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 #ifndef LONGEST_MATCH_ONLY
64 /* ===========================================================================
65 * Function prototypes.
66 */
67 typedef enum {
68 need_more, /* block not completed, need more input or more output */
69 block_done, /* block flush performed */
70 finish_started, /* finish started, need only more output at next deflate */
71 finish_done /* finish done, accept no more input or output */
72 } block_state;
73
74 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
75 /* Compression function. Returns the block state after the call. */
76
77 local void fill_window OF((deflate_state *s));
78 local block_state deflate_stored OF((deflate_state *s, int flush));
79 local block_state deflate_fast OF((deflate_state *s, int flush));
80 #ifndef FASTEST
81 local block_state deflate_slow OF((deflate_state *s, int flush));
82 #endif
83 local block_state deflate_rle OF((deflate_state *s, int flush));
84 local block_state deflate_huff OF((deflate_state *s, int flush));
85 local void lm_init OF((deflate_state *s));
86 local void putShortMSB OF((deflate_state *s, uInt b));
87 local void flush_pending OF((z_streamp strm));
88 local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
89 #ifdef ASMV
90 void match_init OF((void)); /* asm code initialization */
91 uInt longest_match OF((deflate_state *s, IPos cur_match));
92 #else
93 #ifdef ORIG_LONGEST_MATCH
94 local uInt longest_match OF((deflate_state *s, IPos cur_match));
95 #else
96 uInt longest_match OF((deflate_state *s, IPos cur_match));
97 #endif
98 #endif
99
100 #ifdef DEBUG
101 local void check_match OF((deflate_state *s, IPos start, IPos match,
102 int length));
103 #endif
104 #endif /* ! LONGEST_MATCH_ONLY */
105
106 /* ===========================================================================
107 * Local data
108 */
109
110 #define NIL 0
111 /* Tail of hash chains */
112
113 #ifndef LONGEST_MATCH_ONLY
114 #ifndef TOO_FAR
115 # define TOO_FAR 4096
116 #endif
117 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
118
119 /* Values for max_lazy_match, good_match and max_chain_length, depending on
120 * the desired pack level (0..9). The values given below have been tuned to
121 * exclude worst case performance for pathological files. Better values may be
122 * found for specific files.
123 */
124 typedef struct config_s {
125 ush good_length; /* reduce lazy search above this match length */
126 ush max_lazy; /* do not perform lazy search above this match length */
127 ush nice_length; /* quit search above this match length */
128 ush max_chain;
129 compress_func func;
130 } config;
131
132 #ifdef FASTEST
133 local const config configuration_table[2] = {
134 /* good lazy nice chain */
135 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
136 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
137 #else
138 local const config configuration_table[10] = {
139 /* good lazy nice chain */
140 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
141 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
142 /* 2 */ {4, 5, 16, 8, deflate_fast},
143 /* 3 */ {4, 6, 32, 32, deflate_fast},
144
145 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
146 /* 5 */ {8, 16, 32, 32, deflate_slow},
147 /* 6 */ {8, 16, 128, 128, deflate_slow},
148 /* 7 */ {8, 32, 128, 256, deflate_slow},
149 /* 8 */ {32, 128, 258, 1024, deflate_slow},
150 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
151 #endif
152
153 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
154 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
155 * meaning.
156 */
157
158 #define EQUAL 0
159 /* result of memcmp for equal strings */
160
161 #ifndef NO_DUMMY_DECL
162 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
163 #endif
164
165 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
166 #define RANK(f) (((f) << 1) - ((f) > 4 ? 9 : 0))
167
168 /* ===========================================================================
169 * Update a hash value with the given input byte
170 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
171 * input characters, so that a running hash key can be computed from the
172 * previous key instead of complete recalculation each time.
173 */
174 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
175
176
177 /* ===========================================================================
178 * Insert string str in the dictionary and set match_head to the previous head
179 * of the hash chain (the most recent string with same hash key). Return
180 * the previous length of the hash chain.
181 * If this file is compiled with -DFASTEST, the compression level is forced
182 * to 1, and no hash chains are maintained.
183 * IN assertion: all calls to to INSERT_STRING are made with consecutive
184 * input characters and the first MIN_MATCH bytes of str are valid
185 * (except for the last MIN_MATCH-1 bytes of the input file).
186 */
187 #ifdef FASTEST
188 #define INSERT_STRING(s, str, match_head) \
189 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
190 match_head = s->head[s->ins_h], \
191 s->head[s->ins_h] = (Pos)(str))
192 #else
193 #define INSERT_STRING(s, str, match_head) \
194 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
195 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
196 s->head[s->ins_h] = (Pos)(str))
197 #endif
198
199 /* ===========================================================================
200 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
201 * prev[] will be initialized on the fly.
202 */
203 #define CLEAR_HASH(s) \
204 s->head[s->hash_size-1] = NIL; \
205 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
206
207 /* ========================================================================= */
208 int ZEXPORT deflateInit_(strm, level, version, stream_size)
209 z_streamp strm;
210 int level;
211 const char *version;
212 int stream_size;
213 {
214 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
215 Z_DEFAULT_STRATEGY, version, stream_size);
216 /* To do: ignore strm->next_in if we use it as window */
217 }
218
219 /* ========================================================================= */
220 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
221 version, stream_size)
222 z_streamp strm;
223 int level;
224 int method;
225 int windowBits;
226 int memLevel;
227 int strategy;
228 const char *version;
229 int stream_size;
230 {
231 deflate_state *s;
232 int wrap = 1;
233 static const char my_version[] = ZLIB_VERSION;
234
235 ushf *overlay;
236 /* We overlay pending_buf and d_buf+l_buf. This works since the average
237 * output size for (length,distance) codes is <= 24 bits.
