v2/util_math.c

   1 /*----------------------------------------------------------------------------
   2     ChucK Concurrent, On-the-fly Audio Programming Language
   3       Compiler and Virtual Machine
   4
   5     Copyright (c) 2004 Ge Wang and Perry R. Cook.  All rights reserved.
   6       http://chuck.cs.princeton.edu/
   7       http://soundlab.cs.princeton.edu/
   8
   9     This program is free software; you can redistribute it and/or modify
  10     it under the terms of the GNU General Public License as published by
  11     the Free Software Foundation; either version 2 of the License, or
  12     (at your option) any later version.
  13
  14     This program 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
  17     GNU General Public License for more details.
  18
  19     You should have received a copy of the GNU General Public License
  20     along with this program; if not, write to the Free Software
  21     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  22     U.S.A.
  23 -----------------------------------------------------------------------------*/
  24
  25 //-----------------------------------------------------------------------------
  26 // name: util_math.c
  27 // desc: ...
  28 //
  29 // author: Ge Wang (gewang@cs.princeton.edu)
  30 //         Perry R. Cook (prc@cs.princeton.edu)
  31 //         Philip Davidson (philipd@alumni.princeton.edu)
  32 // date: Spring 2004
  33 //-----------------------------------------------------------------------------
  34 #include "util_math.h"
  35 #include <math.h>
  36
  37
  38 // windows / visual c++
  39 #ifdef __PLATFORM_WIN32__
  40
  41
  42 //-----------------------------------------------------------------------------
  43 // name: round()
  44 // desc: ...
  45 //-----------------------------------------------------------------------------
  46 double round( double a )
  47 {
  48     if( a >= 0 ) return (double)(long)( a + .5 );
  49     else return (double)(long)( a - .5 );
  50 }
  51
  52
  53 //-----------------------------------------------------------------------------
  54 // name: trunc()
  55 // desc: ...
  56 //-----------------------------------------------------------------------------
  57 double trunc( double a )
  58 {
  59     return (double)(long)a;
  60 }
  61
  62
  63 //-----------------------------------------------------------------------------
  64 // name: remainder()
  65 // desc: ...
  66 //-----------------------------------------------------------------------------
  67 double remainder( long a, long b )
  68 {
  69     long div = a/b;
  70     return a - b*div;
  71 }
  72
  73
  74 #endif
  75
  76
  77
  78 // the following 6 functions are
  79 // lifted from  PD source
  80 // specifically x_acoustics.c
  81 // http://puredata.info/downloads
  82 #define LOGTWO 0.69314718055994528623
  83 #define LOGTEN 2.302585092994
  84
  85
  86 //-----------------------------------------------------------------------------
  87 // name: mtof()
  88 // desc: midi to freq
  89 //-----------------------------------------------------------------------------
  90 double mtof( double f )
  91 {
  92     if( f <= -1500 ) return (0);
  93     else if( f > 1499 ) return (mtof(1499));
  94     // else return (8.17579891564 * exp(.0577622650 * f));
  95     // TODO: optimize
  96     else return ( pow(2,(f-69)/12.0) * 440.0 );
  97 }
  98
  99
 100 //-----------------------------------------------------------------------------
 101 // name: ftom()
 102 // desc: freq to midi
 103 //-----------------------------------------------------------------------------
 104 double ftom( double f )
 105 {
 106     // return (f > 0 ? 17.3123405046 * log(.12231220585 * f) : -1500);
 107     // TODO: optimize
 108     return (f > 0 ? (log(f/440.0) / LOGTWO) * 12.0 + 69 : -1500);
 109 }
 110
 111
 112 //-----------------------------------------------------------------------------
 113 // name: powtodb()
 114 // desc: ...
 115 //-----------------------------------------------------------------------------
 116 double powtodb( double f )
 117 {
 118     if( f <= 0 ) return (0);
 119     else
 120     {
 121         double val = 100 + 10./LOGTEN * log(f);
 122         return (val < 0 ? 0 : val);
 123     }
 124 }
 125
 126
 127 //-----------------------------------------------------------------------------
 128 // name: rmstodb()
 129 // desc: ...
 130 //-----------------------------------------------------------------------------
 131 double rmstodb( double f )
 132 {
 133     if( f <= 0 ) return (0);
 134     else
 135     {
 136         double val = 100 + 20./LOGTEN * log(f);
 137         return (val < 0 ? 0 : val);
 138     }
 139 }
 140
 141
 142 //-----------------------------------------------------------------------------
 143 // name: dbtopow()
 144 // desc: ...
 145 //-----------------------------------------------------------------------------
 146 double dbtopow( double f )
 147 {
 148     if( f <= 0 )
 149         return (0);
 150     else
 151     {
 152         if( f > 870 ) f = 870;
 153         return (exp((LOGTEN * 0.1) * (f-100.)));
 154     }
 155 }
 156
 157
 158 //-----------------------------------------------------------------------------
 159 // name: dbtorms()
 160 // desc: ...
 161 //-----------------------------------------------------------------------------
 162 double dbtorms( double f )
 163 {
 164     if( f <= 0 )
 165         return (0);
 166     else
 167     {
 168         if( f > 485 ) f = 485;
 169         return (exp((LOGTEN * 0.05) * (f-100.)));
 170     }
 171 }
 172
 173
 174
 175
 176 //-----------------------------------------------------------------------------
 177 // name: nextpow2()
 178 // desc: ...
 179 //-----------------------------------------------------------------------------
 180 unsigned long nextpow2( unsigned long n )
 181 {
 182     unsigned long nn = n;
 183     for( ; n &= n-1; nn = n );
 184     return nn * 2;
 185 }
 186
 187
 188
 189
 190 //-----------------------------------------------------------------------------
 191 // name: ensurepow2()
 192 // desc: ...
 193 //-----------------------------------------------------------------------------
 194 unsigned long ensurepow2( unsigned long n )
 195 {
 196     return nextpow2( n-1 );
 197 }