source: rtems/cpukit/zlib/deflate.c @ 89bace6

4.104.11
Last change on this file since 89bace6 was 959f7df2, checked in by Ralf Corsepius <ralf.corsepius@…>, on Oct 28, 2005 at 7:22:42 AM

Import of zlib-1.2.2.2.tar.gz

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1/* deflate.c -- compress data using the deflation algorithm
2 * Copyright (C) 1995-2004 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 1.2.2.2 Copyright 1995-2004 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_(strm, level, version, stream_size)
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_(strm, level, method, windowBits, memLevel, strategy,
217                  version, stream_size)
218    z_streamp strm;
219    int  level;
220    int  method;
221    int  windowBits;
222    int  memLevel;
223    int  strategy;
224    const char *version;
225    int stream_size;
226{
227    deflate_state *s;
228    int wrap = 1;
229    static const char my_version[] = ZLIB_VERSION;
230
231    ushf *overlay;
232    /* We overlay pending_buf and d_buf+l_buf. This works since the average
233     * output size for (length,distance) codes is <= 24 bits.
234     */
235
236    if (version == Z_NULL || version[0] != my_version[0] ||
237        stream_size != sizeof(z_stream)) {
238        return Z_VERSION_ERROR;
239    }
240    if (strm == Z_NULL) return Z_STREAM_ERROR;
241
242    strm->msg = Z_NULL;
243    if (strm->zalloc == (alloc_func)0) {
244        strm->zalloc = zcalloc;
245        strm->opaque = (voidpf)0;
246    }
247    if (strm->zfree == (free_func)0) strm->zfree = zcfree;
248
249#ifdef FASTEST
250    if (level != 0) level = 1;
251#else
252    if (level == Z_DEFAULT_COMPRESSION) level = 6;
253#endif
254
255    if (windowBits < 0) { /* suppress zlib wrapper */
256        wrap = 0;
257        windowBits = -windowBits;
258    }
259#ifdef GZIP
260    else if (windowBits > 15) {
261        wrap = 2;       /* write gzip wrapper instead */
262        windowBits -= 16;
263    }
264#endif
265    if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
266        windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
267        strategy < 0 || strategy > Z_FIXED) {
268        return Z_STREAM_ERROR;
269    }
270    if (windowBits == 8) windowBits = 9;  /* until 256-byte window bug fixed */
271    s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
272    if (s == Z_NULL) return Z_MEM_ERROR;
273    strm->state = (struct internal_state FAR *)s;
274    s->strm = strm;
275
276    s->wrap = wrap;
277    s->gzhead = Z_NULL;
278    s->w_bits = windowBits;
279    s->w_size = 1 << s->w_bits;
280    s->w_mask = s->w_size - 1;
281
282    s->hash_bits = memLevel + 7;
283    s->hash_size = 1 << s->hash_bits;
284    s->hash_mask = s->hash_size - 1;
285    s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
286
287    s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
288    s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
289    s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
290
291    s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
292
293    overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
294    s->pending_buf = (uchf *) overlay;
295    s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
296
297    if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
298        s->pending_buf == Z_NULL) {
299        s->status = FINISH_STATE;
300        strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
301        deflateEnd (strm);
302        return Z_MEM_ERROR;
303    }
304    s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
305    s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
306
307    s->level = level;
308    s->strategy = strategy;
309    s->method = (Byte)method;
310
311    return deflateReset(strm);
312}
313
314/* ========================================================================= */
315int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
316    z_streamp strm;
317    const Bytef *dictionary;
318    uInt  dictLength;
319{
320    deflate_state *s;
321    uInt length = dictLength;
322    uInt n;
323    IPos hash_head = 0;
324
325    if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
326        strm->state->wrap == 2 ||
327        (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
328        return Z_STREAM_ERROR;
329
330    s = strm->state;
331    if (s->wrap)
332        strm->adler = adler32(strm->adler, dictionary, dictLength);
333
334    if (length < MIN_MATCH) return Z_OK;
335    if (length > MAX_DIST(s)) {
336        length = MAX_DIST(s);
337#ifndef USE_DICT_HEAD
338        dictionary += dictLength - length; /* use the tail of the dictionary */
339#endif
340    }
341    zmemcpy(s->window, dictionary, length);
342    s->strstart = length;
343    s->block_start = (long)length;
344
345    /* Insert all strings in the hash table (except for the last two bytes).
346     * s->lookahead stays null, so s->ins_h will be recomputed at the next
347     * call of fill_window.
348     */
349    s->ins_h = s->window[0];
350    UPDATE_HASH(s, s->ins_h, s->window[1]);
351    for (n = 0; n <= length - MIN_MATCH; n++) {
352        INSERT_STRING(s, n, hash_head);
353    }
354    if (hash_head) hash_head = 0;  /* to make compiler happy */
355    return Z_OK;
356}
357
358/* ========================================================================= */
359int ZEXPORT deflateReset (strm)
360    z_streamp strm;
361{
362    deflate_state *s;
363
364    if (strm == Z_NULL || strm->state == Z_NULL ||
365        strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
366        return Z_STREAM_ERROR;
367    }
368
369    strm->total_in = strm->total_out = 0;
370    strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
371    strm->data_type = Z_UNKNOWN;
372
373    s = (deflate_state *)strm->state;
374    s->pending = 0;
375    s->pending_out = s->pending_buf;
376
377    if (s->wrap < 0) {
378        s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
379    }
380    s->status = s->wrap ? INIT_STATE : BUSY_STATE;
381    strm->adler =
382#ifdef GZIP
383        s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
384#endif
385        adler32(0L, Z_NULL, 0);
386    s->last_flush = Z_NO_FLUSH;
387
388    _tr_init(s);
389    lm_init(s);
390
391    return Z_OK;
392}
393
394/* ========================================================================= */
395int ZEXPORT deflateSetHeader (strm, head)
396    z_streamp strm;
397    gz_headerp head;
398{
399    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
400    if (strm->state->wrap != 2) return Z_STREAM_ERROR;
401    strm->state->gzhead = head;
402    return Z_OK;
403}
404
405/* ========================================================================= */
406int ZEXPORT deflatePrime (strm, bits, value)
407    z_streamp strm;
408    int bits;
409    int value;
410{
411    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
412    strm->state->bi_valid = bits;
413    strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
414    return Z_OK;
415}
416
417/* ========================================================================= */
418int ZEXPORT deflateParams(strm, level, strategy)
419    z_streamp strm;
420    int level;
421    int strategy;
422{
423    deflate_state *s;
424    compress_func func;
425    int err = Z_OK;
426
427    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
428    s = strm->state;
429
430#ifdef FASTEST
431    if (level != 0) level = 1;
432#else
433    if (level == Z_DEFAULT_COMPRESSION) level = 6;
434#endif
435    if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
436        return Z_STREAM_ERROR;
437    }
438    func = configuration_table[s->level].func;
439
440    if (func != configuration_table[level].func && strm->total_in != 0) {
441        /* Flush the last buffer: */
442        err = deflate(strm, Z_PARTIAL_FLUSH);
443    }
444    if (s->level != level) {
445        s->level = level;
446        s->max_lazy_match   = configuration_table[level].max_lazy;
447        s->good_match       = configuration_table[level].good_length;
448        s->nice_match       = configuration_table[level].nice_length;
449        s->max_chain_length = configuration_table[level].max_chain;
450    }
451    s->strategy = strategy;
452    return err;
453}
454
455/* =========================================================================
456 * For the default windowBits of 15 and memLevel of 8, this function returns
457 * a close to exact, as well as small, upper bound on the compressed size.
