a6c203ff3bbc8bc8c1c70096f4c3f0b7d38af446
[libav.git] / libavcodec / mpegaudio_tablegen.h
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 Libav.
7 *
8 * Libav 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 * Libav 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 Libav; 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
29 #define TABLE_4_3_SIZE (8191 + 16)*4
30 #if CONFIG_HARDCODED_TABLES
31 #define mpegaudio_tableinit()
32 #include "libavcodec/mpegaudio_tables.h"
33 #else
34 static int8_t table_4_3_exp[TABLE_4_3_SIZE];
35 static uint32_t table_4_3_value[TABLE_4_3_SIZE];
36 static uint32_t exp_table_fixed[512];
37 static uint32_t expval_table_fixed[512][16];
38 static float exp_table_float[512];
39 static float expval_table_float[512][16];
40
41 #define FRAC_BITS 23
42
43 static void mpegaudio_tableinit(void)
44 {
45 int i, value, exponent;
46 for (i = 1; i < TABLE_4_3_SIZE; i++) {
47 double value = i / 4;
48 double f, fm;
49 int e, m;
50 /* cbrtf() isn't available on all systems, so we use powf(). */
51 f = value * powf(value, 1.0 / 3.0) * pow(2, (i & 3) * 0.25);
52 fm = frexp(f, &e);
53 m = (uint32_t)(fm * (1LL << 31) + 0.5);
54 e += FRAC_BITS - 31 + 5 - 100;
55
56 /* normalized to FRAC_BITS */
57 table_4_3_value[i] = m;
58 table_4_3_exp[i] = -e;
59 }
60 for (exponent = 0; exponent < 512; exponent++) {
61 for (value = 0; value < 16; value++) {
62 /* cbrtf() isn't available on all systems, so we use powf(). */
63 double f = (double)value * powf(value, 1.0 / 3.0) * pow(2, (exponent - 400) * 0.25 + FRAC_BITS + 5);
64 expval_table_fixed[exponent][value] = llrint(f);
65 expval_table_float[exponent][value] = f;
66 }
67 exp_table_fixed[exponent] = expval_table_fixed[exponent][1];
68 exp_table_float[exponent] = expval_table_float[exponent][1];
69 }
70 }
71 #endif /* CONFIG_HARDCODED_TABLES */
72
73 #endif /* AVCODEC_MPEGAUDIO_TABLEGEN_H */