Clock.cpp

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static const char rcsid[] = "$Id$";

/* 
 * See the COPYING file for the terms of usage and distribution.
 */

#include <cstdlib>
#include <sys/time.h>                   // for struct timeval
#ifdef __osf__
#    include <machine/builtins.h>       // for __RPCC()
#elif __linux__ && __i386__
#    define rdtscl(low) \
     __asm__ __volatile__("rdtsc" : "=a" (low) : : "edx")
#endif
#include <iostream>

#include "Clock.hh"

namespace 
{
    const usec_t UsecPerSec = INT64_CONSTANT(1000000);
}

bool Clock::UsingCPU  = std::getenv("CLOCK_USE_CPU") ? true : false;

// -----------------------------------------------------------------------------
usec_t Clock::time(void)
{
    if (UsingCPU) {
        static bool warn = true;
                
        if (warn) {
            std::cout << "Using CPU clock." << std::endl;
            warn = false;
        }

#ifdef __osf__
        return (usec_t) __RPCC();
#elif __linux__ && __i386__
        {
            unsigned long tsc;
                        
            rdtscl(tsc);
            return (usec_t) tsc;
        }
#else
        {
            std::cerr << "CPU clock not implemented for this architecture" << std::endl;
            UsingCPU = false;
            return Clock::time();
        }
#endif  
    } else {
        struct timeval tv;
        
        gettimeofday(&tv, NULL);        
        return (usec_t) (tv.tv_sec * UsecPerSec + tv.tv_usec);
    }
}

// -----------------------------------------------------------------------------
Clock::Clock(void)
    : _start(0),
      _elapsed(0),
      _active(false) 
{
    start();
}

// -----------------------------------------------------------------------------
Clock::~Clock(void)
{
    ;
}

// -----------------------------------------------------------------------------
usec_t Clock::elapsed(void) const
{
    if (!active())
        return _elapsed;

    return time() - _start;
}


// -----------------------------------------------------------------------------
usec_t Clock::start(void)
{
    _active = true;

    return _start = time();
}

// -----------------------------------------------------------------------------
usec_t Clock::stop(void)
{
    _elapsed = elapsed();
    _active  = false;

    return _elapsed;
}