58 lines
1.9 KiB
C
58 lines
1.9 KiB
C
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/****************************************************************************
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* mm/mm_heap/mm_malloc_usable_size.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 <assert.h>
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#include <debug.h>
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#include <malloc.h>
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#include <nuttx/mm/mm.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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size_t malloc_usable_size(FAR void *mem)
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{
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FAR struct mm_freenode_s *node;
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/* Protect against attempts to query a NULL reference */
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if (!mem)
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{
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return 0;
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}
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/* Map the memory chunk into a free node */
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node = (FAR struct mm_freenode_s *)((FAR char *)mem - SIZEOF_MM_ALLOCNODE);
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/* Sanity check against double-frees */
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DEBUGASSERT(node->preceding & MM_ALLOC_BIT);
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return node->size - SIZEOF_MM_ALLOCNODE;
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}
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