2 * Copyright (C) 1993-1996 by Andrey A. Chernov, Moscow, Russia.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
37 #define PASKHA "paskha"
38 #define PASKHALEN (sizeof(PASKHA) - 1)
40 static int paskha(int);
42 /* return year day for Orthodox Easter using Gauss formula */
43 /* (old style result) */
46 paskha(int R) /*year*/
55 d = (19 * a + x) % 30;
56 e = (2 * b + 4 * c + 6 * d + y) % 7;
57 return (((cumdays[3] + 1) + 22) + (d + e));
60 /* return year day for Orthodox Easter depending days */
63 getpaskha(char *s, int year)
67 if (strncasecmp(s, PASKHA, PASKHALEN) == 0)
69 else if (npaskha.name != NULL
70 && strncasecmp(s, npaskha.name, npaskha.len) == 0)
75 /* Paskha+1 or Paskha-2
90 return (paskha(year) + offset + 13 /* new style */);