/[pcsx2_0.9.7]/trunk/3rdparty/zlib/deflate.c
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Revision 31 - (hide annotations) (download)
Tue Sep 7 03:24:11 2010 UTC (10 years, 2 months ago) by william
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committing r3113 initial commit again...
1 william 31 /* deflate.c -- compress data using the deflation algorithm
2     * Copyright (C) 1995-2010 Jean-loup Gailly and Mark Adler
3     * For conditions of distribution and use, see copyright notice in zlib.h
4     */
5    
6     /*
7     * ALGORITHM
8     *
9     * The "deflation" process depends on being able to identify portions
10     * of the input text which are identical to earlier input (within a
11     * sliding window trailing behind the input currently being processed).
12     *
13     * The most straightforward technique turns out to be the fastest for
14     * most input files: try all possible matches and select the longest.
15     * The key feature of this algorithm is that insertions into the string
16     * dictionary are very simple and thus fast, and deletions are avoided
17     * completely. Insertions are performed at each input character, whereas
18     * string matches are performed only when the previous match ends. So it
19     * is preferable to spend more time in matches to allow very fast string
20     * insertions and avoid deletions. The matching algorithm for small
21     * strings is inspired from that of Rabin & Karp. A brute force approach
22     * is used to find longer strings when a small match has been found.
23     * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
24     * (by Leonid Broukhis).
25     * A previous version of this file used a more sophisticated algorithm
26     * (by Fiala and Greene) which is guaranteed to run in linear amortized
27     * time, but has a larger average cost, uses more memory and is patented.
28     * However the F&G algorithm may be faster for some highly redundant
29     * files if the parameter max_chain_length (described below) is too large.
30     *
31     * ACKNOWLEDGEMENTS
32     *
33     * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
34     * I found it in 'freeze' written by Leonid Broukhis.
35     * Thanks to many people for bug reports and testing.
36     *
37     * REFERENCES
38     *
39     * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40     * Available in http://www.ietf.org/rfc/rfc1951.txt
41     *
42     * A description of the Rabin and Karp algorithm is given in the book
43     * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
44     *
45     * Fiala,E.R., and Greene,D.H.
46     * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
47     *
48     */
49    
50     /* @(#) $Id$ */
51    
52     #include "deflate.h"
53    
54     const char deflate_copyright[] =
55     " deflate 1.2.4 Copyright 1995-2010 Jean-loup Gailly and Mark Adler ";
56     /*
57     If you use the zlib library in a product, an acknowledgment is welcome
58     in the documentation of your product. If for some reason you cannot
59     include such an acknowledgment, I would appreciate that you keep this
60     copyright string in the executable of your product.
61     */
62    
63     /* ===========================================================================
64     * Function prototypes.
65     */
66     typedef enum {
67     need_more, /* block not completed, need more input or more output */
68     block_done, /* block flush performed */
69     finish_started, /* finish started, need only more output at next deflate */
70     finish_done /* finish done, accept no more input or output */
71     } block_state;
72    
73     typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74     /* Compression function. Returns the block state after the call. */
75    
76     local void fill_window OF((deflate_state *s));
77     local block_state deflate_stored OF((deflate_state *s, int flush));
78     local block_state deflate_fast OF((deflate_state *s, int flush));
79     #ifndef FASTEST
80     local block_state deflate_slow OF((deflate_state *s, int flush));
81     #endif
82     local block_state deflate_rle OF((deflate_state *s, int flush));
83     local block_state deflate_huff OF((deflate_state *s, int flush));
84     local void lm_init OF((deflate_state *s));
85     local void putShortMSB OF((deflate_state *s, uInt b));
86     local void flush_pending OF((z_streamp strm));
87     local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
88     #ifdef ASMV
89     void match_init OF((void)); /* asm code initialization */
90     uInt longest_match OF((deflate_state *s, IPos cur_match));
91     #else
92     local uInt longest_match OF((deflate_state *s, IPos cur_match));
93     #endif
94    
95     #ifdef DEBUG
96     local void check_match OF((deflate_state *s, IPos start, IPos match,
97     int length));
98     #endif
99    
100     /* ===========================================================================
101     * Local data
102     */
103    
104     #define NIL 0
105     /* Tail of hash chains */
106    
107     #ifndef TOO_FAR
108     # define TOO_FAR 4096
109     #endif
110     /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
111    
112     /* Values for max_lazy_match, good_match and max_chain_length, depending on
113     * the desired pack level (0..9). The values given below have been tuned to
114     * exclude worst case performance for pathological files. Better values may be
115     * found for specific files.
116     */
117     typedef struct config_s {
118     ush good_length; /* reduce lazy search above this match length */
119     ush max_lazy; /* do not perform lazy search above this match length */
120     ush nice_length; /* quit search above this match length */
121     ush max_chain;
122     compress_func func;
123     } config;
124    
125     #ifdef FASTEST
126     local const config configuration_table[2] = {
127     /* good lazy nice chain */
128     /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
129     /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
130     #else
131     local const config configuration_table[10] = {
132     /* good lazy nice chain */
133     /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
134     /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
135     /* 2 */ {4, 5, 16, 8, deflate_fast},
136     /* 3 */ {4, 6, 32, 32, deflate_fast},
137    
138     /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
139     /* 5 */ {8, 16, 32, 32, deflate_slow},
140     /* 6 */ {8, 16, 128, 128, deflate_slow},
141     /* 7 */ {8, 32, 128, 256, deflate_slow},
142     /* 8 */ {32, 128, 258, 1024, deflate_slow},
143     /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
144     #endif
145    
146     /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
147     * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
148     * meaning.
149     */
150    
151     #define EQUAL 0
152     /* result of memcmp for equal strings */
153    
154     #ifndef NO_DUMMY_DECL
155     struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
156     #endif
157    
158     /* ===========================================================================
159     * Update a hash value with the given input byte
160     * IN assertion: all calls to to UPDATE_HASH are made with consecutive
161     * input characters, so that a running hash key can be computed from the
162     * previous key instead of complete recalculation each time.
163     */
164     #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
165    
166    
167     /* ===========================================================================
168     * Insert string str in the dictionary and set match_head to the previous head
169     * of the hash chain (the most recent string with same hash key). Return
170     * the previous length of the hash chain.
171     * If this file is compiled with -DFASTEST, the compression level is forced
172     * to 1, and no hash chains are maintained.
173     * IN assertion: all calls to to INSERT_STRING are made with consecutive
174     * input characters and the first MIN_MATCH bytes of str are valid
175     * (except for the last MIN_MATCH-1 bytes of the input file).
176     */
177     #ifdef FASTEST
178     #define INSERT_STRING(s, str, match_head) \
179     (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
180     match_head = s->head[s->ins_h], \
181     s->head[s->ins_h] = (Pos)(str))
182     #else
183     #define INSERT_STRING(s, str, match_head) \
184     (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
185     match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
186     s->head[s->ins_h] = (Pos)(str))
187     #endif
188    
189     /* ===========================================================================
190     * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
191     * prev[] will be initialized on the fly.
192     */
193     #define CLEAR_HASH(s) \
194     s->head[s->hash_size-1] = NIL; \
195     zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
196    
197     /* ========================================================================= */
198     int ZEXPORT deflateInit_(strm, level, version, stream_size)
199     z_streamp strm;
200     int level;
201     const char *version;
202     int stream_size;
203     {
204     return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
205     Z_DEFAULT_STRATEGY, version, stream_size);
206     /* To do: ignore strm->next_in if we use it as window */
207     }
208    
209     /* ========================================================================= */
210     int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
211     version, stream_size)
212     z_streamp strm;
213     int level;
214     int method;
215     int windowBits;
216     int memLevel;
217     int strategy;
218     const char *version;
219     int stream_size;
220     {
221     deflate_state *s;
222     int wrap = 1;
223     static const char my_version[] = ZLIB_VERSION;
224    
225     ushf *overlay;
226     /* We overlay pending_buf and d_buf+l_buf. This works since the average
227     * output size for (length,distance) codes is <= 24 bits.
