1/*
2 * jdphuff.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1995-1997, Thomas G. Lane.
6 * libjpeg-turbo Modifications:
7 * Copyright (C) 2015-2016, 2018, D. R. Commander.
8 * For conditions of distribution and use, see the accompanying README.ijg
9 * file.
10 *
11 * This file contains Huffman entropy decoding routines for progressive JPEG.
12 *
13 * Much of the complexity here has to do with supporting input suspension.
14 * If the data source module demands suspension, we want to be able to back
15 * up to the start of the current MCU. To do this, we copy state variables
16 * into local working storage, and update them back to the permanent
17 * storage only upon successful completion of an MCU.
18 *
19 * NOTE: All referenced figures are from
20 * Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994.
21 */
22
23#define JPEG_INTERNALS
24#include "jinclude.h"
25#include "jpeglib.h"
26#include "jdhuff.h" /* Declarations shared with jdhuff.c */
27#include <limits.h>
28
29
30#ifdef D_PROGRESSIVE_SUPPORTED
31
32/*
33 * Expanded entropy decoder object for progressive Huffman decoding.
34 *
35 * The savable_state subrecord contains fields that change within an MCU,
36 * but must not be updated permanently until we complete the MCU.
37 */
38
39typedef struct {
40 unsigned int EOBRUN; /* remaining EOBs in EOBRUN */
41 int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
42} savable_state;
43
44/* This macro is to work around compilers with missing or broken
45 * structure assignment. You'll need to fix this code if you have
46 * such a compiler and you change MAX_COMPS_IN_SCAN.
47 */
48
49#ifndef NO_STRUCT_ASSIGN
50#define ASSIGN_STATE(dest, src) ((dest) = (src))
51#else
52#if MAX_COMPS_IN_SCAN == 4
53#define ASSIGN_STATE(dest, src) \
54 ((dest).EOBRUN = (src).EOBRUN, \
55 (dest).last_dc_val[0] = (src).last_dc_val[0], \
56 (dest).last_dc_val[1] = (src).last_dc_val[1], \
57 (dest).last_dc_val[2] = (src).last_dc_val[2], \
58 (dest).last_dc_val[3] = (src).last_dc_val[3])
59#endif
60#endif
61
62
63typedef struct {
64 struct jpeg_entropy_decoder pub; /* public fields */
65
66 /* These fields are loaded into local variables at start of each MCU.
67 * In case of suspension, we exit WITHOUT updating them.
68 */
69 bitread_perm_state bitstate; /* Bit buffer at start of MCU */
70 savable_state saved; /* Other state at start of MCU */
71
72 /* These fields are NOT loaded into local working state. */
73 unsigned int restarts_to_go; /* MCUs left in this restart interval */
74
75 /* Pointers to derived tables (these workspaces have image lifespan) */
76 d_derived_tbl *derived_tbls[NUM_HUFF_TBLS];
77
78 d_derived_tbl *ac_derived_tbl; /* active table during an AC scan */
79} phuff_entropy_decoder;
80
81typedef phuff_entropy_decoder *phuff_entropy_ptr;
82
83/* Forward declarations */
84METHODDEF(boolean) decode_mcu_DC_first(j_decompress_ptr cinfo,
85 JBLOCKROW *MCU_data);
86METHODDEF(boolean) decode_mcu_AC_first(j_decompress_ptr cinfo,
87 JBLOCKROW *MCU_data);
88METHODDEF(boolean) decode_mcu_DC_refine(j_decompress_ptr cinfo,
89 JBLOCKROW *MCU_data);
90METHODDEF(boolean) decode_mcu_AC_refine(j_decompress_ptr cinfo,
91 JBLOCKROW *MCU_data);
92
93
94/*
95 * Initialize for a Huffman-compressed scan.
