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
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 1.2.8 Copyright 1995-2013 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
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));
79 #ifndef FASTEST
80 local block_state deflate_slow OF((deflate_state *s, int flush));
81 #endif
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 int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
88 #ifdef ASMV
89 void match_init OF((void)); /* asm code initialization */
90 uInt longest_match OF((deflate_state *s, IPos cur_match));
91 #else
92 local uInt longest_match OF((deflate_state *s, IPos cur_match));
93 #endif
94
95 #ifdef DEBUG
96 local void check_match OF((deflate_state *s, IPos start, IPos match,
97 int length));
98 #endif
99
100 /* ===========================================================================
101 * Local data
102 */
103
104 #define NIL 0
105 /* Tail of hash chains */
106
107 #ifndef TOO_FAR
108 # define TOO_FAR 4096
109 #endif
110 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
111
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.
116 */
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 */
121 ush max_chain;
122 compress_func func;
123 } config;
124
125 #ifdef FASTEST
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 */
130 #else
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},
137
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 */
144 #endif
145
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
148 * meaning.
149 */
150
151 #define EQUAL 0
152 /* result of memcmp for equal strings */
153
154 #ifndef NO_DUMMY_DECL
155 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
156 #endif
157
158 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
159 #define RANK(f) (((f) << 1) - ((f) > 4 ? 9 : 0))
160
161 /* ===========================================================================
162 * Update a hash value with the given input byte
163 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
164 * input characters, so that a running hash key can be computed from the
165 * previous key instead of complete recalculation each time.
166 */
167 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
168
169
170 /* ===========================================================================
171 * Insert string str in the dictionary and set match_head to the previous head
172 * of the hash chain (the most recent string with same hash key). Return
173 * the previous length of the hash chain.
174 * If this file is compiled with -DFASTEST, the compression level is forced
175 * to 1, and no hash chains are maintained.
176 * IN assertion: all calls to to INSERT_STRING are made with consecutive
177 * input characters and the first MIN_MATCH bytes of str are valid
178 * (except for the last MIN_MATCH-1 bytes of the input file).
179 */
180 #ifdef FASTEST
181 #define INSERT_STRING(s, str, match_head) \
182 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
183 match_head = s->head[s->ins_h], \
184 s->head[s->ins_h] = (Pos)(str))
185 #else
186 #define INSERT_STRING(s, str, match_head) \
187 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
188 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
189 s->head[s->ins_h] = (Pos)(str))
190 #endif
191
192 /* ===========================================================================
193 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
194 * prev[] will be initialized on the fly.
195 */
196 #define CLEAR_HASH(s) \
197 s->head[s->hash_size-1] = NIL; \
198 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
199
200 /* ========================================================================= */
201 int ZEXPORT deflateInit_(strm, level, version, stream_size)
202 z_streamp strm;
203 int level;
204 const char *version;
205 int stream_size;
206 {
207 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
208 Z_DEFAULT_STRATEGY, version, stream_size);
209 /* To do: ignore strm->next_in if we use it as window */
210 }
211
212 /* ========================================================================= */
213 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
214 version, stream_size)
215 z_streamp strm;
216 int level;
217 int method;
218 int windowBits;
219 int memLevel;
220 int strategy;
221 const char *version;
222 int stream_size;
223 {
224 deflate_state *s;
225 int wrap = 1;
226 static const char my_version[] = ZLIB_VERSION;
227
228 ushf *overlay;
229 /* We overlay pending_buf and d_buf+l_buf. This works since the average
230 * output size for (length,distance) codes is <= 24 bits.
231 */
232
233 if (version == Z_NULL || version[0] != my_version[0] ||
234 stream_size != sizeof(z_stream)) {
235 return Z_VERSION_ERROR;
236 }
237 if (strm == Z_NULL) return Z_STREAM_ERROR;
238
239 strm->msg = Z_NULL;
240 if (strm->zalloc == (alloc_func)0) {
241 #ifdef Z_SOLO
242 return Z_STREAM_ERROR;
243 #else
244 strm->zalloc = zcalloc;
245 strm->opaque = (voidpf)0;
246 #endif
247 }
248 if (strm->zfree == (free_func)0)
249 #ifdef Z_SOLO
250 return Z_STREAM_ERROR;
251 #else
252 strm->zfree = zcfree;
253 #endif
254
255 #ifdef FASTEST
256 if (level != 0) level = 1;
257 #else
258 if (level == Z_DEFAULT_COMPRESSION) level = 6;
259 #endif
260
261 if (windowBits < 0) { /* suppress zlib wrapper */
262 wrap = 0;
263 windowBits = -windowBits;
264 }
265 #ifdef GZIP
266 else if (windowBits > 15) {
267 wrap = 2; /* write gzip wrapper instead */
268 windowBits -= 16;
269 }
270 #endif
271 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
272 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
273 strategy < 0 || strategy > Z_FIXED) {
274 return Z_STREAM_ERROR;
275 }
276 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
277 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
278 if (s == Z_NULL) return Z_MEM_ERROR;
279 strm->state = (struct internal_state FAR *)s;
280 s->strm = strm;
281
282 s->wrap = wrap;
283 s->gzhead = Z_NULL;
284 s->w_bits = windowBits;
285 s->w_size = 1 << s->w_bits;
286 s->w_mask = s->w_size - 1;
287
288 s->hash_bits = memLevel + 7;
289 s->hash_size = 1 << s->hash_bits;
290 s->hash_mask = s->hash_size - 1;
291 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
292
293 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
294 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
295 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
296
297 s->high_water = 0; /* nothing written to s->window yet */
298
299 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
300
301 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
302 s->pending_buf = (uchf *) overlay;
303 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
304
305 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
306 s->pending_buf == Z_NULL) {
307 s->status = FINISH_STATE;
308 strm->msg = ERR_MSG(Z_MEM_ERROR);
309 deflateEnd (strm);
310 return Z_MEM_ERROR;
311 }
312 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
313 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
314
315 s->level = level;
316 s->strategy = strategy;
317 s->method = (Byte)method;
318
319 return deflateReset(strm);
320 }
321
322 /* ========================================================================= */
323 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
324 z_streamp strm;
325 const Bytef *dictionary;
326 uInt dictLength;
327 {
328 deflate_state *s;
329 uInt str, n;
330 int wrap;
331 unsigned avail;
332 z_const unsigned char *next;
333
334 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL)
335 return Z_STREAM_ERROR;
336 s = strm->state;
337 wrap = s->wrap;
338 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
339 return Z_STREAM_ERROR;
340
341 /* when using zlib wrappers, compute Adler-32 for provided dictionary */
342 if (wrap == 1)
343 strm->adler = adler32(strm->adler, dictionary, dictLength);
344 s->wrap = 0; /* avoid computing Adler-32 in read_buf */
345
346 /* if dictionary would fill window, just replace the history */
347 if (dictLength >= s->w_size) {
348 if (wrap == 0) { /* already empty otherwise */
349 CLEAR_HASH(s);
350 s->strstart = 0;
351 s->block_start = 0L;
