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
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).
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.
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.
39 * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40 * Available in http://www.ietf.org/rfc/rfc1951.txt
42 * A description of the Rabin and Karp algorithm is given in the book
43 * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
45 * Fiala,E.R., and Greene,D.H.
46 * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
54 #define read_buf dread_buf
56 const char deflate_copyright[] =
57 " deflate 1.2.2 Copyright 1995-2004 Jean-loup Gailly ";
59 If you use the zlib library in a product, an acknowledgment is welcome
60 in the documentation of your product. If for some reason you cannot
61 include such an acknowledgment, I would appreciate that you keep this
62 copyright string in the executable of your product.
65 /* ===========================================================================
66 * Function prototypes.
69 need_more, /* block not completed, need more input or more output */
70 block_done, /* block flush performed */
71 finish_started, /* finish started, need only more output at next deflate */
72 finish_done /* finish done, accept no more input or output */
75 typedef block_state (*compress_func) OF((deflate_state *s, int flush));
76 /* Compression function. Returns the block state after the call. */
78 local void fill_window OF((deflate_state *s));
79 local block_state deflate_stored OF((deflate_state *s, int flush));
80 local block_state deflate_fast OF((deflate_state *s, int flush));
82 local block_state deflate_slow OF((deflate_state *s, int flush));
84 local void lm_init OF((deflate_state *s));
85 local void putShortMSB OF((deflate_state *s, uInt b));
86 local void flush_pending OF((z_streamp strm));
87 local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
90 void match_init OF((void)); /* asm code initialization */
91 uInt longest_match OF((deflate_state *s, IPos cur_match));
93 local uInt longest_match OF((deflate_state *s, IPos cur_match));
96 local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
99 local void check_match OF((deflate_state *s, IPos start, IPos match,
103 /* ===========================================================================
108 /* Tail of hash chains */
111 # define TOO_FAR 4096
113 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
115 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
116 /* Minimum amount of lookahead, except at the end of the input file.
117 * See deflate.c for comments about the MIN_MATCH+1.
120 /* Values for max_lazy_match, good_match and max_chain_length, depending on
121 * the desired pack level (0..9). The values given below have been tuned to
122 * exclude worst case performance for pathological files. Better values may be
123 * found for specific files.
125 typedef struct config_s {
126 ush good_length; /* reduce lazy search above this match length */
127 ush max_lazy; /* do not perform lazy search above this match length */
128 ush nice_length; /* quit search above this match length */
134 local const config configuration_table[2] = {
135 /* good lazy nice chain */
136 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
137 /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
139 local const config configuration_table[10] = {
140 /* good lazy nice chain */
141 /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
142 /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
143 /* 2 */ {4, 5, 16, 8, deflate_fast},
144 /* 3 */ {4, 6, 32, 32, deflate_fast},
146 /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
147 /* 5 */ {8, 16, 32, 32, deflate_slow},
148 /* 6 */ {8, 16, 128, 128, deflate_slow},
149 /* 7 */ {8, 32, 128, 256, deflate_slow},
150 /* 8 */ {32, 128, 258, 1024, deflate_slow},
151 /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
154 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
155 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
160 /* result of memcmp for equal strings */
162 #ifndef NO_DUMMY_DECL
163 struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
166 /* ===========================================================================
167 * Update a hash value with the given input byte
168 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
169 * input characters, so that a running hash key can be computed from the
170 * previous key instead of complete recalculation each time.
172 #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
175 /* ===========================================================================
176 * Insert string str in the dictionary and set match_head to the previous head
177 * of the hash chain (the most recent string with same hash key). Return
178 * the previous length of the hash chain.
179 * If this file is compiled with -DFASTEST, the compression level is forced
180 * to 1, and no hash chains are maintained.
181 * IN assertion: all calls to to INSERT_STRING are made with consecutive
182 * input characters and the first MIN_MATCH bytes of str are valid
183 * (except for the last MIN_MATCH-1 bytes of the input file).
186 #define INSERT_STRING(s, str, match_head) \
187 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
188 match_head = s->head[s->ins_h], \
189 s->head[s->ins_h] = (Pos)(str))
191 #define INSERT_STRING(s, str, match_head) \
192 (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
193 match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \
194 s->head[s->ins_h] = (Pos)(str))
197 /* ===========================================================================
198 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
199 * prev[] will be initialized on the fly.
201 #define CLEAR_HASH(s) \
202 s->head[s->hash_size-1] = NIL; \
203 zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
205 /* ========================================================================= */
206 int ZEXPORT deflateInit_(strm, level, version, stream_size)
212 return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
213 Z_DEFAULT_STRATEGY, version, stream_size);
214 /* To do: ignore strm->next_in if we use it as window */
217 /* ========================================================================= */
218 int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
219 version, stream_size)
231 static const char my_version[] = ZLIB_VERSION;
234 /* We overlay pending_buf and d_buf+l_buf. This works since the average
235 * output size for (length,distance) codes is <= 24 bits.
