Coverage Report

Created: 2025-01-28 06:17

/src/mupdf/thirdparty/libjpeg/jdhuff.c
Line
Count
Source (jump to first uncovered line)
1
/*
2
 * jdhuff.c
3
 *
4
 * Copyright (C) 1991-1997, Thomas G. Lane.
5
 * Modified 2006-2020 by Guido Vollbeding.
6
 * This file is part of the Independent JPEG Group's software.
7
 * For conditions of distribution and use, see the accompanying README file.
8
 *
9
 * This file contains Huffman entropy decoding routines.
10
 * Both sequential and progressive modes are supported in this single module.
11
 *
12
 * Much of the complexity here has to do with supporting input suspension.
13
 * If the data source module demands suspension, we want to be able to back
14
 * up to the start of the current MCU.  To do this, we copy state variables
15
 * into local working storage, and update them back to the permanent
16
 * storage only upon successful completion of an MCU.
17
 */
18
19
#define JPEG_INTERNALS
20
#include "jinclude.h"
21
#include "jpeglib.h"
22
23
24
/* Derived data constructed for each Huffman table */
25
26
14.9M
#define HUFF_LOOKAHEAD  8  /* # of bits of lookahead */
27
28
typedef struct {
29
  /* Basic tables: (element [0] of each array is unused) */
30
  INT32 maxcode[18];    /* largest code of length k (-1 if none) */
31
  /* (maxcode[17] is a sentinel to ensure jpeg_huff_decode terminates) */
32
  INT32 valoffset[17];    /* huffval[] offset for codes of length k */
33
  /* valoffset[k] = huffval[] index of 1st symbol of code length k, less
34
   * the smallest code of length k; so given a code of length k, the
35
   * corresponding symbol is huffval[code + valoffset[k]]
36
   */
37
38
  /* Link to public Huffman table (needed only in jpeg_huff_decode) */
39
  JHUFF_TBL *pub;
40
41
  /* Lookahead tables: indexed by the next HUFF_LOOKAHEAD bits of
42
   * the input data stream.  If the next Huffman code is no more
43
   * than HUFF_LOOKAHEAD bits long, we can obtain its length and
44
   * the corresponding symbol directly from these tables.
45
   */
46
  int look_nbits[1<<HUFF_LOOKAHEAD]; /* # bits, or 0 if too long */
47
  UINT8 look_sym[1<<HUFF_LOOKAHEAD]; /* symbol, or unused */
48
} d_derived_tbl;
49
50
51
/*
52
 * Fetching the next N bits from the input stream is a time-critical operation
53
 * for the Huffman decoders.  We implement it with a combination of inline
54
 * macros and out-of-line subroutines.  Note that N (the number of bits
55
 * demanded at one time) never exceeds 15 for JPEG use.
56
 *
57
 * We read source bytes into get_buffer and dole out bits as needed.
58
 * If get_buffer already contains enough bits, they are fetched in-line
59
 * by the macros CHECK_BIT_BUFFER and GET_BITS.  When there aren't enough
60
 * bits, jpeg_fill_bit_buffer is called; it will attempt to fill get_buffer
61
 * as full as possible (not just to the number of bits needed; this
62
 * prefetching reduces the overhead cost of calling jpeg_fill_bit_buffer).
63
 * Note that jpeg_fill_bit_buffer may return FALSE to indicate suspension.
64
 * On TRUE return, jpeg_fill_bit_buffer guarantees that get_buffer contains
65
 * at least the requested number of bits --- dummy zeroes are inserted if
66
 * necessary.
67
 */
68
69
typedef INT32 bit_buf_type; /* type of bit-extraction buffer */
70
9.35M
#define BIT_BUF_SIZE  32  /* size of buffer in bits */
71
72
/* If long is > 32 bits on your machine, and shifting/masking longs is
73
 * reasonably fast, making bit_buf_type be long and setting BIT_BUF_SIZE
74
 * appropriately should be a win.  Unfortunately we can't define the size
75
 * with something like  #define BIT_BUF_SIZE (sizeof(bit_buf_type)*8)
76
 * because not all machines measure sizeof in 8-bit bytes.
77
 */
78
79
typedef struct {    /* Bitreading state saved across MCUs */
80
  bit_buf_type get_buffer;  /* current bit-extraction buffer */
81
  int bits_left;    /* # of unused bits in it */
82
} bitread_perm_state;
83
84
typedef struct {    /* Bitreading working state within an MCU */
85
  /* Current data source location */
86
  /* We need a copy, rather than munging the original, in case of suspension */
87
  const JOCTET * next_input_byte; /* => next byte to read from source */
88
  size_t bytes_in_buffer; /* # of bytes remaining in source buffer */
89
  /* Bit input buffer --- note these values are kept in register variables,
90
   * not in this struct, inside the inner loops.
91
   */
92
  bit_buf_type get_buffer;  /* current bit-extraction buffer */
93
  int bits_left;    /* # of unused bits in it */
94
  /* Pointer needed by jpeg_fill_bit_buffer. */
95
  j_decompress_ptr cinfo; /* back link to decompress master record */
96
} bitread_working_state;
97
98
/* Macros to declare and load/save bitread local variables. */
99
#define BITREAD_STATE_VARS  \
100
12.7M
  register bit_buf_type get_buffer;  \
101
12.7M
  register int bits_left;  \
102
12.7M
  bitread_working_state br_state
103
104
#define BITREAD_LOAD_STATE(cinfop,permstate)  \
105
1.50M
  br_state.cinfo = cinfop; \
106
1.50M
  br_state.next_input_byte = cinfop->src->next_input_byte; \
107
1.50M
  br_state.bytes_in_buffer = cinfop->src->bytes_in_buffer; \
108
1.50M
  get_buffer = permstate.get_buffer; \
109
1.50M
  bits_left = permstate.bits_left;
110
111
#define BITREAD_SAVE_STATE(cinfop,permstate)  \
112
1.50M
  cinfop->src->next_input_byte = br_state.next_input_byte; \
113
1.50M
  cinfop->src->bytes_in_buffer = br_state.bytes_in_buffer; \
114
1.50M
  permstate.get_buffer = get_buffer; \
115
1.50M
  permstate.bits_left = bits_left
116
117
/*
118
 * These macros provide the in-line portion of bit fetching.
119
 * Use CHECK_BIT_BUFFER to ensure there are N bits in get_buffer
120
 * before using GET_BITS, PEEK_BITS, or DROP_BITS.
121
 * The variables get_buffer and bits_left are assumed to be locals,
122
 * but the state struct might not be (jpeg_huff_decode needs this).
123
 *  CHECK_BIT_BUFFER(state,n,action);
124
 *    Ensure there are N bits in get_buffer; if suspend, take action.
125
 *      val = GET_BITS(n);
126
 *    Fetch next N bits.
127
 *      val = PEEK_BITS(n);
128
 *    Fetch next N bits without removing them from the buffer.
129
 *  DROP_BITS(n);
130
 *    Discard next N bits.
131
 * The value N should be a simple variable, not an expression, because it
132
 * is evaluated multiple times.
133
 */
134
135
#define CHECK_BIT_BUFFER(state,nbits,action) \
136
9.48M
  { if (bits_left < (nbits)) {  \
137
340k
      if (! jpeg_fill_bit_buffer(&(state),get_buffer,bits_left,nbits))  \
138
340k
        { action; }  \
139
340k
      get_buffer = (state).get_buffer; bits_left = (state).bits_left; } }
140
141
#define GET_BITS(nbits) \
142
7.77M
  (((int) (get_buffer >> (bits_left -= (nbits)))) & BIT_MASK(nbits))
143
144
#define PEEK_BITS(nbits) \
145
12.2M
  (((int) (get_buffer >> (bits_left -  (nbits)))) & BIT_MASK(nbits))
146
147
#define DROP_BITS(nbits) \
148
13.6M
  (bits_left -= (nbits))
149
150
151
/*
152
 * Code for extracting next Huffman-coded symbol from input bit stream.
153
 * Again, this is time-critical and we make the main paths be macros.
154
 *
155
 * We use a lookahead table to process codes of up to HUFF_LOOKAHEAD bits
156
 * without looping.  Usually, more than 95% of the Huffman codes will be 8
157
 * or fewer bits long.  The few overlength codes are handled with a loop,
158
 * which need not be inline code.
159
 *
160
 * Notes about the HUFF_DECODE macro:
161
 * 1. Near the end of the data segment, we may fail to get enough bits
162
 *    for a lookahead.  In that case, we do it the hard way.
163
 * 2. If the lookahead table contains no entry, the next code must be
164
 *    more than HUFF_LOOKAHEAD bits long.
