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Diffstat (limited to 'gnu/lib/libmalloc/free.c')
| -rw-r--r-- | gnu/lib/libmalloc/free.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/gnu/lib/libmalloc/free.c b/gnu/lib/libmalloc/free.c new file mode 100644 index 00000000000..7d2a77c8a2f --- /dev/null +++ b/gnu/lib/libmalloc/free.c @@ -0,0 +1,210 @@ +/* Free a block of memory allocated by `malloc'. + Copyright 1990, 1991, 1992 Free Software Foundation + 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 <malloc.h> +#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; + size_t block, blocks; + register 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 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 < (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); +} |