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-rw-r--r--nuttx/mm/mm_realloc.c352
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diff --git a/nuttx/mm/mm_realloc.c b/nuttx/mm/mm_realloc.c
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index b44938995..000000000
--- a/nuttx/mm/mm_realloc.c
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-/****************************************************************************
- * mm/mm_realloc.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 <string.h>
-#include "mm_environment.h"
-#include <stdio.h>
-#include "mm_internal.h"
-
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Global Functions
- ****************************************************************************/
-
-/****************************************************************************
- * Name: realloc
- *
- * Description:
- * If the reallocation is for less space, then:
- *
- * (1) the current allocation is reduced in size
- * (2) the remainder at the end of the allocation is returned to the
- * free list.
- *
- * If the request is for more space and the current allocation can be
- * extended, it will be extended by:
- *
- * (1) Taking the additional space from the following free chunk, or
- * (2) Taking the additional space from the preceding free chunk.
- * (3) Or both
- *
- * If the request is for more space but the current chunk cannot be
- * extended, then malloc a new buffer, copy the data into the new buffer,
- * and free the old buffer.
- *
- ****************************************************************************/
-
-FAR void *realloc(FAR void *oldmem, size_t size)
-{
- FAR struct mm_allocnode_s *oldnode;
- FAR struct mm_freenode_s *prev;
- FAR struct mm_freenode_s *next;
- size_t oldsize;
- size_t prevsize = 0;
- size_t nextsize = 0;
- FAR void *newmem;
-
- /* If oldmem is NULL, then realloc is equivalent to malloc */
-
- if (!oldmem)
- {
- return malloc(size);
- }
-
- /* If size is zero, then realloc is equivalent to free */
-
- if (size <= 0)
- {
- free(oldmem);
- 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);
-
- /* Map the memory chunk into an allocated node structure */
-
- oldnode = (FAR struct mm_allocnode_s *)((FAR char*)oldmem - SIZEOF_MM_ALLOCNODE);
-
- /* We need to hold the MM semaphore while we muck with the nodelist. */
-
- mm_takesemaphore();
-
- /* Check if this is a request to reduce the size of the allocation. */
-
- oldsize = oldnode->size;
- if (size <= oldsize)
- {
- /* Handle the special case where we are not going to change the size
- * of the allocation.
- */
-
- if (size < oldsize)
- {
- mm_shrinkchunk(oldnode, size);
- }
-
- /* Then return the original address */
-
- mm_givesemaphore();
- return oldmem;
- }
-
- /* This is a request to increase the size of the allocation, Get the
- * available sizes before and after the oldnode so that we can make the
- * best decision
- */
-
- next = (FAR struct mm_freenode_s *)((FAR char*)oldnode + oldnode->size);
- if ((next->preceding & MM_ALLOC_BIT) == 0)
- {
- nextsize = next->size;
- }
-
- prev = (FAR struct mm_freenode_s *)((FAR char*)oldnode - (oldnode->preceding & ~MM_ALLOC_BIT));
- if ((prev->preceding & MM_ALLOC_BIT) == 0)
- {
- prevsize = prev->size;
- }
-
- /* Now, check if we can extend the current allocation or not */
-
- if (nextsize + prevsize + oldsize >= size)
- {
- size_t needed = size - oldsize;
- size_t takeprev = 0;
- size_t takenext = 0;
-
- /* Check if we can extend into the previous chunk and if the
- * previous chunk is smaller than the next chunk.
- */
-
- if (prevsize > 0 && (nextsize >= prevsize || nextsize <= 0))
- {
- /* Can we get everything we need from the previous chunk? */
-
- if (needed > prevsize)
- {
- /* No, take the whole previous chunk and get the
- * rest that we need from the next chunk.
- */
-
- takeprev = prevsize;
- takenext = needed - prevsize;
- }
- else
- {
- /* Yes, take what we need from the previous chunk */
-
- takeprev = needed;
- takenext = 0;
- }
-
- needed = 0;
- }
-
- /* Check if we can extend into the next chunk and if we still need
- * more memory.
