Gates: Modify appearance (#515)

Reduce actionqueue complexity, thus faster execution
Improve code style
Add documentation/explanations

.gitignore

@@ -1 +1,3 @@
 *~
+*.patch
+*.diff

mesecons/actionqueue.lua

@@ -1,96 +1,140 @@
-mesecon.queue.actions={} -- contains all ActionQueue actions
+--[[
+Mesecons uses something it calls an ActionQueue.
 
-function mesecon.queue:add_function(name, func)
-	mesecon.queue.funcs[name] = func
+The ActionQueue holds functions and actions.
+Functions are added on load time with a specified name.
+Actions are preserved over server restarts.
+
+Each action consists of a position, the name of an added function to be called,
+the params that should be used in this function call (additionally to the pos),
+the time after which it should be executed, an optional overwritecheck and a
+priority.
+
+If time = 0, the action will be executed in the next globalstep, otherwise the
+earliest globalstep when it will be executed is the after next globalstep.
+
+It is guaranteed, that for two actions ac1, ac2 where ac1 ~= ac2,
+ac1.time == ac2.time, ac1.priority == ac2.priority and ac1 was added earlier
+than ac2, ac1 will be executed before ac2 (but in the same globalstep).
+
+Note: Do not pass references in params, as they can not be preserved.
+
+Also note: Some of the guarantees here might be dropped at some time.
+]]
+
+
+-- localize for speed
+local queue = mesecon.queue
+
+queue.actions = {} -- contains all ActionQueue actions
+
+function queue:add_function(name, func)
+	queue.funcs[name] = func
 end
 
 -- If add_action with twice the same overwritecheck and same position are called, the first one is overwritten
 -- use overwritecheck nil to never overwrite, but just add the event to the queue
 -- priority specifies the order actions are executed within one globalstep, highest first
 -- should be between 0 and 1
-function mesecon.queue:add_action(pos, func, params, time, overwritecheck, priority)
+function queue:add_action(pos, func, params, time, overwritecheck, priority)
 	-- Create Action Table:
 	time = time or 0 -- time <= 0 --> execute, time > 0 --> wait time until execution
 	priority = priority or 1
-	local action = {	pos=mesecon.tablecopy(pos),
-				func=func,
-				params=mesecon.tablecopy(params or {}),
-				time=time,
-				owcheck=(overwritecheck and mesecon.tablecopy(overwritecheck)) or nil,
-				priority=priority}
+	local action = {
+		pos = mesecon.tablecopy(pos),
+		func = func,
+		params = mesecon.tablecopy(params or {}),
+		time = time,
+		owcheck = (overwritecheck and mesecon.tablecopy(overwritecheck)) or nil,
+		priority = priority
+	}
 
-	local toremove = nil
-	-- Otherwise, add the action to the queue
-	if overwritecheck then -- check if old action has to be overwritten / removed:
-		for i, ac in ipairs(mesecon.queue.actions) do
-			if(vector.equals(pos, ac.pos)
-			and mesecon.cmpAny(overwritecheck, ac.owcheck)) then
-				toremove = i
+	 -- check if old action has to be overwritten / removed:
+	if overwritecheck then
+		for i, ac in ipairs(queue.actions) do
+			if vector.equals(pos, ac.pos)
+					and mesecon.cmpAny(overwritecheck, ac.owcheck) then
+				-- remove the old action
+				table.remove(queue.actions, i)
 				break
 			end
 		end
 	end
 
-	if (toremove ~= nil) then
-		table.remove(mesecon.queue.actions, toremove)
-	end
-
-	table.insert(mesecon.queue.actions, action)
+	table.insert(queue.actions, action)
 end
 
 -- execute the stored functions on a globalstep
 -- if however, the pos of a function is not loaded (get_node_or_nil == nil), do NOT execute the function
--- this makes sure that resuming mesecons circuits when restarting minetest works fine
+-- this makes sure that resuming mesecons circuits when restarting minetest works fine (hm, where do we do this?)
 -- However, even that does not work in some cases, that's why we delay the time the globalsteps
--- start to be execute by 5 seconds
-local get_highest_priority = function (actions)
-	local highestp = -1
-	local highesti
-	for i, ac in ipairs(actions) do
-		if ac.priority > highestp then
-			highestp = ac.priority
-			highesti = i
-		end
-	end
+-- start to be execute by 4 seconds
 
-	return highesti
-end
+local function globalstep_func(dtime)
+	local actions = queue.actions
+	-- split into two categories:
+	-- actions_now: actions to execute now
+	-- queue.actions: actions to execute later
+	local actions_now = {}
+	queue.actions = {}
 
