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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"
- /* 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;
- 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
- 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);
- }
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