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d4286ec4 | 1 | /* deflate.c -- compress data using the deflation algorithm |
1e1cf689 WD |
2 | * Copyright (C) 1995-2004 Jean-loup Gailly. |
3 | * For conditions of distribution and use, see copyright notice in zlib.h | |
d4286ec4 PM |
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". | |
1e1cf689 | 40 | * Available in http://www.ietf.org/rfc/rfc1951.txt |
d4286ec4 PM |
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 | ||
12febd80 WD |
54 | #define read_buf dread_buf |
55 | ||
d4286ec4 | 56 | const char deflate_copyright[] = |
1e1cf689 | 57 | " deflate 1.2.2 Copyright 1995-2004 Jean-loup Gailly "; |
d4286ec4 PM |
58 | /* |
59 | If you use the zlib library in a product, an acknowledgment is welcome | |
60 | in the documentation of your product. If for some reason you cannot | |
61 | include such an acknowledgment, I would appreciate that you keep this | |
62 | copyright string in the executable of your product. | |
63 | */ | |
64 | ||
65 | /* =========================================================================== | |
66 | * Function prototypes. | |
67 | */ | |
68 | typedef enum { | |
69 | need_more, /* block not completed, need more input or more output */ | |
70 | block_done, /* block flush performed */ | |
71 | finish_started, /* finish started, need only more output at next deflate */ | |
72 | finish_done /* finish done, accept no more input or output */ | |
73 | } block_state; | |
74 | ||
75 | typedef block_state (*compress_func) OF((deflate_state *s, int flush)); | |
76 | /* Compression function. Returns the block state after the call. */ | |
77 | ||
78 | local void fill_window OF((deflate_state *s)); | |
79 | local block_state deflate_stored OF((deflate_state *s, int flush)); | |
80 | local block_state deflate_fast OF((deflate_state *s, int flush)); | |
1e1cf689 | 81 | #ifndef FASTEST |
d4286ec4 | 82 | local block_state deflate_slow OF((deflate_state *s, int flush)); |
1e1cf689 | 83 | #endif |
d4286ec4 PM |
84 | local void lm_init OF((deflate_state *s)); |
85 | local void putShortMSB OF((deflate_state *s, uInt b)); | |
86 | local void flush_pending OF((z_streamp strm)); | |
12febd80 | 87 | local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); |
1e1cf689 | 88 | #ifndef FASTEST |
d4286ec4 PM |
89 | #ifdef ASMV |
90 | void match_init OF((void)); /* asm code initialization */ | |
91 | uInt longest_match OF((deflate_state *s, IPos cur_match)); | |
92 | #else | |
93 | local uInt longest_match OF((deflate_state *s, IPos cur_match)); | |
94 | #endif | |
1e1cf689 WD |
95 | #endif |
96 | local uInt longest_match_fast OF((deflate_state *s, IPos cur_match)); | |
d4286ec4 PM |
97 | |
98 | #ifdef DEBUG | |
99 | local void check_match OF((deflate_state *s, IPos start, IPos match, | |
100 | int length)); | |
101 | #endif | |
102 | ||
103 | /* =========================================================================== | |
104 | * Local data | |
105 | */ | |
106 | ||
107 | #define NIL 0 | |
108 | /* Tail of hash chains */ | |
109 | ||
110 | #ifndef TOO_FAR | |
111 | # define TOO_FAR 4096 | |
112 | #endif | |
113 | /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ | |
114 | ||
115 | #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) | |
116 | /* Minimum amount of lookahead, except at the end of the input file. | |
117 | * See deflate.c for comments about the MIN_MATCH+1. | |
118 | */ | |
119 | ||
120 | /* Values for max_lazy_match, good_match and max_chain_length, depending on | |
121 | * the desired pack level (0..9). The values given below have been tuned to | |
122 | * exclude worst case performance for pathological files. Better values may be | |
123 | * found for specific files. | |
124 | */ | |
125 | typedef struct config_s { | |
126 | ush good_length; /* reduce lazy search above this match length */ | |
127 | ush max_lazy; /* do not perform lazy search above this match length */ | |
128 | ush nice_length; /* quit search above this match length */ | |
129 | ush max_chain; | |
130 | compress_func func; | |
131 | } config; | |
132 | ||
1e1cf689 WD |
133 | #ifdef FASTEST |
134 | local const config configuration_table[2] = { | |
135 | /* good lazy nice chain */ | |
136 | /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ | |
137 | /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ | |
138 | #else | |
d4286ec4 PM |
139 | local const config configuration_table[10] = { |
140 | /* good lazy nice chain */ | |
141 | /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ | |
1e1cf689 | 142 | /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ |
d4286ec4 PM |
143 | /* 2 */ {4, 5, 16, 8, deflate_fast}, |
144 | /* 3 */ {4, 6, 32, 32, deflate_fast}, | |
145 | ||
146 | /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ | |
147 | /* 5 */ {8, 16, 32, 32, deflate_slow}, | |
148 | /* 6 */ {8, 16, 128, 128, deflate_slow}, | |
149 | /* 7 */ {8, 32, 128, 256, deflate_slow}, | |
150 | /* 8 */ {32, 128, 258, 1024, deflate_slow}, | |
1e1cf689 WD |
151 | /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ |
152 | #endif | |
d4286ec4 PM |
153 | |
154 | /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 | |
155 | * For deflate_fast() (levels <= 3) good is ignored and lazy has a different | |
156 | * meaning. | |
157 | */ | |
158 | ||
159 | #define EQUAL 0 | |
160 | /* result of memcmp for equal strings */ | |
161 | ||
1e1cf689 | 162 | #ifndef NO_DUMMY_DECL |
d4286ec4 | 163 | struct static_tree_desc_s {int dummy;}; /* for buggy compilers */ |
1e1cf689 | 164 | #endif |
d4286ec4 PM |
165 | |
166 | /* =========================================================================== | |
167 | * Update a hash value with the given input byte | |
168 | * IN assertion: all calls to to UPDATE_HASH are made with consecutive | |
169 | * input characters, so that a running hash key can be computed from the | |
170 | * previous key instead of complete recalculation each time. | |
171 | */ | |
172 | #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) | |
173 | ||
174 | ||
175 | /* =========================================================================== | |
176 | * Insert string str in the dictionary and set match_head to the previous head | |
177 | * of the hash chain (the most recent string with same hash key). Return | |
178 | * the previous length of the hash chain. | |
179 | * If this file is compiled with -DFASTEST, the compression level is forced | |
180 | * to 1, and no hash chains are maintained. | |
181 | * IN assertion: all calls to to INSERT_STRING are made with consecutive | |
182 | * input characters and the first MIN_MATCH bytes of str are valid | |
183 | * (except for the last MIN_MATCH-1 bytes of the input file). | |
184 | */ | |
185 | #ifdef FASTEST | |
186 | #define INSERT_STRING(s, str, match_head) \ | |
187 | (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ | |
188 | match_head = s->head[s->ins_h], \ | |
189 | s->head[s->ins_h] = (Pos)(str)) | |
190 | #else | |
191 | #define INSERT_STRING(s, str, match_head) \ | |
192 | (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ | |
1e1cf689 | 193 | match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ |
d4286ec4 PM |
194 | s->head[s->ins_h] = (Pos)(str)) |
195 | #endif | |
196 | ||
197 | /* =========================================================================== | |
198 | * Initialize the hash table (avoiding 64K overflow for 16 bit systems). | |
199 | * prev[] will be initialized on the fly. | |
200 | */ | |
201 | #define CLEAR_HASH(s) \ | |
202 | s->head[s->hash_size-1] = NIL; \ | |
203 | zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); | |
204 | ||
205 | /* ========================================================================= */ | |
206 | int ZEXPORT deflateInit_(strm, level, version, stream_size) | |
