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tif_lzw.c
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1 /* $Id: tif_lzw.c,v 1.29.2.6 2010-06-08 18:50:42 bfriesen Exp $ */
2
3 /*
4 * Copyright (c) 1988-1997 Sam Leffler
5 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
6 *
7 * Permission to use, copy, modify, distribute, and sell this software and
8 * its documentation for any purpose is hereby granted without fee, provided
9 * that (i) the above copyright notices and this permission notice appear in
10 * all copies of the software and related documentation, and (ii) the names of
11 * Sam Leffler and Silicon Graphics may not be used in any advertising or
12 * publicity relating to the software without the specific, prior written
13 * permission of Sam Leffler and Silicon Graphics.
14 *
15 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
17 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
18 *
19 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
20 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
21 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
22 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
23 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
24 * OF THIS SOFTWARE.
25 */
26
27 #include "tiffiop.h"
28 #ifdef LZW_SUPPORT
29 /*
30 * TIFF Library.
31 * Rev 5.0 Lempel-Ziv & Welch Compression Support
32 *
33 * This code is derived from the compress program whose code is
34 * derived from software contributed to Berkeley by James A. Woods,
35 * derived from original work by Spencer Thomas and Joseph Orost.
36 *
37 * The original Berkeley copyright notice appears below in its entirety.
38 */
39 #include "tif_predict.h"
40
41 #include <stdio.h>
42
43 /*
44 * NB: The 5.0 spec describes a different algorithm than Aldus
45 * implements. Specifically, Aldus does code length transitions
46 * one code earlier than should be done (for real LZW).
47 * Earlier versions of this library implemented the correct
48 * LZW algorithm, but emitted codes in a bit order opposite
49 * to the TIFF spec. Thus, to maintain compatibility w/ Aldus
50 * we interpret MSB-LSB ordered codes to be images written w/
51 * old versions of this library, but otherwise adhere to the
52 * Aldus "off by one" algorithm.
53 *
54 * Future revisions to the TIFF spec are expected to "clarify this issue".
55 */
56 #define LZW_COMPAT /* include backwards compatibility code */
57 /*
58 * Each strip of data is supposed to be terminated by a CODE_EOI.
59 * If the following #define is included, the decoder will also
60 * check for end-of-strip w/o seeing this code. This makes the
61 * library more robust, but also slower.
62 */
63 #define LZW_CHECKEOS /* include checks for strips w/o EOI code */
64
65 #define MAXCODE(n) ((1L<<(n))-1)
66 /*
67 * The TIFF spec specifies that encoded bit
68 * strings range from 9 to 12 bits.
69 */
70 #define BITS_MIN 9 /* start with 9 bits */
71 #define BITS_MAX 12 /* max of 12 bit strings */
72 /* predefined codes */
73 #define CODE_CLEAR 256 /* code to clear string table */
74 #define CODE_EOI 257 /* end-of-information code */
75 #define CODE_FIRST 258 /* first free code entry */
76 #define CODE_MAX MAXCODE(BITS_MAX)
77 #define HSIZE 9001L /* 91% occupancy */
78 #define HSHIFT (13-8)
79 #ifdef LZW_COMPAT
80 /* NB: +1024 is for compatibility with old files */
81 #define CSIZE (MAXCODE(BITS_MAX)+1024L)
82 #else
83 #define CSIZE (MAXCODE(BITS_MAX)+1L)
84 #endif
85
86 /*
87 * State block for each open TIFF file using LZW
88 * compression/decompression. Note that the predictor
89 * state block must be first in this data structure.
90 */
91 typedef struct {
92 TIFFPredictorState predict; /* predictor super class */
93
94 unsigned short nbits; /* # of bits/code */
95 unsigned short maxcode; /* maximum code for lzw_nbits */
96 unsigned short free_ent; /* next free entry in hash table */
97 long nextdata; /* next bits of i/o */
98 long nextbits; /* # of valid bits in lzw_nextdata */
99
100 int rw_mode; /* preserve rw_mode from init */
101 } LZWBaseState;
102
103 #define lzw_nbits base.nbits
104 #define lzw_maxcode base.maxcode
105 #define lzw_free_ent base.free_ent
106 #define lzw_nextdata base.nextdata
107 #define lzw_nextbits base.nextbits
108
109 /*
110 * Encoding-specific state.
111 */
112 typedef uint16 hcode_t; /* codes fit in 16 bits */
113 typedef struct {
114 long hash;
115 hcode_t code;
116 } hash_t;
117
118 /*
119 * Decoding-specific state.
120 */
121 typedef struct code_ent {
122 struct code_ent *next;
123 unsigned short length; /* string len, including this token */
124 unsigned char value; /* data value */
125 unsigned char firstchar; /* first token of string */
126 } code_t;
127
128 typedef int (*decodeFunc)(TIFF*, tidata_t, tsize_t, tsample_t);
129
130 typedef struct {
131 LZWBaseState base;
132
133 /* Decoding specific data */
134 long dec_nbitsmask; /* lzw_nbits 1 bits, right adjusted */
135 long dec_restart; /* restart count */
136 #ifdef LZW_CHECKEOS
137 long dec_bitsleft; /* available bits in raw data */
138 #endif
139 decodeFunc dec_decode; /* regular or backwards compatible */
140 code_t* dec_codep; /* current recognized code */
141 code_t* dec_oldcodep; /* previously recognized code */
142 code_t* dec_free_entp; /* next free entry */
143 code_t* dec_maxcodep; /* max available entry */
144 code_t* dec_codetab; /* kept separate for small machines */
145
146 /* Encoding specific data */
147 int enc_oldcode; /* last code encountered */
148 long enc_checkpoint; /* point at which to clear table */
149 #define CHECK_GAP 10000 /* enc_ratio check interval */
150 long enc_ratio; /* current compression ratio */
151 long enc_incount; /* (input) data bytes encoded */
152 long enc_outcount; /* encoded (output) bytes */
153 tidata_t enc_rawlimit; /* bound on tif_rawdata buffer */
154 hash_t* enc_hashtab; /* kept separate for small machines */
155 } LZWCodecState;
156
157 #define LZWState(tif) ((LZWBaseState*) (tif)->tif_data)
158 #define DecoderState(tif) ((LZWCodecState*) LZWState(tif))
159 #define EncoderState(tif) ((LZWCodecState*) LZWState(tif))
160
161 static int LZWDecode(TIFF*, tidata_t, tsize_t, tsample_t);
162 #ifdef LZW_COMPAT
163 static int LZWDecodeCompat(TIFF*, tidata_t, tsize_t, tsample_t);
164 #endif
165 static void cl_hash(LZWCodecState*);
166
167 /*
168 * LZW Decoder.
