fromhex
u->time_low = fromhex(s , 8, &ok);
u->time_mid = fromhex(s + 9, 4, &ok);
u->time_hi_and_version = fromhex(s + 14, 4, &ok);
u->clock_seq_hi_and_reserved = fromhex(s + 19, 2, &ok);
u->clock_seq_low = fromhex(s + 21, 2, &ok);
u->node[0] = fromhex(s + 24, 2, &ok);
u->node[1] = fromhex(s + 26, 2, &ok);
u->node[2] = fromhex(s + 28, 2, &ok);
u->node[3] = fromhex(s + 30, 2, &ok);
u->node[4] = fromhex(s + 32, 2, &ok);
u->node[5] = fromhex(s + 34, 2, &ok);