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1/* $Id: tif_lzw.c,v 1.45 2011-04-02 20:54:09 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 */
91typedef 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 */
112typedef uint16 hcode_t; /* codes fit in 16 bits */
113typedef struct {
114 long hash;
115 hcode_t code;
116} hash_t;
117
118/*
119 * Decoding-specific state.
120 */
121typedef 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
128typedef int (*decodeFunc)(TIFF*, uint8*, tmsize_t, uint16);
129
130typedef 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 uint64 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 uint8* 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
161static int LZWDecode(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s);
162#ifdef LZW_COMPAT
163static int LZWDecodeCompat(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s);
164#endif
165static 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 < (uint64)nbits) { \
178 TIFFWarningExt(_tif->tif_clientdata, module, \
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
191static int
192LZWFixupTags(TIFF* tif)
193{
194 (void) tif;
195 return (1);
196}
197
198static int
199LZWSetupDecode(TIFF* tif)
200{
201 static const char module[] = "LZWSetupDecode";
202 LZWCodecState* sp = DecoderState(tif);
203 int code;
204
205 if( sp == NULL )
206 {
207 /*
208 * Allocate state block so tag methods have storage to record
209 * values.
210 */
211 tif->tif_data = (uint8*) _TIFFmalloc(sizeof(LZWCodecState));
212 if (tif->tif_data == NULL)
213 {
214 TIFFErrorExt(tif->tif_clientdata, module, "No space for LZW state block");
215 return (0);
216 }
217
218 DecoderState(tif)->dec_codetab = NULL;
219 DecoderState(tif)->dec_decode = NULL;
220
221 /*
222 * Setup predictor setup.
223 */
224 (void) TIFFPredictorInit(tif);
225
226 sp = DecoderState(tif);
227 }
228
229 assert(sp != NULL);
230
231 if (sp->dec_codetab == NULL) {
232 sp->dec_codetab = (code_t*)_TIFFmalloc(CSIZE*sizeof (code_t));
233 if (sp->dec_codetab == NULL) {
234 TIFFErrorExt(tif->tif_clientdata, module,
235 "No space for LZW code table");
236 return (0);
237 }
238 /*
239 * Pre-load the table.
240 */
241 code = 255;
242 do {
243 sp->dec_codetab[code].value = code;
244 sp->dec_codetab[code].firstchar = code;
245 sp->dec_codetab[code].length = 1;
246 sp->dec_codetab[code].next = NULL;
247 } while (code--);
248 /*
249 * Zero-out the unused entries
250 */
251 _TIFFmemset(&sp->dec_codetab[CODE_CLEAR], 0,
252 (CODE_FIRST - CODE_CLEAR) * sizeof (code_t));
253 }
254 return (1);
255}
256
257/*
258 * Setup state for decoding a strip.
259 */
260static int
261LZWPreDecode(TIFF* tif, uint16 s)
262{
263 static const char module[] = "LZWPreDecode";
264 LZWCodecState *sp = DecoderState(tif);
265
266 (void) s;
267 assert(sp != NULL);
268 if( sp->dec_codetab == NULL )
269 {
270 tif->tif_setupdecode( tif );
271 }
272
273 /*
274 * Check for old bit-reversed codes.
275 */
276 if (tif->tif_rawdata[0] == 0 && (tif->tif_rawdata[1] & 0x1)) {
277#ifdef LZW_COMPAT
278 if (!sp->dec_decode) {
279 TIFFWarningExt(tif->tif_clientdata, module,
280 "Old-style LZW codes, convert file");
281 /*
282 * Override default decoding methods with
283 * ones that deal with the old coding.
284 * Otherwise the predictor versions set
285 * above will call the compatibility routines
286 * through the dec_decode method.
287 */
288 tif->tif_decoderow = LZWDecodeCompat;
289 tif->tif_decodestrip = LZWDecodeCompat;
290 tif->tif_decodetile = LZWDecodeCompat;
291 /*
292 * If doing horizontal differencing, must
293 * re-setup the predictor logic since we
294 * switched the basic decoder methods...
