s4:provision Don't reference provision_backend when using LDB
[Samba/ekacnet.git] / lib / zlib / deflate.c
blob2720aab91122f917718c8b71c25a6697360dca42
1 /* deflate.c -- compress data using the deflation algorithm
2 * Copyright (C) 1995-2005 Jean-loup Gailly.
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
6 /*
7 * ALGORITHM
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).
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.
31 * ACKNOWLEDGEMENTS
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.
37 * REFERENCES
39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40 * Available in http://www.ietf.org/rfc/rfc1951.txt
42 * A description of the Rabin and Karp algorithm is given in the book
43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
45 * Fiala,E.R., and Greene,D.H.
46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
50 /* @(#) $Id$ */
52 #include "deflate.h"
54 const char deflate_copyright[] =
55 " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly ";
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.
63 /* ===========================================================================
64 * Function prototypes.
66 typedef enum {
67 need_more, /* block not completed, need more input or more output */
68 block_done, /* block flush performed */
69 finish_started, /* finish started, need only more output at next deflate */
70 finish_done /* finish done, accept no more input or output */
71 } block_state;
73 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74 /* Compression function. Returns the block state after the call. */
76 local void fill_window OF((deflate_state *s));
77 local block_state deflate_stored OF((deflate_state *s, int flush));
78 local block_state deflate_fast OF((deflate_state *s, int flush));
79 #ifndef FASTEST
80 local block_state deflate_slow OF((deflate_state *s, int flush));
81 #endif
82 local void lm_init OF((deflate_state *s));
83 local void putShortMSB OF((deflate_state *s, uInt b));
84 local void flush_pending OF((z_streamp strm));
85 local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
86 #ifndef FASTEST
87 #ifdef ASMV
88 void match_init OF((void)); /* asm code initialization */
89 uInt longest_match OF((deflate_state *s, IPos cur_match));
90 #else
91 local uInt longest_match OF((deflate_state *s, IPos cur_match));
92 #endif
93 #endif
94 local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
96 #ifdef DEBUG
97 local void check_match OF((deflate_state *s, IPos start, IPos match,
98 int length));
99 #endif
101 /* ===========================================================================
102 * Local data
105 #define NIL 0
106 /* Tail of hash chains */
108 #ifndef TOO_FAR
109 # define TOO_FAR 4096
110 #endif
111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
113 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
114 /* Minimum amount of lookahead, except at the end of the input file.
115 * See deflate.c for comments about the MIN_MATCH+1.
118 /* Values for max_lazy_match, good_match and max_chain_length, depending on
119 * the desired pack level (0..9). The values given below have been tuned to
120 * exclude worst case performance for pathological files. Better values may be
121 * found for specific files.
123 typedef struct config_s {
124 ush good_length; /* reduce lazy search above this match length */
125 ush max_lazy; /* do not perform lazy search above this match length */
126 ush nice_length; /* quit search above this match length */
127 ush max_chain;
128 compress_func func;
129 } config;
131 #ifdef FASTEST
132 local const config configuration_table[2] = {
133 /* good lazy nice chain */
134 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
135 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
136 #else
137 local const config configuration_table[10] = {
138 /* good lazy nice chain */
139 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
140 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
141 /* 2 */ {4, 5, 16, 8, deflate_fast},
142 /* 3 */ {4, 6, 32, 32, deflate_fast},
144 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
145 /* 5 */ {8, 16, 32, 32, deflate_slow},
146 /* 6 */ {8, 16, 128, 128, deflate_slow},
147 /* 7 */ {8, 32, 128, 256, deflate_slow},
148 /* 8 */ {32, 128, 258, 1024, deflate_slow},
149 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
150 #endif
152 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
153 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
154 * meaning.
157 #ifndef NO_DUMMY_DECL
158 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
159 #endif
161 /* ===========================================================================
162 * Update a hash value with the given input byte
163 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
164 * input characters, so that a running hash key can be computed from the
165 * previous key instead of complete recalculation each time.
167 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
170 /* ===========================================================================
171 * Insert string str in the dictionary and set match_head to the previous head
172 * of the hash chain (the most recent string with same hash key). Return
173 * the previous length of the hash chain.
174 * If this file is compiled with -DFASTEST, the compression level is forced
175 * to 1, and no hash chains are maintained.
176 * IN assertion: all calls to to INSERT_STRING are made with consecutive
177 * input characters and the first MIN_MATCH bytes of str are valid
178 * (except for the last MIN_MATCH-1 bytes of the input file).
180 #ifdef FASTEST
181 #define INSERT_STRING(s, str, match_head) \
182 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
183 match_head = s->head[s->ins_h], \
184 s->head[s->ins_h] = (Pos)(str))
185 #else
186 #define INSERT_STRING(s, str, match_head) \
187 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
188 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
189 s->head[s->ins_h] = (Pos)(str))
190 #endif
192 /* ===========================================================================
193 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
194 * prev[] will be initialized on the fly.
196 #define CLEAR_HASH(s) \
197 s->head[s->hash_size-1] = NIL; \
198 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
200 /* ========================================================================= */
201 int ZEXPORT deflateInit_(strm, level, version, stream_size)
202 z_streamp strm;
203 int level;
204 const char *version;
205 int stream_size;
207 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
208 Z_DEFAULT_STRATEGY, version, stream_size);
209 /* To do: ignore strm->next_in if we use it as window */
212 /* ========================================================================= */
213 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
214 version, stream_size)
215 z_streamp strm;
216 int level;
217 int method;
218 int windowBits;
219 int memLevel;
220 int strategy;
221 const char *version;
222 int stream_size;
224 deflate_state *s;
225 int wrap = 1;
226 static const char my_version[] = ZLIB_VERSION;
228 ushf *overlay;
229 /* We overlay pending_buf and d_buf+l_buf. This works since the average
230 * output size for (length,distance) codes is <= 24 bits.
