FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/mqcdec.c
Date: 2021-09-26 18:22:30
Exec Total Coverage
Lines: 45 53 84.9%
Branches: 20 24 83.3%

Line Branch Exec Source
1 /*
2 * MQ-coder decoder
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 decoder
24 * @file
25 * @author Kamil Nowosad
26 */
27
28 #include "mqc.h"
29
30 16161272 static void bytein(MqcState *mqc)
31 {
32
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16161272 if (*mqc->bp == 0xff) {
33
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473157 if (*(mqc->bp + 1) > 0x8f)
34 407651 mqc->c++;
35 else {
36 65506 mqc->bp++;
37 65506 mqc->c += 2 + 0xfe00 - (*mqc->bp << 9);
38 }
39 } else {
40 15688115 mqc->bp++;
41 15688115 mqc->c += 1 + 0xff00 - (*mqc->bp << 8);
42 }
43 16161272 }
44
45 88937633 static int exchange(MqcState *mqc, uint8_t *cxstate, int lps)
46 {
47 int d;
48
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88937633 if ((mqc->a < ff_mqc_qe[*cxstate]) ^ (!lps)) {
49
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47134844 if (lps)
50 9071787 mqc->a = ff_mqc_qe[*cxstate];
51 47134844 d = *cxstate & 1;
52 47134844 *cxstate = ff_mqc_nmps[*cxstate];
53 } else {
54
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41802789 if (lps)
55 34488874 mqc->a = ff_mqc_qe[*cxstate];
56 41802789 d = 1 - (*cxstate & 1);
57 41802789 *cxstate = ff_mqc_nlps[*cxstate];
58 }
59 // do RENORMD: see ISO/IEC 15444-1:2002 §C.3.3
60 do {
61
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125009704 if (!(mqc->c & 0xff)) {
62 15762913 mqc->c -= 0x100;
63 15762913 bytein(mqc);
64 }
65 125009704 mqc->a += mqc->a;
66 125009704 mqc->c += mqc->c;
67
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125009704 } while (!(mqc->a & 0x8000));
68 88937633 return d;
69 }
70
71 398359 void ff_mqc_initdec(MqcState *mqc, uint8_t *bp, int raw, int reset)
72 {
73 398359 mqc->raw = raw;
74
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398359 if (reset)
75 398359 ff_mqc_init_contexts(mqc);
76 398359 mqc->bp = bp;
77 398359 mqc->c = (*mqc->bp ^ 0xff) << 16;
78 398359 bytein(mqc);
79 398359 mqc->c = mqc->c << 7;
80 398359 mqc->a = 0x8000;
81 398359 }
82
83 static int mqc_decode_bypass(MqcState *mqc) {
84 int bit = !(mqc->c & 0x40000000);
85 if (!(mqc->c & 0xff)) {
86 mqc->c -= 0x100;
87 bytein(mqc);
88 }
89 mqc->c += mqc->c;
90 return bit;
91 }
92
93 185774934 int ff_mqc_decode(MqcState *mqc, uint8_t *cxstate)
94 {
95
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185774934 if (mqc->raw)
96 return mqc_decode_bypass(mqc);
97 185774934 mqc->a -= ff_mqc_qe[*cxstate];
98
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185774934 if ((mqc->c >> 16) < mqc->a) {
99
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142214273 if (mqc->a & 0x8000)
100 96837301 return *cxstate & 1;
101 else
102 45376972 return exchange(mqc, cxstate, 0);
103 } else {
104 43560661 mqc->c -= mqc->a << 16;
105 43560661 return exchange(mqc, cxstate, 1);
106 }
107 }
108