nsresult
TimeStamp::Startup()
{
// Decide which implementation to use for the high-performance timer.
InitializeCriticalSectionAndSpinCount(&sTimeStampLock, kLockSpinCount);
LARGE_INTEGER freq;
BOOL QPCAvailable = ::QueryPerformanceFrequency(&freq);
if (!QPCAvailable) {
// No Performance Counter. Fall back to use GetTickCount.
sFrequencyPerSec = 1;
sFallBackToGTC = true;
InitResolution();
LOG(("TimeStamp: using GetTickCount"));
return NS_OK;
}
sFrequencyPerSec = freq.QuadPart;
ULONGLONG qpc = PerformanceCounter();
sLastCalibrated = TickCount64(::GetTickCount());
sSkew = qpc - ms2mt(sLastCalibrated);
InitThresholds();
InitResolution();
LOG(("TimeStamp: initial skew is %1.2fms", mt2ms_d(sSkew)));
return NS_OK;
}
MFBT_API void
TimeStamp::Startup()
{
if (gInitialized) {
return;
}
gInitialized = true;
// Decide which implementation to use for the high-performance timer.
HMODULE kernelDLL = GetModuleHandleW(L"kernel32.dll");
sGetTickCount64 = reinterpret_cast<GetTickCount64_t>(
GetProcAddress(kernelDLL, "GetTickCount64"));
if (!sGetTickCount64) {
// If the platform does not support the GetTickCount64 (Windows XP doesn't),
// then use our fallback implementation based on GetTickCount.
sGetTickCount64 = MozGetTickCount64;
}
InitializeCriticalSectionAndSpinCount(&sTimeStampLock, kLockSpinCount);
sHasStableTSC = HasStableTSC();
LOG(("TimeStamp: HasStableTSC=%d", sHasStableTSC));
LARGE_INTEGER freq;
sUseQPC = ::QueryPerformanceFrequency(&freq);
if (!sUseQPC) {
// No Performance Counter. Fall back to use GetTickCount.
InitResolution();
LOG(("TimeStamp: using GetTickCount"));
return;
}
sFrequencyPerSec = freq.QuadPart;
LOG(("TimeStamp: QPC frequency=%llu", sFrequencyPerSec));
InitThresholds();
InitResolution();
return;
}
