_buf+l_buf. This works since the average
223 * output size for (length,distance) codes is <= 24 bits.
226 if (version == Z_NULL || version[0] != my_version[0] ||
227 stream_size != sizeof(z_stream)) {
228 return Z_VERSION_ERROR;
230 if (strm == Z_NULL) return Z_STREAM_ERROR;
233 if (strm->zalloc == (alloc_func)0) {
235 return Z_STREAM_ERROR;
237 strm->zalloc = zcalloc;
238 strm->opaque = (voidpf)0;
241 if (strm->zfree == (free_func)0)
243 return Z_STREAM_ERROR;
245 strm->zfree = zcfree;
249 if (level != 0) level = 1;
251 if (level == Z_DEFAULT_COMPRESSION) level = 6;
254 if (windowBits < 0) { /* suppress zlib wrapper */
256 windowBits = -windowBits;
259 else if (windowBits > 15) {
260 wrap = 2; /* write gzip wrapper instead */
264 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
265 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
266 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) {
267 return Z_STREAM_ERROR;
269 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
270 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
271 if (s == Z_NULL) return Z_MEM_ERROR;
272 strm->state = (struct internal_state FAR *)s;
277 s->w_bits = (uInt)windowBits;
278 s->w_size = 1 << s->w_bits;
279 s->w_mask = s->w_size - 1;
281 s->hash_bits = (uInt)memLevel + 7;
282 s->hash_size = 1 << s->hash_bits;
283 s->hash_mask = s->hash_size - 1;
284 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
286 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
287 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
288 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
290 s->high_water = 0; /* nothing written to s->window yet */
292 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
294 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
295 s->pending_buf = (uchf *) overlay;
296 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
298 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
299 s->pending_buf == Z_NULL) {
300 s->status = FINISH_STATE;
301 strm->msg = ERR_MSG(Z_MEM_ERROR);
305 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
306 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
309 s->strategy = strategy;
310 s->method = (Byte)method;
312 return deflateReset(strm);
315 /* ========================================================================= */
316 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
318 const Bytef *dictionary;
325 z_const unsigned char *next;
327 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL)
328 return Z_STREAM_ERROR;
331 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
332 return Z_STREAM_ERROR;
334 /* when using zlib wrappers, compute Adler-32 for provided dictionary */
336 strm->adler = adler32(strm->adler, dictionary, dictLength);
337 s->wrap = 0; /* avoid computing Adler-32 in read_buf */
339 /* if dictionary would fill window, just replace the history */
340 if (dictLength >= s->w_size) {
341 if (wrap == 0) { /* already empty otherwise */
347 dictionary += dictLength - s->w_size; /* use the tail */
348 dictLength = s->w_size;
351 /* insert dictionary into window and hash */
352 avail = strm->avail_in;
353 next = strm->next_in;
354 strm->avail_in = dictLength;
355 strm->next_in = (z_const Bytef *)dictionary;
357 while (s->lookahead >= MIN_MATCH) {
359 n = s->lookahead - (MIN_MATCH-1);
361 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
363 s->prev[str & s->w_mask] = s->head[s->ins_h];
365 s->head[s->ins_h] = (Pos)str;
369 s->lookahead = MIN_MATCH-1;
372 s->strstart += s->lookahead;
373 s->block_start = (long)s->strstart;
374 s->insert = s->lookahead;
376 s->match_length = s->prev_length = MIN_MATCH-1;
377 s->match_available = 0;
378 strm->next_in = next;
379 strm->avail_in = avail;
384 /* ========================================================================= */
385 int ZEXPORT deflateResetKeep (strm)
390 if (strm == Z_NULL || strm->state == Z_NULL ||
391 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
392 return Z_STREAM_ERROR;
395 strm->total_in = strm->total_out = 0;
396 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
397 strm->data_type = Z_UNKNOWN;
399 s = (deflate_state *)strm->state;
401 s->pending_out = s->pending_buf;
404 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
406 s->status = s->wrap ? INIT_STATE : BUSY_STATE;
409 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
411 adler32(0L, Z_NULL, 0);
412 s->last_flush = Z_NO_FLUSH;
419 /* ========================================================================= */
420 int ZEXPORT deflateReset (strm)
425 ret = deflateResetKeep(strm);
427 lm_init(strm->state);
431 /* ========================================================================= */
432 int ZEXPORT deflateSetHeader (strm, head)
436 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
437 if (strm->state->wrap != 2) return Z_STREAM_ERROR;
438 strm->state->gzhead = head;
442 /* ========================================================================= */
443 int ZEXPORT deflatePending (strm, pending, bits)
448 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
449 if (pending != Z_NULL)
450 *pending = strm->state->pending;
452 *bits = strm->state->bi_valid;
456 /* ========================================================================= */
457 int ZEXPORT deflatePrime (strm, bits, value)
465 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
467 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
470 put = Buf_size - s->bi_valid;
473 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
482 /* ========================================================================= */
483 int ZEXPORT deflateParams(strm, level, strategy)
492 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
496 if (level != 0) level = 1;
498 if (level == Z_DEFAULT_COMPRESSION) level = 6;
500 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
501 return Z_STREAM_ERROR;
503 func = configuration_table[s->level].func;
505 if ((strategy != s->strategy || func != configuration_table[level].func)) {
506 /* Flush the last buffer: */
507 err = deflate(strm, Z_BLOCK);
508 if (err == Z_BUF_ERROR && s->pending == 0)
511 if (s->level != level) {
513 s->max_lazy_match = configuration_table[level].max_lazy;
514 s->good_match = configuration_table[level].good_length;
515 s->nice_match = configuration_table[level].nice_length;
516 s->max_chain_length = configuration_table[level].max_chain;
518 s->strategy = strategy;
522 /* ========================================================================= */
523 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
532 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
534 s->good_match = (uInt)good_length;
535 s->max_lazy_match = (uInt)max_lazy;
536 s->nice_match = nice_length;
537 s->max_chain_length = (uInt)max_chain;
541 /* =========================================================================
542 * For the default windowBits of 15 and memLevel of 8, this function returns
543 * a close to exact, as well as small, upper bound on the compressed size.
