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1 /* $Id$ */
2
3 /*
4 * Copyright (c) 1990-1997 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 #ifndef _FAX3_
28 #define _FAX3_
29 /*
30 * TIFF Library.
31 *
32 * CCITT Group 3 (T.4) and Group 4 (T.6) Decompression Support.
33 *
34 * Decoder support is derived, with permission, from the code
35 * in Frank Cringle's viewfax program;
36 * Copyright (C) 1990, 1995 Frank D. Cringle.
37 */
38 #include "tiff.h"
39
40 /*
41 * To override the default routine used to image decoded
42 * spans one can use the pseduo tag TIFFTAG_FAXFILLFUNC.
43 * The routine must have the type signature given below;
44 * for example:
45 *
46 * fillruns(unsigned char* buf, uint32* runs, uint32* erun, uint32 lastx)
47 *
48 * where buf is place to set the bits, runs is the array of b&w run
49 * lengths (white then black), erun is the last run in the array, and
50 * lastx is the width of the row in pixels. Fill routines can assume
51 * the run array has room for at least lastx runs and can overwrite
52 * data in the run array as needed (e.g. to append zero runs to bring
53 * the count up to a nice multiple).
54 */
55 typedef void (*TIFFFaxFillFunc)(unsigned char*, uint32*, uint32*, uint32);
56
57 /*
58 * The default run filler; made external for other decoders.
59 */
60 #if defined(__cplusplus)
61 extern "C" {
62 #endif
63 extern void _TIFFFax3fillruns(unsigned char*, uint32*, uint32*, uint32);
64 #if defined(__cplusplus)
65 }
66 #endif
67
68
69 /* finite state machine codes */
70 #define S_Null 0
71 #define S_Pass 1
72 #define S_Horiz 2
73 #define S_V0 3
74 #define S_VR 4
75 #define S_VL 5
76 #define S_Ext 6
77 #define S_TermW 7
78 #define S_TermB 8
79 #define S_MakeUpW 9
80 #define S_MakeUpB 10
81 #define S_MakeUp 11
82 #define S_EOL 12
83
84 typedef struct { /* state table entry */
85 unsigned char State; /* see above */
86 unsigned char Width; /* width of code in bits */
87 uint32 Param; /* unsigned 32-bit run length in bits */
88 } TIFFFaxTabEnt;
89
90 extern const TIFFFaxTabEnt TIFFFaxMainTable[];
91 extern const TIFFFaxTabEnt TIFFFaxWhiteTable[];
92 extern const TIFFFaxTabEnt TIFFFaxBlackTable[];
93
94 /*
95 * The following macros define the majority of the G3/G4 decoder
96 * algorithm using the state tables defined elsewhere. To build
97 * a decoder you need some setup code and some glue code. Note
98 * that you may also need/want to change the way the NeedBits*
99 * macros get input data if, for example, you know the data to be
100 * decoded is properly aligned and oriented (doing so before running
101 * the decoder can be a big performance win).
102 *
103 * Consult the decoder in the TIFF library for an idea of what you
104 * need to define and setup to make use of these definitions.
105 *
106 * NB: to enable a debugging version of these macros define FAX3_DEBUG
107 * before including this file. Trace output goes to stdout.
108 */
109
110 #ifndef EndOfData
111 #define EndOfData() (cp >= ep)
112 #endif
113 /*
114 * Need <=8 or <=16 bits of input data. Unlike viewfax we
115 * cannot use/assume a word-aligned, properly bit swizzled
116 * input data set because data may come from an arbitrarily
117 * aligned, read-only source such as a memory-mapped file.
118 * Note also that the viewfax decoder does not check for
119 * running off the end of the input data buffer. This is
120 * possible for G3-encoded data because it prescans the input
121 * data to count EOL markers, but can cause problems for G4
122 * data. In any event, we don't prescan and must watch for
123 * running out of data since we can't permit the library to
124 * scan past the end of the input data buffer.
125 *
126 * Finally, note that we must handle remaindered data at the end
127 * of a strip specially. The coder asks for a fixed number of
128 * bits when scanning for the next code. This may be more bits
129 * than are actually present in the data stream. If we appear
130 * to run out of data but still have some number of valid bits
131 * remaining then we makeup the requested amount with zeros and
132 * return successfully. If the returned data is incorrect then
133 * we should be called again and get a premature EOF error;
134 * otherwise we should get the right answer.
