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security/nss/lib/zlib/deflate.c

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1 /* deflate.c -- compress data using the deflation algorithm
2 * Copyright (C) 1995-2010 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://www.ietf.org/rfc/rfc1951.txt
41 *
42 * A description of the Rabin and Karp algorithm is given in the book
43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
44 *
45 * Fiala,E.R., and Greene,D.H.
46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
47 *
48 */
49
50 /* @(#) $Id$ */
51
52 #include "deflate.h"
53
54 const char deflate_copyright[] =
55 " deflate 1.2.5 Copyright 1995-2010 Jean-loup Gailly and Mark Adler ";
56 /*
57 If you use the zlib library in a product, an acknowledgment is welcome
58 in the documentation of your product. If for some reason you cannot
59 include such an acknowledgment, I would appreciate that you keep this
60 copyright string in the executable of your product.
61 */
62
63 /* ===========================================================================
64 * Function prototypes.
65 */
66 typedef enum {
67 need_more, /* block not completed, need more input or more output */
68 block_done, /* block flush performed */
69 finish_started, /* finish started, need only more output at next deflate */
70 finish_done /* finish done, accept no more input or output */
71 } block_state;
72
73 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74 /* Compression function. Returns the block state after the call. */
75
76 local void fill_window OF((deflate_state *s));
77 local block_state deflate_stored OF((deflate_state *s, int flush));
78 local block_state deflate_fast OF((deflate_state *s, int flush));
79 #ifndef FASTEST
80 local block_state deflate_slow OF((deflate_state *s, int flush));
81 #endif
82 local block_state deflate_rle OF((deflate_state *s, int flush));
83 local block_state deflate_huff OF((deflate_state *s, int flush));
84 local void lm_init OF((deflate_state *s));
85 local void putShortMSB OF((deflate_state *s, uInt b));
86 local void flush_pending OF((z_streamp strm));
87 local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
88 #ifdef ASMV
89 void match_init OF((void)); /* asm code initialization */
90 uInt longest_match OF((deflate_state *s, IPos cur_match));
91 #else
92 local uInt longest_match OF((deflate_state *s, IPos cur_match));
93 #endif
94
95 #ifdef DEBUG
96 local void check_match OF((deflate_state *s, IPos start, IPos match,
97 int length));
98 #endif
99
100 /* ===========================================================================
101 * Local data
102 */
103
104 #define NIL 0
105 /* Tail of hash chains */
106
107 #ifndef TOO_FAR
108 # define TOO_FAR 4096
109 #endif
110 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
111
112 /* Values for max_lazy_match, good_match and max_chain_length, depending on
113 * the desired pack level (0..9). The values given below have been tuned to
114 * exclude worst case performance for pathological files. Better values may be
115 * found for specific files.
116 */
117 typedef struct config_s {
118 ush good_length; /* reduce lazy search above this match length */
119 ush max_lazy; /* do not perform lazy search above this match length */
120 ush nice_length; /* quit search above this match length */
121 ush max_chain;
122 compress_func func;
123 } config;
124
125 #ifdef FASTEST
126 local const config configuration_table[2] = {
127 /* good lazy nice chain */
128 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
129 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
130 #else
131 local const config configuration_table[10] = {
132 /* good lazy nice chain */
133 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
134 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
135 /* 2 */ {4, 5, 16, 8, deflate_fast},
136 /* 3 */ {4, 6, 32, 32, deflate_fast},
137
138 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
139 /* 5 */ {8, 16, 32, 32, deflate_slow},
140 /* 6 */ {8, 16, 128, 128, deflate_slow},
141 /* 7 */ {8, 32, 128, 256, deflate_slow},
142 /* 8 */ {32, 128, 258, 1024, deflate_slow},
143 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
144 #endif
145
146 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
147 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
148 * meaning.
149 */
150
151 #define EQUAL 0
152 /* result of memcmp for equal strings */
153
154 #ifndef NO_DUMMY_DECL
155 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
156 #endif
157
158 /* ===========================================================================
159 * Update a hash value with the given input byte
160 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
161 * input characters, so that a running hash key can be computed from the
162 * previous key instead of complete recalculation each time.
163 */
164 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
165
166
167 /* ===========================================================================
168 * Insert string str in the dictionary and set match_head to the previous head
169 * of the hash chain (the most recent string with same hash key). Return
170 * the previous length of the hash chain.
171 * If this file is compiled with -DFASTEST, the compression level is forced
172 * to 1, and no hash chains are maintained.
173 * IN assertion: all calls to to INSERT_STRING are made with consecutive
174 * input characters and the first MIN_MATCH bytes of str are valid
175 * (except for the last MIN_MATCH-1 bytes of the input file).
176 */
177 #ifdef FASTEST
178 #define INSERT_STRING(s, str, match_head) \
179 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
180 match_head = s->head[s->ins_h], \
181 s->head[s->ins_h] = (Pos)(str))
182 #else
183 #define INSERT_STRING(s, str, match_head) \
184 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
185 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
186 s->head[s->ins_h] = (Pos)(str))
187 #endif
188
189 /* ===========================================================================
190 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
191 * prev[] will be initialized on the fly.
192 */
193 #define CLEAR_HASH(s) \
194 s->head[s->hash_size-1] = NIL; \
195 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
196
197 /* ========================================================================= */
198 int ZEXPORT deflateInit_(strm, level, version, stream_size)
199 z_streamp strm;
200 int level;
201 const char *version;
202 int stream_size;
203 {
204 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
205 Z_DEFAULT_STRATEGY, version, stream_size);
206 /* To do: ignore strm->next_in if we use it as window */
207 }
208
209 /* ========================================================================= */
210 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
211 version, stream_size)
212 z_streamp strm;
213 int level;
214 int method;
215 int windowBits;
216 int memLevel;
217 int strategy;
218 const char *version;
219 int stream_size;
220 {
221 deflate_state *s;
222 int wrap = 1;
223 static const char my_version[] = ZLIB_VERSION;
224
225 ushf *overlay;
226 /* We overlay pending_buf and d_buf+l_buf. This works since the average
227 * output size for (length,distance) codes is <= 24 bits.
