1 /*****************************************************************************/
5 /* Change the size of an allocated memory block */
9 /* (C) 1998-2004 Ullrich von Bassewitz */
11 /* D-70597 Stuttgart */
12 /* EMail: uz@musoftware.de */
15 /* This software is provided 'as-is', without any expressed or implied */
16 /* warranty. In no event will the authors be held liable for any damages */
17 /* arising from the use of this software. */
19 /* Permission is granted to anyone to use this software for any purpose, */
20 /* including commercial applications, and to alter it and redistribute it */
21 /* freely, subject to the following restrictions: */
23 /* 1. The origin of this software must not be misrepresented; you must not */
24 /* claim that you wrote the original software. If you use this software */
25 /* in a product, an acknowledgment in the product documentation would be */
26 /* appreciated but is not required. */
27 /* 2. Altered source versions must be plainly marked as such, and must not */
28 /* be misrepresented as being the original software. */
29 /* 3. This notice may not be removed or altered from any source */
32 /*****************************************************************************/
42 void* __fastcall__ realloc (void* block, size_t size)
45 struct usedblock* newblock;
50 /* Check the block parameter */
52 /* Block is NULL, same as malloc */
56 /* Check the size parameter */
58 /* Block is not NULL, but size is: free the block */
63 /* Make the internal used size from the given size */
64 size += HEAP_ADMIN_SPACE;
65 if (size < sizeof (struct freeblock)) {
66 size = sizeof (struct freeblock);
69 /* The word below the user block contains a pointer to the start of the
70 * raw memory block. The first word of this raw memory block is the full
71 * size of the block. Get a pointer to the real block, get the old block
74 b = (((struct usedblock*) block) - 1)->start;
77 /* Get the size difference as a signed quantity */
78 diff = size - oldsize;
80 /* Is the block at the current heap top? */
81 if (((unsigned) b) + oldsize == ((unsigned) _heapptr)) {
82 /* Check if we've enough memory at the heap top */
83 newhptr = ((unsigned) _heapptr) + diff;
84 if (newhptr <= ((unsigned) _heapend)) {
85 /* Ok, there's space enough */
86 _heapptr = (unsigned*) newhptr;
93 /* The given block was not located on top of the heap, or there's no
94 * room left. Try to allocate a new block and copy the data.
96 if (newblock = malloc (size)) {
98 /* Adjust the old size to the user visible portion */
99 oldsize -= HEAP_ADMIN_SPACE;
101 /* If the new block is larger than the old one, copy the old
104 if (size > oldsize) {
108 /* Copy the block data */
109 memcpy (newblock, block, size);