File:
[ELWIX - Embedded LightWeight unIX -] /
embedaddon /
sudo /
zlib /
deflate.c
Revision
1.1.1.2 (vendor branch):
download - view:
text,
annotated -
select for diffs -
revision graph
Mon Jul 22 10:46:14 2013 UTC (10 years, 11 months ago) by
misho
Branches:
sudo,
MAIN
CVS tags:
v1_8_8p0,
v1_8_8,
v1_8_7p0,
v1_8_7,
v1_8_5p1,
v1_8_10p3_0,
v1_8_10p3,
HEAD
1.8.7
1: /* deflate.c -- compress data using the deflation algorithm
2: * Copyright (C) 1995-2012 Jean-loup Gailly and Mark Adler
3: * For conditions of distribution and use, see copyright notice in zlib.h
4: */
5:
6: /*
7: * ALGORITHM
8: *
9: * The "deflation" process depends on being able to identify portions
10: * of the input text which are identical to earlier input (within a
11: * sliding window trailing behind the input currently being processed).
12: *
13: * The most straightforward technique turns out to be the fastest for
14: * most input files: try all possible matches and select the longest.
15: * The key feature of this algorithm is that insertions into the string
16: * dictionary are very simple and thus fast, and deletions are avoided
17: * completely. Insertions are performed at each input character, whereas
18: * string matches are performed only when the previous match ends. So it
19: * is preferable to spend more time in matches to allow very fast string
20: * insertions and avoid deletions. The matching algorithm for small
21: * strings is inspired from that of Rabin & Karp. A brute force approach
22: * is used to find longer strings when a small match has been found.
23: * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
24: * (by Leonid Broukhis).
25: * A previous version of this file used a more sophisticated algorithm
26: * (by Fiala and Greene) which is guaranteed to run in linear amortized
27: * time, but has a larger average cost, uses more memory and is patented.
28: * However the F&G algorithm may be faster for some highly redundant
29: * files if the parameter max_chain_length (described below) is too large.
30: *
31: * ACKNOWLEDGEMENTS
32: *
33: * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
34: * I found it in 'freeze' written by Leonid Broukhis.
35: * Thanks to many people for bug reports and testing.
36: *
37: * REFERENCES
38: *
39: * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40: * Available in http://tools.ietf.org/html/rfc1951
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: deflate.c,v 1.1.1.2 2013/07/22 10:46:14 misho Exp $ */
51:
52: #include "deflate.h"
53:
54: const char deflate_copyright[] =
55: " deflate 1.2.6 Copyright 1995-2012 Jean-loup Gailly and Mark Adler ";
56: /*
57: If you use the zlib library in a product, an acknowledgment is welcome
58: in the documentation of your product. If for some reason you cannot
59: include such an acknowledgment, I would appreciate that you keep this
60: copyright string in the executable of your product.
61: */
62:
63: /* ===========================================================================
64: * Function prototypes.
65: */
66: typedef enum {
67: need_more, /* block not completed, need more input or more output */
68: block_done, /* block flush performed */
69: finish_started, /* finish started, need only more output at next deflate */
70: finish_done /* finish done, accept no more input or output */
71: } block_state;
72:
73: typedef block_state (*compress_func) OF((deflate_state *s, int flush));
74: /* Compression function. Returns the block state after the call. */
75:
76: local void fill_window OF((deflate_state *s));
77: local block_state deflate_stored OF((deflate_state *s, int flush));
78: local block_state deflate_fast OF((deflate_state *s, int flush));
79: #ifndef FASTEST
80: local block_state deflate_slow OF((deflate_state *s, int flush));
81: #endif
82: local block_state deflate_rle OF((deflate_state *s, int flush));
83: local block_state deflate_huff OF((deflate_state *s, int flush));
84: local void lm_init OF((deflate_state *s));
85: local void putShortMSB OF((deflate_state *s, uInt b));
86: local void flush_pending OF((z_streamp strm));
87: local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));
88: #ifdef ASMV
89: void match_init OF((void)); /* asm code initialization */
90: uInt longest_match OF((deflate_state *s, IPos cur_match));
91: #else
92: local uInt longest_match OF((deflate_state *s, IPos cur_match));
93: #endif
94:
95: #ifdef DEBUG
96: local void check_match OF((deflate_state *s, IPos start, IPos match,
97: int length));
98: #endif
99:
100: /* ===========================================================================
101: * Local data
102: */
103:
104: #define NIL 0
105: /* Tail of hash chains */
106:
107: #ifndef TOO_FAR
108: # define TOO_FAR 4096
109: #endif
110: /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
111:
112: /* Values for max_lazy_match, good_match and max_chain_length, depending on
113: * the desired pack level (0..9). The values given below have been tuned to
114: * exclude worst case performance for pathological files. Better values may be
115: * found for specific files.
116: */
117: typedef struct config_s {
118: ush good_length; /* reduce lazy search above this match length */
119: ush max_lazy; /* do not perform lazy search above this match length */
120: ush nice_length; /* quit search above this match length */
121: ush max_chain;
122: compress_func func;
123: } config;
124:
125: #ifdef FASTEST
126: local const config configuration_table[2] = {
127: /* good lazy nice chain */
128: /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
129: /* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */
130: #else
131: local const config configuration_table[10] = {
132: /* good lazy nice chain */
133: /* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */
134: /* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */
135: /* 2 */ {4, 5, 16, 8, deflate_fast},
136: /* 3 */ {4, 6, 32, 32, deflate_fast},
137:
138: /* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */
139: /* 5 */ {8, 16, 32, 32, deflate_slow},
140: /* 6 */ {8, 16, 128, 128, deflate_slow},
141: /* 7 */ {8, 32, 128, 256, deflate_slow},
142: /* 8 */ {32, 128, 258, 1024, deflate_slow},
143: /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */
144: #endif
145:
146: /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
147: * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
148: * meaning.
149: */
150:
151: #define EQUAL 0
152: /* result of memcmp for equal strings */
153:
154: #ifndef NO_DUMMY_DECL
155: struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
156: #endif
157:
158: /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */
159: #define RANK(f) (((f) << 1) - ((f) > 4 ? 9 : 0))
160:
161: /* ===========================================================================
162: * Update a hash value with the given input byte
163: * IN assertion: all calls to to UPDATE_HASH are made with consecutive
164: * input characters, so that a running hash key can be computed from the
165: * previous key instead of complete recalculation each time.
166: */
167: #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
168:
169:
170: /* ===========================================================================
171: * Insert string str in the dictionary and set match_head to the previous head
172: * of the hash chain (the most recent string with same hash key). Return
173: * the previous length of the hash chain.
174: * If this file is compiled with -DFASTEST, the compression level is forced
175: * to 1, and no hash chains are maintained.
176: * IN assertion: all calls to to INSERT_STRING are made with consecutive
177: * input characters and the first MIN_MATCH bytes of str are valid
178: * (except for the last MIN_MATCH-1 bytes of the input file).
179: */
180: #ifdef FASTEST
181: #define INSERT_STRING(s, str, match_head) \
182: (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
183: match_head = s->head[s->ins_h], \
184: s->head[s->ins_h] = (Pos)(str))
185: #else
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->prev[(str) & s->w_mask] = s->head[s->ins_h], \
189: s->head[s->ins_h] = (Pos)(str))
190: #endif
191:
192: /* ===========================================================================
193: * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
194: * prev[] will be initialized on the fly.
195: */
196: #define CLEAR_HASH(s) \
197: s->head[s->hash_size-1] = NIL; \
198: zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));
199:
200: /* ========================================================================= */
201: int ZEXPORT deflateInit_(strm, level, version, stream_size)
202: z_streamp strm;
203: int level;
204: const char *version;
205: int stream_size;
206: {
207: return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
208: Z_DEFAULT_STRATEGY, version, stream_size);
209: /* To do: ignore strm->next_in if we use it as window */
210: }
211:
212: /* ========================================================================= */
213: int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
214: version, stream_size)
215: z_streamp strm;
216: int level;
217: int method;
218: int windowBits;
219: int memLevel;
220: int strategy;
221: const char *version;
222: int stream_size;
223: {
224: deflate_state *s;
225: int wrap = 1;
226: static const char my_version[] = ZLIB_VERSION;
227:
228: ushf *overlay;
229: /* We overlay pending_buf and d_buf+l_buf. This works since the average
230: * output size for (length,distance) codes is <= 24 bits.
