paskha.c revision 15720
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 27#include <stdlib.h> 28#include <string.h> 29#include <stdio.h> 30 31#include "calendar.h" 32 33#define PASKHA "paskha" 34#define PASKHALEN (sizeof(PASKHA) - 1) 35 36/* return year day for Orthodox Easter using Gauss formula */ 37/* (old style result) */ 38 39static int 40paskha (R) 41int R; /*year*/ 42{ 43 int a, b, c, d, e; 44 static int x = 15; 45 static int y = 6; 46 extern int *cumdays; 47 48 a = R % 19; 49 b = R % 4; 50 c = R % 7; 51 d = (19*a + x) % 30; 52 e = (2*b + 4*c + 6*d + y) % 7; 53 return ((cumdays[2/*feb*/] + 22/*mar*/) + (d + e)); 54} 55 56/* return year day for Orthodox Easter depending days */ 57 58int 59getpaskha(s, year) 60 char *s; 61 int year; 62{ 63 int offset; 64 extern struct fixs npaskha; 65 66 if (strncasecmp(s, PASKHA, PASKHALEN) == 0) 67 s += PASKHALEN; 68 else if ( npaskha.name != NULL 69 && strncasecmp(s, npaskha.name, npaskha.len) == 0 70 ) 71 s += npaskha.len; 72 else 73 return 0; 74 75 76 /* Paskha+1 or Paskha-2 77 * ^ ^ */ 78 79 switch(*s) { 80 81 case '-': 82 case '+': 83 offset = atoi(s); 84 break; 85 86 default: 87 offset = 0; 88 break; 89 } 90 91 return (paskha(year) + offset + 13/* new style */); 92} 93