VC++ 高精度计时器

头文件声明（CTimer.h）：

#pragma once

#define	WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <mmsystem.h>

class CTimer
{
public:
	CTimer();
	~CTimer();

	void ResetTimer();						// 重设计时器，重新开始计时
	unsigned __int64 GetTimerDifference();	// 计算时差，返回毫秒差
	unsigned __int64 GetTimerDifference(unsigned __int64 t0, unsigned __int64 t1);	// 计算时差，返回毫秒差

private:
	unsigned __int64 StartTimer();	// 启动计时器
	unsigned __int64 GetTimer();	// 获取当前时钟

protected:

private:
	unsigned __int64 m_tmStart;
	BOOL	m_bInitialize;
	BOOL	m_bHigh;
	signed __int64	m_hpFrequency;
};

           

源文件实现（CTimer.cpp）:

#include "stdafx.h"
#include "CTimer.h"

CTimer::CTimer()
{
	if (!m_bInitialize) {
		if (::timeBeginPeriod(1) == TIMERR_NOERROR)
			m_bInitialize = TRUE;
	}

	m_hpFrequency = 10000000;
	if (::QueryPerformanceFrequency((LARGE_INTEGER*)&m_hpFrequency)) {
		m_bHigh = TRUE;
	}

	StartTimer();
}

CTimer::~CTimer()
{
	if (m_bInitialize) {
		::timeEndPeriod(1);
		m_bInitialize = FALSE;
	}
}

// 重设计时器，重新开始计时
void CTimer::ResetTimer()
{
	StartTimer();
}

// 计算时差，返回毫秒差
unsigned __int64 CTimer::GetTimerDifference()
{
	unsigned __int64 m_tmStop = GetTimer();
	return GetTimerDifference(m_tmStart, m_tmStop);
}

// 计算时差，返回毫秒差
unsigned __int64 CTimer::GetTimerDifference(unsigned __int64 t0, unsigned __int64 t1)
{
	if (m_bHigh) {
		return	trunc(abs((FLOAT)(1000.0*(double)(t1 - t0) / (double)m_hpFrequency)));
	}

	return	trunc(abs((FLOAT)(t1 - t0)*1000.0f));
}

// 启动计时器
unsigned __int64 CTimer::StartTimer()
{
	m_tmStart = GetTimer();
	return m_tmStart;
}

// 获取当前时钟
unsigned __int64 CTimer::GetTimer()
{
	if (m_bHigh) {
		signed __int64	freq;
		::QueryPerformanceCounter((LARGE_INTEGER*)&freq);

		return	freq;
	}

	return	(signed __int64)::timeGetTime();
}