238 */
239
240 if (version == Z_NULL || version[0] != my_version[0] ||
241 stream_size != sizeof(z_stream)) {
242 return Z_VERSION_ERROR;
243 }
244 if (strm == Z_NULL) return Z_STREAM_ERROR;
245
246 strm->msg = Z_NULL;
247 if (strm->zalloc == (alloc_func)0) {
248 #ifdef Z_SOLO
249 return Z_STREAM_ERROR;
250 #else
251 strm->zalloc = zcalloc;
252 strm->opaque = (voidpf)0;
253 #endif
254 }
255 if (strm->zfree == (free_func)0)
256 #ifdef Z_SOLO
257 return Z_STREAM_ERROR;
258 #else
259 strm->zfree = zcfree;
260 #endif
261
262 #ifdef FASTEST
263 if (level != 0) level = 1;
264 #else
265 if (level == Z_DEFAULT_COMPRESSION) level = 6;
266 #endif
267
268 if (windowBits < 0) { /* suppress zlib wrapper */
269 wrap = 0;
270 windowBits = -windowBits;
271 }
272 #ifdef GZIP
273 else if (windowBits > 15) {
274 wrap = 2; /* write gzip wrapper instead */
275 windowBits -= 16;
276 }
277 #endif
278 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
279 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
280 strategy < 0 || strategy > Z_FIXED) {
281 return Z_STREAM_ERROR;
282 }
283 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
284 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
285 if (s == Z_NULL) return Z_MEM_ERROR;
286 strm->state = (struct internal_state FAR *)s;
287 s->strm = strm;
288
289 s->wrap = wrap;
290 s->gzhead = Z_NULL;
291 s->w_bits = windowBits;
292 s->w_size = 1 << s->w_bits;
293 s->w_mask = s->w_size - 1;
294
295 s->hash_bits = memLevel + 7;
296 s->hash_size = 1 << s->hash_bits;
297 s->hash_mask = s->hash_size - 1;
298 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
299
300 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
301 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
302 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
303
304 s->high_water = 0; /* nothing written to s->window yet */
305
306 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
307
308 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
309 s->pending_buf = (uchf *) overlay;
310 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
311
312 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
313 s->pending_buf == Z_NULL) {
314 s->status = FINISH_STATE;
315 strm->msg = ERR_MSG(Z_MEM_ERROR);
316 deflateEnd (strm);
317 return Z_MEM_ERROR;
318 }
319 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
320 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
321
322 s->level = level;
323 s->strategy = strategy;
324 s->method = (Byte)method;
325
326 return deflateReset(strm);
327 }
328
329 /* ========================================================================= */
330 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
331 z_streamp strm;
332 const Bytef *dictionary;
333 uInt dictLength;
334 {
335 deflate_state *s;
336 uInt str, n;
337 int wrap;
338 unsigned avail;
339 z_const unsigned char *next;
340
341 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL)
342 return Z_STREAM_ERROR;
343 s = strm->state;
344 wrap = s->wrap;
345 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
346 return Z_STREAM_ERROR;
347
348 /* when using zlib wrappers, compute Adler-32 for provided dictionary */
349 if (wrap == 1)
350 strm->adler = adler32(strm->adler, dictionary, dictLength);
351 s->wrap = 0; /* avoid computing Adler-32 in read_buf */
352
353 /* if dictionary would fill window, just replace the history */
354 if (dictLength >= s->w_size) {
355 if (wrap == 0) { /* already empty otherwise */
356 CLEAR_HASH(s);
357 s->strstart = 0;
358 s->block_start = 0L;
359 s->insert = 0;
360 }
361 dictionary += dictLength - s->w_size; /* use the tail */
362 dictLength = s->w_size;
363 }
364
365 /* insert dictionary into window and hash */
366 avail = strm->avail_in;
367 next = strm->next_in;
368 strm->avail_in = dictLength;
369 strm->next_in = (z_const Bytef *)dictionary;
370 fill_window(s);
371 while (s->lookahead >= MIN_MATCH) {
372 str = s->strstart;
373 n = s->lookahead - (MIN_MATCH-1);
374 do {
375 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
376 #ifndef FASTEST
377 s->prev[str & s->w_mask] = s->head[s->ins_h];
378 #endif
379 s->head[s->ins_h] = (Pos)str;
380 str++;
381 } while (--n);
382 s->strstart = str;
383 s->lookahead = MIN_MATCH-1;
384 fill_window(s);
385 }
386 s->strstart += s->lookahead;
387 s->block_start = (long)s->strstart;
388 s->insert = s->lookahead;
389 s->lookahead = 0;
390 s->match_length = s->prev_length = MIN_MATCH-1;
391 s->match_available = 0;
392 strm->next_in = next;
393 strm->avail_in = avail;
394 s->wrap = wrap;
395 return Z_OK;
396 }
397
398 /* ========================================================================= */
399 int ZEXPORT deflateResetKeep (strm)
400 z_streamp strm;
401 {
402 deflate_state *s;
403
404 if (strm == Z_NULL || strm->state == Z_NULL ||
405 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
406 return Z_STREAM_ERROR;
407 }
408
409 strm->total_in = strm->total_out = 0;
410 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
411 strm->data_type = Z_UNKNOWN;
412
413 s = (deflate_state *)strm->state;
414 s->pending = 0;
415 s->pending_out = s->pending_buf;
416
417 if (s->wrap < 0) {
418 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
419 }
420 s->status = s->wrap ? INIT_STATE : BUSY_STATE;
421 strm->adler =
422 #ifdef GZIP
423 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
424 #endif
425 adler32(0L, Z_NULL, 0);
426 s->last_flush = Z_NO_FLUSH;
427
428 _tr_init(s);
429
430 return Z_OK;
431 }
432
433 /* ========================================================================= */
434 int ZEXPORT deflateReset (strm)
435 z_streamp strm;
436 {
437 int ret;
438
439 ret = deflateResetKeep(strm);
440 if (ret == Z_OK)
441 lm_init(strm->state);
442 return ret;
443 }
444
445 /* ========================================================================= */
446 int ZEXPORT deflateSetHeader (strm, head)
447 z_streamp strm;
448 gz_headerp head;
449 {
450 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
451 if (strm->state->wrap != 2) return Z_STREAM_ERROR;
452 strm->state->gzhead = head;
453 return Z_OK;
454 }
455
456 /* ========================================================================= */
457 int ZEXPORT deflatePending (strm, pending, bits)
458 unsigned *pending;
459 int *bits;
460 z_streamp strm;
461 {
462 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
463 if (pending != Z_NULL)
464 *pending = strm->state->pending;
465 if (bits != Z_NULL)
466 *bits = strm->state->bi_valid;
467 return Z_OK;
468 }
469
470 /* ========================================================================= */
471 int ZEXPORT deflatePrime (strm, bits, value)
472 z_streamp strm;
473 int bits;
474 int value;
475 {
476 deflate_state *s;
477 int put;
478
479 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
480 s = strm->state;
481 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
482 return Z_BUF_ERROR;
483 do {
484 put = Buf_size - s->bi_valid;
485 if (put > bits)
486 put = bits;
487 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
488 s->bi_valid += put;
489 _tr_flush_bits(s);
490 value >>= put;
491 bits -= put;
492 } while (bits);
493 return Z_OK;
494 }
495
496 /* ========================================================================= */
497 int ZEXPORT deflateParams(strm, level, strategy)
498 z_streamp strm;
499 int level;
500 int strategy;
501 {
502 deflate_state *s;
503 compress_func func;
504 int err = Z_OK;
505
506 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
507 s = strm->state;
508
509 #ifdef FASTEST
510 if (level != 0) level = 1;
511 #else
512 if (level == Z_DEFAULT_COMPRESSION) level = 6;
513 #endif
514 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
515 return Z_STREAM_ERROR;
516 }
517 func = configuration_table[s->level].func;
518
519 if ((strategy != s->strategy || func != configuration_table[level].func) &&
520 strm->total_in != 0) {
521 /* Flush the last buffer: */
522 err = deflate(strm, Z_BLOCK);
523 if (err == Z_BUF_ERROR && s->pending == 0)
524 err = Z_OK;
525 }
526 if (s->level != level) {
527 s->level = level;
528 s->max_lazy_match = configuration_table[level].max_lazy;
529 s->good_match = configuration_table[level].good_length;
530 s->nice_match = configuration_table[level].nice_length;
531 s->max_chain_length = configuration_table[level].max_chain;
532 }
533 s->strategy = strategy;
534 return err;
535 }
536
537 /* ========================================================================= */
538 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
539 z_streamp strm;
540 int good_length;
541 int max_lazy;
542 int nice_length;
543 int max_chain;
544 {
545 deflate_state *s;
546
547 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
548 s = strm->state;
549 s->good_match = good_length;
550 s->max_lazy_match = max_lazy;
551 s->nice_match = nice_length;
552 s->max_chain_length = max_chain;
553 return Z_OK;
554 }
555
556 /* =========================================================================
557 * For the default windowBits of 15 and memLevel of 8, this function returns
558 * a close to exact, as well as small, upper bound on the compressed size.
559 * They are coded as constants here for a reason--if the #define's are
560 * changed, then this function needs to be changed as well. The return
561 * value for 15 and 8 only works for those exact settings.
562 *
563 * For any setting other than those defaults for windowBits and memLevel,
564 * the value returned is a conservative worst case for the maximum expansion
565 * resulting from using fixed blocks instead of stored blocks, which deflate
566 * can emit on compressed data for some combinations of the parameters.
567 *
568 * This function could be more sophisticated to provide closer upper bounds for
569 * every combination of windowBits and memLevel. But even the conservative
570 * upper bound of about 14% expansion does not seem onerous for output buffer
571 * allocation.
