Version 3.2

src/BiQuad.cpp

@@ -0,0 +1,112 @@
+/*******************************************/
+/*
+   BiQuad (2-pole, 2-zero) Filter Class,
+   by Perry R. Cook, 1995-96.
+   Modified by Julius Smith, 2000:
+     setA1,setA2,setB1,setB2
+
+   See books on filters to understand
+   more about how this works.  Nothing
+   out of the ordinary in this version.
+*/
+/*******************************************/
+
+#include "BiQuad.h"
+
+BiQuad :: BiQuad() : Filter()
+{
+  inputs = (MY_FLOAT *) malloc(2 * sizeof(MY_FLOAT));
+  zeroCoeffs[0] = (MY_FLOAT) 0.0;
+  zeroCoeffs[1] = (MY_FLOAT) 0.0;
+  poleCoeffs[0] = (MY_FLOAT) 0.0;
+  poleCoeffs[1] = (MY_FLOAT) 0.0;
+  gain = (MY_FLOAT) 1.0;
+  this->clear();
+}
+
+BiQuad :: ~BiQuad()
+{
+  free(inputs);
+}
+
+void BiQuad :: clear()
+{
+  inputs[0] = (MY_FLOAT) 0.0;
+  inputs[1] = (MY_FLOAT) 0.0;
+  lastOutput = (MY_FLOAT) 0.0;
+}
+
+void BiQuad :: setA1(MY_FLOAT a1)
+{
+  poleCoeffs[0] = -a1;
+}  
+
+void BiQuad :: setA2(MY_FLOAT a2)
+{
+  poleCoeffs[1] = -a2;
+}  
+
+void BiQuad :: setB1(MY_FLOAT b1)
+{
+  zeroCoeffs[0] = b1;
+}  
+
+void BiQuad :: setB2(MY_FLOAT b2)
+{
+  zeroCoeffs[1] = b2;
+}  
+
+void BiQuad :: setPoleCoeffs(MY_FLOAT *coeffs)
+{
+  poleCoeffs[0] = coeffs[0];
+  poleCoeffs[1] = coeffs[1];
+}
+
+void BiQuad :: setZeroCoeffs(MY_FLOAT *coeffs)
+{
+  zeroCoeffs[0] = coeffs[0];
+  zeroCoeffs[1] = coeffs[1];
+}
+
+void BiQuad :: setFreqAndReson(MY_FLOAT freq, MY_FLOAT reson)
+{
+  poleCoeffs[1] = - (reson * reson);
+  poleCoeffs[0] = (MY_FLOAT) 2.0 * reson * (MY_FLOAT)  cos(TWO_PI * freq / SRATE);
+}
+
+void BiQuad :: setEqualGainZeroes()
+{
+  zeroCoeffs[1] = (MY_FLOAT) -1.0;
+  zeroCoeffs[0] = (MY_FLOAT) 0.0;
+}
+
+void BiQuad :: setGain(MY_FLOAT aValue)
+{
+  gain = aValue;
+}
+
+/* Perform Filter Operation */
+MY_FLOAT BiQuad :: tick(MY_FLOAT sample)
+{
+  /*
+     Biquad is two pole, two zero filter. Look it up
+     in your favorite DSP text.  This version implements
+     only 2 state variables.  It takes 5 multiplies, 
+     4 adds, and 3 moves.
+  */
+  MY_FLOAT temp;
+
+  temp = sample * gain;
+  temp += inputs[0] * poleCoeffs[0];
+  temp += inputs[1] * poleCoeffs[1];
+    
+  lastOutput = temp;
+  lastOutput += (inputs[0] * zeroCoeffs[0]);
+  lastOutput += (inputs[1] * zeroCoeffs[1]);
+  inputs[1] = inputs[0];
+  inputs[0] = temp;
+
+  return lastOutput;
+
+}
+