windows driver中的IO_STACK_LOCATION

define IoSkipCurrentIrpStackLocation( Irp ) /
(Irp)->CurrentLocation++; /
(Irp)->Tail.Overlay.CurrentStackLocation++; 

#define IoCopyCurrentIrpStackLocationToNext  ( Irp )   
Value:
{ /
    PIO_STACK_LOCATION irpSp; /
    PIO_STACK_LOCATION nextIrpSp; /
    irpSp = IoGetCurrentIrpStackLocation( (Irp) ); /
    nextIrpSp = IoGetNextIrpStackLocation( (Irp) ); /
    RtlCopyMemory( nextIrpSp, irpSp, FIELD_OFFSET(IO_STACK_LOCATION, CompletionRoutine)); /
    nextIrpSp->Control = 0; }
 
NTSTATUS
IoCallDriver(
    IN PDEVICE_OBJECT DeviceObject,
    IN OUT PIRP Irp
    )
{
    return IofCallDriver (DeviceObject, Irp);
}

NTSTATUS
FASTCALL
IofCallDriver(
    IN PDEVICE_OBJECT DeviceObject,
    IN OUT PIRP Irp
    )
{
    //
    // This routine will either jump immediately to IopfCallDriver, or rather
    // IovCallDriver.
    //
    return pIofCallDriver(DeviceObject, Irp);
}
 
NTSTATUS
FASTCALL
IopfCallDriver(
    IN PDEVICE_OBJECT DeviceObject,
    IN OUT PIRP Irp
    )
/*++
Routine Description:
    This routine is invoked to pass an I/O Request Packet (IRP) to another
    driver at its dispatch routine.
Arguments:
    DeviceObject - Pointer to device object to which the IRP should be passed.
    Irp - Pointer to IRP for request.
Return Value:
    Return status from driver's dispatch routine.
--*/
{
    PIO_STACK_LOCATION irpSp;
    PDRIVER_OBJECT driverObject;
    NTSTATUS status;
    //
    // Ensure that this is really an I/O Request Packet.
    //
    ASSERT( Irp->Type == IO_TYPE_IRP );
    //
    // Update the IRP stack to point to the next location.
    //
    Irp->CurrentLocation--;
    if (Irp->CurrentLocation <= 0) {
        KeBugCheckEx( NO_MORE_IRP_STACK_LOCATIONS, (ULONG_PTR) Irp, 0, 0, 0 );
    }
    irpSp = IoGetNextIrpStackLocation( Irp );
    Irp->Tail.Overlay.CurrentStackLocation = irpSp;
    //
    // Save a pointer to the device object for this request so that it can
    // be used later in completion.
    //
    irpSp->DeviceObject = DeviceObject;
    //
    // Invoke the driver at its dispatch routine entry point.
    //
    driverObject = DeviceObject->DriverObject;
    PERFINFO_DRIVER_MAJORFUNCTION_CALL(Irp, irpSp, driverObject);
    status = driverObject->MajorFunction[irpSp->MajorFunction]( DeviceObject,
                                                              Irp );
    PERFINFO_DRIVER_MAJORFUNCTION_RETURN(Irp, irpSp, driverObject);
    return status;
}