modMessage

DWORD modMessage(uDeviceID, uMsg, dwUser, dwParam1, dwParam2)

Entry point for a MIDI output device driver. This function is supplied by the user.

• Unless specified otherwise under a specific message, the driver should return an MMSYSERR_ or MIDIERR_ error code.

UINT uDeviceID

Specifies the ID of the target device. Device IDs are sequential, starting at zero and ending at a value equal to one less than the number of devices the driver supports.

UINT uMsg

Specifies the message being sent to the driver.

DWORD dwUser

For the MODM_OPEN message, the driver should fill this location with its instance data. For any other messages, the instance data is returned to the driver. Drivers supporting multiple clients can use this instance data to keep track of which client is associated with the message.

DWORD dwParam1

Specifies a message-dependent parameter.

DWORD dwParam2

Specifies a message-dependent parameter.

The driver should return MMSYSERR_NOTSUPPORTED if it does not support the specified message.