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107 pj 1
/* deflate.c -- compress data using the deflation algorithm
2
 * Copyright (C) 1995-2002 Jean-loup Gailly.
3
 * For conditions of distribution and use, see copyright notice in zlib.h
4
 */
5
 
6
/*
7
 *  ALGORITHM
8
 *
9
 *      The "deflation" process depends on being able to identify portions
10
 *      of the input text which are identical to earlier input (within a
11
 *      sliding window trailing behind the input currently being processed).
12
 *
13
 *      The most straightforward technique turns out to be the fastest for
14
 *      most input files: try all possible matches and select the longest.
15
 *      The key feature of this algorithm is that insertions into the string
16
 *      dictionary are very simple and thus fast, and deletions are avoided
17
 *      completely. Insertions are performed at each input character, whereas
18
 *      string matches are performed only when the previous match ends. So it
19
 *      is preferable to spend more time in matches to allow very fast string
20
 *      insertions and avoid deletions. The matching algorithm for small
21
 *      strings is inspired from that of Rabin & Karp. A brute force approach
22
 *      is used to find longer strings when a small match has been found.
23
 *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
24
 *      (by Leonid Broukhis).
25
 *         A previous version of this file used a more sophisticated algorithm
26
 *      (by Fiala and Greene) which is guaranteed to run in linear amortized
27
 *      time, but has a larger average cost, uses more memory and is patented.
28
 *      However the F&G algorithm may be faster for some highly redundant
29
 *      files if the parameter max_chain_length (described below) is too large.
30
 *
31
 *  ACKNOWLEDGEMENTS
32
 *
33
 *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
34
 *      I found it in 'freeze' written by Leonid Broukhis.
35
 *      Thanks to many people for bug reports and testing.
36
 *
37
 *  REFERENCES
38
 *
39
 *      Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40
 *      Available in ftp://ds.internic.net/rfc/rfc1951.txt
41
 *
42
 *      A description of the Rabin and Karp algorithm is given in the book
43
 *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
44
 *
45
 *      Fiala,E.R., and Greene,D.H.
46
 *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
47
 *
48
 */
49
 
129 giacomo 50
/* @(#) $Id: deflate.c,v 1.2 2003-04-23 09:08:13 giacomo Exp $ */
107 pj 51
 
52
#include "deflate.h"
53
 
54
const char deflate_copyright[] =
55
   " deflate 1.1.4 Copyright 1995-2002 Jean-loup Gailly ";
56
/*
57
  If you use the zlib library in a product, an acknowledgment is welcome
58
  in the documentation of your product. If for some reason you cannot
59
  include such an acknowledgment, I would appreciate that you keep this
60
  copyright string in the executable of your product.
61
 */
62
 
63
/* ===========================================================================
64
 *  Function prototypes.
65
 */
66
typedef enum {
67
    need_more,      /* block not completed, need more input or more output */
68
    block_done,     /* block flush performed */
69
    finish_started, /* finish started, need only more output at next deflate */
70
    finish_done     /* finish done, accept no more input or output */
71
} block_state;
72
 
73
typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74
/* Compression function. Returns the block state after the call. */
75
 
76
local void fill_window    OF((deflate_state *s));
77
local block_state deflate_stored OF((deflate_state *s, int flush));
78
local block_state deflate_fast   OF((deflate_state *s, int flush));
79
local block_state deflate_slow   OF((deflate_state *s, int flush));
80
local void lm_init        OF((deflate_state *s));
81
local void putShortMSB    OF((deflate_state *s, uInt b));
82
local void flush_pending  OF((z_streamp strm));
83
local int read_buf        OF((z_streamp strm, Bytef *buf, unsigned size));
84
#ifdef ASMV
85
      void match_init OF((void)); /* asm code initialization */
86
      uInt longest_match  OF((deflate_state *s, IPos cur_match));
87
#else
88
local uInt longest_match  OF((deflate_state *s, IPos cur_match));
89
#endif
90
 
91
#ifdef DEBUG
92
local  void check_match OF((deflate_state *s, IPos start, IPos match,
93
                            int length));
94
#endif
95
 
96
/* ===========================================================================
97
 * Local data
98
 */
99
 
129 giacomo 100
#ifdef NIL
101
#undef NIL
102
#endif
103
 
107 pj 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
#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
113
/* Minimum amount of lookahead, except at the end of the input file.
114
 * See deflate.c for comments about the MIN_MATCH+1.
115
 */
116
 
117
/* Values for max_lazy_match, good_match and max_chain_length, depending on
118
 * the desired pack level (0..9). The values given below have been tuned to
119
 * exclude worst case performance for pathological files. Better values may be
120
 * found for specific files.
121
 */
122
typedef struct config_s {
123
   ush good_length; /* reduce lazy search above this match length */
124
   ush max_lazy;    /* do not perform lazy search above this match length */
125
   ush nice_length; /* quit search above this match length */
126
   ush max_chain;
127
   compress_func func;
128
} config;
129
 
130
local const config configuration_table[10] = {
131
/*      good lazy nice chain */
132
/* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
133
/* 1 */ {4,    4,  8,    4, deflate_fast}, /* maximum speed, no lazy matches */
134
/* 2 */ {4,    5, 16,    8, deflate_fast},
135
/* 3 */ {4,    6, 32,   32, deflate_fast},
136
 
137
/* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
138
/* 5 */ {8,   16, 32,   32, deflate_slow},
139
/* 6 */ {8,   16, 128, 128, deflate_slow},
140
/* 7 */ {8,   32, 128, 256, deflate_slow},
141
/* 8 */ {32, 128, 258, 1024, deflate_slow},
142
/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* maximum compression */
143
 
144
/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
145
 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
146
 * meaning.
147
 */
148
 
149
#define EQUAL 0
150
/* result of memcmp for equal strings */
151
 
152
struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
153
 
154
/* ===========================================================================
155
 * Update a hash value with the given input byte
156
 * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
157
 *    input characters, so that a running hash key can be computed from the
158
 *    previous key instead of complete recalculation each time.
159
 */
160
#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
161
 
