source: rtems/cpukit/zlib/deflate.c @ 59efee34

4.104.11
Last change on this file since 59efee34 was d29a42b, checked in by Ralf Corsepius <ralf.corsepius@…>, on Sep 2, 2008 at 5:33:58 AM

Stop using old-style function definitions.

  • Property mode set to 100644
File size: 62.2 KB
Line 
1/* deflate.c -- compress data using the deflation algorithm
2 * Copyright (C) 1995-2005 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 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
54const char deflate_copyright[] =
55   " deflate 1.2.3 Copyright 1995-2005 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 */
66typedef 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
73typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74/* Compression function. Returns the block state after the call. */
75
76local void fill_window    OF((deflate_state *s));
77local block_state deflate_stored OF((deflate_state *s, int flush));
78local block_state deflate_fast   OF((deflate_state *s, int flush));
79#ifndef FASTEST
80local block_state deflate_slow   OF((deflate_state *s, int flush));
81#endif
82local void lm_init        OF((deflate_state *s));
83local void putShortMSB    OF((deflate_state *s, uInt b));
84local void flush_pending  OF((z_streamp strm));
85local int read_buf        OF((z_streamp strm, Bytef *buf, unsigned size));
86#ifndef FASTEST
87#ifdef ASMV
88      void match_init OF((void)); /* asm code initialization */
89      uInt longest_match  OF((deflate_state *s, IPos cur_match));
90#else
91local uInt longest_match  OF((deflate_state *s, IPos cur_match));
92#endif
93#endif
94local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
95
96#ifdef DEBUG
97local  void check_match OF((deflate_state *s, IPos start, IPos match,
98                            int length));
99#endif
100
101/* ===========================================================================
102 * Local data
103 */
104
105#define NIL 0
106/* Tail of hash chains */
107
108#ifndef TOO_FAR
109#  define TOO_FAR 4096
110#endif
111/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
112
113#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
114/* Minimum amount of lookahead, except at the end of the input file.
115 * See deflate.c for comments about the MIN_MATCH+1.
116 */
117
118/* Values for max_lazy_match, good_match and max_chain_length, depending on
119 * the desired pack level (0..9). The values given below have been tuned to
120 * exclude worst case performance for pathological files. Better values may be
121 * found for specific files.
122 */
123typedef struct config_s {
124   ush good_length; /* reduce lazy search above this match length */
125   ush max_lazy;    /* do not perform lazy search above this match length */
126   ush nice_length; /* quit search above this match length */
127   ush max_chain;
128   compress_func func;
129} config;
130
131#ifdef FASTEST
132local const config configuration_table[2] = {
133/*      good lazy nice chain */
134/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
135/* 1 */ {4,    4,  8,    4, deflate_fast}}; /* max speed, no lazy matches */
136#else
137local const config configuration_table[10] = {
138/*      good lazy nice chain */
139/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
140/* 1 */ {4,    4,  8,    4, deflate_fast}, /* max speed, no lazy matches */
141/* 2 */ {4,    5, 16,    8, deflate_fast},
142/* 3 */ {4,    6, 32,   32, deflate_fast},
143
144/* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
145/* 5 */ {8,   16, 32,   32, deflate_slow},
146/* 6 */ {8,   16, 128, 128, deflate_slow},
147/* 7 */ {8,   32, 128, 256, deflate_slow},
148/* 8 */ {32, 128, 258, 1024, deflate_slow},
149/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
150#endif
151
152/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
153 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
154 * meaning.
155 */
156
157#define EQUAL 0
158/* result of memcmp for equal strings */
159
160#ifndef NO_DUMMY_DECL
161struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
162#endif
163
164/* ===========================================================================
165 * Update a hash value with the given input byte
166 * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
167 *    input characters, so that a running hash key can be computed from the
168 *    previous key instead of complete recalculation each time.
169 */
170#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
171
172
173/* ===========================================================================
174 * Insert string str in the dictionary and set match_head to the previous head
175 * of the hash chain (the most recent string with same hash key). Return
176 * the previous length of the hash chain.
177 * If this file is compiled with -DFASTEST, the compression level is forced
178 * to 1, and no hash chains are maintained.
179 * IN  assertion: all calls to to INSERT_STRING are made with consecutive
180 *    input characters and the first MIN_MATCH bytes of str are valid
181 *    (except for the last MIN_MATCH-1 bytes of the input file).
182 */
183#ifdef FASTEST
184#define INSERT_STRING(s, str, match_head) \
185   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
186    match_head = s->head[s->ins_h], \
187    s->head[s->ins_h] = (Pos)(str))
188#else
189#define INSERT_STRING(s, str, match_head) \
190   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
191    match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
192    s->head[s->ins_h] = (Pos)(str))
193#endif
194
195/* ===========================================================================
196 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
197 * prev[] will be initialized on the fly.
198 */
199#define CLEAR_HASH(s) \
200    s->head[s->hash_size-1] = NIL; \
201    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
202
203/* ========================================================================= */
204int ZEXPORT deflateInit_(
205    z_streamp strm,
206    int level,
207    const char *version,
208    int stream_size)
209{
210    return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
211                         Z_DEFAULT_STRATEGY, version, stream_size);
212    /* To do: ignore strm->next_in if we use it as window */
213}
214
215/* ========================================================================= */
216int ZEXPORT deflateInit2_(
217    z_streamp strm,
218    int  level,
219    int  method,
220    int  windowBits,
221    int  memLevel,
222    int  strategy,
223    const char *version,
224    int stream_size)
225{
226    deflate_state *s;
227    int wrap = 1;
228    static const char my_version[] = ZLIB_VERSION;
229
230    ushf *overlay;
231    /* We overlay pending_buf and d_buf+l_buf. This works since the average
232     * output size for (length,distance) codes is <= 24 bits.
