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/* @(#) $Id$ */
51
52#include "deflate.h"
53
54const char deflate_copyright[] =
55 " deflate 1.2.11 Copyright 1995-2017 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 */
66typedef 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
73typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74/* Compression function. Returns the block state after the call. */
75
76local int deflateStateCheck OF((z_streamp strm));
77local void slide_hash OF((deflate_state *s));
78local void fill_window OF((deflate_state *s));
79local block_state deflate_stored OF((deflate_state *s, int flush));
80local block_state deflate_fast OF((deflate_state *s, int flush));
81#ifndef FASTEST
82local block_state deflate_slow OF((deflate_state *s, int flush));
83#endif
84local block_state deflate_rle OF((deflate_state *s, int flush));
85local block_state deflate_huff OF((deflate_state *s, int flush));
86local void lm_init OF((deflate_state *s));
87local void putShortMSB OF((deflate_state *s, uInt b));
88local void flush_pending OF((z_streamp strm));
89local unsigned read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
90#ifdef ASMV
91# pragma message("Assembler code may have bugs -- use at your own risk")
92 void match_init OF((void)); /* asm code initialization */
93 uInt longest_match OF((deflate_state *s, IPos cur_match));
94#else
95local uInt longest_match OF((deflate_state *s, IPos cur_match));
96#endif
97
98#ifdef ZLIB_DEBUG
99local void check_match OF((deflate_state *s, IPos start, IPos match,
100 int length));
101#endif
102
103/* ===========================================================================
104 * Local data
105 */
106
107#define NIL 0
108/* Tail of hash chains */
109
110#ifndef TOO_FAR
111# define TOO_FAR 4096
112#endif
113/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
114
115/* Values for max_lazy_match, good_match and max_chain_length, depending on
116 * the desired pack level (0..9). The values given below have been tuned to
117 * exclude worst case performance for pathological files. Better values may be
118 * found for specific files.
119 */
120typedef struct config_s {
121 ush good_length; /* reduce lazy search above this match length */
122 ush max_lazy; /* do not perform lazy search above this match length */
123 ush nice_length; /* quit search above this match length */
124 ush max_chain;
125 compress_func func;
126} config;
127
128#ifdef FASTEST
129local const config configuration_table[2] = {
130/* good lazy nice chain */
131/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
132/* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
133#else
134local const config configuration_table[10] = {
135/* good lazy nice chain */
136/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
137/* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
138/* 2 */ {4, 5, 16, 8, deflate_fast},
139/* 3 */ {4, 6, 32, 32, deflate_fast},
140
141/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
142/* 5 */ {8, 16, 32, 32, deflate_slow},
143/* 6 */ {8, 16, 128, 128, deflate_slow},
144/* 7 */ {8, 32, 128, 256, deflate_slow},
145/* 8 */ {32, 128, 258, 1024, deflate_slow},
146/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
147#endif
148
149/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
150 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
151 * meaning.
152 */
153
154/* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
155#define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0))
156
157/* ===========================================================================
158 * Update a hash value with the given input byte
159 * IN assertion: all calls to UPDATE_HASH are made with consecutive input
160 * characters, so that a running hash key can be computed from the previous
161 * key instead of complete recalculation each time.
162 */
163#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
164
165
166/* ===========================================================================
167 * Insert string str in the dictionary and set match_head to the previous head
168 * of the hash chain (the most recent string with same hash key). Return
169 * the previous length of the hash chain.
170 * If this file is compiled with -DFASTEST, the compression level is forced
171 * to 1, and no hash chains are maintained.
172 * IN assertion: all calls to INSERT_STRING are made with consecutive input
173 * characters and the first MIN_MATCH bytes of str are valid (except for
174 * the last MIN_MATCH-1 bytes of the input file).
175 */
176#ifdef FASTEST
177#define INSERT_STRING(s, str, match_head) \
178 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
179 match_head = s->head[s->ins_h], \
180 s->head[s->ins_h] = (Pos)(str))
181#else
182#define INSERT_STRING(s, str, match_head) \
183 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
184 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
185 s->head[s->ins_h] = (Pos)(str))
186#endif
187
188/* ===========================================================================
189 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
190 * prev[] will be initialized on the fly.
191 */
192#define CLEAR_HASH(s) \
193 s->head[s->hash_size-1] = NIL; \
194 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
195
196/* ===========================================================================
197 * Slide the hash table when sliding the window down (could be avoided with 32
198 * bit values at the expense of memory usage). We slide even when level == 0 to
199 * keep the hash table consistent if we switch back to level > 0 later.
200 */
201local void slide_hash(s)
202 deflate_state *s;
203{
204 unsigned n, m;
205 Posf *p;
206 uInt wsize = s->w_size;
207
208 n = s->hash_size;
209 p = &s->head[n];
210 do {
211 m = *--p;
212 *p = (Pos)(m >= wsize ? m - wsize : NIL);
213 } while (--n);
214 n = wsize;
215#ifndef FASTEST
216 p = &s->prev[n];
217 do {
218 m = *--p;
219 *p = (Pos)(m >= wsize ? m - wsize : NIL);
220 /* If n is not on any hash chain, prev[n] is garbage but
221 * its value will never be used.
222 */
223 } while (--n);
224#endif
225}
226
227/* ========================================================================= */
228int ZEXPORT deflateInit_(strm, level, version, stream_size)
229 z_streamp strm;
230 int level;
231 const char *version;
232 int stream_size;
233{
234 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
235 Z_DEFAULT_STRATEGY, version, stream_size);
236 /* To do: ignore strm->next_in if we use it as window */
237}
238
239/* ========================================================================= */
240int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
241 version, stream_size)
242 z_streamp strm;
243 int level;
244 int method;
245 int windowBits;
246 int memLevel;
247 int strategy;
248 const char *version;
249 int stream_size;
250{
251 deflate_state *s;
252 int wrap = 1;
253 static const char my_version[] = ZLIB_VERSION;
254
255 ushf *overlay;
256 /* We overlay pending_buf and d_buf+l_buf. This works since the average
257 * output size for (length,distance) codes is <= 24 bits.
258 */
259
260 if (version == Z_NULL || version[0] != my_version[0] ||
261 stream_size != sizeof(z_stream)) {
262 return Z_VERSION_ERROR;
263 }
264 if (strm == Z_NULL) return Z_STREAM_ERROR;
265
266 strm->msg = Z_NULL;
267 if (strm->zalloc == (alloc_func)0) {
268#ifdef Z_SOLO
269 return Z_STREAM_ERROR;
270#else
271 strm->zalloc = zcalloc;
272 strm->opaque = (voidpf)0;
273#endif
274 }
275 if (strm->zfree == (free_func)0)
276#ifdef Z_SOLO
277 return Z_STREAM_ERROR;
278#else
279 strm->zfree = zcfree;
280#endif
281
282#ifdef FASTEST
283 if (level != 0) level = 1;
284#else
285 if (level == Z_DEFAULT_COMPRESSION) level = 6;
286#endif
287
288 if (windowBits < 0) { /* suppress zlib wrapper */
289 wrap = 0;
290 windowBits = -windowBits;
291 }
292#ifdef GZIP
293 else if (windowBits > 15) {
294 wrap = 2; /* write gzip wrapper instead */
295 windowBits -= 16;
296 }
297#endif
298 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
299 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
300 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) {
301 return Z_STREAM_ERROR;
302 }
303 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
304 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
305 if (s == Z_NULL) return Z_MEM_ERROR;
306 strm->state = (struct internal_state FAR *)s;
307 s->strm = strm;
308 s->status = INIT_STATE; /* to pass state test in deflateReset() */
309
310 s->wrap = wrap;
311 s->gzhead = Z_NULL;
312 s->w_bits = (uInt)windowBits;
313 s->w_size = 1 << s->w_bits;
314 s->w_mask = s->w_size - 1;
315
316 s->hash_bits = (uInt)memLevel + 7;
317 s->hash_size = 1 << s->hash_bits;
318 s->hash_mask = s->hash_size - 1;
319 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
320
321 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
322 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
323 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
324
325 s->high_water = 0; /* nothing written to s->window yet */
326
327 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
328
329 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
330 s->pending_buf = (uchf *) overlay;
331 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
332
333 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
334 s->pending_buf == Z_NULL) {
335 s->status = FINISH_STATE;
336 strm->msg = ERR_MSG(Z_MEM_ERROR);
337 deflateEnd (strm);
338 return Z_MEM_ERROR;
339 }
340 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
341 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
342
343 s->level = level;
344 s->strategy = strategy;
345 s->method = (Byte)method;
346
347 return deflateReset(strm);
348}
349
350/* =========================================================================
351 * Check for a valid deflate stream state. Return 0 if ok, 1 if not.
