936298e2bd
that Chris created: this version of GNU malloc was obtained from prep.ai.mit.edu on 9/22/1993. There was no version noted.
211 lines
6.2 KiB
C
211 lines
6.2 KiB
C
/* Free a block of memory allocated by `malloc'.
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Copyright 1990, 1991, 1992 Free Software Foundation
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Written May 1989 by Mike Haertel.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA.
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The author may be reached (Email) at the address mike@ai.mit.edu,
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or (US mail) as Mike Haertel c/o Free Software Foundation. */
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#ifndef _MALLOC_INTERNAL
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#define _MALLOC_INTERNAL
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#include <malloc.h>
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#endif
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/* Debugging hook for free. */
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void (*__free_hook) __P ((__ptr_t __ptr));
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/* List of blocks allocated by memalign. */
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struct alignlist *_aligned_blocks = NULL;
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/* Return memory to the heap.
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Like `free' but don't call a __free_hook if there is one. */
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void
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_free_internal (ptr)
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__ptr_t ptr;
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{
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int type;
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size_t block, blocks;
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register size_t i;
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struct list *prev, *next;
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block = BLOCK (ptr);
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type = _heapinfo[block].busy.type;
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switch (type)
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{
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case 0:
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/* Get as many statistics as early as we can. */
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--_chunks_used;
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_bytes_used -= _heapinfo[block].busy.info.size * BLOCKSIZE;
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_bytes_free += _heapinfo[block].busy.info.size * BLOCKSIZE;
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/* Find the free cluster previous to this one in the free list.
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Start searching at the last block referenced; this may benefit
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programs with locality of allocation. */
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i = _heapindex;
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if (i > block)
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while (i > block)
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i = _heapinfo[i].free.prev;
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else
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{
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do
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i = _heapinfo[i].free.next;
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while (i > 0 && i < block);
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i = _heapinfo[i].free.prev;
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}
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/* Determine how to link this block into the free list. */
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if (block == i + _heapinfo[i].free.size)
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{
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/* Coalesce this block with its predecessor. */
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_heapinfo[i].free.size += _heapinfo[block].busy.info.size;
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block = i;
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}
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else
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{
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/* Really link this block back into the free list. */
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_heapinfo[block].free.size = _heapinfo[block].busy.info.size;
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_heapinfo[block].free.next = _heapinfo[i].free.next;
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_heapinfo[block].free.prev = i;
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_heapinfo[i].free.next = block;
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_heapinfo[_heapinfo[block].free.next].free.prev = block;
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++_chunks_free;
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}
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/* Now that the block is linked in, see if we can coalesce it
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with its successor (by deleting its successor from the list
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and adding in its size). */
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if (block + _heapinfo[block].free.size == _heapinfo[block].free.next)
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{
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_heapinfo[block].free.size
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+= _heapinfo[_heapinfo[block].free.next].free.size;
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_heapinfo[block].free.next
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= _heapinfo[_heapinfo[block].free.next].free.next;
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_heapinfo[_heapinfo[block].free.next].free.prev = block;
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--_chunks_free;
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}
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/* Now see if we can return stuff to the system. */
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blocks = _heapinfo[block].free.size;
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if (blocks >= FINAL_FREE_BLOCKS && block + blocks == _heaplimit
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&& (*__morecore) (0) == ADDRESS (block + blocks))
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{
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register size_t bytes = blocks * BLOCKSIZE;
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_heaplimit -= blocks;
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(*__morecore) (-bytes);
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_heapinfo[_heapinfo[block].free.prev].free.next
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= _heapinfo[block].free.next;
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_heapinfo[_heapinfo[block].free.next].free.prev
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= _heapinfo[block].free.prev;
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block = _heapinfo[block].free.prev;
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--_chunks_free;
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_bytes_free -= bytes;
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}
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/* Set the next search to begin at this block. */
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_heapindex = block;
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break;
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default:
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/* Do some of the statistics. */
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--_chunks_used;
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_bytes_used -= 1 << type;
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++_chunks_free;
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_bytes_free += 1 << type;
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/* Get the address of the first free fragment in this block. */
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prev = (struct list *) ((char *) ADDRESS (block) +
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(_heapinfo[block].busy.info.frag.first << type));
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if (_heapinfo[block].busy.info.frag.nfree == (BLOCKSIZE >> type) - 1)
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{
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/* If all fragments of this block are free, remove them
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from the fragment list and free the whole block. */
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next = prev;
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for (i = 1; i < (size_t) (BLOCKSIZE >> type); ++i)
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next = next->next;
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prev->prev->next = next;
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if (next != NULL)
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next->prev = prev->prev;
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_heapinfo[block].busy.type = 0;
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_heapinfo[block].busy.info.size = 1;
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/* Keep the statistics accurate. */
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++_chunks_used;
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_bytes_used += BLOCKSIZE;
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_chunks_free -= BLOCKSIZE >> type;
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_bytes_free -= BLOCKSIZE;
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free (ADDRESS (block));
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}
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else if (_heapinfo[block].busy.info.frag.nfree != 0)
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{
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/* If some fragments of this block are free, link this
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fragment into the fragment list after the first free
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fragment of this block. */
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next = (struct list *) ptr;
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next->next = prev->next;
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next->prev = prev;
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prev->next = next;
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if (next->next != NULL)
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next->next->prev = next;
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++_heapinfo[block].busy.info.frag.nfree;
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}
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else
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{
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/* No fragments of this block are free, so link this
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fragment into the fragment list and announce that
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it is the first free fragment of this block. */
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prev = (struct list *) ptr;
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_heapinfo[block].busy.info.frag.nfree = 1;
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_heapinfo[block].busy.info.frag.first = (unsigned long int)
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((unsigned long int) ((char *) ptr - (char *) NULL)
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% BLOCKSIZE >> type);
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prev->next = _fraghead[type].next;
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prev->prev = &_fraghead[type];
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prev->prev->next = prev;
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if (prev->next != NULL)
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prev->next->prev = prev;
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}
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break;
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}
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}
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/* Return memory to the heap. */
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void
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free (ptr)
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__ptr_t ptr;
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{
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register struct alignlist *l;
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if (ptr == NULL)
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return;
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for (l = _aligned_blocks; l != NULL; l = l->next)
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if (l->aligned == ptr)
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{
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l->aligned = NULL; /* Mark the slot in the list as free. */
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ptr = l->exact;
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break;
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}
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if (__free_hook != NULL)
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(*__free_hook) (ptr);
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else
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_free_internal (ptr);
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}
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