posix_memalign()

Allocate aligned memory

Synopsis:

#include <stdlib.h>

int posix_memalign( void ** memptr,
                    size_t alignment,
                    size_t size );

Arguments:

memptr: A pointer to a location where posix_memalign() can store a pointer to the memory.
alignment: The alignment to use for the memory. This must be a multiple of size( void * ) that's also a power of 2.
size: The size, in bytes, of the block to allocate.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The posix_memalign() function allocates size bytes aligned on a boundary specified by alignment. It returns a pointer to the allocated memory in memptr.

The buffer allocated by posix_memalign() is contiguous in virtual address space, but not physical memory. Since some platforms don't allocate memory in 4 KB page sizes, you shouldn't assume that the memory allocated will be physically contiguous if you specify a size of 4 KB or less.

You can obtain the physical address of the start of the buffer using mem_offset() with fd=NOFD.

Returns:

0: Success.
EINVAL: The value of alignment isn't a multiple of size( void * ) that's also a power of 2, or it's greater than the value of the MALLOC_MAX_ALIGNMENT environment variable or the MALLOC_MAX_ALIGNMENT command to mallopt().
ENOMEM: There's insufficient memory available with the requested alignment.

Classification:

POSIX 1003.1 ADV

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes