Version 3.2

src/FIR.cpp

@@ -0,0 +1,67 @@
+/********************************************/  
+/*
+   General Finite-Impulse-Response (FIR)
+   Digital Filter Class
+   by Julius Smith, 1997
+*/
+/********************************************/  
+
+#include "FIR.h"
+
+FIR :: FIR(int theLength) : Object()
+{
+  length = theLength;
+  coeffs = (MY_FLOAT *) malloc(length * sizeof(MY_FLOAT));
+  pastInputs = (MY_FLOAT *) calloc(2*length, sizeof(MY_FLOAT));
+  piOffset = length;
+}
+
+FIR :: ~FIR()
+{
+  free(pastInputs);
+  free(coeffs);
+}
+
+void FIR :: clear()
+{
+  int i;
+  for (i=0; i < 2*length; i++) {
+    pastInputs[i] = 0;
+  }
+  piOffset = length;
+}
+
+void FIR :: setCoeffs(MY_FLOAT *theCoeffs)
+{
+  int i;
+  for (i=0; i < length; i++) {
+    coeffs[i] = theCoeffs[i];
+  }
+}
+
+MY_FLOAT FIR :: tick(MY_FLOAT input) {
+  int i;
+  lastOutput = input*coeffs[0];
+  for (i=1; i<length; i++)
+    lastOutput += coeffs[i] * pastInputs[piOffset-i]; // sample 0 unused
+  pastInputs[piOffset++] = input;
+  if (piOffset >= 2*length) { // sample 2*length-1 unused
+    piOffset = length;
+    for (i=0; i<length; i++)
+      pastInputs[i] = pastInputs[length+i];
+  }
+  return lastOutput;
+}
+
+
+MY_FLOAT FIR :: getDelay(MY_FLOAT freq)
+{
+  return delay;
+}
+
+int FIR :: getLength(void)
+{
+  return length;
+}
+
+