Line data Source code
1 : /* $OpenBSD: deflate.c,v 1.3 2016/03/14 23:08:06 krw Exp $ */
2 : /* deflate.c -- compress data using the deflation algorithm
3 : * Copyright (C) 1995-2005 Jean-loup Gailly.
4 : * For conditions of distribution and use, see copyright notice in zlib.h
5 : */
6 :
7 : /*
8 : * ALGORITHM
9 : *
10 : * The "deflation" process depends on being able to identify portions
11 : * of the input text which are identical to earlier input (within a
12 : * sliding window trailing behind the input currently being processed).
13 : *
14 : * The most straightforward technique turns out to be the fastest for
15 : * most input files: try all possible matches and select the longest.
16 : * The key feature of this algorithm is that insertions into the string
17 : * dictionary are very simple and thus fast, and deletions are avoided
18 : * completely. Insertions are performed at each input character, whereas
19 : * string matches are performed only when the previous match ends. So it
20 : * is preferable to spend more time in matches to allow very fast string
21 : * insertions and avoid deletions. The matching algorithm for small
22 : * strings is inspired from that of Rabin & Karp. A brute force approach
23 : * is used to find longer strings when a small match has been found.
24 : * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
25 : * (by Leonid Broukhis).
26 : * A previous version of this file used a more sophisticated algorithm
27 : * (by Fiala and Greene) which is guaranteed to run in linear amortized
28 : * time, but has a larger average cost, uses more memory and is patented.
29 : * However the F&G algorithm may be faster for some highly redundant
30 : * files if the parameter max_chain_length (described below) is too large.
31 : *
32 : * ACKNOWLEDGEMENTS
33 : *
34 : * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
35 : * I found it in 'freeze' written by Leonid Broukhis.
36 : * Thanks to many people for bug reports and testing.
37 : *
38 : * REFERENCES
39 : *
40 : * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
41 : * Available in http://www.ietf.org/rfc/rfc1951.txt
42 : *
43 : * A description of the Rabin and Karp algorithm is given in the book
44 : * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
45 : *
46 : * Fiala,E.R., and Greene,D.H.
47 : * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
48 : *
49 : */
50 :
51 :
52 : #include "deflate.h"
53 :
54 : /*
55 : If you use the zlib library in a product, an acknowledgment is welcome
56 : in the documentation of your product. If for some reason you cannot
57 : include such an acknowledgment, I would appreciate that you keep this
58 : copyright string in the executable of your product.
59 : */
60 :
61 : /* ===========================================================================
62 : * Function prototypes.
63 : */
64 : typedef enum {
65 : need_more, /* block not completed, need more input or more output */
66 : block_done, /* block flush performed */
67 : finish_started, /* finish started, need only more output at next deflate */
68 : finish_done /* finish done, accept no more input or output */
69 : } block_state;
70 :
71 : typedef block_state (*compress_func) OF((deflate_state *s, int flush));
72 : /* Compression function. Returns the block state after the call. */
73 :
74 : local void fill_window OF((deflate_state *s));
75 : local block_state deflate_stored OF((deflate_state *s, int flush));
76 : local block_state deflate_fast OF((deflate_state *s, int flush));
77 : #ifndef FASTEST
78 : local block_state deflate_slow OF((deflate_state *s, int flush));
79 : #endif
80 : local void lm_init OF((deflate_state *s));
81 : local void putShortMSB OF((deflate_state *s, uInt b));
82 : local void flush_pending OF((z_streamp strm));
83 : local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
84 : #ifndef FASTEST
85 : #ifdef ASMV
86 : void match_init OF((void)); /* asm code initialization */
87 : uInt longest_match OF((deflate_state *s, IPos cur_match));
88 : #else
89 : local uInt longest_match OF((deflate_state *s, IPos cur_match));
90 : #endif
91 : #endif
92 : local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
93 :
94 : #ifdef DEBUG_LIBZ
95 : local void check_match OF((deflate_state *s, IPos start, IPos match,
96 : int length));
97 : #endif
98 :
99 : /* ===========================================================================
100 : * Local data
101 : */
102 :
103 : #define NIL 0
104 : /* Tail of hash chains */
105 :
106 : #ifndef TOO_FAR
107 : # define TOO_FAR 4096
108 : #endif
109 : /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
110 :
111 : #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
112 : /* Minimum amount of lookahead, except at the end of the input file.
113 : * See deflate.c for comments about the MIN_MATCH+1.
114 : */
115 :
116 : /* Values for max_lazy_match, good_match and max_chain_length, depending on
117 : * the desired pack level (0..9). The values given below have been tuned to
118 : * exclude worst case performance for pathological files. Better values may be
119 : * found for specific files.
120 : */
121 : typedef struct config_s {
122 : ush good_length; /* reduce lazy search above this match length */
123 : ush max_lazy; /* do not perform lazy search above this match length */
124 : ush nice_length; /* quit search above this match length */
125 : ush max_chain;
126 : compress_func func;
127 : } config;
128 :
129 : #ifdef FASTEST
130 : local const config configuration_table[2] = {
131 : /* good lazy nice chain */
132 : /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
133 : /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
134 : #else
135 : local const config configuration_table[10] = {
136 : /* good lazy nice chain */
137 : /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
138 : /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
139 : /* 2 */ {4, 5, 16, 8, deflate_fast},
140 : /* 3 */ {4, 6, 32, 32, deflate_fast},
141 :
142 : /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
143 : /* 5 */ {8, 16, 32, 32, deflate_slow},
144 : /* 6 */ {8, 16, 128, 128, deflate_slow},
145 : /* 7 */ {8, 32, 128, 256, deflate_slow},
146 : /* 8 */ {32, 128, 258, 1024, deflate_slow},
147 : /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
148 : #endif
149 :
150 : /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
151 : * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
152 : * meaning.
153 : */
154 :
155 : #define EQUAL 0
156 : /* result of memcmp for equal strings */
157 :
158 : #ifndef NO_DUMMY_DECL
159 : struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
160 : #endif
161 :
162 : /* ===========================================================================
163 : * Update a hash value with the given input byte
164 : * IN assertion: all calls to UPDATE_HASH are made with consecutive
165 : * input characters, so that a running hash key can be computed from the
166 : * previous key instead of complete recalculation each time.
167 : */
168 : #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
169 :
170 :
171 : /* ===========================================================================
172 : * Insert string str in the dictionary and set match_head to the previous head
173 : * of the hash chain (the most recent string with same hash key). Return
174 : * the previous length of the hash chain.
175 : * If this file is compiled with -DFASTEST, the compression level is forced
176 : * to 1, and no hash chains are maintained.
177 : * IN assertion: all calls to INSERT_STRING are made with consecutive
178 : * input characters and the first MIN_MATCH bytes of str are valid
179 : * (except for the last MIN_MATCH-1 bytes of the input file).
180 : */
181 : #ifdef FASTEST
182 : #define INSERT_STRING(s, str, match_head) \
183 : (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
184 : match_head = s->head[s->ins_h], \
185 : s->head[s->ins_h] = (Pos)(str))
186 : #else
187 : #define INSERT_STRING(s, str, match_head) \
188 : (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
189 : match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
190 : s->head[s->ins_h] = (Pos)(str))
191 : #endif
192 :
193 : /* ===========================================================================
194 : * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
195 : * prev[] will be initialized on the fly.
196 : */
197 : #define CLEAR_HASH(s) \
198 : s->head[s->hash_size-1] = NIL; \
199 : zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
200 :
201 : /* ========================================================================= */
202 0 : int ZEXPORT deflateInit_(strm, level, version, stream_size)
203 : z_streamp strm;
204 : int level;
205 : const char *version;
206 : int stream_size;
207 : {
208 0 : return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
209 : Z_DEFAULT_STRATEGY, version, stream_size);
210 : /* To do: ignore strm->next_in if we use it as window */
211 : }
212 :
213 : /* ========================================================================= */
214 0 : int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
215 : version, stream_size)
216 : z_streamp strm;
217 : int level;
218 : int method;
219 : int windowBits;
220 : int memLevel;
221 : int strategy;
222 : const char *version;
223 : int stream_size;
224 : {
225 : deflate_state *s;
226 : int wrap = 1;
227 : static const char my_version[] = ZLIB_VERSION;
228 :
229 : ushf *overlay;
230 : /* We overlay pending_buf and d_buf+l_buf. This works since the average
231 : * output size for (length,distance) codes is <= 24 bits.