233 if (version == Z_NULL || version[0] != my_version[0] ||
234 stream_size != sizeof(z_stream)) {
235 return Z_VERSION_ERROR;
237 if (strm == Z_NULL) return Z_STREAM_ERROR;
239 strm->msg = Z_NULL;
240 if (strm->zalloc == (alloc_func)0) {
241 strm->zalloc = zcalloc;
242 strm->opaque = (voidpf)0;
244 if (strm->zfree == (free_func)0) strm->zfree = zcfree;
246 #ifdef FASTEST
247 if (level != 0) level = 1;
248 #else
249 if (level == Z_DEFAULT_COMPRESSION) level = 6;
250 #endif
252 if (windowBits < 0) { /* suppress zlib wrapper */
253 wrap = 0;
254 windowBits = -windowBits;
256 #ifdef GZIP
257 else if (windowBits > 15) {
258 wrap = 2; /* write gzip wrapper instead */
259 windowBits -= 16;
261 #endif
262 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
263 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
264 strategy < 0 || strategy > Z_FIXED) {
265 return Z_STREAM_ERROR;
267 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
268 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
269 if (s == Z_NULL) return Z_MEM_ERROR;
270 strm->state = (struct internal_state FAR *)s;
271 s->strm = strm;
273 s->wrap = wrap;
274 s->gzhead = Z_NULL;
275 s->w_bits = windowBits;
276 s->w_size = 1 << s->w_bits;
277 s->w_mask = s->w_size - 1;
279 s->hash_bits = memLevel + 7;
280 s->hash_size = 1 << s->hash_bits;
281 s->hash_mask = s->hash_size - 1;
282 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
284 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
285 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
286 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
288 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
290 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
291 s->pending_buf = (uchf *) overlay;
292 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
294 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
295 s->pending_buf == Z_NULL) {
296 s->status = FINISH_STATE;
297 strm->msg = ERR_MSG(Z_MEM_ERROR);
298 deflateEnd (strm);
299 return Z_MEM_ERROR;
301 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
302 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
304 s->level = level;
305 s->strategy = strategy;
306 s->method = (Byte)method;
308 return deflateReset(strm);
311 /* ========================================================================= */
312 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
313 z_streamp strm;
314 const Bytef *dictionary;
315 uInt dictLength;
317 deflate_state *s;
318 uInt length = dictLength;
319 uInt n;
320 IPos hash_head = 0;
322 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
323 strm->state->wrap == 2 ||
324 (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
325 return Z_STREAM_ERROR;
327 s = strm->state;
328 if (s->wrap)
329 strm->adler = adler32(strm->adler, dictionary, dictLength);
331 if (length < MIN_MATCH) return Z_OK;
332 if (length > MAX_DIST(s)) {
333 length = MAX_DIST(s);
334 dictionary += dictLength - length; /* use the tail of the dictionary */
336 zmemcpy(s->window, dictionary, length);
337 s->strstart = length;
338 s->block_start = (long)length;
340 /* Insert all strings in the hash table (except for the last two bytes).
341 * s->lookahead stays null, so s->ins_h will be recomputed at the next
342 * call of fill_window.
344 s->ins_h = s->window[0];
345 UPDATE_HASH(s, s->ins_h, s->window[1]);
346 for (n = 0; n <= length - MIN_MATCH; n++) {
347 INSERT_STRING(s, n, hash_head);
349 if (hash_head) hash_head = 0; /* to make compiler happy */
350 return Z_OK;
353 /* ========================================================================= */
354 int ZEXPORT deflateReset (strm)
355 z_streamp strm;
357 deflate_state *s;
359 if (strm == Z_NULL || strm->state == Z_NULL ||
360 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
361 return Z_STREAM_ERROR;
364 strm->total_in = strm->total_out = 0;
365 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
366 strm->data_type = Z_UNKNOWN;
368 s = (deflate_state *)strm->state;
369 s->pending = 0;
370 s->pending_out = s->pending_buf;
372 if (s->wrap < 0) {
373 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
375 s->status = s->wrap ? INIT_STATE : BUSY_STATE;
376 strm->adler =
377 #ifdef GZIP
378 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
379 #endif
380 adler32(0L, Z_NULL, 0);
381 s->last_flush = Z_NO_FLUSH;
383 _tr_init(s);
384 lm_init(s);
386 return Z_OK;
389 /* ========================================================================= */
390 int ZEXPORT deflateSetHeader (strm, head)
391 z_streamp strm;
392 gz_headerp head;
394 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
395 if (strm->state->wrap != 2) return Z_STREAM_ERROR;
396 strm->state->gzhead = head;
397 return Z_OK;
400 /* ========================================================================= */
401 int ZEXPORT deflatePrime (strm, bits, value)
402 z_streamp strm;
403 int bits;
404 int value;
406 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
407 strm->state->bi_valid = bits;
408 strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
409 return Z_OK;
412 /* ========================================================================= */
413 int ZEXPORT deflateParams(strm, level, strategy)
414 z_streamp strm;
415 int level;
416 int strategy;
418 deflate_state *s;
419 compress_func func;
420 int err = Z_OK;
422 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
423 s = strm->state;
425 #ifdef FASTEST
426 if (level != 0) level = 1;
427 #else
428 if (level == Z_DEFAULT_COMPRESSION) level = 6;
429 #endif
430 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
431 return Z_STREAM_ERROR;
433 func = configuration_table[s->level].func;
435 if (func != configuration_table[level].func && strm->total_in != 0) {
436 /* Flush the last buffer: */
437 err = deflate(strm, Z_PARTIAL_FLUSH);
439 if (s->level != level) {
440 s->level = level;
441 s->max_lazy_match = configuration_table[level].max_lazy;
442 s->good_match = configuration_table[level].good_length;
443 s->nice_match = configuration_table[level].nice_length;
444 s->max_chain_length = configuration_table[level].max_chain;
446 s->strategy = strategy;
447 return err;
450 /* ========================================================================= */
451 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
452 z_streamp strm;
453 int good_length;
454 int max_lazy;
455 int nice_length;
456 int max_chain;
458 deflate_state *s;
460 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
461 s = strm->state;
462 s->good_match = good_length;
463 s->max_lazy_match = max_lazy;
464 s->nice_match = nice_length;
465 s->max_chain_length = max_chain;
466 return Z_OK;
469 /* =========================================================================
470 * For the default windowBits of 15 and memLevel of 8, this function returns
471 * a close to exact, as well as small, upper bound on the compressed size.
472 * They are coded as constants here for a reason--if the #define's are
473 * changed, then this function needs to be changed as well. The return
474 * value for 15 and 8 only works for those exact settings.
476 * For any setting other than those defaults for windowBits and memLevel,
477 * the value returned is a conservative worst case for the maximum expansion
478 * resulting from using fixed blocks instead of stored blocks, which deflate
479 * can emit on compressed data for some combinations of the parameters.
481 * This function could be more sophisticated to provide closer upper bounds
482 * for every combination of windowBits and memLevel, as well as wrap.
483 * But even the conservative upper bound of about 14% expansion does not
484 * seem onerous for output buffer allocation.