162
 
163
/* ===========================================================================
164
 * Insert string str in the dictionary and set match_head to the previous head
165
 * of the hash chain (the most recent string with same hash key). Return
166
 * the previous length of the hash chain.
167
 * If this file is compiled with -DFASTEST, the compression level is forced
168
 * to 1, and no hash chains are maintained.
169
 * IN  assertion: all calls to to INSERT_STRING are made with consecutive
170
 *    input characters and the first MIN_MATCH bytes of str are valid
171
 *    (except for the last MIN_MATCH-1 bytes of the input file).
172
 */
173
#ifdef FASTEST
174
#define INSERT_STRING(s, str, match_head) \
175
   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
176
    match_head = s->head[s->ins_h], \
177
    s->head[s->ins_h] = (Pos)(str))
178
#else
179
#define INSERT_STRING(s, str, match_head) \
180
   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
181
    s->prev[(str) & s->w_mask] = match_head = s->head[s->ins_h], \
182
    s->head[s->ins_h] = (Pos)(str))
183
#endif
184
 
185
/* ===========================================================================
186
 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
187
 * prev[] will be initialized on the fly.
188
 */
189
#define CLEAR_HASH(s) \
190
    s->head[s->hash_size-1] = NIL; \
191
    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
192
 
193
/* ========================================================================= */
194
int ZEXPORT deflateInit_(strm, level, version, stream_size)
195
    z_streamp strm;
196
    int level;
197
    const char *version;
198
    int stream_size;
199
{
200
    return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
201
                         Z_DEFAULT_STRATEGY, version, stream_size);
202
    /* To do: ignore strm->next_in if we use it as window */
203
}
204
 
205
/* ========================================================================= */
206
int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
207
                  version, stream_size)
208
    z_streamp strm;
209
    int  level;
210
    int  method;
211
    int  windowBits;
212
    int  memLevel;
213
    int  strategy;
214
    const char *version;
215
    int stream_size;
216
{
217
    deflate_state *s;
218
    int noheader = 0;
219
    static const char* my_version = ZLIB_VERSION;
220
 
221
    ushf *overlay;
222
    /* We overlay pending_buf and d_buf+l_buf. This works since the average
223
     * output size for (length,distance) codes is <= 24 bits.
224
     */
225
 
226
    if (version == Z_NULL || version[0] != my_version[0] ||
227
        stream_size != sizeof(z_stream)) {
228
        return Z_VERSION_ERROR;
229
    }
230
    if (strm == Z_NULL) return Z_STREAM_ERROR;
231
 
232
    strm->msg = Z_NULL;
233
    if (strm->zalloc == Z_NULL) {
234
        strm->zalloc = zcalloc;
235
        strm->opaque = (voidpf)0;
236
    }
237
    if (strm->zfree == Z_NULL) strm->zfree = zcfree;
238
 
239
    if (level == Z_DEFAULT_COMPRESSION) level = 6;
240
#ifdef FASTEST
241
    level = 1;
242
#endif
243
 
244
    if (windowBits < 0) { /* undocumented feature: suppress zlib header */
245
        noheader = 1;
246
        windowBits = -windowBits;
247
    }
248
    if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
249
        windowBits < 9 || windowBits > 15 || level < 0 || level > 9 ||
250
        strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
251
        return Z_STREAM_ERROR;
252
    }
253
    s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
254
    if (s == Z_NULL) return Z_MEM_ERROR;
255
    strm->state = (struct internal_state FAR *)s;
256
    s->strm = strm;
257
 
258
    s->noheader = noheader;
259
    s->w_bits = windowBits;
260
    s->w_size = 1 << s->w_bits;
261
    s->w_mask = s->w_size - 1;
262
 
263
    s->hash_bits = memLevel + 7;
264
    s->hash_size = 1 << s->hash_bits;
265
    s->hash_mask = s->hash_size - 1;
266
    s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
267
 
268
    s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
269
    s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
270
    s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
271
 
272
    s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
273
 
274
    overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
275
    s->pending_buf = (uchf *) overlay;
276
    s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
277
 
278
    if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
279
        s->pending_buf == Z_NULL) {
280
        strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
281
        deflateEnd (strm);
282
        return Z_MEM_ERROR;
283
    }
284
    s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
285
    s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
286
 
287
    s->level = level;
288
    s->strategy = strategy;
289
    s->method = (Byte)method;
290
 
291
    return deflateReset(strm);
292
}
293
 
294
/* ========================================================================= */
295
int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
296
    z_streamp strm;
297
    const Bytef *dictionary;
298
    uInt  dictLength;
299
{
300
    deflate_state *s;
301
    uInt length = dictLength;
302
    uInt n;
303
    IPos hash_head = 0;
304
 
305
    if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
306
        strm->state->status != INIT_STATE) return Z_STREAM_ERROR;
307
 
308
    s = strm->state;
309
    strm->adler = adler32(strm->adler, dictionary, dictLength);
310
 
311
    if (length < MIN_MATCH) return Z_OK;
312
    if (length > MAX_DIST(s)) {
313
        length = MAX_DIST(s);
314
#ifndef USE_DICT_HEAD
315
        dictionary += dictLength - length; /* use the tail of the dictionary */
316
#endif
317
    }
318
    zmemcpy(s->window, dictionary, length);
319
    s->strstart = length;
320
    s->block_start = (long)length;
321
 
322
    /* Insert all strings in the hash table (except for the last two bytes).
323
     * s->lookahead stays null, so s->ins_h will be recomputed at the next
324
     * call of fill_window.
325
     */
326
    s->ins_h = s->window[0];
327
    UPDATE_HASH(s, s->ins_h, s->window[1]);
328
    for (n = 0; n <= length - MIN_MATCH; n++) {
329
        INSERT_STRING(s, n, hash_head);
330
    }
331
    if (hash_head) hash_head = 0;  /* to make compiler happy */
332
    return Z_OK;
333
}
334
 
335
/* ========================================================================= */
336
int ZEXPORT deflateReset (strm)
337
    z_streamp strm;
338
{
339
    deflate_state *s;
340
 