228     */
229    
230     if (version == Z_NULL || version[0] != my_version[0] ||
231     stream_size != sizeof(z_stream)) {
232     return Z_VERSION_ERROR;
233     }
234     if (strm == Z_NULL) return Z_STREAM_ERROR;
235    
236     strm->msg = Z_NULL;
237     if (strm->zalloc == (alloc_func)0) {
238     strm->zalloc = zcalloc;
239     strm->opaque = (voidpf)0;
240     }
241     if (strm->zfree == (free_func)0) strm->zfree = zcfree;
242    
243     #ifdef FASTEST
244     if (level != 0) level = 1;
245     #else
246     if (level == Z_DEFAULT_COMPRESSION) level = 6;
247     #endif
248    
249     if (windowBits < 0) { /* suppress zlib wrapper */
250     wrap = 0;
251     windowBits = -windowBits;
252     }
253     #ifdef GZIP
254     else if (windowBits > 15) {
255     wrap = 2; /* write gzip wrapper instead */
256     windowBits -= 16;
257     }
258     #endif
259     if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
260     windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
261     strategy < 0 || strategy > Z_FIXED) {
262     return Z_STREAM_ERROR;
263     }
264     if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
265     s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
266     if (s == Z_NULL) return Z_MEM_ERROR;
267     strm->state = (struct internal_state FAR *)s;
268     s->strm = strm;
269    
270     s->wrap = wrap;
271     s->gzhead = Z_NULL;
272     s->w_bits = windowBits;
273     s->w_size = 1 << s->w_bits;
274     s->w_mask = s->w_size - 1;
275    
276     s->hash_bits = memLevel + 7;
277     s->hash_size = 1 << s->hash_bits;
278     s->hash_mask = s->hash_size - 1;
279     s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
280    
281     s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
282     s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
283     s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
284    
285     s->high_water = 0; /* nothing written to s->window yet */
286    
287     s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
288    
289     overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
290     s->pending_buf = (uchf *) overlay;
291     s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
292    
293     if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
294     s->pending_buf == Z_NULL) {
295     s->status = FINISH_STATE;
296     strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
297     deflateEnd (strm);
298     return Z_MEM_ERROR;
299     }
300     s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
301     s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
302    
303     s->level = level;
304     s->strategy = strategy;
305     s->method = (Byte)method;
306    
307     return deflateReset(strm);
308     }
309    
310     /* ========================================================================= */
311     int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
312     z_streamp strm;
313     const Bytef *dictionary;
314     uInt dictLength;
315     {
316     deflate_state *s;
317     uInt length = dictLength;
318     uInt n;
319     IPos hash_head = 0;
320    
321     if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
322     strm->state->wrap == 2 ||
323     (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
324     return Z_STREAM_ERROR;
325    
326     s = strm->state;
327     if (s->wrap)
328     strm->adler = adler32(strm->adler, dictionary, dictLength);
329    
330     if (length < MIN_MATCH) return Z_OK;
331     if (length > s->w_size) {
332     length = s->w_size;
333     dictionary += dictLength - length; /* use the tail of the dictionary */
334     }
335     zmemcpy(s->window, dictionary, length);
336     s->strstart = length;
337     s->block_start = (long)length;
338    
339     /* Insert all strings in the hash table (except for the last two bytes).
340     * s->lookahead stays null, so s->ins_h will be recomputed at the next
341     * call of fill_window.
342     */
343     s->ins_h = s->window[0];
344     UPDATE_HASH(s, s->ins_h, s->window[1]);
345     for (n = 0; n <= length - MIN_MATCH; n++) {
346     INSERT_STRING(s, n, hash_head);
347     }
348     if (hash_head) hash_head = 0; /* to make compiler happy */
349     return Z_OK;
350     }
351    
352     /* ========================================================================= */
353     int ZEXPORT deflateReset (strm)
354     z_streamp strm;
355     {
356     deflate_state *s;
357    
358     if (strm == Z_NULL || strm->state == Z_NULL ||
359     strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
360     return Z_STREAM_ERROR;
361     }
362    
363     strm->total_in = strm->total_out = 0;
364     strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
365     strm->data_type = Z_UNKNOWN;
366    
367     s = (deflate_state *)strm->state;
368     s->pending = 0;
369     s->pending_out = s->pending_buf;
370    
371     if (s->wrap < 0) {
372     s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
373     }
374     s->status = s->wrap ? INIT_STATE : BUSY_STATE;
375     strm->adler =
376     #ifdef GZIP
377     s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
378     #endif
379     adler32(0L, Z_NULL, 0);
380     s->last_flush = Z_NO_FLUSH;
381    
382     _tr_init(s);
383     lm_init(s);
384    
385     return Z_OK;
386     }
387    
388     /* ========================================================================= */
389     int ZEXPORT deflateSetHeader (strm, head)
390     z_streamp strm;
391     gz_headerp head;
392     {
393     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
394     if (strm->state->wrap != 2) return Z_STREAM_ERROR;
395     strm->state->gzhead = head;
396     return Z_OK;
397     }
398    
399     /* ========================================================================= */
400     int ZEXPORT deflatePrime (strm, bits, value)
401     z_streamp strm;
402     int bits;
403     int value;
404     {
405     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
406     strm->state->bi_valid = bits;
407     strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
408     return Z_OK;
409     }
410    
411     /* ========================================================================= */
412     int ZEXPORT deflateParams(strm, level, strategy)
413     z_streamp strm;
414     int level;
415     int strategy;
416     {
417     deflate_state *s;
418     compress_func func;
419     int err = Z_OK;
420    
421     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
422     s = strm->state;
423    
424     #ifdef FASTEST
425     if (level != 0) level = 1;
426     #else
427     if (level == Z_DEFAULT_COMPRESSION) level = 6;
428     #endif
429     if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
430     return Z_STREAM_ERROR;
431     }
432     func = configuration_table[s->level].func;
433    
434     if ((strategy != s->strategy || func != configuration_table[level].func) &&
435     strm->total_in != 0) {
436     /* Flush the last buffer: */
437     err = deflate(strm, Z_BLOCK);
438     }
439     if (s->level != level) {
440     s->level = level;
441     s->max_lazy_match = configuration_table[level].max_lazy;
442     s->good_match = configuration_table[level].good_length;
443     s->nice_match = configuration_table[level].nice_length;
444     s->max_chain_length = configuration_table[level].max_chain;
445     }
446     s->strategy = strategy;
447     return err;
448     }
449    
450     /* ========================================================================= */
451     int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
452     z_streamp strm;
453     int good_length;
454     int max_lazy;
455     int nice_length;
456     int max_chain;
457     {
458     deflate_state *s;
459    
460     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
461     s = strm->state;
462     s->good_match = good_length;
463     s->max_lazy_match = max_lazy;
464     s->nice_match = nice_length;
465     s->max_chain_length = max_chain;
466     return Z_OK;
467     }
468    
469     /* =========================================================================
470     * For the default windowBits of 15 and memLevel of 8, this function returns
471     * a close to exact, as well as small, upper bound on the compressed size.
472     * They are coded as constants here for a reason--if the #define's are
473     * changed, then this function needs to be changed as well. The return
474     * value for 15 and 8 only works for those exact settings.
475     *
476     * For any setting other than those defaults for windowBits and memLevel,
477     * the value returned is a conservative worst case for the maximum expansion
478     * resulting from using fixed blocks instead of stored blocks, which deflate
479     * can emit on compressed data for some combinations of the parameters.
