134 lines
3.6 KiB
Groff
134 lines
3.6 KiB
Groff
.\" $NetBSD: posix_memalign.3,v 1.7 2019/12/06 16:19:32 nros Exp $
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.\"
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.\" Copyright (C) 2006 Jason Evans <jasone@FreeBSD.org>.
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.\" All rights reserved.
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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(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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.\" 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
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" FreeBSD: src/lib/libc/stdlib/posix_memalign.3,v 1.3 2007/03/28 04:32:51 jasone Exp
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.\"
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.Dd July 27, 2018
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.Dt POSIX_MEMALIGN 3
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.Os
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.Sh NAME
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.Nm posix_memalign , aligned_alloc
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.Nd aligned memory allocation
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In stdlib.h
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.Ft int
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.Fn posix_memalign "void **ptr" "size_t alignment" "size_t size"
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.Ft void *
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.Fn aligned_alloc "size_t alignment" "size_t size"
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.Sh DESCRIPTION
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The
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.Fn posix_memalign
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function allocates
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.Fa size
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bytes of memory such that the allocation's base address is an even multiple of
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.Fa alignment ,
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and returns the allocation in the value pointed to by
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.Fa ptr .
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The requested
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.Fa alignment
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must be a power of 2 at least as large as
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.Fn sizeof "void *" .
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.Pp
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The
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.Fn aligned_alloc
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function allocates
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.Fa size
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bytes of memory such that the allocation's base address is an even multiple of
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.Fa alignment .
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The requested
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.Fa alignment
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must be a power of 2.
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.Pp
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Memory that is allocated via
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.Fn posix_memalign
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or
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.Fn aligned_alloc
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can be used as an argument in subsequent calls to
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.Xr realloc 3
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and
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.Xr free 3 .
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.Sh RETURN VALUES
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The
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.Fn posix_memalign
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function returns the value 0 if successful; otherwise it returns an error value.
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.Pp
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The
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.Fn aligned_alloc
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function returns a pointer to the allocated memory if successful; on failure it
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returns
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.Dv NULL
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and sets
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.Fa errno
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to indicate the error.
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.Sh ERRORS
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The
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.Fn posix_memalign
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and
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.Fn aligned_alloc
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functions will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa alignment
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parameter is not a power of 2.
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.It Bq Er ENOMEM
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Memory allocation error.
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.El
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.Pp
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The
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.Fn posix_memalign
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function will also fail if
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa alignment
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parameter is not at least as large as
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.Fn sizeof "void *" .
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.El
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.Sh SEE ALSO
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.Xr free 3 ,
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.Xr malloc 3 ,
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.Xr realloc 3 ,
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.Xr valloc 3
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.Sh STANDARDS
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The
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.Fn posix_memalign
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function conforms to
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.St -p1003.1-2001 .
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The
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.Fn aligned_alloc
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function conforms to
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.St -isoC-2018 .
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.Sh HISTORY
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.St -isoC-2011
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required size to be an integer multiple of alignment.
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This requirement was removed in later standards.
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