1/* deflate.c -- compress data using the deflation algorithm
2 * Copyright (C) 1995-2022 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 1.2.12 Copyright 1995-2022 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 do { \
194 s->head[s->hash_size-1] = NIL; \
195 zmemzero((Bytef *)s->head, \
196 (unsigned)(s->hash_size-1)*sizeof(*s->head)); \
197 } while (0)
198
199/* ===========================================================================
200 * Slide the hash table when sliding the window down (could be avoided with 32
201 * bit values at the expense of memory usage). We slide even when level == 0 to
202 * keep the hash table consistent if we switch back to level > 0 later.
203 */
204local void slide_hash(s)
205 deflate_state *s;
206{
207 unsigned n, m;
208 Posf *p;
209 uInt wsize = s->w_size;
210
211 n = s->hash_size;
212 p = &s->head[n];
213 do {
214 m = *--p;
215 *p = (Pos)(m >= wsize ? m - wsize : NIL);
216 } while (--n);
217 n = wsize;
218#ifndef FASTEST
219 p = &s->prev[n];
220 do {
221 m = *--p;
222 *p = (Pos)(m >= wsize ? m - wsize : NIL);
223 /* If n is not on any hash chain, prev[n] is garbage but
224 * its value will never be used.
225 */
226 } while (--n);
227#endif
228}
229
230/* ========================================================================= */
231int ZEXPORT deflateInit_(strm, level, version, stream_size)
232 z_streamp strm;
233 int level;
234 const char *version;
235 int stream_size;
236{
237 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
238 Z_DEFAULT_STRATEGY, version, stream_size);
239 /* To do: ignore strm->next_in if we use it as window */
240}
241
242/* ========================================================================= */
243int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
244 version, stream_size)
245 z_streamp strm;
246 int level;
247 int method;
248 int windowBits;
249 int memLevel;
250 int strategy;
251 const char *version;
252 int stream_size;
253{
254 deflate_state *s;
255 int wrap = 1;
256 static const char my_version[] = ZLIB_VERSION;
257
258 if (version == Z_NULL || version[0] != my_version[0] ||
259 stream_size != sizeof(z_stream)) {
260 return Z_VERSION_ERROR;
261 }
262 if (strm == Z_NULL) return Z_STREAM_ERROR;
263
264 strm->msg = Z_NULL;
265 if (strm->zalloc == (alloc_func)0) {
266#ifdef Z_SOLO
267 return Z_STREAM_ERROR;
268#else
269 strm->zalloc = zcalloc;
270 strm->opaque = (voidpf)0;
271#endif
272 }
273 if (strm->zfree == (free_func)0)
274#ifdef Z_SOLO
275 return Z_STREAM_ERROR;
276#else
277 strm->zfree = zcfree;
278#endif
279
280#ifdef FASTEST
281 if (level != 0) level = 1;
282#else
283 if (level == Z_DEFAULT_COMPRESSION) level = 6;
284#endif
285
286 if (windowBits < 0) { /* suppress zlib wrapper */
287 wrap = 0;
288 windowBits = -windowBits;
289 }
290#ifdef GZIP
291 else if (windowBits > 15) {
292 wrap = 2; /* write gzip wrapper instead */
293 windowBits -= 16;
294 }
295#endif
296 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
297 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
298 strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) {
299 return Z_STREAM_ERROR;
300 }
301 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
302 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
303 if (s == Z_NULL) return Z_MEM_ERROR;
304 strm->state = (struct internal_state FAR *)s;
305 s->strm = strm;
306 s->status = INIT_STATE; /* to pass state test in deflateReset() */
307
308 s->wrap = wrap;
309 s->gzhead = Z_NULL;
310 s->w_bits = (uInt)windowBits;
311 s->w_size = 1 << s->w_bits;
312 s->w_mask = s->w_size - 1;
313
314 s->hash_bits = (uInt)memLevel + 7;
315 s->hash_size = 1 << s->hash_bits;
316 s->hash_mask = s->hash_size - 1;
317 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
318
319 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
320 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
321 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
322
323 s->high_water = 0; /* nothing written to s->window yet */
324
325 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
326
327 /* We overlay pending_buf and sym_buf. This works since the average size
328 * for length/distance pairs over any compressed block is assured to be 31
329 * bits or less.
330 *
331 * Analysis: The longest fixed codes are a length code of 8 bits plus 5
332 * extra bits, for lengths 131 to 257. The longest fixed distance codes are
333 * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest
334 * possible fixed-codes length/distance pair is then 31 bits total.
335 *
336 * sym_buf starts one-fourth of the way into pending_buf. So there are
337 * three bytes in sym_buf for every four bytes in pending_buf. Each symbol
338 * in sym_buf is three bytes -- two for the distance and one for the
339 * literal/length. As each symbol is consumed, the pointer to the next
340 * sym_buf value to read moves forward three bytes. From that symbol, up to
341 * 31 bits are written to pending_buf. The closest the written pending_buf
342 * bits gets to the next sym_buf symbol to read is just before the last
343 * code is written. At that time, 31*(n-2) bits have been written, just
344 * after 24*(n-2) bits have been consumed from sym_buf. sym_buf starts at
345 * 8*n bits into pending_buf. (Note that the symbol buffer fills when n-1
346 * symbols are written.) The closest the writing gets to what is unread is
347 * then n+14 bits. Here n is lit_bufsize, which is 16384 by default, and
348 * can range from 128 to 32768.
349 *
350 * Therefore, at a minimum, there are 142 bits of space between what is
351 * written and what is read in the overlain buffers, so the symbols cannot
352 * be overwritten by the compressed data. That space is actually 139 bits,
353 * due to the three-bit fixed-code block header.
354 *
355 * That covers the case where either Z_FIXED is specified, forcing fixed
356 * codes, or when the use of fixed codes is chosen, because that choice
357 * results in a smaller compressed block than dynamic codes. That latter
358 * condition then assures that the above analysis also covers all dynamic
359 * blocks. A dynamic-code block will only be chosen to be emitted if it has
360 * fewer bits than a fixed-code block would for the same set of symbols.
361 * Therefore its average symbol length is assured to be less than 31. So
362 * the compressed data for a dynamic block also cannot overwrite the
363 * symbols from which it is being constructed.
364 */
365
366 s->pending_buf = (uchf *) ZALLOC(strm, s->lit_bufsize, 4);
367 s->pending_buf_size = (ulg)s->lit_bufsize * 4;
368
369 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
370 s->pending_buf == Z_NULL) {
371 s->status = FINISH_STATE;
372 strm->msg = ERR_MSG(Z_MEM_ERROR);
373 deflateEnd (strm);
374 return Z_MEM_ERROR;
375 }
376 s->sym_buf = s->pending_buf + s->lit_bufsize;
377 s->sym_end = (s->lit_bufsize - 1) * 3;
378 /* We avoid equality with lit_bufsize*3 because of wraparound at 64K
379 * on 16 bit machines and because stored blocks are restricted to
380 * 64K-1 bytes.
381 */
382
383 s->level = level;
384 s->strategy = strategy;
385 s->method = (Byte)method;
386
387 return deflateReset(strm);
388}
389
390/* =========================================================================
391 * Check for a valid deflate stream state. Return 0 if ok, 1 if not.
