Coverage Report

Created: 2026-10-28 06:08

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/src/libjpeg-turbo.3.0.x/jdphuff.c
Line
Count
Source
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
172k
{
84
172k
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
85
172k
  boolean is_DC_band, bad;
86
172k
  int ci, coefi, tbl;
87
172k
  d_derived_tbl **pdtbl;
88
172k
  int *coef_bit_ptr, *prev_coef_bit_ptr;
89
172k
  jpeg_component_info *compptr;
90
91
172k
  is_DC_band = (cinfo->Ss == 0);
92
93
  /* Validate scan parameters */
94
172k
  bad = FALSE;
95
172k
  if (is_DC_band) {
96
58.9k
    if (cinfo->Se != 0)
97
269
      bad = TRUE;
98
113k
  } else {
99
    /* need not check Ss/Se < 0 since they came from unsigned bytes */
100
113k
    if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
101
678
      bad = TRUE;
102
    /* AC scans may have only one component */
103
113k
    if (cinfo->comps_in_scan != 1)
104
76
      bad = TRUE;
105
113k
  }
106
172k
  if (cinfo->Ah != 0) {
107
    /* Successive approximation refinement scan: must have Al = Ah-1. */
108
96.5k
    if (cinfo->Al != cinfo->Ah - 1)
109
901
      bad = TRUE;
110
96.5k
  }
111
172k
  if (cinfo->Al > 13)           /* need not check for < 0 */
112
371
    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
172k
  if (bad)
120
1.13k
    ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
121
172k
             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
387k
  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
127
214k
    int cindex = cinfo->cur_comp_info[ci]->component_index;
128
214k
    coef_bit_ptr = &cinfo->coef_bits[cindex][0];
129
214k
    prev_coef_bit_ptr = &cinfo->coef_bits[cindex + cinfo->num_components][0];
130
214k
    if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
131
69.0k
      WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
132
5.57M
    for (coefi = MIN(cinfo->Ss, 1); coefi <= MAX(cinfo->Se, 9); coefi++) {
133
5.36M
      if (cinfo->input_scan_number > 1)
134
4.56M
        prev_coef_bit_ptr[coefi] = coef_bit_ptr[coefi];
135
794k
      else
136
794k
        prev_coef_bit_ptr[coefi] = 0;
137
5.36M
    }
138
3.72M
    for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
139
3.51M
      int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
140
3.51M
      if (cinfo->Ah != expected)
141
2.81M
        WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
142
3.51M
      coef_bit_ptr[coefi] = cinfo->Al;
143
3.51M
    }
144
214k
  }
145
146
  /* Select MCU decoding routine */
147
172k
  if (cinfo->Ah == 0) {
148
75.9k
    if (is_DC_band)
149
32.3k
      entropy->pub.decode_mcu = decode_mcu_DC_first;
150
43.6k
    else
151
43.6k
      entropy->pub.decode_mcu = decode_mcu_AC_first;
152
96.7k
  } else {
153
96.7k
    if (is_DC_band)
154
26.2k
      entropy->pub.decode_mcu = decode_mcu_DC_refine;
155
70.4k
    else
156
70.4k
      entropy->pub.decode_mcu = decode_mcu_AC_refine;
157
96.7k
  }
158
159
387k
  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
160
214k
    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
214k
    if (is_DC_band) {
165
101k
      if (cinfo->Ah == 0) {     /* DC refinement needs no table */
166
50.3k
        tbl = compptr->dc_tbl_no;
167
50.3k
        pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl;
168
50.3k
        jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, pdtbl);
169
50.3k
      }
170
112k
    } else {
171
112k
      tbl = compptr->ac_tbl_no;
172
112k
      pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl;
173
112k
      jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, pdtbl);
174
      /* remember the single active table */
175
112k
      entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
176
112k
    }
177
    /* Initialize DC predictions to 0 */
178
214k
    entropy->saved.last_dc_val[ci] = 0;
179
214k
  }
180
181
  /* Initialize bitread state variables */
182
172k
  entropy->bitstate.bits_left = 0;
183
172k
  entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
184
172k
  entropy->pub.insufficient_data = FALSE;
185
186
  /* Initialize private state variables */
187
172k
  entropy->saved.EOBRUN = 0;
188
189
  /* Initialize restart counter */
190
172k
  entropy->restarts_to_go = cinfo->restart_interval;
191
172k
}
