100 lines
3.1 KiB
C
100 lines
3.1 KiB
C
/****************************************************************************
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* mm/umm_heap/umm_realloc.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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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#include <nuttx/config.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <nuttx/mm/mm.h>
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#include "umm_heap/umm_heap.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: realloc
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*
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* Description:
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* Re-allocate memory in the user heap.
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*
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* Input Parameters:
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* oldmem - The old memory allocated
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* newsize - Size (in bytes) of the new memory region to be re-allocated.
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*
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* Returned Value:
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* The address of the re-allocated memory (NULL on failure to re-allocate)
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*
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****************************************************************************/
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#undef realloc /* See mm/README.txt */
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FAR void *realloc(FAR void *oldmem, size_t size)
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{
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#if defined(CONFIG_ARCH_ADDRENV) && defined(CONFIG_BUILD_KERNEL)
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FAR void *brkaddr;
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FAR void *mem;
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if (size < 1)
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{
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mm_free(USR_HEAP, oldmem);
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return NULL;
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}
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/* Initialize the user heap if it wasn't yet */
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umm_try_initialize();
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/* Loop until we successfully allocate the memory or until an error
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* occurs. If we fail to allocate memory on the first pass, then call
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* sbrk to extend the heap by one page. This may require several
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* passes if more the size of the allocation is more than one page.
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*
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* An alternative would be to increase the size of the heap by the
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* full requested allocation in sbrk(). Then the loop should never
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* execute more than twice (but more memory than we need may be
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* allocated).
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*/
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do
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{
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mem = mm_realloc(USR_HEAP, oldmem, size);
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if (!mem)
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{
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brkaddr = sbrk(size);
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if (brkaddr == (FAR void *)-1)
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{
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return NULL;
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}
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}
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}
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while (mem == NULL);
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return mem;
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#else
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return mm_realloc(USR_HEAP, oldmem, size);
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#endif
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}
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