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1 | /* deflate.c -- compress data using the deflation algorithm |
2 | * Copyright (C) 1995-2004 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 | /* @(#) $Id$ */ |
51 | |
52 | #include "deflate.h" |
53 | |
54 | const char deflate_copyright[] = |
55 | " deflate 1.2.2 Copyright 1995-2004 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_RLE) { |
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->w_bits = windowBits; |
278 | s->w_size = 1 << s->w_bits; |
279 | s->w_mask = s->w_size - 1; |
280 | |
281 | s->hash_bits = memLevel + 7; |
282 | s->hash_size = 1 << s->hash_bits; |
283 | s->hash_mask = s->hash_size - 1; |
284 | s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); |
285 | |
286 | s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); |
287 | s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); |
288 | s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); |
289 | |
290 | s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ |
291 | |
292 | overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); |
293 | s->pending_buf = (uchf *) overlay; |
294 | s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); |
295 | |
296 | if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || |
297 | s->pending_buf == Z_NULL) { |
298 | s->status = FINISH_STATE; |
299 | strm->msg = (char*)ERR_MSG(Z_MEM_ERROR); |
300 | deflateEnd (strm); |
301 | return Z_MEM_ERROR; |
302 | } |
303 | s->d_buf = overlay + s->lit_bufsize/sizeof(ush); |
304 | s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; |
305 | |
306 | s->level = level; |
307 | s->strategy = strategy; |
308 | s->method = (Byte)method; |
309 | |
310 | return deflateReset(strm); |
311 | } |
312 | |
313 | /* ========================================================================= */ |
314 | int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) |
315 | z_streamp strm; |
316 | const Bytef *dictionary; |
317 | uInt dictLength; |
318 | { |
319 | deflate_state *s; |
320 | uInt length = dictLength; |
321 | uInt n; |
322 | IPos hash_head = 0; |
323 | |
324 | if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL || |
325 | strm->state->wrap == 2 || |
326 | (strm->state->wrap == 1 && strm->state->status != INIT_STATE)) |
327 | return Z_STREAM_ERROR; |
328 | |
329 | s = strm->state; |
330 | if (s->wrap) |
331 | strm->adler = adler32(strm->adler, dictionary, dictLength); |
332 | |
333 | if (length < MIN_MATCH) return Z_OK; |
334 | if (length > MAX_DIST(s)) { |
335 | length = MAX_DIST(s); |
336 | #ifndef USE_DICT_HEAD |
337 | dictionary += dictLength - length; /* use the tail of the dictionary */ |
338 | #endif |
339 | } |
340 | zmemcpy(s->window, dictionary, length); |
341 | s->strstart = length; |
342 | s->block_start = (long)length; |
343 | |
344 | /* Insert all strings in the hash table (except for the last two bytes). |
345 | * s->lookahead stays null, so s->ins_h will be recomputed at the next |
346 | * call of fill_window. |
347 | */ |
348 | s->ins_h = s->window[0]; |
349 | UPDATE_HASH(s, s->ins_h, s->window[1]); |
350 | for (n = 0; n <= length - MIN_MATCH; n++) { |
351 | INSERT_STRING(s, n, hash_head); |
352 | } |
353 | if (hash_head) hash_head = 0; /* to make compiler happy */ |
354 | return Z_OK; |
355 | } |
356 | |
357 | /* ========================================================================= */ |
358 | int ZEXPORT deflateReset (strm) |
359 | z_streamp strm; |
360 | { |
361 | deflate_state *s; |
362 | |
363 | if (strm == Z_NULL || strm->state == Z_NULL || |
364 | strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { |
365 | return Z_STREAM_ERROR; |
366 | } |
367 | |
368 | strm->total_in = strm->total_out = 0; |
369 | strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ |
370 | strm->data_type = Z_UNKNOWN; |
371 | |
372 | s = (deflate_state *)strm->state; |
373 | s->pending = 0; |
374 | s->pending_out = s->pending_buf; |
375 | |
376 | if (s->wrap < 0) { |
377 | s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ |
378 | } |
379 | s->status = s->wrap ? INIT_STATE : BUSY_STATE; |
380 | strm->adler = |
381 | #ifdef GZIP |
382 | s->wrap == 2 ? crc32(0L, Z_NULL, 0) : |
383 | #endif |
384 | adler32(0L, Z_NULL, 0); |
385 | s->last_flush = Z_NO_FLUSH; |
386 | |
387 | _tr_init(s); |
388 | lm_init(s); |
389 | |
390 | return Z_OK; |
391 | } |
392 | |
393 | /* ========================================================================= */ |
394 | int ZEXPORT deflatePrime (strm, bits, value) |
395 | z_streamp strm; |
396 | int bits; |
397 | int value; |
398 | { |
399 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
400 | strm->state->bi_valid = bits; |
401 | strm->state->bi_buf = (ush)(value & ((1 << bits) - 1)); |
402 | return Z_OK; |
403 | } |
404 | |
405 | /* ========================================================================= */ |
406 | int ZEXPORT deflateParams(strm, level, strategy) |
407 | z_streamp strm; |
408 | int level; |
409 | int strategy; |
410 | { |
411 | deflate_state *s; |
412 | compress_func func; |
413 | int err = Z_OK; |
414 | |
415 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
416 | s = strm->state; |
417 | |
418 | #ifdef FASTEST |
419 | if (level != 0) level = 1; |
420 | #else |
421 | if (level == Z_DEFAULT_COMPRESSION) level = 6; |
422 | #endif |
423 | if (level < 0 || level > 9 || strategy < 0 || strategy > Z_RLE) { |
424 | return Z_STREAM_ERROR; |
425 | } |
426 | func = configuration_table[s->level].func; |
427 | |
428 | if (func != configuration_table[level].func && strm->total_in != 0) { |
429 | /* Flush the last buffer: */ |
430 | err = deflate(strm, Z_PARTIAL_FLUSH); |
431 | } |
432 | if (s->level != level) { |
433 | s->level = level; |
434 | s->max_lazy_match = configuration_table[level].max_lazy; |
435 | s->good_match = configuration_table[level].good_length; |
436 | s->nice_match = configuration_table[level].nice_length; |
