usbgenericdescriptor.c

useful when developer using ARM7 to interface HID devices like USB Keyboard

/* ----------------------------------------------------------------------------
 *         ATMEL Microcontroller Software Support 
 * ----------------------------------------------------------------------------
 * Copyright (c) 2008, Atmel Corporation
 *
 * All rights reserved.
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 * this software without specific prior written permission.
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/*
    Title: USBGenericDescriptor implementation

    About: Purpose
        Implementation of the USBGenericDescriptor class.
*/

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

#include "USBGenericDescriptor.h"

//------------------------------------------------------------------------------
//         Exported functions
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
/// Returns the length of a descriptor.
/// \param descriptor Pointer to a USBGenericDescriptor instance.
/// \return Length of descriptor in bytes.
//------------------------------------------------------------------------------
unsigned int USBGenericDescriptor_GetLength(
    const USBGenericDescriptor *descriptor)
{
    return descriptor->bLength;
}

//------------------------------------------------------------------------------
/// Returns the type of a descriptor.
/// \param descriptor Pointer to a USBGenericDescriptor instance.
/// \return Type of descriptor.
//------------------------------------------------------------------------------
unsigned char USBGenericDescriptor_GetType(
    const USBGenericDescriptor *descriptor)
{
    return descriptor->bDescriptorType;
}

//------------------------------------------------------------------------------
/// Returns a pointer to the descriptor right after the given one, when
/// parsing a Configuration descriptor.
/// \param descriptor - Pointer to a USBGenericDescriptor instance.
/// \return Pointer to the next descriptor.
//------------------------------------------------------------------------------
USBGenericDescriptor *USBGenericDescriptor_GetNextDescriptor(
    const USBGenericDescriptor *descriptor)
{
    return (USBGenericDescriptor *)
        (((char *) descriptor) + USBGenericDescriptor_GetLength(descriptor));
}