1 files changed, 115 insertions, 0 deletions
diff --git a/contrib/ntp/libntp/caljulian.c b/contrib/ntp/libntp/caljulian.c
new file mode 100644
index 000000000000..948bb1c57dd8
--- /dev/null
+++ b/contrib/ntp/libntp/caljulian.c
@@ -0,0 +1,115 @@
+/*
+ * caljulian - determine the Julian date from an NTP time.
+ */
+#include <sys/types.h>
+
+#include "ntp_types.h"
+#include "ntp_calendar.h"
+#include "ntp_stdlib.h"
+
+/*
+ * calmonthtab - days-in-the-month table
+ */
+static u_short calmonthtab[11] = {
+	JAN,
+	FEB,
+	MAR,
+	APR,
+	MAY,
+	JUN,
+	JUL,
+	AUG,
+	SEP,
+	OCT,
+	NOV
+};
+
+void
+caljulian(
+	u_long		  		ntptime,
+	register struct calendar	*jt
+	)
+{
+	u_long ntp_day;
+	u_long minutes;
+	/*
+	 * Absolute, zero-adjusted Christian era day, starting from the
+	 * mythical day 12/1/1 BC
+	 */
+	u_long acez_day;
+
+	u_long d400;				 /* Days into a Gregorian cycle */
+	u_long d100;				 /* Days into a normal century */
+	u_long d4;					 /* Days into a 4-year cycle */
+	u_long n400;				 /* # of Gregorian cycles */
+	u_long n100;				 /* # of normal centuries */
+	u_long n4;					 /* # of 4-year cycles */
+	u_long n1;					 /* # of years into a leap year */
+						 /*   cycle */
+
+	/*
+	 * Do the easy stuff first: take care of hh:mm:ss, ignoring leap
+	 * seconds
+	 */
+	jt->second = (u_char)(ntptime % SECSPERMIN);
+	minutes    = ntptime / SECSPERMIN;
+	jt->minute = (u_char)(minutes % MINSPERHR);
+	jt->hour   = (u_char)((minutes / MINSPERHR) % HRSPERDAY);
+
+	/*
+	 * Find the day past 1900/01/01 00:00 UTC
+	 */
+	ntp_day = ntptime / SECSPERDAY;
+	acez_day = DAY_NTP_STARTS + ntp_day - 1;
+	n400	 = acez_day/GREGORIAN_CYCLE_DAYS;
+	d400	 = acez_day%GREGORIAN_CYCLE_DAYS;
+	n100	 = d400 / GREGORIAN_NORMAL_CENTURY_DAYS;
+	d100	 = d400 % GREGORIAN_NORMAL_CENTURY_DAYS;
+	n4		 = d100 / GREGORIAN_NORMAL_LEAP_CYCLE_DAYS;
+	d4		 = d100 % GREGORIAN_NORMAL_LEAP_CYCLE_DAYS;
+	n1		 = d4 / DAYSPERYEAR;
+
+	/*
+	 * Calculate the year and year-of-day
+	 */
+	jt->yearday = (u_short)(1 + d4%DAYSPERYEAR);
+	jt->year	= (u_short)(400*n400 + 100*n100 + n4*4 + n1);
+
+	if (n100 == 4 || n1 == 4)
+	{
+	/*
+	 * If the cycle year ever comes out to 4, it must be December 31st
+	 * of a leap year.
+	 */
+	jt->month	 = 12;
+	jt->monthday = 31;
+	jt->yearday  = 366;
+	}
+	else
+	{
+	/*
+	 * Else, search forwards through the months to get the right month
+	 * and date.
+	 */
+	int monthday;
+
+	jt->year++;
+	monthday = jt->yearday;
+
+	for (jt->month=0;jt->month<11; jt->month++)
+	{
+		int t;
+
+		t = monthday - calmonthtab[jt->month];
+		if (jt->month == 1 && is_leapyear(jt->year))
+		t--;
+
+		if (t > 0)
+		monthday = t;
+		else
+		break;
+	}
+	jt->month++;
+	jt->monthday = monthday;
+	}
+}