1: /* deflate.c -- compress data using the deflation algorithm
2: * Copyright (C) 1995-2005 Jean-loup Gailly.
3: * For conditions of distribution and use, see copyright notice in zlib.h
4: */
5:
6: /*
7: * ALGORITHM
8: *
9: * The "deflation" process depends on being able to identify portions
10: * of the input text which are identical to earlier input (within a
11: * sliding window trailing behind the input currently being processed).
12: *
13: * The most straightforward technique turns out to be the fastest for
14: * most input files: try all possible matches and select the longest.
15: * The key feature of this algorithm is that insertions into the string
16: * dictionary are very simple and thus fast, and deletions are avoided
17: * completely. Insertions are performed at each input character, whereas
18: * string matches are performed only when the previous match ends. So it
19: * is preferable to spend more time in matches to allow very fast string
20: * insertions and avoid deletions. The matching algorithm for small
21: * strings is inspired from that of Rabin & Karp. A brute force approach
22: * is used to find longer strings when a small match has been found.
23: * A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
24: * (by Leonid Broukhis).
25: * A previous version of this file used a more sophisticated algorithm
26: * (by Fiala and Greene) which is guaranteed to run in linear amortized
27: * time, but has a larger average cost, uses more memory and is patented.
28: * However the F&G algorithm may be faster for some highly redundant
29: * files if the parameter max_chain_length (described below) is too large.
30: *
31: * ACKNOWLEDGEMENTS
32: *
33: * The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
34: * I found it in 'freeze' written by Leonid Broukhis.
35: * Thanks to many people for bug reports and testing.
36: *
37: * REFERENCES
38: *
39: * Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
40: * Available in http://www.ietf.org/rfc/rfc1951.txt
41: *
42: * A description of the Rabin and Karp algorithm is given in the book
43: * "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
44: *
45: * Fiala,E.R., and Greene,D.H.
46: * Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
47: *
48: */
49:
50: /* @(#) $Id: deflate.c,v 1.1 2012/02/17 15:09:30 misho Exp $ */
51:
52: #include "deflate.h"
53:
54: #define read_buf dread_buf
55:
56: const char deflate_copyright[] =
57: " deflate 1.2.3 Copyright 1995-2005 Jean-loup Gailly ";
58: /*
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.
63: */
64:
65: /* ===========================================================================
66: * Function prototypes.
67: */
68: typedef enum {
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 */
73: } block_state;
74:
75: typedef block_state (*compress_func) OF((deflate_state *s, int flush));
76: /* Compression function. Returns the block state after the call. */
77:
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));
81: #ifndef FASTEST
82: local block_state deflate_slow OF((deflate_state *s, int flush));
83: #endif
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: #ifndef FASTEST
89: #ifdef ASMV
90: void match_init OF((void)); /* asm code initialization */
91: uInt longest_match OF((deflate_state *s, IPos cur_match));
92: #else
93: local uInt longest_match OF((deflate_state *s, IPos cur_match));
94: #endif
95: #endif
96: local uInt longest_match_fast OF((deflate_state *s, IPos cur_match));
97:
98: #ifdef DEBUG
99: local void check_match OF((deflate_state *s, IPos start, IPos match,
100: int length));
101: #endif
102:
103: /* ===========================================================================
104: * Local data
105: */
106:
107: #define NIL 0
108: /* Tail of hash chains */
109:
110: #ifndef TOO_FAR
111: # define TOO_FAR 4096
112: #endif
113: /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
114:
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.
118: */
119:
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.
124: */
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 */
129: ush max_chain;
130: compress_func func;
131: } config;
132:
133: #ifdef FASTEST
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 */
138: #else
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},
145:
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 */
152: #endif
153:
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
156: * meaning.
157: */
158:
159: #define EQUAL 0
160: /* result of memcmp for equal strings */
161:
162: #ifndef NO_DUMMY_DECL
163: struct static_tree_desc_s {int dummy;}; /* for buggy compilers */
164: #endif
165:
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.
171: */
172: #define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)
173:
174:
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).
184: */
185: #ifdef FASTEST
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))
190: #else
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))
195: #endif
196:
197: /* ===========================================================================
198: * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
199: * prev[] will be initialized on the fly.
200: */
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));
204:
205: /* ========================================================================= */
206: int ZEXPORT deflateInit_(strm, level, version, stream_size)
207: z_streamp strm;
208: int level;
209: const char *version;
210: int stream_size;
211: {
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 */
215: }
216:
217: /* ========================================================================= */
218: int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,
219: version, stream_size)
220: z_streamp strm;
221: int level;
222: int method;
223: int windowBits;
224: int memLevel;
225: int strategy;
226: const char *version;
227: int stream_size;
228: {
229: deflate_state *s;
230: int wrap = 1;
231: static const char my_version[] = ZLIB_VERSION;
232:
233: ushf *overlay;
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.
236: */
237:
238: if (version == Z_NULL || version[0] != my_version[0] ||
239: stream_size != sizeof(z_stream)) {
240: return Z_VERSION_ERROR;
241: }
242: if (strm == Z_NULL) return Z_STREAM_ERROR;
243:
244: strm->msg = Z_NULL;
245: if (strm->zalloc == (alloc_func)0) {
246: strm->zalloc = zcalloc;
247: strm->opaque = (voidpf)0;
248: }
249: if (strm->zfree == (free_func)0) strm->zfree = zcfree;
250:
251: #ifdef FASTEST
252: if (level != 0) level = 1;
253: #else
254: if (level == Z_DEFAULT_COMPRESSION) level = 6;
255: #endif
256:
257: if (windowBits < 0) { /* suppress zlib wrapper */
258: wrap = 0;
259: windowBits = -windowBits;
260: }
261: #ifdef GZIP
262: else if (windowBits > 15) {
263: wrap = 2; /* write gzip wrapper instead */
264: windowBits -= 16;
265: }
266: #endif
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_FIXED) {
270: return Z_STREAM_ERROR;
271: }
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;
276: s->strm = strm;
277:
278: s->wrap = wrap;
279: s->gzhead = Z_NULL;
280: s->w_bits = windowBits;
281: s->w_size = 1 << s->w_bits;
282: s->w_mask = s->w_size - 1;
283:
284: s->hash_bits = memLevel + 7;
285: s->hash_size = 1 << s->hash_bits;
286: s->hash_mask = s->hash_size - 1;
287: s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
288:
289: s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
290: s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));
291: s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));
292:
293: s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
294:
295: overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
296: s->pending_buf = (uchf *) overlay;
297: s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
298:
299: if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
300: s->pending_buf == Z_NULL) {
301: s->status = FINISH_STATE;
302: strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
303: deflateEnd (strm);
304: return Z_MEM_ERROR;
305: }
306: s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
307: s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
308:
309: s->level = level;
310: s->strategy = strategy;
311: s->method = (Byte)method;
312:
313: return deflateReset(strm);
314: }
315:
316: /* ========================================================================= */
317: int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)
318: z_streamp strm;
319: const Bytef *dictionary;
320: uInt dictLength;
321: {
322: deflate_state *s;
323: uInt length = dictLength;
324: uInt n;
325: IPos hash_head = 0;
326:
327: if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
328: strm->state->wrap == 2 ||
329: (strm->state->wrap == 1 && strm->state->status != INIT_STATE))
330: return Z_STREAM_ERROR;
331:
332: s = strm->state;
333: if (s->wrap)
334: strm->adler = adler32(strm->adler, dictionary, dictLength);
335:
336: if (length < MIN_MATCH) return Z_OK;
337: if (length > MAX_DIST(s)) {
338: length = MAX_DIST(s);
339: dictionary += dictLength - length; /* use the tail of the dictionary */
340: }
341: zmemcpy(s->window, dictionary, length);
342: s->strstart = length;
343: s->block_start = (long)length;
344:
345: /* Insert all strings in the hash table (except for the last two bytes).
