Version 0.99

BiQuad.cpp

@@ -0,0 +1,80 @@
+/*******************************************/
+/*  BiQuad (2-pole, 2-zero) Filter Class,  */
+/*  by Perry R. Cook, 1995-96              */ 
+/*  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 * MY_FLOAT_SIZE);
+    zeroCoeffs[0] = 0.0;
+    zeroCoeffs[1] = 0.0;
+    poleCoeffs[0] = 0.0;
+    poleCoeffs[1] = 0.0;
+    gain = 1.0;
+    this->clear();
+}
+
+BiQuad :: ~BiQuad()
+{
+    free(inputs);
+}
+
+void BiQuad :: clear()
+{
+    inputs[0] = 0.0;
+    inputs[1] = 0.0;
+    lastOutput = 0.0;
+}
+
+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] = 2.0 * reson * cos(TWO_PI * freq / SRATE);
+}
+
+void BiQuad :: setEqualGainZeroes()
+{
+    zeroCoeffs[1] = -1.0;
+    zeroCoeffs[0] = 0.0;
+}
+
+void BiQuad :: setGain(MY_FLOAT aValue)
+{
+    gain = aValue;
+}
+
+MY_FLOAT BiQuad :: tick(MY_FLOAT sample)    /*   Perform Filter Operation            */
+{                                           /*  Biquad is two pole, two zero filter  */
+    MY_FLOAT temp;                          /*  Look it up in your favorite DSP text */
+
+    temp = sample * gain;                       /* Here's the math for the  */
+    temp += inputs[0] * poleCoeffs[0];         /* version which implements */
+    temp += inputs[1] * poleCoeffs[1];         /* only 2 state variables.  */
+    
+    lastOutput = temp;                          /* This form takes          */
+    lastOutput += (inputs[0] * zeroCoeffs[0]);  /* 5 multiplies and         */
+    lastOutput += (inputs[1] * zeroCoeffs[1]);  /* 4 adds                   */
+    inputs[1] = inputs[0];                      /* and 3 moves              */
+    inputs[0] = temp;                           /* like the 2 state-var form*/
+
+    return lastOutput;
+
+}
+