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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 "mqc.h" | |
29 | ||
30 | static void byteout(MqcState *mqc) | |
31 | { | |
32 | retry: | |
33 | if (*mqc->bp == 0xff){ | |
34 | mqc->bp++; | |
35 | *mqc->bp = mqc->c >> 20; | |
36 | mqc->c &= 0xfffff; | |
37 | mqc->ct = 7; | |
38 | } else if ((mqc->c & 0x8000000)){ | |
39 | (*mqc->bp)++; | |
40 | mqc->c &= 0x7ffffff; | |
41 | goto retry; | |
42 | } else{ | |
43 | mqc->bp++; | |
44 | *mqc->bp = mqc->c >> 19; | |
45 | mqc->c &= 0x7ffff; | |
46 | mqc->ct = 8; | |
47 | } | |
48 | } | |
49 | ||
50 | static void renorme(MqcState *mqc) | |
51 | { | |
52 | do{ | |
53 | mqc->a += mqc->a; | |
54 | mqc->c += mqc->c; | |
55 | if (!--mqc->ct) | |
56 | byteout(mqc); | |
57 | } while (!(mqc->a & 0x8000)); | |
58 | } | |
59 | ||
60 | static void setbits(MqcState *mqc) | |
61 | { | |
62 | int tmp = mqc->c + mqc->a; | |
63 | mqc->c |= 0xffff; | |
64 | if (mqc->c >= tmp) | |
65 | mqc->c -= 0x8000; | |
66 | } | |
67 | ||
68 | void ff_mqc_initenc(MqcState *mqc, uint8_t *bp) | |
69 | { | |
70 | ff_mqc_init_contexts(mqc); | |
71 | mqc->a = 0x8000; | |
72 | mqc->c = 0; | |
73 | mqc->bp = bp-1; | |
74 | mqc->bpstart = bp; | |
75 | mqc->ct = 12 + (*mqc->bp == 0xff); | |
76 | } | |
77 | ||
78 | void ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d) | |
79 | { | |
80 | int qe; | |
81 | ||
82 | qe = ff_mqc_qe[*cxstate]; | |
83 | mqc->a -= qe; | |
84 | if ((*cxstate & 1) == d){ | |
85 | if (!(mqc->a & 0x8000)){ | |
86 | if (mqc->a < qe) | |
87 | mqc->a = qe; | |
88 | else | |
89 | mqc->c += qe; | |
90 | *cxstate = ff_mqc_nmps[*cxstate]; | |
91 | renorme(mqc); | |
92 | } else | |
93 | mqc->c += qe; | |
94 | } else{ | |
95 | if (mqc->a < qe) | |
96 | mqc->c += qe; | |
97 | else | |
98 | mqc->a = qe; | |
99 | *cxstate = ff_mqc_nlps[*cxstate]; | |
100 | renorme(mqc); | |
101 | } | |
102 | } | |
103 | ||
104 | int ff_mqc_length(MqcState *mqc) | |
105 | { | |
106 | return mqc->bp - mqc->bpstart; | |
107 | } | |
108 | ||
109 | int ff_mqc_flush(MqcState *mqc) | |
110 | { | |
111 | setbits(mqc); | |
112 | mqc->c = mqc->c << mqc->ct; | |
113 | byteout(mqc); | |
114 | mqc->c = mqc->c << mqc->ct; | |
115 | byteout(mqc); | |
116 | if (*mqc->bp != 0xff) | |
117 | mqc->bp++; | |
118 | return mqc->bp - mqc->bpstart; | |
119 | } |