165
 * 3. jpeg_huff_decode returns -1 if forced to suspend.
166
 */
167
168
12.2M
#define HUFF_DECODE(result,state,htbl,failaction,slowlabel) \
169
12.2M
{ register int nb, look; \
170
12.2M
  if (bits_left < HUFF_LOOKAHEAD) { \
171
2.10M
    if (! jpeg_fill_bit_buffer(&state,get_buffer,bits_left, 0)) {failaction;} \
172
2.10M
    get_buffer = state.get_buffer; bits_left = state.bits_left; \
173
2.10M
    if (bits_left < HUFF_LOOKAHEAD) { \
174
44.4k
      nb = 1; goto slowlabel; \
175
44.4k
    } \
176
2.10M
  } \
177
12.2M
  look = PEEK_BITS(HUFF_LOOKAHEAD); \
178
12.2M
  if ((nb = htbl->look_nbits[look]) != 0) { \
179
11.9M
    DROP_BITS(nb); \
180
11.9M
    result = htbl->look_sym[look]; \
181
11.9M
  } else { \
182
360k
    nb = HUFF_LOOKAHEAD+1; \
183
360k
slowlabel: \
184
360k
    if ((result=jpeg_huff_decode(&state,get_buffer,bits_left,htbl,nb)) < 0) \
185
360k
  { failaction; } \
186
360k
    get_buffer = state.get_buffer; bits_left = state.bits_left; \
187
360k
  } \
188
12.2M
}
189
190
191
/*
192
 * Expanded entropy decoder object for Huffman decoding.
193
 *
194
 * The savable_state subrecord contains fields that change within an MCU,
195
 * but must not be updated permanently until we complete the MCU.
196
 */
197
198
typedef struct {
199
  unsigned int EOBRUN;      /* remaining EOBs in EOBRUN */
200
  int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
201
} savable_state;
202
203
/* This macro is to work around compilers with missing or broken
204
 * structure assignment.  You'll need to fix this code if you have
205
 * such a compiler and you change MAX_COMPS_IN_SCAN.
206
 */
207
208
#ifndef NO_STRUCT_ASSIGN
209
1.46M
#define ASSIGN_STATE(dest,src)  ((dest) = (src))
210
#else
211
#if MAX_COMPS_IN_SCAN == 4
212
#define ASSIGN_STATE(dest,src)  \
213
  ((dest).EOBRUN = (src).EOBRUN, \
214
   (dest).last_dc_val[0] = (src).last_dc_val[0], \
215
   (dest).last_dc_val[1] = (src).last_dc_val[1], \
216
   (dest).last_dc_val[2] = (src).last_dc_val[2], \
217
   (dest).last_dc_val[3] = (src).last_dc_val[3])
218
#endif
219
#endif
220
221
222
typedef struct {
223
  struct jpeg_entropy_decoder pub; /* public fields */
224
225
  /* These fields are loaded into local variables at start of each MCU.
226
   * In case of suspension, we exit WITHOUT updating them.
227
   */
228
  bitread_perm_state bitstate;  /* Bit buffer at start of MCU */
229
  savable_state saved;    /* Other state at start of MCU */
230
231
  /* These fields are NOT loaded into local working state. */
232
  boolean insufficient_data;  /* set TRUE after emitting warning */
233
  unsigned int restarts_to_go;  /* MCUs left in this restart interval */
234
235
  /* Following two fields used only in progressive mode */
236
237
  /* Pointers to derived tables (these workspaces have image lifespan) */
238
  d_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
239
240
  d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */
241
242
  /* Following fields used only in sequential mode */
243
244
  /* Pointers to derived tables (these workspaces have image lifespan) */
245
  d_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];
246
  d_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];
247
248
  /* Precalculated info set up by start_pass for use in decode_mcu: */
249
250
  /* Pointers to derived tables to be used for each block within an MCU */
251
  d_derived_tbl * dc_cur_tbls[D_MAX_BLOCKS_IN_MCU];
252
  d_derived_tbl * ac_cur_tbls[D_MAX_BLOCKS_IN_MCU];
253
  /* Whether we care about the DC and AC coefficient values for each block */
254
  int coef_limit[D_MAX_BLOCKS_IN_MCU];
255
} huff_entropy_decoder;
256
257
typedef huff_entropy_decoder * huff_entropy_ptr;
258
259
260
static const int jpeg_zigzag_order[8][8] = {
261
  {  0,  1,  5,  6, 14, 15, 27, 28 },
262
  {  2,  4,  7, 13, 16, 26, 29, 42 },
263
  {  3,  8, 12, 17, 25, 30, 41, 43 },
264
  {  9, 11, 18, 24, 31, 40, 44, 53 },
265
  { 10, 19, 23, 32, 39, 45, 52, 54 },
266
  { 20, 22, 33, 38, 46, 51, 55, 60 },
267
  { 21, 34, 37, 47, 50, 56, 59, 61 },
268
  { 35, 36, 48, 49, 57, 58, 62, 63 }
269
};
270
271
static const int jpeg_zigzag_order7[7][7] = {
272
  {  0,  1,  5,  6, 14, 15, 27 },
273
  {  2,  4,  7, 13, 16, 26, 28 },
274
  {  3,  8, 12, 17, 25, 29, 38 },
275
  {  9, 11, 18, 24, 30, 37, 39 },
276
  { 10, 19, 23, 31, 36, 40, 45 },
277
  { 20, 22, 32, 35, 41, 44, 46 },
278
  { 21, 33, 34, 42, 43, 47, 48 }
279
};
280
281
static const int jpeg_zigzag_order6[6][6] = {
282
  {  0,  1,  5,  6, 14, 15 },
283
  {  2,  4,  7, 13, 16, 25 },
284
  {  3,  8, 12, 17, 24, 26 },
285
  {  9, 11, 18, 23, 27, 32 },
286
  { 10, 19, 22, 28, 31, 33 },
287
  { 20, 21, 29, 30, 34, 35 }
288
};
289
290
static const int jpeg_zigzag_order5[5][5] = {
291
  {  0,  1,  5,  6, 14 },
292
  {  2,  4,  7, 13, 15 },
293
  {  3,  8, 12, 16, 21 },
294
  {  9, 11, 17, 20, 22 },
295
  { 10, 18, 19, 23, 24 }
296
};
297
298
static const int jpeg_zigzag_order4[4][4] = {
299
  { 0,  1,  5,  6 },
300
  { 2,  4,  7, 12 },
301
  { 3,  8, 11, 13 },
302
  { 9, 10, 14, 15 }
303
};
304
305
static const int jpeg_zigzag_order3[3][3] = {
306
  { 0, 1, 5 },
307
  { 2, 4, 6 },
308
  { 3, 7, 8 }
309
};
310
311
static const int jpeg_zigzag_order2[2][2] = {
312
  { 0, 1 },
313
  { 2, 3 }
314
};
315
316
317
/*
318
 * Compute the derived values for a Huffman table.
319
 * This routine also performs some validation checks on the table.
320
 */
321
322
LOCAL(void)
323
jpeg_make_d_derived_tbl (j_decompress_ptr cinfo, boolean isDC, int tblno,
324
       d_derived_tbl ** pdtbl)
325
7.12k
{
326
7.12k
  JHUFF_TBL *htbl;
327
7.12k
  d_derived_tbl *dtbl;
328
7.12k
  int p, i, l, si, numsymbols;
329
7.12k
  int lookbits, ctr;
330
7.12k
  char huffsize[257];
331
7.12k
  unsigned int huffcode[257];
332
7.12k
  unsigned int code;
333
334
  /* Note that huffsize[] and huffcode[] are filled in code-length order,
335
   * paralleling the order of the symbols themselves in htbl->huffval[].
336
   */
337
338
  /* Find the input Huffman table */
339
7.12k
  if (tblno < 0 || tblno >= NUM_HUFF_TBLS)
340
8
    ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);
341
7.12k
  htbl =
342
7.12k
    isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno];
343
7.12k
  if (htbl == NULL)
344
438
    htbl = jpeg_std_huff_table((j_common_ptr) cinfo, isDC, tblno);
345
346
  /* Allocate a workspace if we haven't already done so. */
347
7.12k
  if (*pdtbl == NULL)
348
1.84k
    *pdtbl = (d_derived_tbl *) (*cinfo->mem->alloc_small)
349
1.84k
      ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(d_derived_tbl));
350
7.12k
  dtbl = *pdtbl;
351
7.12k
  dtbl->pub = htbl;   /* fill in back link */
352
  
353
  /* Figure C.1: make table of Huffman code length for each symbol */
354
355
7.12k
  p = 0;
356
120k
  for (l = 1; l <= 16; l++) {
357
113k
    i = (int) htbl->bits[l];
358
113k
    if (i < 0 || p + i > 256)  /* protect against table overrun */
359
0
      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
360
380k
    while (i--)
361
266k
      huffsize[p++] = (char) l;
362
113k
  }
363
7.12k
  huffsize[p] = 0;
364
7.12k
  numsymbols = p;
365
  
366
  /* Figure C.2: generate the codes themselves */
367
  /* We also validate that the counts represent a legal Huffman code tree. */
368
  
369
7.12k
  code = 0;
370
7.12k
  si = huffsize[0];
371
7.12k
  p = 0;
372
67.5k
  while (huffsize[p]) {
373
327k
    while (((int) huffsize[p]) == si) {
374
266k
      huffcode[p++] = code;
375
266k
      code++;
376
266k
    }
377
    /* code is now 1 more than the last code used for codelength si; but
378
     * it must still fit in si bits, since no code is allowed to be all ones.