233     */
234
235    if (version == Z_NULL || version[0] != my_version[0] ||
236        stream_size != sizeof(z_stream)) {
237        return Z_VERSION_ERROR;
238    }
239    if (strm == Z_NULL) return Z_STREAM_ERROR;
240
241    strm->msg = Z_NULL;
242    if (strm->zalloc == (alloc_func)0) {
243        strm->zalloc = zcalloc;
244        strm->opaque = (voidpf)0;
245    }
246    if (strm->zfree == (free_func)0) strm->zfree = zcfree;
247
248#ifdef FASTEST
249    if (level != 0) level = 1;
250#else
251    if (level == Z_DEFAULT_COMPRESSION) level = 6;
252#endif
253
254    if (windowBits < 0) { /* suppress zlib wrapper */
255        wrap = 0;
256        windowBits = -windowBits;
257    }
258#ifdef GZIP
259    else if (windowBits > 15) {
260        wrap = 2;       /* write gzip wrapper instead */
261        windowBits -= 16;
262    }
263#endif
264    if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
265        windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
266        strategy < 0 || strategy > Z_FIXED) {
267        return Z_STREAM_ERROR;
268    }
269    if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */
270    s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
271    if (s == Z_NULL) return Z_MEM_ERROR;
272    strm->state = (struct internal_state FAR *)s;
273    s->strm = strm;
274
275    s->wrap = wrap;
276    s->gzhead = Z_NULL;
277    s->w_bits = windowBits;
278    s->w_size = 1 << s->w_bits;
279    s->w_mask = s->w_size - 1;
280
281    s->hash_bits = memLevel + 7;
282    s->hash_size = 1 << s->hash_bits;
283    s->hash_mask = s->hash_size - 1;
284    s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
285
286    s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
287    s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
288    s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
289
290    s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
291
292    overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
293    s->pending_buf = (uchf *) overlay;
294    s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
295
296    if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
297        s->pending_buf == Z_NULL) {
298        s->status = FINISH_STATE;
299        strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
300        deflateEnd (strm);
301        return Z_MEM_ERROR;
302    }
303    s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
304    s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
305
306    s->level = level;
307    s->strategy = strategy;
308    s->method = (Byte)method;
309
310    return deflateReset(strm);
311}
312
313/* ========================================================================= */
314int ZEXPORT deflateSetDictionary (
315    z_streamp strm,
316    const Bytef *dictionary,
317    uInt  dictLength)
318{
319    deflate_state *s;
320    uInt length = dictLength;
321    uInt n;
322    IPos hash_head = 0;
323
324    if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
325        strm->state->wrap == 2 ||
326        (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
327        return Z_STREAM_ERROR;
328
329    s = strm->state;
330    if (s->wrap)
331        strm->adler = adler32(strm->adler, dictionary, dictLength);
332
333    if (length < MIN_MATCH) return Z_OK;
334    if (length > MAX_DIST(s)) {
335        length = MAX_DIST(s);
336        dictionary += dictLength - length; /* use the tail of the dictionary */
337    }
338    zmemcpy(s->window, dictionary, length);
339    s->strstart = length;
340    s->block_start = (long)length;
341
342    /* Insert all strings in the hash table (except for the last two bytes).
343     * s->lookahead stays null, so s->ins_h will be recomputed at the next
344     * call of fill_window.
345     */
346    s->ins_h = s->window[0];
347    UPDATE_HASH(s, s->ins_h, s->window[1]);
348    for (n = 0; n <= length - MIN_MATCH; n++) {
349        INSERT_STRING(s, n, hash_head);
350    }
351    if (hash_head) hash_head = 0;  /* to make compiler happy */
352    return Z_OK;
353}
354
355/* ========================================================================= */
356int ZEXPORT deflateReset (
357    z_streamp strm)
358{
359    deflate_state *s;
360
361    if (strm == Z_NULL || strm->state == Z_NULL ||
362        strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
363        return Z_STREAM_ERROR;
364    }
365
366    strm->total_in = strm->total_out = 0;
367    strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
368    strm->data_type = Z_UNKNOWN;
369
370    s = (deflate_state *)strm->state;
371    s->pending = 0;
372    s->pending_out = s->pending_buf;
373
374    if (s->wrap < 0) {
375        s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
376    }
377    s->status = s->wrap ? INIT_STATE : BUSY_STATE;
378    strm->adler =
379#ifdef GZIP
380        s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
381#endif
382        adler32(0L, Z_NULL, 0);
383    s->last_flush = Z_NO_FLUSH;
384
385    _tr_init(s);
386    lm_init(s);
387
388    return Z_OK;
389}
390
391/* ========================================================================= */
392int ZEXPORT deflateSetHeader (
393    z_streamp strm,
394    gz_headerp head)
395{
396    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
397    if (strm->state->wrap != 2) return Z_STREAM_ERROR;
398    strm->state->gzhead = head;
399    return Z_OK;
400}
401
402/* ========================================================================= */
403int ZEXPORT deflatePrime (
404    z_streamp strm,
405    int bits,
406    int value)
407{
408    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
409    strm->state->bi_valid = bits;
410    strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
411    return Z_OK;
412}
413
414/* ========================================================================= */
415int ZEXPORT deflateParams(
416    z_streamp strm,
417    int level,
418    int strategy)
419{
420    deflate_state *s;
421    compress_func func;
422    int err = Z_OK;
423
424    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
425    s = strm->state;
426
427#ifdef FASTEST
428    if (level != 0) level = 1;
429#else
430    if (level == Z_DEFAULT_COMPRESSION) level = 6;
431#endif
432    if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
433        return Z_STREAM_ERROR;
434    }
435    func = configuration_table[s->level].func;
436
437    if (func != configuration_table[level].func && strm->total_in != 0) {
438        /* Flush the last buffer: */
439        err = deflate(strm, Z_PARTIAL_FLUSH);
440    }
441    if (s->level != level) {
442        s->level = level;
443        s->max_lazy_match   = configuration_table[level].max_lazy;
444        s->good_match       = configuration_table[level].good_length;
445        s->nice_match       = configuration_table[level].nice_length;
446        s->max_chain_length = configuration_table[level].max_chain;
447    }
448    s->strategy = strategy;
449    return err;
450}
451
452/* ========================================================================= */
453int ZEXPORT deflateTune(
454    z_streamp strm,
455    int good_length,
456    int max_lazy,
457    int nice_length,
458    int max_chain)
459{
460    deflate_state *s;
461
462    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
463    s = strm->state;
464    s->good_match = good_length;
465    s->max_lazy_match = max_lazy;
466    s->nice_match = nice_length;
467    s->max_chain_length = max_chain;
468    return Z_OK;
469}
470
471/* =========================================================================
472 * For the default windowBits of 15 and memLevel of 8, this function returns
473 * a close to exact, as well as small, upper bound on the compressed size.
474 * They are coded as constants here for a reason--if the #define's are
475 * changed, then this function needs to be changed as well.  The return
476 * value for 15 and 8 only works for those exact settings.
477 *
478 * For any setting other than those defaults for windowBits and memLevel,
479 * the value returned is a conservative worst case for the maximum expansion
480 * resulting from using fixed blocks instead of stored blocks, which deflate
481 * can emit on compressed data for some combinations of the parameters.
482 *
483 * This function could be more sophisticated to provide closer upper bounds
484 * for every combination of windowBits and memLevel, as well as wrap.
485 * But even the conservative upper bound of about 14% expansion does not
486 * seem onerous for output buffer allocation.
