For Chris, mostly,

In my AX25 code, the two queues are named read_data and write_data, you can search for those values. The length, position, and size are right after it and described in the comment above.

There are also some functions named "sub_seq", "add_seq" and "seq_in_range" that handle the wraparound. In particular, seq_in_range is a little tricky. And I see that I should comment those better.

And if you want, I can look at splitting up my code into a library that has the state machine that could be re-used. It may be some overkill, though, it does all the extended sequencing, XID, and such that we don't need.

-corey