usbconfigurationdescriptor.c

This application creates an USB Mass Storage drive on a host computer. The drive is created from the

/* ----------------------------------------------------------------------------
 *         ATMEL Microcontroller Software Support  -  ROUSSET  -
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 * Copyright (c) 2006, Atmel Corporation

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/*
    Title: USBConfigurationDescriptor implementation

    About: Purpose
        Implementation of the USBConfigurationDescriptor class.
*/

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

#include "USBConfigurationDescriptor.h"

//------------------------------------------------------------------------------
//         Exported functions
//------------------------------------------------------------------------------
/*
    Function: USBConfigurationDescriptor_GetTotalLength
        Returns the total length of a configuration, i.e. including the 
        descriptors following it.

    Parameters:
        configuration - Pointer to a USBConfigurationDescriptor instance.

    Returns:
        Total length (in bytes) of the configuration.
*/
unsigned int USBConfigurationDescriptor_GetTotalLength(
    const USBConfigurationDescriptor *configuration)
{
    return configuration->wTotalLength;
}

/*
    Function: USBConfigurationDescriptor_GetNumInterfaces
        Returns the number of interfaces in a configuration.

    Parameters:
        configuration - Pointer to a USBConfigurationDescriptor instance.

    Returns:
        Number of interfaces in configuration.
*/
unsigned char USBConfigurationDescriptor_GetNumInterfaces(
    const USBConfigurationDescriptor *configuration)
{
    return configuration->bNumInterfaces;
}

/*
    Function: USBConfigurationDescriptor_IsSelfPowered
        Indicates if the device is self-powered when in a given configuration.

    Parameters:
        configuration - Pointer to a USBConfigurationDescriptor instance.

    Returns:
        1 if the device is self-powered when in the given configuration;
        otherwise 0.
*/
unsigned char USBConfigurationDescriptor_IsSelfPowered(
    const USBConfigurationDescriptor *configuration)
{
    if ((configuration->bmAttributes & (1 << 6)) != 0) {

        return 1;
    }
    else {

        return 0;
    }
}

/*
    Function: USBConfigurationDescriptor_Parse
        Parses the given Configuration descriptor (followed by relevant
        interface, endpoint and class-specific descriptors) into three arrays.

        *Each array must have its size equal or greater to the number of
        descriptors it stores plus one*. A null-value is inserted after the last
        descriptor of each type to indicate the array end.

        Note that if the pointer to an array is null (0), nothing is stored in
        it.

    Parameters:
        configuration - Pointer to the start of the whole Configuration descriptor.
        interfaces - Pointer to the Interface descriptor array.
        endpoints - Pointer to the Endpoint descriptor array.
        others - Pointer to the class-specific descriptor array.
*/
void USBConfigurationDescriptor_Parse(
    const USBConfigurationDescriptor *configuration,
    USBInterfaceDescriptor **interfaces,
    USBEndpointDescriptor **endpoints,
    USBGenericDescriptor **others)
{
    // Get size of configuration to parse
    int size = USBConfigurationDescriptor_GetTotalLength(configuration);
    size -= sizeof(USBConfigurationDescriptor);

    // Start parsing descriptors
    USBGenericDescriptor *descriptor = (USBGenericDescriptor *) configuration;
    while (size > 0) {

        // Get next descriptor
        descriptor = USBGenericDescriptor_GetNextDescriptor(descriptor);
        size -= USBGenericDescriptor_GetLength(descriptor);

        // Store descriptor in correponding array
        if (USBGenericDescriptor_GetType(descriptor)
             == USBGenericDescriptor_INTERFACE) {

            if (interfaces) {
            
                *interfaces = (USBInterfaceDescriptor *) descriptor;
                interfaces++;
            }
        }
        else if (USBGenericDescriptor_GetType(descriptor)
                  == USBGenericDescriptor_ENDPOINT) {

            if (endpoints) {
                
                *endpoints = (USBEndpointDescriptor *) descriptor;
                endpoints++;
            }
        }
        else if (others) {

            *others = descriptor;
            others++;
        }
    }

    // Null-terminate arrays
    if (interfaces) {

        *interfaces = 0;
    }
    if (endpoints) {

        *endpoints = 0;
    }
    if (others) {

        *others = 0;
    }
}