summaryrefslogtreecommitdiffstats
path: root/libavcodec/pcm_tablegen.h
blob: d8763abc40d1c7d608408a05f7a6bd0d60e25396 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
/*
 * Header file for hardcoded PCM tables
 *
 * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVCODEC_PCM_TABLEGEN_H
#define AVCODEC_PCM_TABLEGEN_H

#include <stdint.h>
#include "libavutil/attributes.h"

/* from g711.c by SUN microsystems (unrestricted use) */

#define         SIGN_BIT        (0x80)      /* Sign bit for a A-law byte. */
#define         QUANT_MASK      (0xf)       /* Quantization field mask. */
#define         NSEGS           (8)         /* Number of A-law segments. */
#define         SEG_SHIFT       (4)         /* Left shift for segment number. */
#define         SEG_MASK        (0x70)      /* Segment field mask. */

#define         BIAS            (0x84)      /* Bias for linear code. */

#define         VIDC_SIGN_BIT    (1)
#define         VIDC_QUANT_MASK  (0x1E)
#define         VIDC_QUANT_SHIFT (1)
#define         VIDC_SEG_SHIFT   (5)
#define         VIDC_SEG_MASK    (0xE0)

/* alaw2linear() - Convert an A-law value to 16-bit linear PCM */
static av_cold int alaw2linear(unsigned char a_val)
{
        int t;
        int seg;

        a_val ^= 0x55;

        t = a_val & QUANT_MASK;
        seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT;
        if(seg) t= (t + t + 1 + 32) << (seg + 2);
        else    t= (t + t + 1     ) << 3;

        return (a_val & SIGN_BIT) ? t : -t;
}

static av_cold int ulaw2linear(unsigned char u_val)
{
        int t;

        /* Complement to obtain normal u-law value. */
        u_val = ~u_val;

        /*
         * Extract and bias the quantization bits. Then
         * shift up by the segment number and subtract out the bias.
         */
        t = ((u_val & QUANT_MASK) << 3) + BIAS;
        t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT;

        return (u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS);
}

static av_cold int vidc2linear(unsigned char u_val)
{
        int t;

        /*
         * Extract and bias the quantization bits. Then
         * shift up by the segment number and subtract out the bias.
         */
        t = (((u_val & VIDC_QUANT_MASK) >> VIDC_QUANT_SHIFT) << 3) + BIAS;
        t <<= ((unsigned)u_val & VIDC_SEG_MASK) >> VIDC_SEG_SHIFT;

        return (u_val & VIDC_SIGN_BIT) ? (BIAS - t) : (t - BIAS);
}

#if CONFIG_HARDCODED_TABLES
#define pcm_alaw_tableinit()
#define pcm_ulaw_tableinit()
#define pcm_vidc_tableinit()
#include "libavcodec/pcm_tables.h"
#else
/* 16384 entries per table */
static uint8_t linear_to_alaw[16384];
static uint8_t linear_to_ulaw[16384];
static uint8_t linear_to_vidc[16384];

static av_cold void build_xlaw_table(uint8_t *linear_to_xlaw,
                             int (*xlaw2linear)(unsigned char),
                             int mask)
{
    int i, j, v, v1, v2;

    j = 1;
    linear_to_xlaw[8192] = mask;
    for(i=0;i<127;i++) {
        v1 = xlaw2linear(i ^ mask);
        v2 = xlaw2linear((i + 1) ^ mask);
        v = (v1 + v2 + 4) >> 3;
        for(;j<v;j+=1) {
            linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80));
            linear_to_xlaw[8192 + j] = (i ^ mask);
        }
    }
    for(;j<8192;j++) {
        linear_to_xlaw[8192 - j] = (127 ^ (mask ^ 0x80));
        linear_to_xlaw[8192 + j] = (127 ^ mask);
    }
    linear_to_xlaw[0] = linear_to_xlaw[1];
}

static void pcm_alaw_tableinit(void)
{
    build_xlaw_table(linear_to_alaw, alaw2linear, 0xd5);
}

static void pcm_ulaw_tableinit(void)
{
    build_xlaw_table(linear_to_ulaw, ulaw2linear, 0xff);
}

static void pcm_vidc_tableinit(void)
{
    build_xlaw_table(linear_to_vidc, vidc2linear, 0xff);
}
#endif /* CONFIG_HARDCODED_TABLES */

#endif /* AVCODEC_PCM_TABLEGEN_H */
OpenPOWER on IntegriCloud