231: */
232:
233: if (version == Z_NULL || version[0] != my_version[0] ||
234: stream_size != sizeof(z_stream)) {
235: return Z_VERSION_ERROR;
236: }
237: if (strm == Z_NULL) return Z_STREAM_ERROR;
238:
239: strm->msg = Z_NULL;
240: if (strm->zalloc == (alloc_func)0) {
241: #ifdef Z_SOLO
242: return Z_STREAM_ERROR;
243: #else
244: strm->zalloc = zcalloc;
245: strm->opaque = (voidpf)0;
246: #endif
247: }
248: if (strm->zfree == (free_func)0)
249: #ifdef Z_SOLO
250: return Z_STREAM_ERROR;
251: #else
252: strm->zfree = zcfree;
253: #endif
254:
255: #ifdef FASTEST
256: if (level != 0) level = 1;
257: #else
258: if (level == Z_DEFAULT_COMPRESSION) level = 6;
259: #endif
260:
261: if (windowBits < 0) { /* suppress zlib wrapper */
262: wrap = 0;
263: windowBits = -windowBits;
264: }
265: #ifdef GZIP
266: else if (windowBits > 15) {
267: wrap = 2; /* write gzip wrapper instead */
268: windowBits -= 16;
269: }
270: #endif
271: if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
272: windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
273: strategy < 0 || strategy > Z_FIXED) {
274: return Z_STREAM_ERROR;
275: }
276: if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */
277: s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
278: if (s == Z_NULL) return Z_MEM_ERROR;
279: strm->state = (struct internal_state FAR *)s;
280: s->strm = strm;
281:
282: s->wrap = wrap;
283: s->gzhead = Z_NULL;
284: s->w_bits = windowBits;
285: s->w_size = 1 << s->w_bits;
286: s->w_mask = s->w_size - 1;
287:
288: s->hash_bits = memLevel + 7;
289: s->hash_size = 1 << s->hash_bits;
290: s->hash_mask = s->hash_size - 1;
291: s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
292:
293: s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
294: s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
295: s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
296:
297: s->high_water = 0; /* nothing written to s->window yet */
298:
299: s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
300:
301: overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
302: s->pending_buf = (uchf *) overlay;
303: s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
304:
305: if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
306: s->pending_buf == Z_NULL) {
307: s->status = FINISH_STATE;
308: strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
309: deflateEnd (strm);
310: return Z_MEM_ERROR;
311: }
312: s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
313: s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
314:
315: s->level = level;
316: s->strategy = strategy;
317: s->method = (Byte)method;
318:
319: return deflateReset(strm);
320: }
321:
322: /* ========================================================================= */
323: int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
324: z_streamp strm;
325: const Bytef *dictionary;
326: uInt dictLength;
327: {
328: deflate_state *s;
329: uInt str, n;
330: int wrap;
331: unsigned avail;
332: unsigned char *next;
333:
334: if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL)
335: return Z_STREAM_ERROR;
336: s = strm->state;
337: wrap = s->wrap;
338: if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead)
339: return Z_STREAM_ERROR;
340:
341: /* when using zlib wrappers, compute Adler-32 for provided dictionary */
342: if (wrap == 1)
343: strm->adler = adler32(strm->adler, dictionary, dictLength);
344: s->wrap = 0; /* avoid computing Adler-32 in read_buf */
345:
346: /* if dictionary would fill window, just replace the history */
347: if (dictLength >= s->w_size) {
348: if (wrap == 0) { /* already empty otherwise */
349: CLEAR_HASH(s);
350: s->strstart = 0;
351: s->block_start = 0L;
352: s->insert = 0;
353: }
354: dictionary += dictLength - s->w_size; /* use the tail */
355: dictLength = s->w_size;
356: }
357:
358: /* insert dictionary into window and hash */
359: avail = strm->avail_in;
360: next = strm->next_in;
361: strm->avail_in = dictLength;
362: strm->next_in = (Bytef *)dictionary;
363: fill_window(s);
364: while (s->lookahead >= MIN_MATCH) {
365: str = s->strstart;
366: n = s->lookahead - (MIN_MATCH-1);
367: do {
368: UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
369: #ifndef FASTEST
370: s->prev[str & s->w_mask] = s->head[s->ins_h];
371: #endif
372: s->head[s->ins_h] = (Pos)str;
373: str++;
374: } while (--n);
375: s->strstart = str;
376: s->lookahead = MIN_MATCH-1;
377: fill_window(s);
378: }
379: s->strstart += s->lookahead;
380: s->block_start = (long)s->strstart;
381: s->insert = s->lookahead;
382: s->lookahead = 0;
383: s->match_length = s->prev_length = MIN_MATCH-1;
384: s->match_available = 0;
385: strm->next_in = next;
386: strm->avail_in = avail;
387: s->wrap = wrap;
388: return Z_OK;
389: }
390:
391: /* ========================================================================= */
392: int ZEXPORT deflateResetKeep (strm)
393: z_streamp strm;
394: {
395: deflate_state *s;
396:
397: if (strm == Z_NULL || strm->state == Z_NULL ||
398: strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
399: return Z_STREAM_ERROR;
400: }
401:
402: strm->total_in = strm->total_out = 0;
403: strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
404: strm->data_type = Z_UNKNOWN;
405:
406: s = (deflate_state *)strm->state;
407: s->pending = 0;
408: s->pending_out = s->pending_buf;
409:
410: if (s->wrap < 0) {
411: s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
412: }
413: s->status = s->wrap ? INIT_STATE : BUSY_STATE;
414: strm->adler =
415: #ifdef GZIP
416: s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
417: #endif
418: adler32(0L, Z_NULL, 0);
419: s->last_flush = Z_NO_FLUSH;
420:
421: _tr_init(s);
422:
423: return Z_OK;
424: }
425:
426: /* ========================================================================= */
427: int ZEXPORT deflateReset (strm)
428: z_streamp strm;
429: {
430: int ret;
431:
432: ret = deflateResetKeep(strm);
433: if (ret == Z_OK)
434: lm_init(strm->state);
435: return ret;
436: }
437:
438: /* ========================================================================= */
439: int ZEXPORT deflateSetHeader (strm, head)
440: z_streamp strm;
441: gz_headerp head;
442: {
443: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
444: if (strm->state->wrap != 2) return Z_STREAM_ERROR;
445: strm->state->gzhead = head;
446: return Z_OK;
447: }
448:
449: /* ========================================================================= */
450: int ZEXPORT deflatePending (strm, pending, bits)
451: unsigned *pending;
452: int *bits;
453: z_streamp strm;
454: {
455: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
456: if (pending != Z_NULL)
457: *pending = strm->state->pending;
458: if (bits != Z_NULL)
459: *bits = strm->state->bi_valid;
460: return Z_OK;
461: }
462:
463: /* ========================================================================= */
464: int ZEXPORT deflatePrime (strm, bits, value)
465: z_streamp strm;
466: int bits;
467: int value;
468: {
469: deflate_state *s;
470: int put;
471:
472: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
473: s = strm->state;
474: if ((Bytef *)(s->d_buf) < s->pending_out + ((Buf_size + 7) >> 3))
475: return Z_BUF_ERROR;
476: do {
477: put = Buf_size - s->bi_valid;
478: if (put > bits)
479: put = bits;
480: s->bi_buf |= (ush)((value & ((1 << put) - 1)) << s->bi_valid);
481: s->bi_valid += put;
482: _tr_flush_bits(s);
483: value >>= put;
484: bits -= put;
485: } while (bits);
486: return Z_OK;
487: }
488:
489: /* ========================================================================= */
490: int ZEXPORT deflateParams(strm, level, strategy)
491: z_streamp strm;
492: int level;
493: int strategy;
494: {
495: deflate_state *s;
496: compress_func func;
497: int err = Z_OK;
498:
499: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
500: s = strm->state;
501:
502: #ifdef FASTEST
503: if (level != 0) level = 1;
504: #else
505: if (level == Z_DEFAULT_COMPRESSION) level = 6;
506: #endif
507: if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
508: return Z_STREAM_ERROR;
509: }
510: func = configuration_table[s->level].func;
511:
512: if ((strategy != s->strategy || func != configuration_table[level].func) &&
513: strm->total_in != 0) {
514: /* Flush the last buffer: */
515: err = deflate(strm, Z_BLOCK);
516: }
517: if (s->level != level) {
518: s->level = level;
519: s->max_lazy_match = configuration_table[level].max_lazy;
520: s->good_match = configuration_table[level].good_length;
521: s->nice_match = configuration_table[level].nice_length;
522: s->max_chain_length = configuration_table[level].max_chain;
523: }
524: s->strategy = strategy;
525: return err;
526: }
527:
528: /* ========================================================================= */
529: int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
530: z_streamp strm;
531: int good_length;
532: int max_lazy;
533: int nice_length;
534: int max_chain;
535: {
536: deflate_state *s;
537:
538: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
539: s = strm->state;
540: s->good_match = good_length;
541: s->max_lazy_match = max_lazy;
542: s->nice_match = nice_length;
543: s->max_chain_length = max_chain;
544: return Z_OK;
545: }
546:
547: /* =========================================================================
548: * For the default windowBits of 15 and memLevel of 8, this function returns
549: * a close to exact, as well as small, upper bound on the compressed size.
