1 /* deflate.c -- compress data using the deflation algorithm
2 * Copyright (C) 1995-2017 Jean-loup Gailly and Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6 /*
7 * ALGORITHM
8 *
9 * The "deflation" process depends on being able to identify portions
10 * of the input text which are identical to earlier input (within a
11 * sliding window trailing behind the input currently being processed).
12 *
13 * The most straightforward technique turns out to be the fastest for
14 * most input files: try all possible matches and select the longest.
15 * The key feature of this algorithm is that insertions into the string
16 * dictionary are very simple and thus fast, and deletions are avoided
17 * completely. Insertions are performed at each input character, whereas
18 * string matches are performed only when the previous match ends. So it
19 * is preferable to spend more time in matches to allow very fast string
20 * insertions and avoid deletions. The matching algorithm for small
21 * strings is inspired from that of Rabin & Karp. A brute force approach
22 * is used to find longer strings when a small match has been found.
23 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
24 * (by Leonid Broukhis).
25 * A previous version of this file used a more sophisticated algorithm
26 * (by Fiala and Greene) which is guaranteed to run in linear amortized
27 * time, but has a larger average cost, uses more memory and is patented.
28 * However the F&G algorithm may be faster for some highly redundant
29 * files if the parameter max_chain_length (described below) is too large.
30 *
31 * ACKNOWLEDGEMENTS
32 *
33 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
34 * I found it in 'freeze' written by Leonid Broukhis.
35 * Thanks to many people for bug reports and testing.
36 *
37 * REFERENCES
38 *
39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40 * Available in http://tools.ietf.org/html/rfc1951
41 *
42 * A description of the Rabin and Karp algorithm is given in the book
43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
44 *
45 * Fiala,E.R., and Greene,D.H.
46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
47 *
48 */
49
50 #include "deflate.h"
51
52 const char deflate_copyright[] =
53 " deflate 1.2.11 Copyright 1995-2017 Jean-loup Gailly and Mark Adler ";
54 /*
55 If you use the zlib library in a product, an acknowledgment is welcome
56 in the documentation of your product. If for some reason you cannot
57 include such an acknowledgment, I would appreciate that you keep this
58 copyright string in the executable of your product.
59 */
60
61 /* ===========================================================================
62 * Function prototypes.
63 */
64 typedef enum {
65 need_more, /* block not completed, need more input or more output */
66 block_done, /* block flush performed */
67 finish_started, /* finish started, need only more output at next deflate */
68 finish_done /* finish done, accept no more input or output */
69 } block_state;
70
71 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
72 /* Compression function. Returns the block state after the call. */
73
74 local int deflateStateCheck OF((z_streamp strm));
75 local void slide_hash OF((deflate_state *s));
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 unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
88 #ifdef ASMV
89 # pragma message("Assembler code may have bugs -- use at your own risk")
90 void match_init OF((void)); /* asm code initialization */
91 uInt longest_match OF((deflate_state *s, IPos cur_match));
92 #else
93 local uInt longest_match OF((deflate_state *s, IPos cur_match));
94 #endif
95
96 #ifdef ZLIB_DEBUG
97 local void check_match OF((deflate_state *s, IPos start, IPos match,
98 int length));
99 #endif
100
101 /* ===========================================================================
102 * Local data
103 */
104
105 #define NIL 0
106 /* Tail of hash chains */
107
108 #ifndef TOO_FAR
109 # define TOO_FAR 4096
110 #endif
111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
112
113 /* Values for max_lazy_match, good_match and max_chain_length, depending on
114 * the desired pack level (0..9). The values given below have been tuned to
115 * exclude worst case performance for pathological files. Better values may be
116 * found for specific files.
117 */
118 typedef struct config_s {
119 ush good_length; /* reduce lazy search above this match length */
120 ush max_lazy; /* do not perform lazy search above this match length */
121 ush nice_length; /* quit search above this match length */
122 ush max_chain;
123 compress_func func;
124 } config;
125
126 #ifdef FASTEST
127 local const config configuration_table[2] = {
128 /* good lazy nice chain */
129 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
130 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
131 #else
132 local const config configuration_table[10] = {
133 /* good lazy nice chain */
134 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
135 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
136 /* 2 */ {4, 5, 16, 8, deflate_fast},
137 /* 3 */ {4, 6, 32, 32, deflate_fast},
138
139 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
140 /* 5 */ {8, 16, 32, 32, deflate_slow},
141 /* 6 */ {8, 16, 128, 128, deflate_slow},
142 /* 7 */ {8, 32, 128, 256, deflate_slow},
143 /* 8 */ {32, 128, 258, 1024, deflate_slow},
144 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
145 #endif
146
147 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
148 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
149 * meaning.
150 */
151
152 /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
153 #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0))
154
155 /* ===========================================================================
156 * Update a hash value with the given input byte
157 * IN assertion: all calls to UPDATE_HASH are made with consecutive input
158 * characters, so that a running hash key can be computed from the previous
159 * key instead of complete recalculation each time.
160 */
161 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
162
163
164 /* ===========================================================================
165 * Insert string str in the dictionary and set match_head to the previous head
166 * of the hash chain (the most recent string with same hash key). Return
167 * the previous length of the hash chain.
168 * If this file is compiled with -DFASTEST, the compression level is forced
169 * to 1, and no hash chains are maintained.
170 * IN assertion: all calls to INSERT_STRING are made with consecutive input
171 * characters and the first MIN_MATCH bytes of str are valid (except for
172 * the last MIN_MATCH-1 bytes of the input file).
173 */
174 #ifdef FASTEST
175 #define INSERT_STRING(s, str, match_head) \
176 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
177 match_head = s->head[s->ins_h], \
178 s->head[s->ins_h] = (Pos)(str))
179 #else
180 #define INSERT_STRING(s, str, match_head) \
181 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
182 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
183 s->head[s->ins_h] = (Pos)(str))
184 #endif
185
186 /* ===========================================================================
187 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
188 * prev[] will be initialized on the fly.
189 */
190 #define CLEAR_HASH(s) \
191 do { \
192 s->head[s->hash_size-1] = NIL; \
193 zmemzero((Bytef *)s->head, \
194 (unsigned)(s->hash_size-1)*sizeof(*s->head)); \
195 } while (0)
196
197 /* ===========================================================================
198 * Slide the hash table when sliding the window down (could be avoided with 32
199 * bit values at the expense of memory usage). We slide even when level == 0 to
200 * keep the hash table consistent if we switch back to level > 0 later.
201 */
202 local void slide_hash(s)
203 deflate_state *s;
204 {
205 unsigned n, m;
206 Posf *p;
207 uInt wsize = s->w_size;
208
209 n = s->hash_size;
210 p = &s->head[n];
211 do {
212 m = *--p;
213 *p = (Pos)(m >= wsize ? m - wsize : NIL);
214 } while (--n);
215 n = wsize;
216 #ifndef FASTEST
217 p = &s->prev[n];
218 do {
219 m = *--p;
220 *p = (Pos)(m >= wsize ? m - wsize : NIL);
221 /* If n is not on any hash chain, prev[n] is garbage but
222 * its value will never be used.
223 */
224 } while (--n);
225 #endif
226 }
227
228 /* ========================================================================= */
229 int ZEXPORT deflateInit_(strm, level, version, stream_size)
230 z_streamp strm;
231 int level;
232 const char *version;
233 int stream_size;
234 {
235 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
236 Z_DEFAULT_STRATEGY, version, stream_size);
237 /* To do: ignore strm->next_in if we use it as window */
238 }
239
240 /* ========================================================================= */
241 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
242 version, stream_size)
243 z_streamp strm;
244 int level;
245 int method;
246 int windowBits;
247 int memLevel;
248 int strategy;
249 const char *version;
250 int stream_size;
251 {
252 deflate_state *s;
253 int wrap = 1;
254 static const char my_version[] = ZLIB_VERSION;
255
256 ushf *overlay;
257 /* We overlay pending_buf and d_buf+l_buf. This works since the average
258 * output size for (length,distance) codes is <= 24 bits.