346: * s->lookahead stays null, so s->ins_h will be recomputed at the next
347: * call of fill_window.
348: */
349: s->ins_h = s->window[0];
350: UPDATE_HASH(s, s->ins_h, s->window[1]);
351: for (n = 0; n <= length - MIN_MATCH; n++) {
352: INSERT_STRING(s, n, hash_head);
353: }
354: if (hash_head) hash_head = 0; /* to make compiler happy */
355: return Z_OK;
356: }
357:
358: /* ========================================================================= */
359: int ZEXPORT deflateReset (strm)
360: z_streamp strm;
361: {
362: deflate_state *s;
363:
364: if (strm == Z_NULL || strm->state == Z_NULL ||
365: strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {
366: return Z_STREAM_ERROR;
367: }
368:
369: strm->total_in = strm->total_out = 0;
370: strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
371: strm->data_type = Z_UNKNOWN;
372:
373: s = (deflate_state *)strm->state;
374: s->pending = 0;
375: s->pending_out = s->pending_buf;
376:
377: if (s->wrap < 0) {
378: s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */
379: }
380: s->status = s->wrap ? INIT_STATE : BUSY_STATE;
381: strm->adler =
382: #ifdef GZIP
383: s->wrap == 2 ? crc32(0L, Z_NULL, 0) :
384: #endif
385: adler32(0L, Z_NULL, 0);
386: s->last_flush = Z_NO_FLUSH;
387:
388: _tr_init(s);
389: lm_init(s);
390:
391: return Z_OK;
392: }
393:
394: /* ========================================================================= */
395: int ZEXPORT deflateSetHeader (strm, head)
396: z_streamp strm;
397: gz_headerp head;
398: {
399: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
400: if (strm->state->wrap != 2) return Z_STREAM_ERROR;
401: strm->state->gzhead = head;
402: return Z_OK;
403: }
404:
405: /* ========================================================================= */
406: int ZEXPORT deflatePrime (strm, bits, value)
407: z_streamp strm;
408: int bits;
409: int value;
410: {
411: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
412: strm->state->bi_valid = bits;
413: strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));
414: return Z_OK;
415: }
416:
417: /* ========================================================================= */
418: int ZEXPORT deflateParams(strm, level, strategy)
419: z_streamp strm;
420: int level;
421: int strategy;
422: {
423: deflate_state *s;
424: compress_func func;
425: int err = Z_OK;
426:
427: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
428: s = strm->state;
429:
430: #ifdef FASTEST
431: if (level != 0) level = 1;
432: #else
433: if (level == Z_DEFAULT_COMPRESSION) level = 6;
434: #endif
435: if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {
436: return Z_STREAM_ERROR;
437: }
438: func = configuration_table[s->level].func;
439:
440: if (func != configuration_table[level].func && strm->total_in != 0) {
441: /* Flush the last buffer: */
442: err = deflate(strm, Z_PARTIAL_FLUSH);
443: }
444: if (s->level != level) {
445: s->level = level;
446: s->max_lazy_match = configuration_table[level].max_lazy;
447: s->good_match = configuration_table[level].good_length;
448: s->nice_match = configuration_table[level].nice_length;
449: s->max_chain_length = configuration_table[level].max_chain;
450: }
451: s->strategy = strategy;
452: return err;
453: }
454:
455: /* ========================================================================= */
456: int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)
457: z_streamp strm;
458: int good_length;
459: int max_lazy;
460: int nice_length;
461: int max_chain;
462: {
463: deflate_state *s;
464:
465: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
466: s = strm->state;
467: s->good_match = good_length;
468: s->max_lazy_match = max_lazy;
469: s->nice_match = nice_length;
470: s->max_chain_length = max_chain;
471: return Z_OK;
472: }
473:
474: /* =========================================================================
475: * For the default windowBits of 15 and memLevel of 8, this function returns
476: * a close to exact, as well as small, upper bound on the compressed size.
477: * They are coded as constants here for a reason--if the #define's are
478: * changed, then this function needs to be changed as well. The return
479: * value for 15 and 8 only works for those exact settings.
480: *
481: * For any setting other than those defaults for windowBits and memLevel,
482: * the value returned is a conservative worst case for the maximum expansion
483: * resulting from using fixed blocks instead of stored blocks, which deflate
484: * can emit on compressed data for some combinations of the parameters.
485: *
486: * This function could be more sophisticated to provide closer upper bounds
487: * for every combination of windowBits and memLevel, as well as wrap.
488: * But even the conservative upper bound of about 14% expansion does not
489: * seem onerous for output buffer allocation.
490: */
491: uLong ZEXPORT deflateBound(strm, sourceLen)
492: z_streamp strm;
493: uLong sourceLen;
494: {
495: deflate_state *s;
496: uLong destLen;
497:
498: /* conservative upper bound */
499: destLen = sourceLen +
500: ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11;
501:
502: /* if can't get parameters, return conservative bound */
503: if (strm == Z_NULL || strm->state == Z_NULL)
504: return destLen;
505:
506: /* if not default parameters, return conservative bound */
507: s = strm->state;
508: if (s->w_bits != 15 || s->hash_bits != 8 + 7)
509: return destLen;
510:
511: /* default settings: return tight bound for that case */
512: return compressBound(sourceLen);
513: }
514:
515: /* =========================================================================
516: * Put a short in the pending buffer. The 16-bit value is put in MSB order.
517: * IN assertion: the stream state is correct and there is enough room in
518: * pending_buf.
519: */
520: local void putShortMSB (s, b)
521: deflate_state *s;
522: uInt b;
523: {
524: put_byte(s, (Byte)(b >> 8));
525: put_byte(s, (Byte)(b & 0xff));
526: }
527:
528: /* =========================================================================
529: * Flush as much pending output as possible. All deflate() output goes
530: * through this function so some applications may wish to modify it
531: * to avoid allocating a large strm->next_out buffer and copying into it.
532: * (See also read_buf()).
