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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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