1 /*
2 * jdphuff.c
3 *
4 * Copyright (C) 1995-1997, Thomas G. Lane.
5 * This file is part of the Independent JPEG Group's software.
6 * For conditions of distribution and use, see the accompanying README file.
7 *
8 * This file contains Huffman entropy decoding routines for progressive JPEG.
9 *
10 * Much of the complexity here has to do with supporting input suspension.
11 * If the data source module demands suspension, we want to be able to back
12 * up to the start of the current MCU. To do this, we copy state variables
13 * into local working storage, and update them back to the permanent
14 * storage only upon successful completion of an MCU.
15 */
16
17 #define JPEG_INTERNALS
18 #include "jinclude.h"
19 #include "jpeglib.h"
20 #include "jdhuff.h" /* Declarations shared with jdhuff.c */
21
22
23 #ifdef D_PROGRESSIVE_SUPPORTED
24
25 /*
26 * Expanded entropy decoder object for progressive Huffman decoding.
27 *
28 * The savable_state subrecord contains fields that change within an MCU,
29 * but must not be updated permanently until we complete the MCU.
30 */
31
32 typedef struct {
33 unsigned int EOBRUN; /* remaining EOBs in EOBRUN */
34 int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
35 } savable_state;
36
37 /* This macro is to work around compilers with missing or broken
38 * structure assignment. You'll need to fix this code if you have
39 * such a compiler and you change MAX_COMPS_IN_SCAN.
40 */
41
42 #ifndef NO_STRUCT_ASSIGN
43 #define ASSIGN_STATE(dest,src) ((dest) = (src))
44 #else
45 #if MAX_COMPS_IN_SCAN == 4
46 #define ASSIGN_STATE(dest,src) \
47 ((dest).EOBRUN = (src).EOBRUN, \
48 (dest).last_dc_val[0] = (src).last_dc_val[0], \
49 (dest).last_dc_val[1] = (src).last_dc_val[1], \
50 (dest).last_dc_val[2] = (src).last_dc_val[2], \
51 (dest).last_dc_val[3] = (src).last_dc_val[3])
52 #endif
53 #endif
54
55
56 typedef struct {
57 struct jpeg_entropy_decoder pub; /* public fields */
58
59 /* These fields are loaded into local variables at start of each MCU.
60 * In case of suspension, we exit WITHOUT updating them.
61 */
62 bitread_perm_state bitstate; /* Bit buffer at start of MCU */
63 savable_state saved; /* Other state at start of MCU */
64
65 /* These fields are NOT loaded into local working state. */
66 unsigned int restarts_to_go; /* MCUs left in this restart interval */
67
68 /* Pointers to derived tables (these workspaces have image lifespan) */
69 d_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
70
71 d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */
72 } phuff_entropy_decoder;
73
74 typedef phuff_entropy_decoder * phuff_entropy_ptr;
75
76 /* Forward declarations */
77 METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo,
78 JBLOCKROW *MCU_data));
79 METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo,
80 JBLOCKROW *MCU_data));
81 METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo,
82 JBLOCKROW *MCU_data));
83 METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo,
84 JBLOCKROW *MCU_data));
85 GLOBAL(void) jpeg_configure_huffman_decoder_progressive(
86 j_decompress_ptr cinfo, huffman_offset_data offset);
87 GLOBAL(void) jpeg_get_huffman_decoder_configuration_progressive(
88 j_decompress_ptr cinfo, huffman_offset_data *offset);
89
90 /*
91 * Initialize for a Huffman-compressed scan.