487 */
488uLong ZEXPORT deflateBound(
489    z_streamp strm,
490    uLong sourceLen)
491{
492    deflate_state *s;
493    uLong destLen;
494
495    /* conservative upper bound */
496    destLen = sourceLen +
497              ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
498
499    /* if can't get parameters, return conservative bound */
500    if (strm == Z_NULL || strm->state == Z_NULL)
501        return destLen;
502
503    /* if not default parameters, return conservative bound */
504    s = strm->state;
505    if (s->w_bits != 15 || s->hash_bits != 8 + 7)
506        return destLen;
507
508    /* default settings: return tight bound for that case */
509    return compressBound(sourceLen);
510}
511
512/* =========================================================================
513 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
514 * IN assertion: the stream state is correct and there is enough room in
515 * pending_buf.
516 */
517local void putShortMSB (
518    deflate_state *s,
519    uInt b)
520{
521    put_byte(s, (Byte)(b >> 8));
522    put_byte(s, (Byte)(b & 0xff));
523}
524
525/* =========================================================================
526 * Flush as much pending output as possible. All deflate() output goes
527 * through this function so some applications may wish to modify it
528 * to avoid allocating a large strm->next_out buffer and copying into it.
529 * (See also read_buf()).
530 */
531local void flush_pending(
532    z_streamp strm)
533{
534    unsigned len = strm->state->pending;
535
536    if (len > strm->avail_out) len = strm->avail_out;
537    if (len == 0) return;
538
539    zmemcpy(strm->next_out, strm->state->pending_out, len);
540    strm->next_out  += len;
541    strm->state->pending_out  += len;
542    strm->total_out += len;
543    strm->avail_out  -= len;
544    strm->state->pending -= len;
545    if (strm->state->pending == 0) {
546        strm->state->pending_out = strm->state->pending_buf;
547    }
548}
549
550/* ========================================================================= */
551int ZEXPORT deflate (
552    z_streamp strm,
553    int flush)
554{
555    int old_flush; /* value of flush param for previous deflate call */
556    deflate_state *s;
557
558    if (strm == Z_NULL || strm->state == Z_NULL ||
559        flush > Z_FINISH || flush < 0) {
560        return Z_STREAM_ERROR;
561    }
562    s = strm->state;
563
564    if (strm->next_out == Z_NULL ||
565        (strm->next_in == Z_NULL && strm->avail_in != 0) ||
566        (s->status == FINISH_STATE && flush != Z_FINISH)) {
567        ERR_RETURN(strm, Z_STREAM_ERROR);
568    }
569    if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
570
571    s->strm = strm; /* just in case */
572    old_flush = s->last_flush;
573    s->last_flush = flush;
574
575    /* Write the header */
576    if (s->status == INIT_STATE) {
577#ifdef GZIP
578        if (s->wrap == 2) {
579            strm->adler = crc32(0L, Z_NULL, 0);
580            put_byte(s, 31);
581            put_byte(s, 139);
582            put_byte(s, 8);
583            if (s->gzhead == NULL) {
584                put_byte(s, 0);
585                put_byte(s, 0);
586                put_byte(s, 0);
587                put_byte(s, 0);
588                put_byte(s, 0);
589                put_byte(s, s->level == 9 ? 2 :
590                            (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
591                             4 : 0));
592                put_byte(s, OS_CODE);
593                s->status = BUSY_STATE;
594            }
595            else {
596                put_byte(s, (s->gzhead->text ? 1 : 0) +
597                            (s->gzhead->hcrc ? 2 : 0) +
598                            (s->gzhead->extra == Z_NULL ? 0 : 4) +
599                            (s->gzhead->name == Z_NULL ? 0 : 8) +
600                            (s->gzhead->comment == Z_NULL ? 0 : 16)
601                        );
602                put_byte(s, (Byte)(s->gzhead->time & 0xff));
603                put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
604                put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
605                put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
606                put_byte(s, s->level == 9 ? 2 :
607                            (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
608                             4 : 0));
609                put_byte(s, s->gzhead->os & 0xff);
610                if (s->gzhead->extra != NULL) {
611                    put_byte(s, s->gzhead->extra_len & 0xff);
612                    put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
613                }
614                if (s->gzhead->hcrc)
615                    strm->adler = crc32(strm->adler, s->pending_buf,
616                                        s->pending);
617                s->gzindex = 0;
618                s->status = EXTRA_STATE;
619            }
620        }
621        else
622#endif
623        {
624            uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
625            uInt level_flags;
626
627            if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
628                level_flags = 0;
629            else if (s->level < 6)
630                level_flags = 1;
631            else if (s->level == 6)
632                level_flags = 2;
633            else
634                level_flags = 3;
635            header |= (level_flags << 6);
636            if (s->strstart != 0) header |= PRESET_DICT;
637            header += 31 - (header % 31);
638
639            s->status = BUSY_STATE;
640            putShortMSB(s, header);
641
642            /* Save the adler32 of the preset dictionary: */
643            if (s->strstart != 0) {
644                putShortMSB(s, (uInt)(strm->adler >> 16));
645                putShortMSB(s, (uInt)(strm->adler & 0xffff));
646            }
647            strm->adler = adler32(0L, Z_NULL, 0);
648        }
649    }
650#ifdef GZIP
651    if (s->status == EXTRA_STATE) {
652        if (s->gzhead->extra != NULL) {
653            uInt beg = s->pending;  /* start of bytes to update crc */
654
655            while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
656                if (s->pending == s->pending_buf_size) {
657                    if (s->gzhead->hcrc && s->pending > beg)
658                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
659                                            s->pending - beg);
660                    flush_pending(strm);
661                    beg = s->pending;
662                    if (s->pending == s->pending_buf_size)
663                        break;
664                }
665                put_byte(s, s->gzhead->extra[s->gzindex]);
666                s->gzindex++;
667            }
668            if (s->gzhead->hcrc && s->pending > beg)
669                strm->adler = crc32(strm->adler, s->pending_buf + beg,
670                                    s->pending - beg);
671            if (s->gzindex == s->gzhead->extra_len) {
672                s->gzindex = 0;
673                s->status = NAME_STATE;
674            }
675        }
676        else
677            s->status = NAME_STATE;
678    }
679    if (s->status == NAME_STATE) {
680        if (s->gzhead->name != NULL) {
681            uInt beg = s->pending;  /* start of bytes to update crc */
682            int val;
683
684            do {
685                if (s->pending == s->pending_buf_size) {
686                    if (s->gzhead->hcrc && s->pending > beg)
687                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
688                                            s->pending - beg);
689                    flush_pending(strm);
690                    beg = s->pending;
691                    if (s->pending == s->pending_buf_size) {
692                        val = 1;
693                        break;
694                    }
695                }
696                val = s->gzhead->name[s->gzindex++];
697                put_byte(s, val);
698            } while (val != 0);
699            if (s->gzhead->hcrc && s->pending > beg)
700                strm->adler = crc32(strm->adler, s->pending_buf + beg,
701                                    s->pending - beg);
702            if (val == 0) {
703                s->gzindex = 0;
704                s->status = COMMENT_STATE;
705            }
706        }
707        else
708            s->status = COMMENT_STATE;
709    }
710    if (s->status == COMMENT_STATE) {
711        if (s->gzhead->comment != 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->comment[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->status = HCRC_STATE;
735        }
736        else
737            s->status = HCRC_STATE;
738    }
739    if (s->status == HCRC_STATE) {
740        if (s->gzhead->hcrc) {
741            if (s->pending + 2 > s->pending_buf_size)
742                flush_pending(strm);
743            if (s->pending + 2 <= s->pending_buf_size) {
744                put_byte(s, (Byte)(strm->adler & 0xff));
745                put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
746                strm->adler = crc32(0L, Z_NULL, 0);
747                s->status = BUSY_STATE;
748            }
749        }
750        else
751            s->status = BUSY_STATE;
752    }
753#endif
754
755    /* Flush as much pending output as possible */
756    if (s->pending != 0) {
757        flush_pending(strm);
758        if (strm->avail_out == 0) {
759            /* Since avail_out is 0, deflate will be called again with
760             * more output space, but possibly with both pending and
761             * avail_in equal to zero. There won't be anything to do,
762             * but this is not an error situation so make sure we
763             * return OK instead of BUF_ERROR at next call of deflate:
764             */
765            s->last_flush = -1;
766            return Z_OK;
767        }
768
769    /* Make sure there is something to do and avoid duplicate consecutive
770     * flushes. For repeated and useless calls with Z_FINISH, we keep
771     * returning Z_STREAM_END instead of Z_BUF_ERROR.
