- if (size <= BLOCKSIZE / 2)
- {
- /* Small allocation to receive a fragment of a block.
- Determine the logarithm to base two of the fragment size. */
- log = 1;
- --size;
- while ((size /= 2) != 0)
- {
- ++log;
- }
-
- /* Look in the fragment lists for a
- free fragment of the desired size. */
- next = mdp -> fraghead[log].next;
- if (next != NULL)
- {
- /* There are free fragments of this size.
- Pop a fragment out of the fragment list and return it.
- Update the block's nfree and first counters. */
- result = (PTR) next;
- next -> prev -> next = next -> next;
- if (next -> next != NULL)
- {
- next -> next -> prev = next -> prev;
- }
- block = BLOCK (result);
- if (--mdp -> heapinfo[block].busy.info.frag.nfree != 0)
- {
- mdp -> heapinfo[block].busy.info.frag.first =
- RESIDUAL (next -> next, BLOCKSIZE) >> log;
- }
-
- /* Update the statistics. */
- mdp -> heapstats.chunks_used++;
- mdp -> heapstats.bytes_used += 1 << log;
- mdp -> heapstats.chunks_free--;
- mdp -> heapstats.bytes_free -= 1 << log;
- }
- else
- {
- /* No free fragments of the desired size, so get a new block
- and break it into fragments, returning the first. */
- result = mmalloc (md, BLOCKSIZE);
- if (result == NULL)
- {
- return (NULL);
- }
-
- /* Link all fragments but the first into the free list. */
- for (i = 1; i < (size_t) (BLOCKSIZE >> log); ++i)
- {
- next = (struct list *) ((char*) result + (i << log));
- next -> next = mdp -> fraghead[log].next;
- next -> prev = &mdp -> fraghead[log];
- next -> prev -> next = next;
- if (next -> next != NULL)
- {
- next -> next -> prev = next;
- }
- }
-
- /* Initialize the nfree and first counters for this block. */
- block = BLOCK (result);
- mdp -> heapinfo[block].busy.type = log;
- mdp -> heapinfo[block].busy.info.frag.nfree = i - 1;
- mdp -> heapinfo[block].busy.info.frag.first = i - 1;
-
- mdp -> heapstats.chunks_free += (BLOCKSIZE >> log) - 1;
- mdp -> heapstats.bytes_free += BLOCKSIZE - (1 << log);
- mdp -> heapstats.bytes_used -= BLOCKSIZE - (1 << log);
- }
- }
- else
- {
- /* Large allocation to receive one or more blocks.
- Search the free list in a circle starting at the last place visited.
- If we loop completely around without finding a large enough
- space we will have to get more memory from the system. */
- blocks = BLOCKIFY(size);
- start = block = MALLOC_SEARCH_START;
- while (mdp -> heapinfo[block].free.size < blocks)
- {
- block = mdp -> heapinfo[block].free.next;
- if (block == start)
- {
- /* Need to get more from the system. Check to see if
- the new core will be contiguous with the final free
- block; if so we don't need to get as much. */
- block = mdp -> heapinfo[0].free.prev;
- lastblocks = mdp -> heapinfo[block].free.size;
- if (mdp -> heaplimit != 0 &&
- block + lastblocks == mdp -> heaplimit &&
- mdp -> morecore (mdp, 0) == ADDRESS(block + lastblocks) &&
- (morecore (mdp, (blocks - lastblocks) * BLOCKSIZE)) != NULL)
- {
- /* Which block we are extending (the `final free
- block' referred to above) might have changed, if
- it got combined with a freed info table. */
- block = mdp -> heapinfo[0].free.prev;
-
- mdp -> heapinfo[block].free.size += (blocks - lastblocks);
- mdp -> heapstats.bytes_free +=
- (blocks - lastblocks) * BLOCKSIZE;
- continue;
- }
- result = morecore(mdp, blocks * BLOCKSIZE);
- if (result == NULL)
- {
- return (NULL);
- }
- block = BLOCK (result);
- mdp -> heapinfo[block].busy.type = 0;
- mdp -> heapinfo[block].busy.info.size = blocks;
- mdp -> heapstats.chunks_used++;
- mdp -> heapstats.bytes_used += blocks * BLOCKSIZE;
- return (result);
- }
- }
-
- /* At this point we have found a suitable free list entry.
- Figure out how to remove what we need from the list. */
- result = ADDRESS(block);
- if (mdp -> heapinfo[block].free.size > blocks)
- {
- /* The block we found has a bit left over,
- so relink the tail end back into the free list. */
- mdp -> heapinfo[block + blocks].free.size
- = mdp -> heapinfo[block].free.size - blocks;
- mdp -> heapinfo[block + blocks].free.next
- = mdp -> heapinfo[block].free.next;
- mdp -> heapinfo[block + blocks].free.prev
- = mdp -> heapinfo[block].free.prev;
- mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
- = mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
- = mdp -> heapindex = block + blocks;
- }
- else
- {
- /* The block exactly matches our requirements,
- so just remove it from the list. */
- mdp -> heapinfo[mdp -> heapinfo[block].free.next].free.prev
- = mdp -> heapinfo[block].free.prev;
- mdp -> heapinfo[mdp -> heapinfo[block].free.prev].free.next
- = mdp -> heapindex = mdp -> heapinfo[block].free.next;
- mdp -> heapstats.chunks_free--;
- }
-
- mdp -> heapinfo[block].busy.type = 0;
- mdp -> heapinfo[block].busy.info.size = blocks;
- mdp -> heapstats.chunks_used++;
- mdp -> heapstats.bytes_used += blocks * BLOCKSIZE;
- mdp -> heapstats.bytes_free -= blocks * BLOCKSIZE;