add px4 parameter api class (with ros implementation)

src/include/px4.h

@@ -45,4 +45,5 @@
 #include "../platforms/px4_middleware.h"
 #include "../platforms/px4_nodehandle.h"
 #include "../platforms/px4_subscriber.h"
+#include "../platforms/px4_parameter.h"
 #endif

src/platforms/px4_parameter.h

@@ -0,0 +1,123 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2015 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 px4_parameter.h
+ *
+ * PX4 Parameter API
+ */
+#pragma once
+#if defined(__PX4_ROS)
+/* includes when building for ros */
+#include "ros/ros.h"
+#include <string>
+#else
+/* includes when building for NuttX */
+#endif
+
+namespace px4
+{
+
+/**
+ * Parameter base class
+ */
+template <typename T>
+class __EXPORT ParameterBase
+{
+public:
+	ParameterBase(const char *name, T value) :
+		_name(name),
+		_value(value)
+	{}
+
+	virtual ~ParameterBase() {};
+
+	/**
+	 * Update the parameter value and return the value
+	 */
+	virtual T update() = 0;
+
+	/**
+	 * Get the current parameter value
+	 */
+	virtual T get() = 0;
+
+protected:
+	const char *_name; /** The parameter name */
+	T _value; /**< The current value of the parameter */
+
+};
+
+#if defined(__PX4_ROS)
+template <typename T>
+class Parameter :
+	public ParameterBase<T>
+{
+public:
+	Parameter(const char *name, T value) :
+		ParameterBase<T>(name, value)
+	{
+		if (!ros::param::has(name)) {
+			ros::param::set(name, value);
+		}
+	}
+
+	~Parameter() {};
+
+	/**
+	 * Update the parameter value
+	 * Nothing to do for ROS
+	 */
+	T update()
+	{
+		ros::param::get(this->_name, this->_value);
+		return get();
+	}
+
+	/**
+	 * Get the current parameter value
+	 */
+	T get()
+	{
+		return this->_value;
+	}
+
+};
+
+
+#else
+#endif
+
+typedef Parameter<double> ParameterFloat;
+typedef Parameter<int> ParameterInt;
+}