Coverage Report

Created: 2024-06-18 06:05

/src/libjpeg-turbo/jdphuff.c
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Count
Source (jump to first uncovered line)
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
 * Lossless JPEG Modifications:
7
 * Copyright (C) 1999, Ken Murchison.
8
 * libjpeg-turbo Modifications:
9
 * Copyright (C) 2015-2016, 2018-2022, D. R. Commander.
10
 * For conditions of distribution and use, see the accompanying README.ijg
11
 * file.
12
 *
13
 * This file contains Huffman entropy decoding routines for progressive JPEG.
14
 *
15
 * Much of the complexity here has to do with supporting input suspension.
16
 * If the data source module demands suspension, we want to be able to back
17
 * up to the start of the current MCU.  To do this, we copy state variables
18
 * into local working storage, and update them back to the permanent
19
 * storage only upon successful completion of an MCU.
20
 *
21
 * NOTE: All referenced figures are from
22
 * Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994.
23
 */
24
25
#define JPEG_INTERNALS
26
#include "jinclude.h"
27
#include "jpeglib.h"
28
#include "jdhuff.h"             /* Declarations shared with jd*huff.c */
29
#include <limits.h>
30
31
32
#ifdef D_PROGRESSIVE_SUPPORTED
33
34
/*
35
 * Expanded entropy decoder object for progressive Huffman decoding.
36
 *
37
 * The savable_state subrecord contains fields that change within an MCU,
38
 * but must not be updated permanently until we complete the MCU.
39
 */
40
41
typedef struct {
42
  unsigned int EOBRUN;                  /* remaining EOBs in EOBRUN */
43
  int last_dc_val[MAX_COMPS_IN_SCAN];   /* last DC coef for each component */
44
} savable_state;
45
46
typedef struct {
47
  struct jpeg_entropy_decoder pub; /* public fields */
48
49
  /* These fields are loaded into local variables at start of each MCU.
50
   * In case of suspension, we exit WITHOUT updating them.
51
   */
52
  bitread_perm_state bitstate;  /* Bit buffer at start of MCU */
53
  savable_state saved;          /* Other state at start of MCU */
54
55
  /* These fields are NOT loaded into local working state. */
56
  unsigned int restarts_to_go;  /* MCUs left in this restart interval */
57
58
  /* Pointers to derived tables (these workspaces have image lifespan) */
59
  d_derived_tbl *derived_tbls[NUM_HUFF_TBLS];
60
61
  d_derived_tbl *ac_derived_tbl; /* active table during an AC scan */
62
} phuff_entropy_decoder;
63
64
typedef phuff_entropy_decoder *phuff_entropy_ptr;
65
66
/* Forward declarations */
67
METHODDEF(boolean) decode_mcu_DC_first(j_decompress_ptr cinfo,
68
                                       JBLOCKROW *MCU_data);
69
METHODDEF(boolean) decode_mcu_AC_first(j_decompress_ptr cinfo,
70
                                       JBLOCKROW *MCU_data);
71
METHODDEF(boolean) decode_mcu_DC_refine(j_decompress_ptr cinfo,
72
                                        JBLOCKROW *MCU_data);
73
METHODDEF(boolean) decode_mcu_AC_refine(j_decompress_ptr cinfo,
74
                                        JBLOCKROW *MCU_data);
75
76
77
/*
78
 * Initialize for a Huffman-compressed scan.
79
 */
80
81
METHODDEF(void)
82
start_pass_phuff_decoder(j_decompress_ptr cinfo)
83
0
{
84
0
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
85
0
  boolean is_DC_band, bad;
86
0
  int ci, coefi, tbl;
87
0
  d_derived_tbl **pdtbl;
88
0
  int *coef_bit_ptr, *prev_coef_bit_ptr;
89
0
  jpeg_component_info *compptr;
90
91
0
  is_DC_band = (cinfo->Ss == 0);
92
93
  /* Validate scan parameters */
94
0
  bad = FALSE;
95
0
  if (is_DC_band) {
96
0
    if (cinfo->Se != 0)
97
0
      bad = TRUE;
98
0
  } else {
99
    /* need not check Ss/Se < 0 since they came from unsigned bytes */
100
0
    if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
101
0
      bad = TRUE;
102
    /* AC scans may have only one component */
103
0
    if (cinfo->comps_in_scan != 1)
104
0
      bad = TRUE;
105
0
  }
106
0
  if (cinfo->Ah != 0) {
107
    /* Successive approximation refinement scan: must have Al = Ah-1. */
108
0
    if (cinfo->Al != cinfo->Ah - 1)
109
0
      bad = TRUE;
110
0
  }
111
0
  if (cinfo->Al > 13)           /* need not check for < 0 */
112
0
    bad = TRUE;
113
  /* Arguably the maximum Al value should be less than 13 for 8-bit precision,
114
   * but the spec doesn't say so, and we try to be liberal about what we
115
   * accept.  Note: large Al values could result in out-of-range DC
116
   * coefficients during early scans, leading to bizarre displays due to
117
   * overflows in the IDCT math.  But we won't crash.
