Diff: TwoPhaseGenerator.hpp

Revision:

0:5b53b74d1fb7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TwoPhaseGenerator.hpp	Thu Oct 23 00:41:02 2014 +0000
@@ -0,0 +1,42 @@
+//--------------------------------------------------------------
+// Two phase sin generator class
+// 2014/10/22, Copyright (c) 2014 MIKAMI, Naoki
+//--------------------------------------------------------------
+
+#ifndef TWO_PHASE_GENERATOR_HPP
+#define TWO_PHASE_GENERATOR_HPP
+
+#include "mbed.h"
+
+namespace Mikami
+{
+    class TwoPhaseGenerator
+    {
+    public:
+        // Constructor
+        TwoPhaseGenerator(float f0, float fs)
+            : a1_(cosf(6.283185f*f0/fs)),
+              b1_(sinf(6.283185f*f0/fs)),
+              xn1_(1.0f), yn1_(0.0f) {}
+
+        // -1.0f <= x1, x2 <= 1.0f
+        void Generate(float& xn, float& yn)
+        {
+            yn = a1_*yn1_ + b1_*xn1_;     // sin
+            xn = -b1_*yn1_ + a1_*xn1_;    // cos
+
+            float c1 = 1.5f - 0.5f*(xn*xn + yn*yn);
+
+            xn1_ = c1*xn;
+            yn1_ = c1*yn;
+        }
+
+    private:
+        const float a1_, b1_;
+        float xn1_, yn1_;
+
+        TwoPhaseGenerator(const TwoPhaseGenerator&);
+        TwoPhaseGenerator& operator=(const TwoPhaseGenerator&);
+    };
+}
+#endif  // TWO_PHASE_GENERATOR_HPP