static void _Heap_Merge_below(
Heap_Control *heap,
uintptr_t extend_area_begin,
Heap_Block *first_block
)
{
uintptr_t const page_size = heap->page_size;
uintptr_t const new_first_block_alloc_begin =
_Heap_Align_up( extend_area_begin + HEAP_BLOCK_HEADER_SIZE, page_size );
uintptr_t const new_first_block_begin =
new_first_block_alloc_begin - HEAP_BLOCK_HEADER_SIZE;
uintptr_t const first_block_begin = (uintptr_t) first_block;
uintptr_t const new_first_block_size =
first_block_begin - new_first_block_begin;
Heap_Block *const new_first_block = (Heap_Block *) new_first_block_begin;
new_first_block->prev_size = first_block->prev_size;
new_first_block->size_and_flag = new_first_block_size | HEAP_PREV_BLOCK_USED;
_Heap_Free_block( heap, new_first_block );
}
void _Heap_Block_split(
Heap_Control *heap,
Heap_Block *block,
Heap_Block *free_list_anchor,
uintptr_t alloc_size
)
{
Heap_Statistics *const stats = &heap->stats;
uintptr_t const page_size = heap->page_size;
uintptr_t const min_block_size = heap->min_block_size;
uintptr_t const min_alloc_size = min_block_size - HEAP_BLOCK_HEADER_SIZE;
uintptr_t const block_size = _Heap_Block_size( block );
uintptr_t const used_size =
_Heap_Max( alloc_size, min_alloc_size ) + HEAP_BLOCK_HEADER_SIZE;
uintptr_t const used_block_size = _Heap_Align_up( used_size, page_size );
uintptr_t const free_size = block_size + HEAP_BLOCK_SIZE_OFFSET - used_size;
uintptr_t const free_size_limit = min_block_size + HEAP_BLOCK_SIZE_OFFSET;
Heap_Block *next_block = _Heap_Block_at( block, block_size );
_HAssert( used_size <= block_size + HEAP_BLOCK_SIZE_OFFSET );
_HAssert( used_size + free_size == block_size + HEAP_BLOCK_SIZE_OFFSET );
if ( free_size >= free_size_limit ) {
Heap_Block *const free_block = _Heap_Block_at( block, used_block_size );
uintptr_t free_block_size = block_size - used_block_size;
_HAssert( used_block_size + free_block_size == block_size );
_Heap_Block_set_size( block, used_block_size );
/* Statistics */
stats->free_size += free_block_size;
if ( _Heap_Is_used( next_block ) ) {
_Heap_Free_list_insert_after( free_list_anchor, free_block );
/* Statistics */
++stats->free_blocks;
} else {
uintptr_t const next_block_size = _Heap_Block_size( next_block );
_Heap_Free_list_replace( next_block, free_block );
free_block_size += next_block_size;
next_block = _Heap_Block_at( free_block, free_block_size );
}
free_block->size_and_flag = free_block_size | HEAP_PREV_BLOCK_USED;
next_block->prev_size = free_block_size;
next_block->size_and_flag &= ~HEAP_PREV_BLOCK_USED;
} else {
next_block->size_and_flag |= HEAP_PREV_BLOCK_USED;
}
}
uintptr_t _Heap_Initialize(
Heap_Control *heap,
void *heap_area_begin_ptr,
uintptr_t heap_area_size,
uintptr_t page_size
)
{
Heap_Statistics *const stats = &heap->stats;
uintptr_t const heap_area_begin = (uintptr_t) heap_area_begin_ptr;
uintptr_t const heap_area_end = heap_area_begin + heap_area_size;
uintptr_t alloc_area_begin = heap_area_begin + HEAP_BLOCK_HEADER_SIZE;
uintptr_t alloc_area_size = 0;
uintptr_t first_block_begin = 0;
uintptr_t first_block_size = 0;
uintptr_t min_block_size = 0;
uintptr_t overhead = 0;
Heap_Block *first_block = NULL;
Heap_Block *last_block = NULL;
if ( page_size == 0 ) {
page_size = CPU_ALIGNMENT;
} else {
page_size = _Heap_Align_up( page_size, CPU_ALIGNMENT );
if ( page_size < CPU_ALIGNMENT ) {
/* Integer overflow */
return 0;
}
}
min_block_size = _Heap_Align_up( sizeof( Heap_Block ), page_size );
alloc_area_begin = _Heap_Align_up( alloc_area_begin, page_size );
first_block_begin = alloc_area_begin - HEAP_BLOCK_HEADER_SIZE;
overhead = HEAP_BLOCK_HEADER_SIZE + (first_block_begin - heap_area_begin);
first_block_size = heap_area_size - overhead;
first_block_size = _Heap_Align_down ( first_block_size, page_size );
alloc_area_size = first_block_size - HEAP_BLOCK_HEADER_SIZE;
if (
heap_area_end < heap_area_begin
|| heap_area_size <= overhead
|| first_block_size < min_block_size
) {
/* Invalid area or area too small */
return 0;
}
/* First block */
first_block = (Heap_Block *) first_block_begin;
first_block->prev_size = page_size;
first_block->size_and_flag = first_block_size | HEAP_PREV_BLOCK_USED;
first_block->next = _Heap_Free_list_tail( heap );
first_block->prev = _Heap_Free_list_head( heap );
/*
* Last block.
*
* The next block of the last block is the first block. Since the first
* block indicates that the previous block is used, this ensures that the
* last block appears as used for the _Heap_Is_used() and _Heap_Is_free()
* functions.
*/
last_block = _Heap_Block_at( first_block, first_block_size );
last_block->prev_size = first_block_size;
last_block->size_and_flag = first_block_begin - (uintptr_t) last_block;
/* Heap control */
heap->page_size = page_size;
heap->min_block_size = min_block_size;
heap->area_begin = heap_area_begin;
heap->area_end = heap_area_end;
heap->first_block = first_block;
heap->last_block = last_block;
_Heap_Free_list_head( heap )->next = first_block;
_Heap_Free_list_tail( heap )->prev = first_block;
/* Statistics */
stats->size = first_block_size;
stats->free_size = first_block_size;
stats->min_free_size = first_block_size;
stats->free_blocks = 1;
stats->max_free_blocks = 1;
stats->used_blocks = 0;
stats->max_search = 0;
stats->allocs = 0;
stats->searches = 0;
stats->frees = 0;
stats->resizes = 0;
stats->instance = instance++;
_HAssert( _Heap_Is_aligned( heap->page_size, CPU_ALIGNMENT ) );
_HAssert( _Heap_Is_aligned( heap->min_block_size, page_size ) );
_HAssert(
_Heap_Is_aligned( _Heap_Alloc_area_of_block( first_block ), page_size )
);
_HAssert(
_Heap_Is_aligned( _Heap_Alloc_area_of_block( last_block ), page_size )
);
return alloc_area_size;
}