207 | z_streamp strm; | |
208 | int level; | |
209 | const char *version; | |
210 | int stream_size; | |
211 | { | |
212 | return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, | |
1e1cf689 | 213 | Z_DEFAULT_STRATEGY, version, stream_size); |
d4286ec4 PM |
214 | /* To do: ignore strm->next_in if we use it as window */ |
215 | } | |
216 | ||
217 | /* ========================================================================= */ | |
218 | int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, | |
1e1cf689 | 219 | version, stream_size) |
d4286ec4 PM |
220 | z_streamp strm; |
221 | int level; | |
222 | int method; | |
223 | int windowBits; | |
224 | int memLevel; | |
225 | int strategy; | |
226 | const char *version; | |
227 | int stream_size; | |
228 | { | |
229 | deflate_state *s; | |
1e1cf689 WD |
230 | int wrap = 1; |
231 | static const char my_version[] = ZLIB_VERSION; | |
d4286ec4 PM |
232 | |
233 | ushf *overlay; | |
234 | /* We overlay pending_buf and d_buf+l_buf. This works since the average | |
235 | * output size for (length,distance) codes is <= 24 bits. | |
236 | */ | |
237 | ||
238 | if (version == Z_NULL || version[0] != my_version[0] || | |
239 | stream_size != sizeof(z_stream)) { | |
1e1cf689 | 240 | return Z_VERSION_ERROR; |
d4286ec4 PM |
241 | } |
242 | if (strm == Z_NULL) return Z_STREAM_ERROR; | |
243 | ||
244 | strm->msg = Z_NULL; | |
1e1cf689 WD |
245 | if (strm->zalloc == (alloc_func)0) { |
246 | strm->zalloc = zcalloc; | |
247 | strm->opaque = (voidpf)0; | |
d4286ec4 | 248 | } |
1e1cf689 | 249 | if (strm->zfree == (free_func)0) strm->zfree = zcfree; |
d4286ec4 | 250 | |
d4286ec4 | 251 | #ifdef FASTEST |
1e1cf689 WD |
252 | if (level != 0) level = 1; |
253 | #else | |
254 | if (level == Z_DEFAULT_COMPRESSION) level = 6; | |
d4286ec4 PM |
255 | #endif |
256 | ||
1e1cf689 WD |
257 | if (windowBits < 0) { /* suppress zlib wrapper */ |
258 | wrap = 0; | |
d4286ec4 PM |
259 | windowBits = -windowBits; |
260 | } | |
1e1cf689 WD |
261 | #ifdef GZIP |
262 | else if (windowBits > 15) { | |
263 | wrap = 2; /* write gzip wrapper instead */ | |
264 | windowBits -= 16; | |
265 | } | |
266 | #endif | |
d4286ec4 | 267 | if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || |
1e1cf689 WD |
268 | windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || |
269 | strategy < 0 || strategy > Z_RLE) { | |
d4286ec4 PM |
270 | return Z_STREAM_ERROR; |
271 | } | |
1e1cf689 | 272 | if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ |
d4286ec4 PM |
273 | s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); |
274 | if (s == Z_NULL) return Z_MEM_ERROR; | |
275 | strm->state = (struct internal_state FAR *)s; | |
276 | s->strm = strm; | |
277 | ||
1e1cf689 | 278 | s->wrap = wrap; |
d4286ec4 PM |
279 | s->w_bits = windowBits; |
280 | s->w_size = 1 << s->w_bits; | |
281 | s->w_mask = s->w_size - 1; | |
282 | ||
283 | s->hash_bits = memLevel + 7; | |
284 | s->hash_size = 1 << s->hash_bits; | |
285 | s->hash_mask = s->hash_size - 1; | |
286 | s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); | |
287 | ||
288 | s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); | |
289 | s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); | |
290 | s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); | |
291 | ||
292 | s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ | |
293 | ||
294 | overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); | |
295 | s->pending_buf = (uchf *) overlay; | |
296 | s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); | |
297 | ||
298 | if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || | |
299 | s->pending_buf == Z_NULL) { | |
1e1cf689 | 300 | s->status = FINISH_STATE; |
d4286ec4 PM |
301 | strm->msg = (char*)ERR_MSG(Z_MEM_ERROR); |
302 | deflateEnd (strm); | |
303 | return Z_MEM_ERROR; | |
304 | } | |
305 | s->d_buf = overlay + s->lit_bufsize/sizeof(ush); | |
306 | s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; | |
307 | ||
308 | s->level = level; | |
309 | s->strategy = strategy; | |
310 | s->method = (Byte)method; | |
311 | ||
312 | return deflateReset(strm); | |
313 | } | |
314 | ||
315 | /* ========================================================================= */ | |
316 | int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) | |
317 | z_streamp strm; | |
318 | const Bytef *dictionary; | |
319 | uInt dictLength; | |
320 | { | |
321 | deflate_state *s; | |
322 | uInt length = dictLength; | |
323 | uInt n; | |
324 | IPos hash_head = 0; | |
325 | ||
326 | if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL || | |
1e1cf689 WD |
327 | strm->state->wrap == 2 || |
328 | (strm->state->wrap == 1 && strm->state->status != INIT_STATE)) | |
329 | return Z_STREAM_ERROR; | |
d4286ec4 PM |
330 | |
331 | s = strm->state; | |
1e1cf689 WD |
332 | if (s->wrap) |
333 | strm->adler = adler32(strm->adler, dictionary, dictLength); | |
d4286ec4 PM |
334 | |
335 | if (length < MIN_MATCH) return Z_OK; | |
336 | if (length > MAX_DIST(s)) { | |
1e1cf689 | 337 | length = MAX_DIST(s); |
d4286ec4 | 338 | #ifndef USE_DICT_HEAD |
1e1cf689 | 339 | dictionary += dictLength - length; /* use the tail of the dictionary */ |
d4286ec4 PM |
340 | #endif |
341 | } | |
342 | zmemcpy(s->window, dictionary, length); | |
343 | s->strstart = length; | |
344 | s->block_start = (long)length; | |
345 | ||
346 | /* Insert all strings in the hash table (except for the last two bytes). | |
347 | * s->lookahead stays null, so s->ins_h will be recomputed at the next | |
348 | * call of fill_window. | |
349 | */ | |
350 | s->ins_h = s->window[0]; | |
351 | UPDATE_HASH(s, s->ins_h, s->window[1]); | |
352 | for (n = 0; n <= length - MIN_MATCH; n++) { | |
1e1cf689 | 353 | INSERT_STRING(s, n, hash_head); |
d4286ec4 PM |
354 | } |
355 | if (hash_head) hash_head = 0; /* to make compiler happy */ | |
356 | return Z_OK; | |
357 | } | |
358 | ||
359 | /* ========================================================================= */ | |
360 | int ZEXPORT deflateReset (strm) | |
361 | z_streamp strm; | |
362 | { | |
363 | deflate_state *s; | |
1e1cf689 | 364 | |
d4286ec4 | 365 | if (strm == Z_NULL || strm->state == Z_NULL || |
1e1cf689 WD |
366 | strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { |
367 | return Z_STREAM_ERROR; | |
368 | } | |
d4286ec4 PM |
369 | |
370 | strm->total_in = strm->total_out = 0; | |
371 | strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ | |
372 | strm->data_type = Z_UNKNOWN; | |
373 | ||
374 | s = (deflate_state *)strm->state; | |
375 | s->pending = 0; | |
376 | s->pending_out = s->pending_buf; | |
377 | ||
1e1cf689 WD |
378 | if (s->wrap < 0) { |
379 | s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ | |
d4286ec4 | 380 | } |
1e1cf689 WD |
381 | s->status = s->wrap ? INIT_STATE : BUSY_STATE; |
382 | strm->adler = | |
383 | #ifdef GZIP | |
384 | s->wrap == 2 ? crc32(0L, Z_NULL, 0) : | |
385 | #endif | |
386 | adler32(0L, Z_NULL, 0); | |
d4286ec4 PM |
387 | s->last_flush = Z_NO_FLUSH; |
388 | ||
389 | _tr_init(s); | |
390 | lm_init(s); | |
391 | ||
392 | return Z_OK; | |
393 | } | |
394 | ||
1e1cf689 WD |
395 | /* ========================================================================= */ |
396 | int ZEXPORT deflatePrime (strm, bits, value) | |
397 | z_streamp strm; | |
398 | int bits; | |
399 | int value; | |
400 | { | |
401 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; | |
402 | strm->state->bi_valid = bits; | |
403 | strm->state->bi_buf = (ush)(value & ((1 << bits) - 1)); | |
404 | return Z_OK; | |
405 | } | |
406 | ||
d4286ec4 PM |
407 | /* ========================================================================= */ |
408 | int ZEXPORT deflateParams(strm, level, strategy) | |
409 | z_streamp strm; | |