352 s->insert = 0;
353 }
354 dictionary += dictLength - s->w_size; /* use the tail */
355 dictLength = s->w_size;
356 }
357
358 /* insert dictionary into window and hash */
359 avail = strm->avail_in;
360 next = strm->next_in;
361 strm->avail_in = dictLength;
362 strm->next_in = (z_const Bytef *)dictionary;
363 fill_window(s);
364 while (s->lookahead >= MIN_MATCH) {
365 str = s->strstart;
366 n = s->lookahead - (MIN_MATCH-1);
367 do {
368 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
369 #ifndef FASTEST
370 s->prev[str & s->w_mask] = s->head[s->ins_h];
371 #endif
372 s->head[s->ins_h] = (Pos)str;
373 str++;
374 } while (--n);
375 s->strstart = str;
376 s->lookahead = MIN_MATCH-1;
377 fill_window(s);
378 }
379 s->strstart += s->lookahead;
380 s->block_start = (long)s->strstart;
381 s->insert = s->lookahead;
382 s->lookahead = 0;
383 s->match_length = s->prev_length = MIN_MATCH-1;
384 s->match_available = 0;
385 strm->next_in = next;
386 strm->avail_in = avail;
387 s->wrap = wrap;
388 return Z_OK;
389 }
390
391 /* ========================================================================= */
392 int ZEXPORT deflateResetKeep (strm)
393 z_streamp strm;
394 {
395 deflate_state *s;
396
397 if (strm == Z_NULL || strm->state == Z_NULL ||
398 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
399 return Z_STREAM_ERROR;
400 }
401
402 strm->total_in = strm->total_out = 0;
403 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
404 strm->data_type = Z_UNKNOWN;
405
406 s = (deflate_state *)strm->state;
407 s->pending = 0;
408 s->pending_out = s->pending_buf;
409
410 if (s->wrap < 0) {
411 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
412 }
413 s->status = s->wrap ? INIT_STATE : BUSY_STATE;
414 strm->adler =
415 #ifdef GZIP
416 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
417 #endif
418 adler32(0L, Z_NULL, 0);
419 s->last_flush = Z_NO_FLUSH;
420
421 _tr_init(s);
422
423 return Z_OK;
424 }
425
426 /* ========================================================================= */
427 int ZEXPORT deflateReset (strm)
428 z_streamp strm;
429 {
430 int ret;
431
432 ret = deflateResetKeep(strm);
433 if (ret == Z_OK)
434 lm_init(strm->state);
435 return ret;
436 }
437
438 /* ========================================================================= */
439 int ZEXPORT deflateSetHeader (strm, head)
440 z_streamp strm;
441 gz_headerp head;
442 {
443 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
444 if (strm->state->wrap != 2) return Z_STREAM_ERROR;
445 strm->state->gzhead = head;
446 return Z_OK;
447 }
448
449 /* ========================================================================= */
450 int ZEXPORT deflatePending (strm, pending, bits)
451 unsigned *pending;
452 int *bits;
453 z_streamp strm;
454 {
455 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
456 if (pending != Z_NULL)
457 *pending = strm->state->pending;
458 if (bits != Z_NULL)
459 *bits = strm->state->bi_valid;
460 return Z_OK;
461 }
462
463 /* ========================================================================= */
464 int ZEXPORT deflatePrime (strm, bits, value)
465 z_streamp strm;
466 int bits;
467 int value;
468 {
469 deflate_state *s;
470 int put;
471
472 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
473 s = strm->state;
474 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
475 return Z_BUF_ERROR;
476 do {
477 put = Buf_size - s->bi_valid;
478 if (put > bits)
479 put = bits;
480 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
481 s->bi_valid += put;
482 _tr_flush_bits(s);
483 value >>= put;
484 bits -= put;
485 } while (bits);
486 return Z_OK;
487 }
488
489 /* ========================================================================= */
490 int ZEXPORT deflateParams(strm, level, strategy)
491 z_streamp strm;
492 int level;
493 int strategy;
494 {
495 deflate_state *s;
496 compress_func func;
497 int err = Z_OK;
498
499 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
500 s = strm->state;
501
502 #ifdef FASTEST
503 if (level != 0) level = 1;
504 #else
505 if (level == Z_DEFAULT_COMPRESSION) level = 6;
506 #endif
507 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
508 return Z_STREAM_ERROR;
509 }
510 func = configuration_table[s->level].func;
511
512 if ((strategy != s->strategy || func != configuration_table[level].func) &&
513 strm->total_in != 0) {
514 /* Flush the last buffer: */
515 err = deflate(strm, Z_BLOCK);
516 if (err == Z_BUF_ERROR && s->pending == 0)
517 err = Z_OK;
518 }
519 if (s->level != level) {
520 s->level = level;
521 s->max_lazy_match = configuration_table[level].max_lazy;
522 s->good_match = configuration_table[level].good_length;
523 s->nice_match = configuration_table[level].nice_length;
524 s->max_chain_length = configuration_table[level].max_chain;
525 }
526 s->strategy = strategy;
527 return err;
528 }
529
530 /* ========================================================================= */
531 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
532 z_streamp strm;
533 int good_length;
534 int max_lazy;
535 int nice_length;
536 int max_chain;
537 {
538 deflate_state *s;
539
540 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
541 s = strm->state;
542 s->good_match = good_length;
543 s->max_lazy_match = max_lazy;
544 s->nice_match = nice_length;
545 s->max_chain_length = max_chain;
546 return Z_OK;
547 }
548
549 /* =========================================================================
550 * For the default windowBits of 15 and memLevel of 8, this function returns
551 * a close to exact, as well as small, upper bound on the compressed size.
552 * They are coded as constants here for a reason--if the #define's are
553 * changed, then this function needs to be changed as well. The return
554 * value for 15 and 8 only works for those exact settings.
555 *
556 * For any setting other than those defaults for windowBits and memLevel,
557 * the value returned is a conservative worst case for the maximum expansion
558 * resulting from using fixed blocks instead of stored blocks, which deflate
559 * can emit on compressed data for some combinations of the parameters.
560 *
561 * This function could be more sophisticated to provide closer upper bounds for
562 * every combination of windowBits and memLevel. But even the conservative
563 * upper bound of about 14% expansion does not seem onerous for output buffer
564 * allocation.
565 */
566 uLong ZEXPORT deflateBound(strm, sourceLen)
567 z_streamp strm;
568 uLong sourceLen;
569 {
570 deflate_state *s;
571 uLong complen, wraplen;
572 Bytef *str;
573
574 /* conservative upper bound for compressed data */
575 complen = sourceLen +
576 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
577
578 /* if can't get parameters, return conservative bound plus zlib wrapper */
579 if (strm == Z_NULL || strm->state == Z_NULL)
580 return complen + 6;
581
582 /* compute wrapper length */
583 s = strm->state;
584 switch (s->wrap) {
585 case 0: /* raw deflate */
586 wraplen = 0;
587 break;
588 case 1: /* zlib wrapper */
589 wraplen = 6 + (s->strstart ? 4 : 0);
590 break;
591 case 2: /* gzip wrapper */
592 wraplen = 18;
593 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
594 if (s->gzhead->extra != Z_NULL)
595 wraplen += 2 + s->gzhead->extra_len;
596 str = s->gzhead->name;
597 if (str != Z_NULL)
598 do {
599 wraplen++;
600 } while (*str++);
601 str = s->gzhead->comment;
602 if (str != Z_NULL)
603 do {
604 wraplen++;
605 } while (*str++);
606 if (s->gzhead->hcrc)
607 wraplen += 2;
608 }
609 break;
610 default: /* for compiler happiness */
611 wraplen = 6;
612 }
613
614 /* if not default parameters, return conservative bound */
615 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
616 return complen + wraplen;
617
618 /* default settings: return tight bound for that case */
619 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
620 (sourceLen >> 25) + 13 - 6 + wraplen;
621 }
622
623 /* =========================================================================
624 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
625 * IN assertion: the stream state is correct and there is enough room in
626 * pending_buf.