544 * They are coded as constants here for a reason--if the #define's are
545 * changed, then this function needs to be changed as well. The return
546 * value for 15 and 8 only works for those exact settings.
548 * For any setting other than those defaults for windowBits and memLevel,
549 * the value returned is a conservative worst case for the maximum expansion
550 * resulting from using fixed blocks instead of stored blocks, which deflate
551 * can emit on compressed data for some combinations of the parameters.
553 * This function could be more sophisticated to provide closer upper bounds for
554 * every combination of windowBits and memLevel. But even the conservative
555 * upper bound of about 14% expansion does not seem onerous for output buffer
558 uLong ZEXPORT deflateBound(strm, sourceLen)
563 uLong complen, wraplen;
566 /* conservative upper bound for compressed data */
567 complen = sourceLen +
568 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
570 /* if can't get parameters, return conservative bound plus zlib wrapper */
571 if (strm == Z_NULL || strm->state == Z_NULL)
574 /* compute wrapper length */
577 case 0: /* raw deflate */
580 case 1: /* zlib wrapper */
581 wraplen = 6 + (s->strstart ? 4 : 0);
583 case 2: /* gzip wrapper */
585 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
586 if (s->gzhead->extra != Z_NULL)
587 wraplen += 2 + s->gzhead->extra_len;
588 str = s->gzhead->name;
593 str = s->gzhead->comment;
602 default: /* for compiler happiness */
606 /* if not default parameters, return conservative bound */
607 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
608 return complen + wraplen;
610 /* default settings: return tight bound for that case */
611 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
612 (sourceLen >> 25) + 13 - 6 + wraplen;
615 /* =========================================================================
616 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
617 * IN assertion: the stream state is correct and there is enough room in
620 local void putShortMSB (s, b)
624 put_byte(s, (Byte)(b >> 8));
625 put_byte(s, (Byte)(b & 0xff));
628 /* =========================================================================
629 * Flush as much pending output as possible. All deflate() output goes
630 * through this function so some applications may wish to modify it
631 * to avoid allocating a large strm->next_out buffer and copying into it.
632 * (See also read_buf()).
634 local void flush_pending(strm)
638 deflate_state *s = strm->state;
642 if (len > strm->avail_out) len = strm->avail_out;
643 if (len == 0) return;
645 zmemcpy(strm->next_out, s->pending_out, len);
646 strm->next_out += len;
647 s->pending_out += len;
648 strm->total_out += len;
649 strm->avail_out -= len;
651 if (s->pending == 0) {
652 s->pending_out = s->pending_buf;
656 /* ========================================================================= */
657 int ZEXPORT deflate (strm, flush)
661 int old_flush; /* value of flush param for previous deflate call */
664 if (strm == Z_NULL || strm->state == Z_NULL ||
665 flush > Z_BLOCK || flush < 0) {
666 return Z_STREAM_ERROR;
670 if (strm->next_out == Z_NULL ||
671 (strm->avail_in != 0 && strm->next_in == Z_NULL) ||
672 (s->status == FINISH_STATE && flush != Z_FINISH)) {
673 ERR_RETURN(strm, Z_STREAM_ERROR);
675 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
677 s->strm = strm; /* just in case */
678 old_flush = s->last_flush;
679 s->last_flush = flush;
681 /* Write the header */
682 if (s->status == INIT_STATE) {
685 strm->adler = crc32(0L, Z_NULL, 0);
689 if (s->gzhead == Z_NULL) {
695 put_byte(s, s->level == 9 ? 2 :
696 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
698 put_byte(s, OS_CODE);
699 s->status = BUSY_STATE;
702 put_byte(s, (s->gzhead->text ? 1 : 0) +
703 (s->gzhead->hcrc ? 2 : 0) +
704 (s->gzhead->extra == Z_NULL ? 0 : 4) +
705 (s->gzhead->name == Z_NULL ? 0 : 8) +
706 (s->gzhead->comment == Z_NULL ? 0 : 16)
708 put_byte(s, (Byte)(s->gzhead->time & 0xff));
709 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
710 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
711 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
712 put_byte(s, s->level == 9 ? 2 :
713 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
715 put_byte(s, s->gzhead->os & 0xff);
716 if (s->gzhead->extra != Z_NULL) {
717 put_byte(s, s->gzhead->extra_len & 0xff);
718 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
721 strm->adler = crc32(strm->adler, s->pending_buf,
724 s->status = EXTRA_STATE;
730 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
