minetest.swap_node = minetest.swap_node or function(pos, node)
	local data = minetest.get_meta(pos):to_table()
	minetest.add_node(pos, node)
	minetest.get_meta(pos):from_table(data)
end

local rules = {}
rules.a = {x = -1, y = 0, z =  0, name="A"}
rules.b = {x =  0, y = 0, z =  1, name="B"}
rules.c = {x =  1, y = 0, z =  0, name="C"}
rules.d = {x =  0, y = 0, z = -1, name="D"}

function legacy_update_ports(pos)
	local meta = minetest.get_meta(pos)
	L = {
		a = mesecon:is_power_on(mesecon:addPosRule(pos, rules.a),
			mesecon:invertRule(rules.a)) and
			mesecon:rules_link(mesecon:addPosRule(pos, rules.a), pos),
		b = mesecon:is_power_on(mesecon:addPosRule(pos, rules.b),
			mesecon:invertRule(rules.b)) and
			mesecon:rules_link(mesecon:addPosRule(pos, rules.b), pos),
		c = mesecon:is_power_on(mesecon:addPosRule(pos, rules.c),
			mesecon:invertRule(rules.c)) and
			mesecon:rules_link(mesecon:addPosRule(pos, rules.c), pos),
		d = mesecon:is_power_on(mesecon:addPosRule(pos, rules.d),
			mesecon:invertRule(rules.d)) and
			mesecon:rules_link(mesecon:addPosRule(pos, rules.d), pos),
	}
	local n = (L.a and 1 or 0) + (L.b and 2 or 0) + (L.c and 4 or 0) + (L.d and 8 or 0) + 1
	meta:set_int("real_portstates", n)
	return L
end