458 * They are coded as constants here for a reason--if the #define's are
459 * changed, then this function needs to be changed as well.  The return
460 * value for 15 and 8 only works for those exact settings.
461 *
462 * For any setting other than those defaults for windowBits and memLevel,
463 * the value returned is a conservative worst case for the maximum expansion
464 * resulting from using fixed blocks instead of stored blocks, which deflate
465 * can emit on compressed data for some combinations of the parameters.
466 *
467 * This function could be more sophisticated to provide closer upper bounds
468 * for every combination of windowBits and memLevel, as well as wrap.
469 * But even the conservative upper bound of about 14% expansion does not
470 * seem onerous for output buffer allocation.
471 */
472uLong ZEXPORT deflateBound(strm, sourceLen)
473    z_streamp strm;
474    uLong sourceLen;
475{
476    deflate_state *s;
477    uLong destLen;
478
479    /* conservative upper bound */
480    destLen = sourceLen +
481              ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
482
483    /* if can't get parameters, return conservative bound */
484    if (strm == Z_NULL || strm->state == Z_NULL)
485        return destLen;
486
487    /* if not default parameters, return conservative bound */
488    s = strm->state;
489    if (s->w_bits != 15 || s->hash_bits != 8 + 7)
490        return destLen;
491
492    /* default settings: return tight bound for that case */
493    return compressBound(sourceLen);
494}
495
496/* =========================================================================
497 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
498 * IN assertion: the stream state is correct and there is enough room in
499 * pending_buf.
500 */
501local void putShortMSB (s, b)
502    deflate_state *s;
503    uInt b;
504{
505    put_byte(s, (Byte)(b >> 8));
506    put_byte(s, (Byte)(b & 0xff));
507}
508
509/* =========================================================================
510 * Flush as much pending output as possible. All deflate() output goes
511 * through this function so some applications may wish to modify it
512 * to avoid allocating a large strm->next_out buffer and copying into it.
513 * (See also read_buf()).
514 */
515local void flush_pending(strm)
516    z_streamp strm;
517{
518    unsigned len = strm->state->pending;
519
520    if (len > strm->avail_out) len = strm->avail_out;
521    if (len == 0) return;
522
523    zmemcpy(strm->next_out, strm->state->pending_out, len);
524    strm->next_out  += len;
525    strm->state->pending_out  += len;
526    strm->total_out += len;
527    strm->avail_out  -= len;
528    strm->state->pending -= len;
529    if (strm->state->pending == 0) {
530        strm->state->pending_out = strm->state->pending_buf;
531    }
532}
533
534/* ========================================================================= */
535int ZEXPORT deflate (strm, flush)
536    z_streamp strm;
537    int flush;
538{
539    int old_flush; /* value of flush param for previous deflate call */
540    deflate_state *s;
541
542    if (strm == Z_NULL || strm->state == Z_NULL ||
543        flush > Z_FINISH || flush < 0) {
544        return Z_STREAM_ERROR;
545    }
546    s = strm->state;
547
548    if (strm->next_out == Z_NULL ||
549        (strm->next_in == Z_NULL && strm->avail_in != 0) ||
550        (s->status == FINISH_STATE && flush != Z_FINISH)) {
551        ERR_RETURN(strm, Z_STREAM_ERROR);
552    }
553    if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
554
555    s->strm = strm; /* just in case */
556    old_flush = s->last_flush;
557    s->last_flush = flush;
558
559    /* Write the header */
560    if (s->status == INIT_STATE) {
561#ifdef GZIP
562        if (s->wrap == 2) {
563            strm->adler = crc32(0L, Z_NULL, 0);
564            put_byte(s, 31);
565            put_byte(s, 139);
566            put_byte(s, 8);
567            if (s->gzhead == NULL) {
568                put_byte(s, 0);
569                put_byte(s, 0);
570                put_byte(s, 0);
571                put_byte(s, 0);
572                put_byte(s, 0);
573                put_byte(s, s->level == 9 ? 2 :
574                            (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
575                             4 : 0));
576                put_byte(s, OS_CODE);
577                s->status = BUSY_STATE;
578            }
579            else {
580                put_byte(s, (s->gzhead->text ? 1 : 0) +
581                            (s->gzhead->hcrc ? 2 : 0) +
582                            (s->gzhead->extra == Z_NULL ? 0 : 4) +
583                            (s->gzhead->name == Z_NULL ? 0 : 8) +
584                            (s->gzhead->comment == Z_NULL ? 0 : 16)
585                        );
586                put_byte(s, s->gzhead->time & 0xff);
587                put_byte(s, (s->gzhead->time >> 8) & 0xff);
588                put_byte(s, (s->gzhead->time >> 16) & 0xff);
589                put_byte(s, (s->gzhead->time >> 24) & 0xff);
590                put_byte(s, s->level == 9 ? 2 :
591                            (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
592                             4 : 0));
593                put_byte(s, s->gzhead->os & 0xff);
594                if (s->gzhead->extra != NULL) {
595                    put_byte(s, s->gzhead->extra_len & 0xff);
596                    put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
597                }
598                if (s->gzhead->hcrc)
599                    strm->adler = crc32(strm->adler, s->pending_buf,
600                                        s->pending);
601                s->gzindex = 0;
602                s->status = EXTRA_STATE;
603            }
604        }
605        else
606#endif
607        {
608            uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
609            uInt level_flags;
610
