1 | /* |
2 | * Copyright (c) 2008-2016 Apple Inc. All rights reserved. |
3 | * |
4 | * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ |
5 | * |
6 | * This file contains Original Code and/or Modifications of Original Code |
7 | * as defined in and that are subject to the Apple Public Source License |
8 | * Version 2.0 (the 'License'). You may not use this file except in |
9 | * compliance with the License. The rights granted to you under the License |
10 | * may not be used to create, or enable the creation or redistribution of, |
11 | * unlawful or unlicensed copies of an Apple operating system, or to |
12 | * circumvent, violate, or enable the circumvention or violation of, any |
13 | * terms of an Apple operating system software license agreement. |
14 | * |
15 | * Please obtain a copy of the License at |
16 | * http://www.opensource.apple.com/apsl/ and read it before using this file. |
17 | * |
18 | * The Original Code and all software distributed under the License are |
19 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER |
20 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, |
21 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, |
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23 | * Please see the License for the specific language governing rights and |
24 | * limitations under the License. |
25 | * |
26 | * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ |
27 | */ |
28 | /* deflate.c -- compress data using the deflation algorithm |
29 | * Copyright (C) 1995-2005 Jean-loup Gailly. |
30 | * For conditions of distribution and use, see copyright notice in zlib.h |
31 | */ |
32 | |
33 | /* |
34 | * ALGORITHM |
35 | * |
36 | * The "deflation" process depends on being able to identify portions |
37 | * of the input text which are identical to earlier input (within a |
38 | * sliding window trailing behind the input currently being processed). |
39 | * |
40 | * The most straightforward technique turns out to be the fastest for |
41 | * most input files: try all possible matches and select the longest. |
42 | * The key feature of this algorithm is that insertions into the string |
43 | * dictionary are very simple and thus fast, and deletions are avoided |
44 | * completely. Insertions are performed at each input character, whereas |
45 | * string matches are performed only when the previous match ends. So it |
46 | * is preferable to spend more time in matches to allow very fast string |
47 | * insertions and avoid deletions. The matching algorithm for small |
48 | * strings is inspired from that of Rabin & Karp. A brute force approach |
49 | * is used to find longer strings when a small match has been found. |
50 | * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze |
51 | * (by Leonid Broukhis). |
52 | * A previous version of this file used a more sophisticated algorithm |
53 | * (by Fiala and Greene) which is guaranteed to run in linear amortized |
54 | * time, but has a larger average cost, uses more memory and is patented. |
55 | * However the F&G algorithm may be faster for some highly redundant |
56 | * files if the parameter max_chain_length (described below) is too large. |
57 | * |
58 | * ACKNOWLEDGEMENTS |
59 | * |
60 | * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and |
61 | * I found it in 'freeze' written by Leonid Broukhis. |
62 | * Thanks to many people for bug reports and testing. |
63 | * |
64 | * REFERENCES |
65 | * |
66 | * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". |
67 | * Available in http://www.ietf.org/rfc/rfc1951.txt |
68 | * |
69 | * A description of the Rabin and Karp algorithm is given in the book |
70 | * "Algorithms" by R. Sedgewick, Addison-Wesley, p252. |
71 | * |
72 | * Fiala,E.R., and Greene,D.H. |
73 | * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 |
74 | * |
75 | */ |
76 | |
77 | /* @(#) $Id$ */ |
78 | |
79 | #include "deflate.h" |
80 | |
81 | const char deflate_copyright[] = |
82 | " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly " ; |
83 | /* |
84 | If you use the zlib library in a product, an acknowledgment is welcome |
85 | in the documentation of your product. If for some reason you cannot |
86 | include such an acknowledgment, I would appreciate that you keep this |
87 | copyright string in the executable of your product. |
88 | */ |
89 | |
90 | /* =========================================================================== |
91 | * Function prototypes. |
92 | */ |
93 | typedef enum { |
94 | need_more, /* block not completed, need more input or more output */ |
95 | block_done, /* block flush performed */ |
96 | finish_started, /* finish started, need only more output at next deflate */ |
97 | finish_done /* finish done, accept no more input or output */ |
98 | } block_state; |
99 | |
100 | typedef block_state (*compress_func) OF((deflate_state *s, int flush)); |
101 | /* Compression function. Returns the block state after the call. */ |
102 | |
103 | local void fill_window OF((deflate_state *s)); |
104 | local block_state deflate_stored OF((deflate_state *s, int flush)); |
105 | local block_state deflate_fast OF((deflate_state *s, int flush)); |
106 | #ifndef FASTEST |
107 | local block_state deflate_slow OF((deflate_state *s, int flush)); |
108 | #endif |
109 | local void lm_init OF((deflate_state *s)); |
110 | local void putShortMSB OF((deflate_state *s, uInt b)); |
111 | local void flush_pending OF((z_streamp strm)); |
112 | local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); |
113 | #ifndef FASTEST |
114 | #ifdef ASMV |
115 | void match_init OF((void)); /* asm code initialization */ |
116 | uInt longest_match OF((deflate_state *s, IPos cur_match)); |
117 | #else |
118 | local uInt longest_match OF((deflate_state *s, IPos cur_match)); |
119 | #endif |
120 | #endif |
121 | local uInt longest_match_fast OF((deflate_state *s, IPos cur_match)); |
122 | |
123 | #ifdef DEBUG |
124 | local void check_match OF((deflate_state *s, IPos start, IPos match, |
125 | int length)); |
126 | #endif |
127 | |
128 | /* =========================================================================== |
129 | * Local data |
130 | */ |
131 | |
132 | #define NIL 0 |
133 | /* Tail of hash chains */ |
134 | |
135 | #ifndef TOO_FAR |
136 | # define TOO_FAR 4096 |
137 | #endif |
138 | /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ |
139 | |
140 | #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) |
141 | /* Minimum amount of lookahead, except at the end of the input file. |
142 | * See deflate.c for comments about the MIN_MATCH+1. |
143 | */ |
144 | |
145 | /* Values for max_lazy_match, good_match and max_chain_length, depending on |
146 | * the desired pack level (0..9). The values given below have been tuned to |
147 | * exclude worst case performance for pathological files. Better values may be |
148 | * found for specific files. |
149 | */ |
150 | typedef struct config_s { |
151 | ush good_length; /* reduce lazy search above this match length */ |
152 | ush max_lazy; /* do not perform lazy search above this match length */ |
153 | ush nice_length; /* quit search above this match length */ |
154 | ush max_chain; |
155 | compress_func func; |
156 | } config; |
157 | |
158 | #ifdef FASTEST |
159 | local const config configuration_table[2] = { |
160 | /* good lazy nice chain */ |
161 | /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ |
162 | /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ |
163 | #else |
164 | local const config configuration_table[10] = { |
165 | /* good lazy nice chain */ |
166 | /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ |
167 | /* 1 */ {.good_length: 4, .max_lazy: 4, .nice_length: 8, .max_chain: 4, .func: deflate_fast}, /* max speed, no lazy matches */ |
168 | /* 2 */ {.good_length: 4, .max_lazy: 5, .nice_length: 16, .max_chain: 8, .func: deflate_fast}, |
169 | /* 3 */ {.good_length: 4, .max_lazy: 6, .nice_length: 32, .max_chain: 32, .func: deflate_fast}, |
170 | |
171 | /* 4 */ {.good_length: 4, .max_lazy: 4, .nice_length: 16, .max_chain: 16, .func: deflate_slow}, /* lazy matches */ |
172 | /* 5 */ {.good_length: 8, .max_lazy: 16, .nice_length: 32, .max_chain: 32, .func: deflate_slow}, |
173 | /* 6 */ {.good_length: 8, .max_lazy: 16, .nice_length: 128, .max_chain: 128, .func: deflate_slow}, |
174 | /* 7 */ {.good_length: 8, .max_lazy: 32, .nice_length: 128, .max_chain: 256, .func: deflate_slow}, |
175 | /* 8 */ {.good_length: 32, .max_lazy: 128, .nice_length: 258, .max_chain: 1024, .func: deflate_slow}, |
176 | /* 9 */ {.good_length: 32, .max_lazy: 258, .nice_length: 258, .max_chain: 4096, .func: deflate_slow}}; /* max compression */ |
177 | #endif |
178 | |