572 */
573 uLong ZEXPORT deflateBound(strm, sourceLen)
574 z_streamp strm;
575 uLong sourceLen;
576 {
577 deflate_state *s;
578 uLong complen, wraplen;
579 Bytef *str;
580
581 /* conservative upper bound for compressed data */
582 complen = sourceLen +
583 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
584
585 /* if can't get parameters, return conservative bound plus zlib wrapper */
586 if (strm == Z_NULL || strm->state == Z_NULL)
587 return complen + 6;
588
589 /* compute wrapper length */
590 s = strm->state;
591 switch (s->wrap) {
592 case 0: /* raw deflate */
593 wraplen = 0;
594 break;
595 case 1: /* zlib wrapper */
596 wraplen = 6 + (s->strstart ? 4 : 0);
597 break;
598 case 2: /* gzip wrapper */
599 wraplen = 18;
600 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
601 if (s->gzhead->extra != Z_NULL)
602 wraplen += 2 + s->gzhead->extra_len;
603 str = s->gzhead->name;
604 if (str != Z_NULL)
605 do {
606 wraplen++;
607 } while (*str++);
608 str = s->gzhead->comment;
609 if (str != Z_NULL)
610 do {
611 wraplen++;
612 } while (*str++);
613 if (s->gzhead->hcrc)
614 wraplen += 2;
615 }
616 break;
617 default: /* for compiler happiness */
618 wraplen = 6;
619 }
620
621 /* if not default parameters, return conservative bound */
622 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
623 return complen + wraplen;
624
625 /* default settings: return tight bound for that case */
626 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
627 (sourceLen >> 25) + 13 - 6 + wraplen;
628 }
629
630 /* =========================================================================
631 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
632 * IN assertion: the stream state is correct and there is enough room in
633 * pending_buf.
634 */
635 local void putShortMSB (s, b)
636 deflate_state *s;
637 uInt b;
638 {
639 put_byte(s, (Byte)(b >> 8));
640 put_byte(s, (Byte)(b & 0xff));
641 }
642
643 /* =========================================================================
644 * Flush as much pending output as possible. All deflate() output goes
645 * through this function so some applications may wish to modify it
646 * to avoid allocating a large strm->next_out buffer and copying into it.
647 * (See also read_buf()).
648 */
649 local void flush_pending(strm)
650 z_streamp strm;
651 {
652 unsigned len;
653 deflate_state *s = strm->state;
654
655 _tr_flush_bits(s);
656 len = s->pending;
657 if (len > strm->avail_out) len = strm->avail_out;
658 if (len == 0) return;
659
660 zmemcpy(strm->next_out, s->pending_out, len);
661 strm->next_out += len;
662 s->pending_out += len;
663 strm->total_out += len;
664 strm->avail_out -= len;
665 s->pending -= len;
666 if (s->pending == 0) {
667 s->pending_out = s->pending_buf;
668 }
669 }
670
671 /* ========================================================================= */
672 int ZEXPORT deflate (strm, flush)
673 z_streamp strm;
674 int flush;
675 {
676 int old_flush; /* value of flush param for previous deflate call */
677 deflate_state *s;
678
679 if (strm == Z_NULL || strm->state == Z_NULL ||
680 flush > Z_BLOCK || flush < 0) {
681 return Z_STREAM_ERROR;
682 }
683 s = strm->state;
684
685 if (strm->next_out == Z_NULL ||
686 (strm->next_in == Z_NULL && strm->avail_in != 0) ||
687 (s->status == FINISH_STATE && flush != Z_FINISH)) {
688 ERR_RETURN(strm, Z_STREAM_ERROR);
689 }
690 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
691
692 s->strm = strm; /* just in case */
693 old_flush = s->last_flush;
694 s->last_flush = flush;
695
696 /* Write the header */
697 if (s->status == INIT_STATE) {
698 #ifdef GZIP
699 if (s->wrap == 2) {
700 strm->adler = crc32(0L, Z_NULL, 0);
701 put_byte(s, 31);
702 put_byte(s, 139);
703 put_byte(s, 8);
704 if (s->gzhead == Z_NULL) {
705 put_byte(s, 0);
706 put_byte(s, 0);
707 put_byte(s, 0);
708 put_byte(s, 0);
709 put_byte(s, 0);
710 put_byte(s, s->level == 9 ? 2 :
711 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
712 4 : 0));
713 put_byte(s, OS_CODE);
714 s->status = BUSY_STATE;
715 }
716 else {
717 put_byte(s, (s->gzhead->text ? 1 : 0) +
718 (s->gzhead->hcrc ? 2 : 0) +
719 (s->gzhead->extra == Z_NULL ? 0 : 4) +
720 (s->gzhead->name == Z_NULL ? 0 : 8) +
721 (s->gzhead->comment == Z_NULL ? 0 : 16)
722 );
723 put_byte(s, (Byte)(s->gzhead->time & 0xff));
724 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
725 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
726 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
727 put_byte(s, s->level == 9 ? 2 :
728 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
729 4 : 0));
730 put_byte(s, s->gzhead->os & 0xff);
731 if (s->gzhead->extra != Z_NULL) {
732 put_byte(s, s->gzhead->extra_len & 0xff);
733 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
734 }
735 if (s->gzhead->hcrc)
736 strm->adler = crc32(strm->adler, s->pending_buf,
737 s->pending);
738 s->gzindex = 0;
739 s->status = EXTRA_STATE;
740 }
741 }
742 else
743 #endif
744 {
745 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
746 uInt level_flags;
747
748 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
749 level_flags = 0;
750 else if (s->level < 6)
751 level_flags = 1;
752 else if (s->level == 6)
753 level_flags = 2;
754 else
755 level_flags = 3;
756 header |= (level_flags << 6);
757 if (s->strstart != 0) header |= PRESET_DICT;
758 header += 31 - (header % 31);
759
760 s->status = BUSY_STATE;
761 putShortMSB(s, header);
762
763 /* Save the adler32 of the preset dictionary: */
764 if (s->strstart != 0) {
765 putShortMSB(s, (uInt)(strm->adler >> 16));
766 putShortMSB(s, (uInt)(strm->adler & 0xffff));
767 }
768 strm->adler = adler32(0L, Z_NULL, 0);
769 }
770 }
771 #ifdef GZIP
772 if (s->status == EXTRA_STATE) {
773 if (s->gzhead->extra != Z_NULL) {
774 uInt beg = s->pending; /* start of bytes to update crc */
775
776 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
777 if (s->pending == s->pending_buf_size) {
778 if (s->gzhead->hcrc && s->pending > beg)
779 strm->adler = crc32(strm->adler, s->pending_buf + beg,
780 s->pending - beg);
781 flush_pending(strm);
782 beg = s->pending;
783 if (s->pending == s->pending_buf_size)
784 break;
785 }
786 put_byte(s, s->gzhead->extra[s->gzindex]);
787 s->gzindex++;
788 }
789 if (s->gzhead->hcrc && s->pending > beg)
790 strm->adler = crc32(strm->adler, s->pending_buf + beg,
791 s->pending - beg);
792 if (s->gzindex == s->gzhead->extra_len) {
793 s->gzindex = 0;
794 s->status = NAME_STATE;
795 }
796 }
797 else
798 s->status = NAME_STATE;
799 }
800 if (s->status == NAME_STATE) {
801 if (s->gzhead->name != Z_NULL) {
802 uInt beg = s->pending; /* start of bytes to update crc */
803 int val;
804
805 do {
806 if (s->pending == s->pending_buf_size) {
807 if (s->gzhead->hcrc && s->pending > beg)
808 strm->adler = crc32(strm->adler, s->pending_buf + beg,
809 s->pending - beg);
810 flush_pending(strm);
811 beg = s->pending;
812 if (s->pending == s->pending_buf_size) {
813 val = 1;
814 break;
815 }
816 }
817 val = s->gzhead->name[s->gzindex++];
818 put_byte(s, val);
819 } while (val != 0);
820 if (s->gzhead->hcrc && s->pending > beg)
821 strm->adler = crc32(strm->adler, s->pending_buf + beg,
822 s->pending - beg);
823 if (val == 0) {
824 s->gzindex = 0;
825 s->status = COMMENT_STATE;
826 }
827 }
828 else
829 s->status = COMMENT_STATE;
830 }
831 if (s->status == COMMENT_STATE) {
832 if (s->gzhead->comment != Z_NULL) {
833 uInt beg = s->pending; /* start of bytes to update crc */
834 int val;
835
836 do {
837 if (s->pending == s->pending_buf_size) {
838 if (s->gzhead->hcrc && s->pending > beg)
839 strm->adler = crc32(strm->adler, s->pending_buf + beg,
840 s->pending - beg);
841 flush_pending(strm);
842 beg = s->pending;
843 if (s->pending == s->pending_buf_size) {
