paskha.c revision 218473
1139749Simp/*- 254134Swpaul * Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia. 354134Swpaul * All rights reserved. 454134Swpaul * 554134Swpaul * Redistribution and use in source and binary forms, with or without 654134Swpaul * modification, are permitted provided that the following conditions 754134Swpaul * are met: 854134Swpaul * 1. Redistributions of source code must retain the above copyright 954134Swpaul * notice, this list of conditions and the following disclaimer. 1054134Swpaul * 2. Redistributions in binary form must reproduce the above copyright 1154134Swpaul * notice, this list of conditions and the following disclaimer in the 1254134Swpaul * documentation and/or other materials provided with the distribution. 1354134Swpaul * 1454134Swpaul * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND 1554134Swpaul * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 1654134Swpaul * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 1754134Swpaul * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 1854134Swpaul * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 1954134Swpaul * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2054134Swpaul * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2154134Swpaul * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2254134Swpaul * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2354134Swpaul * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2454134Swpaul * SUCH DAMAGE. 2554134Swpaul */ 2654134Swpaul 2754134Swpaul#include <sys/cdefs.h> 2854134Swpaul__FBSDID("$FreeBSD: head/usr.bin/calendar/paskha.c 218473 2011-02-09 06:38:32Z osa $"); 2954134Swpaul 3054134Swpaul#include <stdio.h> 3154134Swpaul#include <stdlib.h> 3254134Swpaul#include <string.h> 33119418Sobrien 34119418Sobrien#include "calendar.h" 35119418Sobrien 3654134Swpaul#define PASKHA "paskha" 3754134Swpaul#define PASKHALEN (sizeof(PASKHA) - 1) 38183505Smarius 3954134Swpaul/* return year day for Orthodox Easter using Gauss formula */ 40183505Smarius/* (new style result) */ 4154134Swpaul 4254134Swpaulint 4354134Swpaulpaskha(int R) /*year*/ 4454134Swpaul{ 4554134Swpaul int a, b, c, d, e; 4654134Swpaul static int x = 15; 4754134Swpaul static int y = 6; 4854134Swpaul int *cumday; 4954134Swpaul 5074914Sjhb a = R % 19; 5154134Swpaul b = R % 4; 5267365Sjhb c = R % 7; 5354134Swpaul d = (19 * a + x) % 30; 5454134Swpaul e = (2 * b + 4 * c + 6 * d + y) % 7; 5554134Swpaul cumday = cumdaytab[isleap(R)]; 5654134Swpaul return (((cumday[3] + 1) + 22) + (d + e) + 13); 5754134Swpaul} 5854134Swpaul