486 uLong ZEXPORT deflateBound(strm, sourceLen)
487 z_streamp strm;
488 uLong sourceLen;
490 deflate_state *s;
491 uLong destLen;
493 /* conservative upper bound */
494 destLen = sourceLen +
495 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
497 /* if can't get parameters, return conservative bound */
498 if (strm == Z_NULL || strm->state == Z_NULL)
499 return destLen;
501 /* if not default parameters, return conservative bound */
502 s = strm->state;
503 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
504 return destLen;
506 /* default settings: return tight bound for that case */
507 return compressBound(sourceLen);
510 /* =========================================================================
511 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
512 * IN assertion: the stream state is correct and there is enough room in
513 * pending_buf.
515 local void putShortMSB (s, b)
516 deflate_state *s;
517 uInt b;
519 put_byte(s, (Byte)(b >> 8));
520 put_byte(s, (Byte)(b & 0xff));
523 /* =========================================================================
524 * Flush as much pending output as possible. All deflate() output goes
525 * through this function so some applications may wish to modify it
526 * to avoid allocating a large strm->next_out buffer and copying into it.
527 * (See also read_buf()).
529 local void flush_pending(strm)
530 z_streamp strm;
532 unsigned len = strm->state->pending;
534 if (len > strm->avail_out) len = strm->avail_out;
535 if (len == 0) return;
537 zmemcpy(strm->next_out, strm->state->pending_out, len);
538 strm->next_out += len;
539 strm->state->pending_out += len;
540 strm->total_out += len;
541 strm->avail_out -= len;
542 strm->state->pending -= len;
543 if (strm->state->pending == 0) {
544 strm->state->pending_out = strm->state->pending_buf;
548 /* ========================================================================= */
549 int ZEXPORT deflate (strm, flush)
550 z_streamp strm;
551 int flush;
553 int old_flush; /* value of flush param for previous deflate call */
554 deflate_state *s;
556 if (strm == Z_NULL || strm->state == Z_NULL ||
557 flush > Z_FINISH || flush < 0) {
558 return Z_STREAM_ERROR;
560 s = strm->state;
562 if (strm->next_out == Z_NULL ||
563 (strm->next_in == Z_NULL && strm->avail_in != 0) ||
564 (s->status == FINISH_STATE && flush != Z_FINISH)) {
565 ERR_RETURN(strm, Z_STREAM_ERROR);
567 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
569 s->strm = strm; /* just in case */
570 old_flush = s->last_flush;
571 s->last_flush = flush;
573 /* Write the header */
574 if (s->status == INIT_STATE) {
575 #ifdef GZIP
576 if (s->wrap == 2) {
577 strm->adler = crc32(0L, Z_NULL, 0);
578 put_byte(s, 31);
579 put_byte(s, 139);
580 put_byte(s, 8);
581 if (s->gzhead == NULL) {
582 put_byte(s, 0);
583 put_byte(s, 0);
584 put_byte(s, 0);
585 put_byte(s, 0);
586 put_byte(s, 0);
587 put_byte(s, s->level == 9 ? 2 :
588 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
589 4 : 0));
590 put_byte(s, OS_CODE);
591 s->status = BUSY_STATE;
593 else {
594 put_byte(s, (s->gzhead->text ? 1 : 0) +
595 (s->gzhead->hcrc ? 2 : 0) +
596 (s->gzhead->extra == Z_NULL ? 0 : 4) +
597 (s->gzhead->name == Z_NULL ? 0 : 8) +
598 (s->gzhead->comment == Z_NULL ? 0 : 16)
600 put_byte(s, (Byte)(s->gzhead->time & 0xff));
601 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
602 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
603 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
604 put_byte(s, s->level == 9 ? 2 :
605 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
606 4 : 0));
607 put_byte(s, s->gzhead->os & 0xff);
608 if (s->gzhead->extra != NULL) {
609 put_byte(s, s->gzhead->extra_len & 0xff);
610 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
612 if (s->gzhead->hcrc)
613 strm->adler = crc32(strm->adler, s->pending_buf,
614 s->pending);
615 s->gzindex = 0;
616 s->status = EXTRA_STATE;
619 else
620 #endif
622 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
623 uInt level_flags;
625 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
626 level_flags = 0;
627 else if (s->level < 6)
628 level_flags = 1;
629 else if (s->level == 6)
630 level_flags = 2;
631 else
632 level_flags = 3;
633 header |= (level_flags << 6);
634 if (s->strstart != 0) header |= PRESET_DICT;
635 header += 31 - (header % 31);
637 s->status = BUSY_STATE;
638 putShortMSB(s, header);
640 /* Save the adler32 of the preset dictionary: */
641 if (s->strstart != 0) {
642 putShortMSB(s, (uInt)(strm->adler >> 16));
643 putShortMSB(s, (uInt)(strm->adler & 0xffff));
645 strm->adler = adler32(0L, Z_NULL, 0);
648 #ifdef GZIP
649 if (s->status == EXTRA_STATE) {
650 if (s->gzhead->extra != NULL) {
651 uInt beg = s->pending; /* start of bytes to update crc */
653 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
654 if (s->pending == s->pending_buf_size) {
655 if (s->gzhead->hcrc && s->pending > beg)
656 strm->adler = crc32(strm->adler, s->pending_buf + beg,
657 s->pending - beg);
658 flush_pending(strm);
659 beg = s->pending;
660 if (s->pending == s->pending_buf_size)
661 break;
663 put_byte(s, s->gzhead->extra[s->gzindex]);
664 s->gzindex++;
666 if (s->gzhead->hcrc && s->pending > beg)
667 strm->adler = crc32(strm->adler, s->pending_buf + beg,
668 s->pending - beg);
669 if (s->gzindex == s->gzhead->extra_len) {
670 s->gzindex = 0;
671 s->status = NAME_STATE;
674 else
675 s->status = NAME_STATE;
677 if (s->status == NAME_STATE) {
678 if (s->gzhead->name != NULL) {
679 uInt beg = s->pending; /* start of bytes to update crc */
680 int val;
682 do {
683 if (s->pending == s->pending_buf_size) {
684 if (s->gzhead->hcrc && s->pending > beg)
685 strm->adler = crc32(strm->adler, s->pending_buf + beg,
686 s->pending - beg);
687 flush_pending(strm);
688 beg = s->pending;
689 if (s->pending == s->pending_buf_size) {
690 val = 1;