844 val = 1;
845 break;
846 }
847 }
848 val = s->gzhead->comment[s->gzindex++];
849 put_byte(s, val);
850 } while (val != 0);
851 if (s->gzhead->hcrc && s->pending > beg)
852 strm->adler = crc32(strm->adler, s->pending_buf + beg,
853 s->pending - beg);
854 if (val == 0)
855 s->status = HCRC_STATE;
856 }
857 else
858 s->status = HCRC_STATE;
859 }
860 if (s->status == HCRC_STATE) {
861 if (s->gzhead->hcrc) {
862 if (s->pending + 2 > s->pending_buf_size)
863 flush_pending(strm);
864 if (s->pending + 2 <= s->pending_buf_size) {
865 put_byte(s, (Byte)(strm->adler & 0xff));
866 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
867 strm->adler = crc32(0L, Z_NULL, 0);
868 s->status = BUSY_STATE;
869 }
870 }
871 else
872 s->status = BUSY_STATE;
873 }
874 #endif
875
876 /* Flush as much pending output as possible */
877 if (s->pending != 0) {
878 flush_pending(strm);
879 if (strm->avail_out == 0) {
880 /* Since avail_out is 0, deflate will be called again with
881 * more output space, but possibly with both pending and
882 * avail_in equal to zero. There won't be anything to do,
883 * but this is not an error situation so make sure we
884 * return OK instead of BUF_ERROR at next call of deflate:
885 */
886 s->last_flush = -1;
887 return Z_OK;
888 }
889
890 /* Make sure there is something to do and avoid duplicate consecutive
891 * flushes. For repeated and useless calls with Z_FINISH, we keep
892 * returning Z_STREAM_END instead of Z_BUF_ERROR.
893 */
894 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
895 flush != Z_FINISH) {
896 ERR_RETURN(strm, Z_BUF_ERROR);
897 }
898
899 /* User must not provide more input after the first FINISH: */
900 if (s->status == FINISH_STATE && strm->avail_in != 0) {
901 ERR_RETURN(strm, Z_BUF_ERROR);
902 }
903
904 /* Start a new block or continue the current one.
905 */
906 if (strm->avail_in != 0 || s->lookahead != 0 ||
907 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
908 block_state bstate;
909
910 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
911 (s->strategy == Z_RLE ? deflate_rle(s, flush) :
912 (*(configuration_table[s->level].func))(s, flush));
913
914 if (bstate == finish_started || bstate == finish_done) {
915 s->status = FINISH_STATE;
916 }
917 if (bstate == need_more || bstate == finish_started) {
918 if (strm->avail_out == 0) {
919 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
920 }
921 return Z_OK;
922 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
923 * of deflate should use the same flush parameter to make sure
924 * that the flush is complete. So we don't have to output an
925 * empty block here, this will be done at next call. This also
926 * ensures that for a very small output buffer, we emit at most
927 * one empty block.
928 */
929 }
930 if (bstate == block_done) {
931 if (flush == Z_PARTIAL_FLUSH) {
932 _tr_align(s);
933 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
934 _tr_stored_block(s, (char*)0, 0L, 0);
935 /* For a full flush, this empty block will be recognized
936 * as a special marker by inflate_sync().
937 */
938 if (flush == Z_FULL_FLUSH) {
939 CLEAR_HASH(s); /* forget history */
940 if (s->lookahead == 0) {
941 s->strstart = 0;
942 s->block_start = 0L;
943 s->insert = 0;
944 }
945 }
946 }
947 flush_pending(strm);
948 if (strm->avail_out == 0) {
949 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
950 return Z_OK;
951 }
952 }
953 }
954 Assert(strm->avail_out > 0, "bug2");
955
956 if (flush != Z_FINISH) return Z_OK;
957 if (s->wrap <= 0) return Z_STREAM_END;
958
959 /* Write the trailer */
960 #ifdef GZIP
961 if (s->wrap == 2) {
962 put_byte(s, (Byte)(strm->adler & 0xff));
963 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
964 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
965 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
966 put_byte(s, (Byte)(strm->total_in & 0xff));
967 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
968 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
969 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
970 }
971 else
972 #endif
973 {
974 putShortMSB(s, (uInt)(strm->adler >> 16));
975 putShortMSB(s, (uInt)(strm->adler & 0xffff));
976 }
977 flush_pending(strm);
978 /* If avail_out is zero, the application will call deflate again
979 * to flush the rest.
980 */
981 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
982 return s->pending != 0 ? Z_OK : Z_STREAM_END;
983 }
984
985 /* ========================================================================= */
986 int ZEXPORT deflateEnd (strm)
987 z_streamp strm;
988 {
989 int status;
990
991 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
992
993 status = strm->state->status;
994 if (status != INIT_STATE &&
995 status != EXTRA_STATE &&
996 status != NAME_STATE &&
997 status != COMMENT_STATE &&
998 status != HCRC_STATE &&
999 status != BUSY_STATE &&
1000 status != FINISH_STATE) {
1001 return Z_STREAM_ERROR;
1002 }
1003
1004 /* Deallocate in reverse order of allocations: */
1005 TRY_FREE(strm, strm->state->pending_buf);
1006 TRY_FREE(strm, strm->state->head);
1007 TRY_FREE(strm, strm->state->prev);
1008 TRY_FREE(strm, strm->state->window);
1009
1010 ZFREE(strm, strm->state);
1011 strm->state = Z_NULL;
1012
1013 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1014 }
1015
1016 /* =========================================================================
1017 * Copy the source state to the destination state.
1018 * To simplify the source, this is not supported for 16-bit MSDOS (which
1019 * doesn't have enough memory anyway to duplicate compression states).
1020 */
1021 int ZEXPORT deflateCopy (dest, source)
1022 z_streamp dest;
1023 z_streamp source;
1024 {
1025 #ifdef MAXSEG_64K
1026 return Z_STREAM_ERROR;
1027 #else
1028 deflate_state *ds;
1029 deflate_state *ss;
1030 ushf *overlay;
1031
1032
1033 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
1034 return Z_STREAM_ERROR;
1035 }
1036
1037 ss = source->state;
1038
1039 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1040
1041 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1042 if (ds == Z_NULL) return Z_MEM_ERROR;
1043 dest->state = (struct internal_state FAR *) ds;
1044 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1045 ds->strm = dest;
1046
1047 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1048 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1049 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1050 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1051 ds->pending_buf = (uchf *) overlay;
1052
1053 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1054 ds->pending_buf == Z_NULL) {
1055 deflateEnd (dest);
1056 return Z_MEM_ERROR;
1057 }
1058 /* following zmemcpy do not work for 16-bit MSDOS */
1059 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1060 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1061 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1062 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1063
1064 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1065 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1066 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1067
1068 ds->l_desc.dyn_tree = ds->dyn_ltree;
1069 ds->d_desc.dyn_tree = ds->dyn_dtree;
1070 ds->bl_desc.dyn_tree = ds->bl_tree;
1071
1072 return Z_OK;
1073 #endif /* MAXSEG_64K */
1074 }
1075
1076 /* ===========================================================================
1077 * Read a new buffer from the current input stream, update the adler32
1078 * and total number of bytes read. All deflate() input goes through
1079 * this function so some applications may wish to modify it to avoid
1080 * allocating a large strm->next_in buffer and copying from it.
