vos/corelibs/vos/timer.cc

Go to the documentation of this file.

/*
    This file is part of the Virtual Object System of
    the Interreality project (http://interreality.org).

    Copyright (C) 2001-2003 Peter Amstutz

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser 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

    Peter Amstutz <tetron@interreality.org>
*/

#if defined(_WIN32) && defined(_MSC_VER)
# include <vos/corelibs/vosconfig-vc7.h>
#else
# include <vos/corelibs/vosconfig.h>
#endif

#ifdef HAVE_GETTIMEOFDAY
# ifdef HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  warning Note: According to autoconf, you have gettimeofday(), but not <sys/time.h>. I wonder where gettimeofday() is defined.
# endif
#else
# ifdef WIN32
#  include <windows.h>
# else
#  error I do not know about time on your system
# endif
#endif

#include <time.h>

#if defined(_WIN32) && defined(_MSC_VER)
# ifdef VOS_EXPORTS
#  define VOS_API __declspec(dllexport)
# else
#  define VOS_API __declspec(dllimport)
# endif
#else
# define VOS_API
#endif

namespace VOS
{

#ifdef HAVE_GETTIMEOFDAY
VOS_API double getRealTime()
{
    double now;

    struct timeval tv;
    gettimeofday(&tv, 0);
    now = (double)tv.tv_sec + ((double)tv.tv_usec / 1000000.0);
    
    return now;
}
#else
# ifdef WIN32
// The following code to use the Windows high-resolution timer
// was borrowed from the Crystal Space project :-)
// The "LARGE_INTEGER" type is at least 64 bits
VOS_API double getRealTime()
{
#if defined(__CYGWIN32__)
#       define __int64 long long
#endif  

    static __int64 Freq       = 0;
    static __int64 FirstCount = 0;
    static double startTime   = 0;

  //Freq was set to -1, if the current Hardware does not support
  //high resolution timers. We will use GetTickCount instead then.
  if (Freq <= 0)
  {
      FILETIME ft;
      LARGE_INTEGER _100nanosecs;

      GetSystemTimeAsFileTime(&ft);

      _100nanosecs.LowPart = ft.dwLowDateTime;
      _100nanosecs.HighPart = ft.dwHighDateTime;

    // the ridiculous large figure is the number of 100 ns
    // intervals from 1601-01-01 to 1970-01-01 
    // (to bring it in line with the unix epoch)
#if defined(__CYGWIN32__)
    _100nanosecs.QuadPart -= 116444736000000000ULL;
#else
    _100nanosecs.QuadPart -= 116444736000000000;
#endif
      startTime = (_100nanosecs.QuadPart / 10000000.0) + (((_100nanosecs.QuadPart / 10) % 1000000) / 1000000.0);
      if(Freq < 0) return startTime;
  }

  //Freq is 0, the first time this function is being called.
  if (Freq == 0)
  {
      //try to determine the frequency of the high resulution timer
      if (!QueryPerformanceFrequency((LARGE_INTEGER*)&Freq))
      {
          //There is no such timer....
          Freq=-1;
          return getRealTime();
      }
      // Start counting from first time this function is called.
      QueryPerformanceCounter((LARGE_INTEGER*)&FirstCount);
  }

  //retrieve current count
  __int64 Count = 0;
  QueryPerformanceCounter((LARGE_INTEGER*)&Count);

  return startTime + ((double)(Count-FirstCount))/((double)Freq);
}
#else
#error bad configuration or do not know how to do time on this system
#endif // WIN32
#endif // HAVE_GETTIMEOFDAY_H

VOS_API double getTimer()
{
    static double lasttime = 0.0;
    double now = getRealTime();
    double delta = now - lasttime;

    if(delta < 0.0) delta = 0.000001;
    lasttime += delta;

    return lasttime;
}

}

---