179 | /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 |
180 | * For deflate_fast() (levels <= 3) good is ignored and lazy has a different |
181 | * meaning. |
182 | */ |
183 | |
184 | #define EQUAL 0 |
185 | /* result of memcmp for equal strings */ |
186 | |
187 | #ifndef NO_DUMMY_DECL |
188 | struct static_tree_desc_s {int dummy;}; /* for buggy compilers */ |
189 | #endif |
190 | |
191 | /* =========================================================================== |
192 | * Update a hash value with the given input byte |
193 | * IN assertion: all calls to to UPDATE_HASH are made with consecutive |
194 | * input characters, so that a running hash key can be computed from the |
195 | * previous key instead of complete recalculation each time. |
196 | */ |
197 | #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) |
198 | |
199 | |
200 | /* =========================================================================== |
201 | * Insert string str in the dictionary and set match_head to the previous head |
202 | * of the hash chain (the most recent string with same hash key). Return |
203 | * the previous length of the hash chain. |
204 | * If this file is compiled with -DFASTEST, the compression level is forced |
205 | * to 1, and no hash chains are maintained. |
206 | * IN assertion: all calls to to INSERT_STRING are made with consecutive |
207 | * input characters and the first MIN_MATCH bytes of str are valid |
208 | * (except for the last MIN_MATCH-1 bytes of the input file). |
209 | */ |
210 | #ifdef FASTEST |
211 | #define INSERT_STRING(s, str, match_head) \ |
212 | (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ |
213 | match_head = s->head[s->ins_h], \ |
214 | s->head[s->ins_h] = (Pos)(str)) |
215 | #else |
216 | #define INSERT_STRING(s, str, match_head) \ |
217 | (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ |
218 | match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ |
219 | s->head[s->ins_h] = (Pos)(str)) |
220 | #endif |
221 | |
222 | /* =========================================================================== |
223 | * Initialize the hash table (avoiding 64K overflow for 16 bit systems). |
224 | * prev[] will be initialized on the fly. |
225 | */ |
226 | #define CLEAR_HASH(s) \ |
227 | s->head[s->hash_size-1] = NIL; \ |
228 | zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); |
229 | |
230 | /* ========================================================================= */ |
231 | int ZEXPORT |
232 | deflateInit_(z_streamp strm, int level, const char *version, int stream_size) |
233 | { |
234 | return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, |
235 | Z_DEFAULT_STRATEGY, version, stream_size); |
236 | /* To do: ignore strm->next_in if we use it as window */ |
237 | } |
238 | |
239 | /* ========================================================================= */ |
240 | int ZEXPORT |
241 | deflateInit2_(z_streamp strm, int level, int method, int windowBits, |
242 | int memLevel, int strategy, const char *version, |
243 | int stream_size) |
244 | { |
245 | deflate_state *s; |
246 | int wrap = 1; |
247 | static const char my_version[] = ZLIB_VERSION; |
248 | |
249 | ushf *overlay; |
250 | /* We overlay pending_buf and d_buf+l_buf. This works since the average |
251 | * output size for (length,distance) codes is <= 24 bits. |
252 | */ |
253 | |
254 | if (version == Z_NULL || version[0] != my_version[0] || |
255 | stream_size != sizeof(z_stream)) { |
256 | return Z_VERSION_ERROR; |
257 | } |
258 | if (strm == Z_NULL) return Z_STREAM_ERROR; |
259 | |
260 | strm->msg = Z_NULL; |
261 | #ifndef NO_ZCFUNCS |
262 | if (strm->zalloc == (alloc_func)0) { |
263 | strm->zalloc = zcalloc; |
264 | strm->opaque = (voidpf)0; |
265 | } |
266 | if (strm->zfree == (free_func)0) strm->zfree = zcfree; |
267 | #endif /* NO_ZCFUNCS */ |
268 | |
269 | #ifdef FASTEST |
270 | if (level != 0) level = 1; |
271 | #else |
272 | if (level == Z_DEFAULT_COMPRESSION) level = 6; |
273 | #endif |
274 | |
275 | if (windowBits < 0) { /* suppress zlib wrapper */ |
276 | wrap = 0; |
277 | windowBits = -windowBits; |
278 | } |
279 | #ifdef GZIP |
280 | else if (windowBits > 15) { |
281 | wrap = 2; /* write gzip wrapper instead */ |
282 | windowBits -= 16; |
283 | } |
284 | #endif |
285 | if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || |
286 | windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || |
287 | strategy < 0 || strategy > Z_FIXED) { |
288 | return Z_STREAM_ERROR; |
289 | } |
290 | if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ |
291 | s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); |
292 | if (s == Z_NULL) return Z_MEM_ERROR; |
293 | strm->state = (struct internal_state FAR *)s; |
294 | s->strm = strm; |
295 | |
296 | s->wrap = wrap; |
297 | s->gzhead = Z_NULL; |
298 | s->w_bits = windowBits; |
299 | s->w_size = 1 << s->w_bits; |
300 | s->w_mask = s->w_size - 1; |
301 | |
302 | s->hash_bits = memLevel + 7; |
303 | s->hash_size = 1 << s->hash_bits; |
304 | s->hash_mask = s->hash_size - 1; |
305 | s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); |
306 | |
307 | s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); |
308 | s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); |
309 | s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); |
310 | |
311 | s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ |
312 | |
313 | overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); |
314 | s->pending_buf = (uchf *) overlay; |
315 | s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); |
316 | |
317 | if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || |
318 | s->pending_buf == Z_NULL) { |
319 | s->status = FINISH_STATE; |
320 | strm->msg = (char*)ERR_MSG(Z_MEM_ERROR); |
321 | deflateEnd (strm); |
322 | return Z_MEM_ERROR; |
323 | } |
324 | s->d_buf = overlay + s->lit_bufsize/sizeof(ush); |
325 | s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; |
326 | |
327 | s->level = level; |
328 | s->strategy = strategy; |
329 | s->method = (Byte)method; |
330 | |
331 | return deflateReset(strm); |
332 | } |
333 | |
334 | /* ========================================================================= */ |
335 | int ZEXPORT |
336 | deflateSetDictionary(z_streamp strm, const Bytef *dictionary, uInt dictLength) |
337 | { |
338 | deflate_state *s; |
339 | uInt length = dictLength; |
340 | uInt n; |
341 | IPos hash_head = 0; |
342 | |
343 | if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL || |
344 | strm->state->wrap == 2 || |
345 | (strm->state->wrap == 1 && strm->state->status != INIT_STATE)) |
346 | return Z_STREAM_ERROR; |
347 | |
348 | s = strm->state; |
349 | if (s->wrap) |
350 | strm->adler = adler32(adler: strm->adler, buf: dictionary, len: dictLength); |
351 | |
352 | if (length < MIN_MATCH) return Z_OK; |
353 | if (length > MAX_DIST(s)) { |
354 | length = MAX_DIST(s); |
355 | dictionary += dictLength - length; /* use the tail of the dictionary */ |
356 | } |
357 | zmemcpy(dst: s->window, src: dictionary, n: length); |
358 | s->strstart = length; |
359 | s->block_start = (long)length; |
360 | |
361 | /* Insert all strings in the hash table (except for the last two bytes). |
362 | * s->lookahead stays null, so s->ins_h will be recomputed at the next |
363 | * call of fill_window. |
364 | */ |
365 | s->ins_h = s->window[0]; |
366 | UPDATE_HASH(s, s->ins_h, s->window[1]); |
367 | for (n = 0; n <= length - MIN_MATCH; n++) { |
368 | INSERT_STRING(s, n, hash_head); |
369 | } |
370 | if (hash_head) hash_head = 0; /* to make compiler happy */ |
371 | return Z_OK; |
372 | } |
373 | |
374 | /* ========================================================================= */ |
375 | |
376 | ZEXTERN int ZEXPORT |
377 | deflateResetWithIO(z_streamp strm, z_input_func zinput, z_output_func zoutput) |
378 | { |
379 | int zerr; |
380 | |
381 | zerr = deflateReset(strm); |
382 | if (Z_OK != zerr) return (zerr); |
383 | strm->state->zinput = zinput; |
384 | strm->state->zoutput = zoutput; |
385 | return Z_OK; |
386 | } |
387 | |
388 | /* ========================================================================= */ |
389 | |
390 | int ZEXPORT |
391 | deflateReset(z_streamp strm) |
392 | { |
393 | deflate_state *s; |
394 | |
395 | if (strm == Z_NULL || strm->state == Z_NULL || |
396 | strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { |
397 | return Z_STREAM_ERROR; |
398 | } |
399 | |
400 | strm->total_in = strm->total_out = 0; |
401 | strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ |
402 | strm->data_type = Z_UNKNOWN; |
403 | |
404 | s = (deflate_state *)strm->state; |
405 | s->pending = 0; |
406 | s->pending_out = s->pending_buf; |
407 | s->zinput = &read_buf; |
