GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/mqcdec.c Lines: 45 53 84.9 %
Date: 2019-11-20 04:07:19 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
15972024
static void bytein(MqcState *mqc)
31
{
32
15972024
    if (*mqc->bp == 0xff) {
33
447940
        if (*(mqc->bp + 1) > 0x8f)
34
385409
            mqc->c++;
35
        else {
36
62531
            mqc->bp++;
37
62531
            mqc->c += 2 + 0xfe00 - (*mqc->bp << 9);
38
        }
39
    } else {
40
15524084
        mqc->bp++;
41
15524084
        mqc->c += 1 + 0xff00 - (*mqc->bp << 8);
42
    }
43
15972024
}
44
45
88273842
static int exchange(MqcState *mqc, uint8_t *cxstate, int lps)
46
{
47
    int d;
48
88273842
    if ((mqc->a < ff_mqc_qe[*cxstate]) ^ (!lps)) {
49
46699411
        if (lps)
50
8992607
            mqc->a = ff_mqc_qe[*cxstate];
51
46699411
        d = *cxstate & 1;
52
46699411
        *cxstate = ff_mqc_nmps[*cxstate];
53
    } else {
54
41574431
        if (lps)
55
34304675
            mqc->a = ff_mqc_qe[*cxstate];
56
41574431
        d = 1 - (*cxstate & 1);
57
41574431
        *cxstate = ff_mqc_nlps[*cxstate];
58
    }
59
    // do RENORMD: see ISO/IEC 15444-1:2002 §C.3.3
60
    do {
61
124024020
        if (!(mqc->c & 0xff)) {
62
15609296
            mqc->c -= 0x100;
63
15609296
            bytein(mqc);
64
        }
65
124024020
        mqc->a += mqc->a;
66
124024020
        mqc->c += mqc->c;
67
124024020
    } while (!(mqc->a & 0x8000));
68
88273842
    return d;
69
}
70
71
362728
void ff_mqc_initdec(MqcState *mqc, uint8_t *bp, int raw, int reset)
72
{
73
362728
    mqc->raw = raw;
74
362728
    if (reset)
75
362728
        ff_mqc_init_contexts(mqc);
76
362728
    mqc->bp = bp;
77
362728
    mqc->c  = (*mqc->bp ^ 0xff) << 16;
78
362728
    bytein(mqc);
79
362728
    mqc->c = mqc->c << 7;
80
362728
    mqc->a = 0x8000;
81
362728
}
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
182845733
int ff_mqc_decode(MqcState *mqc, uint8_t *cxstate)
94
{
95
182845733
    if (mqc->raw)
96
        return mqc_decode_bypass(mqc);
97
182845733
    mqc->a -= ff_mqc_qe[*cxstate];
98
182845733
    if ((mqc->c >> 16) < mqc->a) {
99
139548451
        if (mqc->a & 0x8000)
100
94571891
            return *cxstate & 1;
101
        else
102
44976560
            return exchange(mqc, cxstate, 0);
103
    } else {
104
43297282
        mqc->c -= mqc->a << 16;
105
43297282
        return exchange(mqc, cxstate, 1);
106
    }
107
}