pngcrush  1.8.13
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deflate.c
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1 /* deflate.c -- compress data using the deflation algorithm
2  * Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler
3  * For conditions of distribution and use, see copyright notice in zlib.h
4  */
5 
6 /*
7  * ALGORITHM
8  *
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).
12  *
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.
30  *
31  * ACKNOWLEDGEMENTS
32  *
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.
36  *
37  * REFERENCES
38  *
39  * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40  * Available in http://tools.ietf.org/html/rfc1951
41  *
42  * A description of the Rabin and Karp algorithm is given in the book
43  * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
44  *
45  * Fiala,E.R., and Greene,D.H.
46  * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
47  *
48  */
49 
50 /* @(#) $Id$ */
51 
52 #include "deflate.h"
53 
54 const char deflate_copyright[] =
55  " deflate 1.2.11 Copyright 1995-2017 Jean-loup Gailly and Mark Adler ";
56 /*
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.
61  */
62 
63 /* ===========================================================================
64  * Function prototypes.
65  */
66 typedef enum {
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 */
71 } block_state;
72 
73 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74 /* Compression function. Returns the block state after the call. */
75 
77 local void slide_hash OF((deflate_state *s));
81 #ifndef FASTEST
83 #endif
86 local void lm_init OF((deflate_state *s));
87 local void putShortMSB OF((deflate_state *s, uInt b));
88 local void flush_pending OF((z_streamp strm));
89 local unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
90 #ifdef ASMV
91 # pragma message("Assembler code may have bugs -- use at your own risk")
92  void match_init OF((void)); /* asm code initialization */
93  uInt longest_match OF((deflate_state *s, IPos cur_match));
94 #else
95 local uInt longest_match OF((deflate_state *s, IPos cur_match));
96 #endif
97 
98 #ifdef ZLIB_DEBUG
99 local void check_match OF((deflate_state *s, IPos start, IPos match,
100  int length));
101 #endif
102 
103 /* ===========================================================================
104  * Local data
105  */
106 
107 #define NIL 0
108 /* Tail of hash chains */
109 
110 #ifndef TOO_FAR
111 # define TOO_FAR 4096
112 #endif
113 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
114 
115 /* Values for max_lazy_match, good_match and max_chain_length, depending on
116  * the desired pack level (0..9). The values given below have been tuned to
117  * exclude worst case performance for pathological files. Better values may be
118  * found for specific files.
119  */
120 typedef struct config_s {
121  ush good_length; /* reduce lazy search above this match length */
122  ush max_lazy; /* do not perform lazy search above this match length */
123  ush nice_length; /* quit search above this match length */
126 } config;
127 
128 #ifdef FASTEST
129 local const config configuration_table[2] = {
130 /* good lazy nice chain */
131 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
132 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
133 #else
135 /* good lazy nice chain */
136 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
137 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
138 /* 2 */ {4, 5, 16, 8, deflate_fast},
139 /* 3 */ {4, 6, 32, 32, deflate_fast},
140 
141 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
142 /* 5 */ {8, 16, 32, 32, deflate_slow},
143 /* 6 */ {8, 16, 128, 128, deflate_slow},
144 /* 7 */ {8, 32, 128, 256, deflate_slow},
145 /* 8 */ {32, 128, 258, 1024, deflate_slow},
146 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
147 #endif
148 
149 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
150  * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
151  * meaning.
152  */
153 
154 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
155 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0))
156 
157 /* ===========================================================================
158  * Update a hash value with the given input byte
159  * IN assertion: all calls to UPDATE_HASH are made with consecutive input
160  * characters, so that a running hash key can be computed from the previous
161  * key instead of complete recalculation each time.
162  */
163 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
164 
165 
166 /* ===========================================================================
167  * Insert string str in the dictionary and set match_head to the previous head
168  * of the hash chain (the most recent string with same hash key). Return
169  * the previous length of the hash chain.
170  * If this file is compiled with -DFASTEST, the compression level is forced
171  * to 1, and no hash chains are maintained.
172  * IN assertion: all calls to INSERT_STRING are made with consecutive input
173  * characters and the first MIN_MATCH bytes of str are valid (except for
174  * the last MIN_MATCH-1 bytes of the input file).
175  */
176 #ifdef FASTEST
177 #define INSERT_STRING(s, str, match_head) \
178  (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
179  match_head = s->head[s->ins_h], \
180  s->head[s->ins_h] = (Pos)(str))
181 #else
182 #define INSERT_STRING(s, str, match_head) \
183  (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
184  match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
185  s->head[s->ins_h] = (Pos)(str))
186 #endif
187 
188 /* ===========================================================================
189  * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
190  * prev[] will be initialized on the fly.
191  */
192 #define CLEAR_HASH(s) \
193  s->head[s->hash_size-1] = NIL; \
194  zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
195 
196 /* ===========================================================================
197  * Slide the hash table when sliding the window down (could be avoided with 32
198  * bit values at the expense of memory usage). We slide even when level == 0 to
199  * keep the hash table consistent if we switch back to level > 0 later.
200  */
202  deflate_state *s;
203 {
204  unsigned n, m;
205  Posf *p;
206  uInt wsize = s->w_size;
207 
208  n = s->hash_size;
209  p = &s->head[n];
210  do {
211  m = *--p;
212  *p = (Pos)(m >= wsize ? m - wsize : NIL);
213  } while (--n);
214  n = wsize;
215 #ifndef FASTEST
216  p = &s->prev[n];
217  do {
218  m = *--p;
219  *p = (Pos)(m >= wsize ? m - wsize : NIL);
220  /* If n is not on any hash chain, prev[n] is garbage but
221  * its value will never be used.
222  */
223  } while (--n);
224 #endif
225 }
226 
227 /* ========================================================================= */
228 int ZEXPORT deflateInit_(strm, level, version, stream_size)
229  z_streamp strm;
230  int level;
231  const char *version;
232  int stream_size;
233 {
234  return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
235  Z_DEFAULT_STRATEGY, version, stream_size);
236  /* To do: ignore strm->next_in if we use it as window */
237 }
238 
239 /* ========================================================================= */
240 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
241  version, stream_size)
242  z_streamp strm;
243  int level;
244  int method;
245  int windowBits;
246  int memLevel;
247  int strategy;
248  const char *version;
249  int stream_size;
250 {
251  deflate_state *s;
252  int wrap = 1;
253  static const char my_version[] = ZLIB_VERSION;
254 
255  ushf *overlay;
256  /* We overlay pending_buf and d_buf+l_buf. This works since the average
257  * output size for (length,distance) codes is <= 24 bits.
258  */
259 
260  if (version == Z_NULL || version[0] != my_version[0] ||
261  stream_size != sizeof(z_stream)) {
262  return Z_VERSION_ERROR;
263  }
264  if (strm == Z_NULL) return Z_STREAM_ERROR;
265 
266  strm->msg = Z_NULL;
267  if (strm->zalloc == (alloc_func)0) {
268 #ifdef Z_SOLO
269  return Z_STREAM_ERROR;
270 #else
271  strm->zalloc = zcalloc;
272  strm->opaque = (voidpf)0;
273 #endif
274  }
275  if (strm->zfree == (free_func)0)
276 #ifdef Z_SOLO
277  return Z_STREAM_ERROR;
278 #else
279  strm->zfree = zcfree;
280 #endif
281 
282 #ifdef FASTEST
283  if (level != 0) level = 1;
284 #else
285  if (level == Z_DEFAULT_COMPRESSION) level = 6;
286 #endif
287 
288  if (windowBits < 0) { /* suppress zlib wrapper */
289  wrap = 0;
290  windowBits = -windowBits;
291  }
292 #ifdef GZIP
293  else if (windowBits > 15) {
294  wrap = 2; /* write gzip wrapper instead */
295  windowBits -= 16;
296  }
297 #endif
298  if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
299  windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
300  strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) {
301  return Z_STREAM_ERROR;
302  }
303  if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
304  s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
305  if (s == Z_NULL) return Z_MEM_ERROR;
306  strm->state = (struct internal_state FAR *)s;
307  s->strm = strm;
308  s->status = INIT_STATE; /* to pass state test in deflateReset() */
309 
310  s->wrap = wrap;
311  s->gzhead = Z_NULL;
312  s->w_bits = (uInt)windowBits;
313  s->w_size = 1 << s->w_bits;
314  s->w_mask = s->w_size - 1;
315 
316  s->hash_bits = (uInt)memLevel + 7;
317  s->hash_size = 1 << s->hash_bits;
318  s->hash_mask = s->hash_size - 1;
319  s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
320 
321  s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
322  s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
323  s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
324 
325  s->high_water = 0; /* nothing written to s->window yet */
326 
327  s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
328 
329  overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
330  s->pending_buf = (uchf *) overlay;
331  s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
332 
333  if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
334  s->pending_buf == Z_NULL) {
335  s->status = FINISH_STATE;
337  deflateEnd (strm);
338  return Z_MEM_ERROR;
339  }
340  s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
341  s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
342 
343  s->level = level;
344  s->strategy = strategy;
345  s->method = (Byte)method;
346 
347  return deflateReset(strm);
348 }
349 
350 /* =========================================================================
351  * Check for a valid deflate stream state. Return 0 if ok, 1 if not.
