78 lines
3.0 KiB
Groff
78 lines
3.0 KiB
Groff
.\" $NetBSD: microtime.9,v 1.6 2001/09/04 02:51:16 wiz Exp $
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.\"
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.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jeremy Cooper.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd September 14, 1998
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.Dt MICROTIME 9
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.Os
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.Sh NAME
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.Nm microtime
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.Nd realtime system clock
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.Sh SYNOPSIS
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.Fd #include <sys/time.h>
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.Ft void
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.Fo "microtime"
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.Fa "struct timeval *tv"
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.Fc
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.Sh DESCRIPTION
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.Fn microtime
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returns the current value of the system realtime clock in the structure
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pointed to by the argument
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.Fa tv .
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The system realtime clock is guaranteed to be monotonically increasing
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at all times.
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As such,
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all calls to
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.Fn microtime
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are guaranteed to return a system time greater than or equal to the
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system time returned in any previous calls.
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.Sh SEE ALSO
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\" .Xr hz 9 ,
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\" .Xr hardclock 9 ,
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.Xr inittodr 9 ,
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.Xr time 9 ,
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.Xr settimeofday 9
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.Sh CODE REFERENCES
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The implementation of the
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.Fn microtime
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function is machine dependent,
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hence its location in the source code tree varies from architecture to
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architecture.
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.Sh BUGS
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Despite the guarantee that the system realtime clock will always be
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monotonically increasing,
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it is always possible for the system clock to be manually reset by the
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system administrator to any date.
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