Mercurial > hg > CbC > CbC_gcc
comparison zlib/deflate.c @ 51:ae3a4bfb450b
add some files of version 4.4.3 that have been forgotten.
author | kent <kent@cr.ie.u-ryukyu.ac.jp> |
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date | Sun, 07 Feb 2010 18:27:48 +0900 |
parents | |
children | 04ced10e8804 |
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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 */ | |
5 | |
6 /* | |
7 * ALGORITHM | |
8 * | |
9 * The "deflation" process depends on being able to identify portions | |
10 * of the input text which are identical to earlier input (within a | |
11 * sliding window trailing behind the input currently being processed). | |
12 * | |
13 * The most straightforward technique turns out to be the fastest for | |
14 * most input files: try all possible matches and select the longest. | |
15 * The key feature of this algorithm is that insertions into the string | |
16 * dictionary are very simple and thus fast, and deletions are avoided | |
17 * completely. Insertions are performed at each input character, whereas | |
18 * string matches are performed only when the previous match ends. So it | |
19 * is preferable to spend more time in matches to allow very fast string | |
20 * insertions and avoid deletions. The matching algorithm for small | |
21 * strings is inspired from that of Rabin & Karp. A brute force approach | |
22 * is used to find longer strings when a small match has been found. | |
23 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze | |
24 * (by Leonid Broukhis). | |
25 * A previous version of this file used a more sophisticated algorithm | |
26 * (by Fiala and Greene) which is guaranteed to run in linear amortized | |
27 * time, but has a larger average cost, uses more memory and is patented. | |
28 * However the F&G algorithm may be faster for some highly redundant | |
29 * files if the parameter max_chain_length (described below) is too large. | |
30 * | |
31 * ACKNOWLEDGEMENTS | |
32 * | |
33 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and | |
34 * I found it in 'freeze' written by Leonid Broukhis. | |
35 * Thanks to many people for bug reports and testing. | |
36 * | |
37 * REFERENCES | |
38 * | |
39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". | |
40 * Available in http://www.ietf.org/rfc/rfc1951.txt | |
41 * | |
42 * A description of the Rabin and Karp algorithm is given in the book | |
43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252. | |
44 * | |
45 * Fiala,E.R., and Greene,D.H. | |
46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 | |
47 * | |
48 */ | |
49 | |
50 /* @(#) $Id: deflate.c,v 1.1.1.2 2002/03/11 21:53:23 tromey Exp $ */ | |
51 | |
52 #include "deflate.h" | |
53 | |
54 const char deflate_copyright[] = | |
55 " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly "; | |
56 /* | |
57 If you use the zlib library in a product, an acknowledgment is welcome | |
58 in the documentation of your product. If for some reason you cannot | |
59 include such an acknowledgment, I would appreciate that you keep this | |
60 copyright string in the executable of your product. | |
61 */ | |
62 | |
63 /* =========================================================================== | |
64 * Function prototypes. | |
65 */ | |
66 typedef enum { | |
67 need_more, /* block not completed, need more input or more output */ | |
68 block_done, /* block flush performed */ | |
69 finish_started, /* finish started, need only more output at next deflate */ | |
70 finish_done /* finish done, accept no more input or output */ | |
71 } block_state; | |
72 | |
73 typedef block_state (*compress_func) OF((deflate_state *s, int flush)); | |
74 /* Compression function. Returns the block state after the call. */ | |
75 | |
76 local void fill_window OF((deflate_state *s)); | |
77 local block_state deflate_stored OF((deflate_state *s, int flush)); | |
78 local block_state deflate_fast OF((deflate_state *s, int flush)); | |
79 #ifndef FASTEST | |
80 local block_state deflate_slow OF((deflate_state *s, int flush)); | |
81 #endif | |
82 local 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)); | |
95 | |
96 #ifdef DEBUG | |
97 local void check_match OF((deflate_state *s, IPos start, IPos match, | |
98 int length)); | |
99 #endif | |
100 | |
101 /* =========================================================================== | |
102 * Local data | |
103 */ | |
104 | |
105 #define NIL 0 | |
106 /* Tail of hash chains */ | |
107 | |
108 #ifndef TOO_FAR | |
109 # define TOO_FAR 4096 | |
110 #endif | |
111 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ | |
112 | |
113 #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. | |
116 */ | |
117 | |
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. | |
122 */ | |
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; | |
130 | |
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}, | |
143 | |
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 | |
151 | |
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. | |
155 */ | |
156 | |
157 #define EQUAL 0 | |
158 /* result of memcmp for equal strings */ | |
159 | |
160 #ifndef NO_DUMMY_DECL | |
161 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */ | |
162 #endif | |
163 | |
164 /* =========================================================================== | |
165 * Update a hash value with the given input byte | |
166 * IN assertion: all calls to to UPDATE_HASH are made with consecutive | |
167 * input characters, so that a running hash key can be computed from the | |
168 * previous key instead of complete recalculation each time. | |
169 */ | |
170 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) | |
171 | |
172 | |
173 /* =========================================================================== | |
174 * Insert string str in the dictionary and set match_head to the previous head | |
175 * of the hash chain (the most recent string with same hash key). Return | |
176 * the previous length of the hash chain. | |
177 * If this file is compiled with -DFASTEST, the compression level is forced | |
178 * to 1, and no hash chains are maintained. | |
179 * IN assertion: all calls to to INSERT_STRING are made with consecutive | |
180 * input characters and the first MIN_MATCH bytes of str are valid | |
181 * (except for the last MIN_MATCH-1 bytes of the input file). | |
182 */ | |
183 #ifdef FASTEST | |
184 #define INSERT_STRING(s, str, match_head) \ | |
185 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ | |
186 match_head = s->head[s->ins_h], \ | |
187 s->head[s->ins_h] = (Pos)(str)) | |
188 #else | |
189 #define INSERT_STRING(s, str, match_head) \ | |
190 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ | |
191 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ | |
192 s->head[s->ins_h] = (Pos)(str)) | |
193 #endif | |
194 | |