228 */
229
230 if (version == Z_NULL || version[0] != my_version[0] ||
231 stream_size != sizeof(z_stream)) {
232 return Z_VERSION_ERROR;
233 }
234 if (strm == Z_NULL) return Z_STREAM_ERROR;
235
236 strm->msg = Z_NULL;
237 if (strm->zalloc == (alloc_func)0) {
238 strm->zalloc = zcalloc;
239 strm->opaque = (voidpf)0;
240 }
241 if (strm->zfree == (free_func)0) strm->zfree = zcfree;
242
243 #ifdef FASTEST
244 if (level != 0) level = 1;
245 #else
246 if (level == Z_DEFAULT_COMPRESSION) level = 6;
247 #endif
248
249 if (windowBits < 0) { /* suppress zlib wrapper */
250 wrap = 0;
251 windowBits = -windowBits;
252 }
253 #ifdef GZIP
254 else if (windowBits > 15) {
255 wrap = 2; /* write gzip wrapper instead */
256 windowBits -= 16;
257 }
258 #endif
259 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
260 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
261 strategy < 0 || strategy > Z_FIXED) {
262 return Z_STREAM_ERROR;
263 }
264 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
265 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
266 if (s == Z_NULL) return Z_MEM_ERROR;
267 strm->state = (struct internal_state FAR *)s;
268 s->strm = strm;
269
270 s->wrap = wrap;
271 s->gzhead = Z_NULL;
272 s->w_bits = windowBits;
273 s->w_size = 1 << s->w_bits;
274 s->w_mask = s->w_size - 1;
275
276 s->hash_bits = memLevel + 7;
277 s->hash_size = 1 << s->hash_bits;
278 s->hash_mask = s->hash_size - 1;
279 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
280
281 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
282 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
283 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
284
285 s->high_water = 0; /* nothing written to s->window yet */
286
287 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
288
289 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
290 s->pending_buf = (uchf *) overlay;
291 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
292
293 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
294 s->pending_buf == Z_NULL) {
295 s->status = FINISH_STATE;
296 strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
297 deflateEnd (strm);
298 return Z_MEM_ERROR;
299 }
300 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
301 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
302
303 s->level = level;
304 s->strategy = strategy;
305 s->method = (Byte)method;
306
307 return deflateReset(strm);
308 }
309
310 /* ========================================================================= */
311 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
312 z_streamp strm;
313 const Bytef *dictionary;
314 uInt dictLength;
315 {
316 deflate_state *s;
317 uInt length = dictLength;
318 uInt n;
319 IPos hash_head = 0;
320
321 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
322 strm->state->wrap == 2 ||
323 (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
324 return Z_STREAM_ERROR;
325
326 s = strm->state;
327 if (s->wrap)
328 strm->adler = adler32(strm->adler, dictionary, dictLength);
329
330 if (length < MIN_MATCH) return Z_OK;
331 if (length > s->w_size) {
332 length = s->w_size;
333 dictionary += dictLength - length; /* use the tail of the dictionary */
334 }
335 zmemcpy(s->window, dictionary, length);
336 s->strstart = length;
337 s->block_start = (long)length;
338
339 /* Insert all strings in the hash table (except for the last two bytes).
340 * s->lookahead stays null, so s->ins_h will be recomputed at the next
341 * call of fill_window.
342 */
343 s->ins_h = s->window[0];
344 UPDATE_HASH(s, s->ins_h, s->window[1]);
345 for (n = 0; n <= length - MIN_MATCH; n++) {
346 INSERT_STRING(s, n, hash_head);
347 }
348 if (hash_head) hash_head = 0; /* to make compiler happy */
349 return Z_OK;
350 }
351
352 /* ========================================================================= */
353 int ZEXPORT deflateReset (strm)
354 z_streamp strm;
355 {
356 deflate_state *s;
357
358 if (strm == Z_NULL || strm->state == Z_NULL ||
359 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
360 return Z_STREAM_ERROR;
361 }
362
363 strm->total_in = strm->total_out = 0;
364 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
365 strm->data_type = Z_UNKNOWN;
366
367 s = (deflate_state *)strm->state;
368 s->pending = 0;
369 s->pending_out = s->pending_buf;
370
371 if (s->wrap < 0) {
372 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
373 }
374 s->status = s->wrap ? INIT_STATE : BUSY_STATE;
375 strm->adler =
376 #ifdef GZIP
377 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
378 #endif
379 adler32(0L, Z_NULL, 0);
380 s->last_flush = Z_NO_FLUSH;
381
382 _tr_init(s);
383 lm_init(s);
384
385 return Z_OK;
386 }
387
388 /* ========================================================================= */
389 int ZEXPORT deflateSetHeader (strm, head)
390 z_streamp strm;
391 gz_headerp head;
392 {
393 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
394 if (strm->state->wrap != 2) return Z_STREAM_ERROR;
395 strm->state->gzhead = head;
396 return Z_OK;
397 }
398
399 /* ========================================================================= */
400 int ZEXPORT deflatePrime (strm, bits, value)
401 z_streamp strm;
402 int bits;
403 int value;
404 {
405 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
406 strm->state->bi_valid = bits;
407 strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
408 return Z_OK;
409 }
410
411 /* ========================================================================= */
412 int ZEXPORT deflateParams(strm, level, strategy)
413 z_streamp strm;
414 int level;
415 int strategy;
416 {
417 deflate_state *s;
418 compress_func func;
419 int err = Z_OK;
420
421 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
422 s = strm->state;
423
424 #ifdef FASTEST
425 if (level != 0) level = 1;
426 #else
427 if (level == Z_DEFAULT_COMPRESSION) level = 6;
428 #endif
429 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
430 return Z_STREAM_ERROR;
431 }
432 func = configuration_table[s->level].func;
433
434 if ((strategy != s->strategy || func != configuration_table[level].func) &&
435 strm->total_in != 0) {
436 /* Flush the last buffer: */
437 err = deflate(strm, Z_BLOCK);
438 }
439 if (s->level != level) {
440 s->level = level;
441 s->max_lazy_match = configuration_table[level].max_lazy;
442 s->good_match = configuration_table[level].good_length;
443 s->nice_match = configuration_table[level].nice_length;
444 s->max_chain_length = configuration_table[level].max_chain;
445 }
446 s->strategy = strategy;
447 return err;
448 }
449
450 /* ========================================================================= */
451 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
452 z_streamp strm;
453 int good_length;
454 int max_lazy;
455 int nice_length;
456 int max_chain;
457 {
458 deflate_state *s;
459
460 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
461 s = strm->state;
462 s->good_match = good_length;
463 s->max_lazy_match = max_lazy;
464 s->nice_match = nice_length;
465 s->max_chain_length = max_chain;
466 return Z_OK;
467 }
468
469 /* =========================================================================
470 * For the default windowBits of 15 and memLevel of 8, this function returns
471 * a close to exact, as well as small, upper bound on the compressed size.
472 * They are coded as constants here for a reason--if the #define's are
473 * changed, then this function needs to be changed as well. The return
474 * value for 15 and 8 only works for those exact settings.
475 *
476 * For any setting other than those defaults for windowBits and memLevel,
477 * the value returned is a conservative worst case for the maximum expansion
478 * resulting from using fixed blocks instead of stored blocks, which deflate
479 * can emit on compressed data for some combinations of the parameters.
480 *
481 * This function could be more sophisticated to provide closer upper bounds for
482 * every combination of windowBits and memLevel. But even the conservative
483 * upper bound of about 14% expansion does not seem onerous for output buffer
484 * allocation.
