|
0
|
1 /* deflate.c -- compress data using the deflation algorithm
|
|
|
2 * Copyright (C) 1995-1998 Jean-loup Gailly.
|
|
|
3 * For conditions of distribution and use, see copyright notice in zlib.h
|
|
|
4 */
|
|
|
5
|
|
|
6 /*
|
|
|
7 * ALGORITHM
|
|
|
8 *
|
|
|
9 * The "deflation" process depends on being able to identify portions
|
|
|
10 * of the input text which are identical to earlier input (within a
|
|
|
11 * sliding window trailing behind the input currently being processed).
|
|
|
12 *
|
|
|
13 * The most straightforward technique turns out to be the fastest for
|
|
|
14 * most input files: try all possible matches and select the longest.
|
|
|
15 * The key feature of this algorithm is that insertions into the string
|
|
|
16 * dictionary are very simple and thus fast, and deletions are avoided
|
|
|
17 * completely. Insertions are performed at each input character, whereas
|
|
|
18 * string matches are performed only when the previous match ends. So it
|
|
|
19 * is preferable to spend more time in matches to allow very fast string
|
|
|
20 * insertions and avoid deletions. The matching algorithm for small
|
|
|
21 * strings is inspired from that of Rabin & Karp. A brute force approach
|
|
|
22 * is used to find longer strings when a small match has been found.
|
|
|
23 * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
|
|
|
24 * (by Leonid Broukhis).
|
|
|
25 * A previous version of this file used a more sophisticated algorithm
|
|
|
26 * (by Fiala and Greene) which is guaranteed to run in linear amortized
|
|
|
27 * time, but has a larger average cost, uses more memory and is patented.
|
|
|
28 * However the F&G algorithm may be faster for some highly redundant
|
|
|
29 * files if the parameter max_chain_length (described below) is too large.
|
|
|
30 *
|
|
|
31 * ACKNOWLEDGEMENTS
|
|
|
32 *
|
|
|
33 * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
|
|
|
34 * I found it in 'freeze' written by Leonid Broukhis.
|
|
|
35 * Thanks to many people for bug reports and testing.
|
|
|
36 *
|
|
|
37 * REFERENCES
|
|
|
38 *
|
|
|
39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
|
|
|
40 * Available in ftp://ds.internic.net/rfc/rfc1951.txt
|
|
|
41 *
|
|
|
42 * A description of the Rabin and Karp algorithm is given in the book
|
|
|
43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
|
|
|
44 *
|
|
|
45 * Fiala,E.R., and Greene,D.H.
|
|
|
46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
|
|
|
47 *
|
|
|
48 */
|
|
|
49
|
|
|
50 /* @(#) $Id$ */
|
|
|
51
|
|
|
52 #include "deflate.h"
|
|
|
53
|
|
|
54 const char deflate_copyright[] =
|
|
|
55 " deflate 1.1.3 Copyright 1995-1998 Jean-loup Gailly ";
|
|
|
56 /*
|
|
|
57 If you use the zlib library in a product, an acknowledgment is welcome
|
|
|
58 in the documentation of your product. If for some reason you cannot
|
|
|
59 include such an acknowledgment, I would appreciate that you keep this
|
|
|
60 copyright string in the executable of your product.
|
|
|
61 */
|
|
|
62
|
|
|
63 /* ===========================================================================
|
|
|
64 * Function prototypes.
|
|
|
65 */
|
|
|
66 typedef enum {
|
|
|
67 need_more, /* block not completed, need more input or more output */
|
|
|
68 block_done, /* block flush performed */
|
|
|
69 finish_started, /* finish started, need only more output at next deflate */
|
|
|
70 finish_done /* finish done, accept no more input or output */
|
|
|
71 } block_state;
|
|
|
72
|
|
|
73 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
|
|
|
74 /* Compression function. Returns the block state after the call. */
|
|
|
75
|
|
|
76 local void fill_window OF((deflate_state *s));
|
|
|
77 local block_state deflate_stored OF((deflate_state *s, int flush));
|
|
|
78 local block_state deflate_fast OF((deflate_state *s, int flush));
|
|
|
79 local block_state deflate_slow OF((deflate_state *s, int flush));
|
|
|
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 #ifdef ASMV
|
|
|
85 void match_init OF((void)); /* asm code initialization */
|
|
|
86 uInt longest_match OF((deflate_state *s, IPos cur_match));
|
|
|
87 #else
|
|
|
88 local uInt longest_match OF((deflate_state *s, IPos cur_match));
|
|
|
89 #endif
|
|
|
90
|
|
|
91 #ifdef DEBUG
|
|
|
92 local void check_match OF((deflate_state *s, IPos start, IPos match,
|
|
|
93 int length));
|
|
|
94 #endif
|
|
|
95
|
|
|
96 /* ===========================================================================
|
|
|
97 * Local data
|
|
|
98 */
|
|
|
99
|
|
|
100 #define NIL 0
|
|
|
101 /* Tail of hash chains */
|
|
|
102
|
|
|
103 #ifndef TOO_FAR
|
|
|
104 # define TOO_FAR 4096
|
|
|
105 #endif
|
|
|
106 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
|
|
|
107
|
|
|
108 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
|
|
|
109 /* Minimum amount of lookahead, except at the end of the input file.
|
|
|
110 * See deflate.c for comments about the MIN_MATCH+1.
|
|
|
111 */
|
|
|
112
|
|
|
113 /* Values for max_lazy_match, good_match and max_chain_length, depending on
|
|
|
114 * the desired pack level (0..9). The values given below have been tuned to
|
|
|
115 * exclude worst case performance for pathological files. Better values may be
|
|
|
116 * found for specific files.
|
|
|
117 */
|
|
|
118 typedef struct config_s {
|
|
|
119 ush good_length; /* reduce lazy search above this match length */
|
|
|
120 ush max_lazy; /* do not perform lazy search above this match length */
|
|
|
121 ush nice_length; /* quit search above this match length */
|
|
|
122 ush max_chain;
|
|
|
123 compress_func func;
|
|
|
124 } config;
|
|
|
125
|
|
|
126 local const config configuration_table[10] = {
|
|
|
127 /* good lazy nice chain */
|
|
|
128 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
|
|
|
129 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* maximum speed, no lazy matches */
|
|
|
130 /* 2 */ {4, 5, 16, 8, deflate_fast},
|
|
|
131 /* 3 */ {4, 6, 32, 32, deflate_fast},
|
|
|
132
|
|
|
133 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
|
|
|
134 /* 5 */ {8, 16, 32, 32, deflate_slow},
|
|
|
135 /* 6 */ {8, 16, 128, 128, deflate_slow},
|
|
|
136 /* 7 */ {8, 32, 128, 256, deflate_slow},
|
|
|
137 /* 8 */ {32, 128, 258, 1024, deflate_slow},
|
|
|
138 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* maximum compression */
|
|
|
139
|
|
|
140 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
|
|
|
141 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
|
|
|
142 * meaning.
|
|
|
143 */
|
|
|
144
|
|
|
145 #define EQUAL 0
|
|
|
146 /* result of memcmp for equal strings */
|
|
|
147
|
|
|
148 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
|
|
|
149
|
|
|
150 /* ===========================================================================
|
|
|
151 * Update a hash value with the given input byte
|
|
|
152 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
|
|
|
153 * input characters, so that a running hash key can be computed from the
|
|
|
154 * previous key instead of complete recalculation each time.
|
|
|
155 */
|
|
|
156 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
|
|
|
157
|
|
|
158
|
|
|
159 /* ===========================================================================
|
|
|
160 * Insert string str in the dictionary and set match_head to the previous head
|
|
|
161 * of the hash chain (the most recent string with same hash key). Return
|
|
|
162 * the previous length of the hash chain.
|
|
|
163 * If this file is compiled with -DFASTEST, the compression level is forced
|
|
|
164 * to 1, and no hash chains are maintained.
|
|
|
165 * IN assertion: all calls to to INSERT_STRING are made with consecutive
|
|
|
166 * input characters and the first MIN_MATCH bytes of str are valid
|
|
|
167 * (except for the last MIN_MATCH-1 bytes of the input file).