238 if (version == Z_NULL || version[0] != my_version[0] ||
239 stream_size != sizeof(z_stream)) {
240 return Z_VERSION_ERROR;
242 if (strm == Z_NULL) return Z_STREAM_ERROR;
245 if (strm->zalloc == (alloc_func)0) {
246 strm->zalloc = zcalloc;
247 strm->opaque = (voidpf)0;
249 if (strm->zfree == (free_func)0) strm->zfree = zcfree;
252 if (level != 0) level = 1;
254 if (level == Z_DEFAULT_COMPRESSION) level = 6;
257 if (windowBits < 0) { /* suppress zlib wrapper */
259 windowBits = -windowBits;
262 else if (windowBits > 15) {
263 wrap = 2; /* write gzip wrapper instead */
267 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
268 windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
269 strategy < 0 || strategy > Z_RLE) {
270 return Z_STREAM_ERROR;
272 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
273 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
274 if (s == Z_NULL) return Z_MEM_ERROR;
275 strm->state = (struct internal_state FAR *)s;
279 s->w_bits = windowBits;
280 s->w_size = 1 << s->w_bits;
281 s->w_mask = s->w_size - 1;
283 s->hash_bits = memLevel + 7;
284 s->hash_size = 1 << s->hash_bits;
285 s->hash_mask = s->hash_size - 1;
286 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
288 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
289 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
290 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
292 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
294 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
295 s->pending_buf = (uchf *) overlay;
296 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
298 if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
299 s->pending_buf == Z_NULL) {
300 s->status = FINISH_STATE;
301 strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
305 s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
306 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
309 s->strategy = strategy;
310 s->method = (Byte)method;
312 return deflateReset(strm);
315 /* ========================================================================= */
316 int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
318 const Bytef *dictionary;
322 uInt length = dictLength;
326 if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
327 strm->state->wrap == 2 ||
328 (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
329 return Z_STREAM_ERROR;
333 strm->adler = adler32(strm->adler, dictionary, dictLength);
335 if (length < MIN_MATCH) return Z_OK;
336 if (length > MAX_DIST(s)) {
337 length = MAX_DIST(s);
338 #ifndef USE_DICT_HEAD
339 dictionary += dictLength - length; /* use the tail of the dictionary */
342 zmemcpy(s->window, dictionary, length);
343 s->strstart = length;
344 s->block_start = (long)length;
346 /* Insert all strings in the hash table (except for the last two bytes).
347 * s->lookahead stays null, so s->ins_h will be recomputed at the next
348 * call of fill_window.
350 s->ins_h = s->window[0];
351 UPDATE_HASH(s, s->ins_h, s->window[1]);
352 for (n = 0; n <= length - MIN_MATCH; n++) {
353 INSERT_STRING(s, n, hash_head);
355 if (hash_head) hash_head = 0; /* to make compiler happy */
359 /* ========================================================================= */
360 int ZEXPORT deflateReset (strm)
365 if (strm == Z_NULL || strm->state == Z_NULL ||
366 strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
367 return Z_STREAM_ERROR;
370 strm->total_in = strm->total_out = 0;
371 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
372 strm->data_type = Z_UNKNOWN;
374 s = (deflate_state *)strm->state;
376 s->pending_out = s->pending_buf;
379 s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
381 s->status = s->wrap ? INIT_STATE : BUSY_STATE;
384 s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
386 adler32(0L, Z_NULL, 0);
387 s->last_flush = Z_NO_FLUSH;
395 /* ========================================================================= */
396 int ZEXPORT deflatePrime (strm, bits, value)
401 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
402 strm->state->bi_valid = bits;
403 strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
407 /* ========================================================================= */
408 int ZEXPORT deflateParams(strm, level, strategy)
417 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
421 if (level != 0) level = 1;
423 if (level == Z_DEFAULT_COMPRESSION) level = 6;
425 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_RLE) {
426 return Z_STREAM_ERROR;
428 func = configuration_table[s->level].func;
430 if (func != configuration_table[level].func && strm->total_in != 0) {
431 /* Flush the last buffer: */
432 err = deflate(strm, Z_PARTIAL_FLUSH);
434 if (s->level != level) {
436 s->max_lazy_match = configuration_table[level].max_lazy;
437 s->good_match = configuration_table[level].good_length;
438 s->nice_match = configuration_table[level].nice_length;
439 s->max_chain_length = configuration_table[level].max_chain;
441 s->strategy = strategy;
445 /* =========================================================================
446 * For the default windowBits of 15 and memLevel of 8, this function returns
447 * a close to exact, as well as small, upper bound on the compressed size.
