Timer.h

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/*  Timer.h - high frequency timer wrapper
    Copyright (C) 2001-2005 Mark Weaver
    Written by Mark Weaver <mark@npsl.co.uk>

    Part of the Open-Win32 library.
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the
    Free Software Foundation, Inc., 59 Temple Place - Suite 330,
    Boston, MA  02111-1307, USA.
*/

#ifndef OW32_Timer_h
#define OW32_Timer_h

#include <OW32/OW32Libs.h>

namespace OW32
{

class OW32_LIB_EXPORT CTimer
{
private:
    LARGE_INTEGER   m_liStart;
    LARGE_INTEGER   m_liStop;

    class OW32_LIB_EXPORT CTimerFrequency
    {
    private:
        LARGE_INTEGER m_liFreq;

    public:
        CTimerFrequency()
        {
            // Avoid divz on failure
            if (!QueryPerformanceFrequency(&m_liFreq))
                m_liFreq.QuadPart = 1;
        }

        __int64 GetFrequency() { return m_liFreq.QuadPart; }
    };

    static CTimerFrequency m_sTimerFreq;

public:
    BOOL Start()
    {
        return QueryPerformanceCounter(&m_liStart);
    }

    BOOL Stop()
    {
        return QueryPerformanceCounter(&m_liStop);
    }

    double Elapsed() const
    {
        return (double)(m_liStop.QuadPart-m_liStart.QuadPart)/m_sTimerFreq.GetFrequency();
    }
};

} // namespace OW32

#endif // OW32_Timer_h

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