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2117e02e MW |
1 | .TH datetime 3 |
2 | .SH NAME | |
3 | datetime \- convert between TAI labels and seconds | |
4 | .SH SYNTAX | |
5 | .B #include <datetime.h> | |
6 | ||
7 | void \fBdatetime_tai\fP(&\fIdt\fR,\fIt\fR); | |
8 | ||
9 | datetime_sec \fBdatetime_untai\fP(&\fIdt\fR); | |
10 | ||
11 | struct datetime \fIdt\fR; | |
12 | .br | |
13 | datetime_sec \fIt\fR; | |
14 | .SH DESCRIPTION | |
15 | International Atomic Time, TAI, | |
16 | is the fundamental unit for time measurements. | |
17 | TAI has one label for every second of real time, | |
18 | without complications such as leap seconds. | |
19 | ||
20 | A | |
21 | struct datetime | |
22 | variable, | |
23 | such as | |
24 | .IR dt , | |
25 | stores a TAI label. | |
26 | .I dt\fB.year | |
27 | is the year number minus 1900; | |
28 | .I dt\fB.mon | |
29 | is the month number, from 0 (January) through 11 (December); | |
30 | .I dt\fB.mday | |
31 | is the day of the month, from 1 through 31; | |
32 | .I dt\fB.hour | |
33 | is the hour, from 0 through 23; | |
34 | .I dt\fB.min | |
35 | is the minute, from 0 through 59; | |
36 | .I dt\fB.sec | |
37 | is the second, from 0 through 59; | |
38 | .I dt\fB.wday | |
39 | is the day of the week, from 0 (Sunday) through 6 (Saturday); | |
40 | .I dt\fB.yday | |
41 | is the day of the year, from 0 through 365. | |
42 | ||
43 | The | |
44 | .B datetime | |
45 | library supports more convenient TAI manipulation with | |
46 | the datetime_sec type. | |
47 | A datetime_sec value, such as | |
48 | .IR t , | |
49 | is an integer referring to the | |
50 | .IR t th | |
51 | second after the beginning of 1970 TAI. | |
52 | The first second of 1970 TAI was 0; | |
53 | the next second was 1; | |
54 | the last second of 1969 TAI was -1. | |
55 | The difference between two datetime_sec values is a number | |
56 | of real-time seconds. | |
57 | ||
58 | .B datetime_tai | |
59 | converts a datetime_sec to a TAI label. | |
60 | ||
61 | .B datetime_untai | |
62 | reads a TAI label | |
63 | (specifically | |
64 | .IR dt\fB.year , | |
65 | .IR dt\fB.mon , | |
66 | .IR dt\fB.mday , | |
67 | .IR dt\fB.hour , | |
68 | .IR dt\fB.min , | |
69 | and | |
70 | .IR dt\fB.sec ) | |
71 | and returns a datetime_sec. | |
72 | .SH "SEE ALSO" | |
73 | now(3) |