timer.h

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// from: http://snipplr.com/view/40650/timer-class-for-both-unixlinuxmac-and-windows-system/

// How to Use ////

//#include <iostream>
//#include "timer.h"
//using namespace std;
 
//int main()
//{
//    Timer timer;
// 
//    // start timer
//    timer.start();
// 
//    // do something
//    ...
// 
//    // stop timer
//    timer.stop();
// 
//    // print the elapsed time in millisec
//    cout << timer.getElapsedTimeInMilliSec() << " ms.\n";
// 
//    return 0;
//}
 
 
// Timer.h
// =======
// High Resolution Timer.
// This timer is able to measure the elapsed time with 1 micro-second accuracy
// in both Windows, Linux and Unix system 
//
//  AUTHOR: Song Ho Ahn (song.ahn@gmail.com)
// CREATED: 2003-01-13
// UPDATED: 2006-01-13
//
// Copyright (c) 2003 Song Ho Ahn
 
#ifndef TIMER_H_DEF
#define TIMER_H_DEF
 
#ifndef __LINUX__   // Windows system specific
#include <windows.h>
#else          // Unix based system specific
#include <sys/time.h>
#endif

#include <stdlib.h>
 
 
class Timer
{
public:
        // default constructor
    Timer()
    {
    #ifdef WIN32
        QueryPerformanceFrequency(&frequency);
        startCount.QuadPart = 0;
        endCount.QuadPart = 0;
    #else
        startCount.tv_sec = startCount.tv_usec = 0;
        endCount.tv_sec = endCount.tv_usec = 0;
    #endif

        stopped = 0;
        startTimeInMicroSec = 0;
        endTimeInMicroSec = 0;
    }

    // default destructor
    ~Timer()
    {}
 
    // start timer.
    // startCount will be set at this point.
    void start()
    {
        stopped = 0; // reset stop flag
    #ifdef WIN32
        QueryPerformanceCounter(&startCount);
    #else
        gettimeofday(&startCount, NULL);
    #endif
    }

    // stop the timer.
    // endCount will be set at this point.
    void stop()
    {
        stopped = 1; // set timer stopped flag

    #ifdef WIN32
        QueryPerformanceCounter(&endCount);
    #else
        gettimeofday(&endCount, NULL);
    #endif
    }

    // same as getElapsedTimeInSec()
    double getElapsedTime()
    {
        return this->getElapsedTimeInSec();
    }

    // divide elapsedTimeInMicroSec by 1000000
    double getElapsedTimeInSec()
    {
        return this->getElapsedTimeInMicroSec() * 0.000001;
    }

    // divide elapsedTimeInMicroSec by 1000
    double getElapsedTimeInMilliSec()
    {
        return this->getElapsedTimeInMicroSec() * 0.001;
    }

    // compute elapsed time in micro-second resolution.
    // other getElapsedTime will call this first, then convert to correspond resolution.
    double getElapsedTimeInMicroSec()
    {
    #ifdef WIN32
        if(!stopped)
            QueryPerformanceCounter(&endCount);

        startTimeInMicroSec = startCount.QuadPart * (1000000.0 / frequency.QuadPart);
        endTimeInMicroSec = endCount.QuadPart * (1000000.0 / frequency.QuadPart);
    #else
        if(!stopped)
            gettimeofday(&endCount, NULL);

        startTimeInMicroSec = (startCount.tv_sec * 1000000.0) + startCount.tv_usec;
        endTimeInMicroSec = (endCount.tv_sec * 1000000.0) + endCount.tv_usec;
    #endif

        return endTimeInMicroSec - startTimeInMicroSec;
    }
 
 
protected:
 
 
private:
    double startTimeInMicroSec;                 // starting time in micro-second
    double endTimeInMicroSec;                   // ending time in micro-second
    int    stopped;                             // stop flag 
#ifdef WIN32
    LARGE_INTEGER frequency;                    // ticks per second
    LARGE_INTEGER startCount;                   //
    LARGE_INTEGER endCount;                     //
#else
    timeval startCount;                         //
    timeval endCount;                           //
#endif
};
 
#endif // TIMER_H_DEF