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
135M
#define NEG_1  ((unsigned)-1)
203
#define HUFF_EXTEND(x, s) \
204
2.73M
  ((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
96.0M
{
234
96.0M
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
235
96.0M
  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
96.0M
  cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
240
96.0M
  entropy->bitstate.bits_left = 0;
241
242
  /* Advance past the RSTn marker */
243
96.0M
  if (!(*cinfo->marker->read_restart_marker) (cinfo))
244
0
    return FALSE;
245
246
  /* Re-initialize DC predictions to 0 */
247
192M
  for (ci = 0; ci < cinfo->comps_in_scan; ci++)
248
96.4M
    entropy->saved.last_dc_val[ci] = 0;
249
  /* Re-init EOB run count, too */
250
96.0M
  entropy->saved.EOBRUN = 0;
251
252
  /* Reset restart counter */
253
96.0M
  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
96.0M
  if (cinfo->unread_marker == 0)
261
34.5k
    entropy->pub.insufficient_data = FALSE;
262
263
96.0M
  return TRUE;
264
96.0M
}
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
43.4M
{
292
43.4M
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
293
43.4M
  int Al = cinfo->Al;
294
43.4M
  register int s, r;
295
43.4M
  int blkn, ci;
296
43.4M
  JBLOCKROW block;
297
43.4M
  BITREAD_STATE_VARS;
298
43.4M
  savable_state state;
299
43.4M
  d_derived_tbl *tbl;
300
43.4M
  jpeg_component_info *compptr;
301
302
  /* Process restart marker if needed; may have to suspend */
303
43.4M
  if (cinfo->restart_interval) {
304
14.0M
    if (entropy->restarts_to_go == 0)
305
2.38M
      if (!process_restart(cinfo))
306
0
        return FALSE;
307
14.0M
  }
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
43.4M
  if (!entropy->pub.insufficient_data) {
313
314
    /* Load up working state */
315
1.88M
    BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
316
1.88M
    state = entropy->saved;
317
318
    /* Outer loop handles each block in the MCU */
319
320
4.06M
    for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
321
2.18M
      block = MCU_data[blkn];
322
2.18M
      ci = cinfo->MCU_membership[blkn];
323
2.18M
      compptr = cinfo->cur_comp_info[ci];
324
2.18M
      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
2.18M
      HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
330
2.18M
      if (s) {
331
1.91M
        CHECK_BIT_BUFFER(br_state, s, return FALSE);
332
1.91M
        r = GET_BITS(s);
333
1.91M
        s = HUFF_EXTEND(r, s);
334
1.91M
      }
335
336
      /* Convert DC difference to actual value, update last_dc_val */
337
2.18M
      if ((state.last_dc_val[ci] >= 0 &&
338
290k
           s > INT_MAX - state.last_dc_val[ci]) ||
339
2.18M
          (state.last_dc_val[ci] < 0 && s < INT_MIN - state.last_dc_val[ci]))
340
0
        ERREXIT(cinfo, JERR_BAD_DCT_COEF);
341
2.18M
      s += state.last_dc_val[ci];
342
2.18M
      state.last_dc_val[ci] = s;
343
      /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
344
2.18M
      (*block)[0] = (JCOEF)LEFT_SHIFT(s, Al);
345
2.18M
    }
346
347
    /* Completed MCU, so update state */
348
1.88M
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
349
1.88M
    entropy->saved = state;
350
1.88M
  }
351
352
  /* Account for restart interval (no-op if not using restarts) */
353
43.4M
  if (cinfo->restart_interval)
354
14.0M
    entropy->restarts_to_go--;
355
356
43.4M
  return TRUE;
357
43.4M
}
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
98.6M
{
368
98.6M
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
369
98.6M
  int Se = cinfo->Se;
370
98.6M
  int Al = cinfo->Al;
371
98.6M
  register int s, k, r;
372
98.6M
  unsigned int EOBRUN;
373
98.6M
  JBLOCKROW block;
374
98.6M
  BITREAD_STATE_VARS;
375
98.6M
  d_derived_tbl *tbl;
376
377
  /* Process restart marker if needed; may have to suspend */
378
98.6M
  if (cinfo->restart_interval) {
379
51.0M
    if (entropy->restarts_to_go == 0)
380
1.35M
      if (!process_restart(cinfo))
381
0
        return FALSE;
382
51.0M
  }
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
98.6M
  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
2.95M
    EOBRUN = entropy->saved.EOBRUN;     /* only part of saved state we need */
393
394
    /* There is always only one block per MCU */
395
396
2.95M