92 */
93
94 METHODDEF(void)
start_pass_phuff_decoder(j_decompress_ptr cinfo)95 start_pass_phuff_decoder (j_decompress_ptr cinfo)
96 {
97 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
98 boolean is_DC_band, bad;
99 int ci, coefi, tbl;
100 int *coef_bit_ptr;
101 jpeg_component_info * compptr;
102
103 is_DC_band = (cinfo->Ss == 0);
104
105 /* Validate scan parameters */
106 bad = FALSE;
107 if (is_DC_band) {
108 if (cinfo->Se != 0)
109 bad = TRUE;
110 } else {
111 /* need not check Ss/Se < 0 since they came from unsigned bytes */
112 if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
113 bad = TRUE;
114 /* AC scans may have only one component */
115 if (cinfo->comps_in_scan != 1)
116 bad = TRUE;
117 }
118 if (cinfo->Ah != 0) {
119 /* Successive approximation refinement scan: must have Al = Ah-1. */
120 if (cinfo->Al != cinfo->Ah-1)
121 bad = TRUE;
122 }
123 if (cinfo->Al > 13) /* need not check for < 0 */
124 bad = TRUE;
125 /* Arguably the maximum Al value should be less than 13 for 8-bit precision,
126 * but the spec doesn't say so, and we try to be liberal about what we
127 * accept. Note: large Al values could result in out-of-range DC
128 * coefficients during early scans, leading to bizarre displays due to
129 * overflows in the IDCT math. But we won't crash.
130 */
131 if (bad)
132 ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
133 cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
134 /* Update progression status, and verify that scan order is legal.
135 * Note that inter-scan inconsistencies are treated as warnings
136 * not fatal errors ... not clear if this is right way to behave.
137 */
138 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
139 int cindex = cinfo->cur_comp_info[ci]->component_index;
140 coef_bit_ptr = & cinfo->coef_bits[cindex][0];
141 if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
142 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
143 for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
144 int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
145 if (cinfo->Ah != expected)
146 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
147 coef_bit_ptr[coefi] = cinfo->Al;
148 }
149 }
150
151 /* Select MCU decoding routine */
152 if (cinfo->Ah == 0) {
153 if (is_DC_band)
154 entropy->pub.decode_mcu = decode_mcu_DC_first;
155 else
156 entropy->pub.decode_mcu = decode_mcu_AC_first;
157 } else {
158 if (is_DC_band)
159 entropy->pub.decode_mcu = decode_mcu_DC_refine;
160 else
161 entropy->pub.decode_mcu = decode_mcu_AC_refine;
162 }
163
164 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
165 compptr = cinfo->cur_comp_info[ci];
166 /* Make sure requested tables are present, and compute derived tables.
167 * We may build same derived table more than once, but it's not expensive.
168 */
169 if (is_DC_band) {
170 if (cinfo->Ah == 0) { /* DC refinement needs no table */
171 tbl = compptr->dc_tbl_no;
172 jpeg_make_d_derived_tbl(cinfo, TRUE, tbl,
173 & entropy->derived_tbls[tbl]);
174 }
175 } else {
176 tbl = compptr->ac_tbl_no;
177 jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
178 & entropy->derived_tbls[tbl]);
179 /* remember the single active table */
180 entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
181 }
182 /* Initialize DC predictions to 0 */
183 entropy->saved.last_dc_val[ci] = 0;
184 }
185
186 /* Initialize bitread state variables */
187 entropy->bitstate.bits_left = 0;
188 entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
189 entropy->pub.insufficient_data = FALSE;
190
191 /* Initialize private state variables */
192 entropy->saved.EOBRUN = 0;
193
194 /* Initialize restart counter */
195 entropy->restarts_to_go = cinfo->restart_interval;
196 }
197
198
199 /*
200 * Figure F.12: extend sign bit.
201 * On some machines, a shift and add will be faster than a table lookup.
202 */
203
204 #ifdef AVOID_TABLES
205
206 #define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))
207
208 #else
209
210 #define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
211
212 static const int extend_test[16] = /* entry n is 2**(n-1) */
213 { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
214 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
215
216 static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
217 { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
218 ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
219 ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
220 ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
221
222 #endif /* AVOID_TABLES */
223
224
225 /*
226 * Check for a restart marker & resynchronize decoder.