611            if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
612                level_flags = 0;
613            else if (s->level < 6)
614                level_flags = 1;
615            else if (s->level == 6)
616                level_flags = 2;
617            else
618                level_flags = 3;
619            header |= (level_flags << 6);
620            if (s->strstart != 0) header |= PRESET_DICT;
621            header += 31 - (header % 31);
622
623            s->status = BUSY_STATE;
624            putShortMSB(s, header);
625
626            /* Save the adler32 of the preset dictionary: */
627            if (s->strstart != 0) {
628                putShortMSB(s, (uInt)(strm->adler >> 16));
629                putShortMSB(s, (uInt)(strm->adler & 0xffff));
630            }
631            strm->adler = adler32(0L, Z_NULL, 0);
632        }
633    }
634#ifdef GZIP
635    if (s->status == EXTRA_STATE) {
636        if (s->gzhead->extra != NULL) {
637            int beg = s->pending;   /* start of bytes to update crc */
638
639            while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
640                if (s->pending == s->pending_buf_size) {
641                    if (s->gzhead->hcrc && s->pending > beg)
642                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
643                                            s->pending - beg);
644                    flush_pending(strm);
645                    beg = s->pending;
646                    if (s->pending == s->pending_buf_size)
647                        break;
648                }
649                put_byte(s, s->gzhead->extra[s->gzindex]);
650                s->gzindex++;
651            }
652            if (s->gzhead->hcrc && s->pending > beg)
653                strm->adler = crc32(strm->adler, s->pending_buf + beg,
654                                    s->pending - beg);
655            if (s->gzindex == s->gzhead->extra_len) {
656                s->gzindex = 0;
657                s->status = NAME_STATE;
658            }
659        }
660        else
661            s->status = NAME_STATE;
662    }
663    if (s->status == NAME_STATE) {
664        if (s->gzhead->name != NULL) {
665            int beg = s->pending;   /* start of bytes to update crc */
666            int val;
667
668            do {
669                if (s->pending == s->pending_buf_size) {
670                    if (s->gzhead->hcrc && s->pending > beg)
671                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
672                                            s->pending - beg);
673                    flush_pending(strm);
674                    beg = s->pending;
675                    if (s->pending == s->pending_buf_size) {
676                        val = 1;
677                        break;
678                    }
679                }
680                val = s->gzhead->name[s->gzindex++];
681                put_byte(s, val);
682            } while (val != 0);
683            if (s->gzhead->hcrc && s->pending > beg)
684                strm->adler = crc32(strm->adler, s->pending_buf + beg,
685                                    s->pending - beg);
686            if (val == 0) {
687                s->gzindex = 0;
688                s->status = COMMENT_STATE;
689            }
690        }
691        else
692            s->status = COMMENT_STATE;
693    }
694    if (s->status == COMMENT_STATE) {
695        if (s->gzhead->comment != NULL) {
696            int beg = s->pending;   /* start of bytes to update crc */
697            int val;
698
699            do {
700                if (s->pending == s->pending_buf_size) {
701                    if (s->gzhead->hcrc && s->pending > beg)
702                        strm->adler = crc32(strm->adler, s->pending_buf + beg,
703                                            s->pending - beg);
704                    flush_pending(strm);
705                    beg = s->pending;
706                    if (s->pending == s->pending_buf_size) {
707                        val = 1;
708                        break;
709                    }
710                }
711                val = s->gzhead->comment[s->gzindex++];
712                put_byte(s, val);
713            } while (val != 0);
714            if (s->gzhead->hcrc && s->pending > beg)
715                strm->adler = crc32(strm->adler, s->pending_buf + beg,
716                                    s->pending - beg);
717            if (val == 0)
718                s->status = HCRC_STATE;
719        }
720        else
721            s->status = HCRC_STATE;
722    }
723    if (s->status == HCRC_STATE) {
724        if (s->gzhead->hcrc) {
725            if (s->pending + 2 > s->pending_buf_size)
726                flush_pending(strm);
727            if (s->pending + 2 <= s->pending_buf_size) {
728                put_byte(s, strm->adler & 0xff);
729                put_byte(s, (strm->adler >> 8) & 0xff);
730                strm->adler = crc32(0L, Z_NULL, 0);
731                s->status = BUSY_STATE;
732            }
733        }
734        else
735            s->status = BUSY_STATE;
736    }
737#endif
738
739    /* Flush as much pending output as possible */
740    if (s->pending != 0) {
741        flush_pending(strm);
742        if (strm->avail_out == 0) {
743            /* Since avail_out is 0, deflate will be called again with
744             * more output space, but possibly with both pending and
745             * avail_in equal to zero. There won't be anything to do,
746             * but this is not an error situation so make sure we
747             * return OK instead of BUF_ERROR at next call of deflate:
748             */
749            s->last_flush = -1;
750            return Z_OK;
751        }
752
753    /* Make sure there is something to do and avoid duplicate consecutive
754     * flushes. For repeated and useless calls with Z_FINISH, we keep
755     * returning Z_STREAM_END instead of Z_BUF_ERROR.
