media/ffvpx/libavcodec/pcm_tablegen.h

   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 #define         VIDC_SIGN_BIT    (1)
  40 #define         VIDC_QUANT_MASK  (0x1E)
  41 #define         VIDC_QUANT_SHIFT (1)
  42 #define         VIDC_SEG_SHIFT   (5)
  43 #define         VIDC_SEG_MASK    (0xE0)
  44
  45 /* alaw2linear() - Convert an A-law value to 16-bit linear PCM */
  46 static av_cold int alaw2linear(unsigned char a_val)
  47 {
  48     int t;
  49     int seg;
  50
  51     a_val ^= 0x55;
  52
  53     t = a_val & QUANT_MASK;
  54     seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT;
  55     if(seg) t= (t + t + 1 + 32) << (seg + 2);
  56     else    t= (t + t + 1     ) << 3;
  57
  58     return (a_val & SIGN_BIT) ? t : -t;
  59 }
  60
  61 static av_cold int ulaw2linear(unsigned char u_val)
  62 {
  63     int t;
  64
  65     /* Complement to obtain normal u-law value. */
  66     u_val = ~u_val;
  67
  68     /*
  69      * Extract and bias the quantization bits. Then
  70      * shift up by the segment number and subtract out the bias.
  71      */
  72     t = ((u_val & QUANT_MASK) << 3) + BIAS;
  73     t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT;
  74
  75     return (u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS);
  76 }
  77
  78 static av_cold int vidc2linear(unsigned char u_val)
  79 {
  80     int t;
  81
  82     /*
  83      * Extract and bias the quantization bits. Then
  84      * shift up by the segment number and subtract out the bias.
  85      */
  86     t = (((u_val & VIDC_QUANT_MASK) >> VIDC_QUANT_SHIFT) << 3) + BIAS;
  87     t <<= ((unsigned)u_val & VIDC_SEG_MASK) >> VIDC_SEG_SHIFT;
  88
  89     return (u_val & VIDC_SIGN_BIT) ? (BIAS - t) : (t - BIAS);
  90 }
  91
  92 #if CONFIG_HARDCODED_TABLES
  93 #define pcm_alaw_tableinit()
  94 #define pcm_ulaw_tableinit()
  95 #define pcm_vidc_tableinit()
  96 #include "libavcodec/pcm_tables.h"
  97 #else
  98 /* 16384 entries per table */
  99 static uint8_t linear_to_alaw[16384];
 100 static uint8_t linear_to_ulaw[16384];
 101 static uint8_t linear_to_vidc[16384];
 102
 103 static av_cold void build_xlaw_table(uint8_t *linear_to_xlaw,
 104                              int (*xlaw2linear)(unsigned char),
 105                              int mask)
 106 {
 107     int i, j, v, v1, v2;
 108
 109     j = 1;
 110     linear_to_xlaw[8192] = mask;
 111     for(i=0;i<127;i++) {
 112         v1 = xlaw2linear(i ^ mask);
 113         v2 = xlaw2linear((i + 1) ^ mask);
 114         v = (v1 + v2 + 4) >> 3;
 115         for(;j<v;j+=1) {
 116             linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80));
 117             linear_to_xlaw[8192 + j] = (i ^ mask);
 118         }
 119     }
 120     for(;j<8192;j++) {
 121         linear_to_xlaw[8192 - j] = (127 ^ (mask ^ 0x80));
 122         linear_to_xlaw[8192 + j] = (127 ^ mask);
 123     }
 124     linear_to_xlaw[0] = linear_to_xlaw[1];
 125 }
 126
 127 static void pcm_alaw_tableinit(void)
 128 {
 129     build_xlaw_table(linear_to_alaw, alaw2linear, 0xd5);
 130 }
 131
 132 static void pcm_ulaw_tableinit(void)
 133 {
 134     build_xlaw_table(linear_to_ulaw, ulaw2linear, 0xff);
 135 }
 136
 137 static void pcm_vidc_tableinit(void)
 138 {
 139     build_xlaw_table(linear_to_vidc, vidc2linear, 0xff);
 140 }
 141 #endif /* CONFIG_HARDCODED_TABLES */
 142
 143 #endif /* AVCODEC_PCM_TABLEGEN_H */