227 * Returns FALSE if must suspend.
228 */
229
230 LOCAL(boolean)
process_restart(j_decompress_ptr cinfo)231 process_restart (j_decompress_ptr cinfo)
232 {
233 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
234 int ci;
235
236 /* Throw away any unused bits remaining in bit buffer; */
237 /* include any full bytes in next_marker's count of discarded bytes */
238 cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
239 entropy->bitstate.bits_left = 0;
240
241 /* Advance past the RSTn marker */
242 if (! (*cinfo->marker->read_restart_marker) (cinfo))
243 return FALSE;
244
245 /* Re-initialize DC predictions to 0 */
246 for (ci = 0; ci < cinfo->comps_in_scan; ci++)
247 entropy->saved.last_dc_val[ci] = 0;
248 /* Re-init EOB run count, too */
249 entropy->saved.EOBRUN = 0;
250
251 /* Reset restart counter */
252 entropy->restarts_to_go = cinfo->restart_interval;
253
254 /* Reset out-of-data flag, unless read_restart_marker left us smack up
255 * against a marker. In that case we will end up treating the next data
256 * segment as empty, and we can avoid producing bogus output pixels by
257 * leaving the flag set.
258 */
259 if (cinfo->unread_marker == 0)
260 entropy->pub.insufficient_data = FALSE;
261
262 return TRUE;
263 }
264
265
266 /*
267 * Huffman MCU decoding.
268 * Each of these routines decodes and returns one MCU's worth of
269 * Huffman-compressed coefficients.
270 * The coefficients are reordered from zigzag order into natural array order,
271 * but are not dequantized.
272 *
273 * The i'th block of the MCU is stored into the block pointed to by
274 * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
275 *
276 * We return FALSE if data source requested suspension. In that case no
277 * changes have been made to permanent state. (Exception: some output
278 * coefficients may already have been assigned. This is harmless for
279 * spectral selection, since we'll just re-assign them on the next call.
280 * Successive approximation AC refinement has to be more careful, however.)
281 */
282
283 /*
284 * MCU decoding for DC initial scan (either spectral selection,
285 * or first pass of successive approximation).
286 */
287
288 METHODDEF(boolean)
decode_mcu_DC_first(j_decompress_ptr cinfo,JBLOCKROW * MCU_data)289 decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
290 {
291 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
292 int Al = cinfo->Al;
293 register int s, r;
294 int blkn, ci;
295 JBLOCKROW block;
296 BITREAD_STATE_VARS;
297 savable_state state;
298 d_derived_tbl * tbl;
299 jpeg_component_info * compptr;
300
301 /* Process restart marker if needed; may have to suspend */
302 if (cinfo->restart_interval) {
303 if (entropy->restarts_to_go == 0)
304 if (! process_restart(cinfo))
305 return FALSE;
306 }
307
308 /* If we've run out of data, just leave the MCU set to zeroes.
309 * This way, we return uniform gray for the remainder of the segment.
310 */
311 if (! entropy->pub.insufficient_data) {
312
313 /* Load up working state */
314 BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
315 ASSIGN_STATE(state, entropy->saved);
316
317 /* Outer loop handles each block in the MCU */
318
319 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
320 block = MCU_data[blkn];
321 ci = cinfo->MCU_membership[blkn];
322 compptr = cinfo->cur_comp_info[ci];
323 tbl = entropy->derived_tbls[compptr->dc_tbl_no];
324
325 /* Decode a single block's worth of coefficients */
326
327 /* Section F.2.2.1: decode the DC coefficient difference */
328 HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
329 if (s) {
330 CHECK_BIT_BUFFER(br_state, s, return FALSE);
331 r = GET_BITS(s);
332 s = HUFF_EXTEND(r, s);
333 }
334
335 /* Convert DC difference to actual value, update last_dc_val */
336 s += state.last_dc_val[ci];
337 state.last_dc_val[ci] = s;
338 /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
339 (*block)[0] = (JCOEF) (s << Al);
340 }
341
342 /* Completed MCU, so update state */
343 BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
344 ASSIGN_STATE(entropy->saved, state);
345 }
346
347 /* Account for restart interval (no-op if not using restarts) */
348 entropy->restarts_to_go--;
349
350 return TRUE;
351 }
352
353
354 /*
355 * MCU decoding for AC initial scan (either spectral selection,
356 * or first pass of successive approximation).
