A quick pulseview decoder for matching a series of bytes

pd.py

import sigrokdecode as srd
import collections

# Matches to find.
# A list of tuples that contain (ByteToMatch, Name)
Matches = [
    ([0x20, 0x20], "Match One!"),
    ([0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07], "Match Two!"),
    ([0xFF, 0xAA, 0xCC, 0x55], "Match Three!"),
]

# Standard Decoder
class Decoder(srd.Decoder):
    # Decoder stuff that needs to exist for pulseview to be happy
    api_version = 3
    id = "ByteMatch"
    name = "Byte Matcher"
    longname = "A Byte Matcher"
    desc = "This decoder searches for arbitrary set of bytes"
    license = "MIT"
    inputs = ["spi"]  # CHANGE THE DECODE YOU WANT TO STACK ONTOP OF
    outputs = []
    tags = ["IC", "Memory"]
    annotations = (("Matches", "Matches"),)
    annotation_rows = (("Matches", "Matches", (0,)),)
    options = ()

    def __init__(self):
        # Circular buffers for keeping track of the last few bytes
        # Make the buffers the size of the largest match
        MaxLength = max([len(bytes) for bytes, name in Matches])
        # The last few bytes
        self.LastBytes = collections.deque(maxlen=MaxLength)
        # The last few start-samples
        self.LastSamples = collections.deque(maxlen=MaxLength)

    def reset(self):
        # Reset the circular buffers
        self.LastBytes.clear()
        self.LastSamples.clear()

    def start(self):
        # Standard Pulseview Stuff
        self.out_ann = self.register(srd.OUTPUT_ANN)

    def decode(self, startSample, endSample, data):
        # Grab the data from your lower level decoder.
        ptype, mosi, miso = data
        # In this case I only care about full bytes from the decoder (DATA).
        # Do not care about indiviual bits (BITS)
        if ptype != "DATA":
            return

        # Keep track of the byte we just saw and the sample it started at (for annotations)
        self.LastBytes.append(miso)
        self.LastSamples.append(startSample)

        # Just search for a match in the array
        for match in Matches:
            data, annotation = match

            # If the last few bytes in the buffers match our target array
            if data == list(self.LastBytes)[-1 * len(data) :]:

                startSample = (
                    # Cover edge case where we match on the very first byte in the data
                    self.LastSamples[-1 * len(data)]
                    if len(self.LastSamples) >= len(data)
                    else 0
                )

                # Print the annotation at orignal start sample and the current sample
                self.put(startSample, endSample, self.out_ann, [0, [annotation]])

pulseview.png

Thanks for your quick reply Jack. I'll keep trying.

Simon