Custom Program for a factory computer

[Eric Aos]

Has anyone written a complete program for the factory hardware?  It
seems that the registers are pretty well figured out for some of them.
How hard could it be to convert say the program for EFI332 to run on the
GM Processor? is there a C compiler available? It would give all the
benefits of proven hardware, and complete flexibility for those that
just need to control Injectors, and Ignition. Perhaps the best of both
worlds, would be to run a multi-chip, with a tweaked stock program for
daily driving, and full race code for Sunday?