118
   */
119
0
  if (bad)
120
0
    ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
121
0
             cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
122
  /* Update progression status, and verify that scan order is legal.
123
   * Note that inter-scan inconsistencies are treated as warnings
124
   * not fatal errors ... not clear if this is right way to behave.
125
   */
126
0
  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
127
0
    int cindex = cinfo->cur_comp_info[ci]->component_index;
128
0
    coef_bit_ptr = &cinfo->coef_bits[cindex][0];
129
0
    prev_coef_bit_ptr = &cinfo->coef_bits[cindex + cinfo->num_components][0];
130
0
    if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
131
0
      WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
132
0
    for (coefi = MIN(cinfo->Ss, 1); coefi <= MAX(cinfo->Se, 9); coefi++) {
133
0
      if (cinfo->input_scan_number > 1)
134
0
        prev_coef_bit_ptr[coefi] = coef_bit_ptr[coefi];
135
0
      else
136
0
        prev_coef_bit_ptr[coefi] = 0;
137
0
    }
138
0
    for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
139
0
      int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
140
0
      if (cinfo->Ah != expected)
141
0
        WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
142
0
      coef_bit_ptr[coefi] = cinfo->Al;
143
0
    }
144
0
  }
145
146
  /* Select MCU decoding routine */
147
0
  if (cinfo->Ah == 0) {
148
0
    if (is_DC_band)
149
0
      entropy->pub.decode_mcu = decode_mcu_DC_first;
150
0
    else
151
0
      entropy->pub.decode_mcu = decode_mcu_AC_first;
152
0
  } else {
153
0
    if (is_DC_band)
154
0
      entropy->pub.decode_mcu = decode_mcu_DC_refine;
155
0
    else
156
0
      entropy->pub.decode_mcu = decode_mcu_AC_refine;
157
0
  }
158
159
0
  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
160
0
    compptr = cinfo->cur_comp_info[ci];
161
    /* Make sure requested tables are present, and compute derived tables.
162
     * We may build same derived table more than once, but it's not expensive.
163
     */
164
0
    if (is_DC_band) {
165
0
      if (cinfo->Ah == 0) {     /* DC refinement needs no table */
166
0
        tbl = compptr->dc_tbl_no;
167
0
        pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl;
168
0
        jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, pdtbl);
169
0
      }
170
0
    } else {
171
0
      tbl = compptr->ac_tbl_no;
172
0
      pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl;
173
0
      jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, pdtbl);
174
      /* remember the single active table */
175
0
      entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
176
0
    }
177
    /* Initialize DC predictions to 0 */
178
0
    entropy->saved.last_dc_val[ci] = 0;
179
0
  }
180
181
  /* Initialize bitread state variables */
182
0
  entropy->bitstate.bits_left = 0;
183
0
  entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
184
0
  entropy->pub.insufficient_data = FALSE;
185
186
  /* Initialize private state variables */
187
0
  entropy->saved.EOBRUN = 0;
188
189
  /* Initialize restart counter */
190
0
  entropy->restarts_to_go = cinfo->restart_interval;
191
0
}
192
193
194
/*
195
 * Figure F.12: extend sign bit.
196
 * On some machines, a shift and add will be faster than a table lookup.
