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.\"
.\" This file and its contents are supplied under the terms of the
.\" Common Development and Distribution License ("CDDL"), version 1.0.
.\" You may only use this file in accordance with the terms of version
.\" 1.0 of the CDDL.
.\"
.\" A full copy of the text of the CDDL should have accompanied this
.\" source. A copy of the CDDL is also available via the Internet at
.\" http://www.illumos.org/license/CDDL.
.\"
.\"
.\" Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
.\"
.Dd Sep 06, 2020
.Dt timespec 3HEAD
.Os
.Sh NAME
.Nm timespec ,
.Nm timeval ,
.Nm TIMESPEC_TO_TIMEVAL ,
.Nm TIMEVAL_TO_TIMESPEC
.Nd time structures and conversion
.Sh SYNOPSIS
.In sys/time.h
.Ft void
.Fo TIMESPEC_TO_TIMEVAL
.Fa "struct timeval *tv"
.Fa "const struct timespec *ts"
.Fc
.Ft void
.Fo TIMEVAL_TO_TIMESPEC
.Fa "const struct timeval *tv"
.Fa "struct timespec *ts"
.Fc
.Sh DESCRIPTION
The
.Vt timeval
and
.Vt timespec
structures are declared in the
.In time.h
and
.In sys/time.h
headers respectively:
.Bd -literal -offset indent
typedef struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* and nanoseconds */
} timespec_t;
struct timeval {
time_t tv_sec; /* seconds */
suseconds_t tv_usec; /* and microseconds */
};
.Ed
.Pp
In both cases, the
.Fa tv_sec
member represents elapsed time in whole seconds.
The
.Fa tv_nsec
and
.Fa tv_usec
members represent the rest of the elapsed time in nanoseconds and
microseconds respectively, depending on the structure.
.Pp
The
.Dv TIMEVAL_TO_TIMESPEC
macro can be used to convert a
.Vt struct timeval
structure to a
.Vt struct timespec
structure, while the
.Dv TIMESPEC_TO_TIMEVAL
macro works in the opposite direction.
.Pp
When converting from a
.Vt struct timespec
to a
.Vt struct timeval
structure, the
.Fa tv_nsec
member is truncated, losing precision.
When converting from a
.Vt struct timeval
to a
.Vt struct timespec
structure, the
.Fa tv_usec
member is multiplied by 1000 to reach the precision of the target
structure.
The
.Fa tv_sec
member is always preserved, no matter which conversion is performed.
.Pp
Note that the
.Dv TIMEVAL_TO_TIMESPEC
and
.Dv TIMESPEC_TO_TIMEVAL
macros are non-standard but are commonly found on UNIX and UNIX-like systems.
.Sh INTERFACE STABILITY
.Sy Committed
.Sh MT-LEVEL
.Sy MT-Safe
.Sh SEE ALSO
.Xr time.h 3HEAD
|