756     */
757    } else if (strm->avail_in == 0 && flush <= old_flush &&
758               flush != Z_FINISH) {
759        ERR_RETURN(strm, Z_BUF_ERROR);
760    }
761
762    /* User must not provide more input after the first FINISH: */
763    if (s->status == FINISH_STATE && strm->avail_in != 0) {
764        ERR_RETURN(strm, Z_BUF_ERROR);
765    }
766
767    /* Start a new block or continue the current one.
768     */
769    if (strm->avail_in != 0 || s->lookahead != 0 ||
770        (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
771        block_state bstate;
772
773        bstate = (*(configuration_table[s->level].func))(s, flush);
774
775        if (bstate == finish_started || bstate == finish_done) {
776            s->status = FINISH_STATE;
777        }
778        if (bstate == need_more || bstate == finish_started) {
779            if (strm->avail_out == 0) {
780                s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
781            }
782            return Z_OK;
783            /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
784             * of deflate should use the same flush parameter to make sure
785             * that the flush is complete. So we don't have to output an
786             * empty block here, this will be done at next call. This also
787             * ensures that for a very small output buffer, we emit at most
788             * one empty block.
789             */
790        }
791        if (bstate == block_done) {
792            if (flush == Z_PARTIAL_FLUSH) {
793                _tr_align(s);
794            } else { /* FULL_FLUSH or SYNC_FLUSH */
795                _tr_stored_block(s, (char*)0, 0L, 0);
796                /* For a full flush, this empty block will be recognized
797                 * as a special marker by inflate_sync().
798                 */
799                if (flush == Z_FULL_FLUSH) {
800                    CLEAR_HASH(s);             /* forget history */
801                }
802            }
803            flush_pending(strm);
804            if (strm->avail_out == 0) {
805              s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
806              return Z_OK;
807            }
808        }
809    }
810    Assert(strm->avail_out > 0, "bug2");
811
812    if (flush != Z_FINISH) return Z_OK;
813    if (s->wrap <= 0) return Z_STREAM_END;
814
815    /* Write the trailer */
816#ifdef GZIP
817    if (s->wrap == 2) {
818        put_byte(s, (Byte)(strm->adler & 0xff));
819        put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
820        put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
821        put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
822        put_byte(s, (Byte)(strm->total_in & 0xff));
823        put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
824        put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
825        put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
826    }
827    else
828#endif
829    {
830        putShortMSB(s, (uInt)(strm->adler >> 16));
831        putShortMSB(s, (uInt)(strm->adler & 0xffff));
832    }
833    flush_pending(strm);
834    /* If avail_out is zero, the application will call deflate again
835     * to flush the rest.
836     */
837    if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
838    return s->pending != 0 ? Z_OK : Z_STREAM_END;
839}
840
841/* ========================================================================= */
842int ZEXPORT deflateEnd (strm)
843    z_streamp strm;
844{
845    int status;
846
847    if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
848
849    status = strm->state->status;
850    if (status != INIT_STATE &&
851        status != EXTRA_STATE &&
852        status != NAME_STATE &&
853        status != COMMENT_STATE &&
854        status != HCRC_STATE &&
855        status != BUSY_STATE &&
856        status != FINISH_STATE) {
857      return Z_STREAM_ERROR;
858    }
859
860    /* Deallocate in reverse order of allocations: */
861    TRY_FREE(strm, strm->state->pending_buf);
862    TRY_FREE(strm, strm->state->head);
863    TRY_FREE(strm, strm->state->prev);
864    TRY_FREE(strm, strm->state->window);
865
866    ZFREE(strm, strm->state);
867    strm->state = Z_NULL;
868
869    return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
870}
871
872/* =========================================================================
873 * Copy the source state to the destination state.
874 * To simplify the source, this is not supported for 16-bit MSDOS (which
875 * doesn't have enough memory anyway to duplicate compression states).
876 */
877int ZEXPORT deflateCopy (dest, source)
878    z_streamp dest;
879    z_streamp source;
880{
881#ifdef MAXSEG_64K
882    return Z_STREAM_ERROR;
883#else
884    deflate_state *ds;
885    deflate_state *ss;
886    ushf *overlay;
887
888
889    if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
890        return Z_STREAM_ERROR;
891    }
892
893    ss = source->state;
894
895    zmemcpy(dest, source, sizeof(z_stream));
896
897    ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
898    if (ds == Z_NULL) return Z_MEM_ERROR;
899    dest->state = (struct internal_state FAR *) ds;
900    zmemcpy(ds, ss, sizeof(deflate_state));
901    ds->strm = dest;
902
903    ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
904    ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
905    ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
906    overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
907    ds->pending_buf = (uchf *) overlay;
908
909    if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
910        ds->pending_buf == Z_NULL) {
911        deflateEnd (dest);
912        return Z_MEM_ERROR;
913    }
914    /* following zmemcpy do not work for 16-bit MSDOS */
915    zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
916    zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
917    zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
918    zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
919
920    ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
921    ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
922    ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
923
924    ds->l_desc.dyn_tree = ds->dyn_ltree;
925    ds->d_desc.dyn_tree = ds->dyn_dtree;
926    ds->bl_desc.dyn_tree = ds->bl_tree;
927
928    return Z_OK;
929#endif /* MAXSEG_64K */
930}
931
932/* ===========================================================================
933 * Read a new buffer from the current input stream, update the adler32
934 * and total number of bytes read.  All deflate() input goes through
935 * this function so some applications may wish to modify it to avoid
936 * allocating a large strm->next_in buffer and copying from it.
937 * (See also flush_pending()).
