tvsub(register struct timeval *out, register struct timeval *in)
{
    if((out->tv_usec -= in->tv_usec) < 0) {
        out->tv_sec--;
        out->tv_usec += 1000000;
    }
    out->tv_sec -= in->tv_sec;
}
tvsub(register struct timeval *out, register struct timeval *in)
{
    if((out->tv_usec -= in->tv_usec) < 0) {
        out->tv_sec--;
        out->tv_usec += 1000000;
    }
    out->tv_sec -= in->tv_sec;
}