410 | int level; | |
411 | int strategy; | |
412 | { | |
413 | deflate_state *s; | |
414 | compress_func func; | |
415 | int err = Z_OK; | |
416 | ||
417 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; | |
418 | s = strm->state; | |
419 | ||
1e1cf689 WD |
420 | #ifdef FASTEST |
421 | if (level != 0) level = 1; | |
422 | #else | |
423 | if (level == Z_DEFAULT_COMPRESSION) level = 6; | |
424 | #endif | |
425 | if (level < 0 || level > 9 || strategy < 0 || strategy > Z_RLE) { | |
426 | return Z_STREAM_ERROR; | |
d4286ec4 PM |
427 | } |
428 | func = configuration_table[s->level].func; | |
429 | ||
430 | if (func != configuration_table[level].func && strm->total_in != 0) { | |
1e1cf689 WD |
431 | /* Flush the last buffer: */ |
432 | err = deflate(strm, Z_PARTIAL_FLUSH); | |
d4286ec4 PM |
433 | } |
434 | if (s->level != level) { | |
1e1cf689 WD |
435 | s->level = level; |
436 | s->max_lazy_match = configuration_table[level].max_lazy; | |
437 | s->good_match = configuration_table[level].good_length; | |
438 | s->nice_match = configuration_table[level].nice_length; | |
439 | s->max_chain_length = configuration_table[level].max_chain; | |
d4286ec4 PM |
440 | } |
441 | s->strategy = strategy; | |
442 | return err; | |
443 | } | |
444 | ||
1e1cf689 WD |
445 | /* ========================================================================= |
446 | * For the default windowBits of 15 and memLevel of 8, this function returns | |
447 | * a close to exact, as well as small, upper bound on the compressed size. | |
448 | * They are coded as constants here for a reason--if the #define's are | |
449 | * changed, then this function needs to be changed as well. The return | |
450 | * value for 15 and 8 only works for those exact settings. | |
451 | * | |
452 | * For any setting other than those defaults for windowBits and memLevel, | |
453 | * the value returned is a conservative worst case for the maximum expansion | |
454 | * resulting from using fixed blocks instead of stored blocks, which deflate | |
455 | * can emit on compressed data for some combinations of the parameters. | |
456 | * | |
457 | * This function could be more sophisticated to provide closer upper bounds | |
458 | * for every combination of windowBits and memLevel, as well as wrap. | |
459 | * But even the conservative upper bound of about 14% expansion does not | |
460 | * seem onerous for output buffer allocation. | |
461 | */ | |
462 | uLong ZEXPORT deflateBound(strm, sourceLen) | |
463 | z_streamp strm; | |
464 | uLong sourceLen; | |
465 | { | |
466 | deflate_state *s; | |
467 | uLong destLen; | |
468 | ||
469 | /* conservative upper bound */ | |
470 | destLen = sourceLen + | |
471 | ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11; | |
472 | ||
473 | /* if can't get parameters, return conservative bound */ | |
474 | if (strm == Z_NULL || strm->state == Z_NULL) | |
475 | return destLen; | |
476 | ||
477 | /* if not default parameters, return conservative bound */ | |
478 | s = strm->state; | |
479 | if (s->w_bits != 15 || s->hash_bits != 8 + 7) | |
480 | return destLen; | |
481 | ||
482 | /* default settings: return tight bound for that case */ | |
483 | return compressBound(sourceLen); | |
484 | } | |
485 | ||
d4286ec4 PM |
486 | /* ========================================================================= |
487 | * Put a short in the pending buffer. The 16-bit value is put in MSB order. | |
488 | * IN assertion: the stream state is correct and there is enough room in | |
489 | * pending_buf. | |
490 | */ | |
491 | local void putShortMSB (s, b) | |
492 | deflate_state *s; | |
493 | uInt b; | |
494 | { | |
495 | put_byte(s, (Byte)(b >> 8)); | |
496 | put_byte(s, (Byte)(b & 0xff)); | |
1e1cf689 | 497 | } |
d4286ec4 PM |
498 | |
499 | /* ========================================================================= | |
500 | * Flush as much pending output as possible. All deflate() output goes | |
501 | * through this function so some applications may wish to modify it | |
502 | * to avoid allocating a large strm->next_out buffer and copying into it. | |
12febd80 | 503 | * (See also read_buf()). |
d4286ec4 PM |
504 | */ |
505 | local void flush_pending(strm) | |
506 | z_streamp strm; | |
507 | { | |
508 | unsigned len = strm->state->pending; | |
509 | ||
510 | if (len > strm->avail_out) len = strm->avail_out; | |
511 | if (len == 0) return; | |
512 | ||
513 | zmemcpy(strm->next_out, strm->state->pending_out, len); | |
514 | strm->next_out += len; | |
515 | strm->state->pending_out += len; | |
516 | strm->total_out += len; | |
517 | strm->avail_out -= len; | |
518 | strm->state->pending -= len; | |
519 | if (strm->state->pending == 0) { | |
520 | strm->state->pending_out = strm->state->pending_buf; | |
521 | } | |
522 | } | |
523 | ||
524 | /* ========================================================================= */ | |
525 | int ZEXPORT deflate (strm, flush) | |
526 | z_streamp strm; | |
527 | int flush; | |
528 | { | |
529 | int old_flush; /* value of flush param for previous deflate call */ | |
530 | deflate_state *s; | |
531 | ||
532 | if (strm == Z_NULL || strm->state == Z_NULL || | |
1e1cf689 | 533 | flush > Z_INSERT_ONLY || flush < 0) { |
d4286ec4 PM |
534 | return Z_STREAM_ERROR; |
535 | } | |
536 | s = strm->state; | |
537 | ||
538 | if (strm->next_out == Z_NULL || | |
539 | (strm->next_in == Z_NULL && strm->avail_in != 0) || | |
1e1cf689 | 540 | (s->status == FINISH_STATE && flush != Z_FINISH)) { |
d4286ec4 PM |
541 | ERR_RETURN(strm, Z_STREAM_ERROR); |
542 | } | |
543 | if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); | |
544 | ||
545 | s->strm = strm; /* just in case */ | |
546 | old_flush = s->last_flush; | |
547 | s->last_flush = flush; | |
548 | ||
1e1cf689 | 549 | /* Write the header */ |
d4286ec4 | 550 | if (s->status == INIT_STATE) { |
1e1cf689 WD |
551 | #ifdef GZIP |
552 | if (s->wrap == 2) { | |
553 | put_byte(s, 31); | |
554 | put_byte(s, 139); | |
555 | put_byte(s, 8); | |
556 | put_byte(s, 0); | |
557 | put_byte(s, 0); | |
558 | put_byte(s, 0); | |
559 | put_byte(s, 0); | |
560 | put_byte(s, 0); | |
561 | put_byte(s, s->level == 9 ? 2 : | |
562 | (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? | |
563 | 4 : 0)); | |
564 | put_byte(s, 255); | |
565 | s->status = BUSY_STATE; | |
566 | strm->adler = crc32(0L, Z_NULL, 0); | |
567 | } | |
568 | else | |
569 | #endif | |
570 | { | |
571 | uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; | |
572 | uInt level_flags; | |
573 | ||
574 | if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) | |
575 | level_flags = 0; | |
576 | else if (s->level < 6) | |
577 | level_flags = 1; | |
578 | else if (s->level == 6) | |
579 | level_flags = 2; | |
580 | else | |
581 | level_flags = 3; | |
582 | header |= (level_flags << 6); | |
583 | if (s->strstart != 0) header |= PRESET_DICT; | |
584 | header += 31 - (header % 31); | |
585 | ||
586 | s->status = BUSY_STATE; | |
587 | putShortMSB(s, header); | |
588 | ||
589 | /* Save the adler32 of the preset dictionary: */ | |
590 | if (s->strstart != 0) { | |
591 | putShortMSB(s, (uInt)(strm->adler >> 16)); | |
592 | putShortMSB(s, (uInt)(strm->adler & 0xffff)); | |
593 | } | |
594 | strm->adler = adler32(0L, Z_NULL, 0); | |
595 | } | |
d4286ec4 PM |
596 | } |
597 | ||
598 | /* Flush as much pending output as possible */ | |
599 | if (s->pending != 0) { | |
600 | flush_pending(strm); | |
601 | if (strm->avail_out == 0) { | |
1e1cf689 WD |
602 | /* Since avail_out is 0, deflate will be called again with |
603 | * more output space, but possibly with both pending and | |
604 | * avail_in equal to zero. There won't be anything to do, | |
605 | * but this is not an error situation so make sure we | |
606 | * return OK instead of BUF_ERROR at next call of deflate: | |