448 * They are coded as constants here for a reason--if the #define's are
449 * changed, then this function needs to be changed as well. The return
450 * value for 15 and 8 only works for those exact settings.
452 * For any setting other than those defaults for windowBits and memLevel,
453 * the value returned is a conservative worst case for the maximum expansion
454 * resulting from using fixed blocks instead of stored blocks, which deflate
455 * can emit on compressed data for some combinations of the parameters.
457 * This function could be more sophisticated to provide closer upper bounds
458 * for every combination of windowBits and memLevel, as well as wrap.
459 * But even the conservative upper bound of about 14% expansion does not
460 * seem onerous for output buffer allocation.
462 uLong ZEXPORT deflateBound(strm, sourceLen)
469 /* conservative upper bound */
470 destLen = sourceLen +
471 ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
473 /* if can't get parameters, return conservative bound */
474 if (strm == Z_NULL || strm->state == Z_NULL)
477 /* if not default parameters, return conservative bound */
479 if (s->w_bits != 15 || s->hash_bits != 8 + 7)
482 /* default settings: return tight bound for that case */
483 return compressBound(sourceLen);
486 /* =========================================================================
487 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
488 * IN assertion: the stream state is correct and there is enough room in
491 local void putShortMSB (s, b)
495 put_byte(s, (Byte)(b >> 8));
496 put_byte(s, (Byte)(b & 0xff));
499 /* =========================================================================
500 * Flush as much pending output as possible. All deflate() output goes
501 * through this function so some applications may wish to modify it
502 * to avoid allocating a large strm->next_out buffer and copying into it.
503 * (See also read_buf()).
505 local void flush_pending(strm)
508 unsigned len = strm->state->pending;
510 if (len > strm->avail_out) len = strm->avail_out;
511 if (len == 0) return;
513 zmemcpy(strm->next_out, strm->state->pending_out, len);
514 strm->next_out += len;
515 strm->state->pending_out += len;
516 strm->total_out += len;
517 strm->avail_out -= len;
518 strm->state->pending -= len;
519 if (strm->state->pending == 0) {
520 strm->state->pending_out = strm->state->pending_buf;
524 /* ========================================================================= */
525 int ZEXPORT deflate (strm, flush)
529 int old_flush; /* value of flush param for previous deflate call */
532 if (strm == Z_NULL || strm->state == Z_NULL ||
533 flush > Z_INSERT_ONLY || flush < 0) {
534 return Z_STREAM_ERROR;
538 if (strm->next_out == Z_NULL ||
539 (strm->next_in == Z_NULL && strm->avail_in != 0) ||
540 (s->status == FINISH_STATE && flush != Z_FINISH)) {
541 ERR_RETURN(strm, Z_STREAM_ERROR);
543 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
545 s->strm = strm; /* just in case */
546 old_flush = s->last_flush;
547 s->last_flush = flush;
549 /* Write the header */
550 if (s->status == INIT_STATE) {
561 put_byte(s, s->level == 9 ? 2 :
562 (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
565 s->status = BUSY_STATE;
566 strm->adler = crc32(0L, Z_NULL, 0);
571 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
574 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
576 else if (s->level < 6)
578 else if (s->level == 6)
582 header |= (level_flags << 6);
583 if (s->strstart != 0) header |= PRESET_DICT;
584 header += 31 - (header % 31);
586 s->status = BUSY_STATE;
587 putShortMSB(s, header);
589 /* Save the adler32 of the preset dictionary: */
590 if (s->strstart != 0) {
591 putShortMSB(s, (uInt)(strm->adler >> 16));
592 putShortMSB(s, (uInt)(strm->adler & 0xffff));
594 strm->adler = adler32(0L, Z_NULL, 0);
598 /* Flush as much pending output as possible */
599 if (s->pending != 0) {
601 if (strm->avail_out == 0) {
602 /* Since avail_out is 0, deflate will be called again with
603 * more output space, but possibly with both pending and
604 * avail_in equal to zero. There won't be anything to do,
605 * but this is not an error situation so make sure we
606 * return OK instead of BUF_ERROR at next call of deflate:
612 /* Make sure there is something to do and avoid duplicate consecutive
613 * flushes. For repeated and useless calls with Z_FINISH, we keep
614 * returning Z_STREAM_END instead of Z_BUF_ERROR.
616 } else if (strm->avail_in == 0 && flush <= old_flush &&
618 ERR_RETURN(strm, Z_BUF_ERROR);
621 /* User must not provide more input after the first FINISH: */
622 if (s->status == FINISH_STATE && strm->avail_in != 0) {
623 ERR_RETURN(strm, Z_BUF_ERROR);
626 /* Start a new block or continue the current one.
