The Open Group Base Specifications Issue 7
IEEE Std 1003.1, 2013 Edition
Copyright © 2001-2013 The IEEE and The Open Group

#### NAME

> posix_memalign - aligned memory allocation (ADVANCED REALTIME)

#### SYNOPSIS

> ``[ADV] #include <stdlib.h>
> int posix_memalign(void **`memptr`, size_t` alignment`, size_t` size`);``
> `
> `

#### DESCRIPTION

> The posix_memalign() function shall allocate size bytes aligned on a boundary specified by alignment, and shall return a pointer to the allocated memory in memptr. The value of alignment shall be a power of two multiple of sizeof(void *).

> Upon successful completion, the value pointed to by memptr shall be a multiple of alignment.

> If the size of the space requested is 0, the behavior is implementation-defined; the value returned in memptr shall be either a null pointer or a unique pointer.

> [CX] The free() function shall deallocate memory that has previously been allocated by posix_memalign().

#### RETURN VALUE

> Upon successful completion, posix_memalign() shall return zero; otherwise, an error number shall be returned to indicate the error.

#### ERRORS

> The posix_memalign() function shall fail if:

> [EINVAL]
>   The value of the alignment parameter is not a power of two multiple of sizeof(void *).
> [ENOMEM]
>   There is insufficient memory available with the requested alignment.

The following sections are informative.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> The posix_memalign() function is part of the Advisory Information option and need not be provided on all implementations.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> free, malloc

> XBD <stdlib.h>

#### CHANGE HISTORY

> First released in Issue 6. Derived from IEEE Std 1003.1d-1999.

> In the SYNOPSIS, the inclusion of <sys/types.h> is no longer required.

#### Issue 7

> Austin Group Interpretation 1003.1-2001 #058 is applied, clarifying the value of the alignment argument in the DESCRIPTION.

> Austin Group Interpretation 1003.1-2001 #152 is applied, clarifying the behavior when the size of the space requested is 0.

End of informative text.

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