295 */
296 (*tif->tif_setupdecode)(tif);
297 sp->dec_decode = LZWDecodeCompat;
298 }
299 sp->lzw_maxcode = MAXCODE(BITS_MIN);
300#else /* !LZW_COMPAT */
301 if (!sp->dec_decode) {
302 TIFFErrorExt(tif->tif_clientdata, module,
303 "Old-style LZW codes not supported");
304 sp->dec_decode = LZWDecode;
305 }
306 return (0);
307#endif/* !LZW_COMPAT */
308 } else {
309 sp->lzw_maxcode = MAXCODE(BITS_MIN)-1;
310 sp->dec_decode = LZWDecode;
311 }
312 sp->lzw_nbits = BITS_MIN;
313 sp->lzw_nextbits = 0;
314 sp->lzw_nextdata = 0;
315
316 sp->dec_restart = 0;
317 sp->dec_nbitsmask = MAXCODE(BITS_MIN);
318#ifdef LZW_CHECKEOS
319 sp->dec_bitsleft = ((uint64)tif->tif_rawcc) << 3;
320#endif
321 sp->dec_free_entp = sp->dec_codetab + CODE_FIRST;
322 /*
323 * Zero entries that are not yet filled in. We do
324 * this to guard against bogus input data that causes
325 * us to index into undefined entries. If you can
326 * come up with a way to safely bounds-check input codes
327 * while decoding then you can remove this operation.
328 */
329 _TIFFmemset(sp->dec_free_entp, 0, (CSIZE-CODE_FIRST)*sizeof (code_t));
330 sp->dec_oldcodep = &sp->dec_codetab[-1];
331 sp->dec_maxcodep = &sp->dec_codetab[sp->dec_nbitsmask-1];
332 return (1);
333}
334
335/*
336 * Decode a "hunk of data".
337 */
338#define GetNextCode(sp, bp, code) { \
339 nextdata = (nextdata<<8) | *(bp)++; \
340 nextbits += 8; \
341 if (nextbits < nbits) { \
342 nextdata = (nextdata<<8) | *(bp)++; \
343 nextbits += 8; \
344 } \
345 code = (hcode_t)((nextdata >> (nextbits-nbits)) & nbitsmask); \
346 nextbits -= nbits; \
347}
348
349static void
350codeLoop(TIFF* tif, const char* module)
351{
352 TIFFErrorExt(tif->tif_clientdata, module,
353 "Bogus encoding, loop in the code table; scanline %d",
354 tif->tif_row);
355}
356
357static int
358LZWDecode(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s)
359{
360 static const char module[] = "LZWDecode";
361 LZWCodecState *sp = DecoderState(tif);
362 char *op = (char*) op0;
363 long occ = (long) occ0;
364 char *tp;
365 unsigned char *bp;
366 hcode_t code;
367 int len;
368 long nbits, nextbits, nextdata, nbitsmask;
369 code_t *codep, *free_entp, *maxcodep, *oldcodep;
370
371 (void) s;
372 assert(sp != NULL);
373 assert(sp->dec_codetab != NULL);
374
375 /*
376 Fail if value does not fit in long.
377 */
378 if ((tmsize_t) occ != occ0)
379 return (0);
380 /*
381 * Restart interrupted output operation.
382 */
383 if (sp->dec_restart) {
384 long residue;
385
386 codep = sp->dec_codep;
387 residue = codep->length - sp->dec_restart;
388 if (residue > occ) {
389 /*
390 * Residue from previous decode is sufficient
391 * to satisfy decode request. Skip to the
392 * start of the decoded string, place decoded
393 * values in the output buffer, and return.
394 */
395 sp->dec_restart += occ;
396 do {
397 codep = codep->next;
398 } while (--residue > occ && codep);
399 if (codep) {
400 tp = op + occ;
401 do {
402 *--tp = codep->value;
403 codep = codep->next;
404 } while (--occ && codep);
405 }
406 return (1);
407 }
408 /*
409 * Residue satisfies only part of the decode request.