480     *
481     * This function could be more sophisticated to provide closer upper bounds for
482     * every combination of windowBits and memLevel. But even the conservative
483     * upper bound of about 14% expansion does not seem onerous for output buffer
484     * allocation.
485     */
486     uLong ZEXPORT deflateBound(strm, sourceLen)
487     z_streamp strm;
488     uLong sourceLen;
489     {
490     deflate_state *s;
491     uLong complen, wraplen;
492     Bytef *str;
493    
494     /* conservative upper bound for compressed data */
495     complen = sourceLen +
496     ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
497    
498     /* if can't get parameters, return conservative bound plus zlib wrapper */
499     if (strm == Z_NULL || strm->state == Z_NULL)
500     return complen + 6;
501    
502     /* compute wrapper length */
503     s = strm->state;
504     switch (s->wrap) {
505     case 0: /* raw deflate */
506     wraplen = 0;
507     break;
508     case 1: /* zlib wrapper */
509     wraplen = 6 + (s->strstart ? 4 : 0);
510     break;
511     case 2: /* gzip wrapper */
512     wraplen = 18;
513     if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
514     if (s->gzhead->extra != Z_NULL)
515     wraplen += 2 + s->gzhead->extra_len;
516     str = s->gzhead->name;
517     if (str != Z_NULL)
518     do {
519     wraplen++;
520     } while (*str++);
521     str = s->gzhead->comment;
522     if (str != Z_NULL)
523     do {
524     wraplen++;
525     } while (*str++);
526     if (s->gzhead->hcrc)
527     wraplen += 2;
528     }
529     break;
530     default: /* for compiler happiness */
531     wraplen = 6;
532     }
533    
534     /* if not default parameters, return conservative bound */
535     if (s->w_bits != 15 || s->hash_bits != 8 + 7)
536     return complen + wraplen;
537    
538     /* default settings: return tight bound for that case */
539     return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
540     (sourceLen >> 25) + 13 - 6 + wraplen;
541     }
542    
543     /* =========================================================================
544     * Put a short in the pending buffer. The 16-bit value is put in MSB order.
545     * IN assertion: the stream state is correct and there is enough room in
546     * pending_buf.
547     */
548     local void putShortMSB (s, b)
549     deflate_state *s;
550     uInt b;
551     {
552     put_byte(s, (Byte)(b >> 8));
553     put_byte(s, (Byte)(b & 0xff));
554     }
555    
556     /* =========================================================================
557     * Flush as much pending output as possible. All deflate() output goes
558     * through this function so some applications may wish to modify it
559     * to avoid allocating a large strm->next_out buffer and copying into it.
560     * (See also read_buf()).
561     */
562     local void flush_pending(strm)
563     z_streamp strm;
564     {
565     unsigned len = strm->state->pending;
566    
567     if (len > strm->avail_out) len = strm->avail_out;
568     if (len == 0) return;
569    
570     zmemcpy(strm->next_out, strm->state->pending_out, len);
571     strm->next_out += len;
572     strm->state->pending_out += len;
573     strm->total_out += len;
574     strm->avail_out -= len;
575     strm->state->pending -= len;
576     if (strm->state->pending == 0) {
577     strm->state->pending_out = strm->state->pending_buf;
578     }
579     }
580    
581     /* ========================================================================= */
582     int ZEXPORT deflate (strm, flush)
583     z_streamp strm;
584     int flush;
585     {
586     int old_flush; /* value of flush param for previous deflate call */
587     deflate_state *s;
588    
589     if (strm == Z_NULL || strm->state == Z_NULL ||
590     flush > Z_BLOCK || flush < 0) {
591     return Z_STREAM_ERROR;
592     }
593     s = strm->state;
594    
595     if (strm->next_out == Z_NULL ||
596     (strm->next_in == Z_NULL && strm->avail_in != 0) ||
597     (s->status == FINISH_STATE && flush != Z_FINISH)) {
598     ERR_RETURN(strm, Z_STREAM_ERROR);
599     }
600     if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
601    
602     s->strm = strm; /* just in case */
603     old_flush = s->last_flush;
604     s->last_flush = flush;
605    
606     /* Write the header */
607     if (s->status == INIT_STATE) {
608     #ifdef GZIP
609     if (s->wrap == 2) {
610     strm->adler = crc32(0L, Z_NULL, 0);
611     put_byte(s, 31);
612     put_byte(s, 139);
613     put_byte(s, 8);
614     if (s->gzhead == Z_NULL) {
615     put_byte(s, 0);
616     put_byte(s, 0);
617     put_byte(s, 0);
618     put_byte(s, 0);
619     put_byte(s, 0);
620     put_byte(s, s->level == 9 ? 2 :
621     (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
622     4 : 0));
623     put_byte(s, OS_CODE);
624     s->status = BUSY_STATE;
625     }
626     else {
627     put_byte(s, (s->gzhead->text ? 1 : 0) +
628     (s->gzhead->hcrc ? 2 : 0) +
629     (s->gzhead->extra == Z_NULL ? 0 : 4) +
630     (s->gzhead->name == Z_NULL ? 0 : 8) +
631     (s->gzhead->comment == Z_NULL ? 0 : 16)
632     );
633     put_byte(s, (Byte)(s->gzhead->time & 0xff));
634     put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
635     put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
636     put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
637     put_byte(s, s->level == 9 ? 2 :
638     (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
639     4 : 0));
640     put_byte(s, s->gzhead->os & 0xff);
641     if (s->gzhead->extra != Z_NULL) {
642     put_byte(s, s->gzhead->extra_len & 0xff);
643     put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
644     }
645     if (s->gzhead->hcrc)
646     strm->adler = crc32(strm->adler, s->pending_buf,
647     s->pending);
648     s->gzindex = 0;
649     s->status = EXTRA_STATE;
650     }
651     }
652     else
653     #endif
654     {
655     uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
656     uInt level_flags;
657    
658     if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
659     level_flags = 0;
660     else if (s->level < 6)
661     level_flags = 1;
662     else if (s->level == 6)
663     level_flags = 2;
664     else
665     level_flags = 3;
666     header |= (level_flags << 6);
667     if (s->strstart != 0) header |= PRESET_DICT;
668     header += 31 - (header % 31);
669    
670     s->status = BUSY_STATE;
671     putShortMSB(s, header);
672    
673     /* Save the adler32 of the preset dictionary: */
674     if (s->strstart != 0) {
675     putShortMSB(s, (uInt)(strm->adler >> 16));
676     putShortMSB(s, (uInt)(strm->adler & 0xffff));
677     }
678     strm->adler = adler32(0L, Z_NULL, 0);
679     }
680     }
681     #ifdef GZIP
682     if (s->status == EXTRA_STATE) {
683     if (s->gzhead->extra != Z_NULL) {
684     uInt beg = s->pending; /* start of bytes to update crc */
685    
686     while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
687     if (s->pending == s->pending_buf_size) {
688     if (s->gzhead->hcrc && s->pending > beg)
689     strm->adler = crc32(strm->adler, s->pending_buf + beg,
690     s->pending - beg);
691     flush_pending(strm);
692     beg = s->pending;
693     if (s->pending == s->pending_buf_size)
694     break;
695     }
696     put_byte(s, s->gzhead->extra[s->gzindex]);
697     s->gzindex++;
698     }
699     if (s->gzhead->hcrc && s->pending > beg)
700     strm->adler = crc32(strm->adler, s->pending_buf + beg,
701     s->pending - beg);
702     if (s->gzindex == s->gzhead->extra_len) {
703     s->gzindex = 0;
704     s->status = NAME_STATE;
705     }
706     }
707     else
708     s->status = NAME_STATE;