550: * They are coded as constants here for a reason--if the #define's are
551: * changed, then this function needs to be changed as well. The return
552: * value for 15 and 8 only works for those exact settings.
553: *
554: * For any setting other than those defaults for windowBits and memLevel,
555: * the value returned is a conservative worst case for the maximum expansion
556: * resulting from using fixed blocks instead of stored blocks, which deflate
557: * can emit on compressed data for some combinations of the parameters.
558: *
559: * This function could be more sophisticated to provide closer upper bounds for
560: * every combination of windowBits and memLevel. But even the conservative
561: * upper bound of about 14% expansion does not seem onerous for output buffer
562: * allocation.
563: */
564: uLong ZEXPORT deflateBound(strm, sourceLen)
565: z_streamp strm;
566: uLong sourceLen;
567: {
568: deflate_state *s;
569: uLong complen, wraplen;
570: Bytef *str;
571:
572: /* conservative upper bound for compressed data */
573: complen = sourceLen +
574: ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;
575:
576: /* if can't get parameters, return conservative bound plus zlib wrapper */
577: if (strm == Z_NULL || strm->state == Z_NULL)
578: return complen + 6;
579:
580: /* compute wrapper length */
581: s = strm->state;
582: switch (s->wrap) {
583: case 0: /* raw deflate */
584: wraplen = 0;
585: break;
586: case 1: /* zlib wrapper */
587: wraplen = 6 + (s->strstart ? 4 : 0);
588: break;
589: case 2: /* gzip wrapper */
590: wraplen = 18;
591: if (s->gzhead != Z_NULL) { /* user-supplied gzip header */
592: if (s->gzhead->extra != Z_NULL)
593: wraplen += 2 + s->gzhead->extra_len;
594: str = s->gzhead->name;
595: if (str != Z_NULL)
596: do {
597: wraplen++;
598: } while (*str++);
599: str = s->gzhead->comment;
600: if (str != Z_NULL)
601: do {
602: wraplen++;
603: } while (*str++);
604: if (s->gzhead->hcrc)
605: wraplen += 2;
606: }
607: break;
608: default: /* for compiler happiness */
609: wraplen = 6;
610: }
611:
612: /* if not default parameters, return conservative bound */
613: if (s->w_bits != 15 || s->hash_bits != 8 + 7)
614: return complen + wraplen;
615:
616: /* default settings: return tight bound for that case */
617: return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +
618: (sourceLen >> 25) + 13 - 6 + wraplen;
619: }
620:
621: /* =========================================================================
622: * Put a short in the pending buffer. The 16-bit value is put in MSB order.
623: * IN assertion: the stream state is correct and there is enough room in
624: * pending_buf.
625: */
626: local void putShortMSB (s, b)
627: deflate_state *s;
628: uInt b;
629: {
630: put_byte(s, (Byte)(b >> 8));
631: put_byte(s, (Byte)(b & 0xff));
632: }
633:
634: /* =========================================================================
635: * Flush as much pending output as possible. All deflate() output goes
636: * through this function so some applications may wish to modify it
637: * to avoid allocating a large strm->next_out buffer and copying into it.
638: * (See also read_buf()).
639: */
640: local void flush_pending(strm)
641: z_streamp strm;
642: {
643: unsigned len;
644: deflate_state *s = strm->state;
645:
646: _tr_flush_bits(s);
647: len = s->pending;
648: if (len > strm->avail_out) len = strm->avail_out;
649: if (len == 0) return;
650:
651: zmemcpy(strm->next_out, s->pending_out, len);
652: strm->next_out += len;
653: s->pending_out += len;
654: strm->total_out += len;
655: strm->avail_out -= len;
656: s->pending -= len;
657: if (s->pending == 0) {
658: s->pending_out = s->pending_buf;
659: }
660: }
661:
662: /* ========================================================================= */
663: int ZEXPORT deflate (strm, flush)
664: z_streamp strm;
665: int flush;
666: {
667: int old_flush; /* value of flush param for previous deflate call */
668: deflate_state *s;
669:
670: if (strm == Z_NULL || strm->state == Z_NULL ||
671: flush > Z_BLOCK || flush < 0) {
672: return Z_STREAM_ERROR;
673: }
674: s = strm->state;
675:
676: if (strm->next_out == Z_NULL ||
677: (strm->next_in == Z_NULL && strm->avail_in != 0) ||
678: (s->status == FINISH_STATE && flush != Z_FINISH)) {
679: ERR_RETURN(strm, Z_STREAM_ERROR);
680: }
681: if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
682:
683: s->strm = strm; /* just in case */
684: old_flush = s->last_flush;
685: s->last_flush = flush;
686:
687: /* Write the header */
688: if (s->status == INIT_STATE) {
689: #ifdef GZIP
690: if (s->wrap == 2) {
691: strm->adler = crc32(0L, Z_NULL, 0);
692: put_byte(s, 31);
693: put_byte(s, 139);
694: put_byte(s, 8);
695: if (s->gzhead == Z_NULL) {
696: put_byte(s, 0);
697: put_byte(s, 0);
698: put_byte(s, 0);
699: put_byte(s, 0);
700: put_byte(s, 0);
701: put_byte(s, s->level == 9 ? 2 :
702: (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
703: 4 : 0));
704: put_byte(s, OS_CODE);
705: s->status = BUSY_STATE;
706: }
707: else {
708: put_byte(s, (s->gzhead->text ? 1 : 0) +
709: (s->gzhead->hcrc ? 2 : 0) +
710: (s->gzhead->extra == Z_NULL ? 0 : 4) +
711: (s->gzhead->name == Z_NULL ? 0 : 8) +
712: (s->gzhead->comment == Z_NULL ? 0 : 16)
713: );
714: put_byte(s, (Byte)(s->gzhead->time & 0xff));
715: put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
716: put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
717: put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
718: put_byte(s, s->level == 9 ? 2 :
719: (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
720: 4 : 0));
721: put_byte(s, s->gzhead->os & 0xff);
722: if (s->gzhead->extra != Z_NULL) {
723: put_byte(s, s->gzhead->extra_len & 0xff);
724: put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
725: }
726: if (s->gzhead->hcrc)
727: strm->adler = crc32(strm->adler, s->pending_buf,
728: s->pending);
729: s->gzindex = 0;
730: s->status = EXTRA_STATE;
731: }
732: }
733: else
734: #endif
735: {
736: uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
737: uInt level_flags;
738:
739: if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
740: level_flags = 0;
741: else if (s->level < 6)
742: level_flags = 1;
743: else if (s->level == 6)
744: level_flags = 2;
745: else
746: level_flags = 3;
747: header |= (level_flags << 6);
748: if (s->strstart != 0) header |= PRESET_DICT;
749: header += 31 - (header % 31);
750:
751: s->status = BUSY_STATE;
752: putShortMSB(s, header);
753:
754: /* Save the adler32 of the preset dictionary: */
755: if (s->strstart != 0) {
756: putShortMSB(s, (uInt)(strm->adler >> 16));
757: putShortMSB(s, (uInt)(strm->adler & 0xffff));
758: }
759: strm->adler = adler32(0L, Z_NULL, 0);
760: }
761: }
762: #ifdef GZIP
763: if (s->status == EXTRA_STATE) {
764: if (s->gzhead->extra != Z_NULL) {
765: uInt beg = s->pending; /* start of bytes to update crc */
766:
767: while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
768: if (s->pending == s->pending_buf_size) {
769: if (s->gzhead->hcrc && s->pending > beg)
770: strm->adler = crc32(strm->adler, s->pending_buf + beg,
771: s->pending - beg);
772: flush_pending(strm);
773: beg = s->pending;
774: if (s->pending == s->pending_buf_size)
775: break;
776: }
777: put_byte(s, s->gzhead->extra[s->gzindex]);
778: s->gzindex++;
779: }
780: if (s->gzhead->hcrc && s->pending > beg)