392 */
393local int deflateStateCheck (strm)
394 z_streamp strm;
395{
396 deflate_state *s;
397 if (strm == Z_NULL ||
398 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0)
399 return 1;
400 s = strm->state;
401 if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE &&
402#ifdef GZIP
403 s->status != GZIP_STATE &&
404#endif
405 s->status != EXTRA_STATE &&
406 s->status != NAME_STATE &&
407 s->status != COMMENT_STATE &&
408 s->status != HCRC_STATE &&
409 s->status != BUSY_STATE &&
410 s->status != FINISH_STATE))
411 return 1;
412 return 0;
413}
414
415/* ========================================================================= */
416int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
417 z_streamp strm;
418 const Bytef *dictionary;
419 uInt dictLength;
420{
421 deflate_state *s;
422 uInt str, n;
423 int wrap;
424 unsigned avail;
425 z_const unsigned char *next;
426
427 if (deflateStateCheck(strm) || dictionary == Z_NULL)
428 return Z_STREAM_ERROR;
429 s = strm->state;
430 wrap = s->wrap;
431 if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
432 return Z_STREAM_ERROR;
433
434 /* when using zlib wrappers, compute Adler-32 for provided dictionary */
435 if (wrap == 1)
436 strm->adler = adler32(strm->adler, dictionary, dictLength);
437 s->wrap = 0; /* avoid computing Adler-32 in read_buf */
438
439 /* if dictionary would fill window, just replace the history */
440 if (dictLength >= s->w_size) {
441 if (wrap == 0) { /* already empty otherwise */
442 CLEAR_HASH(s);
443 s->strstart = 0;
444 s->block_start = 0L;
445 s->insert = 0;
446 }
447 dictionary += dictLength - s->w_size; /* use the tail */
448 dictLength = s->w_size;
449 }
450
451 /* insert dictionary into window and hash */
452 avail = strm->avail_in;
453 next = strm->next_in;
454 strm->avail_in = dictLength;
455 strm->next_in = (z_const Bytef *)dictionary;
456 fill_window(s);
457 while (s->lookahead >= MIN_MATCH) {
458 str = s->strstart;
459 n = s->lookahead - (MIN_MATCH-1);
460 do {
461 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
462#ifndef FASTEST
463 s->prev[str & s->w_mask] = s->head[s->ins_h];
464#endif
465 s->head[s->ins_h] = (Pos)str;
466 str++;
467 } while (--n);
468 s->strstart = str;
469 s->lookahead = MIN_MATCH-1;
470 fill_window(s);
471 }
472 s->strstart += s->lookahead;
473 s->block_start = (long)s->strstart;
474 s->insert = s->lookahead;
475 s->lookahead = 0;
476 s->match_length = s->prev_length = MIN_MATCH-1;
477 s->match_available = 0;
478 strm->next_in = next;
479 strm->avail_in = avail;
480 s->wrap = wrap;
481 return Z_OK;
482}
483
484/* ========================================================================= */
485int ZEXPORT deflateGetDictionary (strm, dictionary, dictLength)
486 z_streamp strm;
487 Bytef *dictionary;
488 uInt *dictLength;
489{
490 deflate_state *s;
491 uInt len;
492
493 if (deflateStateCheck(strm))
494 return Z_STREAM_ERROR;
495 s = strm->state;
496 len = s->strstart + s->lookahead;
497 if (len > s->w_size)
498 len = s->w_size;
499 if (dictionary != Z_NULL && len)
500 zmemcpy(dictionary, s->window + s->strstart + s->lookahead - len, len);
501 if (dictLength != Z_NULL)
502 *dictLength = len;
503 return Z_OK;
504}
505
506/* ========================================================================= */
507int ZEXPORT deflateResetKeep (strm)
508 z_streamp strm;
509{
510 deflate_state *s;
511
512 if (deflateStateCheck(strm)) {
513 return Z_STREAM_ERROR;
514 }
515
516 strm->total_in = strm->total_out = 0;
517 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
518 strm->data_type = Z_UNKNOWN;
519
520 s = (deflate_state *)strm->state;
521 s->pending = 0;
522 s->pending_out = s->pending_buf;
523
524 if (s->wrap < 0) {
525 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
526 }
527 s->status =
528#ifdef GZIP
529 s->wrap == 2 ? GZIP_STATE :
530#endif
531 INIT_STATE;
532 strm->adler =
533#ifdef GZIP
534 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
535#endif
536 adler32(0L, Z_NULL, 0);
537 s->last_flush = -2;
538
539 _tr_init(s);
540
541 return Z_OK;
542}
543
544/* ========================================================================= */
545int ZEXPORT deflateReset (strm)
546 z_streamp strm;
547{
548 int ret;
549
550 ret = deflateResetKeep(strm);
551 if (ret == Z_OK)
552 lm_init(strm->state);
553 return ret;
554}
555
556/* ========================================================================= */
557int ZEXPORT deflateSetHeader (strm, head)
558 z_streamp strm;
559 gz_headerp head;
560{
561 if (deflateStateCheck(strm) || strm->state->wrap != 2)
562 return Z_STREAM_ERROR;
563 strm->state->gzhead = head;
564 return Z_OK;
565}
566
567/* ========================================================================= */
568int ZEXPORT deflatePending (strm, pending, bits)
569 unsigned *pending;
570 int *bits;
571 z_streamp strm;
572{
573 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
574 if (pending != Z_NULL)
575 *pending = strm->state->pending;
576 if (bits != Z_NULL)
577 *bits = strm->state->bi_valid;
578 return Z_OK;
579}
580
581/* ========================================================================= */
582int ZEXPORT deflatePrime (strm, bits, value)
583 z_streamp strm;
584 int bits;
585 int value;
586{
587 deflate_state *s;
588 int put;
589
590 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
591 s = strm->state;
592 if (bits < 0 || bits > 16 ||
593 s->sym_buf < s->pending_out + ((Buf_size + 7) >> 3))
594 return Z_BUF_ERROR;
595 do {
596 put = Buf_size - s->bi_valid;
597 if (put > bits)
598 put = bits;
599 s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
600 s->bi_valid += put;
601 _tr_flush_bits(s);
602 value >>= put;
603 bits -= put;
604 } while (bits);
605 return Z_OK;
606}
607
608/* ========================================================================= */
609int ZEXPORT deflateParams(strm, level, strategy)
610 z_streamp strm;
611 int level;
612 int strategy;
613{
614 deflate_state *s;
615 compress_func func;
616
617 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
618 s = strm->state;
619
620#ifdef FASTEST
621 if (level != 0) level = 1;
622#else
623 if (level == Z_DEFAULT_COMPRESSION) level = 6;
624#endif
625 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
626 return Z_STREAM_ERROR;
627 }
628 func = configuration_table[s->level].func;
629
630 if ((strategy != s->strategy || func != configuration_table[level].func) &&
631 s->last_flush != -2) {
632 /* Flush the last buffer: */
633 int err = deflate(strm, Z_BLOCK);
634 if (err == Z_STREAM_ERROR)
635 return err;
636 if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead)
637 return Z_BUF_ERROR;
638 }
639 if (s->level != level) {
640 if (s->level == 0 && s->matches != 0) {
641 if (s->matches == 1)
642 slide_hash(s);
643 else
644 CLEAR_HASH(s);
645 s->matches = 0;
646 }
647 s->level = level;
648 s->max_lazy_match = configuration_table[level].max_lazy;
649 s->good_match = configuration_table[level].good_length;
650 s->nice_match = configuration_table[level].nice_length;
651 s->max_chain_length = configuration_table[level].max_chain;
652 }
653 s->strategy = strategy;
654 return Z_OK;
655}
656
657/* ========================================================================= */
658int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
659 z_streamp strm;
660 int good_length;
661 int max_lazy;
662 int nice_length;
663 int max_chain;
664{
665 deflate_state *s;
666
667 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
668 s = strm->state;
669 s->good_match = (uInt)good_length;
670 s->max_lazy_match = (uInt)max_lazy;
671 s->nice_match = nice_length;
672 s->max_chain_length = (uInt)max_chain;
673 return Z_OK;
674}
675
676/* =========================================================================
677 * For the default windowBits of 15 and memLevel of 8, this function returns
678 * a close to exact, as well as small, upper bound on the compressed size.
679 * They are coded as constants here for a reason--if the #define's are
680 * changed, then this function needs to be changed as well. The return
681 * value for 15 and 8 only works for those exact settings.
682 *
683 * For any setting other than those defaults for windowBits and memLevel,
684 * the value returned is a conservative worst case for the maximum expansion
685 * resulting from using fixed blocks instead of stored blocks, which deflate
686 * can emit on compressed data for some combinations of the parameters.
687 *
688 * This function could be more sophisticated to provide closer upper bounds for
689 * every combination of windowBits and memLevel. But even the conservative
690 * upper bound of about 14% expansion does not seem onerous for output buffer
691 * allocation.
692 */
693uLong ZEXPORT deflateBound(strm, sourceLen)
694 z_streamp strm;
695 uLong sourceLen;
696{
697 deflate_state *s;
698 uLong complen, wraplen;
699
700 /* conservative upper bound for compressed data */
701 complen = sourceLen +
702 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
703
704 /* if can't get parameters, return conservative bound plus zlib wrapper */
705 if (deflateStateCheck(strm))
706 return complen + 6;
707
708 /* compute wrapper length */
709 s = strm->state;
710 switch (s->wrap) {
711 case 0: /* raw deflate */
712 wraplen = 0;
713 break;
714 case 1: /* zlib wrapper */
715 wraplen = 6 + (s->strstart ? 4 : 0);
716 break;
717#ifdef GZIP
718 case 2: /* gzip wrapper */
719 wraplen = 18;
720 if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
721 Bytef *str;
722 if (s->gzhead->extra != Z_NULL)
723 wraplen += 2 + s->gzhead->extra_len;
724 str = s->gzhead->name;
725 if (str != Z_NULL)
726 do {
727 wraplen++;
728 } while (*str++);
729 str = s->gzhead->comment;
730 if (str != Z_NULL)
731 do {
732 wraplen++;
733 } while (*str++);
734 if (s->gzhead->hcrc)
735 wraplen += 2;
736 }
737 break;
738#endif
739 default: /* for compiler happiness */
740 wraplen = 6;
741 }
742
743 /* if not default parameters, return conservative bound */
744 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
745 return complen + wraplen;
746
747 /* default settings: return tight bound for that case */
748 return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
749 (sourceLen >> 25) + 13 - 6 + wraplen;
750}
751
752/* =========================================================================
753 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
754 * IN assertion: the stream state is correct and there is enough room in
755 * pending_buf.
