////////////////////////////////////////////////////////////////////////////////
// De-allocation/free() related functions

// REQUIRED
// Attempt to merge the block lower with the next block in
// memory. Does nothing if lower is null or not EL_AVAILABLE and does
// nothing if the next higher block is null (because lower is the last
// block) or not EL_AVAILABLE.  Otherwise, locates the next block with
// el_block_above() and merges these two into a single block. Adjusts
// the fields of lower to incorporate the size of higher block and the
// reclaimed overhead. Adjusts footer of higher to indicate the two
// blocks are merged.  Removes both lower and higher from the
// available list and re-adds lower to the front of the available
// list.
void el_merge_block_with_above(el_blockhead_t *lower){
	printf("merging... \n");
	printf("lower size: %lu\n", lower->size);
	if (lower == NULL || lower->state != EL_AVAILABLE) {printf("lower isn't available.\n"); return; }

	el_blockhead_t *higher = el_block_above(lower);

	if (higher == NULL || higher->state != EL_AVAILABLE) {
		printf("higher isn't available.\n");
		el_remove_block(el_ctl.used, lower);
		el_add_block_front(el_ctl.avail, lower);
		return;
	}

	el_blockfoot_t *hi_foot = el_get_footer(higher);

	el_remove_block(el_ctl.used, lower);

	printf("higher size: %lu\n", higher->size);

	el_remove_block(el_ctl.avail, higher);

	hi_foot->size = lower->size + higher->size + EL_BLOCK_OVERHEAD;

	lower->size = lower->size + higher->size + EL_BLOCK_OVERHEAD;

	el_add_block_front(el_ctl.avail, lower);
	printf("new size: %lu=%lu\n",  hi_foot->size, lower->size);
}

void el_merge_block_with_below(el_blockhead_t *higher){
	printf("merging below...\n");
	printf("higher size: %lu\n", higher->size);
	printf("higher loc: %lu\n",  PTR_MINUS_PTR(higher, el_ctl.heap_start));

	if (higher == NULL || higher->state != EL_AVAILABLE) {printf("higher isn't available.\n"); return; }

	el_blockhead_t *lower = el_block_below(higher);

	//printf("%lu\n", PTR_MINUS_PTR(PTR_MINUS_BYTES(lower, 1),el_ctl.heap_start));

	printf("lower loc: %lu\n",  PTR_MINUS_PTR(lower, el_ctl.heap_start));

	if (lower == NULL || lower->state != EL_AVAILABLE) {
		printf("lower isn't available.\n");
		return;
	}

	el_blockfoot_t *hi_foot = el_get_footer(higher);

	printf("lower size: %lu\n", lower->size);

	el_remove_block(el_ctl.avail, lower);

	el_remove_block(el_ctl.avail, higher);

	hi_foot->size = lower->size + higher->size + EL_BLOCK_OVERHEAD;

	lower->size = lower->size + higher->size + EL_BLOCK_OVERHEAD;

	el_add_block_front(el_ctl.avail, lower);

	printf("new size: %lu=%lu\n",  hi_foot->size, lower->size);

}

// REQUIRED
// Free the block pointed to by the give ptr.  The area immediately
// preceding the pointer should contain an el_blockhead_t with information
// on the block size. Attempts to merge the free'd block with adjacent
// blocks using el_merge_block_with_above().
void el_free(void *ptr){
	printf("freeing... \n");
	el_blockhead_t *block =  PTR_MINUS_BYTES(ptr, sizeof(el_blockhead_t));

	if(block->state != EL_USED){
		return;
	}

	block->state = EL_AVAILABLE;

	el_merge_block_with_above(block);

	el_merge_block_with_below(block);
}