1 /*
2 * MQ-coder encoder
3 * Copyright (c) 2007 Kamil Nowosad
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * MQ-coder encoder
24 * @file
25 * @author Kamil Nowosad
26 */
27
28 #include <string.h>
29
30 #include "libavutil/avassert.h"
31 #include "mqc.h"
32
byteout(MqcState *mqc)33 static void byteout(MqcState *mqc)
34 {
35 retry:
36 if (*mqc->bp == 0xff){
37 mqc->bp++;
38 *mqc->bp = mqc->c >> 20;
39 mqc->c &= 0xfffff;
40 mqc->ct = 7;
41 } else if ((mqc->c & 0x8000000)){
42 (*mqc->bp)++;
43 mqc->c &= 0x7ffffff;
44 goto retry;
45 } else{
46 mqc->bp++;
47 *mqc->bp = mqc->c >> 19;
48 mqc->c &= 0x7ffff;
49 mqc->ct = 8;
50 }
51 }
52
renorme(MqcState *mqc)53 static void renorme(MqcState *mqc)
54 {
55 do{
56 mqc->a += mqc->a;
57 mqc->c += mqc->c;
58 if (!--mqc->ct)
59 byteout(mqc);
60 } while (!(mqc->a & 0x8000));
61 }
62
setbits(MqcState *mqc)63 static void setbits(MqcState *mqc)
64 {
65 int tmp = mqc->c + mqc->a;
66 mqc->c |= 0xffff;
67 if (mqc->c >= tmp)
68 mqc->c -= 0x8000;
69 }
70
ff_mqc_initenc(MqcState *mqc, uint8_t *bp)71 void ff_mqc_initenc(MqcState *mqc, uint8_t *bp)
72 {
73 ff_mqc_init_contexts(mqc);
74 mqc->a = 0x8000;
75 mqc->c = 0;
76 mqc->bp = bp-1;
77 mqc->bpstart = bp;
78 mqc->ct = 12 + (*mqc->bp == 0xff);
79 }
80
ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d)81 void ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d)
82 {
83 int qe;
84
85 qe = ff_mqc_qe[*cxstate];
86 mqc->a -= qe;
87 if ((*cxstate & 1) == d){
88 if (!(mqc->a & 0x8000)){
89 if (mqc->a < qe)
90 mqc->a = qe;
91 else
92 mqc->c += qe;
93 *cxstate = ff_mqc_nmps[*cxstate];
94 renorme(mqc);
95 } else
96 mqc->c += qe;
97 } else{
98 if (mqc->a < qe)
99 mqc->c += qe;
100 else
101 mqc->a = qe;
102 *cxstate = ff_mqc_nlps[*cxstate];
103 renorme(mqc);
104 }
105 }
106
mqc_flush(MqcState *mqc)107 static int mqc_flush(MqcState *mqc)
108 {
109 setbits(mqc);
110 mqc->c = mqc->c << mqc->ct;
111 byteout(mqc);
112 mqc->c = mqc->c << mqc->ct;
113 byteout(mqc);
114 if (*mqc->bp != 0xff)
115 mqc->bp++;
116 return mqc->bp - mqc->bpstart;
117 }
118
ff_mqc_flush_to(MqcState *mqc, uint8_t *dst, int *dst_len)119 int ff_mqc_flush_to(MqcState *mqc, uint8_t *dst, int *dst_len)
120 {
121 MqcState mqc2 = *mqc;
122 mqc2.bpstart=
123 mqc2.bp = dst;
124 *mqc2.bp = *mqc->bp;
125 mqc_flush(&mqc2);
126 *dst_len = mqc2.bp - dst;
127 if (mqc->bp < mqc->bpstart) {
128 av_assert1(mqc->bpstart - mqc->bp == 1);
129 av_assert1(*dst_len > 0);
130 av_assert1(mqc->bp[0] == 0 && dst[0] == 0);
131 (*dst_len) --;
132 memmove(dst, dst+1, *dst_len);
133 return mqc->bp - mqc->bpstart + 1 + *dst_len;
134 }
135 return mqc->bp - mqc->bpstart + *dst_len;
136 }
137