IOReturn
GetBandwidth( IOFireWireLibDeviceRef device, UInt32 * bandwidth )
{
    OSStatus        error ;
    UInt16      irmNodeID ;
    UInt32      generation ;

    // get current bus generation
    error = (**device).GetBusGeneration( device, & generation ) ;

    if ( !error )
    {
        // get ID of IRM
        error = (**device).GetIRMNodeID( device, generation, & irmNodeID ) ;
    }

    if ( !error )
    {
        // build the FireWire address of the BANDWIDTH_AVAILABLE register
        FWAddress address = { irmNodeID,
                              kCSRRegisterSpaceBaseAddressHi, 
                              kCSRBandwidthAvailable } ;

        UInt32 size = sizeof( *bandwidth ) ;

        // read the BANDWIDTH_AVAILABLE register
        error = (**device).Read( device,
                                 0,
                                 address,
                                 bandwidth,
                                 &size,
                                 true,
                                 generation ) ;
    }

    return( error );
}