/*++

Copyright (c) 1989  Microsoft Corporation

Module Name:

    delay.c

Abstract:

   This module implements the executive delay execution system service.

Author:

    David N. Cutler (davec) 13-May-1989

Environment:

    Kernel mode only.

Revision History:

--*/

#include "exp.h"

#ifdef ALLOC_PRAGMA
#pragma alloc_text(PAGE, NtDelayExecution)
#endif


NTSTATUS
NtDelayExecution (
    IN BOOLEAN Alertable,
    IN PLARGE_INTEGER DelayInterval
    )

/*++

Routine Description:

    This function delays the execution of the current thread for the specified
    interval of time.

Arguments:

    Alertable - Supplies a boolean value that specifies whether the delay
        is alertable.

    DelayInterval - Supplies the absolute of relative time over which the
        delay is to occur.

Return Value:

    TBS

--*/

{

    LARGE_INTEGER Interval;
    KPROCESSOR_MODE PreviousMode;
    NTSTATUS Status;

    //
    // Establish an exception handler and probe delay interval address. If
    // the probe fails, then return the exception code as the service status.
    // Otherwise return the status value returned by the delay execution
    // routine.
    //

    try {

        //
        // Get previous processor mode and probe delay interval address if
        // necessary.
        //

        PreviousMode = KeGetPreviousMode();
        if (PreviousMode != KernelMode) {
            ProbeForRead(DelayInterval, sizeof(LARGE_INTEGER), sizeof(ULONG));
        }
        Interval = *DelayInterval;

        //
        // Delay execution for the specified amount of time.
        //

        Status = KeDelayExecutionThread(PreviousMode, Alertable, &Interval);

    //
    // If an exception occurs during the probing of the delay interval address,
    // then always handle the exception and return the exception code as the
    // status value.
    //

    } except(EXCEPTION_EXECUTE_HANDLER) {
        return GetExceptionCode();
    }

    //
    // Return service status.
    //

    return Status;
}