628 if (strm->avail_in != 0 || s->lookahead != 0 ||
629 (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
632 bstate = (*(configuration_table[s->level].func))(s, flush);
634 if (bstate == finish_started || bstate == finish_done) {
635 s->status = FINISH_STATE;
637 if (bstate == need_more || bstate == finish_started) {
638 if (strm->avail_out == 0) {
639 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
642 /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
643 * of deflate should use the same flush parameter to make sure
644 * that the flush is complete. So we don't have to output an
645 * empty block here, this will be done at next call. This also
646 * ensures that for a very small output buffer, we emit at most
650 if (bstate == block_done) {
651 if (flush == Z_PARTIAL_FLUSH) {
653 } else { /* FULL_FLUSH or SYNC_FLUSH */
654 _tr_stored_block(s, (char*)0, 0L, 0);
655 /* For a full flush, this empty block will be recognized
656 * as a special marker by inflate_sync().
658 if (flush == Z_FULL_FLUSH) {
659 CLEAR_HASH(s); /* forget history */
663 if (strm->avail_out == 0) {
664 s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
669 Assert(strm->avail_out > 0, "bug2");
671 if (flush != Z_FINISH) return Z_OK;
672 if (s->wrap <= 0) return Z_STREAM_END;
674 /* Write the trailer */
677 put_byte(s, (Byte)(strm->adler & 0xff));
678 put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
679 put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
680 put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
681 put_byte(s, (Byte)(strm->total_in & 0xff));
682 put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
683 put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
684 put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
689 putShortMSB(s, (uInt)(strm->adler >> 16));
690 putShortMSB(s, (uInt)(strm->adler & 0xffff));
693 /* If avail_out is zero, the application will call deflate again
696 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
697 return s->pending != 0 ? Z_OK : Z_STREAM_END;
700 /* ========================================================================= */
701 int ZEXPORT deflateEnd (strm)
706 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
708 status = strm->state->status;
709 if (status != INIT_STATE && status != BUSY_STATE &&
710 status != FINISH_STATE) {
711 return Z_STREAM_ERROR;
714 /* Deallocate in reverse order of allocations: */
715 TRY_FREE(strm, strm->state->pending_buf);
716 TRY_FREE(strm, strm->state->head);
717 TRY_FREE(strm, strm->state->prev);
718 TRY_FREE(strm, strm->state->window);
720 ZFREE(strm, strm->state);
721 strm->state = Z_NULL;
723 return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
726 /* =========================================================================
727 * Copy the source state to the destination state.
728 * To simplify the source, this is not supported for 16-bit MSDOS (which
729 * doesn't have enough memory anyway to duplicate compression states).
731 int ZEXPORT deflateCopy (dest, source)
736 return Z_STREAM_ERROR;
743 if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
744 return Z_STREAM_ERROR;
751 ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
752 if (ds == Z_NULL) return Z_MEM_ERROR;
753 dest->state = (struct internal_state FAR *) ds;
757 ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
758 ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
759 ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
760 overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
761 ds->pending_buf = (uchf *) overlay;
763 if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
764 ds->pending_buf == Z_NULL) {
768 /* following zmemcpy do not work for 16-bit MSDOS */
769 zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
770 zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
771 zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
772 zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
774 ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
775 ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
776 ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
778 ds->l_desc.dyn_tree = ds->dyn_ltree;
779 ds->d_desc.dyn_tree = ds->dyn_dtree;
780 ds->bl_desc.dyn_tree = ds->bl_tree;
783 #endif /* MAXSEG_64K */
786 /* ===========================================================================
787 * Read a new buffer from the current input stream, update the adler32
788 * and total number of bytes read. All deflate() input goes through
789 * this function so some applications may wish to modify it to avoid
790 * allocating a large strm->next_in buffer and copying from it.
791 * (See also flush_pending()).
793 local int read_buf(strm, buf, size)
798 unsigned len = strm->avail_in;
800 if (len > size) len = size;
801 if (len == 0) return 0;
803 strm->avail_in -= len;
805 if (strm->state->wrap == 1) {
806 strm->adler = adler32(strm->adler, strm->next_in, len);
809 else if (strm->state->wrap == 2) {
810 strm->adler = crc32(strm->adler, strm->next_in, len);
813 zmemcpy(buf, strm->next_in, len);
814 strm->next_in += len;
815 strm->total_in += len;
820 /* ===========================================================================
821 * Initialize the "longest match" routines for a new zlib stream
823 local void lm_init (s)
826 s->window_size = (ulg)2L*s->w_size;
830 /* Set the default configuration parameters:
832 s->max_lazy_match = configuration_table[s->level].max_lazy;
833 s->good_match = configuration_table[s->level].good_length;
834 s->nice_match = configuration_table[s->level].nice_length;
835 s->max_chain_length = configuration_table[s->level].max_chain;
840 s->match_length = s->prev_length = MIN_MATCH-1;
841 s->match_available = 0;
844 match_init(); /* initialize the asm code */
849 /* ===========================================================================
850 * Set match_start to the longest match starting at the given string and
851 * return its length. Matches shorter or equal to prev_length are discarded,
852 * in which case the result is equal to prev_length and match_start is
854 * IN assertions: cur_match is the head of the hash chain for the current
855 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
856 * OUT assertion: the match length is not greater than s->lookahead.