|
|
|
168 */
|
|
|
169 #ifdef FASTEST
|
|
|
170 #define INSERT_STRING(s, str, match_head) \
|
|
|
171 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
|
|
|
172 match_head = s->head[s->ins_h], \
|
|
|
173 s->head[s->ins_h] = (Pos)(str))
|
|
|
174 #else
|
|
|
175 #define INSERT_STRING(s, str, match_head) \
|
|
|
176 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
|
|
|
177 s->prev[(str) & s->w_mask] = match_head = s->head[s->ins_h], \
|
|
|
178 s->head[s->ins_h] = (Pos)(str))
|
|
|
179 #endif
|
|
|
180
|
|
|
181 /* ===========================================================================
|
|
|
182 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
|
|
|
183 * prev[] will be initialized on the fly.
|
|
|
184 */
|
|
|
185 #define CLEAR_HASH(s) \
|
|
|
186 s->head[s->hash_size-1] = NIL; \
|
|
|
187 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
|
|
|
188
|
|
|
189 /* ========================================================================= */
|
|
|
190 int ZEXPORT deflateInit_(strm, level, version, stream_size)
|
|
|
191 z_streamp strm;
|
|
|
192 int level;
|
|
|
193 const char *version;
|
|
|
194 int stream_size;
|
|
|
195 {
|
|
|
196 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
|
|
|
197 Z_DEFAULT_STRATEGY, version, stream_size);
|
|
|
198 /* To do: ignore strm->next_in if we use it as window */
|
|
|
199 }
|
|
|
200
|
|
|
201 /* ========================================================================= */
|
|
|
202 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
|
|
|
203 version, stream_size)
|
|
|
204 z_streamp strm;
|
|
|
205 int level;
|
|
|
206 int method;
|
|
|
207 int windowBits;
|
|
|
208 int memLevel;
|
|
|
209 int strategy;
|
|
|
210 const char *version;
|
|
|
211 int stream_size;
|
|
|
212 {
|
|
|
213 deflate_state *s;
|
|
|
214 int noheader = 0;
|
|
|
215 static const char* my_version = ZLIB_VERSION;
|
|
|
216
|
|
|
217 ushf *overlay;
|
|
|
218 /* We overlay pending_buf and d_buf+l_buf. This works since the average
|
|
|
219 * output size for (length,distance) codes is <= 24 bits.
|
|
|
220 */
|
|
|
221
|
|
|
222 if (version == Z_NULL || version[0] != my_version[0] ||
|
|
|
223 stream_size != sizeof(z_stream)) {
|
|
|
224 return Z_VERSION_ERROR;
|
|
|
225 }
|
|
|
226 if (strm == Z_NULL) return Z_STREAM_ERROR;
|
|
|
227
|
|
|
228 strm->msg = Z_NULL;
|
|
|
229 if (strm->zalloc == Z_NULL) {
|
|
|
230 strm->zalloc = zcalloc;
|
|
|
231 strm->opaque = (voidpf)0;
|
|
|
232 }
|
|
|
233 if (strm->zfree == Z_NULL) strm->zfree = zcfree;
|
|
|
234
|
|
|
235 if (level == Z_DEFAULT_COMPRESSION) level = 6;
|
|
|
236 #ifdef FASTEST
|
|
|
237 level = 1;
|
|
|
238 #endif
|
|
|
239
|
|
|
240 if (windowBits < 0) { /* undocumented feature: suppress zlib header */
|
|
|
241 noheader = 1;
|
|
|
242 windowBits = -windowBits;
|
|
|
243 }
|
|
|
244 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
|
|
|
245 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
|
|
|
246 strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
|
|
|
247 return Z_STREAM_ERROR;
|
|
|
248 }
|
|
|
249 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
|
|
|
250 if (s == Z_NULL) return Z_MEM_ERROR;
|
|
|
251 strm->state = (struct internal_state FAR *)s;
|
|
|
252 s->strm = strm;
|
|
|
253
|
|
|
254 s->noheader = noheader;
|
|
|
255 s->w_bits = windowBits;
|
|
|
256 s->w_size = 1 << s->w_bits;
|
|
|
257 s->w_mask = s->w_size - 1;
|
|
|
258
|
|
|
259 s->hash_bits = memLevel + 7;
|
|
|
260 s->hash_size = 1 << s->hash_bits;
|
|
|
261 s->hash_mask = s->hash_size - 1;
|
|
|
262 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
|
|
|
263
|
|
|
264 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
|
|
|
265 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
|
|
|
266 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
|
|
|
267
|
|
|
268 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
|
|
|
269
|
|
|
270 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
|
|
|
271 s->pending_buf = (uchf *) overlay;
|
|
|
272 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
|
|
|
273
|
|
|
274 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
|
|
|
275 s->pending_buf == Z_NULL) {
|
|
|
276 strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
|
|
|
277 deflateEnd (strm);
|
|
|
278 return Z_MEM_ERROR;
|
|
|
279 }
|
|
|
280 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
|
|
|
281 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
|
|
|
282
|
|
|
283 s->level = level;
|
|
|
284 s->strategy = strategy;
|
|
|
285 s->method = (Byte)method;
|
|
|
286
|
|
|
287 return deflateReset(strm);
|
|
|
288 }
|
|
|
289
|
|
|
290 /* ========================================================================= */
|
|
|
291 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
|
|
|
292 z_streamp strm;
|
|
|
293 const Bytef *dictionary;
|
|
|
294 uInt dictLength;
|
|
|
295 {
|
|
|
296 deflate_state *s;
|
|
|
297 uInt length = dictLength;
|
|
|
298 uInt n;
|
|
|
299 IPos hash_head = 0;
|
|
|
300
|
|
|
301 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
|
|
|
302 strm->state->status != INIT_STATE) return Z_STREAM_ERROR;
|
|
|
303
|
|
|
304 s = strm->state;
|
|
|
305 strm->adler = adler32(strm->adler, dictionary, dictLength);
|
|
|
306
|
|
|
307 if (length < MIN_MATCH) return Z_OK;
|
|
|
308 if (length > MAX_DIST(s)) {
|
|
|
309 length = MAX_DIST(s);
|
|
|
310 #ifndef USE_DICT_HEAD
|
|
|
311 dictionary += dictLength - length; /* use the tail of the dictionary */
|
|
|
312 #endif
|
|
|
313 }
|
|
|
314 zmemcpy(s->window, dictionary, length);
|
|
|
315 s->strstart = length;
|
|
|
316 s->block_start = (long)length;
|
|
|
317
|
|
|
318 /* Insert all strings in the hash table (except for the last two bytes).
|
|
|
319 * s->lookahead stays null, so s->ins_h will be recomputed at the next
|
|
|
320 * call of fill_window.