691 break;
694 val = s->gzhead->name[s->gzindex++];
695 put_byte(s, val);
696 } while (val != 0);
697 if (s->gzhead->hcrc && s->pending > beg)
698 strm->adler = crc32(strm->adler, s->pending_buf + beg,
699 s->pending - beg);
700 if (val == 0) {
701 s->gzindex = 0;
702 s->status = COMMENT_STATE;
705 else
706 s->status = COMMENT_STATE;
708 if (s->status == COMMENT_STATE) {
709 if (s->gzhead->comment != NULL) {
710 uInt beg = s->pending; /* start of bytes to update crc */
711 int val;
713 do {
714 if (s->pending == s->pending_buf_size) {
715 if (s->gzhead->hcrc && s->pending > beg)
716 strm->adler = crc32(strm->adler, s->pending_buf + beg,
717 s->pending - beg);
718 flush_pending(strm);
719 beg = s->pending;
720 if (s->pending == s->pending_buf_size) {
721 val = 1;
722 break;
725 val = s->gzhead->comment[s->gzindex++];
726 put_byte(s, val);
727 } while (val != 0);
728 if (s->gzhead->hcrc && s->pending > beg)
729 strm->adler = crc32(strm->adler, s->pending_buf + beg,
730 s->pending - beg);
731 if (val == 0)
732 s->status = HCRC_STATE;
734 else
735 s->status = HCRC_STATE;
737 if (s->status == HCRC_STATE) {
738 if (s->gzhead->hcrc) {
739 if (s->pending + 2 > s->pending_buf_size)
740 flush_pending(strm);
741 if (s->pending + 2 <= s->pending_buf_size) {
742 put_byte(s, (Byte)(strm->adler & 0xff));
743 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
744 strm->adler = crc32(0L, Z_NULL, 0);
745 s->status = BUSY_STATE;
748 else
749 s->status = BUSY_STATE;
751 #endif
753 /* Flush as much pending output as possible */
754 if (s->pending != 0) {
755 flush_pending(strm);
756 if (strm->avail_out == 0) {
757 /* Since avail_out is 0, deflate will be called again with
758 * more output space, but possibly with both pending and
759 * avail_in equal to zero. There won't be anything to do,
760 * but this is not an error situation so make sure we
761 * return OK instead of BUF_ERROR at next call of deflate:
763 s->last_flush = -1;
764 return Z_OK;
767 /* Make sure there is something to do and avoid duplicate consecutive
768 * flushes. For repeated and useless calls with Z_FINISH, we keep
769 * returning Z_STREAM_END instead of Z_BUF_ERROR.
771 } else if (strm->avail_in == 0 && flush <= old_flush &&
772 flush != Z_FINISH) {
773 ERR_RETURN(strm, Z_BUF_ERROR);
776 /* User must not provide more input after the first FINISH: */
777 if (s->status == FINISH_STATE && strm->avail_in != 0) {
778 ERR_RETURN(strm, Z_BUF_ERROR);
781 /* Start a new block or continue the current one.
783 if (strm->avail_in != 0 || s->lookahead != 0 ||
784 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
785 block_state bstate;
787 bstate = (*(configuration_table[s->level].func))(s, flush);
789 if (bstate == finish_started || bstate == finish_done) {
790 s->status = FINISH_STATE;
792 if (bstate == need_more || bstate == finish_started) {
793 if (strm->avail_out == 0) {
794 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
796 return Z_OK;
797 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
798 * of deflate should use the same flush parameter to make sure
799 * that the flush is complete. So we don't have to output an
800 * empty block here, this will be done at next call. This also
801 * ensures that for a very small output buffer, we emit at most
802 * one empty block.
805 if (bstate == block_done) {
806 if (flush == Z_PARTIAL_FLUSH) {
807 _tr_align(s);
808 } else { /* FULL_FLUSH or SYNC_FLUSH */
809 _tr_stored_block(s, (char*)0, 0L, 0);
810 /* For a full flush, this empty block will be recognized
811 * as a special marker by inflate_sync().
813 if (flush == Z_FULL_FLUSH) {
814 CLEAR_HASH(s); /* forget history */
817 flush_pending(strm);
818 if (strm->avail_out == 0) {
819 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
820 return Z_OK;
824 Assert(strm->avail_out > 0, "bug2");
826 if (flush != Z_FINISH) return Z_OK;
827 if (s->wrap <= 0) return Z_STREAM_END;
829 /* Write the trailer */
830 #ifdef GZIP
831 if (s->wrap == 2) {
832 put_byte(s, (Byte)(strm->adler & 0xff));
833 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
834 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
835 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
836 put_byte(s, (Byte)(strm->total_in & 0xff));
837 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
838 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
839 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
841 else
842 #endif
844 putShortMSB(s, (uInt)(strm->adler >> 16));
845 putShortMSB(s, (uInt)(strm->adler & 0xffff));
847 flush_pending(strm);
848 /* If avail_out is zero, the application will call deflate again
849 * to flush the rest.
851 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
852 return s->pending != 0 ? Z_OK : Z_STREAM_END;
855 /* ========================================================================= */
856 int ZEXPORT deflateEnd (strm)
857 z_streamp strm;
859 int status;
861 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
863 status = strm->state->status;
864 if (status != INIT_STATE &&
865 status != EXTRA_STATE &&
866 status != NAME_STATE &&
867 status != COMMENT_STATE &&
868 status != HCRC_STATE &&
869 status != BUSY_STATE &&
870 status != FINISH_STATE) {
871 return Z_STREAM_ERROR;
874 /* Deallocate in reverse order of allocations: */
875 TRY_FREE(strm, strm->state->pending_buf);
876 TRY_FREE(strm, strm->state->head);
877 TRY_FREE(strm, strm->state->prev);
878 TRY_FREE(strm, strm->state->window);
880 ZFREE(strm, strm->state);
881 strm->state = Z_NULL;
883 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
886 /* =========================================================================
887 * Copy the source state to the destination state.
888 * To simplify the source, this is not supported for 16-bit MSDOS (which
889 * doesn't have enough memory anyway to duplicate compression states).