    if (EOBRUN > 0)             /* if it's a band of zeroes... */
397
2.54M
      EOBRUN--;                 /* ...process it now (we do nothing) */
398
410k
    else {
399
410k
      BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
400
410k
      block = MCU_data[0];
401
410k
      tbl = entropy->ac_derived_tbl;
402
403
1.24M
      for (k = cinfo->Ss; k <= Se; k++) {
404
1.13M
        HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
405
1.13M
        r = s >> 4;
406
1.13M
        s &= 15;
407
1.13M
        if (s) {
408
824k
          k += r;
409
824k
          CHECK_BIT_BUFFER(br_state, s, return FALSE);
410
824k
          r = GET_BITS(s);
411
824k
          s = HUFF_EXTEND(r, s);
412
          /* Scale and output coefficient in natural (dezigzagged) order */
413
824k
          (*block)[jpeg_natural_order[k]] = (JCOEF)LEFT_SHIFT(s, Al);
414
824k
        } else {
415
311k
          if (r == 15) {        /* ZRL */
416
11.7k
            k += 15;            /* skip 15 zeroes in band */
417
299k
          } else {              /* EOBr, run length is 2^r + appended bits */
418
299k
            EOBRUN = 1 << r;
419
299k
            if (r) {            /* EOBr, r > 0 */
420
92.9k
              CHECK_BIT_BUFFER(br_state, r, return FALSE);
421
92.9k
              r = GET_BITS(r);
422
92.9k
              EOBRUN += r;
423
92.9k
            }
424
299k
            EOBRUN--;           /* this band is processed at this moment */
425
299k
            break;              /* force end-of-band */
426
299k
          }
427
311k
        }
428
1.13M
      }
429
430
410k
      BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
431
410k
    }
432
433
    /* Completed MCU, so update state */
434
2.95M
    entropy->saved.EOBRUN = EOBRUN;     /* only part of saved state we need */
435
2.95M
  }
436
437
  /* Account for restart interval (no-op if not using restarts) */
438
98.6M
  if (cinfo->restart_interval)
439
51.0M
    entropy->restarts_to_go--;
440
441
98.6M
  return TRUE;
442
98.6M
}
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
122M
{
454
122M
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
455
122M
  int p1 = 1 << cinfo->Al;      /* 1 in the bit position being coded */
456
122M
  int blkn;
457
122M
  JBLOCKROW block;
458
122M
  BITREAD_STATE_VARS;
459
460
  /* Process restart marker if needed; may have to suspend */
461
122M
  if (cinfo->restart_interval) {
462
91.7M
    if (entropy->restarts_to_go == 0)
463
82.9M
      if (!process_restart(cinfo))
464
0
        return FALSE;
465
91.7M
  }
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
122M
  BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
473
474
  /* Outer loop handles each block in the MCU */
475
476
281M
  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
477
159M
    block = MCU_data[blkn];
478
479
    /* Encoded data is simply the next bit of the two's-complement DC value */
480
159M
    CHECK_BIT_BUFFER(br_state, 1, return FALSE);
481
159M
    if (GET_BITS(1))
482
261k
      (*block)[0] |= p1;
483
    /* Note: since we use |=, repeating the assignment later is safe */
484
159M
  }
485
486
  /* Completed MCU, so update state */
487
122M
  BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
488
489
  /* Account for restart interval (no-op if not using restarts) */
490
122M
  if (cinfo->restart_interval)
491
91.7M
    entropy->restarts_to_go--;
492
493
122M
  return TRUE;
494
122M
}
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
133M
{
504
133M
  phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
505
133M
  int Se = cinfo->Se;
506
133M
  int p1 = 1 << cinfo->Al;        /* 1 in the bit position being coded */
507
133M
  int m1 = (NEG_1) << cinfo->Al;  /* -1 in the bit position being coded */
508
133M
  register int s, k, r;
509
133M
  unsigned int EOBRUN;
510
133M
  JBLOCKROW block;
511
133M
  JCOEFPTR thiscoef;
512
133M
  BITREAD_STATE_VARS;
513
133M
  d_derived_tbl *tbl;
514
133M
  int num_newnz;
515
133M
  int newnz_pos[DCTSIZE2];
516
517
  /* Process restart marker if needed; may have to suspend */
518
133M
  if (cinfo->restart_interval) {
519
61.1M
    if (entropy->restarts_to_go == 0)
520
9.34M
      if (!process_restart(cinfo))
521
0
        return FALSE;
522
61.1M
  }
523
524
  /* If we've run out of data, don't modify the MCU.