533: */
534: local void flush_pending(strm)
535: z_streamp strm;
536: {
537: unsigned len = strm->state->pending;
538:
539: if (len > strm->avail_out) len = strm->avail_out;
540: if (len == 0) return;
541:
542: zmemcpy(strm->next_out, strm->state->pending_out, len);
543: strm->next_out += len;
544: strm->state->pending_out += len;
545: strm->total_out += len;
546: strm->avail_out -= len;
547: strm->state->pending -= len;
548: if (strm->state->pending == 0) {
549: strm->state->pending_out = strm->state->pending_buf;
550: }
551: }
552:
553: /* ========================================================================= */
554: int ZEXPORT deflate (strm, flush)
555: z_streamp strm;
556: int flush;
557: {
558: int old_flush; /* value of flush param for previous deflate call */
559: deflate_state *s;
560:
561: if (strm == Z_NULL || strm->state == Z_NULL ||
562: flush > Z_INSERT_ONLY || flush < 0) {
563: return Z_STREAM_ERROR;
564: }
565: s = strm->state;
566:
567: if (strm->next_out == Z_NULL ||
568: (strm->next_in == Z_NULL && strm->avail_in != 0) ||
569: (s->status == FINISH_STATE && flush != Z_FINISH)) {
570: ERR_RETURN(strm, Z_STREAM_ERROR);
571: }
572: if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);
573:
574: s->strm = strm; /* just in case */
575: old_flush = s->last_flush;
576: s->last_flush = flush;
577:
578: /* Write the header */
579: if (s->status == INIT_STATE) {
580: #ifdef GZIP
581: if (s->wrap == 2) {
582: strm->adler = crc32(0L, Z_NULL, 0);
583: put_byte(s, 31);
584: put_byte(s, 139);
585: put_byte(s, 8);
586: if (s->gzhead == NULL) {
587: put_byte(s, 0);
588: put_byte(s, 0);
589: put_byte(s, 0);
590: put_byte(s, 0);
591: put_byte(s, 0);
592: put_byte(s, s->level == 9 ? 2 :
593: (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
594: 4 : 0));
595: put_byte(s, OS_CODE);
596: s->status = BUSY_STATE;
597: }
598: else {
599: put_byte(s, (s->gzhead->text ? 1 : 0) +
600: (s->gzhead->hcrc ? 2 : 0) +
601: (s->gzhead->extra == Z_NULL ? 0 : 4) +
602: (s->gzhead->name == Z_NULL ? 0 : 8) +
603: (s->gzhead->comment == Z_NULL ? 0 : 16)
604: );
605: put_byte(s, (Byte)(s->gzhead->time & 0xff));
606: put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));
607: put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));
608: put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));
609: put_byte(s, s->level == 9 ? 2 :
610: (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?
611: 4 : 0));
612: put_byte(s, s->gzhead->os & 0xff);
613: if (s->gzhead->extra != NULL) {
614: put_byte(s, s->gzhead->extra_len & 0xff);
615: put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);
616: }
617: if (s->gzhead->hcrc)
618: strm->adler = crc32(strm->adler, s->pending_buf,
619: s->pending);
620: s->gzindex = 0;
621: s->status = EXTRA_STATE;
622: }
623: }
624: else
625: #endif
626: {
627: uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
628: uInt level_flags;
629:
630: if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)
631: level_flags = 0;
632: else if (s->level < 6)
633: level_flags = 1;
634: else if (s->level == 6)
635: level_flags = 2;
636: else
637: level_flags = 3;
638: header |= (level_flags << 6);
639: if (s->strstart != 0) header |= PRESET_DICT;
640: header += 31 - (header % 31);
641:
642: s->status = BUSY_STATE;
643: putShortMSB(s, header);
644:
645: /* Save the adler32 of the preset dictionary: */
646: if (s->strstart != 0) {
647: putShortMSB(s, (uInt)(strm->adler >> 16));
648: putShortMSB(s, (uInt)(strm->adler & 0xffff));
649: }
650: strm->adler = adler32(0L, Z_NULL, 0);
651: }
652: }
653: #ifdef GZIP
654: if (s->status == EXTRA_STATE) {
655: if (s->gzhead->extra != NULL) {
656: uInt beg = s->pending; /* start of bytes to update crc */
657:
658: while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {
659: if (s->pending == s->pending_buf_size) {
660: if (s->gzhead->hcrc && s->pending > beg)
661: strm->adler = crc32(strm->adler, s->pending_buf + beg,
662: s->pending - beg);
663: flush_pending(strm);
664: beg = s->pending;
665: if (s->pending == s->pending_buf_size)
666: break;
667: }
668: put_byte(s, s->gzhead->extra[s->gzindex]);
669: s->gzindex++;
670: }
671: if (s->gzhead->hcrc && s->pending > beg)
672: strm->adler = crc32(strm->adler, s->pending_buf + beg,
673: s->pending - beg);
674: if (s->gzindex == s->gzhead->extra_len) {
675: s->gzindex = 0;
676: s->status = NAME_STATE;
677: }
678: }
679: else
680: s->status = NAME_STATE;
681: }
682: if (s->status == NAME_STATE) {
683: if (s->gzhead->name != NULL) {
684: uInt beg = s->pending; /* start of bytes to update crc */
685: int val;
686:
687: do {
688: if (s->pending == s->pending_buf_size) {
689: if (s->gzhead->hcrc && s->pending > beg)
690: strm->adler = crc32(strm->adler, s->pending_buf + beg,
691: s->pending - beg);
692: flush_pending(strm);
693: beg = s->pending;
694: if (s->pending == s->pending_buf_size) {
695: val = 1;
696: break;
697: }
698: }
699: val = s->gzhead->name[s->gzindex++];
700: put_byte(s, val);
701: } while (val != 0);
702: if (s->gzhead->hcrc && s->pending > beg)
703: strm->adler = crc32(strm->adler, s->pending_buf + beg,
704: s->pending - beg);
705: if (val == 0) {
706: s->gzindex = 0;
707: s->status = COMMENT_STATE;
708: }
709: }
710: else
711: s->status = COMMENT_STATE;
712: }
713: if (s->status == COMMENT_STATE) {
714: if (s->gzhead->comment != NULL) {
715: uInt beg = s->pending; /* start of bytes to update crc */
716: int val;
717:
718: do {
719: if (s->pending == s->pending_buf_size) {
720: if (s->gzhead->hcrc && s->pending > beg)
721: strm->adler = crc32(strm->adler, s->pending_buf + beg,
722: s->pending - beg);
723: flush_pending(strm);
724: beg = s->pending;
725: if (s->pending == s->pending_buf_size) {
726: val = 1;
727: break;
728: }
729: }
730: val = s->gzhead->comment[s->gzindex++];
731: put_byte(s, val);
732: } while (val != 0);
733: if (s->gzhead->hcrc && s->pending > beg)
734: strm->adler = crc32(strm->adler, s->pending_buf + beg,
735: s->pending - beg);
736: if (val == 0)
737: s->status = HCRC_STATE;
738: }
739: else
740: s->status = HCRC_STATE;
741: }
742: if (s->status == HCRC_STATE) {
743: if (s->gzhead->hcrc) {
744: if (s->pending + 2 > s->pending_buf_size)
745: flush_pending(strm);
746: if (s->pending + 2 <= s->pending_buf_size) {
747: put_byte(s, (Byte)(strm->adler & 0xff));
748: put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
749: strm->adler = crc32(0L, Z_NULL, 0);
750: s->status = BUSY_STATE;
751: }
752: }
753: else
754: s->status = BUSY_STATE;
755: }
756: #endif
757:
758: /* Flush as much pending output as possible */
759: if (s->pending != 0) {
760: flush_pending(strm);
761: if (strm->avail_out == 0) {
762: /* Since avail_out is 0, deflate will be called again with
763: * more output space, but possibly with both pending and
764: * avail_in equal to zero. There won't be anything to do,
765: * but this is not an error situation so make sure we
766: * return OK instead of BUF_ERROR at next call of deflate:
767: */
768: s->last_flush = -1;
769: return Z_OK;
770: }
771:
772: /* Make sure there is something to do and avoid duplicate consecutive
773: * flushes. For repeated and useless calls with Z_FINISH, we keep
774: * returning Z_STREAM_END instead of Z_BUF_ERROR.