195 /* =========================================================================== | |
196 * Initialize the hash table (avoiding 64K overflow for 16 bit systems). | |
197 * prev[] will be initialized on the fly. | |
198 */ | |
199 #define CLEAR_HASH(s) \ | |
200 s->head[s->hash_size-1] = NIL; \ | |
201 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); | |
202 | |
203 /* ========================================================================= */ | |
204 int ZEXPORT deflateInit_(strm, level, version, stream_size) | |
205 z_streamp strm; | |
206 int level; | |
207 const char *version; | |
208 int stream_size; | |
209 { | |
210 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, | |
211 Z_DEFAULT_STRATEGY, version, stream_size); | |
212 /* To do: ignore strm->next_in if we use it as window */ | |
213 } | |
214 | |
215 /* ========================================================================= */ | |
216 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, | |
217 version, stream_size) | |
218 z_streamp strm; | |
219 int level; | |
220 int method; | |
221 int windowBits; | |
222 int memLevel; | |
223 int strategy; | |
224 const char *version; | |
225 int stream_size; | |
226 { | |
227 deflate_state *s; | |
228 int wrap = 1; | |
229 static const char my_version[] = ZLIB_VERSION; | |
230 | |
231 ushf *overlay; | |
232 /* We overlay pending_buf and d_buf+l_buf. This works since the average | |
233 * output size for (length,distance) codes is <= 24 bits. | |
234 */ | |
235 | |
236 if (version == Z_NULL || version[0] != my_version[0] || | |
237 stream_size != sizeof(z_stream)) { | |
238 return Z_VERSION_ERROR; | |
239 } | |
240 if (strm == Z_NULL) return Z_STREAM_ERROR; | |
241 | |
242 strm->msg = Z_NULL; | |
243 if (strm->zalloc == (alloc_func)0) { | |
244 strm->zalloc = zcalloc; | |
245 strm->opaque = (voidpf)0; | |
246 } | |
247 if (strm->zfree == (free_func)0) strm->zfree = zcfree; | |
248 | |
249 #ifdef FASTEST | |
250 if (level != 0) level = 1; | |
251 #else | |
252 if (level == Z_DEFAULT_COMPRESSION) level = 6; | |
253 #endif | |
254 | |
255 if (windowBits < 0) { /* suppress zlib wrapper */ | |
256 wrap = 0; | |
257 windowBits = -windowBits; | |
258 } | |
259 #ifdef GZIP | |
260 else if (windowBits > 15) { | |
261 wrap = 2; /* write gzip wrapper instead */ | |
262 windowBits -= 16; | |
263 } | |
264 #endif | |
265 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || | |
266 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || | |
267 strategy < 0 || strategy > Z_FIXED) { | |
268 return Z_STREAM_ERROR; | |
269 } | |
270 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ | |
271 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); | |
272 if (s == Z_NULL) return Z_MEM_ERROR; | |
273 strm->state = (struct internal_state FAR *)s; | |
274 s->strm = strm; | |
275 | |
276 s->wrap = wrap; | |
277 s->gzhead = Z_NULL; | |
278 s->w_bits = windowBits; | |
279 s->w_size = 1 << s->w_bits; | |
280 s->w_mask = s->w_size - 1; | |
281 | |
282 s->hash_bits = memLevel + 7; | |
283 s->hash_size = 1 << s->hash_bits; | |
284 s->hash_mask = s->hash_size - 1; | |
285 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); | |
286 | |
287 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); | |
288 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); | |
289 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); | |
290 | |
291 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ | |
292 | |
293 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); | |
294 s->pending_buf = (uchf *) overlay; | |
295 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); | |
296 | |
297 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || | |
298 s->pending_buf == Z_NULL) { | |
299 s->status = FINISH_STATE; | |
300 strm->msg = (char*)ERR_MSG(Z_MEM_ERROR); | |
301 deflateEnd (strm); | |
302 return Z_MEM_ERROR; | |
303 } | |
304 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); | |
305 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; | |
306 | |
307 s->level = level; | |
308 s->strategy = strategy; | |
309 s->method = (Byte)method; | |
310 | |
311 return deflateReset(strm); | |
312 } | |
313 | |
314 /* ========================================================================= */ | |
315 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) | |
316 z_streamp strm; | |
317 const Bytef *dictionary; | |
318 uInt dictLength; | |
319 { | |
320 deflate_state *s; | |
321 uInt length = dictLength; | |
322 uInt n; | |
323 IPos hash_head = 0; | |
324 | |
325 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL || | |
326 strm->state->wrap == 2 || | |
327 (strm->state->wrap == 1 && strm->state->status != INIT_STATE)) | |
328 return Z_STREAM_ERROR; | |
329 | |
330 s = strm->state; | |
331 if (s->wrap) | |
332 strm->adler = adler32(strm->adler, dictionary, dictLength); | |
333 | |
334 if (length < MIN_MATCH) return Z_OK; | |
335 if (length > MAX_DIST(s)) { | |
336 length = MAX_DIST(s); | |
337 dictionary += dictLength - length; /* use the tail of the dictionary */ | |
338 } | |
339 zmemcpy(s->window, dictionary, length); | |
340 s->strstart = length; | |
341 s->block_start = (long)length; | |
342 | |
343 /* Insert all strings in the hash table (except for the last two bytes). | |
344 * s->lookahead stays null, so s->ins_h will be recomputed at the next | |
345 * call of fill_window. | |
346 */ | |
347 s->ins_h = s->window[0]; | |
348 UPDATE_HASH(s, s->ins_h, s->window[1]); | |
349 for (n = 0; n <= length - MIN_MATCH; n++) { | |
350 INSERT_STRING(s, n, hash_head); | |
351 } | |
352 if (hash_head) hash_head = 0; /* to make compiler happy */ | |
353 return Z_OK; | |
354 } | |
355 | |
356 /* ========================================================================= */ | |
357 int ZEXPORT deflateReset (strm) | |
358 z_streamp strm; | |
359 { | |
360 deflate_state *s; | |
361 | |
362 if (strm == Z_NULL || strm->state == Z_NULL || | |
363 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { | |
364 return Z_STREAM_ERROR; | |
365 } | |
366 | |
367 strm->total_in = strm->total_out = 0; | |
368 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ | |
369 strm->data_type = Z_UNKNOWN; | |
370 | |
371 s = (deflate_state *)strm->state; | |
372 s->pending = 0; | |
373 s->pending_out = s->pending_buf; | |
374 | |
375 if (s->wrap < 0) { | |
376 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ | |
377 } | |
378 s->status = s->wrap ? INIT_STATE : BUSY_STATE; | |
379 strm->adler = | |
380 #ifdef GZIP | |
381 s->wrap == 2 ? crc32(0L, Z_NULL, 0) : | |
382 #endif | |
383 adler32(0L, Z_NULL, 0); | |
384 s->last_flush = Z_NO_FLUSH; | |
385 | |
386 _tr_init(s); | |
387 lm_init(s); | |
388 | |
389 return Z_OK; | |
390 } | |
391 | |
392 /* ========================================================================= */ | |
393 int ZEXPORT deflateSetHeader (strm, head) | |
394 z_streamp strm; | |