341
    if (strm == Z_NULL || strm->state == Z_NULL ||
342
        strm->zalloc == Z_NULL || strm->zfree == Z_NULL) return Z_STREAM_ERROR;
343
 
344
    strm->total_in = strm->total_out = 0;
345
    strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
346
    strm->data_type = Z_UNKNOWN;
347
 
348
    s = (deflate_state *)strm->state;
349
    s->pending = 0;
350
    s->pending_out = s->pending_buf;
351
 
352
    if (s->noheader < 0) {
353
        s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
354
    }
355
    s->status = s->noheader ? BUSY_STATE : INIT_STATE;
356
    strm->adler = 1;
357
    s->last_flush = Z_NO_FLUSH;
358
 
359
    _tr_init(s);
360
    lm_init(s);
361
 
362
    return Z_OK;
363
}
364
 
365
/* ========================================================================= */
366
int ZEXPORT deflateParams(strm, level, strategy)
367
    z_streamp strm;
368
    int level;
369
    int strategy;
370
{
371
    deflate_state *s;
372
    compress_func func;
373
    int err = Z_OK;
374
 
375
    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
376
    s = strm->state;
377
 
378
    if (level == Z_DEFAULT_COMPRESSION) {
379
        level = 6;
380
    }
381
    if (level < 0 || level > 9 || strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
382
        return Z_STREAM_ERROR;
383
    }
384
    func = configuration_table[s->level].func;
385
 
386
    if (func != configuration_table[level].func && strm->total_in != 0) {
387
        /* Flush the last buffer: */
388
        err = deflate(strm, Z_PARTIAL_FLUSH);
389
    }
390
    if (s->level != level) {
391
        s->level = level;
392
        s->max_lazy_match   = configuration_table[level].max_lazy;
393
        s->good_match       = configuration_table[level].good_length;
394
        s->nice_match       = configuration_table[level].nice_length;
395
        s->max_chain_length = configuration_table[level].max_chain;
396
    }
397
    s->strategy = strategy;
398
    return err;
399
}
400
 
401
/* =========================================================================
402
 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
403
 * IN assertion: the stream state is correct and there is enough room in
404
 * pending_buf.
405
 */
406
local void putShortMSB (s, b)
407
    deflate_state *s;
408
    uInt b;
409
{
410
    put_byte(s, (Byte)(b >> 8));
411
    put_byte(s, (Byte)(b & 0xff));
412
}  
413
 
414
/* =========================================================================
415
 * Flush as much pending output as possible. All deflate() output goes
416
 * through this function so some applications may wish to modify it
417
 * to avoid allocating a large strm->next_out buffer and copying into it.
418
 * (See also read_buf()).
419
 */
420
local void flush_pending(strm)
421
    z_streamp strm;
422
{
423
    unsigned len = strm->state->pending;
424
 
425
    if (len > strm->avail_out) len = strm->avail_out;
426
    if (len == 0) return;
427
 
428
    zmemcpy(strm->next_out, strm->state->pending_out, len);
429
    strm->next_out  += len;
430
    strm->state->pending_out  += len;
431
    strm->total_out += len;
432
    strm->avail_out  -= len;
433
    strm->state->pending -= len;
434
    if (strm->state->pending == 0) {
435
        strm->state->pending_out = strm->state->pending_buf;
436
    }
437
}
438
 
439
/* ========================================================================= */
440
int ZEXPORT deflate (strm, flush)
441
    z_streamp strm;
442
    int flush;
443
{
444
    int old_flush; /* value of flush param for previous deflate call */
445
    deflate_state *s;
446
 
447
    if (strm == Z_NULL || strm->state == Z_NULL ||
448
        flush > Z_FINISH || flush < 0) {
449
        return Z_STREAM_ERROR;
450
    }
451
    s = strm->state;
452
 
453
    if (strm->next_out == Z_NULL ||
454
        (strm->next_in == Z_NULL && strm->avail_in != 0) ||
455
        (s->status == FINISH_STATE && flush != Z_FINISH)) {
456
        ERR_RETURN(strm, Z_STREAM_ERROR);
457
    }
458
    if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
459
 
460
    s->strm = strm; /* just in case */
461
    old_flush = s->last_flush;
462
    s->last_flush = flush;
463
 
464
    /* Write the zlib header */
465
    if (s->status == INIT_STATE) {
466
 
467
        uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
468
        uInt level_flags = (s->level-1) >> 1;
469
 
470
        if (level_flags > 3) level_flags = 3;
471
        header |= (level_flags << 6);
472
        if (s->strstart != 0) header |= PRESET_DICT;
473
        header += 31 - (header % 31);
474
 
475
        s->status = BUSY_STATE;
476
        putShortMSB(s, header);
477
 
478
        /* Save the adler32 of the preset dictionary: */
479
        if (s->strstart != 0) {
480
            putShortMSB(s, (uInt)(strm->adler >> 16));
481
            putShortMSB(s, (uInt)(strm->adler & 0xffff));
482
        }
483
        strm->adler = 1L;
484
    }
485
 
486
    /* Flush as much pending output as possible */
487
    if (s->pending != 0) {
488
        flush_pending(strm);
489
        if (strm->avail_out == 0) {
490
            /* Since avail_out is 0, deflate will be called again with
491
             * more output space, but possibly with both pending and
492
             * avail_in equal to zero. There won't be anything to do,
493
             * but this is not an error situation so make sure we
494
             * return OK instead of BUF_ERROR at next call of deflate:
495
             */
496
            s->last_flush = -1;
497
            return Z_OK;
498
        }
499
 
500
    /* Make sure there is something to do and avoid duplicate consecutive
501
     * flushes. For repeated and useless calls with Z_FINISH, we keep
502
     * returning Z_STREAM_END instead of Z_BUFF_ERROR.
503
     */
504
    } else if (strm->avail_in == 0 && flush <= old_flush &&
505
               flush != Z_FINISH) {
506
        ERR_RETURN(strm, Z_BUF_ERROR);
507
    }
508
 
509
    /* User must not provide more input after the first FINISH: */
510
    if (s->status == FINISH_STATE && strm->avail_in != 0) {
511
        ERR_RETURN(strm, Z_BUF_ERROR);
512
    }
513
 
