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1 | /* |
2 | * Header file for hardcoded PCM tables | |
3 | * | |
4 | * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de> | |
5 | * | |
6 | * This file is part of FFmpeg. | |
7 | * | |
8 | * FFmpeg is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * FFmpeg is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with FFmpeg; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
23 | #ifndef AVCODEC_PCM_TABLEGEN_H | |
24 | #define AVCODEC_PCM_TABLEGEN_H | |
25 | ||
26 | #include <stdint.h> | |
27 | #include "libavutil/attributes.h" | |
28 | ||
29 | /* from g711.c by SUN microsystems (unrestricted use) */ | |
30 | ||
31 | #define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */ | |
32 | #define QUANT_MASK (0xf) /* Quantization field mask. */ | |
33 | #define NSEGS (8) /* Number of A-law segments. */ | |
34 | #define SEG_SHIFT (4) /* Left shift for segment number. */ | |
35 | #define SEG_MASK (0x70) /* Segment field mask. */ | |
36 | ||
37 | #define BIAS (0x84) /* Bias for linear code. */ | |
38 | ||
39 | /* | |
40 | * alaw2linear() - Convert an A-law value to 16-bit linear PCM | |
41 | * | |
42 | */ | |
43 | static av_cold int alaw2linear(unsigned char a_val) | |
44 | { | |
45 | int t; | |
46 | int seg; | |
47 | ||
48 | a_val ^= 0x55; | |
49 | ||
50 | t = a_val & QUANT_MASK; | |
51 | seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT; | |
52 | if(seg) t= (t + t + 1 + 32) << (seg + 2); | |
53 | else t= (t + t + 1 ) << 3; | |
54 | ||
55 | return (a_val & SIGN_BIT) ? t : -t; | |
56 | } | |
57 | ||
58 | static av_cold int ulaw2linear(unsigned char u_val) | |
59 | { | |
60 | int t; | |
61 | ||
62 | /* Complement to obtain normal u-law value. */ | |
63 | u_val = ~u_val; | |
64 | ||
65 | /* | |
66 | * Extract and bias the quantization bits. Then | |
67 | * shift up by the segment number and subtract out the bias. | |
68 | */ | |
69 | t = ((u_val & QUANT_MASK) << 3) + BIAS; | |
70 | t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT; | |
71 | ||
72 | return (u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS); | |
73 | } | |
74 | ||
75 | #if CONFIG_HARDCODED_TABLES | |
76 | #define pcm_alaw_tableinit() | |
77 | #define pcm_ulaw_tableinit() | |
78 | #include "libavcodec/pcm_tables.h" | |
79 | #else | |
80 | /* 16384 entries per table */ | |
81 | static uint8_t linear_to_alaw[16384]; | |
82 | static uint8_t linear_to_ulaw[16384]; | |
83 | ||
84 | static av_cold void build_xlaw_table(uint8_t *linear_to_xlaw, | |
85 | int (*xlaw2linear)(unsigned char), | |
86 | int mask) | |
87 | { | |
88 | int i, j, v, v1, v2; | |
89 | ||
90 | j = 0; | |
91 | for(i=0;i<128;i++) { | |
92 | if (i != 127) { | |
93 | v1 = xlaw2linear(i ^ mask); | |
94 | v2 = xlaw2linear((i + 1) ^ mask); | |
95 | v = (v1 + v2 + 4) >> 3; | |
96 | } else { | |
97 | v = 8192; | |
98 | } | |
99 | for(;j<v;j++) { | |
100 | linear_to_xlaw[8192 + j] = (i ^ mask); | |
101 | if (j > 0) | |
102 | linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80)); | |
103 | } | |
104 | } | |
105 | linear_to_xlaw[0] = linear_to_xlaw[1]; | |
106 | } | |
107 | ||
108 | static void pcm_alaw_tableinit(void) | |
109 | { | |
110 | build_xlaw_table(linear_to_alaw, alaw2linear, 0xd5); | |
111 | } | |
112 | ||
113 | static void pcm_ulaw_tableinit(void) | |
114 | { | |
115 | build_xlaw_table(linear_to_ulaw, ulaw2linear, 0xff); | |
116 | } | |
117 | #endif /* CONFIG_HARDCODED_TABLES */ | |
118 | ||
119 | #endif /* AVCODEC_PCM_TABLEGEN_H */ |