485 */
486 uLong ZEXPORT deflateBound(strm, sourceLen)
487 z_streamp strm;
488 uLong sourceLen;
489 {
490 deflate_state *s;
491 uLong complen, wraplen;
492 Bytef *str;
493
494 /* conservative upper bound for compressed data */
495 complen = sourceLen +
496 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
497
498 /* if can't get parameters, return conservative bound plus zlib wrapper */
499 if (strm == Z_NULL || strm->state == Z_NULL)
500 return complen + 6;
501
502 /* compute wrapper length */
503 s = strm->state;
504 switch (s->wrap) {
505 case 0: /* raw deflate */
506 wraplen = 0;
507 break;
508 case 1: /* zlib wrapper */
509 wraplen = 6 + (s->strstart ? 4 : 0);
510 break;
511 case 2: /* gzip wrapper */
512 wraplen = 18;
513 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
514 if (s->gzhead->extra != Z_NULL)
515 wraplen += 2 + s->gzhead->extra_len;
516 str = s->gzhead->name;
517 if (str != Z_NULL)
518 do {
519 wraplen++;
520 } while (*str++);
521 str = s->gzhead->comment;
522 if (str != Z_NULL)
523 do {
524 wraplen++;
525 } while (*str++);
526 if (s->gzhead->hcrc)
527 wraplen += 2;
528 }
529 break;
530 default: /* for compiler happiness */
531 wraplen = 6;
532 }
533
534 /* if not default parameters, return conservative bound */
535 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
536 return complen + wraplen;
537
538 /* default settings: return tight bound for that case */
539 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
540 (sourceLen >> 25) + 13 - 6 + wraplen;
541 }
542
543 /* =========================================================================
544 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
545 * IN assertion: the stream state is correct and there is enough room in
546 * pending_buf.
547 */
548 local void putShortMSB (s, b)
549 deflate_state *s;
550 uInt b;
551 {
552 put_byte(s, (Byte)(b >> 8));
553 put_byte(s, (Byte)(b & 0xff));
554 }
555
556 /* =========================================================================
557 * Flush as much pending output as possible. All deflate() output goes
558 * through this function so some applications may wish to modify it
559 * to avoid allocating a large strm->next_out buffer and copying into it.
560 * (See also read_buf()).
561 */
562 local void flush_pending(strm)
563 z_streamp strm;
564 {
565 unsigned len = strm->state->pending;
566
567 if (len > strm->avail_out) len = strm->avail_out;
568 if (len == 0) return;
569
570 zmemcpy(strm->next_out, strm->state->pending_out, len);
571 strm->next_out += len;
572 strm->state->pending_out += len;
573 strm->total_out += len;
574 strm->avail_out -= len;
575 strm->state->pending -= len;
576 if (strm->state->pending == 0) {
577 strm->state->pending_out = strm->state->pending_buf;
578 }
579 }
580
581 /* ========================================================================= */
582 int ZEXPORT deflate (strm, flush)
583 z_streamp strm;
584 int flush;
585 {
586 int old_flush; /* value of flush param for previous deflate call */
587 deflate_state *s;
588
589 if (strm == Z_NULL || strm->state == Z_NULL ||
590 flush > Z_BLOCK || flush < 0) {
591 return Z_STREAM_ERROR;
592 }
593 s = strm->state;
594
595 if (strm->next_out == Z_NULL ||
596 (strm->next_in == Z_NULL && strm->avail_in != 0) ||
597 (s->status == FINISH_STATE && flush != Z_FINISH)) {
598 ERR_RETURN(strm, Z_STREAM_ERROR);
599 }
600 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
601
602 s->strm = strm; /* just in case */
603 old_flush = s->last_flush;
604 s->last_flush = flush;
605
606 /* Write the header */
607 if (s->status == INIT_STATE) {
608 #ifdef GZIP
609 if (s->wrap == 2) {
610 strm->adler = crc32(0L, Z_NULL, 0);
611 put_byte(s, 31);
612 put_byte(s, 139);
613 put_byte(s, 8);
614 if (s->gzhead == Z_NULL) {
615 put_byte(s, 0);
616 put_byte(s, 0);
617 put_byte(s, 0);
618 put_byte(s, 0);
619 put_byte(s, 0);
620 put_byte(s, s->level == 9 ? 2 :
621 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
622 4 : 0));
623 put_byte(s, OS_CODE);
624 s->status = BUSY_STATE;
625 }
626 else {
627 put_byte(s, (s->gzhead->text ? 1 : 0) +
628 (s->gzhead->hcrc ? 2 : 0) +
629 (s->gzhead->extra == Z_NULL ? 0 : 4) +
630 (s->gzhead->name == Z_NULL ? 0 : 8) +
631 (s->gzhead->comment == Z_NULL ? 0 : 16)
632 );
633 put_byte(s, (Byte)(s->gzhead->time & 0xff));
634 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
635 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
636 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
637 put_byte(s, s->level == 9 ? 2 :
638 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
639 4 : 0));
640 put_byte(s, s->gzhead->os & 0xff);
641 if (s->gzhead->extra != Z_NULL) {
642 put_byte(s, s->gzhead->extra_len & 0xff);
643 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
644 }
645 if (s->gzhead->hcrc)
646 strm->adler = crc32(strm->adler, s->pending_buf,
647 s->pending);
648 s->gzindex = 0;
649 s->status = EXTRA_STATE;
650 }
651 }
652 else
653 #endif
654 {
655 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
656 uInt level_flags;
657
658 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
659 level_flags = 0;
660 else if (s->level < 6)
661 level_flags = 1;
662 else if (s->level == 6)
663 level_flags = 2;
664 else
665 level_flags = 3;
666 header |= (level_flags << 6);
667 if (s->strstart != 0) header |= PRESET_DICT;
668 header += 31 - (header % 31);
669
670 s->status = BUSY_STATE;
671 putShortMSB(s, header);
672
673 /* Save the adler32 of the preset dictionary: */
674 if (s->strstart != 0) {
675 putShortMSB(s, (uInt)(strm->adler >> 16));
676 putShortMSB(s, (uInt)(strm->adler & 0xffff));
677 }
678 strm->adler = adler32(0L, Z_NULL, 0);
679 }
680 }
681 #ifdef GZIP
682 if (s->status == EXTRA_STATE) {
683 if (s->gzhead->extra != Z_NULL) {
684 uInt beg = s->pending; /* start of bytes to update crc */
685
686 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
687 if (s->pending == s->pending_buf_size) {
688 if (s->gzhead->hcrc && s->pending > beg)
689 strm->adler = crc32(strm->adler, s->pending_buf + beg,
690 s->pending - beg);
691 flush_pending(strm);
692 beg = s->pending;
693 if (s->pending == s->pending_buf_size)
694 break;
695 }
696 put_byte(s, s->gzhead->extra[s->gzindex]);
697 s->gzindex++;
698 }
699 if (s->gzhead->hcrc && s->pending > beg)
700 strm->adler = crc32(strm->adler, s->pending_buf + beg,
701 s->pending - beg);
702 if (s->gzindex == s->gzhead->extra_len) {
703 s->gzindex = 0;
704 s->status = NAME_STATE;
705 }
706 }
707 else
708 s->status = NAME_STATE;
709 }
710 if (s->status == NAME_STATE) {
711 if (s->gzhead->name != Z_NULL) {
712 uInt beg = s->pending; /* start of bytes to update crc */
713 int val;
714
715 do {
716 if (s->pending == s->pending_buf_size) {
717 if (s->gzhead->hcrc && s->pending > beg)
718 strm->adler = crc32(strm->adler, s->pending_buf + beg,
719 s->pending - beg);
720 flush_pending(strm);
721 beg = s->pending;
722 if (s->pending == s->pending_buf_size) {
723 val = 1;
724 break;
725 }
726 }
727 val = s->gzhead->name[s->gzindex++];
728 put_byte(s, val);
729 } while (val != 0);
730 if (s->gzhead->hcrc && s->pending > beg)
731 strm->adler = crc32(strm->adler, s->pending_buf + beg,
732 s->pending - beg);
733 if (val == 0) {
734 s->gzindex = 0;
735 s->status = COMMENT_STATE;
736 }
737 }
738 else
739 s->status = COMMENT_STATE;
740 }
741 if (s->status == COMMENT_STATE) {
742 if (s->gzhead->comment != Z_NULL) {
743 uInt beg = s->pending; /* start of bytes to update crc */
744 int val;
745
746 do {
747 if (s->pending == s->pending_buf_size) {
748 if (s->gzhead->hcrc && s->pending > beg)
749 strm->adler = crc32(strm->adler, s->pending_buf + beg,
750 s->pending - beg);
751 flush_pending(strm);
752 beg = s->pending;
753 if (s->pending == s->pending_buf_size) {
754 val = 1;
755 break;
756 }
757 }
758 val = s->gzhead->comment[s->gzindex++];
759 put_byte(s, val);
760 } while (val != 0);
761 if (s->gzhead->hcrc && s->pending > beg)
762 strm->adler = crc32(strm->adler, s->pending_buf + beg,
763 s->pending - beg);
764 if (val == 0)
765 s->status = HCRC_STATE;
766 }
767 else
768 s->status = HCRC_STATE;
769 }
770 if (s->status == HCRC_STATE) {
771 if (s->gzhead->hcrc) {
772 if (s->pending + 2 > s->pending_buf_size)
773 flush_pending(strm);
774 if (s->pending + 2 <= s->pending_buf_size) {
775 put_byte(s, (Byte)(strm->adler & 0xff));
776 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
777 strm->adler = crc32(0L, Z_NULL, 0);
778 s->status = BUSY_STATE;
779 }
780 }
781 else
782 s->status = BUSY_STATE;
783 }
784 #endif
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 && flush <= 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 /* Start a new block or continue the current one.