437 | s->max_chain_length = configuration_table[level].max_chain; |
438 | } |
439 | s->strategy = strategy; |
440 | return err; |
441 | } |
442 | |
443 | /* ========================================================================= |
444 | * For the default windowBits of 15 and memLevel of 8, this function returns |
445 | * a close to exact, as well as small, upper bound on the compressed size. |
446 | * They are coded as constants here for a reason--if the #define's are |
447 | * changed, then this function needs to be changed as well. The return |
448 | * value for 15 and 8 only works for those exact settings. |
449 | * |
450 | * For any setting other than those defaults for windowBits and memLevel, |
451 | * the value returned is a conservative worst case for the maximum expansion |
452 | * resulting from using fixed blocks instead of stored blocks, which deflate |
453 | * can emit on compressed data for some combinations of the parameters. |
454 | * |
455 | * This function could be more sophisticated to provide closer upper bounds |
456 | * for every combination of windowBits and memLevel, as well as wrap. |
457 | * But even the conservative upper bound of about 14% expansion does not |
458 | * seem onerous for output buffer allocation. |
459 | */ |
460 | uLong ZEXPORT deflateBound(strm, sourceLen) |
461 | z_streamp strm; |
462 | uLong sourceLen; |
463 | { |
464 | deflate_state *s; |
465 | uLong destLen; |
466 | |
467 | /* conservative upper bound */ |
468 | destLen = sourceLen + |
469 | ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11; |
470 | |
471 | /* if can't get parameters, return conservative bound */ |
472 | if (strm == Z_NULL || strm->state == Z_NULL) |
473 | return destLen; |
474 | |
475 | /* if not default parameters, return conservative bound */ |
476 | s = strm->state; |
477 | if (s->w_bits != 15 || s->hash_bits != 8 + 7) |
478 | return destLen; |
479 | |
480 | /* default settings: return tight bound for that case */ |
481 | return compressBound(sourceLen); |
482 | } |
483 | |
484 | /* ========================================================================= |
485 | * Put a short in the pending buffer. The 16-bit value is put in MSB order. |
486 | * IN assertion: the stream state is correct and there is enough room in |
487 | * pending_buf. |
488 | */ |
489 | local void putShortMSB (s, b) |
490 | deflate_state *s; |
491 | uInt b; |
492 | { |
493 | put_byte(s, (Byte)(b >> 8)); |
494 | put_byte(s, (Byte)(b & 0xff)); |
495 | } |
496 | |
497 | /* ========================================================================= |
498 | * Flush as much pending output as possible. All deflate() output goes |
499 | * through this function so some applications may wish to modify it |
500 | * to avoid allocating a large strm->next_out buffer and copying into it. |
501 | * (See also read_buf()). |
502 | */ |
503 | local void flush_pending(strm) |
504 | z_streamp strm; |
505 | { |
506 | unsigned len = strm->state->pending; |
507 | |
508 | if (len > strm->avail_out) len = strm->avail_out; |
509 | if (len == 0) return; |
510 | |
511 | zmemcpy(strm->next_out, strm->state->pending_out, len); |
512 | strm->next_out += len; |
513 | strm->state->pending_out += len; |
514 | strm->total_out += len; |
515 | strm->avail_out -= len; |
516 | strm->state->pending -= len; |
517 | if (strm->state->pending == 0) { |
518 | strm->state->pending_out = strm->state->pending_buf; |
519 | } |
520 | } |
521 | |
522 | /* ========================================================================= */ |
523 | int ZEXPORT deflate (strm, flush) |
524 | z_streamp strm; |
525 | int flush; |
526 | { |
527 | int old_flush; /* value of flush param for previous deflate call */ |
528 | deflate_state *s; |
529 | |
530 | if (strm == Z_NULL || strm->state == Z_NULL || |
531 | flush > Z_FINISH || flush < 0) { |
532 | return Z_STREAM_ERROR; |
533 | } |
534 | s = strm->state; |
535 | |
536 | if (strm->next_out == Z_NULL || |
537 | (strm->next_in == Z_NULL && strm->avail_in != 0) || |
538 | (s->status == FINISH_STATE && flush != Z_FINISH)) { |
539 | ERR_RETURN(strm, Z_STREAM_ERROR); |
540 | } |
541 | if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); |
542 | |
543 | s->strm = strm; /* just in case */ |
544 | old_flush = s->last_flush; |
545 | s->last_flush = flush; |
546 | |
547 | /* Write the header */ |
548 | if (s->status == INIT_STATE) { |
549 | #ifdef GZIP |
550 | if (s->wrap == 2) { |
551 | put_byte(s, 31); |
552 | put_byte(s, 139); |
553 | put_byte(s, 8); |
554 | put_byte(s, 0); |
555 | put_byte(s, 0); |
556 | put_byte(s, 0); |
557 | put_byte(s, 0); |
558 | put_byte(s, 0); |
559 | put_byte(s, s->level == 9 ? 2 : |
560 | (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? |
561 | 4 : 0)); |
562 | put_byte(s, 255); |
563 | s->status = BUSY_STATE; |
564 | strm->adler = crc32(0L, Z_NULL, 0); |
565 | } |
566 | else |
567 | #endif |
568 | { |
569 | uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; |
570 | uInt level_flags; |
571 | |
572 | if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) |
573 | level_flags = 0; |
574 | else if (s->level < 6) |
575 | level_flags = 1; |
576 | else if (s->level == 6) |
577 | level_flags = 2; |
578 | else |
579 | level_flags = 3; |
580 | header |= (level_flags << 6); |
581 | if (s->strstart != 0) header |= PRESET_DICT; |
582 | header += 31 - (header % 31); |
583 | |
584 | s->status = BUSY_STATE; |
585 | putShortMSB(s, header); |
586 | |
587 | /* Save the adler32 of the preset dictionary: */ |
588 | if (s->strstart != 0) { |
589 | putShortMSB(s, (uInt)(strm->adler >> 16)); |
590 | putShortMSB(s, (uInt)(strm->adler & 0xffff)); |
591 | } |
592 | strm->adler = adler32(0L, Z_NULL, 0); |
593 | } |
594 | } |
595 | |
596 | /* Flush as much pending output as possible */ |
597 | if (s->pending != 0) { |
598 | flush_pending(strm); |
599 | if (strm->avail_out == 0) { |
