ffmpeg/libavcodec/cbrt_tablegen.h

   1 /*
   2  * Header file for hardcoded AAC cube-root table
   3  *
   4  * Copyright (c) 2010 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_CBRT_TABLEGEN_H
  24 #define AVCODEC_CBRT_TABLEGEN_H
  25
  26 #include <stdint.h>
  27 #include <math.h>
  28 #include "libavutil/attributes.h"
  29
  30 #if CONFIG_HARDCODED_TABLES
  31 #define cbrt_tableinit()
  32 #include "libavcodec/cbrt_tables.h"
  33 #else
  34 static uint32_t cbrt_tab[1 << 13];
  35
  36 static av_cold void cbrt_tableinit(void)
  37 {
  38     if (!cbrt_tab[(1<<13) - 1]) {
  39         int i;
  40         /* cbrtf() isn't available on all systems, so we use powf(). */
  41         for (i = 0; i < 1<<13; i++) {
  42             union {
  43                 float f;
  44                 uint32_t i;
  45             } f;
  46             f.f = pow(i, 1.0 / 3.0) * i;
  47             cbrt_tab[i] = f.i;
  48         }
  49     }
  50 }
  51 #endif /* CONFIG_HARDCODED_TABLES */
  52
  53 #endif /* AVCODEC_CBRT_TABLEGEN_H */