ipa_proto: Add notion of 'codecs'

A codec for a given Stream Identifier can be registered with encode
and decode functions.  This codec transcodes from the binary payload
of messages within that stream identifier and some abstract
representation.  Any received messages will be passed through decode,
while any to-be-transmitted messages will be passed through encode.

Change-Id: I8eaf888402545a1a871df9ae3dfbce690729dd03
1 file changed