klish/lub/heap/heap_extend_upwards.c

#include "private.h"
/*--------------------------------------------------------- */
bool_t
lub_heap_extend_upwards(lub_heap_t * this,
			lub_heap_block_t ** ptr_block, words_t words)
{
	lub_heap_block_t *block = *ptr_block;
	lub_heap_free_block_t *next_block =
	    (lub_heap_free_block_t *) lub_heap_block_getnext(block);
	bool_t result = BOOL_FALSE;

	if (NULL != next_block) {
		/* Do we have a free block above us? */
		if (1 == next_block->tag.free) {
			int segment;
			void *tmp;
			lub_heap_tag_t *tail =
			    lub_heap_block__get_tail((lub_heap_block_t *)
						     next_block);

			/* work out how many extra words we need */
			words -= block->alloc.tag.words;

			/* remove the block from the tree */
			lub_bintree_remove(&this->free_tree, next_block);

			/* remember the segment status of the next block */
			segment = tail->segment;

			/* try and slice off a chunk of memory */
			tmp =
			    lub_heap_slice_from_bottom(this, &next_block,
						       &words, BOOL_FALSE);

			if (NULL != next_block) {
				/* put the modified free block back into the tree */
				lub_bintree_insert(&this->free_tree,
						   next_block);

				/* there is still a block above us */
				segment = 0;
			}
			if (NULL != tmp) {
				/* we managed to extend upwards */
				result = BOOL_TRUE;

				/* taint the old tail pointer */
				tail = lub_heap_block__get_tail(block);
				lub_heap_taint_memory((char *)tail,
						      LUB_HEAP_TAINT_ALLOC,
						      sizeof(lub_heap_tag_t));

				/* fill out the new block details */
				block->alloc.tag.words += words;
				this->stats.alloc_bytes += (words << 2);
				this->stats.alloc_total_bytes += (words << 2);

				tail = lub_heap_block__get_tail(block);
				tail->segment = segment;
				tail->free = 0;
				tail->words = block->alloc.tag.words;
			}
		}
	}
	return result;
}

/*--------------------------------------------------------- */