New protocol decoder: rgb_led_spi

We're happy to announce that there's a new protocol decoder available in libsigrokdecode since today, rgb_led_spi (thanks to Matt Ranostay for the contribution!).

This is a small PD that decodes RGB (red/green/blue) values for a certain type of LED controller that are sent from a host/microcontroller via SPI in order to light up the LEDs in a certain color.

It can be used for decoding data to a WorldSemi WS2801 RGB LED controller, for example (see the led/ws2801 directory in the sigrok-dumps repo for sample files).

Since this (rather simple) "protocol" is transmitted over SPI, the protocol decoder can make use of the stacking feature in libsigrokdecode and simply stack upon the spi decoder (thus avoiding having to re-implement all of the SPI handling in the RGB LED decoder itself).

Happy LED blinking!