408 | s->zoutput = NULL; |
409 | |
410 | if (s->wrap < 0) { |
411 | s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ |
412 | } |
413 | s->status = s->wrap ? INIT_STATE : BUSY_STATE; |
414 | strm->adler = |
415 | #ifdef GZIP |
416 | s->wrap == 2 ? z_crc32(crc: 0L, Z_NULL, len: 0) : |
417 | #endif |
418 | adler32(adler: 0L, Z_NULL, len: 0); |
419 | s->last_flush = Z_NO_FLUSH; |
420 | |
421 | _tr_init(s); |
422 | lm_init(s); |
423 | |
424 | return Z_OK; |
425 | } |
426 | |
427 | /* ========================================================================= */ |
428 | int ZEXPORT |
429 | (z_streamp strm, gz_headerp head) |
430 | { |
431 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
432 | if (strm->state->wrap != 2) return Z_STREAM_ERROR; |
433 | strm->state->gzhead = head; |
434 | return Z_OK; |
435 | } |
436 | |
437 | /* ========================================================================= */ |
438 | int ZEXPORT |
439 | deflatePrime(z_streamp strm, int bits, int value) |
440 | { |
441 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
442 | strm->state->bi_valid = bits; |
443 | strm->state->bi_buf = (ush)(value & ((1 << bits) - 1)); |
444 | return Z_OK; |
445 | } |
446 | |
447 | /* ========================================================================= */ |
448 | int ZEXPORT |
449 | deflateParams(z_streamp strm, int level, int strategy) |
450 | { |
451 | deflate_state *s; |
452 | compress_func func; |
453 | int err = Z_OK; |
454 | |
455 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
456 | s = strm->state; |
457 | |
458 | #ifdef FASTEST |
459 | if (level != 0) level = 1; |
460 | #else |
461 | if (level == Z_DEFAULT_COMPRESSION) level = 6; |
462 | #endif |
463 | if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { |
464 | return Z_STREAM_ERROR; |
465 | } |
466 | func = configuration_table[s->level].func; |
467 | |
468 | if (func != configuration_table[level].func && strm->total_in != 0) { |
469 | /* Flush the last buffer: */ |
470 | err = deflate(strm, Z_PARTIAL_FLUSH); |
471 | } |
472 | if (s->level != level) { |
473 | s->level = level; |
474 | s->max_lazy_match = configuration_table[level].max_lazy; |
475 | s->good_match = configuration_table[level].good_length; |
476 | s->nice_match = configuration_table[level].nice_length; |
477 | s->max_chain_length = configuration_table[level].max_chain; |
478 | } |
479 | s->strategy = strategy; |
480 | return err; |
481 | } |
482 | |
483 | /* ========================================================================= */ |
484 | int ZEXPORT |
485 | deflateTune(z_streamp strm, int good_length, int max_lazy, int nice_length, |
486 | int max_chain) |
487 | { |
488 | deflate_state *s; |
489 | |
490 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
491 | s = strm->state; |
492 | s->good_match = good_length; |
493 | s->max_lazy_match = max_lazy; |
494 | s->nice_match = nice_length; |
495 | s->max_chain_length = max_chain; |
496 | return Z_OK; |
497 | } |
498 | |
499 | /* ========================================================================= |
500 | * For the default windowBits of 15 and memLevel of 8, this function returns |
501 | * a close to exact, as well as small, upper bound on the compressed size. |
502 | * They are coded as constants here for a reason--if the #define's are |
503 | * changed, then this function needs to be changed as well. The return |
504 | * value for 15 and 8 only works for those exact settings. |
505 | * |
506 | * For any setting other than those defaults for windowBits and memLevel, |
507 | * the value returned is a conservative worst case for the maximum expansion |
508 | * resulting from using fixed blocks instead of stored blocks, which deflate |
509 | * can emit on compressed data for some combinations of the parameters. |
510 | * |
511 | * This function could be more sophisticated to provide closer upper bounds |
512 | * for every combination of windowBits and memLevel, as well as wrap. |
513 | * But even the conservative upper bound of about 14% expansion does not |
514 | * seem onerous for output buffer allocation. |
515 | */ |
516 | uLong ZEXPORT |
517 | deflateBound(z_streamp strm, uLong sourceLen) |
518 | { |
519 | deflate_state *s; |
520 | uLong destLen; |
521 | |
522 | /* conservative upper bound */ |
523 | destLen = sourceLen + |
524 | ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11; |
525 | |
526 | /* if can't get parameters, return conservative bound */ |
527 | if (strm == Z_NULL || strm->state == Z_NULL) |
528 | return destLen; |
529 | |
530 | /* if not default parameters, return conservative bound */ |
531 | s = strm->state; |
532 | if (s->w_bits != 15 || s->hash_bits != 8 + 7) |
533 | return destLen; |
534 | |
535 | /* default settings: return tight bound for that case */ |
536 | return compressBound(sourceLen); |
537 | } |
538 | |
539 | /* ========================================================================= |
540 | * Put a short in the pending buffer. The 16-bit value is put in MSB order. |
541 | * IN assertion: the stream state is correct and there is enough room in |
542 | * pending_buf. |
543 | */ |
544 | local void |
545 | putShortMSB(deflate_state *s, uInt b) |
546 | { |
547 | put_byte(s, (Byte)(b >> 8)); |
548 | put_byte(s, (Byte)(b & 0xff)); |
549 | } |
550 | |
551 | /* ========================================================================= |
552 | * Flush as much pending output as possible. All deflate() output goes |
553 | * through this function so some applications may wish to modify it |
554 | * to avoid allocating a large strm->next_out buffer and copying into it. |
555 | * (See also read_buf()). |
556 | */ |
557 | local void |
558 | flush_pending(z_streamp strm) |
559 | { |
560 | unsigned len = strm->state->pending; |
561 | |
562 | if (strm->state->zoutput) { |
563 | len = (*strm->state->zoutput)(strm, strm->state->pending_out, len); |
564 | } else { |
565 | if (len > strm->avail_out) len = strm->avail_out; |
566 | if (len == 0) return; |
567 | zmemcpy(dst: strm->next_out, src: strm->state->pending_out, n: len); |
568 | strm->next_out += len; |
569 | strm->avail_out -= len; |
570 | } |
571 | |
572 | strm->state->pending_out += len; |
573 | strm->total_out += len; |
574 | strm->state->pending -= len; |
575 | if (strm->state->pending == 0) { |
576 | strm->state->pending_out = strm->state->pending_buf; |
577 | } |
578 | } |
579 | |
580 | /* ========================================================================= */ |
581 | int ZEXPORT |
582 | deflate(z_streamp strm, int flush) |
583 | { |
584 | int old_flush; /* value of flush param for previous deflate call */ |
585 | deflate_state *s; |
586 | |
587 | if (strm == Z_NULL || strm->state == Z_NULL || |
588 | flush > Z_FINISH || flush < 0) { |
589 | return Z_STREAM_ERROR; |
590 | } |
591 | s = strm->state; |
592 | |
593 | if (strm->next_out == Z_NULL || |
594 | (strm->next_in == Z_NULL && strm->avail_in != 0) || |
595 | (s->status == FINISH_STATE && flush != Z_FINISH)) { |
596 | ERR_RETURN(strm, Z_STREAM_ERROR); |
597 | } |
598 | if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); |
599 | |
600 | s->strm = strm; /* just in case */ |
601 | old_flush = s->last_flush; |
602 | s->last_flush = flush; |
603 | |
604 | /* Write the header */ |
605 | if (s->status == INIT_STATE) { |
606 | #ifdef GZIP |
607 | if (s->wrap == 2) { |
608 | strm->adler = z_crc32(crc: 0L, Z_NULL, len: 0); |
609 | put_byte(s, 31); |
610 | put_byte(s, 139); |
611 | put_byte(s, 8); |
612 | if (s->gzhead == NULL) { |
613 | put_byte(s, 0); |
614 | put_byte(s, 0); |
615 | put_byte(s, 0); |
616 | put_byte(s, 0); |
617 | put_byte(s, 0); |
618 | put_byte(s, s->level == 9 ? 2 : |
619 | (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? |
620 | 4 : 0)); |
621 | put_byte(s, OS_CODE); |
622 | s->status = BUSY_STATE; |
623 | } |
624 | else { |
625 | put_byte(s, (s->gzhead->text ? 1 : 0) + |
626 | (s->gzhead->hcrc ? 2 : 0) + |
627 | (s->gzhead->extra == Z_NULL ? 0 : 4) + |
628 | (s->gzhead->name == Z_NULL ? 0 : 8) + |
629 | (s->gzhead->comment == Z_NULL ? 0 : 16) |
630 | ); |
631 | put_byte(s, (Byte)(s->gzhead->time & 0xff)); |
632 | put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); |
633 | put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); |
634 | put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); |
635 | put_byte(s, s->level == 9 ? 2 : |
636 | (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? |
637 | 4 : 0)); |
638 | put_byte(s, s->gzhead->os & 0xff); |
639 | if (s->gzhead->extra != NULL) { |
640 | put_byte(s, s->gzhead->extra_len & 0xff); |
641 | put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); |
642 | } |
643 | if (s->gzhead->hcrc) |