733 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
735 else if (s->level < 6)
737 else if (s->level == 6)
741 header |= (level_flags << 6);
742 if (s->strstart != 0) header |= PRESET_DICT;
743 header += 31 - (header % 31);
745 s->status = BUSY_STATE;
746 putShortMSB(s, header);
748 /* Save the adler32 of the preset dictionary: */
749 if (s->strstart != 0) {
750 putShortMSB(s, (uInt)(strm->adler >> 16));
751 putShortMSB(s, (uInt)(strm->adler & 0xffff));
753 strm->adler = adler32(0L, Z_NULL, 0);
757 if (s->status == EXTRA_STATE) {
758 if (s->gzhead->extra != Z_NULL) {
759 uInt beg = s->pending; /* start of bytes to update crc */
761 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
762 if (s->pending == s->pending_buf_size) {
763 if (s->gzhead->hcrc && s->pending > beg)
764 strm->adler = crc32(strm->adler, s->pending_buf + beg,
768 if (s->pending == s->pending_buf_size)
771 put_byte(s, s->gzhead->extra[s->gzindex]);
774 if (s->gzhead->hcrc && s->pending > beg)
775 strm->adler = crc32(strm->adler, s->pending_buf + beg,
777 if (s->gzindex == s->gzhead->extra_len) {
779 s->status = NAME_STATE;
783 s->status = NAME_STATE;
785 if (s->status == NAME_STATE) {
786 if (s->gzhead->name != Z_NULL) {
787 uInt beg = s->pending; /* start of bytes to update crc */
791 if (s->pending == s->pending_buf_size) {
792 if (s->gzhead->hcrc && s->pending > beg)
793 strm->adler = crc32(strm->adler, s->pending_buf + beg,
797 if (s->pending == s->pending_buf_size) {
802 val = s->gzhead->name[s->gzindex++];
805 if (s->gzhead->hcrc && s->pending > beg)
806 strm->adler = crc32(strm->adler, s->pending_buf + beg,
810 s->status = COMMENT_STATE;
814 s->status = COMMENT_STATE;
816 if (s->status == COMMENT_STATE) {
817 if (s->gzhead->comment != Z_NULL) {
818 uInt beg = s->pending; /* start of bytes to update crc */
822 if (s->pending == s->pending_buf_size) {
823 if (s->gzhead->hcrc && s->pending > beg)
824 strm->adler = crc32(strm->adler, s->pending_buf + beg,
828 if (s->pending == s->pending_buf_size) {
833 val = s->gzhead->comment[s->gzindex++];
836 if (s->gzhead->hcrc && s->pending > beg)
837 strm->adler = crc32(strm->adler, s->pending_buf + beg,
840 s->status = HCRC_STATE;
843 s->status = HCRC_STATE;
845 if (s->status == HCRC_STATE) {
846 if (s->gzhead->hcrc) {
847 if (s->pending + 2 > s->pending_buf_size)
849 if (s->pending + 2 <= s->pending_buf_size) {
850 put_byte(s, (Byte)(strm->adler & 0xff));
851 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
852 strm->adler = crc32(0L, Z_NULL, 0);
853 s->status = BUSY_STATE;
857 s->status = BUSY_STATE;
861 /* Flush as much pending output as possible */
862 if (s->pending != 0) {
864 if (strm->avail_out == 0) {
865 /* Since avail_out is 0, deflate will be called again with
866 * more output space, but possibly with both pending and
867 * avail_in equal to zero. There won't be anything to do,
868 * but this is not an error situation so make sure we
869 * return OK instead of BUF_ERROR at next call of deflate:
875 /* Make sure there is something to do and avoid duplicate consecutive
876 * flushes. For repeated and useless calls with Z_FINISH, we keep
877 * returning Z_STREAM_END instead of Z_BUF_ERROR.
879 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
881 ERR_RETURN(strm, Z_BUF_ERROR);
884 /* User must not provide more input after the first FINISH: */
885 if (s->status == FINISH_STATE && strm->avail_in != 0) {
886 ERR_RETURN(strm, Z_BUF_ERROR);
889 /* Start a new block or continue the current one.
891 if (strm->avail_in != 0 || s->lookahead != 0 ||
892 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
895 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
896 (s->strategy == Z_RLE ? deflate_rle(s, flush) :
897 (*(configuration_table[s->level].func))(s, flush));
899 if (bstate == finish_started || bstate == finish_done) {
900 s->status = FINISH_STATE;
902 if (bstate == need_more || bstate == finish_started) {
903 if (strm->avail_out == 0) {
904 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
907 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
908 * of deflate should use the same flush parameter to make sure
909 * that the flush is complete. So we don't have to output an
910 * empty block here, this will be done at next call. This also
911 * ensures that for a very small output buffer, we emit at most
915 if (bstate == block_done) {
916 if (flush == Z_PARTIAL_FLUSH) {
918 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
919 _tr_stored_block(s, (char*)0, 0L, 0);
920 /* For a full flush, this empty block will be recognized
921 * as a special marker by inflate_sync().