197
 */
198
199
#define AVOID_TABLES
200
#ifdef AVOID_TABLES
201
202
0
#define NEG_1  ((unsigned)-1)
203
#define HUFF_EXTEND(x, s) \
204
0
  ((x) < (1 << ((s) - 1)) ? (x) + (((NEG_1) << (s)) + 1) : (x))
205
206
#else
207
208
#define HUFF_EXTEND(x, s) \
209
  ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
210
211
static const int extend_test[16] = {   /* entry n is 2**(n-1) */
212
  0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
213
  0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000
214
};
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
223
#endif /* AVOID_TABLES */
224
225
226
/*
227
 * Check for a restart marker & resynchronize decoder.
228
 * Returns FALSE if must suspend.
229
 */
230
231
LOCAL(boolean)
232
process_restart(j_decompress_ptr cinfo)
233
0
{
234
0
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
235
0
  int ci;
236
237
  /* Throw away any unused bits remaining in bit buffer; */
238
  /* include any full bytes in next_marker's count of discarded bytes */
239
0
  cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
240
0
  entropy->bitstate.bits_left = 0;
241
242
  /* Advance past the RSTn marker */
243
0
  if (!(*cinfo->marker->read_restart_marker) (cinfo))
244
0
    return FALSE;
245
246
  /* Re-initialize DC predictions to 0 */
247
0
  for (ci = 0; ci < cinfo->comps_in_scan; ci++)
248
0
    entropy->saved.last_dc_val[ci] = 0;
249
  /* Re-init EOB run count, too */
250
0
  entropy->saved.EOBRUN = 0;
251
252
  /* Reset restart counter */
253
0
  entropy->restarts_to_go = cinfo->restart_interval;
254
255
  /* Reset out-of-data flag, unless read_restart_marker left us smack up
256
   * against a marker.  In that case we will end up treating the next data
257
   * segment as empty, and we can avoid producing bogus output pixels by
258
   * leaving the flag set.
259
   */
260
0
  if (cinfo->unread_marker == 0)
261
0
    entropy->pub.insufficient_data = FALSE;
262
263
0
  return TRUE;
264
0
}
265
266
267
/*
268
 * Huffman MCU decoding.
269
 * Each of these routines decodes and returns one MCU's worth of
270
 * Huffman-compressed coefficients.
271
 * The coefficients are reordered from zigzag order into natural array order,
272
 * but are not dequantized.
273
 *
274
 * The i'th block of the MCU is stored into the block pointed to by
275
 * MCU_data[i].  WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
276
 *
277
 * We return FALSE if data source requested suspension.  In that case no
278
 * changes have been made to permanent state.  (Exception: some output
279
 * coefficients may already have been assigned.  This is harmless for
280
 * spectral selection, since we'll just re-assign them on the next call.
281
 * Successive approximation AC refinement has to be more careful, however.)
282
 */
283
284
/*
285
 * MCU decoding for DC initial scan (either spectral selection,
286
 * or first pass of successive approximation).
287
 */
288
289
METHODDEF(boolean)
290
decode_mcu_DC_first(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
291
0
{
292
0
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
293
0
  int Al = cinfo->Al;
294
0
  register int s, r;
295
0
  int blkn, ci;
296
0
  JBLOCKROW block;
297
0
  BITREAD_STATE_VARS;
298
0
  savable_state state;
299
0
  d_derived_tbl *tbl;
300
0
  jpeg_component_info *compptr;
301
302
  /* Process restart marker if needed; may have to suspend */
303
0
  if (cinfo->restart_interval) {
304
0
    if (entropy->restarts_to_go == 0)
305
0
      if (!process_restart(cinfo))
306
0
        return FALSE;
307
0
  }
308
309
  /* If we've run out of data, just leave the MCU set to zeroes.
310
   * This way, we return uniform gray for the remainder of the segment.