756 */
757local void putShortMSB (s, b)
758 deflate_state *s;
759 uInt b;
760{
761 put_byte(s, (Byte)(b >> 8));
762 put_byte(s, (Byte)(b & 0xff));
763}
764
765/* =========================================================================
766 * Flush as much pending output as possible. All deflate() output, except for
767 * some deflate_stored() output, goes through this function so some
768 * applications may wish to modify it to avoid allocating a large
769 * strm->next_out buffer and copying into it. (See also read_buf()).
770 */
771local void flush_pending(strm)
772 z_streamp strm;
773{
774 unsigned len;
775 deflate_state *s = strm->state;
776
777 _tr_flush_bits(s);
778 len = s->pending;
779 if (len > strm->avail_out) len = strm->avail_out;
780 if (len == 0) return;
781
782 zmemcpy(strm->next_out, s->pending_out, len);
783 strm->next_out += len;
784 s->pending_out += len;
785 strm->total_out += len;
786 strm->avail_out -= len;
787 s->pending -= len;
788 if (s->pending == 0) {
789 s->pending_out = s->pending_buf;
790 }
791}
792
793/* ===========================================================================
794 * Update the header CRC with the bytes s->pending_buf[beg..s->pending - 1].
795 */
796#define HCRC_UPDATE(beg) \
797 do { \
798 if (s->gzhead->hcrc && s->pending > (beg)) \
799 strm->adler = crc32(strm->adler, s->pending_buf + (beg), \
800 s->pending - (beg)); \
801 } while (0)
802
803/* ========================================================================= */
804int ZEXPORT deflate (strm, flush)
805 z_streamp strm;
806 int flush;
807{
808 int old_flush; /* value of flush param for previous deflate call */
809 deflate_state *s;
810
811 if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) {
812 return Z_STREAM_ERROR;
813 }
814 s = strm->state;
815
816 if (strm->next_out == Z_NULL ||
817 (strm->avail_in != 0 && strm->next_in == Z_NULL) ||
818 (s->status == FINISH_STATE && flush != Z_FINISH)) {
819 ERR_RETURN(strm, Z_STREAM_ERROR);
820 }
821 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
822
823 old_flush = s->last_flush;
824 s->last_flush = flush;
825
826 /* Flush as much pending output as possible */
827 if (s->pending != 0) {
828 flush_pending(strm);
829 if (strm->avail_out == 0) {
830 /* Since avail_out is 0, deflate will be called again with
831 * more output space, but possibly with both pending and
832 * avail_in equal to zero. There won't be anything to do,
833 * but this is not an error situation so make sure we
834 * return OK instead of BUF_ERROR at next call of deflate:
835 */
836 s->last_flush = -1;
837 return Z_OK;
838 }
839
840 /* Make sure there is something to do and avoid duplicate consecutive
841 * flushes. For repeated and useless calls with Z_FINISH, we keep
842 * returning Z_STREAM_END instead of Z_BUF_ERROR.
843 */
844 } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
845 flush != Z_FINISH) {
846 ERR_RETURN(strm, Z_BUF_ERROR);
847 }
848
849 /* User must not provide more input after the first FINISH: */
850 if (s->status == FINISH_STATE && strm->avail_in != 0) {
851 ERR_RETURN(strm, Z_BUF_ERROR);
852 }
853
854 /* Write the header */
855 if (s->status == INIT_STATE && s->wrap == 0)
856 s->status = BUSY_STATE;
857 if (s->status == INIT_STATE) {
858 /* zlib header */
859 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
860 uInt level_flags;
861
862 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
863 level_flags = 0;
864 else if (s->level < 6)
865 level_flags = 1;
866 else if (s->level == 6)
867 level_flags = 2;
868 else
869 level_flags = 3;
870 header |= (level_flags << 6);
871 if (s->strstart != 0) header |= PRESET_DICT;
872 header += 31 - (header % 31);
873
874 putShortMSB(s, header);
875
876 /* Save the adler32 of the preset dictionary: */
877 if (s->strstart != 0) {
878 putShortMSB(s, (uInt)(strm->adler >> 16));
879 putShortMSB(s, (uInt)(strm->adler & 0xffff));
880 }
881 strm->adler = adler32(0L, Z_NULL, 0);
882 s->status = BUSY_STATE;
883
884 /* Compression must start with an empty pending buffer */
885 flush_pending(strm);
886 if (s->pending != 0) {
887 s->last_flush = -1;
888 return Z_OK;
889 }
890 }
891#ifdef GZIP
892 if (s->status == GZIP_STATE) {
893 /* gzip header */
894 strm->adler = crc32(0L, Z_NULL, 0);
895 put_byte(s, 31);
896 put_byte(s, 139);
897 put_byte(s, 8);
898 if (s->gzhead == Z_NULL) {
899 put_byte(s, 0);
900 put_byte(s, 0);
901 put_byte(s, 0);
902 put_byte(s, 0);
903 put_byte(s, 0);
904 put_byte(s, s->level == 9 ? 2 :
905 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
906 4 : 0));
907 put_byte(s, OS_CODE);
908 s->status = BUSY_STATE;
909
910 /* Compression must start with an empty pending buffer */
911 flush_pending(strm);
912 if (s->pending != 0) {
913 s->last_flush = -1;
914 return Z_OK;
915 }
916 }
917 else {
918 put_byte(s, (s->gzhead->text ? 1 : 0) +
919 (s->gzhead->hcrc ? 2 : 0) +
920 (s->gzhead->extra == Z_NULL ? 0 : 4) +
921 (s->gzhead->name == Z_NULL ? 0 : 8) +
922 (s->gzhead->comment == Z_NULL ? 0 : 16)
923 );
924 put_byte(s, (Byte)(s->gzhead->time & 0xff));
925 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
926 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
927 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
928 put_byte(s, s->level == 9 ? 2 :
929 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
930 4 : 0));
931 put_byte(s, s->gzhead->os & 0xff);
932 if (s->gzhead->extra != Z_NULL) {
933 put_byte(s, s->gzhead->extra_len & 0xff);
934 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
935 }
936 if (s->gzhead->hcrc)
937 strm->adler = crc32(strm->adler, s->pending_buf,
938 s->pending);
939 s->gzindex = 0;
940 s->status = EXTRA_STATE;
941 }
942 }
943 if (s->status == EXTRA_STATE) {
944 if (s->gzhead->extra != Z_NULL) {
945 ulg beg = s->pending; /* start of bytes to update crc */
946 uInt left = (s->gzhead->extra_len & 0xffff) - s->gzindex;
947 while (s->pending + left > s->pending_buf_size) {
948 uInt copy = s->pending_buf_size - s->pending;
949 zmemcpy(s->pending_buf + s->pending,
950 s->gzhead->extra + s->gzindex, copy);
951 s->pending = s->pending_buf_size;
952 HCRC_UPDATE(beg);
953 s->gzindex += copy;
954 flush_pending(strm);
955 if (s->pending != 0) {
956 s->last_flush = -1;
957 return Z_OK;
958 }
959 beg = 0;
960 left -= copy;
961 }
962 zmemcpy(s->pending_buf + s->pending,
963 s->gzhead->extra + s->gzindex, left);
964 s->pending += left;
965 HCRC_UPDATE(beg);
966 s->gzindex = 0;
967 }
968 s->status = NAME_STATE;
969 }
970 if (s->status == NAME_STATE) {
971 if (s->gzhead->name != Z_NULL) {
972 ulg beg = s->pending; /* start of bytes to update crc */
973 int val;
974 do {
975 if (s->pending == s->pending_buf_size) {
976 HCRC_UPDATE(beg);
977 flush_pending(strm);
978 if (s->pending != 0) {
979 s->last_flush = -1;
980 return Z_OK;
981 }
982 beg = 0;
983 }
984 val = s->gzhead->name[s->gzindex++];
985 put_byte(s, val);
986 } while (val != 0);
987 HCRC_UPDATE(beg);
988 s->gzindex = 0;
989 }
990 s->status = COMMENT_STATE;
991 }
992 if (s->status == COMMENT_STATE) {
993 if (s->gzhead->comment != Z_NULL) {
994 ulg beg = s->pending; /* start of bytes to update crc */
995 int val;
996 do {
997 if (s->pending == s->pending_buf_size) {
998 HCRC_UPDATE(beg);
999 flush_pending(strm);
1000 if (s->pending != 0) {
1001 s->last_flush = -1;
1002 return Z_OK;
1003 }
1004 beg = 0;
1005 }
1006 val = s->gzhead->comment[s->gzindex++];
1007 put_byte(s, val);
1008 } while (val != 0);
1009 HCRC_UPDATE(beg);
1010 }
1011 s->status = HCRC_STATE;
1012 }
1013 if (s->status == HCRC_STATE) {
1014 if (s->gzhead->hcrc) {
1015 if (s->pending + 2 > s->pending_buf_size) {
1016 flush_pending(strm);
1017 if (s->pending != 0) {
1018 s->last_flush = -1;
1019 return Z_OK;
1020 }
1021 }
1022 put_byte(s, (Byte)(strm->adler & 0xff));
1023 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
1024 strm->adler = crc32(0L, Z_NULL, 0);
1025 }
1026 s->status = BUSY_STATE;
1027
1028 /* Compression must start with an empty pending buffer */
1029 flush_pending(strm);
1030 if (s->pending != 0) {
1031 s->last_flush = -1;
1032 return Z_OK;
1033 }
1034 }
1035#endif
1036
1037 /* Start a new block or continue the current one.
