POSIX_MEMALIGN(3) BSD Library Functions Manual POSIX_MEMALIGN(3)NAMEposix_memalign — aligned memory allocation
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <stdlib.h>
int
posix_memalign(void **ptr, size_t alignment, size_t size);
DESCRIPTION
The posix_memalign() function allocates size bytes of memory such that
the allocation's base address is an even multiple of alignment, and
returns the allocation in the value pointed to by ptr.
The requested alignment must be a power of 2 at least as large as
sizeof(void *).
Memory that is allocated via posix_memalign() can be used as an argument
in subsequent calls to realloc(3), reallocf(3), and free(3).
IMPLEMENTATION NOTES
The posix_memalign() function is directly supported by matching the
requested alignment against a zone of the slab allocator with a compati‐
ble chunking, and using the power-of-2 shortcut whenever possible.
Alignments beyond those supported by the zone mechanism are still guaran‐
teed using cute mmap(2) tricks. Our posix_memalign() is thus able to
take advantage of the slab allocator to produce well-fitted results when
the requests are reasonable.
RETURN VALUES
The posix_memalign() function returns the value 0 if successful; other‐
wise it returns an error value.
ERRORS
The posix_memalign() function will fail if:
[EINVAL] The alignment parameter is not a power of 2 at least
as large as sizeof(void *).
[ENOMEM] Memory allocation error.
SEE ALSOfree(3), malloc(3), realloc(3), reallocf(3), valloc(3)STANDARDS
The posix_memalign() function conforms to IEEE Std 1003.1-2008
(“POSIX.1”).
BSD May 2, 2009 BSD