815 */
816 if (strm->avail_in != 0 || s->lookahead != 0 ||
817 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
818 block_state bstate;
819
820 bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
821 (s->strategy == Z_RLE ? deflate_rle(s, flush) :
822 (*(configuration_table[s->level].func))(s, flush));
823
824 if (bstate == finish_started || bstate == finish_done) {
825 s->status = FINISH_STATE;
826 }
827 if (bstate == need_more || bstate == finish_started) {
828 if (strm->avail_out == 0) {
829 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
830 }
831 return Z_OK;
832 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
833 * of deflate should use the same flush parameter to make sure
834 * that the flush is complete. So we don't have to output an
835 * empty block here, this will be done at next call. This also
836 * ensures that for a very small output buffer, we emit at most
837 * one empty block.
838 */
839 }
840 if (bstate == block_done) {
841 if (flush == Z_PARTIAL_FLUSH) {
842 _tr_align(s);
843 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
844 _tr_stored_block(s, (char*)0, 0L, 0);
845 /* For a full flush, this empty block will be recognized
846 * as a special marker by inflate_sync().
847 */
848 if (flush == Z_FULL_FLUSH) {
849 CLEAR_HASH(s); /* forget history */
850 if (s->lookahead == 0) {
851 s->strstart = 0;
852 s->block_start = 0L;
853 }
854 }
855 }
856 flush_pending(strm);
857 if (strm->avail_out == 0) {
858 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
859 return Z_OK;
860 }
861 }
862 }
863 Assert(strm->avail_out > 0, "bug2");
864
865 if (flush != Z_FINISH) return Z_OK;
866 if (s->wrap <= 0) return Z_STREAM_END;
867
868 /* Write the trailer */
869 #ifdef GZIP
870 if (s->wrap == 2) {
871 put_byte(s, (Byte)(strm->adler & 0xff));
872 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
873 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
874 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
875 put_byte(s, (Byte)(strm->total_in & 0xff));
876 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
877 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
878 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
879 }
880 else
881 #endif
882 {
883 putShortMSB(s, (uInt)(strm->adler >> 16));
884 putShortMSB(s, (uInt)(strm->adler & 0xffff));
885 }
886 flush_pending(strm);
887 /* If avail_out is zero, the application will call deflate again
888 * to flush the rest.
889 */
890 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
891 return s->pending != 0 ? Z_OK : Z_STREAM_END;
892 }
893
894 /* ========================================================================= */
895 int ZEXPORT deflateEnd (strm)
896 z_streamp strm;
897 {
898 int status;
899
900 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
901
902 status = strm->state->status;
903 if (status != INIT_STATE &&
904 status != EXTRA_STATE &&
905 status != NAME_STATE &&
906 status != COMMENT_STATE &&
907 status != HCRC_STATE &&
908 status != BUSY_STATE &&
909 status != FINISH_STATE) {
910 return Z_STREAM_ERROR;
911 }
912
913 /* Deallocate in reverse order of allocations: */
914 TRY_FREE(strm, strm->state->pending_buf);
915 TRY_FREE(strm, strm->state->head);
916 TRY_FREE(strm, strm->state->prev);
917 TRY_FREE(strm, strm->state->window);
918
919 ZFREE(strm, strm->state);
920 strm->state = Z_NULL;
921
922 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
923 }
924
925 /* =========================================================================
926 * Copy the source state to the destination state.
927 * To simplify the source, this is not supported for 16-bit MSDOS (which
928 * doesn't have enough memory anyway to duplicate compression states).
929 */
930 int ZEXPORT deflateCopy (dest, source)
931 z_streamp dest;
932 z_streamp source;
933 {
934 #ifdef MAXSEG_64K
935 return Z_STREAM_ERROR;
936 #else
937 deflate_state *ds;
938 deflate_state *ss;
939 ushf *overlay;
940
941
942 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
943 return Z_STREAM_ERROR;
944 }
945
946 ss = source->state;
947
948 zmemcpy(dest, source, sizeof(z_stream));
949
950 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
951 if (ds == Z_NULL) return Z_MEM_ERROR;
952 dest->state = (struct internal_state FAR *) ds;
953 zmemcpy(ds, ss, sizeof(deflate_state));
954 ds->strm = dest;
955
956 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
957 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
958 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
959 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
960 ds->pending_buf = (uchf *) overlay;
961
962 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
963 ds->pending_buf == Z_NULL) {
964 deflateEnd (dest);
965 return Z_MEM_ERROR;
966 }
967 /* following zmemcpy do not work for 16-bit MSDOS */
968 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
969 zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
970 zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
971 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
972
973 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
974 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
975 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
976
977 ds->l_desc.dyn_tree = ds->dyn_ltree;
978 ds->d_desc.dyn_tree = ds->dyn_dtree;
979 ds->bl_desc.dyn_tree = ds->bl_tree;
980
981 return Z_OK;
982 #endif /* MAXSEG_64K */
983 }
984
985 /* ===========================================================================
986 * Read a new buffer from the current input stream, update the adler32
987 * and total number of bytes read. All deflate() input goes through
988 * this function so some applications may wish to modify it to avoid
989 * allocating a large strm->next_in buffer and copying from it.
990 * (See also flush_pending()).