-local m_time = 0
-local resumetime = mesecon.setting("resumetime", 4)
-minetest.register_globalstep(function (dtime)
-	m_time = m_time + dtime
-	-- don't even try if server has not been running for XY seconds; resumetime = time to wait
-	-- after starting the server before processing the ActionQueue, don't set this too low
-	if (m_time < resumetime) then return end
-	local actions = mesecon.tablecopy(mesecon.queue.actions)
-	local actions_now={}
-
-	mesecon.queue.actions = {}
-
-	-- sort actions into two categories:
-	-- those toexecute now (actions_now) and those to execute later (mesecon.queue.actions)
-	for i, ac in ipairs(actions) do
+	for _, ac in ipairs(actions) do
 		if ac.time > 0 then
-			ac.time = ac.time - dtime -- executed later
-			table.insert(mesecon.queue.actions, ac)
+			-- action ac is to be executed later
+			-- ~> insert into queue.actions
+			ac.time = ac.time - dtime
+			table.insert(queue.actions, ac)
 		else
+			-- action ac is to be executed now
+			-- ~> insert into actions_now
 			table.insert(actions_now, ac)
 		end
 	end
 
-	while(#actions_now > 0) do -- execute highest priorities first, until all are executed
-		local hp = get_highest_priority(actions_now)
-		mesecon.queue:execute(actions_now[hp])
-		table.remove(actions_now, hp)
+	-- stable-sort the executed actions after their priority
+	-- some constructions might depend on the execution order, hence we first
+	-- execute the actions that had a lower index in actions_now
+	local old_action_order = {}
+	for i, ac in ipairs(actions_now) do
+		old_action_order[ac] = i
 	end
-end)
+	table.sort(actions_now, function(ac1, ac2)
+		if ac1.priority ~= ac2.priority then
+			return ac1.priority > ac2.priority
+		else
+			return old_action_order[ac1] < old_action_order[ac2]
+		end
+	end)
 
-function mesecon.queue:execute(action)
+	-- execute highest priorities first, until all are executed
+	for _, ac in ipairs(actions_now) do
+		queue:execute(ac)
+	end
+end
+
+-- delay the time the globalsteps start to be execute by 4 seconds
+do
+	local m_time = 0
+	local resumetime = mesecon.setting("resumetime", 4)
+	local globalstep_func_index = #minetest.registered_globalsteps + 1
+
+	minetest.register_globalstep(function(dtime)
+		m_time = m_time + dtime
+		-- don't even try if server has not been running for XY seconds; resumetime = time to wait
+		-- after starting the server before processing the ActionQueue, don't set this too low
+		if m_time < resumetime then
+			return
+		end
+		-- replace this globalstep function
+		minetest.registered_globalsteps[globalstep_func_index] = globalstep_func
+	end)
+end
+
+function queue:execute(action)
 	-- ignore if action queue function name doesn't exist,
 	-- (e.g. in case the action queue savegame was written by an old mesecons version)
-	if mesecon.queue.funcs[action.func] then
-		mesecon.queue.funcs[action.func](action.pos, unpack(action.params))
+	if queue.funcs[action.func] then
+		queue.funcs[action.func](action.pos, unpack(action.params))
 	end
 end
 
@@ -98,8 +142,8 @@ end
 -- Store and read the ActionQueue to / from a file
 -- so that upcoming actions are remembered when the game
 -- is restarted
-mesecon.queue.actions = mesecon.file2table("mesecon_actionqueue")
+queue.actions = mesecon.file2table("mesecon_actionqueue")
 
 minetest.register_on_shutdown(function()
-	mesecon.table2file("mesecon_actionqueue", mesecon.queue.actions)
+	mesecon.table2file("mesecon_actionqueue", queue.actions)
 end)

mesecons/util.lua

@@ -186,19 +186,11 @@ function mesecon.invertRule(r)
 	return vector.multiply(r, -1)
 end
 
-function mesecon.tablecopy(table) -- deep table copy
-	if type(table) ~= "table" then return table end -- no need to copy
-	local newtable = {}
-
-	for idx, item in pairs(table) do
-		if type(item) == "table" then
-			newtable[idx] = mesecon.tablecopy(item)
-		else
-			newtable[idx] = item
-		end
+function mesecon.tablecopy(obj) -- deep copy
+	if type(obj) == "table" then
+		return table.copy(obj)
 	end
-
-	return newtable
+	return obj
 end
 
 function mesecon.cmpAny(t1, t2)

mesecons_delayer/init.lua

@@ -33,19 +33,9 @@ end
 
 -- Register the 2 (states) x 4 (delay times) delayers
 
-for i = 1, 4 do
-local groups = {}
-if i == 1 then
-	groups = {bendy=2,snappy=1,dig_immediate=2}
-else
-	groups = {bendy=2,snappy=1,dig_immediate=2, not_in_creative_inventory=1}
-end
+local delaytime = { 0.1, 0.3, 0.5, 1.0 }
 