352 */
353local int deflateStateCheck (strm)
354 z_streamp strm;
355{
356 deflate_state *s;
357 if (strm == Z_NULL ||
358 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0)
359 return 1;
360 s = strm->state;
361 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE &&
362#ifdef GZIP
363 s->status != GZIP_STATE &&
364#endif
365 s->status != EXTRA_STATE &&
366 s->status != NAME_STATE &&
367 s->status != COMMENT_STATE &&
368 s->status != HCRC_STATE &&
369 s->status != BUSY_STATE &&
370 s->status != FINISH_STATE))
371 return 1;
372 return 0;
373}
374
375/* ========================================================================= */
376int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
377 z_streamp strm;
378 const Bytef *dictionary;
379 uInt dictLength;
380{
381 deflate_state *s;
382 uInt str, n;
383 int wrap;
384 unsigned avail;
385 z_const unsigned char *next;
386
387 if (deflateStateCheck(strm) || dictionary == Z_NULL)
388 return Z_STREAM_ERROR;
389 s = strm->state;
390 wrap = s->wrap;
391 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
392 return Z_STREAM_ERROR;
393
394 /* when using zlib wrappers, compute Adler-32 for provided dictionary */
395 if (wrap == 1)
396 strm->adler = adler32(strm->adler, dictionary, dictLength);
397 s->wrap = 0; /* avoid computing Adler-32 in read_buf */
398
399 /* if dictionary would fill window, just replace the history */
400 if (dictLength >= s->w_size) {
401 if (wrap == 0) { /* already empty otherwise */
402 CLEAR_HASH(s);
403 s->strstart = 0;
404 s->block_start = 0L;
405 s->insert = 0;
406 }
407 dictionary += dictLength - s->w_size; /* use the tail */
408 dictLength = s->w_size;
409 }
410
411 /* insert dictionary into window and hash */
412 avail = strm->avail_in;
413 next = strm->next_in;
414 strm->avail_in = dictLength;
415 strm->next_in = (z_const Bytef *)dictionary;
416 fill_window(s);
417 while (s->lookahead >= MIN_MATCH) {
418 str = s->strstart;
419 n = s->lookahead - (MIN_MATCH-1);
420 do {
421 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
422#ifndef FASTEST
423 s->prev[str & s->w_mask] = s->head[s->ins_h];
424#endif
425 s->head[s->ins_h] = (Pos)str;
426 str++;
427 } while (--n);
428 s->strstart = str;
429 s->lookahead = MIN_MATCH-1;
430 fill_window(s);
431 }
432 s->strstart += s->lookahead;
433 s->block_start = (long)s->strstart;
434 s->insert = s->lookahead;
435 s->lookahead = 0;
436 s->match_length = s->prev_length = MIN_MATCH-1;
437 s->match_available = 0;
438 strm->next_in = next;
439 strm->avail_in = avail;
440 s->wrap = wrap;
441 return Z_OK;
442}
443
444/* ========================================================================= */
445int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength)
446 z_streamp strm;
447 Bytef *dictionary;
448 uInt *dictLength;
449{
450 deflate_state *s;
451 uInt len;
452
453 if (deflateStateCheck(strm))
454 return Z_STREAM_ERROR;
455 s = strm->state;
456 len = s->strstart + s->lookahead;
457 if (len > s->w_size)
458 len = s->w_size;
459 if (dictionary != Z_NULL && len)
460 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len);
461 if (dictLength != Z_NULL)
462 *dictLength = len;
463 return Z_OK;
464}
465
466/* ========================================================================= */
467int ZEXPORT deflateResetKeep (strm)
468 z_streamp strm;
469{
470 deflate_state *s;
471
472 if (deflateStateCheck(strm)) {
473 return Z_STREAM_ERROR;
474 }
475
476 strm->total_in = strm->total_out = 0;
477 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
478 strm->data_type = Z_UNKNOWN;
479
480 s = (deflate_state *)strm->state;
481 s->pending = 0;
482 s->pending_out = s->pending_buf;
483
484 if (s->wrap < 0) {
485 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
486 }
487 s->status =
488#ifdef GZIP
489 s->wrap == 2 ? GZIP_STATE :
490#endif
491 s->wrap ? INIT_STATE : BUSY_STATE;
492 strm->adler =
493#ifdef GZIP
494 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
495#endif
496 adler32(0L, Z_NULL, 0);
497 s->last_flush = Z_NO_FLUSH;
498
499 _tr_init(s);
500
501 return Z_OK;
502}
503
504/* ========================================================================= */
505int ZEXPORT deflateReset (strm)
506 z_streamp strm;
507{
508 int ret;
509
510 ret = deflateResetKeep(strm);
511 if (ret == Z_OK)
512 lm_init(strm->state);
513 return ret;
514}
515
516/* ========================================================================= */
517int ZEXPORT deflateSetHeader (strm, head)
518 z_streamp strm;
519 gz_headerp head;
520{
521 if (deflateStateCheck(strm) || strm->state->wrap != 2)
522 return Z_STREAM_ERROR;
523 strm->state->gzhead = head;
524 return Z_OK;
525}
526
527/* ========================================================================= */
528int ZEXPORT deflatePending (strm, pending, bits)
529 unsigned *pending;
530 int *bits;
531 z_streamp strm;
532{
533 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
534 if (pending != Z_NULL)
535 *pending = strm->state->pending;
536 if (bits != Z_NULL)
537 *bits = strm->state->bi_valid;
538 return Z_OK;
539}
540
541/* ========================================================================= */
542int ZEXPORT deflatePrime (strm, bits, value)
543 z_streamp strm;
544 int bits;
545 int value;
546{
547 deflate_state *s;
548 int put;
549
550 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
551 s = strm->state;
552 if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
553 return Z_BUF_ERROR;
554 do {
555 put = Buf_size - s->bi_valid;
556 if (put > bits)
557 put = bits;
558 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
559 s->bi_valid += put;
560 _tr_flush_bits(s);
561 value >>= put;
562 bits -= put;
563 } while (bits);
564 return Z_OK;
565}
566
567/* ========================================================================= */
568int ZEXPORT deflateParams(strm, level, strategy)
569 z_streamp strm;
570 int level;
571 int strategy;
572{
573 deflate_state *s;
574 compress_func func;
575
576 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
577 s = strm->state;
578
579#ifdef FASTEST
580 if (level != 0) level = 1;
581#else
582 if (level == Z_DEFAULT_COMPRESSION) level = 6;
583#endif
584 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
585 return Z_STREAM_ERROR;
586 }
587 func = configuration_table[s->level].func;
588
589 if ((strategy != s->strategy || func != configuration_table[level].func) &&
590 s->high_water) {
591 /* Flush the last buffer: */
592 int err = deflate(strm, Z_BLOCK);
593 if (err == Z_STREAM_ERROR)
594 return err;
595 if (strm->avail_out == 0)
596 return Z_BUF_ERROR;
597 }
598 if (s->level != level) {
599 if (s->level == 0 && s->matches != 0) {
600 if (s->matches == 1)
601 slide_hash(s);
602 else
603 CLEAR_HASH(s);
604 s->matches = 0;
605 }
606 s->level = level;
607 s->max_lazy_match = configuration_table[level].max_lazy;
608 s->good_match = configuration_table[level].good_length;
609 s->nice_match = configuration_table[level].nice_length;
610 s->max_chain_length = configuration_table[level].max_chain;
611 }
612 s->strategy = strategy;
613 return Z_OK;
614}
615
616/* ========================================================================= */
617int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
618 z_streamp strm;
619 int good_length;
620 int max_lazy;
621 int nice_length;
622 int max_chain;
623{
624 deflate_state *s;
625
626 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
627 s = strm->state;
628 s->good_match = (uInt)good_length;
629 s->max_lazy_match = (uInt)max_lazy;
630 s->nice_match = nice_length;
631 s->max_chain_length = (uInt)max_chain;
632 return Z_OK;
633}
634
635/* =========================================================================
636 * For the default windowBits of 15 and memLevel of 8, this function returns
637 * a close to exact, as well as small, upper bound on the compressed size.
638 * They are coded as constants here for a reason--if the #define's are
639 * changed, then this function needs to be changed as well. The return
640 * value for 15 and 8 only works for those exact settings.
641 *
642 * For any setting other than those defaults for windowBits and memLevel,
643 * the value returned is a conservative worst case for the maximum expansion
644 * resulting from using fixed blocks instead of stored blocks, which deflate
645 * can emit on compressed data for some combinations of the parameters.