352  */
354  z_streamp strm;
355 {
356  deflate_state *s;
357  if (strm == Z_NULL ||
358  strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0)
359  return 1;
360  s = strm->state;
361  if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE &&
362 #ifdef GZIP
363  s->status != GZIP_STATE &&
364 #endif
365  s->status != EXTRA_STATE &&
366  s->status != NAME_STATE &&
367  s->status != COMMENT_STATE &&
368  s->status != HCRC_STATE &&
369  s->status != BUSY_STATE &&
370  s->status != FINISH_STATE))
371  return 1;
372  return 0;
373 }
374 
375 /* ========================================================================= */
376 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
377  z_streamp strm;
378  const Bytef *dictionary;
379  uInt dictLength;
380 {
381  deflate_state *s;
382  uInt str, n;
383  int wrap;
384  unsigned avail;
385  z_const unsigned char *next;
386 
387  if (deflateStateCheck(strm) || dictionary == Z_NULL)
388  return Z_STREAM_ERROR;
389  s = strm->state;
390  wrap = s->wrap;
391  if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
392  return Z_STREAM_ERROR;
393 
394  /* when using zlib wrappers, compute Adler-32 for provided dictionary */
395  if (wrap == 1)
396  strm->adler = adler32(strm->adler, dictionary, dictLength);
397  s->wrap = 0; /* avoid computing Adler-32 in read_buf */
398 
399  /* if dictionary would fill window, just replace the history */
400  if (dictLength >= s->w_size) {
401  if (wrap == 0) { /* already empty otherwise */
402  CLEAR_HASH(s);
403  s->strstart = 0;
404  s->block_start = 0L;
405  s->insert = 0;
406  }
407  dictionary += dictLength - s->w_size; /* use the tail */
408  dictLength = s->w_size;
409  }
410 
411  /* insert dictionary into window and hash */
412  avail = strm->avail_in;
413  next = strm->next_in;
414  strm->avail_in = dictLength;
415  strm->next_in = (z_const Bytef *)dictionary;
416  fill_window(s);
417  while (s->lookahead >= MIN_MATCH) {
418  str = s->strstart;
419  n = s->lookahead - (MIN_MATCH-1);
420  do {
421  UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
422 #ifndef FASTEST
423  s->prev[str & s->w_mask] = s->head[s->ins_h];
424 #endif
425  s->head[s->ins_h] = (Pos)str;
426  str++;
427  } while (--n);
428  s->strstart = str;
429  s->lookahead = MIN_MATCH-1;
430  fill_window(s);
431  }
432  s->strstart += s->lookahead;
433  s->block_start = (long)s->strstart;
434  s->insert = s->lookahead;
435  s->lookahead = 0;
436  s->match_length = s->prev_length = MIN_MATCH-1;
437  s->match_available = 0;
438  strm->next_in = next;
439  strm->avail_in = avail;
440  s->wrap = wrap;
441  return Z_OK;
442 }
443 
444 /* ========================================================================= */
445 int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength)
446  z_streamp strm;
447  Bytef *dictionary;
448  uInt *dictLength;
449 {
450  deflate_state *s;
451  uInt len;
452 
453  if (deflateStateCheck(strm))
454  return Z_STREAM_ERROR;
455  s = strm->state;
456  len = s->strstart + s->lookahead;
457  if (len > s->w_size)
458  len = s->w_size;
459  if (dictionary != Z_NULL && len)
460  zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len);
461  if (dictLength != Z_NULL)
462  *dictLength = len;
463  return Z_OK;
464 }
465 
466 /* ========================================================================= */
468  z_streamp strm;
469 {
470  deflate_state *s;
471 
472  if (deflateStateCheck(strm)) {
473  return Z_STREAM_ERROR;
474  }
475 
476  strm->total_in = strm->total_out = 0;
477  strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
479 
480  s = (deflate_state *)strm->state;
481  s->pending = 0;
482  s->pending_out = s->pending_buf;
483 
484  if (s->wrap < 0) {
485  s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
486  }
487  s->status =
488 #ifdef GZIP
489  s->wrap == 2 ? GZIP_STATE :
490 #endif
491  s->wrap ? INIT_STATE : BUSY_STATE;
492  strm->adler =
493 #ifdef GZIP
494  s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
495 #endif
496  adler32(0L, Z_NULL, 0);
497  s->last_flush = Z_NO_FLUSH;
498 
499  _tr_init(s);
500 
501  return Z_OK;
502 }
503 
504 /* ========================================================================= */
506  z_streamp strm;
507 {
508  int ret;
509 
510  ret = deflateResetKeep(strm);
511  if (ret == Z_OK)
512  lm_init(strm->state);
513  return ret;
514 }
515 
516 /* ========================================================================= */
518  z_streamp strm;
520 {
521  if (deflateStateCheck(strm) || strm->state->wrap != 2)
522  return Z_STREAM_ERROR;
523  strm->state->gzhead = head;
524  return Z_OK;
525 }
526 
527 /* ========================================================================= */
529  unsigned *pending;
530  int *bits;
531  z_streamp strm;
532 {
534  if (pending != Z_NULL)
535  *pending = strm->state->pending;
536  if (bits != Z_NULL)
537  *bits = strm->state->bi_valid;
538  return Z_OK;
539 }
540 
541 /* ========================================================================= */
542 int ZEXPORT deflatePrime (strm, bits, value)
543  z_streamp strm;
544  int bits;
545  int value;
546 {
547  deflate_state *s;
548  int put;
549 
551  s = strm->state;
552  if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
553  return Z_BUF_ERROR;
554  do {
555  put = Buf_size - s->bi_valid;
556  if (put > bits)
557  put = bits;
558  s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
559  s->bi_valid += put;
560  _tr_flush_bits(s);
561  value >>= put;
562  bits -= put;
563  } while (bits);
564  return Z_OK;
565 }
566 
567 /* ========================================================================= */
569  z_streamp strm;
570  int level;
571  int strategy;
572 {
573  deflate_state *s;
574  compress_func func;
575 
577  s = strm->state;
578 
579 #ifdef FASTEST
580  if (level != 0) level = 1;
581 #else
582  if (level == Z_DEFAULT_COMPRESSION) level = 6;
583 #endif
584  if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
585  return Z_STREAM_ERROR;
586  }
587  func = configuration_table[s->level].func;
588 
589  if ((strategy != s->strategy || func != configuration_table[level].func) &&
590  s->high_water) {
591  /* Flush the last buffer: */
592  int err = deflate(strm, Z_BLOCK);
593  if (err == Z_STREAM_ERROR)
594  return err;
595  if (strm->avail_out == 0)
596  return Z_BUF_ERROR;
597  }
598  if (s->level != level) {
599  if (s->level == 0 && s->matches != 0) {
600  if (s->matches == 1)
601  slide_hash(s);
602  else
603  CLEAR_HASH(s);
604  s->matches = 0;
605  }
606  s->level = level;
611  }
612  s->strategy = strategy;
613  return Z_OK;
614 }
615 
616 /* ========================================================================= */
617 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
618  z_streamp strm;
619  int good_length;
620  int max_lazy;
621  int nice_length;
622  int max_chain;
623 {
624  deflate_state *s;
625 
627  s = strm->state;
628  s->good_match = (uInt)good_length;
629  s->max_lazy_match = (uInt)max_lazy;
630  s->nice_match = nice_length;
631  s->max_chain_length = (uInt)max_chain;
632  return Z_OK;
633 }
634 
635 /* =========================================================================
636  * For the default windowBits of 15 and memLevel of 8, this function returns
637  * a close to exact, as well as small, upper bound on the compressed size.
638  * They are coded as constants here for a reason--if the #define's are
639  * changed, then this function needs to be changed as well. The return
640  * value for 15 and 8 only works for those exact settings.
641  *
642  * For any setting other than those defaults for windowBits and memLevel,
643  * the value returned is a conservative worst case for the maximum expansion
644  * resulting from using fixed blocks instead of stored blocks, which deflate
645  * can emit on compressed data for some combinations of the parameters.
646  *
647  * This function could be more sophisticated to provide closer upper bounds for
648  * every combination of windowBits and memLevel. But even the conservative
649  * upper bound of about 14% expansion does not seem onerous for output buffer
650  * allocation.