311
   */
312
0
  if (!entropy->pub.insufficient_data) {
313
314
    /* Load up working state */
315
0
    BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
316
0
    state = entropy->saved;
317
318
    /* Outer loop handles each block in the MCU */
319
320
0
    for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
321
0
      block = MCU_data[blkn];
322
0
      ci = cinfo->MCU_membership[blkn];
323
0
      compptr = cinfo->cur_comp_info[ci];
324
0
      tbl = entropy->derived_tbls[compptr->dc_tbl_no];
325
326
      /* Decode a single block's worth of coefficients */
327
328
      /* Section F.2.2.1: decode the DC coefficient difference */
329
0
      HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
330
0
      if (s) {
331
0
        CHECK_BIT_BUFFER(br_state, s, return FALSE);
332
0
        r = GET_BITS(s);
333
0
        s = HUFF_EXTEND(r, s);
334
0
      }
335
336
      /* Convert DC difference to actual value, update last_dc_val */
337
0
      if ((state.last_dc_val[ci] >= 0 &&
338
0
           s > INT_MAX - state.last_dc_val[ci]) ||
339
0
          (state.last_dc_val[ci] < 0 && s < INT_MIN - state.last_dc_val[ci]))
340
0
        ERREXIT(cinfo, JERR_BAD_DCT_COEF);
341
0
      s += state.last_dc_val[ci];
342
0
      state.last_dc_val[ci] = s;
343
      /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
344
0
      (*block)[0] = (JCOEF)LEFT_SHIFT(s, Al);
345
0
    }
346
347
    /* Completed MCU, so update state */
348
0
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
349
0
    entropy->saved = state;
350
0
  }
351
352
  /* Account for restart interval (no-op if not using restarts) */
353
0
  if (cinfo->restart_interval)
354
0
    entropy->restarts_to_go--;
355
356
0
  return TRUE;
357
0
}
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
0
{
368
0
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
369
0
  int Se = cinfo->Se;
370
0
  int Al = cinfo->Al;
371
0
  register int s, k, r;
372
0
  unsigned int EOBRUN;
373
0
  JBLOCKROW block;
374
0
  BITREAD_STATE_VARS;
375
0
  d_derived_tbl *tbl;
376
377
  /* Process restart marker if needed; may have to suspend */
378
0
  if (cinfo->restart_interval) {
379
0
    if (entropy->restarts_to_go == 0)
380
0
      if (!process_restart(cinfo))
381
0
        return FALSE;
382
0
  }
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
0
  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
0
    EOBRUN = entropy->saved.EOBRUN;     /* only part of saved state we need */
393
394
    /* There is always only one block per MCU */
395
396
0
    if (EOBRUN > 0)             /* if it's a band of zeroes... */
397
0
      EOBRUN--;                 /* ...process it now (we do nothing) */
398
0
    else {
399
0
      BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
400
0
      block = MCU_data[0];
401
0
      tbl = entropy->ac_derived_tbl;
402
403
0
      for (k = cinfo->Ss; k <= Se; k++) {
404
0
        HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
405
0
        r = s >> 4;
406
0
        s &= 15;
407
0
        if (s) {
408
0
          k += r;
409
0
          CHECK_BIT_BUFFER(br_state, s, return FALSE);
410
0
          r = GET_BITS(s);
411
0
          s = HUFF_EXTEND(r, s);
412
          /* Scale and output coefficient in natural (dezigzagged) order */
413
0
          (*block)[jpeg_natural_order[k]] = (JCOEF)LEFT_SHIFT(s, Al);
414
0
        } else {
415
0
          if (r == 15) {        /* ZRL */
416
0
            k += 15;            /* skip 15 zeroes in band */
417
0
          } else {              /* EOBr, run length is 2^r + appended bits */
418
0
            EOBRUN = 1 << r;
419
0
            if (r) {            /* EOBr, r > 0 */
420
0
              CHECK_BIT_BUFFER(br_state, r, return FALSE);
421
0
              r = GET_BITS(r);
422
0
              EOBRUN += r;
423
0
            }
424
0
            EOBRUN--;           /* this band is processed at this moment */
425
0
            break;              /* force end-of-band */
426
0
          }
427
0
        }
428
0
      }
429
430
0
      BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
431
0
    }
432
433
    /* Completed MCU, so update state */
434
0
    entropy->saved.EOBRUN = EOBRUN;     /* only part of saved state we need */
435
0
  }
436
437
  /* Account for restart interval (no-op if not using restarts) */
438
0
  if (cinfo->restart_interval)
439
0
    entropy->restarts_to_go--;
440
441
0
  return TRUE;
442
0
}
443
444
445
/*
446
 * MCU decoding for DC successive approximation refinement scan.
447
 * Note: we assume such scans can be multi-component, although the spec
448
 * is not very clear on the point.
