/*

 *    微秒级计时器，用来统计程序运行时间

 *   http://blog.csdn.net/hoya5121/article/details/3778487#comments

 *   //整理 [10/16/2013 Duan Yihao]

 */

 #pragma once

 #include "stdafx.h"

 //////////////////////////////////////////////////////////////////////////

 class timer

 {

 public:

     timer();

     ~timer();

     void start(void);

     void end(void);   

     DWORD getTime(void) const;

 private:

     LARGE_INTEGER m_i64CPUFreq;

     LARGE_INTEGER m_i64Begin;

     LARGE_INTEGER m_i64End;

     void reset(void);

 };

 //////////////////////////////////////////////////////////////////////////

 timer::timer()

 {

     QueryPerformanceFrequency(&m_i64CPUFreq);

 }

 timer::~timer()

 {

 }

 void timer::start(void)

 {

     reset();

     QueryPerformanceCounter(&m_i64Begin);

 }

 void timer::end(void)

 {

     QueryPerformanceCounter(&m_i64End);

 }

 DWORD timer::getTime(void) const

 {

     DWORD dwTotalMicrosecond = ;

     LARGE_INTEGER i64TickCount;

     i64TickCount.QuadPart = m_i64End.QuadPart - m_i64Begin.QuadPart;

     dwTotalMicrosecond = (DWORD) (i64TickCount.QuadPart *  / m_i64CPUFreq.QuadPart);

     return dwTotalMicrosecond;

 }

 void timer::reset(void)

 {

     m_i64Begin = m_i64End;

 }

 /*

 //////////////////////////////////////////////////////////////////////////

 //MFC下使用举例：

 void CtestMFCView::OnTest()

 {

     // TODO: 在此添加命令处理程序代码

     //测试例子

     //计时开始

     timer t;

     t.start();

     //运算过程

         for(int i = 0; i < 10; i++)

         {

             int n = i;

             for(int i = 0; i < 10000; i++)

             {

                 int n = i;

             }

         }

     //计时结束

     t.end();

     //输出运行时间

     CString s;

     s.Format(_T("%u ms"), t.getTime());

     AfxMessageBox(s);

 }

 */