651  */
653  z_streamp strm;
654  uLong sourceLen;
655 {
656  deflate_state *s;
657  uLong complen, wraplen;
658 
659  /* conservative upper bound for compressed data */
660  complen = sourceLen +
661  ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
662 
663  /* if can't get parameters, return conservative bound plus zlib wrapper */
664  if (deflateStateCheck(strm))
665  return complen + 6;
666 
667  /* compute wrapper length */
668  s = strm->state;
669  switch (s->wrap) {
670  case 0: /* raw deflate */
671  wraplen = 0;
672  break;
673  case 1: /* zlib wrapper */
674  wraplen = 6 + (s->strstart ? 4 : 0);
675  break;
676 #ifdef GZIP
677  case 2: /* gzip wrapper */
678  wraplen = 18;
679  if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
680  Bytef *str;
681  if (s->gzhead->extra != Z_NULL)
682  wraplen += 2 + s->gzhead->extra_len;
683  str = s->gzhead->name;
684  if (str != Z_NULL)
685  do {
686  wraplen++;
687  } while (*str++);
688  str = s->gzhead->comment;
689  if (str != Z_NULL)
690  do {
691  wraplen++;
692  } while (*str++);
693  if (s->gzhead->hcrc)
694  wraplen += 2;
695  }
696  break;
697 #endif
698  default: /* for compiler happiness */
699  wraplen = 6;
700  }
701 
702  /* if not default parameters, return conservative bound */
703  if (s->w_bits != 15 || s->hash_bits != 8 + 7)
704  return complen + wraplen;
705 
706  /* default settings: return tight bound for that case */
707  return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
708  (sourceLen >> 25) + 13 - 6 + wraplen;
709 }
710 
711 /* =========================================================================
712  * Put a short in the pending buffer. The 16-bit value is put in MSB order.
713  * IN assertion: the stream state is correct and there is enough room in
714  * pending_buf.
715  */
716 local void putShortMSB (s, b)
717  deflate_state *s;
718  uInt b;
719 {
720  put_byte(s, (Byte)(b >> 8));
721  put_byte(s, (Byte)(b & 0xff));
722 }
723 
724 /* =========================================================================
725  * Flush as much pending output as possible. All deflate() output, except for
726  * some deflate_stored() output, goes through this function so some
727  * applications may wish to modify it to avoid allocating a large
728  * strm->next_out buffer and copying into it. (See also read_buf()).
729  */
731  z_streamp strm;
732 {
733  unsigned len;
734  deflate_state *s = strm->state;
735 
736  _tr_flush_bits(s);
737  len = s->pending;
738  if (len > strm->avail_out) len = strm->avail_out;
739  if (len == 0) return;
740 
741  zmemcpy(strm->next_out, s->pending_out, len);
742  strm->next_out += len;
743  s->pending_out += len;
744  strm->total_out += len;
745  strm->avail_out -= len;
746  s->pending -= len;
747  if (s->pending == 0) {
748  s->pending_out = s->pending_buf;
749  }
750 }
751 
752 /* ===========================================================================
753  * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1].
754  */
755 #define HCRC_UPDATE(beg) \
756  do { \
757  if (s->gzhead->hcrc && s->pending > (beg)) \
758  strm->adler = crc32(strm->adler, s->pending_buf + (beg), \
759  s->pending - (beg)); \
760  } while (0)
761 
762 /* ========================================================================= */
763 int ZEXPORT deflate (strm, flush)
764  z_streamp strm;
765  int flush;
766 {
767  int old_flush; /* value of flush param for previous deflate call */
768  deflate_state *s;
769 
770  if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) {
771  return Z_STREAM_ERROR;
772  }
773  s = strm->state;
774 
775  if (strm->next_out == Z_NULL ||
776  (strm->avail_in != 0 && strm->next_in == Z_NULL) ||
777  (s->status == FINISH_STATE && flush != Z_FINISH)) {
779  }
781 
782  old_flush = s->last_flush;
783  s->last_flush = flush;
784 
785  /* Flush as much pending output as possible */
786  if (s->pending != 0) {
788  if (strm->avail_out == 0) {
789  /* Since avail_out is 0, deflate will be called again with
790  * more output space, but possibly with both pending and
791  * avail_in equal to zero. There won't be anything to do,
792  * but this is not an error situation so make sure we
793  * return OK instead of BUF_ERROR at next call of deflate:
794  */
795  s->last_flush = -1;
796  return Z_OK;
797  }
798 
799  /* Make sure there is something to do and avoid duplicate consecutive
800  * flushes. For repeated and useless calls with Z_FINISH, we keep
801  * returning Z_STREAM_END instead of Z_BUF_ERROR.
802  */
803  } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
804  flush != Z_FINISH) {
806  }
807 
808  /* User must not provide more input after the first FINISH: */
809  if (s->status == FINISH_STATE && strm->avail_in != 0) {
811  }
812 
813  /* Write the header */
814  if (s->status == INIT_STATE) {
815  /* zlib header */
816  uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
817  uInt level_flags;
818 
819  if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
820  level_flags = 0;
821  else if (s->level < 6)
822  level_flags = 1;
823  else if (s->level == 6)
824  level_flags = 2;
825  else
826  level_flags = 3;
827  header |= (level_flags << 6);
828  if (s->strstart != 0) header |= PRESET_DICT;
829  header += 31 - (header % 31);
830 
831  putShortMSB(s, header);
832 
833  /* Save the adler32 of the preset dictionary: */
834  if (s->strstart != 0) {
835  putShortMSB(s, (uInt)(strm->adler >> 16));
836  putShortMSB(s, (uInt)(strm->adler & 0xffff));
837  }
838  strm->adler = adler32(0L, Z_NULL, 0);
839  s->status = BUSY_STATE;
840 
841  /* Compression must start with an empty pending buffer */
843  if (s->pending != 0) {
844  s->last_flush = -1;
845  return Z_OK;
846  }
847  }
848 #ifdef GZIP
849  if (s->status == GZIP_STATE) {
850  /* gzip header */
851  strm->adler = crc32(0L, Z_NULL, 0);
852  put_byte(s, 31);
853  put_byte(s, 139);
854  put_byte(s, 8);
855  if (s->gzhead == Z_NULL) {
856  put_byte(s, 0);
857  put_byte(s, 0);
858  put_byte(s, 0);
859  put_byte(s, 0);
860  put_byte(s, 0);
861  put_byte(s, s->level == 9 ? 2 :
862  (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
863  4 : 0));
864  put_byte(s, OS_CODE);
865  s->status = BUSY_STATE;
866 
867  /* Compression must start with an empty pending buffer */
869  if (s->pending != 0) {
870  s->last_flush = -1;
871  return Z_OK;
872  }
873  }
874  else {
875  put_byte(s, (s->gzhead->text ? 1 : 0) +
876  (s->gzhead->hcrc ? 2 : 0) +
877  (s->gzhead->extra == Z_NULL ? 0 : 4) +
878  (s->gzhead->name == Z_NULL ? 0 : 8) +
879  (s->gzhead->comment == Z_NULL ? 0 : 16)
880  );
881  put_byte(s, (Byte)(s->gzhead->time & 0xff));
882  put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
883  put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
884  put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
885  put_byte(s, s->level == 9 ? 2 :
886  (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
887  4 : 0));
888  put_byte(s, s->gzhead->os & 0xff);
889  if (s->gzhead->extra != Z_NULL) {
890  put_byte(s, s->gzhead->extra_len & 0xff);
891  put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
892  }
893  if (s->gzhead->hcrc)
895  s->pending);
896  s->gzindex = 0;
897  s->status = EXTRA_STATE;
898  }
899  }
900  if (s->status == EXTRA_STATE) {
901  if (s->gzhead->extra != Z_NULL) {
902  ulg beg = s->pending; /* start of bytes to update crc */
903  uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex;
904  while (s->pending + left > s->pending_buf_size) {
905  uInt copy = s->pending_buf_size - s->pending;
906  zmemcpy(s->pending_buf + s->pending,
907  s->gzhead->extra + s->gzindex, copy);
908  s->pending = s->pending_buf_size;
909  HCRC_UPDATE(beg);
910  s->gzindex += copy;
912  if (s->pending != 0) {
913  s->last_flush = -1;
914  return Z_OK;
915  }
916  beg = 0;
917  left -= copy;
918  }
919  zmemcpy(s->pending_buf + s->pending,
920  s->gzhead->extra + s->gzindex, left);
921  s->pending += left;
922  HCRC_UPDATE(beg);
923  s->gzindex = 0;
924  }
925  s->status = NAME_STATE;
926  }
927  if (s->status == NAME_STATE) {
928  if (s->gzhead->name != Z_NULL) {
929  ulg beg = s->pending; /* start of bytes to update crc */
930  int val;
931  do {
932  if (s->pending == s->pending_buf_size) {
933  HCRC_UPDATE(beg);
935  if (s->pending != 0) {
936  s->last_flush = -1;
937  return Z_OK;
938  }
939  beg = 0;
940  }
941  val = s->gzhead->name[s->gzindex++];
942  put_byte(s, val);
943  } while (val != 0);
944  HCRC_UPDATE(beg);
945  s->gzindex = 0;
946  }
947  s->status = COMMENT_STATE;
948  }
949  if (s->status == COMMENT_STATE) {
950  if (s->gzhead->comment != Z_NULL) {
951  ulg beg = s->pending; /* start of bytes to update crc */
952  int val;
953  do {
954  if (s->pending == s->pending_buf_size) {
955  HCRC_UPDATE(beg);
957  if (s->pending != 0) {
958  s->last_flush = -1;
959  return Z_OK;
960  }
961  beg = 0;
962  }
963  val = s->gzhead->comment[s->gzindex++];
964  put_byte(s, val);
965  } while (val != 0);
966  HCRC_UPDATE(beg);
967  }
968  s->status = HCRC_STATE;
969  }
970  if (s->status == HCRC_STATE) {
971  if (s->gzhead->hcrc) {
972  if (s->pending + 2 > s->pending_buf_size) {
974  if (s->pending != 0) {
975  s->last_flush = -1;
976  return Z_OK;
977  }
978  }
979  put_byte(s, (Byte)(strm->adler & 0xff));
980  put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
981  strm->adler = crc32(0L, Z_NULL, 0);
982  }
983  s->status = BUSY_STATE;
984 
985  /* Compression must start with an empty pending buffer */
987  if (s->pending != 0) {
988  s->last_flush = -1;
989  return Z_OK;
990  }
991  }
992 #endif
993 
994  /* Start a new block or continue the current one.
