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ulClock.cxx

/*
     PLIB - A Suite of Portable Game Libraries
     Copyright (C) 1998,2002  Steve 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
     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
 
     For further information visit http://plib.sourceforge.net

     $Id: ulClock.cxx 1735 2002-12-01 18:21:48Z sjbaker $
*/


#include <stdio.h>
#include <stdlib.h>
#include "ul.h"

#ifdef UL_CYGWIN
  typedef long long _int64;
  #define LARGEINTEGER _int64
#endif

#ifndef UL_WIN32
#  include <sys/time.h>
#endif

#include <time.h>

#ifdef UL_WIN32

double ulClock::res ;
int ulClock::perf_timer = -1;

void ulClock::initPerformanceTimer ()
{
  if ( perf_timer == -1 )
  {
    /* Use Performance Timer if it's available, mmtimer if not.  */

    __int64 frequency ;

    perf_timer = QueryPerformanceFrequency ( (LARGE_INTEGER *) & frequency ) ;

    if ( perf_timer )
    {
      res = 1.0 / (double) frequency ;
      perf_timer = 1 ;
    }
  }
}
#endif

double ulClock::getRawTime () const
{
#ifdef UL_WIN32

  /* Use Performance Timer if it's available, mmtimer if not.  */

  if ( perf_timer )
  {
    __int64 t ;
 
    QueryPerformanceCounter ( (LARGE_INTEGER *) &t ) ;
 
    return res * (double) t ;
  }
 
  return (double) timeGetTime() * 0.001 ;

#else
  timeval tv ;

  gettimeofday ( & tv, NULL ) ;

  return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0 ;
#endif
}


void ulClock::update ()
{
  now = getRawTime() - start ;

  delta = now - last_time ;

  /*
    KLUDGE: If the frame rate drops below ~5Hz, then
            control will be very difficult.  It's
            actually easier to give up and slow
            down the action. max_delta defaults to
            200ms for that reason.

    KLUDGE: If update is called very rapidly, then
            delta can be zero which causes some
            programs to div0. So we'll clamp to
            a millionth of a second.
  */

  if ( delta >  max_delta ) delta = max_delta ;
  if ( delta <= 0.0 ) delta = 0.0000001 ;

  last_time = now ;
}




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