Annotation of src/usr.bin/calendar/paskha.c, Revision 1.5
1.5 ! deraadt 1: /* $OpenBSD: paskha.c,v 1.4 2004/12/10 15:31:01 mickey Exp $ */
1.1 millert 2:
3: /*
4: * Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia.
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 ``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 REGENTS 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: */
28:
29: #ifndef lint
1.5 ! deraadt 30: static const char rcsid[] = "$OpenBSD: paskha.c,v 1.4 2004/12/10 15:31:01 mickey Exp $";
1.1 millert 31: #endif /* not lint */
32:
33: #include <stdio.h>
1.2 pjanzen 34: #include <tzfile.h>
1.3 deraadt 35:
36: #include "calendar.h"
1.1 millert 37:
38: /* return year day for Orthodox Easter using Gauss formula */
1.2 pjanzen 39: /* (new style result); subtract 13 for old style */
1.1 millert 40:
1.2 pjanzen 41: int
1.5 ! deraadt 42: paskha(int R) /*year*/
1.1 millert 43: {
44: int a, b, c, d, e;
45: static int x = 15;
46: static int y = 6;
1.2 pjanzen 47: int cumdays;
1.1 millert 48:
49: a = R % 19;
50: b = R % 4;
51: c = R % 7;
52: d = (19*a + x) % 30;
53: e = (2*b + 4*c + 6*d + y) % 7;
1.2 pjanzen 54: cumdays = 31 + 28;
55: if (isleap(R))
56: cumdays++;
57: return ((cumdays + 22) + (d + e) + 13);
1.1 millert 58: }