MODM_GETNUMDEVS function

WINMM sends the MODM_GETNUMDEVS message to the modMessage function of a MIDI output driver to request the number of MIDI output devices available.

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_GETNUMDEVS 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 keep track of the client that is associated with the message.

• dwParam1
  Not used.

• dwParam2
  Not used.

Return value

The modMessage function returns the number of MIDI output devices that the driver supports.

Remarks

Drivers can be structured in several ways. The simplest and most common drivers use one physical device to support one logical device. Drivers can also support multiple logical devices by using a single physical device. For example, a driver can use a single digital signal processor (DSP) to support two different types of internal synthesizers. Such a driver would return a value of "2" in response to the MODM_GETNUMDEVS message.

Requirements

See also

ModMessage