859 /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
860 * match.S. The code will be functionally equivalent.
862 local uInt longest_match(s, cur_match)
864 IPos cur_match; /* current match */
866 unsigned chain_length = s->max_chain_length;/* max hash chain length */
867 register Bytef *scan = s->window + s->strstart; /* current string */
868 register Bytef *match; /* matched string */
869 register int len; /* length of current match */
870 int best_len = s->prev_length; /* best match length so far */
871 int nice_match = s->nice_match; /* stop if match long enough */
872 IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
873 s->strstart - (IPos)MAX_DIST(s) : NIL;
874 /* Stop when cur_match becomes <= limit. To simplify the code,
875 * we prevent matches with the string of window index 0.
877 Posf *prev = s->prev;
878 uInt wmask = s->w_mask;
881 /* Compare two bytes at a time. Note: this is not always beneficial.
882 * Try with and without -DUNALIGNED_OK to check.
884 register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
885 register ush scan_start = *(ushf*)scan;
886 register ush scan_end = *(ushf*)(scan+best_len-1);
888 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
889 register Byte scan_end1 = scan[best_len-1];
890 register Byte scan_end = scan[best_len];
893 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
894 * It is easy to get rid of this optimization if necessary.
896 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
898 /* Do not waste too much time if we already have a good match: */
899 if (s->prev_length >= s->good_match) {
902 /* Do not look for matches beyond the end of the input. This is necessary
903 * to make deflate deterministic.
905 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
907 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
910 Assert(cur_match < s->strstart, "no future");
911 match = s->window + cur_match;
913 /* Skip to next match if the match length cannot increase
914 * or if the match length is less than 2:
916 #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
917 /* This code assumes sizeof(unsigned short) == 2. Do not use
918 * UNALIGNED_OK if your compiler uses a different size.
920 if (*(ushf*)(match+best_len-1) != scan_end ||
921 *(ushf*)match != scan_start) continue;
923 /* It is not necessary to compare scan[2] and match[2] since they are
924 * always equal when the other bytes match, given that the hash keys
925 * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
926 * strstart+3, +5, ... up to strstart+257. We check for insufficient
927 * lookahead only every 4th comparison; the 128th check will be made
928 * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
929 * necessary to put more guard bytes at the end of the window, or
930 * to check more often for insufficient lookahead.
932 Assert(scan[2] == match[2], "scan[2]?");
935 } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
936 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
937 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
938 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
940 /* The funny "do {}" generates better code on most compilers */
942 /* Here, scan <= window+strstart+257 */
943 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
944 if (*scan == *match) scan++;
946 len = (MAX_MATCH - 1) - (int)(strend-scan);
947 scan = strend - (MAX_MATCH-1);
949 #else /* UNALIGNED_OK */
951 if (match[best_len] != scan_end ||
952 match[best_len-1] != scan_end1 ||
954 *++match != scan[1]) continue;
956 /* The check at best_len-1 can be removed because it will be made
957 * again later. (This heuristic is not always a win.)
958 * It is not necessary to compare scan[2] and match[2] since they
959 * are always equal when the other bytes match, given that
960 * the hash keys are equal and that HASH_BITS >= 8.
963 Assert(*scan == *match, "match[2]?");
965 /* We check for insufficient lookahead only every 8th comparison;
966 * the 256th check will be made at strstart+258.
969 } while (*++scan == *++match && *++scan == *++match &&
970 *++scan == *++match && *++scan == *++match &&
971 *++scan == *++match && *++scan == *++match &&
972 *++scan == *++match && *++scan == *++match &&
975 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
977 len = MAX_MATCH - (int)(strend - scan);
978 scan = strend - MAX_MATCH;
980 #endif /* UNALIGNED_OK */
982 if (len > best_len) {
983 s->match_start = cur_match;
985 if (len >= nice_match) break;
987 scan_end = *(ushf*)(scan+best_len-1);
989 scan_end1 = scan[best_len-1];
990 scan_end = scan[best_len];
993 } while ((cur_match = prev[cur_match & wmask]) > limit
994 && --chain_length != 0);
996 if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1000 #endif /* FASTEST */
1002 /* ---------------------------------------------------------------------------
1003 * Optimized version for level == 1 or strategy == Z_RLE only
1005 local uInt longest_match_fast(s, cur_match)
1007 IPos cur_match; /* current match */
1009 register Bytef *scan = s->window + s->strstart; /* current string */
1010 register Bytef *match; /* matched string */
1011 register int len; /* length of current match */
1012 register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1014 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1015 * It is easy to get rid of this optimization if necessary.
