struct timeval {
    union {
        long          tv_sec;         /* seconds */
        long          tv_secs;
    };
    union {
        long     tv_usec;        /* and microseconds */
        long     tv_micro;
    };
};

void timeradd(struct timeval *a, struct timeval *b, struct timeval *res) {
	res->tv_sec = a->tv_sec + b->tv_sec;
	res->tv_usec = a->tv_usec + b->tv_usec;
	if (res->tv_usec >= 1000000) {
		++res->tv_sec;
		res->tv_usec -= 1000000;
	}
}