DC_SPY
service_seconds = (service_years * DC_SPY) +
full_years = (tdiff / DC_SPY);
within_year = (tdiff % DC_SPY);
(((uint64_t)cycles_diff * (uint64_t)within_year) / DC_SPY);
when_allowed = service_seconds + (full_years * DC_SPY) +
(((uint64_t)DC_SPY * (uint64_t)cycles_over) / cycles_diff);