259 */
260
261 if (version == Z_NULL || version[0] != my_version[0] ||
262 stream_size != sizeof(z_stream)) {
263 return Z_VERSION_ERROR;
264 }
265 if (strm == Z_NULL) return Z_STREAM_ERROR;
266
267 strm->msg = Z_NULL;
268 if (strm->zalloc == (alloc_func)0) {
269 #ifdef Z_SOLO
270 return Z_STREAM_ERROR;
271 #else
272 strm->zalloc = zcalloc;
273 strm->opaque = (voidpf)0;
274 #endif
275 }
276 if (strm->zfree == (free_func)0)
277 #ifdef Z_SOLO
278 return Z_STREAM_ERROR;
279 #else
280 strm->zfree = zcfree;
281 #endif
282
283 #ifdef FASTEST
284 if (level != 0) level = 1;
285 #else
286 if (level == Z_DEFAULT_COMPRESSION) level = 6;
287 #endif
288
289 if (windowBits < 0) { /* suppress zlib wrapper */
290 wrap = 0;
291 windowBits = -windowBits;
292 }
293 #ifdef GZIP
294 else if (windowBits > 15) {
295 wrap = 2; /* write gzip wrapper instead */
296 windowBits -= 16;
297 }
298 #endif
299 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
300 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
301 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) {
302 return Z_STREAM_ERROR;
303 }
304 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
305 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
306 if (s == Z_NULL) return Z_MEM_ERROR;
307 strm->state = (struct internal_state FAR *)s;
308 s->strm = strm;
309 s->status = INIT_STATE; /* to pass state test in deflateReset() */
310
311 s->wrap = wrap;
312 s->gzhead = Z_NULL;
313 s->w_bits = (uInt)windowBits;
314 s->w_size = 1 << s->w_bits;
315 s->w_mask = s->w_size - 1;
316
317 s->hash_bits = (uInt)memLevel + 7;
318 s->hash_size = 1 << s->hash_bits;
319 s->hash_mask = s->hash_size - 1;
320 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
321
322 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
323 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
324 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
325
326 s->high_water = 0; /* nothing written to s->window yet */
327
328 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
329
330 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
331 s->pending_buf = (uchf *) overlay;
332 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
333
334 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
335 s->pending_buf == Z_NULL) {
336 s->status = FINISH_STATE;
337 strm->msg = ERR_MSG(Z_MEM_ERROR);
338 deflateEnd (strm);
339 return Z_MEM_ERROR;
340 }
341 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
342 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
343
344 s->level = level;
345 s->strategy = strategy;
346 s->method = (Byte)method;
347
348 return deflateReset(strm);
349 }
350
351 /* =========================================================================
352 * Check for a valid deflate stream state. Return 0 if ok, 1 if not.
353 */
354 local int deflateStateCheck (strm)
355 z_streamp strm;
356 {
357 deflate_state *s;
358 if (strm == Z_NULL ||
359 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0)
360 return 1;
361 s = strm->state;
362 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE &&
363 #ifdef GZIP
364 s->status != GZIP_STATE &&
365 #endif
366 s->status != EXTRA_STATE &&
367 s->status != NAME_STATE &&
368 s->status != COMMENT_STATE &&
369 s->status != HCRC_STATE &&
370 s->status != BUSY_STATE &&
371 s->status != FINISH_STATE))
372 return 1;
373 return 0;
374 }
375
376 /* ========================================================================= */
377 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
378 z_streamp strm;
379 const Bytef *dictionary;
380 uInt dictLength;
381 {
382 deflate_state *s;
383 uInt str, n;
384 int wrap;
385 unsigned avail;
386 z_const unsigned char *next;
387
388 if (deflateStateCheck(strm) || dictionary == Z_NULL)
389 return Z_STREAM_ERROR;
390 s = strm->state;
391 wrap = s->wrap;
392 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
393 return Z_STREAM_ERROR;
394
395 /* when using zlib wrappers, compute Adler-32 for provided dictionary */
396 if (wrap == 1)
397 strm->adler = adler32(strm->adler, dictionary, dictLength);
398 s->wrap = 0; /* avoid computing Adler-32 in read_buf */
399
400 /* if dictionary would fill window, just replace the history */
401 if (dictLength >= s->w_size) {
402 if (wrap == 0) { /* already empty otherwise */
403 CLEAR_HASH(s);
404 s->strstart = 0;
405 s->block_start = 0L;
406 s->insert = 0;
407 }
408 dictionary += dictLength - s->w_size; /* use the tail */
409 dictLength = s->w_size;
410 }
411
412 /* insert dictionary into window and hash */
413 avail = strm->avail_in;
414 next = strm->next_in;
415 strm->avail_in = dictLength;
416 strm->next_in = (z_const Bytef *)dictionary;
417 fill_window(s);
418 while (s->lookahead >= MIN_MATCH) {
419 str = s->strstart;
420 n = s->lookahead - (MIN_MATCH-1);
421 do {
422 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
423 #ifndef FASTEST
424 s->prev[str & s->w_mask] = s->head[s->ins_h];
425 #endif
426 s->head[s->ins_h] = (Pos)str;
427 str++;
428 } while (--n);
429 s->strstart = str;
430 s->lookahead = MIN_MATCH-1;
431 fill_window(s);
432 }
433 s->strstart += s->lookahead;
434 s->block_start = (long)s->strstart;
435 s->insert = s->lookahead;
436 s->lookahead = 0;
437 s->match_length = s->prev_length = MIN_MATCH-1;
438 s->match_available = 0;
439 strm->next_in = next;
440 strm->avail_in = avail;
441 s->wrap = wrap;
442 return Z_OK;
443 }
444
445 /* ========================================================================= */
446 int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength)
447 z_streamp strm;
448 Bytef *dictionary;
449 uInt *dictLength;
450 {
451 deflate_state *s;
452 uInt len;
453
454 if (deflateStateCheck(strm))
455 return Z_STREAM_ERROR;
456 s = strm->state;
457 len = s->strstart + s->lookahead;
458 if (len > s->w_size)
459 len = s->w_size;
460 if (dictionary != Z_NULL && len)
461 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len);
462 if (dictLength != Z_NULL)
463 *dictLength = len;
464 return Z_OK;
465 }
466
467 /* ========================================================================= */
468 int ZEXPORT deflateResetKeep (strm)
469 z_streamp strm;
470 {
471 deflate_state *s;
472
473 if (deflateStateCheck(strm)) {
474 return Z_STREAM_ERROR;
475 }
476
477 strm->total_in = strm->total_out = 0;
478 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
479 strm->data_type = Z_UNKNOWN;
480
481 s = (deflate_state *)strm->state;
482 s->pending = 0;
483 s->pending_out = s->pending_buf;
484
485 if (s->wrap < 0) {
486 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
487 }
488 s->status =
489 #ifdef GZIP
490 s->wrap == 2 ? GZIP_STATE :
491 #endif
492 s->wrap ? INIT_STATE : BUSY_STATE;
493 strm->adler =
494 #ifdef GZIP
495 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
496 #endif
497 adler32(0L, Z_NULL, 0);
498 s->last_flush = Z_NO_FLUSH;
499
500 _tr_init(s);
501
502 return Z_OK;
503 }
504
505 /* ========================================================================= */
506 int ZEXPORT deflateReset (strm)
507 z_streamp strm;
508 {
509 int ret;
510
511 ret = deflateResetKeep(strm);
512 if (ret == Z_OK)
513 lm_init(strm->state);
514 return ret;
515 }
516
517 /* ========================================================================= */
518 int ZEXPORT deflateSetHeader (strm, head)
519 z_streamp strm;
520 gz_headerp head;
521 {
522 if (deflateStateCheck(strm) || strm->state->wrap != 2)
523 return Z_STREAM_ERROR;
524 strm->state->gzhead = head;
525 return Z_OK;
526 }
527
528 /* ========================================================================= */
529 int ZEXPORT deflatePending (strm, pending, bits)
530 unsigned *pending;
531 int *bits;
532 z_streamp strm;
533 {
534 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
535 if (pending != Z_NULL)
536 *pending = strm->state->pending;
537 if (bits != Z_NULL)
538 *bits = strm->state->bi_valid;
539 return Z_OK;
540 }
541
542 /* ========================================================================= */
543 int ZEXPORT deflatePrime (strm, bits, value)
544 z_streamp strm;
545 int bits;
546 int value;
547 {
548 deflate_state *s;
549 int put;
550
551 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
552 s = strm->state;
553 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
554 return Z_BUF_ERROR;
555 do {
556 put = Buf_size - s->bi_valid;
557 if (put > bits)
558 put = bits;
559 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
560 s->bi_valid += put;
561 _tr_flush_bits(s);
562 value >>= put;
563 bits -= put;
564 } while (bits);
565 return Z_OK;
566 }
567
568 /* ========================================================================= */
569 int ZEXPORT deflateParams(strm, level, strategy)
570 z_streamp strm;
571 int level;
572 int strategy;
573 {
574 deflate_state *s;
575 compress_func func;
576
577 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
578 s = strm->state;
579
580 #ifdef FASTEST
581 if (level != 0) level = 1;
582 #else
583 if (level == Z_DEFAULT_COMPRESSION) level = 6;
584 #endif
585 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
586 return Z_STREAM_ERROR;
587 }
588 func = configuration_table[s->level].func;
589
590 if ((strategy != s->strategy || func != configuration_table[level].func) &&
591 s->high_water) {
592 /* Flush the last buffer: */
593 int err = deflate(strm, Z_BLOCK);
594 if (err == Z_STREAM_ERROR)
595 return err;
596 if (strm->avail_out == 0)
597 return Z_BUF_ERROR;
598 }
599 if (s->level != level) {
600 if (s->level == 0 && s->matches != 0) {
601 if (s->matches == 1)
602 slide_hash(s);
603 else
604 CLEAR_HASH(s);
605 s->matches = 0;
606 }
607 s->level = level;
608 s->max_lazy_match = configuration_table[level].max_lazy;
609 s->good_match = configuration_table[level].good_length;
610 s->nice_match = configuration_table[level].nice_length;
611 s->max_chain_length = configuration_table[level].max_chain;
612 }
613 s->strategy = strategy;
614 return Z_OK;
615 }
616
617 /* ========================================================================= */
618 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
619 z_streamp strm;
620 int good_length;
621 int max_lazy;
622 int nice_length;
623 int max_chain;
624 {
625 deflate_state *s;
626
627 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
628 s = strm->state;
629 s->good_match = (uInt)good_length;
630 s->max_lazy_match = (uInt)max_lazy;
631 s->nice_match = nice_length;
632 s->max_chain_length = (uInt)max_chain;
633 return Z_OK;
634 }
635
636 /* =========================================================================
637 * For the default windowBits of 15 and memLevel of 8, this function returns
638 * a close to exact, as well as small, upper bound on the compressed size.
