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.\" Copyright (C) 2006 Jason Evans <jasone@FreeBSD.org>.
.\" All rights reserved.
.\"
.\" 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(s), this list of conditions and the following disclaimer as
.\" the first lines of this file unmodified other than the possible
.\" addition of one or more copyright notices.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice(s), 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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.
.\"
.\" $FreeBSD$
.\"
.Dd January 7, 2011
.Dt ALIGNED_ALLOC 3
.Os
.Sh NAME
.Nm aligned_alloc ,
.Nm posix_memalign
.Nd aligned memory allocation
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft void *
.Fn aligned_alloc "size_t alignment" "size_t size"
.Ft int
.Fn posix_memalign "void **ptr" "size_t alignment" "size_t size"
.Sh DESCRIPTION
The
.Fn aligned_alloc
and
.Fn posix_memalign
functions allocate
.Fa size
bytes of memory such that the allocation's base address is an even multiple of
.Fa alignment .
The
.Fn aligned_alloc
function returns the allocation, while the
.Fn posix_memalign
function stores the allocation in the value pointed to by
.Fa ptr .
.Pp
The requested
.Fa alignment
must be a power of 2 at least as large as
.Fn sizeof "void *" .
.Pp
Memory that is allocated via
.Fn aligned_alloc
and
.Fn posix_memalign
can be used as an argument in subsequent calls to
.Xr realloc 3 ,
.Xr reallocf 3 ,
and
.Xr free 3 .
.Sh RETURN VALUES
The
.Fn aligned_alloc
function returns a pointer to the allocation if successful; otherwise a
NULL pointer is returned and
.Va errno
is set to an error value.
.Pp
The
.Fn posix_memalign
function returns the value 0 if successful; otherwise it returns an error value.
.Sh ERRORS
The
.Fn aligned_alloc
and
.Fn posix_memalign
functions will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa alignment
parameter is not a power of 2 at least as large as
.Fn sizeof "void *" .
.It Bq Er ENOMEM
Memory allocation error.
.El
.Sh SEE ALSO
.Xr free 3 ,
.Xr malloc 3 ,
.Xr realloc 3 ,
.Xr reallocf 3 ,
.Xr valloc 3
.Sh STANDARDS
The
.Fn aligned_alloc
function conforms to
.St -isoC-2011 .
.Pp
The
.Fn posix_memalign
function conforms to
.St -p1003.1-2001 .
.Sh HISTORY
The
.Fn posix_memalign
function first appeared in
.Fx 7.0 .
.Pp
The
.Fn aligned_alloc
function first appeared in
.Fx 10.0 .
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