709     }
710     if (s->status == NAME_STATE) {
711     if (s->gzhead->name != Z_NULL) {
712     uInt beg = s->pending; /* start of bytes to update crc */
713     int val;
714    
715     do {
716     if (s->pending == s->pending_buf_size) {
717     if (s->gzhead->hcrc && s->pending > beg)
718     strm->adler = crc32(strm->adler, s->pending_buf + beg,
719     s->pending - beg);
720     flush_pending(strm);
721     beg = s->pending;
722     if (s->pending == s->pending_buf_size) {
723     val = 1;
724     break;
725     }
726     }
727     val = s->gzhead->name[s->gzindex++];
728     put_byte(s, val);
729     } while (val != 0);
730     if (s->gzhead->hcrc && s->pending > beg)
731     strm->adler = crc32(strm->adler, s->pending_buf + beg,
732     s->pending - beg);
733     if (val == 0) {
734     s->gzindex = 0;
735     s->status = COMMENT_STATE;
736     }
737     }
738     else
739     s->status = COMMENT_STATE;
740     }
741     if (s->status == COMMENT_STATE) {
742     if (s->gzhead->comment != Z_NULL) {
743     uInt beg = s->pending; /* start of bytes to update crc */
744     int val;
745    
746     do {
747     if (s->pending == s->pending_buf_size) {
748     if (s->gzhead->hcrc && s->pending > beg)
749     strm->adler = crc32(strm->adler, s->pending_buf + beg,
750     s->pending - beg);
751     flush_pending(strm);
752     beg = s->pending;
753     if (s->pending == s->pending_buf_size) {
754     val = 1;
755     break;
756     }
757     }
758     val = s->gzhead->comment[s->gzindex++];
759     put_byte(s, val);
760     } while (val != 0);
761     if (s->gzhead->hcrc && s->pending > beg)
762     strm->adler = crc32(strm->adler, s->pending_buf + beg,
763     s->pending - beg);
764     if (val == 0)
765     s->status = HCRC_STATE;
766     }
767     else
768     s->status = HCRC_STATE;
769     }
770     if (s->status == HCRC_STATE) {
771     if (s->gzhead->hcrc) {
772     if (s->pending + 2 > s->pending_buf_size)
773     flush_pending(strm);
774     if (s->pending + 2 <= s->pending_buf_size) {
775     put_byte(s, (Byte)(strm->adler & 0xff));
776     put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
777     strm->adler = crc32(0L, Z_NULL, 0);
778     s->status = BUSY_STATE;
779     }
780     }
781     else
782     s->status = BUSY_STATE;
783     }
784     #endif
785    
786     /* Flush as much pending output as possible */
787     if (s->pending != 0) {
788     flush_pending(strm);
789     if (strm->avail_out == 0) {
790     /* Since avail_out is 0, deflate will be called again with
791     * more output space, but possibly with both pending and
792     * avail_in equal to zero. There won't be anything to do,
793     * but this is not an error situation so make sure we
794     * return OK instead of BUF_ERROR at next call of deflate:
795     */
796     s->last_flush = -1;
797     return Z_OK;
798     }
799    
800     /* Make sure there is something to do and avoid duplicate consecutive
801     * flushes. For repeated and useless calls with Z_FINISH, we keep
802     * returning Z_STREAM_END instead of Z_BUF_ERROR.
803     */
804     } else if (strm->avail_in == 0 && flush <= old_flush &&
805     flush != Z_FINISH) {
806     ERR_RETURN(strm, Z_BUF_ERROR);
807     }
808    
809     /* User must not provide more input after the first FINISH: */
810     if (s->status == FINISH_STATE && strm->avail_in != 0) {
811     ERR_RETURN(strm, Z_BUF_ERROR);
812     }
813    
814     /* Start a new block or continue the current one.
815     */
816     if (strm->avail_in != 0 || s->lookahead != 0 ||
817     (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
818     block_state bstate;
819    
820     bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
821     (s->strategy == Z_RLE ? deflate_rle(s, flush) :
822     (*(configuration_table[s->level].func))(s, flush));
823    
824     if (bstate == finish_started || bstate == finish_done) {
825     s->status = FINISH_STATE;
826     }
827     if (bstate == need_more || bstate == finish_started) {
828     if (strm->avail_out == 0) {
829     s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
830     }
831     return Z_OK;
832     /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
833     * of deflate should use the same flush parameter to make sure
834     * that the flush is complete. So we don't have to output an
835     * empty block here, this will be done at next call. This also
836     * ensures that for a very small output buffer, we emit at most
837     * one empty block.
838     */
839     }
840     if (bstate == block_done) {
841     if (flush == Z_PARTIAL_FLUSH) {
842     _tr_align(s);
843     } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
844     _tr_stored_block(s, (char*)0, 0L, 0);
845     /* For a full flush, this empty block will be recognized
846     * as a special marker by inflate_sync().
847     */
848     if (flush == Z_FULL_FLUSH) {
849     CLEAR_HASH(s); /* forget history */
850     if (s->lookahead == 0) {
851     s->strstart = 0;
852     s->block_start = 0L;
853     }
854     }
855     }
856     flush_pending(strm);
857     if (strm->avail_out == 0) {
858     s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
859     return Z_OK;
860     }
861     }
862     }
863     Assert(strm->avail_out > 0, "bug2");
864    
865     if (flush != Z_FINISH) return Z_OK;
866     if (s->wrap <= 0) return Z_STREAM_END;
867    
868     /* Write the trailer */
869     #ifdef GZIP
870     if (s->wrap == 2) {
871     put_byte(s, (Byte)(strm->adler & 0xff));
872     put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
873     put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
874     put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
875     put_byte(s, (Byte)(strm->total_in & 0xff));
876     put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
877     put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
878     put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
879     }
880     else
881     #endif
882     {
883     putShortMSB(s, (uInt)(strm->adler >> 16));
884     putShortMSB(s, (uInt)(strm->adler & 0xffff));
885     }
886     flush_pending(strm);
887     /* If avail_out is zero, the application will call deflate again
888     * to flush the rest.
889     */
890     if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
891     return s->pending != 0 ? Z_OK : Z_STREAM_END;
892     }
893    
894     /* ========================================================================= */
895     int ZEXPORT deflateEnd (strm)
896     z_streamp strm;
897     {
898     int status;
899    
900     if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
901    
902     status = strm->state->status;
903     if (status != INIT_STATE &&
904     status != EXTRA_STATE &&
905     status != NAME_STATE &&
906     status != COMMENT_STATE &&
907     status != HCRC_STATE &&
908     status != BUSY_STATE &&
909     status != FINISH_STATE) {
910     return Z_STREAM_ERROR;
911     }
912    
913     /* Deallocate in reverse order of allocations: */
914     TRY_FREE(strm, strm->state->pending_buf);
915     TRY_FREE(strm, strm->state->head);
916     TRY_FREE(strm, strm->state->prev);
917     TRY_FREE(strm, strm->state->window);
918    
919     ZFREE(strm, strm->state);
920     strm->state = Z_NULL;
921    
922     return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
923     }
924    
925     /* =========================================================================
926     * Copy the source state to the destination state.
927     * To simplify the source, this is not supported for 16-bit MSDOS (which
928     * doesn't have enough memory anyway to duplicate compression states).