96 */
97
98METHODDEF(void)
99start_pass_phuff_decoder(j_decompress_ptr cinfo)
100{
101 phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
102 boolean is_DC_band, bad;
103 int ci, coefi, tbl;
104 d_derived_tbl **pdtbl;
105 int *coef_bit_ptr;
106 jpeg_component_info *compptr;
107
108 is_DC_band = (cinfo->Ss == 0);
109
110 /* Validate scan parameters */
111 bad = FALSE;
112 if (is_DC_band) {
113 if (cinfo->Se != 0)
114 bad = TRUE;
115 } else {
116 /* need not check Ss/Se < 0 since they came from unsigned bytes */
117 if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
118 bad = TRUE;
119 /* AC scans may have only one component */
120 if (cinfo->comps_in_scan != 1)
121 bad = TRUE;
122 }
123 if (cinfo->Ah != 0) {
124 /* Successive approximation refinement scan: must have Al = Ah-1. */
125 if (cinfo->Al != cinfo->Ah - 1)
126 bad = TRUE;
127 }
128 if (cinfo->Al > 13) /* need not check for < 0 */
129 bad = TRUE;
130 /* Arguably the maximum Al value should be less than 13 for 8-bit precision,
131 * but the spec doesn't say so, and we try to be liberal about what we
132 * accept. Note: large Al values could result in out-of-range DC
133 * coefficients during early scans, leading to bizarre displays due to
134 * overflows in the IDCT math. But we won't crash.
135 */
136 if (bad)
137 ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
138 cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
139 /* Update progression status, and verify that scan order is legal.
140 * Note that inter-scan inconsistencies are treated as warnings
141 * not fatal errors ... not clear if this is right way to behave.
142 */
143 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
144 int cindex = cinfo->cur_comp_info[ci]->component_index;
145 coef_bit_ptr = &cinfo->coef_bits[cindex][0];
146 if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
147 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
148 for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
149 int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
150 if (cinfo->Ah != expected)
151 WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
152 coef_bit_ptr[coefi] = cinfo->Al;
153 }
154 }
155
156 /* Select MCU decoding routine */
157 if (cinfo->Ah == 0) {
158 if (is_DC_band)
159 entropy->pub.decode_mcu = decode_mcu_DC_first;
160 else
161 entropy->pub.decode_mcu = decode_mcu_AC_first;
162 } else {
163 if (is_DC_band)
164 entropy->pub.decode_mcu = decode_mcu_DC_refine;
165 else
166 entropy->pub.decode_mcu = decode_mcu_AC_refine;
167 }
168
169 for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
170 compptr = cinfo->cur_comp_info[ci];
171 /* Make sure requested tables are present, and compute derived tables.
172 * We may build same derived table more than once, but it's not expensive.
173 */
174 if (is_DC_band) {
175 if (cinfo->Ah == 0) { /* DC refinement needs no table */
176 tbl = compptr->dc_tbl_no;
177 pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl;
178 jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, pdtbl);
179 }
180 } else {
181 tbl = compptr->ac_tbl_no;
182 pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl;
183 jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, pdtbl);
184 /* remember the single active table */
185 entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
186 }
187 /* Initialize DC predictions to 0 */
188 entropy->saved.last_dc_val[ci] = 0;
189 }
190
191 /* Initialize bitread state variables */
192 entropy->bitstate.bits_left = 0;
193 entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
194 entropy->pub.insufficient_data = FALSE;
195
196 /* Initialize private state variables */
197 entropy->saved.EOBRUN = 0;
198
199 /* Initialize restart counter */
200 entropy->restarts_to_go = cinfo->restart_interval;
201}
202
203
204/*
205 * Figure F.12: extend sign bit.
206 * On some machines, a shift and add will be faster than a table lookup.