781: strm->adler = crc32(strm->adler, s->pending_buf + beg,
782: s->pending - beg);
783: if (s->gzindex == s->gzhead->extra_len) {
784: s->gzindex = 0;
785: s->status = NAME_STATE;
786: }
787: }
788: else
789: s->status = NAME_STATE;
790: }
791: if (s->status == NAME_STATE) {
792: if (s->gzhead->name != Z_NULL) {
793: uInt beg = s->pending; /* start of bytes to update crc */
794: int val;
795:
796: do {
797: if (s->pending == s->pending_buf_size) {
798: if (s->gzhead->hcrc && s->pending > beg)
799: strm->adler = crc32(strm->adler, s->pending_buf + beg,
800: s->pending - beg);
801: flush_pending(strm);
802: beg = s->pending;
803: if (s->pending == s->pending_buf_size) {
804: val = 1;
805: break;
806: }
807: }
808: val = s->gzhead->name[s->gzindex++];
809: put_byte(s, val);
810: } while (val != 0);
811: if (s->gzhead->hcrc && s->pending > beg)
812: strm->adler = crc32(strm->adler, s->pending_buf + beg,
813: s->pending - beg);
814: if (val == 0) {
815: s->gzindex = 0;
816: s->status = COMMENT_STATE;
817: }
818: }
819: else
820: s->status = COMMENT_STATE;
821: }
822: if (s->status == COMMENT_STATE) {
823: if (s->gzhead->comment != Z_NULL) {
824: uInt beg = s->pending; /* start of bytes to update crc */
825: int val;
826:
827: do {
828: if (s->pending == s->pending_buf_size) {
829: if (s->gzhead->hcrc && s->pending > beg)
830: strm->adler = crc32(strm->adler, s->pending_buf + beg,
831: s->pending - beg);
832: flush_pending(strm);
833: beg = s->pending;
834: if (s->pending == s->pending_buf_size) {
835: val = 1;
836: break;
837: }
838: }
839: val = s->gzhead->comment[s->gzindex++];
840: put_byte(s, val);
841: } while (val != 0);
842: if (s->gzhead->hcrc && s->pending > beg)
843: strm->adler = crc32(strm->adler, s->pending_buf + beg,
844: s->pending - beg);
845: if (val == 0)
846: s->status = HCRC_STATE;
847: }
848: else
849: s->status = HCRC_STATE;
850: }
851: if (s->status == HCRC_STATE) {
852: if (s->gzhead->hcrc) {
853: if (s->pending + 2 > s->pending_buf_size)
854: flush_pending(strm);
855: if (s->pending + 2 <= s->pending_buf_size) {
856: put_byte(s, (Byte)(strm->adler & 0xff));
857: put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
858: strm->adler = crc32(0L, Z_NULL, 0);
859: s->status = BUSY_STATE;
860: }
861: }
862: else
863: s->status = BUSY_STATE;
864: }
865: #endif
866:
867: /* Flush as much pending output as possible */
868: if (s->pending != 0) {
869: flush_pending(strm);
870: if (strm->avail_out == 0) {
871: /* Since avail_out is 0, deflate will be called again with
872: * more output space, but possibly with both pending and
873: * avail_in equal to zero. There won't be anything to do,
874: * but this is not an error situation so make sure we
875: * return OK instead of BUF_ERROR at next call of deflate:
876: */
877: s->last_flush = -1;
878: return Z_OK;
879: }
880:
881: /* Make sure there is something to do and avoid duplicate consecutive
882: * flushes. For repeated and useless calls with Z_FINISH, we keep
883: * returning Z_STREAM_END instead of Z_BUF_ERROR.
884: */
885: } else if (strm->avail_in == 0 && RANK(flush) <= RANK(old_flush) &&
886: flush != Z_FINISH) {
887: ERR_RETURN(strm, Z_BUF_ERROR);
888: }
889:
890: /* User must not provide more input after the first FINISH: */
891: if (s->status == FINISH_STATE && strm->avail_in != 0) {
892: ERR_RETURN(strm, Z_BUF_ERROR);
893: }
894:
895: /* Start a new block or continue the current one.
896: */
897: if (strm->avail_in != 0 || s->lookahead != 0 ||
898: (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
899: block_state bstate;
900:
901: bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :
902: (s->strategy == Z_RLE ? deflate_rle(s, flush) :
903: (*(configuration_table[s->level].func))(s, flush));
904:
905: if (bstate == finish_started || bstate == finish_done) {
906: s->status = FINISH_STATE;
907: }
908: if (bstate == need_more || bstate == finish_started) {
909: if (strm->avail_out == 0) {
910: s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
911: }
912: return Z_OK;
913: /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
914: * of deflate should use the same flush parameter to make sure
915: * that the flush is complete. So we don't have to output an
916: * empty block here, this will be done at next call. This also
917: * ensures that for a very small output buffer, we emit at most
918: * one empty block.
919: */
920: }
921: if (bstate == block_done) {
922: if (flush == Z_PARTIAL_FLUSH) {
923: _tr_align(s);
924: } else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */
925: _tr_stored_block(s, (char*)0, 0L, 0);
926: /* For a full flush, this empty block will be recognized
927: * as a special marker by inflate_sync().
928: */
929: if (flush == Z_FULL_FLUSH) {
930: CLEAR_HASH(s); /* forget history */
931: if (s->lookahead == 0) {
932: s->strstart = 0;
933: s->block_start = 0L;
934: s->insert = 0;
935: }
936: }
937: }
938: flush_pending(strm);
939: if (strm->avail_out == 0) {
940: s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
941: return Z_OK;
942: }
943: }
944: }
945: Assert(strm->avail_out > 0, "bug2");
946:
947: if (flush != Z_FINISH) return Z_OK;
948: if (s->wrap <= 0) return Z_STREAM_END;
949:
950: /* Write the trailer */
951: #ifdef GZIP
952: if (s->wrap == 2) {
953: put_byte(s, (Byte)(strm->adler & 0xff));
954: put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
955: put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
956: put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
957: put_byte(s, (Byte)(strm->total_in & 0xff));
958: put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
959: put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
960: put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
961: }
962: else
963: #endif
964: {
965: putShortMSB(s, (uInt)(strm->adler >> 16));
966: putShortMSB(s, (uInt)(strm->adler & 0xffff));
967: }
968: flush_pending(strm);
969: /* If avail_out is zero, the application will call deflate again
970: * to flush the rest.
971: */
972: if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
973: return s->pending != 0 ? Z_OK : Z_STREAM_END;
974: }
975:
976: /* ========================================================================= */
977: int ZEXPORT deflateEnd (strm)
978: z_streamp strm;
979: {
980: int status;
981:
982: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
983:
984: status = strm->state->status;
985: if (status != INIT_STATE &&
986: status != EXTRA_STATE &&
987: status != NAME_STATE &&
988: status != COMMENT_STATE &&
989: status != HCRC_STATE &&
990: status != BUSY_STATE &&
991: status != FINISH_STATE) {
992: return Z_STREAM_ERROR;
993: }
994:
995: /* Deallocate in reverse order of allocations: */
996: TRY_FREE(strm, strm->state->pending_buf);
997: TRY_FREE(strm, strm->state->head);
998: TRY_FREE(strm, strm->state->prev);
999: TRY_FREE(strm, strm->state->window);
1000:
1001: ZFREE(strm, strm->state);
1002: strm->state = Z_NULL;
1003:
1004: return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
1005: }
1006:
1007: /* =========================================================================
1008: * Copy the source state to the destination state.
1009: * To simplify the source, this is not supported for 16-bit MSDOS (which
1010: * doesn't have enough memory anyway to duplicate compression states).