775: */
776: } else if (strm->avail_in == 0 && flush <= old_flush &&
777: flush != Z_FINISH) {
778: ERR_RETURN(strm, Z_BUF_ERROR);
779: }
780:
781: /* User must not provide more input after the first FINISH: */
782: if (s->status == FINISH_STATE && strm->avail_in != 0) {
783: ERR_RETURN(strm, Z_BUF_ERROR);
784: }
785:
786: /* Start a new block or continue the current one.
787: */
788: if (strm->avail_in != 0 || s->lookahead != 0 ||
789: (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
790: block_state bstate;
791:
792: bstate = (*(configuration_table[s->level].func))(s, flush);
793:
794: if (bstate == finish_started || bstate == finish_done) {
795: s->status = FINISH_STATE;
796: }
797: if (bstate == need_more || bstate == finish_started) {
798: if (strm->avail_out == 0) {
799: s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
800: }
801: return Z_OK;
802: /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
803: * of deflate should use the same flush parameter to make sure
804: * that the flush is complete. So we don't have to output an
805: * empty block here, this will be done at next call. This also
806: * ensures that for a very small output buffer, we emit at most
807: * one empty block.
808: */
809: }
810: if (bstate == block_done) {
811: if (flush == Z_PARTIAL_FLUSH) {
812: _tr_align(s);
813: } else { /* FULL_FLUSH or SYNC_FLUSH */
814: _tr_stored_block(s, (char*)0, 0L, 0);
815: /* For a full flush, this empty block will be recognized
816: * as a special marker by inflate_sync().
817: */
818: if (flush == Z_FULL_FLUSH) {
819: CLEAR_HASH(s); /* forget history */
820: }
821: }
822: flush_pending(strm);
823: if (strm->avail_out == 0) {
824: s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
825: return Z_OK;
826: }
827: }
828: }
829: Assert(strm->avail_out > 0, "bug2");
830:
831: if (flush != Z_FINISH) return Z_OK;
832: if (s->wrap <= 0) return Z_STREAM_END;
833:
834: /* Write the trailer */
835: #ifdef GZIP
836: if (s->wrap == 2) {
837: put_byte(s, (Byte)(strm->adler & 0xff));
838: put_byte(s, (Byte)((strm->adler >> 8) & 0xff));
839: put_byte(s, (Byte)((strm->adler >> 16) & 0xff));
840: put_byte(s, (Byte)((strm->adler >> 24) & 0xff));
841: put_byte(s, (Byte)(strm->total_in & 0xff));
842: put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));
843: put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));
844: put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));
845: }
846: else
847: #endif
848: {
849: putShortMSB(s, (uInt)(strm->adler >> 16));
850: putShortMSB(s, (uInt)(strm->adler & 0xffff));
851: }
852: flush_pending(strm);
853: /* If avail_out is zero, the application will call deflate again
854: * to flush the rest.
855: */
856: if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */
857: return s->pending != 0 ? Z_OK : Z_STREAM_END;
858: }
859:
860: /* ========================================================================= */
861: int ZEXPORT deflateEnd (strm)
862: z_streamp strm;
863: {
864: int status;
865:
866: if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;
867:
868: status = strm->state->status;
869: if (status != INIT_STATE &&
870: status != EXTRA_STATE &&
871: status != NAME_STATE &&
872: status != COMMENT_STATE &&
873: status != HCRC_STATE &&
874: status != BUSY_STATE &&
875: status != FINISH_STATE) {
876: return Z_STREAM_ERROR;
877: }
878:
879: /* Deallocate in reverse order of allocations: */
880: TRY_FREE(strm, strm->state->pending_buf);
881: TRY_FREE(strm, strm->state->head);
882: TRY_FREE(strm, strm->state->prev);
883: TRY_FREE(strm, strm->state->window);
884:
885: ZFREE(strm, strm->state);
886: strm->state = Z_NULL;
887:
888: return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
889: }
890:
891: /* =========================================================================
892: * Copy the source state to the destination state.
893: * To simplify the source, this is not supported for 16-bit MSDOS (which
894: * doesn't have enough memory anyway to duplicate compression states).
895: */
896: int ZEXPORT deflateCopy (dest, source)
897: z_streamp dest;
898: z_streamp source;
899: {
900: #ifdef MAXSEG_64K
901: return Z_STREAM_ERROR;
902: #else
903: deflate_state *ds;
904: deflate_state *ss;
905: ushf *overlay;
906:
907:
908: if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
909: return Z_STREAM_ERROR;
910: }
911:
912: ss = source->state;
913:
914: zmemcpy(dest, source, sizeof(z_stream));
915:
916: ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
917: if (ds == Z_NULL) return Z_MEM_ERROR;
918: dest->state = (struct internal_state FAR *) ds;
919: zmemcpy(ds, ss, sizeof(deflate_state));
920: ds->strm = dest;
921:
922: ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
923: ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));
924: ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));
925: overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
926: ds->pending_buf = (uchf *) overlay;
927:
928: if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
929: ds->pending_buf == Z_NULL) {
930: deflateEnd (dest);
931: return Z_MEM_ERROR;
932: }
933: /* following zmemcpy do not work for 16-bit MSDOS */
934: zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
935: zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
936: zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
937: zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
938:
939: ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
940: ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
941: ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
942:
943: ds->l_desc.dyn_tree = ds->dyn_ltree;
944: ds->d_desc.dyn_tree = ds->dyn_dtree;
945: ds->bl_desc.dyn_tree = ds->bl_tree;
946:
947: return Z_OK;
948: #endif /* MAXSEG_64K */
949: }
950:
951: /* ===========================================================================
952: * Read a new buffer from the current input stream, update the adler32
953: * and total number of bytes read. All deflate() input goes through
954: * this function so some applications may wish to modify it to avoid
955: * allocating a large strm->next_in buffer and copying from it.
956: * (See also flush_pending()).
