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/*
* Heap Handler
*
* 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>
/*PAGE
*
* _Heap_Allocate
*
* This kernel routine allocates the requested size of memory
* from the specified heap.
*
* Input parameters:
* the_heap - pointer to heap header.
* size - size in bytes of the memory block to allocate.
*
* Output parameters:
* returns - starting address of memory block allocated
*/
void *_Heap_Allocate(
Heap_Control *the_heap,
uint32_t size
)
{
uint32_t the_size;
uint32_t search_count;
Heap_Block *the_block;
void *ptr = NULL;
Heap_Statistics *const stats = &the_heap->stats;
Heap_Block *const tail = _Heap_Tail(the_heap);
the_size =
_Heap_Calc_block_size(size, the_heap->page_size, the_heap->min_block_size);
if(the_size == 0)
return NULL;
/* Find large enough free block. */
for(the_block = _Heap_First(the_heap), search_count = 0;
the_block != tail;
the_block = the_block->next, ++search_count)
{
/* As we always coalesce free blocks, prev block must have been used. */
_HAssert(_Heap_Is_prev_used(the_block));
/* Don't bother to mask out the HEAP_PREV_USED bit as it won't change the
result of the comparison. */
if(the_block->size >= the_size) {
(void)_Heap_Block_allocate(the_heap, the_block, the_size );
ptr = _Heap_User_area(the_block);
stats->allocs += 1;
stats->searches += search_count + 1;
_HAssert(_Heap_Is_aligned_ptr(ptr, the_heap->page_size));
break;
}
}
if(stats->max_search < search_count)
stats->max_search = search_count;
return ptr;
}
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