410 */
411 op += residue, occ -= residue;
412 tp = op;
413 do {
414 int t;
415 --tp;
416 t = codep->value;
417 codep = codep->next;
418 *tp = t;
419 } while (--residue && codep);
420 sp->dec_restart = 0;
421 }
422
423 bp = (unsigned char *)tif->tif_rawcp;
424 nbits = sp->lzw_nbits;
425 nextdata = sp->lzw_nextdata;
426 nextbits = sp->lzw_nextbits;
427 nbitsmask = sp->dec_nbitsmask;
428 oldcodep = sp->dec_oldcodep;
429 free_entp = sp->dec_free_entp;
430 maxcodep = sp->dec_maxcodep;
431
432 while (occ > 0) {
433 NextCode(tif, sp, bp, code, GetNextCode);
434 if (code == CODE_EOI)
435 break;
436 if (code == CODE_CLEAR) {
437 free_entp = sp->dec_codetab + CODE_FIRST;
438 _TIFFmemset(free_entp, 0,
439 (CSIZE - CODE_FIRST) * sizeof (code_t));
440 nbits = BITS_MIN;
441 nbitsmask = MAXCODE(BITS_MIN);
442 maxcodep = sp->dec_codetab + nbitsmask-1;
443 NextCode(tif, sp, bp, code, GetNextCode);
444 if (code == CODE_EOI)
445 break;
446 if (code >= CODE_CLEAR) {
447 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
448 "LZWDecode: Corrupted LZW table at scanline %d",
449 tif->tif_row);
450 return (0);
451 }
452 *op++ = (char)code, occ--;
453 oldcodep = sp->dec_codetab + code;
454 continue;
455 }
456 codep = sp->dec_codetab + code;
457
458 /*
459 * Add the new entry to the code table.
460 */
461 if (free_entp < &sp->dec_codetab[0] ||
462 free_entp >= &sp->dec_codetab[CSIZE]) {
463 TIFFErrorExt(tif->tif_clientdata, module,
464 "Corrupted LZW table at scanline %d",
465 tif->tif_row);
466 return (0);
467 }
468
469 free_entp->next = oldcodep;
470 if (free_entp->next < &sp->dec_codetab[0] ||
471 free_entp->next >= &sp->dec_codetab[CSIZE]) {
472 TIFFErrorExt(tif->tif_clientdata, module,
473 "Corrupted LZW table at scanline %d",
474 tif->tif_row);
475 return (0);
476 }
477 free_entp->firstchar = free_entp->next->firstchar;
478 free_entp->length = free_entp->next->length+1;
479 free_entp->value = (codep < free_entp) ?
480 codep->firstchar : free_entp->firstchar;
481 if (++free_entp > maxcodep) {
482 if (++nbits > BITS_MAX) /* should not happen */
483 nbits = BITS_MAX;
484 nbitsmask = MAXCODE(nbits);
485 maxcodep = sp->dec_codetab + nbitsmask-1;
486 }
487 oldcodep = codep;
488 if (code >= 256) {
489 /*
490 * Code maps to a string, copy string
491 * value to output (written in reverse).
492 */
493 if(codep->length == 0) {
494 TIFFErrorExt(tif->tif_clientdata, module,
495 "Wrong length of decoded string: "
496 "data probably corrupted at scanline %d",
497 tif->tif_row);
498 return (0);
499 }
500 if (codep->length > occ) {
501 /*
502 * String is too long for decode buffer,
503 * locate portion that will fit, copy to
504 * the decode buffer, and setup restart
505 * logic for the next decoding call.
506 */
507 sp->dec_codep = codep;
508 do {
509 codep = codep->next;
510 } while (codep && codep->length > occ);
511 if (codep) {
512 sp->dec_restart = (long)occ;
513 tp = op + occ;
514 do {
515 *--tp = codep->value;
516 codep = codep->next;
517 } while (--occ && codep);
518 if (codep)
519 codeLoop(tif, module);
520 }
521 break;
522 }
523 len = codep->length;
524 tp = op + len;
525 do {
526 int t;
527 --tp;
528 t = codep->value;
529 codep = codep->next;
530 *tp = t;
531 } while (codep && tp > op);
532 if (codep) {
533 codeLoop(tif, module);
534 break;
535 }
536 assert(occ >= len);
537 op += len, occ -= len;
538 } else
539 *op++ = (char)code, occ--;
540 }
541
542 tif->tif_rawcp = (uint8*) bp;
543 sp->lzw_nbits = (unsigned short) nbits;
544 sp->lzw_nextdata = nextdata;
545 sp->lzw_nextbits = nextbits;
546 sp->dec_nbitsmask = nbitsmask;
547 sp->dec_oldcodep = oldcodep;
548 sp->dec_free_entp = free_entp;
549 sp->dec_maxcodep = maxcodep;
550
551 if (occ > 0) {
552#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
553 TIFFErrorExt(tif->tif_clientdata, module,
554 "Not enough data at scanline %d (short %I64d bytes)",
555 tif->tif_row, (unsigned __int64) occ);
556#else
557 TIFFErrorExt(tif->tif_clientdata, module,
558 "Not enough data at scanline %d (short %llu bytes)",
559 tif->tif_row, (unsigned long long) occ);
560#endif
561 return (0);
562 }
563 return (1);
564}
565
566#ifdef LZW_COMPAT
567/*
568 * Decode a "hunk of data" for old images.