995  */
996  if (strm->avail_in != 0 || s->lookahead != 0 ||
997  (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
998  block_state bstate;
999 
1000  bstate = s->level == 0 ? deflate_stored(s, flush) :
1001  s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
1002  s->strategy == Z_RLE ? deflate_rle(s, flush) :
1003  (*(configuration_table[s->level].func))(s, flush);
1004 
1005  if (bstate == finish_started || bstate == finish_done) {
1006  s->status = FINISH_STATE;
1007  }
1008  if (bstate == need_more || bstate == finish_started) {
1009  if (strm->avail_out == 0) {
1010  s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
1011  }
1012  return Z_OK;
1013  /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
1014  * of deflate should use the same flush parameter to make sure
1015  * that the flush is complete. So we don't have to output an
1016  * empty block here, this will be done at next call. This also
1017  * ensures that for a very small output buffer, we emit at most
1018  * one empty block.
1019  */
1020  }
1021  if (bstate == block_done) {
1022  if (flush == Z_PARTIAL_FLUSH) {
1023  _tr_align(s);
1024  } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
1025  _tr_stored_block(s, (char*)0, 0L, 0);
1026  /* For a full flush, this empty block will be recognized
1027  * as a special marker by inflate_sync().
1028  */
1029  if (flush == Z_FULL_FLUSH) {
1030  CLEAR_HASH(s); /* forget history */
1031  if (s->lookahead == 0) {
1032  s->strstart = 0;
1033  s->block_start = 0L;
1034  s->insert = 0;
1035  }
1036  }
1037  }
1039  if (strm->avail_out == 0) {
1040  s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
1041  return Z_OK;
1042  }
1043  }
1044  }
1045 
1046  if (flush != Z_FINISH) return Z_OK;
1047  if (s->wrap <= 0) return Z_STREAM_END;
1048 
1049  /* Write the trailer */
1050 #ifdef GZIP
1051  if (s->wrap == 2) {
1052  put_byte(s, (Byte)(strm->adler & 0xff));
1053  put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
1054  put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
1055  put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
1056  put_byte(s, (Byte)(strm->total_in & 0xff));
1057  put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
1058  put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
1059  put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
1060  }
1061  else
1062 #endif
1063  {
1064  putShortMSB(s, (uInt)(strm->adler >> 16));
1065  putShortMSB(s, (uInt)(strm->adler & 0xffff));
1066  }
1068  /* If avail_out is zero, the application will call deflate again
1069  * to flush the rest.
1070  */
1071  if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
1072  return s->pending != 0 ? Z_OK : Z_STREAM_END;
1073 }
1074 
1075 /* ========================================================================= */
1077  z_streamp strm;
1078 {
1079  int status;
1080 
1081  if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
1082 
1083  status = strm->state->status;
1084 
1085  /* Deallocate in reverse order of allocations: */
1087  TRY_FREE(strm, strm->state->head);
1088  TRY_FREE(strm, strm->state->prev);
1090 
1091  ZFREE(strm, strm->state);
1092  strm->state = Z_NULL;
1093 
1094  return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1095 }
1096 
1097 /* =========================================================================
1098  * Copy the source state to the destination state.
1099  * To simplify the source, this is not supported for 16-bit MSDOS (which
1100  * doesn't have enough memory anyway to duplicate compression states).
1101  */
1102 int ZEXPORT deflateCopy (dest, source)
1103  z_streamp dest;
1104  z_streamp source;
1105 {
1106 #ifdef MAXSEG_64K
1107  return Z_STREAM_ERROR;
1108 #else
1109  deflate_state *ds;
1110  deflate_state *ss;
1111  ushf *overlay;
1112 
1113 
1114  if (deflateStateCheck(source) || dest == Z_NULL) {
1115  return Z_STREAM_ERROR;
1116  }
1117 
1118  ss = source->state;
1119 
1120  zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1121 
1122  ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1123  if (ds == Z_NULL) return Z_MEM_ERROR;
1124  dest->state = (struct internal_state FAR *) ds;
1125  zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1126  ds->strm = dest;
1127 
1128  ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1129  ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1130  ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1131  overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1132  ds->pending_buf = (uchf *) overlay;
1133 
1134  if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1135  ds->pending_buf == Z_NULL) {
1136  deflateEnd (dest);
1137  return Z_MEM_ERROR;
1138  }
1139  /* following zmemcpy do not work for 16-bit MSDOS */
1140  zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1141  zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1142  zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1143  zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1144 
1145  ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1146  ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1147  ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1148 
1149  ds->l_desc.dyn_tree = ds->dyn_ltree;
1150  ds->d_desc.dyn_tree = ds->dyn_dtree;
1151  ds->bl_desc.dyn_tree = ds->bl_tree;
1152 
1153  return Z_OK;
1154 #endif /* MAXSEG_64K */
1155 }
1156 
1157 /* ===========================================================================
1158  * Read a new buffer from the current input stream, update the adler32
1159  * and total number of bytes read. All deflate() input goes through
1160  * this function so some applications may wish to modify it to avoid
1161  * allocating a large strm->next_in buffer and copying from it.
1162  * (See also flush_pending()).
1163  */
1164 local unsigned read_buf(strm, buf, size)
1165  z_streamp strm;
1166  Bytef *buf;
1167  unsigned size;
1168 {
1169  unsigned len = strm->avail_in;
1170 
1171  if (len > size) len = size;
1172  if (len == 0) return 0;
1173 
1174  strm->avail_in -= len;
1175 
1176  zmemcpy(buf, strm->next_in, len);
1177  if (strm->state->wrap == 1) {
1178  strm->adler = adler32(strm->adler, buf, len);
1179  }
1180 #ifdef GZIP
1181  else if (strm->state->wrap == 2) {
1182  strm->adler = crc32(strm->adler, buf, len);
1183  }
1184 #endif
1185  strm->next_in += len;
1186  strm->total_in += len;
1187 
1188  return len;
1189 }
1190 
1191 /* ===========================================================================
1192  * Initialize the "longest match" routines for a new zlib stream
1193  */
1194 local void lm_init (s)
1195  deflate_state *s;
1196 {
1197  s->window_size = (ulg)2L*s->w_size;
1198 
1199  CLEAR_HASH(s);
1200 
1201  /* Set the default configuration parameters:
1202  */
1203  s->max_lazy_match = configuration_table[s->level].max_lazy;
1204  s->good_match = configuration_table[s->level].good_length;
1205  s->nice_match = configuration_table[s->level].nice_length;
1206  s->max_chain_length = configuration_table[s->level].max_chain;
1207 
1208  s->strstart = 0;
1209  s->block_start = 0L;
1210  s->lookahead = 0;
1211  s->insert = 0;
1212  s->match_length = s->prev_length = MIN_MATCH-1;
1213  s->match_available = 0;
1214  s->ins_h = 0;
1215 #ifndef FASTEST
1216 #ifdef ASMV
1217  match_init(); /* initialize the asm code */
1218 #endif
1219 #endif
1220 }
1221 
1222 #ifndef FASTEST
1223 /* ===========================================================================
1224  * Set match_start to the longest match starting at the given string and
1225  * return its length. Matches shorter or equal to prev_length are discarded,
1226  * in which case the result is equal to prev_length and match_start is
1227  * garbage.
1228  * IN assertions: cur_match is the head of the hash chain for the current
1229  * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1230  * OUT assertion: the match length is not greater than s->lookahead.
