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.\" $FreeBSD: src/lib/libc/sys/ntp_gettime.2,v 1.1.2.1 2003/04/22 17:31:18 trhodes Exp $
.\"
.Dd April 1, 2003
.Dt NTP_GETTIME 2
.Os
.Sh NAME
.Nm ntp_gettime
.Nd NTP user application interface
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/timex.h
.Ft int
.Fn ntp_gettime "struct ntptimeval *ntv"
.Sh DESCRIPTION
The time returned by
.Fn ntp_gettime
is in a
.Vt timespec
structure, but may be in either microsecond
(seconds and microseconds) or nanosecond (seconds and nanoseconds) format.
The particular format in use is determined by the
.Dv STA_NANO
bit of the status
word returned by the
.Fn ntp_adjtime
system call.
.Fn ntp_gettime
has as argument a pointer to the
.Vt ntptimeval
structure with the following members:
.Bd -literal
struct ntptimeval {
	struct timespec time;	/* current time (ns) (ro) */
	long maxerror;		/* maximum error (us) (ro) */
	long esterror;		/* estimated error (us) (ro) */
	long tai;		/* TAI offset */
	int time_state;		/* time status */
};
.Ed
.Pp
These are understood as:
.Bl -tag -width ".Va time_state"
.It Va time
Current time (read-only).
.It Va maxerror
Maximum error in microseconds (read-only).
.It Va esterror
Estimated error in microseconds (read-only).
.It Va tai
Temps Atomique International (French for International Atomic Time),
measures real time.
Used for acute time measurements.
.It Va time_state
Current time status.
.El
.Sh RETURN VALUES
.Rv -std ntp_gettime
.Pp
Possible states of the clock are:
.Pp
.Bl -tag -compact -width ".Dv TIME_ERROR"
.It Dv TIME_OK
Everything okay, no leap second warning.
.It Dv TIME_INS
Insert leap second warning.
.It Dv TIME_DEL
Delete leap second warning.
.It Dv TIME_OOP
Leap second in progress.
.It Dv TIME_WAIT
Leap second has occurred.
.It Dv TIME_ERROR
Clock not synchronized.
.El
.Sh SEE ALSO
.Xr ntp_adjtime 2 ,
.Xr ntpd 8 Pq Pa net/openntpd
.Sh AUTHORS
This manual page was written by
.An Tom Rhodes Aq Mt trhodes@FreeBSD.org .