1/* 2 * Header file for hardcoded PCM tables 3 * 4 * Copyright (c) 2010 Reimar D��ffinger <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 PCM_TABLEGEN_H 24#define 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 */ 43static 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 58static 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 */ 81static uint8_t linear_to_alaw[16384]; 82static uint8_t linear_to_ulaw[16384]; 83 84static 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 108static void pcm_alaw_tableinit(void) 109{ 110 build_xlaw_table(linear_to_alaw, alaw2linear, 0xd5); 111} 112 113static void pcm_ulaw_tableinit(void) 114{ 115 build_xlaw_table(linear_to_ulaw, ulaw2linear, 0xff); 116} 117#endif /* CONFIG_HARDCODED_TABLES */ 118 119#endif /* PCM_TABLEGEN_H */ 120