128 lines
4.5 KiB
C
128 lines
4.5 KiB
C
/****************************************************************************
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* mm/mm_heap/mm_extend.c
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*
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* Copyright (C) 2014 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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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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* 3. Neither the name NuttX nor the names of its contributors may be
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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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#include <nuttx/config.h>
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#include <assert.h>
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#include <nuttx/mm/mm.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define MIN_EXTEND (2 * SIZEOF_MM_ALLOCNODE)
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mm_extend
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*
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* Description:
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* Extend a heap region by add a block of (virtually) contiguous memory
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* to the end of the heap.
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*
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****************************************************************************/
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void mm_extend(FAR struct mm_heap_s *heap, FAR void *mem, size_t size,
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int region)
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{
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struct mm_allocnode_s *oldnode;
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struct mm_allocnode_s *newnode;
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uintptr_t blockstart;
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uintptr_t blockend;
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/* Make sure that we were passed valid parameters */
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DEBUGASSERT(heap && mem);
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#if CONFIG_MM_REGIONS > 1
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DEBUGASSERT(size >= MIN_EXTEND && (unsigned)region < heap->mm_nregions);
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#else
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DEBUGASSERT(size >= MIN_EXTEND && (unsigned)region == 0);
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#endif
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/* Make sure that the memory region are properly aligned */
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blockstart = (uintptr_t)mem;
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blockend = blockstart + size;
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DEBUGASSERT(MM_ALIGN_UP(blockstart) == blockstart);
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DEBUGASSERT(MM_ALIGN_DOWN(blockend) == blockend);
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/* Take the memory manager semaphore */
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mm_takesemaphore(heap);
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/* Get the terminal node in the old heap. The block to extend must
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* immediately follow this node.
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*/
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oldnode = heap->mm_heapend[region];
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DEBUGASSERT((uintptr_t)oldnode + SIZEOF_MM_ALLOCNODE == (uintptr_t)mem);
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/* The size of the old node now extends to the new terminal node.
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* This is the old size (SIZEOF_MM_ALLOCNODE) plus the size of
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* the block (size) minus the size of the new terminal node
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* (SIZEOF_MM_ALLOCNODE) or simply:
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*/
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oldnode->size = size;
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/* The old node should already be marked as allocated */
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DEBUGASSERT((oldnode->preceding & MM_ALLOC_BIT) != 0);
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/* Get and initialize the new terminal node in the heap */
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newnode = (FAR struct mm_allocnode_s *)(blockend - SIZEOF_MM_ALLOCNODE);
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newnode->size = SIZEOF_MM_ALLOCNODE;
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newnode->preceding = oldnode->size | MM_ALLOC_BIT;
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heap->mm_heapend[region] = newnode;
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mm_givesemaphore(heap);
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/* Finally "free" the new block of memory where the old terminal node was
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* located.
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*/
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mm_free(heap, (FAR void *)mem);
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}
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