From ea33ad9de0a77887f0181d8581568fe79d14255e Mon Sep 17 00:00:00 2001
From: orwell96 <orwell@bleipb.de>
Date: Tue, 16 Apr 2019 09:16:44 +0200
Subject: Move LZB system to core and unify approach callback mechanism

---
 advtrains/api_doc.txt                  |   3 +-
 advtrains/init.lua                     |   3 +
 advtrains/lzb.lua                      | 192 ++++++++++++++++++++++
 advtrains/trainlogic.lua               |  24 ++-
 advtrains/wagons.lua                   |   4 +-
 advtrains_interlocking/approach.lua    | 113 +++++++++++++
 advtrains_interlocking/init.lua        |   2 +-
 advtrains_interlocking/lzb.lua         | 292 ---------------------------------
 advtrains_interlocking/signal_api.lua  |   4 +-
 advtrains_interlocking/tsr_rail.lua    |   2 +-
 advtrains_line_automation/stoprail.lua |   2 +-
 11 files changed, 339 insertions(+), 302 deletions(-)
 create mode 100644 advtrains/lzb.lua
 create mode 100644 advtrains_interlocking/approach.lua
 delete mode 100644 advtrains_interlocking/lzb.lua

diff --git a/advtrains/api_doc.txt b/advtrains/api_doc.txt
index 0a2cb44..34f1beb 100644
--- a/advtrains/api_doc.txt
+++ b/advtrains/api_doc.txt
@@ -180,8 +180,9 @@ minetest.register_node(nodename, {
 		^- called when a train leaves the rail
 		
 		-- The following function is only in effect when interlocking is enabled:
-		on_train_approach = function(pos, train_id, train, index)
+		on_train_approach = function(pos, train_id, train, index, lzbdata)
 		^- called when a train is approaching this position, called exactly once for every path recalculation (which can happen at any time)
 		^- This is called so that if the train would start braking now, it would come to halt about(wide approx) 5 nodes before the rail.
+		^- lzbdata should be ignored and nothing should be assigned to it
 	}
 })
diff --git a/advtrains/init.lua b/advtrains/init.lua
index 14a5a02..4e5ae90 100644
--- a/advtrains/init.lua
+++ b/advtrains/init.lua
@@ -25,6 +25,7 @@ local no_action=false
 local function reload_saves()
 	atwarn("Restoring saved state in 1 second...")
 	no_action=true
+	advtrains.lock_path_inval = false
 	--read last save state and continue, as if server was restarted
 	for aoi, le in pairs(minetest.luaentities) do
 		if le.is_wagon then
@@ -192,6 +193,8 @@ dofile(advtrains.modpath.."/craft_items.lua")
 dofile(advtrains.modpath.."/log.lua")
 dofile(advtrains.modpath.."/passive.lua")
 