379
     */
380
60.4k
    if (((INT32) code) >= (((INT32) 1) << si))
381
1
      ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
382
60.4k
    code <<= 1;
383
60.4k
    si++;
384
60.4k
  }
385
386
  /* Figure F.15: generate decoding tables for bit-sequential decoding */
387
388
7.12k
  p = 0;
389
120k
  for (l = 1; l <= 16; l++) {
390
113k
    if (htbl->bits[l]) {
391
      /* valoffset[l] = huffval[] index of 1st symbol of code length l,
392
       * minus the minimum code of length l
393
       */
394
49.0k
      dtbl->valoffset[l] = (INT32) p - (INT32) huffcode[p];
395
49.0k
      p += htbl->bits[l];
396
49.0k
      dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */
397
64.7k
    } else {
398
64.7k
      dtbl->maxcode[l] = -1;  /* -1 if no codes of this length */
399
64.7k
    }
400
113k
  }
401
7.12k
  dtbl->maxcode[17] = 0xFFFFFL; /* ensures jpeg_huff_decode terminates */
402
403
  /* Compute lookahead tables to speed up decoding.
404
   * First we set all the table entries to 0, indicating "too long";
405
   * then we iterate through the Huffman codes that are short enough and
406
   * fill in all the entries that correspond to bit sequences starting
407
   * with that code.
408
   */
409
410
7.12k
  MEMZERO(dtbl->look_nbits, SIZEOF(dtbl->look_nbits));
411
412
7.12k
  p = 0;
413
64.0k
  for (l = 1; l <= HUFF_LOOKAHEAD; l++) {
414
142k
    for (i = 1; i <= (int) htbl->bits[l]; i++, p++) {
415
      /* l = current code's length, p = its index in huffcode[] & huffval[]. */
416
      /* Generate left-justified code followed by all possible bit sequences */
417
85.2k
      lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);
418
1.67M
      for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) {
419
1.58M
  dtbl->look_nbits[lookbits] = l;
420
1.58M
  dtbl->look_sym[lookbits] = htbl->huffval[p];
421
1.58M
  lookbits++;
422
1.58M
      }
423
85.2k
    }
424
56.8k
  }
425
426
  /* Validate symbols as being reasonable.
427
   * For AC tables, we make no check, but accept all byte values 0..255.
428
   * For DC tables, we require the symbols to be in range 0..15.
429
   * (Tighter bounds could be applied depending on the data depth and mode,
430
   * but this is sufficient to ensure safe decoding.)
431
   */
432
7.12k
  if (isDC) {
433
24.1k
    for (i = 0; i < numsymbols; i++) {
434
21.0k
      int sym = htbl->huffval[i];
435
21.0k
      if (sym < 0 || sym > 15)
436
16
  ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
437
21.0k
    }
438
3.06k
  }
439
7.12k
}
440
441
442
/*
443
 * Out-of-line code for bit fetching.
444
 * Note: current values of get_buffer and bits_left are passed as parameters,
445
 * but are returned in the corresponding fields of the state struct.
446
 *
447
 * On most machines MIN_GET_BITS should be 25 to allow the full 32-bit width
448
 * of get_buffer to be used.  (On machines with wider words, an even larger
449
 * buffer could be used.)  However, on some machines 32-bit shifts are
450
 * quite slow and take time proportional to the number of places shifted.
451
 * (This is true with most PC compilers, for instance.)  In this case it may
452
 * be a win to set MIN_GET_BITS to the minimum value of 15.  This reduces the
453
 * average shift distance at the cost of more calls to jpeg_fill_bit_buffer.
454
 */
455
456
#ifdef SLOW_SHIFT_32
457
#define MIN_GET_BITS  15  /* minimum allowable value */
458
#else
459
9.35M
#define MIN_GET_BITS  (BIT_BUF_SIZE-7)
460
#endif
461
462
463
LOCAL(boolean)
464
jpeg_fill_bit_buffer (bitread_working_state * state,
465
          register bit_buf_type get_buffer, register int bits_left,
466
          int nbits)
467
/* Load up the bit buffer to a depth of at least nbits */
468
2.44M
{
469
  /* Copy heavily used state fields into locals (hopefully registers) */
470
2.44M
  register const JOCTET * next_input_byte = state->next_input_byte;
471
2.44M
  register size_t bytes_in_buffer = state->bytes_in_buffer;
472
2.44M
  j_decompress_ptr cinfo = state->cinfo;
473
474
  /* Attempt to load at least MIN_GET_BITS bits into get_buffer. */
475
  /* (It is assumed that no request will be for more than that many bits.) */
476
  /* We fail to do so only if we hit a marker or are forced to suspend. */
477
478
2.44M
  if (cinfo->unread_marker == 0) { /* cannot advance past a marker */
479
8.99M
    while (bits_left < MIN_GET_BITS) {
480
6.78M
      register int c;
481
482
      /* Attempt to read a byte */
483
6.78M
      if (bytes_in_buffer == 0) {
484
24.4k
  if (! (*cinfo->src->fill_input_buffer) (cinfo))
485
0
    return FALSE;
486
24.4k
  next_input_byte = cinfo->src->next_input_byte;
487
24.4k
  bytes_in_buffer = cinfo->src->bytes_in_buffer;
488
24.4k
      }
489
6.78M
      bytes_in_buffer--;
490
6.78M
      c = GETJOCTET(*next_input_byte++);
491
492
      /* If it's 0xFF, check and discard stuffed zero byte */
493
6.78M
      if (c == 0xFF) {
494
  /* Loop here to discard any padding FF's on terminating marker,
495
   * so that we can save a valid unread_marker value.  NOTE: we will
496
   * accept multiple FF's followed by a 0 as meaning a single FF data
497
   * byte.  This data pattern is not valid according to the standard.
498
   */
499
57.9k
  do {
500
57.9k
    if (bytes_in_buffer == 0) {
501
1.47k
      if (! (*cinfo->src->fill_input_buffer) (cinfo))
502
0
        return FALSE;
503
1.47k
      next_input_byte = cinfo->src->next_input_byte;
504
1.47k
      bytes_in_buffer = cinfo->src->bytes_in_buffer;
505
1.47k
    }
506
57.9k
    bytes_in_buffer--;
507
57.9k
    c = GETJOCTET(*next_input_byte++);
508
57.9k
  } while (c == 0xFF);
509
510
56.5k
  if (c == 0) {
511
    /* Found FF/00, which represents an FF data byte */
512
38.9k
    c = 0xFF;
513
38.9k
  } else {
514
    /* Oops, it's actually a marker indicating end of compressed data.
515
     * Save the marker code for later use.
516
     * Fine point: it might appear that we should save the marker into
517
     * bitread working state, not straight into permanent state.  But
518
     * once we have hit a marker, we cannot need to suspend within the
519
     * current MCU, because we will read no more bytes from the data
520
     * source.  So it is OK to update permanent state right away.
521
     */
522
17.6k
    cinfo->unread_marker = c;
523
    /* See if we need to insert some fake zero bits. */
524
17.6k
    goto no_more_bytes;
525
17.6k
  }
526
56.5k
      }
527
528
      /* OK, load c into get_buffer */
529
6.76M
      get_buffer = (get_buffer << 8) | c;
530
6.76M
      bits_left += 8;
531
6.76M
    } /* end while */
532
2.22M
  } else {
533
237k
  no_more_bytes:
534
    /* We get here if we've read the marker that terminates the compressed
535
     * data segment.  There should be enough bits in the buffer register
536
     * to satisfy the request; if so, no problem.
537
     */
538
237k
    if (nbits > bits_left) {
539
      /* Uh-oh.  Report corrupted data to user and stuff zeroes into
540
       * the data stream, so that we can produce some kind of image.