923 if (flush == Z_FULL_FLUSH) {
924 CLEAR_HASH(s); /* forget history */
925 if (s->lookahead == 0) {
933 if (strm->avail_out == 0) {
934 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
939 Assert(strm->avail_out > 0, "bug2");
941 if (flush != Z_FINISH) return Z_OK;
942 if (s->wrap <= 0) return Z_STREAM_END;
944 /* Write the trailer */
947 put_byte(s, (Byte)(strm->adler & 0xff));
948 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
949 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
950 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
951 put_byte(s, (Byte)(strm->total_in & 0xff));
952 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
953 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
954 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
959 putShortMSB(s, (uInt)(strm->adler >> 16));
960 putShortMSB(s, (uInt)(strm->adler & 0xffff));
963 /* If avail_out is zero, the application will call deflate again
966 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
967 return s->pending != 0 ? Z_OK : Z_STREAM_END;
970 /* ========================================================================= */
971 int ZEXPORT deflateEnd (strm)
976 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
978 status = strm->state->status;
979 if (status != INIT_STATE &&
980 status != EXTRA_STATE &&
981 status != NAME_STATE &&
982 status != COMMENT_STATE &&
983 status != HCRC_STATE &&
984 status != BUSY_STATE &&
985 status != FINISH_STATE) {
986 return Z_STREAM_ERROR;
989 /* Deallocate in reverse order of allocations: */
990 TRY_FREE(strm, strm->state->pending_buf);
991 TRY_FREE(strm, strm->state->head);
992 TRY_FREE(strm, strm->state->prev);
993 TRY_FREE(strm, strm->state->window);
995 ZFREE(strm, strm->state);
996 strm->state = Z_NULL;
998 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1001 /* =========================================================================
1002 * Copy the source state to the destination state.
1003 * To simplify the source, this is not supported for 16-bit MSDOS (which
1004 * doesn't have enough memory anyway to duplicate compression states).
1006 int ZEXPORT deflateCopy (dest, source)
1011 return Z_STREAM_ERROR;
1018 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
1019 return Z_STREAM_ERROR;
1024 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1026 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1027 if (ds == Z_NULL) return Z_MEM_ERROR;
1028 dest->state = (struct internal_state FAR *) ds;
1029 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1032 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1033 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1034 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1035 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1036 ds->pending_buf = (uchf *) overlay;
1038 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1039 ds->pending_buf == Z_NULL) {
1043 /* following zmemcpy do not work for 16-bit MSDOS */
1044 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1045 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1046 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1047 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1049 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1050 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1051 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1053 ds->l_desc.dyn_tree = ds->dyn_ltree;
1054 ds->d_desc.dyn_tree = ds->dyn_dtree;
1055 ds->bl_desc.dyn_tree = ds->bl_tree;
1058 #endif /* MAXSEG_64K */
1061 /* ===========================================================================
1062 * Read a new buffer from the current input stream, update the adler32
1063 * and total number of bytes read. All deflate() input goes through
1064 * this function so some applications may wish to modify it to avoid
1065 * allocating a large strm->next_in buffer and copying from it.
1066 * (See also flush_pending()).
1068 local unsigned read_buf(strm, buf, size)
1073 unsigned len = strm->avail_in;
1075 if (len > size) len = size;
1076 if (len == 0) return 0;
1078 strm->avail_in -= len;
1080 zmemcpy(buf, strm->next_in, len);
1081 if (strm->state->wrap == 1) {
1082 strm->adler = adler32(strm->adler, buf, len);
1085 else if (strm->state->wrap == 2) {
1086 strm->adler = crc32(strm->adler, buf, len);
1089 strm->next_in += len;
1090 strm->total_in += len;
1095 /* ===========================================================================
1096 * Initialize the "longest match" routines for a new zlib stream
1098 local void lm_init (s)
1101 s->window_size = (ulg)2L*s->w_size;
1105 /* Set the default configuration parameters:
1107 s->max_lazy_match = configuration_table[s->level].max_lazy;
1108 s->good_match = configuration_table[s->level].good_length;
1109 s->nice_match = configuration_table[s->level].nice_length;
1110 s->max_chain_length = configuration_table[s->level].max_chain;
1113 s->block_start = 0L;
1116 s->match_length = s->prev_length = MIN_MATCH-1;
1117 s->match_available = 0;
1121 match_init(); /* initialize the asm code */
1127 /* ===========================================================================
1128 * Set match_start to the longest match starting at the given string and
1129 * return its length. Matches shorter or equal to prev_length are discarded,
1130 * in which case the result is equal to prev_length and match_start is
1132 * IN assertions: cur_match is the head of the hash chain for the current
1133 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1134 * OUT assertion: the match length is not greater than s->lookahead.
1137 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1138 * match.S. The code will be functionally equivalent.
1140 local uInt longest_match(s, cur_match)
1142 IPos cur_match; /* current match */
1144 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1145 register Bytef *scan = s->window + s->strstart; /* current string */
1146 register Bytef *match; /* matched string */
1147 register int len; /* length of current match */
1148 int best_len = (int)s->prev_length; /* best match length so far */
1149 int nice_match = s->nice_match; /* stop if match long enough */
1150 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1151 s->strstart - (IPos)MAX_DIST(s) : NIL;
1152 /* Stop when cur_match becomes <= limit. To simplify the code,
1153 * we prevent matches with the string of window index 0.
1155 Posf *prev = s->prev;
1156 uInt wmask = s->w_mask;
1159 /* Compare two bytes at a time. Note: this is not always beneficial.