232 : */
233 :
234 0 : if (version == Z_NULL || version[0] != my_version[0] ||
235 0 : stream_size != sizeof(z_stream)) {
236 0 : return Z_VERSION_ERROR;
237 : }
238 0 : if (strm == Z_NULL) return Z_STREAM_ERROR;
239 :
240 0 : strm->msg = Z_NULL;
241 0 : if (strm->zalloc == (alloc_func)0) {
242 0 : strm->zalloc = zcalloc;
243 0 : strm->opaque = (voidpf)0;
244 0 : }
245 0 : if (strm->zfree == (free_func)0) strm->zfree = zcfree;
246 :
247 : #ifdef FASTEST
248 : if (level != 0) level = 1;
249 : #else
250 0 : if (level == Z_DEFAULT_COMPRESSION) level = 6;
251 : #endif
252 :
253 0 : if (windowBits < 0) { /* suppress zlib wrapper */
254 : wrap = 0;
255 0 : windowBits = -windowBits;
256 0 : }
257 : #ifdef GZIP
258 0 : else if (windowBits > 15) {
259 : wrap = 2; /* write gzip wrapper instead */
260 0 : windowBits -= 16;
261 0 : }
262 : #endif
263 0 : if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
264 0 : windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
265 0 : strategy < 0 || strategy > Z_FIXED) {
266 0 : return Z_STREAM_ERROR;
267 : }
268 0 : if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
269 0 : s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
270 0 : if (s == Z_NULL) return Z_MEM_ERROR;
271 0 : strm->state = (struct internal_state FAR *)s;
272 0 : s->strm = strm;
273 :
274 0 : s->wrap = wrap;
275 0 : s->gzhead = Z_NULL;
276 0 : s->w_bits = windowBits;
277 0 : s->w_size = 1 << s->w_bits;
278 0 : s->w_mask = s->w_size - 1;
279 :
280 0 : s->hash_bits = memLevel + 7;
281 0 : s->hash_size = 1 << s->hash_bits;
282 0 : s->hash_mask = s->hash_size - 1;
283 0 : s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
284 :
285 0 : s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
286 0 : s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
287 0 : s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
288 :
289 0 : s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
290 :
291 0 : overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
292 0 : s->pending_buf = (uchf *) overlay;
293 0 : s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
294 :
295 0 : if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
296 0 : s->pending_buf == Z_NULL) {
297 0 : s->status = FINISH_STATE;
298 0 : strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
299 0 : deflateEnd (strm);
300 0 : return Z_MEM_ERROR;
301 : }
302 0 : s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
303 0 : s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
304 :
305 0 : s->level = level;
306 0 : s->strategy = strategy;
307 0 : s->method = (Byte)method;
308 :
309 0 : return deflateReset(strm);
310 0 : }
311 :
312 : /* ========================================================================= */
313 0 : int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
314 : z_streamp strm;
315 : const Bytef *dictionary;
316 : uInt dictLength;
317 : {
318 : deflate_state *s;
319 : uInt length = dictLength;
320 : uInt n;
321 : IPos hash_head = 0;
322 :
323 0 : if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
324 0 : strm->state->wrap == 2 ||
325 0 : (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
326 0 : return Z_STREAM_ERROR;
327 :
328 0 : s = strm->state;
329 0 : if (s->wrap)
330 0 : strm->adler = adler32(strm->adler, dictionary, dictLength);
331 :
332 0 : if (length < MIN_MATCH) return Z_OK;
333 0 : if (length > MAX_DIST(s)) {
334 : length = MAX_DIST(s);
335 0 : dictionary += dictLength - length; /* use the tail of the dictionary */
336 0 : }
337 0 : zmemcpy(s->window, dictionary, length);
338 0 : s->strstart = length;
339 0 : s->block_start = (long)length;
340 :
341 : /* Insert all strings in the hash table (except for the last two bytes).
342 : * s->lookahead stays null, so s->ins_h will be recomputed at the next
343 : * call of fill_window.
344 : */
345 0 : s->ins_h = s->window[0];
346 0 : UPDATE_HASH(s, s->ins_h, s->window[1]);
347 0 : for (n = 0; n <= length - MIN_MATCH; n++) {
348 0 : INSERT_STRING(s, n, hash_head);
349 : }
350 0 : if (hash_head) hash_head = 0; /* to make compiler happy */
351 0 : return Z_OK;
352 0 : }
353 :
354 : /* ========================================================================= */
355 0 : int ZEXPORT deflateReset (strm)
356 : z_streamp strm;
357 : {
358 : deflate_state *s;
359 :
360 0 : if (strm == Z_NULL || strm->state == Z_NULL ||
361 0 : strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
362 0 : return Z_STREAM_ERROR;
363 : }
364 :
365 0 : strm->total_in = strm->total_out = 0;
366 0 : strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
367 0 : strm->data_type = Z_UNKNOWN;
368 :
369 0 : s = (deflate_state *)strm->state;
370 0 : s->pending = 0;
371 0 : s->pending_out = s->pending_buf;
372 :
373 0 : if (s->wrap < 0) {
374 0 : s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
375 0 : }
376 0 : s->status = s->wrap ? INIT_STATE : BUSY_STATE;
377 0 : strm->adler =
378 : #ifdef GZIP
379 0 : s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
380 : #endif
381 0 : adler32(0L, Z_NULL, 0);
382 0 : s->last_flush = Z_NO_FLUSH;
383 :
384 0 : _tr_init(s);
385 0 : lm_init(s);
386 :
387 0 : return Z_OK;
388 0 : }
389 :
390 : /* ========================================================================= */
391 0 : int ZEXPORT deflateSetHeader (strm, head)
392 : z_streamp strm;
393 : gz_headerp head;
394 : {
395 0 : if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
396 0 : if (strm->state->wrap != 2) return Z_STREAM_ERROR;
397 0 : strm->state->gzhead = head;
398 0 : return Z_OK;
399 0 : }
400 :
401 : /* ========================================================================= */
402 0 : int ZEXPORT deflatePrime (strm, bits, value)
403 : z_streamp strm;
404 : int bits;
405 : int value;
406 : {
407 0 : if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
408 0 : strm->state->bi_valid = bits;
409 0 : strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
410 0 : return Z_OK;
411 0 : }
412 :
413 : /* ========================================================================= */
414 0 : int ZEXPORT deflateParams(strm, level, strategy)
415 : z_streamp strm;
416 : int level;
417 : int strategy;
418 : {
419 : deflate_state *s;
420 : compress_func func;
421 : int err = Z_OK;
422 :
423 0 : if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
424 : s = strm->state;
425 :
426 : #ifdef FASTEST
427 : if (level != 0) level = 1;
428 : #else
429 0 : if (level == Z_DEFAULT_COMPRESSION) level = 6;
430 : #endif
431 0 : if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
432 0 : return Z_STREAM_ERROR;
433 : }
434 0 : func = configuration_table[s->level].func;
435 :
436 0 : if (func != configuration_table[level].func && strm->total_in != 0) {
437 : /* Flush the last buffer: */
438 0 : err = deflate(strm, Z_PARTIAL_FLUSH);
439 0 : }
440 0 : if (s->level != level) {
441 0 : s->level = level;
442 0 : s->max_lazy_match = configuration_table[level].max_lazy;
443 0 : s->good_match = configuration_table[level].good_length;
444 0 : s->nice_match = configuration_table[level].nice_length;
445 0 : s->max_chain_length = configuration_table[level].max_chain;
446 0 : }
447 0 : s->strategy = strategy;
448 0 : return err;
449 0 : }
450 :
451 : /* ========================================================================= */
452 0 : int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
453 : z_streamp strm;
454 : int good_length;
455 : int max_lazy;
456 : int nice_length;
457 : int max_chain;
458 : {
459 : deflate_state *s;
460 :
461 0 : if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
462 : s = strm->state;
463 0 : s->good_match = good_length;
464 0 : s->max_lazy_match = max_lazy;
465 0 : s->nice_match = nice_length;
466 0 : s->max_chain_length = max_chain;
467 0 : return Z_OK;
468 0 : }
469 :
470 : /* =========================================================================
471 : * For the default windowBits of 15 and memLevel of 8, this function returns
472 : * a close to exact, as well as small, upper bound on the compressed size.