644 | strm->adler = z_crc32(crc: strm->adler, buf: s->pending_buf, |
645 | len: s->pending); |
646 | s->gzindex = 0; |
647 | s->status = EXTRA_STATE; |
648 | } |
649 | } |
650 | else |
651 | #endif |
652 | { |
653 | uInt = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; |
654 | uInt level_flags; |
655 | |
656 | if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) |
657 | level_flags = 0; |
658 | else if (s->level < 6) |
659 | level_flags = 1; |
660 | else if (s->level == 6) |
661 | level_flags = 2; |
662 | else |
663 | level_flags = 3; |
664 | header |= (level_flags << 6); |
665 | if (s->strstart != 0) header |= PRESET_DICT; |
666 | header += 31 - (header % 31); |
667 | |
668 | s->status = BUSY_STATE; |
669 | putShortMSB(s, b: header); |
670 | |
671 | /* Save the adler32 of the preset dictionary: */ |
672 | if (s->strstart != 0) { |
673 | putShortMSB(s, b: (uInt)(strm->adler >> 16)); |
674 | putShortMSB(s, b: (uInt)(strm->adler & 0xffff)); |
675 | } |
676 | strm->adler = adler32(adler: 0L, Z_NULL, len: 0); |
677 | } |
678 | } |
679 | #ifdef GZIP |
680 | if (s->status == EXTRA_STATE) { |
681 | if (s->gzhead->extra != NULL) { |
682 | uInt beg = s->pending; /* start of bytes to update crc */ |
683 | |
684 | while (s->gzindex < (s->gzhead->extra_len & 0xffff)) { |
685 | if (s->pending == s->pending_buf_size) { |
686 | if (s->gzhead->hcrc && s->pending > beg) |
687 | strm->adler = z_crc32(crc: strm->adler, buf: s->pending_buf + beg, |
688 | len: s->pending - beg); |
689 | flush_pending(strm); |
690 | beg = s->pending; |
691 | if (s->pending == s->pending_buf_size) |
692 | break; |
693 | } |
694 | put_byte(s, s->gzhead->extra[s->gzindex]); |
695 | s->gzindex++; |
696 | } |
697 | if (s->gzhead->hcrc && s->pending > beg) |
698 | strm->adler = z_crc32(crc: strm->adler, buf: s->pending_buf + beg, |
699 | len: s->pending - beg); |
700 | if (s->gzindex == s->gzhead->extra_len) { |
701 | s->gzindex = 0; |
702 | s->status = NAME_STATE; |
703 | } |
704 | } |
705 | else |
706 | s->status = NAME_STATE; |
707 | } |
708 | if (s->status == NAME_STATE) { |
709 | if (s->gzhead->name != NULL) { |
710 | uInt beg = s->pending; /* start of bytes to update crc */ |
711 | Bytef val; |
712 | |
713 | do { |
714 | if (s->pending == s->pending_buf_size) { |
715 | if (s->gzhead->hcrc && s->pending > beg) |
716 | strm->adler = z_crc32(crc: strm->adler, buf: s->pending_buf + beg, |
717 | len: s->pending - beg); |
718 | flush_pending(strm); |
719 | beg = s->pending; |
720 | if (s->pending == s->pending_buf_size) { |
721 | val = 1; |
722 | break; |
723 | } |
724 | } |
725 | val = s->gzhead->name[s->gzindex++]; |
726 | put_byte(s, val); |
727 | } while (val != 0); |
728 | if (s->gzhead->hcrc && s->pending > beg) |
729 | strm->adler = z_crc32(crc: strm->adler, buf: s->pending_buf + beg, |
730 | len: s->pending - beg); |
731 | if (val == 0) { |
732 | s->gzindex = 0; |
733 | s->status = COMMENT_STATE; |
734 | } |
735 | } |
736 | else |
737 | s->status = COMMENT_STATE; |
738 | } |
739 | if (s->status == COMMENT_STATE) { |
740 | if (s->gzhead->comment != NULL) { |
741 | uInt beg = s->pending; /* start of bytes to update crc */ |
742 | Bytef val; |
743 | |
744 | do { |
745 | if (s->pending == s->pending_buf_size) { |
746 | if (s->gzhead->hcrc && s->pending > beg) |
747 | strm->adler = z_crc32(crc: strm->adler, buf: s->pending_buf + beg, |
748 | len: s->pending - beg); |
749 | flush_pending(strm); |
750 | beg = s->pending; |
751 | if (s->pending == s->pending_buf_size) { |
752 | val = 1; |
753 | break; |
754 | } |
755 | } |
756 | val = s->gzhead->comment[s->gzindex++]; |
757 | put_byte(s, val); |
758 | } while (val != 0); |
759 | if (s->gzhead->hcrc && s->pending > beg) |
760 | strm->adler = z_crc32(crc: strm->adler, buf: s->pending_buf + beg, |
761 | len: s->pending - beg); |
762 | if (val == 0) |
763 | s->status = HCRC_STATE; |
764 | } |
765 | else |
766 | s->status = HCRC_STATE; |
767 | } |
768 | if (s->status == HCRC_STATE) { |
769 | if (s->gzhead->hcrc) { |
770 | if (s->pending + 2 > s->pending_buf_size) |
771 | flush_pending(strm); |
772 | if (s->pending + 2 <= s->pending_buf_size) { |
773 | put_byte(s, (Byte)(strm->adler & 0xff)); |
774 | put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); |
775 | strm->adler = z_crc32(crc: 0L, Z_NULL, len: 0); |
776 | s->status = BUSY_STATE; |
777 | } |
778 | } |
779 | else |
780 | s->status = BUSY_STATE; |
781 | } |
782 | #endif |
783 | |
784 | /* Flush as much pending output as possible */ |
785 | if (s->pending != 0) { |
786 | flush_pending(strm); |
787 | if (strm->avail_out == 0) { |
788 | /* Since avail_out is 0, deflate will be called again with |
789 | * more output space, but possibly with both pending and |
790 | * avail_in equal to zero. There won't be anything to do, |
791 | * but this is not an error situation so make sure we |
792 | * return OK instead of BUF_ERROR at next call of deflate: |
793 | */ |
794 | s->last_flush = -1; |
795 | return Z_OK; |
796 | } |
797 | |
798 | /* Make sure there is something to do and avoid duplicate consecutive |
799 | * flushes. For repeated and useless calls with Z_FINISH, we keep |
800 | * returning Z_STREAM_END instead of Z_BUF_ERROR. |
801 | */ |
802 | } else if (strm->avail_in == 0 && flush <= old_flush && |
803 | flush != Z_FINISH) { |
804 | ERR_RETURN(strm, Z_BUF_ERROR); |
805 | } |
806 | |
807 | /* User must not provide more input after the first FINISH: */ |
808 | if (s->status == FINISH_STATE && strm->avail_in != 0) { |
809 | ERR_RETURN(strm, Z_BUF_ERROR); |
810 | } |
811 | |
812 | /* Start a new block or continue the current one. |
813 | */ |
814 | if (strm->avail_in != 0 || s->lookahead != 0 || |
815 | (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { |
816 | block_state bstate; |
817 | |
818 | bstate = (*(configuration_table[s->level].func))(s, flush); |
819 | |
820 | if (bstate == finish_started || bstate == finish_done) { |
821 | s->status = FINISH_STATE; |
822 | } |
823 | if (bstate == need_more || bstate == finish_started) { |
824 | if (strm->avail_out == 0) { |
825 | s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ |
826 | } |
827 | return Z_OK; |
828 | /* If flush != Z_NO_FLUSH && avail_out == 0, the next call |
829 | * of deflate should use the same flush parameter to make sure |
830 | * that the flush is complete. So we don't have to output an |
831 | * empty block here, this will be done at next call. This also |
832 | * ensures that for a very small output buffer, we emit at most |
833 | * one empty block. |
834 | */ |
835 | } |
836 | if (bstate == block_done) { |
837 | if (flush == Z_PARTIAL_FLUSH) { |
838 | _tr_align(s); |
839 | } else { /* FULL_FLUSH or SYNC_FLUSH */ |
840 | _tr_stored_block(s, buf: (char*)0, stored_len: 0L, eof: 0); |
841 | /* For a full flush, this empty block will be recognized |
842 | * as a special marker by inflate_sync(). |
843 | */ |
844 | if (flush == Z_FULL_FLUSH) { |
845 | CLEAR_HASH(s); /* forget history */ |
846 | } |
847 | } |
848 | flush_pending(strm); |
849 | if (strm->avail_out == 0) { |
850 | s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ |
851 | return Z_OK; |
852 | } |
853 | } |
854 | } |
855 | Assert(strm->avail_out > 0, "bug2" ); |
856 | |
857 | if (flush != Z_FINISH) return Z_OK; |
858 | if (s->wrap <= 0) return Z_STREAM_END; |
859 | |
860 | /* Write the trailer */ |
861 | #ifdef GZIP |
862 | if (s->wrap == 2) { |
863 | put_byte(s, (Byte)(strm->adler & 0xff)); |
864 | put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); |
865 | put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); |
866 | put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); |
867 | put_byte(s, (Byte)(strm->total_in & 0xff)); |
868 | put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); |
869 | put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); |
870 | put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); |
871 | } |
872 | else |
873 | #endif |
874 | { |
875 | putShortMSB(s, b: (uInt)(strm->adler >> 16)); |
876 | putShortMSB(s, b: (uInt)(strm->adler & 0xffff)); |
877 | } |
878 | flush_pending(strm); |
879 | /* If avail_out is zero, the application will call deflate again |
880 | * to flush the rest. |
881 | */ |
882 | if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ |
883 | return s->pending != 0 ? Z_OK : Z_STREAM_END; |
884 | } |
885 | |
886 | /* ========================================================================= */ |
887 | int ZEXPORT |
888 | deflateEnd(z_streamp strm) |
889 | { |
890 | int status; |
891 | |
892 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
893 | |
894 | status = strm->state->status; |
895 | if (status != INIT_STATE && |
896 | status != EXTRA_STATE && |