600 | /* Since avail_out is 0, deflate will be called again with |
601 | * more output space, but possibly with both pending and |
602 | * avail_in equal to zero. There won't be anything to do, |
603 | * but this is not an error situation so make sure we |
604 | * return OK instead of BUF_ERROR at next call of deflate: |
605 | */ |
606 | s->last_flush = -1; |
607 | return Z_OK; |
608 | } |
609 | |
610 | /* Make sure there is something to do and avoid duplicate consecutive |
611 | * flushes. For repeated and useless calls with Z_FINISH, we keep |
612 | * returning Z_STREAM_END instead of Z_BUF_ERROR. |
613 | */ |
614 | } else if (strm->avail_in == 0 && flush <= old_flush && |
615 | flush != Z_FINISH) { |
616 | ERR_RETURN(strm, Z_BUF_ERROR); |
617 | } |
618 | |
619 | /* User must not provide more input after the first FINISH: */ |
620 | if (s->status == FINISH_STATE && strm->avail_in != 0) { |
621 | ERR_RETURN(strm, Z_BUF_ERROR); |
622 | } |
623 | |
624 | /* Start a new block or continue the current one. |
625 | */ |
626 | if (strm->avail_in != 0 || s->lookahead != 0 || |
627 | (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { |
628 | block_state bstate; |
629 | |
630 | bstate = (*(configuration_table[s->level].func))(s, flush); |
631 | |
632 | if (bstate == finish_started || bstate == finish_done) { |
633 | s->status = FINISH_STATE; |
634 | } |
635 | if (bstate == need_more || bstate == finish_started) { |
636 | if (strm->avail_out == 0) { |
637 | s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ |
638 | } |
639 | return Z_OK; |
640 | /* If flush != Z_NO_FLUSH && avail_out == 0, the next call |
641 | * of deflate should use the same flush parameter to make sure |
642 | * that the flush is complete. So we don't have to output an |
643 | * empty block here, this will be done at next call. This also |
644 | * ensures that for a very small output buffer, we emit at most |
645 | * one empty block. |
646 | */ |
647 | } |
648 | if (bstate == block_done) { |
649 | if (flush == Z_PARTIAL_FLUSH) { |
650 | _tr_align(s); |
651 | } else { /* FULL_FLUSH or SYNC_FLUSH */ |
652 | _tr_stored_block(s, (char*)0, 0L, 0); |
653 | /* For a full flush, this empty block will be recognized |
654 | * as a special marker by inflate_sync(). |
655 | */ |
656 | if (flush == Z_FULL_FLUSH) { |
657 | CLEAR_HASH(s); /* forget history */ |
658 | } |
659 | } |
660 | flush_pending(strm); |
661 | if (strm->avail_out == 0) { |
662 | s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ |
663 | return Z_OK; |
664 | } |
665 | } |
666 | } |
667 | Assert(strm->avail_out > 0, "bug2"); |
668 | |
669 | if (flush != Z_FINISH) return Z_OK; |
670 | if (s->wrap <= 0) return Z_STREAM_END; |
671 | |
672 | /* Write the trailer */ |
673 | #ifdef GZIP |
674 | if (s->wrap == 2) { |
675 | put_byte(s, (Byte)(strm->adler & 0xff)); |
676 | put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); |
677 | put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); |
678 | put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); |
679 | put_byte(s, (Byte)(strm->total_in & 0xff)); |
680 | put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); |
681 | put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); |
682 | put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); |
683 | } |
684 | else |
685 | #endif |
686 | { |
687 | putShortMSB(s, (uInt)(strm->adler >> 16)); |
688 | putShortMSB(s, (uInt)(strm->adler & 0xffff)); |
689 | } |
690 | flush_pending(strm); |
691 | /* If avail_out is zero, the application will call deflate again |
692 | * to flush the rest. |
693 | */ |
694 | if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ |
695 | return s->pending != 0 ? Z_OK : Z_STREAM_END; |
696 | } |
697 | |
698 | /* ========================================================================= */ |
699 | int ZEXPORT deflateEnd (strm) |
700 | z_streamp strm; |
701 | { |
702 | int status; |
703 | |
704 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
705 | |
706 | status = strm->state->status; |
707 | if (status != INIT_STATE && status != BUSY_STATE && |
708 | status != FINISH_STATE) { |
709 | return Z_STREAM_ERROR; |
710 | } |
711 | |
712 | /* Deallocate in reverse order of allocations: */ |
713 | TRY_FREE(strm, strm->state->pending_buf); |
714 | TRY_FREE(strm, strm->state->head); |
715 | TRY_FREE(strm, strm->state->prev); |
716 | TRY_FREE(strm, strm->state->window); |
717 | |
718 | ZFREE(strm, strm->state); |
719 | strm->state = Z_NULL; |
720 | |
721 | return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; |
722 | } |
723 | |
724 | /* ========================================================================= |
725 | * Copy the source state to the destination state. |
726 | * To simplify the source, this is not supported for 16-bit MSDOS (which |
727 | * doesn't have enough memory anyway to duplicate compression states). |
728 | */ |
729 | int ZEXPORT deflateCopy (dest, source) |
730 | z_streamp dest; |
731 | z_streamp source; |
732 | { |
733 | #ifdef MAXSEG_64K |
734 | return Z_STREAM_ERROR; |
735 | #else |
736 | deflate_state *ds; |
737 | deflate_state *ss; |
738 | ushf *overlay; |
739 | |
740 | |
741 | if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { |
742 | return Z_STREAM_ERROR; |
743 | } |
744 | |
745 | ss = source->state; |
746 | |
747 | *dest = *source; |
748 | |
749 | ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); |
750 | if (ds == Z_NULL) return Z_MEM_ERROR; |
751 | dest->state = (struct internal_state FAR *) ds; |
752 | *ds = *ss; |
753 | ds->strm = dest; |
754 | |
755 | ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); |
756 | ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); |
757 | ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); |
758 | overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); |
759 | ds->pending_buf = (uchf *) overlay; |
760 | |