569 */
570#define GetNextCodeCompat(sp, bp, code) { \
571 nextdata |= (unsigned long) *(bp)++ << nextbits; \
572 nextbits += 8; \
573 if (nextbits < nbits) { \
574 nextdata |= (unsigned long) *(bp)++ << nextbits;\
575 nextbits += 8; \
576 } \
577 code = (hcode_t)(nextdata & nbitsmask); \
578 nextdata >>= nbits; \
579 nextbits -= nbits; \
580}
581
582static int
583LZWDecodeCompat(TIFF* tif, uint8* op0, tmsize_t occ0, uint16 s)
584{
585 static const char module[] = "LZWDecodeCompat";
586 LZWCodecState *sp = DecoderState(tif);
587 char *op = (char*) op0;
588 long occ = (long) occ0;
589 char *tp;
590 unsigned char *bp;
591 int code, nbits;
592 long nextbits, nextdata, nbitsmask;
593 code_t *codep, *free_entp, *maxcodep, *oldcodep;
594
595 (void) s;
596 assert(sp != NULL);
597
598 /*
599 Fail if value does not fit in long.
600 */
601 if ((tmsize_t) occ != occ0)
602 return (0);
603
604 /*
605 * Restart interrupted output operation.
606 */
607 if (sp->dec_restart) {
608 long residue;
609
610 codep = sp->dec_codep;
611 residue = codep->length - sp->dec_restart;
612 if (residue > occ) {
613 /*
614 * Residue from previous decode is sufficient
615 * to satisfy decode request. Skip to the
616 * start of the decoded string, place decoded
617 * values in the output buffer, and return.
618 */
619 sp->dec_restart += occ;
620 do {
621 codep = codep->next;
622 } while (--residue > occ);
623 tp = op + occ;
624 do {
625 *--tp = codep->value;
626 codep = codep->next;
627 } while (--occ);
628 return (1);
629 }
630 /*
631 * Residue satisfies only part of the decode request.
632 */
633 op += residue, occ -= residue;
634 tp = op;
635 do {
636 *--tp = codep->value;
637 codep = codep->next;
638 } while (--residue);
639 sp->dec_restart = 0;
640 }
641
642 bp = (unsigned char *)tif->tif_rawcp;
643 nbits = sp->lzw_nbits;
644 nextdata = sp->lzw_nextdata;
645 nextbits = sp->lzw_nextbits;
646 nbitsmask = sp->dec_nbitsmask;
647 oldcodep = sp->dec_oldcodep;
648 free_entp = sp->dec_free_entp;
649 maxcodep = sp->dec_maxcodep;
650
651 while (occ > 0) {
652 NextCode(tif, sp, bp, code, GetNextCodeCompat);
653 if (code == CODE_EOI)
654 break;
655 if (code == CODE_CLEAR) {
656 free_entp = sp->dec_codetab + CODE_FIRST;
657 _TIFFmemset(free_entp, 0,
658 (CSIZE - CODE_FIRST) * sizeof (code_t));
659 nbits = BITS_MIN;
660 nbitsmask = MAXCODE(BITS_MIN);
661 maxcodep = sp->dec_codetab + nbitsmask;
662 NextCode(tif, sp, bp, code, GetNextCodeCompat);
663 if (code == CODE_EOI)
664 break;
665 if (code >= CODE_CLEAR) {
666 TIFFErrorExt(tif->tif_clientdata, tif->tif_name,
667 "LZWDecode: Corrupted LZW table at scanline %d",
668 tif->tif_row);
669 return (0);
670 }
671 *op++ = code, occ--;
672 oldcodep = sp->dec_codetab + code;
673 continue;
674 }
675 codep = sp->dec_codetab + code;
676
677 /*
678 * Add the new entry to the code table.