1231  */
1232 #ifndef ASMV
1233 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1234  * match.S. The code will be functionally equivalent.
1235  */
1236 local uInt longest_match(s, cur_match)
1237  deflate_state *s;
1238  IPos cur_match; /* current match */
1239 {
1240  unsigned chain_length = s->max_chain_length;/* max hash chain length */
1241  register Bytef *scan = s->window + s->strstart; /* current string */
1242  register Bytef *match; /* matched string */
1243  register int len; /* length of current match */
1244  int best_len = (int)s->prev_length; /* best match length so far */
1245  int nice_match = s->nice_match; /* stop if match long enough */
1246  IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1247  s->strstart - (IPos)MAX_DIST(s) : NIL;
1248  /* Stop when cur_match becomes <= limit. To simplify the code,
1249  * we prevent matches with the string of window index 0.
1250  */
1251  Posf *prev = s->prev;
1252  uInt wmask = s->w_mask;
1253 
1254 #ifdef UNALIGNED_OK
1255  /* Compare two bytes at a time. Note: this is not always beneficial.
1256  * Try with and without -DUNALIGNED_OK to check.
1257  */
1258  register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1259  register ush scan_start = *(ushf*)scan;
1260  register ush scan_end = *(ushf*)(scan+best_len-1);
1261 #else
1262  register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1263  register Byte scan_end1 = scan[best_len-1];
1264  register Byte scan_end = scan[best_len];
1265 #endif
1266 
1267  /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1268  * It is easy to get rid of this optimization if necessary.
1269  */
1270  Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1271 
1272  /* Do not waste too much time if we already have a good match: */
1273  if (s->prev_length >= s->good_match) {
1274  chain_length >>= 2;
1275  }
1276  /* Do not look for matches beyond the end of the input. This is necessary
1277  * to make deflate deterministic.
1278  */
1279  if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead;
1280 
1281  Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1282 
1283  do {
1284  Assert(cur_match < s->strstart, "no future");
1285  match = s->window + cur_match;
1286 
1287  /* Skip to next match if the match length cannot increase
1288  * or if the match length is less than 2. Note that the checks below
1289  * for insufficient lookahead only occur occasionally for performance
1290  * reasons. Therefore uninitialized memory will be accessed, and
1291  * conditional jumps will be made that depend on those values.
1292  * However the length of the match is limited to the lookahead, so
1293  * the output of deflate is not affected by the uninitialized values.
1294  */
1295 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1296  /* This code assumes sizeof(unsigned short) == 2. Do not use
1297  * UNALIGNED_OK if your compiler uses a different size.
1298  */
1299  if (*(ushf*)(match+best_len-1) != scan_end ||
1300  *(ushf*)match != scan_start) continue;
1301 
1302  /* It is not necessary to compare scan[2] and match[2] since they are
1303  * always equal when the other bytes match, given that the hash keys
1304  * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1305  * strstart+3, +5, ... up to strstart+257. We check for insufficient
1306  * lookahead only every 4th comparison; the 128th check will be made
1307  * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1308  * necessary to put more guard bytes at the end of the window, or
1309  * to check more often for insufficient lookahead.
1310  */
1311  Assert(scan[2] == match[2], "scan[2]?");
1312  scan++, match++;
1313  do {
1314  } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1315  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1316  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1317  *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1318  scan < strend);
1319  /* The funny "do {}" generates better code on most compilers */
1320 
1321  /* Here, scan <= window+strstart+257 */
1322  Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1323  if (*scan == *match) scan++;
1324 
1325  len = (MAX_MATCH - 1) - (int)(strend-scan);
1326  scan = strend - (MAX_MATCH-1);
1327 
1328 #else /* UNALIGNED_OK */
1329 
1330  if (match[best_len] != scan_end ||
1331  match[best_len-1] != scan_end1 ||
1332  *match != *scan ||
1333  *++match != scan[1]) continue;
1334 
1335  /* The check at best_len-1 can be removed because it will be made
1336  * again later. (This heuristic is not always a win.)
1337  * It is not necessary to compare scan[2] and match[2] since they
1338  * are always equal when the other bytes match, given that
1339  * the hash keys are equal and that HASH_BITS >= 8.
1340  */
1341  scan += 2, match++;
1342  Assert(*scan == *match, "match[2]?");
1343 
1344  /* We check for insufficient lookahead only every 8th comparison;
1345  * the 256th check will be made at strstart+258.
1346  */
1347  do {
1348  } while (*++scan == *++match && *++scan == *++match &&
1349  *++scan == *++match && *++scan == *++match &&
1350  *++scan == *++match && *++scan == *++match &&
1351  *++scan == *++match && *++scan == *++match &&
1352  scan < strend);
1353 
1354  Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1355 
1356  len = MAX_MATCH - (int)(strend - scan);
1357  scan = strend - MAX_MATCH;
1358 
1359 #endif /* UNALIGNED_OK */
1360 
1361  if (len > best_len) {
1362  s->match_start = cur_match;
1363  best_len = len;
1364  if (len >= nice_match) break;
1365 #ifdef UNALIGNED_OK
1366  scan_end = *(ushf*)(scan+best_len-1);
1367 #else
1368  scan_end1 = scan[best_len-1];
1369  scan_end = scan[best_len];
1370 #endif
1371  }
1372  } while ((cur_match = prev[cur_match & wmask]) > limit
1373  && --chain_length != 0);
1374 
1375  if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1376  return s->lookahead;
1377 }
1378 #endif /* ASMV */
1379 
1380 #else /* FASTEST */
1381 
1382 /* ---------------------------------------------------------------------------
1383  * Optimized version for FASTEST only
1384  */
1385 local uInt longest_match(s, cur_match)
1386  deflate_state *s;
1387  IPos cur_match; /* current match */
1388 {
1389  register Bytef *scan = s->window + s->strstart; /* current string */
1390  register Bytef *match; /* matched string */
1391  register int len; /* length of current match */
1392  register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1393 
1394  /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1395  * It is easy to get rid of this optimization if necessary.
1396  */
1397  Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1398 
1399  Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1400 
1401  Assert(cur_match < s->strstart, "no future");
1402 
1403  match = s->window + cur_match;
1404 
1405  /* Return failure if the match length is less than 2:
1406  */
1407  if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1408 
1409  /* The check at best_len-1 can be removed because it will be made
1410  * again later. (This heuristic is not always a win.)
1411  * It is not necessary to compare scan[2] and match[2] since they
1412  * are always equal when the other bytes match, given that
1413  * the hash keys are equal and that HASH_BITS >= 8.
1414  */
1415  scan += 2, match += 2;
1416  Assert(*scan == *match, "match[2]?");
1417 
1418  /* We check for insufficient lookahead only every 8th comparison;
1419  * the 256th check will be made at strstart+258.
1420  */
1421  do {
1422  } while (*++scan == *++match && *++scan == *++match &&
1423  *++scan == *++match && *++scan == *++match &&
1424  *++scan == *++match && *++scan == *++match &&
1425  *++scan == *++match && *++scan == *++match &&
1426  scan < strend);
1427 
1428  Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1429 
1430  len = MAX_MATCH - (int)(strend - scan);
1431 
1432  if (len < MIN_MATCH) return MIN_MATCH - 1;
1433 
1434  s->match_start = cur_match;
1435  return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1436 }
1437 
1438 #endif /* FASTEST */
1439 
1440 #ifdef ZLIB_DEBUG
1441 
1442 #define EQUAL 0
1443 /* result of memcmp for equal strings */
1444 
1445 /* ===========================================================================
1446  * Check that the match at match_start is indeed a match.
1447  */
1448 local void check_match(s, start, match, length)
1449  deflate_state *s;
1450  IPos start, match;
1451  int length;
1452 {
1453  /* check that the match is indeed a match */
1454  if (zmemcmp(s->window + match,
1455  s->window + start, length) != EQUAL) {
1456  fprintf(stderr, " start %u, match %u, length %d\n",
1457  start, match, length);
1458  do {
1459  fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1460  } while (--length != 0);
1461  z_error("invalid match");
1462  }
1463  if (z_verbose > 1) {
1464  fprintf(stderr,"\\[%d,%d]", start-match, length);
1465  do { putc(s->window[start++], stderr); } while (--length != 0);
1466  }
1467 }
1468 #else
1469 # define check_match(s, start, match, length)
1470 #endif /* ZLIB_DEBUG */
1471 
1472 /* ===========================================================================
1473  * Fill the window when the lookahead becomes insufficient.
1474  * Updates strstart and lookahead.
1475  *
1476  * IN assertion: lookahead < MIN_LOOKAHEAD
1477  * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1478  * At least one byte has been read, or avail_in == 0; reads are
1479  * performed for at least two bytes (required for the zip translate_eol
1480  * option -- not supported here).