135 */
136 #ifndef NeedBits8
137 #define NeedBits8(n,eoflab) do { \
138 if (BitsAvail < (n)) { \
139 if (EndOfData()) { \
140 if (BitsAvail == 0) /* no valid bits */ \
141 goto eoflab; \
142 BitsAvail = (n); /* pad with zeros */ \
143 } else { \
144 BitAcc |= ((uint32) bitmap[*cp++])<<BitsAvail; \
145 BitsAvail += 8; \
146 } \
147 } \
148 } while (0)
149 #endif
150 #ifndef NeedBits16
151 #define NeedBits16(n,eoflab) do { \
152 if (BitsAvail < (n)) { \
153 if (EndOfData()) { \
154 if (BitsAvail == 0) /* no valid bits */ \
155 goto eoflab; \
156 BitsAvail = (n); /* pad with zeros */ \
157 } else { \
158 BitAcc |= ((uint32) bitmap[*cp++])<<BitsAvail; \
159 if ((BitsAvail += 8) < (n)) { \
160 if (EndOfData()) { \
161 /* NB: we know BitsAvail is non-zero here */ \
162 BitsAvail = (n); /* pad with zeros */ \
163 } else { \
164 BitAcc |= ((uint32) bitmap[*cp++])<<BitsAvail; \
165 BitsAvail += 8; \
166 } \
167 } \
168 } \
169 } \
170 } while (0)
171 #endif
172 #define GetBits(n) (BitAcc & ((1<<(n))-1))
173 #define ClrBits(n) do { \
174 BitsAvail -= (n); \
175 BitAcc >>= (n); \
176 } while (0)
177
178 #ifdef FAX3_DEBUG
179 static const char* StateNames[] = {
180 "Null ",
181 "Pass ",
182 "Horiz ",
183 "V0 ",
184 "VR ",
185 "VL ",
186 "Ext ",
187 "TermW ",
188 "TermB ",
189 "MakeUpW",
190 "MakeUpB",
191 "MakeUp ",
192 "EOL ",
193 };
194 #define DEBUG_SHOW putchar(BitAcc & (1 << t) ? '1' : '0')
195 #define LOOKUP8(wid,tab,eoflab) do { \
196 int t; \
197 NeedBits8(wid,eoflab); \
198 TabEnt = tab + GetBits(wid); \
199 printf("%08lX/%d: %s%5d\t", (long) BitAcc, BitsAvail, \
200 StateNames[TabEnt->State], TabEnt->Param); \
201 for (t = 0; t < TabEnt->Width; t++) \
202 DEBUG_SHOW; \
203 putchar('\n'); \
204 fflush(stdout); \
205 ClrBits(TabEnt->Width); \
206 } while (0)
207 #define LOOKUP16(wid,tab,eoflab) do { \
208 int t; \
209 NeedBits16(wid,eoflab); \
210 TabEnt = tab + GetBits(wid); \
211 printf("%08lX/%d: %s%5d\t", (long) BitAcc, BitsAvail, \
212 StateNames[TabEnt->State], TabEnt->Param); \
213 for (t = 0; t < TabEnt->Width; t++) \
214 DEBUG_SHOW; \
215 putchar('\n'); \
216 fflush(stdout); \
217 ClrBits(TabEnt->Width); \
218 } while (0)
219
220 #define SETVAL(x) do { \
221 *pa++ = RunLength + (x); \
222 printf("SETVAL: %d\t%d\n", RunLength + (x), a0); \
223 a0 += x; \
224 RunLength = 0; \
225 } while (0)
226 #else
227 #define LOOKUP8(wid,tab,eoflab) do { \
228 NeedBits8(wid,eoflab); \
229 TabEnt = tab + GetBits(wid); \
230 ClrBits(TabEnt->Width); \
231 } while (0)
232 #define LOOKUP16(wid,tab,eoflab) do { \
233 NeedBits16(wid,eoflab); \
234 TabEnt = tab + GetBits(wid); \
235 ClrBits(TabEnt->Width); \
236 } while (0)
237
238 /*
239 * Append a run to the run length array for the
240 * current row and reset decoding state.
241 */
242 #define SETVAL(x) do { \
243 *pa++ = RunLength + (x); \
244 a0 += (x); \
245 RunLength = 0; \
246 } while (0)
247 #endif
248
249 /*
250 * Synchronize input decoding at the start of each
251 * row by scanning for an EOL (if appropriate) and
252 * skipping any trash data that might be present
253 * after a decoding error. Note that the decoding
254 * done elsewhere that recognizes an EOL only consumes
255 * 11 consecutive zero bits. This means that if EOLcnt
256 * is non-zero then we still need to scan for the final flag
257 * bit that is part of the EOL code.