761 | if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || |
762 | ds->pending_buf == Z_NULL) { |
763 | deflateEnd (dest); |
764 | return Z_MEM_ERROR; |
765 | } |
766 | /* following zmemcpy do not work for 16-bit MSDOS */ |
767 | zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); |
768 | zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos)); |
769 | zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos)); |
770 | zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); |
771 | |
772 | ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); |
773 | ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); |
774 | ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; |
775 | |
776 | ds->l_desc.dyn_tree = ds->dyn_ltree; |
777 | ds->d_desc.dyn_tree = ds->dyn_dtree; |
778 | ds->bl_desc.dyn_tree = ds->bl_tree; |
779 | |
780 | return Z_OK; |
781 | #endif /* MAXSEG_64K */ |
782 | } |
783 | |
784 | /* =========================================================================== |
785 | * Read a new buffer from the current input stream, update the adler32 |
786 | * and total number of bytes read. All deflate() input goes through |
787 | * this function so some applications may wish to modify it to avoid |
788 | * allocating a large strm->next_in buffer and copying from it. |
789 | * (See also flush_pending()). |
790 | */ |
791 | local int read_buf(strm, buf, size) |
792 | z_streamp strm; |
793 | Bytef *buf; |
794 | unsigned size; |
795 | { |
796 | unsigned len = strm->avail_in; |
797 | |
798 | if (len > size) len = size; |
799 | if (len == 0) return 0; |
800 | |
801 | strm->avail_in -= len; |
802 | |
803 | if (strm->state->wrap == 1) { |
804 | strm->adler = adler32(strm->adler, strm->next_in, len); |
805 | } |
806 | #ifdef GZIP |
807 | else if (strm->state->wrap == 2) { |
808 | strm->adler = crc32(strm->adler, strm->next_in, len); |
809 | } |
810 | #endif |
811 | zmemcpy(buf, strm->next_in, len); |
812 | strm->next_in += len; |
813 | strm->total_in += len; |
814 | |
815 | return (int)len; |
816 | } |
817 | |
818 | /* =========================================================================== |
819 | * Initialize the "longest match" routines for a new zlib stream |
820 | */ |
821 | local void lm_init (s) |
822 | deflate_state *s; |
823 | { |
824 | s->window_size = (ulg)2L*s->w_size; |
825 | |
826 | CLEAR_HASH(s); |
827 | |
828 | /* Set the default configuration parameters: |
829 | */ |
830 | s->max_lazy_match = configuration_table[s->level].max_lazy; |
831 | s->good_match = configuration_table[s->level].good_length; |
832 | s->nice_match = configuration_table[s->level].nice_length; |
833 | s->max_chain_length = configuration_table[s->level].max_chain; |
834 | |
835 | s->strstart = 0; |
836 | s->block_start = 0L; |
837 | s->lookahead = 0; |
838 | s->match_length = s->prev_length = MIN_MATCH-1; |
839 | s->match_available = 0; |
840 | s->ins_h = 0; |
841 | #ifdef ASMV |
842 | match_init(); /* initialize the asm code */ |
843 | #endif |
844 | } |
845 | |
846 | #ifndef FASTEST |
847 | /* =========================================================================== |
848 | * Set match_start to the longest match starting at the given string and |
849 | * return its length. Matches shorter or equal to prev_length are discarded, |
850 | * in which case the result is equal to prev_length and match_start is |
851 | * garbage. |
852 | * IN assertions: cur_match is the head of the hash chain for the current |
853 | * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 |
854 | * OUT assertion: the match length is not greater than s->lookahead. |
855 | */ |
856 | #ifndef ASMV |
857 | /* For 80x86 and 680x0, an optimized version will be provided in match.asm or |
858 | * match.S. The code will be functionally equivalent. |
859 | */ |
860 | local uInt longest_match(s, cur_match) |
861 | deflate_state *s; |
862 | IPos cur_match; /* current match */ |
863 | { |
864 | unsigned chain_length = s->max_chain_length;/* max hash chain length */ |
865 | register Bytef *scan = s->window + s->strstart; /* current string */ |
866 | register Bytef *match; /* matched string */ |
867 | register int len; /* length of current match */ |
868 | int best_len = s->prev_length; /* best match length so far */ |
869 | int nice_match = s->nice_match; /* stop if match long enough */ |
870 | IPos limit = s->strstart > (IPos)MAX_DIST(s) ? |
871 | s->strstart - (IPos)MAX_DIST(s) : NIL; |
872 | /* Stop when cur_match becomes <= limit. To simplify the code, |
873 | * we prevent matches with the string of window index 0. |
874 | */ |
875 | Posf *prev = s->prev; |
876 | uInt wmask = s->w_mask; |
877 | |
878 | #ifdef UNALIGNED_OK |
879 | /* Compare two bytes at a time. Note: this is not always beneficial. |
880 | * Try with and without -DUNALIGNED_OK to check. |
881 | */ |
882 | register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; |
883 | register ush scan_start = *(ushf*)scan; |
884 | register ush scan_end = *(ushf*)(scan+best_len-1); |
885 | #else |
886 | register Bytef *strend = s->window + s->strstart + MAX_MATCH; |
887 | register Byte scan_end1 = scan[best_len-1]; |
888 | register Byte scan_end = scan[best_len]; |
889 | #endif |
890 | |
891 | /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. |
892 | * It is easy to get rid of this optimization if necessary. |
893 | */ |
894 | Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); |
895 | |
896 | /* Do not waste too much time if we already have a good match: */ |
897 | if (s->prev_length >= s->good_match) { |
898 | chain_length >>= 2; |
899 | } |
900 | /* Do not look for matches beyond the end of the input. This is necessary |
901 | * to make deflate deterministic. |
902 | */ |
903 | if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; |
904 | |
905 | Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); |
906 | |
907 | do { |
908 | Assert(cur_match < s->strstart, "no future"); |