991 */
992 local int read_buf(strm, buf, size)
993 z_streamp strm;
994 Bytef *buf;
995 unsigned size;
996 {
997 unsigned len = strm->avail_in;
998
999 if (len > size) len = size;
1000 if (len == 0) return 0;
1001
1002 strm->avail_in -= len;
1003
1004 if (strm->state->wrap == 1) {
1005 strm->adler = adler32(strm->adler, strm->next_in, len);
1006 }
1007 #ifdef GZIP
1008 else if (strm->state->wrap == 2) {
1009 strm->adler = crc32(strm->adler, strm->next_in, len);
1010 }
1011 #endif
1012 zmemcpy(buf, strm->next_in, len);
1013 strm->next_in += len;
1014 strm->total_in += len;
1015
1016 return (int)len;
1017 }
1018
1019 /* ===========================================================================
1020 * Initialize the "longest match" routines for a new zlib stream
1021 */
1022 local void lm_init (s)
1023 deflate_state *s;
1024 {
1025 s->window_size = (ulg)2L*s->w_size;
1026
1027 CLEAR_HASH(s);
1028
1029 /* Set the default configuration parameters:
1030 */
1031 s->max_lazy_match = configuration_table[s->level].max_lazy;
1032 s->good_match = configuration_table[s->level].good_length;
1033 s->nice_match = configuration_table[s->level].nice_length;
1034 s->max_chain_length = configuration_table[s->level].max_chain;
1035
1036 s->strstart = 0;
1037 s->block_start = 0L;
1038 s->lookahead = 0;
1039 s->match_length = s->prev_length = MIN_MATCH-1;
1040 s->match_available = 0;
1041 s->ins_h = 0;
1042 #ifndef FASTEST
1043 #ifdef ASMV
1044 match_init(); /* initialize the asm code */
1045 #endif
1046 #endif
1047 }
1048
1049 #ifndef FASTEST
1050 /* ===========================================================================
1051 * Set match_start to the longest match starting at the given string and
1052 * return its length. Matches shorter or equal to prev_length are discarded,
1053 * in which case the result is equal to prev_length and match_start is
1054 * garbage.
1055 * IN assertions: cur_match is the head of the hash chain for the current
1056 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1057 * OUT assertion: the match length is not greater than s->lookahead.
1058 */
1059 #ifndef ASMV
1060 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1061 * match.S. The code will be functionally equivalent.
1062 */
1063 local uInt longest_match(s, cur_match)
1064 deflate_state *s;
1065 IPos cur_match; /* current match */
1066 {
1067 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1068 register Bytef *scan = s->window + s->strstart; /* current string */
1069 register Bytef *match; /* matched string */
1070 register int len; /* length of current match */
1071 int best_len = s->prev_length; /* best match length so far */
1072 int nice_match = s->nice_match; /* stop if match long enough */
1073 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1074 s->strstart - (IPos)MAX_DIST(s) : NIL;
1075 /* Stop when cur_match becomes <= limit. To simplify the code,
1076 * we prevent matches with the string of window index 0.
1077 */
1078 Posf *prev = s->prev;
1079 uInt wmask = s->w_mask;
1080
1081 #ifdef UNALIGNED_OK
1082 /* Compare two bytes at a time. Note: this is not always beneficial.
1083 * Try with and without -DUNALIGNED_OK to check.
1084 */
1085 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1086 register ush scan_start = *(ushf*)scan;
1087 register ush scan_end = *(ushf*)(scan+best_len-1);
1088 #else
1089 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1090 register Byte scan_end1 = scan[best_len-1];
1091 register Byte scan_end = scan[best_len];
1092 #endif
1093
1094 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1095 * It is easy to get rid of this optimization if necessary.
1096 */
1097 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1098
1099 /* Do not waste too much time if we already have a good match: */
1100 if (s->prev_length >= s->good_match) {
1101 chain_length >>= 2;
1102 }
1103 /* Do not look for matches beyond the end of the input. This is necessary
1104 * to make deflate deterministic.
1105 */
1106 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1107
1108 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1109
1110 do {
1111 Assert(cur_match < s->strstart, "no future");
1112 match = s->window + cur_match;
1113
1114 /* Skip to next match if the match length cannot increase
1115 * or if the match length is less than 2. Note that the checks below
1116 * for insufficient lookahead only occur occasionally for performance
1117 * reasons. Therefore uninitialized memory will be accessed, and
1118 * conditional jumps will be made that depend on those values.
1119 * However the length of the match is limited to the lookahead, so
1120 * the output of deflate is not affected by the uninitialized values.
1121 */
1122 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1123 /* This code assumes sizeof(unsigned short) == 2. Do not use
1124 * UNALIGNED_OK if your compiler uses a different size.
1125 */
1126 if (*(ushf*)(match+best_len-1) != scan_end ||
1127 *(ushf*)match != scan_start) continue;
1128
1129 /* It is not necessary to compare scan[2] and match[2] since they are
1130 * always equal when the other bytes match, given that the hash keys
1131 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1132 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1133 * lookahead only every 4th comparison; the 128th check will be made
1134 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1135 * necessary to put more guard bytes at the end of the window, or
1136 * to check more often for insufficient lookahead.
1137 */
1138 Assert(scan[2] == match[2], "scan[2]?");
1139 scan++, match++;
1140 do {
1141 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1142 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1143 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1144 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1145 scan < strend);
1146 /* The funny "do {}" generates better code on most compilers */
1147
1148 /* Here, scan <= window+strstart+257 */
1149 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1150 if (*scan == *match) scan++;
1151
1152 len = (MAX_MATCH - 1) - (int)(strend-scan);
1153 scan = strend - (MAX_MATCH-1);
1154
1155 #else /* UNALIGNED_OK */
1156
1157 if (match[best_len] != scan_end ||
1158 match[best_len-1] != scan_end1 ||
1159 *match != *scan ||
1160 *++match != scan[1]) continue;
1161
1162 /* The check at best_len-1 can be removed because it will be made
1163 * again later. (This heuristic is not always a win.)
1164 * It is not necessary to compare scan[2] and match[2] since they
1165 * are always equal when the other bytes match, given that
1166 * the hash keys are equal and that HASH_BITS >= 8.
1167 */
1168 scan += 2, match++;
1169 Assert(*scan == *match, "match[2]?");
1170
1171 /* We check for insufficient lookahead only every 8th comparison;
1172 * the 256th check will be made at strstart+258.
1173 */
1174 do {
1175 } while (*++scan == *++match && *++scan == *++match &&
1176 *++scan == *++match && *++scan == *++match &&
1177 *++scan == *++match && *++scan == *++match &&
1178 *++scan == *++match && *++scan == *++match &&
1179 scan < strend);
1180
1181 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1182
1183 len = MAX_MATCH - (int)(strend - scan);
1184 scan = strend - MAX_MATCH;
1185
1186 #endif /* UNALIGNED_OK */
1187
1188 if (len > best_len) {
1189 s->match_start = cur_match;
1190 best_len = len;
1191 if (len >= nice_match) break;
1192 #ifdef UNALIGNED_OK
1193 scan_end = *(ushf*)(scan+best_len-1);
1194 #else
1195 scan_end1 = scan[best_len-1];
1196 scan_end = scan[best_len];
1197 #endif
1198 }
1199 } while ((cur_match = prev[cur_match & wmask]) > limit
1200 && --chain_length != 0);
1201
1202 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1203 return s->lookahead;
1204 }
1205 #endif /* ASMV */
1206
1207 #else /* FASTEST */
1208
1209 /* ---------------------------------------------------------------------------
1210 * Optimized version for FASTEST only
1211 */
1212 local uInt longest_match(s, cur_match)
1213 deflate_state *s;
1214 IPos cur_match; /* current match */
1215 {
1216 register Bytef *scan = s->window + s->strstart; /* current string */
1217 register Bytef *match; /* matched string */
1218 register int len; /* length of current match */
1219 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1220
1221 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1222 * It is easy to get rid of this optimization if necessary.
