2007-02-18 00:21:28 +01:00
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/************************************************************
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2009-12-15 02:39:03 +01:00
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* mm/mm_malloc.c
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2007-02-18 00:21:28 +01:00
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*
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2009-12-15 02:39:03 +01:00
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* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
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2007-02-18 00:21:28 +01:00
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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2009-12-15 02:39:03 +01:00
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* 3. Neither the name NuttX nor the names of its contributors may be
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2007-02-18 00:21:28 +01:00
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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************************************************************/
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/************************************************************
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* Included Files
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************************************************************/
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/* Special definitions when we operate in the normal vs. the
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* host-pc test environement.
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*/
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#include <assert.h>
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#include "mm_environment.h"
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#include "mm_internal.h"
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/************************************************************
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2009-12-15 02:39:03 +01:00
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* Pre-processor Definitions
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2007-02-18 00:21:28 +01:00
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************************************************************/
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#ifndef NULL
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# define NULL ((void*)0)
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#endif
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/************************************************************
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* Type Definitions
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************************************************************/
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/************************************************************
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* Private Data
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************************************************************/
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/************************************************************
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* Public Data
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************************************************************/
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/************************************************************
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* Private Functions
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************************************************************/
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/************************************************************
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* Public Functions
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************************************************************/
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/************************************************************
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* malloc
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*
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* Description:
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* Find the smallest chunk that satisfies the request.
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* Take the memory from that chunk, save the remaining,
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* smaller chunk (if any).
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*
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* 8-byte alignment of the allocated data is assured.
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*
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************************************************************/
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2007-02-27 22:17:21 +01:00
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FAR void *malloc(size_t size)
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2007-02-18 00:21:28 +01:00
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{
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2007-02-27 22:17:21 +01:00
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FAR struct mm_freenode_s *node;
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2007-02-18 00:21:28 +01:00
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void *ret = NULL;
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int ndx;
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/* Handle bad sizes */
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if (size <= 0)
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{
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return NULL;
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}
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/* Adjust the size to account for (1) the size of the allocated
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* node and (2) to make sure that it is an even multiple of
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* our granule size.
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*/
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size = MM_ALIGN_UP(size + SIZEOF_MM_ALLOCNODE);
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/* We need to hold the MM semaphore while we muck with the
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* nodelist.
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*/
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mm_takesemaphore();
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/* Get the location in the node list to start the search.
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* Special case really big alloctions
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*/
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if (size >= MM_MAX_CHUNK)
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{
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ndx = MM_NNODES-1;
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}
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else
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{
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/* Convert the request size into a nodelist index */
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ndx = mm_size2ndx(size);
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}
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/* Search for a large enough chunk in the list of nodes.
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* This list is ordered by size, but will have occasional
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* zero sized nodes as we visit other g_nodelist[] entries.
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*/
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for (node = g_nodelist[ndx].flink;
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node && node->size < size;
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node = node->flink);
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/* If we found a node with non-zero size, then this is one
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* to use. Since the list is ordered, we know that is must be
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* best fitting chunk available.
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*/
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if (node)
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{
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FAR struct mm_freenode_s *remainder;
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FAR struct mm_freenode_s *next;
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2007-02-21 22:55:16 +01:00
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size_t remaining;
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2007-02-18 00:21:28 +01:00
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/* Remove the node. There must be a predecessor, but there may
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* not be a successor node.
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*/
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DEBUGASSERT(node->blink);
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node->blink->flink = node->flink;
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if (node->flink)
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{
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node->flink->blink = node->blink;
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}
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/* Check if we have to split the free node into one of the
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* allocated size and another smaller freenode. In some
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* cases, the remaining bytes can be smaller (they may be
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* SIZEOF_MM_ALLOCNODE). In that case, we will just carry
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* the few wasted bytes at the end of the allocation.
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*/
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remaining = node->size - size;
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if (remaining >= SIZEOF_MM_FREENODE)
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{
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/* Get a pointer to the next node in physical memory */
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2007-02-27 22:17:21 +01:00
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next = (FAR struct mm_freenode_s*)(((char*)node) + node->size);
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2007-02-18 00:21:28 +01:00
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/* Create the remainder node */
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2007-02-27 22:17:21 +01:00
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remainder = (FAR struct mm_freenode_s*)(((char*)node) + size);
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2007-02-18 00:21:28 +01:00
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remainder->size = remaining;
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remainder->preceding = size;
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/* Adjust the size of the node under consideration */
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node->size = size;
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/* Adjust the 'preceding' size of the (old) next node,
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* preserving the allocated flag.
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*/
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next->preceding = remaining | (next->preceding & MM_ALLOC_BIT);
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/* Add the remainder back into the nodelist */
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mm_addfreechunk(remainder);
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}
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/* Handle the case of an exact size match */
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node->preceding |= MM_ALLOC_BIT;
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ret = (void*)((char*)node + SIZEOF_MM_ALLOCNODE);
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}
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mm_givesemaphore();
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2011-05-28 23:42:18 +02:00
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mvdbg("Allocated %p, size %d\n", ret, size);
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2007-02-18 00:21:28 +01:00
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return ret;
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}
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