|
|
|
321 */
|
|
|
322 s->ins_h = s->window[0];
|
|
|
323 UPDATE_HASH(s, s->ins_h, s->window[1]);
|
|
|
324 for (n = 0; n <= length - MIN_MATCH; n++) {
|
|
|
325 INSERT_STRING(s, n, hash_head);
|
|
|
326 }
|
|
|
327 if (hash_head) hash_head = 0; /* to make compiler happy */
|
|
|
328 return Z_OK;
|
|
|
329 }
|
|
|
330
|
|
|
331 /* ========================================================================= */
|
|
|
332 int ZEXPORT deflateReset (strm)
|
|
|
333 z_streamp strm;
|
|
|
334 {
|
|
|
335 deflate_state *s;
|
|
|
336
|
|
|
337 if (strm == Z_NULL || strm->state == Z_NULL ||
|
|
|
338 strm->zalloc == Z_NULL || strm->zfree == Z_NULL) return Z_STREAM_ERROR;
|
|
|
339
|
|
|
340 strm->total_in = strm->total_out = 0;
|
|
|
341 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
|
|
|
342 strm->data_type = Z_UNKNOWN;
|
|
|
343
|
|
|
344 s = (deflate_state *)strm->state;
|
|
|
345 s->pending = 0;
|
|
|
346 s->pending_out = s->pending_buf;
|
|
|
347
|
|
|
348 if (s->noheader < 0) {
|
|
|
349 s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
|
|
|
350 }
|
|
|
351 s->status = s->noheader ? BUSY_STATE : INIT_STATE;
|
|
|
352 strm->adler = 1;
|
|
|
353 s->last_flush = Z_NO_FLUSH;
|
|
|
354
|
|
|
355 _tr_init(s);
|
|
|
356 lm_init(s);
|
|
|
357
|
|
|
358 return Z_OK;
|
|
|
359 }
|
|
|
360
|
|
|
361 /* ========================================================================= */
|
|
|
362 int ZEXPORT deflateParams(strm, level, strategy)
|
|
|
363 z_streamp strm;
|
|
|
364 int level;
|
|
|
365 int strategy;
|
|
|
366 {
|
|
|
367 deflate_state *s;
|
|
|
368 compress_func func;
|
|
|
369 int err = Z_OK;
|
|
|
370
|
|
|
371 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
|
|
|
372 s = strm->state;
|
|
|
373
|
|
|
374 if (level == Z_DEFAULT_COMPRESSION) {
|
|
|
375 level = 6;
|
|
|
376 }
|
|
|
377 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
|
|
|
378 return Z_STREAM_ERROR;
|
|
|
379 }
|
|
|
380 func = configuration_table[s->level].func;
|
|
|
381
|
|
|
382 if (func != configuration_table[level].func && strm->total_in != 0) {
|
|
|
383 /* Flush the last buffer: */
|
|
|
384 err = deflate(strm, Z_PARTIAL_FLUSH);
|
|
|
385 }
|
|
|
386 if (s->level != level) {
|
|
|
387 s->level = level;
|
|
|
388 s->max_lazy_match = configuration_table[level].max_lazy;
|
|
|
389 s->good_match = configuration_table[level].good_length;
|
|
|
390 s->nice_match = configuration_table[level].nice_length;
|
|
|
391 s->max_chain_length = configuration_table[level].max_chain;
|
|
|
392 }
|
|
|
393 s->strategy = strategy;
|
|
|
394 return err;
|
|
|
395 }
|
|
|
396
|
|
|
397 /* =========================================================================
|
|
|
398 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
|
|
|
399 * IN assertion: the stream state is correct and there is enough room in
|
|
|
400 * pending_buf.
|
|
|
401 */
|
|
|
402 local void putShortMSB (s, b)
|
|
|
403 deflate_state *s;
|
|
|
404 uInt b;
|
|
|
405 {
|
|
|
406 put_byte(s, (Byte)(b >> 8));
|
|
|
407 put_byte(s, (Byte)(b & 0xff));
|
|
|
408 }
|
|
|
409
|
|
|
410 /* =========================================================================
|
|
|
411 * Flush as much pending output as possible. All deflate() output goes
|
|
|
412 * through this function so some applications may wish to modify it
|
|
|
413 * to avoid allocating a large strm->next_out buffer and copying into it.
|
|
|
414 * (See also read_buf()).
|
|
|
415 */
|
|
|
416 local void flush_pending(strm)
|
|
|
417 z_streamp strm;
|
|
|
418 {
|
|
|
419 unsigned len = strm->state->pending;
|
|
|
420
|
|
|
421 if (len > strm->avail_out) len = strm->avail_out;
|
|
|
422 if (len == 0) return;
|
|
|
423
|
|
|
424 zmemcpy(strm->next_out, strm->state->pending_out, len);
|
|
|
425 strm->next_out += len;
|
|
|
426 strm->state->pending_out += len;
|
|
|
427 strm->total_out += len;
|
|
|
428 strm->avail_out -= len;
|
|
|
429 strm->state->pending -= len;
|
|
|
430 if (strm->state->pending == 0) {
|
|
|
431 strm->state->pending_out = strm->state->pending_buf;
|
|
|
432 }
|
|
|
433 }
|
|
|
434
|
|
|
435 /* ========================================================================= */
|
|
|
436 int ZEXPORT deflate (strm, flush)
|
|
|
437 z_streamp strm;
|
|
|
438 int flush;
|
|
|
439 {
|
|
|
440 int old_flush; /* value of flush param for previous deflate call */
|
|
|
441 deflate_state *s;
|
|
|
442
|
|
|
443 if (strm == Z_NULL || strm->state == Z_NULL ||
|
|
|
444 flush > Z_FINISH || flush < 0) {
|
|
|
445 return Z_STREAM_ERROR;
|
|
|
446 }
|
|
|
447 s = strm->state;
|
|
|
448
|
|
|
449 if (strm->next_out == Z_NULL ||
|
|
|
450 (strm->next_in == Z_NULL && strm->avail_in != 0) ||
|
|
|
451 (s->status == FINISH_STATE && flush != Z_FINISH)) {
|
|
|
452 ERR_RETURN(strm, Z_STREAM_ERROR);
|
|
|
453 }
|
|
|
454 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
|
|
|
455
|
|
|
456 s->strm = strm; /* just in case */
|
|
|
457 old_flush = s->last_flush;
|
|
|
458 s->last_flush = flush;
|
|
|
459
|
|
|
460 /* Write the zlib header */
|
|
|
461 if (s->status == INIT_STATE) {
|
|
|
462
|
|
|
463 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
|
|
|
464 uInt level_flags = (s->level-1) >> 1;
|
|
|
465
|
|
|
466 if (level_flags > 3) level_flags = 3;
|
|
|
467 header |= (level_flags << 6);
|
|
|
468 if (s->strstart != 0) header |= PRESET_DICT;
|
|
|
469 header += 31 - (header % 31);
|
|
|
470
|
|
|
471 s->status = BUSY_STATE;
|
|
|
472 putShortMSB(s, header);
|
|
|
473
|
|
|
474 /* Save the adler32 of the preset dictionary: */
|
|
|
475 if (s->strstart != 0) {
|
|
|
476 putShortMSB(s, (uInt)(strm->adler >> 16));
|
|
|
477 putShortMSB(s, (uInt)(strm->adler & 0xffff));
|
|
|
478 }
|
|
|
479 strm->adler = 1L;
|
|
|
480 }
|
|
|
481
|
|
|
482 /* Flush as much pending output as possible */
|
|
|
483 if (s->pending != 0) {
|
|
|
484 flush_pending(strm);
|
|
|
485 if (strm->avail_out == 0) {
|
|
|
486 /* Since avail_out is 0, deflate will be called again with
|
|
|
487 * more output space, but possibly with both pending and
|
|
|
488 * avail_in equal to zero. There won't be anything to do,
|
|
|
489 * but this is not an error situation so make sure we
|
|
|
490 * return OK instead of BUF_ERROR at next call of deflate:
|
|
|
491 */
|
|
|
492 s->last_flush = -1;
|
|
|
493 return Z_OK;
|
|
|
494 }
|
|
|
495
|
|
|
496 /* Make sure there is something to do and avoid duplicate consecutive
|
|
|
497 * flushes. For repeated and useless calls with Z_FINISH, we keep
|
|
|
498 * returning Z_STREAM_END instead of Z_BUFF_ERROR.
|
|
|
499 */
|
|
|
500 } else if (strm->avail_in == 0 && flush <= old_flush &&
|
|
|
501 flush != Z_FINISH) {
|
|
|
502 ERR_RETURN(strm, Z_BUF_ERROR);
|
|
|
503 }
|
|
|
504
|
|
|
505 /* User must not provide more input after the first FINISH: */
|
|
|
506 if (s->status == FINISH_STATE && strm->avail_in != 0) {
|
|
|
507 ERR_RETURN(strm, Z_BUF_ERROR);
|
|
|
508 }
|
|
|
509
|
|
|
510 /* Start a new block or continue the current one.
