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