772     */
773    } else if (strm->avail_in == 0 && flush <= old_flush &&
774               flush != Z_FINISH) {
775        ERR_RETURN(strm, Z_BUF_ERROR);
776    }
777
778    /* User must not provide more input after the first FINISH: */
779    if (s->status == FINISH_STATE && strm->avail_in != 0) {
780        ERR_RETURN(strm, Z_BUF_ERROR);
781    }
782
783    /* Start a new block or continue the current one.
784     */
785    if (strm->avail_in != 0 || s->lookahead != 0 ||
786        (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
787        block_state bstate;
788
789        bstate = (*(configuration_table[s->level].func))(s, flush);
790
791        if (bstate == finish_started || bstate == finish_done) {
792            s->status = FINISH_STATE;
793        }
794        if (bstate == need_more || bstate == finish_started) {
795            if (strm->avail_out == 0) {
796                s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
797            }
798            return Z_OK;
799            /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
800             * of deflate should use the same flush parameter to make sure
801             * that the flush is complete. So we don't have to output an
802             * empty block here, this will be done at next call. This also
803             * ensures that for a very small output buffer, we emit at most
804             * one empty block.
805             */
806        }
807        if (bstate == block_done) {
808            if (flush == Z_PARTIAL_FLUSH) {
809                _tr_align(s);
810            } else { /* FULL_FLUSH or SYNC_FLUSH */
811                _tr_stored_block(s, (char*)0, 0L, 0);
812                /* For a full flush, this empty block will be recognized
813                 * as a special marker by inflate_sync().
814                 */
815                if (flush == Z_FULL_FLUSH) {
816                    CLEAR_HASH(s);             /* forget history */
817                }
818            }
819            flush_pending(strm);
820            if (strm->avail_out == 0) {
821              s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
822              return Z_OK;
823            }
824        }
825    }
826    Assert(strm->avail_out > 0, "bug2");
827
828    if (flush != Z_FINISH) return Z_OK;
829    if (s->wrap <= 0) return Z_STREAM_END;
830
831    /* Write the trailer */
832#ifdef GZIP
833    if (s->wrap == 2) {
834        put_byte(s, (Byte)(strm->adler & 0xff));
835        put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
836        put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
837        put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
838        put_byte(s, (Byte)(strm->total_in & 0xff));
839        put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
840        put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
841        put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
842    }
843    else
844#endif
845    {
846        putShortMSB(s, (uInt)(strm->adler >> 16));
847        putShortMSB(s, (uInt)(strm->adler & 0xffff));
848    }
849    flush_pending(strm);
850    /* If avail_out is zero, the application will call deflate again
851     * to flush the rest.
852     */
853    if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
854    return s->pending != 0 ? Z_OK : Z_STREAM_END;
855}
856
857/* ========================================================================= */
858int ZEXPORT deflateEnd (
859    z_streamp strm)
860{
861    int status;
862
863    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
864
865    status = strm->state->status;
866    if (status != INIT_STATE &&
867        status != EXTRA_STATE &&
868        status != NAME_STATE &&
869        status != COMMENT_STATE &&
870        status != HCRC_STATE &&
871        status != BUSY_STATE &&
872        status != FINISH_STATE) {
873      return Z_STREAM_ERROR;
874    }
875
876    /* Deallocate in reverse order of allocations: */
877    TRY_FREE(strm, strm->state->pending_buf);
878    TRY_FREE(strm, strm->state->head);
879    TRY_FREE(strm, strm->state->prev);
880    TRY_FREE(strm, strm->state->window);
881
882    ZFREE(strm, strm->state);
883    strm->state = Z_NULL;
884
885    return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
886}
887
888/* =========================================================================
889 * Copy the source state to the destination state.
890 * To simplify the source, this is not supported for 16-bit MSDOS (which
891 * doesn't have enough memory anyway to duplicate compression states).
892 */
893int ZEXPORT deflateCopy (
894    z_streamp dest,
895    z_streamp source)
896{
897#ifdef MAXSEG_64K
898    return Z_STREAM_ERROR;
899#else
900    deflate_state *ds;
901    deflate_state *ss;
902    ushf *overlay;
903
904
905    if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
906        return Z_STREAM_ERROR;
907    }
908
909    ss = source->state;
910
911    zmemcpy(dest, source, sizeof(z_stream));
912
913    ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
914    if (ds == Z_NULL) return Z_MEM_ERROR;
915    dest->state = (struct internal_state FAR *) ds;
916    zmemcpy(ds, ss, sizeof(deflate_state));
917    ds->strm = dest;
918
919    ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
920    ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
921    ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
922    overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
923    ds->pending_buf = (uchf *) overlay;
924
925    if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
926        ds->pending_buf == Z_NULL) {
927        deflateEnd (dest);
928        return Z_MEM_ERROR;
929    }
930    /* following zmemcpy do not work for 16-bit MSDOS */
931    zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
932    zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
933    zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
934    zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
935
936    ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
937    ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
938    ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
939
940    ds->l_desc.dyn_tree = ds->dyn_ltree;
941    ds->d_desc.dyn_tree = ds->dyn_dtree;
942    ds->bl_desc.dyn_tree = ds->bl_tree;
943
944    return Z_OK;
945#endif /* MAXSEG_64K */
946}
947
948/* ===========================================================================
949 * Read a new buffer from the current input stream, update the adler32
950 * and total number of bytes read.  All deflate() input goes through
951 * this function so some applications may wish to modify it to avoid
952 * allocating a large strm->next_in buffer and copying from it.
