RTDECL(int) RTTimerReleaseSystemGranularity(uint32_t u32Granted)
{
if (!g_pfnrtNtExSetTimerResolution)
return VERR_NOT_SUPPORTED;
g_pfnrtNtExSetTimerResolution(0 /* ignored */, FALSE);
NOREF(u32Granted);
return VINF_SUCCESS;
}
RTDECL(int) RTTimerRequestSystemGranularity(uint32_t u32Request, uint32_t *pu32Granted)
{
if (!g_pfnrtNtExSetTimerResolution)
return VERR_NOT_SUPPORTED;
ULONG ulGranted = g_pfnrtNtExSetTimerResolution(u32Request / 100, TRUE);
if (pu32Granted)
*pu32Granted = ulGranted * 100; /* NT -> ns */
return VINF_SUCCESS;
}
RTDECL(uint32_t) RTTimerGetSystemGranularity(void)
{
/*
* Get the default/max timer increment value, return it if ExSetTimerResolution
* isn't available. According to the sysinternals guys NtQueryTimerResolution
* is only available in userland and they find it equally annoying.
*/
ULONG ulTimeInc = KeQueryTimeIncrement();
if (!g_pfnrtNtExSetTimerResolution)
return ulTimeInc * 100; /* The value is in 100ns, the funny NT unit. */
/*
* Use the value returned by ExSetTimerResolution. Since the kernel is keeping
* count of these calls, we have to do two calls that cancel each other out.
*/
g_pfnrtNtExSetTimerResolution(ulTimeInc, TRUE);
ULONG ulResolution = g_pfnrtNtExSetTimerResolution(0 /*ignored*/, FALSE);
return ulResolution * 100; /* NT -> ns */
}