473 : * They are coded as constants here for a reason--if the #define's are
474 : * changed, then this function needs to be changed as well. The return
475 : * value for 15 and 8 only works for those exact settings.
476 : *
477 : * For any setting other than those defaults for windowBits and memLevel,
478 : * the value returned is a conservative worst case for the maximum expansion
479 : * resulting from using fixed blocks instead of stored blocks, which deflate
480 : * can emit on compressed data for some combinations of the parameters.
481 : *
482 : * This function could be more sophisticated to provide closer upper bounds
483 : * for every combination of windowBits and memLevel, as well as wrap.
484 : * But even the conservative upper bound of about 14% expansion does not
485 : * seem onerous for output buffer allocation.
486 : */
487 0 : uLong ZEXPORT deflateBound(strm, sourceLen)
488 : z_streamp strm;
489 : uLong sourceLen;
490 : {
491 : deflate_state *s;
492 : uLong destLen;
493 :
494 : /* conservative upper bound */
495 0 : destLen = sourceLen +
496 0 : ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
497 :
498 : /* if can't get parameters, return conservative bound */
499 0 : if (strm == Z_NULL || strm->state == Z_NULL)
500 0 : return destLen;
501 :
502 : /* if not default parameters, return conservative bound */
503 : s = strm->state;
504 0 : if (s->w_bits != 15 || s->hash_bits != 8 + 7)
505 0 : return destLen;
506 :
507 : /* default settings: return tight bound for that case */
508 0 : return compressBound(sourceLen);
509 0 : }
510 :
511 : /* =========================================================================
512 : * Put a short in the pending buffer. The 16-bit value is put in MSB order.
513 : * IN assertion: the stream state is correct and there is enough room in
514 : * pending_buf.
515 : */
516 0 : local void putShortMSB (s, b)
517 : deflate_state *s;
518 : uInt b;
519 : {
520 0 : put_byte(s, (Byte)(b >> 8));
521 0 : put_byte(s, (Byte)(b & 0xff));
522 0 : }
523 :
524 : /* =========================================================================
525 : * Flush as much pending output as possible. All deflate() output goes
526 : * through this function so some applications may wish to modify it
527 : * to avoid allocating a large strm->next_out buffer and copying into it.
528 : * (See also read_buf()).
529 : */
530 0 : local void flush_pending(strm)
531 : z_streamp strm;
532 : {
533 0 : unsigned len = strm->state->pending;
534 :
535 0 : if (len > strm->avail_out) len = strm->avail_out;
536 0 : if (len == 0) return;
537 :
538 0 : zmemcpy(strm->next_out, strm->state->pending_out, len);
539 0 : strm->next_out += len;
540 0 : strm->state->pending_out += len;
541 0 : strm->total_out += len;
542 0 : strm->avail_out -= len;
543 0 : strm->state->pending -= len;
544 0 : if (strm->state->pending == 0) {
545 0 : strm->state->pending_out = strm->state->pending_buf;
546 0 : }
547 0 : }
548 :
549 : /* ========================================================================= */
550 0 : int ZEXPORT deflate (strm, flush)
551 : z_streamp strm;
552 : int flush;
553 : {
554 : int old_flush; /* value of flush param for previous deflate call */
555 : deflate_state *s;
556 :
557 0 : if (strm == Z_NULL || strm->state == Z_NULL ||
558 0 : flush > Z_FINISH || flush < 0) {
559 0 : return Z_STREAM_ERROR;
560 : }
561 : s = strm->state;
562 :
563 0 : if (strm->next_out == Z_NULL ||
564 0 : (strm->next_in == Z_NULL && strm->avail_in != 0) ||
565 0 : (s->status == FINISH_STATE && flush != Z_FINISH)) {
566 0 : ERR_RETURN(strm, Z_STREAM_ERROR);
567 : }
568 0 : if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
569 :
570 0 : s->strm = strm; /* just in case */
571 0 : old_flush = s->last_flush;
572 0 : s->last_flush = flush;
573 :
574 : /* Write the header */
575 0 : if (s->status == INIT_STATE) {
576 : #ifdef GZIP
577 0 : if (s->wrap == 2) {
578 0 : strm->adler = crc32(0L, Z_NULL, 0);
579 0 : put_byte(s, 31);
580 0 : put_byte(s, 139);
581 0 : put_byte(s, 8);
582 0 : if (s->gzhead == NULL) {
583 0 : put_byte(s, 0);
584 0 : put_byte(s, 0);
585 0 : put_byte(s, 0);
586 0 : put_byte(s, 0);
587 0 : put_byte(s, 0);
588 0 : put_byte(s, s->level == 9 ? 2 :
589 : (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
590 : 4 : 0));
591 0 : put_byte(s, OS_CODE);
592 0 : s->status = BUSY_STATE;
593 0 : }
594 : else {
595 0 : put_byte(s, (s->gzhead->text ? 1 : 0) +
596 : (s->gzhead->hcrc ? 2 : 0) +
597 : (s->gzhead->extra == Z_NULL ? 0 : 4) +
598 : (s->gzhead->name == Z_NULL ? 0 : 8) +
599 : (s->gzhead->comment == Z_NULL ? 0 : 16)
600 : );
601 0 : put_byte(s, (Byte)(s->gzhead->time & 0xff));
602 0 : put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
603 0 : put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
604 0 : put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
605 0 : put_byte(s, s->level == 9 ? 2 :
606 : (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
607 : 4 : 0));
608 0 : put_byte(s, s->gzhead->os & 0xff);
609 0 : if (s->gzhead->extra != NULL) {
610 0 : put_byte(s, s->gzhead->extra_len & 0xff);
611 0 : put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
612 0 : }
613 0 : if (s->gzhead->hcrc)
614 0 : strm->adler = crc32(strm->adler, s->pending_buf,
615 0 : s->pending);
616 0 : s->gzindex = 0;
617 0 : s->status = EXTRA_STATE;
618 : }
619 : }
620 : else
621 : #endif
622 : {
623 0 : uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
624 : uInt level_flags;
625 :
626 0 : if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
627 0 : level_flags = 0;
628 0 : else if (s->level < 6)
629 0 : level_flags = 1;
630 0 : else if (s->level == 6)
631 0 : level_flags = 2;
632 : else
633 : level_flags = 3;
634 0 : header |= (level_flags << 6);
635 0 : if (s->strstart != 0) header |= PRESET_DICT;
636 0 : header += 31 - (header % 31);
637 :
638 0 : s->status = BUSY_STATE;
639 0 : putShortMSB(s, header);
640 :
641 : /* Save the adler32 of the preset dictionary: */
642 0 : if (s->strstart != 0) {
643 0 : putShortMSB(s, (uInt)(strm->adler >> 16));
644 0 : putShortMSB(s, (uInt)(strm->adler & 0xffff));
645 0 : }
646 0 : strm->adler = adler32(0L, Z_NULL, 0);
647 : }
648 : }
649 : #ifdef GZIP
650 0 : if (s->status == EXTRA_STATE) {
651 0 : if (s->gzhead->extra != NULL) {
652 0 : uInt beg = s->pending; /* start of bytes to update crc */
653 :
654 0 : while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
655 0 : if (s->pending == s->pending_buf_size) {
656 0 : if (s->gzhead->hcrc && s->pending > beg)
657 0 : strm->adler = crc32(strm->adler, s->pending_buf + beg,
658 0 : s->pending - beg);
659 0 : flush_pending(strm);
660 0 : beg = s->pending;
661 0 : if (s->pending == s->pending_buf_size)
662 : break;
663 : }
664 0 : put_byte(s, s->gzhead->extra[s->gzindex]);
665 0 : s->gzindex++;
666 : }
667 0 : if (s->gzhead->hcrc && s->pending > beg)
668 0 : strm->adler = crc32(strm->adler, s->pending_buf + beg,
669 0 : s->pending - beg);
670 0 : if (s->gzindex == s->gzhead->extra_len) {
671 0 : s->gzindex = 0;
672 0 : s->status = NAME_STATE;
673 0 : }
674 0 : }
675 : else
676 0 : s->status = NAME_STATE;
677 : }