953 * (See also flush_pending()).
954 */
955local int read_buf(
956    z_streamp strm,
957    Bytef *buf,
958    unsigned size)
959{
960    unsigned len = strm->avail_in;
961
962    if (len > size) len = size;
963    if (len == 0) return 0;
964
965    strm->avail_in  -= len;
966
967    if (strm->state->wrap == 1) {
968        strm->adler = adler32(strm->adler, strm->next_in, len);
969    }
970#ifdef GZIP
971    else if (strm->state->wrap == 2) {
972        strm->adler = crc32(strm->adler, strm->next_in, len);
973    }
974#endif
975    zmemcpy(buf, strm->next_in, len);
976    strm->next_in  += len;
977    strm->total_in += len;
978
979    return (int)len;
980}
981
982/* ===========================================================================
983 * Initialize the "longest match" routines for a new zlib stream
984 */
985local void lm_init (
986    deflate_state *s)
987{
988    s->window_size = (ulg)2L*s->w_size;
989
990    CLEAR_HASH(s);
991
992    /* Set the default configuration parameters:
993     */
994    s->max_lazy_match   = configuration_table[s->level].max_lazy;
995    s->good_match       = configuration_table[s->level].good_length;
996    s->nice_match       = configuration_table[s->level].nice_length;
997    s->max_chain_length = configuration_table[s->level].max_chain;
998
999    s->strstart = 0;
1000    s->block_start = 0L;
1001    s->lookahead = 0;
1002    s->match_length = s->prev_length = MIN_MATCH-1;
1003    s->match_available = 0;
1004    s->ins_h = 0;
1005#ifndef FASTEST
1006#ifdef ASMV
1007    match_init(); /* initialize the asm code */
1008#endif
1009#endif
1010}
1011
1012#ifndef FASTEST
1013/* ===========================================================================
1014 * Set match_start to the longest match starting at the given string and
1015 * return its length. Matches shorter or equal to prev_length are discarded,
1016 * in which case the result is equal to prev_length and match_start is
1017 * garbage.
1018 * IN assertions: cur_match is the head of the hash chain for the current
1019 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1020 * OUT assertion: the match length is not greater than s->lookahead.
1021 */
1022#ifndef ASMV
1023/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1024 * match.S. The code will be functionally equivalent.
1025 */
1026local uInt longest_match(
1027    deflate_state *s,
1028    IPos cur_match)                             /* current match */
1029{
1030    unsigned chain_length = s->max_chain_length;/* max hash chain length */
1031    register Bytef *scan = s->window + s->strstart; /* current string */
1032    register Bytef *match;                       /* matched string */
1033    register int len;                           /* length of current match */
1034    int best_len = s->prev_length;              /* best match length so far */
1035    int nice_match = s->nice_match;             /* stop if match long enough */
1036    IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1037        s->strstart - (IPos)MAX_DIST(s) : NIL;
1038    /* Stop when cur_match becomes <= limit. To simplify the code,
1039     * we prevent matches with the string of window index 0.
1040     */
1041    Posf *prev = s->prev;
1042    uInt wmask = s->w_mask;
1043
1044#ifdef UNALIGNED_OK
1045    /* Compare two bytes at a time. Note: this is not always beneficial.
1046     * Try with and without -DUNALIGNED_OK to check.
1047     */
1048    register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1049    register ush scan_start = *(ushf*)scan;
1050    register ush scan_end   = *(ushf*)(scan+best_len-1);
1051#else
1052    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1053    register Byte scan_end1  = scan[best_len-1];
1054    register Byte scan_end   = scan[best_len];
1055#endif
1056
1057    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1058     * It is easy to get rid of this optimization if necessary.
1059     */
1060    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1061
1062    /* Do not waste too much time if we already have a good match: */
1063    if (s->prev_length >= s->good_match) {
1064        chain_length >>= 2;
1065    }
1066    /* Do not look for matches beyond the end of the input. This is necessary
1067     * to make deflate deterministic.
1068     */
1069    if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1070
1071    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1072
1073    do {
1074        Assert(cur_match < s->strstart, "no future");
1075        match = s->window + cur_match;
1076
1077        /* Skip to next match if the match length cannot increase
1078         * or if the match length is less than 2.  Note that the checks below
1079         * for insufficient lookahead only occur occasionally for performance
1080         * reasons.  Therefore uninitialized memory will be accessed, and
1081         * conditional jumps will be made that depend on those values.
1082         * However the length of the match is limited to the lookahead, so
1083         * the output of deflate is not affected by the uninitialized values.
1084         */
1085#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1086        /* This code assumes sizeof(unsigned short) == 2. Do not use
1087         * UNALIGNED_OK if your compiler uses a different size.
1088         */
1089        if (*(ushf*)(match+best_len-1) != scan_end ||
1090            *(ushf*)match != scan_start) continue;
1091
1092        /* It is not necessary to compare scan[2] and match[2] since they are
1093         * always equal when the other bytes match, given that the hash keys
1094         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1095         * strstart+3, +5, ... up to strstart+257. We check for insufficient
1096         * lookahead only every 4th comparison; the 128th check will be made
1097         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1098         * necessary to put more guard bytes at the end of the window, or
1099         * to check more often for insufficient lookahead.
1100         */
1101        Assert(scan[2] == match[2], "scan[2]?");
1102        scan++, match++;
1103        do {
1104        } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1105                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1106                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1107                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1108                 scan < strend);
1109        /* The funny "do {}" generates better code on most compilers */
1110
1111        /* Here, scan <= window+strstart+257 */
1112        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1113        if (*scan == *match) scan++;
1114
1115        len = (MAX_MATCH - 1) - (int)(strend-scan);
1116        scan = strend - (MAX_MATCH-1);
1117
1118#else /* UNALIGNED_OK */
1119
1120        if (match[best_len]   != scan_end  ||
1121            match[best_len-1] != scan_end1 ||
1122            *match            != *scan     ||
1123            *++match          != scan[1])      continue;
1124
1125        /* The check at best_len-1 can be removed because it will be made
1126         * again later. (This heuristic is not always a win.)
1127         * It is not necessary to compare scan[2] and match[2] since they
1128         * are always equal when the other bytes match, given that
1129         * the hash keys are equal and that HASH_BITS >= 8.
1130         */
1131        scan += 2, match++;
1132        Assert(*scan == *match, "match[2]?");
1133
1134        /* We check for insufficient lookahead only every 8th comparison;
1135         * the 256th check will be made at strstart+258.