957: */
958: local int read_buf(strm, buf, size)
959: z_streamp strm;
960: Bytef *buf;
961: unsigned size;
962: {
963: unsigned len = strm->avail_in;
964:
965: if (len > size) len = size;
966: if (len == 0) return 0;
967:
968: strm->avail_in -= len;
969:
970: if (strm->state->wrap == 1) {
971: strm->adler = adler32(strm->adler, strm->next_in, len);
972: }
973: #ifdef GZIP
974: else if (strm->state->wrap == 2) {
975: strm->adler = crc32(strm->adler, strm->next_in, len);
976: }
977: #endif
978: zmemcpy(buf, strm->next_in, len);
979: strm->next_in += len;
980: strm->total_in += len;
981:
982: return (int)len;
983: }
984:
985: /* ===========================================================================
986: * Initialize the "longest match" routines for a new zlib stream
987: */
988: local void lm_init (s)
989: deflate_state *s;
990: {
991: s->window_size = (ulg)2L*s->w_size;
992:
993: CLEAR_HASH(s);
994:
995: /* Set the default configuration parameters:
996: */
997: s->max_lazy_match = configuration_table[s->level].max_lazy;
998: s->good_match = configuration_table[s->level].good_length;
999: s->nice_match = configuration_table[s->level].nice_length;
1000: s->max_chain_length = configuration_table[s->level].max_chain;
1001:
1002: s->strstart = 0;
1003: s->block_start = 0L;
1004: s->lookahead = 0;
1005: s->match_length = s->prev_length = MIN_MATCH-1;
1006: s->match_available = 0;
1007: s->ins_h = 0;
1008: #ifndef FASTEST
1009: #ifdef ASMV
1010: match_init(); /* initialize the asm code */
1011: #endif
1012: #endif
1013: }
1014:
1015: #ifndef FASTEST
1016: /* ===========================================================================
1017: * Set match_start to the longest match starting at the given string and
1018: * return its length. Matches shorter or equal to prev_length are discarded,
1019: * in which case the result is equal to prev_length and match_start is
1020: * garbage.
1021: * IN assertions: cur_match is the head of the hash chain for the current
1022: * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
1023: * OUT assertion: the match length is not greater than s->lookahead.
1024: */
1025: #ifndef ASMV
1026: /* For 80x86 and 680x0, an optimized version will be provided in match.asm or
1027: * match.S. The code will be functionally equivalent.
1028: */
1029: local uInt longest_match(s, cur_match)
1030: deflate_state *s;
1031: IPos cur_match; /* current match */
1032: {
1033: unsigned chain_length = s->max_chain_length;/* max hash chain length */
1034: register Bytef *scan = s->window + s->strstart; /* current string */
1035: register Bytef *match; /* matched string */
1036: register int len; /* length of current match */
1037: int best_len = s->prev_length; /* best match length so far */
1038: int nice_match = s->nice_match; /* stop if match long enough */
1039: IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
1040: s->strstart - (IPos)MAX_DIST(s) : NIL;
1041: /* Stop when cur_match becomes <= limit. To simplify the code,
1042: * we prevent matches with the string of window index 0.
1043: */
1044: Posf *prev = s->prev;
1045: uInt wmask = s->w_mask;
1046:
1047: #ifdef UNALIGNED_OK
1048: /* Compare two bytes at a time. Note: this is not always beneficial.
1049: * Try with and without -DUNALIGNED_OK to check.
1050: */
1051: register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
1052: register ush scan_start = *(ushf*)scan;
1053: register ush scan_end = *(ushf*)(scan+best_len-1);
1054: #else
1055: register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1056: register Byte scan_end1 = scan[best_len-1];
1057: register Byte scan_end = scan[best_len];
1058: #endif
1059:
1060: /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1061: * It is easy to get rid of this optimization if necessary.
1062: */
1063: Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1064:
1065: /* Do not waste too much time if we already have a good match: */
1066: if (s->prev_length >= s->good_match) {
1067: chain_length >>= 2;
1068: }
1069: /* Do not look for matches beyond the end of the input. This is necessary
1070: * to make deflate deterministic.
1071: */
1072: if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
1073:
1074: Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1075:
1076: do {
1077: Assert(cur_match < s->strstart, "no future");
1078: match = s->window + cur_match;
1079:
1080: /* Skip to next match if the match length cannot increase
1081: * or if the match length is less than 2. Note that the checks below
1082: * for insufficient lookahead only occur occasionally for performance
1083: * reasons. Therefore uninitialized memory will be accessed, and
1084: * conditional jumps will be made that depend on those values.
1085: * However the length of the match is limited to the lookahead, so
1086: * the output of deflate is not affected by the uninitialized values.
1087: */
1088: #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
1089: /* This code assumes sizeof(unsigned short) == 2. Do not use
1090: * UNALIGNED_OK if your compiler uses a different size.
1091: */
1092: if (*(ushf*)(match+best_len-1) != scan_end ||
1093: *(ushf*)match != scan_start) continue;
1094:
1095: /* It is not necessary to compare scan[2] and match[2] since they are
1096: * always equal when the other bytes match, given that the hash keys
1097: * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
1098: * strstart+3, +5, ... up to strstart+257. We check for insufficient
1099: * lookahead only every 4th comparison; the 128th check will be made
1100: * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
1101: * necessary to put more guard bytes at the end of the window, or
1102: * to check more often for insufficient lookahead.
1103: */
1104: Assert(scan[2] == match[2], "scan[2]?");
1105: scan++, match++;
1106: do {
1107: } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1108: *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1109: *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1110: *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
1111: scan < strend);
1112: /* The funny "do {}" generates better code on most compilers */
1113:
1114: /* Here, scan <= window+strstart+257 */
1115: Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1116: if (*scan == *match) scan++;
1117:
1118: len = (MAX_MATCH - 1) - (int)(strend-scan);
1119: scan = strend - (MAX_MATCH-1);
1120:
1121: #else /* UNALIGNED_OK */
1122:
1123: if (match[best_len] != scan_end ||
1124: match[best_len-1] != scan_end1 ||
1125: *match != *scan ||
1126: *++match != scan[1]) continue;
1127:
1128: /* The check at best_len-1 can be removed because it will be made
1129: * again later. (This heuristic is not always a win.)
1130: * It is not necessary to compare scan[2] and match[2] since they
1131: * are always equal when the other bytes match, given that
1132: * the hash keys are equal and that HASH_BITS >= 8.
1133: */
1134: scan += 2, match++;
1135: Assert(*scan == *match, "match[2]?");
1136:
1137: /* We check for insufficient lookahead only every 8th comparison;
1138: * the 256th check will be made at strstart+258.
1139: */
1140: do {
1141: } while (*++scan == *++match && *++scan == *++match &&
1142: *++scan == *++match && *++scan == *++match &&
1143: *++scan == *++match && *++scan == *++match &&
1144: *++scan == *++match && *++scan == *++match &&
1145: scan < strend);
1146:
1147: Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1148:
1149: len = MAX_MATCH - (int)(strend - scan);
1150: scan = strend - MAX_MATCH;
1151:
1152: #endif /* UNALIGNED_OK */
1153:
1154: if (len > best_len) {
1155: s->match_start = cur_match;
1156: best_len = len;
1157: if (len >= nice_match) break;
1158: #ifdef UNALIGNED_OK
1159: scan_end = *(ushf*)(scan+best_len-1);
1160: #else
1161: scan_end1 = scan[best_len-1];
1162: scan_end = scan[best_len];
1163: #endif
1164: }
1165: } while ((cur_match = prev[cur_match & wmask]) > limit
1166: && --chain_length != 0);
1167:
1168: if ((uInt)best_len <= s->lookahead) return (uInt)best_len;
1169: return s->lookahead;
1170: }
1171: #endif /* ASMV */
1172: #endif /* FASTEST */
1173:
1174: /* ---------------------------------------------------------------------------
1175: * Optimized version for level == 1 or strategy == Z_RLE only
1176: */
1177: local uInt longest_match_fast(s, cur_match)
1178: deflate_state *s;
1179: IPos cur_match; /* current match */
1180: {
1181: register Bytef *scan = s->window + s->strstart; /* current string */
1182: register Bytef *match; /* matched string */
1183: register int len; /* length of current match */
1184: register Bytef *strend = s->window + s->strstart + MAX_MATCH;
1185:
1186: /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
1187: * It is easy to get rid of this optimization if necessary.
