1.\" Copyright (C) 2006 Jason Evans <jasone@FreeBSD.org>. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as 9.\" the first lines of this file unmodified other than the possible 10.\" addition of one or more copyright notices. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice(s), this list of conditions and the following disclaimer in 13.\" the documentation and/or other materials provided with the 14.\" distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 17.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE 20.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 23.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 24.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 25.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 26.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27.\" 28.Dd May 2, 2009 29.Dt POSIX_MEMALIGN 3 30.Os 31.Sh NAME 32.Nm posix_memalign 33.Nd aligned memory allocation 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In stdlib.h 38.Ft int 39.Fn posix_memalign "void **ptr" "size_t alignment" "size_t size" 40.Sh DESCRIPTION 41The 42.Fn posix_memalign 43function allocates 44.Fa size 45bytes of memory such that the allocation's base address is an even multiple of 46.Fa alignment , 47and returns the allocation in the value pointed to by 48.Fa ptr . 49.Pp 50The requested 51.Fa alignment 52must be a power of 2 at least as large as 53.Fn sizeof "void *" . 54.Pp 55Memory that is allocated via 56.Fn posix_memalign 57can be used as an argument in subsequent calls to 58.Xr realloc 3 , 59.Xr reallocf 3 , 60and 61.Xr free 3 . 62.Sh IMPLEMENTATION NOTES 63The 64.Fn posix_memalign 65function is directly supported by matching the requested alignment against a zone 66of the slab allocator with a compatible chunking, and using the power-of-2 67shortcut whenever possible. 68Alignments beyond those supported by the zone mechanism are still 69guaranteed using cute 70.Xr mmap 2 71tricks. 72Our 73.Fn posix_memalign 74is thus able to take advantage of the slab allocator to produce 75well-fitted results when the requests are reasonable. 76.Sh RETURN VALUES 77The 78.Fn posix_memalign 79function returns the value 0 if successful; otherwise it returns an error value. 80.Sh ERRORS 81The 82.Fn posix_memalign 83function will fail if: 84.Bl -tag -width Er 85.It Bq Er EINVAL 86The 87.Fa alignment 88parameter is not a power of 2 at least as large as 89.Fn sizeof "void *" . 90.It Bq Er ENOMEM 91Memory allocation error. 92.El 93.Sh SEE ALSO 94.Xr free 3 , 95.Xr malloc 3 , 96.Xr realloc 3 , 97.Xr reallocf 3 , 98.Xr valloc 3 99.Sh STANDARDS 100The 101.Fn posix_memalign 102function conforms to 103.St -p1003.1-2008 . 104