|
|
|
511 */
|
|
|
512 if (strm->avail_in != 0 || s->lookahead != 0 ||
|
|
|
513 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
|
|
|
514 block_state bstate;
|
|
|
515
|
|
|
516 bstate = (*(configuration_table[s->level].func))(s, flush);
|
|
|
517
|
|
|
518 if (bstate == finish_started || bstate == finish_done) {
|
|
|
519 s->status = FINISH_STATE;
|
|
|
520 }
|
|
|
521 if (bstate == need_more || bstate == finish_started) {
|
|
|
522 if (strm->avail_out == 0) {
|
|
|
523 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
|
|
|
524 }
|
|
|
525 return Z_OK;
|
|
|
526 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
|
|
|
527 * of deflate should use the same flush parameter to make sure
|
|
|
528 * that the flush is complete. So we don't have to output an
|
|
|
529 * empty block here, this will be done at next call. This also
|
|
|
530 * ensures that for a very small output buffer, we emit at most
|
|
|
531 * one empty block.
|
|
|
532 */
|
|
|
533 }
|
|
|
534 if (bstate == block_done) {
|
|
|
535 if (flush == Z_PARTIAL_FLUSH) {
|
|
|
536 _tr_align(s);
|
|
|
537 } else { /* FULL_FLUSH or SYNC_FLUSH */
|
|
|
538 _tr_stored_block(s, (char*)0, 0L, 0);
|
|
|
539 /* For a full flush, this empty block will be recognized
|
|
|
540 * as a special marker by inflate_sync().
|
|
|
541 */
|
|
|
542 if (flush == Z_FULL_FLUSH) {
|
|
|
543 CLEAR_HASH(s); /* forget history */
|
|
|
544 }
|
|
|
545 }
|
|
|
546 flush_pending(strm);
|
|
|
547 if (strm->avail_out == 0) {
|
|
|
548 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
|
|
|
549 return Z_OK;
|
|
|
550 }
|
|
|
551 }
|
|
|
552 }
|
|
|
553 Assert(strm->avail_out > 0, "bug2");
|
|
|
554
|
|
|
555 if (flush != Z_FINISH) return Z_OK;
|
|
|
556 if (s->noheader) return Z_STREAM_END;
|
|
|
557
|
|
|
558 /* Write the zlib trailer (adler32) */
|
|
|
559 putShortMSB(s, (uInt)(strm->adler >> 16));
|
|
|
560 putShortMSB(s, (uInt)(strm->adler & 0xffff));
|
|
|
561 flush_pending(strm);
|
|
|
562 /* If avail_out is zero, the application will call deflate again
|
|
|
563 * to flush the rest.
|
|
|
564 */
|
|
|
565 s->noheader = -1; /* write the trailer only once! */
|
|
|
566 return s->pending != 0 ? Z_OK : Z_STREAM_END;
|
|
|
567 }
|
|
|
568
|
|
|
569 /* ========================================================================= */
|
|
|
570 int ZEXPORT deflateEnd (strm)
|
|
|
571 z_streamp strm;
|
|
|
572 {
|
|
|
573 int status;
|
|
|
574
|
|
|
575 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
|
|
|
576
|
|
|
577 status = strm->state->status;
|
|
|
578 if (status != INIT_STATE && status != BUSY_STATE &&
|
|
|
579 status != FINISH_STATE) {
|
|
|
580 return Z_STREAM_ERROR;
|
|
|
581 }
|
|
|
582
|
|
|
583 /* Deallocate in reverse order of allocations: */
|
|
|
584 TRY_FREE(strm, strm->state->pending_buf);
|
|
|
585 TRY_FREE(strm, strm->state->head);
|
|
|
586 TRY_FREE(strm, strm->state->prev);
|
|
|
587 TRY_FREE(strm, strm->state->window);
|
|
|
588
|
|
|
589 ZFREE(strm, strm->state);
|
|
|
590 strm->state = Z_NULL;
|
|
|
591
|
|
|
592 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
|
|
|
593 }
|
|
|
594
|
|
|
595 /* =========================================================================
|
|
|
596 * Copy the source state to the destination state.
|
|
|
597 * To simplify the source, this is not supported for 16-bit MSDOS (which
|
|
|
598 * doesn't have enough memory anyway to duplicate compression states).
|
|
|
599 */
|
|
|
600 int ZEXPORT deflateCopy (dest, source)
|
|
|
601 z_streamp dest;
|
|
|
602 z_streamp source;
|
|
|
603 {
|
|
|
604 #ifdef MAXSEG_64K
|
|
|
605 return Z_STREAM_ERROR;
|
|
|
606 #else
|
|
|
607 deflate_state *ds;
|
|
|
608 deflate_state *ss;
|
|
|
609 ushf *overlay;
|
|
|
610
|
|
|
611
|
|
|
612 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
|
|
|
613 return Z_STREAM_ERROR;
|
|
|
614 }
|
|
|
615
|
|
|
616 ss = source->state;
|
|
|
617
|
|
|
618 *dest = *source;
|
|
|
619
|
|
|
620 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
|
|
|
621 if (ds == Z_NULL) return Z_MEM_ERROR;
|
|
|
622 dest->state = (struct internal_state FAR *) ds;
|
|
|
623 *ds = *ss;
|
|
|
624 ds->strm = dest;
|
|
|
625
|
|
|
626 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
|
|
|
627 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
|
|
|
628 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
|
|
|
629 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
|
|
|
630 ds->pending_buf = (uchf *) overlay;
|
|
|
631
|
|
|
632 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
|
|
|
633 ds->pending_buf == Z_NULL) {
|
|
|
634 deflateEnd (dest);
|
|
|
635 return Z_MEM_ERROR;
|
|
|
636 }
|
|
|
637 /* following zmemcpy do not work for 16-bit MSDOS */
|
|
|
638 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
|
|
|
639 zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
|
|
|
640 zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
|
|
|
641 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
|
|
|
642
|
|
|
643 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
|
|
|
644 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
|
|
|
645 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
|
|
|
646
|
|
|
647 ds->l_desc.dyn_tree = ds->dyn_ltree;
|
|
|
648 ds->d_desc.dyn_tree = ds->dyn_dtree;
|
|
|
649 ds->bl_desc.dyn_tree = ds->bl_tree;
|
|
|
650
|
|
|
651 return Z_OK;
|
|
|
652 #endif
|
|
|
653 }
|
|
|
654
|
|
|
655 /* ===========================================================================
|
|
|
656 * Read a new buffer from the current input stream, update the adler32
|
|
|
657 * and total number of bytes read. All deflate() input goes through
|
|
|
658 * this function so some applications may wish to modify it to avoid
|
|
|
659 * allocating a large strm->next_in buffer and copying from it.
|
|
|
660 * (See also flush_pending()).
|
|
|
661 */
|
|
|
662 local int read_buf(strm, buf, size)
|
|
|
663 z_streamp strm;
|
|
|
664 Bytef *buf;
|
|
|
665 unsigned size;
|
|
|
666 {
|
|
|
667 unsigned len = strm->avail_in;
|
|
|
668
|
|
|
669 if (len > size) len = size;
|
|
|
670 if (len == 0) return 0;
|
|
|
671
|
|
|
672 strm->avail_in -= len;
|
|
|
673
|
|
|
674 if (!strm->state->noheader) {
|
|
|
675 strm->adler = adler32(strm->adler, strm->next_in, len);
|
|
|
676 }
|
|
|
677 zmemcpy(buf, strm->next_in, len);
|
|
|
678 strm->next_in += len;
|
|
|
679 strm->total_in += len;
|
|
|
680
|
|
|
681 return (int)len;
|
|
|
682 }
|
|
|
683
|
|
|
684 /* ===========================================================================
|
|
|
685 * Initialize the "longest match" routines for a new zlib stream
|
|
|
686 */
|
|
|
687 local void lm_init (s)
|
|
|
688 deflate_state *s;
|
|
|
689 {
|
|
|
690 s->window_size = (ulg)2L*s->w_size;
|
|
|
691
|
|
|
692 CLEAR_HASH(s);
|
|
|
693
|
|
|
694 /* Set the default configuration parameters:
|
|
|
695 */
|
|
|
696 s->max_lazy_match = configuration_table[s->level].max_lazy;
|
|
|
697 s->good_match = configuration_table[s->level].good_length;
|
|
|
698 s->nice_match = configuration_table[s->level].nice_length;
|
|
|
699 s->max_chain_length = configuration_table[s->level].max_chain;
|
|
|
700
|
|
|
701 s->strstart = 0;
|
|
|
702 s->block_start = 0L;
|
|
|
703 s->lookahead = 0;
|
|
|
704 s->match_length = s->prev_length = MIN_MATCH-1;
|
|
|
705 s->match_available = 0;
|
|
|
706 s->ins_h = 0;
|
|
|
707 #ifdef ASMV
|
|
|
708 match_init(); /* initialize the asm code */
|
|
|
709 #endif
|
|
|
710 }
|
|
|
711
|
|
|
712 /* ===========================================================================
|
|
|
713 * Set match_start to the longest match starting at the given string and
|
|
|
714 * return its length. Matches shorter or equal to prev_length are discarded,
|
|
|
715 * in which case the result is equal to prev_length and match_start is
|
|
|
716 * garbage.