1160 * Try with and without -DUNALIGNED_OK to check.
1162 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1163 register ush scan_start = *(ushf*)scan;
1164 register ush scan_end = *(ushf*)(scan+best_len-1);
1166 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1167 register Byte scan_end1 = scan[best_len-1];
1168 register Byte scan_end = scan[best_len];
1171 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1172 * It is easy to get rid of this optimization if necessary.
1174 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1176 /* Do not waste too much time if we already have a good match: */
1177 if (s->prev_length >= s->good_match) {
1180 /* Do not look for matches beyond the end of the input. This is necessary
1181 * to make deflate deterministic.
1183 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead;
1185 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1188 Assert(cur_match < s->strstart, "no future");
1189 match = s->window + cur_match;
1191 /* Skip to next match if the match length cannot increase
1192 * or if the match length is less than 2. Note that the checks below
1193 * for insufficient lookahead only occur occasionally for performance
1194 * reasons. Therefore uninitialized memory will be accessed, and
1195 * conditional jumps will be made that depend on those values.
1196 * However the length of the match is limited to the lookahead, so
1197 * the output of deflate is not affected by the uninitialized values.
1199 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1200 /* This code assumes sizeof(unsigned short) == 2. Do not use
1201 * UNALIGNED_OK if your compiler uses a different size.
1203 if (*(ushf*)(match+best_len-1) != scan_end ||
1204 *(ushf*)match != scan_start) continue;
1206 /* It is not necessary to compare scan[2] and match[2] since they are
1207 * always equal when the other bytes match, given that the hash keys
1208 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1209 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1210 * lookahead only every 4th comparison; the 128th check will be made
1211 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1212 * necessary to put more guard bytes at the end of the window, or
1213 * to check more often for insufficient lookahead.
1215 Assert(scan[2] == match[2], "scan[2]?");
1218 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1219 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1220 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1221 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1223 /* The funny "do {}" generates better code on most compilers */
1225 /* Here, scan <= window+strstart+257 */
1226 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1227 if (*scan == *match) scan++;
1229 len = (MAX_MATCH - 1) - (int)(strend-scan);
1230 scan = strend - (MAX_MATCH-1);
1232 #else /* UNALIGNED_OK */
1234 if (match[best_len] != scan_end ||
1235 match[best_len-1] != scan_end1 ||
1237 *++match != scan[1]) continue;
1239 /* The check at best_len-1 can be removed because it will be made
1240 * again later. (This heuristic is not always a win.)
1241 * It is not necessary to compare scan[2] and match[2] since they
1242 * are always equal when the other bytes match, given that
1243 * the hash keys are equal and that HASH_BITS >= 8.
1246 Assert(*scan == *match, "match[2]?");
1248 /* We check for insufficient lookahead only every 8th comparison;
1249 * the 256th check will be made at strstart+258.
1252 } while (*++scan == *++match && *++scan == *++match &&
1253 *++scan == *++match && *++scan == *++match &&
1254 *++scan == *++match && *++scan == *++match &&
1255 *++scan == *++match && *++scan == *++match &&
1258 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1260 len = MAX_MATCH - (int)(strend - scan);
1261 scan = strend - MAX_MATCH;
1263 #endif /* UNALIGNED_OK */
1265 if (len > best_len) {
1266 s->match_start = cur_match;
1268 if (len >= nice_match) break;
1270 scan_end = *(ushf*)(scan+best_len-1);
1272 scan_end1 = scan[best_len-1];
1273 scan_end = scan[best_len];
1276 } while ((cur_match = prev[cur_match & wmask]) > limit
1277 && --chain_length != 0);
1279 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1280 return s->lookahead;
1286 /* ---------------------------------------------------------------------------
1287 * Optimized version for FASTEST only
1289 local uInt longest_match(s, cur_match)
1291 IPos cur_match; /* current match */
1293 register Bytef *scan = s->window + s->strstart; /* current string */
1294 register Bytef *match; /* matched string */
1295 register int len; /* length of current match */
1296 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1298 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1299 * It is easy to get rid of this optimization if necessary.
1301 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1303 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1305 Assert(cur_match < s->strstart, "no future");
1307 match = s->window + cur_match;
1309 /* Return failure if the match length is less than 2:
1311 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1313 /* The check at best_len-1 can be removed because it will be made
1314 * again later. (This heuristic is not always a win.)
1315 * It is not necessary to compare scan[2] and match[2] since they
1316 * are always equal when the other bytes match, given that
1317 * the hash keys are equal and that HASH_BITS >= 8.
1319 scan += 2, match += 2;
1320 Assert(*scan == *match, "match[2]?");
1322 /* We check for insufficient lookahead only every 8th comparison;
1323 * the 256th check will be made at strstart+258.
1326 } while (*++scan == *++match && *++scan == *++match &&
1327 *++scan == *++match && *++scan == *++match &&
1328 *++scan == *++match && *++scan == *++match &&
1329 *++scan == *++match && *++scan == *++match &&
1332 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1334 len = MAX_MATCH - (int)(strend - scan);
1336 if (len < MIN_MATCH) return MIN_MATCH - 1;
1338 s->match_start = cur_match;
1339 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1342 #endif /* FASTEST */
1347 /* result of memcmp for equal strings */
1349 /* ===========================================================================
1350 * Check that the match at match_start is indeed a match.