627 */
628 local void putShortMSB (s, b)
629 deflate_state *s;
630 uInt b;
631 {
632 put_byte(s, (Byte)(b >> 8));
633 put_byte(s, (Byte)(b & 0xff));
634 }
635
636 /* =========================================================================
637 * Flush as much pending output as possible. All deflate() output goes
638 * through this function so some applications may wish to modify it
639 * to avoid allocating a large strm->next_out buffer and copying into it.
640 * (See also read_buf()).
641 */
642 local void flush_pending(strm)
643 z_streamp strm;
644 {
645 unsigned len;
646 deflate_state *s = strm->state;
647
648 _tr_flush_bits(s);
649 len = s->pending;
650 if (len > strm->avail_out) len = strm->avail_out;
651 if (len == 0) return;
652
653 zmemcpy(strm->next_out, s->pending_out, len);
654 strm->next_out += len;
655 s->pending_out += len;
656 strm->total_out += len;
657 strm->avail_out -= len;
658 s->pending -= len;
659 if (s->pending == 0) {
660 s->pending_out = s->pending_buf;
661 }
662 }
663
664 /* ========================================================================= */
665 int ZEXPORT deflate (strm, flush)
666 z_streamp strm;
667 int flush;
668 {
669 int old_flush; /* value of flush param for previous deflate call */
670 deflate_state *s;
671
672 if (strm == Z_NULL || strm->state == Z_NULL ||
673 flush > Z_BLOCK || flush < 0) {
674 return Z_STREAM_ERROR;
675 }
676 s = strm->state;
677
678 if (strm->next_out == Z_NULL ||
679 (strm->next_in == Z_NULL && strm->avail_in != 0) ||
680 (s->status == FINISH_STATE && flush != Z_FINISH)) {
681 ERR_RETURN(strm, Z_STREAM_ERROR);
682 }
683 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
684
685 s->strm = strm; /* just in case */
686 old_flush = s->last_flush;
687 s->last_flush = flush;
688
689 /* Write the header */
690 if (s->status == INIT_STATE) {
691 #ifdef GZIP
692 if (s->wrap == 2) {
693 strm->adler = crc32(0L, Z_NULL, 0);
694 put_byte(s, 31);
695 put_byte(s, 139);
696 put_byte(s, 8);
697 if (s->gzhead == Z_NULL) {
698 put_byte(s, 0);
699 put_byte(s, 0);
700 put_byte(s, 0);
701 put_byte(s, 0);
702 put_byte(s, 0);
703 put_byte(s, s->level == 9 ? 2 :
704 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
705 4 : 0));
706 put_byte(s, OS_CODE);
707 s->status = BUSY_STATE;
708 }
709 else {
710 put_byte(s, (s->gzhead->text ? 1 : 0) +
711 (s->gzhead->hcrc ? 2 : 0) +
712 (s->gzhead->extra == Z_NULL ? 0 : 4) +
713 (s->gzhead->name == Z_NULL ? 0 : 8) +
714 (s->gzhead->comment == Z_NULL ? 0 : 16)
715 );
716 put_byte(s, (Byte)(s->gzhead->time & 0xff));
717 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
718 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
719 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
720 put_byte(s, s->level == 9 ? 2 :
721 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
722 4 : 0));
723 put_byte(s, s->gzhead->os & 0xff);
724 if (s->gzhead->extra != Z_NULL) {
725 put_byte(s, s->gzhead->extra_len & 0xff);
726 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
727 }
728 if (s->gzhead->hcrc)
729 strm->adler = crc32(strm->adler, s->pending_buf,
730 s->pending);
731 s->gzindex = 0;
732 s->status = EXTRA_STATE;
733 }
734 }
735 else
736 #endif
737 {
738 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
739 uInt level_flags;
740
741 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
742 level_flags = 0;
743 else if (s->level < 6)
744 level_flags = 1;
745 else if (s->level == 6)
746 level_flags = 2;
747 else
748 level_flags = 3;
749 header |= (level_flags << 6);
750 if (s->strstart != 0) header |= PRESET_DICT;
751 header += 31 - (header % 31);
752
753 s->status = BUSY_STATE;
754 putShortMSB(s, header);
755
756 /* Save the adler32 of the preset dictionary: */
757 if (s->strstart != 0) {
758 putShortMSB(s, (uInt)(strm->adler >> 16));
759 putShortMSB(s, (uInt)(strm->adler & 0xffff));
760 }
761 strm->adler = adler32(0L, Z_NULL, 0);
762 }
763 }
764 #ifdef GZIP
765 if (s->status == EXTRA_STATE) {
766 if (s->gzhead->extra != Z_NULL) {
767 uInt beg = s->pending; /* start of bytes to update crc */
768
769 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
770 if (s->pending == s->pending_buf_size) {
771 if (s->gzhead->hcrc && s->pending > beg)
772 strm->adler = crc32(strm->adler, s->pending_buf + beg,
773 s->pending - beg);
774 flush_pending(strm);
775 beg = s->pending;
776 if (s->pending == s->pending_buf_size)
777 break;
778 }
779 put_byte(s, s->gzhead->extra[s->gzindex]);
780 s->gzindex++;
781 }
782 if (s->gzhead->hcrc && s->pending > beg)
783 strm->adler = crc32(strm->adler, s->pending_buf + beg,
784 s->pending - beg);
785 if (s->gzindex == s->gzhead->extra_len) {
786 s->gzindex = 0;
787 s->status = NAME_STATE;
788 }
789 }
790 else
791 s->status = NAME_STATE;
792 }
793 if (s->status == NAME_STATE) {
794 if (s->gzhead->name != Z_NULL) {
795 uInt beg = s->pending; /* start of bytes to update crc */
796 int val;
797
798 do {
799 if (s->pending == s->pending_buf_size) {
800 if (s->gzhead->hcrc && s->pending > beg)
801 strm->adler = crc32(strm->adler, s->pending_buf + beg,
802 s->pending - beg);
803 flush_pending(strm);
804 beg = s->pending;
805 if (s->pending == s->pending_buf_size) {
806 val = 1;
807 break;
808 }
809 }
810 val = s->gzhead->name[s->gzindex++];
811 put_byte(s, val);
812 } while (val != 0);
813 if (s->gzhead->hcrc && s->pending > beg)
814 strm->adler = crc32(strm->adler, s->pending_buf + beg,
815 s->pending - beg);
816 if (val == 0) {
817 s->gzindex = 0;
818 s->status = COMMENT_STATE;
819 }
820 }
821 else
822 s->status = COMMENT_STATE;
823 }
824 if (s->status == COMMENT_STATE) {
825 if (s->gzhead->comment != Z_NULL) {
826 uInt beg = s->pending; /* start of bytes to update crc */
827 int val;
828
829 do {
830 if (s->pending == s->pending_buf_size) {
831 if (s->gzhead->hcrc && s->pending > beg)
832 strm->adler = crc32(strm->adler, s->pending_buf + beg,
833 s->pending - beg);
834 flush_pending(strm);
835 beg = s->pending;
836 if (s->pending == s->pending_buf_size) {
837 val = 1;
838 break;
839 }
840 }
841 val = s->gzhead->comment[s->gzindex++];
842 put_byte(s, val);
843 } while (val != 0);
844 if (s->gzhead->hcrc && s->pending > beg)
845 strm->adler = crc32(strm->adler, s->pending_buf + beg,
846 s->pending - beg);
847 if (val == 0)
848 s->status = HCRC_STATE;
849 }
850 else
851 s->status = HCRC_STATE;
852 }
853 if (s->status == HCRC_STATE) {
854 if (s->gzhead->hcrc) {
855 if (s->pending + 2 > s->pending_buf_size)
856 flush_pending(strm);
857 if (s->pending + 2 <= s->pending_buf_size) {
858 put_byte(s, (Byte)(strm->adler & 0xff));
859 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
860 strm->adler = crc32(0L, Z_NULL, 0);
861 s->status = BUSY_STATE;
862 }
863 }
864 else
865 s->status = BUSY_STATE;
866 }
867 #endif
868
869 /* Flush as much pending output as possible */
870 if (s->pending != 0) {
871 flush_pending(strm);
872 if (strm->avail_out == 0) {
873 /* Since avail_out is 0, deflate will be called again with
874 * more output space, but possibly with both pending and
875 * avail_in equal to zero. There won't be anything to do,
876 * but this is not an error situation so make sure we
877 * return OK instead of BUF_ERROR at next call of deflate:
878 */
879 s->last_flush = -1;
880 return Z_OK;
881 }
882
883 /* Make sure there is something to do and avoid duplicate consecutive
884 * flushes. For repeated and useless calls with Z_FINISH, we keep
885 * returning Z_STREAM_END instead of Z_BUF_ERROR.
