1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2019-2020 The DragonFly Project. All rights reserved.
5 *
6 * This code is derived from software contributed to The DragonFly Project
7 * by Aaron LI <aly@aaronly.me>
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 * 3. Neither the name of The DragonFly Project nor the names of its
20 * contributors may be used to endorse or promote products derived
21 * from this software without specific, prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
26 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
27 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
28 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
29 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
31 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
32 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
33 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #ifndef BASICS_H_
38 #define BASICS_H_
39
40 #include <stddef.h>
41
42 struct date {
43 int year;
44 int month;
45 int day;
46 };
47
48 static inline void
date_set(struct date * date,int y,int m,int d)49 date_set(struct date *date, int y, int m, int d)
50 {
51 date->year = y;
52 date->month = m;
53 date->day = d;
54 }
55
56 struct location {
57 double latitude; /* degree */
58 double longitude; /* degree */
59 double elevation; /* meter */
60 double zone; /* time offset (in days) from UTC */
61 };
62
63 enum dayofweek {
64 SUNDAY = 0,
65 MONDAY,
66 TUESDAY,
67 WEDNESDAY,
68 THURSDAY,
69 FRIDAY,
70 SATURDAY,
71 };
72
73 int dayofweek_from_fixed(int rd);
74 int kday_after(int dow, int rd);
75 int kday_nearest(int dow, int rd);
76 int kday_onbefore(int dow, int rd);
77 int nth_kday(int n, int dow, struct date *date);
78 int dayofyear_from_fixed(int rd);
79
80 double julian_centuries(double t);
81 double sidereal_from_moment(double t);
82
83 double ephemeris_correction(double t);
84 double universal_from_dynamical(double t);
85 double dynamical_from_universal(double t);
86
87 double equation_of_time(double t);
88 double apparent_from_local(double t, double longitude);
89 double local_from_apparent(double t, double longitude);
90
91 double obliquity(double t);
92 double declination(double t, double beta, double lambda);
93 double right_ascension(double t, double beta, double lambda);
94
95 double refraction(double elevation);
96
97 int format_time(char *buf, size_t size, double t);
98 int format_zone(char *buf, size_t size, double zone);
99 int format_location(char *buf, size_t size, const struct location *loc);
100
101 #endif
102