added data structures

added audio support
added rfid support
added spi support

data/LinearBuffer.h

@@ -0,0 +1,59 @@
+#ifndef LINEARBUFFER_H
+#define LINEARBUFFER_H
+
+template <typename Scalar, int _size> class LinearBuffer {
+
+private:
+
+	Scalar _data[_size];
+
+	uint16_t head = 0;
+
+public:
+
+	void add(const Scalar value) {
+		if (head >= _size) {return;}
+		_data[head] = value;
+		++head;
+	}
+
+	/** get the number of used entries */
+	uint16_t getNumUsed() const {
+		return head;
+	}
+
+	/** get the number of used bytes */
+	uint32_t getBytesUsed() const {
+		return getNumUsed() * sizeof(Scalar);
+	}
+
+	uint16_t size() const {
+		return _size;
+	}
+
+	/** set the buffer to empty */
+	void reset() {
+		head = 0;
+	}
+
+	const Scalar* data() const {
+		return _data;
+	}
+
+	/** constant array access */
+	const Scalar& operator [] (const size_t idx) const {
+		return _data[idx];
+	}
+
+	/** true if the buffer is currently empty */
+	bool isEmpty() const {
+		return head == 0;
+	}
+
+	bool isFull() const {
+		return head >= size;
+	}
+
+};
+
+#endif // LINEARBUFFER_H