linux/fs/ntfs/time.h
<<
>>
Prefs
   1/*
   2 * time.h - NTFS time conversion functions.  Part of the Linux-NTFS project.
   3 *
   4 * Copyright (c) 2001-2005 Anton Altaparmakov
   5 *
   6 * This program/include file is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License as published
   8 * by the Free Software Foundation; either version 2 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * This program/include file is distributed in the hope that it will be
  12 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  13 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program (in the main directory of the Linux-NTFS
  18 * distribution in the file COPYING); if not, write to the Free Software
  19 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20 */
  21
  22#ifndef _LINUX_NTFS_TIME_H
  23#define _LINUX_NTFS_TIME_H
  24
  25#include <linux/time.h>         /* For current_kernel_time(). */
  26#include <asm/div64.h>          /* For do_div(). */
  27
  28#include "endian.h"
  29
  30#define NTFS_TIME_OFFSET ((s64)(369 * 365 + 89) * 24 * 3600 * 10000000)
  31
  32/**
  33 * utc2ntfs - convert Linux UTC time to NTFS time
  34 * @ts:         Linux UTC time to convert to NTFS time
  35 *
  36 * Convert the Linux UTC time @ts to its corresponding NTFS time and return
  37 * that in little endian format.
  38 *
  39 * Linux stores time in a struct timespec consisting of a time_t (long at
  40 * present) tv_sec and a long tv_nsec where tv_sec is the number of 1-second
  41 * intervals since 1st January 1970, 00:00:00 UTC and tv_nsec is the number of
  42 * 1-nano-second intervals since the value of tv_sec.
  43 *
  44 * NTFS uses Microsoft's standard time format which is stored in a s64 and is
  45 * measured as the number of 100-nano-second intervals since 1st January 1601,
  46 * 00:00:00 UTC.
  47 */
  48static inline sle64 utc2ntfs(const struct timespec ts)
  49{
  50        /*
  51         * Convert the seconds to 100ns intervals, add the nano-seconds
  52         * converted to 100ns intervals, and then add the NTFS time offset.
  53         */
  54        return cpu_to_sle64((s64)ts.tv_sec * 10000000 + ts.tv_nsec / 100 +
  55                        NTFS_TIME_OFFSET);
  56}
  57
  58/**
  59 * get_current_ntfs_time - get the current time in little endian NTFS format
  60 *
  61 * Get the current time from the Linux kernel, convert it to its corresponding
  62 * NTFS time and return that in little endian format.
  63 */
  64static inline sle64 get_current_ntfs_time(void)
  65{
  66        return utc2ntfs(current_kernel_time());
  67}
  68
  69/**
  70 * ntfs2utc - convert NTFS time to Linux time
  71 * @time:       NTFS time (little endian) to convert to Linux UTC
  72 *
  73 * Convert the little endian NTFS time @time to its corresponding Linux UTC
  74 * time and return that in cpu format.
  75 *
  76 * Linux stores time in a struct timespec consisting of a time_t (long at
  77 * present) tv_sec and a long tv_nsec where tv_sec is the number of 1-second
  78 * intervals since 1st January 1970, 00:00:00 UTC and tv_nsec is the number of
  79 * 1-nano-second intervals since the value of tv_sec.
  80 *
  81 * NTFS uses Microsoft's standard time format which is stored in a s64 and is
  82 * measured as the number of 100 nano-second intervals since 1st January 1601,
  83 * 00:00:00 UTC.
  84 */
  85static inline struct timespec ntfs2utc(const sle64 time)
  86{
  87        struct timespec ts;
  88
  89        /* Subtract the NTFS time offset. */
  90        u64 t = (u64)(sle64_to_cpu(time) - NTFS_TIME_OFFSET);
  91        /*
  92         * Convert the time to 1-second intervals and the remainder to
  93         * 1-nano-second intervals.
  94         */
  95        ts.tv_nsec = do_div(t, 10000000) * 100;
  96        ts.tv_sec = t;
  97        return ts;
  98}
  99
 100#endif /* _LINUX_NTFS_TIME_H */
 101
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.