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/* free.c - C standard library routine.
Copyright (c) 1989, 1993 Michael J. Haertel
You may redistribute this library under the terms of the
GNU Library General Public License (version 2 or any later
version) as published by the Free Software Foundation.
THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY EXPRESS OR IMPLIED
WARRANTY. IN PARTICULAR, THE AUTHOR MAKES NO REPRESENTATION OR
WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY OF THIS
SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE. */
#include <limits.h>
#include <stddef.h>
#include <stdlib.h>
#include "malloc.h"
#ifdef __ELF__
#pragma weak free = __libc_free
#endif
/* Return memory to the heap. */
void
_free_internal (void *ptr)
{
int block, blocks, i, type;
struct list *prev, *next;
if (!ptr)
return;
block = BLOCK(ptr);
switch (type = _heapinfo[block].busy.type) {
case 0:
/* Find the free cluster previous to this one in the free list.
Start searching at the last block referenced; this may benefit
programs with locality of allocation. */
i = _heapindex;
if (i > block)
while (i > block)
i = _heapinfo[i].free.prev;
else {
do
i = _heapinfo[i].free.next;
while (i > 0 && i < block);
i = _heapinfo[i].free.prev;
}
/* Determine how to link this block into the free list. */
if (block == i + _heapinfo[i].free.size) {
/* Coalesce this block with its predecessor. */
_heapinfo[i].free.size += _heapinfo[block].busy.info.size;
block = i;
} else {
/* Really link this block back into the free list. */
_heapinfo[block].free.size = _heapinfo[block].busy.info.size;
_heapinfo[block].free.next = _heapinfo[i].free.next;
_heapinfo[block].free.prev = i;
_heapinfo[i].free.next = block;
_heapinfo[_heapinfo[block].free.next].free.prev = block;
}
/* Now that the block is linked in, see if we can coalesce it
with its successor (by deleting its successor from the list
and adding in its size). */
if (block + _heapinfo[block].free.size == _heapinfo[block].free.next) {
_heapinfo[block].free.size
+= _heapinfo[_heapinfo[block].free.next].free.size;
_heapinfo[block].free.next
= _heapinfo[_heapinfo[block].free.next].free.next;
_heapinfo[_heapinfo[block].free.next].free.prev = block;
}
/* Now see if we can return stuff to the system. */
blocks = _heapinfo[block].free.size;
if (blocks >= FINAL_FREE_BLOCKS && block + blocks == _heaplimit
&& (*__morecore)(0) == ADDRESS(block + blocks)) {
_heaplimit -= blocks;
(*__morecore)(-blocks * BLOCKSIZE);
_heapinfo[_heapinfo[block].free.prev].free.next
= _heapinfo[block].free.next;
_heapinfo[_heapinfo[block].free.next].free.prev
= _heapinfo[block].free.prev;
block = _heapinfo[block].free.prev;
}
/* Set the next search to begin at this block. */
_heapindex = block;
break;
default:
/* Get the address of the first free fragment in this block. */
prev = (struct list *) ((char *) ADDRESS(block)
+ (_heapinfo[block].busy.info.frag.first
<< type));
if (_heapinfo[block].busy.info.frag.nfree == (BLOCKSIZE >> type) - 1
&& _fragblocks[type] > 1) {
/* If all fragments of this block are free, remove them
from the fragment list and free the whole block. */
--_fragblocks[type];
for (next = prev, i = 1; i < BLOCKSIZE >> type; ++i)
next = next->next;
prev->prev->next = next;
if (next)
next->prev = prev->prev;
_heapinfo[block].busy.type = 0;
_heapinfo[block].busy.info.size = 1;
__libc_free(ADDRESS(block));
} else if (_heapinfo[block].busy.info.frag.nfree) {
/* If some fragments of this block are free, link this fragment
into the fragment list after the first free fragment of
this block. */
next = ptr;
next->next = prev->next;
next->prev = prev;
prev->next = next;
if (next->next)
next->next->prev = next;
++_heapinfo[block].busy.info.frag.nfree;
} else {
/* No fragments of this block are free, so link this fragment
into the fragment list and announce that it is the first
free fragment of this block. */
prev = (struct list *) ptr;
_heapinfo[block].busy.info.frag.nfree = 1;
_heapinfo[block].busy.info.frag.first
= (unsigned int) ((char *) ptr - (char *) NULL) % BLOCKSIZE
>> type;
prev->next = _fraghead[type].next;
prev->prev = &_fraghead[type];
prev->prev->next = prev;
if (prev->next)
prev->next->prev = prev;
}
break;
}
}
struct alignlist *_aligned_blocks = NULL;
void
__libc_free (void *ptr)
{
register struct alignlist *l;
if (ptr == NULL)
return;
for (l = _aligned_blocks; l != NULL; l = l->next)
{
if (l->aligned == ptr)
{
l->aligned = NULL; /* Mark the slot in the list as free. */
ptr = l->exact;
break;
}
}
_free_internal (ptr);
}
#include <gnu-stabs.h>
#ifdef elf_alias
elf_alias (free, cfree);
#endif
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