1136         */
1137        do {
1138        } while (*++scan == *++match && *++scan == *++match &&
1139                 *++scan == *++match && *++scan == *++match &&
1140                 *++scan == *++match && *++scan == *++match &&
1141                 *++scan == *++match && *++scan == *++match &&
1142                 scan < strend);
1143
1144        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1145
1146        len = MAX_MATCH - (int)(strend - scan);
1147        scan = strend - MAX_MATCH;
1148
1149#endif /* UNALIGNED_OK */
1150
1151        if (len > best_len) {
1152            s->match_start = cur_match;
1153            best_len = len;
1154            if (len >= nice_match) break;
1155#ifdef UNALIGNED_OK
1156            scan_end = *(ushf*)(scan+best_len-1);
1157#else
1158            scan_end1  = scan[best_len-1];
1159            scan_end   = scan[best_len];
1160#endif
1161        }
1162    } while ((cur_match = prev[cur_match & wmask]) > limit
1163             && --chain_length != 0);
1164
1165    if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1166    return s->lookahead;
1167}
1168#endif /* ASMV */
1169#endif /* FASTEST */
1170
1171/* ---------------------------------------------------------------------------
1172 * Optimized version for level == 1 or strategy == Z_RLE only
1173 */
1174local uInt longest_match_fast(
1175    deflate_state *s,
1176    IPos cur_match)                             /* current match */
1177{
1178    register Bytef *scan = s->window + s->strstart; /* current string */
1179    register Bytef *match;                       /* matched string */
1180    register int len;                           /* length of current match */
1181    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1182
1183    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1184     * It is easy to get rid of this optimization if necessary.
1185     */
1186    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1187
1188    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1189
1190    Assert(cur_match < s->strstart, "no future");
1191
1192    match = s->window + cur_match;
1193
1194    /* Return failure if the match length is less than 2:
1195     */
1196    if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1197
1198    /* The check at best_len-1 can be removed because it will be made
1199     * again later. (This heuristic is not always a win.)
1200     * It is not necessary to compare scan[2] and match[2] since they
1201     * are always equal when the other bytes match, given that
1202     * the hash keys are equal and that HASH_BITS >= 8.
1203     */
1204    scan += 2, match += 2;
1205    Assert(*scan == *match, "match[2]?");
1206
1207    /* We check for insufficient lookahead only every 8th comparison;
1208     * the 256th check will be made at strstart+258.
1209     */
1210    do {
1211    } while (*++scan == *++match && *++scan == *++match &&
1212             *++scan == *++match && *++scan == *++match &&
1213             *++scan == *++match && *++scan == *++match &&
1214             *++scan == *++match && *++scan == *++match &&
1215             scan < strend);
1216
1217    Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1218
1219    len = MAX_MATCH - (int)(strend - scan);
1220
1221    if (len < MIN_MATCH) return MIN_MATCH - 1;
1222
1223    s->match_start = cur_match;
1224    return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1225}
1226
1227#ifdef DEBUG
1228/* ===========================================================================
1229 * Check that the match at match_start is indeed a match.
1230 */
1231local void check_match(
1232    deflate_state *s,
1233    IPos start, IPos match,
1234    int length)
1235{
1236    /* check that the match is indeed a match */
1237    if (zmemcmp(s->window + match,
1238                s->window + start, length) != EQUAL) {
1239        fprintf(stderr, " start %u, match %u, length %d\n",
1240                start, match, length);
1241        do {
1242            fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1243        } while (--length != 0);
1244        z_error("invalid match");
1245    }
1246    if (z_verbose > 1) {
1247        fprintf(stderr,"\\[%d,%d]", start-match, length);
1248        do { putc(s->window[start++], stderr); } while (--length != 0);
1249    }
1250}
1251#else
1252#  define check_match(s, start, match, length)
1253#endif /* DEBUG */
1254
1255/* ===========================================================================
1256 * Fill the window when the lookahead becomes insufficient.
1257 * Updates strstart and lookahead.
1258 *
1259 * IN assertion: lookahead < MIN_LOOKAHEAD
1260 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1261 *    At least one byte has been read, or avail_in == 0; reads are
1262 *    performed for at least two bytes (required for the zip translate_eol
1263 *    option -- not supported here).
1264 */
1265local void fill_window(
1266    deflate_state *s)
1267{
1268    register unsigned n, m;
1269    register Posf *p;
1270    unsigned more;    /* Amount of free space at the end of the window. */
1271    uInt wsize = s->w_size;
1272
1273    do {
1274        more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1275
1276        /* Deal with !@#$% 64K limit: */
1277        if (sizeof(int) <= 2) {
1278            if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1279                more = wsize;
1280
1281            } else if (more == (unsigned)(-1)) {
1282                /* Very unlikely, but possible on 16 bit machine if
1283                 * strstart == 0 && lookahead == 1 (input done a byte at time)
1284                 */
1285                more--;
1286            }
1287        }
1288
1289        /* If the window is almost full and there is insufficient lookahead,
1290         * move the upper half to the lower one to make room in the upper half.
1291         */
1292        if (s->strstart >= wsize+MAX_DIST(s)) {
1293
1294            zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1295            s->match_start -= wsize;
1296            s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
1297            s->block_start -= (long) wsize;
1298
1299            /* Slide the hash table (could be avoided with 32 bit values
1300               at the expense of memory usage). We slide even when level == 0
1301               to keep the hash table consistent if we switch back to level > 0
1302               later. (Using level 0 permanently is not an optimal usage of
1303               zlib, so we don't care about this pathological case.)
1304             */
1305            /* %%% avoid this when Z_RLE */
1306            n = s->hash_size;
1307            p = &s->head[n];
1308            do {
1309                m = *--p;
1310                *p = (Pos)(m >= wsize ? m-wsize : NIL);
1311            } while (--n);
1312
1313            n = wsize;
1314#ifndef FASTEST
1315            p = &s->prev[n];
1316            do {
1317                m = *--p;
1318                *p = (Pos)(m >= wsize ? m-wsize : NIL);
1319                /* If n is not on any hash chain, prev[n] is garbage but
1320                 * its value will never be used.
1321                 */
1322            } while (--n);
1323#endif
1324            more += wsize;
1325        }
1326        if (s->strm->avail_in == 0) return;
1327
1328        /* If there was no sliding:
1329         *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1330         *    more == window_size - lookahead - strstart
1331         * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1332         * => more >= window_size - 2*WSIZE + 2
1333         * In the BIG_MEM or MMAP case (not yet supported),
1334         *   window_size == input_size + MIN_LOOKAHEAD  &&
1335         *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1336         * Otherwise, window_size == 2*WSIZE so more >= 2.
1337         * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1338         */
1339        Assert(more >= 2, "more < 2");
1340
1341        n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1342        s->lookahead += n;
1343
1344        /* Initialize the hash value now that we have some input: */
1345        if (s->lookahead >= MIN_MATCH) {
1346            s->ins_h = s->window[s->strstart];
1347            UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1348#if MIN_MATCH != 3
1349            Call UPDATE_HASH() MIN_MATCH-3 more times
1350#endif
1351        }
1352        /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1353         * but this is not important since only literal bytes will be emitted.
