![patacongo](/assets/img/avatar_default.png)
git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@3648 7fd9a85b-ad96-42d3-883c-3090e2eb8679
205 lines
6.2 KiB
C
205 lines
6.2 KiB
C
/************************************************************
|
|
* mm/mm_malloc.c
|
|
*
|
|
* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
|
|
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
|
|
*
|
|
* 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
|
|
************************************************************/
|
|
|
|
/* Special definitions when we operate in the normal vs. the
|
|
* host-pc test environement.
|
|
*/
|
|
|
|
#include <assert.h>
|
|
#include "mm_environment.h"
|
|
#include "mm_internal.h"
|
|
|
|
/************************************************************
|
|
* Pre-processor Definitions
|
|
************************************************************/
|
|
|
|
#ifndef NULL
|
|
# define NULL ((void*)0)
|
|
#endif
|
|
|
|
/************************************************************
|
|
* Type Definitions
|
|
************************************************************/
|
|
|
|
/************************************************************
|
|
* Private Data
|
|
************************************************************/
|
|
|
|
/************************************************************
|
|
* Public Data
|
|
************************************************************/
|
|
|
|
/************************************************************
|
|
* Private Functions
|
|
************************************************************/
|
|
|
|
/************************************************************
|
|
* Public Functions
|
|
************************************************************/
|
|
|
|
/************************************************************
|
|
* malloc
|
|
*
|
|
* Description:
|
|
* Find the smallest chunk that satisfies the request.
|
|
* Take the memory from that chunk, save the remaining,
|
|
* smaller chunk (if any).
|
|
*
|
|
* 8-byte alignment of the allocated data is assured.
|
|
*
|
|
************************************************************/
|
|
|
|
FAR void *malloc(size_t size)
|
|
{
|
|
FAR struct mm_freenode_s *node;
|
|
void *ret = NULL;
|
|
int ndx;
|
|
|
|
/* Handle bad sizes */
|
|
|
|
if (size <= 0)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
/* Adjust the size to account for (1) the size of the allocated
|
|
* node and (2) to make sure that it is an even multiple of
|
|
* our granule size.
|
|
*/
|
|
|
|
size = MM_ALIGN_UP(size + SIZEOF_MM_ALLOCNODE);
|
|
|
|
/* We need to hold the MM semaphore while we muck with the
|
|
* nodelist.
|
|
*/
|
|
|
|
mm_takesemaphore();
|
|
|
|
/* Get the location in the node list to start the search.
|
|
* Special case really big alloctions
|
|
*/
|
|
|
|
if (size >= MM_MAX_CHUNK)
|
|
{
|
|
ndx = MM_NNODES-1;
|
|
}
|
|
else
|
|
{
|
|
/* Convert the request size into a nodelist index */
|
|
|
|
ndx = mm_size2ndx(size);
|
|
}
|
|
|
|
/* Search for a large enough chunk in the list of nodes.
|
|
* This list is ordered by size, but will have occasional
|
|
* zero sized nodes as we visit other g_nodelist[] entries.
|
|
*/
|
|
|
|
for (node = g_nodelist[ndx].flink;
|
|
node && node->size < size;
|
|
node = node->flink);
|
|
|
|
/* If we found a node with non-zero size, then this is one
|
|
* to use. Since the list is ordered, we know that is must be
|
|
* best fitting chunk available.
|
|
*/
|
|
|
|
if (node)
|
|
{
|
|
FAR struct mm_freenode_s *remainder;
|
|
FAR struct mm_freenode_s *next;
|
|
size_t remaining;
|
|
|
|
/* Remove the node. There must be a predecessor, but there may
|
|
* not be a successor node.
|
|
*/
|
|
|
|
DEBUGASSERT(node->blink);
|
|
node->blink->flink = node->flink;
|
|
if (node->flink)
|
|
{
|
|
node->flink->blink = node->blink;
|
|
}
|
|
|
|
/* Check if we have to split the free node into one of the
|
|
* allocated size and another smaller freenode. In some
|
|
* cases, the remaining bytes can be smaller (they may be
|
|
* SIZEOF_MM_ALLOCNODE). In that case, we will just carry
|
|
* the few wasted bytes at the end of the allocation.
|
|
*/
|
|
|
|
remaining = node->size - size;
|
|
if (remaining >= SIZEOF_MM_FREENODE)
|
|
{
|
|
/* Get a pointer to the next node in physical memory */
|
|
|
|
next = (FAR struct mm_freenode_s*)(((char*)node) + node->size);
|
|
|
|
/* Create the remainder node */
|
|
|
|
remainder = (FAR struct mm_freenode_s*)(((char*)node) + size);
|
|
remainder->size = remaining;
|
|
remainder->preceding = size;
|
|
|
|
/* Adjust the size of the node under consideration */
|
|
|
|
node->size = size;
|
|
|
|
/* Adjust the 'preceding' size of the (old) next node,
|
|
* preserving the allocated flag.
|
|
*/
|
|
|
|
next->preceding = remaining | (next->preceding & MM_ALLOC_BIT);
|
|
|
|
/* Add the remainder back into the nodelist */
|
|
|
|
mm_addfreechunk(remainder);
|
|
}
|
|
|
|
/* Handle the case of an exact size match */
|
|
|
|
node->preceding |= MM_ALLOC_BIT;
|
|
ret = (void*)((char*)node + SIZEOF_MM_ALLOCNODE);
|
|
}
|
|
|
|
mm_givesemaphore();
|
|
mvdbg("Allocated %p, size %d\n", ret, size);
|
|
return ret;
|
|
}
|