Microsoft Windows CE 3.0  

WIDM_PREPARE

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This message is used in an MMDRV_MESSAGE_PARAMSstructure passed to the WAV_IOControlfunction to request a waveform input driver to prepare a system-exclusive data buffer for input.

Parameters

uDeviceId
Device identifier — 0, 1, 2, and so on — for the target device.
uMsg
Specifies this message.
dwUser
Specifies a device instance identifier.
dwParam1
Specifies a pointer to a WAVEHDRstructure identifying the buffer.
dwParam2
Specifies the size, in bytes, of WAVEHDR.

Return Values

MMSYSERR_NOERROR indicates success. Otherwise, the driver returns one of the MMSYSERR or WAVEERR error values declared in the Mmsystem.h header file.

Remarks

The ACM sends this message by calling the audio driver's WAV_IOControlentry point through the DeviceIoControlfunction.

Support for this message by drivers is optional. However, if the driver supports this message, it must support WIDM_UNPREPARE.

If the driver returns MMSYSERR_NOTSUPPORTED, Waveapi.dll prepares the buffer for use. For most drivers, this behavior is sufficient. If the driver performs buffer preparation, it must set WHDR_PREPARED in the dwFlagsmember of WAVEHDRand return MMSYSERR_NOERROR.

Requirements

Runs on Versions Defined in Include Link to
Windows CE OS 1.0 and later      
Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.


 Last updated on Tuesday, July 13, 2004

© 2004 Microsoft Corporation. All rights reserved.