357 */
358
359 METHODDEF(boolean)
decode_mcu_AC_first(j_decompress_ptr cinfo,JBLOCKROW * MCU_data)360 decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
361 {
362 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
363 int Se = cinfo->Se;
364 int Al = cinfo->Al;
365 register int s, k, r;
366 unsigned int EOBRUN;
367 JBLOCKROW block;
368 BITREAD_STATE_VARS;
369 d_derived_tbl * tbl;
370
371 /* Process restart marker if needed; may have to suspend */
372 if (cinfo->restart_interval) {
373 if (entropy->restarts_to_go == 0)
374 if (! process_restart(cinfo))
375 return FALSE;
376 }
377
378 /* If we've run out of data, just leave the MCU set to zeroes.
379 * This way, we return uniform gray for the remainder of the segment.
380 */
381 if (! entropy->pub.insufficient_data) {
382
383 /* Load up working state.
384 * We can avoid loading/saving bitread state if in an EOB run.
385 */
386 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
387
388 /* There is always only one block per MCU */
389
390 if (EOBRUN > 0) /* if it's a band of zeroes... */
391 EOBRUN--; /* ...process it now (we do nothing) */
392 else {
393 BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
394 block = MCU_data[0];
395 tbl = entropy->ac_derived_tbl;
396
397 for (k = cinfo->Ss; k <= Se; k++) {
398 HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
399 r = s >> 4;
400 s &= 15;
401 if (s) {
402 k += r;
403 CHECK_BIT_BUFFER(br_state, s, return FALSE);
404 r = GET_BITS(s);
405 s = HUFF_EXTEND(r, s);
406 /* Scale and output coefficient in natural (dezigzagged) order */
407 (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al);
408 } else {
409 if (r == 15) { /* ZRL */
410 k += 15; /* skip 15 zeroes in band */
411 } else { /* EOBr, run length is 2^r + appended bits */
412 EOBRUN = 1 << r;
413 if (r) { /* EOBr, r > 0 */
414 CHECK_BIT_BUFFER(br_state, r, return FALSE);
415 r = GET_BITS(r);
416 EOBRUN += r;
417 }
418 EOBRUN--; /* this band is processed at this moment */
419 break; /* force end-of-band */
420 }
421 }
422 }
423
424 BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
425 }
426
427 /* Completed MCU, so update state */
428 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
429 }
430
431 /* Account for restart interval (no-op if not using restarts) */
432 entropy->restarts_to_go--;
433
434 return TRUE;
435 }
436
437
438 /*
439 * MCU decoding for DC successive approximation refinement scan.
440 * Note: we assume such scans can be multi-component, although the spec
441 * is not very clear on the point.
442 */
443
444 METHODDEF(boolean)
decode_mcu_DC_refine(j_decompress_ptr cinfo,JBLOCKROW * MCU_data)445 decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
446 {
447 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
448 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
449 int blkn;
450 JBLOCKROW block;
451 BITREAD_STATE_VARS;
452
453 /* Process restart marker if needed; may have to suspend */
454 if (cinfo->restart_interval) {
455 if (entropy->restarts_to_go == 0)
456 if (! process_restart(cinfo))
457 return FALSE;
458 }
459
460 /* Not worth the cycles to check insufficient_data here,
461 * since we will not change the data anyway if we read zeroes.