891 int ZEXPORT deflateCopy (dest, source)
892 z_streamp dest;
893 z_streamp source;
895 #ifdef MAXSEG_64K
896 return Z_STREAM_ERROR;
897 #else
898 deflate_state *ds;
899 deflate_state *ss;
900 ushf *overlay;
903 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
904 return Z_STREAM_ERROR;
907 ss = source->state;
909 zmemcpy(dest, source, sizeof(z_stream));
911 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
912 if (ds == Z_NULL) return Z_MEM_ERROR;
913 dest->state = (struct internal_state FAR *) ds;
914 zmemcpy(ds, ss, sizeof(deflate_state));
915 ds->strm = dest;
917 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
918 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
919 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
920 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
921 ds->pending_buf = (uchf *) overlay;
923 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
924 ds->pending_buf == Z_NULL) {
925 deflateEnd (dest);
926 return Z_MEM_ERROR;
928 /* following zmemcpy do not work for 16-bit MSDOS */
929 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
930 zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
931 zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
932 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
934 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
935 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
936 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
938 ds->l_desc.dyn_tree = ds->dyn_ltree;
939 ds->d_desc.dyn_tree = ds->dyn_dtree;
940 ds->bl_desc.dyn_tree = ds->bl_tree;
942 return Z_OK;
943 #endif /* MAXSEG_64K */
946 /* ===========================================================================
947 * Read a new buffer from the current input stream, update the adler32
948 * and total number of bytes read. All deflate() input goes through
949 * this function so some applications may wish to modify it to avoid
950 * allocating a large strm->next_in buffer and copying from it.
951 * (See also flush_pending()).
953 local int read_buf(strm, buf, size)
954 z_streamp strm;
955 Bytef *buf;
956 unsigned size;
958 unsigned len = strm->avail_in;
960 if (len > size) len = size;
961 if (len == 0) return 0;
963 strm->avail_in -= len;
965 if (strm->state->wrap == 1) {
966 strm->adler = adler32(strm->adler, strm->next_in, len);
968 #ifdef GZIP
969 else if (strm->state->wrap == 2) {
970 strm->adler = crc32(strm->adler, strm->next_in, len);
972 #endif
973 zmemcpy(buf, strm->next_in, len);
974 strm->next_in += len;
975 strm->total_in += len;
977 return (int)len;
980 /* ===========================================================================
981 * Initialize the "longest match" routines for a new zlib stream
983 local void lm_init (s)
984 deflate_state *s;
986 s->window_size = (ulg)2L*s->w_size;
988 CLEAR_HASH(s);
990 /* Set the default configuration parameters:
992 s->max_lazy_match = configuration_table[s->level].max_lazy;
993 s->good_match = configuration_table[s->level].good_length;
994 s->nice_match = configuration_table[s->level].nice_length;
995 s->max_chain_length = configuration_table[s->level].max_chain;
997 s->strstart = 0;
998 s->block_start = 0L;
999 s->lookahead = 0;
1000 s->match_length = s->prev_length = MIN_MATCH-1;
1001 s->match_available = 0;
1002 s->ins_h = 0;
1003 #ifndef FASTEST
1004 #ifdef ASMV
1005 match_init(); /* initialize the asm code */
1006 #endif
1007 #endif
1010 #ifndef FASTEST
1011 /* ===========================================================================
1012 * Set match_start to the longest match starting at the given string and
1013 * return its length. Matches shorter or equal to prev_length are discarded,
1014 * in which case the result is equal to prev_length and match_start is
1015 * garbage.
1016 * IN assertions: cur_match is the head of the hash chain for the current
1017 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1018 * OUT assertion: the match length is not greater than s->lookahead.
1020 #ifndef ASMV
1021 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1022 * match.S. The code will be functionally equivalent.
1024 local uInt longest_match(s, cur_match)
1025 deflate_state *s;
1026 IPos cur_match; /* current match */
1028 unsigned chain_length = s->max_chain_length;/* max hash chain length */
1029 register Bytef *scan = s->window + s->strstart; /* current string */
1030 register Bytef *match; /* matched string */
1031 register int len; /* length of current match */
1032 int best_len = s->prev_length; /* best match length so far */
1033 int nice_match = s->nice_match; /* stop if match long enough */
1034 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1035 s->strstart - (IPos)MAX_DIST(s) : NIL;
1036 /* Stop when cur_match becomes <= limit. To simplify the code,
1037 * we prevent matches with the string of window index 0.
1039 Posf *prev = s->prev;
1040 uInt wmask = s->w_mask;
1042 #ifdef UNALIGNED_OK
1043 /* Compare two bytes at a time. Note: this is not always beneficial.
1044 * Try with and without -DUNALIGNED_OK to check.
1046 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1047 register ush scan_start = *(ushf*)scan;
1048 register ush scan_end = *(ushf*)(scan+best_len-1);
1049 #else
1050 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1051 register Byte scan_end1 = scan[best_len-1];
1052 register Byte scan_end = scan[best_len];
1053 #endif
1055 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1056 * It is easy to get rid of this optimization if necessary.
1058 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1060 /* Do not waste too much time if we already have a good match: */
1061 if (s->prev_length >= s->good_match) {
1062 chain_length >>= 2;
1064 /* Do not look for matches beyond the end of the input. This is necessary
1065 * to make deflate deterministic.
1067 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1069 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1071 do {
1072 Assert(cur_match < s->strstart, "no future");
1073 match = s->window + cur_match;
1075 /* Skip to next match if the match length cannot increase
1076 * or if the match length is less than 2. Note that the checks below
1077 * for insufficient lookahead only occur occasionally for performance
1078 * reasons. Therefore uninitialized memory will be accessed, and
1079 * conditional jumps will be made that depend on those values.
1080 * However the length of the match is limited to the lookahead, so
1081 * the output of deflate is not affected by the uninitialized values.
1083 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1084 /* This code assumes sizeof(unsigned short) == 2. Do not use
1085 * UNALIGNED_OK if your compiler uses a different size.
1087 if (*(ushf*)(match+best_len-1) != scan_end ||
1088 *(ushf*)match != scan_start) continue;
1090 /* It is not necessary to compare scan[2] and match[2] since they are
1091 * always equal when the other bytes match, given that the hash keys
1092 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1093 * strstart+3, +5, ... up to strstart+257. We check for insufficient
1094 * lookahead only every 4th comparison; the 128th check will be made
1095 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1096 * necessary to put more guard bytes at the end of the window, or
1097 * to check more often for insufficient lookahead.
1099 Assert(scan[2] == match[2], "scan[2]?");
1100 scan++, match++;
1101 do {
1102 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1103 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1104 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1105 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1106 scan < strend);
1107 /* The funny "do {}" generates better code on most compilers */
1109 /* Here, scan <= window+strstart+257 */
1110 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1111 if (*scan == *match) scan++;
1113 len = (MAX_MATCH - 1) - (int)(strend-scan);
1114 scan = strend - (MAX_MATCH-1);
1116 #else /* UNALIGNED_OK */
1118 if (match[best_len] != scan_end ||
1119 match[best_len-1] != scan_end1 ||
1120 *match != *scan ||
1121 *++match != scan[1]) continue;
1123 /* The check at best_len-1 can be removed because it will be made
1124 * again later. (This heuristic is not always a win.)