909 | match = s->window + cur_match; |
910 | |
911 | /* Skip to next match if the match length cannot increase |
912 | * or if the match length is less than 2: |
913 | */ |
914 | #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) |
915 | /* This code assumes sizeof(unsigned short) == 2. Do not use |
916 | * UNALIGNED_OK if your compiler uses a different size. |
917 | */ |
918 | if (*(ushf*)(match+best_len-1) != scan_end || |
919 | *(ushf*)match != scan_start) continue; |
920 | |
921 | /* It is not necessary to compare scan[2] and match[2] since they are |
922 | * always equal when the other bytes match, given that the hash keys |
923 | * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at |
924 | * strstart+3, +5, ... up to strstart+257. We check for insufficient |
925 | * lookahead only every 4th comparison; the 128th check will be made |
926 | * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is |
927 | * necessary to put more guard bytes at the end of the window, or |
928 | * to check more often for insufficient lookahead. |
929 | */ |
930 | Assert(scan[2] == match[2], "scan[2]?"); |
931 | scan++, match++; |
932 | do { |
933 | } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
934 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
935 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
936 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
937 | scan < strend); |
938 | /* The funny "do {}" generates better code on most compilers */ |
939 | |
940 | /* Here, scan <= window+strstart+257 */ |
941 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); |
942 | if (*scan == *match) scan++; |
943 | |
944 | len = (MAX_MATCH - 1) - (int)(strend-scan); |
945 | scan = strend - (MAX_MATCH-1); |
946 | |
947 | #else /* UNALIGNED_OK */ |
948 | |
949 | if (match[best_len] != scan_end || |
950 | match[best_len-1] != scan_end1 || |
951 | *match != *scan || |
952 | *++match != scan[1]) continue; |
953 | |
954 | /* The check at best_len-1 can be removed because it will be made |
955 | * again later. (This heuristic is not always a win.) |
956 | * It is not necessary to compare scan[2] and match[2] since they |
957 | * are always equal when the other bytes match, given that |
958 | * the hash keys are equal and that HASH_BITS >= 8. |
959 | */ |
960 | scan += 2, match++; |
961 | Assert(*scan == *match, "match[2]?"); |
962 | |
963 | /* We check for insufficient lookahead only every 8th comparison; |
964 | * the 256th check will be made at strstart+258. |
965 | */ |
966 | do { |
967 | } while (*++scan == *++match && *++scan == *++match && |
968 | *++scan == *++match && *++scan == *++match && |
969 | *++scan == *++match && *++scan == *++match && |
970 | *++scan == *++match && *++scan == *++match && |
971 | scan < strend); |
972 | |
973 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); |
974 | |
975 | len = MAX_MATCH - (int)(strend - scan); |
976 | scan = strend - MAX_MATCH; |
977 | |
978 | #endif /* UNALIGNED_OK */ |
979 | |
980 | if (len > best_len) { |
981 | s->match_start = cur_match; |
982 | best_len = len; |
983 | if (len >= nice_match) break; |
984 | #ifdef UNALIGNED_OK |
985 | scan_end = *(ushf*)(scan+best_len-1); |
986 | #else |
987 | scan_end1 = scan[best_len-1]; |
988 | scan_end = scan[best_len]; |
989 | #endif |
990 | } |
991 | } while ((cur_match = prev[cur_match & wmask]) > limit |
992 | && --chain_length != 0); |
993 | |
994 | if ((uInt)best_len <= s->lookahead) return (uInt)best_len; |
995 | return s->lookahead; |
996 | } |
997 | #endif /* ASMV */ |
998 | #endif /* FASTEST */ |
999 | |
1000 | /* --------------------------------------------------------------------------- |
1001 | * Optimized version for level == 1 or strategy == Z_RLE only |
1002 | */ |
1003 | local uInt longest_match_fast(s, cur_match) |
1004 | deflate_state *s; |
1005 | IPos cur_match; /* current match */ |
1006 | { |
1007 | register Bytef *scan = s->window + s->strstart; /* current string */ |
1008 | register Bytef *match; /* matched string */ |
1009 | register int len; /* length of current match */ |
1010 | register Bytef *strend = s->window + s->strstart + MAX_MATCH; |
1011 | |
1012 | /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. |
1013 | * It is easy to get rid of this optimization if necessary. |
1014 | */ |
1015 | Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); |
1016 | |
1017 | Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); |
1018 | |
1019 | Assert(cur_match < s->strstart, "no future"); |
1020 | |
1021 | match = s->window + cur_match; |
1022 | |
1023 | /* Return failure if the match length is less than 2: |
1024 | */ |
1025 | if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; |
1026 | |
1027 | /* The check at best_len-1 can be removed because it will be made |
1028 | * again later. (This heuristic is not always a win.) |
1029 | * It is not necessary to compare scan[2] and match[2] since they |
1030 | * are always equal when the other bytes match, given that |
1031 | * the hash keys are equal and that HASH_BITS >= 8. |
1032 | */ |
1033 | scan += 2, match += 2; |
1034 | Assert(*scan == *match, "match[2]?"); |
1035 | |
1036 | /* We check for insufficient lookahead only every 8th comparison; |
1037 | * the 256th check will be made at strstart+258. |
1038 | */ |
1039 | do { |
1040 | } while (*++scan == *++match && *++scan == *++match && |
1041 | *++scan == *++match && *++scan == *++match && |
1042 | *++scan == *++match && *++scan == *++match && |
1043 | *++scan == *++match && *++scan == *++match && |
1044 | scan < strend); |
1045 | |
1046 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); |
1047 | |
1048 | len = MAX_MATCH - (int)(strend - scan); |
1049 | |
1050 | if (len < MIN_MATCH) return MIN_MATCH - 1; |
1051 | |
1052 | s->match_start = cur_match; |
1053 | return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; |
1054 | } |
1055 | |