207 */
208
209#define AVOID_TABLES
210#ifdef AVOID_TABLES
211
212#define NEG_1 ((unsigned)-1)
213#define HUFF_EXTEND(x, s) \
214 ((x) < (1 << ((s) - 1)) ? (x) + (((NEG_1) << (s)) + 1) : (x))
215
216#else
217
218#define HUFF_EXTEND(x, s) \
219 ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
220
221static const int extend_test[16] = { /* entry n is 2**(n-1) */
222 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
223 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000
224};
225
226static const int extend_offset[16] = { /* entry n is (-1 << n) + 1 */
227 0, ((-1) << 1) + 1, ((-1) << 2) + 1, ((-1) << 3) + 1, ((-1) << 4) + 1,
228 ((-1) << 5) + 1, ((-1) << 6) + 1, ((-1) << 7) + 1, ((-1) << 8) + 1,
229 ((-1) << 9) + 1, ((-1) << 10) + 1, ((-1) << 11) + 1, ((-1) << 12) + 1,
230 ((-1) << 13) + 1, ((-1) << 14) + 1, ((-1) << 15) + 1
231};
232
233#endif /* AVOID_TABLES */
234
235
236/*
237 * Check for a restart marker & resynchronize decoder.
238 * Returns FALSE if must suspend.
239 */
240
241LOCAL(boolean)
242process_restart(j_decompress_ptr cinfo)
243{
244 phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
245 int ci;
246
247 /* Throw away any unused bits remaining in bit buffer; */
248 /* include any full bytes in next_marker's count of discarded bytes */
249 cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
250 entropy->bitstate.bits_left = 0;
251
252 /* Advance past the RSTn marker */
253 if (!(*cinfo->marker->read_restart_marker) (cinfo))
254 return FALSE;
255
256 /* Re-initialize DC predictions to 0 */
257 for (ci = 0; ci < cinfo->comps_in_scan; ci++)
258 entropy->saved.last_dc_val[ci] = 0;
259 /* Re-init EOB run count, too */
260 entropy->saved.EOBRUN = 0;
261
262 /* Reset restart counter */
263 entropy->restarts_to_go = cinfo->restart_interval;
264
265 /* Reset out-of-data flag, unless read_restart_marker left us smack up
266 * against a marker. In that case we will end up treating the next data
267 * segment as empty, and we can avoid producing bogus output pixels by
268 * leaving the flag set.
269 */
270 if (cinfo->unread_marker == 0)
271 entropy->pub.insufficient_data = FALSE;
272
273 return TRUE;
274}
275
276
277/*
278 * Huffman MCU decoding.
279 * Each of these routines decodes and returns one MCU's worth of
280 * Huffman-compressed coefficients.
281 * The coefficients are reordered from zigzag order into natural array order,
282 * but are not dequantized.
283 *
284 * The i'th block of the MCU is stored into the block pointed to by
285 * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
286 *
287 * We return FALSE if data source requested suspension. In that case no
288 * changes have been made to permanent state. (Exception: some output
289 * coefficients may already have been assigned. This is harmless for
290 * spectral selection, since we'll just re-assign them on the next call.
291 * Successive approximation AC refinement has to be more careful, however.)
292 */
293
294/*
295 * MCU decoding for DC initial scan (either spectral selection,
296 * or first pass of successive approximation).
297 */
298
299METHODDEF(boolean)
300decode_mcu_DC_first(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
301{
302 phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
303 int Al = cinfo->Al;
304 register int s, r;
305 int blkn, ci;
306 JBLOCKROW block;
307 BITREAD_STATE_VARS;
308 savable_state state;
309 d_derived_tbl *tbl;
310 jpeg_component_info *compptr;
311
312 /* Process restart marker if needed; may have to suspend */
313 if (cinfo->restart_interval) {
314 if (entropy->restarts_to_go == 0)
315 if (!process_restart(cinfo))
316 return FALSE;
317 }
318
319 /* If we've run out of data, just leave the MCU set to zeroes.
320 * This way, we return uniform gray for the remainder of the segment.