1354         */
1355
1356    } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1357}
1358
1359/* ===========================================================================
1360 * Flush the current block, with given end-of-file flag.
1361 * IN assertion: strstart is set to the end of the current match.
1362 */
1363#define FLUSH_BLOCK_ONLY(s, eof) { \
1364   _tr_flush_block(s, (s->block_start >= 0L ? \
1365                   (charf *)&s->window[(unsigned)s->block_start] : \
1366                   (charf *)Z_NULL), \
1367                (ulg)((long)s->strstart - s->block_start), \
1368                (eof)); \
1369   s->block_start = s->strstart; \
1370   flush_pending(s->strm); \
1371   Tracev((stderr,"[FLUSH]")); \
1372}
1373
1374/* Same but force premature exit if necessary. */
1375#define FLUSH_BLOCK(s, eof) { \
1376   FLUSH_BLOCK_ONLY(s, eof); \
1377   if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1378}
1379
1380/* ===========================================================================
1381 * Copy without compression as much as possible from the input stream, return
1382 * the current block state.
1383 * This function does not insert new strings in the dictionary since
1384 * uncompressible data is probably not useful. This function is used
1385 * only for the level=0 compression option.
1386 * NOTE: this function should be optimized to avoid extra copying from
1387 * window to pending_buf.
1388 */
1389local block_state deflate_stored(
1390    deflate_state *s,
1391    int flush)
1392{
1393    /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1394     * to pending_buf_size, and each stored block has a 5 byte header:
1395     */
1396    ulg max_block_size = 0xffff;
1397    ulg max_start;
1398
1399    if (max_block_size > s->pending_buf_size - 5) {
1400        max_block_size = s->pending_buf_size - 5;
1401    }
1402
1403    /* Copy as much as possible from input to output: */
1404    for (;;) {
1405        /* Fill the window as much as possible: */
1406        if (s->lookahead <= 1) {
1407
1408            Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1409                   s->block_start >= (long)s->w_size, "slide too late");
1410
1411            fill_window(s);
1412            if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1413
1414            if (s->lookahead == 0) break; /* flush the current block */
1415        }
1416        Assert(s->block_start >= 0L, "block gone");
1417
1418        s->strstart += s->lookahead;
1419        s->lookahead = 0;
1420
1421        /* Emit a stored block if pending_buf will be full: */
1422        max_start = s->block_start + max_block_size;
1423        if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1424            /* strstart == 0 is possible when wraparound on 16-bit machine */
1425            s->lookahead = (uInt)(s->strstart - max_start);
1426            s->strstart = (uInt)max_start;
1427            FLUSH_BLOCK(s, 0);
1428        }
1429        /* Flush if we may have to slide, otherwise block_start may become
1430         * negative and the data will be gone:
1431         */
1432        if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1433            FLUSH_BLOCK(s, 0);
1434        }
1435    }
1436    FLUSH_BLOCK(s, flush == Z_FINISH);
1437    return flush == Z_FINISH ? finish_done : block_done;
1438}
1439
1440/* ===========================================================================
1441 * Compress as much as possible from the input stream, return the current
1442 * block state.
1443 * This function does not perform lazy evaluation of matches and inserts
1444 * new strings in the dictionary only for unmatched strings or for short
1445 * matches. It is used only for the fast compression options.
1446 */
1447local block_state deflate_fast(
1448    deflate_state *s,
1449    int flush)
1450{
1451    IPos hash_head = NIL; /* head of the hash chain */
1452    int bflush;           /* set if current block must be flushed */
1453
1454    for (;;) {
1455        /* Make sure that we always have enough lookahead, except
1456         * at the end of the input file. We need MAX_MATCH bytes
1457         * for the next match, plus MIN_MATCH bytes to insert the
1458         * string following the next match.
1459         */
1460        if (s->lookahead < MIN_LOOKAHEAD) {
1461            fill_window(s);
1462            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1463                return need_more;
1464            }
1465            if (s->lookahead == 0) break; /* flush the current block */
1466        }
1467
1468        /* Insert the string window[strstart .. strstart+2] in the
1469         * dictionary, and set hash_head to the head of the hash chain:
1470         */
1471        if (s->lookahead >= MIN_MATCH) {
1472            INSERT_STRING(s, s->strstart, hash_head);
1473        }
1474
1475        /* Find the longest match, discarding those <= prev_length.
1476         * At this point we have always match_length < MIN_MATCH
1477         */
1478        if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1479            /* To simplify the code, we prevent matches with the string
1480             * of window index 0 (in particular we have to avoid a match
1481             * of the string with itself at the start of the input file).
1482             */
1483#ifdef FASTEST
1484            if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) ||
1485                (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
1486                s->match_length = longest_match_fast (s, hash_head);
1487            }
1488#else
1489            if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1490                s->match_length = longest_match (s, hash_head);
1491            } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1492                s->match_length = longest_match_fast (s, hash_head);
1493            }
1494#endif
1495            /* longest_match() or longest_match_fast() sets match_start */
1496        }
1497        if (s->match_length >= MIN_MATCH) {
1498            check_match(s, s->strstart, s->match_start, s->match_length);
1499
1500            _tr_tally_dist(s, s->strstart - s->match_start,
1501                           s->match_length - MIN_MATCH, bflush);
1502
1503            s->lookahead -= s->match_length;
1504
1505            /* Insert new strings in the hash table only if the match length
1506             * is not too large. This saves time but degrades compression.
1507             */
1508#ifndef FASTEST
1509            if (s->match_length <= s->max_insert_length &&
1510                s->lookahead >= MIN_MATCH) {
1511                s->match_length--; /* string at strstart already in table */
1512                do {
1513                    s->strstart++;
1514                    INSERT_STRING(s, s->strstart, hash_head);
1515                    /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1516                     * always MIN_MATCH bytes ahead.
1517                     */
1518                } while (--s->match_length != 0);
1519                s->strstart++;
1520            } else
1521#endif
1522            {
1523                s->strstart += s->match_length;
1524                s->match_length = 0;
1525                s->ins_h = s->window[s->strstart];
1526                UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1527#if MIN_MATCH != 3
1528                Call UPDATE_HASH() MIN_MATCH-3 more times
1529#endif
1530                /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1531                 * matter since it will be recomputed at next deflate call.
1532                 */
1533            }
1534        } else {
1535            /* No match, output a literal byte */
1536            Tracevv((stderr,"%c", s->window[s->strstart]));
1537            _tr_tally_lit (s, s->window[s->strstart], bflush);
1538            s->lookahead--;
1539            s->strstart++;
1540        }
1541        if (bflush) FLUSH_BLOCK(s, 0);
1542    }
1543    FLUSH_BLOCK(s, flush == Z_FINISH);
1544    return flush == Z_FINISH ? finish_done : block_done;
1545}
1546
1547#ifndef FASTEST
1548/* ===========================================================================
1549 * Same as above, but achieves better compression. We use a lazy
1550 * evaluation for matches: a match is finally adopted only if there is
1551 * no better match at the next window position.