897 | status != NAME_STATE && |
898 | status != COMMENT_STATE && |
899 | status != HCRC_STATE && |
900 | status != BUSY_STATE && |
901 | status != FINISH_STATE) { |
902 | return Z_STREAM_ERROR; |
903 | } |
904 | |
905 | /* Deallocate in reverse order of allocations: */ |
906 | TRY_FREE(strm, strm->state->pending_buf); |
907 | TRY_FREE(strm, strm->state->head); |
908 | TRY_FREE(strm, strm->state->prev); |
909 | TRY_FREE(strm, strm->state->window); |
910 | |
911 | ZFREE(strm, strm->state); |
912 | strm->state = Z_NULL; |
913 | |
914 | return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; |
915 | } |
916 | |
917 | /* ========================================================================= |
918 | * Copy the source state to the destination state. |
919 | * To simplify the source, this is not supported for 16-bit MSDOS (which |
920 | * doesn't have enough memory anyway to duplicate compression states). |
921 | */ |
922 | int ZEXPORT |
923 | deflateCopy(z_streamp dest, z_streamp source) |
924 | { |
925 | #ifdef MAXSEG_64K |
926 | return Z_STREAM_ERROR; |
927 | #else |
928 | deflate_state *ds; |
929 | deflate_state *ss; |
930 | ushf *overlay; |
931 | |
932 | |
933 | if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { |
934 | return Z_STREAM_ERROR; |
935 | } |
936 | |
937 | ss = source->state; |
938 | |
939 | zmemcpy(dst: dest, src: source, n: sizeof(z_stream)); |
940 | |
941 | ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); |
942 | if (ds == Z_NULL) return Z_MEM_ERROR; |
943 | dest->state = (struct internal_state FAR *) ds; |
944 | zmemcpy(dst: ds, src: ss, n: sizeof(deflate_state)); |
945 | ds->strm = dest; |
946 | |
947 | ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); |
948 | ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); |
949 | ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); |
950 | overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); |
951 | ds->pending_buf = (uchf *) overlay; |
952 | |
953 | if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || |
954 | ds->pending_buf == Z_NULL) { |
955 | deflateEnd (strm: dest); |
956 | return Z_MEM_ERROR; |
957 | } |
958 | /* following zmemcpy do not work for 16-bit MSDOS */ |
959 | zmemcpy(dst: ds->window, src: ss->window, n: ds->w_size * 2 * sizeof(Byte)); |
960 | zmemcpy(dst: ds->prev, src: ss->prev, n: ds->w_size * sizeof(Pos)); |
961 | zmemcpy(dst: ds->head, src: ss->head, n: ds->hash_size * sizeof(Pos)); |
962 | zmemcpy(dst: ds->pending_buf, src: ss->pending_buf, n: (uInt)ds->pending_buf_size); |
963 | |
964 | ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); |
965 | ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); |
966 | ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; |
967 | |
968 | ds->l_desc.dyn_tree = ds->dyn_ltree; |
969 | ds->d_desc.dyn_tree = ds->dyn_dtree; |
970 | ds->bl_desc.dyn_tree = ds->bl_tree; |
971 | |
972 | return Z_OK; |
973 | #endif /* MAXSEG_64K */ |
974 | } |
975 | |
976 | /* =========================================================================== |
977 | * Read a new buffer from the current input stream, update the adler32 |
978 | * and total number of bytes read. All deflate() input goes through |
979 | * this function so some applications may wish to modify it to avoid |
980 | * allocating a large strm->next_in buffer and copying from it. |
981 | * (See also flush_pending()). |
982 | */ |
983 | local int |
984 | read_buf(z_streamp strm, Bytef *buf, unsigned size) |
985 | { |
986 | unsigned len = strm->avail_in; |
987 | |
988 | if (len > size) len = size; |
989 | if (len == 0) return 0; |
990 | |
991 | strm->avail_in -= len; |
992 | |
993 | if (strm->state->wrap == 1) { |
994 | strm->adler = adler32(adler: strm->adler, buf: strm->next_in, len); |
995 | } |
996 | #ifdef GZIP |
997 | else if (strm->state->wrap == 2) { |
998 | strm->adler = z_crc32(crc: strm->adler, buf: strm->next_in, len); |
999 | } |
1000 | #endif |
1001 | zmemcpy(dst: buf, src: strm->next_in, n: len); |
1002 | strm->next_in += len; |
1003 | strm->total_in += len; |
1004 | |
1005 | return (int)len; |
1006 | } |
1007 | |
1008 | /* =========================================================================== |
1009 | * Initialize the "longest match" routines for a new zlib stream |
1010 | */ |
1011 | local void |
1012 | lm_init(deflate_state *s) |
1013 | { |
1014 | s->window_size = (ulg)2L*s->w_size; |
1015 | |
1016 | CLEAR_HASH(s); |
1017 | |
1018 | /* Set the default configuration parameters: |
1019 | */ |
1020 | s->max_lazy_match = configuration_table[s->level].max_lazy; |
1021 | s->good_match = configuration_table[s->level].good_length; |
1022 | s->nice_match = configuration_table[s->level].nice_length; |
1023 | s->max_chain_length = configuration_table[s->level].max_chain; |
1024 | |
1025 | s->strstart = 0; |
1026 | s->block_start = 0L; |
1027 | s->lookahead = 0; |
1028 | s->match_length = s->prev_length = MIN_MATCH-1; |
1029 | s->match_available = 0; |
1030 | s->ins_h = 0; |
1031 | #ifndef FASTEST |
1032 | #ifdef ASMV |
1033 | match_init(); /* initialize the asm code */ |
1034 | #endif |
1035 | #endif |
1036 | } |
1037 | |
1038 | #ifndef FASTEST |
1039 | /* =========================================================================== |
1040 | * Set match_start to the longest match starting at the given string and |
1041 | * return its length. Matches shorter or equal to prev_length are discarded, |
1042 | * in which case the result is equal to prev_length and match_start is |
1043 | * garbage. |
1044 | * IN assertions: cur_match is the head of the hash chain for the current |
1045 | * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 |
1046 | * OUT assertion: the match length is not greater than s->lookahead. |
1047 | */ |
1048 | #ifndef ASMV |
1049 | /* For 80x86 and 680x0, an optimized version will be provided in match.asm or |
1050 | * match.S. The code will be functionally equivalent. |
1051 | * @param cur_match current match |
1052 | */ |
1053 | local uInt |
1054 | longest_match(deflate_state *s, IPos cur_match) |
1055 | { |
1056 | unsigned chain_length = s->max_chain_length;/* max hash chain length */ |
1057 | Bytef *scan = s->window + s->strstart; /* current string */ |
1058 | Bytef *match; /* matched string */ |
1059 | int len; /* length of current match */ |
1060 | int best_len = s->prev_length; /* best match length so far */ |
1061 | int nice_match = s->nice_match; /* stop if match long enough */ |
1062 | IPos limit = s->strstart > (IPos)MAX_DIST(s) ? |
1063 | s->strstart - (IPos)MAX_DIST(s) : NIL; |
1064 | /* Stop when cur_match becomes <= limit. To simplify the code, |
1065 | * we prevent matches with the string of window index 0. |
1066 | */ |
1067 | Posf *prev = s->prev; |
1068 | uInt wmask = s->w_mask; |
1069 | |
1070 | #ifdef UNALIGNED_OK |
1071 | /* Compare two bytes at a time. Note: this is not always beneficial. |
1072 | * Try with and without -DUNALIGNED_OK to check. |
1073 | */ |
1074 | Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; |
1075 | ush scan_start = *(ushf*)scan; |
1076 | ush scan_end = *(ushf*)(scan+best_len-1); |
1077 | #else |
1078 | Bytef *strend = s->window + s->strstart + MAX_MATCH; |
1079 | Byte scan_end1 = scan[best_len-1]; |
1080 | Byte scan_end = scan[best_len]; |
1081 | #endif |
1082 | |
1083 | /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. |
1084 | * It is easy to get rid of this optimization if necessary. |
1085 | */ |
1086 | Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever" ); |
1087 | |
1088 | /* Do not waste too much time if we already have a good match: */ |
1089 | if (s->prev_length >= s->good_match) { |
1090 | chain_length >>= 2; |
1091 | } |
1092 | /* Do not look for matches beyond the end of the input. This is necessary |
1093 | * to make deflate deterministic. |
1094 | */ |
1095 | if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; |
1096 | |
1097 | Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead" ); |
1098 | |
1099 | do { |
1100 | Assert(cur_match < s->strstart, "no future" ); |
1101 | match = s->window + cur_match; |
1102 | |
1103 | /* Skip to next match if the match length cannot increase |
1104 | * or if the match length is less than 2. Note that the checks below |
1105 | * for insufficient lookahead only occur occasionally for performance |
1106 | * reasons. Therefore uninitialized memory will be accessed, and |
1107 | * conditional jumps will be made that depend on those values. |
1108 | * However the length of the match is limited to the lookahead, so |
1109 | * the output of deflate is not affected by the uninitialized values. |
1110 | */ |
1111 | #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) |
