freebsd-dev/share/man/man3/timeradd.3
Alan Somers 6040822c4e Make timespecadd(3) and friends public
The timespecadd(3) family of macros were imported from NetBSD back in
r35029. However, they were initially guarded by #ifdef _KERNEL. In the
meantime, we have grown at least 28 syscalls that use timespecs in some
way, leading many programs both inside and outside of the base system to
redefine those macros. It's better just to make the definitions public.

Our kernel currently defines two-argument versions of timespecadd and
timespecsub.  NetBSD, OpenBSD, and FreeDesktop.org's libbsd, however, define
three-argument versions.  Solaris also defines a three-argument version, but
only in its kernel.  This revision changes our definition to match the
common three-argument version.

Bump _FreeBSD_version due to the breaking KPI change.

Discussed with:	cem, jilles, ian, bde
Differential Revision:	https://reviews.freebsd.org/D14725
2018-07-30 15:46:40 +00:00

166 lines
4.1 KiB
Groff

.\" Copyright (c) 1999 Kelly Yancey <kbyanc@posi.net>
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.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_nsec; /* 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 .