/* $NetBSD: free.c,v 1.1.1.1 2016/01/13 21:42:18 christos Exp $ */ /* Free a block of memory allocated by `malloc'. Copyright 1990, 1991, 1992, 1994 Free Software Foundation, Inc. Written May 1989 by Mike Haertel. This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with this library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. The author may be reached (Email) at the address mike@ai.mit.edu, or (US mail) as Mike Haertel c/o Free Software Foundation. */ #ifndef _MALLOC_INTERNAL #define _MALLOC_INTERNAL #include #endif /* Debugging hook for free. */ void (*__free_hook) __P ((__ptr_t __ptr)); /* List of blocks allocated by memalign. */ struct alignlist *_aligned_blocks = NULL; /* Return memory to the heap. Like `free' but don't call a __free_hook if there is one. */ void _free_internal (ptr) __ptr_t ptr; { int type; __malloc_size_t block, blocks; register __malloc_size_t i; struct list *prev, *next; block = BLOCK (ptr); type = _heapinfo[block].busy.type; switch (type) { case 0: /* Get as many statistics as early as we can. */ --_chunks_used; _bytes_used -= _heapinfo[block].busy.info.size * BLOCKSIZE; _bytes_free += _heapinfo[block].busy.info.size * BLOCKSIZE; /* 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; ++_chunks_free; } /* 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; --_chunks_free; } /* 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)) { register __malloc_size_t bytes = blocks * BLOCKSIZE; _heaplimit -= blocks; (*__morecore) (-bytes); _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; --_chunks_free; _bytes_free -= bytes; } /* Set the next search to begin at this block. */ _heapindex = block; break; default: /* Do some of the statistics. */ --_chunks_used; _bytes_used -= 1 << type; ++_chunks_free; _bytes_free += 1 << type; /* 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) { /* If all fragments of this block are free, remove them from the fragment list and free the whole block. */ next = prev; for (i = 1; i < (__malloc_size_t) (BLOCKSIZE >> type); ++i) next = next->next; prev->prev->next = next; if (next != NULL) next->prev = prev->prev; _heapinfo[block].busy.type = 0; _heapinfo[block].busy.info.size = 1; /* Keep the statistics accurate. */ ++_chunks_used; _bytes_used += BLOCKSIZE; _chunks_free -= BLOCKSIZE >> type; _bytes_free -= BLOCKSIZE; free (ADDRESS (block)); } else if (_heapinfo[block].busy.info.frag.nfree != 0) { /* If some fragments of this block are free, link this fragment into the fragment list after the first free fragment of this block. */ next = (struct list *) ptr; next->next = prev->next; next->prev = prev; prev->next = next; if (next->next != NULL) 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 long int) ((unsigned long int) ((char *) ptr - (char *) NULL) % BLOCKSIZE >> type); prev->next = _fraghead[type].next; prev->prev = &_fraghead[type]; prev->prev->next = prev; if (prev->next != NULL) prev->next->prev = prev; } break; } } /* Return memory to the heap. */ void free (ptr) __ptr_t 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; } if (__free_hook != NULL) (*__free_hook) (ptr); else _free_internal (ptr); }