639 * They are coded as constants here for a reason--if the #define's are
640 * changed, then this function needs to be changed as well. The return
641 * value for 15 and 8 only works for those exact settings.
642 *
643 * For any setting other than those defaults for windowBits and memLevel,
644 * the value returned is a conservative worst case for the maximum expansion
645 * resulting from using fixed blocks instead of stored blocks, which deflate
646 * can emit on compressed data for some combinations of the parameters.
647 *
648 * This function could be more sophisticated to provide closer upper bounds for
649 * every combination of windowBits and memLevel. But even the conservative
650 * upper bound of about 14% expansion does not seem onerous for output buffer
651 * allocation.
652 */
653 uLong ZEXPORT deflateBound(strm, sourceLen)
654 z_streamp strm;
655 uLong sourceLen;
656 {
657 deflate_state *s;
658 uLong complen, wraplen;
659
660 /* conservative upper bound for compressed data */
661 complen = sourceLen +
662 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
663
664 /* if can't get parameters, return conservative bound plus zlib wrapper */
665 if (deflateStateCheck(strm))
666 return complen + 6;
667
668 /* compute wrapper length */
669 s = strm->state;
670 switch (s->wrap) {
671 case 0: /* raw deflate */
672 wraplen = 0;
673 break;
674 case 1: /* zlib wrapper */
675 wraplen = 6 + (s->strstart ? 4 : 0);
676 break;
677 #ifdef GZIP
678 case 2: /* gzip wrapper */
679 wraplen = 18;
680 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
681 Bytef *str;
682 if (s->gzhead->extra != Z_NULL)
683 wraplen += 2 + s->gzhead->extra_len;
684 str = s->gzhead->name;
685 if (str != Z_NULL)
686 do {
687 wraplen++;
688 } while (*str++);
689 str = s->gzhead->comment;
690 if (str != Z_NULL)
691 do {
692 wraplen++;
693 } while (*str++);
694 if (s->gzhead->hcrc)
695 wraplen += 2;
696 }
697 break;
698 #endif
699 default: /* for compiler happiness */
700 wraplen = 6;
701 }
702
703 /* if not default parameters, return conservative bound */
704 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
705 return complen + wraplen;
706
707 /* default settings: return tight bound for that case */
708 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
709 (sourceLen >> 25) + 13 - 6 + wraplen;
710 }
711
712 /* =========================================================================
713 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
714 * IN assertion: the stream state is correct and there is enough room in
715 * pending_buf.
716 */
717 local void putShortMSB (s, b)
718 deflate_state *s;
719 uInt b;
720 {
721 put_byte(s, (Byte)(b >> 8));
722 put_byte(s, (Byte)(b & 0xff));
723 }
724
725 /* =========================================================================
726 * Flush as much pending output as possible. All deflate() output, except for
727 * some deflate_stored() output, goes through this function so some
728 * applications may wish to modify it to avoid allocating a large
729 * strm->next_out buffer and copying into it. (See also read_buf()).
730 */
731 local void flush_pending(strm)
732 z_streamp strm;
733 {
734 unsigned len;
735 deflate_state *s = strm->state;
736
737 _tr_flush_bits(s);
738 len = s->pending;
739 if (len > strm->avail_out) len = strm->avail_out;
740 if (len == 0) return;
741
742 zmemcpy(strm->next_out, s->pending_out, len);
743 strm->next_out += len;
744 s->pending_out += len;
745 strm->total_out += len;
746 strm->avail_out -= len;
747 s->pending -= len;
748 if (s->pending == 0) {
749 s->pending_out = s->pending_buf;
750 }
751 }
752
753 /* ===========================================================================
754 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1].
755 */
756 #define HCRC_UPDATE(beg) \
757 do { \
758 if (s->gzhead->hcrc && s->pending > (beg)) \
759 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \
760 s->pending - (beg)); \
761 } while (0)
762
763 /* ========================================================================= */
764 int ZEXPORT deflate (strm, flush)
765 z_streamp strm;
766 int flush;
767 {
768 int old_flush; /* value of flush param for previous deflate call */
769 deflate_state *s;
770
771 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) {
772 return Z_STREAM_ERROR;
773 }
774 s = strm->state;
775
776 if (strm->next_out == Z_NULL ||
777 (strm->avail_in != 0 && strm->next_in == Z_NULL) ||
778 (s->status == FINISH_STATE && flush != Z_FINISH)) {
779 ERR_RETURN(strm, Z_STREAM_ERROR);
780 }
781 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
782
783 old_flush = s->last_flush;
784 s->last_flush = flush;
785
786 /* Flush as much pending output as possible */
787 if (s->pending != 0) {
788 flush_pending(strm);
789 if (strm->avail_out == 0) {
790 /* Since avail_out is 0, deflate will be called again with
791 * more output space, but possibly with both pending and
792 * avail_in equal to zero. There won't be anything to do,
793 * but this is not an error situation so make sure we
794 * return OK instead of BUF_ERROR at next call of deflate:
795 */
796 s->last_flush = -1;
797 return Z_OK;
798 }
799
800 /* Make sure there is something to do and avoid duplicate consecutive
801 * flushes. For repeated and useless calls with Z_FINISH, we keep
802 * returning Z_STREAM_END instead of Z_BUF_ERROR.
