MODM_STOP function

WINMM sends the MODM_STOP message to the modMessage function of a MIDI output driver to stop output from the output queue and to turn off any notes that are playing.

Syntax

DWORD modMessage(
   UINT      uDeviceID,
   UINT      uMsg,
   DWORD_PTR dwUser,
   DWORD_PTR dwParam1,
   DWORD_PTR dwParam2
);

Parameters

• uDeviceID
  Specifies the ID of the target device. Device IDs are sequential and have an initial value of zero and a final value that is equal to one less than the number of devices that the driver supports.

• uMsg
  WINMM sets this parameter to MODM_STOP when it calls modMessage to process this message.

• dwUser
  Use this parameter to return instance data to the driver. Drivers that support multiple clients can use this instance data to track the client that is associated with the message.

• dwParam1
  Not used.

• dwParam2
  Not used.

Return value

The modMessage function returns MMSYSERR_NOERROR if the operation is successful. Otherwise it returns MMSYSERR_NOTENABLED to indicate that the driver failed to load or initialize.

Remarks

If the output queue of the MIDI output driver is not empty, it must stop all pending data blocks and mark them as done by setting the MHDR_DONE bit in the dwFlags field of the MIDIHDR structure for each block. The driver must then notify the client by using DriverCallback to send a MOM_DONE message for each data block.

The driver should send a note-off event for all notes that are currently turned on. In addition, the driver should send a damper pedal off event (controller 0x40) for each channel. If the device is an internal synthesizer, the driver should turn off any notes that are playing.

Requirements

See also

modMessage

DriverCallback

MIDIHDR

MOM_DONE