-local delaytime
-if 		i == 1 then delaytime = 0.1
-elseif	i == 2 then delaytime = 0.3
-elseif	i == 3 then delaytime = 0.5
-elseif	i == 4 then delaytime = 1.0 end
+for i = 1, 4 do
 
 local boxes = {
 	 { -6/16, -8/16, -6/16, 6/16, -7/16, 6/16 },		-- the main slab
@@ -61,19 +51,9 @@ local boxes = {
 	 { 6/16, -8/16, -1/16, 8/16, -7/16, 1/16 }
 }
 
-minetest.register_node("mesecons_delayer:delayer_off_"..tostring(i), {
-	description = "Delayer",
+-- Delayer definition defaults
+local def = {
 	drawtype = "nodebox",
-	tiles = {
-		"mesecons_delayer_off_"..tostring(i)..".png",
-		"mesecons_delayer_bottom.png",
-		"mesecons_delayer_ends_off.png",
-		"mesecons_delayer_ends_off.png",
-		"mesecons_delayer_sides_off.png",
-		"mesecons_delayer_sides_off.png"
-		},
-	inventory_image = "mesecons_delayer_off_1.png",
-	wield_image = "mesecons_delayer_off_1.png",
 	walkable = true,
 	selection_box = {
 		type = "fixed",
@@ -83,26 +63,46 @@ minetest.register_node("mesecons_delayer:delayer_off_"..tostring(i), {
 		type = "fixed",
 		fixed = boxes
 	},
-	groups = groups,
 	paramtype = "light",
 	paramtype2 = "facedir",
 	sunlight_propagates = true,
 	is_ground_content = false,
-	drop = 'mesecons_delayer:delayer_off_1',
-	on_punch = function (pos, node)
-		if node.name=="mesecons_delayer:delayer_off_1" then
-			minetest.swap_node(pos, {name = "mesecons_delayer:delayer_off_2", param2=node.param2})
-		elseif node.name=="mesecons_delayer:delayer_off_2" then
-			minetest.swap_node(pos, {name = "mesecons_delayer:delayer_off_3", param2=node.param2})
-		elseif node.name=="mesecons_delayer:delayer_off_3" then
-			minetest.swap_node(pos, {name = "mesecons_delayer:delayer_off_4", param2=node.param2})
-		elseif node.name=="mesecons_delayer:delayer_off_4" then
-			minetest.swap_node(pos, {name = "mesecons_delayer:delayer_off_1", param2=node.param2})
-		end
-	end,
-	delayer_time = delaytime,
-	delayer_onstate = "mesecons_delayer:delayer_on_"..tostring(i),
+	delayer_time = delaytime[i],
 	sounds = default.node_sound_stone_defaults(),
+	on_blast = mesecon.on_blastnode,
+	drop = "mesecons_delayer:delayer_off_1",
+}
+
+-- Deactivated delayer definition defaults
+local off_groups = {bendy=2,snappy=1,dig_immediate=2}
+if i > 1 then
+	off_groups.not_in_creative_inventory = 1
+end
+
+local off_state = {
+	description = "Delayer",
+	tiles = {
+		"mesecons_delayer_off_"..tostring(i)..".png",
+		"mesecons_delayer_bottom.png",
+		"mesecons_delayer_ends_off.png",
+		"mesecons_delayer_ends_off.png",
+		"mesecons_delayer_sides_off.png",
+		"mesecons_delayer_sides_off.png"
+	},
+	inventory_image = "mesecons_delayer_off_1.png",
+	wield_image = "mesecons_delayer_off_1.png",
+	groups = off_groups,
+	on_punch = function(pos, node, puncher)
+		if minetest.is_protected(pos, puncher and puncher:get_player_name()) then
+			return
+		end
+
+		minetest.swap_node(pos, {
+			name = "mesecons_delayer:delayer_off_"..tostring(i % 4 + 1),
+			param2 = node.param2
+		})
+	end,
+	delayer_onstate = "mesecons_delayer:delayer_on_"..tostring(i),
 	mesecons = {
 		receptor =
 		{
@@ -115,13 +115,15 @@ minetest.register_node("mesecons_delayer:delayer_off_"..tostring(i), {
 			action_on = delayer_activate
 		}
 	},
-	on_blast = mesecon.on_blastnode,
-})
+}
+for k, v in pairs(def) do
+	off_state[k] = off_state[k] or v
+end
+minetest.register_node("mesecons_delayer:delayer_off_"..tostring(i), off_state)
 
