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

   1 #if !defined(__PeakEq_h)
   2 #define __PeakEq_h
   3
   4 #include <stdio.h>
   5 #include "Math.h"
   6
   7 class PeakEq
   8 {
   9 public:
  10         int filterDecibel;
  11
  12         float sampleRate;
  13
  14         float a0, a1, a2;
  15         float b0, b1, b2;
  16
  17         float x0, x1, x2;
  18         float     y1, y2;
  19
  20         float outSample;
  21
  22         float a, w0, q, s, alpha;
  23         float cosValue, sqrtValue;
  24         float vsa;   // Very small amount (Denormal Fix)
  25
  26         float dBgain, freq;
  27
  28
  29         PeakEq(float sampleRate, int filterDecibel)
  30         {
  31                 this->sampleRate = sampleRate;
  32                 this->filterDecibel = filterDecibel;
  33
  34                 a0 = a1 = a2 = 0.0f;
  35                 b0 = b1 = b2 = 0.0f;
  36
  37                 x0 = x1 = x2 = 0.0f;
  38                 y1 = y2 = 0.0f;
  39
  40                 q = dBgain = freq = 0.0f;
  41
  42                 s = 2.0f;
  43                 vsa= (1.0f/4294967295.0f);   // Very small amount (Denormal Fix)
  44         }
  45
  46         // gain [0..1], q[0..1], freq[0..44100]
  47         inline void tick(float *inSample, float freq, float q, float gain)
  48         {
  49                 gain = filterDecibel - (1.0f - gain) * filterDecibel * 2.0f;
  50                 calcCoefficients(freq, q, gain);
  51
  52                 outSample = b0*x0 + b1*x1 + b2*x2 - a1*y1 - a2*y2;
  53                 outSample = b0*x0 + b1*x1 + b2*x2 - a1*y1 - a2*y2;
  54                 updateHistory(*inSample, outSample);
  55                 *inSample = outSample;
  56         }
  57
  58         inline void calcCoefficients(float freq, float q, float dBgain)
  59         {
  60                 if (this->q != q || this->dBgain != dBgain || this->freq != freq)
  61                 {
  62                         this->dBgain = dBgain;
  63                         this->q = q;
  64                         this->freq = freq;
  65                         w0 = 2.0f * 3.141592653589793f * freq / sampleRate;
  66                         a = sqrtf(pow(10, dBgain/20.0f));
  67                         alpha = sinf(w0)*sinhf( logf(2.0f)/2.0f * q * w0/sinf(w0));
  68                         // q = 1.0f / sqrt((a + 1.0f/a)*(1.0f/s - 1.0f) + 2.0f);
  69
  70                         cosValue = cosf(w0);
  71                         sqrtValue = sqrtf(a);
  72                 }
  73
  74         b0 =  1.0f + alpha * a;
  75         b1 = -2.0f * cosValue;
  76         b2 =  1.0f - alpha * a;
  77         a0 =  1.0f + alpha / a;
  78         a1 = -2.0f * cosValue;
  79         a2 =  1.0f - alpha / a;
  80
  81                 a0 = 1.0f/a0;
  82
  83                 b0 *= a0;
  84                 b1 *= a0;
  85                 b2 *= a0;
  86                 a1 *= a0;
  87                 a2 *= a0;
  88         }
  89
  90         inline void updateHistory(float inSample, float outSample)
  91         {
  92                 x0 = saturate(x1, -0.05f);
  93                 x1 = saturate(x2, 0.04f);
  94                 x2 = inSample;
  95
  96                 y2 = y1;
  97                 y1 = outSample;
  98         }
  99
 100         inline float saturate(float x, float variation)
 101         {
 102                 return x - 0.002f * (x + variation) * x * x;
 103         }
 104 };
 105
 106 #endif