Why do you want the code in ANSI C, and not just in the
programming language C?
Note that the protocol handler will be quite close to the
hardware, so it isn't unlikely that your own implementation will not
be 100% ANSI or ISO.
A more important criteria if asking for code is to request tested
and/or well-documented code and to add criterias for allowed
If the code is tested and well-documented, then it is probably in
a good enough state that you can modify it for your hardware -
possibly removing some non-ISO keywords and possibly adding some
other non-ISO keywords.