1038 */
1039 if (strm->avail_in != 0 || s->lookahead != 0 ||
1040 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
1041 block_state bstate;
1042
1043 bstate = s->level == 0 ? deflate_stored(s, flush) :
1044 s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
1045 s->strategy == Z_RLE ? deflate_rle(s, flush) :
1046 (*(configuration_table[s->level].func))(s, flush);
1047
1048 if (bstate == finish_started || bstate == finish_done) {
1049 s->status = FINISH_STATE;
1050 }
1051 if (bstate == need_more || bstate == finish_started) {
1052 if (strm->avail_out == 0) {
1053 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
1054 }
1055 return Z_OK;
1056 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
1057 * of deflate should use the same flush parameter to make sure
1058 * that the flush is complete. So we don't have to output an
1059 * empty block here, this will be done at next call. This also
1060 * ensures that for a very small output buffer, we emit at most
1061 * one empty block.
1062 */
1063 }
1064 if (bstate == block_done) {
1065 if (flush == Z_PARTIAL_FLUSH) {
1066 _tr_align(s);
1067 } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
1068 _tr_stored_block(s, (char*)0, 0L, 0);
1069 /* For a full flush, this empty block will be recognized
1070 * as a special marker by inflate_sync().
1071 */
1072 if (flush == Z_FULL_FLUSH) {
1073 CLEAR_HASH(s); /* forget history */
1074 if (s->lookahead == 0) {
1075 s->strstart = 0;
1076 s->block_start = 0L;
1077 s->insert = 0;
1078 }
1079 }
1080 }
1081 flush_pending(strm);
1082 if (strm->avail_out == 0) {
1083 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
1084 return Z_OK;
1085 }
1086 }
1087 }
1088
1089 if (flush != Z_FINISH) return Z_OK;
1090 if (s->wrap <= 0) return Z_STREAM_END;
1091
1092 /* Write the trailer */
1093#ifdef GZIP
1094 if (s->wrap == 2) {
1095 put_byte(s, (Byte)(strm->adler & 0xff));
1096 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
1097 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
1098 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
1099 put_byte(s, (Byte)(strm->total_in & 0xff));
1100 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
1101 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
1102 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
1103 }
1104 else
1105#endif
1106 {
1107 putShortMSB(s, (uInt)(strm->adler >> 16));
1108 putShortMSB(s, (uInt)(strm->adler & 0xffff));
1109 }
1110 flush_pending(strm);
1111 /* If avail_out is zero, the application will call deflate again
1112 * to flush the rest.
1113 */
1114 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
1115 return s->pending != 0 ? Z_OK : Z_STREAM_END;
1116}
1117
1118/* ========================================================================= */
1119int ZEXPORT deflateEnd (strm)
1120 z_streamp strm;
1121{
1122 int status;
1123
1124 if (deflateStateCheck(strm)) return Z_STREAM_ERROR;
1125
1126 status = strm->state->status;
1127
1128 /* Deallocate in reverse order of allocations: */
1129 TRY_FREE(strm, strm->state->pending_buf);
1130 TRY_FREE(strm, strm->state->head);
1131 TRY_FREE(strm, strm->state->prev);
1132 TRY_FREE(strm, strm->state->window);
1133
1134 ZFREE(strm, strm->state);
1135 strm->state = Z_NULL;
1136
1137 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1138}
1139
1140/* =========================================================================
1141 * Copy the source state to the destination state.
1142 * To simplify the source, this is not supported for 16-bit MSDOS (which
1143 * doesn't have enough memory anyway to duplicate compression states).
1144 */
1145int ZEXPORT deflateCopy (dest, source)
1146 z_streamp dest;
1147 z_streamp source;
1148{
1149#ifdef MAXSEG_64K
1150 return Z_STREAM_ERROR;
1151#else
1152 deflate_state *ds;
1153 deflate_state *ss;
1154
1155
1156 if (deflateStateCheck(source) || dest == Z_NULL) {
1157 return Z_STREAM_ERROR;
1158 }
1159
1160 ss = source->state;
1161
1162 zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1163
1164 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1165 if (ds == Z_NULL) return Z_MEM_ERROR;
1166 dest->state = (struct internal_state FAR *) ds;
1167 zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1168 ds->strm = dest;
1169
1170 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1171 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1172 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1173 ds->pending_buf = (uchf *) ZALLOC(dest, ds->lit_bufsize, 4);
1174
1175 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1176 ds->pending_buf == Z_NULL) {
1177 deflateEnd (dest);
1178 return Z_MEM_ERROR;
1179 }
1180 /* following zmemcpy do not work for 16-bit MSDOS */
1181 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1182 zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1183 zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1184 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1185
1186 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1187 ds->sym_buf = ds->pending_buf + ds->lit_bufsize;
1188
1189 ds->l_desc.dyn_tree = ds->dyn_ltree;
1190 ds->d_desc.dyn_tree = ds->dyn_dtree;
1191 ds->bl_desc.dyn_tree = ds->bl_tree;
1192
1193 return Z_OK;
1194#endif /* MAXSEG_64K */
1195}
1196
1197/* ===========================================================================
1198 * Read a new buffer from the current input stream, update the adler32
1199 * and total number of bytes read. All deflate() input goes through
1200 * this function so some applications may wish to modify it to avoid
1201 * allocating a large strm->next_in buffer and copying from it.
1202 * (See also flush_pending()).
1203 */
1204local unsigned read_buf(strm, buf, size)
1205 z_streamp strm;
1206 Bytef *buf;
1207 unsigned size;
1208{
1209 unsigned len = strm->avail_in;
1210
1211 if (len > size) len = size;
1212 if (len == 0) return 0;
1213
1214 strm->avail_in -= len;
1215
1216 zmemcpy(buf, strm->next_in, len);
1217 if (strm->state->wrap == 1) {
1218 strm->adler = adler32(strm->adler, buf, len);
1219 }
1220#ifdef GZIP
1221 else if (strm->state->wrap == 2) {
1222 strm->adler = crc32(strm->adler, buf, len);
1223 }
1224#endif
1225 strm->next_in += len;
1226 strm->total_in += len;
1227
1228 return len;
1229}
1230
1231/* ===========================================================================
1232 * Initialize the "longest match" routines for a new zlib stream
1233 */
1234local void lm_init (s)
1235 deflate_state *s;
1236{
1237 s->window_size = (ulg)2L*s->w_size;
1238
1239 CLEAR_HASH(s);
1240
1241 /* Set the default configuration parameters:
1242 */
1243 s->max_lazy_match = configuration_table[s->level].max_lazy;
1244 s->good_match = configuration_table[s->level].good_length;
1245 s->nice_match = configuration_table[s->level].nice_length;
1246 s->max_chain_length = configuration_table[s->level].max_chain;
1247
1248 s->strstart = 0;
1249 s->block_start = 0L;
1250 s->lookahead = 0;
1251 s->insert = 0;
1252 s->match_length = s->prev_length = MIN_MATCH-1;
1253 s->match_available = 0;
1254 s->ins_h = 0;
1255#ifndef FASTEST
1256#ifdef ASMV
1257 match_init(); /* initialize the asm code */
1258#endif
1259#endif
1260}
1261
1262#ifndef FASTEST
1263/* ===========================================================================
1264 * Set match_start to the longest match starting at the given string and
1265 * return its length. Matches shorter or equal to prev_length are discarded,
1266 * in which case the result is equal to prev_length and match_start is
1267 * garbage.