1011: */
1012: int ZEXPORT deflateCopy (dest, source)
1013: z_streamp dest;
1014: z_streamp source;
1015: {
1016: #ifdef MAXSEG_64K
1017: return Z_STREAM_ERROR;
1018: #else
1019: deflate_state *ds;
1020: deflate_state *ss;
1021: ushf *overlay;
1022:
1023:
1024: if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
1025: return Z_STREAM_ERROR;
1026: }
1027:
1028: ss = source->state;
1029:
1030: zmemcpy((voidpf)dest, (voidpf)source, sizeof(z_stream));
1031:
1032: ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
1033: if (ds == Z_NULL) return Z_MEM_ERROR;
1034: dest->state = (struct internal_state FAR *) ds;
1035: zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state));
1036: ds->strm = dest;
1037:
1038: ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
1039: ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
1040: ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
1041: overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
1042: ds->pending_buf = (uchf *) overlay;
1043:
1044: if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
1045: ds->pending_buf == Z_NULL) {
1046: deflateEnd (dest);
1047: return Z_MEM_ERROR;
1048: }
1049: /* following zmemcpy do not work for 16-bit MSDOS */
1050: zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
1051: zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos));
1052: zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos));
1053: zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
1054:
1055: ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
1056: ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
1057: ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
1058:
1059: ds->l_desc.dyn_tree = ds->dyn_ltree;
1060: ds->d_desc.dyn_tree = ds->dyn_dtree;
1061: ds->bl_desc.dyn_tree = ds->bl_tree;
1062:
1063: return Z_OK;
1064: #endif /* MAXSEG_64K */
1065: }
1066:
1067: /* ===========================================================================
1068: * Read a new buffer from the current input stream, update the adler32
1069: * and total number of bytes read. All deflate() input goes through
1070: * this function so some applications may wish to modify it to avoid
1071: * allocating a large strm->next_in buffer and copying from it.
1072: * (See also flush_pending()).
1073: */
1074: local int read_buf(strm, buf, size)
1075: z_streamp strm;
1076: Bytef *buf;
1077: unsigned size;
1078: {
1079: unsigned len = strm->avail_in;
1080:
1081: if (len > size) len = size;
1082: if (len == 0) return 0;
1083:
1084: strm->avail_in -= len;
1085:
1086: zmemcpy(buf, strm->next_in, len);
1087: if (strm->state->wrap == 1) {
1088: strm->adler = adler32(strm->adler, buf, len);
1089: }
1090: #ifdef GZIP
1091: else if (strm->state->wrap == 2) {
1092: strm->adler = crc32(strm->adler, buf, len);
1093: }
1094: #endif
1095: strm->next_in += len;
1096: strm->total_in += len;
1097:
1098: return (int)len;
1099: }
1100:
1101: /* ===========================================================================
1102: * Initialize the "longest match" routines for a new zlib stream
1103: */
1104: local void lm_init (s)
1105: deflate_state *s;
1106: {
1107: s->window_size = (ulg)2L*s->w_size;
1108:
1109: CLEAR_HASH(s);
1110:
1111: /* Set the default configuration parameters:
1112: */
1113: s->max_lazy_match = configuration_table[s->level].max_lazy;
1114: s->good_match = configuration_table[s->level].good_length;
1115: s->nice_match = configuration_table[s->level].nice_length;
1116: s->max_chain_length = configuration_table[s->level].max_chain;
1117:
1118: s->strstart = 0;
1119: s->block_start = 0L;
1120: s->lookahead = 0;
1121: s->insert = 0;
1122: s->match_length = s->prev_length = MIN_MATCH-1;
1123: s->match_available = 0;
1124: s->ins_h = 0;
1125: #ifndef FASTEST
1126: #ifdef ASMV
1127: match_init(); /* initialize the asm code */
1128: #endif
1129: #endif
1130: }
1131:
1132: #ifndef FASTEST
1133: /* ===========================================================================
1134: * Set match_start to the longest match starting at the given string and
1135: * return its length. Matches shorter or equal to prev_length are discarded,
1136: * in which case the result is equal to prev_length and match_start is
1137: * garbage.
1138: * IN assertions: cur_match is the head of the hash chain for the current
1139: * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1140: * OUT assertion: the match length is not greater than s->lookahead.
1141: */
1142: #ifndef ASMV
1143: /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1144: * match.S. The code will be functionally equivalent.
1145: */
1146: local uInt longest_match(s, cur_match)
1147: deflate_state *s;
1148: IPos cur_match; /* current match */
1149: {
1150: unsigned chain_length = s->max_chain_length;/* max hash chain length */
1151: register Bytef *scan = s->window + s->strstart; /* current string */
1152: register Bytef *match; /* matched string */
1153: register int len; /* length of current match */
1154: int best_len = s->prev_length; /* best match length so far */
1155: int nice_match = s->nice_match; /* stop if match long enough */
1156: IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1157: s->strstart - (IPos)MAX_DIST(s) : NIL;
1158: /* Stop when cur_match becomes <= limit. To simplify the code,
1159: * we prevent matches with the string of window index 0.
1160: */
1161: Posf *prev = s->prev;
1162: uInt wmask = s->w_mask;
1163:
1164: #ifdef UNALIGNED_OK
1165: /* Compare two bytes at a time. Note: this is not always beneficial.
1166: * Try with and without -DUNALIGNED_OK to check.
1167: */
1168: register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1169: register ush scan_start = *(ushf*)scan;
1170: register ush scan_end = *(ushf*)(scan+best_len-1);
1171: #else
1172: register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1173: register Byte scan_end1 = scan[best_len-1];
1174: register Byte scan_end = scan[best_len];
1175: #endif
1176:
1177: /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1178: * It is easy to get rid of this optimization if necessary.
1179: */
1180: Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1181:
1182: /* Do not waste too much time if we already have a good match: */
1183: if (s->prev_length >= s->good_match) {
1184: chain_length >>= 2;
1185: }
1186: /* Do not look for matches beyond the end of the input. This is necessary
1187: * to make deflate deterministic.
1188: */
1189: if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1190:
1191: Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1192:
1193: do {
1194: Assert(cur_match < s->strstart, "no future");
1195: match = s->window + cur_match;
1196:
1197: /* Skip to next match if the match length cannot increase
1198: * or if the match length is less than 2. Note that the checks below
1199: * for insufficient lookahead only occur occasionally for performance
1200: * reasons. Therefore uninitialized memory will be accessed, and
1201: * conditional jumps will be made that depend on those values.
1202: * However the length of the match is limited to the lookahead, so
1203: * the output of deflate is not affected by the uninitialized values.
1204: */
1205: #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1206: /* This code assumes sizeof(unsigned short) == 2. Do not use
1207: * UNALIGNED_OK if your compiler uses a different size.
1208: */
1209: if (*(ushf*)(match+best_len-1) != scan_end ||
1210: *(ushf*)match != scan_start) continue;
1211:
1212: /* It is not necessary to compare scan[2] and match[2] since they are
1213: * always equal when the other bytes match, given that the hash keys
1214: * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1215: * strstart+3, +5, ... up to strstart+257. We check for insufficient
1216: * lookahead only every 4th comparison; the 128th check will be made
1217: * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1218: * necessary to put more guard bytes at the end of the window, or
1219: * to check more often for insufficient lookahead.
1220: */
1221: Assert(scan[2] == match[2], "scan[2]?");
1222: scan++, match++;
1223: do {
1224: } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1225: *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1226: *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1227: *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1228: scan < strend);
1229: /* The funny "do {}" generates better code on most compilers */
1230:
1231: /* Here, scan <= window+strstart+257 */
1232: Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1233: if (*scan == *match) scan++;
1234:
1235: len = (MAX_MATCH - 1) - (int)(strend-scan);
1236: scan = strend - (MAX_MATCH-1);
1237:
1238: #else /* UNALIGNED_OK */
1239:
1240: if (match[best_len] != scan_end ||
1241: match[best_len-1] != scan_end1 ||
1242: *match != *scan ||
1243: *++match != scan[1]) continue;
1244:
1245: /* The check at best_len-1 can be removed because it will be made
1246: * again later. (This heuristic is not always a win.)
1247: * It is not necessary to compare scan[2] and match[2] since they
1248: * are always equal when the other bytes match, given that
1249: * the hash keys are equal and that HASH_BITS >= 8.
1250: */
1251: scan += 2, match++;
1252: Assert(*scan == *match, "match[2]?");
1253:
1254: /* We check for insufficient lookahead only every 8th comparison;
1255: * the 256th check will be made at strstart+258.