d4286ec4 | 607 | */ |
1e1cf689 WD |
608 | s->last_flush = -1; |
609 | return Z_OK; | |
610 | } | |
d4286ec4 PM |
611 | |
612 | /* Make sure there is something to do and avoid duplicate consecutive | |
613 | * flushes. For repeated and useless calls with Z_FINISH, we keep | |
1e1cf689 | 614 | * returning Z_STREAM_END instead of Z_BUF_ERROR. |
d4286ec4 PM |
615 | */ |
616 | } else if (strm->avail_in == 0 && flush <= old_flush && | |
1e1cf689 | 617 | flush != Z_FINISH) { |
d4286ec4 PM |
618 | ERR_RETURN(strm, Z_BUF_ERROR); |
619 | } | |
620 | ||
621 | /* User must not provide more input after the first FINISH: */ | |
622 | if (s->status == FINISH_STATE && strm->avail_in != 0) { | |
623 | ERR_RETURN(strm, Z_BUF_ERROR); | |
624 | } | |
625 | ||
626 | /* Start a new block or continue the current one. | |
627 | */ | |
628 | if (strm->avail_in != 0 || s->lookahead != 0 || | |
629 | (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { | |
630 | block_state bstate; | |
631 | ||
1e1cf689 | 632 | bstate = (*(configuration_table[s->level].func))(s, flush); |
d4286ec4 PM |
633 | |
634 | if (bstate == finish_started || bstate == finish_done) { | |
635 | s->status = FINISH_STATE; | |
636 | } | |
637 | if (bstate == need_more || bstate == finish_started) { | |
1e1cf689 WD |
638 | if (strm->avail_out == 0) { |
639 | s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ | |
640 | } | |
641 | return Z_OK; | |
642 | /* If flush != Z_NO_FLUSH && avail_out == 0, the next call | |
643 | * of deflate should use the same flush parameter to make sure | |
644 | * that the flush is complete. So we don't have to output an | |
645 | * empty block here, this will be done at next call. This also | |
646 | * ensures that for a very small output buffer, we emit at most | |
647 | * one empty block. | |
648 | */ | |
649 | } | |
d4286ec4 PM |
650 | if (bstate == block_done) { |
651 | if (flush == Z_PARTIAL_FLUSH) { | |
652 | _tr_align(s); | |
653 | } else { /* FULL_FLUSH or SYNC_FLUSH */ | |
654 | _tr_stored_block(s, (char*)0, 0L, 0); | |
655 | /* For a full flush, this empty block will be recognized | |
656 | * as a special marker by inflate_sync(). | |
657 | */ | |
658 | if (flush == Z_FULL_FLUSH) { | |
659 | CLEAR_HASH(s); /* forget history */ | |
660 | } | |
661 | } | |
662 | flush_pending(strm); | |
1e1cf689 WD |
663 | if (strm->avail_out == 0) { |
664 | s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ | |
665 | return Z_OK; | |
666 | } | |
d4286ec4 PM |
667 | } |
668 | } | |
669 | Assert(strm->avail_out > 0, "bug2"); | |
670 | ||
671 | if (flush != Z_FINISH) return Z_OK; | |
1e1cf689 WD |
672 | if (s->wrap <= 0) return Z_STREAM_END; |
673 | ||
674 | /* Write the trailer */ | |
675 | #ifdef GZIP | |
676 | if (s->wrap == 2) { | |
677 | put_byte(s, (Byte)(strm->adler & 0xff)); | |
678 | put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); | |
679 | put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); | |
680 | put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); | |
681 | put_byte(s, (Byte)(strm->total_in & 0xff)); | |
682 | put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); | |
683 | put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); | |
684 | put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); | |
685 | } | |
686 | else | |
687 | #endif | |
688 | { | |
689 | putShortMSB(s, (uInt)(strm->adler >> 16)); | |
690 | putShortMSB(s, (uInt)(strm->adler & 0xffff)); | |
691 | } | |
d4286ec4 PM |
692 | flush_pending(strm); |
693 | /* If avail_out is zero, the application will call deflate again | |
694 | * to flush the rest. | |
695 | */ | |
1e1cf689 | 696 | if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ |
d4286ec4 PM |
697 | return s->pending != 0 ? Z_OK : Z_STREAM_END; |
698 | } | |
699 | ||
700 | /* ========================================================================= */ | |
701 | int ZEXPORT deflateEnd (strm) | |
702 | z_streamp strm; | |
703 | { | |
704 | int status; | |
705 | ||
706 | if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; | |
707 | ||
708 | status = strm->state->status; | |
709 | if (status != INIT_STATE && status != BUSY_STATE && | |
1e1cf689 | 710 | status != FINISH_STATE) { |
d4286ec4 PM |
711 | return Z_STREAM_ERROR; |
712 | } | |
713 | ||
714 | /* Deallocate in reverse order of allocations: */ | |
715 | TRY_FREE(strm, strm->state->pending_buf); | |
716 | TRY_FREE(strm, strm->state->head); | |
717 | TRY_FREE(strm, strm->state->prev); | |
718 | TRY_FREE(strm, strm->state->window); | |
719 | ||
720 | ZFREE(strm, strm->state); | |
721 | strm->state = Z_NULL; | |
722 | ||
723 | return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; | |
724 | } | |
725 | ||
726 | /* ========================================================================= | |
727 | * Copy the source state to the destination state. | |
728 | * To simplify the source, this is not supported for 16-bit MSDOS (which | |
729 | * doesn't have enough memory anyway to duplicate compression states). | |
730 | */ | |
731 | int ZEXPORT deflateCopy (dest, source) | |
732 | z_streamp dest; | |
733 | z_streamp source; | |
734 | { | |
735 | #ifdef MAXSEG_64K | |
736 | return Z_STREAM_ERROR; | |
737 | #else | |
738 | deflate_state *ds; | |
739 | deflate_state *ss; | |
740 | ushf *overlay; | |
741 | ||
d4286ec4 | 742 | |
06b91d8e | 743 | if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { |
d4286ec4 PM |
744 | return Z_STREAM_ERROR; |
745 | } | |
06b91d8e MP |
746 | |
747 | ss = source->state; | |
748 | ||
d4286ec4 PM |
749 | *dest = *source; |
750 | ||
751 | ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); | |
752 | if (ds == Z_NULL) return Z_MEM_ERROR; | |
753 | dest->state = (struct internal_state FAR *) ds; | |
754 | *ds = *ss; | |
755 | ds->strm = dest; | |
756 | ||
757 | ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); | |
758 | ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); | |
759 | ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); | |
760 | overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); | |
761 | ds->pending_buf = (uchf *) overlay; | |
762 | ||
763 | if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || | |
764 | ds->pending_buf == Z_NULL) { | |
765 | deflateEnd (dest); | |
766 | return Z_MEM_ERROR; | |
767 | } | |
768 | /* following zmemcpy do not work for 16-bit MSDOS */ | |
769 | zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); | |
770 | zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos)); | |
771 | zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos)); | |
772 | zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); | |
773 | ||
774 | ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); | |
775 | ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); | |
776 | ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; | |
777 | ||
778 | ds->l_desc.dyn_tree = ds->dyn_ltree; | |
779 | ds->d_desc.dyn_tree = ds->dyn_dtree; | |
780 | ds->bl_desc.dyn_tree = ds->bl_tree; | |
781 | ||
782 | return Z_OK; | |
1e1cf689 | 783 | #endif /* MAXSEG_64K */ |
d4286ec4 PM |
784 | } |
785 | ||
786 | /* =========================================================================== | |
787 | * Read a new buffer from the current input stream, update the adler32 | |
788 | * and total number of bytes read. All deflate() input goes through | |
789 | * this function so some applications may wish to modify it to avoid | |
790 | * allocating a large strm->next_in buffer and copying from it. | |
791 | * (See also flush_pending()). | |
792 | */ | |
12febd80 | 793 | local int read_buf(strm, buf, size) |
d4286ec4 PM |
794 | z_streamp strm; |
795 | Bytef *buf; | |
796 | unsigned size; | |
797 | { | |
798 | unsigned len = strm->avail_in; | |
799 | ||
800 | if (len > size) len = size; | |