541
       * We use a nonvolatile flag to ensure that only one warning message
542
       * appears per data segment.
543
       */
544
179k
      if (! ((huff_entropy_ptr) cinfo->entropy)->insufficient_data) {
545
13.4k
  WARNMS(cinfo, JWRN_HIT_MARKER);
546
13.4k
  ((huff_entropy_ptr) cinfo->entropy)->insufficient_data = TRUE;
547
13.4k
      }
548
      /* Fill the buffer with zero bits */
549
179k
      get_buffer <<= MIN_GET_BITS - bits_left;
550
179k
      bits_left = MIN_GET_BITS;
551
179k
    }
552
237k
  }
553
554
  /* Unload the local registers */
555
2.44M
  state->next_input_byte = next_input_byte;
556
2.44M
  state->bytes_in_buffer = bytes_in_buffer;
557
2.44M
  state->get_buffer = get_buffer;
558
2.44M
  state->bits_left = bits_left;
559
560
2.44M
  return TRUE;
561
2.44M
}
562
563
564
/*
565
 * Figure F.12: extend sign bit.
566
 * On some machines, a shift and sub will be faster than a table lookup.
567
 */
568
569
#ifdef AVOID_TABLES
570
571
#define BIT_MASK(nbits)   ((1<<(nbits))-1)
572
#define HUFF_EXTEND(x,s)  ((x) < (1<<((s)-1)) ? (x) - ((1<<(s))-1) : (x))
573
574
#else
575
576
19.9M
#define BIT_MASK(nbits)   bmask[nbits]
577
4.81M
#define HUFF_EXTEND(x,s)  ((x) <= bmask[(s) - 1] ? (x) - bmask[s] : (x))
578
579
static const int bmask[16] =  /* bmask[n] is mask for n rightmost bits */
580
  { 0, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF,
581
    0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF };
582
583
#endif /* AVOID_TABLES */
584
585
586
/*
587
 * Out-of-line code for Huffman code decoding.
588
 */
589
590
LOCAL(int)
591
jpeg_huff_decode (bitread_working_state * state,
592
      register bit_buf_type get_buffer, register int bits_left,
593
      d_derived_tbl * htbl, int min_bits)
594
360k
{
595
360k
  register int l = min_bits;
596
360k
  register INT32 code;
597
598
  /* HUFF_DECODE has determined that the code is at least min_bits */
599
  /* bits long, so fetch that many bits in one swoop. */
600
601
360k
  CHECK_BIT_BUFFER(*state, l, return -1);
602
360k
  code = GET_BITS(l);
603
604
  /* Collect the rest of the Huffman code one bit at a time. */
605
  /* This is per Figure F.16 in the JPEG spec. */
606
607
1.15M
  while (code > htbl->maxcode[l]) {
608
797k
    code <<= 1;
609
797k
    CHECK_BIT_BUFFER(*state, 1, return -1);
610
797k
    code |= GET_BITS(1);
611
797k
    l++;
612
797k
  }
613
614
  /* Unload the local registers */
615
360k
  state->get_buffer = get_buffer;
616
360k
  state->bits_left = bits_left;
617
618
  /* With garbage input we may reach the sentinel value l = 17. */
619
620
360k
  if (l > 16) {
621
5.09k
    WARNMS(state->cinfo, JWRN_HUFF_BAD_CODE);
622
5.09k
    return 0;     /* fake a zero as the safest result */
623
5.09k
  }
624
625
354k
  return htbl->pub->huffval[ (int) (code + htbl->valoffset[l]) ];
626
360k
}
627
628
629
/*
630
 * Finish up at the end of a Huffman-compressed scan.
631
 */
632
633
METHODDEF(void)
634
finish_pass_huff (j_decompress_ptr cinfo)
635
339k
{
636
339k
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
637
638
  /* Throw away any unused bits remaining in bit buffer; */
639
  /* include any full bytes in next_marker's count of discarded bytes */
640
339k
  cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
641
339k
  entropy->bitstate.bits_left = 0;
642
339k
}
643
644
645
/*
646
 * Check for a restart marker & resynchronize decoder.
647
 * Returns FALSE if must suspend.
648
 */
649
650
LOCAL(boolean)
651
process_restart (j_decompress_ptr cinfo)
652
335k
{
653
335k
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
654
335k
  int ci;
655
656
335k
  finish_pass_huff(cinfo);
657
658
  /* Advance past the RSTn marker */
659
335k
  if (! (*cinfo->marker->read_restart_marker) (cinfo))
660
0
    return FALSE;
661
662
  /* Re-initialize DC predictions to 0 */
663
978k
  for (ci = 0; ci < cinfo->comps_in_scan; ci++)
664
643k
    entropy->saved.last_dc_val[ci] = 0;
665
  /* Re-init EOB run count, too */
666
335k
  entropy->saved.EOBRUN = 0;
667
668
  /* Reset restart counter */
669
335k
  entropy->restarts_to_go = cinfo->restart_interval;
670
671
  /* Reset out-of-data flag, unless read_restart_marker left us smack up
672
   * against a marker.  In that case we will end up treating the next data
673
   * segment as empty, and we can avoid producing bogus output pixels by
674
   * leaving the flag set.
675
   */
676
335k
  if (cinfo->unread_marker == 0)
677
18.0k
    entropy->insufficient_data = FALSE;
678
679
335k
  return TRUE;
680
335k
}
681
682
683
/*
684
 * Huffman MCU decoding.
685
 * Each of these routines decodes and returns one MCU's worth of
686
 * Huffman-compressed coefficients. 
687
 * The coefficients are reordered from zigzag order into natural array order,
688
 * but are not dequantized.
689
 *
690
 * The i'th block of the MCU is stored into the block pointed to by
691
 * MCU_data[i].  WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
692
 * (Wholesale zeroing is usually a little faster than retail...)
693
 *
694
 * We return FALSE if data source requested suspension.  In that case no
695
 * changes have been made to permanent state.  (Exception: some output
696
 * coefficients may already have been assigned.  This is harmless for
697
 * spectral selection, since we'll just re-assign them on the next call.
698
 * Successive approximation AC refinement has to be more careful, however.)
699
 */
700
701
/*
702
 * MCU decoding for DC initial scan (either spectral selection,
703
 * or first pass of successive approximation).
704
 */
705
706
METHODDEF(boolean)
707
decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKARRAY MCU_data)
708
1.30M
{
709
1.30M
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
710
1.30M
  int Al = cinfo->Al;
711
1.30M
  register int s, r;
712
1.30M
  int blkn, ci;
713
1.30M
  JBLOCKROW block;
714
1.30M
  BITREAD_STATE_VARS;
715
1.30M
  savable_state state;
716
1.30M
  d_derived_tbl * tbl;
717
1.30M
  jpeg_component_info * compptr;
718
719
  /* Process restart marker if needed; may have to suspend */
720
1.30M
  if (cinfo->restart_interval) {
721
10.7k
    if (entropy->restarts_to_go == 0)
722
1.50k
      if (! process_restart(cinfo))
723
0
  return FALSE;
724
10.7k
  }
725
726
  /* If we've run out of data, just leave the MCU set to zeroes.
727
   * This way, we return uniform gray for the remainder of the segment.
728
   */
729
1.30M
  if (! entropy->insufficient_data) {
730
731
    /* Load up working state */
732
43.9k
    BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
733
43.9k
    ASSIGN_STATE(state, entropy->saved);
734
735
    /* Outer loop handles each block in the MCU */
736
737
293k
    for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
738
249k
      block = MCU_data[blkn];
739
249k
      ci = cinfo->MCU_membership[blkn];
740
249k
      compptr = cinfo->cur_comp_info[ci];
741
249k
      tbl = entropy->derived_tbls[compptr->dc_tbl_no];
742
743
      /* Decode a single block's worth of coefficients */
744
745
      /* Section F.2.2.1: decode the DC coefficient difference */
746
249k
      HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
747
249k
      if (s) {
748
99.0k
  CHECK_BIT_BUFFER(br_state, s, return FALSE);
749
99.0k
  r = GET_BITS(s);
750
99.0k
  s = HUFF_EXTEND(r, s);
751
99.0k
      }
752
753
      /* Convert DC difference to actual value, update last_dc_val */
754
249k
      s += state.last_dc_val[ci];
755
249k
      state.last_dc_val[ci] = s;
756
      /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
757
249k
      (*block)[0] = (JCOEF) (s << Al);
758
249k
    }
759
760
    /* Completed MCU, so update state */
761
43.9k
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
762
43.9k
    ASSIGN_STATE(entropy->saved, state);
763
43.9k
  }
764
765
  /* Account for restart interval if using restarts */
766
1.30M
  if (cinfo->restart_interval)
767
10.7k
    entropy->restarts_to_go--;
768
769
1.30M
  return TRUE;
770
1.30M
}
771
772
773
/*
774
 * MCU decoding for AC initial scan (either spectral selection,
775
 * or first pass of successive approximation).