938 */
939local int read_buf(strm, buf, size)
940    z_streamp strm;
941    Bytef *buf;
942    unsigned size;
943{
944    unsigned len = strm->avail_in;
945
946    if (len > size) len = size;
947    if (len == 0) return 0;
948
949    strm->avail_in  -= len;
950
951    if (strm->state->wrap == 1) {
952        strm->adler = adler32(strm->adler, strm->next_in, len);
953    }
954#ifdef GZIP
955    else if (strm->state->wrap == 2) {
956        strm->adler = crc32(strm->adler, strm->next_in, len);
957    }
958#endif
959    zmemcpy(buf, strm->next_in, len);
960    strm->next_in  += len;
961    strm->total_in += len;
962
963    return (int)len;
964}
965
966/* ===========================================================================
967 * Initialize the "longest match" routines for a new zlib stream
968 */
969local void lm_init (s)
970    deflate_state *s;
971{
972    s->window_size = (ulg)2L*s->w_size;
973
974    CLEAR_HASH(s);
975
976    /* Set the default configuration parameters:
977     */
978    s->max_lazy_match   = configuration_table[s->level].max_lazy;
979    s->good_match       = configuration_table[s->level].good_length;
980    s->nice_match       = configuration_table[s->level].nice_length;
981    s->max_chain_length = configuration_table[s->level].max_chain;
982
983    s->strstart = 0;
984    s->block_start = 0L;
985    s->lookahead = 0;
986    s->match_length = s->prev_length = MIN_MATCH-1;
987    s->match_available = 0;
988    s->ins_h = 0;
989#ifdef ASMV
990    match_init(); /* initialize the asm code */
991#endif
992}
993
994#ifndef FASTEST
995/* ===========================================================================
996 * Set match_start to the longest match starting at the given string and
997 * return its length. Matches shorter or equal to prev_length are discarded,
998 * in which case the result is equal to prev_length and match_start is
999 * garbage.
1000 * IN assertions: cur_match is the head of the hash chain for the current
1001 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1002 * OUT assertion: the match length is not greater than s->lookahead.
1003 */
1004#ifndef ASMV
1005/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1006 * match.S. The code will be functionally equivalent.
1007 */
1008local uInt longest_match(s, cur_match)
1009    deflate_state *s;
1010    IPos cur_match;                             /* current match */
1011{
1012    unsigned chain_length = s->max_chain_length;/* max hash chain length */
1013    register Bytef *scan = s->window + s->strstart; /* current string */
1014    register Bytef *match;                       /* matched string */
1015    register int len;                           /* length of current match */
1016    int best_len = s->prev_length;              /* best match length so far */
1017    int nice_match = s->nice_match;             /* stop if match long enough */
1018    IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1019        s->strstart - (IPos)MAX_DIST(s) : NIL;
1020    /* Stop when cur_match becomes <= limit. To simplify the code,
1021     * we prevent matches with the string of window index 0.
1022     */
1023    Posf *prev = s->prev;
1024    uInt wmask = s->w_mask;
1025
1026#ifdef UNALIGNED_OK
1027    /* Compare two bytes at a time. Note: this is not always beneficial.
1028     * Try with and without -DUNALIGNED_OK to check.
1029     */
1030    register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1031    register ush scan_start = *(ushf*)scan;
1032    register ush scan_end   = *(ushf*)(scan+best_len-1);
1033#else
1034    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1035    register Byte scan_end1  = scan[best_len-1];
1036    register Byte scan_end   = scan[best_len];
1037#endif
1038
1039    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1040     * It is easy to get rid of this optimization if necessary.
1041     */
1042    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1043
1044    /* Do not waste too much time if we already have a good match: */
1045    if (s->prev_length >= s->good_match) {
1046        chain_length >>= 2;
1047    }
1048    /* Do not look for matches beyond the end of the input. This is necessary
1049     * to make deflate deterministic.
1050     */
1051    if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1052
1053    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1054
1055    do {
1056        Assert(cur_match < s->strstart, "no future");
1057        match = s->window + cur_match;
1058
1059        /* Skip to next match if the match length cannot increase
1060         * or if the match length is less than 2.  Note that the checks below
1061         * for insufficient lookahead only occur occasionally for performance
1062         * reasons.  Therefore uninitialized memory will be accessed, and
1063         * conditional jumps will be made that depend on those values.
1064         * However the length of the match is limited to the lookahead, so
1065         * the output of deflate is not affected by the uninitialized values.
1066         */
1067#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1068        /* This code assumes sizeof(unsigned short) == 2. Do not use
1069         * UNALIGNED_OK if your compiler uses a different size.
1070         */
1071        if (*(ushf*)(match+best_len-1) != scan_end ||
1072            *(ushf*)match != scan_start) continue;
1073
1074        /* It is not necessary to compare scan[2] and match[2] since they are
1075         * always equal when the other bytes match, given that the hash keys
1076         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1077         * strstart+3, +5, ... up to strstart+257. We check for insufficient
1078         * lookahead only every 4th comparison; the 128th check will be made
1079         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1080         * necessary to put more guard bytes at the end of the window, or
1081         * to check more often for insufficient lookahead.
1082         */
1083        Assert(scan[2] == match[2], "scan[2]?");
1084        scan++, match++;
1085        do {
1086        } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1087                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1088                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1089                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1090                 scan < strend);
1091        /* The funny "do {}" generates better code on most compilers */
1092
1093        /* Here, scan <= window+strstart+257 */
1094        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1095        if (*scan == *match) scan++;
1096
1097        len = (MAX_MATCH - 1) - (int)(strend-scan);
1098        scan = strend - (MAX_MATCH-1);
1099
1100#else /* UNALIGNED_OK */
1101
1102        if (match[best_len]   != scan_end  ||
1103            match[best_len-1] != scan_end1 ||
1104            *match            != *scan     ||
1105            *++match          != scan[1])      continue;
1106
1107        /* The check at best_len-1 can be removed because it will be made
1108         * again later. (This heuristic is not always a win.)
1109         * It is not necessary to compare scan[2] and match[2] since they
1110         * are always equal when the other bytes match, given that
1111         * the hash keys are equal and that HASH_BITS >= 8.
1112         */
1113        scan += 2, match++;
1114        Assert(*scan == *match, "match[2]?");
1115
1116        /* We check for insufficient lookahead only every 8th comparison;
1117         * the 256th check will be made at strstart+258.