803 */
804 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
805 flush != Z_FINISH) {
806 ERR_RETURN(strm, Z_BUF_ERROR);
807 }
808
809 /* User must not provide more input after the first FINISH: */
810 if (s->status == FINISH_STATE && strm->avail_in != 0) {
811 ERR_RETURN(strm, Z_BUF_ERROR);
812 }
813
814 /* Write the header */
815 if (s->status == INIT_STATE) {
816 /* zlib header */
817 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
818 uInt level_flags;
819
820 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
821 level_flags = 0;
822 else if (s->level < 6)
823 level_flags = 1;
824 else if (s->level == 6)
825 level_flags = 2;
826 else
827 level_flags = 3;
828 header |= (level_flags << 6);
829 if (s->strstart != 0) header |= PRESET_DICT;
830 header += 31 - (header % 31);
831
832 putShortMSB(s, header);
833
834 /* Save the adler32 of the preset dictionary: */
835 if (s->strstart != 0) {
836 putShortMSB(s, (uInt)(strm->adler >> 16));
837 putShortMSB(s, (uInt)(strm->adler & 0xffff));
838 }
839 strm->adler = adler32(0L, Z_NULL, 0);
840 s->status = BUSY_STATE;
841
842 /* Compression must start with an empty pending buffer */
843 flush_pending(strm);
844 if (s->pending != 0) {
845 s->last_flush = -1;
846 return Z_OK;
847 }
848 }
849 #ifdef GZIP
850 if (s->status == GZIP_STATE) {
851 /* gzip header */
852 strm->adler = crc32(0L, Z_NULL, 0);
853 put_byte(s, 31);
854 put_byte(s, 139);
855 put_byte(s, 8);
856 if (s->gzhead == Z_NULL) {
857 put_byte(s, 0);
858 put_byte(s, 0);
859 put_byte(s, 0);
860 put_byte(s, 0);
861 put_byte(s, 0);
862 put_byte(s, s->level == 9 ? 2 :
863 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
864 4 : 0));
865 put_byte(s, OS_CODE);
866 s->status = BUSY_STATE;
867
868 /* Compression must start with an empty pending buffer */
869 flush_pending(strm);
870 if (s->pending != 0) {
871 s->last_flush = -1;
872 return Z_OK;
873 }
874 }
875 else {
876 put_byte(s, (s->gzhead->text ? 1 : 0) +
877 (s->gzhead->hcrc ? 2 : 0) +
878 (s->gzhead->extra == Z_NULL ? 0 : 4) +
879 (s->gzhead->name == Z_NULL ? 0 : 8) +
880 (s->gzhead->comment == Z_NULL ? 0 : 16)
881 );
882 put_byte(s, (Byte)(s->gzhead->time & 0xff));
883 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
884 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
885 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
886 put_byte(s, s->level == 9 ? 2 :
887 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
888 4 : 0));
889 put_byte(s, s->gzhead->os & 0xff);
890 if (s->gzhead->extra != Z_NULL) {
891 put_byte(s, s->gzhead->extra_len & 0xff);
892 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
893 }
894 if (s->gzhead->hcrc)
895 strm->adler = crc32(strm->adler, s->pending_buf,
896 s->pending);
897 s->gzindex = 0;
898 s->status = EXTRA_STATE;
899 }
900 }
901 if (s->status == EXTRA_STATE) {
902 if (s->gzhead->extra != Z_NULL) {
903 ulg beg = s->pending; /* start of bytes to update crc */
904 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex;
905 while (s->pending + left > s->pending_buf_size) {
906 uInt copy = s->pending_buf_size - s->pending;
907 zmemcpy(s->pending_buf + s->pending,
908 s->gzhead->extra + s->gzindex, copy);
909 s->pending = s->pending_buf_size;
910 HCRC_UPDATE(beg);
911 s->gzindex += copy;
912 flush_pending(strm);
913 if (s->pending != 0) {
914 s->last_flush = -1;
915 return Z_OK;
916 }
917 beg = 0;
918 left -= copy;
919 }
920 zmemcpy(s->pending_buf + s->pending,
921 s->gzhead->extra + s->gzindex, left);
922 s->pending += left;
923 HCRC_UPDATE(beg);
924 s->gzindex = 0;
925 }
926 s->status = NAME_STATE;
927 }
928 if (s->status == NAME_STATE) {
929 if (s->gzhead->name != Z_NULL) {
930 ulg beg = s->pending; /* start of bytes to update crc */
931 int val;
932 do {
933 if (s->pending == s->pending_buf_size) {
934 HCRC_UPDATE(beg);
935 flush_pending(strm);
936 if (s->pending != 0) {
937 s->last_flush = -1;
938 return Z_OK;
939 }
940 beg = 0;
941 }
942 val = s->gzhead->name[s->gzindex++];
943 put_byte(s, val);
944 } while (val != 0);
945 HCRC_UPDATE(beg);
946 s->gzindex = 0;
947 }
948 s->status = COMMENT_STATE;
949 }
950 if (s->status == COMMENT_STATE) {
951 if (s->gzhead->comment != Z_NULL) {
952 ulg beg = s->pending; /* start of bytes to update crc */
953 int val;
954 do {
955 if (s->pending == s->pending_buf_size) {
956 HCRC_UPDATE(beg);
957 flush_pending(strm);
958 if (s->pending != 0) {
959 s->last_flush = -1;
960 return Z_OK;
961 }
962 beg = 0;
963 }
964 val = s->gzhead->comment[s->gzindex++];
965 put_byte(s, val);
966 } while (val != 0);
967 HCRC_UPDATE(beg);
968 }
969 s->status = HCRC_STATE;
970 }
971 if (s->status == HCRC_STATE) {
972 if (s->gzhead->hcrc) {
973 if (s->pending + 2 > s->pending_buf_size) {
974 flush_pending(strm);
975 if (s->pending != 0) {
976 s->last_flush = -1;
977 return Z_OK;
978 }
979 }
980 put_byte(s, (Byte)(strm->adler & 0xff));
981 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
982 strm->adler = crc32(0L, Z_NULL, 0);
983 }
984 s->status = BUSY_STATE;
985
986 /* Compression must start with an empty pending buffer */
987 flush_pending(strm);
988 if (s->pending != 0) {
989 s->last_flush = -1;
990 return Z_OK;
991 }
992 }
993 #endif
994
995 /* Start a new block or continue the current one.
996 */
997 if (strm->avail_in != 0 || s->lookahead != 0 ||
998 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
999 block_state bstate;
1000
1001 bstate = s->level == 0 ? deflate_stored(s, flush) :
1002 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
1003 s->strategy == Z_RLE ? deflate_rle(s, flush) :
1004 (*(configuration_table[s->level].func))(s, flush);
1005
1006 if (bstate == finish_started || bstate == finish_done) {
1007 s->status = FINISH_STATE;
1008 }
1009 if (bstate == need_more || bstate == finish_started) {
1010 if (strm->avail_out == 0) {
1011 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
1012 }
1013 return Z_OK;
1014 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
1015 * of deflate should use the same flush parameter to make sure
1016 * that the flush is complete. So we don't have to output an
1017 * empty block here, this will be done at next call. This also
1018 * ensures that for a very small output buffer, we emit at most
1019 * one empty block.
1020 */
1021 }
1022 if (bstate == block_done) {
1023 if (flush == Z_PARTIAL_FLUSH) {
1024 _tr_align(s);
1025 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
1026 _tr_stored_block(s, (char*)0, 0L, 0);
1027 /* For a full flush, this empty block will be recognized
1028 * as a special marker by inflate_sync().
1029 */
1030 if (flush == Z_FULL_FLUSH) {
1031 CLEAR_HASH(s); /* forget history */
1032 if (s->lookahead == 0) {
1033 s->strstart = 0;
1034 s->block_start = 0L;
1035 s->insert = 0;
1036 }
1037 }
1038 }
1039 flush_pending(strm);
1040 if (strm->avail_out == 0) {
1041 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
1042 return Z_OK;
1043 }
1044 }
1045 }
1046
1047 if (flush != Z_FINISH) return Z_OK;
1048 if (s->wrap <= 0) return Z_STREAM_END;
1049
1050 /* Write the trailer */
1051 #ifdef GZIP
1052 if (s->wrap == 2) {
1053 put_byte(s, (Byte)(strm->adler & 0xff));
1054 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
1055 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
1056 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
1057 put_byte(s, (Byte)(strm->total_in & 0xff));
1058 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
1059 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
1060 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
1061 }
1062 else
1063 #endif
1064 {
1065 putShortMSB(s, (uInt)(strm->adler >> 16));
1066 putShortMSB(s, (uInt)(strm->adler & 0xffff));
1067 }
1068 flush_pending(strm);
1069 /* If avail_out is zero, the application will call deflate again
1070 * to flush the rest.
1071 */
1072 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
1073 return s->pending != 0 ? Z_OK : Z_STREAM_END;
1074 }
1075
1076 /* ========================================================================= */
1077 int ZEXPORT deflateEnd (strm)
1078 z_streamp strm;
1079 {
1080 int status;
1081
1082 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
1083
1084 status = strm->state->status;
1085
1086 /* Deallocate in reverse order of allocations: */
1087 TRY_FREE(strm, strm->state->pending_buf);
1088 TRY_FREE(strm, strm->state->head);
1089 TRY_FREE(strm, strm->state->prev);
1090 TRY_FREE(strm, strm->state->window);
1091
1092 ZFREE(strm, strm->state);
1093 strm->state = Z_NULL;
1094
1095 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1096 }
1097
1098 /* =========================================================================
1099 * Copy the source state to the destination state.
1100 * To simplify the source, this is not supported for 16-bit MSDOS (which
1101 * doesn't have enough memory anyway to duplicate compression states).
1102 */
1103 int ZEXPORT deflateCopy (dest, source)
1104 z_streamp dest;
1105 z_streamp source;
1106 {
1107 #ifdef MAXSEG_64K
1108 return Z_STREAM_ERROR;
1109 #else
1110 deflate_state *ds;
1111 deflate_state *ss;
1112 ushf *overlay;
1113
1114
1115 if (deflateStateCheck(source) || dest == Z_NULL) {
1116 return Z_STREAM_ERROR;
1117 }
1118
1119 ss = source->state;
1120
1121 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1122
1123 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1124 if (ds == Z_NULL) return Z_MEM_ERROR;
1125 dest->state = (struct internal_state FAR *) ds;
1126 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1127 ds->strm = dest;
1128
1129 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1130 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1131 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1132 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1133 ds->pending_buf = (uchf *) overlay;
1134
1135 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1136 ds->pending_buf == Z_NULL) {
1137 deflateEnd (dest);
1138 return Z_MEM_ERROR;
1139 }
1140 /* following zmemcpy do not work for 16-bit MSDOS */
1141 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1142 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1143 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1144 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1145
1146 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1147 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1148 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1149
1150 ds->l_desc.dyn_tree = ds->dyn_ltree;
1151 ds->d_desc.dyn_tree = ds->dyn_dtree;
1152 ds->bl_desc.dyn_tree = ds->bl_tree;
1153
1154 return Z_OK;
1155 #endif /* MAXSEG_64K */
1156 }
1157
1158 /* ===========================================================================
1159 * Read a new buffer from the current input stream, update the adler32
1160 * and total number of bytes read. All deflate() input goes through
1161 * this function so some applications may wish to modify it to avoid
1162 * allocating a large strm->next_in buffer and copying from it.
