1/*
2 * ntfstime.h - NTFS time related functions.  Originated from the Linux-NTFS project.
3 *
4 * Copyright (c) 2005 Anton Altaparmakov
5 * Copyright (c) 2005 Yura Pakhuchiy
6 *
7 * This program/include file is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as published
9 * by the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program/include file is distributed in the hope that it will be
13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program (in the main directory of the NTFS-3G
19 * distribution in the file COPYING); if not, write to the Free Software
20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
21 */
22
23#ifndef _NTFS_NTFSTIME_H
24#define _NTFS_NTFSTIME_H
25
26#ifdef HAVE_TIME_H
27#include <time.h>
28#endif
29
30#include "types.h"
31
32#define NTFS_TIME_OFFSET ((s64)(369 * 365 + 89) * 24 * 3600 * 10000000)
33
34/**
35 * ntfs2utc - Convert an NTFS time to Unix time
36 * @ntfs_time:  An NTFS time in 100ns units since 1601
37 *
38 * NTFS stores times as the number of 100ns intervals since January 1st 1601 at
39 * 00:00 UTC.  This system will not suffer from Y2K problems until ~57000AD.
40 *
41 * Return:  n  A Unix time (number of seconds since 1970)
42 */
43static __inline__ time_t ntfs2utc(s64 ntfs_time)
44{
45	return (sle64_to_cpu(ntfs_time) - (NTFS_TIME_OFFSET)) / 10000000;
46}
47
48/**
49 * utc2ntfs - Convert Linux time to NTFS time
50 * @utc_time:  Linux time to convert to NTFS
51 *
52 * Convert the Linux time @utc_time to its corresponding NTFS time.
53 *
54 * Linux stores time in a long at present and measures it as the number of
55 * 1-second intervals since 1st January 1970, 00:00:00 UTC.
56 *
57 * NTFS uses Microsoft's standard time format which is stored in a s64 and is
58 * measured as the number of 100 nano-second intervals since 1st January 1601,
59 * 00:00:00 UTC.
60 *
61 * Return:  n  An NTFS time (100ns units since Jan 1601)
62 */
63static __inline__ s64 utc2ntfs(time_t utc_time)
64{
65	/* Convert to 100ns intervals and then add the NTFS time offset. */
66	return cpu_to_sle64((s64)utc_time * 10000000 + NTFS_TIME_OFFSET);
67}
68
69#endif /* _NTFS_NTFSTIME_H */
70