Wireshark  4.3.0
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epochs.h
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1 
12 #ifndef __EPOCHS_H__
13 #define __EPOCHS_H__
14 
15 #include <glib.h>
16 
17 /*
18  * Deltas between the epochs for various non-UN*X time stamp formats and
19  * the January 1, 1970, 00:00:00 (proleptic?) UTC epoch for the UN*X time
20  * stamp format.
21  */
22 
23 /*
24  * 1900-01-01 00:00:00 (proleptic?) UTC.
25  * Used by a number of time formats.
26  */
27 #define EPOCH_DELTA_1900_01_01_00_00_00_UTC 2208988800U
28 
29 /*
30  * 1904-01-01 00:00:00 (proleptic?) UTC.
31  * Used in the classic Mac OS, and by formats, such as MPEG-4 Part 14 (MP4),
32  * which is based on Apple's QuickTime format.
33  */
34 #define EPOCH_DELTA_1904_01_01_00_00_00_UTC 2082844800U
35 
36 /*
37  * 1601-01-01 (proleptic Gregorian) 00:00:00 (proleptic?) UTC.
38  * The Windows NT epoch, used in a number of places, as it is
39  * the start of a 400 year Gregorian cycle.
40  *
41  * This is
42  *
43  * 369*365.25*24*60*60-(3*24*60*60+6*60*60)
44  *
45  * or equivalently,
46  *
47  * (89*4*365.25+(3*4+1)*365)*24*60*60
48  *
49  * 1970-1601 is 369; 365.25 is the average length of a year in days,
50  * including leap years.
51  *
52  * 369 = 4*92 + 1, so there are 92 groups of 4 consecutive years plus
53  * one leftover year, 1969, with 365 days.
54  *
55  * All but three of the groups of 4 consecutive years average 365.25 days
56  * per year, as they have one leap year in the group. However, 1700, 1800,
57  * and 1900 were not leap years, as, while they're all evenly divisible by 4,
58  * they're also evenly divisible by 100, but not evenly divisible by 400.
59  *
60  * So we have 89 groups of 4 consecutive years that average 365.25
61  * days per year, 3 groups of 4 consecutive years that average 365 days
62  * (as they lack a leap year), and one leftover year, 1969, that is
63  * 365 days long.
64  */
65 #define EPOCH_DELTA_1601_01_01_00_00_00_UTC UINT64_C(11644473600)
66 
67 /*
68  * 2000-01-01 00:00:00 UTC.
69  * Used by the Zigbee Zigbee Cluster Library protocol.
70  */
71 #define EPOCH_DELTA_2000_01_01_00_00_00_UTC ((unsigned)(((3*365 + 366)*7 + 2*365)*24*3600))
72 
73 #endif /* __EPOCHS_H__ */