886 */
887 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
888 flush != Z_FINISH) {
889 ERR_RETURN(strm, Z_BUF_ERROR);
890 }
891
892 /* User must not provide more input after the first FINISH: */
893 if (s->status == FINISH_STATE && strm->avail_in != 0) {
894 ERR_RETURN(strm, Z_BUF_ERROR);
895 }
896
897 /* Start a new block or continue the current one.
898 */
899 if (strm->avail_in != 0 || s->lookahead != 0 ||
900 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
901 block_state bstate;
902
903 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
904 (s->strategy == Z_RLE ? deflate_rle(s, flush) :
905 (*(configuration_table[s->level].func))(s, flush));
906
907 if (bstate == finish_started || bstate == finish_done) {
908 s->status = FINISH_STATE;
909 }
910 if (bstate == need_more || bstate == finish_started) {
911 if (strm->avail_out == 0) {
912 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
913 }
914 return Z_OK;
915 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
916 * of deflate should use the same flush parameter to make sure
917 * that the flush is complete. So we don't have to output an
918 * empty block here, this will be done at next call. This also
919 * ensures that for a very small output buffer, we emit at most
920 * one empty block.
921 */
922 }
923 if (bstate == block_done) {
924 if (flush == Z_PARTIAL_FLUSH) {
925 _tr_align(s);
926 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
927 _tr_stored_block(s, (char*)0, 0L, 0);
928 /* For a full flush, this empty block will be recognized
929 * as a special marker by inflate_sync().
930 */
931 if (flush == Z_FULL_FLUSH) {
932 CLEAR_HASH(s); /* forget history */
933 if (s->lookahead == 0) {
934 s->strstart = 0;
935 s->block_start = 0L;
936 s->insert = 0;
937 }
938 }
939 }
940 flush_pending(strm);
941 if (strm->avail_out == 0) {
942 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
943 return Z_OK;
944 }
945 }
946 }
947 Assert(strm->avail_out > 0, "bug2");
948
949 if (flush != Z_FINISH) return Z_OK;
950 if (s->wrap <= 0) return Z_STREAM_END;
951
952 /* Write the trailer */
953 #ifdef GZIP
954 if (s->wrap == 2) {
955 put_byte(s, (Byte)(strm->adler & 0xff));
956 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
957 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
958 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
959 put_byte(s, (Byte)(strm->total_in & 0xff));
960 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
961 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
962 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
963 }
964 else
965 #endif
966 {
967 putShortMSB(s, (uInt)(strm->adler >> 16));
968 putShortMSB(s, (uInt)(strm->adler & 0xffff));
969 }
970 flush_pending(strm);
971 /* If avail_out is zero, the application will call deflate again
972 * to flush the rest.
973 */
974 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
975 return s->pending != 0 ? Z_OK : Z_STREAM_END;
976 }
977
978 /* ========================================================================= */
979 int ZEXPORT deflateEnd (strm)
980 z_streamp strm;
981 {
982 int status;
983
984 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
985
986 status = strm->state->status;
987 if (status != INIT_STATE &&
988 status != EXTRA_STATE &&
989 status != NAME_STATE &&
990 status != COMMENT_STATE &&
991 status != HCRC_STATE &&
992 status != BUSY_STATE &&
993 status != FINISH_STATE) {
994 return Z_STREAM_ERROR;
995 }
996
997 /* Deallocate in reverse order of allocations: */
998 TRY_FREE(strm, strm->state->pending_buf);
999 TRY_FREE(strm, strm->state->head);
1000 TRY_FREE(strm, strm->state->prev);
1001 TRY_FREE(strm, strm->state->window);
1002
1003 ZFREE(strm, strm->state);
1004 strm->state = Z_NULL;
1005
1006 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1007 }
1008
1009 /* =========================================================================
1010 * Copy the source state to the destination state.
1011 * To simplify the source, this is not supported for 16-bit MSDOS (which
1012 * doesn't have enough memory anyway to duplicate compression states).
1013 */
1014 int ZEXPORT deflateCopy (dest, source)
1015 z_streamp dest;
1016 z_streamp source;
1017 {
1018 #ifdef MAXSEG_64K
1019 return Z_STREAM_ERROR;
1020 #else
1021 deflate_state *ds;
1022 deflate_state *ss;
1023 ushf *overlay;
1024
1025
1026 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
1027 return Z_STREAM_ERROR;
1028 }
1029
1030 ss = source->state;
1031
1032 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1033
1034 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1035 if (ds == Z_NULL) return Z_MEM_ERROR;
1036 dest->state = (struct internal_state FAR *) ds;
1037 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1038 ds->strm = dest;
1039
1040 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1041 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1042 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1043 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1044 ds->pending_buf = (uchf *) overlay;
1045
1046 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1047 ds->pending_buf == Z_NULL) {
1048 deflateEnd (dest);
1049 return Z_MEM_ERROR;
1050 }
1051 /* following zmemcpy do not work for 16-bit MSDOS */
1052 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1053 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1054 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1055 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1056
1057 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1058 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1059 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1060
1061 ds->l_desc.dyn_tree = ds->dyn_ltree;
1062 ds->d_desc.dyn_tree = ds->dyn_dtree;
1063 ds->bl_desc.dyn_tree = ds->bl_tree;
1064
1065 return Z_OK;
1066 #endif /* MAXSEG_64K */
1067 }
1068
1069 /* ===========================================================================
1070 * Read a new buffer from the current input stream, update the adler32
1071 * and total number of bytes read. All deflate() input goes through
1072 * this function so some applications may wish to modify it to avoid
1073 * allocating a large strm->next_in buffer and copying from it.
1074 * (See also flush_pending()).