525
   */
526
133M
  if (!entropy->pub.insufficient_data) {
527
528
    /* Load up working state */
529
2.76M
    BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
530
2.76M
    EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
531
532
    /* There is always only one block per MCU */
533
2.76M
    block = MCU_data[0];
534
2.76M
    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
2.76M
    num_newnz = 0;
543
544
    /* initialize coefficient loop counter to start of band */
545
2.76M
    k = cinfo->Ss;
546
547
2.76M
    if (EOBRUN == 0) {
548
1.63M
      for (; k <= Se; k++) {
549
1.46M
        HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
550
1.46M
        r = s >> 4;
551
1.46M
        s &= 15;
552
1.46M
        if (s) {
553
1.16M
          if (s != 1)           /* size of new coef should always be 1 */
554
495k
            WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
555
1.16M
          CHECK_BIT_BUFFER(br_state, 1, goto undoit);
556
1.16M
          if (GET_BITS(1))
557
424k
            s = p1;             /* newly nonzero coef is positive */
558
740k
          else
559
740k
            s = m1;             /* newly nonzero coef is negative */
560
1.16M
        } else {
561
296k
          if (r != 15) {
562
283k
            EOBRUN = 1 << r;    /* EOBr, run length is 2^r + appended bits */
563
283k
            if (r) {
564
116k
              CHECK_BIT_BUFFER(br_state, r, goto undoit);
565
116k
              r = GET_BITS(r);
566
116k
              EOBRUN += r;
567
116k
            }
568
283k
            break;              /* rest of block is handled by EOB logic */
569
283k
          }
570
          /* note s = 0 for processing ZRL */
571
296k
        }
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
6.22M
        do {
577
6.22M
          thiscoef = *block + jpeg_natural_order[k];
578
6.22M
          if (*thiscoef != 0) {
579
3.19M
            CHECK_BIT_BUFFER(br_state, 1, goto undoit);
580
3.19M
            if (GET_BITS(1)) {
581
1.16M
              if ((*thiscoef & p1) == 0) { /* do nothing if already set it */
582
97.2k
                if (*thiscoef >= 0)
583
46.7k
                  *thiscoef += (JCOEF)p1;
584
50.4k
                else
585
50.4k
                  *thiscoef += (JCOEF)m1;
586
97.2k
              }
587
1.16M
            }
588
3.19M
          } else {
589
3.03M
            if (--r < 0)
590
1.02M
              break;            /* reached target zero coefficient */
591
3.03M
          }
592
5.20M
          k++;
593
5.20M
        } while (k <= Se);
594
1.17M
        if (s) {
595
1.16M
          int pos = jpeg_natural_order[k];
596
          /* Output newly nonzero coefficient */
597
1.16M
          (*block)[pos] = (JCOEF)s;
598
          /* Remember its position in case we have to suspend */
599
1.16M
          newnz_pos[num_newnz++] = pos;
600
1.16M
        }
601
1.17M
      }
602
460k
    }
603
604
2.76M
    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
68.9M
      for (; k <= Se; k++) {
611
66.3M
        thiscoef = *block + jpeg_natural_order[k];
612
66.3M
        if (*thiscoef != 0) {
613
1.28M
          CHECK_BIT_BUFFER(br_state, 1, goto undoit);
614
1.28M
          if (GET_BITS(1)) {
615
634k
            if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
616
75.5k
              if (*thiscoef >= 0)
617
38.3k
                *thiscoef += (JCOEF)p1;
618
37.2k
              else
619
37.2k
                *thiscoef += (JCOEF)m1;
620
75.5k
            }
621
634k
          }
622
1.28M
        }
623
66.3M
      }
624
      /* Count one block completed in EOB run */
625
2.59M
      EOBRUN--;
626
2.59M
    }
627
628
    /* Completed MCU, so update state */
629
2.76M
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
630
2.76M
    entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
631
2.76M
  }
632
633
  /* Account for restart interval (no-op if not using restarts) */
634
133M
  if (cinfo->restart_interval)
635
61.1M
    entropy->restarts_to_go--;
636
637
133M
  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
133M
}
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
30.5k
{
655
30.5k
  phuff_entropy_ptr entropy;
656
30.5k
  int *coef_bit_ptr;
657
30.5k
  int ci, i;
658
659
30.5k
  entropy = (phuff_entropy_ptr)
660
30.5k
    (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
661
30.5k
                                sizeof(phuff_entropy_decoder));
662
30.5k
  cinfo->entropy = (struct jpeg_entropy_decoder *)entropy;
663
30.5k
  entropy->pub.start_pass = start_pass_phuff_decoder;
664
665
  /* Mark derived tables unallocated */
666
152k
  for (i = 0; i < NUM_HUFF_TBLS; i++) {
667
122k
    entropy->derived_tbls[i] = NULL;
668
122k
  }
669
670
  /* Create progression status table */
671
30.5k
  cinfo->coef_bits = (int (*)[DCTSIZE2])
672
30.5k
    (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
673
30.5k
                                cinfo->num_components * 2 * DCTSIZE2 *
674
30.5k
                                sizeof(int));
675
30.5k
  coef_bit_ptr = &cinfo->coef_bits[0][0];
676
89.5k
  for (ci = 0; ci < cinfo->num_components; ci++)
677
3.83M
    for (i = 0; i < DCTSIZE2; i++)
678
3.77M
      *coef_bit_ptr++ = -1;
679
30.5k
}
680
681
#endif /* D_PROGRESSIVE_SUPPORTED */