- static int first = true;
- static double oldtime = 0.0, curtime = 0.0;
- double newtime;
- // LordHavoc: note to people modifying this code, DWORD is specifically defined as an unsigned 32bit number, therefore the 65536.0 * 65536.0 is fine.
- if (sys_usetimegettime.integer)
- {
- static int firsttimegettime = true;
- // timeGetTime
- // platform:
- // Windows 95/98/ME/NT/2000/XP
- // features:
- // reasonable accuracy (millisecond)
- // issues:
- // wraps around every 47 days or so (but this is non-fatal to us, odd times are rejected, only causes a one frame stutter)
-
- // make sure the timer is high precision, otherwise different versions of windows have varying accuracy
- if (firsttimegettime)
- {
- timeBeginPeriod (1);
- firsttimegettime = false;
- }
-
- newtime = (double) timeGetTime () / 1000.0;
- }
- else
- {
- // QueryPerformanceCounter
- // platform:
- // Windows 95/98/ME/NT/2000/XP
- // features:
- // very accurate (CPU cycles)
- // known issues:
- // does not necessarily match realtime too well (tends to get faster and faster in win98)
- // wraps around occasionally on some platforms (depends on CPU speed and probably other unknown factors)
- double timescale;
- LARGE_INTEGER PerformanceFreq;
- LARGE_INTEGER PerformanceCount;
-
- if (!QueryPerformanceFrequency (&PerformanceFreq))
- Sys_Error ("No hardware timer available");
- QueryPerformanceCounter (&PerformanceCount);
-
- #ifdef __BORLANDC__
- timescale = 1.0 / ((double) PerformanceFreq.u.LowPart + (double) PerformanceFreq.u.HighPart * 65536.0 * 65536.0);
- newtime = ((double) PerformanceCount.u.LowPart + (double) PerformanceCount.u.HighPart * 65536.0 * 65536.0) * timescale;
- #else
- timescale = 1.0 / ((double) PerformanceFreq.LowPart + (double) PerformanceFreq.HighPart * 65536.0 * 65536.0);
- newtime = ((double) PerformanceCount.LowPart + (double) PerformanceCount.HighPart * 65536.0 * 65536.0) * timescale;
- #endif
- }
-
- if (first)
- {
- first = false;
- oldtime = newtime;
- }
-
- if (newtime < oldtime)
- {
- // warn if it's significant
- if (newtime - oldtime < -0.01)
- Con_Printf("Sys_DoubleTime: time stepped backwards (went from %f to %f, difference %f)\n", oldtime, newtime, newtime - oldtime);
- }
- else
- curtime += newtime - oldtime;
- oldtime = newtime;