1112 | /* This code assumes sizeof(unsigned short) == 2. Do not use |
1113 | * UNALIGNED_OK if your compiler uses a different size. |
1114 | */ |
1115 | if (*(ushf*)(match+best_len-1) != scan_end || |
1116 | *(ushf*)match != scan_start) continue; |
1117 | |
1118 | /* It is not necessary to compare scan[2] and match[2] since they are |
1119 | * always equal when the other bytes match, given that the hash keys |
1120 | * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at |
1121 | * strstart+3, +5, ... up to strstart+257. We check for insufficient |
1122 | * lookahead only every 4th comparison; the 128th check will be made |
1123 | * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is |
1124 | * necessary to put more guard bytes at the end of the window, or |
1125 | * to check more often for insufficient lookahead. |
1126 | */ |
1127 | Assert(scan[2] == match[2], "scan[2]?" ); |
1128 | scan++, match++; |
1129 | do { |
1130 | } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
1131 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
1132 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
1133 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
1134 | scan < strend); |
1135 | /* The funny "do {}" generates better code on most compilers */ |
1136 | |
1137 | /* Here, scan <= window+strstart+257 */ |
1138 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan" ); |
1139 | if (*scan == *match) scan++; |
1140 | |
1141 | len = (MAX_MATCH - 1) - (int)(strend-scan); |
1142 | scan = strend - (MAX_MATCH-1); |
1143 | |
1144 | #else /* UNALIGNED_OK */ |
1145 | |
1146 | if (match[best_len] != scan_end || |
1147 | match[best_len-1] != scan_end1 || |
1148 | *match != *scan || |
1149 | *++match != scan[1]) continue; |
1150 | |
1151 | /* The check at best_len-1 can be removed because it will be made |
1152 | * again later. (This heuristic is not always a win.) |
1153 | * It is not necessary to compare scan[2] and match[2] since they |
1154 | * are always equal when the other bytes match, given that |
1155 | * the hash keys are equal and that HASH_BITS >= 8. |
1156 | */ |
1157 | scan += 2; |
1158 | match++; |
1159 | Assert(*scan == *match, "match[2]?" ); |
1160 | |
1161 | /* We check for insufficient lookahead only every 8th comparison; |
1162 | * the 256th check will be made at strstart+258. |
1163 | */ |
1164 | do { |
1165 | } while (*++scan == *++match && *++scan == *++match && |
1166 | *++scan == *++match && *++scan == *++match && |
1167 | *++scan == *++match && *++scan == *++match && |
1168 | *++scan == *++match && *++scan == *++match && |
1169 | scan < strend); |
1170 | |
1171 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan" ); |
1172 | |
1173 | len = MAX_MATCH - (int)(strend - scan); |
1174 | scan = strend - MAX_MATCH; |
1175 | |
1176 | #endif /* UNALIGNED_OK */ |
1177 | |
1178 | if (len > best_len) { |
1179 | s->match_start = cur_match; |
1180 | best_len = len; |
1181 | if (len >= nice_match) break; |
1182 | #ifdef UNALIGNED_OK |
1183 | scan_end = *(ushf*)(scan+best_len-1); |
1184 | #else |
1185 | scan_end1 = scan[best_len-1]; |
1186 | scan_end = scan[best_len]; |
1187 | #endif |
1188 | } |
1189 | } while ((cur_match = prev[cur_match & wmask]) > limit |
1190 | && --chain_length != 0); |
1191 | |
1192 | if ((uInt)best_len <= s->lookahead) return (uInt)best_len; |
1193 | return s->lookahead; |
1194 | } |
1195 | #endif /* ASMV */ |
1196 | #endif /* FASTEST */ |
1197 | |
1198 | /* --------------------------------------------------------------------------- |
1199 | * Optimized version for level == 1 or strategy == Z_RLE only |
1200 | * @param cur_match current match |
1201 | */ |
1202 | local uInt |
1203 | longest_match_fast(deflate_state *s, IPos cur_match) |
1204 | { |
1205 | Bytef *scan = s->window + s->strstart; /* current string */ |
1206 | Bytef *match; /* matched string */ |
1207 | int len; /* length of current match */ |
1208 | Bytef *strend = s->window + s->strstart + MAX_MATCH; |
1209 | |
1210 | /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. |
1211 | * It is easy to get rid of this optimization if necessary. |
1212 | */ |
1213 | Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever" ); |
1214 | |
1215 | Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead" ); |
1216 | |
1217 | Assert(cur_match < s->strstart, "no future" ); |
1218 | |
1219 | match = s->window + cur_match; |
1220 | |
1221 | /* Return failure if the match length is less than 2: |
1222 | */ |
1223 | if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; |
1224 | |
1225 | /* The check at best_len-1 can be removed because it will be made |
1226 | * again later. (This heuristic is not always a win.) |
1227 | * It is not necessary to compare scan[2] and match[2] since they |
1228 | * are always equal when the other bytes match, given that |
1229 | * the hash keys are equal and that HASH_BITS >= 8. |
1230 | */ |
1231 | scan += 2; |
1232 | match += 2; |
1233 | Assert(*scan == *match, "match[2]?" ); |
1234 | |
1235 | /* We check for insufficient lookahead only every 8th comparison; |
1236 | * the 256th check will be made at strstart+258. |
1237 | */ |
1238 | do { |
1239 | } while (*++scan == *++match && *++scan == *++match && |
1240 | *++scan == *++match && *++scan == *++match && |
1241 | *++scan == *++match && *++scan == *++match && |
1242 | *++scan == *++match && *++scan == *++match && |
1243 | scan < strend); |
1244 | |
1245 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan" ); |
1246 | |
1247 | len = MAX_MATCH - (int)(strend - scan); |
1248 | |
1249 | if (len < MIN_MATCH) return MIN_MATCH - 1; |
1250 | |
1251 | s->match_start = cur_match; |
1252 | return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; |
1253 | } |
1254 | |
1255 | #ifdef DEBUG |
1256 | /* =========================================================================== |
1257 | * Check that the match at match_start is indeed a match. |
1258 | */ |
1259 | local void |
1260 | check_match(deflate_state *s, IPos start, IPos match, int length) |
1261 | { |
1262 | /* check that the match is indeed a match */ |
1263 | if (zmemcmp(s->window + match, |
1264 | s->window + start, length) != EQUAL) { |
1265 | fprintf(stderr, " start %u, match %u, length %d\n" , |
1266 | start, match, length); |
1267 | do { |
1268 | fprintf(stderr, "%c%c" , s->window[match++], s->window[start++]); |
1269 | } while (--length != 0); |
1270 | z_error("invalid match" ); |
1271 | } |
1272 | if (z_verbose > 1) { |
1273 | fprintf(stderr,"\\[%d,%d]" , start-match, length); |
1274 | do { putc(s->window[start++], stderr); } while (--length != 0); |
1275 | } |
1276 | } |
1277 | #else |
1278 | # define check_match(s, start, match, length) |
1279 | #endif /* DEBUG */ |
1280 | |
1281 | /* =========================================================================== |
1282 | * Fill the window when the lookahead becomes insufficient. |
1283 | * Updates strstart and lookahead. |
1284 | * |
1285 | * IN assertion: lookahead < MIN_LOOKAHEAD |
1286 | * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD |
1287 | * At least one byte has been read, or avail_in == 0; reads are |
1288 | * performed for at least two bytes (required for the zip translate_eol |
1289 | * option -- not supported here). |
1290 | */ |
1291 | local void |
1292 | fill_window(deflate_state *s) |
1293 | { |
1294 | unsigned n, m; |
1295 | Posf *p; |
1296 | unsigned more; /* Amount of free space at the end of the window. */ |
1297 | uInt wsize = s->w_size; |
1298 | |
1299 | do { |
1300 | more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); |
1301 | |
1302 | /* Deal with !@#$% 64K limit: */ |
1303 | if (sizeof(int) <= 2) { |
1304 | if (more == 0 && s->strstart == 0 && s->lookahead == 0) { |
1305 | more = wsize; |
1306 | |
1307 | } else if (more == (unsigned)(-1)) { |
1308 | /* Very unlikely, but possible on 16 bit machine if |
1309 | * strstart == 0 && lookahead == 1 (input done a byte at time) |
1310 | */ |
1311 | more--; |
1312 | } |
1313 | } |
1314 | |
1315 | /* If the window is almost full and there is insufficient lookahead, |
1316 | * move the upper half to the lower one to make room in the upper half. |
1317 | */ |
1318 | if (s->strstart >= wsize+MAX_DIST(s)) { |
1319 | |
1320 | zmemcpy(dst: s->window, src: s->window+wsize, n: (unsigned)wsize); |
1321 | s->match_start -= wsize; |
1322 | s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ |
1323 | s->block_start -= (long) wsize; |
1324 | |
1325 | /* Slide the hash table (could be avoided with 32 bit values |
1326 | at the expense of memory usage). We slide even when level == 0 |
1327 | to keep the hash table consistent if we switch back to level > 0 |
1328 | later. (Using level 0 permanently is not an optimal usage of |