321 */
322 if (!entropy->pub.insufficient_data) {
323
324 /* Load up working state */
325 BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
326 ASSIGN_STATE(state, entropy->saved);
327
328 /* Outer loop handles each block in the MCU */
329
330 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
331 block = MCU_data[blkn];
332 ci = cinfo->MCU_membership[blkn];
333 compptr = cinfo->cur_comp_info[ci];
334 tbl = entropy->derived_tbls[compptr->dc_tbl_no];
335
336 /* Decode a single block's worth of coefficients */
337
338 /* Section F.2.2.1: decode the DC coefficient difference */
339 HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
340 if (s) {
341 CHECK_BIT_BUFFER(br_state, s, return FALSE);
342 r = GET_BITS(s);
343 s = HUFF_EXTEND(r, s);
344 }
345
346 /* Convert DC difference to actual value, update last_dc_val */
347 if ((state.last_dc_val[ci] >= 0 &&
348 s > INT_MAX - state.last_dc_val[ci]) ||
349 (state.last_dc_val[ci] < 0 && s < INT_MIN - state.last_dc_val[ci]))
350 ERREXIT(cinfo, JERR_BAD_DCT_COEF);
351 s += state.last_dc_val[ci];
352 state.last_dc_val[ci] = s;
353 /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
354 (*block)[0] = (JCOEF)LEFT_SHIFT(s, Al);
355 }
356
357 /* Completed MCU, so update state */
358 BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
359 ASSIGN_STATE(entropy->saved, state);
360 }
361
362 /* Account for restart interval (no-op if not using restarts) */
363 entropy->restarts_to_go--;
364
365 return TRUE;
366}
367
368
369/*
370 * MCU decoding for AC initial scan (either spectral selection,
371 * or first pass of successive approximation).
372 */
373
374METHODDEF(boolean)
375decode_mcu_AC_first(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
376{
377 phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
378 int Se = cinfo->Se;
379 int Al = cinfo->Al;
380 register int s, k, r;
381 unsigned int EOBRUN;
382 JBLOCKROW block;
383 BITREAD_STATE_VARS;
384 d_derived_tbl *tbl;
385
386 /* Process restart marker if needed; may have to suspend */
387 if (cinfo->restart_interval) {
388 if (entropy->restarts_to_go == 0)
389 if (!process_restart(cinfo))
390 return FALSE;
391 }
392
393 /* If we've run out of data, just leave the MCU set to zeroes.
394 * This way, we return uniform gray for the remainder of the segment.
395 */
396 if (!entropy->pub.insufficient_data) {
397
398 /* Load up working state.
399 * We can avoid loading/saving bitread state if in an EOB run.
400 */
401 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
402
403 /* There is always only one block per MCU */
404
405 if (EOBRUN > 0) /* if it's a band of zeroes... */
406 EOBRUN--; /* ...process it now (we do nothing) */
407 else {
408 BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
409 block = MCU_data[0];
410 tbl = entropy->ac_derived_tbl;
411
412 for (k = cinfo->Ss; k <= Se; k++) {
413 HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
414 r = s >> 4;
415 s &= 15;
416 if (s) {
417 k += r;
418 CHECK_BIT_BUFFER(br_state, s, return FALSE);
419 r = GET_BITS(s);
420 s = HUFF_EXTEND(r, s);
421 /* Scale and output coefficient in natural (dezigzagged) order */
422 (*block)[jpeg_natural_order[k]] = (JCOEF)LEFT_SHIFT(s, Al);
423 } else {
424 if (r == 15) { /* ZRL */
425 k += 15; /* skip 15 zeroes in band */
426 } else { /* EOBr, run length is 2^r + appended bits */
427 EOBRUN = 1 << r;
428 if (r) { /* EOBr, r > 0 */
429 CHECK_BIT_BUFFER(br_state, r, return FALSE);
430 r = GET_BITS(r);
431 EOBRUN += r;
432 }
433 EOBRUN--; /* this band is processed at this moment */
434 break; /* force end-of-band */
435 }
436 }
437 }
438
439 BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
440 }
441
442 /* Completed MCU, so update state */
443 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
444 }
445
446 /* Account for restart interval (no-op if not using restarts) */
447 entropy->restarts_to_go--;
448
449 return TRUE;
450}
451
452
453/*
454 * MCU decoding for DC successive approximation refinement scan.
