ostern.c revision 15737
113840Swosch/* 213840Swosch * Copyright (c) 1995 Wolfram Schneider. Public domain. 313840Swosch * 415737Sache * $Id: ostern.c,v 1.3 1996/05/10 17:32:05 ache Exp $ 513840Swosch*/ 613840Swosch 715737Sache#include <stdio.h> 815737Sache#include <stdlib.h> 913840Swosch#include <string.h> 1015737Sache#include <time.h> 1113840Swosch 1215720Sache#include "calendar.h" 1315720Sache 1413840Swosch/* return year day for Easter */ 1513840Swosch 1613840Swoschint easter (year) 1713840Swosch int year; /* 0 ... abcd, NOT since 1900 */ 1813840Swosch{ 1913840Swosch 2013840Swosch int e_a, e_b, e_c, e_d, e_e,e_f, e_g, e_h, e_i, e_k, 2113840Swosch e_l, e_m, e_n, e_p, e_q; 2213840Swosch 2313840Swosch /* silly, but it works */ 2413840Swosch e_a = year % 19; 2513840Swosch e_b = year / 100; 2613840Swosch e_c = year % 100; 2713840Swosch 2813840Swosch e_d = e_b / 4; 2913840Swosch e_e = e_b % 4; 3013840Swosch e_f = (e_b + 8) / 25; 3113840Swosch e_g = (e_b + 1 - e_f) / 3; 3213840Swosch e_h = ((19 * e_a) + 15 + e_b - (e_d + e_g)) % 30; 3313840Swosch e_i = e_c / 4; 3413840Swosch e_k = e_c % 4; 3513840Swosch e_l = (32 + 2 * e_e + 2 * e_i - (e_h + e_k)) % 7; 3613840Swosch e_m = (e_a + 11 * e_h + 22 * e_l) / 451; 3713840Swosch e_n = (e_h + e_l + 114 - (7 * e_m)) / 31; 3813840Swosch e_p = (e_h + e_l + 114 - (7 * e_m)) % 31; 3913840Swosch e_p = e_p + 1; 4013840Swosch 4113840Swosch e_q = 31 + 28; 4213840Swosch 4313840Swosch if (e_k == 0 && e_c != 0) 4413840Swosch e_q += 1; 4513840Swosch 4613840Swosch if (e_n == 4) 4713840Swosch e_q += 31; 4813840Swosch 4913840Swosch e_q += e_p; 5013840Swosch 5113840Swosch#if DEBUG 5213840Swosch 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); 5313840Swosch#endif 5413840Swosch 5513840Swosch return (e_q); 5613840Swosch} 5713840Swosch 5813840Swosch/* return year day for Easter or easter depending days 5913840Swosch * Match: Easter([+-][0-9]+)? 6013840Swosch * e.g: Easter-2 is Good Friday (2 days before Easter) 6113840Swosch */ 6213840Swosch 6313840Swoschint 6413840Swoschgeteaster(s, year) 6513840Swosch char *s; 6613840Swosch int year; 6713840Swosch{ 6813840Swosch register int offset = 0; 6915720Sache extern struct fixs neaster; 7013840Swosch 7113840Swosch#define EASTER "easter" 7213840Swosch#define EASTERNAMELEN (sizeof(EASTER) - 1) 7313840Swosch 7415720Sache if (strncasecmp(s, EASTER, EASTERNAMELEN) == 0) 7515720Sache s += EASTERNAMELEN; 7615720Sache else if ( neaster.name != NULL 7715720Sache && strncasecmp(s, neaster.name, neaster.len) == 0 7815720Sache ) 7915720Sache s += neaster.len; 8015720Sache else 8113840Swosch return(0); 8213840Swosch 8313840Swosch#if DEBUG 8413840Swosch printf("%s %d %d\n", s, year, EASTERNAMELEN); 8513840Swosch#endif 8613840Swosch 8713840Swosch /* Easter+1 or Easter-2 8813840Swosch * ^ ^ */ 8913840Swosch 9015720Sache switch(*s) { 9113840Swosch 9213840Swosch case '-': 9313840Swosch case '+': 9415720Sache offset = atoi(s); 9513840Swosch break; 9613840Swosch 9713840Swosch default: 9813840Swosch offset = 0; 9913840Swosch } 10013840Swosch 10113840Swosch return (easter(year) + offset); 10213840Swosch} 103