1118         */
1119        do {
1120        } while (*++scan == *++match && *++scan == *++match &&
1121                 *++scan == *++match && *++scan == *++match &&
1122                 *++scan == *++match && *++scan == *++match &&
1123                 *++scan == *++match && *++scan == *++match &&
1124                 scan < strend);
1125
1126        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1127
1128        len = MAX_MATCH - (int)(strend - scan);
1129        scan = strend - MAX_MATCH;
1130
1131#endif /* UNALIGNED_OK */
1132
1133        if (len > best_len) {
1134            s->match_start = cur_match;
1135            best_len = len;
1136            if (len >= nice_match) break;
1137#ifdef UNALIGNED_OK
1138            scan_end = *(ushf*)(scan+best_len-1);
1139#else
1140            scan_end1  = scan[best_len-1];
1141            scan_end   = scan[best_len];
1142#endif
1143        }
1144    } while ((cur_match = prev[cur_match & wmask]) > limit
1145             && --chain_length != 0);
1146
1147    if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1148    return s->lookahead;
1149}
1150#endif /* ASMV */
1151#endif /* FASTEST */
1152
1153/* ---------------------------------------------------------------------------
1154 * Optimized version for level == 1 or strategy == Z_RLE only
1155 */
1156local uInt longest_match_fast(s, cur_match)
1157    deflate_state *s;
1158    IPos cur_match;                             /* current match */
1159{
1160    register Bytef *scan = s->window + s->strstart; /* current string */
1161    register Bytef *match;                       /* matched string */
1162    register int len;                           /* length of current match */
1163    register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1164
1165    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1166     * It is easy to get rid of this optimization if necessary.
1167     */
1168    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1169
1170    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1171
1172    Assert(cur_match < s->strstart, "no future");
1173
1174    match = s->window + cur_match;
1175
1176    /* Return failure if the match length is less than 2:
1177     */
1178    if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1179
1180    /* The check at best_len-1 can be removed because it will be made
1181     * again later. (This heuristic is not always a win.)
1182     * It is not necessary to compare scan[2] and match[2] since they
1183     * are always equal when the other bytes match, given that
1184     * the hash keys are equal and that HASH_BITS >= 8.
1185     */
1186    scan += 2, match += 2;
1187    Assert(*scan == *match, "match[2]?");
1188
1189    /* We check for insufficient lookahead only every 8th comparison;
1190     * the 256th check will be made at strstart+258.
1191     */
1192    do {
1193    } while (*++scan == *++match && *++scan == *++match &&
1194             *++scan == *++match && *++scan == *++match &&
1195             *++scan == *++match && *++scan == *++match &&
1196             *++scan == *++match && *++scan == *++match &&
1197             scan < strend);
1198
1199    Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1200
1201    len = MAX_MATCH - (int)(strend - scan);
1202
1203    if (len < MIN_MATCH) return MIN_MATCH - 1;
1204
1205    s->match_start = cur_match;
1206    return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1207}
1208
1209#ifdef DEBUG
1210/* ===========================================================================
1211 * Check that the match at match_start is indeed a match.
1212 */
1213local void check_match(s, start, match, length)
1214    deflate_state *s;
1215    IPos start, match;
1216    int length;
1217{
1218    /* check that the match is indeed a match */
1219    if (zmemcmp(s->window + match,
1220                s->window + start, length) != EQUAL) {
1221        fprintf(stderr, " start %u, match %u, length %d\n",
1222                start, match, length);
1223        do {
1224            fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1225        } while (--length != 0);
1226        z_error("invalid match");
1227    }
1228    if (z_verbose > 1) {
1229        fprintf(stderr,"\\[%d,%d]", start-match, length);
1230        do { putc(s->window[start++], stderr); } while (--length != 0);
1231    }
1232}
1233#else
1234#  define check_match(s, start, match, length)
1235#endif /* DEBUG */
1236
1237/* ===========================================================================
1238 * Fill the window when the lookahead becomes insufficient.
1239 * Updates strstart and lookahead.
1240 *
1241 * IN assertion: lookahead < MIN_LOOKAHEAD
1242 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1243 *    At least one byte has been read, or avail_in == 0; reads are
1244 *    performed for at least two bytes (required for the zip translate_eol
1245 *    option -- not supported here).
1246 */
1247local void fill_window(s)
1248    deflate_state *s;
1249{
1250    register unsigned n, m;
1251    register Posf *p;
1252    unsigned more;    /* Amount of free space at the end of the window. */
1253    uInt wsize = s->w_size;
1254
1255    do {
1256        more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1257
1258        /* Deal with !@#$% 64K limit: */
1259        if (sizeof(int) <= 2) {
1260            if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1261                more = wsize;
1262
1263            } else if (more == (unsigned)(-1)) {
1264                /* Very unlikely, but possible on 16 bit machine if
1265                 * strstart == 0 && lookahead == 1 (input done a byte at time)
1266                 */
1267                more--;
1268            }
1269        }
1270
1271        /* If the window is almost full and there is insufficient lookahead,
1272         * move the upper half to the lower one to make room in the upper half.
1273         */
1274        if (s->strstart >= wsize+MAX_DIST(s)) {
1275
1276            zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1277            s->match_start -= wsize;
1278            s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
1279            s->block_start -= (long) wsize;
1280
1281            /* Slide the hash table (could be avoided with 32 bit values
1282               at the expense of memory usage). We slide even when level == 0
1283               to keep the hash table consistent if we switch back to level > 0
1284               later. (Using level 0 permanently is not an optimal usage of
1285               zlib, so we don't care about this pathological case.)
1286             */
1287            n = s->hash_size;
1288            p = &s->head[n];
1289            do {
1290                m = *--p;
1291                *p = (Pos)(m >= wsize ? m-wsize : NIL);
1292            } while (--n);
1293
1294            n = wsize;
1295#ifndef FASTEST
1296            p = &s->prev[n];
1297            do {
1298                m = *--p;
1299                *p = (Pos)(m >= wsize ? m-wsize : NIL);
1300                /* If n is not on any hash chain, prev[n] is garbage but
1301                 * its value will never be used.
1302                 */
1303            } while (--n);
1304#endif
1305            more += wsize;
1306        }
1307        if (s->strm->avail_in == 0) return;
1308
1309        /* If there was no sliding:
1310         *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1311         *    more == window_size - lookahead - strstart
1312         * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1313         * => more >= window_size - 2*WSIZE + 2
1314         * In the BIG_MEM or MMAP case (not yet supported),
1315         *   window_size == input_size + MIN_LOOKAHEAD  &&
1316         *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1317         * Otherwise, window_size == 2*WSIZE so more >= 2.