1163 * (See also flush_pending()).
1164 */
1165 local unsigned read_buf(strm, buf, size)
1166 z_streamp strm;
1167 Bytef *buf;
1168 unsigned size;
1169 {
1170 unsigned len = strm->avail_in;
1171
1172 if (len > size) len = size;
1173 if (len == 0) return 0;
1174
1175 strm->avail_in -= len;
1176
1177 zmemcpy(buf, strm->next_in, len);
1178 if (strm->state->wrap == 1) {
1179 strm->adler = adler32(strm->adler, buf, len);
1180 }
1181 #ifdef GZIP
1182 else if (strm->state->wrap == 2) {
1183 strm->adler = crc32(strm->adler, buf, len);
1184 }
1185 #endif
1186 strm->next_in += len;
1187 strm->total_in += len;
1188
1189 return len;
1190 }
1191
1192 /* ===========================================================================
1193 * Initialize the "longest match" routines for a new zlib stream
1194 */
1195 local void lm_init (s)
1196 deflate_state *s;
1197 {
1198 s->window_size = (ulg)2L*s->w_size;
1199
1200 CLEAR_HASH(s);
1201
1202 /* Set the default configuration parameters:
1203 */
1204 s->max_lazy_match = configuration_table[s->level].max_lazy;
1205 s->good_match = configuration_table[s->level].good_length;
1206 s->nice_match = configuration_table[s->level].nice_length;
1207 s->max_chain_length = configuration_table[s->level].max_chain;
1208
1209 s->strstart = 0;
1210 s->block_start = 0L;
1211 s->lookahead = 0;
1212 s->insert = 0;
1213 s->match_length = s->prev_length = MIN_MATCH-1;
1214 s->match_available = 0;
1215 s->ins_h = 0;
1216 #ifndef FASTEST
1217 #ifdef ASMV
1218 match_init(); /* initialize the asm code */
1219 #endif
1220 #endif
1221 }
1222
1223 #ifndef FASTEST
1224 /* ===========================================================================
1225 * Set match_start to the longest match starting at the given string and
1226 * return its length. Matches shorter or equal to prev_length are discarded,
1227 * in which case the result is equal to prev_length and match_start is
1228 * garbage.
1229 * IN assertions: cur_match is the head of the hash chain for the current
1230 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1231 * OUT assertion: the match length is not greater than s->lookahead.
1232 */
1233 #ifndef ASMV
1234 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1235 * match.S. The code will be functionally equivalent.
1236 */
1237 local uInt longest_match(s, cur_match)
1238 deflate_state *s;
1239 IPos cur_match; /* current match */
1240 {
1241 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1242 register Bytef *scan = s->window + s->strstart; /* current string */
1243 register Bytef *match; /* matched string */
1244 register int len; /* length of current match */
1245 int best_len = (int)s->prev_length; /* best match length so far */
1246 int nice_match = s->nice_match; /* stop if match long enough */
1247 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1248 s->strstart - (IPos)MAX_DIST(s) : NIL;
1249 /* Stop when cur_match becomes <= limit. To simplify the code,
1250 * we prevent matches with the string of window index 0.
1251 */
1252 Posf *prev = s->prev;
1253 uInt wmask = s->w_mask;
1254
1255 #ifdef UNALIGNED_OK
1256 /* Compare two bytes at a time. Note: this is not always beneficial.
1257 * Try with and without -DUNALIGNED_OK to check.
1258 */
1259 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1260 register ush scan_start = *(ushf*)scan;
1261 register ush scan_end = *(ushf*)(scan+best_len-1);
1262 #else
1263 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1264 register Byte scan_end1 = scan[best_len-1];
1265 register Byte scan_end = scan[best_len];
1266 #endif
1267
1268 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1269 * It is easy to get rid of this optimization if necessary.
1270 */
1271 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1272
1273 /* Do not waste too much time if we already have a good match: */
1274 if (s->prev_length >= s->good_match) {
1275 chain_length >>= 2;
1276 }
1277 /* Do not look for matches beyond the end of the input. This is necessary
1278 * to make deflate deterministic.
1279 */
1280 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead;
1281
1282 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1283
1284 do {
1285 Assert(cur_match < s->strstart, "no future");
1286 match = s->window + cur_match;
1287
1288 /* Skip to next match if the match length cannot increase
1289 * or if the match length is less than 2. Note that the checks below
1290 * for insufficient lookahead only occur occasionally for performance
1291 * reasons. Therefore uninitialized memory will be accessed, and
1292 * conditional jumps will be made that depend on those values.
1293 * However the length of the match is limited to the lookahead, so
1294 * the output of deflate is not affected by the uninitialized values.
1295 */
1296 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1297 /* This code assumes sizeof(unsigned short) == 2. Do not use
1298 * UNALIGNED_OK if your compiler uses a different size.
1299 */
1300 if (*(ushf*)(match+best_len-1) != scan_end ||
1301 *(ushf*)match != scan_start) continue;
1302
1303 /* It is not necessary to compare scan[2] and match[2] since they are
1304 * always equal when the other bytes match, given that the hash keys
1305 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1306 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1307 * lookahead only every 4th comparison; the 128th check will be made
1308 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1309 * necessary to put more guard bytes at the end of the window, or
1310 * to check more often for insufficient lookahead.
1311 */
1312 Assert(scan[2] == match[2], "scan[2]?");
1313 scan++, match++;
1314 do {
1315 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1316 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1317 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1318 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1319 scan < strend);
1320 /* The funny "do {}" generates better code on most compilers */
1321
1322 /* Here, scan <= window+strstart+257 */
1323 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1324 if (*scan == *match) scan++;
1325
1326 len = (MAX_MATCH - 1) - (int)(strend-scan);
1327 scan = strend - (MAX_MATCH-1);
1328
1329 #else /* UNALIGNED_OK */
1330
1331 if (match[best_len] != scan_end ||
1332 match[best_len-1] != scan_end1 ||
1333 *match != *scan ||
1334 *++match != scan[1]) continue;
1335
1336 /* The check at best_len-1 can be removed because it will be made
1337 * again later. (This heuristic is not always a win.)
1338 * It is not necessary to compare scan[2] and match[2] since they
1339 * are always equal when the other bytes match, given that
1340 * the hash keys are equal and that HASH_BITS >= 8.
1341 */
1342 scan += 2, match++;
1343 Assert(*scan == *match, "match[2]?");
1344
1345 /* We check for insufficient lookahead only every 8th comparison;
1346 * the 256th check will be made at strstart+258.
1347 */
1348 do {
1349 } while (*++scan == *++match && *++scan == *++match &&
1350 *++scan == *++match && *++scan == *++match &&
1351 *++scan == *++match && *++scan == *++match &&
1352 *++scan == *++match && *++scan == *++match &&
1353 scan < strend);
1354
1355 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1356
1357 len = MAX_MATCH - (int)(strend - scan);
1358 scan = strend - MAX_MATCH;
1359
1360 #endif /* UNALIGNED_OK */
1361
1362 if (len > best_len) {
1363 s->match_start = cur_match;
1364 best_len = len;
1365 if (len >= nice_match) break;
1366 #ifdef UNALIGNED_OK
1367 scan_end = *(ushf*)(scan+best_len-1);
1368 #else
1369 scan_end1 = scan[best_len-1];
1370 scan_end = scan[best_len];
1371 #endif
1372 }
1373 } while ((cur_match = prev[cur_match & wmask]) > limit
1374 && --chain_length != 0);
1375
1376 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1377 return s->lookahead;
1378 }
1379 #endif /* ASMV */
1380
1381 #else /* FASTEST */
1382
1383 /* ---------------------------------------------------------------------------
1384 * Optimized version for FASTEST only
1385 */
1386 local uInt longest_match(s, cur_match)
1387 deflate_state *s;
1388 IPos cur_match; /* current match */
1389 {
1390 register Bytef *scan = s->window + s->strstart; /* current string */
1391 register Bytef *match; /* matched string */
1392 register int len; /* length of current match */
1393 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1394
1395 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1396 * It is easy to get rid of this optimization if necessary.
1397 */
1398 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1399
1400 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1401
1402 Assert(cur_match < s->strstart, "no future");
1403
1404 match = s->window + cur_match;
1405
1406 /* Return failure if the match length is less than 2:
1407 */
1408 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1409
1410 /* The check at best_len-1 can be removed because it will be made
1411 * again later. (This heuristic is not always a win.)
1412 * It is not necessary to compare scan[2] and match[2] since they
1413 * are always equal when the other bytes match, given that
1414 * the hash keys are equal and that HASH_BITS >= 8.
1415 */
1416 scan += 2, match += 2;
1417 Assert(*scan == *match, "match[2]?");
1418
1419 /* We check for insufficient lookahead only every 8th comparison;
1420 * the 256th check will be made at strstart+258.
