plus making it work w/o hw flow control and using better digests for integrity checks and (in case of F&C implementation) minimizing the amount of data to be wr

plus making it work w/o hw flow control and using better digests for integrity checks and (in case of F&C implementation) minimizing the amount of data to be written. it's all pretty common. the most difficult part was figuring out the "stub environment" and reverse-engineering existing rom to find the necessary parts of functionality. e.g. how to reboot into fw correctly after flashing.