120 lines
3.2 KiB
Groff
120 lines
3.2 KiB
Groff
.\" Copyright (c) 1999 Kelly Yancey <kbyanc@posi.net>
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.\" All rights reserved.
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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. Neither the name of the author nor the names of any co-contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd August 11, 1999
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.Dt TIMERADD 3
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.Os
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.Sh NAME
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.Nm timeradd ,
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.Nm timersub ,
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.Nm timerclear ,
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.Nm timerisset ,
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.Nm timercmp
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.Nd operations on timevals
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.Sh SYNOPSIS
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.In sys/time.h
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.Ft void
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.Fn timeradd "struct timeval *a" "struct timeval *b" "struct timeval *res"
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.Ft void
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.Fn timersub "struct timeval *a" "struct timeval *b" "struct timeval *res"
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.Ft void
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.Fn timerclear "struct timeval *tvp"
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.Ft int
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.Fn timerisset "struct timeval *tvp"
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.Ft int
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.Fn timercmp "struct timeval *a" "struct timeval *b" CMP
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.Sh DESCRIPTION
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These macros are provided for manipulating
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.Fa timeval
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structures for use with the
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.Xr gettimeofday 2
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and
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.Xr settimeofday 2
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calls.
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The structure is defined in
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.Aq Pa sys/time.h
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as:
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.Bd -literal
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struct timeval {
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long tv_sec; /* seconds since Jan. 1, 1970 */
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long tv_usec; /* and microseconds */
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};
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.Ed
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.Pp
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.Fn timeradd
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adds the time information stored in
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.Fa a
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to
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.Fa b
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and stores the resulting
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.Vt timeval
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in
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.Fa res .
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The results are simplified such that the value of
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.Fa res->tv_usec
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is always less than 1,000,000 (1 second).
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.Pp
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.Fn timersub
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subtracts the time information stored in
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.Fa b
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from
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.Fa a
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and stores the resulting
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.Vt timeval
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in
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.Fa res .
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.Pp
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.Fn timerclear
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initializes
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.Fa tvp
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to midnight (0 hour) January 1st, 1970 (the Epoch).
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.Pp
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.Fn timerisset
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returns true if
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.Fa tvp
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is set to any time value other than the Epoch.
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.Pp
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.Fn timercmp
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compares
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.Fa a
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to
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.Fa b
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using the comparison operator given in
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.Fa CMP ,
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and returns the result of that comparison.
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.Sh SEE ALSO
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.Xr gettimeofday 2
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.Sh HISTORY
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The
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.Fn timeradd
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family of macros were imported from
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.Nx 1.1 ,
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and appeared in
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.Fx 2.2.6 .
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