IMiniportMidiStream::Read method (portcls.h)

Article
02/22/2024

The Read method reads data from an incoming MIDI stream.

Syntax

NTSTATUS Read(
  [in]  PVOID  BufferAddress,
  [in]  ULONG  BufferLength,
  [out] PULONG BytesRead
);

Parameters

[in] BufferAddress

Specifies the address of a caller-allocated buffer. The method copies the incoming MIDI data from the device to the buffer. The allocated size of this buffer must be greater than or equal to BufferLength.

[in] BufferLength

Specifies the length in bytes of the buffer pointed to by BufferAddress.

[out] BytesRead

Output pointer to a caller-allocated variable into which the method writes a count specifying the actual number of bytes successfully read from the device into the buffer.

Return value

Read returns STATUS_SUCCESS if the call was successful. Otherwise, the method returns an appropriate error code. The following table shows some of the possible return status codes.

Return code	Description
STATUS_INVALID_DEVICE_REQUEST	Invalid device request (for example, calling `Read` on a MIDI output stream).

Remarks

The miniport driver calls IPortMidi::Notify to notify the port driver when incoming MIDI data becomes available from the capture device. The port driver calls IMiniportMidi::Read to retrieve the data. The port driver continues to call Read as long as more data is available.

The Read method returns STATUS_SUCCESS and a BytesRead count of zero to indicate that no more MIDI input data is currently available from the device.

Requirements

Requirement	Value
Target Platform	Universal
Header	portcls.h (include Portcls.h)
IRQL	DISPATCH_LEVEL