679 */
680 if (free_entp < &sp->dec_codetab[0] ||
681 free_entp >= &sp->dec_codetab[CSIZE]) {
682 TIFFErrorExt(tif->tif_clientdata, module,
683 "Corrupted LZW table at scanline %d", tif->tif_row);
684 return (0);
685 }
686
687 free_entp->next = oldcodep;
688 if (free_entp->next < &sp->dec_codetab[0] ||
689 free_entp->next >= &sp->dec_codetab[CSIZE]) {
690 TIFFErrorExt(tif->tif_clientdata, module,
691 "Corrupted LZW table at scanline %d", tif->tif_row);
692 return (0);
693 }
694 free_entp->firstchar = free_entp->next->firstchar;
695 free_entp->length = free_entp->next->length+1;
696 free_entp->value = (codep < free_entp) ?
697 codep->firstchar : free_entp->firstchar;
698 if (++free_entp > maxcodep) {
699 if (++nbits > BITS_MAX) /* should not happen */
700 nbits = BITS_MAX;
701 nbitsmask = MAXCODE(nbits);
702 maxcodep = sp->dec_codetab + nbitsmask;
703 }
704 oldcodep = codep;
705 if (code >= 256) {
706 /*
707 * Code maps to a string, copy string
708 * value to output (written in reverse).
709 */
710 if(codep->length == 0) {
711 TIFFErrorExt(tif->tif_clientdata, module,
712 "Wrong length of decoded "
713 "string: data probably corrupted at scanline %d",
714 tif->tif_row);
715 return (0);
716 }
717 if (codep->length > occ) {
718 /*
719 * String is too long for decode buffer,
720 * locate portion that will fit, copy to
721 * the decode buffer, and setup restart
722 * logic for the next decoding call.
723 */
724 sp->dec_codep = codep;
725 do {
726 codep = codep->next;
727 } while (codep->length > occ);
728 sp->dec_restart = occ;
729 tp = op + occ;
730 do {
731 *--tp = codep->value;
732 codep = codep->next;
733 } while (--occ);
734 break;
735 }
736 assert(occ >= codep->length);
737 op += codep->length, occ -= codep->length;
738 tp = op;
739 do {
740 *--tp = codep->value;
741 } while( (codep = codep->next) != NULL );
742 } else
743 *op++ = code, occ--;
744 }
745
746 tif->tif_rawcp = (uint8*) bp;
747 sp->lzw_nbits = nbits;
748 sp->lzw_nextdata = nextdata;
749 sp->lzw_nextbits = nextbits;
750 sp->dec_nbitsmask = nbitsmask;
751 sp->dec_oldcodep = oldcodep;
752 sp->dec_free_entp = free_entp;
753 sp->dec_maxcodep = maxcodep;
754
755 if (occ > 0) {
756#if defined(__WIN32__) && (defined(_MSC_VER) || defined(__MINGW32__))
757 TIFFErrorExt(tif->tif_clientdata, module,
758 "Not enough data at scanline %d (short %I64d bytes)",
759 tif->tif_row, (unsigned __int64) occ);
760#else
761 TIFFErrorExt(tif->tif_clientdata, module,
762 "Not enough data at scanline %d (short %llu bytes)",
763 tif->tif_row, (unsigned long long) occ);
764#endif
765 return (0);
766 }
767 return (1);
768}
769#endif /* LZW_COMPAT */
770
771/*
772 * LZW Encoding.
773 */
774
775static int
776LZWSetupEncode(TIFF* tif)
777{
778 static const char module[] = "LZWSetupEncode";
779 LZWCodecState* sp = EncoderState(tif);
780
781 assert(sp != NULL);
782 sp->enc_hashtab = (hash_t*) _TIFFmalloc(HSIZE*sizeof (hash_t));
783 if (sp->enc_hashtab == NULL) {
784 TIFFErrorExt(tif->tif_clientdata, module,
785 "No space for LZW hash table");
786 return (0);
787 }
788 return (1);
789}
790
791/*
792 * Reset encoding state at the start of a strip.