1223 */
1224 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1225
1226 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1227
1228 Assert(cur_match < s->strstart, "no future");
1229
1230 match = s->window + cur_match;
1231
1232 /* Return failure if the match length is less than 2:
1233 */
1234 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1235
1236 /* The check at best_len-1 can be removed because it will be made
1237 * again later. (This heuristic is not always a win.)
1238 * It is not necessary to compare scan[2] and match[2] since they
1239 * are always equal when the other bytes match, given that
1240 * the hash keys are equal and that HASH_BITS >= 8.
1241 */
1242 scan += 2, match += 2;
1243 Assert(*scan == *match, "match[2]?");
1244
1245 /* We check for insufficient lookahead only every 8th comparison;
1246 * the 256th check will be made at strstart+258.
1247 */
1248 do {
1249 } while (*++scan == *++match && *++scan == *++match &&
1250 *++scan == *++match && *++scan == *++match &&
1251 *++scan == *++match && *++scan == *++match &&
1252 *++scan == *++match && *++scan == *++match &&
1253 scan < strend);
1254
1255 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1256
1257 len = MAX_MATCH - (int)(strend - scan);
1258
1259 if (len < MIN_MATCH) return MIN_MATCH - 1;
1260
1261 s->match_start = cur_match;
1262 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1263 }
1264
1265 #endif /* FASTEST */
1266
1267 #ifdef DEBUG
1268 /* ===========================================================================
1269 * Check that the match at match_start is indeed a match.
1270 */
1271 local void check_match(s, start, match, length)
1272 deflate_state *s;
1273 IPos start, match;
1274 int length;
1275 {
1276 /* check that the match is indeed a match */
1277 if (zmemcmp(s->window + match,
1278 s->window + start, length) != EQUAL) {
1279 fprintf(stderr, " start %u, match %u, length %d\n",
1280 start, match, length);
1281 do {
1282 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1283 } while (--length != 0);
1284 z_error("invalid match");
1285 }
1286 if (z_verbose > 1) {
1287 fprintf(stderr,"\\[%d,%d]", start-match, length);
1288 do { putc(s->window[start++], stderr); } while (--length != 0);
1289 }
1290 }
1291 #else
1292 # define check_match(s, start, match, length)
1293 #endif /* DEBUG */
1294
1295 /* ===========================================================================
1296 * Fill the window when the lookahead becomes insufficient.
1297 * Updates strstart and lookahead.
1298 *
1299 * IN assertion: lookahead < MIN_LOOKAHEAD
1300 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1301 * At least one byte has been read, or avail_in == 0; reads are
1302 * performed for at least two bytes (required for the zip translate_eol
1303 * option -- not supported here).
1304 */
1305 local void fill_window(s)
1306 deflate_state *s;
1307 {
1308 register unsigned n, m;
1309 register Posf *p;
1310 unsigned more; /* Amount of free space at the end of the window. */
1311 uInt wsize = s->w_size;
1312
1313 do {
1314 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1315
1316 /* Deal with !@#$% 64K limit: */
1317 if (sizeof(int) <= 2) {
1318 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1319 more = wsize;
1320
1321 } else if (more == (unsigned)(-1)) {
1322 /* Very unlikely, but possible on 16 bit machine if
1323 * strstart == 0 && lookahead == 1 (input done a byte at time)
1324 */
1325 more--;
1326 }
1327 }
1328
1329 /* If the window is almost full and there is insufficient lookahead,
1330 * move the upper half to the lower one to make room in the upper half.
1331 */
1332 if (s->strstart >= wsize+MAX_DIST(s)) {
1333
1334 zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1335 s->match_start -= wsize;
1336 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1337 s->block_start -= (long) wsize;
1338
1339 /* Slide the hash table (could be avoided with 32 bit values
1340 at the expense of memory usage). We slide even when level == 0
1341 to keep the hash table consistent if we switch back to level > 0
1342 later. (Using level 0 permanently is not an optimal usage of
1343 zlib, so we don't care about this pathological case.)
1344 */
1345 n = s->hash_size;
1346 p = &s->head[n];
1347 do {
1348 m = *--p;
1349 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1350 } while (--n);
1351
1352 n = wsize;
1353 #ifndef FASTEST
1354 p = &s->prev[n];
1355 do {
1356 m = *--p;
1357 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1358 /* If n is not on any hash chain, prev[n] is garbage but
1359 * its value will never be used.
1360 */
1361 } while (--n);
1362 #endif
1363 more += wsize;
1364 }
1365 if (s->strm->avail_in == 0) return;
1366
1367 /* If there was no sliding:
1368 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1369 * more == window_size - lookahead - strstart
1370 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1371 * => more >= window_size - 2*WSIZE + 2
1372 * In the BIG_MEM or MMAP case (not yet supported),
1373 * window_size == input_size + MIN_LOOKAHEAD &&
1374 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1375 * Otherwise, window_size == 2*WSIZE so more >= 2.
1376 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1377 */
1378 Assert(more >= 2, "more < 2");
1379
1380 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1381 s->lookahead += n;
1382
1383 /* Initialize the hash value now that we have some input: */
1384 if (s->lookahead >= MIN_MATCH) {
1385 s->ins_h = s->window[s->strstart];
1386 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1387 #if MIN_MATCH != 3
1388 Call UPDATE_HASH() MIN_MATCH-3 more times
1389 #endif
1390 }
1391 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1392 * but this is not important since only literal bytes will be emitted.
1393 */
1394
1395 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1396
1397 /* If the WIN_INIT bytes after the end of the current data have never been
1398 * written, then zero those bytes in order to avoid memory check reports of
1399 * the use of uninitialized (or uninitialised as Julian writes) bytes by
1400 * the longest match routines. Update the high water mark for the next
1401 * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1402 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1403 */
1404 if (s->high_water < s->window_size) {
1405 ulg curr = s->strstart + (ulg)(s->lookahead);
1406 ulg init;
1407
1408 if (s->high_water < curr) {
1409 /* Previous high water mark below current data -- zero WIN_INIT
1410 * bytes or up to end of window, whichever is less.
1411 */
1412 init = s->window_size - curr;
1413 if (init > WIN_INIT)
1414 init = WIN_INIT;
1415 zmemzero(s->window + curr, (unsigned)init);
1416 s->high_water = curr + init;
1417 }
1418 else if (s->high_water < (ulg)curr + WIN_INIT) {
1419 /* High water mark at or above current data, but below current data
1420 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1421 * to end of window, whichever is less.
