root/juggler/tags/1.0.5/Performance/vjTimeStampSGI.h

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 *
 * VR Juggler is (C) Copyright 1998, 1999, 2000 by Iowa State University
 *
 * Original Authors:
 *   Allen Bierbaum, Christopher Just,
 *   Patrick Hartling, Kevin Meinert,
 *   Carolina Cruz-Neira, Albert Baker
 *
 * 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
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 * Library General Public License for more details.
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 * File:          $RCSfile$
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#ifndef _VJ_TIMESTAMP_SGI_
#define _VJ_TIMESTAMP_SGI_

#include <vjConfig.h>
#include <sys/types.h>

//-----------------------------------------
//:Time recorder for SGI systems
//
//     This version of vjTimeStamp uses the SGI system cycle
//     counter to collect timing information.  The precision
//     of this hardware timer varies on different machines.
//     For example, on an SGI Onyx it's 21 nanoseconds, while
//     it's 80 ns on an Octane.
//
//     vjTimeStampPosix should never be instantiated directly.
//     Instead, use vjTimeStamp, which will be typedefed to
//     the correct implementation.
//
// @author  Christopher Just
//-----------------------------------------

class vjTimeStampSGI {

public:

    //: Called at application initialization to open the counter
    //! PRE: true
    //! POST: cycle counter is initialized
    //! RETURNS: true - succes
    //! RETURNS: false - failure to open counter. Timestamp set()
    //+          will set to the value 0.
    static void initialize();



    //: Constructor
    //! PRE: initialize() has been called.
    //! POST: self is created and set to the current counter val.
    vjTimeStampSGI();



    //: stamps the timestamp with the current time
    //! PRE: true
    //! POST: self's value is the current time
    inline void set() {
        val = (cyclecntrsize == 64)
            ? *(unsigned long long*) iotimer_addr
            : *(unsigned int*) iotimer_addr;
        val = (val >= initval)
            ? val - initval
            : val + (maxval - initval);
    }



    //: assignment operator
    vjTimeStampSGI& operator= (const vjTimeStampSGI& t2) {
        val = t2.val;
        return *this;
    }



    //: returns number of microseconds between self and t2
    //! PRE: t2 is stamped with an earlier time than self
    //! 
    float operator - (const vjTimeStampSGI& t2) const;



    float usecs();

    friend std::ostream& operator << (std::ostream& out, vjTimeStampSGI& ts);

    //: returns resolution of timer in microseconds
    float getResolution();

private:

    static __psunsigned_t phys_addr, raddr;
    static volatile void* iotimer_addr;
    static volatile unsigned long long longcount;
    static int fd, poffmask;
    static float resolution; // in usecs.
    static int cyclecntrsize;  // either 32 or 64 bits. depends on hardware
    static long long initval;
    static long long maxval;

    long long val; // (in clockticks; resolution*clocktics = time in usecs

};

#endif