793 */
794static int
795LZWPreEncode(TIFF* tif, uint16 s)
796{
797 LZWCodecState *sp = EncoderState(tif);
798
799 (void) s;
800 assert(sp != NULL);
801
802 if( sp->enc_hashtab == NULL )
803 {
804 tif->tif_setupencode( tif );
805 }
806
807 sp->lzw_nbits = BITS_MIN;
808 sp->lzw_maxcode = MAXCODE(BITS_MIN);
809 sp->lzw_free_ent = CODE_FIRST;
810 sp->lzw_nextbits = 0;
811 sp->lzw_nextdata = 0;
812 sp->enc_checkpoint = CHECK_GAP;
813 sp->enc_ratio = 0;
814 sp->enc_incount = 0;
815 sp->enc_outcount = 0;
816 /*
817 * The 4 here insures there is space for 2 max-sized
818 * codes in LZWEncode and LZWPostDecode.
819 */
820 sp->enc_rawlimit = tif->tif_rawdata + tif->tif_rawdatasize-1 - 4;
821 cl_hash(sp); /* clear hash table */
822 sp->enc_oldcode = (hcode_t) -1; /* generates CODE_CLEAR in LZWEncode */
823 return (1);
824}
825
826#define CALCRATIO(sp, rat) { \
827 if (incount > 0x007fffff) { /* NB: shift will overflow */\
828 rat = outcount >> 8; \
829 rat = (rat == 0 ? 0x7fffffff : incount/rat); \
830 } else \
831 rat = (incount<<8) / outcount; \
832}
833#define PutNextCode(op, c) { \
834 nextdata = (nextdata << nbits) | c; \
835 nextbits += nbits; \
836 *op++ = (unsigned char)(nextdata >> (nextbits-8)); \
837 nextbits -= 8; \
838 if (nextbits >= 8) { \
839 *op++ = (unsigned char)(nextdata >> (nextbits-8)); \
840 nextbits -= 8; \
841 } \
842 outcount += nbits; \
843}
844
845/*
846 * Encode a chunk of pixels.
847 *
848 * Uses an open addressing double hashing (no chaining) on the
849 * prefix code/next character combination. We do a variant of
850 * Knuth's algorithm D (vol. 3, sec. 6.4) along with G. Knott's
851 * relatively-prime secondary probe. Here, the modular division
852 * first probe is gives way to a faster exclusive-or manipulation.
853 * Also do block compression with an adaptive reset, whereby the
854 * code table is cleared when the compression ratio decreases,
855 * but after the table fills. The variable-length output codes
856 * are re-sized at this point, and a CODE_CLEAR is generated
857 * for the decoder.
858 */
859static int
860LZWEncode(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
861{
862 register LZWCodecState *sp = EncoderState(tif);
863 register long fcode;
864 register hash_t *hp;
865 register int h, c;
866 hcode_t ent;
867 long disp;
868 long incount, outcount, checkpoint;
869 long nextdata, nextbits;
870 int free_ent, maxcode, nbits;
871 uint8* op;
872 uint8* limit;
873
874 (void) s;
875 if (sp == NULL)
876 return (0);
877
878 assert(sp->enc_hashtab != NULL);
879
880 /*
881 * Load local state.
882 */
883 incount = sp->enc_incount;
884 outcount = sp->enc_outcount;
885 checkpoint = sp->enc_checkpoint;
886 nextdata = sp->lzw_nextdata;
887 nextbits = sp->lzw_nextbits;
888 free_ent = sp->lzw_free_ent;
889 maxcode = sp->lzw_maxcode;
890 nbits = sp->lzw_nbits;
891 op = tif->tif_rawcp;
892 limit = sp->enc_rawlimit;
893 ent = sp->enc_oldcode;
894
895 if (ent == (hcode_t) -1 && cc > 0) {
896 /*
897 * NB: This is safe because it can only happen
898 * at the start of a strip where we know there
899 * is space in the data buffer.
900 */
901 PutNextCode(op, CODE_CLEAR);
902 ent = *bp++; cc--; incount++;
903 }
904 while (cc > 0) {
905 c = *bp++; cc--; incount++;
906 fcode = ((long)c << BITS_MAX) + ent;
907 h = (c << HSHIFT) ^ ent; /* xor hashing */
908#ifdef _WINDOWS
909 /*
910 * Check hash index for an overflow.
911 */
912 if (h >= HSIZE)
913 h -= HSIZE;
914#endif
915 hp = &sp->enc_hashtab[h];
916 if (hp->hash == fcode) {
917 ent = hp->code;
918 continue;
919 }
920 if (hp->hash >= 0) {
921 /*
922 * Primary hash failed, check secondary hash.