514
    /* Start a new block or continue the current one.
515
     */
516
    if (strm->avail_in != 0 || s->lookahead != 0 ||
517
        (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
518
        block_state bstate;
519
 
520
        bstate = (*(configuration_table[s->level].func))(s, flush);
521
 
522
        if (bstate == finish_started || bstate == finish_done) {
523
            s->status = FINISH_STATE;
524
        }
525
        if (bstate == need_more || bstate == finish_started) {
526
            if (strm->avail_out == 0) {
527
                s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
528
            }
529
            return Z_OK;
530
            /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
531
             * of deflate should use the same flush parameter to make sure
532
             * that the flush is complete. So we don't have to output an
533
             * empty block here, this will be done at next call. This also
534
             * ensures that for a very small output buffer, we emit at most
535
             * one empty block.
536
             */
537
        }
538
        if (bstate == block_done) {
539
            if (flush == Z_PARTIAL_FLUSH) {
540
                _tr_align(s);
541
            } else { /* FULL_FLUSH or SYNC_FLUSH */
542
                _tr_stored_block(s, (char*)0, 0L, 0);
543
                /* For a full flush, this empty block will be recognized
544
                 * as a special marker by inflate_sync().
545
                 */
546
                if (flush == Z_FULL_FLUSH) {
547
                    CLEAR_HASH(s);             /* forget history */
548
                }
549
            }
550
            flush_pending(strm);
551
            if (strm->avail_out == 0) {
552
              s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
553
              return Z_OK;
554
            }
555
        }
556
    }
557
    Assert(strm->avail_out > 0, "bug2");
558
 
559
    if (flush != Z_FINISH) return Z_OK;
560
    if (s->noheader) return Z_STREAM_END;
561
 
562
    /* Write the zlib trailer (adler32) */
563
    putShortMSB(s, (uInt)(strm->adler >> 16));
564
    putShortMSB(s, (uInt)(strm->adler & 0xffff));
565
    flush_pending(strm);
566
    /* If avail_out is zero, the application will call deflate again
567
     * to flush the rest.
568
     */
569
    s->noheader = -1; /* write the trailer only once! */
570
    return s->pending != 0 ? Z_OK : Z_STREAM_END;
571
}
572
 
573
/* ========================================================================= */
574
int ZEXPORT deflateEnd (strm)
575
    z_streamp strm;
576
{
577
    int status;
578
 
579
    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
580
 
581
    status = strm->state->status;
582
    if (status != INIT_STATE && status != BUSY_STATE &&
583
        status != FINISH_STATE) {
584
      return Z_STREAM_ERROR;
585
    }
586
 
587
    /* Deallocate in reverse order of allocations: */
588
    TRY_FREE(strm, strm->state->pending_buf);
589
    TRY_FREE(strm, strm->state->head);
590
    TRY_FREE(strm, strm->state->prev);
591
    TRY_FREE(strm, strm->state->window);
592
 
593
    ZFREE(strm, strm->state);
594
    strm->state = Z_NULL;
595
 
596
    return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
597
}
598
 
599
/* =========================================================================
600
 * Copy the source state to the destination state.
601
 * To simplify the source, this is not supported for 16-bit MSDOS (which
602
 * doesn't have enough memory anyway to duplicate compression states).
603
 */
604
int ZEXPORT deflateCopy (dest, source)
605
    z_streamp dest;
606
    z_streamp source;
607
{
608
#ifdef MAXSEG_64K
609
    return Z_STREAM_ERROR;
610
#else
611
    deflate_state *ds;
612
    deflate_state *ss;
613
    ushf *overlay;
614
 
615
 
616
    if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
617
        return Z_STREAM_ERROR;
618
    }
619
 
620
    ss = source->state;
621
 
622
    *dest = *source;
623
 
624
    ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
625
    if (ds == Z_NULL) return Z_MEM_ERROR;
626
    dest->state = (struct internal_state FAR *) ds;
627
    *ds = *ss;
628
    ds->strm = dest;
629
 
630
    ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
631
    ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
632
    ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
633
    overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
634
    ds->pending_buf = (uchf *) overlay;
635
 
636
    if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
637
        ds->pending_buf == Z_NULL) {
638
        deflateEnd (dest);
639
        return Z_MEM_ERROR;
640
    }
641
    /* following zmemcpy do not work for 16-bit MSDOS */
642
    zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
643
    zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
644
    zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
645
    zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
646
 
647
    ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
648
    ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
649
    ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
650
 
651
    ds->l_desc.dyn_tree = ds->dyn_ltree;
652
    ds->d_desc.dyn_tree = ds->dyn_dtree;
653
    ds->bl_desc.dyn_tree = ds->bl_tree;
654
 
655
    return Z_OK;
656
#endif
657
}
658
 
659
/* ===========================================================================
660
 * Read a new buffer from the current input stream, update the adler32
661
 * and total number of bytes read.  All deflate() input goes through
662
 * this function so some applications may wish to modify it to avoid
663
 * allocating a large strm->next_in buffer and copying from it.
664
 * (See also flush_pending()).
665
 */
666
local int read_buf(strm, buf, size)
667
    z_streamp strm;
668
    Bytef *buf;
669
    unsigned size;
670
{
671
    unsigned len = strm->avail_in;
672
 
673
    if (len > size) len = size;
674
    if (len == 0) return 0;
675
 
676
    strm->avail_in  -= len;
677
 
678
    if (!strm->state->noheader) {
679
        strm->adler = adler32(strm->adler, strm->next_in, len);
680
    }
681
    zmemcpy(buf, strm->next_in, len);
682
    strm->next_in  += len;
683
    strm->total_in += len;
684
 
685
    return (int)len;
686
}
687
 
688
/* ===========================================================================
689
 * Initialize the "longest match" routines for a new zlib stream
690
 */
691
local void lm_init (s)
692
    deflate_state *s;
693
{
694
    s->window_size = (ulg)2L*s->w_size;
695
 