1188: */
1189: Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
1190:
1191: Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
1192:
1193: Assert(cur_match < s->strstart, "no future");
1194:
1195: match = s->window + cur_match;
1196:
1197: /* Return failure if the match length is less than 2:
1198: */
1199: if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;
1200:
1201: /* The check at best_len-1 can be removed because it will be made
1202: * again later. (This heuristic is not always a win.)
1203: * It is not necessary to compare scan[2] and match[2] since they
1204: * are always equal when the other bytes match, given that
1205: * the hash keys are equal and that HASH_BITS >= 8.
1206: */
1207: scan += 2, match += 2;
1208: Assert(*scan == *match, "match[2]?");
1209:
1210: /* We check for insufficient lookahead only every 8th comparison;
1211: * the 256th check will be made at strstart+258.
1212: */
1213: do {
1214: } while (*++scan == *++match && *++scan == *++match &&
1215: *++scan == *++match && *++scan == *++match &&
1216: *++scan == *++match && *++scan == *++match &&
1217: *++scan == *++match && *++scan == *++match &&
1218: scan < strend);
1219:
1220: Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
1221:
1222: len = MAX_MATCH - (int)(strend - scan);
1223:
1224: if (len < MIN_MATCH) return MIN_MATCH - 1;
1225:
1226: s->match_start = cur_match;
1227: return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;
1228: }
1229:
1230: #ifdef DEBUG
1231: /* ===========================================================================
1232: * Check that the match at match_start is indeed a match.
1233: */
1234: local void check_match(s, start, match, length)
1235: deflate_state *s;
1236: IPos start, match;
1237: int length;
1238: {
1239: /* check that the match is indeed a match */
1240: if (zmemcmp(s->window + match,
1241: s->window + start, length) != EQUAL) {
1242: fprintf(stderr, " start %u, match %u, length %d\n",
1243: start, match, length);
1244: do {
1245: fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
1246: } while (--length != 0);
1247: z_error("invalid match");
1248: }
1249: if (z_verbose > 1) {
1250: fprintf(stderr,"\\[%d,%d]", start-match, length);
1251: do { putc(s->window[start++], stderr); } while (--length != 0);
1252: }
1253: }
1254: #else
1255: # define check_match(s, start, match, length)
1256: #endif /* DEBUG */
1257:
1258: /* ===========================================================================
1259: * Fill the window when the lookahead becomes insufficient.
1260: * Updates strstart and lookahead.
1261: *
1262: * IN assertion: lookahead < MIN_LOOKAHEAD
1263: * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
1264: * At least one byte has been read, or avail_in == 0; reads are
1265: * performed for at least two bytes (required for the zip translate_eol
1266: * option -- not supported here).
1267: */
1268: local void fill_window(s)
1269: deflate_state *s;
1270: {
1271: register unsigned n, m;
1272: register Posf *p;
1273: unsigned more; /* Amount of free space at the end of the window. */
1274: uInt wsize = s->w_size;
1275:
1276: do {
1277: more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
1278:
1279: /* Deal with !@#$% 64K limit: */
1280: if (sizeof(int) <= 2) {
1281: if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
1282: more = wsize;
1283:
1284: } else if (more == (unsigned)(-1)) {
1285: /* Very unlikely, but possible on 16 bit machine if
1286: * strstart == 0 && lookahead == 1 (input done a byte at time)
1287: */
1288: more--;
1289: }
1290: }
1291:
1292: /* If the window is almost full and there is insufficient lookahead,
1293: * move the upper half to the lower one to make room in the upper half.
1294: */
1295: if (s->strstart >= wsize+MAX_DIST(s)) {
1296:
1297: zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
1298: s->match_start -= wsize;
1299: s->strstart -= wsize; /* we now have strstart >= MAX_DIST */
1300: s->block_start -= (long) wsize;
1301:
1302: /* Slide the hash table (could be avoided with 32 bit values
1303: at the expense of memory usage). We slide even when level == 0
1304: to keep the hash table consistent if we switch back to level > 0
1305: later. (Using level 0 permanently is not an optimal usage of
1306: zlib, so we don't care about this pathological case.)
1307: */
1308: /* %%% avoid this when Z_RLE */
1309: n = s->hash_size;
1310: p = &s->head[n];
1311: do {
1312: m = *--p;
1313: *p = (Pos)(m >= wsize ? m-wsize : NIL);
1314: } while (--n);
1315:
1316: n = wsize;
1317: #ifndef FASTEST
1318: p = &s->prev[n];
1319: do {
1320: m = *--p;
1321: *p = (Pos)(m >= wsize ? m-wsize : NIL);
1322: /* If n is not on any hash chain, prev[n] is garbage but
1323: * its value will never be used.
1324: */
1325: } while (--n);
1326: #endif
1327: more += wsize;
1328: }
1329: if (s->strm->avail_in == 0) return;
1330:
1331: /* If there was no sliding:
1332: * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
1333: * more == window_size - lookahead - strstart
1334: * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
1335: * => more >= window_size - 2*WSIZE + 2
1336: * In the BIG_MEM or MMAP case (not yet supported),
1337: * window_size == input_size + MIN_LOOKAHEAD &&
1338: * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
1339: * Otherwise, window_size == 2*WSIZE so more >= 2.
1340: * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
1341: */
1342: Assert(more >= 2, "more < 2");
1343:
1344: n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
1345: s->lookahead += n;
1346:
1347: /* Initialize the hash value now that we have some input: */
1348: if (s->lookahead >= MIN_MATCH) {
1349: s->ins_h = s->window[s->strstart];
1350: UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1351: #if MIN_MATCH != 3
1352: Call UPDATE_HASH() MIN_MATCH-3 more times
1353: #endif
1354: }
1355: /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
1356: * but this is not important since only literal bytes will be emitted.
1357: */
1358:
1359: } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
1360: }
1361:
1362: /* ===========================================================================
1363: * Flush the current block, with given end-of-file flag.
1364: * IN assertion: strstart is set to the end of the current match.
1365: */
1366: #define FLUSH_BLOCK_ONLY(s, eof) { \
1367: _tr_flush_block(s, (s->block_start >= 0L ? \
1368: (charf *)&s->window[(unsigned)s->block_start] : \
1369: (charf *)Z_NULL), \
1370: (ulg)((long)s->strstart - s->block_start), \
1371: (eof)); \
1372: s->block_start = s->strstart; \
1373: flush_pending(s->strm); \
1374: Tracev((stderr,"[FLUSH]")); \
1375: }
1376:
1377: /* Same but force premature exit if necessary. */
1378: #define FLUSH_BLOCK(s, eof) { \
1379: FLUSH_BLOCK_ONLY(s, eof); \
1380: if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
1381: }
1382:
1383: /* ===========================================================================
1384: * Copy without compression as much as possible from the input stream, return
1385: * the current block state.
