summaryrefslogtreecommitdiff
path: root/third_party/libopenjpeg20/mqc.c
blob: 8f69e29e39ddb53cdf190b9dede98a5fe9bfc3af (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
/*
 * The copyright in this software is being made available under the 2-clauses
 * BSD License, included below. This software may be subject to other third
 * party and contributor rights, including patent rights, and no such rights
 * are granted under this license.
 *
 * Copyright (c) 2002-2014, Universite catholique de Louvain (UCL), Belgium
 * Copyright (c) 2002-2014, Professor Benoit Macq
 * Copyright (c) 2001-2003, David Janssens
 * Copyright (c) 2002-2003, Yannick Verschueren
 * Copyright (c) 2003-2007, Francois-Olivier Devaux
 * Copyright (c) 2003-2014, Antonin Descampe
 * Copyright (c) 2005, Herve Drolon, FreeImage Team
 * Copyright (c) 2008, Jerome Fimes, Communications & Systemes <jerome.fimes@c-s.fr>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS `AS IS'
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "opj_includes.h"

#include <assert.h>

/** @defgroup MQC MQC - Implementation of an MQ-Coder */
/*@{*/

/** @name Local static functions */
/*@{*/

/**
Output a byte, doing bit-stuffing if necessary.
After a 0xff byte, the next byte must be smaller than 0x90.
@param mqc MQC handle
*/
static void opj_mqc_byteout(opj_mqc_t *mqc);
/**
Renormalize mqc->a and mqc->c while encoding, so that mqc->a stays between 0x8000 and 0x10000
@param mqc MQC handle
*/
static void opj_mqc_renorme(opj_mqc_t *mqc);
/**
Encode the most probable symbol
@param mqc MQC handle
*/
static void opj_mqc_codemps(opj_mqc_t *mqc);
/**
Encode the most least symbol
@param mqc MQC handle
*/
static void opj_mqc_codelps(opj_mqc_t *mqc);
/**
Fill mqc->c with 1's for flushing
@param mqc MQC handle
*/
static void opj_mqc_setbits(opj_mqc_t *mqc);
/*@}*/

