mirror of
https://github.com/cc65/cc65.git
synced 2024-12-26 08:32:00 +00:00
85 lines
1.8 KiB
C
85 lines
1.8 KiB
C
/*
|
|
* realloc.c
|
|
*
|
|
* Ullrich von Bassewitz, 06.06.1998
|
|
*/
|
|
|
|
|
|
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include "_heap.h"
|
|
|
|
|
|
|
|
void* realloc (void* block, size_t size)
|
|
{
|
|
unsigned* b;
|
|
unsigned* newblock;
|
|
unsigned oldsize;
|
|
int diff;
|
|
|
|
/* 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);
|
|
}
|
|
|
|
/* Get a pointer to the real block, get the old block size */
|
|
b = (unsigned*) (((int) block) - 2);
|
|
oldsize = *b;
|
|
|
|
/* Get the size difference as a signed quantity */
|
|
diff = size - oldsize;
|
|
|
|
/* Is the block at the current heap top? */
|
|
if (((int) b) + oldsize == ((int) _hptr)) {
|
|
/* Check if we've enough memory at the heap top */
|
|
int newhptr;
|
|
newhptr = ((int) _hptr) + diff;
|
|
if (newhptr <= ((int) _hend)) {
|
|
/* Ok, there's space enough */
|
|
_hptr = (unsigned*) newhptr;
|
|
*b = size;
|
|
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 -= sizeof (unsigned);
|
|
|
|
/* 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;
|
|
}
|
|
|
|
|
|
|