1 /*
2  * The copyright in this software is being made available under the 2-clauses
3  * BSD License, included below. This software may be subject to other third
4  * party and contributor rights, including patent rights, and no such rights
5  * are granted under this license.
6  *
7  * Copyright (c) 2002-2014, Universite catholique de Louvain (UCL), Belgium
8  * Copyright (c) 2002-2014, Professor Benoit Macq
9  * Copyright (c) 2001-2003, David Janssens
10  * Copyright (c) 2002-2003, Yannick Verschueren
11  * Copyright (c) 2003-2007, Francois-Olivier Devaux
12  * Copyright (c) 2003-2014, Antonin Descampe
13  * Copyright (c) 2005, Herve Drolon, FreeImage Team
14  * Copyright (c) 2008, Jerome Fimes, Communications & Systemes <jerome.fimes@c-s.fr>
15  * All rights reserved.
16  *
17  * Redistribution and use in source and binary forms, with or without
18  * modification, are permitted provided that the following conditions
19  * are met:
20  * 1. Redistributions of source code must retain the above copyright
21  *    notice, this list of conditions and the following disclaimer.
22  * 2. Redistributions in binary form must reproduce the above copyright
23  *    notice, this list of conditions and the following disclaimer in the
24  *    documentation and/or other materials provided with the distribution.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS `AS IS'
27  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
30  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 #include "opj_includes.h"
40 
41 #include <assert.h>
42 
43 /** @defgroup MQC MQC - Implementation of an MQ-Coder */
44 /*@{*/
45 
46 /** @name Local static functions */
47 /*@{*/
48 
49 /**
50 Output a byte, doing bit-stuffing if necessary.
51 After a 0xff byte, the next byte must be smaller than 0x90.
52 @param mqc MQC handle
53 */
54 static void opj_mqc_byteout(opj_mqc_t *mqc);
55 /**
56 Renormalize mqc->a and mqc->c while encoding, so that mqc->a stays between 0x8000 and 0x10000
57 @param mqc MQC handle
58 */
59 static void opj_mqc_renorme(opj_mqc_t *mqc);
60 /**
61 Encode the most probable symbol
62 @param mqc MQC handle
63 */
64 static void opj_mqc_codemps(opj_mqc_t *mqc);
65 /**
66 Encode the most least symbol
67 @param mqc MQC handle
68 */
69 static void opj_mqc_codelps(opj_mqc_t *mqc);
70 /**
71 Fill mqc->c with 1's for flushing
72 @param mqc MQC handle
73 */
74 static void opj_mqc_setbits(opj_mqc_t *mqc);
75 /*@}*/
76 
77 /*@}*/
78 
79 /* <summary> */
80 /* This array defines all the possible states for a context. */
81 /* </summary> */
82 static const opj_mqc_state_t mqc_states[47 * 2] = {
83     {0x5601, 0, &mqc_states[2], &mqc_states[3]},
84     {0x5601, 1, &mqc_states[3], &mqc_states[2]},
85     {0x3401, 0, &mqc_states[4], &mqc_states[12]},
86     {0x3401, 1, &mqc_states[5], &mqc_states[13]},
87     {0x1801, 0, &mqc_states[6], &mqc_states[18]},
88     {0x1801, 1, &mqc_states[7], &mqc_states[19]},
89     {0x0ac1, 0, &mqc_states[8], &mqc_states[24]},
90     {0x0ac1, 1, &mqc_states[9], &mqc_states[25]},
91     {0x0521, 0, &mqc_states[10], &mqc_states[58]},
92     {0x0521, 1, &mqc_states[11], &mqc_states[59]},
93     {0x0221, 0, &mqc_states[76], &mqc_states[66]},
94     {0x0221, 1, &mqc_states[77], &mqc_states[67]},
95     {0x5601, 0, &mqc_states[14], &mqc_states[13]},
96     {0x5601, 1, &mqc_states[15], &mqc_states[12]},
97     {0x5401, 0, &mqc_states[16], &mqc_states[28]},
