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cc65/libsrc/common/realloc.c
cuz a992dd05a0 Fixed a bug
git-svn-id: svn://svn.cc65.org/cc65/trunk@128 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-06-25 13:17:26 +00:00

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;
}