929     */
930     int ZEXPORT deflateCopy (dest, source)
931     z_streamp dest;
932     z_streamp source;
933     {
934     #ifdef MAXSEG_64K
935     return Z_STREAM_ERROR;
936     #else
937     deflate_state *ds;
938     deflate_state *ss;
939     ushf *overlay;
940    
941    
942     if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
943     return Z_STREAM_ERROR;
944     }
945    
946     ss = source->state;
947    
948     zmemcpy(dest, source, sizeof(z_stream));
949    
950     ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
951     if (ds == Z_NULL) return Z_MEM_ERROR;
952     dest->state = (struct internal_state FAR *) ds;
953     zmemcpy(ds, ss, sizeof(deflate_state));
954     ds->strm = dest;
955    
956     ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
957     ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
958     ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
959     overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
960     ds->pending_buf = (uchf *) overlay;
961    
962     if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
963     ds->pending_buf == Z_NULL) {
964     deflateEnd (dest);
965     return Z_MEM_ERROR;
966     }
967     /* following zmemcpy do not work for 16-bit MSDOS */
968     zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
969     zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
970     zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
971     zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
972    
973     ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
974     ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
975     ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
976    
977     ds->l_desc.dyn_tree = ds->dyn_ltree;
978     ds->d_desc.dyn_tree = ds->dyn_dtree;
979     ds->bl_desc.dyn_tree = ds->bl_tree;
980    
981     return Z_OK;
982     #endif /* MAXSEG_64K */
983     }
984    
985     /* ===========================================================================
986     * Read a new buffer from the current input stream, update the adler32
987     * and total number of bytes read. All deflate() input goes through
988     * this function so some applications may wish to modify it to avoid
989     * allocating a large strm->next_in buffer and copying from it.
990     * (See also flush_pending()).
991     */
992     local int read_buf(strm, buf, size)
993     z_streamp strm;
994     Bytef *buf;
995     unsigned size;
996     {
997     unsigned len = strm->avail_in;
998    
999     if (len > size) len = size;
1000     if (len == 0) return 0;
1001    
1002     strm->avail_in -= len;
1003    
1004     if (strm->state->wrap == 1) {
1005     strm->adler = adler32(strm->adler, strm->next_in, len);
1006     }
1007     #ifdef GZIP
1008     else if (strm->state->wrap == 2) {
1009     strm->adler = crc32(strm->adler, strm->next_in, len);
1010     }
1011     #endif
1012     zmemcpy(buf, strm->next_in, len);
1013     strm->next_in += len;
1014     strm->total_in += len;
1015    
1016     return (int)len;
1017     }
1018    
1019     /* ===========================================================================
1020     * Initialize the "longest match" routines for a new zlib stream
1021     */
1022     local void lm_init (s)
1023     deflate_state *s;
1024     {
1025     s->window_size = (ulg)2L*s->w_size;
1026    
1027     CLEAR_HASH(s);
1028    
1029     /* Set the default configuration parameters:
1030     */
1031     s->max_lazy_match = configuration_table[s->level].max_lazy;
1032     s->good_match = configuration_table[s->level].good_length;
1033     s->nice_match = configuration_table[s->level].nice_length;
1034     s->max_chain_length = configuration_table[s->level].max_chain;
1035    
1036     s->strstart = 0;
1037     s->block_start = 0L;
1038     s->lookahead = 0;
1039     s->match_length = s->prev_length = MIN_MATCH-1;
1040     s->match_available = 0;
1041     s->ins_h = 0;
1042     #ifndef FASTEST
1043     #ifdef ASMV
1044     match_init(); /* initialize the asm code */
1045     #endif
1046     #endif
1047     }
1048    
1049     #ifndef FASTEST
1050     /* ===========================================================================
1051     * Set match_start to the longest match starting at the given string and
1052     * return its length. Matches shorter or equal to prev_length are discarded,
1053     * in which case the result is equal to prev_length and match_start is
1054     * garbage.
1055     * IN assertions: cur_match is the head of the hash chain for the current
1056     * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1057     * OUT assertion: the match length is not greater than s->lookahead.
1058     */
1059     #ifndef ASMV
1060     /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1061     * match.S. The code will be functionally equivalent.
1062     */
1063     local uInt longest_match(s, cur_match)
1064     deflate_state *s;
1065     IPos cur_match; /* current match */
1066     {
1067     unsigned chain_length = s->max_chain_length;/* max hash chain length */
1068     register Bytef *scan = s->window + s->strstart; /* current string */
1069     register Bytef *match; /* matched string */
1070     register int len; /* length of current match */
1071     int best_len = s->prev_length; /* best match length so far */
1072     int nice_match = s->nice_match; /* stop if match long enough */
1073     IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1074     s->strstart - (IPos)MAX_DIST(s) : NIL;
1075     /* Stop when cur_match becomes <= limit. To simplify the code,
1076     * we prevent matches with the string of window index 0.
1077     */
1078     Posf *prev = s->prev;
1079     uInt wmask = s->w_mask;
1080    
1081     #ifdef UNALIGNED_OK
1082     /* Compare two bytes at a time. Note: this is not always beneficial.
1083     * Try with and without -DUNALIGNED_OK to check.
1084     */
1085     register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1086     register ush scan_start = *(ushf*)scan;
1087     register ush scan_end = *(ushf*)(scan+best_len-1);
1088     #else
1089     register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1090     register Byte scan_end1 = scan[best_len-1];
1091     register Byte scan_end = scan[best_len];
1092     #endif
1093    
1094     /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1095     * It is easy to get rid of this optimization if necessary.
1096     */
1097     Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1098    
1099     /* Do not waste too much time if we already have a good match: */
1100     if (s->prev_length >= s->good_match) {
1101     chain_length >>= 2;
1102     }
1103     /* Do not look for matches beyond the end of the input. This is necessary
1104     * to make deflate deterministic.
1105     */
1106     if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1107    
1108     Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1109    
1110     do {
1111     Assert(cur_match < s->strstart, "no future");
1112     match = s->window + cur_match;
1113    
1114     /* Skip to next match if the match length cannot increase
1115     * or if the match length is less than 2. Note that the checks below
1116     * for insufficient lookahead only occur occasionally for performance
1117     * reasons. Therefore uninitialized memory will be accessed, and
1118     * conditional jumps will be made that depend on those values.
1119     * However the length of the match is limited to the lookahead, so
1120     * the output of deflate is not affected by the uninitialized values.
1121     */
1122     #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1123     /* This code assumes sizeof(unsigned short) == 2. Do not use
1124     * UNALIGNED_OK if your compiler uses a different size.
1125     */
1126     if (*(ushf*)(match+best_len-1) != scan_end ||
1127     *(ushf*)match != scan_start) continue;
1128    
1129     /* It is not necessary to compare scan[2] and match[2] since they are
1130     * always equal when the other bytes match, given that the hash keys
1131     * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1132     * strstart+3, +5, ... up to strstart+257. We check for insufficient
1133     * lookahead only every 4th comparison; the 128th check will be made
1134     * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1135     * necessary to put more guard bytes at the end of the window, or
1136     * to check more often for insufficient lookahead.
1137     */
1138     Assert(scan[2] == match[2], "scan[2]?");
1139     scan++, match++;
1140     do {
1141     } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1142     *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1143     *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1144     *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1145     scan < strend);
1146     /* The funny "do {}" generates better code on most compilers */
1147    
1148     /* Here, scan <= window+strstart+257 */
1149     Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1150     if (*scan == *match) scan++;
1151    
1152     len = (MAX_MATCH - 1) - (int)(strend-scan);
1153     scan = strend - (MAX_MATCH-1);
1154    
1155     #else /* UNALIGNED_OK */
1156    
1157     if (match[best_len] != scan_end ||
1158     match[best_len-1] != scan_end1 ||
1159     *match != *scan ||
1160     *++match != scan[1]) continue;
1161    
1162     /* The check at best_len-1 can be removed because it will be made
1163     * again later. (This heuristic is not always a win.)
1164     * It is not necessary to compare scan[2] and match[2] since they
1165     * are always equal when the other bytes match, given that
1166     * the hash keys are equal and that HASH_BITS >= 8.
1167     */
1168     scan += 2, match++;
1169     Assert(*scan == *match, "match[2]?");
1170    
1171     /* We check for insufficient lookahead only every 8th comparison;
1172     * the 256th check will be made at strstart+258.