-
-minetest.register_node("mesecons_delayer:delayer_on_"..tostring(i), {
+-- Activated delayer definition defaults
+local on_state = {
 	description = "You hacker you",
-	drawtype = "nodebox",
 	tiles = {
 		"mesecons_delayer_on_"..tostring(i)..".png",
 		"mesecons_delayer_bottom.png",
@@ -129,36 +131,19 @@ minetest.register_node("mesecons_delayer:delayer_on_"..tostring(i), {
 		"mesecons_delayer_ends_on.png",
 		"mesecons_delayer_sides_on.png",
 		"mesecons_delayer_sides_on.png"
-		},
-	walkable = true,
-	selection_box = {
-		type = "fixed",
-		fixed = { -8/16, -8/16, -8/16, 8/16, -6/16, 8/16 },
-	},
-	node_box = {
-		type = "fixed",
-		fixed = boxes
 	},
 	groups = {bendy = 2, snappy = 1, dig_immediate = 2, not_in_creative_inventory = 1},
-	paramtype = "light",
-	paramtype2 = "facedir",
-	sunlight_propagates = true,
-	is_ground_content = false,
-	drop = 'mesecons_delayer:delayer_off_1',
-	on_punch = function (pos, node)
-		if node.name=="mesecons_delayer:delayer_on_1" then
-			minetest.swap_node(pos, {name = "mesecons_delayer:delayer_on_2", param2=node.param2})
-		elseif node.name=="mesecons_delayer:delayer_on_2" then
-			minetest.swap_node(pos, {name = "mesecons_delayer:delayer_on_3", param2=node.param2})
-		elseif node.name=="mesecons_delayer:delayer_on_3" then
-			minetest.swap_node(pos, {name = "mesecons_delayer:delayer_on_4", param2=node.param2})
-		elseif node.name=="mesecons_delayer:delayer_on_4" then
-			minetest.swap_node(pos, {name = "mesecons_delayer:delayer_on_1", param2=node.param2})
+	on_punch = function(pos, node, puncher)
+		if minetest.is_protected(pos, puncher and puncher:get_player_name()) then
+			return
 		end
+
+		minetest.swap_node(pos, {
+			name = "mesecons_delayer:delayer_on_"..tostring(i % 4 + 1),
+			param2 = node.param2
+		})
 	end,
-	delayer_time = delaytime,
 	delayer_offstate = "mesecons_delayer:delayer_off_"..tostring(i),
-	sounds = default.node_sound_stone_defaults(),
 	mesecons = {
 		receptor =
 		{
@@ -171,8 +156,12 @@ minetest.register_node("mesecons_delayer:delayer_on_"..tostring(i), {
 			action_off = delayer_deactivate
 		}
 	},
-	on_blast = mesecon.on_blastnode,
-})
+}
+for k, v in pairs(def) do
+	on_state[k] = on_state[k] or v
+end
+minetest.register_node("mesecons_delayer:delayer_on_"..tostring(i), on_state)
+
 end
 
 minetest.register_craft({

mesecons_detector/doc/nodedetector/description.html

@@ -1,8 +1,11 @@
 The node detector is a receptor. It changes its state when either any node
 or a specific node is detected. Right-click it to set a nodename to scan for.
-It can also receive digiline signals. You can either send "GET" and it will
-respond with the detected nodename or you can send any other string and it will
-set this string as the node to scan for.
+It can also receive digiline signals. For example, you can send
+<code>{distance=4, scanname="default:dirt"}</code>
+to set distance to 4 and scan for dirt. You can omit either parameter.
+There is also a command parameter: <code>{command="get"}</code> will respond
+with the detected nodename and <code>{command="scan"}</code> will respond with
+a boolean using the distance and nodename of the detector.
 Nodenames must include the mod they reside in, so for instance default:dirt, not just dirt.
 The distance parameter specifies how many blocks are between the node detector and the node to detect.
 Automatic scanning with Mesecons output only works when the detector is in an active block, but Digilines queries always work.

mesecons_detector/init.lua

@@ -189,28 +189,49 @@ local function node_detector_scan(pos)
 		(frontname ~= "air" and frontname ~= "ignore" and scanname == "")
 end
 
+local function node_detector_send_node_name(pos, node, channel, meta)
+	local distance = meta:get_int("distance")
+	local distance_max = mesecon.setting("node_detector_distance_max", 10)
+	if distance < 0 then distance = 0 end
+	if distance > distance_max then distance = distance_max end
+	local nodename = minetest.get_node(
+		vector.subtract(pos, vector.multiply(minetest.facedir_to_dir(node.param2), distance + 1))
+	).name
+
+	digiline:receptor_send(pos, digiline.rules.default, channel, nodename)
+end
+
 -- set player name when receiving a digiline signal on a specific channel
 local node_detector_digiline = {
 	effector = {
 		action = function(pos, node, channel, msg)
 			local meta = minetest.get_meta(pos)
 
