TickDelta
TickDelta::FromMilliseconds(
int nTimeDelta) // Tick delta, in 1/1000^1 sec
{
AssertMsg(nTimeDelta != _I32_MAX, "Use Infinite() to create an infinite TickDelta");
return FromMicroseconds(((int64) nTimeDelta) * ((int64) 1000));
}
TimeStamp VSyncWin::GetAdjustedVsyncTimeStamp(LARGE_INTEGER& aFrequency,
QPC_TIME& aQpcVblankTime)
{
char buf[1024];
TimeStamp vsync = Now();
LARGE_INTEGER qpcNow;
QueryPerformanceCounter(&qpcNow);
const int microseconds = 1000000;
int64_t adjust = qpcNow.QuadPart - aQpcVblankTime;
int64_t usAdjust = (adjust * microseconds) / aFrequency.QuadPart;
sprintf_s(buf, "\n((((( usadjust %lld and", usAdjust);
OutputDebugStringA(buf);
sprintf_s(buf, "\n(((((Vsync %llu", aQpcVblankTime);
OutputDebugStringA(buf);
vsync -= FromMicroseconds((double)usAdjust);
//if (IsWin10OrLater())
{
// On Windows 10 and on, DWMGetCompositionTimingInfo, mostly
// reports the upcoming vsync time, which is in the future.
// It can also sometimes report a vblank time in the past.
// Since large parts of Gecko assume TimeStamps can't be in future,
// use the previous vsync.
// Windows 10 and Intel HD vsync timestamps are messy and
// all over the place once in a while. Most of the time,
// it reports the upcoming vsync. Sometimes, that upcoming
// vsync is in the past. Sometimes that upcoming vsync is before
// the previously seen vsync. Sometimes, the previous vsync
// is still in the future. In these error cases,
// we try to normalize to Now().
TimeStamp upcomingVsync = vsync;
if (upcomingVsync < mPrevVsync) {
// Windows can report a vsync that's before
// the previous one. So update it to sometime in the future.
upcomingVsync = Now() + FromMilliseconds(1);
}
vsync = mPrevVsync;
sprintf_s(buf, "\n)))) vsync %llu---", vsync);
OutputDebugStringA(buf);
mPrevVsync = upcomingVsync;
}
// On Windows 7 and 8, DwmFlush wakes up AFTER qpcVBlankTime
// from DWMGetCompositionTimingInfo. We can return the adjusted vsync.
// Once in a while, the reported vsync timestamp can be in the future.
// Normalize the reported timestamp to now.
if (vsync >= Now()) {
vsync = Now();
}
return vsync;
}
