1/*
2 * Header file for hardcoded mpegaudiodec tables
3 *
4 * Copyright (c) 2009 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_MPEGAUDIO_TABLEGEN_H
24#define AVCODEC_MPEGAUDIO_TABLEGEN_H
25
26#include <stdint.h>
27#include <math.h>
28#include "libavutil/attributes.h"
29
30#if CONFIG_HARDCODED_TABLES
31#define mpegaudio_tableinit()
32#include "libavcodec/mpegaudio_tables.h"
33#else
34#if defined(BUILD_TABLES) || !USE_FLOATS
35#define FIXED_TABLE
36static uint32_t exp_table_fixed[512];
37static uint32_t expval_table_fixed[512][16];
38#endif
39
40#if defined(BUILD_TABLES) || USE_FLOATS
41#define FLOAT_TABLE
42static float exp_table_float[512];
43static float expval_table_float[512][16];
44#endif
45
46#define IMDCT_SCALAR 1.759
47
48static av_cold void mpegaudio_tableinit(void)
49{
50    int i, value, exponent;
51    static const double exp2_lut[4] = {
52        1.00000000000000000000, /* 2 ^ (0 * 0.25) */
53        1.18920711500272106672, /* 2 ^ (1 * 0.25) */
54        M_SQRT2               , /* 2 ^ (2 * 0.25) */
55        1.68179283050742908606, /* 2 ^ (3 * 0.25) */
56    };
57    double pow43_lut[16];
58    double exp2_base = 2.11758236813575084767080625169910490512847900390625e-22; // 2^(-72)
59    double exp2_val;
60
61    for (i = 0; i < 16; ++i)
62        pow43_lut[i] = i * cbrt(i);
63
64    for (exponent = 0; exponent < 512; exponent++) {
65        if (exponent && (exponent & 3) == 0)
66            exp2_base *= 2;
67        exp2_val = exp2_base * exp2_lut[exponent & 3] / IMDCT_SCALAR;
68        for (value = 0; value < 16; value++) {
69            double f = pow43_lut[value] * exp2_val;
70#ifdef FIXED_TABLE
71            expval_table_fixed[exponent][value] = (f < 0xFFFFFFFF ? llrint(f) : 0xFFFFFFFF);
72#endif
73#ifdef FLOAT_TABLE
74            expval_table_float[exponent][value] = f;
75#endif
76        }
77#ifdef FIXED_TABLE
78        exp_table_fixed[exponent] = expval_table_fixed[exponent][1];
79#endif
80#ifdef FLOAT_TABLE
81        exp_table_float[exponent] = expval_table_float[exponent][1];
82#endif
83    }
84}
85#undef FLOAT_TABLE
86#undef FIXED_TABLE
87#endif /* CONFIG_HARDCODED_TABLES */
88
89#endif /* AVCODEC_MPEGAUDIO_TABLEGEN_H */
90