YEARSHIFT
dat = (tm.tm_year - 80) << YEARSHIFT;
LE_16(year << YEARSHIFT | month << MONSHIFT | day << DAYSHIFT);
year = (LE_16(pctp->pct_date) >> YEARSHIFT) & YEARMASK;
LE_16(127 << YEARSHIFT | 12 << MONSHIFT | 31 << DAYSHIFT)