98     {0x5401, 1, &mqc_states[17], &mqc_states[29]},
99     {0x4801, 0, &mqc_states[18], &mqc_states[28]},
100     {0x4801, 1, &mqc_states[19], &mqc_states[29]},
101     {0x3801, 0, &mqc_states[20], &mqc_states[28]},
102     {0x3801, 1, &mqc_states[21], &mqc_states[29]},
103     {0x3001, 0, &mqc_states[22], &mqc_states[34]},
104     {0x3001, 1, &mqc_states[23], &mqc_states[35]},
105     {0x2401, 0, &mqc_states[24], &mqc_states[36]},
106     {0x2401, 1, &mqc_states[25], &mqc_states[37]},
107     {0x1c01, 0, &mqc_states[26], &mqc_states[40]},
108     {0x1c01, 1, &mqc_states[27], &mqc_states[41]},
109     {0x1601, 0, &mqc_states[58], &mqc_states[42]},
110     {0x1601, 1, &mqc_states[59], &mqc_states[43]},
111     {0x5601, 0, &mqc_states[30], &mqc_states[29]},
112     {0x5601, 1, &mqc_states[31], &mqc_states[28]},
113     {0x5401, 0, &mqc_states[32], &mqc_states[28]},
114     {0x5401, 1, &mqc_states[33], &mqc_states[29]},
115     {0x5101, 0, &mqc_states[34], &mqc_states[30]},
116     {0x5101, 1, &mqc_states[35], &mqc_states[31]},
117     {0x4801, 0, &mqc_states[36], &mqc_states[32]},
118     {0x4801, 1, &mqc_states[37], &mqc_states[33]},
119     {0x3801, 0, &mqc_states[38], &mqc_states[34]},
120     {0x3801, 1, &mqc_states[39], &mqc_states[35]},
121     {0x3401, 0, &mqc_states[40], &mqc_states[36]},
122     {0x3401, 1, &mqc_states[41], &mqc_states[37]},
123     {0x3001, 0, &mqc_states[42], &mqc_states[38]},
124     {0x3001, 1, &mqc_states[43], &mqc_states[39]},
125     {0x2801, 0, &mqc_states[44], &mqc_states[38]},
126     {0x2801, 1, &mqc_states[45], &mqc_states[39]},
127     {0x2401, 0, &mqc_states[46], &mqc_states[40]},
128     {0x2401, 1, &mqc_states[47], &mqc_states[41]},
129     {0x2201, 0, &mqc_states[48], &mqc_states[42]},
130     {0x2201, 1, &mqc_states[49], &mqc_states[43]},
131     {0x1c01, 0, &mqc_states[50], &mqc_states[44]},
132     {0x1c01, 1, &mqc_states[51], &mqc_states[45]},
133     {0x1801, 0, &mqc_states[52], &mqc_states[46]},
134     {0x1801, 1, &mqc_states[53], &mqc_states[47]},
135     {0x1601, 0, &mqc_states[54], &mqc_states[48]},
136     {0x1601, 1, &mqc_states[55], &mqc_states[49]},
137     {0x1401, 0, &mqc_states[56], &mqc_states[50]},
138     {0x1401, 1, &mqc_states[57], &mqc_states[51]},
139     {0x1201, 0, &mqc_states[58], &mqc_states[52]},
140     {0x1201, 1, &mqc_states[59], &mqc_states[53]},
141     {0x1101, 0, &mqc_states[60], &mqc_states[54]},
142     {0x1101, 1, &mqc_states[61], &mqc_states[55]},
143     {0x0ac1, 0, &mqc_states[62], &mqc_states[56]},
144     {0x0ac1, 1, &mqc_states[63], &mqc_states[57]},
145     {0x09c1, 0, &mqc_states[64], &mqc_states[58]},
146     {0x09c1, 1, &mqc_states[65], &mqc_states[59]},
147     {0x08a1, 0, &mqc_states[66], &mqc_states[60]},
148     {0x08a1, 1, &mqc_states[67], &mqc_states[61]},
149     {0x0521, 0, &mqc_states[68], &mqc_states[62]},
150     {0x0521, 1, &mqc_states[69], &mqc_states[63]},
151     {0x0441, 0, &mqc_states[70], &mqc_states[64]},
152     {0x0441, 1, &mqc_states[71], &mqc_states[65]},
153     {0x02a1, 0, &mqc_states[72], &mqc_states[66]},
154     {0x02a1, 1, &mqc_states[73], &mqc_states[67]},
155     {0x0221, 0, &mqc_states[74], &mqc_states[68]},
156     {0x0221, 1, &mqc_states[75], &mqc_states[69]},
157     {0x0141, 0, &mqc_states[76], &mqc_states[70]},
158     {0x0141, 1, &mqc_states[77], &mqc_states[71]},
159     {0x0111, 0, &mqc_states[78], &mqc_states[72]},
