Added easterog() and easteroj() which compute orthodox easter for

Gregorian and Julian Calendar.
Suggested by: Andrey

4 files changed, 55 insertions, 25 deletions

diff --git a/lib/libcalendar/Makefile b/lib/libcalendar/Makefile
index fe41148..5e2a345 100644
--- a/lib/libcalendar/Makefile
+++ b/lib/libcalendar/Makefile
@@ -1,4 +1,4 @@
-#	$Id$
+#	$Id: Makefile,v 1.1.1.1 1997/12/04 10:41:49 helbig Exp $
 
 LIB=	calendar
 
@@ -6,7 +6,7 @@ SRCS=	calendar.c easter.c
 
 MAN3=   calendar.3
 
-MLINKS=	calendar.3 easterg.3 calendar.3 easterj.3 \
+MLINKS=	calendar.3 easterg.3 calendar.3 easterog.3 calendar.3 easteroj.3 \
 	calendar.3 gdate.3 calendar.3 jdate.3 \
 	calendar.3 ndaysg.3 calendar.3 ndaysj.3 \
 	calendar.3 week.3 calendar.3 weekday.3
diff --git a/lib/libcalendar/calendar.3 b/lib/libcalendar/calendar.3
index 4f51a02..0ac6544 100644
--- a/lib/libcalendar/calendar.3
+++ b/lib/libcalendar/calendar.3
@@ -22,14 +22,15 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$Id$
+.\"	$Id: calendar.3,v 1.1.1.1 1997/12/04 10:41:49 helbig Exp $
 .\"
 .Dd November 29, 1997
 .Dt CALENDAR 3
 .Os
 .Sh NAME
 .Nm easterg ,
-.Nm easterj ,
+.Nm easterog ,
+.Nm easteroj ,
 .Nm gdate ,
 .Nm jdate ,
 .Nm ndaysg ,
@@ -42,7 +43,9 @@
 .Ft date *
 .Fn easterg "int year" "date *dt"
 .Ft date *
-.Fn easterj "int year" "date *dt"
+.Fn easterog "int year" "date *dt"
+.Ft date *
+.Fn easteroj "int year" "date *dt"
 .Ft date *
 .Fn gdate "int nd" "date *dt"
 .Ft date *
@@ -64,18 +67,28 @@ Programs should be linked with
 .Fl lcalendar .
 
 The functions
-.Fn easterg
+.Fn easterg ,
+.Fn easterog
 and
-.Fn easterj
+.Fn easteroj
 store the date of Easter Sunday into the structure pointed at by
 .Fa dt
 and return a pointer to this structure.
 The function
 .Fn easterg
 assumes Gregorian Calendar (adopted by most western churches after 1582) and
-.Fn easterj
-assumes Julian Calendar (Western churches before 1582 and Greek Church
+the functions
+.Fn easterog
+and
+.Fn easteroj
+compute the date of Easter Sunday according to the orthodox rules
+(Western churches before 1582, Greek and Russian Orthodox Church
 until today).
+The result returned by
+.Fn easterog
+is the date in Gregorian Calendar, whereas
+.Fn easteroj
+returns the date in Julian Calendar.
 
 The functions 
 .Fn gdate ,
diff --git a/lib/libcalendar/calendar.h b/lib/libcalendar/calendar.h
index 6c8d8f9..8be8d49 100644
--- a/lib/libcalendar/calendar.h
+++ b/lib/libcalendar/calendar.h
@@ -23,7 +23,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id$
+ *	$Id: calendar.h,v 1.1.1.1 1997/12/04 10:41:49 helbig Exp $
  */
 typedef struct date {
 	int y;	/* year */
@@ -32,7 +32,8 @@ typedef struct date {
 } date;
 
 date    *easterg(int _year, date *_dt);
-date    *easterj(int _year, date *_dt);
+date    *easterog(int _year, date *_dt);
+date    *easteroj(int _year, date *_dt);
 date	*gdate(int _nd,  date *_dt);
 date	*jdate(int _nd, date *_dt);
 int	 ndaysg(date *_dt);
diff --git a/lib/libcalendar/easter.c b/lib/libcalendar/easter.c
index 53021f7..fa43837 100644
--- a/lib/libcalendar/easter.c
+++ b/lib/libcalendar/easter.c
@@ -23,11 +23,13 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id$
+ *	$Id: easter.c,v 1.1.1.1 1997/12/04 10:41:49 helbig Exp $
  */
 
 #include "calendar.h"
 
+static int	 easterodn(int y);
+
 /* Compute Easter Sunday in Gregorian Calendar */
 date *
 easterg(int y, date *dt)
@@ -47,11 +49,26 @@ easterg(int y, date *dt)
 	return (dt);
 }
 
-/* Compute Easter Sunday in Julian Calendar */
+/* Compute the Gregorian date of Easter Sunday in Julian Calendar */
+date *
+easterog(int y, date *dt)
+{
+
+	return (gdate(easterodn(y), dt));
+}
+
+/* Compute the Julian date of Easter Sunday in Julian Calendar */
 date   *
-easterj(int y, date * dt)
+easteroj(int y, date * dt)
 {
 
+	return (jdate(easterodn(y), dt));
+}
+
+/* Compute the day number of Easter Sunday in Julian Calendar */
+static int
+easterodn(int y)
+{
 	/*
 	 * Table for the easter limits in one metonic (19-year) cycle. 21
 	 * to 31 is in March, 1 through 18 in April. Easter is the first
@@ -62,21 +79,20 @@ easterj(int y, date * dt)
 
 	/* Offset from a weekday to next sunday */
 	int     ns[] = {6, 5, 4, 3, 2, 1, 7};
+	date	dt;
 	int     dn;
 
-	/* Assign the easter limit of y to *dt */
-	dt->d = mc[y % 19];
+	/* Assign the easter limit of y to dt */
+	dt.d = mc[y % 19];
 
-	if (dt->d < 21)
-		dt->m = 4;
+	if (dt.d < 21)
+		dt.m = 4;
 	else
-		dt->m = 3;
-
-	dt->y = y;
+		dt.m = 3;
 
-	/* Compute the next sunday after the easter limit */
-	dn = ndaysj(dt);
-	dn += ns[weekday(dn)];
+	dt.y = y;
 
-	return (jdate(dn, dt));
+	/* Return the next sunday after the easter limit */
+	dn = ndaysj(&dt);
+	return (dn + ns[weekday(dn)]);
 }