klish/lub/heap/heap_extend_both_ways.c

#include <assert.h>
#include "private.h"

/*--------------------------------------------------------- */
bool_t
lub_heap_extend_both_ways(lub_heap_t * this,
			  lub_heap_block_t ** ptr_block, const words_t words)
{
	lub_heap_block_t *block = *ptr_block;
	lub_heap_free_block_t *prev_block =
	    (lub_heap_free_block_t *) lub_heap_block_getprevious(block);
	lub_heap_free_block_t *next_block =
	    (lub_heap_free_block_t *) lub_heap_block_getnext(block);
	bool_t result = BOOL_FALSE;

	if (prev_block && prev_block->tag.free && next_block
	    && next_block->tag.free) {
		/* OK we have a free block above and below us */
		if (words <= (prev_block->tag.words + next_block->tag.words)) {
			/* There is sufficient space to extend */
			words_t delta = words - next_block->tag.words;
			/* maximise the upward extension */
			result = lub_heap_extend_downwards(this, &block, delta);
			assert(BOOL_TRUE == result);
			result =
			    lub_heap_extend_upwards(this, &block,
						    next_block->tag.words);
			assert(BOOL_TRUE == result);
		}
	}
	return result;
}

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