clock.cpp

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// PTF - Psychological Test Framework
// http://ptf.sourceforge.net
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#include <ptf/environment/clock.hpp>
#include <ptf/core/ptfcore.hpp>
#if _POSIX_VERSION < 199309
    #ifndef _POSIX_TIMERS
        #include <sys/time.h>    
    #endif
#endif
#ifdef MAC
    #include <mach/mach_time.h>
    #include <mach/mach.h>
    #include <mach/clock.h>
    // global variables
    static uint64_t relative_time, startup_time;
    static double timebase_ratio;
    static mach_port_t clock_port;
#endif
#include <stdexcept>

#ifdef MAC
void initMachTimer(){
    mach_timebase_info_data_t timebase;
    memset( &timebase, 0, sizeof( timebase ));
    // get base for mach_absolute_time()
    mach_timebase_info(&timebase);
    timebase_ratio = (double)timebase.numer / (double)timebase.denom * (double)1e-9;
    // get mach port for the clock
    host_get_clock_service(mach_host_self(), REALTIME_CLOCK, &clock_port);
    // prepare for GetRelativeTime()
    relative_time = startup_time = (uint64_t)(mach_absolute_time() * timebase_ratio);
}

uint64_t getMachTimer(){
  return (uint64_t)((mach_absolute_time() * timebase_ratio) * 1e6);
}  
#endif

Clock::Clock() {
    timespec tspec1, tspec2;
    PtfCore::getSingleton().getMessageLog() << MESSAGE("Checking clock capabilities.\n");  
    // Initialize darwin's timer in case of OS is Mac OS X 
    #ifdef MAC
        PtfCore::getSingleton().getMessageLog() 
    << MESSAGE("Using Mac OS X high resolution timer. Initializing it now.\n"); 
        initMachTimer();
    #endif
    // check for POSIX.4 clocks and timer support
    #ifdef _POSIX_TIMERS
    PtfCore::getSingleton().getMessageLog() << MESSAGE("POSIX.4 timers and clocks support.\n");
        clock_getres(CLOCK_REALTIME, &tspec1);
    #else
        PtfCore::getSingleton().getMessageLog() 
    << WARNING("POSIX.4 timers and clocks not supported. Using low resolution timing.\n");
    #endif
    calculateClockResolution(tspec2);
    #ifdef _POSIX_TIMERS
    PtfCore::getSingleton().getMessageLog() << MESSAGE("System reported this clock resolution:    ") 
            << tspec1 << "\n";
    #endif
    PtfCore::getSingleton().getMessageLog() << MESSAGE("PTF has calculated this clock resolution: ") 
        << tspec2 << "\n";
}

Clock::~Clock() {
    // nothing to do here
}

void Clock::getClock(timespec& tspec) {
    #ifdef _POSIX_TIMERS
        // use POSIX timer
        clock_gettime(CLOCK_REALTIME, &tspec);
    #else
        #ifdef MAC
            // use MACH timer on MacOs
            uint64_t current_time = getMachTimer() * 1000;
            tspec.tv_nsec = current_time % (uint64_t)1e9;
            tspec.tv_sec = (int)(current_time / 1e9);
        #else
            // use gettimeofday as fallback
            int err;
            struct timeval tv;
            struct timezone tz; 
            err = gettimeofday(&tv, &tz);
            if(0 != err) {
                PtfCore::getSingleton().getMessageLog() 
                    << "ERROR:   Failed to get time from low resolution timer.\n";
                throw std::runtime_error("Failed to get time from low resolution timer.");
            };
            tspec.tv_sec = (long int)tv.tv_sec;
            tspec.tv_nsec = (long int)tv.tv_usec * 1000;
        #endif
    #endif
}

void Clock::calculateClockResolution(timespec& tspec) {
    timespec tspec1, tspec2;
    getClock(tspec1);
    do {
        getClock(tspec2);
    } while ((tspec1.tv_nsec == tspec2.tv_nsec) && ((tspec1.tv_sec == tspec2.tv_sec)));
    if (tspec1.tv_sec == tspec2.tv_sec) {
        tspec.tv_nsec = tspec2.tv_nsec - tspec1.tv_nsec;
        tspec.tv_sec  = 0;
    }
    else {
        tspec.tv_nsec = 1000000000 - tspec1.tv_nsec + tspec2.tv_nsec;
        if (tspec.tv_nsec >= 1000000000) {
            tspec.tv_nsec -= 1000000000;
            tspec.tv_sec = tspec2.tv_sec - tspec1.tv_sec;
        }
        else {
            tspec.tv_sec = tspec2.tv_sec - tspec1.tv_sec - 1;
        }
    }
}

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