160     {0x0111, 1, &mqc_states[79], &mqc_states[73]},
161     {0x0085, 0, &mqc_states[80], &mqc_states[74]},
162     {0x0085, 1, &mqc_states[81], &mqc_states[75]},
163     {0x0049, 0, &mqc_states[82], &mqc_states[76]},
164     {0x0049, 1, &mqc_states[83], &mqc_states[77]},
165     {0x0025, 0, &mqc_states[84], &mqc_states[78]},
166     {0x0025, 1, &mqc_states[85], &mqc_states[79]},
167     {0x0015, 0, &mqc_states[86], &mqc_states[80]},
168     {0x0015, 1, &mqc_states[87], &mqc_states[81]},
169     {0x0009, 0, &mqc_states[88], &mqc_states[82]},
170     {0x0009, 1, &mqc_states[89], &mqc_states[83]},
171     {0x0005, 0, &mqc_states[90], &mqc_states[84]},
172     {0x0005, 1, &mqc_states[91], &mqc_states[85]},
173     {0x0001, 0, &mqc_states[90], &mqc_states[86]},
174     {0x0001, 1, &mqc_states[91], &mqc_states[87]},
175     {0x5601, 0, &mqc_states[92], &mqc_states[92]},
176     {0x5601, 1, &mqc_states[93], &mqc_states[93]},
177 };
178 
179 /*
180 ==========================================================
181    local functions
182 ==========================================================
183 */
184 
185 static void opj_mqc_byteout(opj_mqc_t *mqc)
186 {
187     /* bp is initialized to start - 1 in opj_mqc_init_enc() */
188     /* but this is safe, see opj_tcd_code_block_enc_allocate_data() */
189     assert(mqc->bp >= mqc->start - 1);
190     if (*mqc->bp == 0xff) {
191         mqc->bp++;
192         *mqc->bp = (OPJ_BYTE)(mqc->c >> 20);
193         mqc->c &= 0xfffff;
194         mqc->ct = 7;
195     } else {
196         if ((mqc->c & 0x8000000) == 0) {
197             mqc->bp++;
198             *mqc->bp = (OPJ_BYTE)(mqc->c >> 19);
199             mqc->c &= 0x7ffff;
200             mqc->ct = 8;
201         } else {
202             (*mqc->bp)++;
203             if (*mqc->bp == 0xff) {
204                 mqc->c &= 0x7ffffff;
205                 mqc->bp++;
206                 *mqc->bp = (OPJ_BYTE)(mqc->c >> 20);
207                 mqc->c &= 0xfffff;
208                 mqc->ct = 7;
209             } else {
210                 mqc->bp++;
211                 *mqc->bp = (OPJ_BYTE)(mqc->c >> 19);
212                 mqc->c &= 0x7ffff;
213                 mqc->ct = 8;
214             }
215         }
216     }
217 }
218 
219 static void opj_mqc_renorme(opj_mqc_t *mqc)
220 {
221     do {
222         mqc->a <<= 1;
223         mqc->c <<= 1;
224         mqc->ct--;
225         if (mqc->ct == 0) {
226             opj_mqc_byteout(mqc);
227         }
228     } while ((mqc->a & 0x8000) == 0);
229 }
230 
231 static void opj_mqc_codemps(opj_mqc_t *mqc)
232 {
233     mqc->a -= (*mqc->curctx)->qeval;
234     if ((mqc->a & 0x8000) == 0) {
235         if (mqc->a < (*mqc->curctx)->qeval) {
236             mqc->a = (*mqc->curctx)->qeval;
237         } else {
238             mqc->c += (*mqc->curctx)->qeval;
239         }
240         *mqc->curctx = (*mqc->curctx)->nmps;
241         opj_mqc_renorme(mqc);
242     } else {
243         mqc->c += (*mqc->curctx)->qeval;
244     }
245 }
246 
247 static void opj_mqc_codelps(opj_mqc_t *mqc)
248 {
249     mqc->a -= (*mqc->curctx)->qeval;
250     if (mqc->a < (*mqc->curctx)->qeval) {
251         mqc->c += (*mqc->curctx)->qeval;
252     } else {
253         mqc->a = (*mqc->curctx)->qeval;
254     }
255     *mqc->curctx = (*mqc->curctx)->nlps;
256     opj_mqc_renorme(mqc);
257 }
258 
