From f02f2190f064584ff838352a8ec1cc92dc191742 Mon Sep 17 00:00:00 2001
From: Willem van de Krol <008054@jfc.nl>
Date: Fri, 4 Jul 2014 22:23:52 +0200
Subject: [PATCH] fixed incorrect fday handling in dayofweek() function

---
 cal.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/cal.c b/cal.c
index 8faf3de..a477db9 100644
--- a/cal.c
+++ b/cal.c
@@ -79,15 +79,11 @@ drawcal(int year, int month, int day, int ncols, int nmons, int fday)
 static int
 dayofweek(int year, int month, int day, int fday)
 {
-	int a, y, m, d;
+	static int t[] = { 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4 };
 
-	month++;
-	a = (14 - month) / 12;
-	y = year + 4800 - a;
-	m = month + 12 * a - 3;
-	d = (day + (153 * m + 2) / 5 + 365 * y + y / 4 - y / 100 + y \
-			/ 400 - 32045 + 1) % 7;
-	return (fday > d)? (7 - d) : (d - fday);
+	day += 7 - fday;
+	year -= month < 2;
+	return (year + year / 4 - year / 100 + year / 400 + t[month] + day) % 7;
 }
 
 static bool