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310 lines
7.2 KiB
310 lines
7.2 KiB
/*++
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Copyright (c) 1989 Microsoft Corporation
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Module Name:
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timersup.c
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Abstract:
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This module contains the support routines for the timer object. It
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contains functions to insert and remove from the timer queue.
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Author:
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David N. Cutler (davec) 13-Mar-1989
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Environment:
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Kernel mode only.
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Revision History:
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--*/
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#include "ki.h"
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//
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// Define forward referenced function prototypes.
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//
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LOGICAL
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FASTCALL
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KiInsertTimerTable (
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LARGE_INTEGER Interval,
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LARGE_INTEGER CurrentTime,
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IN PKTIMER Timer
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);
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LOGICAL
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FASTCALL
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KiInsertTreeTimer (
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IN PKTIMER Timer,
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IN LARGE_INTEGER Interval
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)
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/*++
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Routine Description:
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This function inserts a timer object in the timer queue.
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N.B. This routine assumes that the dispatcher data lock has been acquired.
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Arguments:
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Timer - Supplies a pointer to a dispatcher object of type timer.
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Interval - Supplies the absolute or relative time at which the time
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is to expire.
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Return Value:
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If the timer is inserted in the timer tree, than a value of TRUE is
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returned. Otherwise, a value of FALSE is returned.
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--*/
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{
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LARGE_INTEGER CurrentTime;
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LARGE_INTEGER SystemTime;
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LARGE_INTEGER TimeDifference;
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//
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// Clear the signal state of timer if the timer period is zero and set
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// the inserted state to TRUE.
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//
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Timer->Header.Inserted = TRUE;
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Timer->Header.Absolute = FALSE;
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if (Timer->Period == 0) {
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Timer->Header.SignalState = FALSE;
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}
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//
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// If the specified interval is not a relative time (i.e., is an absolute
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// time), then convert it to relative time.
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//
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if (Interval.HighPart >= 0) {
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KiQuerySystemTime(&SystemTime);
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TimeDifference.QuadPart = SystemTime.QuadPart - Interval.QuadPart;
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//
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// If the resultant relative time is greater than or equal to zero,
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// then the timer has already expired.
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//
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if (TimeDifference.HighPart >= 0) {
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Timer->Header.SignalState = TRUE;
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Timer->Header.Inserted = FALSE;
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return FALSE;
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}
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Interval = TimeDifference;
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Timer->Header.Absolute = TRUE;
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}
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//
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// Get the current interrupt time, insert the timer in the timer table,
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// and return the inserted state.
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//
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KiQueryInterruptTime(&CurrentTime);
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return KiInsertTimerTable(Interval, CurrentTime, Timer);
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}
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LOGICAL
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FASTCALL
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KiReinsertTreeTimer (
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IN PKTIMER Timer,
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IN ULARGE_INTEGER DueTime
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)
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/*++
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Routine Description:
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This function reinserts a timer object in the timer queue.
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N.B. This routine assumes that the dispatcher data lock has been acquired.
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Arguments:
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Timer - Supplies a pointer to a dispatcher object of type timer.
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DueTime - Supplies the absolute time the timer is to expire.
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Return Value:
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If the timer is inserted in the timer tree, than a value of TRUE is
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returned. Otherwise, a value of FALSE is returned.
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--*/
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{
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LARGE_INTEGER CurrentTime;
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LARGE_INTEGER Interval;
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//
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// Clear the signal state of timer if the timer period is zero and set
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// the inserted state to TRUE.
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//
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Timer->Header.Inserted = TRUE;
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if (Timer->Period == 0) {
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Timer->Header.SignalState = FALSE;
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}
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//
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// Compute the interval between the current time and the due time.
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// If the resultant relative time is greater than or equal to zero,
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// then the timer has already expired.
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//
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KiQueryInterruptTime(&CurrentTime);
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Interval.QuadPart = CurrentTime.QuadPart - DueTime.QuadPart;
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if (Interval.HighPart >= 0) {
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Timer->Header.SignalState = TRUE;
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Timer->Header.Inserted = FALSE;
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return FALSE;
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}
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//
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// Insert the timer in the timer table and return the inserted state.
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//
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return KiInsertTimerTable(Interval, CurrentTime, Timer);
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}
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LOGICAL
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FASTCALL
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KiInsertTimerTable (
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LARGE_INTEGER Interval,
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LARGE_INTEGER CurrentTime,
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IN PKTIMER Timer
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)
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/*++
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Routine Description:
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This function inserts a timer object in the timer table.
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N.B. This routine assumes that the dispatcher data lock has been acquired.
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Arguments:
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Interval - Supplies the relative timer before the timer is to expire.
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CurrentTime - supplies the current interrupt time.
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InTimer - Supplies a pointer to a dispatcher object of type timer.
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Return Value:
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If the timer is inserted in the timer tree, than a value of TRUE is
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returned. Otherwise, a value of FALSE is returned.
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--*/
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{
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ULONG Index;
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PLIST_ENTRY ListHead;
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PLIST_ENTRY NextEntry;
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PKTIMER NextTimer;
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#if DBG
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ULONG SearchCount;
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#endif
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//
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// Compute the timer table index and set the timer expiration time.
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//
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Index = KiComputeTimerTableIndex(Interval, CurrentTime, Timer);
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//
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// If the timer is due before the first entry in the computed list
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// or the computed list is empty, then insert the timer at the front
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// of the list and check if the timer has already expired. Otherwise,
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// insert then timer in the sorted order of the list searching from
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// the back of the list forward.
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//
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// N.B. The sequence of operations below is critical to avoid the race
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// condition that exists between this code and the clock interrupt
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// code that examines the timer table lists to detemine when timers
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// expire.
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//
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ListHead = &KiTimerTableListHead[Index];
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NextEntry = ListHead->Blink;
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#if DBG
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SearchCount = 0;
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#endif
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while (NextEntry != ListHead) {
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//
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// Compute the maximum search count.
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//
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#if DBG
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SearchCount += 1;
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if (SearchCount > KiMaximumSearchCount) {
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KiMaximumSearchCount = SearchCount;
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}
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#endif
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NextTimer = CONTAINING_RECORD(NextEntry, KTIMER, TimerListEntry);
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if (Timer->DueTime.QuadPart >= NextTimer->DueTime.QuadPart) {
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break;
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}
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NextEntry = NextEntry->Blink;
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}
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InsertHeadList(NextEntry, &Timer->TimerListEntry);
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if (NextEntry == ListHead) {
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//
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// The computed list is empty or the timer is due to expire before
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// the first entry in the list.
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//
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//
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// Make sure the writes for the insert into the list are done before
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// reading the interrupt time. KeUpdateSystemTime update will write
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// the time and then check the list for expired timers.
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//
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KeMemoryBarrier();
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KiQueryInterruptTime(&CurrentTime);
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if (Timer->DueTime.QuadPart <= (ULONG64)CurrentTime.QuadPart) {
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//
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// The timer is due to expire before the current time. Remove the
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// timer from the computed list, set its status to Signaled, and
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// set its inserted state to FALSE.
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//
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KiRemoveTreeTimer(Timer);
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Timer->Header.SignalState = TRUE;
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Timer->Header.Inserted = FALSE;
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}
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}
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return Timer->Header.Inserted;
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}
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