696
    CLEAR_HASH(s);
697
 
698
    /* Set the default configuration parameters:
699
     */
700
    s->max_lazy_match   = configuration_table[s->level].max_lazy;
701
    s->good_match       = configuration_table[s->level].good_length;
702
    s->nice_match       = configuration_table[s->level].nice_length;
703
    s->max_chain_length = configuration_table[s->level].max_chain;
704
 
705
    s->strstart = 0;
706
    s->block_start = 0L;
707
    s->lookahead = 0;
708
    s->match_length = s->prev_length = MIN_MATCH-1;
709
    s->match_available = 0;
710
    s->ins_h = 0;
711
#ifdef ASMV
712
    match_init(); /* initialize the asm code */
713
#endif
714
}
715
 
716
/* ===========================================================================
717
 * Set match_start to the longest match starting at the given string and
718
 * return its length. Matches shorter or equal to prev_length are discarded,
719
 * in which case the result is equal to prev_length and match_start is
720
 * garbage.
721
 * IN assertions: cur_match is the head of the hash chain for the current
722
 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
723
 * OUT assertion: the match length is not greater than s->lookahead.
724
 */
725
#ifndef ASMV
726
/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
727
 * match.S. The code will be functionally equivalent.
728
 */
729
#ifndef FASTEST
730
local uInt longest_match(s, cur_match)
731
    deflate_state *s;
732
    IPos cur_match;                             /* current match */
733
{
734
    unsigned chain_length = s->max_chain_length;/* max hash chain length */
735
    register Bytef *scan = s->window + s->strstart; /* current string */
736
    register Bytef *match;                       /* matched string */
737
    register int len;                           /* length of current match */
738
    int best_len = s->prev_length;              /* best match length so far */
739
    int nice_match = s->nice_match;             /* stop if match long enough */
740
    IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
741
        s->strstart - (IPos)MAX_DIST(s) : NIL;
742
    /* Stop when cur_match becomes <= limit. To simplify the code,
743
     * we prevent matches with the string of window index 0.
744
     */
745
    Posf *prev = s->prev;
746
    uInt wmask = s->w_mask;
747
 
748
#ifdef UNALIGNED_OK
749
    /* Compare two bytes at a time. Note: this is not always beneficial.
750
     * Try with and without -DUNALIGNED_OK to check.
751
     */
752
    register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
753
    register ush scan_start = *(ushf*)scan;
754
    register ush scan_end   = *(ushf*)(scan+best_len-1);
755
#else
756
    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
757
    register Byte scan_end1  = scan[best_len-1];
758
    register Byte scan_end   = scan[best_len];
759
#endif
760
 
761
    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
762
     * It is easy to get rid of this optimization if necessary.
763
     */
764
    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
765
 
766
    /* Do not waste too much time if we already have a good match: */
767
    if (s->prev_length >= s->good_match) {
768
        chain_length >>= 2;
769
    }
770
    /* Do not look for matches beyond the end of the input. This is necessary
771
     * to make deflate deterministic.
772
     */
773
    if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
774
 
775
    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
776
 
777
    do {
778
        Assert(cur_match < s->strstart, "no future");
779
        match = s->window + cur_match;
780
 
781
        /* Skip to next match if the match length cannot increase
782
         * or if the match length is less than 2:
783
         */
784
#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
785
        /* This code assumes sizeof(unsigned short) == 2. Do not use
786
         * UNALIGNED_OK if your compiler uses a different size.
787
         */
788
        if (*(ushf*)(match+best_len-1) != scan_end ||
789
            *(ushf*)match != scan_start) continue;
790
 
791
        /* It is not necessary to compare scan[2] and match[2] since they are
792
         * always equal when the other bytes match, given that the hash keys
793
         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
794
         * strstart+3, +5, ... up to strstart+257. We check for insufficient
795
         * lookahead only every 4th comparison; the 128th check will be made
796
         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
797
         * necessary to put more guard bytes at the end of the window, or
798
         * to check more often for insufficient lookahead.
799
         */
800
        Assert(scan[2] == match[2], "scan[2]?");
801
        scan++, match++;
802
        do {
803
        } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
804
                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
805
                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
806
                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
807
                 scan < strend);
808
        /* The funny "do {}" generates better code on most compilers */
809
 
810
        /* Here, scan <= window+strstart+257 */
811
        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
812
        if (*scan == *match) scan++;
813
 
814
        len = (MAX_MATCH - 1) - (int)(strend-scan);
815
        scan = strend - (MAX_MATCH-1);
816
 
817
#else /* UNALIGNED_OK */
818
 
819
        if (match[best_len]   != scan_end  ||
820
            match[best_len-1] != scan_end1 ||
821
            *match            != *scan     ||
822
            *++match          != scan[1])      continue;
823
 
824
        /* The check at best_len-1 can be removed because it will be made
825
         * again later. (This heuristic is not always a win.)
826
         * It is not necessary to compare scan[2] and match[2] since they
827
         * are always equal when the other bytes match, given that
828
         * the hash keys are equal and that HASH_BITS >= 8.
829
         */
830
        scan += 2, match++;
831
        Assert(*scan == *match, "match[2]?");
832
 
833
        /* We check for insufficient lookahead only every 8th comparison;
834
         * the 256th check will be made at strstart+258.
835
         */
836
        do {
837
        } while (*++scan == *++match && *++scan == *++match &&
838
                 *++scan == *++match && *++scan == *++match &&
839
                 *++scan == *++match && *++scan == *++match &&
840
                 *++scan == *++match && *++scan == *++match &&
841
                 scan < strend);
842
 
843
        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
844
 
845
        len = MAX_MATCH - (int)(strend - scan);
846
        scan = strend - MAX_MATCH;
847
 
848
#endif /* UNALIGNED_OK */
849
 
850
        if (len > best_len) {
851
            s->match_start = cur_match;
852
            best_len = len;
853
            if (len >= nice_match) break;
854
#ifdef UNALIGNED_OK
855
            scan_end = *(ushf*)(scan+best_len-1);
856
#else
857
            scan_end1  = scan[best_len-1];
858
            scan_end   = scan[best_len];
859
#endif
860
        }
861
    } while ((cur_match = prev[cur_match & wmask]) > limit
862
             && --chain_length != 0);
863
 
