static Heap_Resize_status _Heap_Resize_block_checked(
Heap_Control *heap,
Heap_Block *block,
uintptr_t alloc_begin,
uintptr_t new_alloc_size,
uintptr_t *old_size,
uintptr_t *new_size
)
{
Heap_Statistics *const stats = &heap->stats;
uintptr_t const block_begin = (uintptr_t) block;
uintptr_t block_size = _Heap_Block_size( block );
uintptr_t block_end = block_begin + block_size;
uintptr_t alloc_size = block_end - alloc_begin + HEAP_ALLOC_BONUS;
Heap_Block *next_block = _Heap_Block_at( block, block_size );
uintptr_t next_block_size = _Heap_Block_size( next_block );
bool next_block_is_free = _Heap_Is_free( next_block );
_HAssert( _Heap_Is_block_in_heap( heap, next_block ) );
_HAssert( _Heap_Is_prev_used( next_block ) );
*old_size = alloc_size;
if ( next_block_is_free ) {
block_size += next_block_size;
alloc_size += next_block_size;
}
if ( new_alloc_size > alloc_size ) {
return HEAP_RESIZE_UNSATISFIED;
}
if ( next_block_is_free ) {
_Heap_Block_set_size( block, block_size );
_Heap_Free_list_remove( next_block );
next_block = _Heap_Block_at( block, block_size );
next_block->size_and_flag |= HEAP_PREV_BLOCK_USED;
/* Statistics */
--stats->free_blocks;
stats->free_size -= next_block_size;
}
block = _Heap_Block_allocate( heap, block, alloc_begin, new_alloc_size );
block_size = _Heap_Block_size( block );
next_block = _Heap_Block_at( block, block_size );
*new_size = (uintptr_t) next_block - alloc_begin + HEAP_ALLOC_BONUS;
/* Statistics */
++stats->resizes;
return HEAP_RESIZE_SUCCESSFUL;
}
static void _Heap_Link_above(
Heap_Block *link,
Heap_Block *first_block,
Heap_Block *last_block
)
{
uintptr_t const link_begin = (uintptr_t) link;
uintptr_t const first_block_begin = (uintptr_t) first_block;
_Heap_Block_set_size( link, first_block_begin - link_begin );
last_block->size_and_flag |= HEAP_PREV_BLOCK_USED;
}
static void _Heap_Merge_above(
Heap_Control *heap,
Heap_Block *last_block,
uintptr_t extend_area_end
)
{
uintptr_t const page_size = heap->page_size;
uintptr_t const last_block_begin = (uintptr_t) last_block;
uintptr_t const last_block_new_size = _Heap_Align_down(
extend_area_end - last_block_begin - HEAP_BLOCK_HEADER_SIZE,
page_size
);
Heap_Block *const new_last_block =
_Heap_Block_at( last_block, last_block_new_size );
new_last_block->size_and_flag =
(last_block->size_and_flag - last_block_new_size)
| HEAP_PREV_BLOCK_USED;
_Heap_Block_set_size( last_block, last_block_new_size );
_Heap_Free_block( heap, last_block );
}
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;
}
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;
}
}