1268 * IN assertions: cur_match is the head of the hash chain for the current
1269 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1270 * OUT assertion: the match length is not greater than s->lookahead.
1271 */
1272#ifndef ASMV
1273/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1274 * match.S. The code will be functionally equivalent.
1275 */
1276local uInt longest_match(s, cur_match)
1277 deflate_state *s;
1278 IPos cur_match; /* current match */
1279{
1280 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1281 register Bytef *scan = s->window + s->strstart; /* current string */
1282 register Bytef *match; /* matched string */
1283 register int len; /* length of current match */
1284 int best_len = (int)s->prev_length; /* best match length so far */
1285 int nice_match = s->nice_match; /* stop if match long enough */
1286 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1287 s->strstart - (IPos)MAX_DIST(s) : NIL;
1288 /* Stop when cur_match becomes <= limit. To simplify the code,
1289 * we prevent matches with the string of window index 0.
1290 */
1291 Posf *prev = s->prev;
1292 uInt wmask = s->w_mask;
1293
1294#ifdef UNALIGNED_OK
1295 /* Compare two bytes at a time. Note: this is not always beneficial.
1296 * Try with and without -DUNALIGNED_OK to check.
1297 */
1298 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1299 register ush scan_start = *(ushf*)scan;
1300 register ush scan_end = *(ushf*)(scan+best_len-1);
1301#else
1302 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1303 register Byte scan_end1 = scan[best_len-1];
1304 register Byte scan_end = scan[best_len];
1305#endif
1306
1307 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1308 * It is easy to get rid of this optimization if necessary.
1309 */
1310 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1311
1312 /* Do not waste too much time if we already have a good match: */
1313 if (s->prev_length >= s->good_match) {
1314 chain_length >>= 2;
1315 }
1316 /* Do not look for matches beyond the end of the input. This is necessary
1317 * to make deflate deterministic.
1318 */
1319 if ((uInt)nice_match > s->lookahead) nice_match = (int)s->lookahead;
1320
1321 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1322
1323 do {
1324 Assert(cur_match < s->strstart, "no future");
1325 match = s->window + cur_match;
1326
1327 /* Skip to next match if the match length cannot increase
1328 * or if the match length is less than 2. Note that the checks below
1329 * for insufficient lookahead only occur occasionally for performance
1330 * reasons. Therefore uninitialized memory will be accessed, and
1331 * conditional jumps will be made that depend on those values.
1332 * However the length of the match is limited to the lookahead, so
1333 * the output of deflate is not affected by the uninitialized values.
1334 */
1335#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1336 /* This code assumes sizeof(unsigned short) == 2. Do not use
1337 * UNALIGNED_OK if your compiler uses a different size.
1338 */
1339 if (*(ushf*)(match+best_len-1) != scan_end ||
1340 *(ushf*)match != scan_start) continue;
1341
1342 /* It is not necessary to compare scan[2] and match[2] since they are
1343 * always equal when the other bytes match, given that the hash keys
1344 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1345 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1346 * lookahead only every 4th comparison; the 128th check will be made
1347 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1348 * necessary to put more guard bytes at the end of the window, or
1349 * to check more often for insufficient lookahead.
1350 */
1351 Assert(scan[2] == match[2], "scan[2]?");
1352 scan++, match++;
1353 do {
1354 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1355 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1356 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1357 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1358 scan < strend);
1359 /* The funny "do {}" generates better code on most compilers */
1360
1361 /* Here, scan <= window+strstart+257 */
1362 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1363 if (*scan == *match) scan++;
1364
1365 len = (MAX_MATCH - 1) - (int)(strend-scan);
1366 scan = strend - (MAX_MATCH-1);
1367
1368#else /* UNALIGNED_OK */
1369
1370 if (match[best_len] != scan_end ||
1371 match[best_len-1] != scan_end1 ||
1372 *match != *scan ||
1373 *++match != scan[1]) continue;
1374
1375 /* The check at best_len-1 can be removed because it will be made
1376 * again later. (This heuristic is not always a win.)
1377 * It is not necessary to compare scan[2] and match[2] since they
1378 * are always equal when the other bytes match, given that
1379 * the hash keys are equal and that HASH_BITS >= 8.
1380 */
1381 scan += 2, match++;
1382 Assert(*scan == *match, "match[2]?");
1383
1384 /* We check for insufficient lookahead only every 8th comparison;
1385 * the 256th check will be made at strstart+258.
1386 */
1387 do {
1388 } while (*++scan == *++match && *++scan == *++match &&
1389 *++scan == *++match && *++scan == *++match &&
1390 *++scan == *++match && *++scan == *++match &&
1391 *++scan == *++match && *++scan == *++match &&
1392 scan < strend);
1393
1394 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1395
1396 len = MAX_MATCH - (int)(strend - scan);
1397 scan = strend - MAX_MATCH;
1398
1399#endif /* UNALIGNED_OK */
1400
1401 if (len > best_len) {
1402 s->match_start = cur_match;
1403 best_len = len;
1404 if (len >= nice_match) break;
1405#ifdef UNALIGNED_OK
1406 scan_end = *(ushf*)(scan+best_len-1);
1407#else
1408 scan_end1 = scan[best_len-1];
1409 scan_end = scan[best_len];
1410#endif
1411 }
1412 } while ((cur_match = prev[cur_match & wmask]) > limit
1413 && --chain_length != 0);
1414
1415 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1416 return s->lookahead;
1417}
1418#endif /* ASMV */
1419
1420#else /* FASTEST */
1421
1422/* ---------------------------------------------------------------------------
1423 * Optimized version for FASTEST only
1424 */
1425local uInt longest_match(s, cur_match)
1426 deflate_state *s;
1427 IPos cur_match; /* current match */
1428{
1429 register Bytef *scan = s->window + s->strstart; /* current string */
1430 register Bytef *match; /* matched string */
1431 register int len; /* length of current match */
1432 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1433
1434 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1435 * It is easy to get rid of this optimization if necessary.
1436 */
1437 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1438
1439 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1440
1441 Assert(cur_match < s->strstart, "no future");
1442
1443 match = s->window + cur_match;
1444
1445 /* Return failure if the match length is less than 2:
1446 */
1447 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1448
1449 /* The check at best_len-1 can be removed because it will be made
1450 * again later. (This heuristic is not always a win.)
1451 * It is not necessary to compare scan[2] and match[2] since they
1452 * are always equal when the other bytes match, given that
1453 * the hash keys are equal and that HASH_BITS >= 8.
1454 */
1455 scan += 2, match += 2;
1456 Assert(*scan == *match, "match[2]?");
1457
1458 /* We check for insufficient lookahead only every 8th comparison;
1459 * the 256th check will be made at strstart+258.
1460 */
1461 do {
1462 } while (*++scan == *++match && *++scan == *++match &&
1463 *++scan == *++match && *++scan == *++match &&
1464 *++scan == *++match && *++scan == *++match &&
1465 *++scan == *++match && *++scan == *++match &&
1466 scan < strend);
1467
1468 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1469
1470 len = MAX_MATCH - (int)(strend - scan);
1471
1472 if (len < MIN_MATCH) return MIN_MATCH - 1;
1473
1474 s->match_start = cur_match;
1475 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1476}
1477
1478#endif /* FASTEST */
1479
1480#ifdef ZLIB_DEBUG
1481
1482#define EQUAL 0
1483/* result of memcmp for equal strings */
1484
1485/* ===========================================================================
1486 * Check that the match at match_start is indeed a match.
1487 */
1488local void check_match(s, start, match, length)
1489 deflate_state *s;
1490 IPos start, match;
1491 int length;
1492{
1493 /* check that the match is indeed a match */
1494 if (zmemcmp(s->window + match,
1495 s->window + start, length) != EQUAL) {
1496 fprintf(stderr, " start %u, match %u, length %d\n",
1497 start, match, length);
1498 do {
1499 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1500 } while (--length != 0);
1501 z_error("invalid match");
1502 }
1503 if (z_verbose > 1) {
1504 fprintf(stderr,"\\[%d,%d]", start-match, length);
1505 do { putc(s->window[start++], stderr); } while (--length != 0);
1506 }
1507}
1508#else
1509# define check_match(s, start, match, length)
1510#endif /* ZLIB_DEBUG */
1511
1512/* ===========================================================================
1513 * Fill the window when the lookahead becomes insufficient.