864
    if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
865
    return s->lookahead;
866
}
867
 
868
#else /* FASTEST */
869
/* ---------------------------------------------------------------------------
870
 * Optimized version for level == 1 only
871
 */
872
local uInt longest_match(s, cur_match)
873
    deflate_state *s;
874
    IPos cur_match;                             /* current match */
875
{
876
    register Bytef *scan = s->window + s->strstart; /* current string */
877
    register Bytef *match;                       /* matched string */
878
    register int len;                           /* length of current match */
879
    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
880
 
881
    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
882
     * It is easy to get rid of this optimization if necessary.
883
     */
884
    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
885
 
886
    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
887
 
888
    Assert(cur_match < s->strstart, "no future");
889
 
890
    match = s->window + cur_match;
891
 
892
    /* Return failure if the match length is less than 2:
893
     */
894
    if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
895
 
896
    /* The check at best_len-1 can be removed because it will be made
897
     * again later. (This heuristic is not always a win.)
898
     * It is not necessary to compare scan[2] and match[2] since they
899
     * are always equal when the other bytes match, given that
900
     * the hash keys are equal and that HASH_BITS >= 8.
901
     */
902
    scan += 2, match += 2;
903
    Assert(*scan == *match, "match[2]?");
904
 
905
    /* We check for insufficient lookahead only every 8th comparison;
906
     * the 256th check will be made at strstart+258.
907
     */
908
    do {
909
    } while (*++scan == *++match && *++scan == *++match &&
910
             *++scan == *++match && *++scan == *++match &&
911
             *++scan == *++match && *++scan == *++match &&
912
             *++scan == *++match && *++scan == *++match &&
913
             scan < strend);
914
 
915
    Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
916
 
917
    len = MAX_MATCH - (int)(strend - scan);
918
 
919
    if (len < MIN_MATCH) return MIN_MATCH - 1;
920
 
921
    s->match_start = cur_match;
922
    return len <= s->lookahead ? len : s->lookahead;
923
}
924
#endif /* FASTEST */
925
#endif /* ASMV */
926
 
927
#ifdef DEBUG
928
/* ===========================================================================
929
 * Check that the match at match_start is indeed a match.
930
 */
931
local void check_match(s, start, match, length)
932
    deflate_state *s;
933
    IPos start, match;
934
    int length;
935
{
936
    /* check that the match is indeed a match */
937
    if (zmemcmp(s->window + match,
938
                s->window + start, length) != EQUAL) {
939
        cprintf(" start %u, match %u, length %d\n",
940
                start, match, length);
941
        do {
942
            cprintf("%c%c", s->window[match++], s->window[start++]);
943
        } while (--length != 0);
944
        z_error("invalid match");
945
    }
946
    if (z_verbose > 1) {
947
        cprintf("\\[%d,%d]", start-match, length);
948
        do { putc(s->window[start++], stderr); } while (--length != 0);
949
    }
950
}
951
#else
952
#  define check_match(s, start, match, length)
953
#endif
954
 
955
/* ===========================================================================
956
 * Fill the window when the lookahead becomes insufficient.
957
 * Updates strstart and lookahead.
958
 *
959
 * IN assertion: lookahead < MIN_LOOKAHEAD
960
 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
961
 *    At least one byte has been read, or avail_in == 0; reads are
962
 *    performed for at least two bytes (required for the zip translate_eol
963
 *    option -- not supported here).
964
 */
965
local void fill_window(s)
966
    deflate_state *s;
967
{
968
    register unsigned n, m;
969
    register Posf *p;
970
    unsigned more;    /* Amount of free space at the end of the window. */
971
    uInt wsize = s->w_size;
972
 
973
    do {
974
        more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
975
 
976
        /* Deal with !@#$% 64K limit: */
977
        if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
978
            more = wsize;
979
 
980
        } else if (more == (unsigned)(-1)) {
981
            /* Very unlikely, but possible on 16 bit machine if strstart == 0
982
             * and lookahead == 1 (input done one byte at time)
983
             */
984
            more--;
985
 
986
        /* If the window is almost full and there is insufficient lookahead,
987
         * move the upper half to the lower one to make room in the upper half.
988
         */
989
        } else if (s->strstart >= wsize+MAX_DIST(s)) {
990
 
991
            zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
992
            s->match_start -= wsize;
993
            s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
994
            s->block_start -= (long) wsize;
995
 
996
            /* Slide the hash table (could be avoided with 32 bit values
997
               at the expense of memory usage). We slide even when level == 0
998
               to keep the hash table consistent if we switch back to level > 0
999
               later. (Using level 0 permanently is not an optimal usage of
1000
               zlib, so we don't care about this pathological case.)
1001
             */
1002
            n = s->hash_size;
1003
            p = &s->head[n];
1004
            do {
1005
                m = *--p;
1006
                *p = (Pos)(m >= wsize ? m-wsize : NIL);
1007
            } while (--n);
1008
 
1009
            n = wsize;
1010
#ifndef FASTEST
1011
            p = &s->prev[n];
1012
            do {
1013
                m = *--p;
1014
                *p = (Pos)(m >= wsize ? m-wsize : NIL);
1015
                /* If n is not on any hash chain, prev[n] is garbage but
1016
                 * its value will never be used.
1017
                 */
1018
            } while (--n);
1019
#endif
1020
            more += wsize;
1021
        }
1022
        if (s->strm->avail_in == 0) return;
1023
 
1024
        /* If there was no sliding:
1025
         *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1026
         *    more == window_size - lookahead - strstart
1027
         * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1028
         * => more >= window_size - 2*WSIZE + 2
1029
         * In the BIG_MEM or MMAP case (not yet supported),
1030
         *   window_size == input_size + MIN_LOOKAHEAD  &&
1031
         *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1032
         * Otherwise, window_size == 2*WSIZE so more >= 2.
1033
         * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1034
         */
1035
        Assert(more >= 2, "more < 2");
1036
 
1037
        n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1038
        s->lookahead += n;
1039
 
