usbgenericdescriptor.c

Atmel的AT91SAM7x256芯片的usb存储的源程序

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 *         ATMEL Microcontroller Software Support  -  ROUSSET  -
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/*
    Title: USBGenericDescriptor implementation

    About: Purpose
        Implementation of the USBGenericDescriptor class.
*/

//------------------------------------------------------------------------------
//         Headers
//------------------------------------------------------------------------------

#include "USBGenericDescriptor.h"

//------------------------------------------------------------------------------
//         Exported functions
//------------------------------------------------------------------------------
/*
    Function: USBGenericDescriptor_GetLength
        Returns the length of a descriptor.

    Parameters:
        descriptor - Pointer to a USBGenericDescriptor instance.

    Returns:
        Length of descriptor in bytes.
*/
unsigned int USBGenericDescriptor_GetLength(
    const USBGenericDescriptor *descriptor)
{
    return descriptor->bLength;
}

/*
    Function: USBGenericDescriptor_GetType
        Returns the type of a descriptor.

    Parameters:
        descriptor - Pointer to a USBGenericDescriptor instance.

    Returns:
        Type of descriptor.
*/
unsigned char USBGenericDescriptor_GetType(const USBGenericDescriptor *descriptor)
{
    return descriptor->bDescriptorType;
}

/*
    Function: USBGenericDescriptor_GetNextDescriptor
        Returns a pointer to the descriptor right after the given one, when
        parsing a Configuration descriptor.

    Parameters:
        descriptor - Pointer to a USBGenericDescriptor instance.

    Returns:
        Pointer to the next descriptor.
*/
USBGenericDescriptor *USBGenericDescriptor_GetNextDescriptor(
    const USBGenericDescriptor *descriptor)
{
    return (USBGenericDescriptor *)
        (((char *) descriptor) + USBGenericDescriptor_GetLength(descriptor));
}