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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* time.h - NTFS time conversion functions. Part of the Linux-NTFS project.
*
* Copyright (c) 2001-2005 Anton Altaparmakov
*/
#ifndef _LINUX_NTFS_TIME_H
#define _LINUX_NTFS_TIME_H
#include <linux/time.h> /* For current_kernel_time(). */
#include <asm/div64.h> /* For do_div(). */
#include "endian.h"
#define NTFS_TIME_OFFSET ((s64)(369 * 365 + 89) * 24 * 3600 * 10000000)
/**
* utc2ntfs - convert Linux UTC time to NTFS time
* @ts: Linux UTC time to convert to NTFS time
*
* Convert the Linux UTC time @ts to its corresponding NTFS time and return
* that in little endian format.
*
* Linux stores time in a struct timespec64 consisting of a time64_t tv_sec
* and a long tv_nsec where tv_sec is the number of 1-second intervals since
* 1st January 1970, 00:00:00 UTC and tv_nsec is the number of 1-nano-second
* intervals since the value of tv_sec.
*
* NTFS uses Microsoft's standard time format which is stored in a s64 and is
* measured as the number of 100-nano-second intervals since 1st January 1601,
* 00:00:00 UTC.
*/
static inline sle64 utc2ntfs(const struct timespec64 ts)
{
/*
* Convert the seconds to 100ns intervals, add the nano-seconds
* converted to 100ns intervals, and then add the NTFS time offset.
*/
return cpu_to_sle64((s64)ts.tv_sec * 10000000 + ts.tv_nsec / 100 +
NTFS_TIME_OFFSET);
}
/**
* get_current_ntfs_time - get the current time in little endian NTFS format
*
* Get the current time from the Linux kernel, convert it to its corresponding
* NTFS time and return that in little endian format.
*/
static inline sle64 get_current_ntfs_time(void)
{
struct timespec64 ts;
ktime_get_coarse_real_ts64(&ts);
return utc2ntfs(ts);
}
/**
* ntfs2utc - convert NTFS time to Linux time
* @time: NTFS time (little endian) to convert to Linux UTC
*
* Convert the little endian NTFS time @time to its corresponding Linux UTC
* time and return that in cpu format.
*
* Linux stores time in a struct timespec64 consisting of a time64_t tv_sec
* and a long tv_nsec where tv_sec is the number of 1-second intervals since
* 1st January 1970, 00:00:00 UTC and tv_nsec is the number of 1-nano-second
* intervals since the value of tv_sec.
*
* NTFS uses Microsoft's standard time format which is stored in a s64 and is
* measured as the number of 100 nano-second intervals since 1st January 1601,
* 00:00:00 UTC.
*/
static inline struct timespec64 ntfs2utc(const sle64 time)
{
struct timespec64 ts;
/* Subtract the NTFS time offset. */
u64 t = (u64)(sle64_to_cpu(time) - NTFS_TIME_OFFSET);
/*
* Convert the time to 1-second intervals and the remainder to
* 1-nano-second intervals.
*/
ts.tv_nsec = do_div(t, 10000000) * 100;
ts.tv_sec = t;
return ts;
}
#endif /* _LINUX_NTFS_TIME_H */
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