1421 */
1422 do {
1423 } while (*++scan == *++match && *++scan == *++match &&
1424 *++scan == *++match && *++scan == *++match &&
1425 *++scan == *++match && *++scan == *++match &&
1426 *++scan == *++match && *++scan == *++match &&
1427 scan < strend);
1428
1429 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1430
1431 len = MAX_MATCH - (int)(strend - scan);
1432
1433 if (len < MIN_MATCH) return MIN_MATCH - 1;
1434
1435 s->match_start = cur_match;
1436 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1437 }
1438
1439 #endif /* FASTEST */
1440
1441 #ifdef ZLIB_DEBUG
1442
1443 #define EQUAL 0
1444 /* result of memcmp for equal strings */
1445
1446 /* ===========================================================================
1447 * Check that the match at match_start is indeed a match.
1448 */
1449 local void check_match(s, start, match, length)
1450 deflate_state *s;
1451 IPos start, match;
1452 int length;
1453 {
1454 /* check that the match is indeed a match */
1455 if (zmemcmp(s->window + match,
1456 s->window + start, length) != EQUAL) {
1457 fprintf(stderr, " start %u, match %u, length %d\n",
1458 start, match, length);
1459 do {
1460 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1461 } while (--length != 0);
1462 z_error("invalid match");
1463 }
1464 if (z_verbose > 1) {
1465 fprintf(stderr,"\\[%d,%d]", start-match, length);
1466 do { putc(s->window[start++], stderr); } while (--length != 0);
1467 }
1468 }
1469 #else
1470 # define check_match(s, start, match, length)
1471 #endif /* ZLIB_DEBUG */
1472
1473 /* ===========================================================================
1474 * Fill the window when the lookahead becomes insufficient.
1475 * Updates strstart and lookahead.
1476 *
1477 * IN assertion: lookahead < MIN_LOOKAHEAD
1478 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1479 * At least one byte has been read, or avail_in == 0; reads are
1480 * performed for at least two bytes (required for the zip translate_eol
1481 * option -- not supported here).
1482 */
1483 local void fill_window(s)
1484 deflate_state *s;
1485 {
1486 unsigned n;
1487 unsigned more; /* Amount of free space at the end of the window. */
1488 uInt wsize = s->w_size;
1489
1490 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1491
1492 do {
1493 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1494
1495 /* Deal with !@#$% 64K limit: */
1496 if (sizeof(int) <= 2) {
1497 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1498 more = wsize;
1499
1500 } else if (more == (unsigned)(-1)) {
1501 /* Very unlikely, but possible on 16 bit machine if
1502 * strstart == 0 && lookahead == 1 (input done a byte at time)
1503 */
1504 more--;
1505 }
1506 }
1507
1508 /* If the window is almost full and there is insufficient lookahead,
1509 * move the upper half to the lower one to make room in the upper half.
1510 */
1511 if (s->strstart >= wsize+MAX_DIST(s)) {
1512
1513 zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more);
1514 s->match_start -= wsize;
1515 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1516 s->block_start -= (long) wsize;
1517 slide_hash(s);
1518 more += wsize;
1519 }
1520 if (s->strm->avail_in == 0) break;
1521
1522 /* If there was no sliding:
1523 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1524 * more == window_size - lookahead - strstart
1525 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1526 * => more >= window_size - 2*WSIZE + 2
1527 * In the BIG_MEM or MMAP case (not yet supported),
1528 * window_size == input_size + MIN_LOOKAHEAD &&
1529 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1530 * Otherwise, window_size == 2*WSIZE so more >= 2.
1531 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1532 */
1533 Assert(more >= 2, "more < 2");
1534
1535 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1536 s->lookahead += n;
1537
1538 /* Initialize the hash value now that we have some input: */
1539 if (s->lookahead + s->insert >= MIN_MATCH) {
1540 uInt str = s->strstart - s->insert;
1541 s->ins_h = s->window[str];
1542 UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1543 #if MIN_MATCH != 3
1544 Call UPDATE_HASH() MIN_MATCH-3 more times
1545 #endif
1546 while (s->insert) {
1547 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1548 #ifndef FASTEST
1549 s->prev[str & s->w_mask] = s->head[s->ins_h];
1550 #endif
1551 s->head[s->ins_h] = (Pos)str;
1552 str++;
1553 s->insert--;
1554 if (s->lookahead + s->insert < MIN_MATCH)
1555 break;
1556 }
1557 }
1558 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1559 * but this is not important since only literal bytes will be emitted.
1560 */
1561
1562 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1563
1564 /* If the WIN_INIT bytes after the end of the current data have never been
1565 * written, then zero those bytes in order to avoid memory check reports of
1566 * the use of uninitialized (or uninitialised as Julian writes) bytes by
1567 * the longest match routines. Update the high water mark for the next
1568 * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1569 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1570 */
1571 if (s->high_water < s->window_size) {
1572 ulg curr = s->strstart + (ulg)(s->lookahead);
1573 ulg init;
1574
1575 if (s->high_water < curr) {
1576 /* Previous high water mark below current data -- zero WIN_INIT
1577 * bytes or up to end of window, whichever is less.
1578 */
1579 init = s->window_size - curr;
1580 if (init > WIN_INIT)
1581 init = WIN_INIT;
1582 zmemzero(s->window + curr, (unsigned)init);
1583 s->high_water = curr + init;
1584 }
1585 else if (s->high_water < (ulg)curr + WIN_INIT) {
1586 /* High water mark at or above current data, but below current data
1587 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1588 * to end of window, whichever is less.
1589 */
1590 init = (ulg)curr + WIN_INIT - s->high_water;
1591 if (init > s->window_size - s->high_water)
1592 init = s->window_size - s->high_water;
1593 zmemzero(s->window + s->high_water, (unsigned)init);
1594 s->high_water += init;
1595 }
1596 }
1597
1598 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1599 "not enough room for search");
1600 }
1601
1602 /* ===========================================================================
1603 * Flush the current block, with given end-of-file flag.
1604 * IN assertion: strstart is set to the end of the current match.
1605 */
1606 #define FLUSH_BLOCK_ONLY(s, last) { \
1607 _tr_flush_block(s, (s->block_start >= 0L ? \
1608 (charf *)&s->window[(unsigned)s->block_start] : \
1609 (charf *)Z_NULL), \
1610 (ulg)((long)s->strstart - s->block_start), \
1611 (last)); \
1612 s->block_start = s->strstart; \
1613 flush_pending(s->strm); \
1614 Tracev((stderr,"[FLUSH]")); \
1615 }
1616
1617 /* Same but force premature exit if necessary. */
1618 #define FLUSH_BLOCK(s, last) { \
1619 FLUSH_BLOCK_ONLY(s, last); \
1620 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1621 }
1622
1623 /* Maximum stored block length in deflate format (not including header). */
1624 #define MAX_STORED 65535
1625
1626 /* Minimum of a and b. */
1627 #define MIN(a, b) ((a) > (b) ? (b) : (a))
1628
1629 /* ===========================================================================
1630 * Copy without compression as much as possible from the input stream, return
1631 * the current block state.
1632 *
1633 * In case deflateParams() is used to later switch to a non-zero compression
1634 * level, s->matches (otherwise unused when storing) keeps track of the number
1635 * of hash table slides to perform. If s->matches is 1, then one hash table
1636 * slide will be done when switching. If s->matches is 2, the maximum value
1637 * allowed here, then the hash table will be cleared, since two or more slides
1638 * is the same as a clear.
1639 *
1640 * deflate_stored() is written to minimize the number of times an input byte is
1641 * copied. It is most efficient with large input and output buffers, which
1642 * maximizes the opportunites to have a single copy from next_in to next_out.
1643 */
1644 local block_state deflate_stored(s, flush)
1645 deflate_state *s;
1646 int flush;
1647 {
1648 /* Smallest worthy block size when not flushing or finishing. By default
1649 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For
1650 * large input and output buffers, the stored block size will be larger.
1651 */
1652 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size);
1653
1654 /* Copy as many min_block or larger stored blocks directly to next_out as
1655 * possible. If flushing, copy the remaining available input to next_out as
1656 * stored blocks, if there is enough space.
1657 */
1658 unsigned len, left, have, last = 0;
1659 unsigned used = s->strm->avail_in;
1660 do {
1661 /* Set len to the maximum size block that we can copy directly with the
1662 * available input data and output space. Set left to how much of that
1663 * would be copied from what's left in the window.
