2 * realloc.c - dynamic memory allocation
4 * written by Vangelis Rokas, 2004 (vrokas@otenet.gr)
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; either version 2, or (at your option) any
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
20 * In other words, you are welcome to use, share and improve this program.
21 * You are forbidden to forbid anyone else to use, share and improve
22 * what you give them. Help stamp out software-hoarding!
24 * $Id: realloc.c 3835 2005-08-07 20:09:11Z tecodev $
29 extern unsigned char _MALLOC_SPEC *heap;
31 unsigned char _MALLOC_SPEC *realloc(unsigned char _MALLOC_SPEC *mblock, unsigned char len)
33 _malloc_rec _MALLOC_SPEC *pHeap; /* pointer to block header */
34 _malloc_rec _MALLOC_SPEC *temp;
35 unsigned char bLen; /* size of block */
37 if(len >= MAX_BLOCK_SIZE)
38 return ((unsigned char _MALLOC_SPEC *)0);
40 /* if mblock is NULL, then same as malloc */
47 return ((unsigned char _MALLOC_SPEC *)0);
50 pHeap = (_malloc_rec _MALLOC_SPEC *)((unsigned int)mblock - 1);
51 bLen = pHeap->bits.count;
53 /* block too small for len bytes + 1 byte header <===> bLen < len + 1 <===> blen <= len */
55 /* so, new segment has size bigger than the old one, we can return a
56 * valid pointer only when after the block there is an empty block that
57 * can be merged to produce a new block of the requested size, otherwise
59 temp = _mergeHeapBlock(pHeap, len);
62 /* no could not find a valid block, return NULL */
63 return ((unsigned char _MALLOC_SPEC *)0);
66 //pHeap = temp; /* temp == pHeap */
67 bLen = pHeap->bits.count;
70 len++; /* increase to also count the header */
73 /* new segment is smaller than the old one (or the merged one), that's easy! */
74 pHeap->bits.count = len;
75 temp = (_malloc_rec _MALLOC_SPEC *)((unsigned int)pHeap + len);
77 temp->bits.count = bLen - len;