titan requires prototype(fast) functions for translation ports
Submitted by Kristof Szabados
In it current implementation titan requires function used as translation frunctions to have a prototype(fast) attribute.
Otherwise an error is reported:
In type mapping:
function' mapping: error: The referenced function @PortTranslation.char_to_hex' does not have `prototype' fast attribute
But the standard does not list such a requirement for the usable functions.