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Annotation of src/usr.bin/calendar/ostern.c, Revision 1.4

1.4     ! deraadt     1: /*     $OpenBSD: ostern.c,v 1.3 1998/12/13 07:31:08 pjanzen Exp $      */
1.1       millert     2:
                      3: /*
                      4:  * Copyright (c) 1996 Wolfram Schneider <wosch@FreeBSD.org>. Berlin.
                      5:  * All rights reserved.
                      6:  *
                      7:  * Redistribution and use in source and binary forms, with or without
                      8:  * modification, are permitted provided that the following conditions
                      9:  * are met:
                     10:  * 1. Redistributions of source code must retain the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer.
                     12:  * 2. Redistributions in binary form must reproduce the above copyright
                     13:  *    notice, this list of conditions and the following disclaimer in the
                     14:  *    documentation and/or other materials provided with the distribution.
                     15:  *
                     16:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
                     17:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     18:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     19:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
                     20:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     21:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     22:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     23:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     24:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     25:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     26:  * SUCH DAMAGE.
                     27:  *
1.4     ! deraadt    28:  *     $Id: ostern.c,v 1.3 1998/12/13 07:31:08 pjanzen Exp $
1.1       millert    29:  */
                     30:
                     31: #ifndef lint
1.4     ! deraadt    32: static char rcsid[] = "$OpenBSD: ostern.c,v 1.3 1998/12/13 07:31:08 pjanzen Exp $";
1.1       millert    33: #endif /* not lint */
                     34:
                     35: #include <stdio.h>
                     36: #include <stdlib.h>
                     37: #include <string.h>
                     38: #include <time.h>
1.3       pjanzen    39: #include <tzfile.h>
1.4     ! deraadt    40:
        !            41: #include "calendar.h"
1.1       millert    42:
                     43: /* return year day for Easter */
                     44:
                     45: int easter (year)
                     46:     int year;            /* 0 ... abcd, NOT since 1900 */
                     47: {
                     48:
                     49:     int e_a, e_b, e_c, e_d, e_e,e_f, e_g, e_h, e_i, e_k,
                     50:         e_l, e_m, e_n, e_p, e_q;
                     51:
                     52:     /* silly, but it works */
                     53:     e_a = year % 19;
                     54:     e_b = year / 100;
                     55:     e_c = year % 100;
                     56:
                     57:     e_d = e_b / 4;
                     58:     e_e = e_b % 4;
                     59:     e_f = (e_b + 8) / 25;
                     60:     e_g = (e_b + 1 - e_f) / 3;
                     61:     e_h = ((19 * e_a) + 15 + e_b - (e_d + e_g)) % 30;
                     62:     e_i = e_c / 4;
                     63:     e_k = e_c % 4;
                     64:     e_l = (32 + 2 * e_e + 2 * e_i - (e_h + e_k)) % 7;
                     65:     e_m = (e_a + 11 * e_h + 22 * e_l) / 451;
                     66:     e_n = (e_h + e_l + 114 - (7 * e_m)) / 31;
                     67:     e_p = (e_h + e_l + 114 - (7 * e_m)) % 31;
                     68:     e_p = e_p + 1;
                     69:
1.3       pjanzen    70:     e_q = 31 + 28 + e_p;
                     71:     if (isleap(year))
                     72:            e_q++;
1.1       millert    73:
                     74:     if (e_n == 4)
                     75:        e_q += 31;
                     76:
                     77: #if DEBUG
                     78:     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);
                     79: #endif
                     80:
                     81:     return (e_q);
                     82: }