1056 | #ifdef DEBUG |
1057 | /* =========================================================================== |
1058 | * Check that the match at match_start is indeed a match. |
1059 | */ |
1060 | local void check_match(s, start, match, length) |
1061 | deflate_state *s; |
1062 | IPos start, match; |
1063 | int length; |
1064 | { |
1065 | /* check that the match is indeed a match */ |
1066 | if (zmemcmp(s->window + match, |
1067 | s->window + start, length) != EQUAL) { |
1068 | fprintf(stderr, " start %u, match %u, length %d\n", |
1069 | start, match, length); |
1070 | do { |
1071 | fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); |
1072 | } while (--length != 0); |
1073 | z_error("invalid match"); |
1074 | } |
1075 | if (z_verbose > 1) { |
1076 | fprintf(stderr,"\\[%d,%d]", start-match, length); |
1077 | do { putc(s->window[start++], stderr); } while (--length != 0); |
1078 | } |
1079 | } |
1080 | #else |
1081 | # define check_match(s, start, match, length) |
1082 | #endif /* DEBUG */ |
1083 | |
1084 | /* =========================================================================== |
1085 | * Fill the window when the lookahead becomes insufficient. |
1086 | * Updates strstart and lookahead. |
1087 | * |
1088 | * IN assertion: lookahead < MIN_LOOKAHEAD |
1089 | * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD |
1090 | * At least one byte has been read, or avail_in == 0; reads are |
1091 | * performed for at least two bytes (required for the zip translate_eol |
1092 | * option -- not supported here). |
1093 | */ |
1094 | local void fill_window(s) |
1095 | deflate_state *s; |
1096 | { |
1097 | register unsigned n, m; |
1098 | register Posf *p; |
1099 | unsigned more; /* Amount of free space at the end of the window. */ |
1100 | uInt wsize = s->w_size; |
1101 | |
1102 | do { |
1103 | more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); |
1104 | |
1105 | /* Deal with !@#$% 64K limit: */ |
1106 | if (sizeof(int) <= 2) { |
1107 | if (more == 0 && s->strstart == 0 && s->lookahead == 0) { |
1108 | more = wsize; |
1109 | |
1110 | } else if (more == (unsigned)(-1)) { |
1111 | /* Very unlikely, but possible on 16 bit machine if |
1112 | * strstart == 0 && lookahead == 1 (input done a byte at time) |
1113 | */ |
1114 | more--; |
1115 | } |
1116 | } |
1117 | |
1118 | /* If the window is almost full and there is insufficient lookahead, |
1119 | * move the upper half to the lower one to make room in the upper half. |
1120 | */ |
1121 | if (s->strstart >= wsize+MAX_DIST(s)) { |
1122 | |
1123 | zmemcpy(s->window, s->window+wsize, (unsigned)wsize); |
1124 | s->match_start -= wsize; |
1125 | s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ |
1126 | s->block_start -= (long) wsize; |
1127 | |
1128 | /* Slide the hash table (could be avoided with 32 bit values |
1129 | at the expense of memory usage). We slide even when level == 0 |
1130 | to keep the hash table consistent if we switch back to level > 0 |
1131 | later. (Using level 0 permanently is not an optimal usage of |
1132 | zlib, so we don't care about this pathological case.) |
1133 | */ |
1134 | n = s->hash_size; |
1135 | p = &s->head[n]; |
1136 | do { |
1137 | m = *--p; |
1138 | *p = (Pos)(m >= wsize ? m-wsize : NIL); |
1139 | } while (--n); |
1140 | |
1141 | n = wsize; |
1142 | #ifndef FASTEST |
1143 | p = &s->prev[n]; |
1144 | do { |
1145 | m = *--p; |
1146 | *p = (Pos)(m >= wsize ? m-wsize : NIL); |
1147 | /* If n is not on any hash chain, prev[n] is garbage but |
1148 | * its value will never be used. |
1149 | */ |
1150 | } while (--n); |
1151 | #endif |
1152 | more += wsize; |
1153 | } |
1154 | if (s->strm->avail_in == 0) return; |
1155 | |
1156 | /* If there was no sliding: |
1157 | * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && |
1158 | * more == window_size - lookahead - strstart |
1159 | * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) |
1160 | * => more >= window_size - 2*WSIZE + 2 |
1161 | * In the BIG_MEM or MMAP case (not yet supported), |
1162 | * window_size == input_size + MIN_LOOKAHEAD && |
1163 | * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. |
1164 | * Otherwise, window_size == 2*WSIZE so more >= 2. |
1165 | * If there was sliding, more >= WSIZE. So in all cases, more >= 2. |
1166 | */ |
1167 | Assert(more >= 2, "more < 2"); |
1168 | |
1169 | n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); |
1170 | s->lookahead += n; |
1171 | |
1172 | /* Initialize the hash value now that we have some input: */ |
1173 | if (s->lookahead >= MIN_MATCH) { |
1174 | s->ins_h = s->window[s->strstart]; |
1175 | UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); |
1176 | #if MIN_MATCH != 3 |
1177 | Call UPDATE_HASH() MIN_MATCH-3 more times |
1178 | #endif |
1179 | } |
1180 | /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, |
1181 | * but this is not important since only literal bytes will be emitted. |
1182 | */ |
1183 | |
1184 | } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); |
1185 | } |
1186 | |
1187 | /* =========================================================================== |
1188 | * Flush the current block, with given end-of-file flag. |
1189 | * IN assertion: strstart is set to the end of the current match. |
1190 | */ |
1191 | #define FLUSH_BLOCK_ONLY(s, eof) { \ |
1192 | _tr_flush_block(s, (s->block_start >= 0L ? \ |
1193 | (charf *)&s->window[(unsigned)s->block_start] : \ |
1194 | (charf *)Z_NULL), \ |
1195 | (ulg)((long)s->strstart - s->block_start), \ |
1196 | (eof)); \ |
1197 | s->block_start = s->strstart; \ |
1198 | flush_pending(s->strm); \ |
1199 | Tracev((stderr,"[FLUSH]")); \ |
1200 | } |
1201 | |
1202 | /* Same but force premature exit if necessary. */ |
1203 | #define FLUSH_BLOCK(s, eof) { \ |
1204 | FLUSH_BLOCK_ONLY(s, eof); \ |
1205 | if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \ |
1206 | } |
1207 | |