/*@}*/

/* <summary> */
/* This array defines all the possible states for a context. */
/* </summary> */
static opj_mqc_state_t mqc_states[47 * 2] = {
    {0x5601, 0, &mqc_states[2], &mqc_states[3]},
    {0x5601, 1, &mqc_states[3], &mqc_states[2]},
    {0x3401, 0, &mqc_states[4], &mqc_states[12]},
    {0x3401, 1, &mqc_states[5], &mqc_states[13]},
    {0x1801, 0, &mqc_states[6], &mqc_states[18]},
    {0x1801, 1, &mqc_states[7], &mqc_states[19]},
    {0x0ac1, 0, &mqc_states[8], &mqc_states[24]},
    {0x0ac1, 1, &mqc_states[9], &mqc_states[25]},
    {0x0521, 0, &mqc_states[10], &mqc_states[58]},
    {0x0521, 1, &mqc_states[11], &mqc_states[59]},
    {0x0221, 0, &mqc_states[76], &mqc_states[66]},
    {0x0221, 1, &mqc_states[77], &mqc_states[67]},
    {0x5601, 0, &mqc_states[14], &mqc_states[13]},
    {0x5601, 1, &mqc_states[15], &mqc_states[12]},
    {0x5401, 0, &mqc_states[16], &mqc_states[28]},
    {0x5401, 1, &mqc_states[17], &mqc_states[29]},
    {0x4801, 0, &mqc_states[18], &mqc_states[28]},
    {0x4801, 1, &mqc_states[19], &mqc_states[29]},
    {0x3801, 0, &mqc_states[20], &mqc_states[28]},
    {0x3801, 1, &mqc_states[21], &mqc_states[29]},
    {0x3001, 0, &mqc_states[22], &mqc_states[34]},
    {0x3001, 1, &mqc_states[23], &mqc_states[35]},
    {0x2401, 0, &mqc_states[24], &mqc_states[36]},
    {0x2401, 1, &mqc_states[25], &mqc_states[37]},
    {0x1c01, 0, &mqc_states[26], &mqc_states[40]},
    {0x1c01, 1, &mqc_states[27], &mqc_states[41]},
    {0x1601, 0, &mqc_states[58], &mqc_states[42]},
    {0x1601, 1, &mqc_states[59], &mqc_states[43]},
    {0x5601, 0, &mqc_states[30], &mqc_states[29]},
    {0x5601, 1, &mqc_states[31], &mqc_states[28]},
    {0x5401, 0, &mqc_states[32], &mqc_states[28]},
    {0x5401, 1, &mqc_states[33], &mqc_states[29]},
    {0x5101, 0, &mqc_states[34], &mqc_states[30]},
    {0x5101, 1, &mqc_states[35], &mqc_states[31]},
    {0x4801, 0, &mqc_states[36], &mqc_states[32]},
    {0x4801, 1, &mqc_states[37], &mqc_states[33]},
    {0x3801, 0, &mqc_states[38], &mqc_states[34]},
    {0x3801, 1, &mqc_states[39], &mqc_states[35]},
    {0x3401, 0, &mqc_states[40], &mqc_states[36]},
    {0x3401, 1, &mqc_states[41], &mqc_states[37]},
    {0x3001, 0, &mqc_states[42], &mqc_states[38]},
    {0x3001, 1, &mqc_states[43], &mqc_states[39]},
    {0x2801, 0, &mqc_states[44], &mqc_states[38]},
    {0x2801, 1, &mqc_states[45], &mqc_states[39]},
    {0x2401, 0, &mqc_states[46], &mqc_states[40]},
    {0x2401, 1, &mqc_states[47], &mqc_states[41]},
    {0x2201, 0, &mqc_states[48], &mqc_states[42]},
    {0x2201, 1, &mqc_states[49], &mqc_states[43]},
    {0x1c01, 0, &mqc_states[50], &mqc_states[44]},
    {0x1c01, 1, &mqc_states[51], &mqc_states[45]},
    {0x1801, 0, &mqc_states[52], &mqc_states[46]},
    {0x1801, 1, &mqc_states[53], &mqc_states[47]},
    {0x1601, 0, &mqc_states[54], &mqc_states[48]},
    {0x1601, 1, &mqc_states[55], &mqc_states[49]},
    {0x1401, 0, &mqc_states[56], &mqc_states[50]},
    {0x1401, 1, &mqc_states[57], &mqc_states[51]},
    {0x1201, 0, &mqc_states[58], &mqc_states[52]},
    {0x1201, 1, &mqc_states[59], &mqc_states[53]},
    {0x1101, 0, &mqc_states[60], &mqc_states[54]},
    {0x1101, 1, &mqc_states[61], &mqc_states[55]},
    {0x0ac1, 0, &mqc_states[62], &mqc_states[56]},
    {0x0ac1, 1, &mqc_states[63], &mqc_states[57]},
    {0x09c1, 0, &mqc_states[64], &mqc_states[58]},
    {0x09c1, 1, &mqc_states[65], &mqc_states[59]},
    {0x08a1, 0, &mqc_states[66], &mqc_states[60]},
    {0x08a1, 1, &mqc_states[67], &mqc_states[61]},
    {0x0521, 0, &mqc_states[68], &mqc_states[62]},
    {0x0521, 1, &mqc_states[69], &mqc_states[63]},
    {0x0441, 0, &mqc_states[70], &mqc_states[64]},
    {0x0441, 1, &mqc_states[71], &mqc_states[65]},
    {0x02a1, 0, &mqc_states[72], &mqc_states[66]},
    {0x02a1, 1, &mqc_states[73], &mqc_states[67]},
    {0x0221, 0, &mqc_states[74], &mqc_states[68]},
    {0x0221, 1, &mqc_states[75], &mqc_states[69]},
    {0x0141, 0, &mqc_states[76], &mqc_states[70]},
    {0x0141, 1, &mqc_states[77], &mqc_states[71]},
    {0x0111, 0, &mqc_states[78], &mqc_states[72]},
    {0x0111, 1, &mqc_states[79], &mqc_states[73]},
    {0x0085, 0, &mqc_states[80], &mqc_states[74]},
    {0x0085, 1, &mqc_states[81], &mqc_states[75]},
    {0x0049, 0, &mqc_states[82], &mqc_states[76]},
    {0x0049, 1, &mqc_states[83], &mqc_states[77]},
    {0x0025, 0, &mqc_states[84], &mqc_states[78]},
    {0x0025, 1, &mqc_states[85], &mqc_states[79]},
    {0x0015, 0, &mqc_states[86], &mqc_states[80]},
    {0x0015, 1, &mqc_states[87], &mqc_states[81]},
    {0x0009, 0, &mqc_states[88], &mqc_states[82]},
    {0x0009, 1, &mqc_states[89], &mqc_states[83]},
    {0x0005, 0, &mqc_states[90], &mqc_states[84]},
    {0x0005, 1, &mqc_states[91], &mqc_states[85]},
    {0x0001, 0, &mqc_states[90], &mqc_states[86]},
    {0x0001, 1, &mqc_states[91], &mqc_states[87]},
    {0x5601, 0, &mqc_states[92], &mqc_states[92]},
    {0x5601, 1, &mqc_states[93], &mqc_states[93]},
};

