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NC:parallel.PPARALLEL_TRY_ALLOCATE_ROUTINE

PPARALLEL_TRY_ALLOCATE_ROUTINE (parallel.h)

The PPARALLEL_TRY_ALLOCATE_ROUTINE-typed (ISR) callback routine attempts to allocate a parallel port at IRQL = DIRQL. The system-supplied function driver for parallel ports supplies this routine.

parports\parallel_try_allocate_routine__isr_.htm

parports

02/15/2018

PPARALLEL_TRY_ALLOCATE_ROUTINE callback

PPARALLEL_TRY_ALLOCATE_ROUTINE, ParallelTryAllocateRoutine, ParallelTryAllocateRoutine callback function [Parallel Ports], cisspd_737cb583-bcc9-46e9-915b-e073da2c11bf.xml, parallel/ParallelTryAllocateRoutine, parports.parallel_try_allocate_routine__isr_

parallel.h

Parallel.h

Desktop

DIRQL

Windows

RILGBATOKEN, *LPRILGBATOKEN

PPARALLEL_TRY_ALLOCATE_ROUTINE

parallel/PPARALLEL_TRY_ALLOCATE_ROUTINE

APIRef

kbSyntax

UserDefined

parallel.h

PPARALLEL_TRY_ALLOCATE_ROUTINE

PPARALLEL_TRY_ALLOCATE_ROUTINE callback

-description

The PPARALLEL_TRY_ALLOCATE_ROUTINE-typed (ISR) callback routine attempts to allocate a parallel port at IRQL = DIRQL. The system-supplied function driver for parallel ports supplies this routine.

-parameters

-param TryAllocateContext [in]

Pointer to the device extension of a functional device object that represents a parallel port.

-returns

Return code	Description
TRUE	The parallel port was allocated.
FALSE	The parallel port was not allocated.

-prototype

typedef BOOLEAN ParallelTryAllocateRoutine(
  _In_ PVOID TryAllocateContext
);

-remarks

A kernel-mode driver connects an interrupt service routine by using an IOCTL_INTERNAL_PARALLEL_CONNECT_INTERRUPT, which returns a PARALLEL_INTERRUPT_INFORMATION structure. This structure includes the TryAllocatePortAtInterruptLevel member, which is a pointer to the system-supplied PPARALLEL_TRY_ALLOCATE_ROUTINE (ISR) callback.

The PPARALLEL_TRY_ALLOCATE_ROUTINE (ISR) callback is nonblocking, does not queue an allocate request, and returns immediately.

A driver uses the PPARALLEL_TRY_ALLOCATE_ROUTINE (ISR) callback in conjunction with a driver-supplied ISR. If the driver does not have a parallel port allocated when the driver's ISR is called, the driver can use this callback.

For more information about allocating a parallel port in an ISR, see Connecting an Interrupt Service Routine to a ParallelPort.

Note The PPARALLEL_TRY_ALLOCATE_ROUTINE (ISR) callback is untested. Microsoft does not recommend using a client-supplied interrupt routine. The use of interrupts might cause system instability. By default, the IOCTL_INTERNAL_PARALLEL_CONNECT_INTERRUPT request is disabled.