paskha.c revision 169343
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 <sys/cdefs.h> 28__FBSDID("$FreeBSD: head/usr.bin/calendar/paskha.c 169343 2007-05-07 11:18:30Z dwmalone $"); 29 30#include <stdio.h> 31#include <stdlib.h> 32#include <string.h> 33#include <time.h> 34 35#include "calendar.h" 36 37#define PASKHA "paskha" 38#define PASKHALEN (sizeof(PASKHA) - 1) 39 40static int paskha (int); 41 42/* return year day for Orthodox Easter using Gauss formula */ 43/* (old style result) */ 44 45static int 46paskha(int R) /*year*/ 47{ 48 int a, b, c, d, e; 49 static int x = 15; 50 static int y = 6; 51 52 a = R % 19; 53 b = R % 4; 54 c = R % 7; 55 d = (19*a + x) % 30; 56 e = (2*b + 4*c + 6*d + y) % 7; 57 return (((cumdays[3] + 1) + 22) + (d + e)); 58} 59 60/* return year day for Orthodox Easter depending days */ 61 62int 63getpaskha(char *s, int year) 64{ 65 int offset; 66 67 if (strncasecmp(s, PASKHA, PASKHALEN) == 0) 68 s += PASKHALEN; 69 else if ( npaskha.name != NULL 70 && strncasecmp(s, npaskha.name, npaskha.len) == 0 71 ) 72 s += npaskha.len; 73 else 74 return 0; 75 76 77 /* Paskha+1 or Paskha-2 78 * ^ ^ */ 79 80 switch(*s) { 81 82 case '-': 83 case '+': 84 offset = atoi(s); 85 break; 86 87 default: 88 offset = 0; 89 break; 90 } 91 92 return (paskha(year) + offset + 13/* new style */); 93} 94