ostern.c revision 15720
113840Swosch/* 213840Swosch * Copyright (c) 1995 Wolfram Schneider. Public domain. 313840Swosch * 415720Sache * $Id: ostern.c,v 1.2 1996/05/10 16:29:42 ache Exp $ 513840Swosch*/ 613840Swosch 713840Swosch#include <string.h> 815714Sache#include <stdlib.h> 915720Sache#include <stdio.h> 1013840Swosch 1115720Sache#include "calendar.h" 1215720Sache 1313840Swosch/* return year day for Easter */ 1413840Swosch 1513840Swoschint easter (year) 1613840Swosch int year; /* 0 ... abcd, NOT since 1900 */ 1713840Swosch{ 1813840Swosch 1913840Swosch int e_a, e_b, e_c, e_d, e_e,e_f, e_g, e_h, e_i, e_k, 2013840Swosch e_l, e_m, e_n, e_p, e_q; 2113840Swosch 2213840Swosch /* silly, but it works */ 2313840Swosch e_a = year % 19; 2413840Swosch e_b = year / 100; 2513840Swosch e_c = year % 100; 2613840Swosch 2713840Swosch e_d = e_b / 4; 2813840Swosch e_e = e_b % 4; 2913840Swosch e_f = (e_b + 8) / 25; 3013840Swosch e_g = (e_b + 1 - e_f) / 3; 3113840Swosch e_h = ((19 * e_a) + 15 + e_b - (e_d + e_g)) % 30; 3213840Swosch e_i = e_c / 4; 3313840Swosch e_k = e_c % 4; 3413840Swosch e_l = (32 + 2 * e_e + 2 * e_i - (e_h + e_k)) % 7; 3513840Swosch e_m = (e_a + 11 * e_h + 22 * e_l) / 451; 3613840Swosch e_n = (e_h + e_l + 114 - (7 * e_m)) / 31; 3713840Swosch e_p = (e_h + e_l + 114 - (7 * e_m)) % 31; 3813840Swosch e_p = e_p + 1; 3913840Swosch 4013840Swosch e_q = 31 + 28; 4113840Swosch 4213840Swosch if (e_k == 0 && e_c != 0) 4313840Swosch e_q += 1; 4413840Swosch 4513840Swosch if (e_n == 4) 4613840Swosch e_q += 31; 4713840Swosch 4813840Swosch e_q += e_p; 4913840Swosch 5013840Swosch#if DEBUG 5113840Swosch 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); 5213840Swosch#endif 5313840Swosch 5413840Swosch return (e_q); 5513840Swosch} 5613840Swosch 5713840Swosch/* return year day for Easter or easter depending days 5813840Swosch * Match: Easter([+-][0-9]+)? 5913840Swosch * e.g: Easter-2 is Good Friday (2 days before Easter) 6013840Swosch */ 6113840Swosch 6213840Swoschint 6313840Swoschgeteaster(s, year) 6413840Swosch char *s; 6513840Swosch int year; 6613840Swosch{ 6713840Swosch register int offset = 0; 6815720Sache extern struct fixs neaster; 6913840Swosch 7013840Swosch#define EASTER "easter" 7113840Swosch#define EASTERNAMELEN (sizeof(EASTER) - 1) 7213840Swosch 7315720Sache if (strncasecmp(s, EASTER, EASTERNAMELEN) == 0) 7415720Sache s += EASTERNAMELEN; 7515720Sache else if ( neaster.name != NULL 7615720Sache && strncasecmp(s, neaster.name, neaster.len) == 0 7715720Sache ) 7815720Sache s += neaster.len; 7915720Sache else 8013840Swosch return(0); 8113840Swosch 8213840Swosch#if DEBUG 8313840Swosch printf("%s %d %d\n", s, year, EASTERNAMELEN); 8413840Swosch#endif 8513840Swosch 8613840Swosch /* Easter+1 or Easter-2 8713840Swosch * ^ ^ */ 8813840Swosch 8915720Sache switch(*s) { 9013840Swosch 9113840Swosch case '-': 9213840Swosch case '+': 9315720Sache offset = atoi(s); 9413840Swosch break; 9513840Swosch 9613840Swosch default: 9713840Swosch offset = 0; 9813840Swosch } 9913840Swosch 10013840Swosch return (easter(year) + offset); 10113840Swosch} 102