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250 lines
7.3 KiB
C
250 lines
7.3 KiB
C
/* Free a block of memory allocated by `mmalloc'.
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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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Heavily modified Mar 1992 by Fred Fish. (fnf@cygnus.com)
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The GNU C 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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The GNU C 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 the GNU C 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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#include "mmalloc.h"
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/* Return memory to the heap.
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Like `mfree' but don't call a mfree_hook if there is one. */
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void
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__mmalloc_free (mdp, ptr)
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struct mdesc *mdp;
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PTR 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 = mdp -> 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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mdp -> heapstats.chunks_used--;
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mdp -> heapstats.bytes_used -=
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mdp -> heapinfo[block].busy.info.size * BLOCKSIZE;
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mdp -> heapstats.bytes_free +=
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mdp -> 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 = mdp -> heapindex;
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if (i > block)
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{
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while (i > block)
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{
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i = mdp -> heapinfo[i].free.prev;
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}
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}
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else
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{
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do
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{
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i = mdp -> heapinfo[i].free.next;
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}
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while (i > 0 && i < block);
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i = mdp -> 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 + mdp -> heapinfo[i].free.size)
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{
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/* Coalesce this block with its predecessor. */
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mdp -> heapinfo[i].free.size +=
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mdp -> 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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mdp -> heapinfo[block].free.size =
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mdp -> heapinfo[block].busy.info.size;
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mdp -> heapinfo[block].free.next = mdp -> heapinfo[i].free.next;
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mdp -> heapinfo[block].free.prev = i;
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mdp -> heapinfo[i].free.next = block;
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mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev = block;
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mdp -> heapstats.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 + mdp -> heapinfo[block].free.size ==
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mdp -> heapinfo[block].free.next)
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{
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mdp -> heapinfo[block].free.size
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+= mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.size;
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mdp -> heapinfo[block].free.next
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= mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.next;
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mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev = block;
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mdp -> heapstats.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 = mdp -> heapinfo[block].free.size;
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if (blocks >= FINAL_FREE_BLOCKS && block + blocks == mdp -> heaplimit
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&& mdp -> morecore (mdp, 0) == ADDRESS (block + blocks))
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{
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register size_t bytes = blocks * BLOCKSIZE;
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mdp -> heaplimit -= blocks;
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mdp -> morecore (mdp, -bytes);
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mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
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= mdp -> heapinfo[block].free.next;
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mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
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= mdp -> heapinfo[block].free.prev;
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block = mdp -> heapinfo[block].free.prev;
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mdp -> heapstats.chunks_free--;
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mdp -> heapstats.bytes_free -= bytes;
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}
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/* Set the next search to begin at this block. */
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mdp -> 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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mdp -> heapstats.chunks_used--;
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mdp -> heapstats.bytes_used -= 1 << type;
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mdp -> heapstats.chunks_free++;
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mdp -> heapstats.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 *)
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((char *) ADDRESS(block) +
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(mdp -> heapinfo[block].busy.info.frag.first << type));
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if (mdp -> heapinfo[block].busy.info.frag.nfree ==
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(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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{
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next = next -> next;
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}
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prev -> prev -> next = next;
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if (next != NULL)
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{
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next -> prev = prev -> prev;
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}
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mdp -> heapinfo[block].busy.type = 0;
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mdp -> heapinfo[block].busy.info.size = 1;
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/* Keep the statistics accurate. */
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mdp -> heapstats.chunks_used++;
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mdp -> heapstats.bytes_used += BLOCKSIZE;
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mdp -> heapstats.chunks_free -= BLOCKSIZE >> type;
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mdp -> heapstats.bytes_free -= BLOCKSIZE;
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mfree (mdp, ADDRESS(block));
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}
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else if (mdp -> 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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{
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next -> next -> prev = next;
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}
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++mdp -> 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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mdp -> heapinfo[block].busy.info.frag.nfree = 1;
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mdp -> heapinfo[block].busy.info.frag.first =
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RESIDUAL (ptr, BLOCKSIZE) >> type;
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prev -> next = mdp -> fraghead[type].next;
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prev -> prev = &mdp -> fraghead[type];
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prev -> prev -> next = prev;
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if (prev -> next != NULL)
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{
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prev -> next -> prev = prev;
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}
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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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mfree (md, ptr)
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PTR md;
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PTR ptr;
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{
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struct mdesc *mdp;
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register struct alignlist *l;
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if (ptr != NULL)
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{
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mdp = MD_TO_MDP (md);
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for (l = mdp -> aligned_blocks; l != NULL; l = l -> next)
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{
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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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}
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if (mdp -> mfree_hook != NULL)
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{
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(*mdp -> mfree_hook) (md, ptr);
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}
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else
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{
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__mmalloc_free (mdp, ptr);
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}
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}
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}
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/* When using this package, provide a version of malloc/realloc/free built
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on top of it, so that if we use the default sbrk() region we will not
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collide with another malloc package trying to do the same thing, if
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the application contains any "hidden" calls to malloc/realloc/free (such
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as inside a system library).
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NOTE: Defining our own copy of this breaks ANSI conformance. */
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void
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free (ptr)
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PTR ptr;
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{
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mfree ((void *) NULL, ptr);
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}
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