1318         * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1319         */
1320        Assert(more >= 2, "more < 2");
1321
1322        n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1323        s->lookahead += n;
1324
1325        /* Initialize the hash value now that we have some input: */
1326        if (s->lookahead >= MIN_MATCH) {
1327            s->ins_h = s->window[s->strstart];
1328            UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1329#if MIN_MATCH != 3
1330            Call UPDATE_HASH() MIN_MATCH-3 more times
1331#endif
1332        }
1333        /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1334         * but this is not important since only literal bytes will be emitted.
1335         */
1336
1337    } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1338}
1339
1340/* ===========================================================================
1341 * Flush the current block, with given end-of-file flag.
1342 * IN assertion: strstart is set to the end of the current match.
1343 */
1344#define FLUSH_BLOCK_ONLY(s, eof) { \
1345   _tr_flush_block(s, (s->block_start >= 0L ? \
1346                   (charf *)&s->window[(unsigned)s->block_start] : \
1347                   (charf *)Z_NULL), \
1348                (ulg)((long)s->strstart - s->block_start), \
1349                (eof)); \
1350   s->block_start = s->strstart; \
1351   flush_pending(s->strm); \
1352   Tracev((stderr,"[FLUSH]")); \
1353}
1354
1355/* Same but force premature exit if necessary. */
1356#define FLUSH_BLOCK(s, eof) { \
1357   FLUSH_BLOCK_ONLY(s, eof); \
1358   if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1359}
1360
1361/* ===========================================================================
1362 * Copy without compression as much as possible from the input stream, return
1363 * the current block state.
1364 * This function does not insert new strings in the dictionary since
1365 * uncompressible data is probably not useful. This function is used
1366 * only for the level=0 compression option.
1367 * NOTE: this function should be optimized to avoid extra copying from
1368 * window to pending_buf.
1369 */
1370local block_state deflate_stored(s, flush)
1371    deflate_state *s;
1372    int flush;
1373{
1374    /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1375     * to pending_buf_size, and each stored block has a 5 byte header:
1376     */
1377    ulg max_block_size = 0xffff;
1378    ulg max_start;
1379
1380    if (max_block_size > s->pending_buf_size - 5) {
1381        max_block_size = s->pending_buf_size - 5;
1382    }
1383
1384    /* Copy as much as possible from input to output: */
1385    for (;;) {
1386        /* Fill the window as much as possible: */
1387        if (s->lookahead <= 1) {
1388
1389            Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1390                   s->block_start >= (long)s->w_size, "slide too late");
1391
1392            fill_window(s);
1393            if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1394
1395            if (s->lookahead == 0) break; /* flush the current block */
1396        }
1397        Assert(s->block_start >= 0L, "block gone");
1398
1399        s->strstart += s->lookahead;
1400        s->lookahead = 0;
1401
1402        /* Emit a stored block if pending_buf will be full: */
1403        max_start = s->block_start + max_block_size;
1404        if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1405            /* strstart == 0 is possible when wraparound on 16-bit machine */
1406            s->lookahead = (uInt)(s->strstart - max_start);
1407            s->strstart = (uInt)max_start;
1408            FLUSH_BLOCK(s, 0);
1409        }
1410        /* Flush if we may have to slide, otherwise block_start may become
1411         * negative and the data will be gone:
1412         */
1413        if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1414            FLUSH_BLOCK(s, 0);
1415        }
1416    }
1417    FLUSH_BLOCK(s, flush == Z_FINISH);
1418    return flush == Z_FINISH ? finish_done : block_done;
1419}
1420
1421/* ===========================================================================
1422 * Compress as much as possible from the input stream, return the current
1423 * block state.
1424 * This function does not perform lazy evaluation of matches and inserts
1425 * new strings in the dictionary only for unmatched strings or for short
1426 * matches. It is used only for the fast compression options.
1427 */
1428local block_state deflate_fast(s, flush)
1429    deflate_state *s;
1430    int flush;
1431{
1432    IPos hash_head = NIL; /* head of the hash chain */
1433    int bflush;           /* set if current block must be flushed */
1434
1435    for (;;) {
1436        /* Make sure that we always have enough lookahead, except
1437         * at the end of the input file. We need MAX_MATCH bytes
1438         * for the next match, plus MIN_MATCH bytes to insert the
1439         * string following the next match.
1440         */
1441        if (s->lookahead < MIN_LOOKAHEAD) {
1442            fill_window(s);
1443            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1444                return need_more;
1445            }
1446            if (s->lookahead == 0) break; /* flush the current block */
1447        }
1448
1449        /* Insert the string window[strstart .. strstart+2] in the
1450         * dictionary, and set hash_head to the head of the hash chain:
1451         */
1452        if (s->lookahead >= MIN_MATCH) {
1453            INSERT_STRING(s, s->strstart, hash_head);
1454        }
1455
1456        /* Find the longest match, discarding those <= prev_length.
1457         * At this point we have always match_length < MIN_MATCH
1458         */
1459        if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1460            /* To simplify the code, we prevent matches with the string
1461             * of window index 0 (in particular we have to avoid a match
1462             * of the string with itself at the start of the input file).
1463             */
1464#ifdef FASTEST
1465            if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) ||
1466                (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
1467                s->match_length = longest_match_fast (s, hash_head);
1468            }
1469#else
1470            if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1471                s->match_length = longest_match (s, hash_head);
1472            } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1473                s->match_length = longest_match_fast (s, hash_head);
1474            }
1475#endif
1476            /* longest_match() or longest_match_fast() sets match_start */
1477        }
1478        if (s->match_length >= MIN_MATCH) {
1479            check_match(s, s->strstart, s->match_start, s->match_length);
1480
1481            _tr_tally_dist(s, s->strstart - s->match_start,
1482                           s->match_length - MIN_MATCH, bflush);
1483
1484            s->lookahead -= s->match_length;
1485
1486            /* Insert new strings in the hash table only if the match length
1487             * is not too large. This saves time but degrades compression.