1075 */
1076 local int read_buf(strm, buf, size)
1077 z_streamp strm;
1078 Bytef *buf;
1079 unsigned size;
1080 {
1081 unsigned len = strm->avail_in;
1082
1083 if (len > size) len = size;
1084 if (len == 0) return 0;
1085
1086 strm->avail_in -= len;
1087
1088 zmemcpy(buf, strm->next_in, len);
1089 if (strm->state->wrap == 1) {
1090 strm->adler = adler32(strm->adler, buf, len);
1091 }
1092 #ifdef GZIP
1093 else if (strm->state->wrap == 2) {
1094 strm->adler = crc32(strm->adler, buf, len);
1095 }
1096 #endif
1097 strm->next_in += len;
1098 strm->total_in += len;
1099
1100 return (int)len;
1101 }
1102
1103 /* ===========================================================================
1104 * Initialize the "longest match" routines for a new zlib stream
1105 */
1106 local void lm_init (s)
1107 deflate_state *s;
1108 {
1109 s->window_size = (ulg)2L*s->w_size;
1110
1111 CLEAR_HASH(s);
1112
1113 /* Set the default configuration parameters:
1114 */
1115 s->max_lazy_match = configuration_table[s->level].max_lazy;
1116 s->good_match = configuration_table[s->level].good_length;
1117 s->nice_match = configuration_table[s->level].nice_length;
1118 s->max_chain_length = configuration_table[s->level].max_chain;
1119
1120 s->strstart = 0;
1121 s->block_start = 0L;
1122 s->lookahead = 0;
1123 s->insert = 0;
1124 s->match_length = s->prev_length = MIN_MATCH-1;
1125 s->match_available = 0;
1126 s->ins_h = 0;
1127 #ifndef FASTEST
1128 #ifdef ASMV
1129 match_init(); /* initialize the asm code */
1130 #endif
1131 #endif
1132 }
1133
1134 #ifndef FASTEST
1135 /* ===========================================================================
1136 * Set match_start to the longest match starting at the given string and
1137 * return its length. Matches shorter or equal to prev_length are discarded,
1138 * in which case the result is equal to prev_length and match_start is
1139 * garbage.
1140 * IN assertions: cur_match is the head of the hash chain for the current
1141 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1142 * OUT assertion: the match length is not greater than s->lookahead.
1143 */
1144 #ifndef ASMV
1145 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1146 * match.S. The code will be functionally equivalent.
1147 */
1148 local uInt longest_match(s, cur_match)
1149 deflate_state *s;
1150 IPos cur_match; /* current match */
1151 {
1152 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1153 register Bytef *scan = s->window + s->strstart; /* current string */
1154 register Bytef *match; /* matched string */
1155 register int len; /* length of current match */
1156 int best_len = s->prev_length; /* best match length so far */
1157 int nice_match = s->nice_match; /* stop if match long enough */
1158 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1159 s->strstart - (IPos)MAX_DIST(s) : NIL;
1160 /* Stop when cur_match becomes <= limit. To simplify the code,
1161 * we prevent matches with the string of window index 0.
1162 */
1163 Posf *prev = s->prev;
1164 uInt wmask = s->w_mask;
1165
1166 #ifdef UNALIGNED_OK
1167 /* Compare two bytes at a time. Note: this is not always beneficial.
1168 * Try with and without -DUNALIGNED_OK to check.
1169 */
1170 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1171 register ush scan_start = *(ushf*)scan;
1172 register ush scan_end = *(ushf*)(scan+best_len-1);
1173 #else
1174 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1175 register Byte scan_end1 = scan[best_len-1];
1176 register Byte scan_end = scan[best_len];
1177 #endif
1178
1179 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1180 * It is easy to get rid of this optimization if necessary.
1181 */
1182 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1183
1184 /* Do not waste too much time if we already have a good match: */
1185 if (s->prev_length >= s->good_match) {
1186 chain_length >>= 2;
1187 }
1188 /* Do not look for matches beyond the end of the input. This is necessary
1189 * to make deflate deterministic.
1190 */
1191 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1192
1193 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1194
1195 do {
1196 Assert(cur_match < s->strstart, "no future");
1197 match = s->window + cur_match;
1198
1199 /* Skip to next match if the match length cannot increase
1200 * or if the match length is less than 2. Note that the checks below
1201 * for insufficient lookahead only occur occasionally for performance
1202 * reasons. Therefore uninitialized memory will be accessed, and
1203 * conditional jumps will be made that depend on those values.
1204 * However the length of the match is limited to the lookahead, so
1205 * the output of deflate is not affected by the uninitialized values.
1206 */
1207 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1208 /* This code assumes sizeof(unsigned short) == 2. Do not use
1209 * UNALIGNED_OK if your compiler uses a different size.
1210 */
1211 if (*(ushf*)(match+best_len-1) != scan_end ||
1212 *(ushf*)match != scan_start) continue;
1213
1214 /* It is not necessary to compare scan[2] and match[2] since they are
1215 * always equal when the other bytes match, given that the hash keys
1216 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1217 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1218 * lookahead only every 4th comparison; the 128th check will be made
1219 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1220 * necessary to put more guard bytes at the end of the window, or
1221 * to check more often for insufficient lookahead.
1222 */
1223 Assert(scan[2] == match[2], "scan[2]?");
1224 scan++, match++;
1225 do {
1226 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1227 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1228 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1229 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1230 scan < strend);
1231 /* The funny "do {}" generates better code on most compilers */
1232
1233 /* Here, scan <= window+strstart+257 */
1234 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1235 if (*scan == *match) scan++;
1236
1237 len = (MAX_MATCH - 1) - (int)(strend-scan);
1238 scan = strend - (MAX_MATCH-1);
1239
1240 #else /* UNALIGNED_OK */
1241
1242 if (match[best_len] != scan_end ||
1243 match[best_len-1] != scan_end1 ||
1244 *match != *scan ||
1245 *++match != scan[1]) continue;
1246
1247 /* The check at best_len-1 can be removed because it will be made
1248 * again later. (This heuristic is not always a win.)
1249 * It is not necessary to compare scan[2] and match[2] since they
1250 * are always equal when the other bytes match, given that
1251 * the hash keys are equal and that HASH_BITS >= 8.
1252 */
1253 scan += 2, match++;
1254 Assert(*scan == *match, "match[2]?");
1255
1256 /* We check for insufficient lookahead only every 8th comparison;
1257 * the 256th check will be made at strstart+258.
1258 */
1259 do {
1260 } while (*++scan == *++match && *++scan == *++match &&
1261 *++scan == *++match && *++scan == *++match &&
1262 *++scan == *++match && *++scan == *++match &&
1263 *++scan == *++match && *++scan == *++match &&
1264 scan < strend);
1265
1266 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1267
1268 len = MAX_MATCH - (int)(strend - scan);
1269 scan = strend - MAX_MATCH;
1270
1271 #endif /* UNALIGNED_OK */
1272
1273 if (len > best_len) {
1274 s->match_start = cur_match;
1275 best_len = len;
1276 if (len >= nice_match) break;
1277 #ifdef UNALIGNED_OK
1278 scan_end = *(ushf*)(scan+best_len-1);
1279 #else
1280 scan_end1 = scan[best_len-1];
1281 scan_end = scan[best_len];
1282 #endif
1283 }
1284 } while ((cur_match = prev[cur_match & wmask]) > limit
1285 && --chain_length != 0);
1286
1287 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1288 return s->lookahead;
1289 }
1290 #endif /* ASMV */
1291
1292 #else /* FASTEST */
1293
1294 /* ---------------------------------------------------------------------------
1295 * Optimized version for FASTEST only
1296 */
1297 local uInt longest_match(s, cur_match)
1298 deflate_state *s;
1299 IPos cur_match; /* current match */
1300 {
1301 register Bytef *scan = s->window + s->strstart; /* current string */
1302 register Bytef *match; /* matched string */
1303 register int len; /* length of current match */
1304 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1305
1306 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1307 * It is easy to get rid of this optimization if necessary.