1125 * It is not necessary to compare scan[2] and match[2] since they
1126 * are always equal when the other bytes match, given that
1127 * the hash keys are equal and that HASH_BITS >= 8.
1129 scan += 2, match++;
1130 Assert(*scan == *match, "match[2]?");
1132 /* We check for insufficient lookahead only every 8th comparison;
1133 * the 256th check will be made at strstart+258.
1135 do {
1136 } while (*++scan == *++match && *++scan == *++match &&
1137 *++scan == *++match && *++scan == *++match &&
1138 *++scan == *++match && *++scan == *++match &&
1139 *++scan == *++match && *++scan == *++match &&
1140 scan < strend);
1142 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1144 len = MAX_MATCH - (int)(strend - scan);
1145 scan = strend - MAX_MATCH;
1147 #endif /* UNALIGNED_OK */
1149 if (len > best_len) {
1150 s->match_start = cur_match;
1151 best_len = len;
1152 if (len >= nice_match) break;
1153 #ifdef UNALIGNED_OK
1154 scan_end = *(ushf*)(scan+best_len-1);
1155 #else
1156 scan_end1 = scan[best_len-1];
1157 scan_end = scan[best_len];
1158 #endif
1160 } while ((cur_match = prev[cur_match & wmask]) > limit
1161 && --chain_length != 0);
1163 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1164 return s->lookahead;
1166 #endif /* ASMV */
1167 #endif /* FASTEST */
1169 /* ---------------------------------------------------------------------------
1170 * Optimized version for level == 1 or strategy == Z_RLE only
1172 local uInt longest_match_fast(s, cur_match)
1173 deflate_state *s;
1174 IPos cur_match; /* current match */
1176 register Bytef *scan = s->window + s->strstart; /* current string */
1177 register Bytef *match; /* matched string */
1178 register int len; /* length of current match */
1179 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1181 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1182 * It is easy to get rid of this optimization if necessary.
1184 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1186 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1188 Assert(cur_match < s->strstart, "no future");
1190 match = s->window + cur_match;
1192 /* Return failure if the match length is less than 2:
1194 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1196 /* The check at best_len-1 can be removed because it will be made
1197 * again later. (This heuristic is not always a win.)
1198 * It is not necessary to compare scan[2] and match[2] since they
1199 * are always equal when the other bytes match, given that
1200 * the hash keys are equal and that HASH_BITS >= 8.
1202 scan += 2, match += 2;
1203 Assert(*scan == *match, "match[2]?");
1205 /* We check for insufficient lookahead only every 8th comparison;
1206 * the 256th check will be made at strstart+258.
1208 do {
1209 } while (*++scan == *++match && *++scan == *++match &&
1210 *++scan == *++match && *++scan == *++match &&
1211 *++scan == *++match && *++scan == *++match &&
1212 *++scan == *++match && *++scan == *++match &&
1213 scan < strend);
1215 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1217 len = MAX_MATCH - (int)(strend - scan);
1219 if (len < MIN_MATCH) return MIN_MATCH - 1;
1221 s->match_start = cur_match;
1222 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1225 #ifdef DEBUG
1226 #define EQUAL 0
1227 /* result of memcmp for equal strings */
1229 /* ===========================================================================
1230 * Check that the match at match_start is indeed a match.
1232 local void check_match(s, start, match, length)
1233 deflate_state *s;
1234 IPos start, match;
1235 int length;
1237 /* check that the match is indeed a match */
1238 if (zmemcmp(s->window + match,
1239 s->window + start, length) != EQUAL) {
1240 fprintf(stderr, " start %u, match %u, length %d\n",
1241 start, match, length);
1242 do {
1243 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1244 } while (--length != 0);
1245 z_error("invalid match");
1247 if (z_verbose > 1) {
1248 fprintf(stderr,"\\[%d,%d]", start-match, length);
1249 do { putc(s->window[start++], stderr); } while (--length != 0);
1252 #else
1253 # define check_match(s, start, match, length)
1254 #endif /* DEBUG */
1256 /* ===========================================================================
1257 * Fill the window when the lookahead becomes insufficient.
1258 * Updates strstart and lookahead.
1260 * IN assertion: lookahead < MIN_LOOKAHEAD
1261 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1262 * At least one byte has been read, or avail_in == 0; reads are
1263 * performed for at least two bytes (required for the zip translate_eol
1264 * option -- not supported here).
1266 local void fill_window(s)
1267 deflate_state *s;
1269 register unsigned n, m;
1270 register Posf *p;
1271 unsigned more; /* Amount of free space at the end of the window. */
1272 uInt wsize = s->w_size;
1274 do {
1275 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1277 /* Deal with !@#$% 64K limit: */
1278 if (sizeof(int) <= 2) {
1279 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1280 more = wsize;
1282 } else if (more == (unsigned)(-1)) {
1283 /* Very unlikely, but possible on 16 bit machine if
1284 * strstart == 0 && lookahead == 1 (input done a byte at time)
1286 more--;
1290 /* If the window is almost full and there is insufficient lookahead,
1291 * move the upper half to the lower one to make room in the upper half.
1293 if (s->strstart >= wsize+MAX_DIST(s)) {
1295 zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1296 s->match_start -= wsize;
1297 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1298 s->block_start -= (long) wsize;
1300 /* Slide the hash table (could be avoided with 32 bit values
1301 at the expense of memory usage). We slide even when level == 0
1302 to keep the hash table consistent if we switch back to level > 0
1303 later. (Using level 0 permanently is not an optimal usage of
1304 zlib, so we don't care about this pathological case.)
1306 /* %%% avoid this when Z_RLE */
1307 n = s->hash_size;
1308 p = &s->head[n];
1309 do {
1310 m = *--p;
1311 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1312 } while (--n);
1314 n = wsize;
1315 #ifndef FASTEST
1316 p = &s->prev[n];
1317 do {
1318 m = *--p;
1319 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1320 /* If n is not on any hash chain, prev[n] is garbage but
1321 * its value will never be used.
