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/* $OpenBSD: ostern.c,v 1.8 2015/03/15 00:41:28 millert Exp $ */ |
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/* |
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* Copyright (c) 1996 Wolfram Schneider <wosch@FreeBSD.org>. Berlin. |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* |
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* $Id: ostern.c,v 1.8 2015/03/15 00:41:28 millert Exp $ |
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*/ |
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#include <stdio.h> |
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#include <time.h> |
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#include "calendar.h" |
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/* return year day for Easter */ |
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int |
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easter(int year) /* 0 ... abcd, NOT since 1900 */ |
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{ |
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int e_a, e_b, e_c, e_d, e_e,e_f, e_g, e_h, e_i, e_k; |
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int e_l, e_m, e_n, e_p, e_q; |
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/* silly, but it works */ |
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e_a = year % 19; |
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e_b = year / 100; |
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e_c = year % 100; |
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e_d = e_b / 4; |
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e_e = e_b % 4; |
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e_f = (e_b + 8) / 25; |
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e_g = (e_b + 1 - e_f) / 3; |
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e_h = ((19 * e_a) + 15 + e_b - (e_d + e_g)) % 30; |
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e_i = e_c / 4; |
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e_k = e_c % 4; |
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e_l = (32 + 2 * e_e + 2 * e_i - (e_h + e_k)) % 7; |
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e_m = (e_a + 11 * e_h + 22 * e_l) / 451; |
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e_n = (e_h + e_l + 114 - (7 * e_m)) / 31; |
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e_p = (e_h + e_l + 114 - (7 * e_m)) % 31; |
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e_p = e_p + 1; |
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e_q = 31 + 28 + e_p; |
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if (isleap(year)) |
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e_q++; |
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if (e_n == 4) |
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e_q += 31; |
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#if DEBUG |
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printf("%d %d %d %d %d %d %d %d %d %d %d %d %d %d %d\n", |
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e_a, e_b, e_c, e_d, e_e, e_f, e_g, e_h, |
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e_i, e_k, e_l, e_m, e_n, e_p, e_q); |
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#endif |
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return (e_q); |
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} |