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Implement MH's version of Sys_DoubleTime for windows.

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From http://forums.inside3d.com/viewtopic.php?p=36239
This commit is contained in:
Bill Currie 2013-01-05 17:42:27 +09:00
parent e0e69ac71a
commit 49d07ce452
1 changed files with 46 additions and 0 deletions
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46
libs/util/sys.c
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@ -289,6 +289,7 @@ Sys_DoubleTime (void)
{
static qboolean first = true;
#ifdef _WIN32
# if 0
static DWORD starttime;
DWORD now;
@ -307,6 +308,51 @@ Sys_DoubleTime (void)
return 0.0;
return (now - starttime) / 1000.0;
# else
// MH's solution combining timeGetTime for stability and
// QueryPerformanceCounter for precision.
static __int64 qpcfreq = 0;
static __int64 currqpccount = 0;
static __int64 lastqpccount = 0;
static double qpcfudge = 0;
DWORD currtime = 0;
static DWORD lasttime = 0;
static DWORD starttime = 0;
if (first) {
timeBeginPeriod (1);
starttime = lasttime = timeGetTime ();
QueryPerformanceFrequency ((LARGE_INTEGER *) &qpcfreq);
QueryPerformanceCounter ((LARGE_INTEGER *) &lastqpccount);
first = false;
return 0;
}
// get the current time from both counters
currtime = timeGetTime ();
QueryPerformanceCounter ((LARGE_INTEGER *) &currqpccount);
if (currtime != lasttime) {
// requery the frequency in case it changes (which it can on multicore
// machines)
QueryPerformanceFrequency ((LARGE_INTEGER *) &qpcfreq);
// store back times and calc a fudge factor as timeGetTime can
// overshoot on a sub-millisecond scale
qpcfudge = (((double) (currqpccount - lastqpccount)
/ (double) qpcfreq))
- ((double) (currtime - lasttime) * 0.001);
lastqpccount = currqpccount;
lasttime = currtime;
} else {
qpcfudge = 0;
}
// the final time is the base from timeGetTime plus an addition from QPC
return ((double) (currtime - starttime) * 0.001)
+ ((double) (currqpccount - lastqpccount) / (double) qpcfreq)
+ qpcfudge;
# endif
#else
struct timeval tp;
struct timezone tzp;