169 */
170
171 #ifdef LZW_CHECKEOS
172 /*
173 * This check shouldn't be necessary because each
174 * strip is suppose to be terminated with CODE_EOI.
175 */
176 #define NextCode(_tif, _sp, _bp, _code, _get) { \
177 if ((_sp)->dec_bitsleft < nbits) { \
178 TIFFWarningExt(_tif->tif_clientdata, _tif->tif_name, \
179 "LZWDecode: Strip %d not terminated with EOI code", \
180 _tif->tif_curstrip); \
181 _code = CODE_EOI; \
182 } else { \
183 _get(_sp,_bp,_code); \
184 (_sp)->dec_bitsleft -= nbits; \
185 } \
186 }
187 #else
188 #define NextCode(tif, sp, bp, code, get) get(sp, bp, code)
189 #endif
190
191 static int
192 LZWSetupDecode(TIFF* tif)
193 {
194 LZWCodecState* sp = DecoderState(tif);
195 static const char module[] = " LZWSetupDecode";
196 int code;
197
198 if( sp == NULL )
199 {
200 /*
201 * Allocate state block so tag methods have storage to record
202 * values.
203 */
204 tif->tif_data = (tidata_t) _TIFFmalloc(sizeof(LZWCodecState));
205 if (tif->tif_data == NULL)
206 {
207 TIFFErrorExt(tif->tif_clientdata, "LZWPreDecode", "No space for LZW state block");
208 return (0);
209 }
210
211 DecoderState(tif)->dec_codetab = NULL;
212 DecoderState(tif)->dec_decode = NULL;
213
214 /*
215 * Setup predictor setup.
216 */
217 (void) TIFFPredictorInit(tif);
218
219 sp = DecoderState(tif);
220 }
221
222 assert(sp != NULL);
223
224 if (sp->dec_codetab == NULL) {
225 sp->dec_codetab = (code_t*)_TIFFmalloc(CSIZE*sizeof (code_t));
226 if (sp->dec_codetab == NULL) {
227 TIFFErrorExt(tif->tif_clientdata, module,
228 "No space for LZW code table");
229 return (0);
230 }
231 /*
232 * Pre-load the table.
233 */
234 code = 255;
235 do {
236 sp->dec_codetab[code].value = code;
237 sp->dec_codetab[code].firstchar = code;
238 sp->dec_codetab[code].length = 1;
239 sp->dec_codetab[code].next = NULL;
240 } while (code--);
241 /*
242 * Zero-out the unused entries
243 */
244 _TIFFmemset(&sp->dec_codetab[CODE_CLEAR], 0,
245 (CODE_FIRST - CODE_CLEAR) * sizeof (code_t));
246 }
247 return (1);
248 }
249
250 /*
251 * Setup state for decoding a strip.
252 */
253 static int
254 LZWPreDecode(TIFF* tif, tsample_t s)
255 {
256 LZWCodecState *sp = DecoderState(tif);
257
258 (void) s;
259 assert(sp != NULL);
260 if( sp->dec_codetab == NULL )
261 {
262 tif->tif_setupdecode( tif );
263 }
264
265 /*
266 * Check for old bit-reversed codes.
267 */
268 if (tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) {
269 #ifdef LZW_COMPAT
270 if (!sp->dec_decode) {
271 TIFFWarningExt(tif->tif_clientdata, tif->tif_name,
272 "Old-style LZW codes, convert file");
273 /*
274 * Override default decoding methods with
275 * ones that deal with the old coding.
276 * Otherwise the predictor versions set
277 * above will call the compatibility routines
278 * through the dec_decode method.
279 */
280 tif->tif_decoderow = LZWDecodeCompat;
281 tif->tif_decodestrip = LZWDecodeCompat;
282 tif->tif_decodetile = LZWDecodeCompat;
283 /*
284 * If doing horizontal differencing, must
285 * re-setup the predictor logic since we
286 * switched the basic decoder methods...
287 */
288 (*tif->tif_setupdecode)(tif);
289 sp->dec_decode = LZWDecodeCompat;
290 }
291 sp->lzw_maxcode = MAXCODE(BITS_MIN);
292 #else /* !LZW_COMPAT */
293 if (!sp->dec_decode) {
294 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
295 "Old-style LZW codes not supported");
296 sp->dec_decode = LZWDecode;
297 }
298 return (0);
299 #endif/* !LZW_COMPAT */
300 } else {
301 sp->lzw_maxcode = MAXCODE(BITS_MIN)-1;
302 sp->dec_decode = LZWDecode;
303 }
304 sp->lzw_nbits = BITS_MIN;
305 sp->lzw_nextbits = 0;
306 sp->lzw_nextdata = 0;
307
308 sp->dec_restart = 0;
309 sp->dec_nbitsmask = MAXCODE(BITS_MIN);
310 #ifdef LZW_CHECKEOS
311 sp->dec_bitsleft = tif->tif_rawcc << 3;
312 #endif
313 sp->dec_free_entp = sp->dec_codetab + CODE_FIRST;
314 /*
315 * Zero entries that are not yet filled in. We do
316 * this to guard against bogus input data that causes
317 * us to index into undefined entries. If you can
318 * come up with a way to safely bounds-check input codes
319 * while decoding then you can remove this operation.
