added IIR stuff

worked on StepDetection

math/DelayBuffer.h

@@ -0,0 +1,33 @@
+#ifndef DELAYBUFFER_H
+#define DELAYBUFFER_H
+
+#include <vector>
+
+/** efficient delay using a ring-buffer */
+template <typename Scalar> class DelayBuffer {
+
+	size_t head = 0;
+	std::vector<Scalar> vec;
+
+public:
+
+	/** ctor */
+	DelayBuffer(int size) {
+		vec.resize(size);
+	}
+
+	/** set all elements to the same value */
+	void setAll(const Scalar s) {
+		std::fill(vec.begin(), vec.end(), s);
+	}
+
+	/** append a new element, get the delayed output */
+	Scalar add(Scalar s) {
+		vec[head] = s;
+		head = (head + 1) % vec.size();	// next to-be-overwritten element = oldest element = tail
+		return vec[head];
+	}
+
+};
+
+#endif // DELAYBUFFER_H