1422 */
1423 init = (ulg)curr + WIN_INIT - s->high_water;
1424 if (init > s->window_size - s->high_water)
1425 init = s->window_size - s->high_water;
1426 zmemzero(s->window + s->high_water, (unsigned)init);
1427 s->high_water += init;
1428 }
1429 }
1430 }
1431
1432 /* ===========================================================================
1433 * Flush the current block, with given end-of-file flag.
1434 * IN assertion: strstart is set to the end of the current match.
1435 */
1436 #define FLUSH_BLOCK_ONLY(s, last) { \
1437 _tr_flush_block(s, (s->block_start >= 0L ? \
1438 (charf *)&s->window[(unsigned)s->block_start] : \
1439 (charf *)Z_NULL), \
1440 (ulg)((long)s->strstart - s->block_start), \
1441 (last)); \
1442 s->block_start = s->strstart; \
1443 flush_pending(s->strm); \
1444 Tracev((stderr,"[FLUSH]")); \
1445 }
1446
1447 /* Same but force premature exit if necessary. */
1448 #define FLUSH_BLOCK(s, last) { \
1449 FLUSH_BLOCK_ONLY(s, last); \
1450 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1451 }
1452
1453 /* ===========================================================================
1454 * Copy without compression as much as possible from the input stream, return
1455 * the current block state.
1456 * This function does not insert new strings in the dictionary since
1457 * uncompressible data is probably not useful. This function is used
1458 * only for the level=0 compression option.
1459 * NOTE: this function should be optimized to avoid extra copying from
1460 * window to pending_buf.
1461 */
1462 local block_state deflate_stored(s, flush)
1463 deflate_state *s;
1464 int flush;
1465 {
1466 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1467 * to pending_buf_size, and each stored block has a 5 byte header:
1468 */
1469 ulg max_block_size = 0xffff;
1470 ulg max_start;
1471
1472 if (max_block_size > s->pending_buf_size - 5) {
1473 max_block_size = s->pending_buf_size - 5;
1474 }
1475
1476 /* Copy as much as possible from input to output: */
1477 for (;;) {
1478 /* Fill the window as much as possible: */
1479 if (s->lookahead <= 1) {
1480
1481 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1482 s->block_start >= (long)s->w_size, "slide too late");
1483
1484 fill_window(s);
1485 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1486
1487 if (s->lookahead == 0) break; /* flush the current block */
1488 }
1489 Assert(s->block_start >= 0L, "block gone");
1490
1491 s->strstart += s->lookahead;
1492 s->lookahead = 0;
1493
1494 /* Emit a stored block if pending_buf will be full: */
1495 max_start = s->block_start + max_block_size;
1496 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1497 /* strstart == 0 is possible when wraparound on 16-bit machine */
1498 s->lookahead = (uInt)(s->strstart - max_start);
1499 s->strstart = (uInt)max_start;
1500 FLUSH_BLOCK(s, 0);
1501 }
1502 /* Flush if we may have to slide, otherwise block_start may become
1503 * negative and the data will be gone:
1504 */
1505 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1506 FLUSH_BLOCK(s, 0);
1507 }
1508 }
1509 FLUSH_BLOCK(s, flush == Z_FINISH);
1510 return flush == Z_FINISH ? finish_done : block_done;
1511 }
1512
1513 /* ===========================================================================
1514 * Compress as much as possible from the input stream, return the current
1515 * block state.
1516 * This function does not perform lazy evaluation of matches and inserts
1517 * new strings in the dictionary only for unmatched strings or for short
1518 * matches. It is used only for the fast compression options.
1519 */
1520 local block_state deflate_fast(s, flush)
1521 deflate_state *s;
1522 int flush;
1523 {
1524 IPos hash_head; /* head of the hash chain */
1525 int bflush; /* set if current block must be flushed */
1526
1527 for (;;) {
1528 /* Make sure that we always have enough lookahead, except
1529 * at the end of the input file. We need MAX_MATCH bytes
1530 * for the next match, plus MIN_MATCH bytes to insert the
1531 * string following the next match.
1532 */
1533 if (s->lookahead < MIN_LOOKAHEAD) {
1534 fill_window(s);
1535 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1536 return need_more;
1537 }
1538 if (s->lookahead == 0) break; /* flush the current block */
1539 }
1540
1541 /* Insert the string window[strstart .. strstart+2] in the
1542 * dictionary, and set hash_head to the head of the hash chain:
1543 */
1544 hash_head = NIL;
1545 if (s->lookahead >= MIN_MATCH) {
1546 INSERT_STRING(s, s->strstart, hash_head);
1547 }
1548
1549 /* Find the longest match, discarding those <= prev_length.
1550 * At this point we have always match_length < MIN_MATCH
1551 */
1552 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1553 /* To simplify the code, we prevent matches with the string
1554 * of window index 0 (in particular we have to avoid a match
1555 * of the string with itself at the start of the input file).
1556 */
1557 s->match_length = longest_match (s, hash_head);
1558 /* longest_match() sets match_start */
1559 }
1560 if (s->match_length >= MIN_MATCH) {
1561 check_match(s, s->strstart, s->match_start, s->match_length);
1562
1563 _tr_tally_dist(s, s->strstart - s->match_start,
1564 s->match_length - MIN_MATCH, bflush);
1565
1566 s->lookahead -= s->match_length;
1567
1568 /* Insert new strings in the hash table only if the match length
1569 * is not too large. This saves time but degrades compression.
1570 */
1571 #ifndef FASTEST
1572 if (s->match_length <= s->max_insert_length &&
1573 s->lookahead >= MIN_MATCH) {
1574 s->match_length--; /* string at strstart already in table */
1575 do {
1576 s->strstart++;
1577 INSERT_STRING(s, s->strstart, hash_head);
1578 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1579 * always MIN_MATCH bytes ahead.
1580 */
1581 } while (--s->match_length != 0);
1582 s->strstart++;
1583 } else
1584 #endif
1585 {
1586 s->strstart += s->match_length;
1587 s->match_length = 0;
1588 s->ins_h = s->window[s->strstart];
1589 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1590 #if MIN_MATCH != 3
1591 Call UPDATE_HASH() MIN_MATCH-3 more times
1592 #endif
1593 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1594 * matter since it will be recomputed at next deflate call.
1595 */
1596 }
1597 } else {
1598 /* No match, output a literal byte */
1599 Tracevv((stderr,"%c", s->window[s->strstart]));
1600 _tr_tally_lit (s, s->window[s->strstart], bflush);
1601 s->lookahead--;
1602 s->strstart++;
1603 }
1604 if (bflush) FLUSH_BLOCK(s, 0);
1605 }
1606 FLUSH_BLOCK(s, flush == Z_FINISH);
1607 return flush == Z_FINISH ? finish_done : block_done;
1608 }
1609
1610 #ifndef FASTEST
1611 /* ===========================================================================
1612 * Same as above, but achieves better compression. We use a lazy
1613 * evaluation for matches: a match is finally adopted only if there is
1614 * no better match at the next window position.
1615 */
1616 local block_state deflate_slow(s, flush)
1617 deflate_state *s;
1618 int flush;
1619 {
1620 IPos hash_head; /* head of hash chain */
1621 int bflush; /* set if current block must be flushed */
1622
1623 /* Process the input block. */
1624 for (;;) {
1625 /* Make sure that we always have enough lookahead, except
1626 * at the end of the input file. We need MAX_MATCH bytes
1627 * for the next match, plus MIN_MATCH bytes to insert the
1628 * string following the next match.