801 | if (len == 0) return 0; | |
802 | ||
803 | strm->avail_in -= len; | |
804 | ||
1e1cf689 | 805 | if (strm->state->wrap == 1) { |
d4286ec4 PM |
806 | strm->adler = adler32(strm->adler, strm->next_in, len); |
807 | } | |
1e1cf689 WD |
808 | #ifdef GZIP |
809 | else if (strm->state->wrap == 2) { | |
810 | strm->adler = crc32(strm->adler, strm->next_in, len); | |
811 | } | |
812 | #endif | |
d4286ec4 PM |
813 | zmemcpy(buf, strm->next_in, len); |
814 | strm->next_in += len; | |
815 | strm->total_in += len; | |
816 | ||
817 | return (int)len; | |
818 | } | |
819 | ||
820 | /* =========================================================================== | |
821 | * Initialize the "longest match" routines for a new zlib stream | |
822 | */ | |
823 | local void lm_init (s) | |
824 | deflate_state *s; | |
825 | { | |
826 | s->window_size = (ulg)2L*s->w_size; | |
827 | ||
828 | CLEAR_HASH(s); | |
829 | ||
830 | /* Set the default configuration parameters: | |
831 | */ | |
832 | s->max_lazy_match = configuration_table[s->level].max_lazy; | |
833 | s->good_match = configuration_table[s->level].good_length; | |
834 | s->nice_match = configuration_table[s->level].nice_length; | |
835 | s->max_chain_length = configuration_table[s->level].max_chain; | |
836 | ||
837 | s->strstart = 0; | |
838 | s->block_start = 0L; | |
839 | s->lookahead = 0; | |
840 | s->match_length = s->prev_length = MIN_MATCH-1; | |
841 | s->match_available = 0; | |
842 | s->ins_h = 0; | |
843 | #ifdef ASMV | |
844 | match_init(); /* initialize the asm code */ | |
845 | #endif | |
846 | } | |
847 | ||
1e1cf689 | 848 | #ifndef FASTEST |
d4286ec4 PM |
849 | /* =========================================================================== |
850 | * Set match_start to the longest match starting at the given string and | |
851 | * return its length. Matches shorter or equal to prev_length are discarded, | |
852 | * in which case the result is equal to prev_length and match_start is | |
853 | * garbage. | |
854 | * IN assertions: cur_match is the head of the hash chain for the current | |
855 | * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 | |
856 | * OUT assertion: the match length is not greater than s->lookahead. | |
857 | */ | |
858 | #ifndef ASMV | |
859 | /* For 80x86 and 680x0, an optimized version will be provided in match.asm or | |
860 | * match.S. The code will be functionally equivalent. | |
861 | */ | |
d4286ec4 PM |
862 | local uInt longest_match(s, cur_match) |
863 | deflate_state *s; | |
864 | IPos cur_match; /* current match */ | |
865 | { | |
866 | unsigned chain_length = s->max_chain_length;/* max hash chain length */ | |
867 | register Bytef *scan = s->window + s->strstart; /* current string */ | |
868 | register Bytef *match; /* matched string */ | |
869 | register int len; /* length of current match */ | |
870 | int best_len = s->prev_length; /* best match length so far */ | |
871 | int nice_match = s->nice_match; /* stop if match long enough */ | |
872 | IPos limit = s->strstart > (IPos)MAX_DIST(s) ? | |
873 | s->strstart - (IPos)MAX_DIST(s) : NIL; | |
874 | /* Stop when cur_match becomes <= limit. To simplify the code, | |
875 | * we prevent matches with the string of window index 0. | |
876 | */ | |
877 | Posf *prev = s->prev; | |
878 | uInt wmask = s->w_mask; | |
879 | ||
880 | #ifdef UNALIGNED_OK | |
881 | /* Compare two bytes at a time. Note: this is not always beneficial. | |
882 | * Try with and without -DUNALIGNED_OK to check. | |
883 | */ | |
884 | register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; | |
885 | register ush scan_start = *(ushf*)scan; | |
886 | register ush scan_end = *(ushf*)(scan+best_len-1); | |
887 | #else | |
888 | register Bytef *strend = s->window + s->strstart + MAX_MATCH; | |
889 | register Byte scan_end1 = scan[best_len-1]; | |
890 | register Byte scan_end = scan[best_len]; | |
891 | #endif | |
892 | ||
893 | /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. | |
894 | * It is easy to get rid of this optimization if necessary. | |
895 | */ | |
896 | Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); | |
897 | ||
898 | /* Do not waste too much time if we already have a good match: */ | |
899 | if (s->prev_length >= s->good_match) { | |
900 | chain_length >>= 2; | |
901 | } | |
902 | /* Do not look for matches beyond the end of the input. This is necessary | |
903 | * to make deflate deterministic. | |
904 | */ | |
905 | if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; | |
906 | ||
907 | Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); | |
908 | ||
909 | do { | |
910 | Assert(cur_match < s->strstart, "no future"); | |
911 | match = s->window + cur_match; | |
912 | ||
913 | /* Skip to next match if the match length cannot increase | |
914 | * or if the match length is less than 2: | |
915 | */ | |
916 | #if (defined(UNALIGNED_OK) && MAX_MATCH == 258) | |
917 | /* This code assumes sizeof(unsigned short) == 2. Do not use | |
918 | * UNALIGNED_OK if your compiler uses a different size. | |
919 | */ | |
920 | if (*(ushf*)(match+best_len-1) != scan_end || | |
921 | *(ushf*)match != scan_start) continue; | |
922 | ||
923 | /* It is not necessary to compare scan[2] and match[2] since they are | |
924 | * always equal when the other bytes match, given that the hash keys | |
925 | * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at | |
926 | * strstart+3, +5, ... up to strstart+257. We check for insufficient | |
927 | * lookahead only every 4th comparison; the 128th check will be made | |
928 | * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is | |
929 | * necessary to put more guard bytes at the end of the window, or | |
930 | * to check more often for insufficient lookahead. | |
931 | */ | |
932 | Assert(scan[2] == match[2], "scan[2]?"); | |
933 | scan++, match++; | |
934 | do { | |
935 | } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && | |
936 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && | |
937 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && | |
938 | *(ushf*)(scan+=2) == *(ushf*)(match+=2) && | |
939 | scan < strend); | |
940 | /* The funny "do {}" generates better code on most compilers */ | |
941 | ||
942 | /* Here, scan <= window+strstart+257 */ | |
943 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); | |
944 | if (*scan == *match) scan++; | |
945 | ||
946 | len = (MAX_MATCH - 1) - (int)(strend-scan); | |
947 | scan = strend - (MAX_MATCH-1); | |
948 | ||
949 | #else /* UNALIGNED_OK */ | |
950 | ||
951 | if (match[best_len] != scan_end || | |
952 | match[best_len-1] != scan_end1 || | |
953 | *match != *scan || | |
954 | *++match != scan[1]) continue; | |
955 | ||
956 | /* The check at best_len-1 can be removed because it will be made | |
957 | * again later. (This heuristic is not always a win.) | |
958 | * It is not necessary to compare scan[2] and match[2] since they | |
959 | * are always equal when the other bytes match, given that | |
960 | * the hash keys are equal and that HASH_BITS >= 8. | |
961 | */ | |
962 | scan += 2, match++; | |
963 | Assert(*scan == *match, "match[2]?"); | |
964 | ||
965 | /* We check for insufficient lookahead only every 8th comparison; | |
966 | * the 256th check will be made at strstart+258. | |
967 | */ | |
968 | do { | |
969 | } while (*++scan == *++match && *++scan == *++match && | |
970 | *++scan == *++match && *++scan == *++match && | |
971 | *++scan == *++match && *++scan == *++match && | |
972 | *++scan == *++match && *++scan == *++match && | |
973 | scan < strend); | |
974 | ||
975 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); | |
976 | ||
977 | len = MAX_MATCH - (int)(strend - scan); | |
978 | scan = strend - MAX_MATCH; | |
979 | ||
980 | #endif /* UNALIGNED_OK */ | |
