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libavcodec/mpegaudio_tablegen.h

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00001 /*
00002  * Header file for hardcoded mpegaudiodec tables
00003  *
00004  * Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 #ifndef AVCODEC_MPEGAUDIO_TABLEGEN_H
00024 #define AVCODEC_MPEGAUDIO_TABLEGEN_H
00025 
00026 #include <stdint.h>
00027 #include <math.h>
00028 
00029 #define TABLE_4_3_SIZE (8191 + 16)*4
00030 #if CONFIG_HARDCODED_TABLES
00031 #define mpegaudio_tableinit()
00032 #include "libavcodec/mpegaudio_tables.h"
00033 #else
00034 static int8_t   table_4_3_exp[TABLE_4_3_SIZE];
00035 static uint32_t table_4_3_value[TABLE_4_3_SIZE];
00036 static uint32_t exp_table_fixed[512];
00037 static uint32_t expval_table_fixed[512][16];
00038 static float exp_table_float[512];
00039 static float expval_table_float[512][16];
00040 
00041 #define FRAC_BITS 23
00042 
00043 static void mpegaudio_tableinit(void)
00044 {
00045     int i, value, exponent;
00046     for (i = 1; i < TABLE_4_3_SIZE; i++) {
00047         double value = i / 4;
00048         double f, fm;
00049         int e, m;
00050         f  = value * cbrtf(value) * pow(2, (i & 3) * 0.25);
00051         fm = frexp(f, &e);
00052         m  = (uint32_t)(fm * (1LL << 31) + 0.5);
00053         e += FRAC_BITS - 31 + 5 - 100;
00054 
00055         /* normalized to FRAC_BITS */
00056         table_4_3_value[i] =  m;
00057         table_4_3_exp[i]   = -e;
00058     }
00059     for (exponent = 0; exponent < 512; exponent++) {
00060         for (value = 0; value < 16; value++) {
00061             double f = (double)value * cbrtf(value) * pow(2, (exponent - 400) * 0.25 + FRAC_BITS + 5);
00062             expval_table_fixed[exponent][value] = llrint(f);
00063             expval_table_float[exponent][value] = f;
00064         }
00065         exp_table_fixed[exponent] = expval_table_fixed[exponent][1];
00066         exp_table_float[exponent] = expval_table_float[exponent][1];
00067     }
00068 }
00069 #endif /* CONFIG_HARDCODED_TABLES */
00070 
00071 #endif /* AVCODEC_MPEGAUDIO_TABLEGEN_H */

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