/* $NetBSD: aligned_alloc.c,v 1.3 2024/08/18 18:47:20 riastradh Exp $ */

/*-
* Copyright (C) 2015 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Niclas Rosenvik.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice(s), this list of conditions and the following disclaimer as
*    the first lines of this file unmodified other than the possible
*    addition of one or more copyright notices.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice(s), this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__RCSID("$NetBSD: aligned_alloc.c,v 1.3 2024/08/18 18:47:20 riastradh Exp $");

#include <errno.h>
#include <stdlib.h>

void *
aligned_alloc(size_t alignment, size_t size)
{
       void *memptr;
       int err;

       /*
        * Check that alignment is a power of 2.
        */
       if (alignment == 0 || ((alignment - 1) & alignment) != 0) {
               errno = EINVAL;
               return NULL;
       }

       /*
        * Adjust alignment to satisfy posix_memalign,
        * larger alignments satisfy smaller alignments.
        */
       while (alignment < sizeof(void *)) {
               alignment <<= 1;
       }

       err = posix_memalign(&memptr, alignment, size);
       if (err) {
               errno = err;
               return NULL;
       }

       return memptr;
}