259 static void opj_mqc_setbits(opj_mqc_t *mqc)
260 {
261     OPJ_UINT32 tempc = mqc->c + mqc->a;
262     mqc->c |= 0xffff;
263     if (mqc->c >= tempc) {
264         mqc->c -= 0x8000;
265     }
266 }
267 
268 /*
269 ==========================================================
270    MQ-Coder interface
271 ==========================================================
272 */
273 
274 OPJ_UINT32 opj_mqc_numbytes(opj_mqc_t *mqc)
275 {
276     const ptrdiff_t diff = mqc->bp - mqc->start;
277 #if 0
278     assert(diff <= 0xffffffff && diff >= 0);   /* UINT32_MAX */
279 #endif
280     return (OPJ_UINT32)diff;
281 }
282 
283 void opj_mqc_init_enc(opj_mqc_t *mqc, OPJ_BYTE *bp)
284 {
285     /* To avoid the curctx pointer to be dangling, but not strictly */
286     /* required as the current context is always set before encoding */
287     opj_mqc_setcurctx(mqc, 0);
288 
289     /* As specified in Figure C.10 - Initialization of the encoder */
290     /* (C.2.8 Initialization of the encoder (INITENC)) */
291     mqc->a = 0x8000;
292     mqc->c = 0;
293     /* Yes, we point before the start of the buffer, but this is safe */
294     /* given opj_tcd_code_block_enc_allocate_data() */
295     mqc->bp = bp - 1;
296     mqc->ct = 12;
297     /* At this point we should test *(mqc->bp) against 0xFF, but this is not */
298     /* necessary, as this is only used at the beginning of the code block */
299     /* and our initial fake byte is set at 0 */
300     assert(*(mqc->bp) != 0xff);
301 
302     mqc->start = bp;
303     mqc->end_of_byte_stream_counter = 0;
304 }
305 
306 void opj_mqc_encode(opj_mqc_t *mqc, OPJ_UINT32 d)
307 {
308     if ((*mqc->curctx)->mps == d) {
309         opj_mqc_codemps(mqc);
310     } else {
311         opj_mqc_codelps(mqc);
312     }
313 }
314 
315 void opj_mqc_flush(opj_mqc_t *mqc)
316 {
317     /* C.2.9 Termination of coding (FLUSH) */
318     /* Figure C.11 – FLUSH procedure */
319     opj_mqc_setbits(mqc);
320     mqc->c <<= mqc->ct;
321     opj_mqc_byteout(mqc);
322     mqc->c <<= mqc->ct;
323     opj_mqc_byteout(mqc);
324 
325     /* It is forbidden that a coding pass ends with 0xff */
326     if (*mqc->bp != 0xff) {
327         /* Advance pointer so that opj_mqc_numbytes() returns a valid value */
328         mqc->bp++;
329     }
330 }
331 
332 #define BYPASS_CT_INIT  0xDEADBEEF
333 
334 void opj_mqc_bypass_init_enc(opj_mqc_t *mqc)
335 {
336     /* This function is normally called after at least one opj_mqc_flush() */
337     /* which will have advance mqc->bp by at least 2 bytes beyond its */
338     /* initial position */
339     assert(mqc->bp >= mqc->start);
340     mqc->c = 0;
341     /* in theory we should initialize to 8, but use this special value */
342     /* as a hint that opj_mqc_bypass_enc() has never been called, so */
343     /* as to avoid the 0xff 0x7f elimination trick in opj_mqc_bypass_flush_enc() */
344     /* to trigger when we don't have output any bit during this bypass sequence */
345     /* Any value > 8 will do */
346     mqc->ct = BYPASS_CT_INIT;
347     /* Given that we are called after opj_mqc_flush(), the previous byte */
348     /* cannot be 0xff. */
349     assert(mqc->bp[-1] != 0xff);
350 }
351 
352 void opj_mqc_bypass_enc(opj_mqc_t *mqc, OPJ_UINT32 d)
353 {
354     if (mqc->ct == BYPASS_CT_INIT) {
355         mqc->ct = 8;
356     }
357     mqc->ct--;
358     mqc->c = mqc->c + (d << mqc->ct);
359     if (mqc->ct == 0) {
