1 /*
2 * aligned_malloc.c - aligned memory allocation
3 *
4 * Originally public domain; changes after 2016-09-07 are copyrighted.
5 *
6 * Copyright 2016 Eric Biggers
7 *
8 * Permission is hereby granted, free of charge, to any person
9 * obtaining a copy of this software and associated documentation
10 * files (the "Software"), to deal in the Software without
11 * restriction, including without limitation the rights to use,
12 * copy, modify, merge, publish, distribute, sublicense, and/or sell
13 * copies of the Software, and to permit persons to whom the
14 * Software is furnished to do so, subject to the following
15 * conditions:
16 *
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
19 *
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
22 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
24 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
25 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
26 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
27 * OTHER DEALINGS IN THE SOFTWARE.
28 */
29
30 /*
31 * This file provides portable aligned memory allocation functions that only
32 * use malloc() and free(). This avoids portability problems with
33 * posix_memalign(), aligned_alloc(), etc.
34 */
35
36 #include <stdlib.h>
37
38 #include "aligned_malloc.h"
39
40 void *
aligned_malloc(size_t alignment,size_t size)41 aligned_malloc(size_t alignment, size_t size)
42 {
43 void *ptr = malloc(sizeof(void *) + alignment - 1 + size);
44 if (ptr) {
45 void *orig_ptr = ptr;
46 ptr = (void *)ALIGN((uintptr_t)ptr + sizeof(void *), alignment);
47 ((void **)ptr)[-1] = orig_ptr;
48 }
49 return ptr;
50 }
51
52 void
aligned_free(void * ptr)53 aligned_free(void *ptr)
54 {
55 if (ptr)
56 free(((void **)ptr)[-1]);
57 }
58