981 | ||
982 | if (len > best_len) { | |
983 | s->match_start = cur_match; | |
984 | best_len = len; | |
985 | if (len >= nice_match) break; | |
986 | #ifdef UNALIGNED_OK | |
987 | scan_end = *(ushf*)(scan+best_len-1); | |
988 | #else | |
989 | scan_end1 = scan[best_len-1]; | |
990 | scan_end = scan[best_len]; | |
991 | #endif | |
992 | } | |
993 | } while ((cur_match = prev[cur_match & wmask]) > limit | |
994 | && --chain_length != 0); | |
995 | ||
996 | if ((uInt)best_len <= s->lookahead) return (uInt)best_len; | |
997 | return s->lookahead; | |
998 | } | |
1e1cf689 WD |
999 | #endif /* ASMV */ |
1000 | #endif /* FASTEST */ | |
d4286ec4 | 1001 | |
d4286ec4 | 1002 | /* --------------------------------------------------------------------------- |
1e1cf689 | 1003 | * Optimized version for level == 1 or strategy == Z_RLE only |
d4286ec4 | 1004 | */ |
1e1cf689 | 1005 | local uInt longest_match_fast(s, cur_match) |
d4286ec4 PM |
1006 | deflate_state *s; |
1007 | IPos cur_match; /* current match */ | |
1008 | { | |
1009 | register Bytef *scan = s->window + s->strstart; /* current string */ | |
1010 | register Bytef *match; /* matched string */ | |
1011 | register int len; /* length of current match */ | |
1012 | register Bytef *strend = s->window + s->strstart + MAX_MATCH; | |
1013 | ||
1014 | /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. | |
1015 | * It is easy to get rid of this optimization if necessary. | |
1016 | */ | |
1017 | Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); | |
1018 | ||
1019 | Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); | |
1020 | ||
1021 | Assert(cur_match < s->strstart, "no future"); | |
1022 | ||
1023 | match = s->window + cur_match; | |
1024 | ||
1025 | /* Return failure if the match length is less than 2: | |
1026 | */ | |
1027 | if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; | |
1028 | ||
1029 | /* The check at best_len-1 can be removed because it will be made | |
1030 | * again later. (This heuristic is not always a win.) | |
1031 | * It is not necessary to compare scan[2] and match[2] since they | |
1032 | * are always equal when the other bytes match, given that | |
1033 | * the hash keys are equal and that HASH_BITS >= 8. | |
1034 | */ | |
1035 | scan += 2, match += 2; | |
1036 | Assert(*scan == *match, "match[2]?"); | |
1037 | ||
1038 | /* We check for insufficient lookahead only every 8th comparison; | |
1039 | * the 256th check will be made at strstart+258. | |
1040 | */ | |
1041 | do { | |
1042 | } while (*++scan == *++match && *++scan == *++match && | |
1e1cf689 WD |
1043 | *++scan == *++match && *++scan == *++match && |
1044 | *++scan == *++match && *++scan == *++match && | |
1045 | *++scan == *++match && *++scan == *++match && | |
1046 | scan < strend); | |
d4286ec4 PM |
1047 | |
1048 | Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); | |
1049 | ||
1050 | len = MAX_MATCH - (int)(strend - scan); | |
1051 | ||
1052 | if (len < MIN_MATCH) return MIN_MATCH - 1; | |
1053 | ||
1054 | s->match_start = cur_match; | |
1e1cf689 | 1055 | return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; |
d4286ec4 | 1056 | } |
d4286ec4 PM |
1057 | |
1058 | #ifdef DEBUG | |
1059 | /* =========================================================================== | |
1060 | * Check that the match at match_start is indeed a match. | |
1061 | */ | |
1062 | local void check_match(s, start, match, length) | |
1063 | deflate_state *s; | |
1064 | IPos start, match; | |
1065 | int length; | |
1066 | { | |
1067 | /* check that the match is indeed a match */ | |
1068 | if (zmemcmp(s->window + match, | |
1069 | s->window + start, length) != EQUAL) { | |
1070 | fprintf(stderr, " start %u, match %u, length %d\n", | |
1e1cf689 | 1071 | start, match, length); |
d4286ec4 | 1072 | do { |
1e1cf689 WD |
1073 | fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); |
1074 | } while (--length != 0); | |
d4286ec4 PM |
1075 | z_error("invalid match"); |
1076 | } | |
1077 | if (z_verbose > 1) { | |
1078 | fprintf(stderr,"\\[%d,%d]", start-match, length); | |
1079 | do { putc(s->window[start++], stderr); } while (--length != 0); | |
1080 | } | |
1081 | } | |
1082 | #else | |
1083 | # define check_match(s, start, match, length) | |
1e1cf689 | 1084 | #endif /* DEBUG */ |
d4286ec4 PM |
1085 | |
1086 | /* =========================================================================== | |
1087 | * Fill the window when the lookahead becomes insufficient. | |
1088 | * Updates strstart and lookahead. | |
1089 | * | |
1090 | * IN assertion: lookahead < MIN_LOOKAHEAD | |
1091 | * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD | |
1092 | * At least one byte has been read, or avail_in == 0; reads are | |
1093 | * performed for at least two bytes (required for the zip translate_eol | |
1094 | * option -- not supported here). | |
1095 | */ | |
1096 | local void fill_window(s) | |
1097 | deflate_state *s; | |
1098 | { | |
1099 | register unsigned n, m; | |
1100 | register Posf *p; | |
1101 | unsigned more; /* Amount of free space at the end of the window. */ | |
1102 | uInt wsize = s->w_size; | |
1103 | ||
1104 | do { | |
1105 | more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); | |
1106 | ||
1107 | /* Deal with !@#$% 64K limit: */ | |
1e1cf689 WD |
1108 | if (sizeof(int) <= 2) { |
1109 | if (more == 0 && s->strstart == 0 && s->lookahead == 0) { | |
1110 | more = wsize; | |
d4286ec4 | 1111 | |
1e1cf689 WD |
1112 | } else if (more == (unsigned)(-1)) { |
1113 | /* Very unlikely, but possible on 16 bit machine if | |
1114 | * strstart == 0 && lookahead == 1 (input done a byte at time) | |
1115 | */ | |
1116 | more--; | |
1117 | } | |
1118 | } | |
d4286ec4 PM |
1119 | |
1120 | /* If the window is almost full and there is insufficient lookahead, | |
1121 | * move the upper half to the lower one to make room in the upper half. | |
1122 | */ | |
1e1cf689 | 1123 | if (s->strstart >= wsize+MAX_DIST(s)) { |
d4286ec4 PM |
1124 | |
1125 | zmemcpy(s->window, s->window+wsize, (unsigned)wsize); | |
1126 | s->match_start -= wsize; | |
1127 | s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ | |
1128 | s->block_start -= (long) wsize; | |
1129 | ||
1130 | /* Slide the hash table (could be avoided with 32 bit values | |
1131 | at the expense of memory usage). We slide even when level == 0 | |
1132 | to keep the hash table consistent if we switch back to level > 0 | |
1133 | later. (Using level 0 permanently is not an optimal usage of | |
1134 | zlib, so we don't care about this pathological case.) | |
1135 | */ | |
1e1cf689 WD |
1136 | n = s->hash_size; |
1137 | p = &s->head[n]; | |
1138 | do { | |
1139 | m = *--p; | |
1140 | *p = (Pos)(m >= wsize ? m-wsize : NIL); | |
1141 | } while (--n); | |
1142 | ||
1143 | n = wsize; | |
d4286ec4 | 1144 | #ifndef FASTEST |
1e1cf689 WD |
1145 | p = &s->prev[n]; |
1146 | do { | |
1147 | m = *--p; | |
1148 | *p = (Pos)(m >= wsize ? m-wsize : NIL); | |
1149 | /* If n is not on any hash chain, prev[n] is garbage but | |
1150 | * its value will never be used. | |
1151 | */ | |
1152 | } while (--n); | |
d4286ec4 PM |
1153 | #endif |
1154 | more += wsize; | |
1155 | } | |
1156 | if (s->strm->avail_in == 0) return; | |
1157 | ||
1158 | /* If there was no sliding: | |
1159 | * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && | |
1160 | * more == window_size - lookahead - strstart | |
1161 | * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) | |
1162 | * => more >= window_size - 2*WSIZE + 2 | |
1163 | * In the BIG_MEM or MMAP case (not yet supported), | |
1164 | * window_size == input_size + MIN_LOOKAHEAD && | |
1165 | * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. | |
1166 | * Otherwise, window_size == 2*WSIZE so more >= 2. | |