923 */
924 disp = HSIZE - h;
925 if (h == 0)
926 disp = 1;
927 do {
928 /*
929 * Avoid pointer arithmetic 'cuz of
930 * wraparound problems with segments.
931 */
932 if ((h -= disp) < 0)
933 h += HSIZE;
934 hp = &sp->enc_hashtab[h];
935 if (hp->hash == fcode) {
936 ent = hp->code;
937 goto hit;
938 }
939 } while (hp->hash >= 0);
940 }
941 /*
942 * New entry, emit code and add to table.
943 */
944 /*
945 * Verify there is space in the buffer for the code
946 * and any potential Clear code that might be emitted
947 * below. The value of limit is setup so that there
948 * are at least 4 bytes free--room for 2 codes.
949 */
950 if (op > limit) {
951 tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
952 TIFFFlushData1(tif);
953 op = tif->tif_rawdata;
954 }
955 PutNextCode(op, ent);
956 ent = c;
957 hp->code = free_ent++;
958 hp->hash = fcode;
959 if (free_ent == CODE_MAX-1) {
960 /* table is full, emit clear code and reset */
961 cl_hash(sp);
962 sp->enc_ratio = 0;
963 incount = 0;
964 outcount = 0;
965 free_ent = CODE_FIRST;
966 PutNextCode(op, CODE_CLEAR);
967 nbits = BITS_MIN;
968 maxcode = MAXCODE(BITS_MIN);
969 } else {
970 /*
971 * If the next entry is going to be too big for
972 * the code size, then increase it, if possible.
973 */
974 if (free_ent > maxcode) {
975 nbits++;
976 assert(nbits <= BITS_MAX);
977 maxcode = (int) MAXCODE(nbits);
978 } else if (incount >= checkpoint) {
979 long rat;
980 /*
981 * Check compression ratio and, if things seem
982 * to be slipping, clear the hash table and
983 * reset state. The compression ratio is a
984 * 24+8-bit fractional number.
985 */
986 checkpoint = incount+CHECK_GAP;
987 CALCRATIO(sp, rat);
988 if (rat <= sp->enc_ratio) {
989 cl_hash(sp);
990 sp->enc_ratio = 0;
991 incount = 0;
992 outcount = 0;
993 free_ent = CODE_FIRST;
994 PutNextCode(op, CODE_CLEAR);
995 nbits = BITS_MIN;
996 maxcode = MAXCODE(BITS_MIN);
997 } else
998 sp->enc_ratio = rat;
999 }
1000 }
1001 hit:
1002 ;
1003 }
1004
1005 /*
1006 * Restore global state.
1007 */
1008 sp->enc_incount = incount;
1009 sp->enc_outcount = outcount;
1010 sp->enc_checkpoint = checkpoint;
1011 sp->enc_oldcode = ent;
1012 sp->lzw_nextdata = nextdata;
1013 sp->lzw_nextbits = nextbits;
1014 sp->lzw_free_ent = free_ent;
1015 sp->lzw_maxcode = maxcode;
1016 sp->lzw_nbits = nbits;
1017 tif->tif_rawcp = op;
1018 return (1);
1019}
1020
1021/*
1022 * Finish off an encoded strip by flushing the last
1023 * string and tacking on an End Of Information code.
1024 */
1025static int
1026LZWPostEncode(TIFF* tif)
1027{
1028 register LZWCodecState *sp = EncoderState(tif);
1029 uint8* op = tif->tif_rawcp;
1030 long nextbits = sp->lzw_nextbits;
1031 long nextdata = sp->lzw_nextdata;
1032 long outcount = sp->enc_outcount;
1033 int nbits = sp->lzw_nbits;
1034
1035 if (op > sp->enc_rawlimit) {
1036 tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
1037 TIFFFlushData1(tif);
1038 op = tif->tif_rawdata;
1039 }
1040 if (sp->enc_oldcode != (hcode_t) -1) {
1041 PutNextCode(op, sp->enc_oldcode);
1042 sp->enc_oldcode = (hcode_t) -1;
1043 }
1044 PutNextCode(op, CODE_EOI);
1045 if (nextbits > 0)
1046 *op++ = (unsigned char)(nextdata << (8-nextbits));
1047 tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
1048 return (1);
1049}
1050
1051/*
1052 * Reset encoding hash table.
