Store gate inputs in param2 instead of metadata (#583)

mesecons_gates/init.lua

@@ -23,17 +23,19 @@ local gate_get_input_rules_twoinputs = mesecon.horiz_rules_getter({
 local function set_gate(pos, node, state)
 	local gate = minetest.registered_nodes[node.name]
 
+	local new_nodename = state and gate.onstate or gate.offstate
+	minetest.swap_node(pos, {name = new_nodename, param2 = node.param2})
+	if new_nodename ~= node.name then
 		if mesecon.do_overheat(pos) then
 			minetest.remove_node(pos)
 			mesecon.receptor_off(pos, gate_get_output_rules(node))
 			minetest.add_item(pos, gate.drop)
 		elseif state then
-		minetest.swap_node(pos, {name = gate.onstate, param2=node.param2})
 			mesecon.receptor_on(pos, gate_get_output_rules(node))
 		else
-		minetest.swap_node(pos, {name = gate.offstate, param2=node.param2})
 			mesecon.receptor_off(pos, gate_get_output_rules(node))
 		end
+	end
 end
 
 local function update_gate(pos, node, link, newstate)
@@ -42,11 +44,36 @@ local function update_gate(pos, node, link, newstate)
 	if gate.inputnumber == 1 then
 		set_gate(pos, node, gate.assess(newstate == "on"))
 	elseif gate.inputnumber == 2 then
+		-- Inputs are stored in param2. Bit 5 is always set.
+		-- input1 is bit 6 and input2 is bit 7.
+		local val1, val2
+		if node.param2 >= 32 then
+			-- Bit 5 is set, so param2 is in the proper format.
+			if link.name == "input1" then
+				val1 = newstate == "on"
+				val2 = node.param2 >= 128
+			else
+				val1 = node.param2 % 128 >= 64
+				val2 = newstate == "on"
+			end
+		else
+			-- Migrate old gates where the inputs are stored as metadata.
+			-- This also triggers for newly placed gates.
 			local meta = minetest.get_meta(pos)
-		meta:set_int(link.name, newstate == "on" and 1 or 0)
+			if link.name == "input1" then
-
+				val1 = newstate == "on"
-		local val1 = meta:get_int("input1") == 1
+				val2 = meta:get_int("input2") == 1
-		local val2 = meta:get_int("input2") == 1
+			else
+				val1 = meta:get_int("input1") == 1
+				val2 = newstate == "on"
+			end
+			-- Set bit 5 so this won't happen again.
+			node.param2 = node.param2 + 32
+			-- Clear the metadata.
+			meta:set_string("input1", "")
+			meta:set_string("input2", "")
+		end
+		node.param2 = node.param2 % 64 + (val1 and 64 or 0) + (val2 and 128 or 0)
 		set_gate(pos, node, gate.assess(val1, val2))
 	end
 end