This archive contains several scripts to process logs get with sniffusb (see tools). The first one to use is decode.sh which turns raw USB data into a readable form. Then you can use cmd.sh on the output of the first script to see what's the scanner is doing. This second script builds an internal state that reflects what the ASIC state would be and uses sart/stop motor commands as commits.
The process of adapting the backend is to process USB data, run a test scan of the backend with full debugging activated, then compare both. Fix differences until it works.
Once downloaded and extracted to a directory, you can configure it with
./configure --enable-libusb, compile it with
make, then you can run this testing version -without installing it- with 2 scripts located in the backend subdirectory. 'run-xp200' and 'run-genesys'. In case you do some test, please send me the *.log and *.pnm files that will be created.