projects / apple / libc.git / blame
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1 | .\" Copyright (c) 2006 Apple Computer, Inc. All rights reserved. |
| 2 | .\" | |
| 3 | .\" @APPLE_LICENSE_HEADER_START@ | |
| 4 | .\" | |
| 5 | .\" The contents of this file constitute Original Code as defined in and | |
| 6 | .\" are subject to the Apple Public Source License Version 1.1 (the | |
| 7 | .\" "License"). You may not use this file except in compliance with the | |
| 8 | .\" License. Please obtain a copy of the License at | |
| 9 | .\" http://www.apple.com/publicsource and read it before using this file. | |
| 10 | .\" | |
| 11 | .\" This Original Code and all software distributed under the License are | |
| 12 | .\" distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER | |
| 13 | .\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, | |
| 14 | .\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| 15 | .\" FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the | |
| 16 | .\" License for the specific language governing rights and limitations | |
| 17 | .\" under the License. | |
| 18 | .\" | |
| 19 | .\" @APPLE_LICENSE_HEADER_END@ | |
| 20 | .\" | |
| 21 | .Dd April 9, 2008 | |
| 22 | .Dt POSIX_MEMALIGN 3 | |
| 23 | .Os | |
| 24 | .Sh NAME | |
| 25 | .Nm posix_memalign | |
| 26 | .Nd aligned memory allocation | |
| 27 | .Sh SYNOPSIS | |
| 28 | .In stdlib.h | |
| 29 | .Ft int | |
| 30 | .Fo posix_memalign | |
| 31 | .Fa "void **memptr" | |
| 32 | .Fa "size_t alignment" | |
| 33 | .Fa "size_t size" | |
| 34 | .Fc | |
| 35 | .Sh DESCRIPTION | |
| 36 | The | |
| 37 | .Fn posix_memalign | |
| 38 | function allocates | |
| 39 | .Fa size | |
| 40 | bytes of memory such that the allocation's base address is an exact multiple of | |
| 41 | .Fa alignment , | |
| 42 | and returns the allocation in the value pointed to by | |
| 43 | .Fa memptr . | |
| 44 | .Pp | |
| 45 | The requested | |
| 46 | .Fa alignment | |
| 47 | must be a power of 2 at least as large as | |
| 48 | .Fn sizeof "void *" . | |
| 49 | .Pp | |
| 50 | Memory that is allocated via | |
| 51 | .Fn posix_memalign | |
| 52 | can be used as an argument in subsequent calls to | |
| 53 | .Xr realloc 3 , | |
| 54 | .Xr reallocf 3 , | |
| 55 | and | |
| 56 | .Xr free 3 . | |
| 57 | (Note however, that the allocation returned by | |
| 58 | .Xr realloc 3 | |
| 59 | or | |
| 60 | .Xr reallocf 3 | |
| 61 | is not guaranteed to preserve the original | |
| 62 | .Fa alignment ) . | |
| 63 | .Sh NOTES | |
| 64 | .Fn posix_memalign | |
| 65 | should be used judiciously as the algorithm that realizes the | |
| 66 | .Fa alignment | |
| 67 | constraint can incur significant memory overhead. | |
| 68 | .Sh RETURN VALUES | |
| 69 | The | |
| 70 | .Fn posix_memalign | |
| 71 | function returns the value 0 if successful; otherwise it returns an error value. | |
| 72 | .Sh ERRORS | |
| 73 | The | |
| 74 | .Fn posix_memalign | |
| 75 | function will fail if: | |
| 76 | .Bl -tag -width Er | |
| 77 | .It Bq Er EINVAL | |
| 78 | The | |
| 79 | .Fa alignment | |
| 80 | parameter is not a power of 2 at least as large as | |
| 81 | .Fn sizeof "void *" . | |
| 82 | .It Bq Er ENOMEM | |
| 83 | Memory allocation error. | |
| 84 | .El | |
| 85 | .Sh SEE ALSO | |
| 86 | .Xr free 3 , | |
| 87 | .Xr malloc 3 , | |
| 88 | .Xr realloc 3 , | |
| 89 | .Xr reallocf 3 , | |
| 90 | .Xr valloc 3 , | |
| 91 | .Xr malloc_zone_memalign 3 | |
| 92 | .Sh STANDARDS | |
| 93 | The | |
| 94 | .Fn posix_memalign | |
| 95 | function conforms to | |
| 96 | .St -p1003.1-2001 . |