Diff: Biquad.hpp

Revision:

0:c17cb8371b55

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Biquad.hpp	Sat Jul 25 07:56:36 2015 +0000
@@ -0,0 +1,48 @@
+//--------------------------------------------------------------
+// Biquad filter for IIR filter of cascade structure
+// 2014/10/21, Copyright (c) 2014 MIKAMI, Naoki
+//--------------------------------------------------------------
+
+#ifndef IIR_BIQUAD_HPP
+#define IIR_BIQUAD_HPP
+
+#include "mbed.h"
+
+// 2nd order IIR filter
+namespace Mikami
+{
+    class Biquad
+    {
+    public:
+        struct Coefs { float a1, a2, b1, b2; };
+
+        Biquad() {}     // Default constructore
+
+        Biquad(const Coefs ck)
+              : a1_(ck.a1), a2_(ck.a2), b1_(ck.b1), b2_(ck.b2)
+        { Clear(); }       
+
+        float Execute(float xn)
+        {
+            float un = xn + a1_*un1_ + a2_*un2_;
+            float yn = un + b1_*un1_ + b2_*un2_;
+    
+            un2_ = un1_;
+            un1_ = un;
+
+            return yn;
+        }
+
+        void Clear() { un1_ = un2_ = 0; }
+
+    private:
+        float a1_, a2_, b1_, b2_;
+        float un1_, un2_;
+
+        Biquad(const Biquad&);
+};
+}
+#endif  // IIR_BIQUAD_HPP
+
+
+