|
|
|
717 * IN assertions: cur_match is the head of the hash chain for the current
|
|
|
718 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
|
|
|
719 * OUT assertion: the match length is not greater than s->lookahead.
|
|
|
720 */
|
|
|
721 #ifndef ASMV
|
|
|
722 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
|
|
|
723 * match.S. The code will be functionally equivalent.
|
|
|
724 */
|
|
|
725 #ifndef FASTEST
|
|
|
726 local uInt longest_match(s, cur_match)
|
|
|
727 deflate_state *s;
|
|
|
728 IPos cur_match; /* current match */
|
|
|
729 {
|
|
|
730 unsigned chain_length = s->max_chain_length;/* max hash chain length */
|
|
|
731 register Bytef *scan = s->window + s->strstart; /* current string */
|
|
|
732 register Bytef *match; /* matched string */
|
|
|
733 register int len; /* length of current match */
|
|
|
734 int best_len = s->prev_length; /* best match length so far */
|
|
|
735 int nice_match = s->nice_match; /* stop if match long enough */
|
|
|
736 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
|
|
|
737 s->strstart - (IPos)MAX_DIST(s) : NIL;
|
|
|
738 /* Stop when cur_match becomes <= limit. To simplify the code,
|
|
|
739 * we prevent matches with the string of window index 0.
|
|
|
740 */
|
|
|
741 Posf *prev = s->prev;
|
|
|
742 uInt wmask = s->w_mask;
|
|
|
743
|
|
|
744 #ifdef UNALIGNED_OK
|
|
|
745 /* Compare two bytes at a time. Note: this is not always beneficial.
|
|
|
746 * Try with and without -DUNALIGNED_OK to check.
|
|
|
747 */
|
|
|
748 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
|
|
|
749 register ush scan_start = *(ushf*)scan;
|
|
|
750 register ush scan_end = *(ushf*)(scan+best_len-1);
|
|
|
751 #else
|
|
|
752 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
|
|
|
753 register Byte scan_end1 = scan[best_len-1];
|
|
|
754 register Byte scan_end = scan[best_len];
|
|
|
755 #endif
|
|
|
756
|
|
|
757 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
|
|
|
758 * It is easy to get rid of this optimization if necessary.
|
|
|
759 */
|
|
|
760 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
|
|
|
761
|
|
|
762 /* Do not waste too much time if we already have a good match: */
|
|
|
763 if (s->prev_length >= s->good_match) {
|
|
|
764 chain_length >>= 2;
|
|
|
765 }
|
|
|
766 /* Do not look for matches beyond the end of the input. This is necessary
|
|
|
767 * to make deflate deterministic.
|
|
|
768 */
|
|
|
769 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
|
|
|
770
|
|
|
771 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
|
|
|
772
|
|
|
773 do {
|
|
|
774 Assert(cur_match < s->strstart, "no future");
|
|
|
775 match = s->window + cur_match;
|
|
|
776
|
|
|
777 /* Skip to next match if the match length cannot increase
|
|
|
778 * or if the match length is less than 2:
|
|
|
779 */
|
|
|
780 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
|
|
|
781 /* This code assumes sizeof(unsigned short) == 2. Do not use
|
|
|
782 * UNALIGNED_OK if your compiler uses a different size.
|
|
|
783 */
|
|
|
784 if (*(ushf*)(match+best_len-1) != scan_end ||
|
|
|
785 *(ushf*)match != scan_start) continue;
|
|
|
786
|
|
|
787 /* It is not necessary to compare scan[2] and match[2] since they are
|
|
|
788 * always equal when the other bytes match, given that the hash keys
|
|
|
789 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
|
|
|
790 * strstart+3, +5, ... up to strstart+257. We check for insufficient
|
|
|
791 * lookahead only every 4th comparison; the 128th check will be made
|
|
|
792 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
|
|
|
793 * necessary to put more guard bytes at the end of the window, or
|
|
|
794 * to check more often for insufficient lookahead.
|
|
|
795 */
|
|
|
796 Assert(scan[2] == match[2], "scan[2]?");
|
|
|
797 scan++, match++;
|
|
|
798 do {
|
|
|
799 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
|
|
|
800 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
|
|
|
801 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
|
|
|
802 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
|
|
|
803 scan < strend);
|
|
|
804 /* The funny "do {}" generates better code on most compilers */
|
|
|
805
|
|
|
806 /* Here, scan <= window+strstart+257 */
|
|
|
807 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
|
|
|
808 if (*scan == *match) scan++;
|
|
|
809
|
|
|
810 len = (MAX_MATCH - 1) - (int)(strend-scan);
|
|
|
811 scan = strend - (MAX_MATCH-1);
|
|
|
812
|
|
|
813 #else /* UNALIGNED_OK */
|
|
|
814
|
|
|
815 if (match[best_len] != scan_end ||
|
|
|
816 match[best_len-1] != scan_end1 ||
|
|
|
817 *match != *scan ||
|
|
|
818 *++match != scan[1]) continue;
|
|
|
819
|
|
|
820 /* The check at best_len-1 can be removed because it will be made
|
|
|
821 * again later. (This heuristic is not always a win.)
|
|
|
822 * It is not necessary to compare scan[2] and match[2] since they
|
|
|
823 * are always equal when the other bytes match, given that
|
|
|
824 * the hash keys are equal and that HASH_BITS >= 8.
|
|
|
825 */
|
|
|
826 scan += 2, match++;
|
|
|
827 Assert(*scan == *match, "match[2]?");
|
|
|
828
|
|
|
829 /* We check for insufficient lookahead only every 8th comparison;
|
|
|
830 * the 256th check will be made at strstart+258.
|
|
|
831 */
|
|
|
832 do {
|
|
|
833 } while (*++scan == *++match && *++scan == *++match &&
|
|
|
834 *++scan == *++match && *++scan == *++match &&
|
|
|
835 *++scan == *++match && *++scan == *++match &&
|
|
|
836 *++scan == *++match && *++scan == *++match &&
|
|
|
837 scan < strend);
|
|
|
838
|
|
|
839 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
|
|
|
840
|
|
|
841 len = MAX_MATCH - (int)(strend - scan);
|
|
|
842 scan = strend - MAX_MATCH;
|
|
|
843
|
|
|
844 #endif /* UNALIGNED_OK */
|
|
|
845
|
|
|
846 if (len > best_len) {
|
|
|
847 s->match_start = cur_match;
|
|
|
848 best_len = len;
|
|
|
849 if (len >= nice_match) break;
|
|
|
850 #ifdef UNALIGNED_OK
|
|
|
851 scan_end = *(ushf*)(scan+best_len-1);
|
|
|
852 #else
|
|
|
853 scan_end1 = scan[best_len-1];
|
|
|
854 scan_end = scan[best_len];
|
|
|
855 #endif
|
|
|
856 }
|
|
|
857 } while ((cur_match = prev[cur_match & wmask]) > limit
|
|
|
858 && --chain_length != 0);
|
|
|
859
|
|
|
860 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
|
|
|
861 return s->lookahead;
|
|
|
862 }
|
|
|
863
|
|
|
864 #else /* FASTEST */
|
|
|
865 /* ---------------------------------------------------------------------------
|
|
|
866 * Optimized version for level == 1 only
|
|
|
867 */
|
|
|
868 local uInt longest_match(s, cur_match)
|
|
|
869 deflate_state *s;
|
|
|
870 IPos cur_match; /* current match */
|
|
|
871 {
|
|
|
872 register Bytef *scan = s->window + s->strstart; /* current string */
|
|
|
873 register Bytef *match; /* matched string */
|
|
|
874 register int len; /* length of current match */
|
|
|
875 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
|
|
|
876
|
|
|
877 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
|
|
|
878 * It is easy to get rid of this optimization if necessary.
