/// Copyright (c) 2010 Ruben Penalva. 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. The name of the author may not be used to endorse or promote products derived
///    from this software without specific prior written permission.
///
/// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.

#ifndef _TIMER_H_
#define _TIMER_H_

#include <boost\shared_array.hpp>
#include <windows.h>

namespace TestFrameWork
{

/// @brief Timer class provides services to measure the time.
/// It's based on high performance counter. Create a timer
/// object to start the counter. Get the elapsed time using ElapsedTime
/// @todo SetThreadAffinityMask() in order to avoid timing issues
/// in many core architectures. Attach the thread to one core.
class Timer
{
public:
	/// Constructor. It resets counter for first time.
	Timer(int samplesCount);

	/// Destructor
	~Timer(void);

	/// @brief It gives the time elapsed since construction or
	/// between ElapsedTime calls.
	/// It resets counter.
	/// @return elapsed time between timer resets in us.
	float ElapsedTime(void);

	float MeanElapsedTime(void) const;

private:
	int m_samplesCount;

	boost::shared_array<float> m_elapsedTimeSamples;

	int m_samplesInsertionIndex;

	/// Time factor to translate units from ticks to us.
	float m_timeFactor;
	
	/// Time between timer resets.
	LONGLONG m_lastTime;
	
	/// @brief It configures the timer: checking if there's
	/// a high performance counter and getting the time
	/// factor.
	/// @return time factor.
	float ConfigureTimeCounter(void) const;
};

}

#endif