1.\" $NetBSD: microtime.9,v 1.8 2002/02/13 08:18:46 ross Exp $ 2.\" 3.\" Copyright (c) 1998 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Jeremy Cooper. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd September 14, 1998 38.Dt MICROTIME 9 39.Os 40.Sh NAME 41.Nm microtime 42.Nd realtime system clock 43.Sh SYNOPSIS 44.Fd #include \*[Lt]sys/time.h\*[Gt] 45.Ft void 46.Fo "microtime" 47.Fa "struct timeval *tv" 48.Fc 49.Sh DESCRIPTION 50.Fn microtime 51returns the current value of the system realtime clock in the structure 52pointed to by the argument 53.Fa tv . 54The system realtime clock is guaranteed to be monotonically increasing 55at all times. 56As such, 57all calls to 58.Fn microtime 59are guaranteed to return a system time greater than or equal to the 60system time returned in any previous calls. 61.Sh SEE ALSO 62.Xr settimeofday 2 , 63\" .Xr hardclock 9 , 64.Xr hz 9 , 65.Xr inittodr 9 , 66.Xr time 9 67.Sh CODE REFERENCES 68The implementation of the 69.Fn microtime 70function is machine dependent, 71hence its location in the source code tree varies from architecture to 72architecture. 73.Sh BUGS 74Despite the guarantee that the system realtime clock will always be 75monotonically increasing, 76it is always possible for the system clock to be manually reset by the 77system administrator to any date. 78