776
 */
777
778
METHODDEF(boolean)
779
decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKARRAY MCU_data)
780
5.25M
{
781
5.25M
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
782
5.25M
  register int s, k, r;
783
5.25M
  unsigned int EOBRUN;
784
5.25M
  int Se, Al;
785
5.25M
  const int * natural_order;
786
5.25M
  JBLOCKROW block;
787
5.25M
  BITREAD_STATE_VARS;
788
5.25M
  d_derived_tbl * tbl;
789
790
  /* Process restart marker if needed; may have to suspend */
791
5.25M
  if (cinfo->restart_interval) {
792
117k
    if (entropy->restarts_to_go == 0)
793
7.30k
      if (! process_restart(cinfo))
794
0
  return FALSE;
795
117k
  }
796
797
  /* If we've run out of data, just leave the MCU set to zeroes.
798
   * This way, we return uniform gray for the remainder of the segment.
799
   */
800
5.25M
  if (! entropy->insufficient_data) {
801
802
    /* Load up working state.
803
     * We can avoid loading/saving bitread state if in an EOB run.
804
     */
805
333k
    EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
806
807
    /* There is always only one block per MCU */
808
809
333k
    if (EOBRUN)      /* if it's a band of zeroes... */
810
213k
      EOBRUN--;      /* ...process it now (we do nothing) */
811
119k
    else {
812
119k
      BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
813
119k
      Se = cinfo->Se;
814
119k
      Al = cinfo->Al;
815
119k
      natural_order = cinfo->natural_order;
816
119k
      block = MCU_data[0];
817
119k
      tbl = entropy->ac_derived_tbl;
818
819
724k
      for (k = cinfo->Ss; k <= Se; k++) {
820
704k
  HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
821
704k
  r = s >> 4;
822
704k
  s &= 15;
823
704k
  if (s) {
824
603k
    k += r;
825
603k
    CHECK_BIT_BUFFER(br_state, s, return FALSE);
826
603k
    r = GET_BITS(s);
827
603k
    s = HUFF_EXTEND(r, s);
828
    /* Scale and output coefficient in natural (dezigzagged) order */
829
603k
    (*block)[natural_order[k]] = (JCOEF) (s << Al);
830
603k
  } else {
831
101k
    if (r != 15) { /* EOBr, run length is 2^r + appended bits */
832
100k
      if (r) {   /* EOBr, r > 0 */
833
20.8k
        EOBRUN = 1 << r;
834
20.8k
        CHECK_BIT_BUFFER(br_state, r, return FALSE);
835
20.8k
        r = GET_BITS(r);
836
20.8k
        EOBRUN += r;
837
20.8k
        EOBRUN--;   /* this band is processed at this moment */
838
20.8k
      }
839
100k
      break;   /* force end-of-band */
840
100k
    }
841
864
    k += 15;    /* ZRL: skip 15 zeroes in band */
842
864
  }
843
704k
      }
844
845
119k
      BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
846
119k
    }
847
848
    /* Completed MCU, so update state */
849
333k
    entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
850
333k
  }
851
852
  /* Account for restart interval if using restarts */
853
5.25M
  if (cinfo->restart_interval)
854
117k
    entropy->restarts_to_go--;
855
856
5.25M
  return TRUE;
857
5.25M
}
858
859
860
/*
861
 * MCU decoding for DC successive approximation refinement scan.
862
 * Note: we assume such scans can be multi-component,
863
 * although the spec is not very clear on the point.
864
 */
865
866
METHODDEF(boolean)
867
decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKARRAY MCU_data)
868
305k
{
869
305k
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
870
305k
  JCOEF p1;
871
305k
  int blkn;
872
305k
  BITREAD_STATE_VARS;
873
874
  /* Process restart marker if needed; may have to suspend */
875
305k
  if (cinfo->restart_interval) {
876
201k
    if (entropy->restarts_to_go == 0)
877
104k
      if (! process_restart(cinfo))
878
0
  return FALSE;
879
201k
  }
880
881
  /* Not worth the cycles to check insufficient_data here,
882
   * since we will not change the data anyway if we read zeroes.
883
   */
884
885
  /* Load up working state */
886
305k
  BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
887
888
305k
  p1 = 1 << cinfo->Al;    /* 1 in the bit position being coded */
889
890
  /* Outer loop handles each block in the MCU */
891
892
1.09M
  for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
893
    /* Encoded data is simply the next bit of the two's-complement DC value */
894
788k
    CHECK_BIT_BUFFER(br_state, 1, return FALSE);
895
788k
    if (GET_BITS(1))
896
84.7k
      MCU_data[blkn][0][0] |= p1;
897
    /* Note: since we use |=, repeating the assignment later is safe */
898
788k
  }
899
900
  /* Completed MCU, so update state */
901
305k
  BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
902
903
  /* Account for restart interval if using restarts */
904
305k
  if (cinfo->restart_interval)
905
201k
    entropy->restarts_to_go--;
906
907
305k
  return TRUE;
908
305k
}
909
910
911
/*
912
 * MCU decoding for AC successive approximation refinement scan.
913
 */
914
915
METHODDEF(boolean)
916
decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKARRAY MCU_data)
917
1.44M
{
918
1.44M
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
919
1.44M
  register int s, k, r;
920
1.44M
  unsigned int EOBRUN;
921
1.44M
  int Se;
922
1.44M
  JCOEF p1, m1;
923
1.44M
  const int * natural_order;
924
1.44M
  JBLOCKROW block;
925
1.44M
  JCOEFPTR thiscoef;
926
1.44M
  BITREAD_STATE_VARS;
927
1.44M
  d_derived_tbl * tbl;
928
1.44M
  int num_newnz;
929
1.44M
  int newnz_pos[DCTSIZE2];
930
931
  /* Process restart marker if needed; may have to suspend */
932
1.44M
  if (cinfo->restart_interval) {
933
850k
    if (entropy->restarts_to_go == 0)
934
48.8k
      if (! process_restart(cinfo))
935
0
  return FALSE;
936
850k
  }
937
938
  /* If we've run out of data, don't modify the MCU.
939
   */
940
1.44M
  if (! entropy->insufficient_data) {
941
942
342k
    Se = cinfo->Se;
943
342k
    p1 = 1 << cinfo->Al;  /* 1 in the bit position being coded */
944
342k
    m1 = -p1;     /* -1 in the bit position being coded */
945
342k
    natural_order = cinfo->natural_order;
946
947
    /* Load up working state */
948
342k
    BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
949
342k
    EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
950
951
    /* There is always only one block per MCU */
952
342k
    block = MCU_data[0];
953
342k
    tbl = entropy->ac_derived_tbl;
954
955
    /* If we are forced to suspend, we must undo the assignments to any newly
956
     * nonzero coefficients in the block, because otherwise we'd get confused
957
     * next time about which coefficients were already nonzero.
958
     * But we need not undo addition of bits to already-nonzero coefficients;
959
     * instead, we can test the current bit to see if we already did it.
960
     */
961
342k
    num_newnz = 0;
962
963
    /* initialize coefficient loop counter to start of band */
964
342k
    k = cinfo->Ss;
965
966
342k
    if (EOBRUN == 0) {
967
476k
      do {
968
476k
  HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
969
476k
  r = s >> 4;
970
476k
  s &= 15;
971
476k
  if (s) {
972
386k
    if (s != 1)    /* size of new coef should always be 1 */
973
18.1k
      WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
974
386k
    CHECK_BIT_BUFFER(br_state, 1, goto undoit);
975
386k
    if (GET_BITS(1))
976
190k
      s = p1;    /* newly nonzero coef is positive */
977
196k
    else
978
196k
      s = m1;   /* newly nonzero coef is negative */
979
386k
  } else {
980
89.3k
    if (r != 15) {
981
86.2k
      EOBRUN = 1 << r;  /* EOBr, run length is 2^r + appended bits */
982
86.2k
      if (r) {
983
22.5k
        CHECK_BIT_BUFFER(br_state, r, goto undoit);
984
22.5k
        r = GET_BITS(r);
985
22.5k
        EOBRUN += r;
986
22.5k
      }
987
86.2k
      break;   /* rest of block is handled by EOB logic */
988
86.2k
    }
989
    /* note s = 0 for processing ZRL */
990
89.3k
  }
991
  /* Advance over already-nonzero coefs and r still-zero coefs,
992
   * appending correction bits to the nonzeroes.  A correction bit is 1
993
   * if the absolute value of the coefficient must be increased.
