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/**
* @file
*
* @ingroup ScoreHeap
*
* @brief Heap Handler implementation.
*/
/*
* COPYRIGHT (c) 1989-1999.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*
* $Id$
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <rtems/system.h>
#include <rtems/score/sysstate.h>
#include <rtems/score/heap.h>
Heap_Extend_status _Heap_Extend(
Heap_Control *heap,
void *area_begin_ptr,
uintptr_t area_size,
uintptr_t *amount_extended
)
{
Heap_Statistics *const stats = &heap->stats;
uintptr_t const area_begin = (uintptr_t) area_begin_ptr;
uintptr_t const heap_area_begin = heap->area_begin;
uintptr_t const heap_area_end = heap->area_end;
uintptr_t const new_heap_area_end = heap_area_end + area_size;
uintptr_t extend_size = 0;
Heap_Block *const last_block = heap->last_block;
/*
* There are five possibilities for the location of starting
* address:
*
* 1. non-contiguous lower address (NOT SUPPORTED)
* 2. contiguous lower address (NOT SUPPORTED)
* 3. in the heap (ERROR)
* 4. contiguous higher address (SUPPORTED)
* 5. non-contiguous higher address (NOT SUPPORTED)
*
* As noted, this code only supports (4).
*/
if ( area_begin >= heap_area_begin && area_begin < heap_area_end ) {
return HEAP_EXTEND_ERROR; /* case 3 */
} else if ( area_begin != heap_area_end ) {
return HEAP_EXTEND_NOT_IMPLEMENTED; /* cases 1, 2, and 5 */
}
/*
* Currently only case 4 should make it to this point.
* The basic trick is to make the extend area look like a used
* block and free it.
*/
heap->area_end = new_heap_area_end;
extend_size = new_heap_area_end
- (uintptr_t) last_block - HEAP_BLOCK_HEADER_SIZE;
extend_size = _Heap_Align_down( extend_size, heap->page_size );
*amount_extended = extend_size;
if( extend_size >= heap->min_block_size ) {
Heap_Block *const new_last_block = _Heap_Block_at( last_block, extend_size );
_Heap_Block_set_size( last_block, extend_size );
new_last_block->size_and_flag =
((uintptr_t) heap->first_block - (uintptr_t) new_last_block)
| HEAP_PREV_BLOCK_USED;
heap->last_block = new_last_block;
/* Statistics */
stats->size += extend_size;
++stats->used_blocks;
--stats->frees; /* Do not count subsequent call as actual free() */
_Heap_Free( heap, (void *) _Heap_Alloc_area_of_block( last_block ));
}
return HEAP_EXTEND_SUCCESSFUL;
}
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