While working on some projects involving things like (sometimes unknown) binary protocols via a TTY, or dealing with small binary protocol chunks in other protocol streams I realised that once I can pretty print decoded protocol frames I have half of the emacs implementation ready - and the other way round.
I built a debug framework around that, noticed how useful it'd be to use the same code to sniff and pretty-print communication between the device and the closed client - and added the option to run helpers that forward packets at linespeed, and make them available to emacs at its own pace. At that point I realised that this could be useful as a standalone package, and started ripping it out of that codebase to form lempo as a standalone package.
The screenshot is a pcap bridge helper I've added as simple demonstration of the concept - it's pretty easy to have that as self contained module. The setup in the scratch buffer is because the interactive path for doing that broke a bit when ripping the code out - I should be able to fix that over the next few days, though.
While this currently heavily focuses on binary protocols (and with that, mostly nicely printed hex dumps) doing helper bridges decoding higher level protocols should be easily doable as well.
The current code (with the "I'm still fixing the bits I broke by making it standalone" warning) is at https://github.com/aardsoft/lempo/