1308 */
1309 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1310
1311 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1312
1313 Assert(cur_match < s->strstart, "no future");
1314
1315 match = s->window + cur_match;
1316
1317 /* Return failure if the match length is less than 2:
1318 */
1319 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1320
1321 /* The check at best_len-1 can be removed because it will be made
1322 * again later. (This heuristic is not always a win.)
1323 * It is not necessary to compare scan[2] and match[2] since they
1324 * are always equal when the other bytes match, given that
1325 * the hash keys are equal and that HASH_BITS >= 8.
1326 */
1327 scan += 2, match += 2;
1328 Assert(*scan == *match, "match[2]?");
1329
1330 /* We check for insufficient lookahead only every 8th comparison;
1331 * the 256th check will be made at strstart+258.
1332 */
1333 do {
1334 } while (*++scan == *++match && *++scan == *++match &&
1335 *++scan == *++match && *++scan == *++match &&
1336 *++scan == *++match && *++scan == *++match &&
1337 *++scan == *++match && *++scan == *++match &&
1338 scan < strend);
1339
1340 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1341
1342 len = MAX_MATCH - (int)(strend - scan);
1343
1344 if (len < MIN_MATCH) return MIN_MATCH - 1;
1345
1346 s->match_start = cur_match;
1347 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1348 }
1349
1350 #endif /* FASTEST */
1351
1352 #ifdef DEBUG
1353 /* ===========================================================================
1354 * Check that the match at match_start is indeed a match.
1355 */
1356 local void check_match(s, start, match, length)
1357 deflate_state *s;
1358 IPos start, match;
1359 int length;
1360 {
1361 /* check that the match is indeed a match */
1362 if (zmemcmp(s->window + match,
1363 s->window + start, length) != EQUAL) {
1364 fprintf(stderr, " start %u, match %u, length %d\n",
1365 start, match, length);
1366 do {
1367 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1368 } while (--length != 0);
1369 z_error("invalid match");
1370 }
1371 if (z_verbose > 1) {
1372 fprintf(stderr,"\\[%d,%d]", start-match, length);
1373 do { putc(s->window[start++], stderr); } while (--length != 0);
1374 }
1375 }
1376 #else
1377 # define check_match(s, start, match, length)
1378 #endif /* DEBUG */
1379
1380 /* ===========================================================================
1381 * Fill the window when the lookahead becomes insufficient.
1382 * Updates strstart and lookahead.
1383 *
1384 * IN assertion: lookahead < MIN_LOOKAHEAD
1385 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1386 * At least one byte has been read, or avail_in == 0; reads are
1387 * performed for at least two bytes (required for the zip translate_eol
1388 * option -- not supported here).
1389 */
1390 local void fill_window(s)
1391 deflate_state *s;
1392 {
1393 register unsigned n, m;
1394 register Posf *p;
1395 unsigned more; /* Amount of free space at the end of the window. */
1396 uInt wsize = s->w_size;
1397
1398 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1399
1400 do {
1401 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1402
1403 /* Deal with !@#$% 64K limit: */
1404 if (sizeof(int) <= 2) {
1405 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1406 more = wsize;
1407
1408 } else if (more == (unsigned)(-1)) {
1409 /* Very unlikely, but possible on 16 bit machine if
1410 * strstart == 0 && lookahead == 1 (input done a byte at time)
1411 */
1412 more--;
1413 }
1414 }
1415
1416 /* If the window is almost full and there is insufficient lookahead,
1417 * move the upper half to the lower one to make room in the upper half.
1418 */
1419 if (s->strstart >= wsize+MAX_DIST(s)) {
1420
1421 zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1422 s->match_start -= wsize;
1423 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1424 s->block_start -= (long) wsize;
1425
1426 /* Slide the hash table (could be avoided with 32 bit values
1427 at the expense of memory usage). We slide even when level == 0
1428 to keep the hash table consistent if we switch back to level > 0
1429 later. (Using level 0 permanently is not an optimal usage of
1430 zlib, so we don't care about this pathological case.)
1431 */
1432 n = s->hash_size;
1433 p = &s->head[n];
1434 do {
1435 m = *--p;
1436 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1437 } while (--n);
1438
1439 n = wsize;
1440 #ifndef FASTEST
1441 p = &s->prev[n];
1442 do {
1443 m = *--p;
1444 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1445 /* If n is not on any hash chain, prev[n] is garbage but
1446 * its value will never be used.
1447 */
1448 } while (--n);
1449 #endif
1450 more += wsize;
1451 }
1452 if (s->strm->avail_in == 0) break;
1453
1454 /* If there was no sliding:
1455 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1456 * more == window_size - lookahead - strstart
1457 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1458 * => more >= window_size - 2*WSIZE + 2
1459 * In the BIG_MEM or MMAP case (not yet supported),
1460 * window_size == input_size + MIN_LOOKAHEAD &&
1461 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1462 * Otherwise, window_size == 2*WSIZE so more >= 2.
1463 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1464 */
1465 Assert(more >= 2, "more < 2");
1466
1467 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1468 s->lookahead += n;
1469
1470 /* Initialize the hash value now that we have some input: */
1471 if (s->lookahead + s->insert >= MIN_MATCH) {
1472 uInt str = s->strstart - s->insert;
1473 s->ins_h = s->window[str];
1474 UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1475 #if MIN_MATCH != 3
1476 Call UPDATE_HASH() MIN_MATCH-3 more times
1477 #endif
1478 while (s->insert) {
1479 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1480 #ifndef FASTEST
1481 s->prev[str & s->w_mask] = s->head[s->ins_h];
1482 #endif
1483 s->head[s->ins_h] = (Pos)str;
1484 str++;
1485 s->insert--;
1486 if (s->lookahead + s->insert < MIN_MATCH)
1487 break;
1488 }
1489 }
1490 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1491 * but this is not important since only literal bytes will be emitted.
1492 */
1493
1494 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1495
1496 /* If the WIN_INIT bytes after the end of the current data have never been
1497 * written, then zero those bytes in order to avoid memory check reports of
1498 * the use of uninitialized (or uninitialised as Julian writes) bytes by
1499 * the longest match routines. Update the high water mark for the next
1500 * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1501 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1502 */
1503 if (s->high_water < s->window_size) {
1504 ulg curr = s->strstart + (ulg)(s->lookahead);
1505 ulg init;
1506
1507 if (s->high_water < curr) {
1508 /* Previous high water mark below current data -- zero WIN_INIT
1509 * bytes or up to end of window, whichever is less.
1510 */
1511 init = s->window_size - curr;
1512 if (init > WIN_INIT)
1513 init = WIN_INIT;
1514 zmemzero(s->window + curr, (unsigned)init);
1515 s->high_water = curr + init;
1516 }
1517 else if (s->high_water < (ulg)curr + WIN_INIT) {
1518 /* High water mark at or above current data, but below current data
1519 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1520 * to end of window, whichever is less.
1521 */
1522 init = (ulg)curr + WIN_INIT - s->high_water;
1523 if (init > s->window_size - s->high_water)
1524 init = s->window_size - s->high_water;
1525 zmemzero(s->window + s->high_water, (unsigned)init);
1526 s->high_water += init;
1527 }
1528 }
1529
1530 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1531 "not enough room for search");
1532 }
1533
1534 /* ===========================================================================
1535 * Flush the current block, with given end-of-file flag.
