xtime
a02x = xtime(k1);
a13x = xtime(k2);
k1 ^= (k2 ^ xtime(state[j + 1] ^ state[j + 2]));
a02xx = xtime(a02x);
a13xx = xtime(a13x);
k1 ^= (xtime(a02xx ^ a13xx) ^ a02xx);
k2 ^= (xtime(a02xx ^ a13xx) ^ a13xx);
char xtime [ISODCL (45, 61)]; /* 8.4.26.1 */
char xtime [ISODCL (45, 61)]; /* 8.4.26.1 */