1552 */
1553local block_state deflate_slow(
1554    deflate_state *s,
1555    int flush)
1556{
1557    IPos hash_head = NIL;    /* head of hash chain */
1558    int bflush;              /* set if current block must be flushed */
1559
1560    /* Process the input block. */
1561    for (;;) {
1562        /* Make sure that we always have enough lookahead, except
1563         * at the end of the input file. We need MAX_MATCH bytes
1564         * for the next match, plus MIN_MATCH bytes to insert the
1565         * string following the next match.
1566         */
1567        if (s->lookahead < MIN_LOOKAHEAD) {
1568            fill_window(s);
1569            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1570                return need_more;
1571            }
1572            if (s->lookahead == 0) break; /* flush the current block */
1573        }
1574
1575        /* Insert the string window[strstart .. strstart+2] in the
1576         * dictionary, and set hash_head to the head of the hash chain:
1577         */
1578        if (s->lookahead >= MIN_MATCH) {
1579            INSERT_STRING(s, s->strstart, hash_head);
1580        }
1581
1582        /* Find the longest match, discarding those <= prev_length.
1583         */
1584        s->prev_length = s->match_length, s->prev_match = s->match_start;
1585        s->match_length = MIN_MATCH-1;
1586
1587        if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1588            s->strstart - hash_head <= MAX_DIST(s)) {
1589            /* To simplify the code, we prevent matches with the string
1590             * of window index 0 (in particular we have to avoid a match
1591             * of the string with itself at the start of the input file).
1592             */
1593            if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1594                s->match_length = longest_match (s, hash_head);
1595            } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1596                s->match_length = longest_match_fast (s, hash_head);
1597            }
1598            /* longest_match() or longest_match_fast() sets match_start */
1599
1600            if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1601#if TOO_FAR <= 32767
1602                || (s->match_length == MIN_MATCH &&
1603                    s->strstart - s->match_start > TOO_FAR)
1604#endif
1605                )) {
1606
1607                /* If prev_match is also MIN_MATCH, match_start is garbage
1608                 * but we will ignore the current match anyway.
1609                 */
1610                s->match_length = MIN_MATCH-1;
1611            }
1612        }
1613        /* If there was a match at the previous step and the current
1614         * match is not better, output the previous match:
1615         */
1616        if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1617            uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1618            /* Do not insert strings in hash table beyond this. */
1619
1620            check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1621
1622            _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1623                           s->prev_length - MIN_MATCH, bflush);
1624
1625            /* Insert in hash table all strings up to the end of the match.
1626             * strstart-1 and strstart are already inserted. If there is not
1627             * enough lookahead, the last two strings are not inserted in
1628             * the hash table.
1629             */
1630            s->lookahead -= s->prev_length-1;
1631            s->prev_length -= 2;
1632            do {
1633                if (++s->strstart <= max_insert) {
1634                    INSERT_STRING(s, s->strstart, hash_head);
1635                }
1636            } while (--s->prev_length != 0);
1637            s->match_available = 0;
1638            s->match_length = MIN_MATCH-1;
1639            s->strstart++;
1640
1641            if (bflush) FLUSH_BLOCK(s, 0);
1642
1643        } else if (s->match_available) {
1644            /* If there was no match at the previous position, output a
1645             * single literal. If there was a match but the current match
1646             * is longer, truncate the previous match to a single literal.
1647             */
1648            Tracevv((stderr,"%c", s->window[s->strstart-1]));
1649            _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1650            if (bflush) {
1651                FLUSH_BLOCK_ONLY(s, 0);
1652            }
1653            s->strstart++;
1654            s->lookahead--;
1655            if (s->strm->avail_out == 0) return need_more;
1656        } else {
1657            /* There is no previous match to compare with, wait for
1658             * the next step to decide.
1659             */
1660            s->match_available = 1;
1661            s->strstart++;
1662            s->lookahead--;
1663        }
1664    }
1665    Assert (flush != Z_NO_FLUSH, "no flush?");
1666    if (s->match_available) {
1667        Tracevv((stderr,"%c", s->window[s->strstart-1]));
1668        _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1669        s->match_available = 0;
1670    }
1671    FLUSH_BLOCK(s, flush == Z_FINISH);
1672    return flush == Z_FINISH ? finish_done : block_done;
1673}
1674#endif /* FASTEST */
1675
1676#if 0
1677/* ===========================================================================
1678 * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1679 * one.  Do not maintain a hash table.  (It will be regenerated if this run of
1680 * deflate switches away from Z_RLE.)
1681 */
1682local block_state deflate_rle(
1683    deflate_state *s,
1684    int flush)
1685{
1686    int bflush;         /* set if current block must be flushed */
1687    uInt run;           /* length of run */
1688    uInt max;           /* maximum length of run */
1689    uInt prev;          /* byte at distance one to match */
1690    Bytef *scan;        /* scan for end of run */
1691
1692    for (;;) {
1693        /* Make sure that we always have enough lookahead, except
1694         * at the end of the input file. We need MAX_MATCH bytes
1695         * for the longest encodable run.
1696         */
1697        if (s->lookahead < MAX_MATCH) {
1698            fill_window(s);
1699            if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {
1700                return need_more;
1701            }
1702            if (s->lookahead == 0) break; /* flush the current block */
1703        }
1704
1705        /* See how many times the previous byte repeats */
1706        run = 0;
1707        if (s->strstart > 0) {      /* if there is a previous byte, that is */
1708            max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH;
1709            scan = s->window + s->strstart - 1;
1710            prev = *scan++;
1711            do {
1712                if (*scan++ != prev)
1713                    break;
1714            } while (++run < max);
1715        }
1716
1717        /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1718        if (run >= MIN_MATCH) {
1719            check_match(s, s->strstart, s->strstart - 1, run);
1720            _tr_tally_dist(s, 1, run - MIN_MATCH, bflush);
1721            s->lookahead -= run;
1722            s->strstart += run;
1723        } else {
1724            /* No match, output a literal byte */
1725            Tracevv((stderr,"%c", s->window[s->strstart]));
1726            _tr_tally_lit (s, s->window[s->strstart], bflush);
1727            s->lookahead--;
1728            s->strstart++;
1729        }
1730        if (bflush) FLUSH_BLOCK(s, 0);
1731    }
1732    FLUSH_BLOCK(s, flush == Z_FINISH);
1733    return flush == Z_FINISH ? finish_done : block_done;
1734}
1735#endif
Note: See TracBrowser for help on using the repository browser.