678 0 : if (s->status == NAME_STATE) {
679 0 : if (s->gzhead->name != NULL) {
680 0 : uInt beg = s->pending; /* start of bytes to update crc */
681 : int val;
682 :
683 0 : do {
684 0 : if (s->pending == s->pending_buf_size) {
685 0 : if (s->gzhead->hcrc && s->pending > beg)
686 0 : strm->adler = crc32(strm->adler, s->pending_buf + beg,
687 0 : s->pending - beg);
688 0 : flush_pending(strm);
689 0 : beg = s->pending;
690 0 : if (s->pending == s->pending_buf_size) {
691 : val = 1;
692 0 : break;
693 : }
694 : }
695 0 : val = s->gzhead->name[s->gzindex++];
696 0 : put_byte(s, val);
697 0 : } while (val != 0);
698 0 : if (s->gzhead->hcrc && s->pending > beg)
699 0 : strm->adler = crc32(strm->adler, s->pending_buf + beg,
700 0 : s->pending - beg);
701 0 : if (val == 0) {
702 0 : s->gzindex = 0;
703 0 : s->status = COMMENT_STATE;
704 0 : }
705 0 : }
706 : else
707 0 : s->status = COMMENT_STATE;
708 : }
709 0 : if (s->status == COMMENT_STATE) {
710 0 : if (s->gzhead->comment != NULL) {
711 0 : uInt beg = s->pending; /* start of bytes to update crc */
712 : int val;
713 :
714 0 : do {
715 0 : if (s->pending == s->pending_buf_size) {
716 0 : if (s->gzhead->hcrc && s->pending > beg)
717 0 : strm->adler = crc32(strm->adler, s->pending_buf + beg,
718 0 : s->pending - beg);
719 0 : flush_pending(strm);
720 0 : beg = s->pending;
721 0 : if (s->pending == s->pending_buf_size) {
722 : val = 1;
723 0 : break;
724 : }
725 : }
726 0 : val = s->gzhead->comment[s->gzindex++];
727 0 : put_byte(s, val);
728 0 : } while (val != 0);
729 0 : if (s->gzhead->hcrc && s->pending > beg)
730 0 : strm->adler = crc32(strm->adler, s->pending_buf + beg,
731 0 : s->pending - beg);
732 0 : if (val == 0)
733 0 : s->status = HCRC_STATE;
734 0 : }
735 : else
736 0 : s->status = HCRC_STATE;
737 : }
738 0 : if (s->status == HCRC_STATE) {
739 0 : if (s->gzhead->hcrc) {
740 0 : if (s->pending + 2 > s->pending_buf_size)
741 0 : flush_pending(strm);
742 0 : if (s->pending + 2 <= s->pending_buf_size) {
743 0 : put_byte(s, (Byte)(strm->adler & 0xff));
744 0 : put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
745 0 : strm->adler = crc32(0L, Z_NULL, 0);
746 0 : s->status = BUSY_STATE;
747 0 : }
748 : }
749 : else
750 0 : s->status = BUSY_STATE;
751 : }
752 : #endif
753 :
754 : /* Flush as much pending output as possible */
755 0 : if (s->pending != 0) {
756 0 : flush_pending(strm);
757 0 : if (strm->avail_out == 0) {
758 : /* Since avail_out is 0, deflate will be called again with
759 : * more output space, but possibly with both pending and
760 : * avail_in equal to zero. There won't be anything to do,
761 : * but this is not an error situation so make sure we
762 : * return OK instead of BUF_ERROR at next call of deflate:
763 : */
764 0 : s->last_flush = -1;
765 0 : return Z_OK;
766 : }
767 :
768 : /* Make sure there is something to do and avoid duplicate consecutive
769 : * flushes. For repeated and useless calls with Z_FINISH, we keep
770 : * returning Z_STREAM_END instead of Z_BUF_ERROR.
771 : */
772 0 : } else if (strm->avail_in == 0 && flush <= old_flush &&
773 : flush != Z_FINISH) {
774 0 : ERR_RETURN(strm, Z_BUF_ERROR);
775 : }
776 :
777 : /* User must not provide more input after the first FINISH: */
778 0 : if (s->status == FINISH_STATE && strm->avail_in != 0) {
779 0 : ERR_RETURN(strm, Z_BUF_ERROR);
780 : }
781 :
782 : /* Start a new block or continue the current one.
783 : */
784 0 : if (strm->avail_in != 0 || s->lookahead != 0 ||
785 0 : (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
786 : block_state bstate;
787 :
788 0 : bstate = (*(configuration_table[s->level].func))(s, flush);
789 :
790 0 : if (bstate == finish_started || bstate == finish_done) {
791 0 : s->status = FINISH_STATE;
792 0 : }
793 0 : if (bstate == need_more || bstate == finish_started) {
794 0 : if (strm->avail_out == 0) {
795 0 : s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
796 0 : }
797 0 : return Z_OK;
798 : /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
799 : * of deflate should use the same flush parameter to make sure
800 : * that the flush is complete. So we don't have to output an
801 : * empty block here, this will be done at next call. This also
802 : * ensures that for a very small output buffer, we emit at most
803 : * one empty block.
804 : */
805 : }
806 0 : if (bstate == block_done) {
807 0 : if (flush == Z_PARTIAL_FLUSH) {
808 0 : _tr_align(s);
809 0 : } else { /* FULL_FLUSH or SYNC_FLUSH */
810 0 : _tr_stored_block(s, NULL, 0L, 0);
811 : /* For a full flush, this empty block will be recognized
812 : * as a special marker by inflate_sync().
813 : */
814 0 : if (flush == Z_FULL_FLUSH) {
815 0 : CLEAR_HASH(s); /* forget history */
816 0 : }
817 : }
818 0 : flush_pending(strm);
819 0 : if (strm->avail_out == 0) {
820 0 : s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
821 0 : return Z_OK;
822 : }
823 : }
824 0 : }
825 : Assert(strm->avail_out > 0, "bug2");
826 :
827 0 : if (flush != Z_FINISH) return Z_OK;
828 0 : if (s->wrap <= 0) return Z_STREAM_END;
829 :
830 : /* Write the trailer */
831 : #ifdef GZIP
832 0 : if (s->wrap == 2) {
833 0 : put_byte(s, (Byte)(strm->adler & 0xff));
834 0 : put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
835 0 : put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
836 0 : put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
837 0 : put_byte(s, (Byte)(strm->total_in & 0xff));
838 0 : put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
839 0 : put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
840 0 : put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
841 0 : }
842 : else
843 : #endif
844 : {
845 0 : putShortMSB(s, (uInt)(strm->adler >> 16));
846 0 : putShortMSB(s, (uInt)(strm->adler & 0xffff));
847 : }
848 0 : flush_pending(strm);
849 : /* If avail_out is zero, the application will call deflate again
850 : * to flush the rest.
851 : */
852 0 : if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
853 0 : return s->pending != 0 ? Z_OK : Z_STREAM_END;
854 0 : }
855 :
856 : /* ========================================================================= */
857 0 : int ZEXPORT deflateEnd (strm)
858 : z_streamp strm;
859 : {
860 : int status;
861 :
862 0 : if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
863 :
864 0 : status = strm->state->status;
865 0 : if (status != INIT_STATE &&
866 0 : status != EXTRA_STATE &&
867 0 : status != NAME_STATE &&
868 0 : status != COMMENT_STATE &&
869 0 : status != HCRC_STATE &&
870 0 : status != BUSY_STATE &&
871 0 : status != FINISH_STATE) {
872 0 : return Z_STREAM_ERROR;
873 : }
874 :
875 : /* Deallocate in reverse order of allocations: */
876 0 : TRY_FREE(strm, strm->state->pending_buf);
877 0 : TRY_FREE(strm, strm->state->head);
878 0 : TRY_FREE(strm, strm->state->prev);
879 0 : TRY_FREE(strm, strm->state->window);
880 :
881 0 : ZFREE(strm, strm->state);
882 0 : strm->state = Z_NULL;
883 :
884 0 : return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
885 0 : }
886 :
887 : /* =========================================================================
888 : * Copy the source state to the destination state.