1536 * IN assertion: strstart is set to the end of the current match.
1537 */
1538 #define FLUSH_BLOCK_ONLY(s, last) { \
1539 _tr_flush_block(s, (s->block_start >= 0L ? \
1540 (charf *)&s->window[(unsigned)s->block_start] : \
1541 (charf *)Z_NULL), \
1542 (ulg)((long)s->strstart - s->block_start), \
1543 (last)); \
1544 s->block_start = s->strstart; \
1545 flush_pending(s->strm); \
1546 Tracev((stderr,"[FLUSH]")); \
1547 }
1548
1549 /* Same but force premature exit if necessary. */
1550 #define FLUSH_BLOCK(s, last) { \
1551 FLUSH_BLOCK_ONLY(s, last); \
1552 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1553 }
1554
1555 /* ===========================================================================
1556 * Copy without compression as much as possible from the input stream, return
1557 * the current block state.
1558 * This function does not insert new strings in the dictionary since
1559 * uncompressible data is probably not useful. This function is used
1560 * only for the level=0 compression option.
1561 * NOTE: this function should be optimized to avoid extra copying from
1562 * window to pending_buf.
1563 */
1564 local block_state deflate_stored(s, flush)
1565 deflate_state *s;
1566 int flush;
1567 {
1568 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1569 * to pending_buf_size, and each stored block has a 5 byte header:
1570 */
1571 ulg max_block_size = 0xffff;
1572 ulg max_start;
1573
1574 if (max_block_size > s->pending_buf_size - 5) {
1575 max_block_size = s->pending_buf_size - 5;
1576 }
1577
1578 /* Copy as much as possible from input to output: */
1579 for (;;) {
1580 /* Fill the window as much as possible: */
1581 if (s->lookahead <= 1) {
1582
1583 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1584 s->block_start >= (long)s->w_size, "slide too late");
1585
1586 fill_window(s);
1587 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1588
1589 if (s->lookahead == 0) break; /* flush the current block */
1590 }
1591 Assert(s->block_start >= 0L, "block gone");
1592
1593 s->strstart += s->lookahead;
1594 s->lookahead = 0;
1595
1596 /* Emit a stored block if pending_buf will be full: */
1597 max_start = s->block_start + max_block_size;
1598 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1599 /* strstart == 0 is possible when wraparound on 16-bit machine */
1600 s->lookahead = (uInt)(s->strstart - max_start);
1601 s->strstart = (uInt)max_start;
1602 FLUSH_BLOCK(s, 0);
1603 }
1604 /* Flush if we may have to slide, otherwise block_start may become
1605 * negative and the data will be gone:
1606 */
1607 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1608 FLUSH_BLOCK(s, 0);
1609 }
1610 }
1611 s->insert = 0;
1612 if (flush == Z_FINISH) {
1613 FLUSH_BLOCK(s, 1);
1614 return finish_done;
1615 }
1616 if ((long)s->strstart > s->block_start)
1617 FLUSH_BLOCK(s, 0);
1618 return block_done;
1619 }
1620
1621 /* ===========================================================================
1622 * Compress as much as possible from the input stream, return the current
1623 * block state.
1624 * This function does not perform lazy evaluation of matches and inserts
1625 * new strings in the dictionary only for unmatched strings or for short
1626 * matches. It is used only for the fast compression options.
1627 */
1628 local block_state deflate_fast(s, flush)
1629 deflate_state *s;
1630 int flush;
1631 {
1632 IPos hash_head; /* head of the hash chain */
1633 int bflush; /* set if current block must be flushed */
1634
1635 for (;;) {
1636 /* Make sure that we always have enough lookahead, except
1637 * at the end of the input file. We need MAX_MATCH bytes
1638 * for the next match, plus MIN_MATCH bytes to insert the
1639 * string following the next match.
1640 */
1641 if (s->lookahead < MIN_LOOKAHEAD) {
1642 fill_window(s);
1643 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1644 return need_more;
1645 }
1646 if (s->lookahead == 0) break; /* flush the current block */
1647 }
1648
1649 /* Insert the string window[strstart .. strstart+2] in the
1650 * dictionary, and set hash_head to the head of the hash chain:
1651 */
1652 hash_head = NIL;
1653 if (s->lookahead >= MIN_MATCH) {
1654 INSERT_STRING(s, s->strstart, hash_head);
1655 }
1656
1657 /* Find the longest match, discarding those <= prev_length.
1658 * At this point we have always match_length < MIN_MATCH
1659 */
1660 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1661 /* To simplify the code, we prevent matches with the string
1662 * of window index 0 (in particular we have to avoid a match
1663 * of the string with itself at the start of the input file).
1664 */
1665 s->match_length = longest_match (s, hash_head);
1666 /* longest_match() sets match_start */
1667 }
1668 if (s->match_length >= MIN_MATCH) {
1669 check_match(s, s->strstart, s->match_start, s->match_length);
1670
1671 _tr_tally_dist(s, s->strstart - s->match_start,
1672 s->match_length - MIN_MATCH, bflush);
1673
1674 s->lookahead -= s->match_length;
1675
1676 /* Insert new strings in the hash table only if the match length
1677 * is not too large. This saves time but degrades compression.
1678 */
1679 #ifndef FASTEST
1680 if (s->match_length <= s->max_insert_length &&
1681 s->lookahead >= MIN_MATCH) {
1682 s->match_length--; /* string at strstart already in table */
1683 do {
1684 s->strstart++;
1685 INSERT_STRING(s, s->strstart, hash_head);
1686 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1687 * always MIN_MATCH bytes ahead.
1688 */
1689 } while (--s->match_length != 0);
1690 s->strstart++;
1691 } else
1692 #endif
1693 {
1694 s->strstart += s->match_length;
1695 s->match_length = 0;
1696 s->ins_h = s->window[s->strstart];
1697 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1698 #if MIN_MATCH != 3
1699 Call UPDATE_HASH() MIN_MATCH-3 more times
1700 #endif
1701 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1702 * matter since it will be recomputed at next deflate call.
1703 */
1704 }
1705 } else {
1706 /* No match, output a literal byte */
1707 Tracevv((stderr,"%c", s->window[s->strstart]));
1708 _tr_tally_lit (s, s->window[s->strstart], bflush);
1709 s->lookahead--;
1710 s->strstart++;
1711 }
1712 if (bflush) FLUSH_BLOCK(s, 0);
1713 }
1714 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1715 if (flush == Z_FINISH) {
1716 FLUSH_BLOCK(s, 1);
1717 return finish_done;
1718 }
1719 if (s->last_lit)
1720 FLUSH_BLOCK(s, 0);
1721 return block_done;
1722 }
1723
1724 #ifndef FASTEST
1725 /* ===========================================================================
1726 * Same as above, but achieves better compression. We use a lazy
1727 * evaluation for matches: a match is finally adopted only if there is
1728 * no better match at the next window position.
1729 */
1730 local block_state deflate_slow(s, flush)
1731 deflate_state *s;
1732 int flush;
1733 {
1734 IPos hash_head; /* head of hash chain */
1735 int bflush; /* set if current block must be flushed */
1736
1737 /* Process the input block. */
1738 for (;;) {
1739 /* Make sure that we always have enough lookahead, except
1740 * at the end of the input file. We need MAX_MATCH bytes
1741 * for the next match, plus MIN_MATCH bytes to insert the
1742 * string following the next match.