1323 } while (--n);
1324 #endif
1325 more += wsize;
1327 if (s->strm->avail_in == 0) return;
1329 /* If there was no sliding:
1330 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1331 * more == window_size - lookahead - strstart
1332 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1333 * => more >= window_size - 2*WSIZE + 2
1334 * In the BIG_MEM or MMAP case (not yet supported),
1335 * window_size == input_size + MIN_LOOKAHEAD &&
1336 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1337 * Otherwise, window_size == 2*WSIZE so more >= 2.
1338 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1340 Assert(more >= 2, "more < 2");
1342 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1343 s->lookahead += n;
1345 /* Initialize the hash value now that we have some input: */
1346 if (s->lookahead >= MIN_MATCH) {
1347 s->ins_h = s->window[s->strstart];
1348 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1349 #if MIN_MATCH != 3
1350 Call UPDATE_HASH() MIN_MATCH-3 more times
1351 #endif
1353 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1354 * but this is not important since only literal bytes will be emitted.
1357 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1360 /* ===========================================================================
1361 * Flush the current block, with given end-of-file flag.
1362 * IN assertion: strstart is set to the end of the current match.
1364 #define FLUSH_BLOCK_ONLY(s, eof) { \
1365 _tr_flush_block(s, (s->block_start >= 0L ? \
1366 (charf *)&s->window[(unsigned)s->block_start] : \
1367 (charf *)Z_NULL), \
1368 (ulg)((long)s->strstart - s->block_start), \
1369 (eof)); \
1370 s->block_start = s->strstart; \
1371 flush_pending(s->strm); \
1372 Tracev((stderr,"[FLUSH]")); \
1375 /* Same but force premature exit if necessary. */
1376 #define FLUSH_BLOCK(s, eof) { \
1377 FLUSH_BLOCK_ONLY(s, eof); \
1378 if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1381 /* ===========================================================================
1382 * Copy without compression as much as possible from the input stream, return
1383 * the current block state.
1384 * This function does not insert new strings in the dictionary since
1385 * uncompressible data is probably not useful. This function is used
1386 * only for the level=0 compression option.
1387 * NOTE: this function should be optimized to avoid extra copying from
1388 * window to pending_buf.
1390 local block_state deflate_stored(s, flush)
1391 deflate_state *s;
1392 int flush;
1394 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1395 * to pending_buf_size, and each stored block has a 5 byte header:
1397 ulg max_block_size = 0xffff;
1398 ulg max_start;
1400 if (max_block_size > s->pending_buf_size - 5) {
1401 max_block_size = s->pending_buf_size - 5;
1404 /* Copy as much as possible from input to output: */
1405 for (;;) {
1406 /* Fill the window as much as possible: */
1407 if (s->lookahead <= 1) {
1409 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1410 s->block_start >= (long)s->w_size, "slide too late");
1412 fill_window(s);
1413 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1415 if (s->lookahead == 0) break; /* flush the current block */
1417 Assert(s->block_start >= 0L, "block gone");
1419 s->strstart += s->lookahead;
1420 s->lookahead = 0;
1422 /* Emit a stored block if pending_buf will be full: */
1423 max_start = s->block_start + max_block_size;
1424 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1425 /* strstart == 0 is possible when wraparound on 16-bit machine */
1426 s->lookahead = (uInt)(s->strstart - max_start);
1427 s->strstart = (uInt)max_start;
1428 FLUSH_BLOCK(s, 0);
1430 /* Flush if we may have to slide, otherwise block_start may become
1431 * negative and the data will be gone:
1433 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1434 FLUSH_BLOCK(s, 0);
1437 FLUSH_BLOCK(s, flush == Z_FINISH);
1438 return flush == Z_FINISH ? finish_done : block_done;
1441 /* ===========================================================================
1442 * Compress as much as possible from the input stream, return the current
1443 * block state.
1444 * This function does not perform lazy evaluation of matches and inserts
1445 * new strings in the dictionary only for unmatched strings or for short
1446 * matches. It is used only for the fast compression options.
1448 local block_state deflate_fast(s, flush)
1449 deflate_state *s;
1450 int flush;
1452 IPos hash_head = NIL; /* head of the hash chain */
1453 int bflush; /* set if current block must be flushed */
1455 for (;;) {
1456 /* Make sure that we always have enough lookahead, except
1457 * at the end of the input file. We need MAX_MATCH bytes
1458 * for the next match, plus MIN_MATCH bytes to insert the
1459 * string following the next match.
1461 if (s->lookahead < MIN_LOOKAHEAD) {
1462 fill_window(s);
1463 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1464 return need_more;
1466 if (s->lookahead == 0) break; /* flush the current block */
1469 /* Insert the string window[strstart .. strstart+2] in the
1470 * dictionary, and set hash_head to the head of the hash chain:
1472 if (s->lookahead >= MIN_MATCH) {
1473 INSERT_STRING(s, s->strstart, hash_head);
1476 /* Find the longest match, discarding those <= prev_length.
1477 * At this point we have always match_length < MIN_MATCH
1479 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1480 /* To simplify the code, we prevent matches with the string
1481 * of window index 0 (in particular we have to avoid a match
1482 * of the string with itself at the start of the input file).
1484 #ifdef FASTEST
1485 if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) ||
1486 (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
1487 s->match_length = longest_match_fast (s, hash_head);
1489 #else
1490 if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1491 s->match_length = longest_match (s, hash_head);
1492 } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1493 s->match_length = longest_match_fast (s, hash_head);
1495 #endif
1496 /* longest_match() or longest_match_fast() sets match_start */
1498 if (s->match_length >= MIN_MATCH) {
1499 check_match(s, s->strstart, s->match_start, s->match_length);
1501 _tr_tally_dist(s, s->strstart - s->match_start,
1502 s->match_length - MIN_MATCH, bflush);
1504 s->lookahead -= s->match_length;
1506 /* Insert new strings in the hash table only if the match length
1507 * is not too large. This saves time but degrades compression.
1509 #ifndef FASTEST
1510 if (s->match_length <= s->max_insert_length &&
1511 s->lookahead >= MIN_MATCH) {
1512 s->match_length--; /* string at strstart already in table */
1513 do {
1514 s->strstart++;
1515 INSERT_STRING(s, s->strstart, hash_head);
1516 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1517 * always MIN_MATCH bytes ahead.
1519 } while (--s->match_length != 0);
1520 s->strstart++;
1521 } else
1522 #endif
1524 s->strstart += s->match_length;
1525 s->match_length = 0;
1526 s->ins_h = s->window[s->strstart];
1527 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1528 #if MIN_MATCH != 3
1529 Call UPDATE_HASH() MIN_MATCH-3 more times
1530 #endif
1531 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1532 * matter since it will be recomputed at next deflate call.
