103 lines
2.7 KiB
Groff
103 lines
2.7 KiB
Groff
.\" $NetBSD: roundup.9,v 1.8 2011/06/01 11:19:19 jruoho Exp $
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.\"
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.\" Copyright (c) 2010 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Jukka Ruohonen.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd June 1, 2011
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.Dt ROUNDUP 9
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.Os
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.Sh NAME
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.Nm roundup
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.Nd macros for counting and rounding
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.Sh SYNOPSIS
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.In sys/param.h
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.Ft size
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.Fn howmany "x" "size"
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.Ft size
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.Fn roundup "x" "size"
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.Ft size
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.Fn rounddown "x" "size"
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.Ft size
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.Fn roundup2 "x" "size"
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.Ft int
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.Fn powerof2 "x"
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.Sh DESCRIPTION
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The
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.Fn roundup
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and
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.Fn rounddown
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macros return an integer from rounding
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.Fa x
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up and down, respectively, to the next
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.Fa size .
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The
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.Fn howmany
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macro in turn reveals how many times
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.Fa size
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fits into
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.Fa x ,
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rounding the residual up.
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.Pp
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The
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.Fn roundup2
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macro also rounds up, but with the assumption that
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.Fa size
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is a power of two.
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If
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.Fa x
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is indeed a power of two,
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.Fn powerof2
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return 1.
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.Sh RETURN VALUES
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The return value is an integer from the respective operation.
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If
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.Fa x
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is 0, all macros except
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.Fn powerof2
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return 0.
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The behavior is undefined if
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.Fa size
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is 0.
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.Sh EXAMPLES
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The following example rounds the variable
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.Va rx
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to a 32-bit boundary:
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.Bd -literal -offset indent
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uint16_t rx;
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\&...
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rx = roundup2(rx, sizeof(uint32_t));
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.Ed
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.Sh SEE ALSO
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.Xr ilog2 3 ,
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.Xr param 3 ,
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.Xr imax 9
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.Sh CAVEATS
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All described macros make no assumptions about the type of the parameters.
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These are implicitly assumed to be unsigned integers.
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