[apple/libc.git] / gen / FreeBSD / clock.3

.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the American National Standards Committee X3, on Information
.\" Processing Systems.
.\"
.\" 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. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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.
.\"
.\"     @(#)clock.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: src/lib/libc/gen/clock.3,v 1.11 2001/11/20 13:43:58 ru Exp $
.\"
.Dd June 4, 1993
.Dt CLOCK 3
.Os
.Sh NAME
.Nm clock
.Nd determine processor time used
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In time.h
.Ft clock_t
.Fn clock void
.Sh DESCRIPTION
The
.Fn clock
function
determines the amount of processor time used since the invocation of the
calling process, measured in
.Dv CLOCKS_PER_SEC Ns s
of a second.
.Sh RETURN VALUES
The
.Fn clock
function returns the amount of time used unless an error occurs, in which
case the return value is \-1.
.Sh SEE ALSO
.Xr getrusage 2 ,
.Xr clocks 7
.Sh STANDARDS
The
.Fn clock
function conforms to
.St -isoC .
However,
.St -susv2
requires
.Dv CLOCKS_PER_SEC
to be defined as one million.
.Fx
does not conform to this requirement;
changing the value would introduce binary incompatibility
and one million is still inadequate on modern processors.
Commit	Line	Data
5b2abdfb	1	.\" Copyright (c) 1990, 1991, 1993
e9ce8d39 A	2	.\" The Regents of the University of California. All rights reserved.
e9ce8d39 A	3	.\"
5b2abdfb A	4	.\" This code is derived from software contributed to Berkeley by
	5	.\" the American National Standards Committee X3, on Information
	6	.\" Processing Systems.
	7	.\"
e9ce8d39 A	8	.\" Redistribution and use in source and binary forms, with or without
	9	.\" modification, are permitted provided that the following conditions
	10	.\" are met:
	11	.\" 1. Redistributions of source code must retain the above copyright
	12	.\" notice, this list of conditions and the following disclaimer.
	13	.\" 2. Redistributions in binary form must reproduce the above copyright
	14	.\" notice, this list of conditions and the following disclaimer in the
	15	.\" documentation and/or other materials provided with the distribution.
	16	.\" 3. All advertising materials mentioning features or use of this software
	17	.\" must display the following acknowledgement:
	18	.\" This product includes software developed by the University of
	19	.\" California, Berkeley and its contributors.
	20	.\" 4. Neither the name of the University nor the names of its contributors
	21	.\" may be used to endorse or promote products derived from this software
	22	.\" without specific prior written permission.
	23	.\"
	24	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	25	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	26	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	27	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	28	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	29	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	30	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	31	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	32	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	33	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	34	.\" SUCH DAMAGE.
	35	.\"
5b2abdfb	36	.\" @(#)clock.3 8.1 (Berkeley) 6/4/93
9385eb3d	37	.\" $FreeBSD: src/lib/libc/gen/clock.3,v 1.11 2001/11/20 13:43:58 ru Exp $
e9ce8d39	38	.\"
5b2abdfb A	39	.Dd June 4, 1993
5b2abdfb A	40	.Dt CLOCK 3
e9ce8d39 A	41	.Os
e9ce8d39 A	42	.Sh NAME
5b2abdfb A	43	.Nm clock
5b2abdfb A	44	.Nd determine processor time used
e9ce8d39 A	45	.Sh LIBRARY
	46	.Lb libc
	47	.Sh SYNOPSIS
5b2abdfb A	48	.In time.h
	49	.Ft clock_t
	50	.Fn clock void
e9ce8d39 A	51	.Sh DESCRIPTION
e9ce8d39 A	52	The
5b2abdfb A	53	.Fn clock
	54	function
	55	determines the amount of processor time used since the invocation of the
	56	calling process, measured in
	57	.Dv CLOCKS_PER_SEC Ns s
	58	of a second.
e9ce8d39	59	.Sh RETURN VALUES
5b2abdfb A	60	The
	61	.Fn clock
	62	function returns the amount of time used unless an error occurs, in which
	63	case the return value is \-1.
e9ce8d39	64	.Sh SEE ALSO
5b2abdfb A	65	.Xr getrusage 2 ,
	66	.Xr clocks 7
	67	.Sh STANDARDS
e9ce8d39	68	The
5b2abdfb A	69	.Fn clock
	70	function conforms to
	71	.St -isoC .
	72	However,
9385eb3d	73	.St -susv2
5b2abdfb A	74	requires
	75	.Dv CLOCKS_PER_SEC
	76	to be defined as one million.
	77	.Fx
	78	does not conform to this requirement;
	79	changing the value would introduce binary incompatibility
	80	and one million is still inadequate on modern processors.