1081 * (See also flush_pending()).
1082 */
1083 local int read_buf(strm, buf, size)
1084 z_streamp strm;
1085 Bytef *buf;
1086 unsigned size;
1087 {
1088 unsigned len = strm->avail_in;
1089
1090 if (len > size) len = size;
1091 if (len == 0) return 0;
1092
1093 strm->avail_in -= len;
1094
1095 zmemcpy(buf, strm->next_in, len);
1096 if (strm->state->wrap == 1) {
1097 strm->adler = adler32(strm->adler, buf, len);
1098 }
1099 #ifdef GZIP
1100 else if (strm->state->wrap == 2) {
1101 strm->adler = crc32(strm->adler, buf, len);
1102 }
1103 #endif
1104 strm->next_in += len;
1105 strm->total_in += len;
1106
1107 return (int)len;
1108 }
1109
1110 /* ===========================================================================
1111 * Initialize the "longest match" routines for a new zlib stream
1112 */
1113 local void lm_init (s)
1114 deflate_state *s;
1115 {
1116 s->window_size = (ulg)2L*s->w_size;
1117
1118 CLEAR_HASH(s);
1119
1120 /* Set the default configuration parameters:
1121 */
1122 s->max_lazy_match = configuration_table[s->level].max_lazy;
1123 s->good_match = configuration_table[s->level].good_length;
1124 s->nice_match = configuration_table[s->level].nice_length;
1125 s->max_chain_length = configuration_table[s->level].max_chain;
1126
1127 s->strstart = 0;
1128 s->block_start = 0L;
1129 s->lookahead = 0;
1130 s->insert = 0;
1131 s->match_length = s->prev_length = MIN_MATCH-1;
1132 s->match_available = 0;
1133 s->ins_h = 0;
1134 #ifndef FASTEST
1135 #ifdef ASMV
1136 match_init(); /* initialize the asm code */
1137 #endif
1138 #endif
1139 }
1140 #endif /* ! LONGEST_MATCH_ONLY */
1141
1142 #if defined(ORIG_LONGEST_MATCH) || defined(ORIG_LONGEST_MATCH_GLOBAL)
1143 #ifndef FASTEST
1144 /* ===========================================================================
1145 * Set match_start to the longest match starting at the given string and
1146 * return its length. Matches shorter or equal to prev_length are discarded,
1147 * in which case the result is equal to prev_length and match_start is
1148 * garbage.
1149 * IN assertions: cur_match is the head of the hash chain for the current
1150 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1151 * OUT assertion: the match length is not greater than s->lookahead.
1152 */
1153 #ifndef ASMV
1154 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1155 * match.S. The code will be functionally equivalent.
1156 */
1157 #ifdef ORIG_LONGEST_MATCH_GLOBAL
1158 uInt longest_match(s, cur_match)
1159 #else
1160 local uInt longest_match(s, cur_match)
1161 #endif
1162 deflate_state *s;
1163 IPos cur_match; /* current match */
1164 {
1165 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1166 register Bytef *scan = s->window + s->strstart; /* current string */
1167 register Bytef *match; /* matched string */
1168 register int len; /* length of current match */
1169 int best_len = s->prev_length; /* best match length so far */
1170 int nice_match = s->nice_match; /* stop if match long enough */
1171 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1172 s->strstart - (IPos)MAX_DIST(s) : NIL;
1173 /* Stop when cur_match becomes <= limit. To simplify the code,
1174 * we prevent matches with the string of window index 0.
1175 */
1176 Posf *prev = s->prev;
1177 uInt wmask = s->w_mask;
1178
1179 #ifdef UNALIGNED_OK
1180 /* Compare two bytes at a time. Note: this is not always beneficial.
1181 * Try with and without -DUNALIGNED_OK to check.
1182 */
1183 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1184 register ush scan_start = *(ushf*)scan;
1185 register ush scan_end = *(ushf*)(scan+best_len-1);
1186 #else
1187 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1188 register Byte scan_end1 = scan[best_len-1];
1189 register Byte scan_end = scan[best_len];
1190 #endif
1191
1192 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1193 * It is easy to get rid of this optimization if necessary.
1194 */
1195 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1196
1197 /* Do not waste too much time if we already have a good match: */
1198 if (s->prev_length >= s->good_match) {
1199 chain_length >>= 2;
1200 }
1201 /* Do not look for matches beyond the end of the input. This is necessary
1202 * to make deflate deterministic.
1203 */
1204 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1205
1206 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1207
1208 do {
1209 Assert(cur_match < s->strstart, "no future");
1210 match = s->window + cur_match;
1211
1212 /* Skip to next match if the match length cannot increase
1213 * or if the match length is less than 2. Note that the checks below
1214 * for insufficient lookahead only occur occasionally for performance
1215 * reasons. Therefore uninitialized memory will be accessed, and
1216 * conditional jumps will be made that depend on those values.
1217 * However the length of the match is limited to the lookahead, so
1218 * the output of deflate is not affected by the uninitialized values.
1219 */
1220 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1221 /* This code assumes sizeof(unsigned short) == 2. Do not use
1222 * UNALIGNED_OK if your compiler uses a different size.
1223 */
1224 if (*(ushf*)(match+best_len-1) != scan_end ||
1225 *(ushf*)match != scan_start) continue;
1226
1227 /* It is not necessary to compare scan[2] and match[2] since they are
1228 * always equal when the other bytes match, given that the hash keys
1229 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1230 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1231 * lookahead only every 4th comparison; the 128th check will be made
1232 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1233 * necessary to put more guard bytes at the end of the window, or
1234 * to check more often for insufficient lookahead.
1235 */
1236 Assert(scan[2] == match[2], "scan[2]?");
1237 scan++, match++;
1238 do {
1239 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1240 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1241 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1242 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1243 scan < strend);
1244 /* The funny "do {}" generates better code on most compilers */
1245
1246 /* Here, scan <= window+strstart+257 */
1247 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1248 if (*scan == *match) scan++;
1249
1250 len = (MAX_MATCH - 1) - (int)(strend-scan);
1251 scan = strend - (MAX_MATCH-1);
1252
1253 #else /* UNALIGNED_OK */
1254
1255 if (match[best_len] != scan_end ||
1256 match[best_len-1] != scan_end1 ||
1257 *match != *scan ||
1258 *++match != scan[1]) continue;
1259
1260 /* The check at best_len-1 can be removed because it will be made
1261 * again later. (This heuristic is not always a win.)
1262 * It is not necessary to compare scan[2] and match[2] since they
1263 * are always equal when the other bytes match, given that
1264 * the hash keys are equal and that HASH_BITS >= 8.
1265 */
1266 scan += 2, match++;
1267 Assert(*scan == *match, "match[2]?");
1268
1269 /* We check for insufficient lookahead only every 8th comparison;
1270 * the 256th check will be made at strstart+258.
