Takes 24 byte sequence to be represented in 3/4 encoding,
            returns 8 words suitable for writing "encoded" to an efuse block

def apply_34_encoding(self, inbits):
        """ Takes 24 byte sequence to be represented in 3/4 encoding,
            returns 8 words suitable for writing "encoded" to an efuse block
        """
        def popcnt(b):
            """ Return number of "1" bits set in 'b' """
            return len([x for x in bin(b) if x == "1"])

        outbits = b""
        while len(inbits) > 0:  # process in chunks of 6 bytes
            bits = inbits[0:6]
            inbits = inbits[6:]
            xor_res = 0
            mul_res = 0
            index = 1
            for b in struct.unpack("B" * 6, bits):
                xor_res ^= b
                mul_res += index * popcnt(b)
                index += 1
            outbits += bits
            outbits += struct.pack("BB", xor_res, mul_res)
        return struct.unpack("<" + "I" * (len(outbits) // 4), outbits)