- * @lastoctet: The last octet we got.
- * @curoctet: The current octet we're expecting (0, 1 or 2).
- * @count: The number of octets we've seen.
- * @crc24: A running CRC24 of the data we've seen.
- * @putchar_func: The function to output a character.
- * @ctx: Context for putchar_func.