320 */
321 _TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t));
322 sp->dec_oldcodep = &sp->dec_codetab[-1];
323 sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1];
324 return (1);
325 }
326
327 /*
328 * Decode a "hunk of data".
329 */
330 #define GetNextCode(sp, bp, code) { \
331 nextdata = (nextdata<<8) | *(bp)++; \
332 nextbits += 8; \
333 if (nextbits < nbits) { \
334 nextdata = (nextdata<<8) | *(bp)++; \
335 nextbits += 8; \
336 } \
337 code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask); \
338 nextbits -= nbits; \
339 }
340
341 static void
342 codeLoop(TIFF* tif)
343 {
344 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
345 "LZWDecode: Bogus encoding, loop in the code table; scanline %d",
346 tif->tif_row);
347 }
348
349 static int
350 LZWDecode(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
351 {
352 LZWCodecState *sp = DecoderState(tif);
353 char *op = (char*) op0;
354 long occ = (long) occ0;
355 char *tp;
356 unsigned char *bp;
357 hcode_t code;
358 int len;
359 long nbits, nextbits, nextdata, nbitsmask;
360 code_t *codep, *free_entp, *maxcodep, *oldcodep;
361
362 (void) s;
363 assert(sp != NULL);
364 assert(sp->dec_codetab != NULL);
365 /*
366 * Restart interrupted output operation.
367 */
368 if (sp->dec_restart) {
369 long residue;
370
371 codep = sp->dec_codep;
372 residue = codep->length - sp->dec_restart;
373 if (residue > occ) {
374 /*
375 * Residue from previous decode is sufficient
376 * to satisfy decode request. Skip to the
377 * start of the decoded string, place decoded
378 * values in the output buffer, and return.
379 */
380 sp->dec_restart += occ;
381 do {
382 codep = codep->next;
383 } while (--residue > occ && codep);
384 if (codep) {
385 tp = op + occ;
386 do {
387 *--tp = codep->value;
388 codep = codep->next;
389 } while (--occ && codep);
390 }
391 return (1);
392 }
393 /*
394 * Residue satisfies only part of the decode request.
395 */
396 op += residue, occ -= residue;
397 tp = op;
398 do {
399 int t;
400 --tp;
401 t = codep->value;
402 codep = codep->next;
403 *tp = t;
404 } while (--residue && codep);
405 sp->dec_restart = 0;
406 }
407
408 bp = (unsigned char *)tif->tif_rawcp;
409 nbits = sp->lzw_nbits;
410 nextdata = sp->lzw_nextdata;
411 nextbits = sp->lzw_nextbits;
412 nbitsmask = sp->dec_nbitsmask;
413 oldcodep = sp->dec_oldcodep;
414 free_entp = sp->dec_free_entp;
415 maxcodep = sp->dec_maxcodep;
416
417 while (occ > 0) {
418 NextCode(tif, sp, bp, code, GetNextCode);
419 if (code == CODE_EOI)
420 break;
421 if (code == CODE_CLEAR) {
422 free_entp = sp->dec_codetab + CODE_FIRST;
423 _TIFFmemset(free_entp, 0,
424 (CSIZE - CODE_FIRST) * sizeof (code_t));
425 nbits = BITS_MIN;
426 nbitsmask = MAXCODE(BITS_MIN);
427 maxcodep = sp->dec_codetab + nbitsmask-1;
428 NextCode(tif, sp, bp, code, GetNextCode);
429 if (code == CODE_EOI)
430 break;
431 if (code == CODE_CLEAR) {
432 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
433 "LZWDecode: Corrupted LZW table at scanline %d",
434 tif->tif_row);
435 return (0);
436 }
437 *op++ = (char)code, occ--;
438 oldcodep = sp->dec_codetab + code;
439 continue;
440 }
441 codep = sp->dec_codetab + code;
442
443 /*
444 * Add the new entry to the code table.
445 */
446 if (free_entp < &sp->dec_codetab[0] ||
447 free_entp >= &sp->dec_codetab[CSIZE]) {
448 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
449 "LZWDecode: Corrupted LZW table at scanline %d",
450 tif->tif_row);
451 return (0);
452 }
453
454 free_entp->next = oldcodep;
455 if (free_entp->next < &sp->dec_codetab[0] ||
456 free_entp->next >= &sp->dec_codetab[CSIZE]) {
457 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
458 "LZWDecode: Corrupted LZW table at scanline %d",
459 tif->tif_row);
460 return (0);
461 }
462 free_entp->firstchar = free_entp->next->firstchar;
463 free_entp->length = free_entp->next->length+1;
464 free_entp->value = (codep < free_entp) ?
465 codep->firstchar : free_entp->firstchar;
466 if (++free_entp > maxcodep) {
467 if (++nbits > BITS_MAX) /* should not happen */
468 nbits = BITS_MAX;
469 nbitsmask = MAXCODE(nbits);
470 maxcodep = sp->dec_codetab + nbitsmask-1;
471 }
472 oldcodep = codep;
473 if (code >= 256) {
474 /*
475 * Code maps to a string, copy string
476 * value to output (written in reverse).
477 */
478 if(codep->length == 0) {
479 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
480 "LZWDecode: Wrong length of decoded string: "
481 "data probably corrupted at scanline %d",
482 tif->tif_row);
483 return (0);
484 }
485 if (codep->length > occ) {
486 /*
487 * String is too long for decode buffer,
488 * locate portion that will fit, copy to
489 * the decode buffer, and setup restart
490 * logic for the next decoding call.
