uint128_add64
uint128_add64(&ctr, addend);
uint128_add64(&fortuna_state.fs_counter, blockcount);
ATF_TC_WITHOUT_HEAD(uint128_add64);
ATF_TC_BODY(uint128_add64, tc)
uint128_add64(&a, tests[i].addend);
ATF_TP_ADD_TC(tp, uint128_add64);