X-Git-Url: https://git.sesse.net/?p=c64tapwav;a=blobdiff_plain;f=filter.h;fp=filter.h;h=a67f98a7f4a63bcc641a8cda72a9857b454cfc71;hp=0000000000000000000000000000000000000000;hb=cec99d15ad920457eea61bc442b5ba610c13430e;hpb=1d431da4497326b4496cdc6596c52736d98699e7

diff --git a/filter.h b/filter.h
new file mode 100644
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)