140 lines
5.0 KiB
C
140 lines
5.0 KiB
C
/****************************************************************************
|
|
* mm/mm_shrinkchunk.c
|
|
*
|
|
* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
|
|
* Author: Gregory Nutt <gnutt@nuttx.org>
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
* 3. Neither the name NuttX nor the names of its contributors may be
|
|
* used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include "mm_environment.h"
|
|
#include "mm_internal.h"
|
|
|
|
/****************************************************************************
|
|
* Pre-processor Definitions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Global Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: mm_shrinkchunk
|
|
*
|
|
* Description:
|
|
* Reduce the size of the chunk specified by the node structure to the
|
|
* specified size. this internal logic is used both from memalign to
|
|
* dispose of any trailing memory in the aligned allocation and also by
|
|
* realloc when there is a request to reduce the size of an allocation.
|
|
*
|
|
* NOTES:
|
|
* (1) size is the whole chunk size (payload and header)
|
|
* (2) the caller must hold the MM semaphore.
|
|
*
|
|
****************************************************************************/
|
|
|
|
void mm_shrinkchunk(FAR struct mm_allocnode_s *node, size_t size)
|
|
{
|
|
FAR struct mm_freenode_s *next;
|
|
|
|
/* Get a reference to the next node */
|
|
|
|
next = (FAR struct mm_freenode_s*)((char*)node + node->size);
|
|
|
|
/* Check if it is free */
|
|
|
|
if ((next->preceding & MM_ALLOC_BIT) == 0)
|
|
{
|
|
FAR struct mm_allocnode_s *andbeyond;
|
|
FAR struct mm_freenode_s *newnode;
|
|
|
|
/* Get the chunk next the next node (which could be the tail chunk) */
|
|
|
|
andbeyond = (FAR struct mm_allocnode_s*)((char*)next + next->size);
|
|
|
|
/* Remove the next node. There must be a predecessor, but there may
|
|
* not be a successor node.
|
|
*/
|
|
|
|
DEBUGASSERT(next->blink);
|
|
next->blink->flink = next->flink;
|
|
if (next->flink)
|
|
{
|
|
next->flink->blink = next->blink;
|
|
}
|
|
|
|
/* Create a new chunk that will hold both the next chunk and the
|
|
* tailing memory from the aligned chunk.
|
|
*/
|
|
|
|
newnode = (FAR struct mm_freenode_s*)((char*)node + size);
|
|
|
|
/* Set up the size of the new node */
|
|
|
|
newnode->size = next->size + node->size - size;
|
|
newnode->preceding = size;
|
|
node->size = size;
|
|
andbeyond->preceding = newnode->size | (andbeyond->preceding & MM_ALLOC_BIT);
|
|
|
|
/* Add the new node to the freenodelist */
|
|
|
|
mm_addfreechunk(newnode);
|
|
}
|
|
|
|
/* The next chunk is allocated. Try to free the end portion at the end
|
|
* chunk to be shrunk.
|
|
*/
|
|
|
|
else if (node->size >= size + SIZEOF_MM_FREENODE)
|
|
{
|
|
FAR struct mm_freenode_s *newnode;
|
|
|
|
/* Create a new chunk that will hold both the next chunk and the
|
|
* tailing memory from the aligned chunk.
|
|
*/
|
|
|
|
newnode = (FAR struct mm_freenode_s*)((char*)node + size);
|
|
|
|
/* Set up the size of the new node */
|
|
|
|
newnode->size = node->size - size;
|
|
newnode->preceding = size;
|
|
node->size = size;
|
|
next->preceding = newnode->size | MM_ALLOC_BIT;
|
|
|
|
/* Add the new node to the freenodelist */
|
|
|
|
mm_addfreechunk(newnode);
|
|
}
|
|
}
|