1352 local void check_match(s, start, match, length)
1357 /* check that the match is indeed a match */
1358 if (zmemcmp(s->window + match,
1359 s->window + start, length) != EQUAL) {
1360 fprintf(stderr, " start %u, match %u, length %d\n",
1361 start, match, length);
1363 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1364 } while (--length != 0);
1365 z_error("invalid match");
1367 if (z_verbose > 1) {
1368 fprintf(stderr,"\\[%d,%d]", start-match, length);
1369 do { putc(s->window[start++], stderr); } while (--length != 0);
1373 # define check_match(s, start, match, length)
1374 #endif /* ZLIB_DEBUG */
1376 /* ===========================================================================
1377 * Fill the window when the lookahead becomes insufficient.
1378 * Updates strstart and lookahead.
1380 * IN assertion: lookahead < MIN_LOOKAHEAD
1381 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1382 * At least one byte has been read, or avail_in == 0; reads are
1383 * performed for at least two bytes (required for the zip translate_eol
1384 * option -- not supported here).
1386 local void fill_window(s)
1389 register unsigned n, m;
1391 unsigned more; /* Amount of free space at the end of the window. */
1392 uInt wsize = s->w_size;
1394 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1397 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1399 /* Deal with !@#$% 64K limit: */
1400 if (sizeof(int) <= 2) {
1401 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1404 } else if (more == (unsigned)(-1)) {
1405 /* Very unlikely, but possible on 16 bit machine if
1406 * strstart == 0 && lookahead == 1 (input done a byte at time)
1412 /* If the window is almost full and there is insufficient lookahead,
1413 * move the upper half to the lower one to make room in the upper half.
1415 if (s->strstart >= wsize+MAX_DIST(s)) {
1417 zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1418 s->match_start -= wsize;
1419 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1420 s->block_start -= (long) wsize;
1422 /* Slide the hash table (could be avoided with 32 bit values
1423 at the expense of memory usage). We slide even when level == 0
1424 to keep the hash table consistent if we switch back to level > 0
1425 later. (Using level 0 permanently is not an optimal usage of
1426 zlib, so we don't care about this pathological case.)
1432 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1440 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1441 /* If n is not on any hash chain, prev[n] is garbage but
1442 * its value will never be used.
1448 if (s->strm->avail_in == 0) break;
1450 /* If there was no sliding:
1451 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1452 * more == window_size - lookahead - strstart
1453 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1454 * => more >= window_size - 2*WSIZE + 2
1455 * In the BIG_MEM or MMAP case (not yet supported),
1456 * window_size == input_size + MIN_LOOKAHEAD &&
1457 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1458 * Otherwise, window_size == 2*WSIZE so more >= 2.
1459 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1461 Assert(more >= 2, "more < 2");
1463 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1466 /* Initialize the hash value now that we have some input: */
1467 if (s->lookahead + s->insert >= MIN_MATCH) {
1468 uInt str = s->strstart - s->insert;
1469 s->ins_h = s->window[str];
1470 UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1472 Call UPDATE_HASH() MIN_MATCH-3 more times
1475 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1477 s->prev[str & s->w_mask] = s->head[s->ins_h];
1479 s->head[s->ins_h] = (Pos)str;
1482 if (s->lookahead + s->insert < MIN_MATCH)
1486 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1487 * but this is not important since only literal bytes will be emitted.
1490 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1492 /* If the WIN_INIT bytes after the end of the current data have never been
1493 * written, then zero those bytes in order to avoid memory check reports of
1494 * the use of uninitialized (or uninitialised as Julian writes) bytes by
1495 * the longest match routines. Update the high water mark for the next
1496 * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1497 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1499 if (s->high_water < s->window_size) {
1500 ulg curr = s->strstart + (ulg)(s->lookahead);
1503 if (s->high_water < curr) {
1504 /* Previous high water mark below current data -- zero WIN_INIT
1505 * bytes or up to end of window, whichever is less.
1507 init = s->window_size - curr;
1508 if (init > WIN_INIT)
1510 zmemzero(s->window + curr, (unsigned)init);
1511 s->high_water = curr + init;
1513 else if (s->high_water < (ulg)curr + WIN_INIT) {
1514 /* High water mark at or above current data, but below current data
1515 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1516 * to end of window, whichever is less.
1518 init = (ulg)curr + WIN_INIT - s->high_water;
1519 if (init > s->window_size - s->high_water)
1520 init = s->window_size - s->high_water;
1521 zmemzero(s->window + s->high_water, (unsigned)init);
1522 s->high_water += init;
1526 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1527 "not enough room for search");
1530 /* ===========================================================================
1531 * Flush the current block, with given end-of-file flag.
1532 * IN assertion: strstart is set to the end of the current match.
1534 #define FLUSH_BLOCK_ONLY(s, last) { \
1535 _tr_flush_block(s, (s->block_start >= 0L ? \
1536 (charf *)&s->window[(unsigned)s->block_start] : \
1538 (ulg)((long)s->strstart - s->block_start), \
1540 s->block_start = s->strstart; \
1541 flush_pending(s->strm); \
1542 Tracev((stderr,"[FLUSH]")); \
1545 /* Same but force premature exit if necessary. */
1546 #define FLUSH_BLOCK(s, last) { \
1547 FLUSH_BLOCK_ONLY(s, last); \
1548 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1551 /* ===========================================================================
1552 * Copy without compression as much as possible from the input stream, return
1553 * the current block state.
