1 /*
2  * libc/stdlib/malloc/heap_alloc.c -- allocate memory from a heap
3  *
4  *  Copyright (C) 2002  NEC Corporation
5  *  Copyright (C) 2002  Miles Bader <miles@gnu.org>
6  *
7  * This file is subject to the terms and conditions of the GNU Lesser
8  * General Public License.  See the file COPYING.LIB in the main
9  * directory of this archive for more details.
10  *
11  * Written by Miles Bader <miles@gnu.org>
12  */
13 
14 #include <stdlib.h>
15 
16 #include "heap.h"
17 
18 
19 /* Allocate and return a block at least *SIZE bytes long from HEAP.
20    *SIZE is adjusted to reflect the actual amount allocated (which may be
21    greater than requested).  */
22 void *
__heap_alloc(struct heap_free_area ** heap,size_t * size)23 __heap_alloc (struct heap_free_area **heap, size_t *size)
24 {
25   struct heap_free_area *fa;
26   size_t _size = *size;
27   void *mem = 0;
28 
29   _size = HEAP_ADJUST_SIZE (_size);
30 
31   if (_size < sizeof (struct heap_free_area))
32     /* Because we sometimes must use a freed block to hold a free-area node,
33        we must make sure that every allocated block can hold one.  */
34     _size = HEAP_ADJUST_SIZE (sizeof (struct heap_free_area));
35 
36   HEAP_DEBUG (*heap, "before __heap_alloc");
37 
38   /* Look for a free area that can contain _SIZE bytes.  */
39   for (fa = *heap; fa; fa = fa->next)
40     if (fa->size >= _size)
41       {
42 	/* Found one!  */
43 	mem = HEAP_FREE_AREA_START (fa);
44 	*size = __heap_free_area_alloc (heap, fa, _size);
45 	break;
46       }
47 
48   HEAP_DEBUG (*heap, "after __heap_alloc");
49 
50   return mem;
51 }
52