New protocol decoder: Qi

Another somewhat recently added protocol decoder for libsigrokdecode is the qi PD.

This PD decodes demodulated data streams used by the Qi standard for communication from the receiver to the charging station. You can read more about the Wireless power consortium's Qi standard on Wikipedia.

As always, we have a few example files in the sigrok-dumps repo and some test-cases in the sigrok-test repo.

The decoder was contributed by Josef Gajdusek, thanks a lot!