1386: * This function does not insert new strings in the dictionary since
1387: * uncompressible data is probably not useful. This function is used
1388: * only for the level=0 compression option.
1389: * NOTE: this function should be optimized to avoid extra copying from
1390: * window to pending_buf.
1391: */
1392: local block_state deflate_stored(s, flush)
1393: deflate_state *s;
1394: int flush;
1395: {
1396: /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
1397: * to pending_buf_size, and each stored block has a 5 byte header:
1398: */
1399: ulg max_block_size = 0xffff;
1400: ulg max_start;
1401:
1402: if (max_block_size > s->pending_buf_size - 5) {
1403: max_block_size = s->pending_buf_size - 5;
1404: }
1405:
1406: /* Copy as much as possible from input to output: */
1407: for (;;) {
1408: /* Fill the window as much as possible: */
1409: if (s->lookahead <= 1) {
1410:
1411: Assert(s->strstart < s->w_size+MAX_DIST(s) ||
1412: s->block_start >= (long)s->w_size, "slide too late");
1413:
1414: fill_window(s);
1415: if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;
1416:
1417: if (s->lookahead == 0) break; /* flush the current block */
1418: }
1419: Assert(s->block_start >= 0L, "block gone");
1420:
1421: s->strstart += s->lookahead;
1422: s->lookahead = 0;
1423:
1424: if (flush == Z_INSERT_ONLY) {
1425: s->block_start = s->strstart;
1426: continue;
1427: }
1428:
1429: /* Emit a stored block if pending_buf will be full: */
1430: max_start = s->block_start + max_block_size;
1431: if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
1432: /* strstart == 0 is possible when wraparound on 16-bit machine */
1433: s->lookahead = (uInt)(s->strstart - max_start);
1434: s->strstart = (uInt)max_start;
1435: FLUSH_BLOCK(s, 0);
1436: }
1437: /* Flush if we may have to slide, otherwise block_start may become
1438: * negative and the data will be gone:
1439: */
1440: if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
1441: FLUSH_BLOCK(s, 0);
1442: }
1443: }
1444: if (flush == Z_INSERT_ONLY) {
1445: s->block_start = s->strstart;
1446: return need_more;
1447: }
1448:
1449: FLUSH_BLOCK(s, flush == Z_FINISH);
1450: return flush == Z_FINISH ? finish_done : block_done;
1451: }
1452:
1453: /* ===========================================================================
1454: * Compress as much as possible from the input stream, return the current
1455: * block state.
1456: * This function does not perform lazy evaluation of matches and inserts
1457: * new strings in the dictionary only for unmatched strings or for short
1458: * matches. It is used only for the fast compression options.
1459: */
1460: local block_state deflate_fast(s, flush)
1461: deflate_state *s;
1462: int flush;
1463: {
1464: IPos hash_head = NIL; /* head of the hash chain */
1465: int bflush; /* set if current block must be flushed */
1466:
1467: for (;;) {
1468: /* Make sure that we always have enough lookahead, except
1469: * at the end of the input file. We need MAX_MATCH bytes
1470: * for the next match, plus MIN_MATCH bytes to insert the
1471: * string following the next match.
1472: */
1473: if (s->lookahead < MIN_LOOKAHEAD) {
1474: fill_window(s);
1475: if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1476: return need_more;
1477: }
1478: if (s->lookahead == 0) break; /* flush the current block */
1479: }
1480:
1481: /* Insert the string window[strstart .. strstart+2] in the
1482: * dictionary, and set hash_head to the head of the hash chain:
1483: */
1484: if (s->lookahead >= MIN_MATCH) {
1485: INSERT_STRING(s, s->strstart, hash_head);
1486: }
1487:
1488: if (flush == Z_INSERT_ONLY) {
1489: s->strstart++;
1490: s->lookahead--;
1491: continue;
1492: }
1493:
1494: /* Find the longest match, discarding those <= prev_length.
1495: * At this point we have always match_length < MIN_MATCH
1496: */
1497: if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
1498: /* To simplify the code, we prevent matches with the string
1499: * of window index 0 (in particular we have to avoid a match
1500: * of the string with itself at the start of the input file).
1501: */
1502: #ifdef FASTEST
1503: if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) ||
1504: (s->strategy == Z_RLE && s->strstart - hash_head == 1)) {
1505: s->match_length = longest_match_fast (s, hash_head);
1506: }
1507: #else
1508: if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1509: s->match_length = longest_match (s, hash_head);
1510: } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1511: s->match_length = longest_match_fast (s, hash_head);
1512: }
1513: #endif
1514: /* longest_match() or longest_match_fast() sets match_start */
1515: }
1516: if (s->match_length >= MIN_MATCH) {
1517: check_match(s, s->strstart, s->match_start, s->match_length);
1518:
1519: _tr_tally_dist(s, s->strstart - s->match_start,
1520: s->match_length - MIN_MATCH, bflush);
1521:
1522: s->lookahead -= s->match_length;
1523:
1524: /* Insert new strings in the hash table only if the match length
1525: * is not too large. This saves time but degrades compression.
1526: */
1527: #ifndef FASTEST
1528: if (s->match_length <= s->max_insert_length &&
1529: s->lookahead >= MIN_MATCH) {
1530: s->match_length--; /* string at strstart already in table */
1531: do {
1532: s->strstart++;
1533: INSERT_STRING(s, s->strstart, hash_head);
1534: /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1535: * always MIN_MATCH bytes ahead.
1536: */
1537: } while (--s->match_length != 0);
1538: s->strstart++;
1539: } else
1540: #endif
1541: {
1542: s->strstart += s->match_length;
1543: s->match_length = 0;
1544: s->ins_h = s->window[s->strstart];
1545: UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
1546: #if MIN_MATCH != 3
1547: Call UPDATE_HASH() MIN_MATCH-3 more times
1548: #endif
1549: /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
1550: * matter since it will be recomputed at next deflate call.
1551: */
1552: }
1553: } else {
1554: /* No match, output a literal byte */
1555: Tracevv((stderr,"%c", s->window[s->strstart]));
1556: _tr_tally_lit (s, s->window[s->strstart], bflush);
1557: s->lookahead--;
1558: s->strstart++;
1559: }
1560: if (bflush) FLUSH_BLOCK(s, 0);
1561: }
1562: if (flush == Z_INSERT_ONLY) {
1563: s->block_start = s->strstart;
1564: return need_more;
1565: }
1566: FLUSH_BLOCK(s, flush == Z_FINISH);
1567: return flush == Z_FINISH ? finish_done : block_done;
1568: }
1569:
1570: #ifndef FASTEST
1571: /* ===========================================================================
1572: * Same as above, but achieves better compression. We use a lazy
1573: * evaluation for matches: a match is finally adopted only if there is
1574: * no better match at the next window position.
