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.TH POSIX_MEMALIGN "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.

.SH NAME
posix_memalign
\(em aligned memory allocation
(\fBADVANCED REALTIME\fP)
.SH SYNOPSIS
.LP
.nf
#include <stdlib.h>
.P
int posix_memalign(void **\fImemptr\fP, size_t \fIalignment\fP, size_t \fIsize\fP);
.fi
.SH DESCRIPTION
The
\fIposix_memalign\fR()
function shall allocate
.IR size
bytes aligned on a boundary specified by
.IR alignment ,
and shall return a pointer to the allocated memory in
.IR memptr .
The value of
.IR alignment
shall be a power of two multiple of
.IR sizeof (\c
.BR "void *" ).
.P
Upon successful completion, the value pointed to by
.IR memptr
shall be a multiple of
.IR alignment .
.P
If the size of the space requested is 0, the behavior is
implementation-defined; the value returned in
.IR memptr
shall be either a null pointer or a unique pointer.
.P
The
\fIfree\fR()
function shall deallocate memory that has previously been allocated by
\fIposix_memalign\fR().
.SH "RETURN VALUE"
Upon successful completion,
\fIposix_memalign\fR()
shall return zero; otherwise, an error number shall be returned to
indicate the error.
.SH ERRORS
The
\fIposix_memalign\fR()
function shall fail if:
.TP
.BR EINVAL
The value of the alignment parameter is not a power of two multiple of
.IR sizeof (\c
.BR "void *" ).
.TP
.BR ENOMEM
There is insufficient memory available with the requested alignment.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
The
\fIposix_memalign\fR()
function is part of the Advisory Information option and need not be
provided on all implementations.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIfree\fR\^(\|)",
.IR "\fImalloc\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2008,
.IR "\fB<stdlib.h>\fP"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.unix.org/online.html .

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