mpegaudio_tablegen.h (2824B)
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 36 static uint32_t exp_table_fixed[512]; 37 static uint32_t expval_table_fixed[512][16]; 38 #endif 39 40 #if defined(BUILD_TABLES) || USE_FLOATS 41 #define FLOAT_TABLE 42 static float exp_table_float[512]; 43 static float expval_table_float[512][16]; 44 #endif 45 46 #define IMDCT_SCALAR 1.759 47 48 static 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 */