1481  */
1483  deflate_state *s;
1484 {
1485  unsigned n;
1486  unsigned more; /* Amount of free space at the end of the window. */
1487  uInt wsize = s->w_size;
1488 
1489  Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1490 
1491  do {
1492  more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1493 
1494  /* Deal with !@#$% 64K limit: */
1495  if (sizeof(int) <= 2) {
1496  if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1497  more = wsize;
1498 
1499  } else if (more == (unsigned)(-1)) {
1500  /* Very unlikely, but possible on 16 bit machine if
1501  * strstart == 0 && lookahead == 1 (input done a byte at time)
1502  */
1503  more--;
1504  }
1505  }
1506 
1507  /* If the window is almost full and there is insufficient lookahead,
1508  * move the upper half to the lower one to make room in the upper half.
1509  */
1510  if (s->strstart >= wsize+MAX_DIST(s)) {
1511 
1512  zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more);
1513  s->match_start -= wsize;
1514  s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1515  s->block_start -= (long) wsize;
1516  slide_hash(s);
1517  more += wsize;
1518  }
1519  if (s->strm->avail_in == 0) break;
1520 
1521  /* If there was no sliding:
1522  * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1523  * more == window_size - lookahead - strstart
1524  * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1525  * => more >= window_size - 2*WSIZE + 2
1526  * In the BIG_MEM or MMAP case (not yet supported),
1527  * window_size == input_size + MIN_LOOKAHEAD &&
1528  * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1529  * Otherwise, window_size == 2*WSIZE so more >= 2.
1530  * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1531  */
1532  Assert(more >= 2, "more < 2");
1533 
1534  n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1535  s->lookahead += n;
1536 
1537  /* Initialize the hash value now that we have some input: */
1538  if (s->lookahead + s->insert >= MIN_MATCH) {
1539  uInt str = s->strstart - s->insert;
1540  s->ins_h = s->window[str];
1541  UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1542 #if MIN_MATCH != 3
1543  Call UPDATE_HASH() MIN_MATCH-3 more times
1544 #endif
1545  while (s->insert) {
1546  UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1547 #ifndef FASTEST
1548  s->prev[str & s->w_mask] = s->head[s->ins_h];
1549 #endif
1550  s->head[s->ins_h] = (Pos)str;
1551  str++;
1552  s->insert--;
1553  if (s->lookahead + s->insert < MIN_MATCH)
1554  break;
1555  }
1556  }
1557  /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1558  * but this is not important since only literal bytes will be emitted.
1559  */
1560 
1561  } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1562 
1563  /* If the WIN_INIT bytes after the end of the current data have never been
1564  * written, then zero those bytes in order to avoid memory check reports of
1565  * the use of uninitialized (or uninitialised as Julian writes) bytes by
1566  * the longest match routines. Update the high water mark for the next
1567  * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1568  * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1569  */
1570  if (s->high_water < s->window_size) {
1571  ulg curr = s->strstart + (ulg)(s->lookahead);
1572  ulg init;
1573 
1574  if (s->high_water < curr) {
1575  /* Previous high water mark below current data -- zero WIN_INIT
1576  * bytes or up to end of window, whichever is less.
1577  */
1578  init = s->window_size - curr;
1579  if (init > WIN_INIT)
1580  init = WIN_INIT;
1581  zmemzero(s->window + curr, (unsigned)init);
1582  s->high_water = curr + init;
1583  }
1584  else if (s->high_water < (ulg)curr + WIN_INIT) {
1585  /* High water mark at or above current data, but below current data
1586  * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1587  * to end of window, whichever is less.
1588  */
1589  init = (ulg)curr + WIN_INIT - s->high_water;
1590  if (init > s->window_size - s->high_water)
1591  init = s->window_size - s->high_water;
1592  zmemzero(s->window + s->high_water, (unsigned)init);
1593  s->high_water += init;
1594  }
1595  }
1596 
1597  Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1598  "not enough room for search");
1599 }
1600 
1601 /* ===========================================================================
1602  * Flush the current block, with given end-of-file flag.
1603  * IN assertion: strstart is set to the end of the current match.
1604  */
1605 #define FLUSH_BLOCK_ONLY(s, last) { \
1606  _tr_flush_block(s, (s->block_start >= 0L ? \
1607  (charf *)&s->window[(unsigned)s->block_start] : \
1608  (charf *)Z_NULL), \
1609  (ulg)((long)s->strstart - s->block_start), \
1610  (last)); \
1611  s->block_start = s->strstart; \
1612  flush_pending(s->strm); \
1613  Tracev((stderr,"[FLUSH]")); \
1614 }
1615 
1616 /* Same but force premature exit if necessary. */
1617 #define FLUSH_BLOCK(s, last) { \
1618  FLUSH_BLOCK_ONLY(s, last); \
1619  if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1620 }
1621 
1622 /* Maximum stored block length in deflate format (not including header). */
1623 #define MAX_STORED 65535
1624 
1625 /* Minimum of a and b. */
1626 #define MIN(a, b) ((a) > (b) ? (b) : (a))
1627 
1628 /* ===========================================================================
1629  * Copy without compression as much as possible from the input stream, return
1630  * the current block state.
1631  *
1632  * In case deflateParams() is used to later switch to a non-zero compression
1633  * level, s->matches (otherwise unused when storing) keeps track of the number
1634  * of hash table slides to perform. If s->matches is 1, then one hash table
1635  * slide will be done when switching. If s->matches is 2, the maximum value
1636  * allowed here, then the hash table will be cleared, since two or more slides
1637  * is the same as a clear.
1638  *
1639  * deflate_stored() is written to minimize the number of times an input byte is
1640  * copied. It is most efficient with large input and output buffers, which
1641  * maximizes the opportunites to have a single copy from next_in to next_out.
1642  */
1644  deflate_state *s;
1645  int flush;
1646 {
1647  /* Smallest worthy block size when not flushing or finishing. By default
1648  * this is 32K. This can be as small as 507 bytes for memLevel == 1. For
1649  * large input and output buffers, the stored block size will be larger.
1650  */
1651  unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size);
1652 
1653  /* Copy as many min_block or larger stored blocks directly to next_out as
1654  * possible. If flushing, copy the remaining available input to next_out as
1655  * stored blocks, if there is enough space.
1656  */
1657  unsigned len, left, have, last = 0;
1658  unsigned used = s->strm->avail_in;
1659  do {
1660  /* Set len to the maximum size block that we can copy directly with the
1661  * available input data and output space. Set left to how much of that
1662  * would be copied from what's left in the window.
1663  */
1664  len = MAX_STORED; /* maximum deflate stored block length */
1665  have = (s->bi_valid + 42) >> 3; /* number of header bytes */
1666  if (s->strm->avail_out < have) /* need room for header */
1667  break;
1668  /* maximum stored block length that will fit in avail_out: */
1669  have = s->strm->avail_out - have;
1670  left = s->strstart - s->block_start; /* bytes left in window */
1671  if (len > (ulg)left + s->strm->avail_in)
1672  len = left + s->strm->avail_in; /* limit len to the input */
1673  if (len > have)
1674  len = have; /* limit len to the output */
1675 
1676  /* If the stored block would be less than min_block in length, or if
1677  * unable to copy all of the available input when flushing, then try
1678  * copying to the window and the pending buffer instead. Also don't
1679  * write an empty block when flushing -- deflate() does that.
1680  */
1681  if (len < min_block && ((len == 0 && flush != Z_FINISH) ||
1682  flush == Z_NO_FLUSH ||
1683  len != left + s->strm->avail_in))
1684  break;
1685 
1686  /* Make a dummy stored block in pending to get the header bytes,
1687  * including any pending bits. This also updates the debugging counts.
1688  */
1689  last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0;
1690  _tr_stored_block(s, (char *)0, 0L, last);
1691 
1692  /* Replace the lengths in the dummy stored block with len. */
1693  s->pending_buf[s->pending - 4] = len;
1694  s->pending_buf[s->pending - 3] = len >> 8;
1695  s->pending_buf[s->pending - 2] = ~len;
1696  s->pending_buf[s->pending - 1] = ~len >> 8;
1697 
1698  /* Write the stored block header bytes. */
1699  flush_pending(s->strm);
1700 
1701 #ifdef ZLIB_DEBUG
1702  /* Update debugging counts for the data about to be copied. */
1703  s->compressed_len += len << 3;
1704  s->bits_sent += len << 3;
1705 #endif
1706 
1707  /* Copy uncompressed bytes from the window to next_out. */
1708  if (left) {
1709  if (left > len)
1710  left = len;
1711  zmemcpy(s->strm->next_out, s->window + s->block_start, left);
1712  s->strm->next_out += left;
1713  s->strm->avail_out -= left;
1714  s->strm->total_out += left;
1715  s->block_start += left;
1716  len -= left;
1717  }
1718 
1719  /* Copy uncompressed bytes directly from next_in to next_out, updating
1720  * the check value.
