tool wanted: to convert utf8 <-> unicode in hex

[Skaperen]

i am looking for a tool to convert both ways between utf8 and unicode without using any builtin python conversion (if it is written in python) for the purpose of cross checking usage of python conversion code to be sure it is correct. this tool needs to come in easily readable and compilable/runnable source code. it needs to be organized in a simple way to make correctness verification easier. C and/or Pike and/or Python would be preferred because i can more easily read those. else i'll end up making my own in C some day. it needs to take input in args or STDIN (if args are empty) and output the converted to STDOUT.