My latest project is a joint one. The project aim is to create an emulator for the Arduino set of boards.
Right now we're working on decoding the Atmel AVR instruction set. This comes comes as two parts.
1/ Work out which op-code it is so we can...
2/ Work out what format it is to determine what the parameters are.
I'm in the middle of 1/ at the moment, putting together a rather large look-up table with all the bit-masks to work out the op-code.
Likely enough it's only an 8-bit instruction set so quite simple!
The project will be on SourceForge soon!