1329 | zlib, so we don't care about this pathological case.) |
1330 | */ |
1331 | /* %%% avoid this when Z_RLE */ |
1332 | n = s->hash_size; |
1333 | p = &s->head[n]; |
1334 | do { |
1335 | m = *--p; |
1336 | *p = (Pos)(m >= wsize ? m-wsize : NIL); |
1337 | } while (--n); |
1338 | |
1339 | n = wsize; |
1340 | #ifndef FASTEST |
1341 | p = &s->prev[n]; |
1342 | do { |
1343 | m = *--p; |
1344 | *p = (Pos)(m >= wsize ? m-wsize : NIL); |
1345 | /* If n is not on any hash chain, prev[n] is garbage but |
1346 | * its value will never be used. |
1347 | */ |
1348 | } while (--n); |
1349 | #endif |
1350 | more += wsize; |
1351 | } |
1352 | if (s->strm->avail_in == 0) return; |
1353 | |
1354 | /* If there was no sliding: |
1355 | * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && |
1356 | * more == window_size - lookahead - strstart |
1357 | * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) |
1358 | * => more >= window_size - 2*WSIZE + 2 |
1359 | * In the BIG_MEM or MMAP case (not yet supported), |
1360 | * window_size == input_size + MIN_LOOKAHEAD && |
1361 | * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. |
1362 | * Otherwise, window_size == 2*WSIZE so more >= 2. |
1363 | * If there was sliding, more >= WSIZE. So in all cases, more >= 2. |
1364 | */ |
1365 | Assert(more >= 2, "more < 2" ); |
1366 | |
1367 | n = (*s->zinput)(s->strm, s->window + s->strstart + s->lookahead, more); |
1368 | s->lookahead += n; |
1369 | |
1370 | /* Initialize the hash value now that we have some input: */ |
1371 | if (s->lookahead >= MIN_MATCH) { |
1372 | s->ins_h = s->window[s->strstart]; |
1373 | UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); |
1374 | #if MIN_MATCH != 3 |
1375 | Call UPDATE_HASH() MIN_MATCH-3 more times |
1376 | #endif |
1377 | } |
1378 | /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, |
1379 | * but this is not important since only literal bytes will be emitted. |
1380 | */ |
1381 | |
1382 | } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); |
1383 | } |
1384 | |
1385 | /* =========================================================================== |
1386 | * Flush the current block, with given end-of-file flag. |
1387 | * IN assertion: strstart is set to the end of the current match. |
1388 | */ |
1389 | #define FLUSH_BLOCK_ONLY(s, eof) { \ |
1390 | _tr_flush_block(s, (s->block_start >= 0L ? \ |
1391 | (charf *)&s->window[(unsigned)s->block_start] : \ |
1392 | (charf *)Z_NULL), \ |
1393 | (ulg)((long)s->strstart - s->block_start), \ |
1394 | (eof)); \ |
1395 | s->block_start = s->strstart; \ |
1396 | flush_pending(s->strm); \ |
1397 | Tracev((stderr,"[FLUSH]")); \ |
1398 | } |
1399 | |
1400 | /* Same but force premature exit if necessary. */ |
1401 | #define FLUSH_BLOCK(s, eof) { \ |
1402 | FLUSH_BLOCK_ONLY(s, eof); \ |
1403 | if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \ |
1404 | } |
1405 | |
1406 | /* =========================================================================== |
1407 | * Copy without compression as much as possible from the input stream, return |
1408 | * the current block state. |
1409 | * This function does not insert new strings in the dictionary since |
1410 | * uncompressible data is probably not useful. This function is used |
1411 | * only for the level=0 compression option. |
1412 | * NOTE: this function should be optimized to avoid extra copying from |
1413 | * window to pending_buf. |
1414 | */ |
1415 | local block_state |
1416 | deflate_stored(deflate_state *s, int flush) |
1417 | { |
1418 | /* Stored blocks are limited to 0xffff bytes, pending_buf is limited |
1419 | * to pending_buf_size, and each stored block has a 5 byte header: |
1420 | */ |
1421 | ulg max_block_size = 0xffff; |
1422 | ulg max_start; |
1423 | |
1424 | if (max_block_size > s->pending_buf_size - 5) { |
1425 | max_block_size = s->pending_buf_size - 5; |
1426 | } |
1427 | |
1428 | /* Copy as much as possible from input to output: */ |
1429 | for (;;) { |
1430 | /* Fill the window as much as possible: */ |
1431 | if (s->lookahead <= 1) { |
1432 | |
1433 | Assert(s->strstart < s->w_size+MAX_DIST(s) || |
1434 | s->block_start >= (long)s->w_size, "slide too late" ); |
1435 | |
1436 | fill_window(s); |
1437 | if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; |
1438 | |
1439 | if (s->lookahead == 0) break; /* flush the current block */ |
1440 | } |
1441 | Assert(s->block_start >= 0L, "block gone" ); |
1442 | |
1443 | s->strstart += s->lookahead; |
1444 | s->lookahead = 0; |
1445 | |
1446 | /* Emit a stored block if pending_buf will be full: */ |
1447 | max_start = s->block_start + max_block_size; |
1448 | if (s->strstart == 0 || (ulg)s->strstart >= max_start) { |
1449 | /* strstart == 0 is possible when wraparound on 16-bit machine */ |
1450 | s->lookahead = (uInt)(s->strstart - max_start); |
1451 | s->strstart = (uInt)max_start; |
1452 | FLUSH_BLOCK(s, 0); |
1453 | } |
1454 | /* Flush if we may have to slide, otherwise block_start may become |
1455 | * negative and the data will be gone: |
1456 | */ |
1457 | if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { |
1458 | FLUSH_BLOCK(s, 0); |
1459 | } |
1460 | } |
1461 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1462 | return flush == Z_FINISH ? finish_done : block_done; |
1463 | } |
1464 | |
1465 | /* =========================================================================== |
1466 | * Compress as much as possible from the input stream, return the current |
1467 | * block state. |
1468 | * This function does not perform lazy evaluation of matches and inserts |
1469 | * new strings in the dictionary only for unmatched strings or for short |
1470 | * matches. It is used only for the fast compression options. |
1471 | */ |
1472 | local block_state |
1473 | deflate_fast(deflate_state *s, int flush) |
1474 | { |
1475 | IPos hash_head = NIL; /* head of the hash chain */ |
1476 | int bflush; /* set if current block must be flushed */ |
1477 | |
1478 | for (;;) { |
1479 | /* Make sure that we always have enough lookahead, except |
1480 | * at the end of the input file. We need MAX_MATCH bytes |
1481 | * for the next match, plus MIN_MATCH bytes to insert the |
1482 | * string following the next match. |
1483 | */ |
1484 | if (s->lookahead < MIN_LOOKAHEAD) { |
1485 | fill_window(s); |
1486 | if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { |
1487 | return need_more; |
1488 | } |
1489 | if (s->lookahead == 0) break; /* flush the current block */ |
1490 | } |
1491 | |
1492 | /* Insert the string window[strstart .. strstart+2] in the |
1493 | * dictionary, and set hash_head to the head of the hash chain: |
1494 | */ |
1495 | if (s->lookahead >= MIN_MATCH) { |
1496 | INSERT_STRING(s, s->strstart, hash_head); |
1497 | } |
1498 | |
1499 | /* Find the longest match, discarding those <= prev_length. |
1500 | * At this point we have always match_length < MIN_MATCH |
1501 | */ |
1502 | if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { |
1503 | /* To simplify the code, we prevent matches with the string |
1504 | * of window index 0 (in particular we have to avoid a match |
1505 | * of the string with itself at the start of the input file). |
1506 | */ |
1507 | #ifdef FASTEST |
1508 | if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) || |
1509 | (s->strategy == Z_RLE && s->strstart - hash_head == 1)) { |
1510 | s->match_length = longest_match_fast (s, hash_head); |
1511 | } |
1512 | #else |
1513 | if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) { |
1514 | s->match_length = longest_match (s, cur_match: hash_head); |
1515 | } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { |
1516 | s->match_length = longest_match_fast (s, cur_match: hash_head); |
1517 | } |
1518 | #endif |
1519 | /* longest_match() or longest_match_fast() sets match_start */ |
1520 | } |
1521 | if (s->match_length >= MIN_MATCH) { |
1522 | check_match(s, s->strstart, s->match_start, s->match_length); |
1523 | |
1524 | _tr_tally_dist(s, s->strstart - s->match_start, |
1525 | s->match_length - MIN_MATCH, bflush); |
1526 | |
1527 | s->lookahead -= s->match_length; |
1528 | |
1529 | /* Insert new strings in the hash table only if the match length |
1530 | * is not too large. This saves time but degrades compression. |
1531 | */ |
1532 | #ifndef FASTEST |
1533 | if (s->match_length <= s->max_insert_length && |
1534 | s->lookahead >= MIN_MATCH) { |
1535 | s->match_length--; /* string at strstart already in table */ |
1536 | do { |
1537 | s->strstart++; |
1538 | INSERT_STRING(s, s->strstart, hash_head); |
1539 | /* strstart never exceeds WSIZE-MAX_MATCH, so there are |
1540 | * always MIN_MATCH bytes ahead. |
1541 | */ |