449
 */
450
451
METHODDEF(boolean)
452
decode_mcu_DC_refine(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
453
0
{
454
0
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
455
0
  int p1 = 1 << cinfo->Al;      /* 1 in the bit position being coded */
456
0
  int blkn;
457
0
  JBLOCKROW block;
458
0
  BITREAD_STATE_VARS;
459
460
  /* Process restart marker if needed; may have to suspend */
461
0
  if (cinfo->restart_interval) {
462
0
    if (entropy->restarts_to_go == 0)
463
0
      if (!process_restart(cinfo))
464
0
        return FALSE;
465
0
  }
466
467
  /* Not worth the cycles to check insufficient_data here,
468
   * since we will not change the data anyway if we read zeroes.
469
   */
470
471
  /* Load up working state */
472
0
  BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
473
474
  /* Outer loop handles each block in the MCU */
475
476
0
  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
477
0
    block = MCU_data[blkn];
478
479
    /* Encoded data is simply the next bit of the two's-complement DC value */
480
0
    CHECK_BIT_BUFFER(br_state, 1, return FALSE);
481
0
    if (GET_BITS(1))
482
0
      (*block)[0] |= p1;
483
    /* Note: since we use |=, repeating the assignment later is safe */
484
0
  }
485
486
  /* Completed MCU, so update state */
487
0
  BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
488
489
  /* Account for restart interval (no-op if not using restarts) */
490
0
  if (cinfo->restart_interval)
491
0
    entropy->restarts_to_go--;
492
493
0
  return TRUE;
494
0
}
495
496
497
/*
498
 * MCU decoding for AC successive approximation refinement scan.
499
 */
500
501
METHODDEF(boolean)
502
decode_mcu_AC_refine(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
503
0
{
504
0
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
505
0
  int Se = cinfo->Se;
506
0
  int p1 = 1 << cinfo->Al;        /* 1 in the bit position being coded */
507
0
  int m1 = (NEG_1) << cinfo->Al;  /* -1 in the bit position being coded */
508
0
  register int s, k, r;
509
0
  unsigned int EOBRUN;
510
0
  JBLOCKROW block;
511
0
  JCOEFPTR thiscoef;
512
0
  BITREAD_STATE_VARS;
513
0
  d_derived_tbl *tbl;
514
0
  int num_newnz;
515
0
  int newnz_pos[DCTSIZE2];
516
517
  /* Process restart marker if needed; may have to suspend */
518
0
  if (cinfo->restart_interval) {
519
0
    if (entropy->restarts_to_go == 0)
520
0
      if (!process_restart(cinfo))
521
0
        return FALSE;
522
0
  }
523
524
  /* If we've run out of data, don't modify the MCU.
525
   */
526
0
  if (!entropy->pub.insufficient_data) {
527
528
    /* Load up working state */
529
0
    BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
530
0
    EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
531
532
    /* There is always only one block per MCU */
533
0
    block = MCU_data[0];
534
0
    tbl = entropy->ac_derived_tbl;
535
536
    /* If we are forced to suspend, we must undo the assignments to any newly
537
     * nonzero coefficients in the block, because otherwise we'd get confused
538
     * next time about which coefficients were already nonzero.
539
     * But we need not undo addition of bits to already-nonzero coefficients;
540
     * instead, we can test the current bit to see if we already did it.
541
     */
542
0
    num_newnz = 0;
543
544
    /* initialize coefficient loop counter to start of band */
545
0
    k = cinfo->Ss;
546
547
0
    if (EOBRUN == 0) {
548
0
      for (; k <= Se; k++) {
549
0
        HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
550
0
        r = s >> 4;
551
0
        s &= 15;
552
0
        if (s) {
553
0
          if (s != 1)           /* size of new coef should always be 1 */
554
0
            WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
555
0
          CHECK_BIT_BUFFER(br_state, 1, goto undoit);
556
0
          if (GET_BITS(1))
557
0
            s = p1;             /* newly nonzero coef is positive */
558
0
          else
559
0
            s = m1;             /* newly nonzero coef is negative */
560
0
        } else {
561
0
          if (r != 15) {
562
0
            EOBRUN = 1 << r;    /* EOBr, run length is 2^r + appended bits */
563
0
            if (r) {
564
0
              CHECK_BIT_BUFFER(br_state, r, goto undoit);
565
0
              r = GET_BITS(r);
566
0
              EOBRUN += r;
567
0
            }
568
0
            break;              /* rest of block is handled by EOB logic */
569
0
          }
570
          /* note s = 0 for processing ZRL */
571
0
        }
572
        /* Advance over already-nonzero coefs and r still-zero coefs,
573
         * appending correction bits to the nonzeroes.  A correction bit is 1
574
         * if the absolute value of the coefficient must be increased.
