Timing Question

/***************************************************************Zehne Ziba Corpotarion******************************************************************************HOW TO USE TIMER**********************Docment Written by Ehsan Kamrani***********Files:..\Common\Timer.h..\Common\Timer.cppUsage:1)Include the header file:   #include "Common\Timer.h"2)Declare a timer object:   	TIMER *timer;3)In your initialization function, initialize timer:    timer = new Timer;	if( !timer->Init() )	{        //Report an error message		MessageBox( NULL, "Cannot initialize the timer", "ERROR", MB_OK | MB_ICONINFORMATION );		return 0; 	}4)In your rendering function:    float elapsedTime;	elapsedTime = timer->GetElapsedSeconds( 1 ) ;5)In your release code, write the following code:   delete timer;   timer = NULL;/**************************************************************************************************************************//**************************************************************************** HiResTimer.h  Wrapper for the high-resolution timer. Can't be used if the hi-res timer doesn't exist.   Author   :   Dave Astle Date     :   2/1/2001 Written for OpenGL Game Programming*****************************************************************************/#ifndef __TIMER_H_INCLUDED__#define __TIMER_H_INCLUDED__#include <windows.h>class TIMER{public:  TIMER();  ~TIMER();  bool Init();  float GetElapsedSeconds(unsigned long elapsedFrames = 1);  float GetFPS(unsigned long elapsedFrames = 1);  float LockFPS(unsigned char targetFPS);private:  LARGE_INTEGER   m_startTime;  LARGE_INTEGER   m_ticksPerSecond;};#endif // __TIMER_H_INCLUDED_

#include "Timer.h"/***************************************************************************** Init() If the hi-res timer is present, the tick rate is stored and the function returns true. Otherwise, the function returns false, and the timer should not be used.*****************************************************************************/TIMER::TIMER(){}TIMER::~TIMER(){}bool TIMER::Init(){	if (!QueryPerformanceFrequency(&m_ticksPerSecond))	{		// system doesn't support hi-res timer		return false;	}	else	{		QueryPerformanceCounter(&m_startTime);		return true;	}} // end Init()float TIMER::GetElapsedSeconds(unsigned long elapsedFrames){  static LARGE_INTEGER s_lastTime = m_startTime;  LARGE_INTEGER currentTime;  QueryPerformanceCounter(&currentTime);  float seconds =  ((float)currentTime.QuadPart - (float)s_lastTime.QuadPart) / (float)m_ticksPerSecond.QuadPart;  // reset the timer  s_lastTime = currentTime;  return seconds;} // end GetElapsedSeconds()/*************************************************************************** GetFPS() Returns the average frames per second over elapsedFrames, which defaults to one. If this is not called every frame, the client should track the number of frames itself, and reset the value after this is called.***************************************************************************/float TIMER::GetFPS(unsigned long elapsedFrames){  static LARGE_INTEGER s_lastTime = m_startTime;  LARGE_INTEGER currentTime;  QueryPerformanceCounter(&currentTime);  float fps = (float)elapsedFrames * (float)m_ticksPerSecond.QuadPart / ((float)currentTime.QuadPart - (float)s_lastTime.QuadPart);  // reset the timer  s_lastTime = currentTime;  return fps;} // end GetFPS/*************************************************************************** LockFPS() Used to lock the frame rate to a set amount. This will block until enough time has passed to ensure that the fps won't go over the requested amount. Note that this can only keep the fps from going above the specified level; it can still drop below it. It is assumed that if used, this function will be called every frame. The value returned is the instantaneous fps, which will be <= targetFPS.***************************************************************************/float TIMER::LockFPS(unsigned char targetFPS){  if (targetFPS == 0)     targetFPS = 1;  static LARGE_INTEGER s_lastTime = m_startTime;  LARGE_INTEGER currentTime;  float   fps;  // delay to maintain a constant frame rate  do {    QueryPerformanceCounter(&currentTime);    fps = (float)m_ticksPerSecond.QuadPart/((float)(currentTime.QuadPart - s_lastTime.QuadPart));  } while (fps > (float)targetFPS);  // reset the timer  s_lastTime = m_startTime;  return fps;} // end LockFPS()