/* encrypt/decrypt columns of the key n.b. you can replace this with byte-wise xor if you wish.  */
static void add_round_key(u32 *state, u32 *key)
/* encrypt/decrypt columns of the key n.b. you can replace this with byte-wise xor if you wish.  */
static void add_round_key(u32 *state, u32 *key)
{
	int idx;
	for (idx = 0; idx < 4; idx++)
		state[idx] ^= key[idx];
}