575
         */
576
0
        do {
577
0
          thiscoef = *block + jpeg_natural_order[k];
578
0
          if (*thiscoef != 0) {
579
0
            CHECK_BIT_BUFFER(br_state, 1, goto undoit);
580
0
            if (GET_BITS(1)) {
581
0
              if ((*thiscoef & p1) == 0) { /* do nothing if already set it */
582
0
                if (*thiscoef >= 0)
583
0
                  *thiscoef += (JCOEF)p1;
584
0
                else
585
0
                  *thiscoef += (JCOEF)m1;
586
0
              }
587
0
            }
588
0
          } else {
589
0
            if (--r < 0)
590
0
              break;            /* reached target zero coefficient */
591
0
          }
592
0
          k++;
593
0
        } while (k <= Se);
594
0
        if (s) {
595
0
          int pos = jpeg_natural_order[k];
596
          /* Output newly nonzero coefficient */
597
0
          (*block)[pos] = (JCOEF)s;
598
          /* Remember its position in case we have to suspend */
599
0
          newnz_pos[num_newnz++] = pos;
600
0
        }
601
0
      }
602
0
    }
603
604
0
    if (EOBRUN > 0) {
605
      /* Scan any remaining coefficient positions after the end-of-band
606
       * (the last newly nonzero coefficient, if any).  Append a correction
607
       * bit to each already-nonzero coefficient.  A correction bit is 1
608
       * if the absolute value of the coefficient must be increased.
609
       */
610
0
      for (; k <= Se; k++) {
611
0
        thiscoef = *block + jpeg_natural_order[k];
612
0
        if (*thiscoef != 0) {
613
0
          CHECK_BIT_BUFFER(br_state, 1, goto undoit);
614
0
          if (GET_BITS(1)) {
615
0
            if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
616
0
              if (*thiscoef >= 0)
617
0
                *thiscoef += (JCOEF)p1;
618
0
              else
619
0
                *thiscoef += (JCOEF)m1;
620
0
            }
621
0
          }
622
0
        }
623
0
      }
624
      /* Count one block completed in EOB run */
625
0
      EOBRUN--;
626
0
    }
627
628
    /* Completed MCU, so update state */
629
0
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
630
0
    entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
631
0
  }
632
633
  /* Account for restart interval (no-op if not using restarts) */
634
0
  if (cinfo->restart_interval)
635
0
    entropy->restarts_to_go--;
636
637
0
  return TRUE;
638
639
0
undoit:
640
  /* Re-zero any output coefficients that we made newly nonzero */
641
0
  while (num_newnz > 0)
642
0
    (*block)[newnz_pos[--num_newnz]] = 0;
643
644
0
  return FALSE;
645
0
}
646
647
648
/*
649
 * Module initialization routine for progressive Huffman entropy decoding.
650
 */
651
652
GLOBAL(void)
653
jinit_phuff_decoder(j_decompress_ptr cinfo)
654
0
{
655
0
  phuff_entropy_ptr entropy;
656
0
  int *coef_bit_ptr;
657
0
  int ci, i;
658
659
0
  entropy = (phuff_entropy_ptr)
660
0
    (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
661
0
                                sizeof(phuff_entropy_decoder));
662
0
  cinfo->entropy = (struct jpeg_entropy_decoder *)entropy;
663
0
  entropy->pub.start_pass = start_pass_phuff_decoder;
664
665
  /* Mark derived tables unallocated */
666
0
  for (i = 0; i < NUM_HUFF_TBLS; i++) {
667
0
    entropy->derived_tbls[i] = NULL;
668
0
  }
669
670
  /* Create progression status table */
671
0
  cinfo->coef_bits = (int (*)[DCTSIZE2])
672
0
    (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
673
0
                                cinfo->num_components * 2 * DCTSIZE2 *
674
0
                                sizeof(int));
675
0
  coef_bit_ptr = &cinfo->coef_bits[0][0];
676
0
  for (ci = 0; ci < cinfo->num_components; ci++)
677
0
    for (i = 0; i < DCTSIZE2; i++)
678
0
      *coef_bit_ptr++ = -1;
679
0
}
680
681
#endif /* D_PROGRESSIVE_SUPPORTED */