A protocol decoder for SPI, Dual SPI and Quad SPI (QSPI) for use with sigrok/pulseview

The QUAD SPI (Serial Peripheral Interface) protocol decoder supports synchronous SPI(-like) protocols with a clock line and 1, 2 or 4 bidirectional data lines. The first byte (command) determines which lines are used to transmit the following bytes based on the chosen command set (e.g. SPI Memory)

IO0/MOSI is required. Other IOs are optional.