1256: */
1257: do {
1258: } while (*++scan == *++match && *++scan == *++match &&
1259: *++scan == *++match && *++scan == *++match &&
1260: *++scan == *++match && *++scan == *++match &&
1261: *++scan == *++match && *++scan == *++match &&
1262: scan < strend);
1263:
1264: Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1265:
1266: len = MAX_MATCH - (int)(strend - scan);
1267: scan = strend - MAX_MATCH;
1268:
1269: #endif /* UNALIGNED_OK */
1270:
1271: if (len > best_len) {
1272: s->match_start = cur_match;
1273: best_len = len;
1274: if (len >= nice_match) break;
1275: #ifdef UNALIGNED_OK
1276: scan_end = *(ushf*)(scan+best_len-1);
1277: #else
1278: scan_end1 = scan[best_len-1];
1279: scan_end = scan[best_len];
1280: #endif
1281: }
1282: } while ((cur_match = prev[cur_match & wmask]) > limit
1283: && --chain_length != 0);
1284:
1285: if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1286: return s->lookahead;
1287: }
1288: #endif /* ASMV */
1289:
1290: #else /* FASTEST */
1291:
1292: /* ---------------------------------------------------------------------------
1293: * Optimized version for FASTEST only
1294: */
1295: local uInt longest_match(s, cur_match)
1296: deflate_state *s;
1297: IPos cur_match; /* current match */
1298: {
1299: register Bytef *scan = s->window + s->strstart; /* current string */
1300: register Bytef *match; /* matched string */
1301: register int len; /* length of current match */
1302: register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1303:
1304: /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1305: * It is easy to get rid of this optimization if necessary.
1306: */
1307: Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1308:
1309: Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1310:
1311: Assert(cur_match < s->strstart, "no future");
1312:
1313: match = s->window + cur_match;
1314:
1315: /* Return failure if the match length is less than 2:
1316: */
1317: if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1318:
1319: /* The check at best_len-1 can be removed because it will be made
1320: * again later. (This heuristic is not always a win.)
1321: * It is not necessary to compare scan[2] and match[2] since they
1322: * are always equal when the other bytes match, given that
1323: * the hash keys are equal and that HASH_BITS >= 8.
1324: */
1325: scan += 2, match += 2;
1326: Assert(*scan == *match, "match[2]?");
1327:
1328: /* We check for insufficient lookahead only every 8th comparison;
1329: * the 256th check will be made at strstart+258.
1330: */
1331: do {
1332: } while (*++scan == *++match && *++scan == *++match &&
1333: *++scan == *++match && *++scan == *++match &&
1334: *++scan == *++match && *++scan == *++match &&
1335: *++scan == *++match && *++scan == *++match &&
1336: scan < strend);
1337:
1338: Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1339:
1340: len = MAX_MATCH - (int)(strend - scan);
1341:
1342: if (len < MIN_MATCH) return MIN_MATCH - 1;
1343:
1344: s->match_start = cur_match;
1345: return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1346: }
1347:
1348: #endif /* FASTEST */
1349:
1350: #ifdef DEBUG
1351: /* ===========================================================================
1352: * Check that the match at match_start is indeed a match.
1353: */
1354: local void check_match(s, start, match, length)
1355: deflate_state *s;
1356: IPos start, match;
1357: int length;
1358: {
1359: /* check that the match is indeed a match */
1360: if (zmemcmp(s->window + match,
1361: s->window + start, length) != EQUAL) {
1362: fprintf(stderr, " start %u, match %u, length %d\n",
1363: start, match, length);
1364: do {
1365: fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1366: } while (--length != 0);
1367: z_error("invalid match");
1368: }
1369: if (z_verbose > 1) {
1370: fprintf(stderr,"\\[%d,%d]", start-match, length);
1371: do { putc(s->window[start++], stderr); } while (--length != 0);
1372: }
1373: }
1374: #else
1375: # define check_match(s, start, match, length)
1376: #endif /* DEBUG */
1377:
1378: /* ===========================================================================
1379: * Fill the window when the lookahead becomes insufficient.
1380: * Updates strstart and lookahead.
1381: *
1382: * IN assertion: lookahead < MIN_LOOKAHEAD
1383: * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1384: * At least one byte has been read, or avail_in == 0; reads are
1385: * performed for at least two bytes (required for the zip translate_eol
1386: * option -- not supported here).
1387: */
1388: local void fill_window(s)
1389: deflate_state *s;
1390: {
1391: register unsigned n, m;
1392: register Posf *p;
1393: unsigned more; /* Amount of free space at the end of the window. */
1394: uInt wsize = s->w_size;
1395:
1396: Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead");
1397:
1398: do {
1399: more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1400:
1401: /* Deal with !@#$% 64K limit: */
1402: if (sizeof(int) <= 2) {
1403: if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1404: more = wsize;
1405:
1406: } else if (more == (unsigned)(-1)) {
1407: /* Very unlikely, but possible on 16 bit machine if
1408: * strstart == 0 && lookahead == 1 (input done a byte at time)
1409: */
1410: more--;
1411: }
1412: }
1413:
1414: /* If the window is almost full and there is insufficient lookahead,
1415: * move the upper half to the lower one to make room in the upper half.
1416: */
1417: if (s->strstart >= wsize+MAX_DIST(s)) {
1418:
1419: zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1420: s->match_start -= wsize;
1421: s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1422: s->block_start -= (long) wsize;
1423:
1424: /* Slide the hash table (could be avoided with 32 bit values
1425: at the expense of memory usage). We slide even when level == 0
1426: to keep the hash table consistent if we switch back to level > 0
1427: later. (Using level 0 permanently is not an optimal usage of
1428: zlib, so we don't care about this pathological case.)
1429: */
1430: n = s->hash_size;
1431: p = &s->head[n];
1432: do {
1433: m = *--p;
1434: *p = (Pos)(m >= wsize ? m-wsize : NIL);
1435: } while (--n);
1436:
1437: n = wsize;
1438: #ifndef FASTEST
1439: p = &s->prev[n];
1440: do {
1441: m = *--p;
1442: *p = (Pos)(m >= wsize ? m-wsize : NIL);
1443: /* If n is not on any hash chain, prev[n] is garbage but
1444: * its value will never be used.
1445: */
1446: } while (--n);
1447: #endif
1448: more += wsize;
1449: }
1450: if (s->strm->avail_in == 0) break;
1451:
1452: /* If there was no sliding:
1453: * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1454: * more == window_size - lookahead - strstart
1455: * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1456: * => more >= window_size - 2*WSIZE + 2
1457: * In the BIG_MEM or MMAP case (not yet supported),
1458: * window_size == input_size + MIN_LOOKAHEAD &&
1459: * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1460: * Otherwise, window_size == 2*WSIZE so more >= 2.
1461: * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1462: */
1463: Assert(more >= 2, "more < 2");
1464:
1465: n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1466: s->lookahead += n;
1467:
1468: /* Initialize the hash value now that we have some input: */
1469: if (s->lookahead + s->insert >= MIN_MATCH) {
1470: uInt str = s->strstart - s->insert;
1471: s->ins_h = s->window[str];
1472: UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
1473: #if MIN_MATCH != 3
1474: Call UPDATE_HASH() MIN_MATCH-3 more times
1475: #endif
1476: while (s->insert) {
1477: UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]);
1478: #ifndef FASTEST
1479: s->prev[str & s->w_mask] = s->head[s->ins_h];
1480: #endif
1481: s->head[s->ins_h] = (Pos)str;
1482: str++;
1483: s->insert--;
1484: if (s->lookahead + s->insert < MIN_MATCH)
1485: break;
1486: }
1487: }
1488: /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1489: * but this is not important since only literal bytes will be emitted.
1490: */
1491:
1492: } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1493:
1494: /* If the WIN_INIT bytes after the end of the current data have never been
1495: * written, then zero those bytes in order to avoid memory check reports of
1496: * the use of uninitialized (or uninitialised as Julian writes) bytes by
1497: * the longest match routines. Update the high water mark for the next
1498: * time through here. WIN_INIT is set to MAX_MATCH since the longest match
1499: * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.
1500: */
1501: if (s->high_water < s->window_size) {
1502: ulg curr = s->strstart + (ulg)(s->lookahead);
1503: ulg init;
1504:
1505: if (s->high_water < curr) {
1506: /* Previous high water mark below current data -- zero WIN_INIT
1507: * bytes or up to end of window, whichever is less.