491 */
492 sp->dec_codep = codep;
493 do {
494 codep = codep->next;
495 } while (codep && codep->length > occ);
496 if (codep) {
497 sp->dec_restart = occ;
498 tp = op + occ;
499 do {
500 *--tp = codep->value;
501 codep = codep->next;
502 } while (--occ && codep);
503 if (codep)
504 codeLoop(tif);
505 }
506 break;
507 }
508 len = codep->length;
509 tp = op + len;
510 do {
511 int t;
512 --tp;
513 t = codep->value;
514 codep = codep->next;
515 *tp = t;
516 } while (codep && tp > op);
517 if (codep) {
518 codeLoop(tif);
519 break;
520 }
521 op += len, occ -= len;
522 } else
523 *op++ = (char)code, occ--;
524 }
525
526 tif->tif_rawcp = (tidata_t) bp;
527 sp->lzw_nbits = (unsigned short) nbits;
528 sp->lzw_nextdata = nextdata;
529 sp->lzw_nextbits = nextbits;
530 sp->dec_nbitsmask = nbitsmask;
531 sp->dec_oldcodep = oldcodep;
532 sp->dec_free_entp = free_entp;
533 sp->dec_maxcodep = maxcodep;
534
535 if (occ > 0) {
536 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
537 "LZWDecode: Not enough data at scanline %d (short %ld bytes)",
538 tif->tif_row, occ);
539 return (0);
540 }
541 return (1);
542 }
543
544 #ifdef LZW_COMPAT
545 /*
546 * Decode a "hunk of data" for old images.
547 */
548 #define GetNextCodeCompat(sp, bp, code) { \
549 nextdata |= (unsigned long) *(bp)++ << nextbits; \
550 nextbits += 8; \
551 if (nextbits < nbits) { \
552 nextdata |= (unsigned long) *(bp)++ << nextbits;\
553 nextbits += 8; \
554 } \
555 code = (hcode_t)(nextdata & nbitsmask); \
556 nextdata >>= nbits; \
557 nextbits -= nbits; \
558 }
559
560 static int
561 LZWDecodeCompat(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
562 {
563 LZWCodecState *sp = DecoderState(tif);
564 char *op = (char*) op0;
565 long occ = (long) occ0;
566 char *tp;
567 unsigned char *bp;
568 int code, nbits;
569 long nextbits, nextdata, nbitsmask;
570 code_t *codep, *free_entp, *maxcodep, *oldcodep;
571
572 (void) s;
573 assert(sp != NULL);
574 /*
575 * Restart interrupted output operation.
576 */
577 if (sp->dec_restart) {
578 long residue;
579
580 codep = sp->dec_codep;
581 residue = codep->length - sp->dec_restart;
582 if (residue > occ) {
583 /*
584 * Residue from previous decode is sufficient
585 * to satisfy decode request. Skip to the
586 * start of the decoded string, place decoded
587 * values in the output buffer, and return.
588 */
589 sp->dec_restart += occ;
590 do {
591 codep = codep->next;
592 } while (--residue > occ);
593 tp = op + occ;
594 do {
595 *--tp = codep->value;
596 codep = codep->next;
597 } while (--occ);
598 return (1);
599 }
600 /*
601 * Residue satisfies only part of the decode request.
602 */
603 op += residue, occ -= residue;
604 tp = op;
605 do {
606 *--tp = codep->value;
607 codep = codep->next;
608 } while (--residue);
609 sp->dec_restart = 0;
610 }
611
612 bp = (unsigned char *)tif->tif_rawcp;
613 nbits = sp->lzw_nbits;
614 nextdata = sp->lzw_nextdata;
615 nextbits = sp->lzw_nextbits;
616 nbitsmask = sp->dec_nbitsmask;
617 oldcodep = sp->dec_oldcodep;
618 free_entp = sp->dec_free_entp;
619 maxcodep = sp->dec_maxcodep;
620
621 while (occ > 0) {
622 NextCode(tif, sp, bp, code, GetNextCodeCompat);
623 if (code == CODE_EOI)
624 break;
625 if (code == CODE_CLEAR) {
626 free_entp = sp->dec_codetab + CODE_FIRST;
627 _TIFFmemset(free_entp, 0,
628 (CSIZE - CODE_FIRST) * sizeof (code_t));
629 nbits = BITS_MIN;
630 nbitsmask = MAXCODE(BITS_MIN);
631 maxcodep = sp->dec_codetab + nbitsmask;
632 NextCode(tif, sp, bp, code, GetNextCodeCompat);
633 if (code == CODE_EOI)
634 break;
635 if (code == CODE_CLEAR) {
636 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
637 "LZWDecode: Corrupted LZW table at scanline %d",
638 tif->tif_row);
639 return (0);
640 }
641 *op++ = code, occ--;
642 oldcodep = sp->dec_codetab + code;
643 continue;
644 }
645 codep = sp->dec_codetab + code;
646
647 /*
648 * Add the new entry to the code table.
649 */
650 if (free_entp < &sp->dec_codetab[0] ||
651 free_entp >= &sp->dec_codetab[CSIZE]) {
652 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
653 "LZWDecodeCompat: Corrupted LZW table at scanline %d",
654 tif->tif_row);
655 return (0);
656 }
657
658 free_entp->next = oldcodep;
659 if (free_entp->next < &sp->dec_codetab[0] ||
660 free_entp->next >= &sp->dec_codetab[CSIZE]) {
661 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
662 "LZWDecodeCompat: Corrupted LZW table at scanline %d",
663 tif->tif_row);
664 return (0);
665 }
666 free_entp->firstchar = free_entp->next->firstchar;
667 free_entp->length = free_entp->next->length+1;
668 free_entp->value = (codep < free_entp) ?
669 codep->firstchar : free_entp->firstchar;
670 if (++free_entp > maxcodep) {
671 if (++nbits > BITS_MAX) /* should not happen */
672 nbits = BITS_MAX;
673 nbitsmask = MAXCODE(nbits);
674 maxcodep = sp->dec_codetab + nbitsmask;
675 }
676 oldcodep = codep;
677 if (code >= 256) {
678 char *op_orig = op;
679 /*
680 * Code maps to a string, copy string
681 * value to output (written in reverse).