- */
-
- if (nextsize > 0 && needed)
- {
- /* Can we get everything we need from the next chunk? */
-
- if (needed > nextsize)
- {
- /* No, take the whole next chunk and get the rest that we
- * need from the previous chunk.
- */
-
- takeprev = needed - nextsize;
- takenext = nextsize;
- }
- else
- {
- /* Yes, take what we need from the previous chunk */
-
- takeprev = 0;
- takenext = needed;
- }
- }
-
- /* Extend into the previous free chunk */
-
- newmem = oldmem;
- if (takeprev)
- {
- FAR struct mm_allocnode_s *newnode;
-
- /* Remove the previous node. There must be a predecessor, but
- * there may not be a successor node.
- */
-
- DEBUGASSERT(prev->blink);
- prev->blink->flink = prev->flink;
- if (prev->flink)
- {
- prev->flink->blink = prev->blink;
- }
-
- /* Extend the node into the previous free chunk */
-
- newnode = (FAR struct mm_allocnode_s *)((FAR char*)oldnode - takeprev);
-
- /* Did we consume the entire preceding chunk? */
-
- if (takeprev < prevsize)
- {
- /* No.. just take what we need from the previous chunk and put
- * it back into the free list
- */
-
- prev->size -= takeprev;
- newnode->size = oldsize + takeprev;
- newnode->preceding = prev->size | MM_ALLOC_BIT;
- next->preceding = newnode->size | (next->preceding & MM_ALLOC_BIT);
-
- /* Return the previous free node to the nodelist (with the new size) */
-
- mm_addfreechunk(prev);
-
- /* Now we want to return newnode */
-
- oldnode = newnode;
- }
- else
- {
- /* Yes.. update its size (newnode->preceding is already set) */
-
- newnode->size += oldsize;
- newnode->preceding |= MM_ALLOC_BIT;
- next->preceding = newnode->size | (next->preceding & MM_ALLOC_BIT);
- }
-
- oldnode = newnode;
- oldsize = newnode->size;
-
- /* Now we have to move the user contents 'down' in memory. memcpy should
- * should be save for this.
- */
-
- newmem = (FAR void*)((FAR char*)newnode + SIZEOF_MM_ALLOCNODE);
- memcpy(newmem, oldmem, oldsize - SIZEOF_MM_ALLOCNODE);
- }
-
- /* Extend into the next free chunk */
-
- if (takenext)
- {
- FAR struct mm_freenode_s *newnode;
- FAR struct mm_allocnode_s *andbeyond;
-
- /* Get the chunk following the next node (which could be the tail
- * chunk)
- */
-
- andbeyond = (FAR struct mm_allocnode_s*)((char*)next + nextsize);
-
- /* 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;
- }
-
- /* Extend the node into the next chunk */
-
- oldnode->size = oldsize + takenext;
- newnode = (FAR struct mm_freenode_s *)((char*)oldnode + oldnode->size);
-
- /* Did we consume the entire preceding chunk? */
-
- if (takenext < nextsize)
- {
- /* No, take what we need from the next chunk and return it to
- * the free nodelist.
- */
-
- newnode->size = nextsize - takenext;
- newnode->preceding = oldnode->size;
- andbeyond->preceding = newnode->size | (andbeyond->preceding & MM_ALLOC_BIT);
-
- /* Add the new free node to the nodelist (with the new size) */
-
- mm_addfreechunk(newnode);
- }
- else
- {
- /* Yes, just update some pointers. */
-
- andbeyond->preceding = oldnode->size | (andbeyond->preceding & MM_ALLOC_BIT);
- }
- }
-
- mm_givesemaphore();
- return newmem;
- }
-
- /* The current chunk cannot be extended. Just allocate a new chunk and copy */
-
- else
- {
- /* Allocate a new block. On failure, realloc must return NULL but
- * leave the original memory in place.
- */
-
- mm_givesemaphore();
- newmem = (FAR void*)malloc(size);
- if (newmem)
- {
- memcpy(newmem, oldmem, oldsize);
- free(oldmem);
- }
-
- return newmem;
- }
-}
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