Quantifying The Accuracy Of Sleep

// StopWatch.h: interface for the CStopWatch class.
//
//////////////////////////////////////////////////////////////////////

#if !defined(AFX_STOPWATCH_H__7E8AC6E0_4649_11D7_A1EE_00C0F03D7695__INCLUDED_)
#define AFX_STOPWATCH_H__7E8AC6E0_4649_11D7_A1EE_00C0F03D7695__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

class CStopWatch  
{
public:
	CStopWatch();
	virtual ~CStopWatch();
	void Start(void);
	void Stop(void);
	DWORD GetLapTime() const;	// in whole microseconds (less than 214 secs) -- stopwatch keeps running
	DWORD GetInterval() const;	// in whole microseconds (less than 214 secs) -- must call Stop() first, or returns zero
	LONGLONG GetLapTimeLongLong() const;	// in whole microseconds -- stopwatch keeps running
	LONGLONG GetIntervalLongLong() const;	// in whole microseconds -- must call Stop() first, or returns zero

protected:
	LARGE_INTEGER m_liStart;
	LARGE_INTEGER m_liStop;
	LONGLONG m_llFrequency;
};


inline CStopWatch::CStopWatch(void)
{
	LARGE_INTEGER liFrequency;

	::QueryPerformanceFrequency(&liFrequency);
	m_llFrequency = liFrequency.QuadPart;

	m_liStart.QuadPart = 0;
	m_liStop.QuadPart = 0;
}


inline CStopWatch::~CStopWatch()
{

}


inline void CStopWatch::Start(void)
{
	::QueryPerformanceCounter(&m_liStart);
	m_liStop = m_liStart;
}


inline void CStopWatch::Stop(void)
{
	::QueryPerformanceCounter(&m_liStop);
}


inline DWORD CStopWatch::GetInterval(void) const
{
	return (DWORD)( (m_liStop.QuadPart - m_liStart.QuadPart) * 1000000 / m_llFrequency);
}


inline DWORD CStopWatch::GetLapTime(void) const
{
	LARGE_INTEGER liCurrent;
	::QueryPerformanceCounter(&liCurrent);
	return (DWORD)( (liCurrent.QuadPart - m_liStart.QuadPart) * 1000000 / m_llFrequency);
}


inline LONGLONG CStopWatch::GetIntervalLongLong(void) const
{
	return (m_liStop.QuadPart - m_liStart.QuadPart) * 1000000 / m_llFrequency;
}


inline LONGLONG CStopWatch::GetLapTimeLongLong(void) const
{
	LARGE_INTEGER liCurrent;
	::QueryPerformanceCounter(&liCurrent);
	return (liCurrent.QuadPart - m_liStart.QuadPart) * 1000000 / m_llFrequency;
}

#endif // !defined(AFX_STOPWATCH_H__7E8AC6E0_4649_11D7_A1EE_00C0F03D7695__INCLUDED_)