889 : * To simplify the source, this is not supported for 16-bit MSDOS (which
890 : * doesn't have enough memory anyway to duplicate compression states).
891 : */
892 0 : int ZEXPORT deflateCopy (dest, source)
893 : z_streamp dest;
894 : z_streamp source;
895 : {
896 : #ifdef MAXSEG_64K
897 : return Z_STREAM_ERROR;
898 : #else
899 : deflate_state *ds;
900 : deflate_state *ss;
901 : ushf *overlay;
902 :
903 :
904 0 : if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
905 0 : return Z_STREAM_ERROR;
906 : }
907 :
908 : ss = source->state;
909 :
910 0 : zmemcpy(dest, source, sizeof(z_stream));
911 :
912 0 : ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
913 0 : if (ds == Z_NULL) return Z_MEM_ERROR;
914 0 : dest->state = (struct internal_state FAR *) ds;
915 0 : zmemcpy(ds, ss, sizeof(deflate_state));
916 0 : ds->strm = dest;
917 :
918 0 : ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
919 0 : ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
920 0 : ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
921 0 : overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
922 0 : ds->pending_buf = (uchf *) overlay;
923 :
924 0 : if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
925 0 : ds->pending_buf == Z_NULL) {
926 0 : deflateEnd (dest);
927 0 : return Z_MEM_ERROR;
928 : }
929 : /* following zmemcpy do not work for 16-bit MSDOS */
930 0 : zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
931 0 : zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
932 0 : zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
933 0 : zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
934 :
935 0 : ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
936 0 : ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
937 0 : ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
938 :
939 0 : ds->l_desc.dyn_tree = ds->dyn_ltree;
940 0 : ds->d_desc.dyn_tree = ds->dyn_dtree;
941 0 : ds->bl_desc.dyn_tree = ds->bl_tree;
942 :
943 0 : return Z_OK;
944 : #endif /* MAXSEG_64K */
945 0 : }
946 :
947 : /* ===========================================================================
948 : * Read a new buffer from the current input stream, update the adler32
949 : * and total number of bytes read. All deflate() input goes through
950 : * this function so some applications may wish to modify it to avoid
951 : * allocating a large strm->next_in buffer and copying from it.
952 : * (See also flush_pending()).
953 : */
954 0 : local int read_buf(strm, buf, size)
955 : z_streamp strm;
956 : Bytef *buf;
957 : unsigned size;
958 : {
959 0 : unsigned len = strm->avail_in;
960 :
961 0 : if (len > size) len = size;
962 0 : if (len == 0) return 0;
963 :
964 0 : strm->avail_in -= len;
965 :
966 0 : if (strm->state->wrap == 1) {
967 0 : strm->adler = adler32(strm->adler, strm->next_in, len);
968 0 : }
969 : #ifdef GZIP
970 0 : else if (strm->state->wrap == 2) {
971 0 : strm->adler = crc32(strm->adler, strm->next_in, len);
972 0 : }
973 : #endif
974 0 : zmemcpy(buf, strm->next_in, len);
975 0 : strm->next_in += len;
976 0 : strm->total_in += len;
977 :
978 0 : return (int)len;
979 0 : }
980 :
981 : /* ===========================================================================
982 : * Initialize the "longest match" routines for a new zlib stream
983 : */
984 0 : local void lm_init (s)
985 : deflate_state *s;
986 : {
987 0 : s->window_size = (ulg)2L*s->w_size;
988 :
989 0 : CLEAR_HASH(s);
990 :
991 : /* Set the default configuration parameters:
992 : */
993 0 : s->max_lazy_match = configuration_table[s->level].max_lazy;
994 0 : s->good_match = configuration_table[s->level].good_length;
995 0 : s->nice_match = configuration_table[s->level].nice_length;
996 0 : s->max_chain_length = configuration_table[s->level].max_chain;
997 :
998 0 : s->strstart = 0;
999 0 : s->block_start = 0L;
1000 0 : s->lookahead = 0;
1001 0 : s->match_length = s->prev_length = MIN_MATCH-1;
1002 0 : s->match_available = 0;
1003 0 : s->ins_h = 0;
1004 : #ifndef FASTEST
1005 : #ifdef ASMV
1006 : match_init(); /* initialize the asm code */
1007 : #endif
1008 : #endif
1009 0 : }
1010 :
1011 : #ifndef FASTEST
1012 : /* ===========================================================================
1013 : * Set match_start to the longest match starting at the given string and
1014 : * return its length. Matches shorter or equal to prev_length are discarded,
1015 : * in which case the result is equal to prev_length and match_start is
1016 : * garbage.
1017 : * IN assertions: cur_match is the head of the hash chain for the current
1018 : * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1019 : * OUT assertion: the match length is not greater than s->lookahead.
1020 : */
1021 : #ifndef ASMV
1022 : /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1023 : * match.S. The code will be functionally equivalent.
1024 : */
1025 0 : local uInt longest_match(s, cur_match)
1026 : deflate_state *s;
1027 : IPos cur_match; /* current match */
1028 : {
1029 0 : unsigned chain_length = s->max_chain_length;/* max hash chain length */
1030 0 : register Bytef *scan = s->window + s->strstart; /* current string */
1031 : register Bytef *match; /* matched string */
1032 : register int len; /* length of current match */
1033 0 : int best_len = s->prev_length; /* best match length so far */
1034 0 : int nice_match = s->nice_match; /* stop if match long enough */
1035 0 : IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1036 0 : s->strstart - (IPos)MAX_DIST(s) : NIL;
1037 : /* Stop when cur_match becomes <= limit. To simplify the code,
1038 : * we prevent matches with the string of window index 0.
1039 : */
1040 0 : Posf *prev = s->prev;
1041 0 : uInt wmask = s->w_mask;
1042 :
1043 : #ifdef UNALIGNED_OK
1044 : /* Compare two bytes at a time. Note: this is not always beneficial.
1045 : * Try with and without -DUNALIGNED_OK to check.
1046 : */
1047 : register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1048 : register ush scan_start = *(ushf*)scan;
1049 : register ush scan_end = *(ushf*)(scan+best_len-1);
1050 : #else
1051 0 : register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1052 0 : register Byte scan_end1 = scan[best_len-1];
1053 0 : register Byte scan_end = scan[best_len];
1054 : #endif
1055 :
1056 : /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1057 : * It is easy to get rid of this optimization if necessary.
1058 : */
1059 : Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1060 :
1061 : /* Do not waste too much time if we already have a good match: */
1062 0 : if (s->prev_length >= s->good_match) {
1063 0 : chain_length >>= 2;
1064 0 : }
1065 : /* Do not look for matches beyond the end of the input. This is necessary
1066 : * to make deflate deterministic.
1067 : */
1068 0 : if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1069 :
1070 : Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1071 :
1072 0 : do {
1073 : Assert(cur_match < s->strstart, "no future");
1074 0 : match = s->window + cur_match;
1075 :
1076 : /* Skip to next match if the match length cannot increase
1077 : * or if the match length is less than 2. Note that the checks below
1078 : * for insufficient lookahead only occur occasionally for performance
1079 : * reasons. Therefore uninitialized memory will be accessed, and
1080 : * conditional jumps will be made that depend on those values.
1081 : * However the length of the match is limited to the lookahead, so
1082 : * the output of deflate is not affected by the uninitialized values.
1083 : */
1084 : #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1085 : /* This code assumes sizeof(unsigned short) == 2. Do not use
1086 : * UNALIGNED_OK if your compiler uses a different size.
1087 : */
1088 : if (*(ushf*)(match+best_len-1) != scan_end ||
1089 : *(ushf*)match != scan_start) continue;
1090 :
1091 : /* It is not necessary to compare scan[2] and match[2] since they are
1092 : * always equal when the other bytes match, given that the hash keys
1093 : * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1094 : * strstart+3, +5, ... up to strstart+257. We check for insufficient
1095 : * lookahead only every 4th comparison; the 128th check will be made
1096 : * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1097 : * necessary to put more guard bytes at the end of the window, or
1098 : * to check more often for insufficient lookahead.