462 */
463
464 /* Load up working state */
465 BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
466
467 /* Outer loop handles each block in the MCU */
468
469 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
470 block = MCU_data[blkn];
471
472 /* Encoded data is simply the next bit of the two's-complement DC value */
473 CHECK_BIT_BUFFER(br_state, 1, return FALSE);
474 if (GET_BITS(1))
475 (*block)[0] |= p1;
476 /* Note: since we use |=, repeating the assignment later is safe */
477 }
478
479 /* Completed MCU, so update state */
480 BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
481
482 /* Account for restart interval (no-op if not using restarts) */
483 entropy->restarts_to_go--;
484
485 return TRUE;
486 }
487
488
489 /*
490 * MCU decoding for AC successive approximation refinement scan.
491 */
492
493 METHODDEF(boolean)
decode_mcu_AC_refine(j_decompress_ptr cinfo,JBLOCKROW * MCU_data)494 decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
495 {
496 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
497 int Se = cinfo->Se;
498 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
499 int m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */
500 register int s, k, r;
501 unsigned int EOBRUN;
502 JBLOCKROW block;
503 JCOEFPTR thiscoef;
504 BITREAD_STATE_VARS;
505 d_derived_tbl * tbl;
506 int num_newnz;
507 int newnz_pos[DCTSIZE2];
508
509 /* Process restart marker if needed; may have to suspend */
510 if (cinfo->restart_interval) {
511 if (entropy->restarts_to_go == 0)
512 if (! process_restart(cinfo))
513 return FALSE;
514 }
515
516 /* If we've run out of data, don't modify the MCU.
517 */
518 if (! entropy->pub.insufficient_data) {
519
520 /* Load up working state */
521 BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
522 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
523
524 /* There is always only one block per MCU */
525 block = MCU_data[0];
526 tbl = entropy->ac_derived_tbl;
527
528 /* If we are forced to suspend, we must undo the assignments to any newly
529 * nonzero coefficients in the block, because otherwise we'd get confused
530 * next time about which coefficients were already nonzero.
531 * But we need not undo addition of bits to already-nonzero coefficients;
532 * instead, we can test the current bit to see if we already did it.
533 */
534 num_newnz = 0;
535
536 /* initialize coefficient loop counter to start of band */
537 k = cinfo->Ss;
538
539 if (EOBRUN == 0) {
540 for (; k <= Se; k++) {
541 HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
542 r = s >> 4;
543 s &= 15;
544 if (s) {
545 if (s != 1) /* size of new coef should always be 1 */
546 WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
547 CHECK_BIT_BUFFER(br_state, 1, goto undoit);
548 if (GET_BITS(1))
549 s = p1; /* newly nonzero coef is positive */
550 else
551 s = m1; /* newly nonzero coef is negative */
552 } else {
553 if (r != 15) {
554 EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */
555 if (r) {
556 CHECK_BIT_BUFFER(br_state, r, goto undoit);
557 r = GET_BITS(r);
558 EOBRUN += r;
559 }
560 break; /* rest of block is handled by EOB logic */
561 }
562 /* note s = 0 for processing ZRL */
563 }
564 /* Advance over already-nonzero coefs and r still-zero coefs,
565 * appending correction bits to the nonzeroes. A correction bit is 1
566 * if the absolute value of the coefficient must be increased.