994
   */
995
1.50M
  do {
996
1.50M
    thiscoef = *block + natural_order[k];
997
1.50M
    if (*thiscoef) {
998
416k
      CHECK_BIT_BUFFER(br_state, 1, goto undoit);
999
416k
      if (GET_BITS(1)) {
1000
166k
        if ((*thiscoef & p1) == 0) { /* do nothing if already set it */
1001
164k
    if (*thiscoef >= 0)
1002
83.1k
      *thiscoef += p1;
1003
80.9k
    else
1004
80.9k
      *thiscoef += m1;
1005
164k
        }
1006
166k
      }
1007
1.09M
    } else {
1008
1.09M
      if (--r < 0)
1009
377k
        break;   /* reached target zero coefficient */
1010
1.09M
    }
1011
1.13M
    k++;
1012
1.13M
  } while (k <= Se);
1013
390k
  if (s) {
1014
386k
    int pos = natural_order[k];
1015
    /* Output newly nonzero coefficient */
1016
386k
    (*block)[pos] = (JCOEF) s;
1017
    /* Remember its position in case we have to suspend */
1018
386k
    newnz_pos[num_newnz++] = pos;
1019
386k
  }
1020
390k
  k++;
1021
390k
      } while (k <= Se);
1022
100k
    }
1023
1024
342k
    if (EOBRUN) {
1025
      /* Scan any remaining coefficient positions after the end-of-band
1026
       * (the last newly nonzero coefficient, if any).  Append a correction
1027
       * bit to each already-nonzero coefficient.  A correction bit is 1
1028
       * if the absolute value of the coefficient must be increased.
1029
       */
1030
12.9M
      do {
1031
12.9M
  thiscoef = *block + natural_order[k];
1032
12.9M
  if (*thiscoef) {
1033
172k
    CHECK_BIT_BUFFER(br_state, 1, goto undoit);
1034
172k
    if (GET_BITS(1)) {
1035
37.0k
      if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
1036
24.0k
        if (*thiscoef >= 0)
1037
12.2k
    *thiscoef += p1;
1038
11.8k
        else
1039
11.8k
    *thiscoef += m1;
1040
24.0k
      }
1041
37.0k
    }
1042
172k
  }
1043
12.9M
  k++;
1044
12.9M
      } while (k <= Se);
1045
      /* Count one block completed in EOB run */
1046
327k
      EOBRUN--;
1047
327k
    }
1048
1049
    /* Completed MCU, so update state */
1050
342k
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
1051
342k
    entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
1052
342k
  }
1053
1054
  /* Account for restart interval if using restarts */
1055
1.44M
  if (cinfo->restart_interval)
1056
850k
    entropy->restarts_to_go--;
1057
1058
1.44M
  return TRUE;
1059
1060
0
undoit:
1061
  /* Re-zero any output coefficients that we made newly nonzero */
1062
0
  while (num_newnz)
1063
0
    (*block)[newnz_pos[--num_newnz]] = 0;
1064
1065
0
  return FALSE;
1066
1.44M
}
1067
1068
1069
/*
1070
 * Decode one MCU's worth of Huffman-compressed coefficients,
1071
 * partial blocks.
1072
 */
1073
1074
METHODDEF(boolean)
1075
decode_mcu_sub (j_decompress_ptr cinfo, JBLOCKARRAY MCU_data)
1076
1.95M
{
1077
1.95M
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
1078
1.95M
  const int * natural_order;
1079
1.95M
  int Se, blkn;
1080
1.95M
  BITREAD_STATE_VARS;
1081
1.95M
  savable_state state;
1082
1083
  /* Process restart marker if needed; may have to suspend */
1084
1.95M
  if (cinfo->restart_interval) {
1085
575k
    if (entropy->restarts_to_go == 0)
1086
20.5k
      if (! process_restart(cinfo))
1087
0
  return FALSE;
1088
575k
  }
1089
1090
  /* If we've run out of data, just leave the MCU set to zeroes.
1091
   * This way, we return uniform gray for the remainder of the segment.
1092
   */
1093
1.95M
  if (! entropy->insufficient_data) {
1094
1095
3.00k
    natural_order = cinfo->natural_order;
1096
3.00k
    Se = cinfo->lim_Se;
1097
1098
    /* Load up working state */
1099
3.00k
    BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
1100
3.00k
    ASSIGN_STATE(state, entropy->saved);
1101
1102
    /* Outer loop handles each block in the MCU */
1103
1104
7.25k
    for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
1105
4.24k
      JBLOCKROW block = MCU_data[blkn];
1106
4.24k
      d_derived_tbl * htbl;
1107
4.24k
      register int s, k, r;
1108
4.24k
      int coef_limit, ci;
1109
1110
      /* Decode a single block's worth of coefficients */
1111
1112
      /* Section F.2.2.1: decode the DC coefficient difference */
1113
4.24k
      htbl = entropy->dc_cur_tbls[blkn];
1114
4.24k
      HUFF_DECODE(s, br_state, htbl, return FALSE, label1);
1115
1116
4.24k
      htbl = entropy->ac_cur_tbls[blkn];
1117
4.24k
      k = 1;
1118
4.24k
      coef_limit = entropy->coef_limit[blkn];
1119
4.24k
      if (coef_limit) {
1120
  /* Convert DC difference to actual value, update last_dc_val */
1121
4.24k
  if (s) {
1122
1.72k
    CHECK_BIT_BUFFER(br_state, s, return FALSE);
1123
1.72k
    r = GET_BITS(s);
1124
1.72k
    s = HUFF_EXTEND(r, s);
1125
1.72k
  }
1126
4.24k
  ci = cinfo->MCU_membership[blkn];
1127
4.24k
  s += state.last_dc_val[ci];
1128
4.24k
  state.last_dc_val[ci] = s;
1129
  /* Output the DC coefficient */
1130
4.24k
  (*block)[0] = (JCOEF) s;
1131
1132
  /* Section F.2.2.2: decode the AC coefficients */
1133
  /* Since zeroes are skipped, output area must be cleared beforehand */
1134
17.8k
  for (; k < coef_limit; k++) {
1135
14.3k
    HUFF_DECODE(s, br_state, htbl, return FALSE, label2);
1136
1137
14.3k
    r = s >> 4;
1138
14.3k
    s &= 15;
1139
1140
14.3k
    if (s) {
1141
13.5k
      k += r;
1142
13.5k
      CHECK_BIT_BUFFER(br_state, s, return FALSE);
1143
13.5k
      r = GET_BITS(s);
1144
13.5k
      s = HUFF_EXTEND(r, s);
1145
      /* Output coefficient in natural (dezigzagged) order.
1146
       * Note: the extra entries in natural_order[] will save us
1147
       * if k > Se, which could happen if the data is corrupted.
1148
       */
1149
13.5k
      (*block)[natural_order[k]] = (JCOEF) s;
1150
13.5k
    } else {
1151
810
      if (r != 15)
1152
810
        goto EndOfBlock;
1153
0
      k += 15;
1154
0
    }
1155
14.3k
  }
1156
4.24k
      } else {
1157
0
  if (s) {
1158
0
    CHECK_BIT_BUFFER(br_state, s, return FALSE);
1159
0
    DROP_BITS(s);
1160
0
  }
1161
0
      }
1162
1163
      /* Section F.2.2.2: decode the AC coefficients */
1164
      /* In this path we just discard the values */
1165
6.88k
      for (; k <= Se; k++) {
1166
3.78k
  HUFF_DECODE(s, br_state, htbl, return FALSE, label3);
1167
1168
3.78k
  r = s >> 4;
1169
3.78k
  s &= 15;
1170
1171
3.78k
  if (s) {
1172
3.44k
    k += r;
1173
3.44k
    CHECK_BIT_BUFFER(br_state, s, return FALSE);
1174
3.44k
    DROP_BITS(s);
1175
3.44k
  } else {
1176
342
    if (r != 15)
1177
342
      break;
1178
0
    k += 15;
1179
0
  }
1180
3.78k
      }
1181
1182
4.24k
      EndOfBlock: ;
1183
4.24k
    }
1184
1185
    /* Completed MCU, so update state */
1186
3.00k
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
1187
3.00k
    ASSIGN_STATE(entropy->saved, state);
1188
3.00k
  }
1189
1190
  /* Account for restart interval if using restarts */
1191
1.95M
  if (cinfo->restart_interval)
1192
575k
    entropy->restarts_to_go--;
1193
1194
1.95M
  return TRUE;
1195
1.95M
}
1196
1197
1198
/*
1199
 * Decode one MCU's worth of Huffman-compressed coefficients,
1200
 * full-size blocks.