1099 : */
1100 : Assert(scan[2] == match[2], "scan[2]?");
1101 : scan++, match++;
1102 : do {
1103 : } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1104 : *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1105 : *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1106 : *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1107 : scan < strend);
1108 : /* The funny "do {}" generates better code on most compilers */
1109 :
1110 : /* Here, scan <= window+strstart+257 */
1111 : Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1112 : if (*scan == *match) scan++;
1113 :
1114 : len = (MAX_MATCH - 1) - (int)(strend-scan);
1115 : scan = strend - (MAX_MATCH-1);
1116 :
1117 : #else /* UNALIGNED_OK */
1118 :
1119 0 : if (match[best_len] != scan_end ||
1120 0 : match[best_len-1] != scan_end1 ||
1121 0 : *match != *scan ||
1122 0 : *++match != scan[1]) continue;
1123 :
1124 : /* The check at best_len-1 can be removed because it will be made
1125 : * again later. (This heuristic is not always a win.)
1126 : * It is not necessary to compare scan[2] and match[2] since they
1127 : * are always equal when the other bytes match, given that
1128 : * the hash keys are equal and that HASH_BITS >= 8.
1129 : */
1130 0 : scan += 2, match++;
1131 : Assert(*scan == *match, "match[2]?");
1132 :
1133 : /* We check for insufficient lookahead only every 8th comparison;
1134 : * the 256th check will be made at strstart+258.
1135 : */
1136 0 : do {
1137 0 : } while (*++scan == *++match && *++scan == *++match &&
1138 0 : *++scan == *++match && *++scan == *++match &&
1139 0 : *++scan == *++match && *++scan == *++match &&
1140 0 : *++scan == *++match && *++scan == *++match &&
1141 0 : scan < strend);
1142 :
1143 : Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1144 :
1145 0 : len = MAX_MATCH - (int)(strend - scan);
1146 0 : scan = strend - MAX_MATCH;
1147 :
1148 : #endif /* UNALIGNED_OK */
1149 :
1150 0 : if (len > best_len) {
1151 0 : s->match_start = cur_match;
1152 : best_len = len;
1153 0 : if (len >= nice_match) break;
1154 : #ifdef UNALIGNED_OK
1155 : scan_end = *(ushf*)(scan+best_len-1);
1156 : #else
1157 0 : scan_end1 = scan[best_len-1];
1158 0 : scan_end = scan[best_len];
1159 : #endif
1160 0 : }
1161 0 : } while ((cur_match = prev[cur_match & wmask]) > limit
1162 0 : && --chain_length != 0);
1163 :
1164 0 : if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1165 0 : return s->lookahead;
1166 0 : }
1167 : #endif /* ASMV */
1168 : #endif /* FASTEST */
1169 :
1170 : /* ---------------------------------------------------------------------------
1171 : * Optimized version for level == 1 or strategy == Z_RLE only
1172 : */
1173 0 : local uInt longest_match_fast(s, cur_match)
1174 : deflate_state *s;
1175 : IPos cur_match; /* current match */
1176 : {
1177 0 : register Bytef *scan = s->window + s->strstart; /* current string */
1178 : register Bytef *match; /* matched string */
1179 : register int len; /* length of current match */
1180 0 : register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1181 :
1182 : /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1183 : * It is easy to get rid of this optimization if necessary.
1184 : */
1185 : Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1186 :
1187 : Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1188 :
1189 : Assert(cur_match < s->strstart, "no future");
1190 :
1191 0 : match = s->window + cur_match;
1192 :
1193 : /* Return failure if the match length is less than 2:
1194 : */
1195 0 : if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1196 :
1197 : /* The check at best_len-1 can be removed because it will be made
1198 : * again later. (This heuristic is not always a win.)
1199 : * It is not necessary to compare scan[2] and match[2] since they
1200 : * are always equal when the other bytes match, given that
1201 : * the hash keys are equal and that HASH_BITS >= 8.
1202 : */
1203 0 : scan += 2, match += 2;
1204 : Assert(*scan == *match, "match[2]?");
1205 :
1206 : /* We check for insufficient lookahead only every 8th comparison;
1207 : * the 256th check will be made at strstart+258.
1208 : */
1209 0 : do {
1210 0 : } while (*++scan == *++match && *++scan == *++match &&
1211 0 : *++scan == *++match && *++scan == *++match &&
1212 0 : *++scan == *++match && *++scan == *++match &&
1213 0 : *++scan == *++match && *++scan == *++match &&
1214 0 : scan < strend);
1215 :
1216 : Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1217 :
1218 0 : len = MAX_MATCH - (int)(strend - scan);
1219 :
1220 0 : if (len < MIN_MATCH) return MIN_MATCH - 1;
1221 :
1222 0 : s->match_start = cur_match;
1223 0 : return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1224 0 : }
1225 :
1226 : #ifdef DEBUG_LIBZ
1227 : /* ===========================================================================
1228 : * Check that the match at match_start is indeed a match.
1229 : */
1230 : local void check_match(s, start, match, length)
1231 : deflate_state *s;
1232 : IPos start, match;
1233 : int length;
1234 : {
1235 : /* check that the match is indeed a match */
1236 : if (zmemcmp(s->window + match,
1237 : s->window + start, length) != EQUAL) {
1238 : fprintf(stderr, " start %u, match %u, length %d\n",
1239 : start, match, length);
1240 : do {
1241 : fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1242 : } while (--length != 0);
1243 : z_error("invalid match");
1244 : }
1245 : if (z_verbose > 1) {
1246 : fprintf(stderr,"\\[%d,%d]", start-match, length);
1247 : do { putc(s->window[start++], stderr); } while (--length != 0);
1248 : }
1249 : }
1250 : #else
1251 : # define check_match(s, start, match, length)
1252 : #endif /* DEBUG_LIBZ */
1253 :
1254 : /* ===========================================================================
1255 : * Fill the window when the lookahead becomes insufficient.
1256 : * Updates strstart and lookahead.
1257 : *
1258 : * IN assertion: lookahead < MIN_LOOKAHEAD
1259 : * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1260 : * At least one byte has been read, or avail_in == 0; reads are
1261 : * performed for at least two bytes (required for the zip translate_eol
1262 : * option -- not supported here).
1263 : */
1264 0 : local void fill_window(s)
1265 : deflate_state *s;
1266 : {
1267 : register unsigned n, m;
1268 : register Posf *p;
1269 : unsigned more; /* Amount of free space at the end of the window. */
1270 0 : uInt wsize = s->w_size;
1271 :
1272 0 : do {
1273 0 : more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1274 :
1275 : /* Deal with !@#$% 64K limit: */
1276 : if (sizeof(int) <= 2) {
1277 : if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1278 : more = wsize;
1279 :
1280 : } else if (more == (unsigned)(-1)) {
1281 : /* Very unlikely, but possible on 16 bit machine if
1282 : * strstart == 0 && lookahead == 1 (input done a byte at time)
1283 : */
1284 : more--;
1285 : }
1286 : }
1287 :
1288 : /* If the window is almost full and there is insufficient lookahead,
1289 : * move the upper half to the lower one to make room in the upper half.
1290 : */
1291 0 : if (s->strstart >= wsize+MAX_DIST(s)) {
1292 :
1293 0 : zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1294 0 : s->match_start -= wsize;
1295 0 : s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1296 0 : s->block_start -= (long) wsize;
1297 :
1298 : /* Slide the hash table (could be avoided with 32 bit values
1299 : at the expense of memory usage). We slide even when level == 0
1300 : to keep the hash table consistent if we switch back to level > 0
1301 : later. (Using level 0 permanently is not an optimal usage of
1302 : zlib, so we don't care about this pathological case.)
1303 : */
1304 : /* %%% avoid this when Z_RLE */
1305 0 : n = s->hash_size;
1306 0 : p = &s->head[n];
1307 0 : do {
1308 0 : m = *--p;
1309 0 : *p = (Pos)(m >= wsize ? m-wsize : NIL);
1310 0 : } while (--n);
1311 :
1312 : n = wsize;
1313 : #ifndef FASTEST
1314 0 : p = &s->prev[n];
1315 0 : do {
1316 0 : m = *--p;
1317 0 : *p = (Pos)(m >= wsize ? m-wsize : NIL);
1318 : /* If n is not on any hash chain, prev[n] is garbage but
1319 : * its value will never be used.