1629 */
1630 if (s->lookahead < MIN_LOOKAHEAD) {
1631 fill_window(s);
1632 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1633 return need_more;
1634 }
1635 if (s->lookahead == 0) break; /* flush the current block */
1636 }
1637
1638 /* Insert the string window[strstart .. strstart+2] in the
1639 * dictionary, and set hash_head to the head of the hash chain:
1640 */
1641 hash_head = NIL;
1642 if (s->lookahead >= MIN_MATCH) {
1643 INSERT_STRING(s, s->strstart, hash_head);
1644 }
1645
1646 /* Find the longest match, discarding those <= prev_length.
1647 */
1648 s->prev_length = s->match_length, s->prev_match = s->match_start;
1649 s->match_length = MIN_MATCH-1;
1650
1651 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1652 s->strstart - hash_head <= MAX_DIST(s)) {
1653 /* To simplify the code, we prevent matches with the string
1654 * of window index 0 (in particular we have to avoid a match
1655 * of the string with itself at the start of the input file).
1656 */
1657 s->match_length = longest_match (s, hash_head);
1658 /* longest_match() sets match_start */
1659
1660 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1661 #if TOO_FAR <= 32767
1662 || (s->match_length == MIN_MATCH &&
1663 s->strstart - s->match_start > TOO_FAR)
1664 #endif
1665 )) {
1666
1667 /* If prev_match is also MIN_MATCH, match_start is garbage
1668 * but we will ignore the current match anyway.
1669 */
1670 s->match_length = MIN_MATCH-1;
1671 }
1672 }
1673 /* If there was a match at the previous step and the current
1674 * match is not better, output the previous match:
1675 */
1676 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1677 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1678 /* Do not insert strings in hash table beyond this. */
1679
1680 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1681
1682 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1683 s->prev_length - MIN_MATCH, bflush);
1684
1685 /* Insert in hash table all strings up to the end of the match.
1686 * strstart-1 and strstart are already inserted. If there is not
1687 * enough lookahead, the last two strings are not inserted in
1688 * the hash table.
1689 */
1690 s->lookahead -= s->prev_length-1;
1691 s->prev_length -= 2;
1692 do {
1693 if (++s->strstart <= max_insert) {
1694 INSERT_STRING(s, s->strstart, hash_head);
1695 }
1696 } while (--s->prev_length != 0);
1697 s->match_available = 0;
1698 s->match_length = MIN_MATCH-1;
1699 s->strstart++;
1700
1701 if (bflush) FLUSH_BLOCK(s, 0);
1702
1703 } else if (s->match_available) {
1704 /* If there was no match at the previous position, output a
1705 * single literal. If there was a match but the current match
1706 * is longer, truncate the previous match to a single literal.
1707 */
1708 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1709 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1710 if (bflush) {
1711 FLUSH_BLOCK_ONLY(s, 0);
1712 }
1713 s->strstart++;
1714 s->lookahead--;
1715 if (s->strm->avail_out == 0) return need_more;
1716 } else {
1717 /* There is no previous match to compare with, wait for
1718 * the next step to decide.
1719 */
1720 s->match_available = 1;
1721 s->strstart++;
1722 s->lookahead--;
1723 }
1724 }
1725 Assert (flush != Z_NO_FLUSH, "no flush?");
1726 if (s->match_available) {
1727 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1728 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1729 s->match_available = 0;
1730 }
1731 FLUSH_BLOCK(s, flush == Z_FINISH);
1732 return flush == Z_FINISH ? finish_done : block_done;
1733 }
1734 #endif /* FASTEST */
1735
1736 /* ===========================================================================
1737 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1738 * one. Do not maintain a hash table. (It will be regenerated if this run of
1739 * deflate switches away from Z_RLE.)
1740 */
1741 local block_state deflate_rle(s, flush)
1742 deflate_state *s;
1743 int flush;
1744 {
1745 int bflush; /* set if current block must be flushed */
1746 uInt prev; /* byte at distance one to match */
1747 Bytef *scan, *strend; /* scan goes up to strend for length of run */
1748
1749 for (;;) {
1750 /* Make sure that we always have enough lookahead, except
1751 * at the end of the input file. We need MAX_MATCH bytes
1752 * for the longest encodable run.
1753 */
1754 if (s->lookahead < MAX_MATCH) {
1755 fill_window(s);
1756 if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {
1757 return need_more;
1758 }
1759 if (s->lookahead == 0) break; /* flush the current block */
1760 }
1761
1762 /* See how many times the previous byte repeats */
1763 s->match_length = 0;
1764 if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
1765 scan = s->window + s->strstart - 1;
1766 prev = *scan;
1767 if (prev == *++scan && prev == *++scan && prev == *++scan) {
1768 strend = s->window + s->strstart + MAX_MATCH;
1769 do {
1770 } while (prev == *++scan && prev == *++scan &&
1771 prev == *++scan && prev == *++scan &&
1772 prev == *++scan && prev == *++scan &&
1773 prev == *++scan && prev == *++scan &&
1774 scan < strend);
1775 s->match_length = MAX_MATCH - (int)(strend - scan);
1776 if (s->match_length > s->lookahead)
1777 s->match_length = s->lookahead;
1778 }
1779 }
1780
1781 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1782 if (s->match_length >= MIN_MATCH) {
1783 check_match(s, s->strstart, s->strstart - 1, s->match_length);
1784
1785 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
1786
1787 s->lookahead -= s->match_length;
1788 s->strstart += s->match_length;
1789 s->match_length = 0;
1790 } else {
1791 /* No match, output a literal byte */
1792 Tracevv((stderr,"%c", s->window[s->strstart]));
1793 _tr_tally_lit (s, s->window[s->strstart], bflush);
1794 s->lookahead--;
1795 s->strstart++;
1796 }
1797 if (bflush) FLUSH_BLOCK(s, 0);
1798 }
1799 FLUSH_BLOCK(s, flush == Z_FINISH);
1800 return flush == Z_FINISH ? finish_done : block_done;
1801 }
1802
1803 /* ===========================================================================
1804 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
1805 * (It will be regenerated if this run of deflate switches away from Huffman.)
1806 */
1807 local block_state deflate_huff(s, flush)
1808 deflate_state *s;
1809 int flush;
1810 {
1811 int bflush; /* set if current block must be flushed */
1812
1813 for (;;) {
1814 /* Make sure that we have a literal to write. */
1815 if (s->lookahead == 0) {
1816 fill_window(s);
1817 if (s->lookahead == 0) {
1818 if (flush == Z_NO_FLUSH)
1819 return need_more;
1820 break; /* flush the current block */
1821 }
1822 }
1823
1824 /* Output a literal byte */
1825 s->match_length = 0;
1826 Tracevv((stderr,"%c", s->window[s->strstart]));
1827 _tr_tally_lit (s, s->window[s->strstart], bflush);
1828 s->lookahead--;
1829 s->strstart++;
1830 if (bflush) FLUSH_BLOCK(s, 0);
1831 }
1832 FLUSH_BLOCK(s, flush == Z_FINISH);
1833 return flush == Z_FINISH ? finish_done : block_done;
1834 }

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