PPARALLEL_WRITE callback function (parallel.h)

Article
10/21/2021

The PPARALLEL_WRITE-typed callback routine writes data to a parallel device. The system-supplied bus driver for parallel ports supplies this routine.

Syntax

PPARALLEL_WRITE PparallelWrite;

NTSTATUS PparallelWrite(
  [in]  PVOID Context,
  [in]  PVOID Buffer,
  [in]  ULONG NumBytesToWrite,
  [out] PULONG NumBytesWritten,
  [in]  UCHAR Channel
)
{...}

Parameters

[in] Context

Pointer to the device extension of a parallel device's physical device object (PDO).

[in] Buffer

Pointer to a caller-allocated write buffer.

[in] NumBytesToWrite

Specifies the number of bytes to copy from the write buffer to the parallel device. Must be less than or equal to the number of bytes in the caller-allocated write buffer.

[out] NumBytesWritten

Specifies the number of bytes that were actually copied from the caller-allocated write buffer to the parallel device.

[in] Channel

Not used.

Return value

Return code	Description
STATUS_SUCCESS	The caller-supplied data was successfully transferred to the device.
STATUS_Xxx	An internal operation resulted in an NTSTATUS error.

Remarks

To obtain a pointer to the system-supplied PPARALLEL_WRITE callback, a kernel-mode driver uses an IOCTL_INTERNAL_PARCLASS_CONNECT request, which returns a PARCLASS_INFORMATION structure. The ParallelWrite member of the PARCLASS_INFORMATION structure is a pointer to this callback.

A client can only use this routine if it has a lock on a parallel port. A client obtains a lock on a parallel port by using an IOCTL_INTERNAL_LOCK_PORT request.

The PPARALLEL_WRITE callback runs in the caller's thread at the IRQL of the caller.

Requirements

Requirement	Value
Target Platform	Desktop
Header	parallel.h (include Parallel.h)

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