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