1017 Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1019 Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1021 Assert(cur_match < s->strstart, "no future");
1023 match = s->window + cur_match;
1025 /* Return failure if the match length is less than 2:
1027 if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1029 /* The check at best_len-1 can be removed because it will be made
1030 * again later. (This heuristic is not always a win.)
1031 * It is not necessary to compare scan[2] and match[2] since they
1032 * are always equal when the other bytes match, given that
1033 * the hash keys are equal and that HASH_BITS >= 8.
1035 scan += 2, match += 2;
1036 Assert(*scan == *match, "match[2]?");
1038 /* We check for insufficient lookahead only every 8th comparison;
1039 * the 256th check will be made at strstart+258.
1042 } while (*++scan == *++match && *++scan == *++match &&
1043 *++scan == *++match && *++scan == *++match &&
1044 *++scan == *++match && *++scan == *++match &&
1045 *++scan == *++match && *++scan == *++match &&
1048 Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1050 len = MAX_MATCH - (int)(strend - scan);
1052 if (len < MIN_MATCH) return MIN_MATCH - 1;
1054 s->match_start = cur_match;
1055 return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1059 /* ===========================================================================
1060 * Check that the match at match_start is indeed a match.
1062 local void check_match(s, start, match, length)
1067 /* check that the match is indeed a match */
1068 if (zmemcmp(s->window + match,
1069 s->window + start, length) != EQUAL) {
1070 fprintf(stderr, " start %u, match %u, length %d\n",
1071 start, match, length);
1073 fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1074 } while (--length != 0);
1075 z_error("invalid match");
1077 if (z_verbose > 1) {
1078 fprintf(stderr,"\\[%d,%d]", start-match, length);
1079 do { putc(s->window[start++], stderr); } while (--length != 0);
1083 # define check_match(s, start, match, length)
1086 /* ===========================================================================
1087 * Fill the window when the lookahead becomes insufficient.
1088 * Updates strstart and lookahead.
1090 * IN assertion: lookahead < MIN_LOOKAHEAD
1091 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1092 * At least one byte has been read, or avail_in == 0; reads are
1093 * performed for at least two bytes (required for the zip translate_eol
1094 * option -- not supported here).
1096 local void fill_window(s)
1099 register unsigned n, m;
1101 unsigned more; /* Amount of free space at the end of the window. */
1102 uInt wsize = s->w_size;
1105 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1107 /* Deal with !@#$% 64K limit: */
1108 if (sizeof(int) <= 2) {
1109 if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1112 } else if (more == (unsigned)(-1)) {
1113 /* Very unlikely, but possible on 16 bit machine if
1114 * strstart == 0 && lookahead == 1 (input done a byte at time)
1120 /* If the window is almost full and there is insufficient lookahead,
1121 * move the upper half to the lower one to make room in the upper half.
1123 if (s->strstart >= wsize+MAX_DIST(s)) {
1125 zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1126 s->match_start -= wsize;
1127 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1128 s->block_start -= (long) wsize;
1130 /* Slide the hash table (could be avoided with 32 bit values
1131 at the expense of memory usage). We slide even when level == 0
1132 to keep the hash table consistent if we switch back to level > 0
1133 later. (Using level 0 permanently is not an optimal usage of
1134 zlib, so we don't care about this pathological case.)
1140 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1148 *p = (Pos)(m >= wsize ? m-wsize : NIL);
1149 /* If n is not on any hash chain, prev[n] is garbage but
1150 * its value will never be used.
1156 if (s->strm->avail_in == 0) return;
1158 /* If there was no sliding:
1159 * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1160 * more == window_size - lookahead - strstart
1161 * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1162 * => more >= window_size - 2*WSIZE + 2
1163 * In the BIG_MEM or MMAP case (not yet supported),
1164 * window_size == input_size + MIN_LOOKAHEAD &&
1165 * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1166 * Otherwise, window_size == 2*WSIZE so more >= 2.
1167 * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1169 Assert(more >= 2, "more < 2");
1171 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1174 /* Initialize the hash value now that we have some input: */
1175 if (s->lookahead >= MIN_MATCH) {
1176 s->ins_h = s->window[s->strstart];
1177 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1179 Call UPDATE_HASH() MIN_MATCH-3 more times
1182 /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1183 * but this is not important since only literal bytes will be emitted.
1186 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1189 /* ===========================================================================
1190 * Flush the current block, with given end-of-file flag.
1191 * IN assertion: strstart is set to the end of the current match.
