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Annotation of src/usr.bin/calendar/paskha.c, Revision 1.1

1.1     ! millert     1: /*     $OpenBSD: $     */
        !             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
        !            30: static char rcsid[] = "$OpenBSD: $";
        !            31: #endif /* not lint */
        !            32:
        !            33: #include <stdio.h>
        !            34: #include <stdlib.h>
        !            35: #include <string.h>
        !            36: #include <time.h>
        !            37:
        !            38: #include "calendar.h"
        !            39:
        !            40: #define PASKHA "paskha"
        !            41: #define PASKHALEN (sizeof(PASKHA) - 1)
        !            42:
        !            43: /* return year day for Orthodox Easter using Gauss formula */
        !            44: /* (old style result) */
        !            45:
        !            46: static int
        !            47: paskha (R)
        !            48: int R;  /*year*/
        !            49: {
        !            50:        int a, b, c, d, e;
        !            51:        static int x = 15;
        !            52:        static int y = 6;
        !            53:        extern int *cumdays;
        !            54:
        !            55:        a = R % 19;
        !            56:        b = R % 4;
        !            57:        c = R % 7;
        !            58:        d = (19*a + x) % 30;
        !            59:        e = (2*b + 4*c + 6*d + y) % 7;
        !            60:        return (((cumdays[3] + 1) + 22) + (d + e));
        !            61: }
        !            62:
        !            63: /* return year day for Orthodox Easter depending days */
        !            64:
        !            65: int
        !            66: getpaskha(s, year)
        !            67:        char *s;
        !            68:         int year;
        !            69: {
        !            70:        int offset;
        !            71:        extern struct fixs npaskha;
        !            72:
        !            73:        if (strncasecmp(s, PASKHA, PASKHALEN) == 0)
        !            74:            s += PASKHALEN;
        !            75:        else if (   npaskha.name != NULL
        !            76:                 && strncasecmp(s, npaskha.name, npaskha.len) == 0
        !            77:                )
        !            78:            s += npaskha.len;
        !            79:        else
        !            80:            return 0;
        !            81:
        !            82:
        !            83:        /* Paskha+1  or Paskha-2
        !            84:         *       ^            ^   */
        !            85:
        !            86:        switch(*s) {
        !            87:
        !            88:        case '-':
        !            89:        case '+':
        !            90:            offset = atoi(s);
        !            91:            break;
        !            92:
        !            93:        default:
        !            94:            offset = 0;
        !            95:            break;
        !            96:        }
        !            97:
        !            98:        return (paskha(year) + offset + 13/* new style */);
        !            99: }