1575: */
1576: local block_state deflate_slow(s, flush)
1577: deflate_state *s;
1578: int flush;
1579: {
1580: IPos hash_head = NIL; /* head of hash chain */
1581: int bflush; /* set if current block must be flushed */
1582:
1583: /* Process the input block. */
1584: for (;;) {
1585: /* Make sure that we always have enough lookahead, except
1586: * at the end of the input file. We need MAX_MATCH bytes
1587: * for the next match, plus MIN_MATCH bytes to insert the
1588: * string following the next match.
1589: */
1590: if (s->lookahead < MIN_LOOKAHEAD) {
1591: fill_window(s);
1592: if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
1593: return need_more;
1594: }
1595: if (s->lookahead == 0) break; /* flush the current block */
1596: }
1597:
1598: /* Insert the string window[strstart .. strstart+2] in the
1599: * dictionary, and set hash_head to the head of the hash chain:
1600: */
1601: if (s->lookahead >= MIN_MATCH) {
1602: INSERT_STRING(s, s->strstart, hash_head);
1603: }
1604:
1605: if (flush == Z_INSERT_ONLY) {
1606: s->strstart++;
1607: s->lookahead--;
1608: continue;
1609: }
1610:
1611: /* Find the longest match, discarding those <= prev_length.
1612: */
1613: s->prev_length = s->match_length, s->prev_match = s->match_start;
1614: s->match_length = MIN_MATCH-1;
1615:
1616: if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
1617: s->strstart - hash_head <= MAX_DIST(s)) {
1618: /* To simplify the code, we prevent matches with the string
1619: * of window index 0 (in particular we have to avoid a match
1620: * of the string with itself at the start of the input file).
1621: */
1622: if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) {
1623: s->match_length = longest_match (s, hash_head);
1624: } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) {
1625: s->match_length = longest_match_fast (s, hash_head);
1626: }
1627: /* longest_match() or longest_match_fast() sets match_start */
1628:
1629: if (s->match_length <= 5 && (s->strategy == Z_FILTERED
1630: #if TOO_FAR <= 32767
1631: || (s->match_length == MIN_MATCH &&
1632: s->strstart - s->match_start > TOO_FAR)
1633: #endif
1634: )) {
1635:
1636: /* If prev_match is also MIN_MATCH, match_start is garbage
1637: * but we will ignore the current match anyway.
1638: */
1639: s->match_length = MIN_MATCH-1;
1640: }
1641: }
1642: /* If there was a match at the previous step and the current
1643: * match is not better, output the previous match:
1644: */
1645: if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
1646: uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
1647: /* Do not insert strings in hash table beyond this. */
1648:
1649: check_match(s, s->strstart-1, s->prev_match, s->prev_length);
1650:
1651: _tr_tally_dist(s, s->strstart -1 - s->prev_match,
1652: s->prev_length - MIN_MATCH, bflush);
1653:
1654: /* Insert in hash table all strings up to the end of the match.
1655: * strstart-1 and strstart are already inserted. If there is not
1656: * enough lookahead, the last two strings are not inserted in
1657: * the hash table.
1658: */
1659: s->lookahead -= s->prev_length-1;
1660: s->prev_length -= 2;
1661: do {
1662: if (++s->strstart <= max_insert) {
1663: INSERT_STRING(s, s->strstart, hash_head);
1664: }
1665: } while (--s->prev_length != 0);
1666: s->match_available = 0;
1667: s->match_length = MIN_MATCH-1;
1668: s->strstart++;
1669:
1670: if (bflush) FLUSH_BLOCK(s, 0);
1671:
1672: } else if (s->match_available) {
1673: /* If there was no match at the previous position, output a
1674: * single literal. If there was a match but the current match
1675: * is longer, truncate the previous match to a single literal.
1676: */
1677: Tracevv((stderr,"%c", s->window[s->strstart-1]));
1678: _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1679: if (bflush) {
1680: FLUSH_BLOCK_ONLY(s, 0);
1681: }
1682: s->strstart++;
1683: s->lookahead--;
1684: if (s->strm->avail_out == 0) return need_more;
1685: } else {
1686: /* There is no previous match to compare with, wait for
1687: * the next step to decide.
1688: */
1689: s->match_available = 1;
1690: s->strstart++;
1691: s->lookahead--;
1692: }
1693: }
1694: if (flush == Z_INSERT_ONLY) {
1695: s->block_start = s->strstart;
1696: return need_more;
1697: }
1698: Assert (flush != Z_NO_FLUSH, "no flush?");
1699: if (s->match_available) {
1700: Tracevv((stderr,"%c", s->window[s->strstart-1]));
1701: _tr_tally_lit(s, s->window[s->strstart-1], bflush);
1702: s->match_available = 0;
1703: }
1704: FLUSH_BLOCK(s, flush == Z_FINISH);
1705: return flush == Z_FINISH ? finish_done : block_done;
1706: }
1707: #endif /* FASTEST */
1708:
1709: #if 0
1710: /* ===========================================================================
1711: * For Z_RLE, simply look for runs of bytes, generate matches only of distance
1712: * one. Do not maintain a hash table. (It will be regenerated if this run of
1713: * deflate switches away from Z_RLE.)
1714: */
1715: local block_state deflate_rle(s, flush)
1716: deflate_state *s;
1717: int flush;
1718: {
1719: int bflush; /* set if current block must be flushed */
1720: uInt run; /* length of run */
1721: uInt max; /* maximum length of run */
1722: uInt prev; /* byte at distance one to match */
1723: Bytef *scan; /* scan for end of run */
1724:
1725: for (;;) {
1726: /* Make sure that we always have enough lookahead, except
1727: * at the end of the input file. We need MAX_MATCH bytes
1728: * for the longest encodable run.
1729: */
1730: if (s->lookahead < MAX_MATCH) {
1731: fill_window(s);
1732: if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {
1733: return need_more;
1734: }
1735: if (s->lookahead == 0) break; /* flush the current block */
1736: }
1737:
1738: /* See how many times the previous byte repeats */
1739: run = 0;
1740: if (s->strstart > 0) { /* if there is a previous byte, that is */
1741: max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH;
1742: scan = s->window + s->strstart - 1;
1743: prev = *scan++;
1744: do {
1745: if (*scan++ != prev)
1746: break;
1747: } while (++run < max);
1748: }
1749:
1750: /* Emit match if have run of MIN_MATCH or longer, else emit literal */
1751: if (run >= MIN_MATCH) {
1752: check_match(s, s->strstart, s->strstart - 1, run);
1753: _tr_tally_dist(s, 1, run - MIN_MATCH, bflush);
1754: s->lookahead -= run;
1755: s->strstart += run;
1756: } else {
1757: /* No match, output a literal byte */
1758: Tracevv((stderr,"%c", s->window[s->strstart]));
1759: _tr_tally_lit (s, s->window[s->strstart], bflush);
1760: s->lookahead--;
1761: s->strstart++;
1762: }
1763: if (bflush) FLUSH_BLOCK(s, 0);
1764: }
1765: FLUSH_BLOCK(s, flush == Z_FINISH);
1766: return flush == Z_FINISH ? finish_done : block_done;
1767: }
1768: #endif
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