646 *
647 * This function could be more sophisticated to provide closer upper bounds for
648 * every combination of windowBits and memLevel. But even the conservative
649 * upper bound of about 14% expansion does not seem onerous for output buffer
650 * allocation.
651 */
652uLong ZEXPORT deflateBound(strm, sourceLen)
653 z_streamp strm;
654 uLong sourceLen;
655{
656 deflate_state *s;
657 uLong complen, wraplen;
658
659 /* conservative upper bound for compressed data */
660 complen = sourceLen +
661 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
662
663 /* if can't get parameters, return conservative bound plus zlib wrapper */
664 if (deflateStateCheck(strm))
665 return complen + 6;
666
667 /* compute wrapper length */
668 s = strm->state;
669 switch (s->wrap) {
670 case 0: /* raw deflate */
671 wraplen = 0;
672 break;
673 case 1: /* zlib wrapper */
674 wraplen = 6 + (s->strstart ? 4 : 0);
675 break;
676#ifdef GZIP
677 case 2: /* gzip wrapper */
678 wraplen = 18;
679 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
680 Bytef *str;
681 if (s->gzhead->extra != Z_NULL)
682 wraplen += 2 + s->gzhead->extra_len;
683 str = s->gzhead->name;
684 if (str != Z_NULL)
685 do {
686 wraplen++;
687 } while (*str++);
688 str = s->gzhead->comment;
689 if (str != Z_NULL)
690 do {
691 wraplen++;
692 } while (*str++);
693 if (s->gzhead->hcrc)
694 wraplen += 2;
695 }
696 break;
697#endif
698 default: /* for compiler happiness */
699 wraplen = 6;
700 }
701
702 /* if not default parameters, return conservative bound */
703 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
704 return complen + wraplen;
705
706 /* default settings: return tight bound for that case */
707 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
708 (sourceLen >> 25) + 13 - 6 + wraplen;
709}
710
711/* =========================================================================
712 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
713 * IN assertion: the stream state is correct and there is enough room in
714 * pending_buf.
715 */
716local void putShortMSB (s, b)
717 deflate_state *s;
718 uInt b;
719{
720 put_byte(s, (Byte)(b >> 8));
721 put_byte(s, (Byte)(b & 0xff));
722}
723
724/* =========================================================================
725 * Flush as much pending output as possible. All deflate() output, except for
726 * some deflate_stored() output, goes through this function so some
727 * applications may wish to modify it to avoid allocating a large
728 * strm->next_out buffer and copying into it. (See also read_buf()).
729 */
730local void flush_pending(strm)
731 z_streamp strm;
732{
733 unsigned len;
734 deflate_state *s = strm->state;
735
736 _tr_flush_bits(s);
737 len = s->pending;
738 if (len > strm->avail_out) len = strm->avail_out;
739 if (len == 0) return;
740
741 zmemcpy(strm->next_out, s->pending_out, len);
742 strm->next_out += len;
743 s->pending_out += len;
744 strm->total_out += len;
745 strm->avail_out -= len;
746 s->pending -= len;
747 if (s->pending == 0) {
748 s->pending_out = s->pending_buf;
749 }
750}
751
752/* ===========================================================================
753 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1].
754 */
755#define HCRC_UPDATE(beg) \
756 do { \
757 if (s->gzhead->hcrc && s->pending > (beg)) \
758 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \
759 s->pending - (beg)); \
760 } while (0)
761
762/* ========================================================================= */
763int ZEXPORT deflate (strm, flush)
764 z_streamp strm;
765 int flush;
766{
767 int old_flush; /* value of flush param for previous deflate call */
768 deflate_state *s;
769
770 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) {
771 return Z_STREAM_ERROR;
772 }
773 s = strm->state;
774
775 if (strm->next_out == Z_NULL ||
776 (strm->avail_in != 0 && strm->next_in == Z_NULL) ||
777 (s->status == FINISH_STATE && flush != Z_FINISH)) {
778 ERR_RETURN(strm, Z_STREAM_ERROR);
779 }
780 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
781
782 old_flush = s->last_flush;
783 s->last_flush = flush;
784
785 /* Flush as much pending output as possible */
786 if (s->pending != 0) {
787 flush_pending(strm);
788 if (strm->avail_out == 0) {
789 /* Since avail_out is 0, deflate will be called again with
790 * more output space, but possibly with both pending and
791 * avail_in equal to zero. There won't be anything to do,
792 * but this is not an error situation so make sure we
793 * return OK instead of BUF_ERROR at next call of deflate:
794 */
795 s->last_flush = -1;
796 return Z_OK;
797 }
798
799 /* Make sure there is something to do and avoid duplicate consecutive
800 * flushes. For repeated and useless calls with Z_FINISH, we keep
801 * returning Z_STREAM_END instead of Z_BUF_ERROR.
802 */
803 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
804 flush != Z_FINISH) {
805 ERR_RETURN(strm, Z_BUF_ERROR);
806 }
807
808 /* User must not provide more input after the first FINISH: */
809 if (s->status == FINISH_STATE && strm->avail_in != 0) {
810 ERR_RETURN(strm, Z_BUF_ERROR);
811 }
812
813 /* Write the header */
814 if (s->status == INIT_STATE) {
815 /* zlib header */
816 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
817 uInt level_flags;
818
819 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
820 level_flags = 0;
821 else if (s->level < 6)
822 level_flags = 1;
823 else if (s->level == 6)
824 level_flags = 2;
825 else
826 level_flags = 3;
827 header |= (level_flags << 6);
828 if (s->strstart != 0) header |= PRESET_DICT;
829 header += 31 - (header % 31);
830
831 putShortMSB(s, header);
832
833 /* Save the adler32 of the preset dictionary: */
834 if (s->strstart != 0) {
835 putShortMSB(s, (uInt)(strm->adler >> 16));
836 putShortMSB(s, (uInt)(strm->adler & 0xffff));
837 }
838 strm->adler = adler32(0L, Z_NULL, 0);
839 s->status = BUSY_STATE;
840
841 /* Compression must start with an empty pending buffer */
842 flush_pending(strm);
843 if (s->pending != 0) {
844 s->last_flush = -1;
845 return Z_OK;
846 }
847 }
848#ifdef GZIP
849 if (s->status == GZIP_STATE) {
850 /* gzip header */
851 strm->adler = crc32(0L, Z_NULL, 0);
852 put_byte(s, 31);
853 put_byte(s, 139);
854 put_byte(s, 8);
855 if (s->gzhead == Z_NULL) {
856 put_byte(s, 0);
857 put_byte(s, 0);
858 put_byte(s, 0);
859 put_byte(s, 0);
860 put_byte(s, 0);
861 put_byte(s, s->level == 9 ? 2 :
862 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
863 4 : 0));
864 put_byte(s, OS_CODE);
865 s->status = BUSY_STATE;
866
867 /* Compression must start with an empty pending buffer */
868 flush_pending(strm);
869 if (s->pending != 0) {
870 s->last_flush = -1;
871 return Z_OK;
872 }
873 }
874 else {
875 put_byte(s, (s->gzhead->text ? 1 : 0) +
876 (s->gzhead->hcrc ? 2 : 0) +
877 (s->gzhead->extra == Z_NULL ? 0 : 4) +
878 (s->gzhead->name == Z_NULL ? 0 : 8) +
879 (s->gzhead->comment == Z_NULL ? 0 : 16)
880 );
881 put_byte(s, (Byte)(s->gzhead->time & 0xff));
882 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
883 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
884 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
885 put_byte(s, s->level == 9 ? 2 :
886 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
887 4 : 0));
888 put_byte(s, s->gzhead->os & 0xff);
889 if (s->gzhead->extra != Z_NULL) {
890 put_byte(s, s->gzhead->extra_len & 0xff);
891 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
892 }
893 if (s->gzhead->hcrc)
894 strm->adler = crc32(strm->adler, s->pending_buf,
895 s->pending);
896 s->gzindex = 0;
897 s->status = EXTRA_STATE;
898 }
899 }
900 if (s->status == EXTRA_STATE) {
901 if (s->gzhead->extra != Z_NULL) {
902 ulg beg = s->pending; /* start of bytes to update crc */
903 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex;
904 while (s->pending + left > s->pending_buf_size) {
905 uInt copy = s->pending_buf_size - s->pending;
