Belkin F8E211 Guia do Utilizador descarregar pdf (Página 52)

usbd descriptor()  2006, QNX Software Systems GmbH & Co. KG.

Get USB descriptors.

Synopsis:

#include <sys/usbdi.h>

int usbd

descriptor( struct usbd device *device,

int set,

uint8 type, uint16 rtype,

uint8 index, uint16 langid,

uint8 *desc, size t len );

Description:

The usbd descriptor() function lets you obtain the USB descriptors.

device An opaque handle used to identify the USB device.

set A ﬂag that says to either get or set a descriptor.

type Type of descriptor (e.g.

USB DESC DEVICE,

USB DESC CONFIGURATION, USB DESC STRING,

USB DESC HUB).

rtype Type of request (e.g.

USB RECIPIENT DEVICE,

USB RECIPIENT INTERFACE,

USB RECIPIENT ENDPOINT, USB RECIPIENT OTHER,

USB TYPE STANDARD, USB TYPE CLASS,

USB TYPE VENDOR).

index This varies, depending on the request. It’s used for passing

a parameter to the device.

langid Identiﬁes the language supported in strings (according to

the LANGID table).

desc Pointer at buffer to put descriptors.

len The length of the data transfer in bytes.

40 Chapter 4 USB Library Reference November 2, 2006

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