258 */
259 #define SYNC_EOL(eoflab) do { \
260 if (EOLcnt == 0) { \
261 for (;;) { \
262 NeedBits16(11,eoflab); \
263 if (GetBits(11) == 0) \
264 break; \
265 ClrBits(1); \
266 } \
267 } \
268 for (;;) { \
269 NeedBits8(8,eoflab); \
270 if (GetBits(8)) \
271 break; \
272 ClrBits(8); \
273 } \
274 while (GetBits(1) == 0) \
275 ClrBits(1); \
276 ClrBits(1); /* EOL bit */ \
277 EOLcnt = 0; /* reset EOL counter/flag */ \
278 } while (0)
279
280 /*
281 * Cleanup the array of runs after decoding a row.
282 * We adjust final runs to insure the user buffer is not
283 * overwritten and/or undecoded area is white filled.
284 */
285 #define CLEANUP_RUNS() do { \
286 if (RunLength) \
287 SETVAL(0); \
288 if (a0 != lastx) { \
289 badlength(a0, lastx); \
290 while (a0 > lastx && pa > thisrun) \
291 a0 -= *--pa; \
292 if (a0 < lastx) { \
293 if (a0 < 0) \
294 a0 = 0; \
295 if ((pa-thisrun)&1) \
296 SETVAL(0); \
297 SETVAL(lastx - a0); \
298 } else if (a0 > lastx) { \
299 SETVAL(lastx); \
300 SETVAL(0); \
301 } \
302 } \
303 } while (0)
304
305 /*
306 * Decode a line of 1D-encoded data.
307 *
308 * The line expanders are written as macros so that they can be reused
309 * but still have direct access to the local variables of the "calling"
310 * function.
311 *
312 * Note that unlike the original version we have to explicitly test for
313 * a0 >= lastx after each black/white run is decoded. This is because
314 * the original code depended on the input data being zero-padded to
315 * insure the decoder recognized an EOL before running out of data.
316 */
317 #define EXPAND1D(eoflab) do { \
318 for (;;) { \
319 for (;;) { \
320 LOOKUP16(12, TIFFFaxWhiteTable, eof1d); \
321 switch (TabEnt->State) { \
322 case S_EOL: \
323 EOLcnt = 1; \
324 goto done1d; \
325 case S_TermW: \
326 SETVAL(TabEnt->Param); \
327 goto doneWhite1d; \
328 case S_MakeUpW: \
329 case S_MakeUp: \
330 a0 += TabEnt->Param; \
331 RunLength += TabEnt->Param; \
332 break; \
333 default: \
334 unexpected("WhiteTable", a0); \
335 goto done1d; \
336 } \
337 } \
338 doneWhite1d: \
339 if (a0 >= lastx) \
340 goto done1d; \
341 for (;;) { \
342 LOOKUP16(13, TIFFFaxBlackTable, eof1d); \
343 switch (TabEnt->State) { \
344 case S_EOL: \
345 EOLcnt = 1; \
346 goto done1d; \
347 case S_TermB: \
348 SETVAL(TabEnt->Param); \
349 goto doneBlack1d; \
350 case S_MakeUpB: \
351 case S_MakeUp: \
352 a0 += TabEnt->Param; \
353 RunLength += TabEnt->Param; \
354 break; \
355 default: \
356 unexpected("BlackTable", a0); \
357 goto done1d; \
358 } \
359 } \
360 doneBlack1d: \
361 if (a0 >= lastx) \
362 goto done1d; \
363 } \
364 eof1d: \
365 prematureEOF(a0); \
366 CLEANUP_RUNS(); \
367 goto eoflab; \
368 done1d: \
369 CLEANUP_RUNS(); \
370 } while (0)
371
372 /*
373 * Update the value of b1 using the array
374 * of runs for the reference line.
375 */
376 #define CHECK_b1 do { \
377 if (pa != thisrun) while (b1 <= a0 && b1 < lastx) { \
378 b1 += pb[0] + pb[1]; \
379 pb += 2; \
380 } \
381 } while (0)
382
383 /*
384 * Expand a row of 2D-encoded data.
