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Preliminary User Guide, Rev. 2 USS-720
February 1999 USB Device Driver
Lucent Technologies Inc. 7-21
13
4 I/O Control Codes (continued)
4.12 IOCTL_GET_DEVICE_DESCRIPTOR
IOCTL_GET_DEVICE_DESCRIPTOR retrieves the current device descriptor. Details regarding parameters and
error codes follow.
4.12.1 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 USB_DEVICE_DESCRIPTOR data structure (see
WDM
USB Driver Specification
).
nOutBufferSize—Specifies the size (in bytes) of the buffer pointed to by lpOutBuffer, which must be large enough to
contain the USB_DEVICE_DESCRIPTOR data structure (see
WDM USB Driver Specification
). Specify zero to
return only the length of the Device ID string in lpBytesReturned.
lpBytesReturned—Points to a DWORD that receives the actual size (in bytes) of the data stored into lpOutBuffer.
4.12.2 Notes
None.
4.12.3 Error Code
ERROR_NOT_ENOUGH_BUFFER—lpOutBuffer was not large enough to receive the USB Device Descriptor.