1271 */
1272 do {
1273 } while (*++scan == *++match && *++scan == *++match &&
1274 *++scan == *++match && *++scan == *++match &&
1275 *++scan == *++match && *++scan == *++match &&
1276 *++scan == *++match && *++scan == *++match &&
1277 scan < strend);
1278
1279 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1280
1281 len = MAX_MATCH - (int)(strend - scan);
1282 scan = strend - MAX_MATCH;
1283
1284 #endif /* UNALIGNED_OK */
1285
1286 if (len > best_len) {
1287 s->match_start = cur_match;
1288 best_len = len;
1289 if (len >= nice_match) break;
1290 #ifdef UNALIGNED_OK
1291 scan_end = *(ushf*)(scan+best_len-1);
1292 #else
1293 scan_end1 = scan[best_len-1];
1294 scan_end = scan[best_len];
1295 #endif
1296 }
1297 } while ((cur_match = prev[cur_match & wmask]) > limit
1298 && --chain_length != 0);
1299
1300 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1301 return s->lookahead;
1302 }
1303 #endif /* ASMV */
1304 #endif /* ORIG_LONGEST_MATCHT */
1305
1306 #else /* FASTEST */
1307
1308 /* ---------------------------------------------------------------------------
1309 * Optimized version for FASTEST only
1310 */
1311 local uInt longest_match(s, cur_match)
1312 deflate_state *s;
1313 IPos cur_match; /* current match */
1314 {
1315 register Bytef *scan = s->window + s->strstart; /* current string */
1316 register Bytef *match; /* matched string */
1317 register int len; /* length of current match */
1318 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1319
1320 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1321 * It is easy to get rid of this optimization if necessary.
1322 */
1323 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1324
1325 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1326
1327 Assert(cur_match < s->strstart, "no future");
1328
1329 match = s->window + cur_match;
1330
1331 /* Return failure if the match length is less than 2:
1332 */
1333 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
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 += 2;
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
1358 if (len < MIN_MATCH) return MIN_MATCH - 1;
1359
1360 s->match_start = cur_match;
1361 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1362 }
1363
1364 #endif /* FASTEST */
1365
1366 #ifndef LONGEST_MATCH_ONLY
1367 #ifdef DEBUG
1368 /* ===========================================================================
1369 * Check that the match at match_start is indeed a match.
1370 */
1371 local void check_match(s, start, match, length)
1372 deflate_state *s;
1373 IPos start, match;
1374 int length;
1375 {
1376 /* check that the match is indeed a match */
1377 if (zmemcmp(s->window + match,
1378 s->window + start, length) != EQUAL) {
1379 fprintf(stderr, " start %u, match %u, length %d\n",
1380 start, match, length);
1381 do {
1382 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1383 } while (--length != 0);
1384 z_error("invalid match");
1385 }
1386 if (z_verbose > 1) {
1387 fprintf(stderr,"\\[%d,%d]", start-match, length);
1388 do { putc(s->window[start++], stderr); } while (--length != 0);
1389 }
1390 }
1391 #else
1392 # define check_match(s, start, match, length)
1393 #endif /* DEBUG */
1394
1395 /* ===========================================================================
1396 * Fill the window when the lookahead becomes insufficient.
1397 * Updates strstart and lookahead.
1398 *
1399 * IN assertion: lookahead < MIN_LOOKAHEAD
1400 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1401 * At least one byte has been read, or avail_in == 0; reads are
1402 * performed for at least two bytes (required for the zip translate_eol
1403 * option -- not supported here).
1404 */
1405 local void fill_window(s)
1406 deflate_state *s;
1407 {
1408 register unsigned n, m;
1409 register Posf *p;
1410 unsigned more; /* Amount of free space at the end of the window. */
1411 uInt wsize = s->w_size;
1412
1413 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1414
1415 do {
1416 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1417
1418 /* Deal with !@#$% 64K limit: */
1419 if (sizeof(int) <= 2) {
1420 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1421 more = wsize;
1422
1423 } else if (more == (unsigned)(-1)) {
1424 /* Very unlikely, but possible on 16 bit machine if
1425 * strstart == 0 && lookahead == 1 (input done a byte at time)
1426 */
1427 more--;
1428 }
1429 }
1430
1431 /* If the window is almost full and there is insufficient lookahead,
1432 * move the upper half to the lower one to make room in the upper half.
1433 */
1434 if (s->strstart >= wsize+MAX_DIST(s)) {
1435
1436 zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1437 s->match_start -= wsize;
1438 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1439 s->block_start -= (long) wsize;
1440
1441 /* Slide the hash table (could be avoided with 32 bit values
1442 at the expense of memory usage). We slide even when level == 0
1443 to keep the hash table consistent if we switch back to level > 0
1444 later. (Using level 0 permanently is not an optimal usage of
1445 zlib, so we don't care about this pathological case.)
1446 */
1447 n = s->hash_size;
1448 p = &s->head[n];
1449 do {
1450 m = *--p;
1451 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1452 } while (--n);
1453
1454 n = wsize;
1455 #ifndef FASTEST
1456 p = &s->prev[n];
1457 do {
1458 m = *--p;
1459 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1460 /* If n is not on any hash chain, prev[n] is garbage but
1461 * its value will never be used.
1462 */
1463 } while (--n);
1464 #endif
1465 more += wsize;
1466 }
1467 if (s->strm->avail_in == 0) break;
1468
1469 /* If there was no sliding:
1470 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1471 * more == window_size - lookahead - strstart
1472 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1473 * => more >= window_size - 2*WSIZE + 2
1474 * In the BIG_MEM or MMAP case (not yet supported),
1475 * window_size == input_size + MIN_LOOKAHEAD &&
1476 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1477 * Otherwise, window_size == 2*WSIZE so more >= 2.
1478 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1479 */
1480 Assert(more >= 2, "more < 2");
1481
1482 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1483 s->lookahead += n;
1484
1485 /* Initialize the hash value now that we have some input: */
1486 if (s->lookahead + s->insert >= MIN_MATCH) {
1487 uInt str = s->strstart - s->insert;
1488 s->ins_h = s->window[str];
1489 UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1490 #if MIN_MATCH != 3
1491 Call UPDATE_HASH() MIN_MATCH-3 more times
1492 #endif
1493 while (s->insert) {
1494 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1495 #ifndef FASTEST
1496 s->prev[str & s->w_mask] = s->head[s->ins_h];
1497 #endif
1498 s->head[s->ins_h] = (Pos)str;
1499 str++;
1500 s->insert--;
1501 if (s->lookahead + s->insert < MIN_MATCH)
1502 break;
1503 }
1504 }
1505 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1506 * but this is not important since only literal bytes will be emitted.
1507 */
1508
1509 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1510
1511 /* If the WIN_INIT bytes after the end of the current data have never been
1512 * written, then zero those bytes in order to avoid memory check reports of
1513 * the use of uninitialized (or uninitialised as Julian writes) bytes by
1514 * the longest match routines. Update the high water mark for the next
1515 * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1516 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1517 */
1518 if (s->high_water < s->window_size) {
1519 ulg curr = s->strstart + (ulg)(s->lookahead);
1520 ulg init;
1521
1522 if (s->high_water < curr) {
1523 /* Previous high water mark below current data -- zero WIN_INIT
1524 * bytes or up to end of window, whichever is less.
1525 */
1526 init = s->window_size - curr;
1527 if (init > WIN_INIT)
1528 init = WIN_INIT;
1529 zmemzero(s->window + curr, (unsigned)init);
1530 s->high_water = curr + init;
1531 }
1532 else if (s->high_water < (ulg)curr + WIN_INIT) {
1533 /* High water mark at or above current data, but below current data
1534 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1535 * to end of window, whichever is less.