+dofile(advtrains.modpath.."/lzb.lua")
+
 
 --load/save
 
diff --git a/advtrains/lzb.lua b/advtrains/lzb.lua
new file mode 100644
index 0000000..efbce66
--- /dev/null
+++ b/advtrains/lzb.lua
@@ -0,0 +1,192 @@
+-- lzb.lua
+-- Enforced and/or automatic train override control, providing the on_train_approach callback
+
+--[[
+Documentation of train.lzb table
+train.lzb = {
+	trav = Current index that the traverser has advanced so far
+	oncoming = table containing oncoming signals, in order of appearance on the path
+		{
+			pos = position of the point
+			idx = where this is on the path
+			spd = speed allowed to pass
+			fun = function(pos, id, train, index, speed, lzbdata)
+			-- Function that determines what to do on the train in the moment it drives over that point.
+		}
+}
+each step, for every item in "oncoming", we need to determine the location to start braking (+ some safety margin)
+and, if we passed this point for at least one of the items, initiate brake.
+When speed has dropped below, say 3, decrease the margin to zero, so that trains actually stop at the signal IP.
+The spd variable and travsht need to be updated on every aspect change. it's probably best to reset everything when any aspect changes
+]]
+
+
+local params = {
+	BRAKE_SPACE = 10,
+	AWARE_ZONE  = 50,
+
+	ADD_STAND  =  2.5,
+	ADD_SLOW   =  1.5,
+	ADD_FAST   =  7,
+	ZONE_ROLL  =  2,
+	ZONE_HOLD  =  5, -- added on top of ZONE_ROLL
+	ZONE_VSLOW =  3, -- When speed is <2, still allow accelerating
+
+	DST_FACTOR =  1.5,
+
+	SHUNT_SPEED_MAX = advtrains.SHUNT_SPEED_MAX,
+}
+
+function advtrains.set_lzb_param(par, val)
+	if params[par] and tonumber(val) then
+		params[par] = tonumber(val)
+	else
+		error("Inexistant param or not a number")
+	end
+end
+
+
+local function look_ahead(id, train)
+	
+	local acc = advtrains.get_acceleration(train, 1)
+	local vel = train.velocity
+	local brakedst = ( -(vel*vel) / (2*acc) ) * params.DST_FACTOR
+	
+	local brake_i = advtrains.path_get_index_by_offset(train, train.index, brakedst + params.BRAKE_SPACE)
+	--local aware_i = advtrains.path_get_index_by_offset(train, brake_i, AWARE_ZONE)
+	
+	local lzb = train.lzb
+	local trav = lzb.trav
+	
+	--train.debug = lspd
+	
+	while trav <= brake_i do
+		trav = trav + 1
+		local pos = advtrains.path_get(train, trav)
+		-- check offtrack
+		if trav > train.path_trk_f then
+			table.insert(lzb.oncoming, {
+				pos = pos,
+				idx = trav-1,
+				spd = 0,
+			})
+		else
+			-- run callbacks
+			-- Note: those callbacks are defined in trainlogic.lua for consistency with the other node callbacks
+			advtrains.tnc_call_approach_callback(pos, id, train, trav, lzb.data)
+			
+		end
+	end
+	
+	lzb.trav = trav
+	
+end
+
+--[[
+Distance needed to accelerate from v0 to v1 with constant acceleration a:
+
+         v1 - v0     a   / v1 - v0 \ 2
+s = v0 * -------  +  - * | ------- |
+            a        2   \    a    /
+]]
+
+local function apply_control(id, train)
+	local lzb = train.lzb
+	
+	local i = 1
+	while i<=#lzb.oncoming do
+		if lzb.oncoming[i].idx < train.index then
+			local ent = lzb.oncoming[i]
+			if ent.fun then
+				ent.fun(ent.pos, id, train, ent.idx, ent.spd, lzb.data)
+			end
+			
+			table.remove(lzb.oncoming, i)
+		else
+			i = i + 1
+		end
+	end
+	
+	for i, it in ipairs(lzb.oncoming) do
+		local a = advtrains.get_acceleration(train, 1) --should be negative
+		local v0 = train.velocity
+		local v1 = it.spd
+		if v1 and v1 <= v0 then
+			local f = (v1-v0) / a
+			local s = v0*f + a*f*f/2
+			
+			local st = s + params.ADD_SLOW
+			if v0 > 3 then
+				st = s + params.ADD_FAST
+			end
+			if v0<=0 then
+				st = s + params.ADD_STAND
+			end
+			
+			local i = advtrains.path_get_index_by_offset(train, it.idx, -st)
+			
+			--train.debug = dump({v0f=v0*f, aff=a*f*f,v0=v0, v1=v1, f=f, a=a, s=s, st=st, i=i, idx=train.index})
+			if i <= train.index then
+				-- Gotcha! Braking...
+				train.ctrl.lzb = 1
+				--train.debug = train.debug .. "BRAKE!!!"
+				return
+			end
+			
+			i = advtrains.path_get_index_by_offset(train, i, -params.ZONE_ROLL)
+			if i <= train.index and v0>1 then
+				-- roll control
+				train.ctrl.lzb = 2
+				return
+			end
+			i = advtrains.path_get_index_by_offset(train, i, -params.ZONE_HOLD)
+			if i <= train.index and v0>1 then
+				-- hold speed
+				train.ctrl.lzb = 3
+				return
+			end
+		end
+	end
+	train.ctrl.lzb = nil
+end
+
+local function invalidate(train)
+	train.lzb = {
+		trav = atfloor(train.index),
+		data = {},
+		oncoming = {},
+	}
+end
+
+function advtrains.lzb_invalidate(train)
+	invalidate(train)
+end
+
+-- Add LZB control point
+-- udata: User-defined additional data
+function advtrains.lzb_add_checkpoint(train, index, speed, callback, udata)
+	local lzb = train.lzb
+	local pos = advtrains.path_get(train, index)
+	table.insert(lzb.oncoming, {
+		pos = pos,
+		idx = index,
+		spd = speed,
+		fun = callback,
+		data = udata,
+	})
+end
+
+
+advtrains.te_register_on_new_path(function(id, train)
+	invalidate(train)
+	look_ahead(id, train)
+end)
+
+advtrains.te_register_on_update(function(id, train)
+	if not train.path or not train.lzb then
+		atprint("LZB run: no path on train, skip step")
+		return
+	end
+	look_ahead(id, train)
+	apply_control(id, train)
+end, true)
diff --git a/advtrains/trainlogic.lua b/advtrains/trainlogic.lua
index 523e51d..ce9ec8b 100644
--- a/advtrains/trainlogic.lua
+++ b/advtrains/trainlogic.lua
@@ -585,9 +585,9 @@ local function mknodecallback(name)
 			table.insert(callt, func)
 		end
 	end
-	return callt, function(pos, id, train, index)
+	return callt, function(pos, id, train, index, paramx1, paramx2, paramx3)
 		for _,f in ipairs(callt) do
-			f(pos, id, train, index)
+			f(pos, id, train, index, paramx1, paramx2, paramx3)
 		end
 	end
 end
@@ -597,6 +597,14 @@ end
 local callbacks_enter_node, run_callbacks_enter_node = mknodecallback("enter")
 local callbacks_leave_node, run_callbacks_leave_node = mknodecallback("leave")
 