-			local distance = meta:get_int("distance")
-			local distance_max = mesecon.setting("node_detector_distance_max", 10)
-			if distance < 0 then distance = 0 end
-			if distance > distance_max then distance = distance_max end
-
 			if channel ~= meta:get_string("digiline_channel") then return end
 
-			if msg == GET_COMMAND then
-				local nodename = minetest.get_node(
-					vector.subtract(pos, vector.multiply(minetest.facedir_to_dir(node.param2), distance + 1))
-				).name
-
-				digiline:receptor_send(pos, digiline.rules.default, channel, nodename)
+			if type(msg) == "table" then
+				if msg.distance or msg.scanname then
+					if msg.distance then
+						meta:set_string("distance", msg.distance)
+					end
+					if msg.scanname then
+						meta:set_string("scanname", msg.scanname)
+					end
+					node_detector_make_formspec(pos)
+				end
+				if msg.command == "get" then
+					node_detector_send_node_name(pos, node, channel, meta)
+				elseif msg.command == "scan" then
+					local result = node_detector_scan(pos)
+					digiline:receptor_send(pos, digiline.rules.default, channel, result)
+				end
 			else
-				meta:set_string("scanname", msg)
-				node_detector_make_formspec(pos)
+				if msg == GET_COMMAND then
+					node_detector_send_node_name(pos, node, channel, meta)
+				else
+					meta:set_string("scanname", msg)
+					node_detector_make_formspec(pos)
+				end
 			end
 		end,
 	},

mesecons_fpga/init.lua

@@ -1,10 +1,11 @@
 local plg = {}
 plg.rules = {}
+-- per-player formspec positions
+plg.open_formspecs = {}
 
 local lcore = dofile(minetest.get_modpath(minetest.get_current_modname()) .. "/logic.lua")
 dofile(minetest.get_modpath(minetest.get_current_modname()) .. "/tool.lua")(plg)
 
-
 plg.register_nodes = function(template)
 	-- each loop is for one of the 4 IO ports
 	for a = 0, 1 do
@@ -93,16 +94,20 @@ plg.register_nodes({
 
 		meta:set_string("instr", lcore.serialize(is))
 		meta:set_int("valid", 0)
-		meta:set_string("formspec", plg.to_formspec_string(is))
 		meta:set_string("infotext", "FPGA")
 	end,
-	on_receive_fields = function(pos, formname, fields, sender)
-		if fields.program == nil then return end -- we only care when the user clicks "Program"
+	on_rightclick = function(pos, node, clicker)
+		if not minetest.is_player(clicker) then
+			return
+		end
 		local meta = minetest.get_meta(pos)
-		local is = plg.from_formspec_fields(fields)
+		local name = clicker:get_player_name()
+		-- Erase formspecs of old FPGAs
+		meta:set_string("formspec", "")
 
-		meta:set_string("instr", lcore.serialize(is))
-		plg.update_formspec(pos, is)
+		plg.open_formspecs[name] = pos
+		local is = lcore.deserialize(meta:get_string("instr"))
+		minetest.show_formspec(name, "mesecons:fpga", plg.to_formspec_string(is, nil))
 	end,
 	sounds = default.node_sound_stone_defaults(),
 	mesecons = {
@@ -116,6 +121,12 @@ plg.register_nodes({
 	},
 	after_dig_node = function(pos, node)
 		mesecon.receptor_off(pos, plg.rules[node.name])
+		for name, open_pos in pairs(plg.open_formspecs) do
+			if vector.equals(pos, open_pos) then
+				minetest.close_formspec(name, "mesecons:fpga")
+				plg.open_formspecs[name] = nil
+			end
+		end
 	end,
 	on_blast = mesecon.on_blastnode,
 	on_rotate = function(pos, node, user, mode)
@@ -153,13 +164,12 @@ plg.register_nodes({
 		end
 
 		meta:set_string("instr", lcore.serialize(instr))
-		plg.update_formspec(pos, instr)
+		plg.update_meta(pos, instr)
 		return true
 	end,
 })
 