|
|
|
879 */
|
|
|
880 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
|
|
|
881
|
|
|
882 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
|
|
|
883
|
|
|
884 Assert(cur_match < s->strstart, "no future");
|
|
|
885
|
|
|
886 match = s->window + cur_match;
|
|
|
887
|
|
|
888 /* Return failure if the match length is less than 2:
|
|
|
889 */
|
|
|
890 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
|
|
|
891
|
|
|
892 /* The check at best_len-1 can be removed because it will be made
|
|
|
893 * again later. (This heuristic is not always a win.)
|
|
|
894 * It is not necessary to compare scan[2] and match[2] since they
|
|
|
895 * are always equal when the other bytes match, given that
|
|
|
896 * the hash keys are equal and that HASH_BITS >= 8.
|
|
|
897 */
|
|
|
898 scan += 2, match += 2;
|
|
|
899 Assert(*scan == *match, "match[2]?");
|
|
|
900
|
|
|
901 /* We check for insufficient lookahead only every 8th comparison;
|
|
|
902 * the 256th check will be made at strstart+258.
|
|
|
903 */
|
|
|
904 do {
|
|
|
905 } while (*++scan == *++match && *++scan == *++match &&
|
|
|
906 *++scan == *++match && *++scan == *++match &&
|
|
|
907 *++scan == *++match && *++scan == *++match &&
|
|
|
908 *++scan == *++match && *++scan == *++match &&
|
|
|
909 scan < strend);
|
|
|
910
|
|
|
911 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
|
|
|
912
|
|
|
913 len = MAX_MATCH - (int)(strend - scan);
|
|
|
914
|
|
|
915 if (len < MIN_MATCH) return MIN_MATCH - 1;
|
|
|
916
|
|
|
917 s->match_start = cur_match;
|
|
|
918 return len <= s->lookahead ? len : s->lookahead;
|
|
|
919 }
|
|
|
920 #endif /* FASTEST */
|
|
|
921 #endif /* ASMV */
|
|
|
922
|
|
|
923 #ifdef DEBUG
|
|
|
924 /* ===========================================================================
|
|
|
925 * Check that the match at match_start is indeed a match.
|
|
|
926 */
|
|
|
927 local void check_match(s, start, match, length)
|
|
|
928 deflate_state *s;
|
|
|
929 IPos start, match;
|
|
|
930 int length;
|
|
|
931 {
|
|
|
932 /* check that the match is indeed a match */
|
|
|
933 if (zmemcmp(s->window + match,
|
|
|
934 s->window + start, length) != EQUAL) {
|
|
|
935 fprintf(stderr, " start %u, match %u, length %d\n",
|
|
|
936 start, match, length);
|
|
|
937 do {
|
|
|
938 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
|
|
|
939 } while (--length != 0);
|
|
|
940 z_error("invalid match");
|
|
|
941 }
|
|
|
942 if (z_verbose > 1) {
|
|
|
943 fprintf(stderr,"\\[%d,%d]", start-match, length);
|
|
|
944 do { putc(s->window[start++], stderr); } while (--length != 0);
|
|
|
945 }
|
|
|
946 }
|
|
|
947 #else
|
|
|
948 # define check_match(s, start, match, length)
|
|
|
949 #endif
|
|
|
950
|
|
|
951 /* ===========================================================================
|
|
|
952 * Fill the window when the lookahead becomes insufficient.
|
|
|
953 * Updates strstart and lookahead.
|
|
|
954 *
|
|
|
955 * IN assertion: lookahead < MIN_LOOKAHEAD
|
|
|
956 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
|
|
|
957 * At least one byte has been read, or avail_in == 0; reads are
|
|
|
958 * performed for at least two bytes (required for the zip translate_eol
|
|
|
959 * option -- not supported here).
|
|
|
960 */
|
|
|
961 local void fill_window(s)
|
|
|
962 deflate_state *s;
|
|
|
963 {
|
|
|
964 register unsigned n, m;
|
|
|
965 register Posf *p;
|
|
|
966 unsigned more; /* Amount of free space at the end of the window. */
|
|
|
967 uInt wsize = s->w_size;
|
|
|
968
|
|
|
969 do {
|
|
|
970 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
|
|
|
971
|
|
|
972 /* Deal with !@#$% 64K limit: */
|
|
|
973 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
|
|
|
974 more = wsize;
|
|
|
975
|
|
|
976 } else if (more == (unsigned)(-1)) {
|
|
|
977 /* Very unlikely, but possible on 16 bit machine if strstart == 0
|
|
|
978 * and lookahead == 1 (input done one byte at time)
|
|
|
979 */
|
|
|
980 more--;
|
|
|
981
|
|
|
982 /* If the window is almost full and there is insufficient lookahead,
|
|
|
983 * move the upper half to the lower one to make room in the upper half.
|
|
|
984 */
|
|
|
985 } else if (s->strstart >= wsize+MAX_DIST(s)) {
|
|
|
986
|
|
|
987 zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
|
|
|
988 s->match_start -= wsize;
|
|
|
989 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
|
|
|
990 s->block_start -= (long) wsize;
|
|
|
991
|
|
|
992 /* Slide the hash table (could be avoided with 32 bit values
|
|
|
993 at the expense of memory usage). We slide even when level == 0
|
|
|
994 to keep the hash table consistent if we switch back to level > 0
|
|
|
995 later. (Using level 0 permanently is not an optimal usage of
|
|
|
996 zlib, so we don't care about this pathological case.)
|
|
|
997 */
|
|
|
998 n = s->hash_size;
|
|
|
999 p = &s->head[n];
|
|
|
1000 do {
|
|
|
1001 m = *--p;
|
|
|
1002 *p = (Pos)(m >= wsize ? m-wsize : NIL);
|
|
|
1003 } while (--n);
|
|
|
1004
|
|
|
1005 n = wsize;
|
|
|
1006 #ifndef FASTEST
|
|
|
1007 p = &s->prev[n];
|
|
|
1008 do {
|
|
|
1009 m = *--p;
|
|
|
1010 *p = (Pos)(m >= wsize ? m-wsize : NIL);
|
|
|
1011 /* If n is not on any hash chain, prev[n] is garbage but
|
|
|
1012 * its value will never be used.
|
|
|
1013 */
|
|
|
1014 } while (--n);
|
|
|
1015 #endif
|
|
|
1016 more += wsize;
|
|
|
1017 }
|
|
|
1018 if (s->strm->avail_in == 0) return;
|
|
|
1019
|
|
|
1020 /* If there was no sliding:
|
|
|
1021 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
|
|
|
1022 * more == window_size - lookahead - strstart
|
|
|
1023 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
|
|
|
1024 * => more >= window_size - 2*WSIZE + 2
|
|
|
1025 * In the BIG_MEM or MMAP case (not yet supported),
|
|
|
1026 * window_size == input_size + MIN_LOOKAHEAD &&
|
|
|
1027 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
|
|
|
1028 * Otherwise, window_size == 2*WSIZE so more >= 2.