/*
==========================================================
   local functions
==========================================================
*/

static void opj_mqc_byteout(opj_mqc_t *mqc)
{
    /* bp is initialized to start - 1 in opj_mqc_init_enc() */
    /* but this is safe, see opj_tcd_code_block_enc_allocate_data() */
    assert(mqc->bp >= mqc->start - 1);
    if (*mqc->bp == 0xff) {
        mqc->bp++;
        *mqc->bp = (OPJ_BYTE)(mqc->c >> 20);
        mqc->c &= 0xfffff;
        mqc->ct = 7;
    } else {
        if ((mqc->c & 0x8000000) == 0) {
            mqc->bp++;
            *mqc->bp = (OPJ_BYTE)(mqc->c >> 19);
            mqc->c &= 0x7ffff;
            mqc->ct = 8;
        } else {
            (*mqc->bp)++;
            if (*mqc->bp == 0xff) {
                mqc->c &= 0x7ffffff;
                mqc->bp++;
                *mqc->bp = (OPJ_BYTE)(mqc->c >> 20);
                mqc->c &= 0xfffff;
                mqc->ct = 7;
            } else {
                mqc->bp++;
                *mqc->bp = (OPJ_BYTE)(mqc->c >> 19);
                mqc->c &= 0x7ffff;
                mqc->ct = 8;
            }
        }
    }
}

static void opj_mqc_renorme(opj_mqc_t *mqc)
{
    do {
        mqc->a <<= 1;
        mqc->c <<= 1;
        mqc->ct--;
        if (mqc->ct == 0) {
            opj_mqc_byteout(mqc);
        }
    } while ((mqc->a & 0x8000) == 0);
}

static void opj_mqc_codemps(opj_mqc_t *mqc)
{
    mqc->a -= (*mqc->curctx)->qeval;
    if ((mqc->a & 0x8000) == 0) {
        if (mqc->a < (*mqc->curctx)->qeval) {
            mqc->a = (*mqc->curctx)->qeval;
        } else {
            mqc->c += (*mqc->curctx)->qeval;
        }
        *mqc->curctx = (*mqc->curctx)->nmps;
        opj_mqc_renorme(mqc);
    } else {
        mqc->c += (*mqc->curctx)->qeval;
    }
}

static void opj_mqc_codelps(opj_mqc_t *mqc)
{
    mqc->a -= (*mqc->curctx)->qeval;
    if (mqc->a < (*mqc->curctx)->qeval) {
        mqc->c += (*mqc->curctx)->qeval;
    } else {
        mqc->a = (*mqc->curctx)->qeval;
    }
    *mqc->curctx = (*mqc->curctx)->nlps;
    opj_mqc_renorme(mqc);
}

static void opj_mqc_setbits(opj_mqc_t *mqc)
{
    OPJ_UINT32 tempc = mqc->c + mqc->a;
    mqc->c |= 0xffff;
    if (mqc->c >= tempc) {
        mqc->c -= 0x8000;
    }
}

