'Convert a relative address in some memory region to an absolute address.
:param region_id:           The memory region ID
:param relative_address:    The relative memory offset in that memory region
:return:                    An absolute address if converted, or an exception is raised when region id does not
exist.'

def absolutize(self, region_id, relative_address):

    if (region_id == 'global'):
        return relative_address
    if (region_id not in self._region_id_to_address):
        raise SimRegionMapError(('Non-existent    region    ID    "%s"' % region_id))
    base_address = self._region_id_to_address[region_id].base_address
    return (base_address + relative_address)