906 zmemcpy(s->pending_buf + s->pending,
907 s->gzhead->extra + s->gzindex, copy);
908 s->pending = s->pending_buf_size;
909 HCRC_UPDATE(beg);
910 s->gzindex += copy;
911 flush_pending(strm);
912 if (s->pending != 0) {
913 s->last_flush = -1;
914 return Z_OK;
915 }
916 beg = 0;
917 left -= copy;
918 }
919 zmemcpy(s->pending_buf + s->pending,
920 s->gzhead->extra + s->gzindex, left);
921 s->pending += left;
922 HCRC_UPDATE(beg);
923 s->gzindex = 0;
924 }
925 s->status = NAME_STATE;
926 }
927 if (s->status == NAME_STATE) {
928 if (s->gzhead->name != Z_NULL) {
929 ulg beg = s->pending; /* start of bytes to update crc */
930 int val;
931 do {
932 if (s->pending == s->pending_buf_size) {
933 HCRC_UPDATE(beg);
934 flush_pending(strm);
935 if (s->pending != 0) {
936 s->last_flush = -1;
937 return Z_OK;
938 }
939 beg = 0;
940 }
941 val = s->gzhead->name[s->gzindex++];
942 put_byte(s, val);
943 } while (val != 0);
944 HCRC_UPDATE(beg);
945 s->gzindex = 0;
946 }
947 s->status = COMMENT_STATE;
948 }
949 if (s->status == COMMENT_STATE) {
950 if (s->gzhead->comment != Z_NULL) {
951 ulg beg = s->pending; /* start of bytes to update crc */
952 int val;
953 do {
954 if (s->pending == s->pending_buf_size) {
955 HCRC_UPDATE(beg);
956 flush_pending(strm);
957 if (s->pending != 0) {
958 s->last_flush = -1;
959 return Z_OK;
960 }
961 beg = 0;
962 }
963 val = s->gzhead->comment[s->gzindex++];
964 put_byte(s, val);
965 } while (val != 0);
966 HCRC_UPDATE(beg);
967 }
968 s->status = HCRC_STATE;
969 }
970 if (s->status == HCRC_STATE) {
971 if (s->gzhead->hcrc) {
972 if (s->pending + 2 > s->pending_buf_size) {
973 flush_pending(strm);
974 if (s->pending != 0) {
975 s->last_flush = -1;
976 return Z_OK;
977 }
978 }
979 put_byte(s, (Byte)(strm->adler & 0xff));
980 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
981 strm->adler = crc32(0L, Z_NULL, 0);
982 }
983 s->status = BUSY_STATE;
984
985 /* Compression must start with an empty pending buffer */
986 flush_pending(strm);
987 if (s->pending != 0) {
988 s->last_flush = -1;
989 return Z_OK;
990 }
991 }
992#endif
993
994 /* Start a new block or continue the current one.
995 */
996 if (strm->avail_in != 0 || s->lookahead != 0 ||
997 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
998 block_state bstate;
999
1000 bstate = s->level == 0 ? deflate_stored(s, flush) :
1001 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
1002 s->strategy == Z_RLE ? deflate_rle(s, flush) :
1003 (*(configuration_table[s->level].func))(s, flush);
1004
1005 if (bstate == finish_started || bstate == finish_done) {
1006 s->status = FINISH_STATE;
1007 }
1008 if (bstate == need_more || bstate == finish_started) {
1009 if (strm->avail_out == 0) {
1010 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
1011 }
1012 return Z_OK;
1013 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
1014 * of deflate should use the same flush parameter to make sure
1015 * that the flush is complete. So we don't have to output an
1016 * empty block here, this will be done at next call. This also
1017 * ensures that for a very small output buffer, we emit at most
1018 * one empty block.
1019 */
1020 }
1021 if (bstate == block_done) {
1022 if (flush == Z_PARTIAL_FLUSH) {
1023 _tr_align(s);
1024 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
1025 _tr_stored_block(s, (char*)0, 0L, 0);
1026 /* For a full flush, this empty block will be recognized
1027 * as a special marker by inflate_sync().
1028 */
1029 if (flush == Z_FULL_FLUSH) {
1030 CLEAR_HASH(s); /* forget history */
1031 if (s->lookahead == 0) {
1032 s->strstart = 0;
1033 s->block_start = 0L;
1034 s->insert = 0;
1035 }
1036 }
1037 }
1038 flush_pending(strm);
1039 if (strm->avail_out == 0) {
1040 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
1041 return Z_OK;
1042 }
1043 }
1044 }
1045
1046 if (flush != Z_FINISH) return Z_OK;
1047 if (s->wrap <= 0) return Z_STREAM_END;
1048
1049 /* Write the trailer */
1050#ifdef GZIP
1051 if (s->wrap == 2) {
1052 put_byte(s, (Byte)(strm->adler & 0xff));
1053 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
1054 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
1055 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
1056 put_byte(s, (Byte)(strm->total_in & 0xff));
1057 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
1058 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
1059 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
1060 }
1061 else
1062#endif
1063 {
1064 putShortMSB(s, (uInt)(strm->adler >> 16));
1065 putShortMSB(s, (uInt)(strm->adler & 0xffff));
1066 }
1067 flush_pending(strm);
1068 /* If avail_out is zero, the application will call deflate again
1069 * to flush the rest.
1070 */
1071 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
1072 return s->pending != 0 ? Z_OK : Z_STREAM_END;
1073}
1074
1075/* ========================================================================= */
1076int ZEXPORT deflateEnd (strm)
1077 z_streamp strm;
1078{
1079 int status;
1080
1081 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
1082
1083 status = strm->state->status;
1084
1085 /* Deallocate in reverse order of allocations: */
1086 TRY_FREE(strm, strm->state->pending_buf);
1087 TRY_FREE(strm, strm->state->head);
1088 TRY_FREE(strm, strm->state->prev);
1089 TRY_FREE(strm, strm->state->window);
1090
1091 ZFREE(strm, strm->state);
1092 strm->state = Z_NULL;
1093
1094 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1095}
1096
1097/* =========================================================================
1098 * Copy the source state to the destination state.
1099 * To simplify the source, this is not supported for 16-bit MSDOS (which
1100 * doesn't have enough memory anyway to duplicate compression states).
1101 */
1102int ZEXPORT deflateCopy (dest, source)
1103 z_streamp dest;
1104 z_streamp source;
1105{
1106#ifdef MAXSEG_64K
1107 return Z_STREAM_ERROR;
1108#else
1109 deflate_state *ds;
1110 deflate_state *ss;
1111 ushf *overlay;
1112
1113
1114 if (deflateStateCheck(source) || dest == Z_NULL) {
1115 return Z_STREAM_ERROR;
1116 }
1117
1118 ss = source->state;
1119
1120 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1121
1122 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1123 if (ds == Z_NULL) return Z_MEM_ERROR;
1124 dest->state = (struct internal_state FAR *) ds;
1125 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1126 ds->strm = dest;
1127
1128 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1129 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1130 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1131 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1132 ds->pending_buf = (uchf *) overlay;
1133
1134 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1135 ds->pending_buf == Z_NULL) {
1136 deflateEnd (dest);
1137 return Z_MEM_ERROR;
1138 }
1139 /* following zmemcpy do not work for 16-bit MSDOS */
1140 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1141 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1142 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1143 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1144
1145 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1146 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1147 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1148
1149 ds->l_desc.dyn_tree = ds->dyn_ltree;
1150 ds->d_desc.dyn_tree = ds->dyn_dtree;
1151 ds->bl_desc.dyn_tree = ds->bl_tree;
1152
1153 return Z_OK;
1154#endif /* MAXSEG_64K */
1155}
1156
1157/* ===========================================================================
1158 * Read a new buffer from the current input stream, update the adler32
1159 * and total number of bytes read. All deflate() input goes through
1160 * this function so some applications may wish to modify it to avoid
1161 * allocating a large strm->next_in buffer and copying from it.
1162 * (See also flush_pending()).