1508: */
1509: init = s->window_size - curr;
1510: if (init > WIN_INIT)
1511: init = WIN_INIT;
1512: zmemzero(s->window + curr, (unsigned)init);
1513: s->high_water = curr + init;
1514: }
1515: else if (s->high_water < (ulg)curr + WIN_INIT) {
1516: /* High water mark at or above current data, but below current data
1517: * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up
1518: * to end of window, whichever is less.
1519: */
1520: init = (ulg)curr + WIN_INIT - s->high_water;
1521: if (init > s->window_size - s->high_water)
1522: init = s->window_size - s->high_water;
1523: zmemzero(s->window + s->high_water, (unsigned)init);
1524: s->high_water += init;
1525: }
1526: }
1527:
1528: Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD,
1529: "not enough room for search");
1530: }
1531:
1532: /* ===========================================================================
1533: * Flush the current block, with given end-of-file flag.
1534: * IN assertion: strstart is set to the end of the current match.
1535: */
1536: #define FLUSH_BLOCK_ONLY(s, last) { \
1537: _tr_flush_block(s, (s->block_start >= 0L ? \
1538: (charf *)&s->window[(unsigned)s->block_start] : \
1539: (charf *)Z_NULL), \
1540: (ulg)((long)s->strstart - s->block_start), \
1541: (last)); \
1542: s->block_start = s->strstart; \
1543: flush_pending(s->strm); \
1544: Tracev((stderr,"[FLUSH]")); \
1545: }
1546:
1547: /* Same but force premature exit if necessary. */
1548: #define FLUSH_BLOCK(s, last) { \
1549: FLUSH_BLOCK_ONLY(s, last); \
1550: if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \
1551: }
1552:
1553: /* ===========================================================================
1554: * Copy without compression as much as possible from the input stream, return
1555: * the current block state.
1556: * This function does not insert new strings in the dictionary since
1557: * uncompressible data is probably not useful. This function is used
1558: * only for the level=0 compression option.
1559: * NOTE: this function should be optimized to avoid extra copying from
1560: * window to pending_buf.
1561: */
1562: local block_state deflate_stored(s, flush)
1563: deflate_state *s;
1564: int flush;
1565: {
1566: /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1567: * to pending_buf_size, and each stored block has a 5 byte header:
1568: */
1569: ulg max_block_size = 0xffff;
1570: ulg max_start;
1571:
1572: if (max_block_size > s->pending_buf_size - 5) {
1573: max_block_size = s->pending_buf_size - 5;
1574: }
1575:
1576: /* Copy as much as possible from input to output: */
1577: for (;;) {
1578: /* Fill the window as much as possible: */
1579: if (s->lookahead <= 1) {
1580:
1581: Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1582: s->block_start >= (long)s->w_size, "slide too late");
1583:
1584: fill_window(s);
1585: if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1586:
1587: if (s->lookahead == 0) break; /* flush the current block */
1588: }
1589: Assert(s->block_start >= 0L, "block gone");
1590:
1591: s->strstart += s->lookahead;
1592: s->lookahead = 0;
1593:
1594: /* Emit a stored block if pending_buf will be full: */
1595: max_start = s->block_start + max_block_size;
1596: if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1597: /* strstart == 0 is possible when wraparound on 16-bit machine */
1598: s->lookahead = (uInt)(s->strstart - max_start);
1599: s->strstart = (uInt)max_start;
1600: FLUSH_BLOCK(s, 0);
1601: }
1602: /* Flush if we may have to slide, otherwise block_start may become
1603: * negative and the data will be gone:
1604: */
1605: if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1606: FLUSH_BLOCK(s, 0);
1607: }
1608: }
1609: s->insert = 0;
1610: if (flush == Z_FINISH) {
1611: FLUSH_BLOCK(s, 1);
1612: return finish_done;
1613: }
1614: if ((long)s->strstart > s->block_start)
1615: FLUSH_BLOCK(s, 0);
1616: return block_done;
1617: }
1618:
1619: /* ===========================================================================
1620: * Compress as much as possible from the input stream, return the current
1621: * block state.
1622: * This function does not perform lazy evaluation of matches and inserts
1623: * new strings in the dictionary only for unmatched strings or for short
1624: * matches. It is used only for the fast compression options.
1625: */
1626: local block_state deflate_fast(s, flush)
1627: deflate_state *s;
1628: int flush;
1629: {
1630: IPos hash_head; /* head of the hash chain */
1631: int bflush; /* set if current block must be flushed */
1632:
1633: for (;;) {
1634: /* Make sure that we always have enough lookahead, except
1635: * at the end of the input file. We need MAX_MATCH bytes
1636: * for the next match, plus MIN_MATCH bytes to insert the
1637: * string following the next match.
1638: */
1639: if (s->lookahead < MIN_LOOKAHEAD) {
1640: fill_window(s);
1641: if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1642: return need_more;
1643: }
1644: if (s->lookahead == 0) break; /* flush the current block */
1645: }
1646:
1647: /* Insert the string window[strstart .. strstart+2] in the
1648: * dictionary, and set hash_head to the head of the hash chain:
1649: */
1650: hash_head = NIL;
1651: if (s->lookahead >= MIN_MATCH) {
1652: INSERT_STRING(s, s->strstart, hash_head);
1653: }
1654:
1655: /* Find the longest match, discarding those <= prev_length.
1656: * At this point we have always match_length < MIN_MATCH
1657: */
1658: if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1659: /* To simplify the code, we prevent matches with the string
1660: * of window index 0 (in particular we have to avoid a match
1661: * of the string with itself at the start of the input file).
1662: */
1663: s->match_length = longest_match (s, hash_head);
1664: /* longest_match() sets match_start */
1665: }
1666: if (s->match_length >= MIN_MATCH) {
1667: check_match(s, s->strstart, s->match_start, s->match_length);
1668:
1669: _tr_tally_dist(s, s->strstart - s->match_start,
1670: s->match_length - MIN_MATCH, bflush);
1671:
1672: s->lookahead -= s->match_length;
1673:
1674: /* Insert new strings in the hash table only if the match length
1675: * is not too large. This saves time but degrades compression.
1676: */
1677: #ifndef FASTEST
1678: if (s->match_length <= s->max_insert_length &&
1679: s->lookahead >= MIN_MATCH) {
1680: s->match_length--; /* string at strstart already in table */
1681: do {
1682: s->strstart++;
1683: INSERT_STRING(s, s->strstart, hash_head);
1684: /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1685: * always MIN_MATCH bytes ahead.
1686: */
1687: } while (--s->match_length != 0);
1688: s->strstart++;
1689: } else
1690: #endif
1691: {
1692: s->strstart += s->match_length;
1693: s->match_length = 0;
1694: s->ins_h = s->window[s->strstart];
1695: UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1696: #if MIN_MATCH != 3
1697: Call UPDATE_HASH() MIN_MATCH-3 more times
1698: #endif
1699: /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1700: * matter since it will be recomputed at next deflate call.
1701: */
1702: }
1703: } else {
1704: /* No match, output a literal byte */
1705: Tracevv((stderr,"%c", s->window[s->strstart]));
1706: _tr_tally_lit (s, s->window[s->strstart], bflush);
1707: s->lookahead--;
1708: s->strstart++;
1709: }
1710: if (bflush) FLUSH_BLOCK(s, 0);
1711: }
1712: s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1713: if (flush == Z_FINISH) {
1714: FLUSH_BLOCK(s, 1);
1715: return finish_done;
1716: }
1717: if (s->last_lit)
1718: FLUSH_BLOCK(s, 0);
1719: return block_done;
1720: }
1721:
1722: #ifndef FASTEST
1723: /* ===========================================================================
1724: * Same as above, but achieves better compression. We use a lazy
1725: * evaluation for matches: a match is finally adopted only if there is
1726: * no better match at the next window position.
1727: */
1728: local block_state deflate_slow(s, flush)
1729: deflate_state *s;
1730: int flush;
1731: {
1732: IPos hash_head; /* head of hash chain */
1733: int bflush; /* set if current block must be flushed */
1734:
1735: /* Process the input block. */
1736: for (;;) {
1737: /* Make sure that we always have enough lookahead, except
1738: * at the end of the input file. We need MAX_MATCH bytes
1739: * for the next match, plus MIN_MATCH bytes to insert the
1740: * string following the next match.
