Belkin F8E211 Uživatelská příručka stáhnout pdf (Strana 46)

usbd

Get or set 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 );

Arguments:

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.

Library:

libusbdi

Description:

The usbd

descriptor() function lets you obtain the USB descriptors.

Returns:

EMSGSIZE Buffer too small for descriptor.

ENOMEM No memory for URB.

32 Chapter 4 • USB Library Reference September 10, 2007

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Belkin F8E211 Uživatelská příručka Strana 46