1664 */
1665 len = MAX_STORED; /* maximum deflate stored block length */
1666 have = (s->bi_valid + 42) >> 3; /* number of header bytes */
1667 if (s->strm->avail_out < have) /* need room for header */
1668 break;
1669 /* maximum stored block length that will fit in avail_out: */
1670 have = s->strm->avail_out - have;
1671 left = s->strstart - s->block_start; /* bytes left in window */
1672 if (len > (ulg)left + s->strm->avail_in)
1673 len = left + s->strm->avail_in; /* limit len to the input */
1674 if (len > have)
1675 len = have; /* limit len to the output */
1676
1677 /* If the stored block would be less than min_block in length, or if
1678 * unable to copy all of the available input when flushing, then try
1679 * copying to the window and the pending buffer instead. Also don't
1680 * write an empty block when flushing -- deflate() does that.
1681 */
1682 if (len < min_block && ((len == 0 && flush != Z_FINISH) ||
1683 flush == Z_NO_FLUSH ||
1684 len != left + s->strm->avail_in))
1685 break;
1686
1687 /* Make a dummy stored block in pending to get the header bytes,
1688 * including any pending bits. This also updates the debugging counts.
1689 */
1690 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0;
1691 _tr_stored_block(s, (char *)0, 0L, last);
1692
1693 /* Replace the lengths in the dummy stored block with len. */
1694 s->pending_buf[s->pending - 4] = len;
1695 s->pending_buf[s->pending - 3] = len >> 8;
1696 s->pending_buf[s->pending - 2] = ~len;
1697 s->pending_buf[s->pending - 1] = ~len >> 8;
1698
1699 /* Write the stored block header bytes. */
1700 flush_pending(s->strm);
1701
1702 #ifdef ZLIB_DEBUG
1703 /* Update debugging counts for the data about to be copied. */
1704 s->compressed_len += len << 3;
1705 s->bits_sent += len << 3;
1706 #endif
1707
1708 /* Copy uncompressed bytes from the window to next_out. */
1709 if (left) {
1710 if (left > len)
1711 left = len;
1712 zmemcpy(s->strm->next_out, s->window + s->block_start, left);
1713 s->strm->next_out += left;
1714 s->strm->avail_out -= left;
1715 s->strm->total_out += left;
1716 s->block_start += left;
1717 len -= left;
1718 }
1719
1720 /* Copy uncompressed bytes directly from next_in to next_out, updating
1721 * the check value.
1722 */
1723 if (len) {
1724 read_buf(s->strm, s->strm->next_out, len);
1725 s->strm->next_out += len;
1726 s->strm->avail_out -= len;
1727 s->strm->total_out += len;
1728 }
1729 } while (last == 0);
1730
1731 /* Update the sliding window with the last s->w_size bytes of the copied
1732 * data, or append all of the copied data to the existing window if less
1733 * than s->w_size bytes were copied. Also update the number of bytes to
1734 * insert in the hash tables, in the event that deflateParams() switches to
1735 * a non-zero compression level.
1736 */
1737 used -= s->strm->avail_in; /* number of input bytes directly copied */
1738 if (used) {
1739 /* If any input was used, then no unused input remains in the window,
1740 * therefore s->block_start == s->strstart.
1741 */
1742 if (used >= s->w_size) { /* supplant the previous history */
1743 s->matches = 2; /* clear hash */
1744 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);
1745 s->strstart = s->w_size;
1746 }
1747 else {
1748 if (s->window_size - s->strstart <= used) {
1749 /* Slide the window down. */
1750 s->strstart -= s->w_size;
1751 zmemcpy(s->window, s->window + s->w_size, s->strstart);
1752 if (s->matches < 2)
1753 s->matches++; /* add a pending slide_hash() */
1754 }
1755 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used);
1756 s->strstart += used;
1757 }
1758 s->block_start = s->strstart;
1759 s->insert += MIN(used, s->w_size - s->insert);
1760 }
1761 if (s->high_water < s->strstart)
1762 s->high_water = s->strstart;
1763
1764 /* If the last block was written to next_out, then done. */
1765 if (last)
1766 return finish_done;
1767
1768 /* If flushing and all input has been consumed, then done. */
1769 if (flush != Z_NO_FLUSH && flush != Z_FINISH &&
1770 s->strm->avail_in == 0 && (long)s->strstart == s->block_start)
1771 return block_done;
1772
1773 /* Fill the window with any remaining input. */
1774 have = s->window_size - s->strstart - 1;
1775 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) {
1776 /* Slide the window down. */
1777 s->block_start -= s->w_size;
1778 s->strstart -= s->w_size;
1779 zmemcpy(s->window, s->window + s->w_size, s->strstart);
1780 if (s->matches < 2)
1781 s->matches++; /* add a pending slide_hash() */
1782 have += s->w_size; /* more space now */
1783 }
1784 if (have > s->strm->avail_in)
1785 have = s->strm->avail_in;
1786 if (have) {
1787 read_buf(s->strm, s->window + s->strstart, have);
1788 s->strstart += have;
1789 }
1790 if (s->high_water < s->strstart)
1791 s->high_water = s->strstart;
1792
1793 /* There was not enough avail_out to write a complete worthy or flushed
1794 * stored block to next_out. Write a stored block to pending instead, if we
1795 * have enough input for a worthy block, or if flushing and there is enough
1796 * room for the remaining input as a stored block in the pending buffer.
1797 */
1798 have = (s->bi_valid + 42) >> 3; /* number of header bytes */
1799 /* maximum stored block length that will fit in pending: */
1800 have = MIN(s->pending_buf_size - have, MAX_STORED);
1801 min_block = MIN(have, s->w_size);
1802 left = s->strstart - s->block_start;
1803 if (left >= min_block ||
1804 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH &&
1805 s->strm->avail_in == 0 && left <= have)) {
1806 len = MIN(left, have);
1807 last = flush == Z_FINISH && s->strm->avail_in == 0 &&
1808 len == left ? 1 : 0;
1809 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last);
1810 s->block_start += len;
1811 flush_pending(s->strm);
1812 }
1813
1814 /* We've done all we can with the available input and output. */
1815 return last ? finish_started : need_more;
1816 }
1817
1818 /* ===========================================================================
1819 * Compress as much as possible from the input stream, return the current
1820 * block state.
1821 * This function does not perform lazy evaluation of matches and inserts
1822 * new strings in the dictionary only for unmatched strings or for short
1823 * matches. It is used only for the fast compression options.
1824 */
1825 local block_state deflate_fast(s, flush)
1826 deflate_state *s;
1827 int flush;
1828 {
1829 IPos hash_head; /* head of the hash chain */
1830 int bflush; /* set if current block must be flushed */
1831
1832 for (;;) {
1833 /* Make sure that we always have enough lookahead, except
1834 * at the end of the input file. We need MAX_MATCH bytes
1835 * for the next match, plus MIN_MATCH bytes to insert the
1836 * string following the next match.
1837 */
1838 if (s->lookahead < MIN_LOOKAHEAD) {
1839 fill_window(s);
1840 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1841 return need_more;
1842 }
1843 if (s->lookahead == 0) break; /* flush the current block */
1844 }
1845
1846 /* Insert the string window[strstart .. strstart+2] in the
1847 * dictionary, and set hash_head to the head of the hash chain:
1848 */
1849 hash_head = NIL;
1850 if (s->lookahead >= MIN_MATCH) {
1851 INSERT_STRING(s, s->strstart, hash_head);
1852 }
1853
1854 /* Find the longest match, discarding those <= prev_length.
1855 * At this point we have always match_length < MIN_MATCH
1856 */
1857 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1858 /* To simplify the code, we prevent matches with the string
1859 * of window index 0 (in particular we have to avoid a match
1860 * of the string with itself at the start of the input file).
1861 */
1862 s->match_length = longest_match (s, hash_head);
1863 /* longest_match() sets match_start */
1864 }
1865 if (s->match_length >= MIN_MATCH) {
1866 check_match(s, s->strstart, s->match_start, s->match_length);
1867
1868 _tr_tally_dist(s, s->strstart - s->match_start,
1869 s->match_length - MIN_MATCH, bflush);
1870
1871 s->lookahead -= s->match_length;
1872
1873 /* Insert new strings in the hash table only if the match length
1874 * is not too large. This saves time but degrades compression.
1875 */
1876 #ifndef FASTEST
1877 if (s->match_length <= s->max_insert_length &&
1878 s->lookahead >= MIN_MATCH) {
1879 s->match_length--; /* string at strstart already in table */
1880 do {
1881 s->strstart++;
1882 INSERT_STRING(s, s->strstart, hash_head);
1883 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1884 * always MIN_MATCH bytes ahead.
1885 */
1886 } while (--s->match_length != 0);
1887 s->strstart++;
1888 } else
1889 #endif
1890 {
1891 s->strstart += s->match_length;
1892 s->match_length = 0;
1893 s->ins_h = s->window[s->strstart];
1894 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1895 #if MIN_MATCH != 3
1896 Call UPDATE_HASH() MIN_MATCH-3 more times
1897 #endif
1898 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1899 * matter since it will be recomputed at next deflate call.
