/* calleapwhen.c,v 3.1 1993/07/06 01:08:02 jbj Exp * calleapwhen - determine the number of seconds to the next possible * leap occurance and the last one. */ #include #include "ntp_types.h" #include "ntp_calendar.h" #include "ntp_stdlib.h" /* * calleaptab - leaps occur at the end of December and June */ LONG calleaptab[10] = { -(JAN+FEBLEAP)*SECSPERDAY, /* leap previous to cycle */ (MAR+APR+MAY+JUN)*SECSPERDAY, /* end of June */ (MAR+APR+MAY+JUN+JUL+AUG+SEP+OCT+NOV+DEC)*SECSPERDAY, /* end of Dec */ (MAR+APR+MAY+JUN)*SECSPERDAY + SECSPERYEAR, (MAR+APR+MAY+JUN+JUL+AUG+SEP+OCT+NOV+DEC)*SECSPERDAY + SECSPERYEAR, (MAR+APR+MAY+JUN)*SECSPERDAY + 2*SECSPERYEAR, (MAR+APR+MAY+JUN+JUL+AUG+SEP+OCT+NOV+DEC)*SECSPERDAY + 2*SECSPERYEAR, (MAR+APR+MAY+JUN)*SECSPERDAY + 3*SECSPERYEAR, (MAR+APR+MAY+JUN+JUL+AUG+SEP+OCT+NOV+DEC)*SECSPERDAY + 3*SECSPERYEAR, (MAR+APR+MAY+JUN+JUL+AUG+SEP+OCT+NOV+DEC+JAN+FEBLEAP+MAR+APR+MAY+JUN) *SECSPERDAY + 3*SECSPERYEAR, /* next after current cycle */ }; void calleapwhen(ntpdate, leaplast, leapnext) U_LONG ntpdate; U_LONG *leaplast; U_LONG *leapnext; { register U_LONG dateincycle; register int i; /* * Find the offset from the start of the cycle */ dateincycle = ntpdate; if (dateincycle >= MAR1988) dateincycle -= MAR1988; else dateincycle -= MAR1900; while (dateincycle >= SECSPERCYCLE) dateincycle -= SECSPERCYCLE; /* * Find where we are with respect to the leap events. */ for (i = 1; i < 9; i++) if (dateincycle < (U_LONG)calleaptab[i]) break; /* * i points at the next leap. Compute the last and the next. */ *leaplast = (U_LONG)((LONG)dateincycle - calleaptab[i-1]); *leapnext = (U_LONG)(calleaptab[i] - (LONG)dateincycle); }