diff include/IirFilter.h @ 233:18d03901f866 mergingClockSync

Turned gShouldStop into int

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/IirFilter.h	Sun Apr 10 03:20:52 2016 +0200
@@ -0,0 +1,86 @@
+/*
+ * IirFilter.h
+ *
+ *  Created on: 17 Sep 2015
+ *      Author: giulio
+ */
+
+#ifndef IIRFILTER_H_
+#define IIRFILTER_H_
+
+#define IIR_FILTER_STAGE_COEFFICIENTS (5)
+#define IIR_FILTER_STAGE_STATES (IIR_FILTER_STAGE_COEFFICIENTS - 1)
+
+class IirFilterStage{ //TODO : to save (some) memory we should only store the coefficients pointers here,
+						//so that IirFilter can share them among multiple stages if needbe)
+private:
+	double coefficients[IIR_FILTER_STAGE_COEFFICIENTS]; // these are b0,b1,b2,a1,a2
+	double states[IIR_FILTER_STAGE_STATES]; // these are xprev, xprevprev, yprev, yprevprev
+public:
+	IirFilterStage();
+	void setCoefficients(double* newCoefficients);
+	void setStates(double* newStates);
+	// this is not meant to be efficient, just of practical use!
+	double process(double in){
+		process(&in, 1);
+		return in;
+	}
+
+	void process(double* inout, int length){
+		// make variables explicit. A smart compiler will optimize these out, right?
+		double b0=coefficients[0];
+		double b1=coefficients[1];
+		double b2=coefficients[2];
+		double a1=coefficients[3];
+		double a2=coefficients[4];
+		double x1 = states[0];
+		double x2=  states[1];
+		double y1 = states[2];
+		double y2 = states[3];
+		for(int n = 0; n < length; n++){
+			double x0 = inout[n];
+			double y = x0 * b0 + x1 * b1 + x2 * b2 +
+					- y1 * a1 - y2 * a2;
+			inout[n] = y;
+			x2 = x1;
+			x1 = x0;
+			y2 = y1;
+			y1 = y;
+		}
+		states[0] = x1;
+		states[1] = x2;
+		states[2] = y1;
+		states[3] = y2;
+	}
+};
+
+class IirFilter{
+private:
+	struct IirFilterStage** stages;
+	int numberOfStages;
+	void dealloc();
+public:
+	IirFilter();
+	IirFilter(int newNumberOfStages);
+	IirFilter(int newNumberOfStages, double *newCoefficients);
+	void setCoefficients(double* newCoefficients);
+	void setStates(double* newStates);
+	void setNumberOfStages(int newNumberOfStages);
+//	double process(double in);
+//	inline void process(double* inout, int length);
+//	inline void process(double* in, double* out, int length);
+	double process(double in){
+		process(&in, 1);
+		return in;
+	};
+	void process(double* inout, int length){
+		for(int n = 0; n < numberOfStages && n < 8/* TODO: this "8" compensates for a memory corruption somewhere on the BBB*/; n++){
+			stages[n]->process(inout, length);
+		}
+	}
+};
+
+
+//void IirFilter::process(double* in, double* out, int length);
+
+#endif /* IIRFILTER_H_ */