/*
==========================================================
   MQ-Coder interface
==========================================================
*/

OPJ_UINT32 opj_mqc_numbytes(opj_mqc_t *mqc)
{
    const ptrdiff_t diff = mqc->bp - mqc->start;
#if 0
    assert(diff <= 0xffffffff && diff >= 0);   /* UINT32_MAX */
#endif
    return (OPJ_UINT32)diff;
}

void opj_mqc_init_enc(opj_mqc_t *mqc, OPJ_BYTE *bp)
{
    /* To avoid the curctx pointer to be dangling, but not strictly */
    /* required as the current context is always set before encoding */
    opj_mqc_setcurctx(mqc, 0);

    /* As specified in Figure C.10 - Initialization of the encoder */
    /* (C.2.8 Initialization of the encoder (INITENC)) */
    mqc->a = 0x8000;
    mqc->c = 0;
    /* Yes, we point before the start of the buffer, but this is safe */
    /* given opj_tcd_code_block_enc_allocate_data() */
    mqc->bp = bp - 1;
    mqc->ct = 12;
    /* At this point we should test *(mqc->bp) against 0xFF, but this is not */
    /* necessary, as this is only used at the beginning of the code block */
    /* and our initial fake byte is set at 0 */
    assert(*(mqc->bp) != 0xff);

    mqc->start = bp;
    mqc->end_of_byte_stream_counter = 0;
}

void opj_mqc_encode(opj_mqc_t *mqc, OPJ_UINT32 d)
{
    if ((*mqc->curctx)->mps == d) {
        opj_mqc_codemps(mqc);
    } else {
        opj_mqc_codelps(mqc);
    }
}

void opj_mqc_flush(opj_mqc_t *mqc)
{
    /* C.2.9 Termination of coding (FLUSH) */
    /* Figure C.11 – FLUSH procedure */
    opj_mqc_setbits(mqc);
    mqc->c <<= mqc->ct;
    opj_mqc_byteout(mqc);
    mqc->c <<= mqc->ct;
    opj_mqc_byteout(mqc);

    /* It is forbidden that a coding pass ends with 0xff */
    if (*mqc->bp != 0xff) {
        /* Advance pointer so that opj_mqc_numbytes() returns a valid value */
        mqc->bp++;
    }
}

#define BYPASS_CT_INIT  0xDEADBEEF

void opj_mqc_bypass_init_enc(opj_mqc_t *mqc)
{
    /* This function is normally called after at least one opj_mqc_flush() */
    /* which will have advance mqc->bp by at least 2 bytes beyond its */
    /* initial position */
    assert(mqc->bp >= mqc->start);
    mqc->c = 0;
    /* in theory we should initialize to 8, but use this special value */
    /* as a hint that opj_mqc_bypass_enc() has never been called, so */
    /* as to avoid the 0xff 0x7f elimination trick in opj_mqc_bypass_flush_enc() */
    /* to trigger when we don't have output any bit during this bypass sequence */
    /* Any value > 8 will do */
    mqc->ct = BYPASS_CT_INIT;
    /* Given that we are called after opj_mqc_flush(), the previous byte */
    /* cannot be 0xff. */
    assert(mqc->bp[-1] != 0xff);
}

void opj_mqc_bypass_enc(opj_mqc_t *mqc, OPJ_UINT32 d)
{
    if (mqc->ct == BYPASS_CT_INIT) {
        mqc->ct = 8;
    }
    mqc->ct--;
    mqc->c = mqc->c + (d << mqc->ct);
    if (mqc->ct == 0) {
        *mqc->bp = (OPJ_BYTE)mqc->c;
        mqc->ct = 8;
        /* If the previous byte was 0xff, make sure that the next msb is 0 */
        if (*mqc->bp == 0xff) {
            mqc->ct = 7;
        }
        mqc->bp++;
        mqc->c = 0;
    }
}