1554 * This function does not insert new strings in the dictionary since
1555 * uncompressible data is probably not useful. This function is used
1556 * only for the level=0 compression option.
1557 * NOTE: this function should be optimized to avoid extra copying from
1558 * window to pending_buf.
1560 local block_state deflate_stored(s, flush)
1564 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1565 * to pending_buf_size, and each stored block has a 5 byte header:
1567 ulg max_block_size = 0xffff;
1570 if (max_block_size > s->pending_buf_size - 5) {
1571 max_block_size = s->pending_buf_size - 5;
1574 /* Copy as much as possible from input to output: */
1576 /* Fill the window as much as possible: */
1577 if (s->lookahead <= 1) {
1579 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1580 s->block_start >= (long)s->w_size, "slide too late");
1583 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1585 if (s->lookahead == 0) break; /* flush the current block */
1587 Assert(s->block_start >= 0L, "block gone");
1589 s->strstart += s->lookahead;
1592 /* Emit a stored block if pending_buf will be full: */
1593 max_start = max_block_size + (ulg)s->block_start;
1594 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1595 /* strstart == 0 is possible when wraparound on 16-bit machine */
1596 s->lookahead = (uInt)(s->strstart - max_start);
1597 s->strstart = (uInt)max_start;
1600 /* Flush if we may have to slide, otherwise block_start may become
1601 * negative and the data will be gone:
1603 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1608 if (flush == Z_FINISH) {
1612 if ((long)s->strstart > s->block_start)
1617 /* ===========================================================================
1618 * Compress as much as possible from the input stream, return the current
1620 * This function does not perform lazy evaluation of matches and inserts
1621 * new strings in the dictionary only for unmatched strings or for short
1622 * matches. It is used only for the fast compression options.
1624 local block_state deflate_fast(s, flush)
1628 IPos hash_head; /* head of the hash chain */
1629 int bflush; /* set if current block must be flushed */
1632 /* Make sure that we always have enough lookahead, except
1633 * at the end of the input file. We need MAX_MATCH bytes
1634 * for the next match, plus MIN_MATCH bytes to insert the
1635 * string following the next match.
1637 if (s->lookahead < MIN_LOOKAHEAD) {
1639 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1642 if (s->lookahead == 0) break; /* flush the current block */
1645 /* Insert the string window[strstart .. strstart+2] in the
1646 * dictionary, and set hash_head to the head of the hash chain:
1649 if (s->lookahead >= MIN_MATCH) {
1650 INSERT_STRING(s, s->strstart, hash_head);
1653 /* Find the longest match, discarding those <= prev_length.
1654 * At this point we have always match_length < MIN_MATCH
1656 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1657 /* To simplify the code, we prevent matches with the string
1658 * of window index 0 (in particular we have to avoid a match
1659 * of the string with itself at the start of the input file).
1661 s->match_length = longest_match (s, hash_head);
1662 /* longest_match() sets match_start */
1664 if (s->match_length >= MIN_MATCH) {
1665 check_match(s, s->strstart, s->match_start, s->match_length);
1667 _tr_tally_dist(s, s->strstart - s->match_start,
1668 s->match_length - MIN_MATCH, bflush);
1670 s->lookahead -= s->match_length;
1672 /* Insert new strings in the hash table only if the match length
1673 * is not too large. This saves time but degrades compression.
1676 if (s->match_length <= s->max_insert_length &&
1677 s->lookahead >= MIN_MATCH) {
1678 s->match_length--; /* string at strstart already in table */
1681 INSERT_STRING(s, s->strstart, hash_head);
1682 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1683 * always MIN_MATCH bytes ahead.
1685 } while (--s->match_length != 0);
1690 s->strstart += s->match_length;
1691 s->match_length = 0;
1692 s->ins_h = s->window[s->strstart];
1693 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1695 Call UPDATE_HASH() MIN_MATCH-3 more times
1697 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1698 * matter since it will be recomputed at next deflate call.
1702 /* No match, output a literal byte */
1703 Tracevv((stderr,"%c", s->window[s->strstart]));
1704 _tr_tally_lit (s, s->window[s->strstart], bflush);
1708 if (bflush) FLUSH_BLOCK(s, 0);
1710 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1711 if (flush == Z_FINISH) {
1721 /* ===========================================================================
1722 * Same as above, but achieves better compression. We use a lazy
1723 * evaluation for matches: a match is finally adopted only if there is
1724 * no better match at the next window position.
1726 local block_state deflate_slow(s, flush)
1730 IPos hash_head; /* head of hash chain */
1731 int bflush; /* set if current block must be flushed */
1733 /* Process the input block. */
1735 /* Make sure that we always have enough lookahead, except
1736 * at the end of the input file. We need MAX_MATCH bytes
1737 * for the next match, plus MIN_MATCH bytes to insert the
1738 * string following the next match.
1740 if (s->lookahead < MIN_LOOKAHEAD) {
1742 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1745 if (s->lookahead == 0) break; /* flush the current block */
1748 /* Insert the string window[strstart .. strstart+2] in the
1749 * dictionary, and set hash_head to the head of the hash chain:
1752 if (s->lookahead >= MIN_MATCH) {
1753 INSERT_STRING(s, s->strstart, hash_head);
1756 /* Find the longest match, discarding those <= prev_length.