682 */
683 if(codep->length == 0) {
684 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
685 "LZWDecodeCompat: Wrong length of decoded "
686 "string: data probably corrupted at scanline %d",
687 tif->tif_row);
688 return (0);
689 }
690 if (codep->length > occ) {
691 /*
692 * String is too long for decode buffer,
693 * locate portion that will fit, copy to
694 * the decode buffer, and setup restart
695 * logic for the next decoding call.
696 */
697 sp->dec_codep = codep;
698 do {
699 codep = codep->next;
700 } while (codep->length > occ);
701 sp->dec_restart = occ;
702 tp = op + occ;
703 do {
704 *--tp = codep->value;
705 codep = codep->next;
706 } while (--occ);
707 break;
708 }
709 op += codep->length, occ -= codep->length;
710 tp = op;
711 do {
712 *--tp = codep->value;
713 } while( (codep = codep->next) != NULL && tp > op_orig);
714 } else
715 *op++ = code, occ--;
716 }
717
718 tif->tif_rawcp = (tidata_t) bp;
719 sp->lzw_nbits = nbits;
720 sp->lzw_nextdata = nextdata;
721 sp->lzw_nextbits = nextbits;
722 sp->dec_nbitsmask = nbitsmask;
723 sp->dec_oldcodep = oldcodep;
724 sp->dec_free_entp = free_entp;
725 sp->dec_maxcodep = maxcodep;
726
727 if (occ > 0) {
728 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
729 "LZWDecodeCompat: Not enough data at scanline %d (short %ld bytes)",
730 tif->tif_row, occ);
731 return (0);
732 }
733 return (1);
734 }
735 #endif /* LZW_COMPAT */
736
737 /*
738 * LZW Encoding.
739 */
740
741 static int
742 LZWSetupEncode(TIFF* tif)
743 {
744 LZWCodecState* sp = EncoderState(tif);
745 static const char module[] = "LZWSetupEncode";
746
747 assert(sp != NULL);
748 sp->enc_hashtab = (hash_t*) _TIFFmalloc(HSIZE*sizeof (hash_t));
749 if (sp->enc_hashtab == NULL) {
750 TIFFErrorExt(tif->tif_clientdata, module, "No space for LZW hash table");
751 return (0);
752 }
753 return (1);
754 }
755
756 /*
757 * Reset encoding state at the start of a strip.
758 */
759 static int
760 LZWPreEncode(TIFF* tif, tsample_t s)
761 {
762 LZWCodecState *sp = EncoderState(tif);
763
764 (void) s;
765 assert(sp != NULL);
766
767 if( sp->enc_hashtab == NULL )
768 {
769 tif->tif_setupencode( tif );
770 }
771
772 sp->lzw_nbits = BITS_MIN;
773 sp->lzw_maxcode = MAXCODE(BITS_MIN);
774 sp->lzw_free_ent = CODE_FIRST;
775 sp->lzw_nextbits = 0;
776 sp->lzw_nextdata = 0;
777 sp->enc_checkpoint = CHECK_GAP;
778 sp->enc_ratio = 0;
779 sp->enc_incount = 0;
780 sp->enc_outcount = 0;
781 /*
782 * The 4 here insures there is space for 2 max-sized
783 * codes in LZWEncode and LZWPostDecode.
784 */
785 sp->enc_rawlimit = tif->tif_rawdata + tif->tif_rawdatasize-1 - 4;
786 cl_hash(sp); /* clear hash table */
787 sp->enc_oldcode = (hcode_t) -1; /* generates CODE_CLEAR in LZWEncode */
788 return (1);
789 }
790
791 #define CALCRATIO(sp, rat) { \
792 if (incount > 0x007fffff) { /* NB: shift will overflow */\
793 rat = outcount >> 8; \
794 rat = (rat == 0 ? 0x7fffffff : incount/rat); \
795 } else \
796 rat = (incount<<8) / outcount; \
797 }
798 #define PutNextCode(op, c) { \
799 nextdata = (nextdata << nbits) | c; \
800 nextbits += nbits; \
801 *op++ = (unsigned char)(nextdata >> (nextbits-8)); \
802 nextbits -= 8; \
803 if (nextbits >= 8) { \
804 *op++ = (unsigned char)(nextdata >> (nextbits-8)); \
805 nextbits -= 8; \
806 } \
807 outcount += nbits; \
808 }
809
810 /*
811 * Encode a chunk of pixels.
812 *
813 * Uses an open addressing double hashing (no chaining) on the
814 * prefix code/next character combination. We do a variant of
815 * Knuth's algorithm D (vol. 3, sec. 6.4) along with G. Knott's
816 * relatively-prime secondary probe. Here, the modular division
817 * first probe is gives way to a faster exclusive-or manipulation.
818 * Also do block compression with an adaptive reset, whereby the
819 * code table is cleared when the compression ratio decreases,
820 * but after the table fills. The variable-length output codes
821 * are re-sized at this point, and a CODE_CLEAR is generated
822 * for the decoder.
823 */
824 static int
825 LZWEncode(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
826 {
827 register LZWCodecState *sp = EncoderState(tif);
828 register long fcode;
829 register hash_t *hp;
830 register int h, c;
831 hcode_t ent;
832 long disp;
833 long incount, outcount, checkpoint;
834 long nextdata, nextbits;
835 int free_ent, maxcode, nbits;
836 tidata_t op, limit;
837
838 (void) s;
839 if (sp == NULL)
840 return (0);
841
842 assert(sp->enc_hashtab != NULL);
843
844 /*
845 * Load local state.