-
-plg.to_formspec_string = function(is)
+plg.to_formspec_string = function(is, err)
 	local function dropdown_op(x, y, name, val)
 		local s = "dropdown[" .. tostring(x) .. "," .. tostring(y) .. ";"
 				.. "0.75,0.5;" .. name .. ";" -- the height seems to be ignored?
@@ -180,26 +190,20 @@ plg.to_formspec_string = function(is)
 		return s .. "]"
 	end
 	local function dropdown_action(x, y, name, val)
-		local s = "dropdown[" .. tostring(x) .. "," .. tostring(y) .. ";"
-				.. "1.125,0.5;" .. name .. ";" -- the height seems to be ignored?
-		s = s .. " , AND,  OR, NOT, XOR,NAND,   =,XNOR;"
-		if val == nil then
-			return s .. "0]" -- actually selects no field at all
+		local selected = 0
+		local titles = { " " }
+		for i, data in ipairs(lcore.get_operations()) do
+			titles[i + 1] = data.fs_name
+			if val == data.gate then
+				selected = i + 1
+			end
 		end
-		local mapping = {
-			["and"] = 1,
-			["or"] = 2,
-			["not"] = 3,
-			["xor"] = 4,
-			["nand"] = 5,
-			["buf"] = 6,
-			["xnor"] = 7,
-		}
-		return s .. tostring(1 + mapping[val]) .. "]"
+		return ("dropdown[%f,%f;1.125,0.5;%s;%s;%i]"):format(
+			x, y, name, table.concat(titles, ","), selected)
 	end
 	local s = "size[9,9]"..
 		"label[3.4,-0.15;FPGA gate configuration]"..
-		"button_exit[7,7.5;2,2.5;program;Program]"..
+		"button[7,7.5;2,2.5;program;Program]"..
 		"box[4.2,0.5;0.03,7;#ffffff]"..
 		"label[0.25,0.25;op. 1]"..
 		"label[1.0,0.25;gate type]"..
@@ -225,6 +229,12 @@ plg.to_formspec_string = function(is)
 			y = 1 - 0.25
 		end
 	end
+	if err then
+		local fmsg = minetest.colorize("#ff0000", minetest.formspec_escape(err.msg))
+		s = s .. plg.red_box_around(err.i) ..
+			"label[0.25,8.25;The gate configuration is erroneous in the marked area:]"..
+			"label[0.25,8.5;" .. fmsg .. "]"
+	end
 	return s
 end
 
@@ -239,20 +249,11 @@ plg.from_formspec_fields = function(fields)
 		end
 	end
 	local function read_action(s)
-		if s == nil or s == " " then
-			return nil
+		for i, data in ipairs(lcore.get_operations()) do
+			if data.fs_name == s then
+				return data.gate
+			end
 		end
-		local mapping = {
-			["AND"] = "and",
-			["OR"] = "or",
-			["NOT"] = "not",
-			["XOR"] = "xor",
-			["NAND"] = "nand",
-			["="] = "buf",
-			["XNOR"] = "xnor",
-		}
-		s = s:gsub("^%s*", "") -- remove leading spaces
-		return mapping[s]
 	end
 	local is = {}
 	for i = 1, 14 do
@@ -266,12 +267,11 @@ plg.from_formspec_fields = function(fields)
 	return is
 end
 
-plg.update_formspec = function(pos, is)
+plg.update_meta = function(pos, is)
 	if type(is) == "string" then -- serialized string
 		is = lcore.deserialize(is)
 	end
 	local meta = minetest.get_meta(pos)
-	local form = plg.to_formspec_string(is)
 
 	local err = lcore.validate(is)
 	if err == nil then
@@ -280,17 +280,20 @@ plg.update_formspec = function(pos, is)
 	else
 		meta:set_int("valid", 0)
 		meta:set_string("infotext", "FPGA")
-		local fmsg = minetest.colorize("#ff0000", minetest.formspec_escape(err.msg))
-		form = form .. plg.red_box_around(err.i) ..
-			"label[0.25,8.25;The gate configuration is erroneous in the marked area:]"..
-			"label[0.25,8.5;" .. fmsg .. "]"
 	end
 
-	meta:set_string("formspec", form)
-
 	-- reset ports and run programmed logic
 	plg.setports(pos, false, false, false, false)
 	plg.update(pos)
+
+	-- Refresh open formspecs
+	local form = plg.to_formspec_string(is, err)
+	for name, open_pos in pairs(plg.open_formspecs) do
+		if vector.equals(pos, open_pos) then
+			minetest.show_formspec(name, "mesecons:fpga", form)
+		end
+	end
+	return err
 end
 
 plg.red_box_around = function(i)
@@ -409,6 +412,38 @@ plg.setports = function(pos, A, B, C, D) -- sets states of OUTPUT
 	end
 end
 