1163 */
1164local unsigned read_buf(strm, buf, size)
1165 z_streamp strm;
1166 Bytef *buf;
1167 unsigned size;
1168{
1169 unsigned len = strm->avail_in;
1170
1171 if (len > size) len = size;
1172 if (len == 0) return 0;
1173
1174 strm->avail_in -= len;
1175
1176 zmemcpy(buf, strm->next_in, len);
1177 if (strm->state->wrap == 1) {
1178 strm->adler = adler32(strm->adler, buf, len);
1179 }
1180#ifdef GZIP
1181 else if (strm->state->wrap == 2) {
1182 strm->adler = crc32(strm->adler, buf, len);
1183 }
1184#endif
1185 strm->next_in += len;
1186 strm->total_in += len;
1187
1188 return len;
1189}
1190
1191/* ===========================================================================
1192 * Initialize the "longest match" routines for a new zlib stream
1193 */
1194local void lm_init (s)
1195 deflate_state *s;
1196{
1197 s->window_size = (ulg)2L*s->w_size;
1198
1199 CLEAR_HASH(s);
1200
1201 /* Set the default configuration parameters:
1202 */
1203 s->max_lazy_match = configuration_table[s->level].max_lazy;
1204 s->good_match = configuration_table[s->level].good_length;
1205 s->nice_match = configuration_table[s->level].nice_length;
1206 s->max_chain_length = configuration_table[s->level].max_chain;
1207
1208 s->strstart = 0;
1209 s->block_start = 0L;
1210 s->lookahead = 0;
1211 s->insert = 0;
1212 s->match_length = s->prev_length = MIN_MATCH-1;
1213 s->match_available = 0;
1214 s->ins_h = 0;
1215#ifndef FASTEST
1216#ifdef ASMV
1217 match_init(); /* initialize the asm code */
1218#endif
1219#endif
1220}
1221
1222#ifndef FASTEST
1223/* ===========================================================================
1224 * Set match_start to the longest match starting at the given string and
1225 * return its length. Matches shorter or equal to prev_length are discarded,
1226 * in which case the result is equal to prev_length and match_start is
1227 * garbage.
1228 * IN assertions: cur_match is the head of the hash chain for the current
1229 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1230 * OUT assertion: the match length is not greater than s->lookahead.
1231 */
1232#ifndef ASMV
1233/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1234 * match.S. The code will be functionally equivalent.
1235 */
1236local uInt longest_match(s, cur_match)
1237 deflate_state *s;
1238 IPos cur_match; /* current match */
1239{
1240 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1241 register Bytef *scan = s->window + s->strstart; /* current string */
1242 register Bytef *match; /* matched string */
1243 register int len; /* length of current match */
1244 int best_len = (int)s->prev_length; /* best match length so far */
1245 int nice_match = s->nice_match; /* stop if match long enough */
1246 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1247 s->strstart - (IPos)MAX_DIST(s) : NIL;
1248 /* Stop when cur_match becomes <= limit. To simplify the code,
1249 * we prevent matches with the string of window index 0.
1250 */
1251 Posf *prev = s->prev;
1252 uInt wmask = s->w_mask;
1253
1254#ifdef UNALIGNED_OK
1255 /* Compare two bytes at a time. Note: this is not always beneficial.
1256 * Try with and without -DUNALIGNED_OK to check.
1257 */
1258 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1259 register ush scan_start = *(ushf*)scan;
1260 register ush scan_end = *(ushf*)(scan+best_len-1);
1261#else
1262 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1263 register Byte scan_end1 = scan[best_len-1];
1264 register Byte scan_end = scan[best_len];
1265#endif
1266
1267 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1268 * It is easy to get rid of this optimization if necessary.
1269 */
1270 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1271
1272 /* Do not waste too much time if we already have a good match: */
1273 if (s->prev_length >= s->good_match) {
1274 chain_length >>= 2;
1275 }
1276 /* Do not look for matches beyond the end of the input. This is necessary
1277 * to make deflate deterministic.
1278 */
1279 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead;
1280
1281 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1282
1283 do {
1284 Assert(cur_match < s->strstart, "no future");
1285 match = s->window + cur_match;
1286
1287 /* Skip to next match if the match length cannot increase
1288 * or if the match length is less than 2. Note that the checks below
1289 * for insufficient lookahead only occur occasionally for performance
1290 * reasons. Therefore uninitialized memory will be accessed, and
1291 * conditional jumps will be made that depend on those values.
1292 * However the length of the match is limited to the lookahead, so
1293 * the output of deflate is not affected by the uninitialized values.
1294 */
1295#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1296 /* This code assumes sizeof(unsigned short) == 2. Do not use
1297 * UNALIGNED_OK if your compiler uses a different size.
1298 */
1299 if (*(ushf*)(match+best_len-1) != scan_end ||
1300 *(ushf*)match != scan_start) continue;
1301
1302 /* It is not necessary to compare scan[2] and match[2] since they are
1303 * always equal when the other bytes match, given that the hash keys
1304 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1305 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1306 * lookahead only every 4th comparison; the 128th check will be made
1307 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1308 * necessary to put more guard bytes at the end of the window, or
1309 * to check more often for insufficient lookahead.
1310 */
1311 Assert(scan[2] == match[2], "scan[2]?");
1312 scan++, match++;
1313 do {
1314 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1315 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1316 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1317 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1318 scan < strend);
1319 /* The funny "do {}" generates better code on most compilers */
1320
1321 /* Here, scan <= window+strstart+257 */
1322 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1323 if (*scan == *match) scan++;
1324
1325 len = (MAX_MATCH - 1) - (int)(strend-scan);
1326 scan = strend - (MAX_MATCH-1);
1327
1328#else /* UNALIGNED_OK */
1329
1330 if (match[best_len] != scan_end ||
1331 match[best_len-1] != scan_end1 ||
1332 *match != *scan ||
1333 *++match != scan[1]) continue;
1334
1335 /* The check at best_len-1 can be removed because it will be made
1336 * again later. (This heuristic is not always a win.)
1337 * It is not necessary to compare scan[2] and match[2] since they
1338 * are always equal when the other bytes match, given that
1339 * the hash keys are equal and that HASH_BITS >= 8.
1340 */
1341 scan += 2, match++;
1342 Assert(*scan == *match, "match[2]?");
1343
1344 /* We check for insufficient lookahead only every 8th comparison;
1345 * the 256th check will be made at strstart+258.
1346 */
1347 do {
1348 } while (*++scan == *++match && *++scan == *++match &&
1349 *++scan == *++match && *++scan == *++match &&
1350 *++scan == *++match && *++scan == *++match &&
1351 *++scan == *++match && *++scan == *++match &&
1352 scan < strend);
1353
1354 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1355
1356 len = MAX_MATCH - (int)(strend - scan);
1357 scan = strend - MAX_MATCH;
1358
1359#endif /* UNALIGNED_OK */
1360
1361 if (len > best_len) {
1362 s->match_start = cur_match;
1363 best_len = len;
1364 if (len >= nice_match) break;
1365#ifdef UNALIGNED_OK
1366 scan_end = *(ushf*)(scan+best_len-1);
1367#else
1368 scan_end1 = scan[best_len-1];
1369 scan_end = scan[best_len];
1370#endif
1371 }
1372 } while ((cur_match = prev[cur_match & wmask]) > limit
1373 && --chain_length != 0);
1374
1375 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1376 return s->lookahead;
1377}
1378#endif /* ASMV */
1379
1380#else /* FASTEST */
1381
1382/* ---------------------------------------------------------------------------
1383 * Optimized version for FASTEST only
1384 */
1385local uInt longest_match(s, cur_match)
1386 deflate_state *s;
1387 IPos cur_match; /* current match */
1388{
1389 register Bytef *scan = s->window + s->strstart; /* current string */
1390 register Bytef *match; /* matched string */
1391 register int len; /* length of current match */
1392 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1393
1394 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1395 * It is easy to get rid of this optimization if necessary.
1396 */
1397 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1398
1399 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1400
1401 Assert(cur_match < s->strstart, "no future");
1402
1403 match = s->window + cur_match;
1404
1405 /* Return failure if the match length is less than 2:
1406 */
1407 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1408
1409 /* The check at best_len-1 can be removed because it will be made
1410 * again later. (This heuristic is not always a win.)
1411 * It is not necessary to compare scan[2] and match[2] since they
1412 * are always equal when the other bytes match, given that
1413 * the hash keys are equal and that HASH_BITS >= 8.
1414 */
1415 scan += 2, match += 2;
1416 Assert(*scan == *match, "match[2]?");
1417
1418 /* We check for insufficient lookahead only every 8th comparison;
1419 * the 256th check will be made at strstart+258.
1420 */
1421 do {
1422 } while (*++scan == *++match && *++scan == *++match &&
1423 *++scan == *++match && *++scan == *++match &&
1424 *++scan == *++match && *++scan == *++match &&
1425 *++scan == *++match && *++scan == *++match &&
1426 scan < strend);
1427
1428 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1429
1430 len = MAX_MATCH - (int)(strend - scan);
1431
1432 if (len < MIN_MATCH) return MIN_MATCH - 1;
1433
1434 s->match_start = cur_match;
1435 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1436}
1437
1438#endif /* FASTEST */
1439
1440#ifdef ZLIB_DEBUG
1441
1442#define EQUAL 0
1443/* result of memcmp for equal strings */
1444
1445/* ===========================================================================
1446 * Check that the match at match_start is indeed a match.