360         *mqc->bp = (OPJ_BYTE)mqc->c;
361         mqc->ct = 8;
362         /* If the previous byte was 0xff, make sure that the next msb is 0 */
363         if (*mqc->bp == 0xff) {
364             mqc->ct = 7;
365         }
366         mqc->bp++;
367         mqc->c = 0;
368     }
369 }
370 
371 OPJ_UINT32 opj_mqc_bypass_get_extra_bytes(opj_mqc_t *mqc, OPJ_BOOL erterm)
372 {
373     return (mqc->ct < 7 ||
374             (mqc->ct == 7 && (erterm || mqc->bp[-1] != 0xff))) ? 1 : 0;
375 }
376 
377 void opj_mqc_bypass_flush_enc(opj_mqc_t *mqc, OPJ_BOOL erterm)
378 {
379     /* Is there any bit remaining to be flushed ? */
380     /* If the last output byte is 0xff, we can discard it, unless */
381     /* erterm is required (I'm not completely sure why in erterm */
382     /* we must output 0xff 0x2a if the last byte was 0xff instead of */
383     /* discarding it, but Kakadu requires it when decoding */
384     /* in -fussy mode) */
385     if (mqc->ct < 7 || (mqc->ct == 7 && (erterm || mqc->bp[-1] != 0xff))) {
386         OPJ_BYTE bit_value = 0;
387         /* If so, fill the remaining lsbs with an alternating sequence of */
388         /* 0,1,... */
389         /* Note: it seems the standard only requires that for a ERTERM flush */
390         /* and doesn't specify what to do for a regular BYPASS flush */
391         while (mqc->ct > 0) {
392             mqc->ct--;
393             mqc->c += (OPJ_UINT32)(bit_value << mqc->ct);
394             bit_value = (OPJ_BYTE)(1U - bit_value);
395         }
396         *mqc->bp = (OPJ_BYTE)mqc->c;
397         /* Advance pointer so that opj_mqc_numbytes() returns a valid value */
398         mqc->bp++;
399     } else if (mqc->ct == 7 && mqc->bp[-1] == 0xff) {
400         /* Discard last 0xff */
401         assert(!erterm);
402         mqc->bp --;
403     } else if (mqc->ct == 8 && !erterm &&
404                mqc->bp[-1] == 0x7f && mqc->bp[-2] == 0xff) {
405         /* Tiny optimization: discard terminating 0xff 0x7f since it is */
406         /* interpreted as 0xff 0x7f [0xff 0xff] by the decoder, and given */
407         /* the bit stuffing, in fact as 0xff 0xff [0xff ..] */
408         /* Happens once on opj_compress -i ../MAPA.tif -o MAPA.j2k  -M 1 */
409         mqc->bp -= 2;
410     }
411 
412     assert(mqc->bp[-1] != 0xff);
413 }
414 
415 void opj_mqc_reset_enc(opj_mqc_t *mqc)
416 {
417     opj_mqc_resetstates(mqc);
418     opj_mqc_setstate(mqc, T1_CTXNO_UNI, 0, 46);
419     opj_mqc_setstate(mqc, T1_CTXNO_AGG, 0, 3);
420     opj_mqc_setstate(mqc, T1_CTXNO_ZC, 0, 4);
421 }
422 
423 #ifdef notdef
424 OPJ_UINT32 opj_mqc_restart_enc(opj_mqc_t *mqc)
425 {
426     OPJ_UINT32 correction = 1;
427 
428     /* <flush part> */
429     OPJ_INT32 n = (OPJ_INT32)(27 - 15 - mqc->ct);
430     mqc->c <<= mqc->ct;
431     while (n > 0) {
432         opj_mqc_byteout(mqc);
433         n -= (OPJ_INT32)mqc->ct;
434         mqc->c <<= mqc->ct;
435     }
436     opj_mqc_byteout(mqc);
437 
438     return correction;
439 }
440 #endif
441 
442 void opj_mqc_restart_init_enc(opj_mqc_t *mqc)
443 {
444     /* <Re-init part> */
445 
446     /* As specified in Figure C.10 - Initialization of the encoder */
447     /* (C.2.8 Initialization of the encoder (INITENC)) */
448     mqc->a = 0x8000;
449     mqc->c = 0;
450     mqc->ct = 12;
451     /* This function is normally called after at least one opj_mqc_flush() */
