freebsd-dev/share/man/man3/timeradd.3
Doug White e5606f14a9 Add manpage for timeradd macros and friends. A companion page for
timespecadd should be added at a future point...

PR:		13079
2002-01-14 00:38:20 +00:00

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.\" Copyright (c) 1999 Kelly Yancey <kbyanc@posi.net>
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.\" $FreeBSD$
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.Dd Aug 11, 1999
.Dt TIMERADD 3
.Os BSD 4
.Sh NAME
.Nm timeradd ,
.Nm timersub ,
.Nm timerclear ,
.Nm timerisset ,
.Nm timercmp
.Nd operations on timevals
.Sh SYNOPSIS
.Fd #include <sys/time.h>
.Fn timeradd "&tvp" "&uvp" "&vvp"
.Fn timersub "&tvp" "&uvp" "&vvp"
.Fn timerclear "&tvp"
.Fn timerisset "&tvp"
.Fn timercmp "&tvp" "&uvp" "cmp"
.Sh DESCRIPTION
.Pp
These macros are provided for manipulating
.Fa timeval
structures for use with the
.Fn gettimeofday
and
.Fn settimeofday
calls.
The structures pointed to by
.Fa tvp ,
.Fa uvp ,
and
.Fa vvp
are defined in
.Ao Pa sys/time.h Ac
as:
.Pp
.Bd -literal
struct timeval {
long tv_sec; /* seconds since Jan. 1, 1970 */
long tv_usec; /* and microseconds */
};
.Ed
.Pp
.Fn timeradd
adds the time information stored in
.Fa uvp
to
.Fa tvp
and stores the resulting
.Fa timeval
in
.Fa vvp .
The results are simplified such that the value of
.Fa vvp->tv_usec
is always less than 1,000,000 (1 second).
.Pp
.Fn timersub
subtracts the time information stored in
.Fa uvp
from
.Fa tvp
and stores the resulting
.Fa timeval
in
.Fa vvp .
.Pp
.Fn timerclear
initializes
.Fa tvp
to midnight (0 hour) January 1st, 1970 (the Epoch).
.Pp
.Fn timerisset
returns true if
.Fa tvp
is set to any time value other than the Epoch.
.Pp
.Fn timercmp
compares
.Fa tvp
to
.Fa uvp
using the comparison operator given in
.Fa cmp
and returns the result of that comparison.
.Sh SEE ALSO
.Xr gettimeofday 2
.Sh HISTORY
The
.Fn timeradd
family of macros were imported from
.Nx 1.1 ,
and appeared in
.Fx 2.2.6 .