455 * Note: we assume such scans can be multi-component, although the spec
456 * is not very clear on the point.
457 */
458
459METHODDEF(boolean)
460decode_mcu_DC_refine(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
461{
462 phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
463 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
464 int blkn;
465 JBLOCKROW block;
466 BITREAD_STATE_VARS;
467
468 /* Process restart marker if needed; may have to suspend */
469 if (cinfo->restart_interval) {
470 if (entropy->restarts_to_go == 0)
471 if (!process_restart(cinfo))
472 return FALSE;
473 }
474
475 /* Not worth the cycles to check insufficient_data here,
476 * since we will not change the data anyway if we read zeroes.
477 */
478
479 /* Load up working state */
480 BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
481
482 /* Outer loop handles each block in the MCU */
483
484 for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
485 block = MCU_data[blkn];
486
487 /* Encoded data is simply the next bit of the two's-complement DC value */
488 CHECK_BIT_BUFFER(br_state, 1, return FALSE);
489 if (GET_BITS(1))
490 (*block)[0] |= p1;
491 /* Note: since we use |=, repeating the assignment later is safe */
492 }
493
494 /* Completed MCU, so update state */
495 BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
496
497 /* Account for restart interval (no-op if not using restarts) */
498 entropy->restarts_to_go--;
499
500 return TRUE;
501}
502
503
504/*
505 * MCU decoding for AC successive approximation refinement scan.
506 */
507
508METHODDEF(boolean)
509decode_mcu_AC_refine(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
510{
511 phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
512 int Se = cinfo->Se;
513 int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
514 int m1 = (NEG_1) << cinfo->Al; /* -1 in the bit position being coded */
515 register int s, k, r;
516 unsigned int EOBRUN;
517 JBLOCKROW block;
518 JCOEFPTR thiscoef;
519 BITREAD_STATE_VARS;
520 d_derived_tbl *tbl;
521 int num_newnz;
522 int newnz_pos[DCTSIZE2];
523
524 /* Process restart marker if needed; may have to suspend */
525 if (cinfo->restart_interval) {
526 if (entropy->restarts_to_go == 0)
527 if (!process_restart(cinfo))
528 return FALSE;
529 }
530
531 /* If we've run out of data, don't modify the MCU.
532 */
533 if (!entropy->pub.insufficient_data) {
534
535 /* Load up working state */
536 BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
537 EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
538
539 /* There is always only one block per MCU */
540 block = MCU_data[0];
541 tbl = entropy->ac_derived_tbl;
542
543 /* If we are forced to suspend, we must undo the assignments to any newly
544 * nonzero coefficients in the block, because otherwise we'd get confused
545 * next time about which coefficients were already nonzero.
546 * But we need not undo addition of bits to already-nonzero coefficients;
547 * instead, we can test the current bit to see if we already did it.
548 */
549 num_newnz = 0;
550
551 /* initialize coefficient loop counter to start of band */
552 k = cinfo->Ss;
553
554 if (EOBRUN == 0) {
555 for (; k <= Se; k++) {
556 HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
557 r = s >> 4;
558 s &= 15;
559 if (s) {
560 if (s != 1) /* size of new coef should always be 1 */
561 WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
562 CHECK_BIT_BUFFER(br_state, 1, goto undoit);
563 if (GET_BITS(1))
564 s = p1; /* newly nonzero coef is positive */
565 else
566 s = m1; /* newly nonzero coef is negative */
567 } else {
568 if (r != 15) {
569 EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */
570 if (r) {
571 CHECK_BIT_BUFFER(br_state, r, goto undoit);
572 r = GET_BITS(r);
573 EOBRUN += r;
574 }
575 break; /* rest of block is handled by EOB logic */
576 }
577 /* note s = 0 for processing ZRL */
578 }
579 /* Advance over already-nonzero coefs and r still-zero coefs,
580 * appending correction bits to the nonzeroes. A correction bit is 1
581 * if the absolute value of the coefficient must be increased.