846 */
847 incount = sp->enc_incount;
848 outcount = sp->enc_outcount;
849 checkpoint = sp->enc_checkpoint;
850 nextdata = sp->lzw_nextdata;
851 nextbits = sp->lzw_nextbits;
852 free_ent = sp->lzw_free_ent;
853 maxcode = sp->lzw_maxcode;
854 nbits = sp->lzw_nbits;
855 op = tif->tif_rawcp;
856 limit = sp->enc_rawlimit;
857 ent = sp->enc_oldcode;
858
859 if (ent == (hcode_t) -1 && cc > 0) {
860 /*
861 * NB: This is safe because it can only happen
862 * at the start of a strip where we know there
863 * is space in the data buffer.
864 */
865 PutNextCode(op, CODE_CLEAR);
866 ent = *bp++; cc--; incount++;
867 }
868 while (cc > 0) {
869 c = *bp++; cc--; incount++;
870 fcode = ((long)c << BITS_MAX) + ent;
871 h = (c << HSHIFT) ^ ent; /* xor hashing */
872 #ifdef _WINDOWS
873 /*
874 * Check hash index for an overflow.
875 */
876 if (h >= HSIZE)
877 h -= HSIZE;
878 #endif
879 hp = &sp->enc_hashtab[h];
880 if (hp->hash == fcode) {
881 ent = hp->code;
882 continue;
883 }
884 if (hp->hash >= 0) {
885 /*
886 * Primary hash failed, check secondary hash.
887 */
888 disp = HSIZE - h;
889 if (h == 0)
890 disp = 1;
891 do {
892 /*
893 * Avoid pointer arithmetic 'cuz of
894 * wraparound problems with segments.
895 */
896 if ((h -= disp) < 0)
897 h += HSIZE;
898 hp = &sp->enc_hashtab[h];
899 if (hp->hash == fcode) {
900 ent = hp->code;
901 goto hit;
902 }
903 } while (hp->hash >= 0);
904 }
905 /*
906 * New entry, emit code and add to table.
907 */
908 /*
909 * Verify there is space in the buffer for the code
910 * and any potential Clear code that might be emitted
911 * below. The value of limit is setup so that there
912 * are at least 4 bytes free--room for 2 codes.
913 */
914 if (op > limit) {
915 tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
916 TIFFFlushData1(tif);
917 op = tif->tif_rawdata;
918 }
919 PutNextCode(op, ent);
920 ent = c;
921 hp->code = free_ent++;
922 hp->hash = fcode;
923 if (free_ent == CODE_MAX-1) {
924 /* table is full, emit clear code and reset */
925 cl_hash(sp);
926 sp->enc_ratio = 0;
927 incount = 0;
928 outcount = 0;
929 free_ent = CODE_FIRST;
930 PutNextCode(op, CODE_CLEAR);
931 nbits = BITS_MIN;
932 maxcode = MAXCODE(BITS_MIN);
933 } else {
934 /*
935 * If the next entry is going to be too big for
936 * the code size, then increase it, if possible.
937 */
938 if (free_ent > maxcode) {
939 nbits++;
940 assert(nbits <= BITS_MAX);
941 maxcode = (int) MAXCODE(nbits);
942 } else if (incount >= checkpoint) {
943 long rat;
944 /*
945 * Check compression ratio and, if things seem
946 * to be slipping, clear the hash table and
947 * reset state. The compression ratio is a
948 * 24+8-bit fractional number.
949 */
950 checkpoint = incount+CHECK_GAP;
951 CALCRATIO(sp, rat);
952 if (rat <= sp->enc_ratio) {
953 cl_hash(sp);
954 sp->enc_ratio = 0;
955 incount = 0;
956 outcount = 0;
957 free_ent = CODE_FIRST;
958 PutNextCode(op, CODE_CLEAR);
959 nbits = BITS_MIN;
960 maxcode = MAXCODE(BITS_MIN);
961 } else
962 sp->enc_ratio = rat;
963 }
964 }
965 hit:
966 ;
967 }
968
969 /*
970 * Restore global state.
971 */
972 sp->enc_incount = incount;
973 sp->enc_outcount = outcount;
974 sp->enc_checkpoint = checkpoint;
975 sp->enc_oldcode = ent;
976 sp->lzw_nextdata = nextdata;
977 sp->lzw_nextbits = nextbits;
978 sp->lzw_free_ent = free_ent;
979 sp->lzw_maxcode = maxcode;
980 sp->lzw_nbits = nbits;
981 tif->tif_rawcp = op;
982 return (1);
983 }
984
985 /*
986 * Finish off an encoded strip by flushing the last
987 * string and tacking on an End Of Information code.
988 */
989 static int
990 LZWPostEncode(TIFF* tif)
991 {
992 register LZWCodecState *sp = EncoderState(tif);
993 tidata_t op = tif->tif_rawcp;
994 long nextbits = sp->lzw_nextbits;
995 long nextdata = sp->lzw_nextdata;
996 long outcount = sp->enc_outcount;
997 int nbits = sp->lzw_nbits;
998
999 if (op > sp->enc_rawlimit) {
1000 tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
1001 TIFFFlushData1(tif);
1002 op = tif->tif_rawdata;
1003 }
1004 if (sp->enc_oldcode != (hcode_t) -1) {
1005 PutNextCode(op, sp->enc_oldcode);
1006 sp->enc_oldcode = (hcode_t) -1;
1007 }
1008 PutNextCode(op, CODE_EOI);
1009 if (nextbits > 0)
1010 *op++ = (unsigned char)(nextdata << (8-nextbits));
1011 tif->tif_rawcc = (tsize_t)(op - tif->tif_rawdata);
1012 return (1);
1013 }
1014
1015 /*
1016 * Reset encoding hash table.