1514 * Updates strstart and lookahead.
1515 *
1516 * IN assertion: lookahead < MIN_LOOKAHEAD
1517 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1518 * At least one byte has been read, or avail_in == 0; reads are
1519 * performed for at least two bytes (required for the zip translate_eol
1520 * option -- not supported here).
1521 */
1522local void fill_window(s)
1523 deflate_state *s;
1524{
1525 unsigned n;
1526 unsigned more; /* Amount of free space at the end of the window. */
1527 uInt wsize = s->w_size;
1528
1529 Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1530
1531 do {
1532 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1533
1534 /* Deal with !@#$% 64K limit: */
1535 if (sizeof(int) <= 2) {
1536 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1537 more = wsize;
1538
1539 } else if (more == (unsigned)(-1)) {
1540 /* Very unlikely, but possible on 16 bit machine if
1541 * strstart == 0 && lookahead == 1 (input done a byte at time)
1542 */
1543 more--;
1544 }
1545 }
1546
1547 /* If the window is almost full and there is insufficient lookahead,
1548 * move the upper half to the lower one to make room in the upper half.
1549 */
1550 if (s->strstart >= wsize+MAX_DIST(s)) {
1551
1552 zmemcpy(s->window, s->window+wsize, (unsigned)wsize - more);
1553 s->match_start -= wsize;
1554 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1555 s->block_start -= (long) wsize;
1556 if (s->insert > s->strstart)
1557 s->insert = s->strstart;
1558 slide_hash(s);
1559 more += wsize;
1560 }
1561 if (s->strm->avail_in == 0) break;
1562
1563 /* If there was no sliding:
1564 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1565 * more == window_size - lookahead - strstart
1566 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1567 * => more >= window_size - 2*WSIZE + 2
1568 * In the BIG_MEM or MMAP case (not yet supported),
1569 * window_size == input_size + MIN_LOOKAHEAD &&
1570 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1571 * Otherwise, window_size == 2*WSIZE so more >= 2.
1572 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1573 */
1574 Assert(more >= 2, "more < 2");
1575
1576 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1577 s->lookahead += n;
1578
1579 /* Initialize the hash value now that we have some input: */
1580 if (s->lookahead + s->insert >= MIN_MATCH) {
1581 uInt str = s->strstart - s->insert;
1582 s->ins_h = s->window[str];
1583 UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1584#if MIN_MATCH != 3
1585 Call UPDATE_HASH() MIN_MATCH-3 more times
1586#endif
1587 while (s->insert) {
1588 UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1589#ifndef FASTEST
1590 s->prev[str & s->w_mask] = s->head[s->ins_h];
1591#endif
1592 s->head[s->ins_h] = (Pos)str;
1593 str++;
1594 s->insert--;
1595 if (s->lookahead + s->insert < MIN_MATCH)
1596 break;
1597 }
1598 }
1599 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1600 * but this is not important since only literal bytes will be emitted.
1601 */
1602
1603 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1604
1605 /* If the WIN_INIT bytes after the end of the current data have never been
1606 * written, then zero those bytes in order to avoid memory check reports of
1607 * the use of uninitialized (or uninitialised as Julian writes) bytes by
1608 * the longest match routines. Update the high water mark for the next
1609 * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1610 * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1611 */
1612 if (s->high_water < s->window_size) {
1613 ulg curr = s->strstart + (ulg)(s->lookahead);
1614 ulg init;
1615
1616 if (s->high_water < curr) {
1617 /* Previous high water mark below current data -- zero WIN_INIT
1618 * bytes or up to end of window, whichever is less.
1619 */
1620 init = s->window_size - curr;
1621 if (init > WIN_INIT)
1622 init = WIN_INIT;
1623 zmemzero(s->window + curr, (unsigned)init);
1624 s->high_water = curr + init;
1625 }
1626 else if (s->high_water < (ulg)curr + WIN_INIT) {
1627 /* High water mark at or above current data, but below current data
1628 * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1629 * to end of window, whichever is less.
1630 */
1631 init = (ulg)curr + WIN_INIT - s->high_water;
1632 if (init > s->window_size - s->high_water)
1633 init = s->window_size - s->high_water;
1634 zmemzero(s->window + s->high_water, (unsigned)init);
1635 s->high_water += init;
1636 }
1637 }
1638
1639 Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1640 "not enough room for search");
1641}
1642
1643/* ===========================================================================
1644 * Flush the current block, with given end-of-file flag.
1645 * IN assertion: strstart is set to the end of the current match.
1646 */
1647#define FLUSH_BLOCK_ONLY(s, last) { \
1648 _tr_flush_block(s, (s->block_start >= 0L ? \
1649 (charf *)&s->window[(unsigned)s->block_start] : \
1650 (charf *)Z_NULL), \
1651 (ulg)((long)s->strstart - s->block_start), \
1652 (last)); \
1653 s->block_start = s->strstart; \
1654 flush_pending(s->strm); \
1655 Tracev((stderr,"[FLUSH]")); \
1656}
1657
1658/* Same but force premature exit if necessary. */
1659#define FLUSH_BLOCK(s, last) { \
1660 FLUSH_BLOCK_ONLY(s, last); \
1661 if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1662}
1663
1664/* Maximum stored block length in deflate format (not including header). */
1665#define MAX_STORED 65535
1666
1667/* Minimum of a and b. */
1668#define MIN(a, b) ((a) > (b) ? (b) : (a))
1669
1670/* ===========================================================================
1671 * Copy without compression as much as possible from the input stream, return
1672 * the current block state.
1673 *
1674 * In case deflateParams() is used to later switch to a non-zero compression
1675 * level, s->matches (otherwise unused when storing) keeps track of the number
1676 * of hash table slides to perform. If s->matches is 1, then one hash table
1677 * slide will be done when switching. If s->matches is 2, the maximum value
1678 * allowed here, then the hash table will be cleared, since two or more slides
1679 * is the same as a clear.
1680 *
1681 * deflate_stored() is written to minimize the number of times an input byte is
1682 * copied. It is most efficient with large input and output buffers, which
1683 * maximizes the opportunites to have a single copy from next_in to next_out.
1684 */
1685local block_state deflate_stored(s, flush)
1686 deflate_state *s;
1687 int flush;
1688{
1689 /* Smallest worthy block size when not flushing or finishing. By default
1690 * this is 32K. This can be as small as 507 bytes for memLevel == 1. For
1691 * large input and output buffers, the stored block size will be larger.
1692 */
1693 unsigned min_block = MIN(s->pending_buf_size - 5, s->w_size);
1694
1695 /* Copy as many min_block or larger stored blocks directly to next_out as
1696 * possible. If flushing, copy the remaining available input to next_out as
1697 * stored blocks, if there is enough space.
1698 */
1699 unsigned len, left, have, last = 0;
1700 unsigned used = s->strm->avail_in;
1701 do {
1702 /* Set len to the maximum size block that we can copy directly with the
1703 * available input data and output space. Set left to how much of that
1704 * would be copied from what's left in the window.
1705 */
1706 len = MAX_STORED; /* maximum deflate stored block length */
1707 have = (s->bi_valid + 42) >> 3; /* number of header bytes */
1708 if (s->strm->avail_out < have) /* need room for header */
1709 break;
1710 /* maximum stored block length that will fit in avail_out: */
1711 have = s->strm->avail_out - have;
1712 left = s->strstart - s->block_start; /* bytes left in window */
1713 if (len > (ulg)left + s->strm->avail_in)
1714 len = left + s->strm->avail_in; /* limit len to the input */
1715 if (len > have)
1716 len = have; /* limit len to the output */
1717
1718 /* If the stored block would be less than min_block in length, or if
1719 * unable to copy all of the available input when flushing, then try
1720 * copying to the window and the pending buffer instead. Also don't
1721 * write an empty block when flushing -- deflate() does that.
1722 */
1723 if (len < min_block && ((len == 0 && flush != Z_FINISH) ||
1724 flush == Z_NO_FLUSH ||
1725 len != left + s->strm->avail_in))
1726 break;
1727
1728 /* Make a dummy stored block in pending to get the header bytes,
1729 * including any pending bits. This also updates the debugging counts.