395 gz_headerp head; | |
396 { | |
397 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; | |
398 if (strm->state->wrap != 2) return Z_STREAM_ERROR; | |
399 strm->state->gzhead = head; | |
400 return Z_OK; | |
401 } | |
402 | |
403 /* ========================================================================= */ | |
404 int ZEXPORT deflatePrime (strm, bits, value) | |
405 z_streamp strm; | |
406 int bits; | |
407 int value; | |
408 { | |
409 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; | |
410 strm->state->bi_valid = bits; | |
411 strm->state->bi_buf = (ush)(value & ((1 << bits) - 1)); | |
412 return Z_OK; | |
413 } | |
414 | |
415 /* ========================================================================= */ | |
416 int ZEXPORT deflateParams(strm, level, strategy) | |
417 z_streamp strm; | |
418 int level; | |
419 int strategy; | |
420 { | |
421 deflate_state *s; | |
422 compress_func func; | |
423 int err = Z_OK; | |
424 | |
425 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; | |
426 s = strm->state; | |
427 | |
428 #ifdef FASTEST | |
429 if (level != 0) level = 1; | |
430 #else | |
431 if (level == Z_DEFAULT_COMPRESSION) level = 6; | |
432 #endif | |
433 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { | |
434 return Z_STREAM_ERROR; | |
435 } | |
436 func = configuration_table[s->level].func; | |
437 | |
438 if (func != configuration_table[level].func && strm->total_in != 0) { | |
439 /* Flush the last buffer: */ | |
440 err = deflate(strm, Z_PARTIAL_FLUSH); | |
441 } | |
442 if (s->level != level) { | |
443 s->level = level; | |
444 s->max_lazy_match = configuration_table[level].max_lazy; | |
445 s->good_match = configuration_table[level].good_length; | |
446 s->nice_match = configuration_table[level].nice_length; | |
447 s->max_chain_length = configuration_table[level].max_chain; | |
448 } | |
449 s->strategy = strategy; | |
450 return err; | |
451 } | |
452 | |
453 /* ========================================================================= */ | |
454 int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) | |
455 z_streamp strm; | |
456 int good_length; | |
457 int max_lazy; | |
458 int nice_length; | |
459 int max_chain; | |
460 { | |
461 deflate_state *s; | |
462 | |
463 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; | |
464 s = strm->state; | |
465 s->good_match = good_length; | |
466 s->max_lazy_match = max_lazy; | |
467 s->nice_match = nice_length; | |
468 s->max_chain_length = max_chain; | |
469 return Z_OK; | |
470 } | |
471 | |
472 /* ========================================================================= | |
473 * For the default windowBits of 15 and memLevel of 8, this function returns | |
474 * a close to exact, as well as small, upper bound on the compressed size. | |
475 * They are coded as constants here for a reason--if the #define's are | |
476 * changed, then this function needs to be changed as well. The return | |
477 * value for 15 and 8 only works for those exact settings. | |
478 * | |
479 * For any setting other than those defaults for windowBits and memLevel, | |
480 * the value returned is a conservative worst case for the maximum expansion | |
481 * resulting from using fixed blocks instead of stored blocks, which deflate | |
482 * can emit on compressed data for some combinations of the parameters. | |
483 * | |
484 * This function could be more sophisticated to provide closer upper bounds | |
485 * for every combination of windowBits and memLevel, as well as wrap. | |
486 * But even the conservative upper bound of about 14% expansion does not | |
487 * seem onerous for output buffer allocation. | |
488 */ | |
489 uLong ZEXPORT deflateBound(strm, sourceLen) | |
490 z_streamp strm; | |
491 uLong sourceLen; | |
492 { | |
493 deflate_state *s; | |
494 uLong destLen; | |
495 | |
496 /* conservative upper bound */ | |
497 destLen = sourceLen + | |
498 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11; | |
499 | |
500 /* if can't get parameters, return conservative bound */ | |
501 if (strm == Z_NULL || strm->state == Z_NULL) | |
502 return destLen; | |
503 | |
504 /* if not default parameters, return conservative bound */ | |
505 s = strm->state; | |
506 if (s->w_bits != 15 || s->hash_bits != 8 + 7) | |
507 return destLen; | |
508 | |
509 /* default settings: return tight bound for that case */ | |
510 return compressBound(sourceLen); | |
511 } | |
512 | |
513 /* ========================================================================= | |
514 * Put a short in the pending buffer. The 16-bit value is put in MSB order. | |
515 * IN assertion: the stream state is correct and there is enough room in | |
516 * pending_buf. | |
517 */ | |
518 local void putShortMSB (s, b) | |
519 deflate_state *s; | |
520 uInt b; | |
521 { | |
522 put_byte(s, (Byte)(b >> 8)); | |
523 put_byte(s, (Byte)(b & 0xff)); | |
524 } | |
525 | |
526 /* ========================================================================= | |
527 * Flush as much pending output as possible. All deflate() output goes | |
528 * through this function so some applications may wish to modify it | |
529 * to avoid allocating a large strm->next_out buffer and copying into it. | |
530 * (See also read_buf()). | |
531 */ | |
532 local void flush_pending(strm) | |
533 z_streamp strm; | |
534 { | |
535 unsigned len = strm->state->pending; | |
536 | |
537 if (len > strm->avail_out) len = strm->avail_out; | |
538 if (len == 0) return; | |
539 | |
540 zmemcpy(strm->next_out, strm->state->pending_out, len); | |
541 strm->next_out += len; | |
542 strm->state->pending_out += len; | |
543 strm->total_out += len; | |
544 strm->avail_out -= len; | |
545 strm->state->pending -= len; | |
546 if (strm->state->pending == 0) { | |
547 strm->state->pending_out = strm->state->pending_buf; | |
548 } | |
549 } | |
550 | |
551 /* ========================================================================= */ | |
552 int ZEXPORT deflate (strm, flush) | |
553 z_streamp strm; | |
554 int flush; | |
555 { | |
556 int old_flush; /* value of flush param for previous deflate call */ | |
557 deflate_state *s; | |
558 | |
559 if (strm == Z_NULL || strm->state == Z_NULL || | |
560 flush > Z_FINISH || flush < 0) { | |
561 return Z_STREAM_ERROR; | |
562 } | |
563 s = strm->state; | |
564 | |
565 if (strm->next_out == Z_NULL || | |
566 (strm->next_in == Z_NULL && strm->avail_in != 0) || | |
567 (s->status == FINISH_STATE && flush != Z_FINISH)) { | |
568 ERR_RETURN(strm, Z_STREAM_ERROR); | |
569 } | |
570 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); | |
571 | |
572 s->strm = strm; /* just in case */ | |
573 old_flush = s->last_flush; | |
574 s->last_flush = flush; | |
575 | |
576 /* Write the header */ | |
577 if (s->status == INIT_STATE) { | |
578 #ifdef GZIP | |
579 if (s->wrap == 2) { | |
580 strm->adler = crc32(0L, Z_NULL, 0); | |
581 put_byte(s, 31); | |
