apps/fixedpoint.h

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2006 Jens Arnold
  11  *
  12  * Fixed point library for plugins
  13  *
  14  * This program is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU General Public License
  16  * as published by the Free Software Foundation; either version 2
  17  * of the License, or (at your option) any later version.
  18  *
  19  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  20  * KIND, either express or implied.
  21  *
  22  ****************************************************************************/
  23
  24 /** APPS - FIXED POINT MATH ROUTINES - USAGE
  25  *
  26  *  - x and y arguments are fixed point integers
  27  *  - fracbits is the number of fractional bits in the argument(s)
  28  *  - functions return long fixed point integers with the specified number
  29  *    of fractional bits unless otherwise specified
  30  *
  31  *  Multiply two fixed point numbers:
  32  *      fp_mul(x, y, fracbits)
  33  *
  34  *  Divide two fixed point numbers:
  35  *      fp_div(x, y, fracbits)
  36  *
  37  *  Calculate decibel equivalent of a gain factor:
  38  *      fp_decibels(factor, fracbits)
  39  *          where fracbits is in the range 12 to 22 (higher is better),
  40  *          and factor is a positive fixed point integer.
  41  *
  42  *  Calculate factor equivalent of a decibel value:
  43  *      fp_factor(decibels, fracbits)
  44  *          where fracbits is in the range 12 to 22 (lower is better),
  45  *          and decibels is a fixed point integer.
  46  */
  47
  48 #ifndef _FIXEDPOINT_H_APPS
  49 #define _FIXEDPOINT_H_APPS
  50
  51 #define fp_mul(x, y, z) (long)((((long long)(x)) * ((long long)(y))) >> (z))
  52 #define fp_div(x, y, z) (long)((((long long)(x)) << (z)) / ((long long)(y)))
  53
  54
  55 /** TAKEN FROM ORIGINAL fixedpoint.h */
  56 long fp_sincos(unsigned long phase, long *cos);
  57
  58
  59 /** MODIFIED FROM replaygain.c */
  60 #define FP_INF          (0x7fffffff)
  61 #define FP_NEGINF      -(0x7fffffff)
  62
  63 /* fracbits in range 12 - 22 work well. Higher is better for
  64  * calculating dB, lower is better for calculating factor.
  65  */
  66 /* long fp_decibels(unsigned long factor, unsigned int fracbits); */
  67 long fp_factor(long decibels, unsigned int fracbits);
  68
  69 #endif