paskha.c revision 59945
1/* 2 * Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: head/usr.bin/calendar/paskha.c 59945 2000-05-04 11:28:55Z phantom $ 27 */ 28 29#include <stdio.h> 30#include <stdlib.h> 31#include <string.h> 32#include <time.h> 33 34#include "calendar.h" 35 36#define PASKHA "paskha" 37#define PASKHALEN (sizeof(PASKHA) - 1) 38 39/* return year day for Orthodox Easter using Gauss formula */ 40/* (old style result) */ 41 42static int 43paskha (R) 44int R; /*year*/ 45{ 46 int a, b, c, d, e; 47 static int x = 15; 48 static int y = 6; 49 extern int *cumdays; 50 51 a = R % 19; 52 b = R % 4; 53 c = R % 7; 54 d = (19*a + x) % 30; 55 e = (2*b + 4*c + 6*d + y) % 7; 56 return (((cumdays[3] + 1) + 22) + (d + e)); 57} 58 59/* return year day for Orthodox Easter depending days */ 60 61int 62getpaskha(s, year) 63 char *s; 64 int year; 65{ 66 int offset; 67 extern struct fixs npaskha; 68 69 if (strncasecmp(s, PASKHA, PASKHALEN) == 0) 70 s += PASKHALEN; 71 else if ( npaskha.name != NULL 72 && strncasecmp(s, npaskha.name, npaskha.len) == 0 73 ) 74 s += npaskha.len; 75 else 76 return 0; 77 78 79 /* Paskha+1 or Paskha-2 80 * ^ ^ */ 81 82 switch(*s) { 83 84 case '-': 85 case '+': 86 offset = atoi(s); 87 break; 88 89 default: 90 offset = 0; 91 break; 92 } 93 94 return (paskha(year) + offset + 13/* new style */); 95} 96