385 */
386 #define EXPAND2D(eoflab) do { \
387 while (a0 < lastx) { \
388 LOOKUP8(7, TIFFFaxMainTable, eof2d); \
389 switch (TabEnt->State) { \
390 case S_Pass: \
391 CHECK_b1; \
392 b1 += *pb++; \
393 RunLength += b1 - a0; \
394 a0 = b1; \
395 b1 += *pb++; \
396 break; \
397 case S_Horiz: \
398 if ((pa-thisrun)&1) { \
399 for (;;) { /* black first */ \
400 LOOKUP16(13, TIFFFaxBlackTable, eof2d); \
401 switch (TabEnt->State) { \
402 case S_TermB: \
403 SETVAL(TabEnt->Param); \
404 goto doneWhite2da; \
405 case S_MakeUpB: \
406 case S_MakeUp: \
407 a0 += TabEnt->Param; \
408 RunLength += TabEnt->Param; \
409 break; \
410 default: \
411 goto badBlack2d; \
412 } \
413 } \
414 doneWhite2da:; \
415 for (;;) { /* then white */ \
416 LOOKUP16(12, TIFFFaxWhiteTable, eof2d); \
417 switch (TabEnt->State) { \
418 case S_TermW: \
419 SETVAL(TabEnt->Param); \
420 goto doneBlack2da; \
421 case S_MakeUpW: \
422 case S_MakeUp: \
423 a0 += TabEnt->Param; \
424 RunLength += TabEnt->Param; \
425 break; \
426 default: \
427 goto badWhite2d; \
428 } \
429 } \
430 doneBlack2da:; \
431 } else { \
432 for (;;) { /* white first */ \
433 LOOKUP16(12, TIFFFaxWhiteTable, eof2d); \
434 switch (TabEnt->State) { \
435 case S_TermW: \
436 SETVAL(TabEnt->Param); \
437 goto doneWhite2db; \
438 case S_MakeUpW: \
439 case S_MakeUp: \
440 a0 += TabEnt->Param; \
441 RunLength += TabEnt->Param; \
442 break; \
443 default: \
444 goto badWhite2d; \
445 } \
446 } \
447 doneWhite2db:; \
448 for (;;) { /* then black */ \
449 LOOKUP16(13, TIFFFaxBlackTable, eof2d); \
450 switch (TabEnt->State) { \
451 case S_TermB: \
452 SETVAL(TabEnt->Param); \
453 goto doneBlack2db; \
454 case S_MakeUpB: \
455 case S_MakeUp: \
456 a0 += TabEnt->Param; \
457 RunLength += TabEnt->Param; \
458 break; \
459 default: \
460 goto badBlack2d; \
461 } \
462 } \
463 doneBlack2db:; \
464 } \
465 CHECK_b1; \
466 break; \
467 case S_V0: \
468 CHECK_b1; \
469 SETVAL(b1 - a0); \
470 b1 += *pb++; \
471 break; \
472 case S_VR: \
473 CHECK_b1; \
474 SETVAL(b1 - a0 + TabEnt->Param); \
475 b1 += *pb++; \
476 break; \
477 case S_VL: \
478 CHECK_b1; \
479 SETVAL(b1 - a0 - TabEnt->Param); \
480 b1 -= *--pb; \
481 break; \
482 case S_Ext: \
483 *pa++ = lastx - a0; \
484 extension(a0); \
485 goto eol2d; \
486 case S_EOL: \
487 *pa++ = lastx - a0; \
488 NeedBits8(5,eof2d); \
489 if (GetBits(5)) \
490 unexpected("EOL", a0); \
491 EOLcnt = 1; \
492 goto eol2d; \
493 default: \
494 badMain2d: \
495 unexpected("MainTable", a0); \
496 goto eol2d; \
497 badBlack2d: \
498 unexpected("BlackTable", a0); \
499 goto eol2d; \
500 badWhite2d: \
501 unexpected("WhiteTable", a0); \
502 goto eol2d; \
503 eof2d: \
504 prematureEOF(a0); \
505 CLEANUP_RUNS(); \
506 goto eoflab; \
507 } \
508 } \
509 if (RunLength) { \
510 if (RunLength + a0 < lastx) { \
511 /* expect a final V0 */ \
512 NeedBits8(1,eof2d); \
513 if (!GetBits(1)) \
514 goto badMain2d; \
515 ClrBits(1); \
516 } \
517 SETVAL(0); \
518 } \
519 eol2d: \
520 CLEANUP_RUNS(); \
521 } while (0)
522 #endif /* _FAX3_ */