1536 */
1537 init = (ulg)curr + WIN_INIT - s->high_water;
1538 if (init > s->window_size - s->high_water)
1539 init = s->window_size - s->high_water;
1540 zmemzero(s->window + s->high_water, (unsigned)init);
1541 s->high_water += init;
1542 }
1543 }
1544
1545 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1546 "not enough room for search");
1547 }
1548
1549 /* ===========================================================================
1550 * Flush the current block, with given end-of-file flag.
1551 * IN assertion: strstart is set to the end of the current match.
1552 */
1553 #define FLUSH_BLOCK_ONLY(s, last) { \
1554 _tr_flush_block(s, (s->block_start >= 0L ? \
1555 (charf *)&s->window[(unsigned)s->block_start] : \
1556 (charf *)Z_NULL), \
1557 (ulg)((long)s->strstart - s->block_start), \
1558 (last)); \
1559 s->block_start = s->strstart; \
1560 flush_pending(s->strm); \
1561 Tracev((stderr,"[FLUSH]")); \
1562 }
1563
1564 /* Same but force premature exit if necessary. */
1565 #define FLUSH_BLOCK(s, last) { \
1566 FLUSH_BLOCK_ONLY(s, last); \
1567 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1568 }
1569
1570 /* ===========================================================================
1571 * Copy without compression as much as possible from the input stream, return
1572 * the current block state.
1573 * This function does not insert new strings in the dictionary since
1574 * uncompressible data is probably not useful. This function is used
1575 * only for the level=0 compression option.
1576 * NOTE: this function should be optimized to avoid extra copying from
1577 * window to pending_buf.
1578 */
1579 local block_state deflate_stored(s, flush)
1580 deflate_state *s;
1581 int flush;
1582 {
1583 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1584 * to pending_buf_size, and each stored block has a 5 byte header:
1585 */
1586 ulg max_block_size = 0xffff;
1587 ulg max_start;
1588
1589 if (max_block_size > s->pending_buf_size - 5) {
1590 max_block_size = s->pending_buf_size - 5;
1591 }
1592
1593 /* Copy as much as possible from input to output: */
1594 for (;;) {
1595 /* Fill the window as much as possible: */
1596 if (s->lookahead <= 1) {
1597
1598 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1599 s->block_start >= (long)s->w_size, "slide too late");
1600
1601 fill_window(s);
1602 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1603
1604 if (s->lookahead == 0) break; /* flush the current block */
1605 }
1606 Assert(s->block_start >= 0L, "block gone");
1607
1608 s->strstart += s->lookahead;
1609 s->lookahead = 0;
1610
1611 /* Emit a stored block if pending_buf will be full: */
1612 max_start = s->block_start + max_block_size;
1613 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1614 /* strstart == 0 is possible when wraparound on 16-bit machine */
1615 s->lookahead = (uInt)(s->strstart - max_start);
1616 s->strstart = (uInt)max_start;
1617 FLUSH_BLOCK(s, 0);
1618 }
1619 /* Flush if we may have to slide, otherwise block_start may become
1620 * negative and the data will be gone:
1621 */
1622 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1623 FLUSH_BLOCK(s, 0);
1624 }
1625 }
1626 s->insert = 0;
1627 if (flush == Z_FINISH) {
1628 FLUSH_BLOCK(s, 1);
1629 return finish_done;
1630 }
1631 if ((long)s->strstart > s->block_start)
1632 FLUSH_BLOCK(s, 0);
1633 return block_done;
1634 }
1635
1636 /* ===========================================================================
1637 * Compress as much as possible from the input stream, return the current
1638 * block state.
1639 * This function does not perform lazy evaluation of matches and inserts
1640 * new strings in the dictionary only for unmatched strings or for short
1641 * matches. It is used only for the fast compression options.
1642 */
1643 local block_state deflate_fast(s, flush)
1644 deflate_state *s;
1645 int flush;
1646 {
1647 IPos hash_head; /* head of the hash chain */
1648 int bflush; /* set if current block must be flushed */
1649
1650 for (;;) {
1651 /* Make sure that we always have enough lookahead, except
1652 * at the end of the input file. We need MAX_MATCH bytes
1653 * for the next match, plus MIN_MATCH bytes to insert the
1654 * string following the next match.
1655 */
1656 if (s->lookahead < MIN_LOOKAHEAD) {
1657 fill_window(s);
1658 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1659 return need_more;
1660 }
1661 if (s->lookahead == 0) break; /* flush the current block */
1662 }
1663
1664 /* Insert the string window[strstart .. strstart+2] in the
1665 * dictionary, and set hash_head to the head of the hash chain:
1666 */
1667 hash_head = NIL;
1668 if (s->lookahead >= MIN_MATCH) {
1669 INSERT_STRING(s, s->strstart, hash_head);
1670 }
1671
1672 /* Find the longest match, discarding those <= prev_length.
1673 * At this point we have always match_length < MIN_MATCH
1674 */
1675 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1676 /* To simplify the code, we prevent matches with the string
1677 * of window index 0 (in particular we have to avoid a match
1678 * of the string with itself at the start of the input file).
1679 */
1680 s->match_length = longest_match (s, hash_head);
1681 /* longest_match() sets match_start */
1682 }
1683 if (s->match_length >= MIN_MATCH) {
1684 check_match(s, s->strstart, s->match_start, s->match_length);
1685
1686 _tr_tally_dist(s, s->strstart - s->match_start,
1687 s->match_length - MIN_MATCH, bflush);
1688
1689 s->lookahead -= s->match_length;
1690
1691 /* Insert new strings in the hash table only if the match length
1692 * is not too large. This saves time but degrades compression.
1693 */
1694 #ifndef FASTEST
1695 if (s->match_length <= s->max_insert_length &&
1696 s->lookahead >= MIN_MATCH) {
1697 s->match_length--; /* string at strstart already in table */
1698 do {
1699 s->strstart++;
1700 INSERT_STRING(s, s->strstart, hash_head);
1701 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1702 * always MIN_MATCH bytes ahead.
1703 */
1704 } while (--s->match_length != 0);
1705 s->strstart++;
1706 } else
1707 #endif
1708 {
1709 s->strstart += s->match_length;
1710 s->match_length = 0;
1711 s->ins_h = s->window[s->strstart];
1712 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1713 #if MIN_MATCH != 3
1714 Call UPDATE_HASH() MIN_MATCH-3 more times
1715 #endif
1716 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1717 * matter since it will be recomputed at next deflate call.
1718 */
1719 }
1720 } else {
1721 /* No match, output a literal byte */
1722 Tracevv((stderr,"%c", s->window[s->strstart]));
1723 _tr_tally_lit (s, s->window[s->strstart], bflush);
1724 s->lookahead--;
1725 s->strstart++;
1726 }
1727 if (bflush) FLUSH_BLOCK(s, 0);
1728 }
1729 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1730 if (flush == Z_FINISH) {
1731 FLUSH_BLOCK(s, 1);
1732 return finish_done;
1733 }
1734 if (s->last_lit)
1735 FLUSH_BLOCK(s, 0);
1736 return block_done;
1737 }
1738
1739 #ifndef FASTEST
1740 /* ===========================================================================
1741 * Same as above, but achieves better compression. We use a lazy
1742 * evaluation for matches: a match is finally adopted only if there is
1743 * no better match at the next window position.
1744 */
1745 local block_state deflate_slow(s, flush)
1746 deflate_state *s;
1747 int flush;
1748 {
1749 IPos hash_head; /* head of hash chain */
1750 int bflush; /* set if current block must be flushed */
1751
1752 /* Process the input block. */
1753 for (;;) {
1754 /* Make sure that we always have enough lookahead, except
1755 * at the end of the input file. We need MAX_MATCH bytes
1756 * for the next match, plus MIN_MATCH bytes to insert the
1757 * string following the next match.