1208 | /* =========================================================================== |
1209 | * Copy without compression as much as possible from the input stream, return |
1210 | * the current block state. |
1211 | * This function does not insert new strings in the dictionary since |
1212 | * uncompressible data is probably not useful. This function is used |
1213 | * only for the level=0 compression option. |
1214 | * NOTE: this function should be optimized to avoid extra copying from |
1215 | * window to pending_buf. |
1216 | */ |
1217 | local block_state deflate_stored(s, flush) |
1218 | deflate_state *s; |
1219 | int flush; |
1220 | { |
1221 | /* Stored blocks are limited to 0xffff bytes, pending_buf is limited |
1222 | * to pending_buf_size, and each stored block has a 5 byte header: |
1223 | */ |
1224 | ulg max_block_size = 0xffff; |
1225 | ulg max_start; |
1226 | |
1227 | if (max_block_size > s->pending_buf_size - 5) { |
1228 | max_block_size = s->pending_buf_size - 5; |
1229 | } |
1230 | |
1231 | /* Copy as much as possible from input to output: */ |
1232 | for (;;) { |
1233 | /* Fill the window as much as possible: */ |
1234 | if (s->lookahead <= 1) { |
1235 | |
1236 | Assert(s->strstart < s->w_size+MAX_DIST(s) || |
1237 | s->block_start >= (long)s->w_size, "slide too late"); |
1238 | |
1239 | fill_window(s); |
1240 | if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; |
1241 | |
1242 | if (s->lookahead == 0) break; /* flush the current block */ |
1243 | } |
1244 | Assert(s->block_start >= 0L, "block gone"); |
1245 | |
1246 | s->strstart += s->lookahead; |
1247 | s->lookahead = 0; |
1248 | |
1249 | /* Emit a stored block if pending_buf will be full: */ |
1250 | max_start = s->block_start + max_block_size; |
1251 | if (s->strstart == 0 || (ulg)s->strstart >= max_start) { |
1252 | /* strstart == 0 is possible when wraparound on 16-bit machine */ |
1253 | s->lookahead = (uInt)(s->strstart - max_start); |
1254 | s->strstart = (uInt)max_start; |
1255 | FLUSH_BLOCK(s, 0); |
1256 | } |
1257 | /* Flush if we may have to slide, otherwise block_start may become |
1258 | * negative and the data will be gone: |
1259 | */ |
1260 | if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { |
1261 | FLUSH_BLOCK(s, 0); |
1262 | } |
1263 | } |
1264 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1265 | return flush == Z_FINISH ? finish_done : block_done; |
1266 | } |
1267 | |
1268 | /* =========================================================================== |
1269 | * Compress as much as possible from the input stream, return the current |
1270 | * block state. |
1271 | * This function does not perform lazy evaluation of matches and inserts |
1272 | * new strings in the dictionary only for unmatched strings or for short |
1273 | * matches. It is used only for the fast compression options. |
1274 | */ |
1275 | local block_state deflate_fast(s, flush) |
1276 | deflate_state *s; |
1277 | int flush; |
1278 | { |
1279 | IPos hash_head = NIL; /* head of the hash chain */ |
1280 | int bflush; /* set if current block must be flushed */ |
1281 | |
1282 | for (;;) { |
1283 | /* Make sure that we always have enough lookahead, except |
1284 | * at the end of the input file. We need MAX_MATCH bytes |
1285 | * for the next match, plus MIN_MATCH bytes to insert the |
1286 | * string following the next match. |
1287 | */ |
1288 | if (s->lookahead < MIN_LOOKAHEAD) { |
1289 | fill_window(s); |
1290 | if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { |
1291 | return need_more; |
1292 | } |
1293 | if (s->lookahead == 0) break; /* flush the current block */ |
1294 | } |
1295 | |
1296 | /* Insert the string window[strstart .. strstart+2] in the |
1297 | * dictionary, and set hash_head to the head of the hash chain: |
1298 | */ |
1299 | if (s->lookahead >= MIN_MATCH) { |
1300 | INSERT_STRING(s, s->strstart, hash_head); |
1301 | } |
1302 | |
1303 | /* Find the longest match, discarding those <= prev_length. |
1304 | * At this point we have always match_length < MIN_MATCH |
1305 | */ |
1306 | if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { |
1307 | /* To simplify the code, we prevent matches with the string |
1308 | * of window index 0 (in particular we have to avoid a match |
1309 | * of the string with itself at the start of the input file). |
1310 | */ |
1311 | #ifdef FASTEST |
1312 | if ((s->strategy < Z_HUFFMAN_ONLY) || |
1313 | (s->strategy == Z_RLE && s->strstart - hash_head == 1)) { |
1314 | s->match_length = longest_match_fast (s, hash_head); |
1315 | } |
1316 | #else |
1317 | if (s->strategy < Z_HUFFMAN_ONLY) { |
1318 | s->match_length = longest_match (s, hash_head); |
1319 | } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { |
1320 | s->match_length = longest_match_fast (s, hash_head); |
1321 | } |
1322 | #endif |
1323 | /* longest_match() or longest_match_fast() sets match_start */ |
1324 | } |
1325 | if (s->match_length >= MIN_MATCH) { |
1326 | check_match(s, s->strstart, s->match_start, s->match_length); |
1327 | |
1328 | _tr_tally_dist(s, s->strstart - s->match_start, |
1329 | s->match_length - MIN_MATCH, bflush); |
1330 | |
1331 | s->lookahead -= s->match_length; |
1332 | |
1333 | /* Insert new strings in the hash table only if the match length |
1334 | * is not too large. This saves time but degrades compression. |
1335 | */ |
1336 | #ifndef FASTEST |
1337 | if (s->match_length <= s->max_insert_length && |
1338 | s->lookahead >= MIN_MATCH) { |
1339 | s->match_length--; /* string at strstart already in table */ |
1340 | do { |
1341 | s->strstart++; |
1342 | INSERT_STRING(s, s->strstart, hash_head); |
1343 | /* strstart never exceeds WSIZE-MAX_MATCH, so there are |
1344 | * always MIN_MATCH bytes ahead. |
1345 | */ |
1346 | } while (--s->match_length != 0); |
1347 | s->strstart++; |
1348 | } else |
1349 | #endif |
1350 | { |
1351 | s->strstart += s->match_length; |
1352 | s->match_length = 0; |
