Split the filter code into a class.

[c64tapwav] / filter.h

diff --git a/filter.h b/filter.h
new file mode 100644 (file)
index 0000000..a67f98a
--- /dev/null
+++ b/filter.h
@@ -0,0 +1,26 @@
+#ifndef _FILTER_H
+#define _FILTER_H 1
+
+class Filter {
+public:
+       Filter(float a0, float a1, float a2, float b0, float b1, float b2)
+               : a1(a1 / a0), a2(a2 / a0), b0(b0 / a0), b1(b1 / a0), b2(b2 / a0), d0(0.0f), d1(0.0f) {}
+
+       inline float update(float in)
+       {
+               float out = b0*in + d0;
+               d0 = b1 * in - a1 * out + d1;
+               d1 = b2 * in - a2 * out;
+               return out;
+       }
+
+       void reset();
+
+       static Filter lpf(float cutoff_radians);
+
+private:
+       float a1, a2, b0, b1, b2;
+       float d0, d1;
+};
+
+#endif  // !defined(_FILTER_H)