09c2d08c
 Hu Chunming
arm交付版
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/*
* Header file for hardcoded shared mpegaudiodec tables
*
* Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
* Copyright (c) 2020 Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
*
* 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_MPEGAUDIODEC_COMMON_TABLEGEN_H
#define AVCODEC_MPEGAUDIODEC_COMMON_TABLEGEN_H
#include <stdint.h>
#define TABLE_4_3_SIZE ((8191 + 16)*4)
#if CONFIG_HARDCODED_TABLES
#define mpegaudiodec_common_tableinit()
#include "libavcodec/mpegaudiodec_common_tables.h"
#else
#include <math.h>
#include "libavutil/attributes.h"
int8_t ff_table_4_3_exp [TABLE_4_3_SIZE];
uint32_t ff_table_4_3_value[TABLE_4_3_SIZE];
#define FRAC_BITS 23
#define IMDCT_SCALAR 1.759
static av_cold void mpegaudiodec_common_tableinit(void)
{
static const double exp2_lut[4] = {
1.00000000000000000000, /* 2 ^ (0 * 0.25) */
1.18920711500272106672, /* 2 ^ (1 * 0.25) */
M_SQRT2 , /* 2 ^ (2 * 0.25) */
1.68179283050742908606, /* 2 ^ (3 * 0.25) */
};
double pow43_val = 0;
for (int i = 1; i < TABLE_4_3_SIZE; i++) {
double f, fm;
int e, m;
double value = i / 4;
if ((i & 3) == 0)
pow43_val = value / IMDCT_SCALAR * cbrt(value);
f = pow43_val * exp2_lut[i & 3];
fm = frexp(f, &e);
m = llrint(fm * (1LL << 31));
e += FRAC_BITS - 31 + 5 - 100;
/* normalized to FRAC_BITS */
ff_table_4_3_value[i] = m;
ff_table_4_3_exp [i] = -e;
}
}
#endif /* CONFIG_HARDCODED_TABLES */
#endif /* AVCODEC_MPEGAUDIODEC_COMMON_TABLEGEN_H */
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