1201
 */
1202
1203
METHODDEF(boolean)
1204
decode_mcu (j_decompress_ptr cinfo, JBLOCKARRAY MCU_data)
1205
2.43M
{
1206
2.43M
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
1207
2.43M
  int blkn;
1208
2.43M
  BITREAD_STATE_VARS;
1209
2.43M
  savable_state state;
1210
1211
  /* Process restart marker if needed; may have to suspend */
1212
2.43M
  if (cinfo->restart_interval) {
1213
702k
    if (entropy->restarts_to_go == 0)
1214
152k
      if (! process_restart(cinfo))
1215
0
  return FALSE;
1216
702k
  }
1217
1218
  /* If we've run out of data, just leave the MCU set to zeroes.
1219
   * This way, we return uniform gray for the remainder of the segment.
1220
   */
1221
2.43M
  if (! entropy->insufficient_data) {
1222
1223
    /* Load up working state */
1224
687k
    BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
1225
687k
    ASSIGN_STATE(state, entropy->saved);
1226
1227
    /* Outer loop handles each block in the MCU */
1228
1229
3.42M
    for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
1230
2.73M
      JBLOCKROW block = MCU_data[blkn];
1231
2.73M
      d_derived_tbl * htbl;
1232
2.73M
      register int s, k, r;
1233
2.73M
      int coef_limit, ci;
1234
1235
      /* Decode a single block's worth of coefficients */
1236
1237
      /* Section F.2.2.1: decode the DC coefficient difference */
1238
2.73M
      htbl = entropy->dc_cur_tbls[blkn];
1239
2.73M
      HUFF_DECODE(s, br_state, htbl, return FALSE, label1);
1240
1241
2.73M
      htbl = entropy->ac_cur_tbls[blkn];
1242
2.73M
      k = 1;
1243
2.73M
      coef_limit = entropy->coef_limit[blkn];
1244
2.73M
      if (coef_limit) {
1245
  /* Convert DC difference to actual value, update last_dc_val */
1246
2.73M
  if (s) {
1247
466k
    CHECK_BIT_BUFFER(br_state, s, return FALSE);
1248
466k
    r = GET_BITS(s);
1249
466k
    s = HUFF_EXTEND(r, s);
1250
466k
  }
1251
2.73M
  ci = cinfo->MCU_membership[blkn];
1252
2.73M
  s += state.last_dc_val[ci];
1253
2.73M
  state.last_dc_val[ci] = s;
1254
  /* Output the DC coefficient */
1255
2.73M
  (*block)[0] = (JCOEF) s;
1256
1257
  /* Section F.2.2.2: decode the AC coefficients */
1258
  /* Since zeroes are skipped, output area must be cleared beforehand */
1259
6.36M
  for (; k < coef_limit; k++) {
1260
6.14M
    HUFF_DECODE(s, br_state, htbl, return FALSE, label2);
1261
1262
6.14M
    r = s >> 4;
1263
6.14M
    s &= 15;
1264
1265
6.14M
    if (s) {
1266
3.62M
      k += r;
1267
3.62M
      CHECK_BIT_BUFFER(br_state, s, return FALSE);
1268
3.62M
      r = GET_BITS(s);
1269
3.62M
      s = HUFF_EXTEND(r, s);
1270
      /* Output coefficient in natural (dezigzagged) order.
1271
       * Note: the extra entries in jpeg_natural_order[] will save us
1272
       * if k >= DCTSIZE2, which could happen if the data is corrupted.
1273
       */
1274
3.62M
      (*block)[jpeg_natural_order[k]] = (JCOEF) s;
1275
3.62M
    } else {
1276
2.51M
      if (r != 15)
1277
2.50M
        goto EndOfBlock;
1278
3.68k
      k += 15;
1279
3.68k
    }
1280
6.14M
  }
1281
2.73M
      } else {
1282
0
  if (s) {
1283
0
    CHECK_BIT_BUFFER(br_state, s, return FALSE);
1284
0
    DROP_BITS(s);
1285
0
  }
1286
0
      }
1287
1288
      /* Section F.2.2.2: decode the AC coefficients */
1289
      /* In this path we just discard the values */
1290
1.94M
      for (; k < DCTSIZE2; k++) {
1291
1.93M
  HUFF_DECODE(s, br_state, htbl, return FALSE, label3);
1292
1293
1.93M
  r = s >> 4;
1294
1.93M
  s &= 15;
1295
1296
1.93M
  if (s) {
1297
1.70M
    k += r;
1298
1.70M
    CHECK_BIT_BUFFER(br_state, s, return FALSE);
1299
1.70M
    DROP_BITS(s);
1300
1.70M
  } else {
1301
228k
    if (r != 15)
1302
215k
      break;
1303
13.0k
    k += 15;
1304
13.0k
  }
1305
1.93M
      }
1306
1307
2.73M
      EndOfBlock: ;
1308
2.73M
    }
1309
1310
    /* Completed MCU, so update state */
1311
687k
    BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
1312
687k
    ASSIGN_STATE(entropy->saved, state);
1313
687k
  }
1314
1315
  /* Account for restart interval if using restarts */
1316
2.43M
  if (cinfo->restart_interval)
1317
702k
    entropy->restarts_to_go--;
1318
1319
2.43M
  return TRUE;
1320
2.43M
}
1321
1322
1323
/*
1324
 * Initialize for a Huffman-compressed scan.
1325
 */
1326
1327
METHODDEF(void)
1328
start_pass_huff_decoder (j_decompress_ptr cinfo)
1329
4.07k
{
1330
4.07k
  huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
1331
4.07k
  int ci, blkn, tbl, i;
1332
4.07k
  jpeg_component_info * compptr;
1333
1334
4.07k
  if (cinfo->progressive_mode) {
1335
    /* Validate progressive scan parameters */
1336
3.40k
    if (cinfo->Ss == 0) {
1337
667
      if (cinfo->Se != 0)
1338
4
  goto bad;
1339
2.73k
    } else {
1340
      /* need not check Ss/Se < 0 since they came from unsigned bytes */
1341
2.73k
      if (cinfo->Se < cinfo->Ss || cinfo->Se > cinfo->lim_Se)
1342
16
  goto bad;
1343
      /* AC scans may have only one component */
1344
2.71k
      if (cinfo->comps_in_scan != 1)
1345
1
  goto bad;
1346
2.71k
    }
1347
3.38k
    if (cinfo->Ah != 0) {
1348
      /* Successive approximation refinement scan: must have Al = Ah-1. */
1349
2.03k
      if (cinfo->Ah-1 != cinfo->Al)
1350
17
  goto bad;
1351
2.03k
    }
1352
3.36k
    if (cinfo->Al > 13) { /* need not check for < 0 */
1353
      /* Arguably the maximum Al value should be less than 13 for 8-bit
1354
       * precision, but the spec doesn't say so, and we try to be liberal
1355
       * about what we accept.  Note: large Al values could result in
1356
       * out-of-range DC coefficients during early scans, leading to bizarre
1357
       * displays due to overflows in the IDCT math.  But we won't crash.
1358
       */
1359
39
      bad:
1360
39
      ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
1361
39
         cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
1362
39
    }
1363
    /* Update progression status, and verify that scan order is legal.
1364
     * Note that inter-scan inconsistencies are treated as warnings
1365
     * not fatal errors ... not clear if this is right way to behave.
1366
     */
1367
7.98k
    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
1368
4.58k
      int coefi, cindex = cinfo->cur_comp_info[ci]->component_index;
1369
4.58k
      int *coef_bit_ptr = & cinfo->coef_bits[cindex][0];
1370
4.58k
      if (cinfo->Ss && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
1371
2.44k
  WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
1372
56.6k
      for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
1373
52.0k
  int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
1374
52.0k
  if (cinfo->Ah != expected)
1375
31.7k
    WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
1376
52.0k
  coef_bit_ptr[coefi] = cinfo->Al;
1377
52.0k
      }
1378
4.58k
    }
1379
1380
    /* Select MCU decoding routine */
1381
3.40k
    if (cinfo->Ah == 0) {
1382
1.34k
      if (cinfo->Ss == 0)
1383
579
  entropy->pub.decode_mcu = decode_mcu_DC_first;
1384
763
      else
1385
763
  entropy->pub.decode_mcu = decode_mcu_AC_first;
1386
2.05k
    } else {
1387
2.05k
      if (cinfo->Ss == 0)
1388
74
  entropy->pub.decode_mcu = decode_mcu_DC_refine;
1389
1.98k
      else
1390
1.98k
  entropy->pub.decode_mcu = decode_mcu_AC_refine;
1391
2.05k
    }
1392
1393
7.97k
    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
1394
4.56k
      compptr = cinfo->cur_comp_info[ci];
1395
      /* Make sure requested tables are present, and compute derived tables.
