}

	// put operator for two zero bits in even
	gf2MatrixSquare(even, odd)

	// put operator for four zero bits in odd
	gf2MatrixSquare(odd, even)

	// apply len2 zeros to crc1 (first square will put the operator for one
	// zero byte, eight zero bits, in even)
	crc1n := uint64(crc1)
	for {
		// apply zeros operator for this bit of len2
		gf2MatrixSquare(even, odd)
		if len2&1 != 0 {