1447 */
1448local void check_match(s, start, match, length)
1449 deflate_state *s;
1450 IPos start, match;
1451 int length;
1452{
1453 /* check that the match is indeed a match */
1454 if (zmemcmp(s->window + match,
1455 s->window + start, length) != EQUAL) {
1456 fprintf(stderr, " start %u, match %u, length %d\n",
1457 start, match, length);
1458 do {
1459 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1460 } while (--length != 0);
1461 z_error("invalid match");
1462 }
1463 if (z_verbose > 1) {
1464 fprintf(stderr,"\\[%d,%d]", start-match, length);
1465 do { putc(s->window[start++], stderr); } while (--length != 0);
1466 }
1467}
1468#else
1469# define check_match(s, start, match, length)
1470#endif /* ZLIB_DEBUG */
1471
1472/* ===========================================================================
1473 * Fill the window when the lookahead becomes insufficient.
1474 * Updates strstart and lookahead.
1475 *
1476 * IN assertion: lookahead < MIN_LOOKAHEAD
1477 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1478 * At least one byte has been read, or avail_in == 0; reads are
1479 * performed for at least two bytes (required for the zip translate_eol
1480 * option -- not supported here).
1481 */
1482local void fill_window(s)
1483 deflate_state *s;
1484{
1485 unsigned n;
1486 unsigned more; /* Amount of free space at the end of the window. */
1487 uInt wsize = s->w_size;
1488
1489 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1490
1491 do {
1492 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1493
1494 /* Deal with !@#$% 64K limit: */
1495 if (sizeof(int) <= 2) {
1496 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1497 more = wsize;
1498
1499 } else if (more == (unsigned)(-1)) {
1500 /* Very unlikely, but possible on 16 bit machine if
1501 * strstart == 0 && lookahead == 1 (input done a byte at time)
1502 */
1503 more--;
1504 }
1505 }
1506
1507 /* If the window is almost full and there is insufficient lookahead,
1508 * move the upper half to the lower one to make room in the upper half.
1509 */
1510 if (s->strstart >= wsize+MAX_DIST(s)) {
1511
1512 zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more);
1513 s->match_start -= wsize;
1514 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1515 s->block_start -= (long) wsize;
1516 slide_hash(s);
1517 more += wsize;
1518 }
1519 if (s->strm->avail_in == 0) break;
1520
1521 /* If there was no sliding:
1522 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1523 * more == window_size - lookahead - strstart
1524 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1525 * => more >= window_size - 2*WSIZE + 2
1526 * In the BIG_MEM or MMAP case (not yet supported),
1527 * window_size == input_size + MIN_LOOKAHEAD &&
1528 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1529 * Otherwise, window_size == 2*WSIZE so more >= 2.
1530 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1531 */
1532 Assert(more >= 2, "more < 2");
1533
1534 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1535 s->lookahead += n;
1536
1537 /* Initialize the hash value now that we have some input: */
1538 if (s->lookahead + s->insert >= MIN_MATCH) {
1539 uInt str = s->strstart - s->insert;
1540 s->ins_h = s->window[str];
1541 UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1542#if MIN_MATCH != 3
1543 Call UPDATE_HASH() MIN_MATCH-3 more times
1544#endif
1545 while (s->insert) {
1546 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1547#ifndef FASTEST
1548 s->prev[str & s->w_mask] = s->head[s->ins_h];
1549#endif
1550 s->head[s->ins_h] = (Pos)str;
1551 str++;
1552 s->insert--;
1553 if (s->lookahead + s->insert < MIN_MATCH)
1554 break;
1555 }
1556 }
1557 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1558 * but this is not important since only literal bytes will be emitted.
1559 */
1560
1561 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1562
1563 /* If the WIN_INIT bytes after the end of the current data have never been
1564 * written, then zero those bytes in order to avoid memory check reports of
1565 * the use of uninitialized (or uninitialised as Julian writes) bytes by
1566 * the longest match routines. Update the high water mark for the next
1567 * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1568 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1569 */
1570 if (s->high_water < s->window_size) {
1571 ulg curr = s->strstart + (ulg)(s->lookahead);
1572 ulg init;
1573
1574 if (s->high_water < curr) {
1575 /* Previous high water mark below current data -- zero WIN_INIT
1576 * bytes or up to end of window, whichever is less.
1577 */
1578 init = s->window_size - curr;
1579 if (init > WIN_INIT)
1580 init = WIN_INIT;
1581 zmemzero(s->window + curr, (unsigned)init);
1582 s->high_water = curr + init;
1583 }
1584 else if (s->high_water < (ulg)curr + WIN_INIT) {
1585 /* High water mark at or above current data, but below current data
1586 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1587 * to end of window, whichever is less.
1588 */
1589 init = (ulg)curr + WIN_INIT - s->high_water;
1590 if (init > s->window_size - s->high_water)
1591 init = s->window_size - s->high_water;
1592 zmemzero(s->window + s->high_water, (unsigned)init);
1593 s->high_water += init;
1594 }
1595 }
1596
1597 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1598 "not enough room for search");
1599}
1600
1601/* ===========================================================================
1602 * Flush the current block, with given end-of-file flag.
1603 * IN assertion: strstart is set to the end of the current match.
1604 */
1605#define FLUSH_BLOCK_ONLY(s, last) { \
1606 _tr_flush_block(s, (s->block_start >= 0L ? \
1607 (charf *)&s->window[(unsigned)s->block_start] : \
1608 (charf *)Z_NULL), \
1609 (ulg)((long)s->strstart - s->block_start), \
1610 (last)); \
1611 s->block_start = s->strstart; \
1612 flush_pending(s->strm); \
1613 Tracev((stderr,"[FLUSH]")); \
1614}
1615
1616/* Same but force premature exit if necessary. */
1617#define FLUSH_BLOCK(s, last) { \
1618 FLUSH_BLOCK_ONLY(s, last); \
1619 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1620}
1621
1622/* Maximum stored block length in deflate format (not including header). */
1623#define MAX_STORED 65535
1624
1625/* Minimum of a and b. */
1626#define MIN(a, b) ((a) > (b) ? (b) : (a))
1627
1628/* ===========================================================================
1629 * Copy without compression as much as possible from the input stream, return
1630 * the current block state.
1631 *
1632 * In case deflateParams() is used to later switch to a non-zero compression
1633 * level, s->matches (otherwise unused when storing) keeps track of the number
1634 * of hash table slides to perform. If s->matches is 1, then one hash table
1635 * slide will be done when switching. If s->matches is 2, the maximum value
1636 * allowed here, then the hash table will be cleared, since two or more slides
1637 * is the same as a clear.
1638 *
1639 * deflate_stored() is written to minimize the number of times an input byte is
1640 * copied. It is most efficient with large input and output buffers, which
1641 * maximizes the opportunites to have a single copy from next_in to next_out.
1642 */
1643local block_state deflate_stored(s, flush)
1644 deflate_state *s;
1645 int flush;
1646{
1647 /* Smallest worthy block size when not flushing or finishing. By default
1648 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For
1649 * large input and output buffers, the stored block size will be larger.
1650 */
1651 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size);
1652
1653 /* Copy as many min_block or larger stored blocks directly to next_out as
1654 * possible. If flushing, copy the remaining available input to next_out as
1655 * stored blocks, if there is enough space.
1656 */
1657 unsigned len, left, have, last = 0;
1658 unsigned used = s->strm->avail_in;
1659 do {
1660 /* Set len to the maximum size block that we can copy directly with the
1661 * available input data and output space. Set left to how much of that
1662 * would be copied from what's left in the window.
1663 */
1664 len = MAX_STORED; /* maximum deflate stored block length */
1665 have = (s->bi_valid + 42) >> 3; /* number of header bytes */
1666 if (s->strm->avail_out < have) /* need room for header */
1667 break;
1668 /* maximum stored block length that will fit in avail_out: */
1669 have = s->strm->avail_out - have;
1670 left = s->strstart - s->block_start; /* bytes left in window */
1671 if (len > (ulg)left + s->strm->avail_in)
1672 len = left + s->strm->avail_in; /* limit len to the input */
1673 if (len > have)
1674 len = have; /* limit len to the output */
1675
1676 /* If the stored block would be less than min_block in length, or if
1677 * unable to copy all of the available input when flushing, then try
1678 * copying to the window and the pending buffer instead. Also don't
1679 * write an empty block when flushing -- deflate() does that.
