1 /*
2 * Copyright (c) 2012-2014 Christian Hansen <chansen@cpan.org>
3 * <https://github.com/chansen/c-dt>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright notice, this
10 * list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
19 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
20 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
21 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
22 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
24 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26 #include "dt_core.h"
27
28 bool
dt_leap_year(int y)29 dt_leap_year(int y) {
30 return ((y & 3) == 0 && (y % 100 != 0 || y % 400 == 0));
31 }
32
33 int
dt_days_in_year(int y)34 dt_days_in_year(int y) {
35 return dt_leap_year(y) ? 366 : 365;
36 }
37
38 int
dt_days_in_quarter(int y,int q)39 dt_days_in_quarter(int y, int q) {
40 static const int days_in_quarter[2][5] = {
41 { 0, 90, 91, 92, 92 },
42 { 0, 91, 91, 92, 92 }
43 };
44 if (q < 1 || q > 4)
45 return 0;
46 return days_in_quarter[dt_leap_year(y)][q];
47 }
48
49 int
dt_days_in_month(int y,int m)50 dt_days_in_month(int y, int m) {
51 static const int days_in_month[2][13] = {
52 { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
53 { 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
54 };
55 if (m < 1 || m > 12)
56 return 0;
57 return days_in_month[dt_leap_year(y)][m];
58 }
59
60 int
dt_weeks_in_year(int year)61 dt_weeks_in_year(int year) {
62 unsigned int y, d;
63 if (year < 1)
64 year += 400 * (1 - year/400);
65 y = year - 1;
66 d = (y + y/4 - y/100 + y/400) % 7; /* Mon = 0, ... Sun = 6 */
67 return (d == 3 || (d == 2 && dt_leap_year(year))) ? 53 : 52;
68 }
69
70