1173     */
1174     do {
1175     } while (*++scan == *++match && *++scan == *++match &&
1176     *++scan == *++match && *++scan == *++match &&
1177     *++scan == *++match && *++scan == *++match &&
1178     *++scan == *++match && *++scan == *++match &&
1179     scan < strend);
1180    
1181     Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1182    
1183     len = MAX_MATCH - (int)(strend - scan);
1184     scan = strend - MAX_MATCH;
1185    
1186     #endif /* UNALIGNED_OK */
1187    
1188     if (len > best_len) {
1189     s->match_start = cur_match;
1190     best_len = len;
1191     if (len >= nice_match) break;
1192     #ifdef UNALIGNED_OK
1193     scan_end = *(ushf*)(scan+best_len-1);
1194     #else
1195     scan_end1 = scan[best_len-1];
1196     scan_end = scan[best_len];
1197     #endif
1198     }
1199     } while ((cur_match = prev[cur_match & wmask]) > limit
1200     && --chain_length != 0);
1201    
1202     if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1203     return s->lookahead;
1204     }
1205     #endif /* ASMV */
1206    
1207     #else /* FASTEST */
1208    
1209     /* ---------------------------------------------------------------------------
1210     * Optimized version for FASTEST only
1211     */
1212     local uInt longest_match(s, cur_match)
1213     deflate_state *s;
1214     IPos cur_match; /* current match */
1215     {
1216     register Bytef *scan = s->window + s->strstart; /* current string */
1217     register Bytef *match; /* matched string */
1218     register int len; /* length of current match */
1219     register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1220    
1221     /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1222     * It is easy to get rid of this optimization if necessary.
1223     */
1224     Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1225    
1226     Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1227    
1228     Assert(cur_match < s->strstart, "no future");
1229    
1230     match = s->window + cur_match;
1231    
1232     /* Return failure if the match length is less than 2:
1233     */
1234     if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1235    
1236     /* The check at best_len-1 can be removed because it will be made
1237     * again later. (This heuristic is not always a win.)
1238     * It is not necessary to compare scan[2] and match[2] since they
1239     * are always equal when the other bytes match, given that
1240     * the hash keys are equal and that HASH_BITS >= 8.
1241     */
1242     scan += 2, match += 2;
1243     Assert(*scan == *match, "match[2]?");
1244    
1245     /* We check for insufficient lookahead only every 8th comparison;
1246     * the 256th check will be made at strstart+258.
1247     */
1248     do {
1249     } while (*++scan == *++match && *++scan == *++match &&
1250     *++scan == *++match && *++scan == *++match &&
1251     *++scan == *++match && *++scan == *++match &&
1252     *++scan == *++match && *++scan == *++match &&
1253     scan < strend);
1254    
1255     Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1256    
1257     len = MAX_MATCH - (int)(strend - scan);
1258    
1259     if (len < MIN_MATCH) return MIN_MATCH - 1;
1260    
1261     s->match_start = cur_match;
1262     return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1263     }
1264    
1265     #endif /* FASTEST */
1266    
1267     #ifdef DEBUG
1268     /* ===========================================================================
1269     * Check that the match at match_start is indeed a match.
1270     */
1271     local void check_match(s, start, match, length)
1272     deflate_state *s;
1273     IPos start, match;
1274     int length;
1275     {
1276     /* check that the match is indeed a match */
1277     if (zmemcmp(s->window + match,
1278     s->window + start, length) != EQUAL) {
1279     fprintf(stderr, " start %u, match %u, length %d\n",
1280     start, match, length);
1281     do {
1282     fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1283     } while (--length != 0);
1284     z_error("invalid match");
1285     }
1286     if (z_verbose > 1) {
1287     fprintf(stderr,"\\[%d,%d]", start-match, length);
1288     do { putc(s->window[start++], stderr); } while (--length != 0);
1289     }
1290     }
1291     #else
1292     # define check_match(s, start, match, length)
1293     #endif /* DEBUG */
1294    
1295     /* ===========================================================================
1296     * Fill the window when the lookahead becomes insufficient.
1297     * Updates strstart and lookahead.
1298     *
1299     * IN assertion: lookahead < MIN_LOOKAHEAD
1300     * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1301     * At least one byte has been read, or avail_in == 0; reads are
1302     * performed for at least two bytes (required for the zip translate_eol
1303     * option -- not supported here).
1304     */
1305     local void fill_window(s)
1306     deflate_state *s;
1307     {
1308     register unsigned n, m;
1309     register Posf *p;
1310     unsigned more; /* Amount of free space at the end of the window. */
1311     uInt wsize = s->w_size;
1312    
1313     do {
1314     more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1315    
1316     /* Deal with !@#$% 64K limit: */
1317     if (sizeof(int) <= 2) {
1318     if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1319     more = wsize;
1320    
1321     } else if (more == (unsigned)(-1)) {
1322     /* Very unlikely, but possible on 16 bit machine if
1323     * strstart == 0 && lookahead == 1 (input done a byte at time)
1324     */
1325     more--;
1326     }
1327     }
1328    
1329     /* If the window is almost full and there is insufficient lookahead,
1330     * move the upper half to the lower one to make room in the upper half.
1331     */
1332     if (s->strstart >= wsize+MAX_DIST(s)) {
1333    
1334     zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1335     s->match_start -= wsize;
1336     s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1337     s->block_start -= (long) wsize;
1338    
1339     /* Slide the hash table (could be avoided with 32 bit values
1340     at the expense of memory usage). We slide even when level == 0
1341     to keep the hash table consistent if we switch back to level > 0
1342     later. (Using level 0 permanently is not an optimal usage of
1343     zlib, so we don't care about this pathological case.)
1344     */
1345     n = s->hash_size;
1346     p = &s->head[n];
1347     do {
1348     m = *--p;
1349     *p = (Pos)(m >= wsize ? m-wsize : NIL);
1350     } while (--n);
1351    
1352     n = wsize;
1353     #ifndef FASTEST
1354     p = &s->prev[n];
1355     do {
1356     m = *--p;
1357     *p = (Pos)(m >= wsize ? m-wsize : NIL);
1358     /* If n is not on any hash chain, prev[n] is garbage but
1359     * its value will never be used.
1360     */
1361     } while (--n);
1362     #endif
1363     more += wsize;
1364     }
1365     if (s->strm->avail_in == 0) return;
1366    
1367     /* If there was no sliding:
1368     * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1369     * more == window_size - lookahead - strstart
1370     * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1371     * => more >= window_size - 2*WSIZE + 2
1372     * In the BIG_MEM or MMAP case (not yet supported),
1373     * window_size == input_size + MIN_LOOKAHEAD &&
1374     * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1375     * Otherwise, window_size == 2*WSIZE so more >= 2.
1376     * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1377     */
1378     Assert(more >= 2, "more < 2");
1379    
1380     n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1381     s->lookahead += n;
1382    
1383     /* Initialize the hash value now that we have some input: */
1384     if (s->lookahead >= MIN_MATCH) {
1385     s->ins_h = s->window[s->strstart];
1386     UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1387     #if MIN_MATCH != 3
1388     Call UPDATE_HASH() MIN_MATCH-3 more times
1389     #endif
1390     }
1391     /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1392     * but this is not important since only literal bytes will be emitted.
1393     */
1394    
1395     } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1396    
1397     /* If the WIN_INIT bytes after the end of the current data have never been
1398     * written, then zero those bytes in order to avoid memory check reports of
1399     * the use of uninitialized (or uninitialised as Julian writes) bytes by
1400     * the longest match routines. Update the high water mark for the next
1401     * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1402     * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1403     */
1404     if (s->high_water < s->window_size) {
1405     ulg curr = s->strstart + (ulg)(s->lookahead);
1406     ulg init;
1407    
1408     if (s->high_water < curr) {
1409     /* Previous high water mark below current data -- zero WIN_INIT
1410     * bytes or up to end of window, whichever is less.