1167 | * If there was sliding, more >= WSIZE. So in all cases, more >= 2. | |
1168 | */ | |
1169 | Assert(more >= 2, "more < 2"); | |
1170 | ||
12febd80 | 1171 | n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); |
d4286ec4 PM |
1172 | s->lookahead += n; |
1173 | ||
1174 | /* Initialize the hash value now that we have some input: */ | |
1175 | if (s->lookahead >= MIN_MATCH) { | |
1176 | s->ins_h = s->window[s->strstart]; | |
1177 | UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); | |
1178 | #if MIN_MATCH != 3 | |
1179 | Call UPDATE_HASH() MIN_MATCH-3 more times | |
1180 | #endif | |
1181 | } | |
1182 | /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, | |
1183 | * but this is not important since only literal bytes will be emitted. | |
1184 | */ | |
1185 | ||
1186 | } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); | |
1187 | } | |
1188 | ||
1189 | /* =========================================================================== | |
1190 | * Flush the current block, with given end-of-file flag. | |
1191 | * IN assertion: strstart is set to the end of the current match. | |
1192 | */ | |
1193 | #define FLUSH_BLOCK_ONLY(s, eof) { \ | |
1194 | _tr_flush_block(s, (s->block_start >= 0L ? \ | |
1195 | (charf *)&s->window[(unsigned)s->block_start] : \ | |
1196 | (charf *)Z_NULL), \ | |
1e1cf689 WD |
1197 | (ulg)((long)s->strstart - s->block_start), \ |
1198 | (eof)); \ | |
d4286ec4 PM |
1199 | s->block_start = s->strstart; \ |
1200 | flush_pending(s->strm); \ | |
1201 | Tracev((stderr,"[FLUSH]")); \ | |
1202 | } | |
1203 | ||
1204 | /* Same but force premature exit if necessary. */ | |
1205 | #define FLUSH_BLOCK(s, eof) { \ | |
1206 | FLUSH_BLOCK_ONLY(s, eof); \ | |
1207 | if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \ | |
1208 | } | |
1209 | ||
1210 | /* =========================================================================== | |
1211 | * Copy without compression as much as possible from the input stream, return | |
1212 | * the current block state. | |
1213 | * This function does not insert new strings in the dictionary since | |
1214 | * uncompressible data is probably not useful. This function is used | |
1215 | * only for the level=0 compression option. | |
1216 | * NOTE: this function should be optimized to avoid extra copying from | |
1217 | * window to pending_buf. | |
1218 | */ | |
1219 | local block_state deflate_stored(s, flush) | |
1220 | deflate_state *s; | |
1221 | int flush; | |
1222 | { | |
1223 | /* Stored blocks are limited to 0xffff bytes, pending_buf is limited | |
1224 | * to pending_buf_size, and each stored block has a 5 byte header: | |
1225 | */ | |
1226 | ulg max_block_size = 0xffff; | |
1227 | ulg max_start; | |
1228 | ||
1229 | if (max_block_size > s->pending_buf_size - 5) { | |
1230 | max_block_size = s->pending_buf_size - 5; | |
1231 | } | |
1232 | ||
1233 | /* Copy as much as possible from input to output: */ | |
1234 | for (;;) { | |
1235 | /* Fill the window as much as possible: */ | |
1236 | if (s->lookahead <= 1) { | |
1237 | ||
1238 | Assert(s->strstart < s->w_size+MAX_DIST(s) || | |
1e1cf689 | 1239 | s->block_start >= (long)s->w_size, "slide too late"); |
d4286ec4 PM |
1240 | |
1241 | fill_window(s); | |
1242 | if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; | |
1243 | ||
1244 | if (s->lookahead == 0) break; /* flush the current block */ | |
1245 | } | |
1e1cf689 | 1246 | Assert(s->block_start >= 0L, "block gone"); |
d4286ec4 | 1247 | |
1e1cf689 WD |
1248 | s->strstart += s->lookahead; |
1249 | s->lookahead = 0; | |
d4286ec4 | 1250 | |
0301b334 WD |
1251 | if (flush == Z_INSERT_ONLY) { |
1252 | s->block_start = s->strstart; | |
1253 | continue; | |
1254 | } | |
1255 | ||
1e1cf689 WD |
1256 | /* Emit a stored block if pending_buf will be full: */ |
1257 | max_start = s->block_start + max_block_size; | |
d4286ec4 | 1258 | if (s->strstart == 0 || (ulg)s->strstart >= max_start) { |
1e1cf689 WD |
1259 | /* strstart == 0 is possible when wraparound on 16-bit machine */ |
1260 | s->lookahead = (uInt)(s->strstart - max_start); | |
1261 | s->strstart = (uInt)max_start; | |
d4286ec4 | 1262 | FLUSH_BLOCK(s, 0); |
1e1cf689 WD |
1263 | } |
1264 | /* Flush if we may have to slide, otherwise block_start may become | |
d4286ec4 PM |
1265 | * negative and the data will be gone: |
1266 | */ | |
1267 | if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { | |
1268 | FLUSH_BLOCK(s, 0); | |
1e1cf689 | 1269 | } |
d4286ec4 | 1270 | } |
0301b334 WD |
1271 | if (flush == Z_INSERT_ONLY) { |
1272 | s->block_start = s->strstart; | |
1273 | return need_more; | |
1274 | } | |
1275 | ||
d4286ec4 PM |
1276 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1277 | return flush == Z_FINISH ? finish_done : block_done; | |
1278 | } | |
1279 | ||
1280 | /* =========================================================================== | |
1281 | * Compress as much as possible from the input stream, return the current | |
1282 | * block state. | |
1283 | * This function does not perform lazy evaluation of matches and inserts | |
1284 | * new strings in the dictionary only for unmatched strings or for short | |
1285 | * matches. It is used only for the fast compression options. | |
1286 | */ | |
1287 | local block_state deflate_fast(s, flush) | |
1288 | deflate_state *s; | |
1289 | int flush; | |
1290 | { | |
1291 | IPos hash_head = NIL; /* head of the hash chain */ | |
1292 | int bflush; /* set if current block must be flushed */ | |
1293 | ||
1294 | for (;;) { | |
1295 | /* Make sure that we always have enough lookahead, except | |
1296 | * at the end of the input file. We need MAX_MATCH bytes | |
1297 | * for the next match, plus MIN_MATCH bytes to insert the | |
1298 | * string following the next match. | |
1299 | */ | |
1300 | if (s->lookahead < MIN_LOOKAHEAD) { | |
1301 | fill_window(s); | |
1302 | if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { | |
1e1cf689 WD |
1303 | return need_more; |
1304 | } | |
d4286ec4 PM |
1305 | if (s->lookahead == 0) break; /* flush the current block */ |
1306 | } | |
1307 | ||
1308 | /* Insert the string window[strstart .. strstart+2] in the | |
1309 | * dictionary, and set hash_head to the head of the hash chain: | |
1310 | */ | |
1311 | if (s->lookahead >= MIN_MATCH) { | |
1312 | INSERT_STRING(s, s->strstart, hash_head); | |
1313 | } | |
1314 | ||
5914bf15 PM |
1315 | if (flush == Z_INSERT_ONLY) { |
1316 | s->strstart++; | |
1317 | s->lookahead--; | |
1318 | continue; | |
1319 | } | |
1320 | ||
d4286ec4 PM |
1321 | /* Find the longest match, discarding those <= prev_length. |
1322 | * At this point we have always match_length < MIN_MATCH | |
1323 | */ | |
1324 | if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { | |
1325 | /* To simplify the code, we prevent matches with the string | |
1326 | * of window index 0 (in particular we have to avoid a match | |
1327 | * of the string with itself at the start of the input file). | |
1328 | */ | |
1e1cf689 WD |
1329 | #ifdef FASTEST |
1330 | if ((s->strategy < Z_HUFFMAN_ONLY) || | |
1331 | (s->strategy == Z_RLE && s->strstart - hash_head == 1)) { | |
1332 | s->match_length = longest_match_fast (s, hash_head); | |
1333 | } | |
1334 | #else | |
1335 | if (s->strategy < Z_HUFFMAN_ONLY) { | |
d4286ec4 | 1336 | s->match_length = longest_match (s, hash_head); |
1e1cf689 WD |
1337 | } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { |
1338 | s->match_length = longest_match_fast (s, hash_head); | |
d4286ec4 | 1339 | } |
1e1cf689 WD |
1340 | #endif |
1341 | /* longest_match() or longest_match_fast() sets match_start */ | |
d4286ec4 PM |
1342 | } |
1343 | if (s->match_length >= MIN_MATCH) { | |
1344 | check_match(s, s->strstart, s->match_start, s->match_length); | |
1345 | ||
1346 | _tr_tally_dist(s, s->strstart - s->match_start, | |