1053 */
1054static void
1055cl_hash(LZWCodecState* sp)
1056{
1057 register hash_t *hp = &sp->enc_hashtab[HSIZE-1];
1058 register long i = HSIZE-8;
1059
1060 do {
1061 i -= 8;
1062 hp[-7].hash = -1;
1063 hp[-6].hash = -1;
1064 hp[-5].hash = -1;
1065 hp[-4].hash = -1;
1066 hp[-3].hash = -1;
1067 hp[-2].hash = -1;
1068 hp[-1].hash = -1;
1069 hp[ 0].hash = -1;
1070 hp -= 8;
1071 } while (i >= 0);
1072 for (i += 8; i > 0; i--, hp--)
1073 hp->hash = -1;
1074}
1075
1076static void
1077LZWCleanup(TIFF* tif)
1078{
1079 (void)TIFFPredictorCleanup(tif);
1080
1081 assert(tif->tif_data != 0);
1082
1083 if (DecoderState(tif)->dec_codetab)
1084 _TIFFfree(DecoderState(tif)->dec_codetab);
1085
1086 if (EncoderState(tif)->enc_hashtab)
1087 _TIFFfree(EncoderState(tif)->enc_hashtab);
1088
1089 _TIFFfree(tif->tif_data);
1090 tif->tif_data = NULL;
1091
1092 _TIFFSetDefaultCompressionState(tif);
1093}
1094
1095int
1096TIFFInitLZW(TIFF* tif, int scheme)
1097{
1098 static const char module[] = "TIFFInitLZW";
1099 assert(scheme == COMPRESSION_LZW);
1100 /*
1101 * Allocate state block so tag methods have storage to record values.
1102 */
1103 tif->tif_data = (uint8*) _TIFFmalloc(sizeof (LZWCodecState));
1104 if (tif->tif_data == NULL)
1105 goto bad;
1106 DecoderState(tif)->dec_codetab = NULL;
1107 DecoderState(tif)->dec_decode = NULL;
1108 EncoderState(tif)->enc_hashtab = NULL;
1109 LZWState(tif)->rw_mode = tif->tif_mode;
1110
1111 /*
1112 * Install codec methods.
1113 */
1114 tif->tif_fixuptags = LZWFixupTags;
1115 tif->tif_setupdecode = LZWSetupDecode;
1116 tif->tif_predecode = LZWPreDecode;
1117 tif->tif_decoderow = LZWDecode;
1118 tif->tif_decodestrip = LZWDecode;
1119 tif->tif_decodetile = LZWDecode;
1120 tif->tif_setupencode = LZWSetupEncode;
1121 tif->tif_preencode = LZWPreEncode;
1122 tif->tif_postencode = LZWPostEncode;
1123 tif->tif_encoderow = LZWEncode;
1124 tif->tif_encodestrip = LZWEncode;
1125 tif->tif_encodetile = LZWEncode;
1126 tif->tif_cleanup = LZWCleanup;
1127 /*
1128 * Setup predictor setup.
1129 */
1130 (void) TIFFPredictorInit(tif);
1131 return (1);
1132bad:
1133 TIFFErrorExt(tif->tif_clientdata, module,
1134 "No space for LZW state block");
1135 return (0);
1136}
1137
1138/*
1139 * Copyright (c) 1985, 1986 The Regents of the University of California.
1140 * All rights reserved.
1141 *
1142 * This code is derived from software contributed to Berkeley by
1143 * James A. Woods, derived from original work by Spencer Thomas
1144 * and Joseph Orost.
1145 *
1146 * Redistribution and use in source and binary forms are permitted
1147 * provided that the above copyright notice and this paragraph are
1148 * duplicated in all such forms and that any documentation,
1149 * advertising materials, and other materials related to such
1150 * distribution and use acknowledge that the software was developed
1151 * by the University of California, Berkeley. The name of the
1152 * University may not be used to endorse or promote products derived
1153 * from this software without specific prior written permission.
1154 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
1155 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
1156 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
1157 */
1158#endif /* LZW_SUPPORT */
1159
1160/* vim: set ts=8 sts=8 sw=8 noet: */
1161/*
1162 * Local Variables:
1163 * mode: c
1164 * c-basic-offset: 8
1165 * fill-column: 78
1166 * End:
1167 */
1168
generated by cgit at 2024-05-18 21:49:58 (GMT)