1411     */
1412     init = s->window_size - curr;
1413     if (init > WIN_INIT)
1414     init = WIN_INIT;
1415     zmemzero(s->window + curr, (unsigned)init);
1416     s->high_water = curr + init;
1417     }
1418     else if (s->high_water < (ulg)curr + WIN_INIT) {
1419     /* High water mark at or above current data, but below current data
1420     * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1421     * to end of window, whichever is less.
1422     */
1423     init = (ulg)curr + WIN_INIT - s->high_water;
1424     if (init > s->window_size - s->high_water)
1425     init = s->window_size - s->high_water;
1426     zmemzero(s->window + s->high_water, (unsigned)init);
1427     s->high_water += init;
1428     }
1429     }
1430     }
1431    
1432     /* ===========================================================================
1433     * Flush the current block, with given end-of-file flag.
1434     * IN assertion: strstart is set to the end of the current match.
1435     */
1436     #define FLUSH_BLOCK_ONLY(s, last) { \
1437     _tr_flush_block(s, (s->block_start >= 0L ? \
1438     (charf *)&s->window[(unsigned)s->block_start] : \
1439     (charf *)Z_NULL), \
1440     (ulg)((long)s->strstart - s->block_start), \
1441     (last)); \
1442     s->block_start = s->strstart; \
1443     flush_pending(s->strm); \
1444     Tracev((stderr,"[FLUSH]")); \
1445     }
1446    
1447     /* Same but force premature exit if necessary. */
1448     #define FLUSH_BLOCK(s, last) { \
1449     FLUSH_BLOCK_ONLY(s, last); \
1450     if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1451     }
1452    
1453     /* ===========================================================================
1454     * Copy without compression as much as possible from the input stream, return
1455     * the current block state.
1456     * This function does not insert new strings in the dictionary since
1457     * uncompressible data is probably not useful. This function is used
1458     * only for the level=0 compression option.
1459     * NOTE: this function should be optimized to avoid extra copying from
1460     * window to pending_buf.
1461     */
1462     local block_state deflate_stored(s, flush)
1463     deflate_state *s;
1464     int flush;
1465     {
1466     /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1467     * to pending_buf_size, and each stored block has a 5 byte header:
1468     */
1469     ulg max_block_size = 0xffff;
1470     ulg max_start;
1471    
1472     if (max_block_size > s->pending_buf_size - 5) {
1473     max_block_size = s->pending_buf_size - 5;
1474     }
1475    
1476     /* Copy as much as possible from input to output: */
1477     for (;;) {
1478     /* Fill the window as much as possible: */
1479     if (s->lookahead <= 1) {
1480    
1481     Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1482     s->block_start >= (long)s->w_size, "slide too late");
1483    
1484     fill_window(s);
1485     if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1486    
1487     if (s->lookahead == 0) break; /* flush the current block */
1488     }
1489     Assert(s->block_start >= 0L, "block gone");
1490    
1491     s->strstart += s->lookahead;
1492     s->lookahead = 0;
1493    
1494     /* Emit a stored block if pending_buf will be full: */
1495     max_start = s->block_start + max_block_size;
1496     if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1497     /* strstart == 0 is possible when wraparound on 16-bit machine */
1498     s->lookahead = (uInt)(s->strstart - max_start);
1499     s->strstart = (uInt)max_start;
1500     FLUSH_BLOCK(s, 0);
1501     }
1502     /* Flush if we may have to slide, otherwise block_start may become
1503     * negative and the data will be gone:
1504     */
1505     if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1506     FLUSH_BLOCK(s, 0);
1507     }
1508     }
1509     FLUSH_BLOCK(s, flush == Z_FINISH);
1510     return flush == Z_FINISH ? finish_done : block_done;
1511     }
1512    
1513     /* ===========================================================================
1514     * Compress as much as possible from the input stream, return the current
1515     * block state.
1516     * This function does not perform lazy evaluation of matches and inserts
1517     * new strings in the dictionary only for unmatched strings or for short
1518     * matches. It is used only for the fast compression options.
1519     */
1520     local block_state deflate_fast(s, flush)
1521     deflate_state *s;
1522     int flush;
1523     {
1524     IPos hash_head; /* head of the hash chain */
1525     int bflush; /* set if current block must be flushed */
1526    
1527     for (;;) {
1528     /* Make sure that we always have enough lookahead, except
1529     * at the end of the input file. We need MAX_MATCH bytes
1530     * for the next match, plus MIN_MATCH bytes to insert the
1531     * string following the next match.
1532     */
1533     if (s->lookahead < MIN_LOOKAHEAD) {
1534     fill_window(s);
1535     if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1536     return need_more;
1537     }
1538     if (s->lookahead == 0) break; /* flush the current block */
1539     }
1540    
1541     /* Insert the string window[strstart .. strstart+2] in the
1542     * dictionary, and set hash_head to the head of the hash chain:
1543     */
1544     hash_head = NIL;
1545     if (s->lookahead >= MIN_MATCH) {
1546     INSERT_STRING(s, s->strstart, hash_head);
1547     }
1548    
1549     /* Find the longest match, discarding those <= prev_length.
1550     * At this point we have always match_length < MIN_MATCH
1551     */
1552     if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1553     /* To simplify the code, we prevent matches with the string
1554     * of window index 0 (in particular we have to avoid a match
1555     * of the string with itself at the start of the input file).
1556     */
1557     s->match_length = longest_match (s, hash_head);
1558     /* longest_match() sets match_start */
1559     }
1560     if (s->match_length >= MIN_MATCH) {
1561     check_match(s, s->strstart, s->match_start, s->match_length);
1562    
1563     _tr_tally_dist(s, s->strstart - s->match_start,
1564     s->match_length - MIN_MATCH, bflush);
1565    
1566     s->lookahead -= s->match_length;
1567    
1568     /* Insert new strings in the hash table only if the match length
1569     * is not too large. This saves time but degrades compression.
1570     */
1571     #ifndef FASTEST
1572     if (s->match_length <= s->max_insert_length &&
1573     s->lookahead >= MIN_MATCH) {
1574     s->match_length--; /* string at strstart already in table */
1575     do {
1576     s->strstart++;
1577     INSERT_STRING(s, s->strstart, hash_head);
1578     /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1579     * always MIN_MATCH bytes ahead.
1580     */
1581     } while (--s->match_length != 0);
1582     s->strstart++;
1583     } else
1584     #endif
1585     {
1586     s->strstart += s->match_length;
1587     s->match_length = 0;
1588     s->ins_h = s->window[s->strstart];
1589     UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1590     #if MIN_MATCH != 3
1591     Call UPDATE_HASH() MIN_MATCH-3 more times
1592     #endif
1593     /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1594     * matter since it will be recomputed at next deflate call.
1595     */
1596     }
1597     } else {
1598     /* No match, output a literal byte */
1599     Tracevv((stderr,"%c", s->window[s->strstart]));
1600     _tr_tally_lit (s, s->window[s->strstart], bflush);
1601     s->lookahead--;
1602     s->strstart++;
1603     }
1604     if (bflush) FLUSH_BLOCK(s, 0);
1605     }
1606     FLUSH_BLOCK(s, flush == Z_FINISH);
1607     return flush == Z_FINISH ? finish_done : block_done;
1608     }
1609    
1610     #ifndef FASTEST
1611     /* ===========================================================================
1612     * Same as above, but achieves better compression. We use a lazy
1613     * evaluation for matches: a match is finally adopted only if there is
1614     * no better match at the next window position.
