p5timer.hpp

来自「开放源码的编译器open watcom 1.6.0版的源代码」· HPP 代码 · 共 122 行

/****************************************************************************
*
*                            Open Watcom Project
*
*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
*  ========================================================================
*
*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
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****************************************************************************/


#ifndef _P5TIMER_HPP
#define _P5TIMER_HPP

/****************************************************
 *
 * P5Timer
 *
 * Usage:
 *
 * #include "p5timer.hpp"
 *
 * void foo() {
 *     P5Timer  timer;                  // implicitly does a Start()
 *     ...
 *     timer.Restart();
 *     ... expensive stuff ...
 *     cout << timer.Time() << endl;    // time in clock cycles
 * }
 *
 * Improvements:
 *   - correct for rdtsc overhead
 *   - determine the process clock speed
 *
 ****************************************************/

#include <limits.h>

#ifndef __WATCOM_INT64__
#  error 'You must be using a compiler that supports __int64'
#endif

unsigned __int64 P5Timer_ReadTSC();
#pragma aux     P5Timer_ReadTSC =   \
        ".586"                      \
        "rdtsc"                     \
        value [eax edx];



typedef unsigned __int64 p5time_t;

class P5Timer {
    public:
        P5Timer() {
            _start = P5Timer_ReadTSC();
        }

        P5Timer( const P5Timer & o )
            : _start( o._start )
        {}

        P5Timer & operator=( const P5Timer & o ) {
            _start = o._start;
            return *this;
        }

        //
        // Restart
        //
        //  Restart the timer from 0

        void Restart() {
            _start = P5Timer_ReadTSC();
        }

        //
        // Time
        //
        //  Return the time in since the most recent Restart.

        p5time_t Time() {
            return( P5Timer_ReadTSC() - _start );
        }

        //
        // Now
        //
        //  Return the current processor tick count

        static inline p5time_t Now() {
            return( P5Timer_ReadTSC() );
        }


    private:
        p5time_t        _start;
};

#endif // _P5TIMER_HPP