1680 */
1681 if (len < min_block && ((len == 0 && flush != Z_FINISH) ||
1682 flush == Z_NO_FLUSH ||
1683 len != left + s->strm->avail_in))
1684 break;
1685
1686 /* Make a dummy stored block in pending to get the header bytes,
1687 * including any pending bits. This also updates the debugging counts.
1688 */
1689 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0;
1690 _tr_stored_block(s, (char *)0, 0L, last);
1691
1692 /* Replace the lengths in the dummy stored block with len. */
1693 s->pending_buf[s->pending - 4] = len;
1694 s->pending_buf[s->pending - 3] = len >> 8;
1695 s->pending_buf[s->pending - 2] = ~len;
1696 s->pending_buf[s->pending - 1] = ~len >> 8;
1697
1698 /* Write the stored block header bytes. */
1699 flush_pending(s->strm);
1700
1701#ifdef ZLIB_DEBUG
1702 /* Update debugging counts for the data about to be copied. */
1703 s->compressed_len += len << 3;
1704 s->bits_sent += len << 3;
1705#endif
1706
1707 /* Copy uncompressed bytes from the window to next_out. */
1708 if (left) {
1709 if (left > len)
1710 left = len;
1711 zmemcpy(s->strm->next_out, s->window + s->block_start, left);
1712 s->strm->next_out += left;
1713 s->strm->avail_out -= left;
1714 s->strm->total_out += left;
1715 s->block_start += left;
1716 len -= left;
1717 }
1718
1719 /* Copy uncompressed bytes directly from next_in to next_out, updating
1720 * the check value.
1721 */
1722 if (len) {
1723 read_buf(s->strm, s->strm->next_out, len);
1724 s->strm->next_out += len;
1725 s->strm->avail_out -= len;
1726 s->strm->total_out += len;
1727 }
1728 } while (last == 0);
1729
1730 /* Update the sliding window with the last s->w_size bytes of the copied
1731 * data, or append all of the copied data to the existing window if less
1732 * than s->w_size bytes were copied. Also update the number of bytes to
1733 * insert in the hash tables, in the event that deflateParams() switches to
1734 * a non-zero compression level.
1735 */
1736 used -= s->strm->avail_in; /* number of input bytes directly copied */
1737 if (used) {
1738 /* If any input was used, then no unused input remains in the window,
1739 * therefore s->block_start == s->strstart.
1740 */
1741 if (used >= s->w_size) { /* supplant the previous history */
1742 s->matches = 2; /* clear hash */
1743 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);
1744 s->strstart = s->w_size;
1745 }
1746 else {
1747 if (s->window_size - s->strstart <= used) {
1748 /* Slide the window down. */
1749 s->strstart -= s->w_size;
1750 zmemcpy(s->window, s->window + s->w_size, s->strstart);
1751 if (s->matches < 2)
1752 s->matches++; /* add a pending slide_hash() */
1753 }
1754 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used);
1755 s->strstart += used;
1756 }
1757 s->block_start = s->strstart;
1758 s->insert += MIN(used, s->w_size - s->insert);
1759 }
1760 if (s->high_water < s->strstart)
1761 s->high_water = s->strstart;
1762
1763 /* If the last block was written to next_out, then done. */
1764 if (last)
1765 return finish_done;
1766
1767 /* If flushing and all input has been consumed, then done. */
1768 if (flush != Z_NO_FLUSH && flush != Z_FINISH &&
1769 s->strm->avail_in == 0 && (long)s->strstart == s->block_start)
1770 return block_done;
1771
1772 /* Fill the window with any remaining input. */
1773 have = s->window_size - s->strstart - 1;
1774 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) {
1775 /* Slide the window down. */
1776 s->block_start -= s->w_size;
1777 s->strstart -= s->w_size;
1778 zmemcpy(s->window, s->window + s->w_size, s->strstart);
1779 if (s->matches < 2)
1780 s->matches++; /* add a pending slide_hash() */
1781 have += s->w_size; /* more space now */
1782 }
1783 if (have > s->strm->avail_in)
1784 have = s->strm->avail_in;
1785 if (have) {
1786 read_buf(s->strm, s->window + s->strstart, have);
1787 s->strstart += have;
1788 }
1789 if (s->high_water < s->strstart)
1790 s->high_water = s->strstart;
1791
1792 /* There was not enough avail_out to write a complete worthy or flushed
1793 * stored block to next_out. Write a stored block to pending instead, if we
1794 * have enough input for a worthy block, or if flushing and there is enough
1795 * room for the remaining input as a stored block in the pending buffer.
1796 */
1797 have = (s->bi_valid + 42) >> 3; /* number of header bytes */
1798 /* maximum stored block length that will fit in pending: */
1799 have = MIN(s->pending_buf_size - have, MAX_STORED);
1800 min_block = MIN(have, s->w_size);
1801 left = s->strstart - s->block_start;
1802 if (left >= min_block ||
1803 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH &&
1804 s->strm->avail_in == 0 && left <= have)) {
1805 len = MIN(left, have);
1806 last = flush == Z_FINISH && s->strm->avail_in == 0 &&
1807 len == left ? 1 : 0;
1808 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last);
1809 s->block_start += len;
1810 flush_pending(s->strm);
1811 }
1812
1813 /* We've done all we can with the available input and output. */
1814 return last ? finish_started : need_more;
1815}
1816
1817/* ===========================================================================
1818 * Compress as much as possible from the input stream, return the current
1819 * block state.
1820 * This function does not perform lazy evaluation of matches and inserts
1821 * new strings in the dictionary only for unmatched strings or for short
1822 * matches. It is used only for the fast compression options.
1823 */
1824local block_state deflate_fast(s, flush)
1825 deflate_state *s;
1826 int flush;
1827{
1828 IPos hash_head; /* head of the hash chain */
1829 int bflush; /* set if current block must be flushed */
1830
1831 for (;;) {
1832 /* Make sure that we always have enough lookahead, except
1833 * at the end of the input file. We need MAX_MATCH bytes
1834 * for the next match, plus MIN_MATCH bytes to insert the
1835 * string following the next match.
1836 */
1837 if (s->lookahead < MIN_LOOKAHEAD) {
1838 fill_window(s);
1839 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1840 return need_more;
1841 }
1842 if (s->lookahead == 0) break; /* flush the current block */
1843 }
1844
1845 /* Insert the string window[strstart .. strstart+2] in the
1846 * dictionary, and set hash_head to the head of the hash chain:
1847 */
1848 hash_head = NIL;
1849 if (s->lookahead >= MIN_MATCH) {
1850 INSERT_STRING(s, s->strstart, hash_head);
1851 }
1852
1853 /* Find the longest match, discarding those <= prev_length.
1854 * At this point we have always match_length < MIN_MATCH
1855 */
1856 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1857 /* To simplify the code, we prevent matches with the string
1858 * of window index 0 (in particular we have to avoid a match
1859 * of the string with itself at the start of the input file).
1860 */
1861 s->match_length = longest_match (s, hash_head);
1862 /* longest_match() sets match_start */
1863 }
1864 if (s->match_length >= MIN_MATCH) {
1865 check_match(s, s->strstart, s->match_start, s->match_length);
1866
1867 _tr_tally_dist(s, s->strstart - s->match_start,
1868 s->match_length - MIN_MATCH, bflush);
1869
1870 s->lookahead -= s->match_length;
1871
1872 /* Insert new strings in the hash table only if the match length
1873 * is not too large. This saves time but degrades compression.
1874 */
1875#ifndef FASTEST
1876 if (s->match_length <= s->max_insert_length &&
1877 s->lookahead >= MIN_MATCH) {
1878 s->match_length--; /* string at strstart already in table */
1879 do {
1880 s->strstart++;
1881 INSERT_STRING(s, s->strstart, hash_head);
1882 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1883 * always MIN_MATCH bytes ahead.
1884 */
1885 } while (--s->match_length != 0);
1886 s->strstart++;
1887 } else
1888#endif
1889 {
1890 s->strstart += s->match_length;
1891 s->match_length = 0;
1892 s->ins_h = s->window[s->strstart];
1893 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1894#if MIN_MATCH != 3
1895 Call UPDATE_HASH() MIN_MATCH-3 more times
1896#endif
1897 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1898 * matter since it will be recomputed at next deflate call.