582 */
583 do {
584 thiscoef = *block + jpeg_natural_order[k];
585 if (*thiscoef != 0) {
586 CHECK_BIT_BUFFER(br_state, 1, goto undoit);
587 if (GET_BITS(1)) {
588 if ((*thiscoef & p1) == 0) { /* do nothing if already set it */
589 if (*thiscoef >= 0)
590 *thiscoef += p1;
591 else
592 *thiscoef += m1;
593 }
594 }
595 } else {
596 if (--r < 0)
597 break; /* reached target zero coefficient */
598 }
599 k++;
600 } while (k <= Se);
601 if (s) {
602 int pos = jpeg_natural_order[k];
603 /* Output newly nonzero coefficient */
604 (*block)[pos] = (JCOEF)s;
605 /* Remember its position in case we have to suspend */
606 newnz_pos[num_newnz++] = pos;
607 }
608 }
609 }
610
611 if (EOBRUN > 0) {
612 /* Scan any remaining coefficient positions after the end-of-band
613 * (the last newly nonzero coefficient, if any). Append a correction
614 * bit to each already-nonzero coefficient. A correction bit is 1
615 * if the absolute value of the coefficient must be increased.
616 */
617 for (; k <= Se; k++) {
618 thiscoef = *block + jpeg_natural_order[k];
619 if (*thiscoef != 0) {
620 CHECK_BIT_BUFFER(br_state, 1, goto undoit);
621 if (GET_BITS(1)) {
622 if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
623 if (*thiscoef >= 0)
624 *thiscoef += p1;
625 else
626 *thiscoef += m1;
627 }
628 }
629 }
630 }
631 /* Count one block completed in EOB run */
632 EOBRUN--;
633 }
634
635 /* Completed MCU, so update state */
636 BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
637 entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
638 }
639
640 /* Account for restart interval (no-op if not using restarts) */
641 entropy->restarts_to_go--;
642
643 return TRUE;
644
645undoit:
646 /* Re-zero any output coefficients that we made newly nonzero */
647 while (num_newnz > 0)
648 (*block)[newnz_pos[--num_newnz]] = 0;
649
650 return FALSE;
651}
652
653
654/*
655 * Module initialization routine for progressive Huffman entropy decoding.
656 */
657
658GLOBAL(void)
659jinit_phuff_decoder(j_decompress_ptr cinfo)
660{
661 phuff_entropy_ptr entropy;
662 int *coef_bit_ptr;
663 int ci, i;
664
665 entropy = (phuff_entropy_ptr)
666 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
667 sizeof(phuff_entropy_decoder));
668 cinfo->entropy = (struct jpeg_entropy_decoder *)entropy;
669 entropy->pub.start_pass = start_pass_phuff_decoder;
670
671 /* Mark derived tables unallocated */
672 for (i = 0; i < NUM_HUFF_TBLS; i++) {
673 entropy->derived_tbls[i] = NULL;
674 }
675
676 /* Create progression status table */
677 cinfo->coef_bits = (int (*)[DCTSIZE2])
678 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
679 cinfo->num_components * DCTSIZE2 *
680 sizeof(int));
681 coef_bit_ptr = &cinfo->coef_bits[0][0];
682 for (ci = 0; ci < cinfo->num_components; ci++)
683 for (i = 0; i < DCTSIZE2; i++)
684 *coef_bit_ptr++ = -1;
685}
686
687#endif /* D_PROGRESSIVE_SUPPORTED */
688