1396
       * We may build same derived table more than once, but it's not expensive.
1397
       */
1398
4.56k
      if (cinfo->Ss == 0) {
1399
1.86k
  if (cinfo->Ah == 0) { /* DC refinement needs no table */
1400
1.68k
    tbl = compptr->dc_tbl_no;
1401
1.68k
    jpeg_make_d_derived_tbl(cinfo, TRUE, tbl,
1402
1.68k
          & entropy->derived_tbls[tbl]);
1403
1.68k
  }
1404
2.70k
      } else {
1405
2.70k
  tbl = compptr->ac_tbl_no;
1406
2.70k
  jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
1407
2.70k
        & entropy->derived_tbls[tbl]);
1408
  /* remember the single active table */
1409
2.70k
  entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
1410
2.70k
      }
1411
      /* Initialize DC predictions to 0 */
1412
4.56k
      entropy->saved.last_dc_val[ci] = 0;
1413
4.56k
    }
1414
1415
    /* Initialize private state variables */
1416
3.40k
    entropy->saved.EOBRUN = 0;
1417
3.40k
  } else {
1418
    /* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
1419
     * This ought to be an error condition, but we make it a warning because
1420
     * there are some baseline files out there with all zeroes in these bytes.
1421
     */
1422
669
    if (cinfo->Ss != 0 || cinfo->Ah != 0 || cinfo->Al != 0 ||
1423
669
  ((cinfo->is_baseline || cinfo->Se < DCTSIZE2) &&
1424
342
  cinfo->Se != cinfo->lim_Se))
1425
362
      WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);
1426
1427
    /* Select MCU decoding routine */
1428
    /* We retain the hard-coded case for full-size blocks.
1429
     * This is not necessary, but it appears that this version is slightly
1430
     * more performant in the given implementation.
1431
     * With an improved implementation we would prefer a single optimized
1432
     * function.
1433
     */
1434
669
    if (cinfo->lim_Se != DCTSIZE2-1)
1435
52
      entropy->pub.decode_mcu = decode_mcu_sub;
1436
617
    else
1437
617
      entropy->pub.decode_mcu = decode_mcu;
1438
1439
2.05k
    for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
1440
1.38k
      compptr = cinfo->cur_comp_info[ci];
1441
      /* Compute derived values for Huffman tables */
1442
      /* We may do this more than once for a table, but it's not expensive */
1443
1.38k
      tbl = compptr->dc_tbl_no;
1444
1.38k
      jpeg_make_d_derived_tbl(cinfo, TRUE, tbl,
1445
1.38k
            & entropy->dc_derived_tbls[tbl]);
1446
1.38k
      if (cinfo->lim_Se) { /* AC needs no table when not present */
1447
1.34k
  tbl = compptr->ac_tbl_no;
1448
1.34k
  jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
1449
1.34k
        & entropy->ac_derived_tbls[tbl]);
1450
1.34k
      }
1451
      /* Initialize DC predictions to 0 */
1452
1.38k
      entropy->saved.last_dc_val[ci] = 0;
1453
1.38k
    }
1454
1455
    /* Precalculate decoding info for each block in an MCU of this scan */
1456
3.78k
    for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
1457
3.11k
      ci = cinfo->MCU_membership[blkn];
1458
3.11k
      compptr = cinfo->cur_comp_info[ci];
1459
      /* Precalculate which table to use for each block */
1460
3.11k
      entropy->dc_cur_tbls[blkn] = entropy->dc_derived_tbls[compptr->dc_tbl_no];
1461
3.11k
      entropy->ac_cur_tbls[blkn] =  /* AC needs no table when not present */
1462
3.11k
  cinfo->lim_Se ? entropy->ac_derived_tbls[compptr->ac_tbl_no] : NULL;
1463
      /* Decide whether we really care about the coefficient values */
1464
3.11k
      if (compptr->component_needed) {
1465
3.11k
  ci = compptr->DCT_v_scaled_size;
1466
3.11k
  i = compptr->DCT_h_scaled_size;
1467
3.11k
  switch (cinfo->lim_Se) {
1468
28
  case (1*1-1):
1469
28
    entropy->coef_limit[blkn] = 1;
1470
28
    break;
1471
0
  case (2*2-1):
1472
0
    if (ci <= 0 || ci > 2) ci = 2;
1473
0
    if (i <= 0 || i > 2) i = 2;
1474
0
    entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order2[ci - 1][i - 1];
1475
0
    break;
1476
29
  case (3*3-1):
1477
29
    if (ci <= 0 || ci > 3) ci = 3;
1478
29
    if (i <= 0 || i > 3) i = 3;
1479
29
    entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order3[ci - 1][i - 1];
1480
29
    break;
1481
13
  case (4*4-1):
1482
13
    if (ci <= 0 || ci > 4) ci = 4;
1483
13
    if (i <= 0 || i > 4) i = 4;
1484
13
    entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order4[ci - 1][i - 1];
1485
13
    break;
1486
0
  case (5*5-1):
1487
0
    if (ci <= 0 || ci > 5) ci = 5;
1488
0
    if (i <= 0 || i > 5) i = 5;
1489
0
    entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order5[ci - 1][i - 1];
1490
0
    break;
1491
4
  case (6*6-1):
1492
4
    if (ci <= 0 || ci > 6) ci = 6;
1493
4
    if (i <= 0 || i > 6) i = 6;
1494
4
    entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order6[ci - 1][i - 1];
1495
4
    break;
1496
0
  case (7*7-1):
1497
0
    if (ci <= 0 || ci > 7) ci = 7;
1498
0
    if (i <= 0 || i > 7) i = 7;
1499
0
    entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order7[ci - 1][i - 1];
1500
0
    break;
1501
3.04k
  default:
1502
3.04k
    if (ci <= 0 || ci > 8) ci = 8;
1503
3.04k
    if (i <= 0 || i > 8) i = 8;
1504
3.04k
    entropy->coef_limit[blkn] = 1 + jpeg_zigzag_order[ci - 1][i - 1];
1505
3.11k
  }
1506
3.11k
      } else {
1507
0
  entropy->coef_limit[blkn] = 0;
1508
0
      }
1509
3.11k
    }
1510
669
  }
1511
1512
  /* Initialize bitread state variables */
1513
4.07k
  entropy->bitstate.bits_left = 0;
1514
4.07k
  entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
1515
4.07k
  entropy->insufficient_data = FALSE;
1516
1517
  /* Initialize restart counter */
1518
4.07k
  entropy->restarts_to_go = cinfo->restart_interval;
1519
4.07k
}
1520
1521
1522
/*
1523
 * Module initialization routine for Huffman entropy decoding.
1524
 */
1525
1526
GLOBAL(void)
1527
jinit_huff_decoder (j_decompress_ptr cinfo)
1528
875
{
1529
875
  huff_entropy_ptr entropy;
1530
875
  int i;
1531
1532
875
  entropy = (huff_entropy_ptr) (*cinfo->mem->alloc_small)
1533
875
    ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(huff_entropy_decoder));
1534
875
  cinfo->entropy = &entropy->pub;
1535
875
  entropy->pub.start_pass = start_pass_huff_decoder;
1536
875
  entropy->pub.finish_pass = finish_pass_huff;
1537
1538
875
  if (cinfo->progressive_mode) {
1539
    /* Create progression status table */
1540
469
    int *coef_bit_ptr, ci;
1541
469
    cinfo->coef_bits = (int (*)[DCTSIZE2]) (*cinfo->mem->alloc_small)
1542
469
      ((j_common_ptr) cinfo, JPOOL_IMAGE,
1543
469
       cinfo->num_components * DCTSIZE2 * SIZEOF(int));
1544
469
    coef_bit_ptr = & cinfo->coef_bits[0][0];
1545
1.74k
    for (ci = 0; ci < cinfo->num_components; ci++)
1546
83.2k
      for (i = 0; i < DCTSIZE2; i++)
1547
81.9k
  *coef_bit_ptr++ = -1;
1548
1549
    /* Mark derived tables unallocated */
1550
2.34k
    for (i = 0; i < NUM_HUFF_TBLS; i++) {
1551
1.87k
      entropy->derived_tbls[i] = NULL;
1552
1.87k
    }
1553
469
  } else {
1554
    /* Mark derived tables unallocated */
1555
2.03k
    for (i = 0; i < NUM_HUFF_TBLS; i++) {
1556
1.62k
      entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
1557
1.62k
    }
1558
406
  }
1559
875
}