freebsd-skq/share/man/man9/microtime.9

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.\" Copyright (c) 2000 Kelly Yancey
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
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.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" $FreeBSD$
.\"
.Dd September 16, 2004
.Dt MICROTIME 9
.Os
.Sh NAME
.Nm bintime ,
.Nm getbintime ,
.Nm microtime ,
.Nm getmicrotime ,
.Nm nanotime ,
.Nm getnanotime
.Nd get the current time
.Sh SYNOPSIS
.In sys/time.h
.Ft void
.Fn bintime "struct bintime *bt"
.Ft void
.Fn getbintime "struct bintime *bt"
.Ft void
.Fn microtime "struct timeval *tv"
.Ft void
.Fn getmicrotime "struct timeval *tv"
.Ft void
.Fn nanotime "struct timespec *ts"
.Ft void
.Fn getnanotime "struct timespec *tsp"
.Sh DESCRIPTION
The
.Fn bintime
and
.Fn getbintime
functions store the system time as a
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.Vt "struct bintime"
at the addresses specified by
.Fa bt .
The
.Fn microtime
and
.Fn getmicrotime
functions perform the same utility, but record the time as a
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.Vt "struct timeval"
instead.
Similarly the
.Fn nanotime
and
.Fn getnanotime
functions store the time as a
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.Vt "struct timespec" .
.Pp
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The
.Fn bintime ,
.Fn microtime ,
and
.Fn nanotime
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functions
always query the timecounter to return the current time as precisely as
possible.
Whereas
.Fn getbintime ,
.Fn getmicrotime ,
and
.Fn getnanotime
functions are abstractions which return a less precise, but
faster to obtain, time.
.Pp
The intent of the
.Fn getbintime ,
.Fn getmicrotime ,
and
.Fn getnanotime
functions is to enforce the user's preference for timer accuracy versus
execution time.
.Sh SEE ALSO
.Xr binuptime 9 ,
.Xr getbinuptime 9 ,
.Xr getmicrouptime 9 ,
.Xr getnanouptime 9 ,
.Xr microuptime 9 ,
.Xr nanouptime 9 ,
.Xr tvtohz 9
.Sh HISTORY
The
.Nm bintime
functions first appeared in
.Fx 5.0 .
The
.Nm microtime
and
.Nm nanotime
functions first appeared in
.Fx 3.0
but have existed in other incarnations since
.Bx 4.4 .
.Sh AUTHORS
This manual page was written by
.An Kelly Yancey Aq Mt kbyanc@posi.net .