1730 */
1731 last = flush == Z_FINISH && len == left + s->strm->avail_in ? 1 : 0;
1732 _tr_stored_block(s, (char *)0, 0L, last);
1733
1734 /* Replace the lengths in the dummy stored block with len. */
1735 s->pending_buf[s->pending - 4] = len;
1736 s->pending_buf[s->pending - 3] = len >> 8;
1737 s->pending_buf[s->pending - 2] = ~len;
1738 s->pending_buf[s->pending - 1] = ~len >> 8;
1739
1740 /* Write the stored block header bytes. */
1741 flush_pending(s->strm);
1742
1743#ifdef ZLIB_DEBUG
1744 /* Update debugging counts for the data about to be copied. */
1745 s->compressed_len += len << 3;
1746 s->bits_sent += len << 3;
1747#endif
1748
1749 /* Copy uncompressed bytes from the window to next_out. */
1750 if (left) {
1751 if (left > len)
1752 left = len;
1753 zmemcpy(s->strm->next_out, s->window + s->block_start, left);
1754 s->strm->next_out += left;
1755 s->strm->avail_out -= left;
1756 s->strm->total_out += left;
1757 s->block_start += left;
1758 len -= left;
1759 }
1760
1761 /* Copy uncompressed bytes directly from next_in to next_out, updating
1762 * the check value.
1763 */
1764 if (len) {
1765 read_buf(s->strm, s->strm->next_out, len);
1766 s->strm->next_out += len;
1767 s->strm->avail_out -= len;
1768 s->strm->total_out += len;
1769 }
1770 } while (last == 0);
1771
1772 /* Update the sliding window with the last s->w_size bytes of the copied
1773 * data, or append all of the copied data to the existing window if less
1774 * than s->w_size bytes were copied. Also update the number of bytes to
1775 * insert in the hash tables, in the event that deflateParams() switches to
1776 * a non-zero compression level.
1777 */
1778 used -= s->strm->avail_in; /* number of input bytes directly copied */
1779 if (used) {
1780 /* If any input was used, then no unused input remains in the window,
1781 * therefore s->block_start == s->strstart.
1782 */
1783 if (used >= s->w_size) { /* supplant the previous history */
1784 s->matches = 2; /* clear hash */
1785 zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size);
1786 s->strstart = s->w_size;
1787 s->insert = s->strstart;
1788 }
1789 else {
1790 if (s->window_size - s->strstart <= used) {
1791 /* Slide the window down. */
1792 s->strstart -= s->w_size;
1793 zmemcpy(s->window, s->window + s->w_size, s->strstart);
1794 if (s->matches < 2)
1795 s->matches++; /* add a pending slide_hash() */
1796 if (s->insert > s->strstart)
1797 s->insert = s->strstart;
1798 }
1799 zmemcpy(s->window + s->strstart, s->strm->next_in - used, used);
1800 s->strstart += used;
1801 s->insert += MIN(used, s->w_size - s->insert);
1802 }
1803 s->block_start = s->strstart;
1804 }
1805 if (s->high_water < s->strstart)
1806 s->high_water = s->strstart;
1807
1808 /* If the last block was written to next_out, then done. */
1809 if (last)
1810 return finish_done;
1811
1812 /* If flushing and all input has been consumed, then done. */
1813 if (flush != Z_NO_FLUSH && flush != Z_FINISH &&
1814 s->strm->avail_in == 0 && (long)s->strstart == s->block_start)
1815 return block_done;
1816
1817 /* Fill the window with any remaining input. */
1818 have = s->window_size - s->strstart;
1819 if (s->strm->avail_in > have && s->block_start >= (long)s->w_size) {
1820 /* Slide the window down. */
1821 s->block_start -= s->w_size;
1822 s->strstart -= s->w_size;
1823 zmemcpy(s->window, s->window + s->w_size, s->strstart);
1824 if (s->matches < 2)
1825 s->matches++; /* add a pending slide_hash() */
1826 have += s->w_size; /* more space now */
1827 if (s->insert > s->strstart)
1828 s->insert = s->strstart;
1829 }
1830 if (have > s->strm->avail_in)
1831 have = s->strm->avail_in;
1832 if (have) {
1833 read_buf(s->strm, s->window + s->strstart, have);
1834 s->strstart += have;
1835 s->insert += MIN(have, s->w_size - s->insert);
1836 }
1837 if (s->high_water < s->strstart)
1838 s->high_water = s->strstart;
1839
1840 /* There was not enough avail_out to write a complete worthy or flushed
1841 * stored block to next_out. Write a stored block to pending instead, if we
1842 * have enough input for a worthy block, or if flushing and there is enough
1843 * room for the remaining input as a stored block in the pending buffer.
1844 */
1845 have = (s->bi_valid + 42) >> 3; /* number of header bytes */
1846 /* maximum stored block length that will fit in pending: */
1847 have = MIN(s->pending_buf_size - have, MAX_STORED);
1848 min_block = MIN(have, s->w_size);
1849 left = s->strstart - s->block_start;
1850 if (left >= min_block ||
1851 ((left || flush == Z_FINISH) && flush != Z_NO_FLUSH &&
1852 s->strm->avail_in == 0 && left <= have)) {
1853 len = MIN(left, have);
1854 last = flush == Z_FINISH && s->strm->avail_in == 0 &&
1855 len == left ? 1 : 0;
1856 _tr_stored_block(s, (charf *)s->window + s->block_start, len, last);
1857 s->block_start += len;
1858 flush_pending(s->strm);
1859 }
1860
1861 /* We've done all we can with the available input and output. */
1862 return last ? finish_started : need_more;
1863}
1864
1865/* ===========================================================================
1866 * Compress as much as possible from the input stream, return the current
1867 * block state.
1868 * This function does not perform lazy evaluation of matches and inserts
1869 * new strings in the dictionary only for unmatched strings or for short
1870 * matches. It is used only for the fast compression options.
1871 */
1872local block_state deflate_fast(s, flush)
1873 deflate_state *s;
1874 int flush;
1875{
1876 IPos hash_head; /* head of the hash chain */
1877 int bflush; /* set if current block must be flushed */
1878
1879 for (;;) {
1880 /* Make sure that we always have enough lookahead, except
1881 * at the end of the input file. We need MAX_MATCH bytes
1882 * for the next match, plus MIN_MATCH bytes to insert the
1883 * string following the next match.
1884 */
1885 if (s->lookahead < MIN_LOOKAHEAD) {
1886 fill_window(s);
1887 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1888 return need_more;
1889 }
1890 if (s->lookahead == 0) break; /* flush the current block */
1891 }
1892
1893 /* Insert the string window[strstart .. strstart+2] in the
1894 * dictionary, and set hash_head to the head of the hash chain:
1895 */
1896 hash_head = NIL;
1897 if (s->lookahead >= MIN_MATCH) {
1898 INSERT_STRING(s, s->strstart, hash_head);
1899 }
1900
1901 /* Find the longest match, discarding those <= prev_length.
1902 * At this point we have always match_length < MIN_MATCH
1903 */
1904 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1905 /* To simplify the code, we prevent matches with the string
1906 * of window index 0 (in particular we have to avoid a match
1907 * of the string with itself at the start of the input file).
1908 */
1909 s->match_length = longest_match (s, hash_head);
1910 /* longest_match() sets match_start */
1911 }
1912 if (s->match_length >= MIN_MATCH) {
1913 check_match(s, s->strstart, s->match_start, s->match_length);
1914
1915 _tr_tally_dist(s, s->strstart - s->match_start,
1916 s->match_length - MIN_MATCH, bflush);
1917
1918 s->lookahead -= s->match_length;
1919
1920 /* Insert new strings in the hash table only if the match length
1921 * is not too large. This saves time but degrades compression.
1922 */
1923#ifndef FASTEST
1924 if (s->match_length <= s->max_insert_length &&
1925 s->lookahead >= MIN_MATCH) {
1926 s->match_length--; /* string at strstart already in table */
1927 do {
1928 s->strstart++;
1929 INSERT_STRING(s, s->strstart, hash_head);
1930 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1931 * always MIN_MATCH bytes ahead.
1932 */
1933 } while (--s->match_length != 0);
1934 s->strstart++;
1935 } else
1936#endif
1937 {
1938 s->strstart += s->match_length;
1939 s->match_length = 0;
1940 s->ins_h = s->window[s->strstart];
1941 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1942#if MIN_MATCH != 3
1943 Call UPDATE_HASH() MIN_MATCH-3 more times
1944#endif
1945 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1946 * matter since it will be recomputed at next deflate call.