1743 */
1744 if (s->lookahead < MIN_LOOKAHEAD) {
1745 fill_window(s);
1746 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1747 return need_more;
1748 }
1749 if (s->lookahead == 0) break; /* flush the current block */
1750 }
1751
1752 /* Insert the string window[strstart .. strstart+2] in the
1753 * dictionary, and set hash_head to the head of the hash chain:
1754 */
1755 hash_head = NIL;
1756 if (s->lookahead >= MIN_MATCH) {
1757 INSERT_STRING(s, s->strstart, hash_head);
1758 }
1759
1760 /* Find the longest match, discarding those <= prev_length.
1761 */
1762 s->prev_length = s->match_length, s->prev_match = s->match_start;
1763 s->match_length = MIN_MATCH-1;
1764
1765 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1766 s->strstart - hash_head <= MAX_DIST(s)) {
1767 /* To simplify the code, we prevent matches with the string
1768 * of window index 0 (in particular we have to avoid a match
1769 * of the string with itself at the start of the input file).
1770 */
1771 s->match_length = longest_match (s, hash_head);
1772 /* longest_match() sets match_start */
1773
1774 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1775 #if TOO_FAR <= 32767
1776 || (s->match_length == MIN_MATCH &&
1777 s->strstart - s->match_start > TOO_FAR)
1778 #endif
1779 )) {
1780
1781 /* If prev_match is also MIN_MATCH, match_start is garbage
1782 * but we will ignore the current match anyway.
1783 */
1784 s->match_length = MIN_MATCH-1;
1785 }
1786 }
1787 /* If there was a match at the previous step and the current
1788 * match is not better, output the previous match:
1789 */
1790 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1791 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1792 /* Do not insert strings in hash table beyond this. */
1793
1794 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1795
1796 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1797 s->prev_length - MIN_MATCH, bflush);
1798
1799 /* Insert in hash table all strings up to the end of the match.
1800 * strstart-1 and strstart are already inserted. If there is not
1801 * enough lookahead, the last two strings are not inserted in
1802 * the hash table.
1803 */
1804 s->lookahead -= s->prev_length-1;
1805 s->prev_length -= 2;
1806 do {
1807 if (++s->strstart <= max_insert) {
1808 INSERT_STRING(s, s->strstart, hash_head);
1809 }
1810 } while (--s->prev_length != 0);
1811 s->match_available = 0;
1812 s->match_length = MIN_MATCH-1;
1813 s->strstart++;
1814
1815 if (bflush) FLUSH_BLOCK(s, 0);
1816
1817 } else if (s->match_available) {
1818 /* If there was no match at the previous position, output a
1819 * single literal. If there was a match but the current match
1820 * is longer, truncate the previous match to a single literal.
1821 */
1822 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1823 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1824 if (bflush) {
1825 FLUSH_BLOCK_ONLY(s, 0);
1826 }
1827 s->strstart++;
1828 s->lookahead--;
1829 if (s->strm->avail_out == 0) return need_more;
1830 } else {
1831 /* There is no previous match to compare with, wait for
1832 * the next step to decide.
1833 */
1834 s->match_available = 1;
1835 s->strstart++;
1836 s->lookahead--;
1837 }
1838 }
1839 Assert (flush != Z_NO_FLUSH, "no flush?");
1840 if (s->match_available) {
1841 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1842 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1843 s->match_available = 0;
1844 }
1845 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1846 if (flush == Z_FINISH) {
1847 FLUSH_BLOCK(s, 1);
1848 return finish_done;
1849 }
1850 if (s->last_lit)
1851 FLUSH_BLOCK(s, 0);
1852 return block_done;
1853 }
1854 #endif /* FASTEST */
1855
1856 /* ===========================================================================
1857 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1858 * one. Do not maintain a hash table. (It will be regenerated if this run of
1859 * deflate switches away from Z_RLE.)
1860 */
1861 local block_state deflate_rle(s, flush)
1862 deflate_state *s;
1863 int flush;
1864 {
1865 int bflush; /* set if current block must be flushed */
1866 uInt prev; /* byte at distance one to match */
1867 Bytef *scan, *strend; /* scan goes up to strend for length of run */
1868
1869 for (;;) {
1870 /* Make sure that we always have enough lookahead, except
1871 * at the end of the input file. We need MAX_MATCH bytes
1872 * for the longest run, plus one for the unrolled loop.
1873 */
1874 if (s->lookahead <= MAX_MATCH) {
1875 fill_window(s);
1876 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
1877 return need_more;
1878 }
1879 if (s->lookahead == 0) break; /* flush the current block */
1880 }
1881
1882 /* See how many times the previous byte repeats */
1883 s->match_length = 0;
1884 if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
1885 scan = s->window + s->strstart - 1;
1886 prev = *scan;
1887 if (prev == *++scan && prev == *++scan && prev == *++scan) {
1888 strend = s->window + s->strstart + MAX_MATCH;
1889 do {
1890 } while (prev == *++scan && prev == *++scan &&
1891 prev == *++scan && prev == *++scan &&
1892 prev == *++scan && prev == *++scan &&
1893 prev == *++scan && prev == *++scan &&
1894 scan < strend);
1895 s->match_length = MAX_MATCH - (int)(strend - scan);
1896 if (s->match_length > s->lookahead)
1897 s->match_length = s->lookahead;
1898 }
1899 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
1900 }
1901
1902 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1903 if (s->match_length >= MIN_MATCH) {
1904 check_match(s, s->strstart, s->strstart - 1, s->match_length);
1905
1906 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
1907
1908 s->lookahead -= s->match_length;
1909 s->strstart += s->match_length;
1910 s->match_length = 0;
1911 } else {
1912 /* No match, output a literal byte */
1913 Tracevv((stderr,"%c", s->window[s->strstart]));
1914 _tr_tally_lit (s, s->window[s->strstart], bflush);
1915 s->lookahead--;
1916 s->strstart++;
1917 }
1918 if (bflush) FLUSH_BLOCK(s, 0);
1919 }
1920 s->insert = 0;
1921 if (flush == Z_FINISH) {
1922 FLUSH_BLOCK(s, 1);
1923 return finish_done;
1924 }
1925 if (s->last_lit)
1926 FLUSH_BLOCK(s, 0);
1927 return block_done;
1928 }
1929
1930 /* ===========================================================================
1931 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
1932 * (It will be regenerated if this run of deflate switches away from Huffman.)
1933 */
1934 local block_state deflate_huff(s, flush)
1935 deflate_state *s;
1936 int flush;
1937 {
1938 int bflush; /* set if current block must be flushed */
1939
1940 for (;;) {
1941 /* Make sure that we have a literal to write. */
1942 if (s->lookahead == 0) {
1943 fill_window(s);
1944 if (s->lookahead == 0) {
1945 if (flush == Z_NO_FLUSH)
1946 return need_more;
1947 break; /* flush the current block */
1948 }
1949 }
1950
1951 /* Output a literal byte */
1952 s->match_length = 0;
1953 Tracevv((stderr,"%c", s->window[s->strstart]));
1954 _tr_tally_lit (s, s->window[s->strstart], bflush);
1955 s->lookahead--;
1956 s->strstart++;
1957 if (bflush) FLUSH_BLOCK(s, 0);
1958 }
1959 s->insert = 0;
1960 if (flush == Z_FINISH) {
1961 FLUSH_BLOCK(s, 1);
1962 return finish_done;
1963 }
1964 if (s->last_lit)
1965 FLUSH_BLOCK(s, 0);
1966 return block_done;
1967 }