|
|
|
1029 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
|
|
|
1030 */
|
|
|
1031 Assert(more >= 2, "more < 2");
|
|
|
1032
|
|
|
1033 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
|
|
|
1034 s->lookahead += n;
|
|
|
1035
|
|
|
1036 /* Initialize the hash value now that we have some input: */
|
|
|
1037 if (s->lookahead >= MIN_MATCH) {
|
|
|
1038 s->ins_h = s->window[s->strstart];
|
|
|
1039 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
|
|
|
1040 #if MIN_MATCH != 3
|
|
|
1041 Call UPDATE_HASH() MIN_MATCH-3 more times
|
|
|
1042 #endif
|
|
|
1043 }
|
|
|
1044 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
|
|
|
1045 * but this is not important since only literal bytes will be emitted.
|
|
|
1046 */
|
|
|
1047
|
|
|
1048 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
|
|
|
1049 }
|
|
|
1050
|
|
|
1051 /* ===========================================================================
|
|
|
1052 * Flush the current block, with given end-of-file flag.
|
|
|
1053 * IN assertion: strstart is set to the end of the current match.
|
|
|
1054 */
|
|
|
1055 #define FLUSH_BLOCK_ONLY(s, eof) { \
|
|
|
1056 _tr_flush_block(s, (s->block_start >= 0L ? \
|
|
|
1057 (charf *)&s->window[(unsigned)s->block_start] : \
|
|
|
1058 (charf *)Z_NULL), \
|
|
|
1059 (ulg)((long)s->strstart - s->block_start), \
|
|
|
1060 (eof)); \
|
|
|
1061 s->block_start = s->strstart; \
|
|
|
1062 flush_pending(s->strm); \
|
|
|
1063 Tracev((stderr,"[FLUSH]")); \
|
|
|
1064 }
|
|
|
1065
|
|
|
1066 /* Same but force premature exit if necessary. */
|
|
|
1067 #define FLUSH_BLOCK(s, eof) { \
|
|
|
1068 FLUSH_BLOCK_ONLY(s, eof); \
|
|
|
1069 if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
|
|
|
1070 }
|
|
|
1071
|
|
|
1072 /* ===========================================================================
|
|
|
1073 * Copy without compression as much as possible from the input stream, return
|
|
|
1074 * the current block state.
|
|
|
1075 * This function does not insert new strings in the dictionary since
|
|
|
1076 * uncompressible data is probably not useful. This function is used
|
|
|
1077 * only for the level=0 compression option.
|
|
|
1078 * NOTE: this function should be optimized to avoid extra copying from
|
|
|
1079 * window to pending_buf.
|
|
|
1080 */
|
|
|
1081 local block_state deflate_stored(s, flush)
|
|
|
1082 deflate_state *s;
|
|
|
1083 int flush;
|
|
|
1084 {
|
|
|
1085 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
|
|
|
1086 * to pending_buf_size, and each stored block has a 5 byte header:
|
|
|
1087 */
|
|
|
1088 ulg max_block_size = 0xffff;
|
|
|
1089 ulg max_start;
|
|
|
1090
|
|
|
1091 if (max_block_size > s->pending_buf_size - 5) {
|
|
|
1092 max_block_size = s->pending_buf_size - 5;
|
|
|
1093 }
|
|
|
1094
|
|
|
1095 /* Copy as much as possible from input to output: */
|
|
|
1096 for (;;) {
|
|
|
1097 /* Fill the window as much as possible: */
|
|
|
1098 if (s->lookahead <= 1) {
|
|
|
1099
|
|
|
1100 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
|
|
|
1101 s->block_start >= (long)s->w_size, "slide too late");
|
|
|
1102
|
|
|
1103 fill_window(s);
|
|
|
1104 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
|
|
|
1105
|
|
|
1106 if (s->lookahead == 0) break; /* flush the current block */
|
|
|
1107 }
|
|
|
1108 Assert(s->block_start >= 0L, "block gone");
|
|
|
1109
|
|
|
1110 s->strstart += s->lookahead;
|
|
|
1111 s->lookahead = 0;
|
|
|
1112
|
|
|
1113 /* Emit a stored block if pending_buf will be full: */
|
|
|
1114 max_start = s->block_start + max_block_size;
|
|
|
1115 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
|
|
|
1116 /* strstart == 0 is possible when wraparound on 16-bit machine */
|
|
|
1117 s->lookahead = (uInt)(s->strstart - max_start);
|
|
|
1118 s->strstart = (uInt)max_start;
|
|
|
1119 FLUSH_BLOCK(s, 0);
|
|
|
1120 }
|
|
|
1121 /* Flush if we may have to slide, otherwise block_start may become
|
|
|
1122 * negative and the data will be gone:
|
|
|
1123 */
|
|
|
1124 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
|
|
|
1125 FLUSH_BLOCK(s, 0);
|
|
|
1126 }
|
|
|
1127 }
|
|
|
1128 FLUSH_BLOCK(s, flush == Z_FINISH);
|
|
|
1129 return flush == Z_FINISH ? finish_done : block_done;
|
|
|
1130 }
|
|
|
1131
|
|
|
1132 /* ===========================================================================
|
|
|
1133 * Compress as much as possible from the input stream, return the current
|
|
|
1134 * block state.
|
|
|
1135 * This function does not perform lazy evaluation of matches and inserts
|
|
|
1136 * new strings in the dictionary only for unmatched strings or for short
|
|
|
1137 * matches. It is used only for the fast compression options.
|
|
|
1138 */
|
|
|
1139 local block_state deflate_fast(s, flush)
|
|
|
1140 deflate_state *s;
|
|
|
1141 int flush;
|
|
|
1142 {
|
|
|
1143 IPos hash_head = NIL; /* head of the hash chain */
|
|
|
1144 int bflush; /* set if current block must be flushed */
|
|
|
1145
|
|
|
1146 for (;;) {
|
|
|
1147 /* Make sure that we always have enough lookahead, except
|
|
|
1148 * at the end of the input file. We need MAX_MATCH bytes
|
|
|
1149 * for the next match, plus MIN_MATCH bytes to insert the
|
|
|
1150 * string following the next match.
|
|
|
1151 */
|
|
|
1152 if (s->lookahead < MIN_LOOKAHEAD) {
|
|
|
1153 fill_window(s);
|
|
|
1154 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
|
|
|
1155 return need_more;
|
|
|
1156 }
|
|
|
1157 if (s->lookahead == 0) break; /* flush the current block */
|
|
|
1158 }
|
|
|
1159
|
|
|
1160 /* Insert the string window[strstart .. strstart+2] in the
|
|
|
1161 * dictionary, and set hash_head to the head of the hash chain:
|
|
|
1162 */
|
|
|
1163 if (s->lookahead >= MIN_MATCH) {
|
|
|
1164 INSERT_STRING(s, s->strstart, hash_head);
|
|
|
1165 }
|
|
|
1166
|
|
|
1167 /* Find the longest match, discarding those <= prev_length.
|
|
|
1168 * At this point we have always match_length < MIN_MATCH
|
|
|
1169 */
|
|
|
1170 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
|
|
|
1171 /* To simplify the code, we prevent matches with the string
|
|
|
1172 * of window index 0 (in particular we have to avoid a match
|
|
|
1173 * of the string with itself at the start of the input file).
|
|
|
1174 */
|
|
|
1175 if (s->strategy != Z_HUFFMAN_ONLY) {
|
|
|
1176 s->match_length = longest_match (s, hash_head);
|
|
|
1177 }
|
|
|
1178 /* longest_match() sets match_start */
|
|
|
1179 }
|
|
|
1180 if (s->match_length >= MIN_MATCH) {
|
|
|
1181 check_match(s, s->strstart, s->match_start, s->match_length);
|
|
|
1182
|
|
|
1183 _tr_tally_dist(s, s->strstart - s->match_start,
|
|
|
1184 s->match_length - MIN_MATCH, bflush);
|
|
|
1185
|
|
|
1186 s->lookahead -= s->match_length;
|
|
|
1187
|
|
|
1188 /* Insert new strings in the hash table only if the match length
|
|
|
1189 * is not too large. This saves time but degrades compression.