1353 | s->ins_h = s->window[s->strstart]; |
1354 | UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); |
1355 | #if MIN_MATCH != 3 |
1356 | Call UPDATE_HASH() MIN_MATCH-3 more times |
1357 | #endif |
1358 | /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not |
1359 | * matter since it will be recomputed at next deflate call. |
1360 | */ |
1361 | } |
1362 | } else { |
1363 | /* No match, output a literal byte */ |
1364 | Tracevv((stderr,"%c", s->window[s->strstart])); |
1365 | _tr_tally_lit (s, s->window[s->strstart], bflush); |
1366 | s->lookahead--; |
1367 | s->strstart++; |
1368 | } |
1369 | if (bflush) FLUSH_BLOCK(s, 0); |
1370 | } |
1371 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1372 | return flush == Z_FINISH ? finish_done : block_done; |
1373 | } |
1374 | |
1375 | #ifndef FASTEST |
1376 | /* =========================================================================== |
1377 | * Same as above, but achieves better compression. We use a lazy |
1378 | * evaluation for matches: a match is finally adopted only if there is |
1379 | * no better match at the next window position. |
1380 | */ |
1381 | local block_state deflate_slow(s, flush) |
1382 | deflate_state *s; |
1383 | int flush; |
1384 | { |
1385 | IPos hash_head = NIL; /* head of hash chain */ |
1386 | int bflush; /* set if current block must be flushed */ |
1387 | |
1388 | /* Process the input block. */ |
1389 | for (;;) { |
1390 | /* Make sure that we always have enough lookahead, except |
1391 | * at the end of the input file. We need MAX_MATCH bytes |
1392 | * for the next match, plus MIN_MATCH bytes to insert the |
1393 | * string following the next match. |
1394 | */ |
1395 | if (s->lookahead < MIN_LOOKAHEAD) { |
1396 | fill_window(s); |
1397 | if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { |
1398 | return need_more; |
1399 | } |
1400 | if (s->lookahead == 0) break; /* flush the current block */ |
1401 | } |
1402 | |
1403 | /* Insert the string window[strstart .. strstart+2] in the |
1404 | * dictionary, and set hash_head to the head of the hash chain: |
1405 | */ |
1406 | if (s->lookahead >= MIN_MATCH) { |
1407 | INSERT_STRING(s, s->strstart, hash_head); |
1408 | } |
1409 | |
1410 | /* Find the longest match, discarding those <= prev_length. |
1411 | */ |
1412 | s->prev_length = s->match_length, s->prev_match = s->match_start; |
1413 | s->match_length = MIN_MATCH-1; |
1414 | |
1415 | if (hash_head != NIL && s->prev_length < s->max_lazy_match && |
1416 | s->strstart - hash_head <= MAX_DIST(s)) { |
1417 | /* To simplify the code, we prevent matches with the string |
1418 | * of window index 0 (in particular we have to avoid a match |
1419 | * of the string with itself at the start of the input file). |
1420 | */ |
1421 | if (s->strategy < Z_HUFFMAN_ONLY) { |
1422 | s->match_length = longest_match (s, hash_head); |
1423 | } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { |
1424 | s->match_length = longest_match_fast (s, hash_head); |
1425 | } |
1426 | /* longest_match() or longest_match_fast() sets match_start */ |
1427 | |
1428 | if (s->match_length <= 5 && (s->strategy == Z_FILTERED |
1429 | #if TOO_FAR <= 32767 |
1430 | || (s->match_length == MIN_MATCH && |
1431 | s->strstart - s->match_start > TOO_FAR) |
1432 | #endif |
1433 | )) { |
1434 | |
1435 | /* If prev_match is also MIN_MATCH, match_start is garbage |
1436 | * but we will ignore the current match anyway. |
1437 | */ |
1438 | s->match_length = MIN_MATCH-1; |
1439 | } |
1440 | } |
1441 | /* If there was a match at the previous step and the current |
1442 | * match is not better, output the previous match: |
1443 | */ |
1444 | if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { |
1445 | uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; |
1446 | /* Do not insert strings in hash table beyond this. */ |
1447 | |
1448 | check_match(s, s->strstart-1, s->prev_match, s->prev_length); |
1449 | |
1450 | _tr_tally_dist(s, s->strstart -1 - s->prev_match, |
1451 | s->prev_length - MIN_MATCH, bflush); |
1452 | |
1453 | /* Insert in hash table all strings up to the end of the match. |
1454 | * strstart-1 and strstart are already inserted. If there is not |
1455 | * enough lookahead, the last two strings are not inserted in |
1456 | * the hash table. |
1457 | */ |
1458 | s->lookahead -= s->prev_length-1; |
1459 | s->prev_length -= 2; |
1460 | do { |
1461 | if (++s->strstart <= max_insert) { |
1462 | INSERT_STRING(s, s->strstart, hash_head); |
1463 | } |
1464 | } while (--s->prev_length != 0); |
1465 | s->match_available = 0; |
1466 | s->match_length = MIN_MATCH-1; |
1467 | s->strstart++; |
1468 | |
1469 | if (bflush) FLUSH_BLOCK(s, 0); |
1470 | |
1471 | } else if (s->match_available) { |
1472 | /* If there was no match at the previous position, output a |
1473 | * single literal. If there was a match but the current match |
1474 | * is longer, truncate the previous match to a single literal. |
1475 | */ |
1476 | Tracevv((stderr,"%c", s->window[s->strstart-1])); |
1477 | _tr_tally_lit(s, s->window[s->strstart-1], bflush); |
1478 | if (bflush) { |
1479 | FLUSH_BLOCK_ONLY(s, 0); |
1480 | } |
1481 | s->strstart++; |
1482 | s->lookahead--; |
1483 | if (s->strm->avail_out == 0) return need_more; |
1484 | } else { |
1485 | /* There is no previous match to compare with, wait for |
1486 | * the next step to decide. |
1487 | */ |
1488 | s->match_available = 1; |
1489 | s->strstart++; |
1490 | s->lookahead--; |
1491 | } |
1492 | } |
1493 | Assert (flush != Z_NO_FLUSH, "no flush?"); |
1494 | if (s->match_available) { |
1495 | Tracevv((stderr,"%c", s->window[s->strstart-1])); |
1496 | _tr_tally_lit(s, s->window[s->strstart-1], bflush); |
1497 | s->match_available = 0; |
1498 | } |
1499 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1500 | return flush == Z_FINISH ? finish_done : block_done; |
1501 | } |
1502 | #endif /* FASTEST */ |