1040
        /* Initialize the hash value now that we have some input: */
1041
        if (s->lookahead >= MIN_MATCH) {
1042
            s->ins_h = s->window[s->strstart];
1043
            UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1044
#if MIN_MATCH != 3
1045
            Call UPDATE_HASH() MIN_MATCH-3 more times
1046
#endif
1047
        }
1048
        /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1049
         * but this is not important since only literal bytes will be emitted.
1050
         */
1051
 
1052
    } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1053
}
1054
 
1055
/* ===========================================================================
1056
 * Flush the current block, with given end-of-file flag.
1057
 * IN assertion: strstart is set to the end of the current match.
1058
 */
1059
#define FLUSH_BLOCK_ONLY(s, eof) { \
1060
   _tr_flush_block(s, (s->block_start >= 0L ? \
1061
                   (charf *)&s->window[(unsigned)s->block_start] : \
1062
                   (charf *)Z_NULL), \
1063
                (ulg)((long)s->strstart - s->block_start), \
1064
                (eof)); \
1065
   s->block_start = s->strstart; \
1066
   flush_pending(s->strm); \
1067
   Tracev((stderr,"[FLUSH]")); \
1068
}
1069
 
1070
/* Same but force premature exit if necessary. */
1071
#define FLUSH_BLOCK(s, eof) { \
1072
   FLUSH_BLOCK_ONLY(s, eof); \
1073
   if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1074
}
1075
 
1076
/* ===========================================================================
1077
 * Copy without compression as much as possible from the input stream, return
1078
 * the current block state.
1079
 * This function does not insert new strings in the dictionary since
1080
 * uncompressible data is probably not useful. This function is used
1081
 * only for the level=0 compression option.
1082
 * NOTE: this function should be optimized to avoid extra copying from
1083
 * window to pending_buf.
1084
 */
1085
local block_state deflate_stored(s, flush)
1086
    deflate_state *s;
1087
    int flush;
1088
{
1089
    /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1090
     * to pending_buf_size, and each stored block has a 5 byte header:
1091
     */
1092
    ulg max_block_size = 0xffff;
1093
    ulg max_start;
1094
 
1095
    if (max_block_size > s->pending_buf_size - 5) {
1096
        max_block_size = s->pending_buf_size - 5;
1097
    }
1098
 
1099
    /* Copy as much as possible from input to output: */
1100
    for (;;) {
1101
        /* Fill the window as much as possible: */
1102
        if (s->lookahead <= 1) {
1103
 
1104
            Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1105
                   s->block_start >= (long)s->w_size, "slide too late");
1106
 
1107
            fill_window(s);
1108
            if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1109
 
1110
            if (s->lookahead == 0) break; /* flush the current block */
1111
        }
1112
        Assert(s->block_start >= 0L, "block gone");
1113
 
1114
        s->strstart += s->lookahead;
1115
        s->lookahead = 0;
1116
 
1117
        /* Emit a stored block if pending_buf will be full: */
1118
        max_start = s->block_start + max_block_size;
1119
        if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1120
            /* strstart == 0 is possible when wraparound on 16-bit machine */
1121
            s->lookahead = (uInt)(s->strstart - max_start);
1122
            s->strstart = (uInt)max_start;
1123
            FLUSH_BLOCK(s, 0);
1124
        }
1125
        /* Flush if we may have to slide, otherwise block_start may become
1126
         * negative and the data will be gone:
1127
         */
1128
        if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1129
            FLUSH_BLOCK(s, 0);
1130
        }
1131
    }
1132
    FLUSH_BLOCK(s, flush == Z_FINISH);
1133
    return flush == Z_FINISH ? finish_done : block_done;
1134
}
1135
 
1136
/* ===========================================================================
1137
 * Compress as much as possible from the input stream, return the current
1138
 * block state.
1139
 * This function does not perform lazy evaluation of matches and inserts
1140
 * new strings in the dictionary only for unmatched strings or for short
1141
 * matches. It is used only for the fast compression options.
1142
 */
1143
local block_state deflate_fast(s, flush)
1144
    deflate_state *s;
1145
    int flush;
1146
{
1147
    IPos hash_head = NIL; /* head of the hash chain */
1148
    int bflush;           /* set if current block must be flushed */
1149
 
1150
    for (;;) {
1151
        /* Make sure that we always have enough lookahead, except
1152
         * at the end of the input file. We need MAX_MATCH bytes
1153
         * for the next match, plus MIN_MATCH bytes to insert the
1154
         * string following the next match.
1155
         */
1156
        if (s->lookahead < MIN_LOOKAHEAD) {
1157
            fill_window(s);
1158
            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1159
                return need_more;
1160
            }
1161
            if (s->lookahead == 0) break; /* flush the current block */
1162
        }
1163
 
1164
        /* Insert the string window[strstart .. strstart+2] in the
1165
         * dictionary, and set hash_head to the head of the hash chain:
1166
         */
1167
        if (s->lookahead >= MIN_MATCH) {
1168
            INSERT_STRING(s, s->strstart, hash_head);
1169
        }
1170
 
1171
        /* Find the longest match, discarding those <= prev_length.
1172
         * At this point we have always match_length < MIN_MATCH
1173
         */
1174
        if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1175
            /* To simplify the code, we prevent matches with the string
1176
             * of window index 0 (in particular we have to avoid a match
1177
             * of the string with itself at the start of the input file).
1178
             */
1179
            if (s->strategy != Z_HUFFMAN_ONLY) {
1180
                s->match_length = longest_match (s, hash_head);
1181
            }
1182
            /* longest_match() sets match_start */
1183
        }
1184
        if (s->match_length >= MIN_MATCH) {
1185
            check_match(s, s->strstart, s->match_start, s->match_length);
1186
 
1187
            _tr_tally_dist(s, s->strstart - s->match_start,
1188
                           s->match_length - MIN_MATCH, bflush);
1189
 