1741: */
1742: if (s->lookahead < MIN_LOOKAHEAD) {
1743: fill_window(s);
1744: if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1745: return need_more;
1746: }
1747: if (s->lookahead == 0) break; /* flush the current block */
1748: }
1749:
1750: /* Insert the string window[strstart .. strstart+2] in the
1751: * dictionary, and set hash_head to the head of the hash chain:
1752: */
1753: hash_head = NIL;
1754: if (s->lookahead >= MIN_MATCH) {
1755: INSERT_STRING(s, s->strstart, hash_head);
1756: }
1757:
1758: /* Find the longest match, discarding those <= prev_length.
1759: */
1760: s->prev_length = s->match_length, s->prev_match = s->match_start;
1761: s->match_length = MIN_MATCH-1;
1762:
1763: if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1764: s->strstart - hash_head <= MAX_DIST(s)) {
1765: /* To simplify the code, we prevent matches with the string
1766: * of window index 0 (in particular we have to avoid a match
1767: * of the string with itself at the start of the input file).
1768: */
1769: s->match_length = longest_match (s, hash_head);
1770: /* longest_match() sets match_start */
1771:
1772: if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1773: #if TOO_FAR <= 32767
1774: || (s->match_length == MIN_MATCH &&
1775: s->strstart - s->match_start > TOO_FAR)
1776: #endif
1777: )) {
1778:
1779: /* If prev_match is also MIN_MATCH, match_start is garbage
1780: * but we will ignore the current match anyway.
1781: */
1782: s->match_length = MIN_MATCH-1;
1783: }
1784: }
1785: /* If there was a match at the previous step and the current
1786: * match is not better, output the previous match:
1787: */
1788: if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1789: uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1790: /* Do not insert strings in hash table beyond this. */
1791:
1792: check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1793:
1794: _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1795: s->prev_length - MIN_MATCH, bflush);
1796:
1797: /* Insert in hash table all strings up to the end of the match.
1798: * strstart-1 and strstart are already inserted. If there is not
1799: * enough lookahead, the last two strings are not inserted in
1800: * the hash table.
1801: */
1802: s->lookahead -= s->prev_length-1;
1803: s->prev_length -= 2;
1804: do {
1805: if (++s->strstart <= max_insert) {
1806: INSERT_STRING(s, s->strstart, hash_head);
1807: }
1808: } while (--s->prev_length != 0);
1809: s->match_available = 0;
1810: s->match_length = MIN_MATCH-1;
1811: s->strstart++;
1812:
1813: if (bflush) FLUSH_BLOCK(s, 0);
1814:
1815: } else if (s->match_available) {
1816: /* If there was no match at the previous position, output a
1817: * single literal. If there was a match but the current match
1818: * is longer, truncate the previous match to a single literal.
1819: */
1820: Tracevv((stderr,"%c", s->window[s->strstart-1]));
1821: _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1822: if (bflush) {
1823: FLUSH_BLOCK_ONLY(s, 0);
1824: }
1825: s->strstart++;
1826: s->lookahead--;
1827: if (s->strm->avail_out == 0) return need_more;
1828: } else {
1829: /* There is no previous match to compare with, wait for
1830: * the next step to decide.
1831: */
1832: s->match_available = 1;
1833: s->strstart++;
1834: s->lookahead--;
1835: }
1836: }
1837: Assert (flush != Z_NO_FLUSH, "no flush?");
1838: if (s->match_available) {
1839: Tracevv((stderr,"%c", s->window[s->strstart-1]));
1840: _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1841: s->match_available = 0;
1842: }
1843: s->insert = s->strstart < MIN_MATCH-1 ? s->strstart : MIN_MATCH-1;
1844: if (flush == Z_FINISH) {
1845: FLUSH_BLOCK(s, 1);
1846: return finish_done;
1847: }
1848: if (s->last_lit)
1849: FLUSH_BLOCK(s, 0);
1850: return block_done;
1851: }
1852: #endif /* FASTEST */
1853:
1854: /* ===========================================================================
1855: * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1856: * one. Do not maintain a hash table. (It will be regenerated if this run of
1857: * deflate switches away from Z_RLE.)
1858: */
1859: local block_state deflate_rle(s, flush)
1860: deflate_state *s;
1861: int flush;
1862: {
1863: int bflush; /* set if current block must be flushed */
1864: uInt prev; /* byte at distance one to match */
1865: Bytef *scan, *strend; /* scan goes up to strend for length of run */
1866:
1867: for (;;) {
1868: /* Make sure that we always have enough lookahead, except
1869: * at the end of the input file. We need MAX_MATCH bytes
1870: * for the longest run, plus one for the unrolled loop.
1871: */
1872: if (s->lookahead <= MAX_MATCH) {
1873: fill_window(s);
1874: if (s->lookahead <= MAX_MATCH && flush == Z_NO_FLUSH) {
1875: return need_more;
1876: }
1877: if (s->lookahead == 0) break; /* flush the current block */
1878: }
1879:
1880: /* See how many times the previous byte repeats */
1881: s->match_length = 0;
1882: if (s->lookahead >= MIN_MATCH && s->strstart > 0) {
1883: scan = s->window + s->strstart - 1;
1884: prev = *scan;
1885: if (prev == *++scan && prev == *++scan && prev == *++scan) {
1886: strend = s->window + s->strstart + MAX_MATCH;
1887: do {
1888: } while (prev == *++scan && prev == *++scan &&
1889: prev == *++scan && prev == *++scan &&
1890: prev == *++scan && prev == *++scan &&
1891: prev == *++scan && prev == *++scan &&
1892: scan < strend);
1893: s->match_length = MAX_MATCH - (int)(strend - scan);
1894: if (s->match_length > s->lookahead)
1895: s->match_length = s->lookahead;
1896: }
1897: Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan");
1898: }
1899:
1900: /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1901: if (s->match_length >= MIN_MATCH) {
1902: check_match(s, s->strstart, s->strstart - 1, s->match_length);
1903:
1904: _tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);
1905:
1906: s->lookahead -= s->match_length;
1907: s->strstart += s->match_length;
1908: s->match_length = 0;
1909: } else {
1910: /* No match, output a literal byte */
1911: Tracevv((stderr,"%c", s->window[s->strstart]));
1912: _tr_tally_lit (s, s->window[s->strstart], bflush);
1913: s->lookahead--;
1914: s->strstart++;
1915: }
1916: if (bflush) FLUSH_BLOCK(s, 0);
1917: }
1918: s->insert = 0;
1919: if (flush == Z_FINISH) {
1920: FLUSH_BLOCK(s, 1);
1921: return finish_done;
1922: }
1923: if (s->last_lit)
1924: FLUSH_BLOCK(s, 0);
1925: return block_done;
1926: }
1927:
1928: /* ===========================================================================
1929: * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.
1930: * (It will be regenerated if this run of deflate switches away from Huffman.)
1931: */
1932: local block_state deflate_huff(s, flush)
1933: deflate_state *s;
1934: int flush;
1935: {
1936: int bflush; /* set if current block must be flushed */
1937:
1938: for (;;) {
1939: /* Make sure that we have a literal to write. */
1940: if (s->lookahead == 0) {
1941: fill_window(s);
1942: if (s->lookahead == 0) {
1943: if (flush == Z_NO_FLUSH)
1944: return need_more;
1945: break; /* flush the current block */
1946: }
1947: }
1948:
1949: /* Output a literal byte */
1950: s->match_length = 0;
1951: Tracevv((stderr,"%c", s->window[s->strstart]));
1952: _tr_tally_lit (s, s->window[s->strstart], bflush);
1953: s->lookahead--;
1954: s->strstart++;
1955: if (bflush) FLUSH_BLOCK(s, 0);
1956: }
1957: s->insert = 0;
1958: if (flush == Z_FINISH) {
1959: FLUSH_BLOCK(s, 1);
1960: return finish_done;
1961: }
1962: if (s->last_lit)
1963: FLUSH_BLOCK(s, 0);
1964: return block_done;
1965: }
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>
![[BACK]](/icons/cvsweb/back.gif){kind=icon}
Return to deflate.c CVS log ![[TXT]](/icons/cvsweb/text.gif){kind=icon}
![[DIR]](/icons/cvsweb/dir.gif){kind=icon}
Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / sudo / zlib