1017 */
1018 static void
1019 cl_hash(LZWCodecState* sp)
1020 {
1021 register hash_t *hp = &sp->enc_hashtab[HSIZE-1];
1022 register long i = HSIZE-8;
1023
1024 do {
1025 i -= 8;
1026 hp[-7].hash = -1;
1027 hp[-6].hash = -1;
1028 hp[-5].hash = -1;
1029 hp[-4].hash = -1;
1030 hp[-3].hash = -1;
1031 hp[-2].hash = -1;
1032 hp[-1].hash = -1;
1033 hp[ 0].hash = -1;
1034 hp -= 8;
1035 } while (i >= 0);
1036 for (i += 8; i > 0; i--, hp--)
1037 hp->hash = -1;
1038 }
1039
1040 static void
1041 LZWCleanup(TIFF* tif)
1042 {
1043 (void)TIFFPredictorCleanup(tif);
1044
1045 assert(tif->tif_data != 0);
1046
1047 if (DecoderState(tif)->dec_codetab)
1048 _TIFFfree(DecoderState(tif)->dec_codetab);
1049
1050 if (EncoderState(tif)->enc_hashtab)
1051 _TIFFfree(EncoderState(tif)->enc_hashtab);
1052
1053 _TIFFfree(tif->tif_data);
1054 tif->tif_data = NULL;
1055
1056 _TIFFSetDefaultCompressionState(tif);
1057 }
1058
1059 int
1060 TIFFInitLZW(TIFF* tif, int scheme)
1061 {
1062 assert(scheme == COMPRESSION_LZW);
1063 /*
1064 * Allocate state block so tag methods have storage to record values.
1065 */
1066 tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (LZWCodecState));
1067 if (tif->tif_data == NULL)
1068 goto bad;
1069 DecoderState(tif)->dec_codetab = NULL;
1070 DecoderState(tif)->dec_decode = NULL;
1071 EncoderState(tif)->enc_hashtab = NULL;
1072 LZWState(tif)->rw_mode = tif->tif_mode;
1073
1074 /*
1075 * Install codec methods.
1076 */
1077 tif->tif_setupdecode = LZWSetupDecode;
1078 tif->tif_predecode = LZWPreDecode;
1079 tif->tif_decoderow = LZWDecode;
1080 tif->tif_decodestrip = LZWDecode;
1081 tif->tif_decodetile = LZWDecode;
1082 tif->tif_setupencode = LZWSetupEncode;
1083 tif->tif_preencode = LZWPreEncode;
1084 tif->tif_postencode = LZWPostEncode;
1085 tif->tif_encoderow = LZWEncode;
1086 tif->tif_encodestrip = LZWEncode;
1087 tif->tif_encodetile = LZWEncode;
1088 tif->tif_cleanup = LZWCleanup;
1089 /*
1090 * Setup predictor setup.
1091 */
1092 (void) TIFFPredictorInit(tif);
1093 return (1);
1094 bad:
1095 TIFFErrorExt(tif->tif_clientdata, "TIFFInitLZW",
1096 "No space for LZW state block");
1097 return (0);
1098 }
1099
1100 /*
1101 * Copyright (c) 1985, 1986 The Regents of the University of California.
1102 * All rights reserved.
1103 *
1104 * This code is derived from software contributed to Berkeley by
1105 * James A. Woods, derived from original work by Spencer Thomas
1106 * and Joseph Orost.
1107 *
1108 * Redistribution and use in source and binary forms are permitted
1109 * provided that the above copyright notice and this paragraph are
1110 * duplicated in all such forms and that any documentation,
1111 * advertising materials, and other materials related to such
1112 * distribution and use acknowledge that the software was developed
1113 * by the University of California, Berkeley. The name of the
1114 * University may not be used to endorse or promote products derived
1115 * from this software without specific prior written permission.
1116 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
1117 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
1118 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
1119 */
1120 #endif /* LZW_SUPPORT */
1121
1122 /* vim: set ts=8 sts=8 sw=8 noet: */
1123 /*
1124 * Local Variables:
1125 * mode: c
1126 * c-basic-offset: 8
1127 * fill-column: 78
1128 * End:
1129 */
LZWBaseState::free_ent
unsigned short free_ent
Definition: tif_lzw.c:96
tsize_t
int32 tsize_t
Definition: tiffio.h:67
tsample_t
uint16 tsample_t
Definition: tiffio.h:63
tiff::tif_decoderow
TIFFCodeMethod tif_decoderow
Definition: tiffiop.h:159
hash_t::code
hcode_t code
Definition: tif_lzw.c:115
tiff::tif_predecode
TIFFPreMethod tif_predecode
Definition: tiffiop.h:154
TIFFWarningExt
void TIFFWarningExt(thandle_t fd, const char *module, const char *fmt,...)
