freebsd-dev/gnu/lib/libmalloc/memalign.c

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/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#ifndef _MALLOC_INTERNAL
#define _MALLOC_INTERNAL
#include <malloc.h>
#endif
__ptr_t
memalign (alignment, size)
size_t alignment;
size_t size;
{
__ptr_t result;
unsigned long int adj;
size = ((size + alignment - 1) / alignment) * alignment;
result = malloc (size);
if (result == NULL)
return NULL;
adj = (unsigned long int) ((unsigned long int) ((char *) result -
(char *) NULL)) % alignment;
if (adj != 0)
{
struct alignlist *l;
for (l = _aligned_blocks; l != NULL; l = l->next)
if (l->aligned == NULL)
/* This slot is free. Use it. */
break;
if (l == NULL)
{
l = (struct alignlist *) malloc (sizeof (struct alignlist));
if (l == NULL)
{
free (result);
return NULL;
}
}
l->exact = result;
result = l->aligned = (char *) result + alignment - adj;
l->next = _aligned_blocks;
_aligned_blocks = l;
}
return result;
}