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

(INTERFACE) - ..... (INTERFACE)

(ENDPOINT) - ..... (ENDPOINT)

Any vendor-speciﬁc or class-speciﬁc descriptors that are embedded

into the standard descriptor output are also inserted into this tree at the

appropriate point.

Although a descriptor for endpoint 0 (control) isn’t present on the

wire, one is constructed and placed in the tree (to simplify

enumeration within the class driver).

You use type for specifying the type of descriptor to ﬁnd; index is the

nth occurrence. Note that type 0 will match any descriptor type; you

can use it to retrieve any embedded class or vendor-speciﬁc

descriptors if you don’t know their type.

Here’s an example that will walk all endpoints for an interface:

for (eix = 0; (desc = usbd parse descriptors(device, ifc, USB DESC ENDPOINT,

eix, &ept)) != NULL; ++eix)

;

where ifc is the appropriate (INTERFACE) node (found by a previous

call to usbd

parse descriptors() or usbd interface descriptor().

Returns:

A pointer to the descriptor on success, NULL on error.

Classiﬁcation:

QNX Neutrino, QNX 4

Safety

Cancellation point No

Interrupt handler No

Signal handler No

continued.. .

72 Chapter 4 USB Library Reference November 2, 2006

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Belkin F8E211 Guía de usuario Pagina 84