1193 #define FLUSH_BLOCK_ONLY(s, eof) { \
1194 _tr_flush_block(s, (s->block_start >= 0L ? \
1195 (charf *)&s->window[(unsigned)s->block_start] : \
1197 (ulg)((long)s->strstart - s->block_start), \
1199 s->block_start = s->strstart; \
1200 flush_pending(s->strm); \
1201 Tracev((stderr,"[FLUSH]")); \
1204 /* Same but force premature exit if necessary. */
1205 #define FLUSH_BLOCK(s, eof) { \
1206 FLUSH_BLOCK_ONLY(s, eof); \
1207 if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1210 /* ===========================================================================
1211 * Copy without compression as much as possible from the input stream, return
1212 * the current block state.
1213 * This function does not insert new strings in the dictionary since
1214 * uncompressible data is probably not useful. This function is used
1215 * only for the level=0 compression option.
1216 * NOTE: this function should be optimized to avoid extra copying from
1217 * window to pending_buf.
1219 local block_state deflate_stored(s, flush)
1223 /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1224 * to pending_buf_size, and each stored block has a 5 byte header:
1226 ulg max_block_size = 0xffff;
1229 if (max_block_size > s->pending_buf_size - 5) {
1230 max_block_size = s->pending_buf_size - 5;
1233 /* Copy as much as possible from input to output: */
1235 /* Fill the window as much as possible: */
1236 if (s->lookahead <= 1) {
1238 Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1239 s->block_start >= (long)s->w_size, "slide too late");
1242 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1244 if (s->lookahead == 0) break; /* flush the current block */
1246 Assert(s->block_start >= 0L, "block gone");
1248 s->strstart += s->lookahead;
1251 if (flush == Z_INSERT_ONLY) {
1252 s->block_start = s->strstart;
1256 /* Emit a stored block if pending_buf will be full: */
1257 max_start = s->block_start + max_block_size;
1258 if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1259 /* strstart == 0 is possible when wraparound on 16-bit machine */
1260 s->lookahead = (uInt)(s->strstart - max_start);
1261 s->strstart = (uInt)max_start;
1264 /* Flush if we may have to slide, otherwise block_start may become
1265 * negative and the data will be gone:
1267 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1271 if (flush == Z_INSERT_ONLY) {
1272 s->block_start = s->strstart;
1276 FLUSH_BLOCK(s, flush == Z_FINISH);
1277 return flush == Z_FINISH ? finish_done : block_done;
1280 /* ===========================================================================
1281 * Compress as much as possible from the input stream, return the current
1283 * This function does not perform lazy evaluation of matches and inserts
1284 * new strings in the dictionary only for unmatched strings or for short
1285 * matches. It is used only for the fast compression options.
1287 local block_state deflate_fast(s, flush)
1291 IPos hash_head = NIL; /* head of the hash chain */
1292 int bflush; /* set if current block must be flushed */
1295 /* Make sure that we always have enough lookahead, except
1296 * at the end of the input file. We need MAX_MATCH bytes
1297 * for the next match, plus MIN_MATCH bytes to insert the
1298 * string following the next match.
1300 if (s->lookahead < MIN_LOOKAHEAD) {
1302 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1305 if (s->lookahead == 0) break; /* flush the current block */
1308 /* Insert the string window[strstart .. strstart+2] in the
1309 * dictionary, and set hash_head to the head of the hash chain:
1311 if (s->lookahead >= MIN_MATCH) {
1312 INSERT_STRING(s, s->strstart, hash_head);
1315 if (flush == Z_INSERT_ONLY) {
1321 /* Find the longest match, discarding those <= prev_length.
1322 * At this point we have always match_length < MIN_MATCH
1324 if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1325 /* To simplify the code, we prevent matches with the string
1326 * of window index 0 (in particular we have to avoid a match
1327 * of the string with itself at the start of the input file).
1330 if ((s->strategy < Z_HUFFMAN_ONLY) ||
1331 (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
1332 s->match_length = longest_match_fast (s, hash_head);
1335 if (s->strategy < Z_HUFFMAN_ONLY) {
1336 s->match_length = longest_match (s, hash_head);
1337 } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1338 s->match_length = longest_match_fast (s, hash_head);
1341 /* longest_match() or longest_match_fast() sets match_start */
1343 if (s->match_length >= MIN_MATCH) {
1344 check_match(s, s->strstart, s->match_start, s->match_length);
1346 _tr_tally_dist(s, s->strstart - s->match_start,
1347 s->match_length - MIN_MATCH, bflush);
1349 s->lookahead -= s->match_length;
1351 /* Insert new strings in the hash table only if the match length
1352 * is not too large. This saves time but degrades compression.
1355 if (s->match_length <= s->max_insert_length &&
1356 s->lookahead >= MIN_MATCH) {
1357 s->match_length--; /* string at strstart already in table */
1360 INSERT_STRING(s, s->strstart, hash_head);
1361 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1362 * always MIN_MATCH bytes ahead.