582 put_byte(s, 139); | |
583 put_byte(s, 8); | |
584 if (s->gzhead == NULL) { | |
585 put_byte(s, 0); | |
586 put_byte(s, 0); | |
587 put_byte(s, 0); | |
588 put_byte(s, 0); | |
589 put_byte(s, 0); | |
590 put_byte(s, s->level == 9 ? 2 : | |
591 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? | |
592 4 : 0)); | |
593 put_byte(s, OS_CODE); | |
594 s->status = BUSY_STATE; | |
595 } | |
596 else { | |
597 put_byte(s, (s->gzhead->text ? 1 : 0) + | |
598 (s->gzhead->hcrc ? 2 : 0) + | |
599 (s->gzhead->extra == Z_NULL ? 0 : 4) + | |
600 (s->gzhead->name == Z_NULL ? 0 : 8) + | |
601 (s->gzhead->comment == Z_NULL ? 0 : 16) | |
602 ); | |
603 put_byte(s, (Byte)(s->gzhead->time & 0xff)); | |
604 put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); | |
605 put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); | |
606 put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); | |
607 put_byte(s, s->level == 9 ? 2 : | |
608 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? | |
609 4 : 0)); | |
610 put_byte(s, s->gzhead->os & 0xff); | |
611 if (s->gzhead->extra != NULL) { | |
612 put_byte(s, s->gzhead->extra_len & 0xff); | |
613 put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); | |
614 } | |
615 if (s->gzhead->hcrc) | |
616 strm->adler = crc32(strm->adler, s->pending_buf, | |
617 s->pending); | |
618 s->gzindex = 0; | |
619 s->status = EXTRA_STATE; | |
620 } | |
621 } | |
622 else | |
623 #endif | |
624 { | |
625 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; | |
626 uInt level_flags; | |
627 | |
628 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) | |
629 level_flags = 0; | |
630 else if (s->level < 6) | |
631 level_flags = 1; | |
632 else if (s->level == 6) | |
633 level_flags = 2; | |
634 else | |
635 level_flags = 3; | |
636 header |= (level_flags << 6); | |
637 if (s->strstart != 0) header |= PRESET_DICT; | |
638 header += 31 - (header % 31); | |
639 | |
640 s->status = BUSY_STATE; | |
641 putShortMSB(s, header); | |
642 | |
643 /* Save the adler32 of the preset dictionary: */ | |
644 if (s->strstart != 0) { | |
645 putShortMSB(s, (uInt)(strm->adler >> 16)); | |
646 putShortMSB(s, (uInt)(strm->adler & 0xffff)); | |
647 } | |
648 strm->adler = adler32(0L, Z_NULL, 0); | |
649 } | |
650 } | |
651 #ifdef GZIP | |
652 if (s->status == EXTRA_STATE) { | |
653 if (s->gzhead->extra != NULL) { | |
654 uInt beg = s->pending; /* start of bytes to update crc */ | |
655 | |
656 while (s->gzindex < (s->gzhead->extra_len & 0xffff)) { | |
657 if (s->pending == s->pending_buf_size) { | |
658 if (s->gzhead->hcrc && s->pending > beg) | |
659 strm->adler = crc32(strm->adler, s->pending_buf + beg, | |
660 s->pending - beg); | |
661 flush_pending(strm); | |
662 beg = s->pending; | |
663 if (s->pending == s->pending_buf_size) | |
664 break; | |
665 } | |
666 put_byte(s, s->gzhead->extra[s->gzindex]); | |
667 s->gzindex++; | |
668 } | |
669 if (s->gzhead->hcrc && s->pending > beg) | |
670 strm->adler = crc32(strm->adler, s->pending_buf + beg, | |
671 s->pending - beg); | |
672 if (s->gzindex == s->gzhead->extra_len) { | |
673 s->gzindex = 0; | |
674 s->status = NAME_STATE; | |
675 } | |
676 } | |
677 else | |
678 s->status = NAME_STATE; | |
679 } | |
680 if (s->status == NAME_STATE) { | |
681 if (s->gzhead->name != NULL) { | |
682 uInt beg = s->pending; /* start of bytes to update crc */ | |
683 int val; | |
684 | |
685 do { | |
686 if (s->pending == s->pending_buf_size) { | |
687 if (s->gzhead->hcrc && s->pending > beg) | |
688 strm->adler = crc32(strm->adler, s->pending_buf + beg, | |
689 s->pending - beg); | |
690 flush_pending(strm); | |
691 beg = s->pending; | |
692 if (s->pending == s->pending_buf_size) { | |
693 val = 1; | |
694 break; | |
695 } | |
696 } | |
697 val = s->gzhead->name[s->gzindex++]; | |
698 put_byte(s, val); | |
699 } while (val != 0); | |
700 if (s->gzhead->hcrc && s->pending > beg) | |
701 strm->adler = crc32(strm->adler, s->pending_buf + beg, | |
702 s->pending - beg); | |
703 if (val == 0) { | |
704 s->gzindex = 0; | |
705 s->status = COMMENT_STATE; | |
706 } | |
707 } | |
708 else | |
709 s->status = COMMENT_STATE; | |
710 } | |
711 if (s->status == COMMENT_STATE) { | |
712 if (s->gzhead->comment != NULL) { | |
713 uInt beg = s->pending; /* start of bytes to update crc */ | |
714 int val; | |
715 | |
716 do { | |
717 if (s->pending == s->pending_buf_size) { | |
718 if (s->gzhead->hcrc && s->pending > beg) | |
719 strm->adler = crc32(strm->adler, s->pending_buf + beg, | |
720 s->pending - beg); | |
721 flush_pending(strm); | |
722 beg = s->pending; | |
723 if (s->pending == s->pending_buf_size) { | |
724 val = 1; | |
725 break; | |
726 } | |
727 } | |
728 val = s->gzhead->comment[s->gzindex++]; | |
729 put_byte(s, val); | |
730 } while (val != 0); | |
731 if (s->gzhead->hcrc && s->pending > beg) | |
732 strm->adler = crc32(strm->adler, s->pending_buf + beg, | |
733 s->pending - beg); | |
734 if (val == 0) | |
735 s->status = HCRC_STATE; | |
736 } | |
737 else | |
738 s->status = HCRC_STATE; | |
739 } | |
740 if (s->status == HCRC_STATE) { | |
741 if (s->gzhead->hcrc) { | |
742 if (s->pending + 2 > s->pending_buf_size) | |
743 flush_pending(strm); | |
744 if (s->pending + 2 <= s->pending_buf_size) { | |
745 put_byte(s, (Byte)(strm->adler & 0xff)); | |
746 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); | |
747 strm->adler = crc32(0L, Z_NULL, 0); | |
748 s->status = BUSY_STATE; | |
749 } | |
750 } | |
751 else | |
752 s->status = BUSY_STATE; | |
753 } | |
754 #endif | |
755 | |
756 /* Flush as much pending output as possible */ | |
757 if (s->pending != 0) { | |
758 flush_pending(strm); | |
759 if (strm->avail_out == 0) { | |
760 /* Since avail_out is 0, deflate will be called again with | |
761 * more output space, but possibly with both pending and | |
762 * avail_in equal to zero. There won't be anything to do, | |
763 * but this is not an error situation so make sure we | |
764 * return OK instead of BUF_ERROR at next call of deflate: | |
765 */ | |
766 s->last_flush = -1; | |
767 return Z_OK; | |
768 } | |
769 | |
770 /* Make sure there is something to do and avoid duplicate consecutive | |
771 * flushes. For repeated and useless calls with Z_FINISH, we keep | |
772 * returning Z_STREAM_END instead of Z_BUF_ERROR. | |
773 */ | |
774 } else if (strm->avail_in == 0 && flush <= old_flush && | |
775 flush != Z_FINISH) { | |
776 ERR_RETURN(strm, Z_BUF_ERROR); | |
777 } | |
778 | |
779 /* User must not provide more input after the first FINISH: */ | |
780 if (s->status == FINISH_STATE && strm->avail_in != 0) { | |
781 ERR_RETURN(strm, Z_BUF_ERROR); | |
782 } | |
783 | |
784 /* Start a new block or continue the current one. | |
785 */ | |
786 if (strm->avail_in != 0 || s->lookahead != 0 || | |
787 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { | |
788 block_state bstate; | |
789 | |
