added base class for data storage

EKF/RingBuffer.h

@@ -0,0 +1,110 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file RingBuffer.h
+ * @author Roman Bapst <bapstroman@gmail.com>
+ * Template RingBuffer.
+ */
+
+template <typename data_type>
+class RingBuffer
+{
+public:
+	RingBuffer() {_buffer = NULL;};
+	~RingBuffer() {delete _buffer;}
+
+	bool allocate(unsigned size)
+	{
+		if (size == 0) {
+			return false;
+		}
+
+		_buffer = new data_type[size];
+
+		if (_buffer == NULL) {
+			return false;
+		}
+
+		_size = size;
+		return true;
+	}
+
+	inline void push(data_type sample)
+	{
+		_buffer[_head] = sample;
+		_head = (_head + 1) % _size;
+
+		// move tail if we overwrite it
+		if (_head == _tail && _size > 1) {
+			_tail = (_tail + 1) % _size;
+		}
+	}
+
+	inline data_type get_oldest()
+	{
+		return _buffer[_tail];
+	}
+
+	inline bool pop_first_older_than(uint64_t timestamp, data_type &sample)
+	{
+		// start looking from oldest data of buffer
+		for (unsigned i = 0; i < _size; i++) {
+			unsigned index = (_tail + i) % _size;
+
+			if (timestamp >= _buffer[index].time_us) {
+				sample = _buffer[_tail + i];
+				// now we can set the tail to the item
+				// which comes after the one we removed
+				_tail = (_tail + i + 1);
+				return true;
+			}
+
+			if (index == _head) {
+				// we have reached the head and haven't found anything
+				return false;
+			}
+		}
+
+		return false;
+	}
+
+	data_type &operator[](unsigned index)
+	{
+		return _buffer[index];
+	}
+
+private:
+	data_type *_buffer;
+	unsigned _head, _tail, _size;
+};