OPJ_UINT32 opj_mqc_bypass_get_extra_bytes(opj_mqc_t *mqc, OPJ_BOOL erterm)
{
    return (mqc->ct < 7 ||
            (mqc->ct == 7 && (erterm || mqc->bp[-1] != 0xff))) ? 1 : 0;
}

void opj_mqc_bypass_flush_enc(opj_mqc_t *mqc, OPJ_BOOL erterm)
{
    /* Is there any bit remaining to be flushed ? */
    /* If the last output byte is 0xff, we can discard it, unless */
    /* erterm is required (I'm not completely sure why in erterm */
    /* we must output 0xff 0x2a if the last byte was 0xff instead of */
    /* discarding it, but Kakadu requires it when decoding */
    /* in -fussy mode) */
    if (mqc->ct < 7 || (mqc->ct == 7 && (erterm || mqc->bp[-1] != 0xff))) {
        OPJ_BYTE bit_value = 0;
        /* If so, fill the remaining lsbs with an alternating sequence of */
        /* 0,1,... */
        /* Note: it seems the standard only requires that for a ERTERM flush */
        /* and doesn't specify what to do for a regular BYPASS flush */
        while (mqc->ct > 0) {
            mqc->ct--;
            mqc->c += (OPJ_UINT32)(bit_value << mqc->ct);
            bit_value = (OPJ_BYTE)(1U - bit_value);
        }
        *mqc->bp = (OPJ_BYTE)mqc->c;
        /* Advance pointer so that opj_mqc_numbytes() returns a valid value */
        mqc->bp++;
    } else if (mqc->ct == 7 && mqc->bp[-1] == 0xff) {
        /* Discard last 0xff */
        assert(!erterm);
        mqc->bp --;
    } else if (mqc->ct == 8 && !erterm &&
               mqc->bp[-1] == 0x7f && mqc->bp[-2] == 0xff) {
        /* Tiny optimization: discard terminating 0xff 0x7f since it is */
        /* interpreted as 0xff 0x7f [0xff 0xff] by the decoder, and given */
        /* the bit stuffing, in fact as 0xff 0xff [0xff ..] */
        /* Happens once on opj_compress -i ../MAPA.tif -o MAPA.j2k  -M 1 */
        mqc->bp -= 2;
    }

    assert(mqc->bp[-1] != 0xff);
}

void opj_mqc_reset_enc(opj_mqc_t *mqc)
{
    opj_mqc_resetstates(mqc);
    opj_mqc_setstate(mqc, T1_CTXNO_UNI, 0, 46);
    opj_mqc_setstate(mqc, T1_CTXNO_AGG, 0, 3);
    opj_mqc_setstate(mqc, T1_CTXNO_ZC, 0, 4);
}

#ifdef notdef
OPJ_UINT32 opj_mqc_restart_enc(opj_mqc_t *mqc)
{
    OPJ_UINT32 correction = 1;

    /* <flush part> */
    OPJ_INT32 n = (OPJ_INT32)(27 - 15 - mqc->ct);
    mqc->c <<= mqc->ct;
    while (n > 0) {
        opj_mqc_byteout(mqc);
        n -= (OPJ_INT32)mqc->ct;
        mqc->c <<= mqc->ct;
    }
    opj_mqc_byteout(mqc);

    return correction;
}
#endif

void opj_mqc_restart_init_enc(opj_mqc_t *mqc)
{
    /* <Re-init part> */

    /* As specified in Figure C.10 - Initialization of the encoder */
    /* (C.2.8 Initialization of the encoder (INITENC)) */
    mqc->a = 0x8000;
    mqc->c = 0;
    mqc->ct = 12;
    /* This function is normally called after at least one opj_mqc_flush() */
    /* which will have advance mqc->bp by at least 2 bytes beyond its */
    /* initial position */
    mqc->bp --;
    assert(mqc->bp >= mqc->start - 1);
    assert(*mqc->bp != 0xff);
    if (*mqc->bp == 0xff) {
        mqc->ct = 13;
    }
}