1190
            s->lookahead -= s->match_length;
1191
 
1192
            /* Insert new strings in the hash table only if the match length
1193
             * is not too large. This saves time but degrades compression.
1194
             */
1195
#ifndef FASTEST
1196
            if (s->match_length <= s->max_insert_length &&
1197
                s->lookahead >= MIN_MATCH) {
1198
                s->match_length--; /* string at strstart already in hash table */
1199
                do {
1200
                    s->strstart++;
1201
                    INSERT_STRING(s, s->strstart, hash_head);
1202
                    /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1203
                     * always MIN_MATCH bytes ahead.
1204
                     */
1205
                } while (--s->match_length != 0);
1206
                s->strstart++;
1207
            } else
1208
#endif
1209
            {
1210
                s->strstart += s->match_length;
1211
                s->match_length = 0;
1212
                s->ins_h = s->window[s->strstart];
1213
                UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1214
#if MIN_MATCH != 3
1215
                Call UPDATE_HASH() MIN_MATCH-3 more times
1216
#endif
1217
                /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1218
                 * matter since it will be recomputed at next deflate call.
1219
                 */
1220
            }
1221
        } else {
1222
            /* No match, output a literal byte */
1223
            Tracevv((stderr,"%c", s->window[s->strstart]));
1224
            _tr_tally_lit (s, s->window[s->strstart], bflush);
1225
            s->lookahead--;
1226
            s->strstart++;
1227
        }
1228
        if (bflush) FLUSH_BLOCK(s, 0);
1229
    }
1230
    FLUSH_BLOCK(s, flush == Z_FINISH);
1231
    return flush == Z_FINISH ? finish_done : block_done;
1232
}
1233
 
1234
/* ===========================================================================
1235
 * Same as above, but achieves better compression. We use a lazy
1236
 * evaluation for matches: a match is finally adopted only if there is
1237
 * no better match at the next window position.
1238
 */
1239
local block_state deflate_slow(s, flush)
1240
    deflate_state *s;
1241
    int flush;
1242
{
1243
    IPos hash_head = NIL;    /* head of hash chain */
1244
    int bflush;              /* set if current block must be flushed */
1245
 
1246
    /* Process the input block. */
1247
    for (;;) {
1248
        /* Make sure that we always have enough lookahead, except
1249
         * at the end of the input file. We need MAX_MATCH bytes
1250
         * for the next match, plus MIN_MATCH bytes to insert the
1251
         * string following the next match.
1252
         */
1253
        if (s->lookahead < MIN_LOOKAHEAD) {
1254
            fill_window(s);
1255
            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1256
                return need_more;
1257
            }
1258
            if (s->lookahead == 0) break; /* flush the current block */
1259
        }
1260
 
1261
        /* Insert the string window[strstart .. strstart+2] in the
1262
         * dictionary, and set hash_head to the head of the hash chain:
1263
         */
1264
        if (s->lookahead >= MIN_MATCH) {
1265
            INSERT_STRING(s, s->strstart, hash_head);
1266
        }
1267
 
1268
        /* Find the longest match, discarding those <= prev_length.
1269
         */
1270
        s->prev_length = s->match_length, s->prev_match = s->match_start;
1271
        s->match_length = MIN_MATCH-1;
1272
 
1273
        if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1274
            s->strstart - hash_head <= MAX_DIST(s)) {
1275
            /* To simplify the code, we prevent matches with the string
1276
             * of window index 0 (in particular we have to avoid a match
1277
             * of the string with itself at the start of the input file).
1278
             */
1279
            if (s->strategy != Z_HUFFMAN_ONLY) {
1280
                s->match_length = longest_match (s, hash_head);
1281
            }
1282
            /* longest_match() sets match_start */
1283
 
1284
            if (s->match_length <= 5 && (s->strategy == Z_FILTERED ||
1285
                 (s->match_length == MIN_MATCH &&
1286
                  s->strstart - s->match_start > TOO_FAR))) {
1287
 
1288
                /* If prev_match is also MIN_MATCH, match_start is garbage
1289
                 * but we will ignore the current match anyway.
1290
                 */
1291
                s->match_length = MIN_MATCH-1;
1292
            }
1293
        }
1294
        /* If there was a match at the previous step and the current
1295
         * match is not better, output the previous match:
1296
         */
1297
        if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1298
            uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1299
            /* Do not insert strings in hash table beyond this. */
1300
 
1301
            check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1302
 
1303
            _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1304
                           s->prev_length - MIN_MATCH, bflush);
1305
 
1306
            /* Insert in hash table all strings up to the end of the match.
1307
             * strstart-1 and strstart are already inserted. If there is not
1308
             * enough lookahead, the last two strings are not inserted in
1309
             * the hash table.
1310
             */
1311
            s->lookahead -= s->prev_length-1;
1312
            s->prev_length -= 2;
1313
            do {
1314
                if (++s->strstart <= max_insert) {
1315
                    INSERT_STRING(s, s->strstart, hash_head);
1316
                }
1317
            } while (--s->prev_length != 0);
1318
            s->match_available = 0;
1319
            s->match_length = MIN_MATCH-1;
1320
            s->strstart++;
1321
 
1322
            if (bflush) FLUSH_BLOCK(s, 0);
1323
 
1324
        } else if (s->match_available) {
1325
            /* If there was no match at the previous position, output a
1326
             * single literal. If there was a match but the current match
1327
             * is longer, truncate the previous match to a single literal.
1328
             */
1329
            Tracevv((stderr,"%c", s->window[s->strstart-1]));
1330
            _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1331
            if (bflush) {
1332
                FLUSH_BLOCK_ONLY(s, 0);
1333
            }
1334
            s->strstart++;
1335
            s->lookahead--;
1336
            if (s->strm->avail_out == 0) return need_more;
1337
        } else {
1338
            /* There is no previous match to compare with, wait for
1339
             * the next step to decide.
1340
             */
1341
            s->match_available = 1;
1342
            s->strstart++;
1343
            s->lookahead--;
1344
        }
1345
    }
1346
    Assert (flush != Z_NO_FLUSH, "no flush?");
1347
    if (s->match_available) {
1348
        Tracevv((stderr,"%c", s->window[s->strstart-1]));
1349
        _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1350
        s->match_available = 0;
1351
    }
1352
    FLUSH_BLOCK(s, flush == Z_FINISH);
1353
    return flush == Z_FINISH ? finish_done : block_done;
1354
}