1615     */
1616     local block_state deflate_slow(s, flush)
1617     deflate_state *s;
1618     int flush;
1619     {
1620     IPos hash_head; /* head of hash chain */
1621     int bflush; /* set if current block must be flushed */
1622    
1623     /* Process the input block. */
1624     for (;;) {
1625     /* Make sure that we always have enough lookahead, except
1626     * at the end of the input file. We need MAX_MATCH bytes
1627     * for the next match, plus MIN_MATCH bytes to insert the
1628     * string following the next match.
1629     */
1630     if (s->lookahead < MIN_LOOKAHEAD) {
1631     fill_window(s);
1632     if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1633     return need_more;
1634     }
1635     if (s->lookahead == 0) break; /* flush the current block */
1636     }
1637    
1638     /* Insert the string window[strstart .. strstart+2] in the
1639     * dictionary, and set hash_head to the head of the hash chain:
1640     */
1641     hash_head = NIL;
1642     if (s->lookahead >= MIN_MATCH) {
1643     INSERT_STRING(s, s->strstart, hash_head);
1644     }
1645    
1646     /* Find the longest match, discarding those <= prev_length.
1647     */
1648     s->prev_length = s->match_length, s->prev_match = s->match_start;
1649     s->match_length = MIN_MATCH-1;
1650    
1651     if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1652     s->strstart - hash_head <= MAX_DIST(s)) {
1653     /* To simplify the code, we prevent matches with the string
1654     * of window index 0 (in particular we have to avoid a match
1655     * of the string with itself at the start of the input file).
1656     */
1657     s->match_length = longest_match (s, hash_head);
1658     /* longest_match() sets match_start */
1659    
1660     if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1661     #if TOO_FAR <= 32767
1662     || (s->match_length == MIN_MATCH &&
1663     s->strstart - s->match_start > TOO_FAR)
1664     #endif
1665     )) {
1666    
1667     /* If prev_match is also MIN_MATCH, match_start is garbage
1668     * but we will ignore the current match anyway.
1669     */
1670     s->match_length = MIN_MATCH-1;
1671     }
1672     }
1673     /* If there was a match at the previous step and the current
1674     * match is not better, output the previous match:
1675     */
1676     if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1677     uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1678     /* Do not insert strings in hash table beyond this. */
1679    
1680     check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1681    
1682     _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1683     s->prev_length - MIN_MATCH, bflush);
1684    
1685     /* Insert in hash table all strings up to the end of the match.
1686     * strstart-1 and strstart are already inserted. If there is not
1687     * enough lookahead, the last two strings are not inserted in
1688     * the hash table.
1689     */
1690     s->lookahead -= s->prev_length-1;
1691     s->prev_length -= 2;
1692     do {
1693     if (++s->strstart <= max_insert) {
1694     INSERT_STRING(s, s->strstart, hash_head);
1695     }
1696     } while (--s->prev_length != 0);
1697     s->match_available = 0;
1698     s->match_length = MIN_MATCH-1;
1699     s->strstart++;
1700    
1701     if (bflush) FLUSH_BLOCK(s, 0);
1702    
1703     } else if (s->match_available) {
1704     /* If there was no match at the previous position, output a
1705     * single literal. If there was a match but the current match
1706     * is longer, truncate the previous match to a single literal.
1707     */
1708     Tracevv((stderr,"%c", s->window[s->strstart-1]));
1709     _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1710     if (bflush) {
1711     FLUSH_BLOCK_ONLY(s, 0);
1712     }
1713     s->strstart++;
1714     s->lookahead--;
1715     if (s->strm->avail_out == 0) return need_more;
1716     } else {
1717     /* There is no previous match to compare with, wait for
1718     * the next step to decide.
1719     */
1720     s->match_available = 1;
1721     s->strstart++;
1722     s->lookahead--;
1723     }
1724     }
1725     Assert (flush != Z_NO_FLUSH, "no flush?");
1726     if (s->match_available) {
1727     Tracevv((stderr,"%c", s->window[s->strstart-1]));
1728     _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1729     s->match_available = 0;
1730     }
1731     FLUSH_BLOCK(s, flush == Z_FINISH);
1732     return flush == Z_FINISH ? finish_done : block_done;
1733     }
1734     #endif /* FASTEST */
1735    
1736     /* ===========================================================================
1737     * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1738     * one. Do not maintain a hash table. (It will be regenerated if this run of
1739     * deflate switches away from Z_RLE.)
1740     */
1741     local block_state deflate_rle(s, flush)
1742     deflate_state *s;
1743     int flush;
1744     {
1745     int bflush; /* set if current block must be flushed */
1746     uInt prev; /* byte at distance one to match */
1747     Bytef *scan, *strend; /* scan goes up to strend for length of run */
1748    
1749     for (;;) {
1750     /* Make sure that we always have enough lookahead, except
1751     * at the end of the input file. We need MAX_MATCH bytes
1752     * for the longest encodable run.
1753     */
1754     if (s->lookahead < MAX_MATCH) {
1755     fill_window(s);
1756     if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {
1757     return need_more;
1758     }
1759     if (s->lookahead == 0) break; /* flush the current block */
1760     }
1761    
1762     /* See how many times the previous byte repeats */
1763     s->match_length = 0;
1764     if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
1765     scan = s->window + s->strstart - 1;
1766     prev = *scan;
1767     if (prev == *++scan && prev == *++scan && prev == *++scan) {
1768     strend = s->window + s->strstart + MAX_MATCH;
1769     do {
1770     } while (prev == *++scan && prev == *++scan &&
1771     prev == *++scan && prev == *++scan &&
1772     prev == *++scan && prev == *++scan &&
1773     prev == *++scan && prev == *++scan &&
1774     scan < strend);
1775     s->match_length = MAX_MATCH - (int)(strend - scan);
1776     if (s->match_length > s->lookahead)
1777     s->match_length = s->lookahead;
1778     }
1779     }
1780    
1781     /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1782     if (s->match_length >= MIN_MATCH) {
1783     check_match(s, s->strstart, s->strstart - 1, s->match_length);
1784    
1785     _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
1786    
1787     s->lookahead -= s->match_length;
1788     s->strstart += s->match_length;
1789     s->match_length = 0;
1790     } else {
1791     /* No match, output a literal byte */
1792     Tracevv((stderr,"%c", s->window[s->strstart]));
1793     _tr_tally_lit (s, s->window[s->strstart], bflush);
1794     s->lookahead--;
1795     s->strstart++;
1796     }
1797     if (bflush) FLUSH_BLOCK(s, 0);
1798     }
1799     FLUSH_BLOCK(s, flush == Z_FINISH);
1800     return flush == Z_FINISH ? finish_done : block_done;
1801     }
1802    
1803     /* ===========================================================================
1804     * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
1805     * (It will be regenerated if this run of deflate switches away from Huffman.)
1806     */
1807     local block_state deflate_huff(s, flush)
1808     deflate_state *s;
1809     int flush;
1810     {
1811     int bflush; /* set if current block must be flushed */
1812    
1813     for (;;) {
1814     /* Make sure that we have a literal to write. */
1815     if (s->lookahead == 0) {
1816     fill_window(s);
1817     if (s->lookahead == 0) {
1818     if (flush == Z_NO_FLUSH)
1819     return need_more;
1820     break; /* flush the current block */
1821     }
1822     }
1823    
1824     /* Output a literal byte */
1825     s->match_length = 0;
1826     Tracevv((stderr,"%c", s->window[s->strstart]));
1827     _tr_tally_lit (s, s->window[s->strstart], bflush);
1828     s->lookahead--;
1829     s->strstart++;
1830     if (bflush) FLUSH_BLOCK(s, 0);
1831     }
1832     FLUSH_BLOCK(s, flush == Z_FINISH);
1833     return flush == Z_FINISH ? finish_done : block_done;
1834     }

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