1947 */
1948 }
1949 } else {
1950 /* No match, output a literal byte */
1951 Tracevv((stderr,"%c", s->window[s->strstart]));
1952 _tr_tally_lit (s, s->window[s->strstart], bflush);
1953 s->lookahead--;
1954 s->strstart++;
1955 }
1956 if (bflush) FLUSH_BLOCK(s, 0);
1957 }
1958 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1959 if (flush == Z_FINISH) {
1960 FLUSH_BLOCK(s, 1);
1961 return finish_done;
1962 }
1963 if (s->sym_next)
1964 FLUSH_BLOCK(s, 0);
1965 return block_done;
1966}
1967
1968#ifndef FASTEST
1969/* ===========================================================================
1970 * Same as above, but achieves better compression. We use a lazy
1971 * evaluation for matches: a match is finally adopted only if there is
1972 * no better match at the next window position.
1973 */
1974local block_state deflate_slow(s, flush)
1975 deflate_state *s;
1976 int flush;
1977{
1978 IPos hash_head; /* head of hash chain */
1979 int bflush; /* set if current block must be flushed */
1980
1981 /* Process the input block. */
1982 for (;;) {
1983 /* Make sure that we always have enough lookahead, except
1984 * at the end of the input file. We need MAX_MATCH bytes
1985 * for the next match, plus MIN_MATCH bytes to insert the
1986 * string following the next match.
1987 */
1988 if (s->lookahead < MIN_LOOKAHEAD) {
1989 fill_window(s);
1990 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1991 return need_more;
1992 }
1993 if (s->lookahead == 0) break; /* flush the current block */
1994 }
1995
1996 /* Insert the string window[strstart .. strstart+2] in the
1997 * dictionary, and set hash_head to the head of the hash chain:
1998 */
1999 hash_head = NIL;
2000 if (s->lookahead >= MIN_MATCH) {
2001 INSERT_STRING(s, s->strstart, hash_head);
2002 }
2003
2004 /* Find the longest match, discarding those <= prev_length.
2005 */
2006 s->prev_length = s->match_length, s->prev_match = s->match_start;
2007 s->match_length = MIN_MATCH-1;
2008
2009 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
2010 s->strstart - hash_head <= MAX_DIST(s)) {
2011 /* To simplify the code, we prevent matches with the string
2012 * of window index 0 (in particular we have to avoid a match
2013 * of the string with itself at the start of the input file).
2014 */
2015 s->match_length = longest_match (s, hash_head);
2016 /* longest_match() sets match_start */
2017
2018 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
2019#if TOO_FAR <= 32767
2020 || (s->match_length == MIN_MATCH &&
2021 s->strstart - s->match_start > TOO_FAR)
2022#endif
2023 )) {
2024
2025 /* If prev_match is also MIN_MATCH, match_start is garbage
2026 * but we will ignore the current match anyway.
2027 */
2028 s->match_length = MIN_MATCH-1;
2029 }
2030 }
2031 /* If there was a match at the previous step and the current
2032 * match is not better, output the previous match:
2033 */
2034 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
2035 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
2036 /* Do not insert strings in hash table beyond this. */
2037
2038 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
2039
2040 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
2041 s->prev_length - MIN_MATCH, bflush);
2042
2043 /* Insert in hash table all strings up to the end of the match.
2044 * strstart-1 and strstart are already inserted. If there is not
2045 * enough lookahead, the last two strings are not inserted in
2046 * the hash table.
2047 */
2048 s->lookahead -= s->prev_length-1;
2049 s->prev_length -= 2;
2050 do {
2051 if (++s->strstart <= max_insert) {
2052 INSERT_STRING(s, s->strstart, hash_head);
2053 }
2054 } while (--s->prev_length != 0);
2055 s->match_available = 0;
2056 s->match_length = MIN_MATCH-1;
2057 s->strstart++;
2058
2059 if (bflush) FLUSH_BLOCK(s, 0);
2060
2061 } else if (s->match_available) {
2062 /* If there was no match at the previous position, output a
2063 * single literal. If there was a match but the current match
2064 * is longer, truncate the previous match to a single literal.
2065 */
2066 Tracevv((stderr,"%c", s->window[s->strstart-1]));
2067 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
2068 if (bflush) {
2069 FLUSH_BLOCK_ONLY(s, 0);
2070 }
2071 s->strstart++;
2072 s->lookahead--;
2073 if (s->strm->avail_out == 0) return need_more;
2074 } else {
2075 /* There is no previous match to compare with, wait for
2076 * the next step to decide.
2077 */
2078 s->match_available = 1;
2079 s->strstart++;
2080 s->lookahead--;
2081 }
2082 }
2083 Assert (flush != Z_NO_FLUSH, "no flush?");
2084 if (s->match_available) {
2085 Tracevv((stderr,"%c", s->window[s->strstart-1]));
2086 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
2087 s->match_available = 0;
2088 }
2089 s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
2090 if (flush == Z_FINISH) {
2091 FLUSH_BLOCK(s, 1);
2092 return finish_done;
2093 }
2094 if (s->sym_next)
2095 FLUSH_BLOCK(s, 0);
2096 return block_done;
2097}
2098#endif /* FASTEST */
2099
2100/* ===========================================================================
2101 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
2102 * one. Do not maintain a hash table. (It will be regenerated if this run of
2103 * deflate switches away from Z_RLE.)
2104 */
2105local block_state deflate_rle(s, flush)
2106 deflate_state *s;
2107 int flush;
2108{
2109 int bflush; /* set if current block must be flushed */
2110 uInt prev; /* byte at distance one to match */
2111 Bytef *scan, *strend; /* scan goes up to strend for length of run */
2112
2113 for (;;) {
2114 /* Make sure that we always have enough lookahead, except
2115 * at the end of the input file. We need MAX_MATCH bytes
2116 * for the longest run, plus one for the unrolled loop.
2117 */
2118 if (s->lookahead <= MAX_MATCH) {
2119 fill_window(s);
2120 if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
2121 return need_more;
2122 }
2123 if (s->lookahead == 0) break; /* flush the current block */
2124 }
2125
2126 /* See how many times the previous byte repeats */
2127 s->match_length = 0;
2128 if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
2129 scan = s->window + s->strstart - 1;
2130 prev = *scan;
2131 if (prev == *++scan && prev == *++scan && prev == *++scan) {
2132 strend = s->window + s->strstart + MAX_MATCH;
2133 do {
2134 } while (prev == *++scan && prev == *++scan &&
2135 prev == *++scan && prev == *++scan &&
2136 prev == *++scan && prev == *++scan &&
2137 prev == *++scan && prev == *++scan &&
2138 scan < strend);
2139 s->match_length = MAX_MATCH - (uInt)(strend - scan);
2140 if (s->match_length > s->lookahead)
2141 s->match_length = s->lookahead;
2142 }
2143 Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
2144 }
2145
2146 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
2147 if (s->match_length >= MIN_MATCH) {
2148 check_match(s, s->strstart, s->strstart - 1, s->match_length);
2149
2150 _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
2151
2152 s->lookahead -= s->match_length;
2153 s->strstart += s->match_length;
2154 s->match_length = 0;
2155 } else {
2156 /* No match, output a literal byte */
2157 Tracevv((stderr,"%c", s->window[s->strstart]));
2158 _tr_tally_lit (s, s->window[s->strstart], bflush);
2159 s->lookahead--;
2160 s->strstart++;
2161 }
2162 if (bflush) FLUSH_BLOCK(s, 0);
2163 }
2164 s->insert = 0;
2165 if (flush == Z_FINISH) {
2166 FLUSH_BLOCK(s, 1);
2167 return finish_done;
2168 }
2169 if (s->sym_next)
2170 FLUSH_BLOCK(s, 0);
2171 return block_done;
2172}
2173
2174/* ===========================================================================
2175 * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
2176 * (It will be regenerated if this run of deflate switches away from Huffman.)
2177 */
2178local block_state deflate_huff(s, flush)
2179 deflate_state *s;
2180 int flush;
2181{
2182 int bflush; /* set if current block must be flushed */
2183
2184 for (;;) {
2185 /* Make sure that we have a literal to write. */
2186 if (s->lookahead == 0) {
2187 fill_window(s);
2188 if (s->lookahead == 0) {
2189 if (flush == Z_NO_FLUSH)
2190 return need_more;
2191 break; /* flush the current block */
2192 }
2193 }
2194
2195 /* Output a literal byte */
2196 s->match_length = 0;
2197 Tracevv((stderr,"%c", s->window[s->strstart]));
2198 _tr_tally_lit (s, s->window[s->strstart], bflush);
2199 s->lookahead--;
2200 s->strstart++;
2201 if (bflush) FLUSH_BLOCK(s, 0);
2202 }
2203 s->insert = 0;
2204 if (flush == Z_FINISH) {
2205 FLUSH_BLOCK(s, 1);
2206 return finish_done;
2207 }
2208 if (s->sym_next)
2209 FLUSH_BLOCK(s, 0);
2210 return block_done;
2211}
2212