1 files changed, 131 insertions, 0 deletions
diff --git a/usr.sbin/xntpd/lib/clocktime.c b/usr.sbin/xntpd/lib/clocktime.c
new file mode 100644
index 0000000..36b967e
--- /dev/null
+++ b/usr.sbin/xntpd/lib/clocktime.c
@@ -0,0 +1,131 @@
+/* clocktime.c,v 3.1 1993/07/06 01:08:07 jbj Exp
+ * clocktime - compute the NTP date from a day of year, hour, minute
+ *	       and second.
+ */
+#include "ntp_fp.h"
+#include "ntp_unixtime.h"
+#include "ntp_stdlib.h"
+
+/*
+ * Hacks to avoid excercising the multiplier.  I have no pride.
+ */
+#define	MULBY10(x)	(((x)<<3) + ((x)<<1))
+#define	MULBY60(x)	(((x)<<6) - ((x)<<2))	/* watch overflow */
+#define	MULBY24(x)	(((x)<<4) + ((x)<<3))
+
+/*
+ * Two days, in seconds.
+ */
+#define	TWODAYS		(2*24*60*60)
+
+/*
+ * We demand that the time be within CLOSETIME seconds of the receive
+ * time stamp.  This is about 4 hours, which hopefully should be
+ * wide enough to collect most data, while close enough to keep things
+ * from getting confused.
+ */
+#define	CLOSETIME	(4*60*60)
+
+
+int
+clocktime(yday, hour, minute, second, tzoff, rec_ui, yearstart, ts_ui)
+	int yday;
+	int hour;
+	int minute;
+	int second;
+	int tzoff;
+	U_LONG rec_ui;
+	U_LONG *yearstart;
+	U_LONG *ts_ui;
+{
+	register LONG tmp;
+	register U_LONG date;
+	register U_LONG yst;
+
+	/*
+	 * Compute the offset into the year in seconds.  Note that
+	 * this could come out to be a negative number.
+	 */
+	tmp = (LONG)(MULBY24((yday-1)) + hour + tzoff);
+	tmp = MULBY60(tmp) + (LONG)minute;
+	tmp = MULBY60(tmp) + (LONG)second;
+
+	/*
+	 * Initialize yearstart, if necessary.
+	 */
+	yst = *yearstart;
+	if (yst == 0) {
+		yst = calyearstart(rec_ui);
+		*yearstart = yst;
+	}
+
+	/*
+	 * Now the fun begins.  We demand that the received clock time
+	 * be within CLOSETIME of the receive timestamp, but
+	 * there is uncertainty about the year the timestamp is in.
+	 * Use the current year start for the first check, this should
+	 * work most of the time.
+	 */
+	date = (U_LONG)(tmp + (LONG)yst);
+	if (date < (rec_ui + CLOSETIME) &&
+	    date > (rec_ui - CLOSETIME)) {
+		*ts_ui = date;
+		return 1;
+	}
+
+	/*
+	 * Trouble.  Next check is to see if the year rolled over and, if
+	 * so, try again with the new year's start.
+	 */
+	yst = calyearstart(rec_ui);
+	if (yst != *yearstart) {
+		date = (U_LONG)((LONG)yst + tmp);
+		*ts_ui = date;
+		if (date < (rec_ui + CLOSETIME) &&
+		    date > (rec_ui - CLOSETIME)) {
+			*yearstart = yst;
+			return 1;
+		}
+	}
+
+	/*
+	 * Here we know the year start matches the current system
+	 * time.  One remaining possibility is that the time code
+	 * is in the year previous to that of the system time.  This
+	 * is only worth checking if the receive timestamp is less
+	 * than a couple of days into the new year.
+	 */
+	if ((rec_ui - yst) < TWODAYS) {
+		yst = calyearstart(yst - TWODAYS);
+		if (yst != *yearstart) {
+			date = (U_LONG)(tmp + (LONG)yst);
+			if (date < (rec_ui + CLOSETIME) &&
+			    date > (rec_ui - CLOSETIME)) {
+				*yearstart = yst;
+				*ts_ui = date;
+				return 1;
+			}
+		}
+	}
+
+	/*
+	 * One last possibility is that the time stamp is in the year
+	 * following the year the system is in.  Try this one before
+	 * giving up.
+	 */
+	yst = calyearstart(rec_ui + TWODAYS);
+	if (yst != *yearstart) {
+		date = (U_LONG)((LONG)yst + tmp);
+		if (date < (rec_ui + CLOSETIME) &&
+		    date > (rec_ui - CLOSETIME)) {
+			*yearstart = yst;
+			*ts_ui = date;
+			return 1;
+		}
+	}
+
+	/*
+	 * Give it up.
+	 */
+	return 0;
+}