567 */
568 do {
569 thiscoef = *block + jpeg_natural_order[k];
570 if (*thiscoef != 0) {
571 CHECK_BIT_BUFFER(br_state, 1, goto undoit);
572 if (GET_BITS(1)) {
573 if ((*thiscoef & p1) == 0) { /* do nothing if already set it */
574 if (*thiscoef >= 0)
575 *thiscoef += p1;
576 else
577 *thiscoef += m1;
578 }
579 }
580 } else {
581 if (--r < 0)
582 break; /* reached target zero coefficient */
583 }
584 k++;
585 } while (k <= Se);
586 if (s) {
587 int pos = jpeg_natural_order[k];
588 /* Output newly nonzero coefficient */
589 (*block)[pos] = (JCOEF) s;
590 /* Remember its position in case we have to suspend */
591 newnz_pos[num_newnz++] = pos;
592 }
593 }
594 }
595
596 if (EOBRUN > 0) {
597 /* Scan any remaining coefficient positions after the end-of-band
598 * (the last newly nonzero coefficient, if any). Append a correction
599 * bit to each already-nonzero coefficient. A correction bit is 1
600 * if the absolute value of the coefficient must be increased.
601 */
602 for (; k <= Se; k++) {
603 thiscoef = *block + jpeg_natural_order[k];
604 if (*thiscoef != 0) {
605 CHECK_BIT_BUFFER(br_state, 1, goto undoit);
606 if (GET_BITS(1)) {
607 if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
608 if (*thiscoef >= 0)
609 *thiscoef += p1;
610 else
611 *thiscoef += m1;
612 }
613 }
614 }
615 }
616 /* Count one block completed in EOB run */
617 EOBRUN--;
618 }
619
620 /* Completed MCU, so update state */
621 BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
622 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
623 }
624
625 /* Account for restart interval (no-op if not using restarts) */
626 entropy->restarts_to_go--;
627
628 return TRUE;
629
630 undoit:
631 /* Re-zero any output coefficients that we made newly nonzero */
632 while (num_newnz > 0)
633 (*block)[newnz_pos[--num_newnz]] = 0;
634
635 return FALSE;
636 }
637
638 /*
639 * Save the current Huffman deocde position and the DC coefficients
640 * for each component into bitstream_offset and dc_info[], respectively.
641 */
642 METHODDEF(void)
get_huffman_decoder_configuration(j_decompress_ptr cinfo,huffman_offset_data * offset)643 get_huffman_decoder_configuration(j_decompress_ptr cinfo,
644 huffman_offset_data *offset)
645 {
646 int i;
647 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
648 jpeg_get_huffman_decoder_configuration_progressive(cinfo, offset);
649 offset->EOBRUN = entropy->saved.EOBRUN;
650 for (i = 0; i < cinfo->comps_in_scan; i++)
651 offset->prev_dc[i] = entropy->saved.last_dc_val[i];
652 }
653
654
655 /*
656 * Save the current Huffman decoder position and the bit buffer
657 * into bitstream_offset and get_buffer, respectively.
658 */
659 GLOBAL(void)
jpeg_get_huffman_decoder_configuration_progressive(j_decompress_ptr cinfo,huffman_offset_data * offset)660 jpeg_get_huffman_decoder_configuration_progressive(j_decompress_ptr cinfo,
661 huffman_offset_data *offset)
662 {
663 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
664
665 if (cinfo->restart_interval) {
666 // We are at the end of a data segment
667 if (entropy->restarts_to_go == 0)
668 if (! process_restart(cinfo))
669 return;
670 }
671
672 // Save restarts_to_go and next_restart_num.
673 offset->restarts_to_go = (unsigned short) entropy->restarts_to_go;
674 offset->next_restart_num = cinfo->marker->next_restart_num;
675
676 offset->bitstream_offset =
677 (jget_input_stream_position(cinfo) << LOG_TWO_BIT_BUF_SIZE)
678 + entropy->bitstate.bits_left;
679
680 offset->get_buffer = entropy->bitstate.get_buffer;
681 }
682
683
684 /*
685 * Configure the Huffman decoder to decode the image
686 * starting from (iMCU_row_offset, iMCU_col_offset).
