summaryrefslogtreecommitdiffstats
path: root/misc_cmds/calendar/paskha.c
blob: 8193fb3481e7f9272661f1c4b0baad7d4c201f13 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
/*
 * Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia.
 * 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 ``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 REGENTS 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.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/usr.bin/calendar/paskha.c,v 1.8 2007/05/07 11:18:30 dwmalone Exp $");

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "calendar.h"

#define PASKHA "paskha"
#define PASKHALEN (sizeof(PASKHA) - 1)

static int paskha (int);

/* return year day for Orthodox Easter using Gauss formula */
/* (old style result) */

static int
paskha(int R) /*year*/
{
	int a, b, c, d, e;
	static int x = 15;
	static int y = 6;

	a = R % 19;
	b = R % 4;
	c = R % 7;
	d = (19*a + x) % 30;
	e = (2*b + 4*c + 6*d + y) % 7;
	return (((cumdays[3] + 1) + 22) + (d + e));
}

/* return year day for Orthodox Easter depending days */

int
getpaskha(char *s, int year)
{
	int offset;

	if (strncasecmp(s, PASKHA, PASKHALEN) == 0)
	    s += PASKHALEN;
	else if (   npaskha.name != NULL
		 && strncasecmp(s, npaskha.name, npaskha.len) == 0
		)
	    s += npaskha.len;
	else
	    return 0;


	/* Paskha+1  or Paskha-2
	 *       ^            ^   */

	switch(*s) {

	case '-':
	case '+':
	    offset = atoi(s);
	    break;

	default:
	    offset = 0;
	    break;
	}
	    
	return (paskha(year) + offset + 13/* new style */);
}