+minetest.register_on_player_receive_fields(function(player, formname, fields)
+	local player_name = player:get_player_name()
+
+	if formname ~= "mesecons:fpga" or fields.quit then
+		plg.open_formspecs[player_name] = nil -- potential garbage
+		return
+	end
+	if not fields.program then
+		return -- we only care when the user clicks "Program"
+	end
+	local pos = plg.open_formspecs[player_name]
+	if minetest.is_protected(pos, player_name) then
+		minetest.record_protection_violation(pos, player_name)
+		return
+	end
+
+	local meta = minetest.get_meta(pos)
+	local is = plg.from_formspec_fields(fields)
+
+	meta:set_string("instr", lcore.serialize(is))
+	local err = plg.update_meta(pos, is)
+
+	if not err then
+		plg.open_formspecs[player_name] = nil
+		-- Close on success
+		minetest.close_formspec(player_name, "mesecons:fpga")
+	end
+end)
+
+minetest.register_on_leaveplayer(function(player)
+	plg.open_formspecs[player:get_player_name()] = nil
+end)
 
 minetest.register_craft({
 	output = "mesecons_fpga:fpga0000 2",

mesecons_fpga/logic.lua

@@ -1,5 +1,27 @@
+
 local lg = {}
 
+local operations = {
+	-- table index: Index in the formspec dropdown
+	-- gate:    Internal name
+	-- short:   Serialized form, single character
+	-- fs_name: Display name, padded to 4 characters
+	-- func:    Function that applies the operation
+	-- unary:   Whether this gate only has one input
+	{ gate = "and",  short = "&", fs_name = " AND", func = function(a, b) return a and b end },
+	{ gate = "or",   short = "|", fs_name = "  OR", func = function(a, b) return a or b end },
+	{ gate = "not",  short = "~", fs_name = " NOT", func = function(a, b) return not b end, unary = true },
+	{ gate = "xor",  short = "^", fs_name = " XOR", func = function(a, b) return a ~= b end },
+	{ gate = "nand", short = "?", fs_name = "NAND", func = function(a, b) return not (a and b) end },
+	{ gate = "buf",  short = "_", fs_name = "   =", func = function(a, b) return b end, unary = true },
+	{ gate = "xnor", short = "=", fs_name = "XNOR", func = function(a, b) return a == b end },
+	{ gate = "nor",  short = "!", fs_name = " NOR", func = function(a, b) return not (a or b) end },
+}
+
+lg.get_operations = function()
+	return operations
+end
+
 -- (de)serialize
 lg.serialize = function(t)
 	local function _op(t)
@@ -11,20 +33,14 @@ lg.serialize = function(t)
 			return tostring(t.n)
 		end
 	end
-	local function _action(s)
-		if s == nil then
-			return " "
+	-- Serialize actions (gates) from eg. "and" to "&"
+	local function _action(action)
+		for i, data in ipairs(operations) do
+			if data.gate == action then
+				return data.short
+			end
 		end
-		local mapping = {
-			["and"] = "&",
-			["or"] = "|",
-			["not"] = "~",
-			["xor"] = "^",
-			["nand"] = "?", --dunno
-			["buf"] = "_",
-			["xnor"] = "=",
-		}
-		return mapping[s]
+		return " "
 	end
 
 	local s = ""
@@ -48,18 +64,14 @@ lg.deserialize = function(s)
 			return {type = "reg", n = tonumber(c)}
 		end
 	end
-	local function _action(c)
-		local mapping = {
-			["&"] = "and",
-			["|"] = "or",
-			["~"] = "not",
-			["^"] = "xor",
-			["?"] = "nand",
-			["_"] = "buf",
-			["="] = "xnor",
-			[" "] = nil,
-		}
-		return mapping[c]
+	-- Deserialize actions (gates) from eg. "&" to "and"
+	local function _action(action)
+		for i, data in ipairs(operations) do
+			if data.short == action then
+				return data.gate
+			end
+		end
+		-- nil
 	end
 
 	local ret = {}
@@ -109,16 +121,25 @@ lg.validate_single = function(t, i)
 		return false
 	end
 	local elem = t[i]
+
+	local gate_data
+	for j, data in ipairs(operations) do
+		if data.gate == elem.action then
+			gate_data = data
+			break
+		end
+	end
+
 	-- check for completeness
-	if elem.action == nil then
-		return {i = i, msg = "Gate type required"}
-	elseif elem.action == "not" or elem.action == "buf" then
+	if not gate_data then
+		return {i = i, msg = "Gate type is required"}
+	elseif gate_data.unary then
 		if elem.op1 ~= nil or elem.op2 == nil or elem.dst == nil then
-			return {i = i, msg = "Second operand (only) and destination required"}
+			return {i = i, msg = "Second operand (only) and destination are required"}
 		end
 	else
 		if elem.op1 == nil or elem.op2 == nil or elem.dst == nil then
-			return {i = i, msg = "Operands and destination required"}
+			return {i = i, msg = "Operands and destination are required"}
 		end
 	end
 	-- check whether operands/destination are identical
@@ -159,21 +180,12 @@ end
 -- interpreter
 lg.interpret = function(t, a, b, c, d)
 	local function _action(s, v1, v2)
-		if s == "and" then
-			return v1 and v2
-		elseif s == "or" then
-			return v1 or v2
-		elseif s == "not" then
-			return not v2
-		elseif s == "xor" then
-			return v1 ~= v2
-		elseif s == "nand" then
-			return not (v1 and v2)
-		elseif s == "buf" then
-			return v2
-		else -- s == "xnor"
-			return v1 == v2
+		for i, data in ipairs(operations) do
+			if data.gate == s then
+				return data.func(v1, v2)
+			end
 		end
+		return false -- unknown gate
 	end
 	local function _op(t, regs, io_in)
 		if t.type == "reg" then