687 */
688 METHODDEF(void)
configure_huffman_decoder(j_decompress_ptr cinfo,huffman_offset_data offset)689 configure_huffman_decoder(j_decompress_ptr cinfo, huffman_offset_data offset)
690 {
691 int i;
692 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
693 jpeg_configure_huffman_decoder_progressive(cinfo, offset);
694 entropy->saved.EOBRUN = offset.EOBRUN;
695 for (i = 0; i < cinfo->comps_in_scan; i++)
696 entropy->saved.last_dc_val[i] = offset.prev_dc[i];
697 }
698
699 /*
700 * Configure the Huffman decoder reader position and bit buffer.
701 */
702 GLOBAL(void)
jpeg_configure_huffman_decoder_progressive(j_decompress_ptr cinfo,huffman_offset_data offset)703 jpeg_configure_huffman_decoder_progressive(j_decompress_ptr cinfo,
704 huffman_offset_data offset)
705 {
706 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
707
708 // Restore restarts_to_go and next_restart_num
709 cinfo->unread_marker = 0;
710 entropy->restarts_to_go = offset.restarts_to_go;
711 cinfo->marker->next_restart_num = offset.next_restart_num;
712
713 unsigned int bitstream_offset = offset.bitstream_offset;
714 int blkn, i;
715
716 unsigned int byte_offset = bitstream_offset >> LOG_TWO_BIT_BUF_SIZE;
717 unsigned int bit_in_bit_buffer =
718 bitstream_offset & ((1 << LOG_TWO_BIT_BUF_SIZE) - 1);
719
720 jset_input_stream_position_bit(cinfo, byte_offset,
721 bit_in_bit_buffer, offset.get_buffer);
722 }
723
724 GLOBAL(void)
jpeg_configure_huffman_index_scan(j_decompress_ptr cinfo,huffman_index * index,int scan_no,int offset)725 jpeg_configure_huffman_index_scan(j_decompress_ptr cinfo,
726 huffman_index *index, int scan_no, int offset)
727 {
728 phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
729 if (scan_no >= index->scan_count) {
730 index->scan = realloc(index->scan,
731 (scan_no + 1) * sizeof(huffman_scan_header));
732 index->mem_used += (scan_no - index->scan_count + 1)
733 * (sizeof(huffman_scan_header) + cinfo->total_iMCU_rows
734 * sizeof(huffman_offset_data*));
735 index->scan_count = scan_no + 1;
736 }
737 index->scan[scan_no].offset = (huffman_offset_data**)malloc(
738 cinfo->total_iMCU_rows * sizeof(huffman_offset_data*));
739 index->scan[scan_no].bitstream_offset = offset;
740 }
741
742 /*
743 * Module initialization routine for progressive Huffman entropy decoding.
744 */
745 GLOBAL(void)
jinit_phuff_decoder(j_decompress_ptr cinfo)746 jinit_phuff_decoder (j_decompress_ptr cinfo)
747 {
748 phuff_entropy_ptr entropy;
749 int *coef_bit_ptr;
750 int ci, i;
751
752 entropy = (phuff_entropy_ptr)
753 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
754 SIZEOF(phuff_entropy_decoder));
755 cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
756 entropy->pub.start_pass = start_pass_phuff_decoder;
757 entropy->pub.configure_huffman_decoder = configure_huffman_decoder;
758 entropy->pub.get_huffman_decoder_configuration =
759 get_huffman_decoder_configuration;
760
761 /* Mark derived tables unallocated */
762 for (i = 0; i < NUM_HUFF_TBLS; i++) {
763 entropy->derived_tbls[i] = NULL;
764 }
765
766 /* Create progression status table */
767 cinfo->coef_bits = (int (*)[DCTSIZE2])
768 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
769 cinfo->num_components*DCTSIZE2*SIZEOF(int));
770 coef_bit_ptr = & cinfo->coef_bits[0][0];
771 for (ci = 0; ci < cinfo->num_components; ci++)
772 for (i = 0; i < DCTSIZE2; i++)
773 *coef_bit_ptr++ = -1;
774 }
775
776 #endif /* D_PROGRESSIVE_SUPPORTED */
777