1542 | } while (--s->match_length != 0); |
1543 | s->strstart++; |
1544 | } else |
1545 | #endif |
1546 | { |
1547 | s->strstart += s->match_length; |
1548 | s->match_length = 0; |
1549 | s->ins_h = s->window[s->strstart]; |
1550 | UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); |
1551 | #if MIN_MATCH != 3 |
1552 | Call UPDATE_HASH() MIN_MATCH-3 more times |
1553 | #endif |
1554 | /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not |
1555 | * matter since it will be recomputed at next deflate call. |
1556 | */ |
1557 | } |
1558 | } else { |
1559 | /* No match, output a literal byte */ |
1560 | Tracevv((stderr,"%c" , s->window[s->strstart])); |
1561 | _tr_tally_lit (s, s->window[s->strstart], bflush); |
1562 | s->lookahead--; |
1563 | s->strstart++; |
1564 | } |
1565 | if (bflush) FLUSH_BLOCK(s, 0); |
1566 | } |
1567 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1568 | return flush == Z_FINISH ? finish_done : block_done; |
1569 | } |
1570 | |
1571 | #ifndef FASTEST |
1572 | /* =========================================================================== |
1573 | * Same as above, but achieves better compression. We use a lazy |
1574 | * evaluation for matches: a match is finally adopted only if there is |
1575 | * no better match at the next window position. |
1576 | */ |
1577 | local block_state |
1578 | deflate_slow(deflate_state *s, int flush) |
1579 | { |
1580 | IPos hash_head = NIL; /* head of hash chain */ |
1581 | int bflush; /* set if current block must be flushed */ |
1582 | |
1583 | /* Process the input block. */ |
1584 | for (;;) { |
1585 | /* Make sure that we always have enough lookahead, except |
1586 | * at the end of the input file. We need MAX_MATCH bytes |
1587 | * for the next match, plus MIN_MATCH bytes to insert the |
1588 | * string following the next match. |
1589 | */ |
1590 | if (s->lookahead < MIN_LOOKAHEAD) { |
1591 | fill_window(s); |
1592 | if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { |
1593 | return need_more; |
1594 | } |
1595 | if (s->lookahead == 0) break; /* flush the current block */ |
1596 | } |
1597 | |
1598 | /* Insert the string window[strstart .. strstart+2] in the |
1599 | * dictionary, and set hash_head to the head of the hash chain: |
1600 | */ |
1601 | if (s->lookahead >= MIN_MATCH) { |
1602 | INSERT_STRING(s, s->strstart, hash_head); |
1603 | } |
1604 | |
1605 | /* Find the longest match, discarding those <= prev_length. |
1606 | */ |
1607 | s->prev_length = s->match_length; |
1608 | s->prev_match = s->match_start; |
1609 | s->match_length = MIN_MATCH-1; |
1610 | |
1611 | if (hash_head != NIL && s->prev_length < s->max_lazy_match && |
1612 | s->strstart - hash_head <= MAX_DIST(s)) { |
1613 | /* To simplify the code, we prevent matches with the string |
1614 | * of window index 0 (in particular we have to avoid a match |
1615 | * of the string with itself at the start of the input file). |
1616 | */ |
1617 | if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) { |
1618 | s->match_length = longest_match (s, cur_match: hash_head); |
1619 | } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { |
1620 | s->match_length = longest_match_fast (s, cur_match: hash_head); |
1621 | } |
1622 | /* longest_match() or longest_match_fast() sets match_start */ |
1623 | |
1624 | if (s->match_length <= 5 && (s->strategy == Z_FILTERED |
1625 | #if TOO_FAR <= 32767 |
1626 | || (s->match_length == MIN_MATCH && |
1627 | s->strstart - s->match_start > TOO_FAR) |
1628 | #endif |
1629 | )) { |
1630 | |
1631 | /* If prev_match is also MIN_MATCH, match_start is garbage |
1632 | * but we will ignore the current match anyway. |
1633 | */ |
1634 | s->match_length = MIN_MATCH-1; |
1635 | } |
1636 | } |
1637 | /* If there was a match at the previous step and the current |
1638 | * match is not better, output the previous match: |
1639 | */ |
1640 | if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { |
1641 | uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; |
1642 | /* Do not insert strings in hash table beyond this. */ |
1643 | |
1644 | check_match(s, s->strstart-1, s->prev_match, s->prev_length); |
1645 | |
1646 | _tr_tally_dist(s, s->strstart -1 - s->prev_match, |
1647 | s->prev_length - MIN_MATCH, bflush); |
1648 | |
1649 | /* Insert in hash table all strings up to the end of the match. |
1650 | * strstart-1 and strstart are already inserted. If there is not |
1651 | * enough lookahead, the last two strings are not inserted in |
1652 | * the hash table. |
1653 | */ |
1654 | s->lookahead -= s->prev_length-1; |
1655 | s->prev_length -= 2; |
1656 | do { |
1657 | if (++s->strstart <= max_insert) { |
1658 | INSERT_STRING(s, s->strstart, hash_head); |
1659 | } |
1660 | } while (--s->prev_length != 0); |
1661 | s->match_available = 0; |
1662 | s->match_length = MIN_MATCH-1; |
1663 | s->strstart++; |
1664 | |
1665 | if (bflush) FLUSH_BLOCK(s, 0); |
1666 | |
1667 | } else if (s->match_available) { |
1668 | /* If there was no match at the previous position, output a |
1669 | * single literal. If there was a match but the current match |
1670 | * is longer, truncate the previous match to a single literal. |
1671 | */ |
1672 | Tracevv((stderr,"%c" , s->window[s->strstart-1])); |
1673 | _tr_tally_lit(s, s->window[s->strstart-1], bflush); |
1674 | if (bflush) { |
1675 | FLUSH_BLOCK_ONLY(s, 0); |
1676 | } |
1677 | s->strstart++; |
1678 | s->lookahead--; |
1679 | if (s->strm->avail_out == 0) return need_more; |
1680 | } else { |
1681 | /* There is no previous match to compare with, wait for |
1682 | * the next step to decide. |
1683 | */ |
1684 | s->match_available = 1; |
1685 | s->strstart++; |
1686 | s->lookahead--; |
1687 | } |
1688 | } |
1689 | Assert (flush != Z_NO_FLUSH, "no flush?" ); |
1690 | if (s->match_available) { |
1691 | Tracevv((stderr,"%c" , s->window[s->strstart-1])); |
1692 | _tr_tally_lit(s, s->window[s->strstart-1], bflush); |
1693 | s->match_available = 0; |
1694 | } |
1695 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1696 | return flush == Z_FINISH ? finish_done : block_done; |
1697 | } |
1698 | #endif /* FASTEST */ |
1699 | |
1700 | #if 0 |
1701 | /* =========================================================================== |
1702 | * For Z_RLE, simply look for runs of bytes, generate matches only of distance |
1703 | * one. Do not maintain a hash table. (It will be regenerated if this run of |
1704 | * deflate switches away from Z_RLE.) |
1705 | */ |
1706 | local block_state |
1707 | deflate_rle(deflate_state *s, int flush) |
1708 | { |
1709 | int bflush; /* set if current block must be flushed */ |
1710 | uInt run; /* length of run */ |
1711 | uInt max; /* maximum length of run */ |
1712 | uInt prev; /* byte at distance one to match */ |
1713 | Bytef *scan; /* scan for end of run */ |
1714 | |
1715 | for (;;) { |
1716 | /* Make sure that we always have enough lookahead, except |
1717 | * at the end of the input file. We need MAX_MATCH bytes |
1718 | * for the longest encodable run. |
1719 | */ |
1720 | if (s->lookahead < MAX_MATCH) { |
1721 | fill_window(s); |
1722 | if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) { |
1723 | return need_more; |
1724 | } |
1725 | if (s->lookahead == 0) break; /* flush the current block */ |
1726 | } |
1727 | |
1728 | /* See how many times the previous byte repeats */ |
1729 | run = 0; |
1730 | if (s->strstart > 0) { /* if there is a previous byte, that is */ |
1731 | max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH; |
1732 | scan = s->window + s->strstart - 1; |
1733 | prev = *scan++; |
1734 | do { |
1735 | if (*scan++ != prev) |
1736 | break; |
1737 | } while (++run < max); |
1738 | } |
1739 | |
1740 | /* Emit match if have run of MIN_MATCH or longer, else emit literal */ |
1741 | if (run >= MIN_MATCH) { |
1742 | check_match(s, s->strstart, s->strstart - 1, run); |
1743 | _tr_tally_dist(s, 1, run - MIN_MATCH, bflush); |
1744 | s->lookahead -= run; |
1745 | s->strstart += run; |
1746 | } else { |
1747 | /* No match, output a literal byte */ |
1748 | Tracevv((stderr,"%c" , s->window[s->strstart])); |
1749 | _tr_tally_lit (s, s->window[s->strstart], bflush); |
1750 | s->lookahead--; |
1751 | s->strstart++; |
1752 | } |
1753 | if (bflush) FLUSH_BLOCK(s, 0); |
1754 | } |
1755 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1756 | return flush == Z_FINISH ? finish_done : block_done; |
1757 | } |
1758 | #endif |
1759 | |
1760 | #if XNU_KERNEL_PRIVATE |
1761 | |
1762 | uLong |
1763 | zlib_deflate_memory_size(int wbits, int memlevel) |
1764 | { |
1765 | return (31 + sizeof(deflate_state) + (1 << (wbits + 2)) + (1 << (memlevel + 9))); |
1766 | } |
1767 | |
1768 | #endif /* XNU_KERNEL_PRIVATE */ |
1769 | |