1721  */
1722  if (len) {
1723  read_buf(s->strm, s->strm->next_out, len);
1724  s->strm->next_out += len;
1725  s->strm->avail_out -= len;
1726  s->strm->total_out += len;
1727  }
1728  } while (last == 0);
1729 
1730  /* Update the sliding window with the last s->w_size bytes of the copied
1731  * data, or append all of the copied data to the existing window if less
1732  * than s->w_size bytes were copied. Also update the number of bytes to
1733  * insert in the hash tables, in the event that deflateParams() switches to
1734  * a non-zero compression level.
1735  */
1736  used -= s->strm->avail_in; /* number of input bytes directly copied */
1737  if (used) {
1738  /* If any input was used, then no unused input remains in the window,
1739  * therefore s->block_start == s->strstart.
1740  */
1741  if (used >= s->w_size) { /* supplant the previous history */
1742  s->matches = 2; /* clear hash */
1743  zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);
1744  s->strstart = s->w_size;
1745  }
1746  else {
1747  if (s->window_size - s->strstart <= used) {
1748  /* Slide the window down. */
1749  s->strstart -= s->w_size;
1750  zmemcpy(s->window, s->window + s->w_size, s->strstart);
1751  if (s->matches < 2)
1752  s->matches++; /* add a pending slide_hash() */
1753  }
1754  zmemcpy(s->window + s->strstart, s->strm->next_in - used, used);
1755  s->strstart += used;
1756  }
1757  s->block_start = s->strstart;
1758  s->insert += MIN(used, s->w_size - s->insert);
1759  }
1760  if (s->high_water < s->strstart)
1761  s->high_water = s->strstart;
1762 
1763  /* If the last block was written to next_out, then done. */
1764  if (last)
1765  return finish_done;
1766 
1767  /* If flushing and all input has been consumed, then done. */
1768  if (flush != Z_NO_FLUSH && flush != Z_FINISH &&
1769  s->strm->avail_in == 0 && (long)s->strstart == s->block_start)
1770  return block_done;
1771 
1772  /* Fill the window with any remaining input. */
1773  have = s->window_size - s->strstart - 1;
1774  if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) {
1775  /* Slide the window down. */
1776  s->block_start -= s->w_size;
1777  s->strstart -= s->w_size;
1778  zmemcpy(s->window, s->window + s->w_size, s->strstart);
1779  if (s->matches < 2)
1780  s->matches++; /* add a pending slide_hash() */
1781  have += s->w_size; /* more space now */
1782  }
1783  if (have > s->strm->avail_in)
1784  have = s->strm->avail_in;
1785  if (have) {
1786  read_buf(s->strm, s->window + s->strstart, have);
1787  s->strstart += have;
1788  }
1789  if (s->high_water < s->strstart)
1790  s->high_water = s->strstart;
1791 
1792  /* There was not enough avail_out to write a complete worthy or flushed
1793  * stored block to next_out. Write a stored block to pending instead, if we
1794  * have enough input for a worthy block, or if flushing and there is enough
1795  * room for the remaining input as a stored block in the pending buffer.
1796  */
1797  have = (s->bi_valid + 42) >> 3; /* number of header bytes */
1798  /* maximum stored block length that will fit in pending: */
1799  have = MIN(s->pending_buf_size - have, MAX_STORED);
1800  min_block = MIN(have, s->w_size);
1801  left = s->strstart - s->block_start;
1802  if (left >= min_block ||
1803  ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH &&
1804  s->strm->avail_in == 0 && left <= have)) {
1805  len = MIN(left, have);
1806  last = flush == Z_FINISH && s->strm->avail_in == 0 &&
1807  len == left ? 1 : 0;
1808  _tr_stored_block(s, (charf *)s->window + s->block_start, len, last);
1809  s->block_start += len;
1810  flush_pending(s->strm);
1811  }
1812 
1813  /* We've done all we can with the available input and output. */
1814  return last ? finish_started : need_more;
1815 }
1816 
1817 /* ===========================================================================
1818  * Compress as much as possible from the input stream, return the current
1819  * block state.
1820  * This function does not perform lazy evaluation of matches and inserts
1821  * new strings in the dictionary only for unmatched strings or for short
1822  * matches. It is used only for the fast compression options.
1823  */
1825  deflate_state *s;
1826  int flush;
1827 {
1828  IPos hash_head; /* head of the hash chain */
1829  int bflush; /* set if current block must be flushed */
1830 
1831  for (;;) {
1832  /* Make sure that we always have enough lookahead, except
1833  * at the end of the input file. We need MAX_MATCH bytes
1834  * for the next match, plus MIN_MATCH bytes to insert the
1835  * string following the next match.
1836  */
1837  if (s->lookahead < MIN_LOOKAHEAD) {
1838  fill_window(s);
1839  if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1840  return need_more;
1841  }
1842  if (s->lookahead == 0) break; /* flush the current block */
1843  }
1844 
1845  /* Insert the string window[strstart .. strstart+2] in the
1846  * dictionary, and set hash_head to the head of the hash chain:
1847  */
1848  hash_head = NIL;
1849  if (s->lookahead >= MIN_MATCH) {
1850  INSERT_STRING(s, s->strstart, hash_head);
1851  }
1852 
1853  /* Find the longest match, discarding those <= prev_length.
1854  * At this point we have always match_length < MIN_MATCH
1855  */
1856  if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1857  /* To simplify the code, we prevent matches with the string
1858  * of window index 0 (in particular we have to avoid a match
1859  * of the string with itself at the start of the input file).
1860  */
1861  s->match_length = longest_match (s, hash_head);
1862  /* longest_match() sets match_start */
1863  }
1864  if (s->match_length >= MIN_MATCH) {
1865  check_match(s, s->strstart, s->match_start, s->match_length);
1866 
1867  _tr_tally_dist(s, s->strstart - s->match_start,
1868  s->match_length - MIN_MATCH, bflush);
1869 
1870  s->lookahead -= s->match_length;
1871 
1872  /* Insert new strings in the hash table only if the match length
1873  * is not too large. This saves time but degrades compression.
1874  */
1875 #ifndef FASTEST
1876  if (s->match_length <= s->max_insert_length &&
1877  s->lookahead >= MIN_MATCH) {
1878  s->match_length--; /* string at strstart already in table */
1879  do {
1880  s->strstart++;
1881  INSERT_STRING(s, s->strstart, hash_head);
1882  /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1883  * always MIN_MATCH bytes ahead.
1884  */
1885  } while (--s->match_length != 0);
1886  s->strstart++;
1887  } else
1888 #endif
1889  {
1890  s->strstart += s->match_length;
1891  s->match_length = 0;
1892  s->ins_h = s->window[s->strstart];
1893  UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1894 #if MIN_MATCH != 3
1895  Call UPDATE_HASH() MIN_MATCH-3 more times
1896 #endif
1897  /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1898  * matter since it will be recomputed at next deflate call.
1899  */
1900  }
1901  } else {
1902  /* No match, output a literal byte */
1903  Tracevv((stderr,"%c", s->window[s->strstart]));
1904  _tr_tally_lit (s, s->window[s->strstart], bflush);
1905  s->lookahead--;
1906  s->strstart++;
1907  }
1908  if (bflush) FLUSH_BLOCK(s, 0);
1909  }
1910  s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1911  if (flush == Z_FINISH) {
1912  FLUSH_BLOCK(s, 1);
1913  return finish_done;
1914  }
1915  if (s->last_lit)
1916  FLUSH_BLOCK(s, 0);
1917  return block_done;
1918 }
1919 
1920 #ifndef FASTEST
1921 /* ===========================================================================
1922  * Same as above, but achieves better compression. We use a lazy
1923  * evaluation for matches: a match is finally adopted only if there is
1924  * no better match at the next window position.
1925  */
1927  deflate_state *s;
1928  int flush;
1929 {
1930  IPos hash_head; /* head of hash chain */
1931  int bflush; /* set if current block must be flushed */
1932 
1933  /* Process the input block. */
1934  for (;;) {
1935  /* Make sure that we always have enough lookahead, except
1936  * at the end of the input file. We need MAX_MATCH bytes
1937  * for the next match, plus MIN_MATCH bytes to insert the
1938  * string following the next match.
1939  */
1940  if (s->lookahead < MIN_LOOKAHEAD) {
1941  fill_window(s);
1942  if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1943  return need_more;
1944  }
1945  if (s->lookahead == 0) break; /* flush the current block */
1946  }
1947 
1948  /* Insert the string window[strstart .. strstart+2] in the
1949  * dictionary, and set hash_head to the head of the hash chain:
1950  */
1951  hash_head = NIL;
1952  if (s->lookahead >= MIN_MATCH) {
1953  INSERT_STRING(s, s->strstart, hash_head);
1954  }
1955 
1956  /* Find the longest match, discarding those <= prev_length.