1488             */
1489#ifndef FASTEST
1490            if (s->match_length <= s->max_insert_length &&
1491                s->lookahead >= MIN_MATCH) {
1492                s->match_length--; /* string at strstart already in table */
1493                do {
1494                    s->strstart++;
1495                    INSERT_STRING(s, s->strstart, hash_head);
1496                    /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1497                     * always MIN_MATCH bytes ahead.
1498                     */
1499                } while (--s->match_length != 0);
1500                s->strstart++;
1501            } else
1502#endif
1503            {
1504                s->strstart += s->match_length;
1505                s->match_length = 0;
1506                s->ins_h = s->window[s->strstart];
1507                UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1508#if MIN_MATCH != 3
1509                Call UPDATE_HASH() MIN_MATCH-3 more times
1510#endif
1511                /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1512                 * matter since it will be recomputed at next deflate call.
1513                 */
1514            }
1515        } else {
1516            /* No match, output a literal byte */
1517            Tracevv((stderr,"%c", s->window[s->strstart]));
1518            _tr_tally_lit (s, s->window[s->strstart], bflush);
1519            s->lookahead--;
1520            s->strstart++;
1521        }
1522        if (bflush) FLUSH_BLOCK(s, 0);
1523    }
1524    FLUSH_BLOCK(s, flush == Z_FINISH);
1525    return flush == Z_FINISH ? finish_done : block_done;
1526}
1527
1528#ifndef FASTEST
1529/* ===========================================================================
1530 * Same as above, but achieves better compression. We use a lazy
1531 * evaluation for matches: a match is finally adopted only if there is
1532 * no better match at the next window position.
1533 */
1534local block_state deflate_slow(s, flush)
1535    deflate_state *s;
1536    int flush;
1537{
1538    IPos hash_head = NIL;    /* head of hash chain */
1539    int bflush;              /* set if current block must be flushed */
1540
1541    /* Process the input block. */
1542    for (;;) {
1543        /* Make sure that we always have enough lookahead, except
1544         * at the end of the input file. We need MAX_MATCH bytes
1545         * for the next match, plus MIN_MATCH bytes to insert the
1546         * string following the next match.
1547         */
1548        if (s->lookahead < MIN_LOOKAHEAD) {
1549            fill_window(s);
1550            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1551                return need_more;
1552            }
1553            if (s->lookahead == 0) break; /* flush the current block */
1554        }
1555
1556        /* Insert the string window[strstart .. strstart+2] in the
1557         * dictionary, and set hash_head to the head of the hash chain:
1558         */
1559        if (s->lookahead >= MIN_MATCH) {
1560            INSERT_STRING(s, s->strstart, hash_head);
1561        }
1562
1563        /* Find the longest match, discarding those <= prev_length.
1564         */
1565        s->prev_length = s->match_length, s->prev_match = s->match_start;
1566        s->match_length = MIN_MATCH-1;
1567
1568        if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1569            s->strstart - hash_head <= MAX_DIST(s)) {
1570            /* To simplify the code, we prevent matches with the string
1571             * of window index 0 (in particular we have to avoid a match
1572             * of the string with itself at the start of the input file).
1573             */
1574            if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1575                s->match_length = longest_match (s, hash_head);
1576            } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1577                s->match_length = longest_match_fast (s, hash_head);
1578            }
1579            /* longest_match() or longest_match_fast() sets match_start */
1580
1581            if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1582#if TOO_FAR <= 32767
1583                || (s->match_length == MIN_MATCH &&
1584                    s->strstart - s->match_start > TOO_FAR)
1585#endif
1586                )) {
1587
1588                /* If prev_match is also MIN_MATCH, match_start is garbage
1589                 * but we will ignore the current match anyway.
1590                 */
1591                s->match_length = MIN_MATCH-1;
1592            }
1593        }
1594        /* If there was a match at the previous step and the current
1595         * match is not better, output the previous match:
1596         */
1597        if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1598            uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1599            /* Do not insert strings in hash table beyond this. */
1600
1601            check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1602
1603            _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1604                           s->prev_length - MIN_MATCH, bflush);
1605
1606            /* Insert in hash table all strings up to the end of the match.
1607             * strstart-1 and strstart are already inserted. If there is not
1608             * enough lookahead, the last two strings are not inserted in
1609             * the hash table.
1610             */
1611            s->lookahead -= s->prev_length-1;
1612            s->prev_length -= 2;
1613            do {
1614                if (++s->strstart <= max_insert) {
1615                    INSERT_STRING(s, s->strstart, hash_head);
1616                }
1617            } while (--s->prev_length != 0);
1618            s->match_available = 0;
1619            s->match_length = MIN_MATCH-1;
1620            s->strstart++;
1621
1622            if (bflush) FLUSH_BLOCK(s, 0);
1623
1624        } else if (s->match_available) {
1625            /* If there was no match at the previous position, output a
1626             * single literal. If there was a match but the current match
1627             * is longer, truncate the previous match to a single literal.
1628             */
1629            Tracevv((stderr,"%c", s->window[s->strstart-1]));
1630            _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1631            if (bflush) {
1632                FLUSH_BLOCK_ONLY(s, 0);
1633            }
1634            s->strstart++;
1635            s->lookahead--;
1636            if (s->strm->avail_out == 0) return need_more;
1637        } else {
1638            /* There is no previous match to compare with, wait for
1639             * the next step to decide.
1640             */
1641            s->match_available = 1;
1642            s->strstart++;
1643            s->lookahead--;
1644        }
1645    }
1646    Assert (flush != Z_NO_FLUSH, "no flush?");
1647    if (s->match_available) {
1648        Tracevv((stderr,"%c", s->window[s->strstart-1]));
1649        _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1650        s->match_available = 0;
1651    }
1652    FLUSH_BLOCK(s, flush == Z_FINISH);
1653    return flush == Z_FINISH ? finish_done : block_done;
1654}
1655#endif /* FASTEST */
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