void opj_mqc_erterm_enc(opj_mqc_t *mqc)
{
    OPJ_INT32 k = (OPJ_INT32)(11 - mqc->ct + 1);

    while (k > 0) {
        mqc->c <<= mqc->ct;
        mqc->ct = 0;
        opj_mqc_byteout(mqc);
        k -= (OPJ_INT32)mqc->ct;
    }

    if (*mqc->bp != 0xff) {
        opj_mqc_byteout(mqc);
    }
}

void opj_mqc_segmark_enc(opj_mqc_t *mqc)
{
    OPJ_UINT32 i;
    opj_mqc_setcurctx(mqc, 18);

    for (i = 1; i < 5; i++) {
        opj_mqc_encode(mqc, i % 2);
    }
}

static void opj_mqc_init_dec_common(opj_mqc_t *mqc,
                                    OPJ_BYTE *bp,
                                    OPJ_UINT32 len,
                                    OPJ_UINT32 extra_writable_bytes)
{
    (void)extra_writable_bytes;

    assert(extra_writable_bytes >= OPJ_COMMON_CBLK_DATA_EXTRA);
    mqc->start = bp;
    mqc->end = bp + len;
    /* Insert an artificial 0xFF 0xFF marker at end of the code block */
    /* data so that the bytein routines stop on it. This saves us comparing */
    /* the bp and end pointers */
    /* But before inserting it, backup th bytes we will overwrite */
    memcpy(mqc->backup, mqc->end, OPJ_COMMON_CBLK_DATA_EXTRA);
    mqc->end[0] = 0xFF;
    mqc->end[1] = 0xFF;
    mqc->bp = bp;
}
void opj_mqc_init_dec(opj_mqc_t *mqc, OPJ_BYTE *bp, OPJ_UINT32 len,
                      OPJ_UINT32 extra_writable_bytes)
{
    /* Implements ISO 15444-1 C.3.5 Initialization of the decoder (INITDEC) */
    /* Note: alternate "J.1 - Initialization of the software-conventions */
    /* decoder" has been tried, but does */
    /* not bring any improvement. */
    /* See https://github.com/uclouvain/openjpeg/issues/921 */
    opj_mqc_init_dec_common(mqc, bp, len, extra_writable_bytes);
    opj_mqc_setcurctx(mqc, 0);
    mqc->end_of_byte_stream_counter = 0;
    if (len == 0) {
        mqc->c = 0xff << 16;
    } else {
        mqc->c = (OPJ_UINT32)(*mqc->bp << 16);
    }

    opj_mqc_bytein(mqc);
    mqc->c <<= 7;
    mqc->ct -= 7;
    mqc->a = 0x8000;
}


void opj_mqc_raw_init_dec(opj_mqc_t *mqc, OPJ_BYTE *bp, OPJ_UINT32 len,
                          OPJ_UINT32 extra_writable_bytes)
{
    opj_mqc_init_dec_common(mqc, bp, len, extra_writable_bytes);
    mqc->c = 0;
    mqc->ct = 0;
}


void opq_mqc_finish_dec(opj_mqc_t *mqc)
{
    /* Restore the bytes overwritten by opj_mqc_init_dec_common() */
    memcpy(mqc->end, mqc->backup, OPJ_COMMON_CBLK_DATA_EXTRA);
}

void opj_mqc_resetstates(opj_mqc_t *mqc)
{
    OPJ_UINT32 i;
    for (i = 0; i < MQC_NUMCTXS; i++) {
        mqc->ctxs[i] = mqc_states;
    }
}

void opj_mqc_setstate(opj_mqc_t *mqc, OPJ_UINT32 ctxno, OPJ_UINT32 msb,
                      OPJ_INT32 prob)
{
    mqc->ctxs[ctxno] = &mqc_states[msb + (OPJ_UINT32)(prob << 1)];
}