1 /* 2 * Copyright (c) 1996 Wolfram Schneider <wosch@FreeBSD.org>. Berlin. 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 AND CONTRIBUTORS ``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 AUTHOR 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 * $Id: ostern.c,v 1.4 1996/05/11 20:44:20 ache Exp $ 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 /* return year day for Easter */ 37 38 int easter (year) 39 int year; /* 0 ... abcd, NOT since 1900 */ 40 { 41 42 int e_a, e_b, e_c, e_d, e_e,e_f, e_g, e_h, e_i, e_k, 43 e_l, e_m, e_n, e_p, e_q; 44 45 /* silly, but it works */ 46 e_a = year % 19; 47 e_b = year / 100; 48 e_c = year % 100; 49 50 e_d = e_b / 4; 51 e_e = e_b % 4; 52 e_f = (e_b + 8) / 25; 53 e_g = (e_b + 1 - e_f) / 3; 54 e_h = ((19 * e_a) + 15 + e_b - (e_d + e_g)) % 30; 55 e_i = e_c / 4; 56 e_k = e_c % 4; 57 e_l = (32 + 2 * e_e + 2 * e_i - (e_h + e_k)) % 7; 58 e_m = (e_a + 11 * e_h + 22 * e_l) / 451; 59 e_n = (e_h + e_l + 114 - (7 * e_m)) / 31; 60 e_p = (e_h + e_l + 114 - (7 * e_m)) % 31; 61 e_p = e_p + 1; 62 63 e_q = 31 + 28; 64 65 if (e_k == 0 && e_c != 0) 66 e_q += 1; 67 68 if (e_n == 4) 69 e_q += 31; 70 71 e_q += e_p; 72 73 #if DEBUG 74 printf("%d %d %d %d %d %d %d %d %d %d %d %d %d %d %d\n", e_a , e_b , e_c , e_d , e_e , e_f , e_g , e_h , e_i , e_k , e_l , e_m , e_n , e_p , e_q); 75 #endif 76 77 return (e_q); 78 } 79 80 /* return year day for Easter or easter depending days 81 * Match: Easter([+-][0-9]+)? 82 * e.g: Easter-2 is Good Friday (2 days before Easter) 83 */ 84 85 int 86 geteaster(s, year) 87 char *s; 88 int year; 89 { 90 register int offset = 0; 91 extern struct fixs neaster; 92 93 #define EASTER "easter" 94 #define EASTERNAMELEN (sizeof(EASTER) - 1) 95 96 if (strncasecmp(s, EASTER, EASTERNAMELEN) == 0) 97 s += EASTERNAMELEN; 98 else if ( neaster.name != NULL 99 && strncasecmp(s, neaster.name, neaster.len) == 0 100 ) 101 s += neaster.len; 102 else 103 return(0); 104 105 #if DEBUG 106 printf("%s %d %d\n", s, year, EASTERNAMELEN); 107 #endif 108 109 /* Easter+1 or Easter-2 110 * ^ ^ */ 111 112 switch(*s) { 113 114 case '-': 115 case '+': 116 offset = atoi(s); 117 break; 118 119 default: 120 offset = 0; 121 } 122 123 return (easter(year) + offset); 124 } 125