1758 s->prev_length = s->match_length, s->prev_match = s->match_start;
1759 s->match_length = MIN_MATCH-1;
1761 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1762 s->strstart - hash_head <= MAX_DIST(s)) {
1763 /* To simplify the code, we prevent matches with the string
1764 * of window index 0 (in particular we have to avoid a match
1765 * of the string with itself at the start of the input file).
1767 s->match_length = longest_match (s, hash_head);
1768 /* longest_match() sets match_start */
1770 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1771 #if TOO_FAR <= 32767
1772 || (s->match_length == MIN_MATCH &&
1773 s->strstart - s->match_start > TOO_FAR)
1777 /* If prev_match is also MIN_MATCH, match_start is garbage
1778 * but we will ignore the current match anyway.
1780 s->match_length = MIN_MATCH-1;
1783 /* If there was a match at the previous step and the current
1784 * match is not better, output the previous match:
1786 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1787 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1788 /* Do not insert strings in hash table beyond this. */
1790 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1792 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1793 s->prev_length - MIN_MATCH, bflush);
1795 /* Insert in hash table all strings up to the end of the match.
1796 * strstart-1 and strstart are already inserted. If there is not
1797 * enough lookahead, the last two strings are not inserted in
1800 s->lookahead -= s->prev_length-1;
1801 s->prev_length -= 2;
1803 if (++s->strstart <= max_insert) {
1804 INSERT_STRING(s, s->strstart, hash_head);
1806 } while (--s->prev_length != 0);
1807 s->match_available = 0;
1808 s->match_length = MIN_MATCH-1;
1811 if (bflush) FLUSH_BLOCK(s, 0);
1813 } else if (s->match_available) {
1814 /* If there was no match at the previous position, output a
1815 * single literal. If there was a match but the current match
1816 * is longer, truncate the previous match to a single literal.
1818 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1819 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1821 FLUSH_BLOCK_ONLY(s, 0);
1825 if (s->strm->avail_out == 0) return need_more;
1827 /* There is no previous match to compare with, wait for
1828 * the next step to decide.
1830 s->match_available = 1;
1835 Assert (flush != Z_NO_FLUSH, "no flush?");
1836 if (s->match_available) {
1837 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1838 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1839 s->match_available = 0;
1841 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1842 if (flush == Z_FINISH) {
1850 #endif /* FASTEST */
1852 /* ===========================================================================
1853 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1854 * one. Do not maintain a hash table. (It will be regenerated if this run of
1855 * deflate switches away from Z_RLE.)
1857 local block_state deflate_rle(s, flush)
1861 int bflush; /* set if current block must be flushed */
1862 uInt prev; /* byte at distance one to match */
1863 Bytef *scan, *strend; /* scan goes up to strend for length of run */
1866 /* Make sure that we always have enough lookahead, except
1867 * at the end of the input file. We need MAX_MATCH bytes
1868 * for the longest run, plus one for the unrolled loop.
1870 if (s->lookahead <= MAX_MATCH) {
1872 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
1875 if (s->lookahead == 0) break; /* flush the current block */
1878 /* See how many times the previous byte repeats */
1879 s->match_length = 0;
1880 if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
1881 scan = s->window + s->strstart - 1;
1883 if (prev == *++scan && prev == *++scan && prev == *++scan) {
1884 strend = s->window + s->strstart + MAX_MATCH;
1886 } while (prev == *++scan && prev == *++scan &&
1887 prev == *++scan && prev == *++scan &&
1888 prev == *++scan && prev == *++scan &&
1889 prev == *++scan && prev == *++scan &&
1891 s->match_length = MAX_MATCH - (uInt)(strend - scan);
1892 if (s->match_length > s->lookahead)
1893 s->match_length = s->lookahead;
1895 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
1898 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1899 if (s->match_length >= MIN_MATCH) {
1900 check_match(s, s->strstart, s->strstart - 1, s->match_length);
1902 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
1904 s->lookahead -= s->match_length;
1905 s->strstart += s->match_length;
1906 s->match_length = 0;
1908 /* No match, output a literal byte */
1909 Tracevv((stderr,"%c", s->window[s->strstart]));
1910 _tr_tally_lit (s, s->window[s->strstart], bflush);
1914 if (bflush) FLUSH_BLOCK(s, 0);
1917 if (flush == Z_FINISH) {
1926 /* ===========================================================================
1927 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
1928 * (It will be regenerated if this run of deflate switches away from Huffman.)
1930 local block_state deflate_huff(s, flush)
1934 int bflush; /* set if current block must be flushed */
1937 /* Make sure that we have a literal to write. */
1938 if (s->lookahead == 0) {
1940 if (s->lookahead == 0) {
1941 if (flush == Z_NO_FLUSH)
1943 break; /* flush the current block */
1947 /* Output a literal byte */
1948 s->match_length = 0;
1949 Tracevv((stderr,"%c", s->window[s->strstart]));
1950 _tr_tally_lit (s, s->window[s->strstart], bflush);
1953 if (bflush) FLUSH_BLOCK(s, 0);
1956 if (flush == Z_FINISH) {