in kapi.c [27:39]
static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
{
ts->nsec += offset->nsec;
while (ts->nsec >= NSEC_PER_SEC) {
ts->nsec -= NSEC_PER_SEC;
ts->sec++;
}
while (ts->nsec < 0) {
ts->nsec += NSEC_PER_SEC;
ts->sec--;
}
ts->sec += offset->sec;
}