mpegaudiodec_common_tablegen.h (2342B)
1 /* 2 * Header file for hardcoded shared mpegaudiodec tables 3 * 4 * Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de> 5 * Copyright (c) 2020 Andreas Rheinhardt <andreas.rheinhardt@gmail.com> 6 * 7 * This file is part of FFmpeg. 8 * 9 * FFmpeg is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU Lesser General Public 11 * License as published by the Free Software Foundation; either 12 * version 2.1 of the License, or (at your option) any later version. 13 * 14 * FFmpeg is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 * Lesser General Public License for more details. 18 * 19 * You should have received a copy of the GNU Lesser General Public 20 * License along with FFmpeg; if not, write to the Free Software 21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 22 */ 23 24 #ifndef AVCODEC_MPEGAUDIODEC_COMMON_TABLEGEN_H 25 #define AVCODEC_MPEGAUDIODEC_COMMON_TABLEGEN_H 26 27 #include <stdint.h> 28 29 #define TABLE_4_3_SIZE ((8191 + 16)*4) 30 31 #if CONFIG_HARDCODED_TABLES 32 #define mpegaudiodec_common_tableinit() 33 #include "libavcodec/mpegaudiodec_common_tables.h" 34 #else 35 #include <math.h> 36 #include "libavutil/attributes.h" 37 38 int8_t ff_table_4_3_exp [TABLE_4_3_SIZE]; 39 uint32_t ff_table_4_3_value[TABLE_4_3_SIZE]; 40 41 #define FRAC_BITS 23 42 #define IMDCT_SCALAR 1.759 43 44 static av_cold void mpegaudiodec_common_tableinit(void) 45 { 46 static const double exp2_lut[4] = { 47 1.00000000000000000000, /* 2 ^ (0 * 0.25) */ 48 1.18920711500272106672, /* 2 ^ (1 * 0.25) */ 49 M_SQRT2 , /* 2 ^ (2 * 0.25) */ 50 1.68179283050742908606, /* 2 ^ (3 * 0.25) */ 51 }; 52 double pow43_val = 0; 53 54 for (int i = 1; i < TABLE_4_3_SIZE; i++) { 55 double f, fm; 56 int e, m; 57 double value = i / 4; 58 if ((i & 3) == 0) 59 pow43_val = value / IMDCT_SCALAR * cbrt(value); 60 f = pow43_val * exp2_lut[i & 3]; 61 fm = frexp(f, &e); 62 m = llrint(fm * (1LL << 31)); 63 e += FRAC_BITS - 31 + 5 - 100; 64 65 /* normalized to FRAC_BITS */ 66 ff_table_4_3_value[i] = m; 67 ff_table_4_3_exp [i] = -e; 68 } 69 } 70 71 #endif /* CONFIG_HARDCODED_TABLES */ 72 #endif /* AVCODEC_MPEGAUDIODEC_COMMON_TABLEGEN_H */