|
|
|
1190 */
|
|
|
1191 #ifndef FASTEST
|
|
|
1192 if (s->match_length <= s->max_insert_length &&
|
|
|
1193 s->lookahead >= MIN_MATCH) {
|
|
|
1194 s->match_length--; /* string at strstart already in hash table */
|
|
|
1195 do {
|
|
|
1196 s->strstart++;
|
|
|
1197 INSERT_STRING(s, s->strstart, hash_head);
|
|
|
1198 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
|
|
|
1199 * always MIN_MATCH bytes ahead.
|
|
|
1200 */
|
|
|
1201 } while (--s->match_length != 0);
|
|
|
1202 s->strstart++;
|
|
|
1203 } else
|
|
|
1204 #endif
|
|
|
1205 {
|
|
|
1206 s->strstart += s->match_length;
|
|
|
1207 s->match_length = 0;
|
|
|
1208 s->ins_h = s->window[s->strstart];
|
|
|
1209 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
|
|
|
1210 #if MIN_MATCH != 3
|
|
|
1211 Call UPDATE_HASH() MIN_MATCH-3 more times
|
|
|
1212 #endif
|
|
|
1213 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
|
|
|
1214 * matter since it will be recomputed at next deflate call.
|
|
|
1215 */
|
|
|
1216 }
|
|
|
1217 } else {
|
|
|
1218 /* No match, output a literal byte */
|
|
|
1219 Tracevv((stderr,"%c", s->window[s->strstart]));
|
|
|
1220 _tr_tally_lit (s, s->window[s->strstart], bflush);
|
|
|
1221 s->lookahead--;
|
|
|
1222 s->strstart++;
|
|
|
1223 }
|
|
|
1224 if (bflush) FLUSH_BLOCK(s, 0);
|
|
|
1225 }
|
|
|
1226 FLUSH_BLOCK(s, flush == Z_FINISH);
|
|
|
1227 return flush == Z_FINISH ? finish_done : block_done;
|
|
|
1228 }
|
|
|
1229
|
|
|
1230 /* ===========================================================================
|
|
|
1231 * Same as above, but achieves better compression. We use a lazy
|
|
|
1232 * evaluation for matches: a match is finally adopted only if there is
|
|
|
1233 * no better match at the next window position.
|
|
|
1234 */
|
|
|
1235 local block_state deflate_slow(s, flush)
|
|
|
1236 deflate_state *s;
|
|
|
1237 int flush;
|
|
|
1238 {
|
|
|
1239 IPos hash_head = NIL; /* head of hash chain */
|
|
|
1240 int bflush; /* set if current block must be flushed */
|
|
|
1241
|
|
|
1242 /* Process the input block. */
|
|
|
1243 for (;;) {
|
|
|
1244 /* Make sure that we always have enough lookahead, except
|
|
|
1245 * at the end of the input file. We need MAX_MATCH bytes
|
|
|
1246 * for the next match, plus MIN_MATCH bytes to insert the
|
|
|
1247 * string following the next match.
|
|
|
1248 */
|
|
|
1249 if (s->lookahead < MIN_LOOKAHEAD) {
|
|
|
1250 fill_window(s);
|
|
|
1251 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
|
|
|
1252 return need_more;
|
|
|
1253 }
|
|
|
1254 if (s->lookahead == 0) break; /* flush the current block */
|
|
|
1255 }
|
|
|
1256
|
|
|
1257 /* Insert the string window[strstart .. strstart+2] in the
|
|
|
1258 * dictionary, and set hash_head to the head of the hash chain:
|
|
|
1259 */
|
|
|
1260 if (s->lookahead >= MIN_MATCH) {
|
|
|
1261 INSERT_STRING(s, s->strstart, hash_head);
|
|
|
1262 }
|
|
|
1263
|
|
|
1264 /* Find the longest match, discarding those <= prev_length.
|
|
|
1265 */
|
|
|
1266 s->prev_length = s->match_length, s->prev_match = s->match_start;
|
|
|
1267 s->match_length = MIN_MATCH-1;
|
|
|
1268
|
|
|
1269 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
|
|
|
1270 s->strstart - hash_head <= MAX_DIST(s)) {
|
|
|
1271 /* To simplify the code, we prevent matches with the string
|
|
|
1272 * of window index 0 (in particular we have to avoid a match
|
|
|
1273 * of the string with itself at the start of the input file).
|
|
|
1274 */
|
|
|
1275 if (s->strategy != Z_HUFFMAN_ONLY) {
|
|
|
1276 s->match_length = longest_match (s, hash_head);
|
|
|
1277 }
|
|
|
1278 /* longest_match() sets match_start */
|
|
|
1279
|
|
|
1280 if (s->match_length <= 5 && (s->strategy == Z_FILTERED ||
|
|
|
1281 (s->match_length == MIN_MATCH &&
|
|
|
1282 s->strstart - s->match_start > TOO_FAR))) {
|
|
|
1283
|
|
|
1284 /* If prev_match is also MIN_MATCH, match_start is garbage
|
|
|
1285 * but we will ignore the current match anyway.
|
|
|
1286 */
|
|
|
1287 s->match_length = MIN_MATCH-1;
|
|
|
1288 }
|
|
|
1289 }
|
|
|
1290 /* If there was a match at the previous step and the current
|
|
|
1291 * match is not better, output the previous match:
|
|
|
1292 */
|
|
|
1293 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
|
|
|
1294 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
|
|
|
1295 /* Do not insert strings in hash table beyond this. */
|
|
|
1296
|
|
|
1297 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
|
|
|
1298
|
|
|
1299 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
|
|
|
1300 s->prev_length - MIN_MATCH, bflush);
|
|
|
1301
|
|
|
1302 /* Insert in hash table all strings up to the end of the match.
|
|
|
1303 * strstart-1 and strstart are already inserted. If there is not
|
|
|
1304 * enough lookahead, the last two strings are not inserted in
|
|
|
1305 * the hash table.
|
|
|
1306 */
|
|
|
1307 s->lookahead -= s->prev_length-1;
|
|
|
1308 s->prev_length -= 2;
|
|
|
1309 do {
|
|
|
1310 if (++s->strstart <= max_insert) {
|
|
|
1311 INSERT_STRING(s, s->strstart, hash_head);
|
|
|
1312 }
|
|
|
1313 } while (--s->prev_length != 0);
|
|
|
1314 s->match_available = 0;
|
|
|
1315 s->match_length = MIN_MATCH-1;
|
|
|
1316 s->strstart++;
|
|
|
1317
|
|
|
1318 if (bflush) FLUSH_BLOCK(s, 0);
|
|
|
1319
|
|
|
1320 } else if (s->match_available) {
|
|
|
1321 /* If there was no match at the previous position, output a
|
|
|
1322 * single literal. If there was a match but the current match
|
|
|
1323 * is longer, truncate the previous match to a single literal.
|
|
|
1324 */
|
|
|
1325 Tracevv((stderr,"%c", s->window[s->strstart-1]));
|
|
|
1326 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
|
|
|
1327 if (bflush) {
|
|
|
1328 FLUSH_BLOCK_ONLY(s, 0);
|
|
|
1329 }
|
|
|
1330 s->strstart++;
|
|
|
1331 s->lookahead--;
|
|
|
1332 if (s->strm->avail_out == 0) return need_more;
|
|
|
1333 } else {
|
|
|
1334 /* There is no previous match to compare with, wait for
|
|
|
1335 * the next step to decide.
|
|
|
1336 */
|
|
|
1337 s->match_available = 1;
|
|
|
1338 s->strstart++;
|
|
|
1339 s->lookahead--;
|
|
|
1340 }
|
|
|
1341 }
|
|
|
1342 Assert (flush != Z_NO_FLUSH, "no flush?");
|
|
|
1343 if (s->match_available) {
|
|
|
1344 Tracevv((stderr,"%c", s->window[s->strstart-1]));
|
|
|
1345 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
|
|
|
1346 s->match_available = 0;
|
|
|
1347 }
|
|
|
1348 FLUSH_BLOCK(s, flush == Z_FINISH);
|
|
|
1349 return flush == Z_FINISH ? finish_done : block_done;
|
|
|
1350 }
|
