AUXDM_GETNUMDEVS

The AUXDM_GETNUMDEVS message requests an auxiliary audio driver to return the number of auxiliary audio device instances that it supports.

Parameters

uDeviceId

Device identifier (0, 1, 2, and so on) for the target device.

uMsg

AUXDM_GETNUMDEVS

dwUser

Not used.

dwParam1

Not used.

dwParam2

Not used.

Return Value

The driver returns the number of auxiliary audio device instances it supports.

Comments

A client sends the AUXDM_GETNUMDEVS message by calling the user-mode driver’s auxMessage entry point, passing the specified parameters.

The driver should return the number of logical auxiliary audio devices that can be supported. Typically, for each physical device, a kernel-mode driver can support one or more logical devices of various types. For example, for each Creative Labs Sound Blaster card, there are MIDI, waveform input, mixer, and auxiliary audio devices. Kernel-mode drivers store logical device names and types in the registry under the path HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DriverName\Parameters\DeviceNumber\Devices. To correctly return the number of logical devices, the user-mode driver should examine the \Devices subkey for each of the driver’s \DeviceNumber keys, searching for logical devices of the desired type. (Code in drvlib.lib provides this capability.)