1320 : */
1321 0 : } while (--n);
1322 : #endif
1323 0 : more += wsize;
1324 0 : }
1325 0 : if (s->strm->avail_in == 0) return;
1326 :
1327 : /* If there was no sliding:
1328 : * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1329 : * more == window_size - lookahead - strstart
1330 : * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1331 : * => more >= window_size - 2*WSIZE + 2
1332 : * In the BIG_MEM or MMAP case (not yet supported),
1333 : * window_size == input_size + MIN_LOOKAHEAD &&
1334 : * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1335 : * Otherwise, window_size == 2*WSIZE so more >= 2.
1336 : * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1337 : */
1338 : Assert(more >= 2, "more < 2");
1339 :
1340 0 : n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1341 0 : s->lookahead += n;
1342 :
1343 : /* Initialize the hash value now that we have some input: */
1344 0 : if (s->lookahead >= MIN_MATCH) {
1345 0 : s->ins_h = s->window[s->strstart];
1346 0 : UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1347 : #if MIN_MATCH != 3
1348 : Call UPDATE_HASH() MIN_MATCH-3 more times
1349 : #endif
1350 0 : }
1351 : /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1352 : * but this is not important since only literal bytes will be emitted.
1353 : */
1354 :
1355 0 : } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1356 0 : }
1357 :
1358 : /* ===========================================================================
1359 : * Flush the current block, with given end-of-file flag.
1360 : * IN assertion: strstart is set to the end of the current match.
1361 : */
1362 : #define FLUSH_BLOCK_ONLY(s, eof) { \
1363 : _tr_flush_block(s, (s->block_start >= 0L ? \
1364 : (charf *)&s->window[(unsigned)s->block_start] : \
1365 : (charf *)Z_NULL), \
1366 : (ulg)((long)s->strstart - s->block_start), \
1367 : (eof)); \
1368 : s->block_start = s->strstart; \
1369 : flush_pending(s->strm); \
1370 : Tracev((stderr,"[FLUSH]")); \
1371 : }
1372 :
1373 : /* Same but force premature exit if necessary. */
1374 : #define FLUSH_BLOCK(s, eof) { \
1375 : FLUSH_BLOCK_ONLY(s, eof); \
1376 : if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1377 : }
1378 :
1379 : /* ===========================================================================
1380 : * Copy without compression as much as possible from the input stream, return
1381 : * the current block state.
1382 : * This function does not insert new strings in the dictionary since
1383 : * uncompressible data is probably not useful. This function is used
1384 : * only for the level=0 compression option.
1385 : * NOTE: this function should be optimized to avoid extra copying from
1386 : * window to pending_buf.
1387 : */
1388 0 : local block_state deflate_stored(s, flush)
1389 : deflate_state *s;
1390 : int flush;
1391 : {
1392 : /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1393 : * to pending_buf_size, and each stored block has a 5 byte header:
1394 : */
1395 : ulg max_block_size = 0xffff;
1396 : ulg max_start;
1397 :
1398 0 : if (max_block_size > s->pending_buf_size - 5) {
1399 : max_block_size = s->pending_buf_size - 5;
1400 0 : }
1401 :
1402 : /* Copy as much as possible from input to output: */
1403 0 : for (;;) {
1404 : /* Fill the window as much as possible: */
1405 0 : if (s->lookahead <= 1) {
1406 :
1407 : Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1408 : s->block_start >= (long)s->w_size, "slide too late");
1409 :
1410 0 : fill_window(s);
1411 0 : if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1412 :
1413 0 : if (s->lookahead == 0) break; /* flush the current block */
1414 : }
1415 : Assert(s->block_start >= 0L, "block gone");
1416 :
1417 0 : s->strstart += s->lookahead;
1418 0 : s->lookahead = 0;
1419 :
1420 : /* Emit a stored block if pending_buf will be full: */
1421 0 : max_start = s->block_start + max_block_size;
1422 0 : if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1423 : /* strstart == 0 is possible when wraparound on 16-bit machine */
1424 0 : s->lookahead = (uInt)(s->strstart - max_start);
1425 0 : s->strstart = (uInt)max_start;
1426 0 : FLUSH_BLOCK(s, 0);
1427 : }
1428 : /* Flush if we may have to slide, otherwise block_start may become
1429 : * negative and the data will be gone:
1430 : */
1431 0 : if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1432 0 : FLUSH_BLOCK(s, 0);
1433 : }
1434 : }
1435 0 : FLUSH_BLOCK(s, flush == Z_FINISH);
1436 0 : return flush == Z_FINISH ? finish_done : block_done;
1437 0 : }
1438 :
1439 : /* ===========================================================================
1440 : * Compress as much as possible from the input stream, return the current
1441 : * block state.
1442 : * This function does not perform lazy evaluation of matches and inserts
1443 : * new strings in the dictionary only for unmatched strings or for short
1444 : * matches. It is used only for the fast compression options.
1445 : */
1446 0 : local block_state deflate_fast(s, flush)
1447 : deflate_state *s;
1448 : int flush;
1449 : {
1450 : IPos hash_head = NIL; /* head of the hash chain */
1451 : int bflush; /* set if current block must be flushed */
1452 :
1453 0 : for (;;) {
1454 : /* Make sure that we always have enough lookahead, except
1455 : * at the end of the input file. We need MAX_MATCH bytes
1456 : * for the next match, plus MIN_MATCH bytes to insert the
1457 : * string following the next match.
1458 : */
1459 0 : if (s->lookahead < MIN_LOOKAHEAD) {
1460 0 : fill_window(s);
1461 0 : if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1462 0 : return need_more;
1463 : }
1464 0 : if (s->lookahead == 0) break; /* flush the current block */
1465 : }
1466 :
1467 : /* Insert the string window[strstart .. strstart+2] in the
1468 : * dictionary, and set hash_head to the head of the hash chain:
1469 : */
1470 0 : if (s->lookahead >= MIN_MATCH) {
1471 0 : INSERT_STRING(s, s->strstart, hash_head);
1472 0 : }
1473 :
1474 : /* Find the longest match, discarding those <= prev_length.
1475 : * At this point we have always match_length < MIN_MATCH
1476 : */
1477 0 : if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1478 : /* To simplify the code, we prevent matches with the string
1479 : * of window index 0 (in particular we have to avoid a match
1480 : * of the string with itself at the start of the input file).
1481 : */
1482 : #ifdef FASTEST
1483 : if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) ||
1484 : (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
1485 : s->match_length = longest_match_fast (s, hash_head);
1486 : }
1487 : #else
1488 0 : if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1489 0 : s->match_length = longest_match (s, hash_head);
1490 0 : } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1491 0 : s->match_length = longest_match_fast (s, hash_head);
1492 0 : }
1493 : #endif
1494 : /* longest_match() or longest_match_fast() sets match_start */
1495 : }
1496 0 : if (s->match_length >= MIN_MATCH) {
1497 : check_match(s, s->strstart, s->match_start, s->match_length);
1498 :
1499 0 : _tr_tally_dist(s, s->strstart - s->match_start,
1500 : s->match_length - MIN_MATCH, bflush);
1501 :
1502 0 : s->lookahead -= s->match_length;
1503 :
1504 : /* Insert new strings in the hash table only if the match length
1505 : * is not too large. This saves time but degrades compression.
1506 : */
1507 : #ifndef FASTEST
1508 0 : if (s->match_length <= s->max_insert_length &&
1509 0 : s->lookahead >= MIN_MATCH) {
1510 0 : s->match_length--; /* string at strstart already in table */
1511 0 : do {
1512 0 : s->strstart++;
1513 0 : INSERT_STRING(s, s->strstart, hash_head);
1514 : /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1515 : * always MIN_MATCH bytes ahead.
1516 : */
1517 0 : } while (--s->match_length != 0);
1518 0 : s->strstart++;
1519 0 : } else
1520 : #endif
1521 : {
1522 0 : s->strstart += s->match_length;
1523 0 : s->match_length = 0;
1524 0 : s->ins_h = s->window[s->strstart];
1525 0 : UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1526 : #if MIN_MATCH != 3
1527 : Call UPDATE_HASH() MIN_MATCH-3 more times
1528 : #endif
1529 : /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1530 : * matter since it will be recomputed at next deflate call.
