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/*****************************************************************************/
/* */
/* realloc.c */
/* */
/* Change the size of an allocated memory block */
/* */
/* */
/* */
/* (C) 1998-2004 Ullrich von Bassewitz */
/* Wacholderweg 14 */
/* D-70597 Stuttgart */
/* EMail: uz@musoftware.de */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
/* warranty. In no event will the authors be held liable for any damages */
/* arising from the use of this software. */
/* */
/* Permission is granted to anyone to use this software for any purpose, */
/* including commercial applications, and to alter it and redistribute it */
/* freely, subject to the following restrictions: */
/* */
/* 1. The origin of this software must not be misrepresented; you must not */
/* claim that you wrote the original software. If you use this software */
/* in a product, an acknowledgment in the product documentation would be */
/* appreciated but is not required. */
/* 2. Altered source versions must be plainly marked as such, and must not */
/* be misrepresented as being the original software. */
/* 3. This notice may not be removed or altered from any source */
/* distribution. */
/* */
/*****************************************************************************/
#include <stdlib.h>
#include <string.h>
#include <_heap.h>
void* __fastcall__ realloc (void* block, register size_t size)
{
register struct usedblock* b;
struct usedblock* newblock;
unsigned oldsize;
unsigned newhptr;
/* Check the block parameter */
if (!block) {
/* Block is NULL, same as malloc */
return malloc (size);
}
/* Check the size parameter */
if (size == 0) {
/* Block is not NULL, but size is: free the block */
free (block);
return 0;
}
/* Make the internal used size from the given size */
size += HEAP_ADMIN_SPACE;
if (size < sizeof (struct freeblock)) {
size = sizeof (struct freeblock);
}
/* The word below the user block contains a pointer to the start of the
** raw memory block. The first word of this raw memory block is the full
** size of the block. Get a pointer to the real block, get the old block
** size.
*/
b = (((struct usedblock*) block) - 1)->start;
oldsize = b->size;
/* Is the block at the current heap top? */
if (((unsigned) b) + oldsize == ((unsigned) _heapptr)) {
/* Check if we've enough memory at the heap top */
newhptr = ((unsigned) _heapptr) - oldsize + size;
if (newhptr <= ((unsigned) _heapend)) {
/* Ok, there's space enough */
_heapptr = (unsigned*) newhptr;
b->size = size;
b->start = b;
return block;
}
}
/* The given block was not located on top of the heap, or there's no
** room left. Try to allocate a new block and copy the data.
*/
if (newblock = malloc (size)) {
/* Adjust the old size to the user visible portion */
oldsize -= HEAP_ADMIN_SPACE;
/* If the new block is larger than the old one, copy the old
** data only
*/
if (size > oldsize) {
size = oldsize;
}
/* Copy the block data */
memcpy (newblock, block, size);
free (block);
}
return newblock;
}
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