1900 */
1901 }
1902 } else {
1903 /* No match, output a literal byte */
1904 Tracevv((stderr,"%c", s->window[s->strstart]));
1905 _tr_tally_lit (s, s->window[s->strstart], bflush);
1906 s->lookahead--;
1907 s->strstart++;
1908 }
1909 if (bflush) FLUSH_BLOCK(s, 0);
1910 }
1911 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1912 if (flush == Z_FINISH) {
1913 FLUSH_BLOCK(s, 1);
1914 return finish_done;
1915 }
1916 if (s->last_lit)
1917 FLUSH_BLOCK(s, 0);
1918 return block_done;
1919 }
1920
1921 #ifndef FASTEST
1922 /* ===========================================================================
1923 * Same as above, but achieves better compression. We use a lazy
1924 * evaluation for matches: a match is finally adopted only if there is
1925 * no better match at the next window position.
1926 */
1927 local block_state deflate_slow(s, flush)
1928 deflate_state *s;
1929 int flush;
1930 {
1931 IPos hash_head; /* head of hash chain */
1932 int bflush; /* set if current block must be flushed */
1933
1934 /* Process the input block. */
1935 for (;;) {
1936 /* Make sure that we always have enough lookahead, except
1937 * at the end of the input file. We need MAX_MATCH bytes
1938 * for the next match, plus MIN_MATCH bytes to insert the
1939 * string following the next match.
1940 */
1941 if (s->lookahead < MIN_LOOKAHEAD) {
1942 fill_window(s);
1943 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1944 return need_more;
1945 }
1946 if (s->lookahead == 0) break; /* flush the current block */
1947 }
1948
1949 /* Insert the string window[strstart .. strstart+2] in the
1950 * dictionary, and set hash_head to the head of the hash chain:
1951 */
1952 hash_head = NIL;
1953 if (s->lookahead >= MIN_MATCH) {
1954 INSERT_STRING(s, s->strstart, hash_head);
1955 }
1956
1957 /* Find the longest match, discarding those <= prev_length.
1958 */
1959 s->prev_length = s->match_length, s->prev_match = s->match_start;
1960 s->match_length = MIN_MATCH-1;
1961
1962 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1963 s->strstart - hash_head <= MAX_DIST(s)) {
1964 /* To simplify the code, we prevent matches with the string
1965 * of window index 0 (in particular we have to avoid a match
1966 * of the string with itself at the start of the input file).
1967 */
1968 s->match_length = longest_match (s, hash_head);
1969 /* longest_match() sets match_start */
1970
1971 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1972 #if TOO_FAR <= 32767
1973 || (s->match_length == MIN_MATCH &&
1974 s->strstart - s->match_start > TOO_FAR)
1975 #endif
1976 )) {
1977
1978 /* If prev_match is also MIN_MATCH, match_start is garbage
1979 * but we will ignore the current match anyway.
1980 */
1981 s->match_length = MIN_MATCH-1;
1982 }
1983 }
1984 /* If there was a match at the previous step and the current
1985 * match is not better, output the previous match:
1986 */
1987 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1988 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1989 /* Do not insert strings in hash table beyond this. */
1990
1991 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1992
1993 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1994 s->prev_length - MIN_MATCH, bflush);
1995
1996 /* Insert in hash table all strings up to the end of the match.
1997 * strstart-1 and strstart are already inserted. If there is not
1998 * enough lookahead, the last two strings are not inserted in
1999 * the hash table.
2000 */
2001 s->lookahead -= s->prev_length-1;
2002 s->prev_length -= 2;
2003 do {
2004 if (++s->strstart <= max_insert) {
2005 INSERT_STRING(s, s->strstart, hash_head);
2006 }
2007 } while (--s->prev_length != 0);
2008 s->match_available = 0;
2009 s->match_length = MIN_MATCH-1;
2010 s->strstart++;
2011
2012 if (bflush) FLUSH_BLOCK(s, 0);
2013
2014 } else if (s->match_available) {
2015 /* If there was no match at the previous position, output a
2016 * single literal. If there was a match but the current match
2017 * is longer, truncate the previous match to a single literal.
2018 */
2019 Tracevv((stderr,"%c", s->window[s->strstart-1]));
2020 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
2021 if (bflush) {
2022 FLUSH_BLOCK_ONLY(s, 0);
2023 }
2024 s->strstart++;
2025 s->lookahead--;
2026 if (s->strm->avail_out == 0) return need_more;
2027 } else {
2028 /* There is no previous match to compare with, wait for
2029 * the next step to decide.
2030 */
2031 s->match_available = 1;
2032 s->strstart++;
2033 s->lookahead--;
2034 }
2035 }
2036 Assert (flush != Z_NO_FLUSH, "no flush?");
2037 if (s->match_available) {
2038 Tracevv((stderr,"%c", s->window[s->strstart-1]));
2039 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
2040 s->match_available = 0;
2041 }
2042 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
2043 if (flush == Z_FINISH) {
2044 FLUSH_BLOCK(s, 1);
2045 return finish_done;
2046 }
2047 if (s->last_lit)
2048 FLUSH_BLOCK(s, 0);
2049 return block_done;
2050 }
2051 #endif /* FASTEST */
2052
2053 /* ===========================================================================
2054 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
2055 * one. Do not maintain a hash table. (It will be regenerated if this run of
2056 * deflate switches away from Z_RLE.)
2057 */
2058 local block_state deflate_rle(s, flush)
2059 deflate_state *s;
2060 int flush;
2061 {
2062 int bflush; /* set if current block must be flushed */
2063 uInt prev; /* byte at distance one to match */
2064 Bytef *scan, *strend; /* scan goes up to strend for length of run */
2065
2066 for (;;) {
2067 /* Make sure that we always have enough lookahead, except
2068 * at the end of the input file. We need MAX_MATCH bytes
2069 * for the longest run, plus one for the unrolled loop.
2070 */
2071 if (s->lookahead <= MAX_MATCH) {
2072 fill_window(s);
2073 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
2074 return need_more;
2075 }
2076 if (s->lookahead == 0) break; /* flush the current block */
2077 }
2078
2079 /* See how many times the previous byte repeats */
2080 s->match_length = 0;
2081 if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
2082 scan = s->window + s->strstart - 1;
2083 prev = *scan;
2084 if (prev == *++scan && prev == *++scan && prev == *++scan) {
2085 strend = s->window + s->strstart + MAX_MATCH;
2086 do {
2087 } while (prev == *++scan && prev == *++scan &&
2088 prev == *++scan && prev == *++scan &&
2089 prev == *++scan && prev == *++scan &&
2090 prev == *++scan && prev == *++scan &&
2091 scan < strend);
2092 s->match_length = MAX_MATCH - (uInt)(strend - scan);
2093 if (s->match_length > s->lookahead)
2094 s->match_length = s->lookahead;
2095 }
2096 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
2097 }
2098
2099 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
2100 if (s->match_length >= MIN_MATCH) {
2101 check_match(s, s->strstart, s->strstart - 1, s->match_length);
2102
2103 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
2104
2105 s->lookahead -= s->match_length;
2106 s->strstart += s->match_length;
2107 s->match_length = 0;
2108 } else {
2109 /* No match, output a literal byte */
2110 Tracevv((stderr,"%c", s->window[s->strstart]));
2111 _tr_tally_lit (s, s->window[s->strstart], bflush);
2112 s->lookahead--;
2113 s->strstart++;
2114 }
2115 if (bflush) FLUSH_BLOCK(s, 0);
2116 }
2117 s->insert = 0;
2118 if (flush == Z_FINISH) {
2119 FLUSH_BLOCK(s, 1);
2120 return finish_done;
2121 }
2122 if (s->last_lit)
2123 FLUSH_BLOCK(s, 0);
2124 return block_done;
2125 }
2126
2127 /* ===========================================================================
2128 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
2129 * (It will be regenerated if this run of deflate switches away from Huffman.)
2130 */
2131 local block_state deflate_huff(s, flush)
2132 deflate_state *s;
2133 int flush;
2134 {
2135 int bflush; /* set if current block must be flushed */
2136
2137 for (;;) {
2138 /* Make sure that we have a literal to write. */
2139 if (s->lookahead == 0) {
2140 fill_window(s);
2141 if (s->lookahead == 0) {
2142 if (flush == Z_NO_FLUSH)
2143 return need_more;
2144 break; /* flush the current block */
2145 }
2146 }
2147
2148 /* Output a literal byte */
2149 s->match_length = 0;
2150 Tracevv((stderr,"%c", s->window[s->strstart]));
2151 _tr_tally_lit (s, s->window[s->strstart], bflush);
2152 s->lookahead--;
2153 s->strstart++;
2154 if (bflush) FLUSH_BLOCK(s, 0);
2155 }
2156 s->insert = 0;
2157 if (flush == Z_FINISH) {
2158 FLUSH_BLOCK(s, 1);
2159 return finish_done;
2160 }
2161 if (s->last_lit)
2162 FLUSH_BLOCK(s, 0);
2163 return block_done;
2164 }