1347 | s->match_length - MIN_MATCH, bflush); | |
1348 | ||
1349 | s->lookahead -= s->match_length; | |
1350 | ||
1351 | /* Insert new strings in the hash table only if the match length | |
1352 | * is not too large. This saves time but degrades compression. | |
1353 | */ | |
1354 | #ifndef FASTEST | |
1355 | if (s->match_length <= s->max_insert_length && | |
1356 | s->lookahead >= MIN_MATCH) { | |
1e1cf689 | 1357 | s->match_length--; /* string at strstart already in table */ |
d4286ec4 PM |
1358 | do { |
1359 | s->strstart++; | |
1360 | INSERT_STRING(s, s->strstart, hash_head); | |
1361 | /* strstart never exceeds WSIZE-MAX_MATCH, so there are | |
1362 | * always MIN_MATCH bytes ahead. | |
1363 | */ | |
1364 | } while (--s->match_length != 0); | |
1e1cf689 | 1365 | s->strstart++; |
d4286ec4 PM |
1366 | } else |
1367 | #endif | |
1e1cf689 | 1368 | { |
d4286ec4 PM |
1369 | s->strstart += s->match_length; |
1370 | s->match_length = 0; | |
1371 | s->ins_h = s->window[s->strstart]; | |
1372 | UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); | |
1373 | #if MIN_MATCH != 3 | |
1374 | Call UPDATE_HASH() MIN_MATCH-3 more times | |
1375 | #endif | |
1376 | /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not | |
1377 | * matter since it will be recomputed at next deflate call. | |
1378 | */ | |
1379 | } | |
1380 | } else { | |
1381 | /* No match, output a literal byte */ | |
1382 | Tracevv((stderr,"%c", s->window[s->strstart])); | |
1383 | _tr_tally_lit (s, s->window[s->strstart], bflush); | |
1384 | s->lookahead--; | |
1e1cf689 | 1385 | s->strstart++; |
d4286ec4 PM |
1386 | } |
1387 | if (bflush) FLUSH_BLOCK(s, 0); | |
1388 | } | |
5914bf15 PM |
1389 | if (flush == Z_INSERT_ONLY) { |
1390 | s->block_start = s->strstart; | |
1391 | return need_more; | |
1392 | } | |
d4286ec4 PM |
1393 | FLUSH_BLOCK(s, flush == Z_FINISH); |
1394 | return flush == Z_FINISH ? finish_done : block_done; | |
1395 | } | |
1396 | ||
1e1cf689 | 1397 | #ifndef FASTEST |
d4286ec4 PM |
1398 | /* =========================================================================== |
1399 | * Same as above, but achieves better compression. We use a lazy | |
1400 | * evaluation for matches: a match is finally adopted only if there is | |
1401 | * no better match at the next window position. | |
1402 | */ | |
1403 | local block_state deflate_slow(s, flush) | |
1404 | deflate_state *s; | |
1405 | int flush; | |
1406 | { | |
1407 | IPos hash_head = NIL; /* head of hash chain */ | |
1408 | int bflush; /* set if current block must be flushed */ | |
1409 | ||
1410 | /* Process the input block. */ | |
1411 | for (;;) { | |
1412 | /* Make sure that we always have enough lookahead, except | |
1413 | * at the end of the input file. We need MAX_MATCH bytes | |
1414 | * for the next match, plus MIN_MATCH bytes to insert the | |
1415 | * string following the next match. | |
1416 | */ | |
1417 | if (s->lookahead < MIN_LOOKAHEAD) { | |
1418 | fill_window(s); | |
1419 | if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { | |
1e1cf689 WD |
1420 | return need_more; |
1421 | } | |
d4286ec4 PM |
1422 | if (s->lookahead == 0) break; /* flush the current block */ |
1423 | } | |
1424 | ||
1425 | /* Insert the string window[strstart .. strstart+2] in the | |
1426 | * dictionary, and set hash_head to the head of the hash chain: | |
1427 | */ | |
1428 | if (s->lookahead >= MIN_MATCH) { | |
1429 | INSERT_STRING(s, s->strstart, hash_head); | |
1430 | } | |
1431 | ||
5914bf15 PM |
1432 | if (flush == Z_INSERT_ONLY) { |
1433 | s->strstart++; | |
1434 | s->lookahead--; | |
1435 | continue; | |
1436 | } | |
1437 | ||
d4286ec4 PM |
1438 | /* Find the longest match, discarding those <= prev_length. |
1439 | */ | |
1440 | s->prev_length = s->match_length, s->prev_match = s->match_start; | |
1441 | s->match_length = MIN_MATCH-1; | |
1442 | ||
1443 | if (hash_head != NIL && s->prev_length < s->max_lazy_match && | |
1444 | s->strstart - hash_head <= MAX_DIST(s)) { | |
1445 | /* To simplify the code, we prevent matches with the string | |
1446 | * of window index 0 (in particular we have to avoid a match | |
1447 | * of the string with itself at the start of the input file). | |
1448 | */ | |
1e1cf689 | 1449 | if (s->strategy < Z_HUFFMAN_ONLY) { |
d4286ec4 | 1450 | s->match_length = longest_match (s, hash_head); |
1e1cf689 WD |
1451 | } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { |
1452 | s->match_length = longest_match_fast (s, hash_head); | |
d4286ec4 | 1453 | } |
1e1cf689 | 1454 | /* longest_match() or longest_match_fast() sets match_start */ |
d4286ec4 | 1455 | |
1e1cf689 WD |
1456 | if (s->match_length <= 5 && (s->strategy == Z_FILTERED |
1457 | #if TOO_FAR <= 32767 | |
1458 | || (s->match_length == MIN_MATCH && | |
1459 | s->strstart - s->match_start > TOO_FAR) | |
1460 | #endif | |
1461 | )) { | |
d4286ec4 PM |
1462 | |
1463 | /* If prev_match is also MIN_MATCH, match_start is garbage | |
1464 | * but we will ignore the current match anyway. | |
1465 | */ | |
1466 | s->match_length = MIN_MATCH-1; | |
1467 | } | |
1468 | } | |
1469 | /* If there was a match at the previous step and the current | |
1470 | * match is not better, output the previous match: | |
1471 | */ | |
1472 | if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { | |
1473 | uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; | |
1474 | /* Do not insert strings in hash table beyond this. */ | |
1475 | ||
1476 | check_match(s, s->strstart-1, s->prev_match, s->prev_length); | |
1477 | ||
1478 | _tr_tally_dist(s, s->strstart -1 - s->prev_match, | |
1e1cf689 | 1479 | s->prev_length - MIN_MATCH, bflush); |
d4286ec4 PM |
1480 | |
1481 | /* Insert in hash table all strings up to the end of the match. | |
1482 | * strstart-1 and strstart are already inserted. If there is not | |
1483 | * enough lookahead, the last two strings are not inserted in | |
1484 | * the hash table. | |
1485 | */ | |
1486 | s->lookahead -= s->prev_length-1; | |
1487 | s->prev_length -= 2; | |
1488 | do { | |
1489 | if (++s->strstart <= max_insert) { | |
1490 | INSERT_STRING(s, s->strstart, hash_head); | |
1491 | } | |
1492 | } while (--s->prev_length != 0); | |
1493 | s->match_available = 0; | |
1494 | s->match_length = MIN_MATCH-1; | |
1495 | s->strstart++; | |
1496 | ||
1497 | if (bflush) FLUSH_BLOCK(s, 0); | |
1498 | ||
1499 | } else if (s->match_available) { | |
1500 | /* If there was no match at the previous position, output a | |
1501 | * single literal. If there was a match but the current match | |
1502 | * is longer, truncate the previous match to a single literal. | |
1503 | */ | |
1504 | Tracevv((stderr,"%c", s->window[s->strstart-1])); | |
1e1cf689 WD |
1505 | _tr_tally_lit(s, s->window[s->strstart-1], bflush); |
1506 | if (bflush) { | |
d4286ec4 PM |
1507 | FLUSH_BLOCK_ONLY(s, 0); |
1508 | } | |
1509 | s->strstart++; | |
1510 | s->lookahead--; | |
1511 | if (s->strm->avail_out == 0) return need_more; | |
1512 | } else { | |
1513 | /* There is no previous match to compare with, wait for | |
1514 | * the next step to decide. | |
1515 | */ | |
1516 | s->match_available = 1; | |
1517 | s->strstart++; | |
1518 | s->lookahead--; | |
1519 | } | |
1520 | } | |
5914bf15 PM |
1521 | if (flush == Z_INSERT_ONLY) { |
1522 | s->block_start = s->strstart; | |
1523 | return need_more; | |
1524 | } | |
d4286ec4 PM |
1525 | Assert (flush != Z_NO_FLUSH, "no flush?"); |
1526 | if (s->match_available) { | |
1527 | Tracevv((stderr,"%c", s->window[s->strstart-1])); | |
1528 | _tr_tally_lit(s, s->window[s->strstart-1], bflush); | |
1529 | s->match_available = 0; | |
1530 | } | |
1531 | FLUSH_BLOCK(s, flush == Z_FINISH); | |
1532 | return flush == Z_FINISH ? finish_done : block_done; | |
1533 | } | |
1e1cf689 | 1534 | #endif /* FASTEST */ |