1364 } while (--s->match_length != 0);
1369 s->strstart += s->match_length;
1370 s->match_length = 0;
1371 s->ins_h = s->window[s->strstart];
1372 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1374 Call UPDATE_HASH() MIN_MATCH-3 more times
1376 /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1377 * matter since it will be recomputed at next deflate call.
1381 /* No match, output a literal byte */
1382 Tracevv((stderr,"%c", s->window[s->strstart]));
1383 _tr_tally_lit (s, s->window[s->strstart], bflush);
1387 if (bflush) FLUSH_BLOCK(s, 0);
1389 if (flush == Z_INSERT_ONLY) {
1390 s->block_start = s->strstart;
1393 FLUSH_BLOCK(s, flush == Z_FINISH);
1394 return flush == Z_FINISH ? finish_done : block_done;
1398 /* ===========================================================================
1399 * Same as above, but achieves better compression. We use a lazy
1400 * evaluation for matches: a match is finally adopted only if there is
1401 * no better match at the next window position.
1403 local block_state deflate_slow(s, flush)
1407 IPos hash_head = NIL; /* head of hash chain */
1408 int bflush; /* set if current block must be flushed */
1410 /* Process the input block. */
1412 /* Make sure that we always have enough lookahead, except
1413 * at the end of the input file. We need MAX_MATCH bytes
1414 * for the next match, plus MIN_MATCH bytes to insert the
1415 * string following the next match.
1417 if (s->lookahead < MIN_LOOKAHEAD) {
1419 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1422 if (s->lookahead == 0) break; /* flush the current block */
1425 /* Insert the string window[strstart .. strstart+2] in the
1426 * dictionary, and set hash_head to the head of the hash chain:
1428 if (s->lookahead >= MIN_MATCH) {
1429 INSERT_STRING(s, s->strstart, hash_head);
1432 if (flush == Z_INSERT_ONLY) {
1438 /* Find the longest match, discarding those <= prev_length.
1440 s->prev_length = s->match_length, s->prev_match = s->match_start;
1441 s->match_length = MIN_MATCH-1;
1443 if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1444 s->strstart - hash_head <= MAX_DIST(s)) {
1445 /* To simplify the code, we prevent matches with the string
1446 * of window index 0 (in particular we have to avoid a match
1447 * of the string with itself at the start of the input file).
1449 if (s->strategy < Z_HUFFMAN_ONLY) {
1450 s->match_length = longest_match (s, hash_head);
1451 } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1452 s->match_length = longest_match_fast (s, hash_head);
1454 /* longest_match() or longest_match_fast() sets match_start */
1456 if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1457 #if TOO_FAR <= 32767
1458 || (s->match_length == MIN_MATCH &&
1459 s->strstart - s->match_start > TOO_FAR)
1463 /* If prev_match is also MIN_MATCH, match_start is garbage
1464 * but we will ignore the current match anyway.
1466 s->match_length = MIN_MATCH-1;
1469 /* If there was a match at the previous step and the current
1470 * match is not better, output the previous match:
1472 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1473 uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1474 /* Do not insert strings in hash table beyond this. */
1476 check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1478 _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1479 s->prev_length - MIN_MATCH, bflush);
1481 /* Insert in hash table all strings up to the end of the match.
1482 * strstart-1 and strstart are already inserted. If there is not
1483 * enough lookahead, the last two strings are not inserted in
1486 s->lookahead -= s->prev_length-1;
1487 s->prev_length -= 2;
1489 if (++s->strstart <= max_insert) {
1490 INSERT_STRING(s, s->strstart, hash_head);
1492 } while (--s->prev_length != 0);
1493 s->match_available = 0;
1494 s->match_length = MIN_MATCH-1;
1497 if (bflush) FLUSH_BLOCK(s, 0);
1499 } else if (s->match_available) {
1500 /* If there was no match at the previous position, output a
1501 * single literal. If there was a match but the current match
1502 * is longer, truncate the previous match to a single literal.
1504 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1505 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1507 FLUSH_BLOCK_ONLY(s, 0);
1511 if (s->strm->avail_out == 0) return need_more;
1513 /* There is no previous match to compare with, wait for
1514 * the next step to decide.
1516 s->match_available = 1;
1521 if (flush == Z_INSERT_ONLY) {
1522 s->block_start = s->strstart;
1525 Assert (flush != Z_NO_FLUSH, "no flush?");
1526 if (s->match_available) {
1527 Tracevv((stderr,"%c", s->window[s->strstart-1]));
1528 _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1529 s->match_available = 0;
1531 FLUSH_BLOCK(s, flush == Z_FINISH);
1532 return flush == Z_FINISH ? finish_done : block_done;
1534 #endif /* FASTEST */