1899 */
1900 }
1901 } else {
1902 /* No match, output a literal byte */
1903 Tracevv((stderr,"%c", s->window[s->strstart]));
1904 _tr_tally_lit (s, s->window[s->strstart], bflush);
1905 s->lookahead--;
1906 s->strstart++;
1907 }
1908 if (bflush) FLUSH_BLOCK(s, 0);
1909 }
1910 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1911 if (flush == Z_FINISH) {
1912 FLUSH_BLOCK(s, 1);
1913 return finish_done;
1914 }
1915 if (s->last_lit)
1916 FLUSH_BLOCK(s, 0);
1917 return block_done;
1918}
1919
1920#ifndef FASTEST
1921/* ===========================================================================
1922 * Same as above, but achieves better compression. We use a lazy
1923 * evaluation for matches: a match is finally adopted only if there is
1924 * no better match at the next window position.
1925 */
1926local block_state deflate_slow(s, flush)
1927 deflate_state *s;
1928 int flush;
1929{
1930 IPos hash_head; /* head of hash chain */
1931 int bflush; /* set if current block must be flushed */
1932
1933 /* Process the input block. */
1934 for (;;) {
1935 /* Make sure that we always have enough lookahead, except
1936 * at the end of the input file. We need MAX_MATCH bytes
1937 * for the next match, plus MIN_MATCH bytes to insert the
1938 * string following the next match.
1939 */
1940 if (s->lookahead < MIN_LOOKAHEAD) {
1941 fill_window(s);
1942 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1943 return need_more;
1944 }
1945 if (s->lookahead == 0) break; /* flush the current block */
1946 }
1947
1948 /* Insert the string window[strstart .. strstart+2] in the
1949 * dictionary, and set hash_head to the head of the hash chain:
1950 */
1951 hash_head = NIL;
1952 if (s->lookahead >= MIN_MATCH) {
1953 INSERT_STRING(s, s->strstart, hash_head);
1954 }
1955
1956 /* Find the longest match, discarding those <= prev_length.
1957 */
1958 s->prev_length = s->match_length, s->prev_match = s->match_start;
1959 s->match_length = MIN_MATCH-1;
1960
1961 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1962 s->strstart - hash_head <= MAX_DIST(s)) {
1963 /* To simplify the code, we prevent matches with the string
1964 * of window index 0 (in particular we have to avoid a match
1965 * of the string with itself at the start of the input file).
1966 */
1967 s->match_length = longest_match (s, hash_head);
1968 /* longest_match() sets match_start */
1969
1970 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1971#if TOO_FAR <= 32767
1972 || (s->match_length == MIN_MATCH &&
1973 s->strstart - s->match_start > TOO_FAR)
1974#endif
1975 )) {
1976
1977 /* If prev_match is also MIN_MATCH, match_start is garbage
1978 * but we will ignore the current match anyway.
1979 */
1980 s->match_length = MIN_MATCH-1;
1981 }
1982 }
1983 /* If there was a match at the previous step and the current
1984 * match is not better, output the previous match:
1985 */
1986 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1987 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1988 /* Do not insert strings in hash table beyond this. */
1989
1990 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1991
1992 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1993 s->prev_length - MIN_MATCH, bflush);
1994
1995 /* Insert in hash table all strings up to the end of the match.
1996 * strstart-1 and strstart are already inserted. If there is not
1997 * enough lookahead, the last two strings are not inserted in
1998 * the hash table.
1999 */
2000 s->lookahead -= s->prev_length-1;
2001 s->prev_length -= 2;
2002 do {
2003 if (++s->strstart <= max_insert) {
2004 INSERT_STRING(s, s->strstart, hash_head);
2005 }
2006 } while (--s->prev_length != 0);
2007 s->match_available = 0;
2008 s->match_length = MIN_MATCH-1;
2009 s->strstart++;
2010
2011 if (bflush) FLUSH_BLOCK(s, 0);
2012
2013 } else if (s->match_available) {
2014 /* If there was no match at the previous position, output a
2015 * single literal. If there was a match but the current match
2016 * is longer, truncate the previous match to a single literal.
2017 */
2018 Tracevv((stderr,"%c", s->window[s->strstart-1]));
2019 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
2020 if (bflush) {
2021 FLUSH_BLOCK_ONLY(s, 0);
2022 }
2023 s->strstart++;
2024 s->lookahead--;
2025 if (s->strm->avail_out == 0) return need_more;
2026 } else {
2027 /* There is no previous match to compare with, wait for
2028 * the next step to decide.
2029 */
2030 s->match_available = 1;
2031 s->strstart++;
2032 s->lookahead--;
2033 }
2034 }
2035 Assert (flush != Z_NO_FLUSH, "no flush?");
2036 if (s->match_available) {
2037 Tracevv((stderr,"%c", s->window[s->strstart-1]));
2038 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
2039 s->match_available = 0;
2040 }
2041 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
2042 if (flush == Z_FINISH) {
2043 FLUSH_BLOCK(s, 1);
2044 return finish_done;
2045 }
2046 if (s->last_lit)
2047 FLUSH_BLOCK(s, 0);
2048 return block_done;
2049}
2050#endif /* FASTEST */
2051
2052/* ===========================================================================
2053 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
2054 * one. Do not maintain a hash table. (It will be regenerated if this run of
2055 * deflate switches away from Z_RLE.)
2056 */
2057local block_state deflate_rle(s, flush)
2058 deflate_state *s;
2059 int flush;
2060{
2061 int bflush; /* set if current block must be flushed */
2062 uInt prev; /* byte at distance one to match */
2063 Bytef *scan, *strend; /* scan goes up to strend for length of run */
2064
2065 for (;;) {
2066 /* Make sure that we always have enough lookahead, except
2067 * at the end of the input file. We need MAX_MATCH bytes
2068 * for the longest run, plus one for the unrolled loop.
2069 */
2070 if (s->lookahead <= MAX_MATCH) {
2071 fill_window(s);
2072 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
2073 return need_more;
2074 }
2075 if (s->lookahead == 0) break; /* flush the current block */
2076 }
2077
2078 /* See how many times the previous byte repeats */
2079 s->match_length = 0;
2080 if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
2081 scan = s->window + s->strstart - 1;
2082 prev = *scan;
2083 if (prev == *++scan && prev == *++scan && prev == *++scan) {
2084 strend = s->window + s->strstart + MAX_MATCH;
2085 do {
2086 } while (prev == *++scan && prev == *++scan &&
2087 prev == *++scan && prev == *++scan &&
2088 prev == *++scan && prev == *++scan &&
2089 prev == *++scan && prev == *++scan &&
2090 scan < strend);
2091 s->match_length = MAX_MATCH - (uInt)(strend - scan);
2092 if (s->match_length > s->lookahead)
2093 s->match_length = s->lookahead;
2094 }
2095 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
2096 }
2097
2098 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
2099 if (s->match_length >= MIN_MATCH) {
2100 check_match(s, s->strstart, s->strstart - 1, s->match_length);
2101
2102 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
2103
2104 s->lookahead -= s->match_length;
2105 s->strstart += s->match_length;
2106 s->match_length = 0;
2107 } else {
2108 /* No match, output a literal byte */
2109 Tracevv((stderr,"%c", s->window[s->strstart]));
2110 _tr_tally_lit (s, s->window[s->strstart], bflush);
2111 s->lookahead--;
2112 s->strstart++;
2113 }
2114 if (bflush) FLUSH_BLOCK(s, 0);
2115 }
2116 s->insert = 0;
2117 if (flush == Z_FINISH) {
2118 FLUSH_BLOCK(s, 1);
2119 return finish_done;
2120 }
2121 if (s->last_lit)
2122 FLUSH_BLOCK(s, 0);
2123 return block_done;
2124}
2125
2126/* ===========================================================================
2127 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
2128 * (It will be regenerated if this run of deflate switches away from Huffman.)
2129 */
2130local block_state deflate_huff(s, flush)
2131 deflate_state *s;
2132 int flush;
2133{
2134 int bflush; /* set if current block must be flushed */
2135
2136 for (;;) {
2137 /* Make sure that we have a literal to write. */
2138 if (s->lookahead == 0) {
2139 fill_window(s);
2140 if (s->lookahead == 0) {
2141 if (flush == Z_NO_FLUSH)
2142 return need_more;
2143 break; /* flush the current block */
2144 }
2145 }
2146
2147 /* Output a literal byte */
2148 s->match_length = 0;
2149 Tracevv((stderr,"%c", s->window[s->strstart]));
2150 _tr_tally_lit (s, s->window[s->strstart], bflush);
2151 s->lookahead--;
2152 s->strstart++;
2153 if (bflush) FLUSH_BLOCK(s, 0);
2154 }
2155 s->insert = 0;
2156 if (flush == Z_FINISH) {
2157 FLUSH_BLOCK(s, 1);
2158 return finish_done;
2159 }
2160 if (s->last_lit)
2161 FLUSH_BLOCK(s, 0);
2162 return block_done;
2163}
2164