790 bstate = (*(configuration_table[s->level].func))(s, flush); | |
791 | |
792 if (bstate == finish_started || bstate == finish_done) { | |
793 s->status = FINISH_STATE; | |
794 } | |
795 if (bstate == need_more || bstate == finish_started) { | |
796 if (strm->avail_out == 0) { | |
797 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ | |
798 } | |
799 return Z_OK; | |
800 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call | |
801 * of deflate should use the same flush parameter to make sure | |
802 * that the flush is complete. So we don't have to output an | |
803 * empty block here, this will be done at next call. This also | |
804 * ensures that for a very small output buffer, we emit at most | |
805 * one empty block. | |
806 */ | |
807 } | |
808 if (bstate == block_done) { | |
809 if (flush == Z_PARTIAL_FLUSH) { | |
810 _tr_align(s); | |
811 } else { /* FULL_FLUSH or SYNC_FLUSH */ | |
812 _tr_stored_block(s, (char*)0, 0L, 0); | |
813 /* For a full flush, this empty block will be recognized | |
814 * as a special marker by inflate_sync(). | |
815 */ | |
816 if (flush == Z_FULL_FLUSH) { | |
817 CLEAR_HASH(s); /* forget history */ | |
818 } | |
819 } | |
820 flush_pending(strm); | |
821 if (strm->avail_out == 0) { | |
822 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ | |
823 return Z_OK; | |
824 } | |
825 } | |
826 } | |
827 Assert(strm->avail_out > 0, "bug2"); | |
828 | |
829 if (flush != Z_FINISH) return Z_OK; | |
830 if (s->wrap <= 0) return Z_STREAM_END; | |
831 | |
832 /* Write the trailer */ | |
833 #ifdef GZIP | |
834 if (s->wrap == 2) { | |
835 put_byte(s, (Byte)(strm->adler & 0xff)); | |
836 put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); | |
837 put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); | |
838 put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); | |
839 put_byte(s, (Byte)(strm->total_in & 0xff)); | |
840 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); | |
841 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); | |
842 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); | |
843 } | |
844 else | |
845 #endif | |
846 { | |
847 putShortMSB(s, (uInt)(strm->adler >> 16)); | |
848 putShortMSB(s, (uInt)(strm->adler & 0xffff)); | |
849 } | |
850 flush_pending(strm); | |
851 /* If avail_out is zero, the application will call deflate again | |
852 * to flush the rest. | |
853 */ | |
854 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ | |
855 return s->pending != 0 ? Z_OK : Z_STREAM_END; | |
856 } | |
857 | |
858 /* ========================================================================= */ | |
859 int ZEXPORT deflateEnd (strm) | |
860 z_streamp strm; | |
861 { | |
862 int status; | |
863 | |
864 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; | |
865 | |
866 status = strm->state->status; | |
867 if (status != INIT_STATE && | |
868 status != EXTRA_STATE && | |
869 status != NAME_STATE && | |
870 status != COMMENT_STATE && | |
871 status != HCRC_STATE && | |
872 status != BUSY_STATE && | |
873 status != FINISH_STATE) { | |
874 return Z_STREAM_ERROR; | |
875 } | |
876 | |
877 /* Deallocate in reverse order of allocations: */ | |
878 TRY_FREE(strm, strm->state->pending_buf); | |
879 TRY_FREE(strm, strm->state->head); | |
880 TRY_FREE(strm, strm->state->prev); | |
881 TRY_FREE(strm, strm->state->window); | |
882 | |
883 ZFREE(strm, strm->state); | |
884 strm->state = Z_NULL; | |
885 | |
886 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; | |
887 } | |
888 | |
889 /* ========================================================================= | |
890 * Copy the source state to the destination state. | |
891 * To simplify the source, this is not supported for 16-bit MSDOS (which | |
892 * doesn't have enough memory anyway to duplicate compression states). | |
893 */ | |
894 int ZEXPORT deflateCopy (dest, source) | |
895 z_streamp dest; | |
896 z_streamp source; | |
897 { | |
898 #ifdef MAXSEG_64K | |
899 return Z_STREAM_ERROR; | |
900 #else | |
901 deflate_state *ds; | |
902 deflate_state *ss; | |
903 ushf *overlay; | |
904 | |
905 | |
906 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { | |
907 return Z_STREAM_ERROR; | |
908 } | |
909 | |
910 ss = source->state; | |
911 | |
912 zmemcpy(dest, source, sizeof(z_stream)); | |
913 | |
914 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); | |
915 if (ds == Z_NULL) return Z_MEM_ERROR; | |
916 dest->state = (struct internal_state FAR *) ds; | |
917 zmemcpy(ds, ss, sizeof(deflate_state)); | |
918 ds->strm = dest; | |
919 | |
920 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); | |
921 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); | |
922 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); | |
923 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); | |
924 ds->pending_buf = (uchf *) overlay; | |
925 | |
926 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || | |
927 ds->pending_buf == Z_NULL) { | |
928 deflateEnd (dest); | |
929 return Z_MEM_ERROR; | |
930 } | |
931 /* following zmemcpy do not work for 16-bit MSDOS */ | |
932 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); | |
933 zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos)); | |
934 zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos)); | |
935 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); | |
936 | |
937 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); | |
938 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); | |
939 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; | |
940 | |
941 ds->l_desc.dyn_tree = ds->dyn_ltree; | |
942 ds->d_desc.dyn_tree = ds->dyn_dtree; | |
943 ds->bl_desc.dyn_tree = ds->bl_tree; | |
944 | |
945 return Z_OK; | |
946 #endif /* MAXSEG_64K */ | |
947 } | |
948 | |
949 /* =========================================================================== | |
950 * Read a new buffer from the current input stream, update the adler32 | |
951 * and total number of bytes read. All deflate() input goes through | |
952 * this function so some applications may wish to modify it to avoid | |
953 * allocating a large strm->next_in buffer and copying from it. | |
954 * (See also flush_pending()). | |
955 */ | |
956 local int read_buf(strm, buf, size) | |
957 z_streamp strm; | |
958 Bytef *buf; | |
959 unsigned size; | |
960 { | |
961 unsigned len = strm->avail_in; | |
962 | |
963 if (len > size) len = size; | |
964 if (len == 0) return 0; | |
965 | |
966 strm->avail_in -= len; | |
967 | |
968 if (strm->state->wrap == 1) { | |
969 strm->adler = adler32(strm->adler, strm->next_in, len); | |
970 } | |
971 #ifdef GZIP | |
972 else if (strm->state->wrap == 2) { | |
973 strm->adler = crc32(strm->adler, strm->next_in, len); | |
974 } | |
975 #endif | |
976 zmemcpy(buf, strm->next_in, len); | |
977 strm->next_in += len; | |
978 strm->total_in += len; | |
979 | |
980 return (int)len; | |