1535 } else {
1536 /* No match, output a literal byte */
1537 Tracevv((stderr,"%c", s->window[s->strstart]));
1538 _tr_tally_lit (s, s->window[s->strstart], bflush);
1539 s->lookahead--;
1540 s->strstart++;
1542 if (bflush) FLUSH_BLOCK(s, 0);
1544 FLUSH_BLOCK(s, flush == Z_FINISH);
1545 return flush == Z_FINISH ? finish_done : block_done;
1548 #ifndef FASTEST
1549 /* ===========================================================================
1550 * Same as above, but achieves better compression. We use a lazy
1551 * evaluation for matches: a match is finally adopted only if there is
1552 * no better match at the next window position.
1554 local block_state deflate_slow(s, flush)
1555 deflate_state *s;
1556 int flush;
1558 IPos hash_head = NIL; /* head of hash chain */
1559 int bflush; /* set if current block must be flushed */
1561 /* Process the input block. */
1562 for (;;) {
1563 /* Make sure that we always have enough lookahead, except
1564 * at the end of the input file. We need MAX_MATCH bytes
1565 * for the next match, plus MIN_MATCH bytes to insert the
1566 * string following the next match.
1568 if (s->lookahead < MIN_LOOKAHEAD) {
1569 fill_window(s);
1570 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1571 return need_more;
1573 if (s->lookahead == 0) break; /* flush the current block */
1576 /* Insert the string window[strstart .. strstart+2] in the
1577 * dictionary, and set hash_head to the head of the hash chain:
1579 if (s->lookahead >= MIN_MATCH) {
1580 INSERT_STRING(s, s->strstart, hash_head);
1583 /* Find the longest match, discarding those <= prev_length.
1585 s->prev_length = s->match_length, s->prev_match = s->match_start;
1586 s->match_length = MIN_MATCH-1;
1588 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1589 s->strstart - hash_head <= MAX_DIST(s)) {
1590 /* To simplify the code, we prevent matches with the string
1591 * of window index 0 (in particular we have to avoid a match
1592 * of the string with itself at the start of the input file).
1594 if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1595 s->match_length = longest_match (s, hash_head);
1596 } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1597 s->match_length = longest_match_fast (s, hash_head);
1599 /* longest_match() or longest_match_fast() sets match_start */
1601 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1602 #if TOO_FAR <= 32767
1603 || (s->match_length == MIN_MATCH &&
1604 s->strstart - s->match_start > TOO_FAR)
1605 #endif
1606 )) {
1608 /* If prev_match is also MIN_MATCH, match_start is garbage
1609 * but we will ignore the current match anyway.
1611 s->match_length = MIN_MATCH-1;
1614 /* If there was a match at the previous step and the current
1615 * match is not better, output the previous match:
1617 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1618 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1619 /* Do not insert strings in hash table beyond this. */
1621 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1623 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1624 s->prev_length - MIN_MATCH, bflush);
1626 /* Insert in hash table all strings up to the end of the match.
1627 * strstart-1 and strstart are already inserted. If there is not
1628 * enough lookahead, the last two strings are not inserted in
1629 * the hash table.
1631 s->lookahead -= s->prev_length-1;
1632 s->prev_length -= 2;
1633 do {
1634 if (++s->strstart <= max_insert) {
1635 INSERT_STRING(s, s->strstart, hash_head);
1637 } while (--s->prev_length != 0);
1638 s->match_available = 0;
1639 s->match_length = MIN_MATCH-1;
1640 s->strstart++;
1642 if (bflush) FLUSH_BLOCK(s, 0);
1644 } else if (s->match_available) {
1645 /* If there was no match at the previous position, output a
1646 * single literal. If there was a match but the current match
1647 * is longer, truncate the previous match to a single literal.
1649 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1650 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1651 if (bflush) {
1652 FLUSH_BLOCK_ONLY(s, 0);
1654 s->strstart++;
1655 s->lookahead--;
1656 if (s->strm->avail_out == 0) return need_more;
1657 } else {
1658 /* There is no previous match to compare with, wait for
1659 * the next step to decide.
1661 s->match_available = 1;
1662 s->strstart++;
1663 s->lookahead--;
1666 Assert (flush != Z_NO_FLUSH, "no flush?");
1667 if (s->match_available) {
1668 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1669 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1670 s->match_available = 0;
1672 FLUSH_BLOCK(s, flush == Z_FINISH);
1673 return flush == Z_FINISH ? finish_done : block_done;
1675 #endif /* FASTEST */
1677 #if 0
1678 /* ===========================================================================
1679 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1680 * one. Do not maintain a hash table. (It will be regenerated if this run of
1681 * deflate switches away from Z_RLE.)
1683 local block_state deflate_rle(s, flush)
1684 deflate_state *s;
1685 int flush;
1687 int bflush; /* set if current block must be flushed */
1688 uInt run; /* length of run */
1689 uInt max; /* maximum length of run */
1690 uInt prev; /* byte at distance one to match */
1691 Bytef *scan; /* scan for end of run */
1693 for (;;) {
1694 /* Make sure that we always have enough lookahead, except
1695 * at the end of the input file. We need MAX_MATCH bytes
1696 * for the longest encodable run.
1698 if (s->lookahead < MAX_MATCH) {
1699 fill_window(s);
1700 if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {
1701 return need_more;
1703 if (s->lookahead == 0) break; /* flush the current block */
1706 /* See how many times the previous byte repeats */
1707 run = 0;
1708 if (s->strstart > 0) { /* if there is a previous byte, that is */
1709 max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH;
1710 scan = s->window + s->strstart - 1;
1711 prev = *scan++;
1712 do {
1713 if (*scan++ != prev)
1714 break;
1715 } while (++run < max);
1718 /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1719 if (run >= MIN_MATCH) {
1720 check_match(s, s->strstart, s->strstart - 1, run);
1721 _tr_tally_dist(s, 1, run - MIN_MATCH, bflush);
1722 s->lookahead -= run;
1723 s->strstart += run;
1724 } else {
1725 /* No match, output a literal byte */
1726 Tracevv((stderr,"%c", s->window[s->strstart]));
1727 _tr_tally_lit (s, s->window[s->strstart], bflush);
1728 s->lookahead--;
1729 s->strstart++;
1731 if (bflush) FLUSH_BLOCK(s, 0);
1733 FLUSH_BLOCK(s, flush == Z_FINISH);
1734 return flush == Z_FINISH ? finish_done : block_done;
1736 #endif