Lucent Technologies USS-720 manual Ioctlgetaltsetting, ALTINTERFACE0, ALTINTERFACE1, ALTINTERFACE2

USS-720	Preliminary User Guide, Rev. 2
USB Device Driver	February 1999

4 I/O Control Codes (continued)

4.9 IOCTL_GET_ALTSETTING

IOCTL_GET_ALTSETTING retrieves the current alternate interface setting from the USS-720 device. Details regarding parameters and error codes follow.

4.9.1 Parameters

lpInBuffer—Points to an input buffer. Not used with this operation. Set to NULL.

nInBufferSize—Specifies the size (in bytes) of the buffer pointed to by lpInBuffer. Not used with this operation. Set to zero.

lpOutBuffer—Points to an output buffer that will receive a single byte indicating the current alternate setting based on one of the following:

Value	Description
ALT_INTERFACE_0	Bulk Out pipe only.
ALT_INTERFACE_1	Bulk Out and Bulk In pipe.
ALT_INTERFACE_2	Bulk Out, Bulk In, Interrupt pipe, and 1284 register capabilities.

nOutBufferSize—Specifies the size (in bytes) of the buffer pointed to by lpOutBuffer. The buffer must be large enough to contain one byte value.

lpBytesReturned—Points to a DWORD that receives the actual size (in bytes) of the data stored into lpOutBuffer.

4.9.2 Notes

None.

4.9.3 Error Code

ERROR_NOT_ENOUGH_BUFFER—lpOutBuffer needs to be large enough to contain one byte value.

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