Data Structures
===============

	heap
		top
		free_head
		free_tail
	block
		next_free
		user_data

Functions
=========

	malloc(heap)
		if heap->top unset
			heap->top = 0
			return 0
		elif heap->free_head unset
			return ++heap->top
		else
			block = heap->free_head
			if heap->free_head == heap->free_tail
				unset heap->free_head
				unset heap->free_tail
			else
				heap->free_head = heap->free_head->next_free
			return block
	free(heap, ptr)
		if heap->free_tail unset
			heap->free_head = heap->free_tail = ptr
		else
			heap->free_tail->next_free = ptr
			heap->free_tail = ptr

Return register:

	__mr