This might be useful for anyone starting an RF project with the inexpensive RF-KLPA trans/receiv pair.
http://home.earthlink.net/~dtvii/
It uses a couple AVRs (Atmega8L & ATtiny2313) to form the encoder/decoder logic. All the code is written in AVRGCC.
There’s a fairly good manchester-decoding routine in the receiver code. It’s nibble-oriented (small modifications would be needed to send a full byte) but fast. The manchester-encoding routine just uses an array.