452     /* which will have advance mqc->bp by at least 2 bytes beyond its */
453     /* initial position */
454     mqc->bp --;
455     assert(mqc->bp >= mqc->start - 1);
456     assert(*mqc->bp != 0xff);
457     if (*mqc->bp == 0xff) {
458         mqc->ct = 13;
459     }
460 }
461 
462 void opj_mqc_erterm_enc(opj_mqc_t *mqc)
463 {
464     OPJ_INT32 k = (OPJ_INT32)(11 - mqc->ct + 1);
465 
466     while (k > 0) {
467         mqc->c <<= mqc->ct;
468         mqc->ct = 0;
469         opj_mqc_byteout(mqc);
470         k -= (OPJ_INT32)mqc->ct;
471     }
472 
473     if (*mqc->bp != 0xff) {
474         opj_mqc_byteout(mqc);
475     }
476 }
477 
478 void opj_mqc_segmark_enc(opj_mqc_t *mqc)
479 {
480     OPJ_UINT32 i;
481     opj_mqc_setcurctx(mqc, 18);
482 
483     for (i = 1; i < 5; i++) {
484         opj_mqc_encode(mqc, i % 2);
485     }
486 }
487 
488 static void opj_mqc_init_dec_common(opj_mqc_t *mqc,
489                                     OPJ_BYTE *bp,
490                                     OPJ_UINT32 len,
491                                     OPJ_UINT32 extra_writable_bytes)
492 {
493     (void)extra_writable_bytes;
494 
495     assert(extra_writable_bytes >= OPJ_COMMON_CBLK_DATA_EXTRA);
496     mqc->start = bp;
497     mqc->end = bp + len;
498     /* Insert an artificial 0xFF 0xFF marker at end of the code block */
499     /* data so that the bytein routines stop on it. This saves us comparing */
500     /* the bp and end pointers */
501     /* But before inserting it, backup th bytes we will overwrite */
502     memcpy(mqc->backup, mqc->end, OPJ_COMMON_CBLK_DATA_EXTRA);
503     mqc->end[0] = 0xFF;
504     mqc->end[1] = 0xFF;
505     mqc->bp = bp;
506 }
507 void opj_mqc_init_dec(opj_mqc_t *mqc, OPJ_BYTE *bp, OPJ_UINT32 len,
508                       OPJ_UINT32 extra_writable_bytes)
509 {
510     /* Implements ISO 15444-1 C.3.5 Initialization of the decoder (INITDEC) */
511     /* Note: alternate "J.1 - Initialization of the software-conventions */
512     /* decoder" has been tried, but does */
513     /* not bring any improvement. */
514     /* See https://github.com/uclouvain/openjpeg/issues/921 */
515     opj_mqc_init_dec_common(mqc, bp, len, extra_writable_bytes);
516     opj_mqc_setcurctx(mqc, 0);
517     mqc->end_of_byte_stream_counter = 0;
518     if (len == 0) {
519         mqc->c = 0xff << 16;
520     } else {
521         mqc->c = (OPJ_UINT32)(*mqc->bp << 16);
522     }
523 
524     opj_mqc_bytein(mqc);
525     mqc->c <<= 7;
526     mqc->ct -= 7;
527     mqc->a = 0x8000;
528 }
529 
530 
531 void opj_mqc_raw_init_dec(opj_mqc_t *mqc, OPJ_BYTE *bp, OPJ_UINT32 len,
532                           OPJ_UINT32 extra_writable_bytes)
533 {
534     opj_mqc_init_dec_common(mqc, bp, len, extra_writable_bytes);
535     mqc->c = 0;
536     mqc->ct = 0;
537 }
538 
539 
540 void opq_mqc_finish_dec(opj_mqc_t *mqc)
541 {
542     /* Restore the bytes overwritten by opj_mqc_init_dec_common() */
543     memcpy(mqc->end, mqc->backup, OPJ_COMMON_CBLK_DATA_EXTRA);
544 }
545 
546 void opj_mqc_resetstates(opj_mqc_t *mqc)
547 {
548     OPJ_UINT32 i;
549     for (i = 0; i < MQC_NUMCTXS; i++) {
550         mqc->ctxs[i] = mqc_states;
551     }
552 }
553 
554 void opj_mqc_setstate(opj_mqc_t *mqc, OPJ_UINT32 ctxno, OPJ_UINT32 msb,
555                       OPJ_INT32 prob)
556 {
557     mqc->ctxs[ctxno] = &mqc_states[msb + (OPJ_UINT32)(prob << 1)];
558 }
559 
560 
561