mesecons_fpga/tool.lua

@@ -34,17 +34,22 @@ minetest.register_tool("mesecons_fpga:programmer", {
 		if minetest.get_node(pos).name:find("mesecons_fpga:fpga") ~= 1 then
 			return itemstack
 		end
+		local player_name = user:get_player_name()
+		if minetest.is_protected(pos, player_name) then
+			minetest.record_protection_violation(pos, player_name)
+			return itemstack
+		end
 
 		local imeta = itemstack:get_metadata()
 		if imeta == "" then
-			minetest.chat_send_player(user:get_player_name(), "Use shift+right-click to copy a gate configuration first.")
+			minetest.chat_send_player(player_name, "Use shift+right-click to copy a gate configuration first.")
 			return itemstack
 		end
 
 		local meta = minetest.get_meta(pos)
 		meta:set_string("instr", imeta)
-		plg.update_formspec(pos, imeta)
-		minetest.chat_send_player(user:get_player_name(), "Gate configuration was successfully written to FPGA!")
+		plg.update_meta(pos, imeta)
+		minetest.chat_send_player(player_name, "Gate configuration was successfully written to FPGA!")
 
 		return itemstack
 	end

mesecons_gates/init.lua

@@ -1,6 +1,14 @@
+local selection_box = {
+	type = "fixed",
+	fixed = { -8/16, -8/16, -8/16, 8/16, -6/16, 8/16 }
+}
+
 local nodebox = {
 	type = "fixed",
-	fixed = {{-8/16, -8/16, -8/16, 8/16, -7/16, 8/16 }},
+	fixed = {
+		{ -8/16, -8/16, -8/16, 8/16, -7/16, 8/16 }, -- bottom slab
+		{ -6/16, -7/16, -6/16, 6/16, -6/16, 6/16 }
+	},
 }
 
 local function gate_rotate_rules(node, rules)
@@ -68,7 +76,7 @@ local function register_gate(name, inputnumber, assess, recipe, description)
 		is_ground_content = false,
 		drawtype = "nodebox",
 		drop = basename.."_off",
-		selection_box = nodebox,
+		selection_box = selection_box,
 		node_box = nodebox,
 		walkable = true,
 		sounds = default.node_sound_stone_defaults(),
@@ -78,8 +86,16 @@ local function register_gate(name, inputnumber, assess, recipe, description)
 		inputnumber = inputnumber,
 		after_dig_node = mesecon.do_cooldown,
 	},{
-		tiles = {"jeija_microcontroller_bottom.png^".."jeija_gate_off.png^"..
-			"jeija_gate_"..name..".png"},
+		tiles = {
+			"jeija_microcontroller_bottom.png^".."jeija_gate_off.png^"..
+			"jeija_gate_output_off.png^".."jeija_gate_"..name..".png",
+			"jeija_microcontroller_bottom.png^".."jeija_gate_output_off.png^"..
+			"[transformFY",
+			"jeija_gate_side.png^".."jeija_gate_side_output_off.png",
+			"jeija_gate_side.png",
+			"jeija_gate_side.png",
+			"jeija_gate_side.png"
+		},
 		groups = {dig_immediate = 2, overheat = 1},
 		mesecons = { receptor = {
 			state = "off",
@@ -89,8 +105,16 @@ local function register_gate(name, inputnumber, assess, recipe, description)
 			action_change = update_gate
 		}}
 	},{
-		tiles = {"jeija_microcontroller_bottom.png^".."jeija_gate_on.png^"..
-			"jeija_gate_"..name..".png"},
+		tiles = {
+			"jeija_microcontroller_bottom.png^".."jeija_gate_on.png^"..
+			"jeija_gate_output_on.png^".."jeija_gate_"..name..".png",
+			"jeija_microcontroller_bottom.png^".."jeija_gate_output_on.png^"..
+			"[transformFY",
+			"jeija_gate_side.png^".."jeija_gate_side_output_on.png",
+			"jeija_gate_side.png",
+			"jeija_gate_side.png",
+			"jeija_gate_side.png"
+		},
 		groups = {dig_immediate = 2, not_in_creative_inventory = 1, overheat = 1},
 		mesecons = { receptor = {
 			state = "on",