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