mirror of
https://github.com/ApfelTeeSaft/reactos.git
synced 2026-08-29 19:26:33 +00:00
Samuel Serapion
- Implement ExSetTimerResolution, tested with a VirtualBox driver. - Rewrite comments in TimeRefresh lock/unlock functions. svn path=/trunk/; revision=44918
This commit is contained in:
Aleksey Bragin
+168
-18
@@ -25,35 +25,197 @@ ULONG ExpAltTimeZoneBias;
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ULONG ExpTimeZoneId;
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ULONG ExpTickCountMultiplier;
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ERESOURCE ExpTimeRefreshLock;
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ULONG ExpKernelResolutionCount = 0;
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ULONG ExpTimerResolutionCount = 0;
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/* FUNCTIONS ****************************************************************/
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/*++
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* @name ExAcquireTimeRefreshLock
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*
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* The ExReleaseTimeRefreshLock routine acquires the system-wide lock used
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* to synchronize clock interrupt frequency changes.
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*
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* @param Wait
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* If TRUE, the system will block the caller thread waiting for the lock
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* to become available. If FALSE, the routine will fail if the lock has
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* already been acquired.
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*
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* @return Boolean value indicating success or failure of the lock acquisition.
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*
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* @remarks None.
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*
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*--*/
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BOOLEAN
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NTAPI
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ExAcquireTimeRefreshLock(BOOLEAN Wait)
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ExAcquireTimeRefreshLock(
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IN BOOLEAN Wait
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)
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{
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/* Simply acquire the Resource */
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/* Block APCs */
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KeEnterCriticalRegion();
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/* Attempt lock acquisition */
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if (!(ExAcquireResourceExclusiveLite(&ExpTimeRefreshLock, Wait)))
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{
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/* We failed! */
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/* Lock was not acquired, enable APCs and fail */
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KeLeaveCriticalRegion();
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return FALSE;
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}
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/* Success */
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/* Lock has been acquired */
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return TRUE;
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}
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/*++
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* @name ExReleaseTimeRefreshLock
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*
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* The ExReleaseTimeRefreshLock routine releases the system-wide lock used
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* to synchronize clock interrupt frequency changes.
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*
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* @param None.
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*
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* @return None.
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*
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* @remarks None.
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*
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*--*/
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VOID
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NTAPI
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ExReleaseTimeRefreshLock(VOID)
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ExReleaseTimeRefreshLock(
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VOID
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)
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{
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/* Simply release the Resource */
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/* Release the lock and re-enable APCs */
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ExReleaseResourceLite(&ExpTimeRefreshLock);
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KeLeaveCriticalRegion();
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}
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/*++
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* @name ExSetTimerResolution
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* @exported
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*
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* The KiInsertQueueApc routine modifies the frequency at which the system
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* clock interrupts.
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*
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* @param DesiredTime
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* Specifies the amount of time that should elapse between each timer
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* interrupt, in 100-nanosecond units.
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*
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* This parameter is ignored if SetResolution is FALSE.
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*
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* @param SetResolution
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* If TRUE, the call is a request to set the clock interrupt frequency to
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* the value specified by DesiredTime. If FALSE, the call is a request to
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* restore the clock interrupt frequency to the system's default value.
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*
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* @return New timer resolution, in 100-nanosecond ticks.
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*
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* @remarks (1) The clock frequency is changed only if the DesiredTime value is
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* less than the current setting.
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*
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* (2) The routine just returns the current setting if the DesiredTime
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* value is greater than what is currently set.
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*
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* (3) If the DesiredTime value is less than the system clock can
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* support, the routine uses the smallest resolution the system can
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* support, and returns that value.
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*
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* (4) If multiple drivers have attempted to change the clock interrupt
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* frequency, the system will only restore the default frequency
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* once ALL drivers have called the routine with SetResolution set
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* to FALSE.
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*
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* NB. This routine synchronizes with IRP_MJ_POWER requests through the
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* TimeRefreshLock.
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*
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*--*/
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ULONG
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NTAPI
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ExSetTimerResolution(IN ULONG DesiredTime,
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IN BOOLEAN SetResolution)
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{
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ULONG CurrentIncrement;
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/* Wait for clock interrupt frequency and power requests to synchronize */
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ExAcquireTimeRefreshLock(TRUE);
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/* Obey remark 2*/
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CurrentIncrement = KeTimeIncrement;
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/* Check the type of operation this is */
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if (SetResolution)
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{
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/*
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* If this is the first kernel change, bump the timer resolution change
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* count, then bump the kernel change count as well.
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*
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* These two variables are tracked differently since user-mode processes
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* can also change the timer resolution through the NtSetTimerResolution
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* system call. A per-process flag in the EPROCESS then stores the per-
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* process change state.
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*
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*/
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if (!ExpKernelResolutionCount++) ExpTimerResolutionCount++;
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/* Obey remark 3 */
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if (DesiredTime < KeMinimumIncrement) DesiredTime = KeMinimumIncrement;
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/* Obey remark 1 */
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if (DesiredTime < KeTimeIncrement)
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{
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/* Force this thread on CPU zero, since we don't want it to drift */
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KeSetSystemAffinityThread(1);
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/* Now call the platform driver (HAL) to make the change */
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CurrentIncrement = HalSetTimeIncrement(DesiredTime);
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/* Put the thread back to its original affinity */
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KeRevertToUserAffinityThread();
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/* Finally, keep track of the new value in the kernel */
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KeTimeIncrement = CurrentIncrement;
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}
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}
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else
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{
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/* First, make sure that a driver has actually changed the resolution */
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if (ExpKernelResolutionCount)
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{
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/* Obey remark 4 */
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if (--ExpKernelResolutionCount)
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{
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/*
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* All kernel drivers have requested the original frequency to
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* be restored, but there might still be user processes with an
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* ongoing clock interrupt frequency change, so make sure that
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* this isn't the case.
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*/
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if (--ExpTimerResolutionCount)
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{
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/* Force this thread on one CPU so that it doesn't drift */
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KeSetSystemAffinityThread(1);
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/* Call the HAL to restore the frequency to its default */
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CurrentIncrement = HalSetTimeIncrement(KeMaximumIncrement);
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/* Put the thread back to its original affinity */
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KeRevertToUserAffinityThread();
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/* Finally, keep track of the new value in the kernel */
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KeTimeIncrement = CurrentIncrement;
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}
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}
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}
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}
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/* Release the clock interrupt frequency lock since changes are done */
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ExReleaseTimeRefreshLock();
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/* And return the current value -- which could reflect the new frequency */
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return CurrentIncrement;
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}
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VOID
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NTAPI
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ExUpdateSystemTimeFromCmos(IN BOOLEAN UpdateInterruptTime,
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@@ -305,18 +467,6 @@ ExLocalTimeToSystemTime(PLARGE_INTEGER LocalTime,
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SystemTime->QuadPart = LocalTime->QuadPart + ExpTimeZoneBias.QuadPart;
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}
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/*
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* @unimplemented
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*/
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ULONG
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NTAPI
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ExSetTimerResolution(IN ULONG DesiredTime,
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IN BOOLEAN SetResolution)
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{
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UNIMPLEMENTED;
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return 0;
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}
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/*
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* @implemented
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*/
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