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/* $OpenBSD: paskha.c,v 1.5 2005/11/16 16:45:11 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.
*/
#ifndef lint
static const char rcsid[] = "$OpenBSD: paskha.c,v 1.5 2005/11/16 16:45:11 deraadt Exp $";
#endif /* not lint */
#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);
}
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