/*
     * This trick allows us to avoid having separate states for "first four ints" and "all other
     * four int chunks."  The state we want after the first four bytes is
     *
     * crc0 = ~int0
     * crc1 = int1
     * crc2 = int2
     * crc3 = int3
     *
     * ...so we set crc0 so that computeForWord(crc0) = -1 and xoring it with the first int