981 } | |
982 | |
983 /* =========================================================================== | |
984 * Initialize the "longest match" routines for a new zlib stream | |
985 */ | |
986 local void lm_init (s) | |
987 deflate_state *s; | |
988 { | |
989 s->window_size = (ulg)2L*s->w_size; | |
990 | |
991 CLEAR_HASH(s); | |
992 | |
993 /* Set the default configuration parameters: | |
994 */ | |
995 s->max_lazy_match = configuration_table[s->level].max_lazy; | |
996 s->good_match = configuration_table[s->level].good_length; | |
997 s->nice_match = configuration_table[s->level].nice_length; | |
998 s->max_chain_length = configuration_table[s->level].max_chain; | |
999 | |
1000 s->strstart = 0; | |
1001 s->block_start = 0L; | |
1002 s->lookahead = 0; | |
1003 s->match_length = s->prev_length = MIN_MATCH-1; | |
1004 s->match_available = 0; | |
1005 s->ins_h = 0; | |
1006 #ifndef FASTEST | |
1007 #ifdef ASMV | |
1008 match_init(); /* initialize the asm code */ | |
1009 #endif | |
1010 #endif | |
1011 } | |
1012 | |
1013 #ifndef FASTEST | |
1014 /* =========================================================================== | |
1015 * Set match_start to the longest match starting at the given string and | |
1016 * return its length. Matches shorter or equal to prev_length are discarded, | |
1017 * in which case the result is equal to prev_length and match_start is | |
1018 * garbage. | |
1019 * IN assertions: cur_match is the head of the hash chain for the current | |
1020 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 | |
1021 * OUT assertion: the match length is not greater than s->lookahead. | |
1022 */ | |
1023 #ifndef ASMV | |
1024 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or | |
1025 * match.S. The code will be functionally equivalent. | |
1026 */ | |
1027 local uInt longest_match(s, cur_match) | |
1028 deflate_state *s; | |
1029 IPos cur_match; /* current match */ | |
1030 { | |
1031 unsigned chain_length = s->max_chain_length;/* max hash chain length */ | |
1032 register Bytef *scan = s->window + s->strstart; /* current string */ | |
1033 register Bytef *match; /* matched string */ | |
1034 register int len; /* length of current match */ | |
1035 int best_len = s->prev_length; /* best match length so far */ | |
1036 int nice_match = s->nice_match; /* stop if match long enough */ | |
1037 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? | |
1038 s->strstart - (IPos)MAX_DIST(s) : NIL; | |
1039 /* Stop when cur_match becomes <= limit. To simplify the code, | |
1040 * we prevent matches with the string of window index 0. | |
1041 */ | |
1042 Posf *prev = s->prev; | |
1043 uInt wmask = s->w_mask; | |
1044 | |
1045 #ifdef UNALIGNED_OK | |
1046 /* Compare two bytes at a time. Note: this is not always beneficial. | |
1047 * Try with and without -DUNALIGNED_OK to check. | |
1048 */ | |
1049 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; | |
1050 register ush scan_start = *(ushf*)scan; | |
1051 register ush scan_end = *(ushf*)(scan+best_len-1); | |
1052 #else | |
1053 register Bytef *strend = s->window + s->strstart + MAX_MATCH; | |
1054 register Byte scan_end1 = scan[best_len-1]; | |
1055 register Byte scan_end = scan[best_len]; | |
1056 #endif | |
1057 | |
1058 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. | |
1059 * It is easy to get rid of this optimization if necessary. | |
1060 */ | |
1061 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); | |
1062 | |
1063 /* Do not waste too much time if we already have a good match: */ | |
1064 if (s->prev_length >= s->good_match) { | |
1065 chain_length >>= 2; | |
1066 } | |
1067 /* Do not look for matches beyond the end of the input. This is necessary | |
1068 * to make deflate deterministic. | |
1069 */ | |
1070 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; | |
1071 | |
1072 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); | |
1073 | |
1074 do { | |
1075 Assert(cur_match < s->strstart, "no future"); | |
1076 match = s->window + cur_match; | |
1077 | |
1078 /* Skip to next match if the match length cannot increase | |
1079 * or if the match length is less than 2. Note that the checks below | |
1080 * for insufficient lookahead only occur occasionally for performance | |
1081 * reasons. Therefore uninitialized memory will be accessed, and | |
1082 * conditional jumps will be made that depend on those values. | |
1083 * However the length of the match is limited to the lookahead, so | |
1084 * the output of deflate is not affected by the uninitialized values. | |
1085 */ | |
1086 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) | |
1087 /* This code assumes sizeof(unsigned short) == 2. Do not use | |
1088 * UNALIGNED_OK if your compiler uses a different size. | |
1089 */ | |
1090 if (*(ushf*)(match+best_len-1) != scan_end || | |
1091 *(ushf*)match != scan_start) continue; | |
1092 | |
1093 /* It is not necessary to compare scan[2] and match[2] since they are | |
1094 * always equal when the other bytes match, given that the hash keys | |
1095 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at | |
1096 * strstart+3, +5, ... up to strstart+257. We check for insufficient | |
1097 * lookahead only every 4th comparison; the 128th check will be made | |
1098 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is | |
1099 * necessary to put more guard bytes at the end of the window, or | |
1100 * to check more often for insufficient lookahead. | |
1101 */ | |
1102 Assert(scan[2] == match[2], "scan[2]?"); | |
1103 scan++, match++; | |
1104 do { | |
1105 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && | |
1106 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && | |
1107 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && | |
1108 *(ushf*)(scan+=2) == *(ushf*)(match+=2) && | |
1109 scan < strend); | |
1110 /* The funny "do {}" generates better code on most compilers */ | |
1111 | |
1112 /* Here, scan <= window+strstart+257 */ | |
1113 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); | |
1114 if (*scan == *match) scan++; | |
1115 | |
1116 len = (MAX_MATCH - 1) - (int)(strend-scan); | |
1117 scan = strend - (MAX_MATCH-1); | |
1118 | |
1119 #else /* UNALIGNED_OK */ | |
1120 | |
1121 if (match[best_len] != scan_end || | |
1122 match[best_len-1] != scan_end1 || | |
1123 *match != *scan || | |
1124 *++match != scan[1]) continue; | |
1125 | |
1126 /* The check at best_len-1 can be removed because it will be made | |
1127 * again later. (This heuristic is not always a win.) | |
1128 * It is not necessary to compare scan[2] and match[2] since they | |
1129 * are always equal when the other bytes match, given that | |
1130 * the hash keys are equal and that HASH_BITS >= 8. | |
1131 */ | |
1132 scan += 2, match++; | |
1133 Assert(*scan == *match, "match[2]?"); | |
1134 | |
1135 /* We check for insufficient lookahead only every 8th comparison; | |
