/* $NetBSD: calleapwhen.c,v 1.1.1.1 2000/03/29 12:38:49 simonb Exp $ */ /* * calleapwhen - determine the number of seconds to the next possible * leap occurance. */ #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 */ }; u_long calleapwhen( u_long ntpdate ) { 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. */ return (u_long)(calleaptab[i] - (long)dateincycle); }