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