1136 * the 256th check will be made at strstart+258. | |
1137 */ | |
1138 do { | |
1139 } while (*++scan == *++match && *++scan == *++match && | |
1140 *++scan == *++match && *++scan == *++match && | |
1141 *++scan == *++match && *++scan == *++match && | |
1142 *++scan == *++match && *++scan == *++match && | |
1143 scan < strend); | |
1144 | |
1145 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); | |
1146 | |
1147 len = MAX_MATCH - (int)(strend - scan); | |
1148 scan = strend - MAX_MATCH; | |
1149 | |
1150 #endif /* UNALIGNED_OK */ | |
1151 | |
1152 if (len > best_len) { | |
1153 s->match_start = cur_match; | |
1154 best_len = len; | |
1155 if (len >= nice_match) break; | |
1156 #ifdef UNALIGNED_OK | |
1157 scan_end = *(ushf*)(scan+best_len-1); | |
1158 #else | |
1159 scan_end1 = scan[best_len-1]; | |
1160 scan_end = scan[best_len]; | |
1161 #endif | |
1162 } | |
1163 } while ((cur_match = prev[cur_match & wmask]) > limit | |
1164 && --chain_length != 0); | |
1165 | |
1166 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; | |
1167 return s->lookahead; | |
1168 } | |
1169 #endif /* ASMV */ | |
1170 #endif /* FASTEST */ | |
1171 | |
1172 /* --------------------------------------------------------------------------- | |
1173 * Optimized version for level == 1 or strategy == Z_RLE only | |
1174 */ | |
1175 local uInt longest_match_fast(s, cur_match) | |
1176 deflate_state *s; | |
1177 IPos cur_match; /* current match */ | |
1178 { | |
1179 register Bytef *scan = s->window + s->strstart; /* current string */ | |
1180 register Bytef *match; /* matched string */ | |
1181 register int len; /* length of current match */ | |
1182 register Bytef *strend = s->window + s->strstart + MAX_MATCH; | |
1183 | |
1184 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. | |
1185 * It is easy to get rid of this optimization if necessary. | |
1186 */ | |
1187 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); | |
1188 | |
1189 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); | |
1190 | |
1191 Assert(cur_match < s->strstart, "no future"); | |
1192 | |
1193 match = s->window + cur_match; | |
1194 | |
1195 /* Return failure if the match length is less than 2: | |
1196 */ | |
1197 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; | |
1198 | |
1199 /* The check at best_len-1 can be removed because it will be made | |
1200 * again later. (This heuristic is not always a win.) | |
1201 * It is not necessary to compare scan[2] and match[2] since they | |
1202 * are always equal when the other bytes match, given that | |
1203 * the hash keys are equal and that HASH_BITS >= 8. | |
1204 */ | |
1205 scan += 2, match += 2; | |
1206 Assert(*scan == *match, "match[2]?"); | |
1207 | |
1208 /* We check for insufficient lookahead only every 8th comparison; | |
1209 * the 256th check will be made at strstart+258. | |
1210 */ | |
1211 do { | |
1212 } while (*++scan == *++match && *++scan == *++match && | |
1213 *++scan == *++match && *++scan == *++match && | |
1214 *++scan == *++match && *++scan == *++match && | |
1215 *++scan == *++match && *++scan == *++match && | |
1216 scan < strend); | |
1217 | |
1218 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); | |
1219 | |
1220 len = MAX_MATCH - (int)(strend - scan); | |
1221 | |
1222 if (len < MIN_MATCH) return MIN_MATCH - 1; | |
1223 | |
1224 s->match_start = cur_match; | |
1225 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; | |
1226 } | |
1227 | |
1228 #ifdef DEBUG | |
1229 /* =========================================================================== | |
1230 * Check that the match at match_start is indeed a match. | |
1231 */ | |
1232 local void check_match(s, start, match, length) | |
1233 deflate_state *s; | |
1234 IPos start, match; | |
1235 int length; | |
1236 { | |
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"); | |
1246 } | |
1247 if (z_verbose > 1) { | |
1248 fprintf(stderr,"\\[%d,%d]", start-match, length); | |
1249 do { putc(s->window[start++], stderr); } while (--length != 0); | |
1250 } | |
1251 } | |
1252 #else | |
1253 # define check_match(s, start, match, length) | |
1254 #endif /* DEBUG */ | |
1255 | |
1256 /* =========================================================================== | |
1257 * Fill the window when the lookahead becomes insufficient. | |
1258 * Updates strstart and lookahead. | |
1259 * | |
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). | |
1265 */ | |
1266 local void fill_window(s) | |
1267 deflate_state *s; | |
1268 { | |
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; | |
1273 | |
1274 do { | |
1275 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); | |
1276 | |
1277 /* Deal with !@#$% 64K limit: */ | |
1278 if (sizeof(int) <= 2) { | |
1279 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { | |
1280 more = wsize; | |
1281 | |
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) | |
1285 */ | |
1286 more--; | |
1287 } | |
1288 } | |
1289 | |
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. | |
1292 */ | |
1293 if (s->strstart >= wsize+MAX_DIST(s)) { | |
1294 | |
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; | |
1299 | |
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.) | |
1305 */ | |
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); | |
1313 | |
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. | |
1322 */ | |
1323 } while (--n); | |
1324 #endif | |
1325 more += wsize; | |
1326 } | |
1327 if (s->strm->avail_in == 0) return; | |
1328 | |
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. | |
1339 */ | |
1340 Assert(more >= 2, "more < 2"); | |
1341 | |
1342 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); | |
1343 s->lookahead += n; | |
1344 | |
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 | |
1352 } | |
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. | |
1355 */ | |
1356 | |
1357 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); | |
1358 } | |
1359 | |
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. | |
1363 */ | |
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]")); \ | |
1373 } | |
1374 | |
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; \ | |
1379 } | |
1380 | |
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. | |
1389 */ | |
1390 local block_state deflate_stored(s, flush) | |
1391 deflate_state *s; | |
1392 int flush; | |
1393 { | |
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: | |
1396 */ | |
1397 ulg max_block_size = 0xffff; | |
1398 ulg max_start; | |
1399 | |
1400 if (max_block_size > s->pending_buf_size - 5) { | |
1401 max_block_size = s->pending_buf_size - 5; | |
1402 } | |
1403 | |
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) { | |
1408 | |
1409 Assert(s->strstart < s->w_size+MAX_DIST(s) || | |
1410 s->block_start >= (long)s->w_size, "slide too late"); | |
1411 | |
1412 fill_window(s); | |
