2 * Header file for hardcoded mpegaudiodec tables
4 * Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
6 * This file is part of FFmpeg.
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.
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.
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
23 #ifndef AVCODEC_MPEGAUDIO_TABLEGEN_H
24 #define AVCODEC_MPEGAUDIO_TABLEGEN_H
28 #include "libavutil/attributes.h"
30 #define TABLE_4_3_SIZE (8191 + 16)*4
31 #if CONFIG_HARDCODED_TABLES
32 #define mpegaudio_tableinit()
33 #include "libavcodec/mpegaudio_tables.h"
35 static int8_t table_4_3_exp[TABLE_4_3_SIZE];
36 static uint32_t table_4_3_value[TABLE_4_3_SIZE];
38 #if defined(BUILD_TABLES) || !USE_FLOATS
40 static uint32_t exp_table_fixed[512];
41 static uint32_t expval_table_fixed[512][16];
44 #if defined(BUILD_TABLES) || USE_FLOATS
46 static float exp_table_float[512];
47 static float expval_table_float[512][16];
51 #define IMDCT_SCALAR 1.759
53 static av_cold void mpegaudio_tableinit(void)
55 int i, value, exponent;
56 static const double exp2_lut[4] = {
57 1.00000000000000000000, /* 2 ^ (0 * 0.25) */
58 1.18920711500272106672, /* 2 ^ (1 * 0.25) */
59 M_SQRT2 , /* 2 ^ (2 * 0.25) */
60 1.68179283050742908606, /* 2 ^ (3 * 0.25) */
62 static double pow43_lut[16];
63 double exp2_base = 2.11758236813575084767080625169910490512847900390625e-22; // 2^(-72)
66 for (i = 0; i < 16; ++i)
67 pow43_lut[i] = i * cbrt(i);
69 for (i = 1; i < TABLE_4_3_SIZE; i++) {
74 pow43_val = value / IMDCT_SCALAR * cbrt(value);
75 f = pow43_val * exp2_lut[i & 3];
77 m = llrint(fm * (1LL << 31));
78 e += FRAC_BITS - 31 + 5 - 100;
80 /* normalized to FRAC_BITS */
81 table_4_3_value[i] = m;
82 table_4_3_exp[i] = -e;
84 for (exponent = 0; exponent < 512; exponent++) {
85 if (exponent && (exponent & 3) == 0)
87 exp2_val = exp2_base * exp2_lut[exponent & 3] / IMDCT_SCALAR;
88 for (value = 0; value < 16; value++) {
89 double f = pow43_lut[value] * exp2_val;
91 expval_table_fixed[exponent][value] = (f < 0xFFFFFFFF ? llrint(f) : 0xFFFFFFFF);
94 expval_table_float[exponent][value] = f;
98 exp_table_fixed[exponent] = expval_table_fixed[exponent][1];
101 exp_table_float[exponent] = expval_table_float[exponent][1];
107 #endif /* CONFIG_HARDCODED_TABLES */
109 #endif /* AVCODEC_MPEGAUDIO_TABLEGEN_H */