Definition: tif_warning.c:63
TIFFPredictorState
Definition: tif_predict.h:38
NextCode
#define NextCode(_tif, _sp, _bp, _code, _get)
Definition: tif_lzw.c:176
DecoderState
#define DecoderState(tif)
Definition: tif_lzw.c:158
LZWCodecState::dec_bitsleft
long dec_bitsleft
Definition: tif_lzw.c:137
tiff::tif_encodestrip
TIFFCodeMethod tif_encodestrip
Definition: tiffiop.h:162
BITS_MIN
#define BITS_MIN
Definition: tif_lzw.c:70
LZWCodecState::enc_checkpoint
long enc_checkpoint
Definition: tif_lzw.c:148
code_ent::firstchar
unsigned char firstchar
Definition: tif_lzw.c:125
tiff::tif_encoderow
TIFFCodeMethod tif_encoderow
Definition: tiffiop.h:160
tiff::tif_rawdata
tidata_t tif_rawdata
Definition: tiffiop.h:174
LZWCodecState::dec_free_entp
code_t * dec_free_entp
Definition: tif_lzw.c:142
tiff::tif_clientdata
thandle_t tif_clientdata
Definition: tiffiop.h:185
CODE_EOI
#define CODE_EOI
Definition: tif_lzw.c:74
LZWCodecState::enc_rawlimit
tidata_t enc_rawlimit
Definition: tif_lzw.c:153
tiffiop.h
TIFFPredictorCleanup
int TIFFPredictorCleanup(TIFF *tif)
Definition: tif_predict.c:714
tiff::tif_name
char * tif_name
Definition: tiffiop.h:103
tiff
Definition: tiffiop.h:102
LZWCodecState::dec_codetab
code_t * dec_codetab
Definition: tif_lzw.c:144
code_ent::value
unsigned char value
Definition: tif_lzw.c:124
decodeFunc
int(* decodeFunc)(TIFF *, tidata_t, tsize_t, tsample_t)
Definition: tif_lzw.c:128
LZWCodecState::enc_outcount
long enc_outcount
Definition: tif_lzw.c:152
code_t
struct code_ent code_t
tif_predict.h
CALCRATIO
#define CALCRATIO(sp, rat)
Definition: tif_lzw.c:791
CSIZE
#define CSIZE
Definition: tif_lzw.c:81
tiff::tif_rawcp
tidata_t tif_rawcp
Definition: tiffiop.h:176
tiff::tif_mode
int tif_mode
Definition: tiffiop.h:105
tiff::tif_decodestrip
TIFFCodeMethod tif_decodestrip
Definition: tiffiop.h:161
HSIZE
#define HSIZE
Definition: tif_lzw.c:77
LZWBaseState::nbits
unsigned short nbits
Definition: tif_lzw.c:94
GetNextCodeCompat
#define GetNextCodeCompat(sp, bp, code)
Definition: tif_lzw.c:548
tiff::tif_encodetile
TIFFCodeMethod tif_encodetile
Definition: tiffiop.h:164
LZWCodecState::dec_decode
decodeFunc dec_decode
Definition: tif_lzw.c:139
hcode_t
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Definition: tif_lzw.c:112
LZWBaseState
Definition: tif_lzw.c:91
LZWBaseState::maxcode
unsigned short maxcode
Definition: tif_lzw.c:95
PutNextCode
#define PutNextCode(op, c)
Definition: tif_lzw.c:798
LZWBaseState::nextbits
long nextbits
Definition: tif_lzw.c:98
CODE_CLEAR
#define CODE_CLEAR
Definition: tif_lzw.c:73
tiff::tif_preencode
TIFFPreMethod tif_preencode
Definition: tiffiop.h:157
TIFFInitLZW
int TIFFInitLZW(TIFF *tif, int scheme)
Definition: tif_lzw.c:1060
uint16
unsigned short uint16
Definition: tiff.h:71
hash_t::hash
long hash
Definition: tif_lzw.c:114
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int rw_mode
Definition: tif_lzw.c:100
tiff::tif_postencode
TIFFBoolMethod tif_postencode
Definition: tiffiop.h:158
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TIFFPredictorState predict
Definition: tif_lzw.c:92
MAXCODE
#define MAXCODE(n)
Definition: tif_lzw.c:65
nbits
register bit_buf_type register int int nbits
Definition: jdhuff.h:155
CODE_MAX
#define CODE_MAX
Definition: tif_lzw.c:76
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long enc_ratio
Definition: tif_lzw.c:150
TIFFErrorExt
void TIFFErrorExt(thandle_t fd, const char *module, const char *fmt,...)
Definition: tif_error.c:63
tiff::tif_rawdatasize
tsize_t tif_rawdatasize
Definition: tiffiop.h:175
tiff::tif_rawcc
tsize_t tif_rawcc
Definition: tiffiop.h:177
code_ent
Definition: tif_lzw.c:121
tiff::tif_decodetile
TIFFCodeMethod tif_decodetile
Definition: tiffiop.h:163
LZWCodecState::enc_incount
long enc_incount
Definition: tif_lzw.c:151
code_ent::next
struct code_ent * next
Definition: tif_lzw.c:122
EncoderState
#define EncoderState(tif)
Definition: tif_lzw.c:159
tiff::tif_cleanup
TIFFVoidMethod tif_cleanup
Definition: tiffiop.h:167
LZWBaseState::nextdata
long nextdata
Definition: tif_lzw.c:97
_TIFFmemset
void _TIFFmemset(tdata_t p, int v, tsize_t c)
Definition: tif_acorn.c:479
_TIFFSetDefaultCompressionState
void _TIFFSetDefaultCompressionState(TIFF *tif)
Definition: tif_compress.c:129
code
Definition: inftrees.h:24
HSHIFT
#define HSHIFT
Definition: tif_lzw.c:78
LZWCodecState::dec_oldcodep
code_t * dec_oldcodep
Definition: tif_lzw.c:141
tidata_t
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Definition: tiffiop.h:91
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Definition: tif_lzw.c:123
CHECK_GAP
#define CHECK_GAP
Definition: tif_lzw.c:149
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Definition: tif_lzw.c:131
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#define GetNextCode(sp, bp, code)
Definition: tif_lzw.c:330
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Definition: tif_predict.c:673
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Definition: tiffiop.h:139
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#define LZWState(tif)
Definition: tif_lzw.c:157
BITS_MAX
#define BITS_MAX
Definition: tif_lzw.c:71
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Definition: tif_lzw.c:130
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Definition: tif_lzw.c:113
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Definition: tif_acorn.c:461
LZWCodecState::dec_restart
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Definition: tif_lzw.c:135
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Definition: tif_lzw.c:154
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Definition: tif_lzw.c:134
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_TIFFfree
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LZWCodecState::dec_maxcodep
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Definition: tif_lzw.c:143
COMPRESSION_LZW
#define COMPRESSION_LZW
Definition: tiff.h:175
tiff::tif_setupencode
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Definition: tiffiop.h:155
tiff::tif_data
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Definition: tiffiop.h:170
CODE_FIRST
#define CODE_FIRST
Definition: tif_lzw.c:75
TIFFFlushData1
int TIFFFlushData1(TIFF *tif)
Definition: tif_write.c:682
LZWCodecState::dec_codep
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Definition: tif_lzw.c:140
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Definition: tiffiop.h:153