PPARALLEL_FREE_ROUTINE callback function (parallel.h)
The PPARALLEL_FREE_ROUTINE-typed callback routine frees a parallel port. The system-supplied function driver for parallel ports supplies this routine.
Syntax
PPARALLEL_FREE_ROUTINE PparallelFreeRoutine;
void PparallelFreeRoutine(
[in] PVOID FreeContext
)
{...}
Parameters
[in] FreeContext
Pointer to the device extension of a parallel port's functional device object (FDO).
Return value
None
Remarks
To obtain a pointer to the system-supplied PPARALLEL_FREE_ROUTINE callback, a kernel-mode driver uses an IOCTL_INTERNAL_GET_PARALLEL_PORT_INFO request, which returns a PARALLEL_PORT_INFORMATION structure. The FreePort member of the PARALLEL_PORT_INFORMATION structure is a pointer to this callback.
The driver should allocate a parallel port before freeing it. A driver can use PPARALLEL_QUERY_WAITERS_ROUTINE to determine the number of clients that are waiting to allocate the parallel port, and PPARALLEL_TRY_ALLOCATE_ROUTINE to try to allocate the parallel port.
For more information, see Synchronizing the Use of a ParallelPort.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Desktop |
| Header | parallel.h (include Parallel.h) |
| IRQL | <=DISPATCH_LEVEL |
See also
IOCTL_INTERNAL_GET_PARALLEL_PORT_INFO