1758 */
1759 if (s->lookahead < MIN_LOOKAHEAD) {
1760 fill_window(s);
1761 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1762 return need_more;
1763 }
1764 if (s->lookahead == 0) break; /* flush the current block */
1765 }
1766
1767 /* Insert the string window[strstart .. strstart+2] in the
1768 * dictionary, and set hash_head to the head of the hash chain:
1769 */
1770 hash_head = NIL;
1771 if (s->lookahead >= MIN_MATCH) {
1772 INSERT_STRING(s, s->strstart, hash_head);
1773 }
1774
1775 /* Find the longest match, discarding those <= prev_length.
1776 */
1777 s->prev_length = s->match_length, s->prev_match = s->match_start;
1778 s->match_length = MIN_MATCH-1;
1779
1780 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1781 s->strstart - hash_head <= MAX_DIST(s)) {
1782 /* To simplify the code, we prevent matches with the string
1783 * of window index 0 (in particular we have to avoid a match
1784 * of the string with itself at the start of the input file).
1785 */
1786 s->match_length = longest_match (s, hash_head);
1787 /* longest_match() sets match_start */
1788
1789 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1790 #if TOO_FAR <= 32767
1791 || (s->match_length == MIN_MATCH &&
1792 s->strstart - s->match_start > TOO_FAR)
1793 #endif
1794 )) {
1795
1796 /* If prev_match is also MIN_MATCH, match_start is garbage
1797 * but we will ignore the current match anyway.
1798 */
1799 s->match_length = MIN_MATCH-1;
1800 }
1801 }
1802 /* If there was a match at the previous step and the current
1803 * match is not better, output the previous match:
1804 */
1805 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1806 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1807 /* Do not insert strings in hash table beyond this. */
1808
1809 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1810
1811 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1812 s->prev_length - MIN_MATCH, bflush);
1813
1814 /* Insert in hash table all strings up to the end of the match.
1815 * strstart-1 and strstart are already inserted. If there is not
1816 * enough lookahead, the last two strings are not inserted in
1817 * the hash table.
1818 */
1819 s->lookahead -= s->prev_length-1;
1820 s->prev_length -= 2;
1821 do {
1822 if (++s->strstart <= max_insert) {
1823 INSERT_STRING(s, s->strstart, hash_head);
1824 }
1825 } while (--s->prev_length != 0);
1826 s->match_available = 0;
1827 s->match_length = MIN_MATCH-1;
1828 s->strstart++;
1829
1830 if (bflush) FLUSH_BLOCK(s, 0);
1831
1832 } else if (s->match_available) {
1833 /* If there was no match at the previous position, output a
1834 * single literal. If there was a match but the current match
1835 * is longer, truncate the previous match to a single literal.
1836 */
1837 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1838 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1839 if (bflush) {
1840 FLUSH_BLOCK_ONLY(s, 0);
1841 }
1842 s->strstart++;
1843 s->lookahead--;
1844 if (s->strm->avail_out == 0) return need_more;
1845 } else {
1846 /* There is no previous match to compare with, wait for
1847 * the next step to decide.
1848 */
1849 s->match_available = 1;
1850 s->strstart++;
1851 s->lookahead--;
1852 }
1853 }
1854 Assert (flush != Z_NO_FLUSH, "no flush?");
1855 if (s->match_available) {
1856 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1857 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1858 s->match_available = 0;
1859 }
1860 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1861 if (flush == Z_FINISH) {
1862 FLUSH_BLOCK(s, 1);
1863 return finish_done;
1864 }
1865 if (s->last_lit)
1866 FLUSH_BLOCK(s, 0);
1867 return block_done;
1868 }
1869 #endif /* FASTEST */
1870
1871 /* ===========================================================================
1872 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1873 * one. Do not maintain a hash table. (It will be regenerated if this run of
1874 * deflate switches away from Z_RLE.)
1875 */
1876 local block_state deflate_rle(s, flush)
1877 deflate_state *s;
1878 int flush;
1879 {
1880 int bflush; /* set if current block must be flushed */
1881 uInt prev; /* byte at distance one to match */
1882 Bytef *scan, *strend; /* scan goes up to strend for length of run */
1883
1884 for (;;) {
1885 /* Make sure that we always have enough lookahead, except
1886 * at the end of the input file. We need MAX_MATCH bytes
1887 * for the longest run, plus one for the unrolled loop.
1888 */
1889 if (s->lookahead <= MAX_MATCH) {
1890 fill_window(s);
1891 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
1892 return need_more;
1893 }
1894 if (s->lookahead == 0) break; /* flush the current block */
1895 }
1896
1897 /* See how many times the previous byte repeats */
1898 s->match_length = 0;
1899 if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
1900 scan = s->window + s->strstart - 1;
1901 prev = *scan;
1902 if (prev == *++scan && prev == *++scan && prev == *++scan) {
1903 strend = s->window + s->strstart + MAX_MATCH;
1904 do {
1905 } while (prev == *++scan && prev == *++scan &&
1906 prev == *++scan && prev == *++scan &&
1907 prev == *++scan && prev == *++scan &&
1908 prev == *++scan && prev == *++scan &&
1909 scan < strend);
1910 s->match_length = MAX_MATCH - (int)(strend - scan);
1911 if (s->match_length > s->lookahead)
1912 s->match_length = s->lookahead;
1913 }
1914 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
1915 }
1916
1917 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1918 if (s->match_length >= MIN_MATCH) {
1919 check_match(s, s->strstart, s->strstart - 1, s->match_length);
1920
1921 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
1922
1923 s->lookahead -= s->match_length;
1924 s->strstart += s->match_length;
1925 s->match_length = 0;
1926 } else {
1927 /* No match, output a literal byte */
1928 Tracevv((stderr,"%c", s->window[s->strstart]));
1929 _tr_tally_lit (s, s->window[s->strstart], bflush);
1930 s->lookahead--;
1931 s->strstart++;
1932 }
1933 if (bflush) FLUSH_BLOCK(s, 0);
1934 }
1935 s->insert = 0;
1936 if (flush == Z_FINISH) {
1937 FLUSH_BLOCK(s, 1);
1938 return finish_done;
1939 }
1940 if (s->last_lit)
1941 FLUSH_BLOCK(s, 0);
1942 return block_done;
1943 }
1944
1945 /* ===========================================================================
1946 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
1947 * (It will be regenerated if this run of deflate switches away from Huffman.)
1948 */
1949 local block_state deflate_huff(s, flush)
1950 deflate_state *s;
1951 int flush;
1952 {
1953 int bflush; /* set if current block must be flushed */
1954
1955 for (;;) {
1956 /* Make sure that we have a literal to write. */
1957 if (s->lookahead == 0) {
1958 fill_window(s);
1959 if (s->lookahead == 0) {
1960 if (flush == Z_NO_FLUSH)
1961 return need_more;
1962 break; /* flush the current block */
1963 }
1964 }
1965
1966 /* Output a literal byte */
1967 s->match_length = 0;
1968 Tracevv((stderr,"%c", s->window[s->strstart]));
1969 _tr_tally_lit (s, s->window[s->strstart], bflush);
1970 s->lookahead--;
1971 s->strstart++;
1972 if (bflush) FLUSH_BLOCK(s, 0);
1973 }
1974 s->insert = 0;
1975 if (flush == Z_FINISH) {
1976 FLUSH_BLOCK(s, 1);
1977 return finish_done;
1978 }
1979 if (s->last_lit)
1980 FLUSH_BLOCK(s, 0);
1981 return block_done;
1982 }
1983 #endif /* ! LONGEST_MATCH_ONLY */