tal-reverb-2-juce/src/Engine/NoiseGenerator.h

   1 /*
   2         ==============================================================================
   3         This file is part of Tal-Reverb by Patrick Kunz.
   4
   5         Copyright(c) 2005-2009 Patrick Kunz, TAL
   6         Togu Audio Line, Inc.
   7         http://kunz.corrupt.ch
   8
   9         This file may be licensed under the terms of of the
  10         GNU General Public License Version 2 (the ``GPL'').
  11
  12         Software distributed under the License is distributed
  13         on an ``AS IS'' basis, WITHOUT WARRANTY OF ANY KIND, either
  14         express or implied. See the GPL for the specific language
  15         governing rights and limitations.
  16
  17         You should have received a copy of the GPL along with this
  18         program. If not, go to http://www.gnu.org/licenses/gpl.html
  19         or write to the Free Software Foundation, Inc.,
  20         51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21         ==============================================================================
  22  */
  23
  24
  25 #if !defined(__NoiseGenerator_h)
  26 #define __NoiseGenerator_h
  27
  28 #include <cstdlib>
  29
  30 class NoiseGenerator
  31 {
  32 public:
  33     int randSeed;
  34         float actualValue;
  35         float deltaValue;
  36
  37         float actualValueFiltered;
  38         float filterFactor;
  39         float filterFactorInversePlusOne;
  40
  41         float invertedRandomMax;
  42
  43         NoiseGenerator(int sampleRate)
  44         {
  45                 // No sample rate conversion here
  46                 filterFactor = 5000.0f;
  47                 filterFactorInversePlusOne = 1.0f / (filterFactor + 1.0f);
  48
  49                 actualValue = 0.0f;
  50                 actualValueFiltered = 0.0f;
  51                 deltaValue = 0.0f;
  52
  53                 getNextRandomPeriod(1.0f);
  54
  55         randSeed = 1;
  56         }
  57
  58         // returns a random value [0..1]
  59         inline float tickNoise()
  60         {
  61                 // return ((float)(((randSeed = randSeed * 214013L + 2531011L) >> 16) & 0x7fff)/RAND_MAX);
  62
  63         randSeed *= 16807;
  64         return (float)(randSeed &  0x7FFFFFFF) * 4.6566129e-010f;
  65         //return (float)randSeed * 4.6566129e-010f;
  66         }
  67
  68         // returns a lp filtered random value [0..1]
  69         inline float tickFilteredNoise()
  70         {
  71                 if (actualValue >= 1.0f)
  72                 {
  73                         getNextRandomPeriod(-1.0f);
  74                 }
  75                 if (actualValue <= 0.0f)
  76                 {
  77                         getNextRandomPeriod(1.0f);
  78                 }
  79                 actualValue += deltaValue;
  80
  81                 // Exponential averager
  82                 actualValueFiltered =  (actualValueFiltered * filterFactor + actualValue) * filterFactorInversePlusOne;
  83                 return actualValueFiltered;
  84         }
  85
  86         inline void getNextRandomPeriod(float sign)
  87         {
  88                 int randomPeriod = (int)(tickNoise() * 22768.0f) + 22188;
  89                 deltaValue = 1.0f / (float)randomPeriod;
  90                 deltaValue *= sign;
  91         }
  92
  93         inline float tickFilteredNoiseFast()
  94         {
  95         actualValueFiltered = (actualValueFiltered * 1000.0f + tickNoise()) / 1001.0f;
  96                 return actualValueFiltered;
  97         }
  98 };
  99 #endif