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Document the counting and rounding macros from <sys/param.h>.

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jruoho 2010-03-04 08:09:51 +00:00
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10
share/man/man9/Makefile
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@ -1,4 +1,4 @@
# $NetBSD: Makefile,v 1.318 2010/03/01 19:09:41 jruoho Exp $
# $NetBSD: Makefile,v 1.319 2010/03/04 08:09:51 jruoho Exp $
# Makefile for section 9 (kernel function and variable) manual pages.
@ -41,8 +41,8 @@ MAN= accept_filter.9 accf_data.9 accf_http.9 \
pcmcia.9 pcq.9 percpu.9 pfil.9 physio.9 pmap.9 pmatch.9 pmc.9 pmf.9 \
pool.9 pool_cache.9 powerhook_establish.9 ppsratecheck.9 \
preempt.9 putter.9 \
radio.9 ras.9 rasops.9 ratecheck.9 resettodr.9 rnd.9 rssadapt.9 \
rt_timer.9 rwlock.9 RUN_ONCE.9 \
radio.9 ras.9 rasops.9 ratecheck.9 resettodr.9 rnd.9 roundup.9 \
rssadapt.9 rt_timer.9 rwlock.9 RUN_ONCE.9 \
sched_4bsd.9 scsipi.9 \
secmodel.9 secmodel_bsd44.9 secmodel_overlay.9 secmodel_securelevel.9 \
secmodel_suser.9 setbit.9 setjmp.9 shutdownhook_establish.9 \
@ -577,6 +577,10 @@ MLINKS+=rasops.9 rasops_init.9 \
rasops.9 rasops_reconfig.9
MLINKS+=rnd.9 rnd_attach_source.9 rnd.9 rnd_detach_source.9 \
rnd.9 rnd_add_data.9 rnd.9 rnd_add_uint32.9
MLINKS+=roundup.9 howmany.9 \
roundup.9 rounddown.9 \
roundup.9 roundup2.9 \
roundup.9 powerof2.9
MLINKS+=rssadapt.9 ieee80211_rssadapt_choose.9 \
rssadapt.9 ieee80211_rssadapt_input.9 \
rssadapt.9 ieee80211_rssadapt_lower_rate.9 \

96
share/man/man9/roundup.9 Normal file
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.\" $NetBSD: roundup.9,v 1.1 2010/03/04 08:09:52 jruoho Exp $
.\"
.\" Copyright (c) 2010 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jukka Ruohonen.
.\"
.\" 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.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
.\"
.Dd March 4, 2010
.Dt ROUNDUP 9
.Os
.Sh NAME
.Nm roundup
.Nd macros for counting and rounding
.Sh SYNOPSIS
.In sys/param.h
.Ft size
.Fn howmany "x" "size"
.Ft size
.Fn roundup "x" "size"
.Ft size
.Fn rounddown "x" "size"
.Ft size
.Fn roundup2 "x" "size"
.Ft int
.Fn powerof2 "x"
.Sh DESCRIPTION
The
.Fn roundup
and
.Fn rounddown
macros return an integer from rounding
.Fa x
up and down, respectively, to the next
.Fa size .
The
.Fn howmany
macro in turn reveals how many times
.Fa size
fits into
.Fa x ,
rounding the residual up.
.Pp
The
.Fn roundup2
macro also rounds up, but with the assumption that
.Fa x
is a power of two.
If
.Fa x
is indeed a power of two,
.Fn powerof2
return 1.
.Sh RETURN VALUES
The return value is an integer from the respective operation.
If
.Fa x
is 0, all macros except
.Fn powerof2
return 0.
The behavior is undefined if
.Fa size
is 0.
.Sh EXAMPLES
.Bd -literal -offset indent
uint16_t rx;
\&...
/* Round up to 32-bit boundary. */
rx = roundup2(rx, sizeof(uint32_t));
.Ed
.Sh CAVEATS
All described macros make no assumptions about the type of the parameters.
These are implicitly assumed to be unsigned integers.