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.\" Copyright (c) 1999 Kelly Yancey <kbyanc@posi.net>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 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
.\" documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the author nor the names of any co-contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd July 30, 2018
.Dt TIMERADD 3
.Os
.Sh NAME
.Nm timeradd ,
.Nm timersub ,
.Nm timerclear ,
.Nm timerisset ,
.Nm timercmp ,
.Nm timespecadd ,
.Nm timespecsub ,
.Nm timespecclear ,
.Nm timespecisset ,
.Nm timespeccmp
.Nd operations on timevals and timespecs
.Sh SYNOPSIS
.In sys/time.h
.Ft void
.Fn timeradd "struct timeval *a" "struct timeval *b" "struct timeval *res"
.Ft void
.Fn timersub "struct timeval *a" "struct timeval *b" "struct timeval *res"
.Ft void
.Fn timerclear "struct timeval *tvp"
.Ft int
.Fn timerisset "struct timeval *tvp"
.Ft int
.Fn timercmp "struct timeval *a" "struct timeval *b" CMP
.Ft void
.Fn timespecadd "struct timespec *a" "struct timespec *b" "struct timespec *res"
.Ft void
.Fn timespecsub "struct timespec *a" "struct timespec *b" "struct timespec *res"
.Ft void
.Fn timespecclear "struct timespec *ts"
.Ft int
.Fn timespecisset "struct timespec *ts"
.Ft int
.Fn timespeccmp "struct timespec *a" "struct timespec *b" CMP
.Sh DESCRIPTION
These macros are provided for manipulating
.Fa timeval
and
.Fa timespec
structures for use with the
.Xr clock_gettime 2 ,
.Xr clock_settime 2 ,
.Xr gettimeofday 2
and
.Xr settimeofday 2
calls.
The
.Fa timeval
structure is defined in
.In sys/time.h
as:
.Bd -literal
struct timeval {
long tv_sec; /* seconds since Jan. 1, 1970 */
long tv_usec; /* and microseconds */
};
.Ed
And the
.Fa timespec
structure is defined in
.In time.h
as:
.Bd -literal
struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* and nanoseconds */
};
.Ed
.Pp
.Fn timeradd
and
.Fn timespecadd
add the time information stored in
.Fa a
to
.Fa b
and store the result in
.Fa res .
The results are simplified such that the value of
.Fa res->tv_usec
or
.Fa res->tv_nsec
is always less than 1 second.
.Pp
.Fn timersub
and
.Fn timespecsub
subtract the time information stored in
.Fa b
from
.Fa a
and store the result
in
.Fa res .
.Pp
.Fn timerclear
and
.Fn timespecclear
initialize their argument to midnight (0 hour) January 1st, 1970 (the Epoch).
.Pp
.Fn timerisset
and
.Fn timespecisset
return true if their argument is set to any time value other than the Epoch.
.Pp
.Fn timercmp
and
.Fn timespeccmp
compare
.Fa a
to
.Fa b
using the comparison operator given in
.Fa CMP ,
and return the result of that comparison.
.Sh SEE ALSO
.Xr gettimeofday 2 ,
.Xr clock_gettime 2
.Sh HISTORY
The
.Fn timeradd
family of macros were imported from
.Nx 1.1 ,
and appeared in
.Fx 2.2.6 .
The
.Fn timespecadd
family of macros were imported from
.Nx 1.3
into
.Fx 3.0 ,
though they were not exposed to userland until
.Fx 12.0 .
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