diff options
Diffstat (limited to 'src/usr.bin/calendar/paskha.c')
-rw-r--r-- | src/usr.bin/calendar/paskha.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/src/usr.bin/calendar/paskha.c b/src/usr.bin/calendar/paskha.c new file mode 100644 index 0000000..fb958cd --- /dev/null +++ b/src/usr.bin/calendar/paskha.c @@ -0,0 +1,54 @@ +/* $OpenBSD: paskha.c,v 1.6 2009/10/27 23:59:36 deraadt Exp $ */ + +/* + * Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <stdio.h> +#include <tzfile.h> + +#include "calendar.h" + +/* return year day for Orthodox Easter using Gauss formula */ +/* (new style result); subtract 13 for old style */ + +int +paskha(int R) /*year*/ +{ + int a, b, c, d, e; + static int x = 15; + static int y = 6; + int cumdays; + + a = R % 19; + b = R % 4; + c = R % 7; + d = (19*a + x) % 30; + e = (2*b + 4*c + 6*d + y) % 7; + cumdays = 31 + 28; + if (isleap(R)) + cumdays++; + return ((cumdays + 22) + (d + e) + 13); +} |