1413 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; | |
1414 | |
1415 if (s->lookahead == 0) break; /* flush the current block */ | |
1416 } | |
1417 Assert(s->block_start >= 0L, "block gone"); | |
1418 | |
1419 s->strstart += s->lookahead; | |
1420 s->lookahead = 0; | |
1421 | |
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); | |
1429 } | |
1430 /* Flush if we may have to slide, otherwise block_start may become | |
1431 * negative and the data will be gone: | |
1432 */ | |
1433 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { | |
1434 FLUSH_BLOCK(s, 0); | |
1435 } | |
1436 } | |
1437 FLUSH_BLOCK(s, flush == Z_FINISH); | |
1438 return flush == Z_FINISH ? finish_done : block_done; | |
1439 } | |
1440 | |
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. | |
1447 */ | |
1448 local block_state deflate_fast(s, flush) | |
1449 deflate_state *s; | |
1450 int flush; | |
1451 { | |
1452 IPos hash_head = NIL; /* head of the hash chain */ | |
1453 int bflush; /* set if current block must be flushed */ | |
1454 | |
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. | |
1460 */ | |
1461 if (s->lookahead < MIN_LOOKAHEAD) { | |
1462 fill_window(s); | |
1463 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { | |
1464 return need_more; | |
1465 } | |
1466 if (s->lookahead == 0) break; /* flush the current block */ | |
1467 } | |
1468 | |
1469 /* Insert the string window[strstart .. strstart+2] in the | |
1470 * dictionary, and set hash_head to the head of the hash chain: | |
1471 */ | |
1472 if (s->lookahead >= MIN_MATCH) { | |
1473 INSERT_STRING(s, s->strstart, hash_head); | |
1474 } | |
1475 | |
1476 /* Find the longest match, discarding those <= prev_length. | |
1477 * At this point we have always match_length < MIN_MATCH | |
1478 */ | |
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). | |
1483 */ | |
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); | |
1488 } | |
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); | |
1494 } | |
1495 #endif | |
1496 /* longest_match() or longest_match_fast() sets match_start */ | |
1497 } | |
1498 if (s->match_length >= MIN_MATCH) { | |
1499 check_match(s, s->strstart, s->match_start, s->match_length); | |
1500 | |
1501 _tr_tally_dist(s, s->strstart - s->match_start, | |
1502 s->match_length - MIN_MATCH, bflush); | |
1503 | |
1504 s->lookahead -= s->match_length; | |
1505 | |
1506 /* Insert new strings in the hash table only if the match length | |
1507 * is not too large. This saves time but degrades compression. | |
1508 */ | |
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. | |
1518 */ | |
1519 } while (--s->match_length != 0); | |
1520 s->strstart++; | |
1521 } else | |
1522 #endif | |
1523 { | |
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. | |
1533 */ | |
1534 } | |
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++; | |
1541 } | |
1542 if (bflush) FLUSH_BLOCK(s, 0); | |
1543 } | |
1544 FLUSH_BLOCK(s, flush == Z_FINISH); | |
1545 return flush == Z_FINISH ? finish_done : block_done; | |
1546 } | |
1547 | |
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. | |
1553 */ | |
1554 local block_state deflate_slow(s, flush) | |
1555 deflate_state *s; | |
1556 int flush; | |
1557 { | |
1558 IPos hash_head = NIL; /* head of hash chain */ | |
1559 int bflush; /* set if current block must be flushed */ | |
1560 | |
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. | |
1567 */ | |
1568 if (s->lookahead < MIN_LOOKAHEAD) { | |
1569 fill_window(s); | |
1570 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { | |
1571 return need_more; | |
1572 } | |
1573 if (s->lookahead == 0) break; /* flush the current block */ | |
1574 } | |
1575 | |
1576 /* Insert the string window[strstart .. strstart+2] in the | |
1577 * dictionary, and set hash_head to the head of the hash chain: | |
1578 */ | |
1579 if (s->lookahead >= MIN_MATCH) { | |
1580 INSERT_STRING(s, s->strstart, hash_head); | |
1581 } | |
1582 | |
1583 /* Find the longest match, discarding those <= prev_length. | |
1584 */ | |
1585 s->prev_length = s->match_length, s->prev_match = s->match_start; | |
1586 s->match_length = MIN_MATCH-1; | |
1587 | |
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). | |
1593 */ | |
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); | |
1598 } | |
1599 /* longest_match() or longest_match_fast() sets match_start */ | |
1600 | |
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 )) { | |
1607 | |
1608 /* If prev_match is also MIN_MATCH, match_start is garbage | |
1609 * but we will ignore the current match anyway. | |
1610 */ | |
1611 s->match_length = MIN_MATCH-1; | |
1612 } | |
1613 } | |
1614 /* If there was a match at the previous step and the current | |
1615 * match is not better, output the previous match: | |
1616 */ | |
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. */ | |
1620 | |
1621 check_match(s, s->strstart-1, s->prev_match, s->prev_length); | |
1622 | |
1623 _tr_tally_dist(s, s->strstart -1 - s->prev_match, | |
1624 s->prev_length - MIN_MATCH, bflush); | |
1625 | |
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. | |
1630 */ | |
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); | |
1636 } | |
1637 } while (--s->prev_length != 0); | |
1638 s->match_available = 0; | |
1639 s->match_length = MIN_MATCH-1; | |
1640 s->strstart++; | |
1641 | |
1642 if (bflush) FLUSH_BLOCK(s, 0); | |
1643 | |
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. | |
1648 */ | |
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); | |
1653 } | |
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. | |
1660 */ | |
1661 s->match_available = 1; | |
1662 s->strstart++; | |
1663 s->lookahead--; | |
1664 } | |
1665 } | |
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; | |
1671 } | |
1672 FLUSH_BLOCK(s, flush == Z_FINISH); | |
1673 return flush == Z_FINISH ? finish_done : block_done; | |
1674 } | |
1675 #endif /* FASTEST */ | |
1676 | |
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.) | |
1682 */ | |
1683 local block_state deflate_rle(s, flush) | |
1684 deflate_state *s; | |
1685 int flush; | |
1686 { | |
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 */ | |
1692 | |
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. | |
1697 */ | |
1698 if (s->lookahead < MAX_MATCH) { | |
1699 fill_window(s); | |
1700 if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) { | |
1701 return need_more; | |
1702 } | |
1703 if (s->lookahead == 0) break; /* flush the current block */ | |
1704 } | |
1705 | |
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); | |
1716 } | |
1717 | |
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++; | |
1730 } | |
1731 if (bflush) FLUSH_BLOCK(s, 0); | |
1732 } | |
1733 FLUSH_BLOCK(s, flush == Z_FINISH); | |
1734 return flush == Z_FINISH ? finish_done : block_done; | |
1735 } | |
1736 #endif |