diff options
Diffstat (limited to 'src/usr.bin/calendar/ostern.c')
| -rw-r--r-- | src/usr.bin/calendar/ostern.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/src/usr.bin/calendar/ostern.c b/src/usr.bin/calendar/ostern.c new file mode 100644 index 0000000..c86c577 --- /dev/null +++ b/src/usr.bin/calendar/ostern.c @@ -0,0 +1,77 @@ +/* $OpenBSD: ostern.c,v 1.7 2009/10/27 23:59:36 deraadt Exp $ */ + +/* + * Copyright (c) 1996 Wolfram Schneider <wosch@FreeBSD.org>. Berlin. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $Id: ostern.c,v 1.7 2009/10/27 23:59:36 deraadt Exp $ + */ + +#include <stdio.h> +#include <time.h> +#include <tzfile.h> + +#include "calendar.h" + +/* return year day for Easter */ + +int +easter(int year) /* 0 ... abcd, NOT since 1900 */ +{ + int e_a, e_b, e_c, e_d, e_e,e_f, e_g, e_h, e_i, e_k; + int e_l, e_m, e_n, e_p, e_q; + + /* silly, but it works */ + e_a = year % 19; + e_b = year / 100; + e_c = year % 100; + + e_d = e_b / 4; + e_e = e_b % 4; + e_f = (e_b + 8) / 25; + e_g = (e_b + 1 - e_f) / 3; + e_h = ((19 * e_a) + 15 + e_b - (e_d + e_g)) % 30; + e_i = e_c / 4; + e_k = e_c % 4; + e_l = (32 + 2 * e_e + 2 * e_i - (e_h + e_k)) % 7; + e_m = (e_a + 11 * e_h + 22 * e_l) / 451; + e_n = (e_h + e_l + 114 - (7 * e_m)) / 31; + e_p = (e_h + e_l + 114 - (7 * e_m)) % 31; + e_p = e_p + 1; + + e_q = 31 + 28 + e_p; + if (isleap(year)) + e_q++; + + if (e_n == 4) + e_q += 31; + +#if DEBUG + 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); +#endif + + return (e_q); +} |