1957  */
1958  s->prev_length = s->match_length, s->prev_match = s->match_start;
1959  s->match_length = MIN_MATCH-1;
1960 
1961  if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1962  s->strstart - hash_head <= MAX_DIST(s)) {
1963  /* To simplify the code, we prevent matches with the string
1964  * of window index 0 (in particular we have to avoid a match
1965  * of the string with itself at the start of the input file).
1966  */
1967  s->match_length = longest_match (s, hash_head);
1968  /* longest_match() sets match_start */
1969 
1970  if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1971 #if TOO_FAR <= 32767
1972  || (s->match_length == MIN_MATCH &&
1973  s->strstart - s->match_start > TOO_FAR)
1974 #endif
1975  )) {
1976 
1977  /* If prev_match is also MIN_MATCH, match_start is garbage
1978  * but we will ignore the current match anyway.
1979  */
1980  s->match_length = MIN_MATCH-1;
1981  }
1982  }
1983  /* If there was a match at the previous step and the current
1984  * match is not better, output the previous match:
1985  */
1986  if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1987  uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1988  /* Do not insert strings in hash table beyond this. */
1989 
1990  check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1991 
1992  _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1993  s->prev_length - MIN_MATCH, bflush);
1994 
1995  /* Insert in hash table all strings up to the end of the match.
1996  * strstart-1 and strstart are already inserted. If there is not
1997  * enough lookahead, the last two strings are not inserted in
1998  * the hash table.
1999  */
2000  s->lookahead -= s->prev_length-1;
2001  s->prev_length -= 2;
2002  do {
2003  if (++s->strstart <= max_insert) {
2004  INSERT_STRING(s, s->strstart, hash_head);
2005  }
2006  } while (--s->prev_length != 0);
2007  s->match_available = 0;
2008  s->match_length = MIN_MATCH-1;
2009  s->strstart++;
2010 
2011  if (bflush) FLUSH_BLOCK(s, 0);
2012 
2013  } else if (s->match_available) {
2014  /* If there was no match at the previous position, output a
2015  * single literal. If there was a match but the current match
2016  * is longer, truncate the previous match to a single literal.
2017  */
2018  Tracevv((stderr,"%c", s->window[s->strstart-1]));
2019  _tr_tally_lit(s, s->window[s->strstart-1], bflush);
2020  if (bflush) {
2021  FLUSH_BLOCK_ONLY(s, 0);
2022  }
2023  s->strstart++;
2024  s->lookahead--;
2025  if (s->strm->avail_out == 0) return need_more;
2026  } else {
2027  /* There is no previous match to compare with, wait for
2028  * the next step to decide.
2029  */
2030  s->match_available = 1;
2031  s->strstart++;
2032  s->lookahead--;
2033  }
2034  }
2035  Assert (flush != Z_NO_FLUSH, "no flush?");
2036  if (s->match_available) {
2037  Tracevv((stderr,"%c", s->window[s->strstart-1]));
2038  _tr_tally_lit(s, s->window[s->strstart-1], bflush);
2039  s->match_available = 0;
2040  }
2041  s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
2042  if (flush == Z_FINISH) {
2043  FLUSH_BLOCK(s, 1);
2044  return finish_done;
2045  }
2046  if (s->last_lit)
2047  FLUSH_BLOCK(s, 0);
2048  return block_done;
2049 }
2050 #endif /* FASTEST */
2051 
2052 /* ===========================================================================
2053  * For Z_RLE, simply look for runs of bytes, generate matches only of distance
2054  * one. Do not maintain a hash table. (It will be regenerated if this run of
2055  * deflate switches away from Z_RLE.)
2056  */
2058  deflate_state *s;
2059  int flush;
2060 {
2061  int bflush; /* set if current block must be flushed */
2062  uInt prev; /* byte at distance one to match */
2063  Bytef *scan, *strend; /* scan goes up to strend for length of run */
2064 
2065  for (;;) {
2066  /* Make sure that we always have enough lookahead, except
2067  * at the end of the input file. We need MAX_MATCH bytes
2068  * for the longest run, plus one for the unrolled loop.
2069  */
2070  if (s->lookahead <= MAX_MATCH) {
2071  fill_window(s);
2072  if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
2073  return need_more;
2074  }
2075  if (s->lookahead == 0) break; /* flush the current block */
2076  }
2077 
2078  /* See how many times the previous byte repeats */
2079  s->match_length = 0;
2080  if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
2081  scan = s->window + s->strstart - 1;
2082  prev = *scan;
2083  if (prev == *++scan && prev == *++scan && prev == *++scan) {
2084  strend = s->window + s->strstart + MAX_MATCH;
2085  do {
2086  } while (prev == *++scan && prev == *++scan &&
2087  prev == *++scan && prev == *++scan &&
2088  prev == *++scan && prev == *++scan &&
2089  prev == *++scan && prev == *++scan &&
2090  scan < strend);
2091  s->match_length = MAX_MATCH - (uInt)(strend - scan);
2092  if (s->match_length > s->lookahead)
2093  s->match_length = s->lookahead;
2094  }
2095  Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
2096  }
2097 
2098  /* Emit match if have run of MIN_MATCH or longer, else emit literal */
2099  if (s->match_length >= MIN_MATCH) {
2100  check_match(s, s->strstart, s->strstart - 1, s->match_length);
2101 
2102  _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
2103 
2104  s->lookahead -= s->match_length;
2105  s->strstart += s->match_length;
2106  s->match_length = 0;
2107  } else {
2108  /* No match, output a literal byte */
2109  Tracevv((stderr,"%c", s->window[s->strstart]));
2110  _tr_tally_lit (s, s->window[s->strstart], bflush);
2111  s->lookahead--;
2112  s->strstart++;
2113  }
2114  if (bflush) FLUSH_BLOCK(s, 0);
2115  }
2116  s->insert = 0;
2117  if (flush == Z_FINISH) {
2118  FLUSH_BLOCK(s, 1);
2119  return finish_done;
2120  }
2121  if (s->last_lit)
2122  FLUSH_BLOCK(s, 0);
2123  return block_done;
2124 }
2125 
2126 /* ===========================================================================
2127  * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
2128  * (It will be regenerated if this run of deflate switches away from Huffman.)
2129  */
2131  deflate_state *s;
2132  int flush;
2133 {
2134  int bflush; /* set if current block must be flushed */
2135 
2136  for (;;) {
2137  /* Make sure that we have a literal to write. */
2138  if (s->lookahead == 0) {
2139  fill_window(s);
2140  if (s->lookahead == 0) {
2141  if (flush == Z_NO_FLUSH)
2142  return need_more;
2143  break; /* flush the current block */
2144  }
2145  }
2146 
2147  /* Output a literal byte */
2148  s->match_length = 0;
2149  Tracevv((stderr,"%c", s->window[s->strstart]));
2150  _tr_tally_lit (s, s->window[s->strstart], bflush);
2151  s->lookahead--;
2152  s->strstart++;
2153  if (bflush) FLUSH_BLOCK(s, 0);
2154  }
2155  s->insert = 0;
2156  if (flush == Z_FINISH) {
2157  FLUSH_BLOCK(s, 1);
2158  return finish_done;
2159  }
2160  if (s->last_lit)
2161  FLUSH_BLOCK(s, 0);
2162  return block_done;
2163 }
Z_MEM_ERROR
#define Z_MEM_ERROR
Definition: zlib.h:183
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Definition: zlib.h:96
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Definition: deflate.h:92
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Definition: deflate.h:142
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Definition: deflate.c:123
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Definition: deflate.h:116
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Definition: deflate.c:73
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Definition: deflate.h:144
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Definition: zlib.h:185
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Definition: deflate.h:111
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Definition: zutil.h:77
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Definition: zlib.h:198
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Definition: deflate.h:161
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Definition: deflate.c:192
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Definition: deflate.h:159
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Definition: deflate.h:147
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Definition: deflate.h:93
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Definition: zconf.h:270
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Definition: zlib.h:81
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Definition: zconf.h:380
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Definition: deflate.c:68
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Definition: deflate.h:119
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Definition: deflate.h:102
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Definition: zlib.h:193
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Definition: deflate.c:652
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Definition: deflate.h:106
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Definition: zconf.h:393
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Definition: zutil.h:262
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Definition: zconf.h:400
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Definition: png.c:2253
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Definition: deflate.h:252
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Definition: deflate.c:122
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Definition: zutil.h:264
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Definition: deflate.c:763
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Definition: zutil.c:149
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Definition: zutil.h:47
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Definition: deflate.c:376
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Definition: deflate.h:23
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Definition: zutil.h:251
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Definition: zlib.h:93
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Definition: deflate.h:154
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Definition: deflate.h:189
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Definition: deflate.h:61
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Definition: deflate.h:117
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Definition: deflate.c:568
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Definition: zlib.h:120
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Definition: deflate.h:143
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