1531 : */
1532 : }
1533 : } else {
1534 : /* No match, output a literal byte */
1535 : Tracevv((stderr,"%c", s->window[s->strstart]));
1536 0 : _tr_tally_lit (s, s->window[s->strstart], bflush);
1537 0 : s->lookahead--;
1538 0 : s->strstart++;
1539 : }
1540 0 : if (bflush) FLUSH_BLOCK(s, 0);
1541 : }
1542 0 : FLUSH_BLOCK(s, flush == Z_FINISH);
1543 0 : return flush == Z_FINISH ? finish_done : block_done;
1544 0 : }
1545 :
1546 : #ifndef FASTEST
1547 : /* ===========================================================================
1548 : * Same as above, but achieves better compression. We use a lazy
1549 : * evaluation for matches: a match is finally adopted only if there is
1550 : * no better match at the next window position.
1551 : */
1552 0 : local block_state deflate_slow(s, flush)
1553 : deflate_state *s;
1554 : int flush;
1555 : {
1556 : IPos hash_head = NIL; /* head of hash chain */
1557 : int bflush; /* set if current block must be flushed */
1558 :
1559 : /* Process the input block. */
1560 0 : for (;;) {
1561 : /* Make sure that we always have enough lookahead, except
1562 : * at the end of the input file. We need MAX_MATCH bytes
1563 : * for the next match, plus MIN_MATCH bytes to insert the
1564 : * string following the next match.
1565 : */
1566 0 : if (s->lookahead < MIN_LOOKAHEAD) {
1567 0 : fill_window(s);
1568 0 : if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1569 0 : return need_more;
1570 : }
1571 0 : if (s->lookahead == 0) break; /* flush the current block */
1572 : }
1573 :
1574 : /* Insert the string window[strstart .. strstart+2] in the
1575 : * dictionary, and set hash_head to the head of the hash chain:
1576 : */
1577 0 : if (s->lookahead >= MIN_MATCH) {
1578 0 : INSERT_STRING(s, s->strstart, hash_head);
1579 0 : }
1580 :
1581 : /* Find the longest match, discarding those <= prev_length.
1582 : */
1583 0 : s->prev_length = s->match_length, s->prev_match = s->match_start;
1584 0 : s->match_length = MIN_MATCH-1;
1585 :
1586 0 : if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1587 0 : s->strstart - hash_head <= MAX_DIST(s)) {
1588 : /* To simplify the code, we prevent matches with the string
1589 : * of window index 0 (in particular we have to avoid a match
1590 : * of the string with itself at the start of the input file).
1591 : */
1592 0 : if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1593 0 : s->match_length = longest_match (s, hash_head);
1594 0 : } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1595 0 : s->match_length = longest_match_fast (s, hash_head);
1596 0 : }
1597 : /* longest_match() or longest_match_fast() sets match_start */
1598 :
1599 0 : if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1600 : #if TOO_FAR <= 32767
1601 0 : || (s->match_length == MIN_MATCH &&
1602 0 : s->strstart - s->match_start > TOO_FAR)
1603 : #endif
1604 : )) {
1605 :
1606 : /* If prev_match is also MIN_MATCH, match_start is garbage
1607 : * but we will ignore the current match anyway.
1608 : */
1609 0 : s->match_length = MIN_MATCH-1;
1610 0 : }
1611 : }
1612 : /* If there was a match at the previous step and the current
1613 : * match is not better, output the previous match:
1614 : */
1615 0 : if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1616 0 : uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1617 : /* Do not insert strings in hash table beyond this. */
1618 :
1619 : check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1620 :
1621 0 : _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1622 : s->prev_length - MIN_MATCH, bflush);
1623 :
1624 : /* Insert in hash table all strings up to the end of the match.
1625 : * strstart-1 and strstart are already inserted. If there is not
1626 : * enough lookahead, the last two strings are not inserted in
1627 : * the hash table.
1628 : */
1629 0 : s->lookahead -= s->prev_length-1;
1630 0 : s->prev_length -= 2;
1631 0 : do {
1632 0 : if (++s->strstart <= max_insert) {
1633 0 : INSERT_STRING(s, s->strstart, hash_head);
1634 0 : }
1635 0 : } while (--s->prev_length != 0);
1636 0 : s->match_available = 0;
1637 0 : s->match_length = MIN_MATCH-1;
1638 0 : s->strstart++;
1639 :
1640 0 : if (bflush) FLUSH_BLOCK(s, 0);
1641 :
1642 0 : } else if (s->match_available) {
1643 : /* If there was no match at the previous position, output a
1644 : * single literal. If there was a match but the current match
1645 : * is longer, truncate the previous match to a single literal.
1646 : */
1647 : Tracevv((stderr,"%c", s->window[s->strstart-1]));
1648 0 : _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1649 0 : if (bflush) {
1650 0 : FLUSH_BLOCK_ONLY(s, 0);
1651 0 : }
1652 0 : s->strstart++;
1653 0 : s->lookahead--;
1654 0 : if (s->strm->avail_out == 0) return need_more;
1655 : } else {
1656 : /* There is no previous match to compare with, wait for
1657 : * the next step to decide.
1658 : */
1659 0 : s->match_available = 1;
1660 0 : s->strstart++;
1661 0 : s->lookahead--;
1662 : }
1663 : }
1664 : Assert (flush != Z_NO_FLUSH, "no flush?");
1665 0 : if (s->match_available) {
1666 : Tracevv((stderr,"%c", s->window[s->strstart-1]));
1667 0 : _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1668 0 : s->match_available = 0;
1669 0 : }
1670 0 : FLUSH_BLOCK(s, flush == Z_FINISH);
1671 0 : return flush == Z_FINISH ? finish_done : block_done;
1672 0 : }
1673 : #endif /* FASTEST */
1674 :
1675 : #if 0
1676 : /* ===========================================================================
1677 : * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1678 : * one. Do not maintain a hash table. (It will be regenerated if this run of
1679 : * deflate switches away from Z_RLE.)
1680 : */
1681 : local block_state deflate_rle(s, flush)
1682 : deflate_state *s;
1683 : int flush;
1684 : {
1685 : int bflush; /* set if current block must be flushed */
1686 : uInt run; /* length of run */
1687 : uInt max; /* maximum length of run */
1688 : uInt prev; /* byte at distance one to match */
1689 : Bytef *scan; /* scan for end of run */
1690 :
1691 : for (;;) {
1692 : /* Make sure that we always have enough lookahead, except
1693 : * at the end of the input file. We need MAX_MATCH bytes
1694 : * for the longest encodable run.
1695 : */
1696 : if (s->lookahead < MAX_MATCH) {
1697 : fill_window(s);
1698 : if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {
1699 : return need_more;
1700 : }
1701 : if (s->lookahead == 0) break; /* flush the current block */
1702 : }
1703 :
1704 : /* See how many times the previous byte repeats */
1705 : run = 0;
1706 : if (s->strstart > 0) { /* if there is a previous byte, that is */
1707 : max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH;
1708 : scan = s->window + s->strstart - 1;
1709 : prev = *scan++;
1710 : do {
1711 : if (*scan++ != prev)
1712 : break;
1713 : } while (++run < max);
1714 : }
1715 :
1716 : /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1717 : if (run >= MIN_MATCH) {
1718 : check_match(s, s->strstart, s->strstart - 1, run);
1719 : _tr_tally_dist(s, 1, run - MIN_MATCH, bflush);
1720 : s->lookahead -= run;
1721 : s->strstart += run;
1722 : } else {
1723 : /* No match, output a literal byte */
1724 : Tracevv((stderr,"%c", s->window[s->strstart]));
1725 : _tr_tally_lit (s, s->window[s->strstart], bflush);
1726 : s->lookahead--;
1727 : s->strstart++;
1728 : }
1729 : if (bflush) FLUSH_BLOCK(s, 0);
1730 : }
1731 : FLUSH_BLOCK(s, flush == Z_FINISH);
1732 : return flush == Z_FINISH ? finish_done : block_done;
1733 : }
1734 : #endif
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