+-- Node callback for approaching
+-- Might be called multiple times, whenever path is recalculated
+-- signature is function(pos, id, train, index, lzbdata)
+-- lzbdata: arbitrary data (shared between all callbacks), deleted when LZB is restarted.
+-- These callbacks are called in order of distance as train progresses along tracks, so lzbdata can be used to
+-- keep track of a train's state once it passes this point
+local callbacks_approach_node, run_callbacks_approach_node = mknodecallback("approach")
+
 
 local function tnc_call_enter_callback(pos, train_id, train, index)
 	--atdebug("tnc enter",pos,train_id)
@@ -621,6 +629,18 @@ local function tnc_call_leave_callback(pos, train_id, train, index)
 	run_callbacks_leave_node(pos, train_id, train, index)
 end
 
+function advtrains.tnc_call_approach_callback(pos, train_id, train, index, lzbdata)
+	--atdebug("tnc approach",pos,train_id, lzbdata)
+	local node = advtrains.ndb.get_node(pos) --this spares the check if node is nil, it has a name in any case
+	local mregnode=minetest.registered_nodes[node.name]
+	if mregnode and mregnode.advtrains and mregnode.advtrains.on_train_approach then
+		mregnode.advtrains.on_train_approach(pos, train_id, train, index, lzbdata)
+	end
+	
+	-- call other registered callbacks
+	run_callbacks_approach_node(pos, train_id, train, index, lzbdata)
+end
+
 
 advtrains.te_register_on_new_path(function(id, train)
 	train.tnc = {
diff --git a/advtrains/wagons.lua b/advtrains/wagons.lua
index 5b15c70..381f835 100644
--- a/advtrains/wagons.lua
+++ b/advtrains/wagons.lua
@@ -846,8 +846,8 @@ function wagon:show_bordcom(pname)
 		local i=1
 		while train.lzb.oncoming[i] do
 			local oci = train.lzb.oncoming[i]
-			if oci.pos then
-				if advtrains.interlocking.db.get_sigd_for_signal(oci.pos) then
+			if oci.udata and oci.udata.signal_pos then
+				if advtrains.interlocking.db.get_sigd_for_signal(oci.udata.signal_pos) then
 					form = form .. "button[4.5,8;5,1;ilrs;Remote Routesetting]"
 					break
 				end
diff --git a/advtrains_interlocking/approach.lua b/advtrains_interlocking/approach.lua
new file mode 100644
index 0000000..630ebfe
--- /dev/null
+++ b/advtrains_interlocking/approach.lua
@@ -0,0 +1,113 @@
+-- Interlocking counterpart of LZB, which has been moved into the core...
+-- Registers LZB callback for signal management.
+
+--[[
+usage of lzbdata:
+{
+	travsht = boolean indicating whether the train will be a shunt move at "trav"
+	travspd = speed restriction at end of traverser
+	travwspd = warning speed res.t
+}
+]]
+
+local SHUNT_SPEED_MAX = advtrains.SHUNT_SPEED_MAX
+
+local il = advtrains.interlocking
+
+local function get_over_function(speed, shunt)
+	return function(pos, id, train, index, speed, lzbdata)
+		if speed == 0 and minetest.settings:get_bool("at_il_force_lzb_halt") then
+			atwarn(id,"overrun LZB 0 restriction (red signal) ",ent.pos)
+			-- Set train 1 index backward. Hope this does not lead to bugs...
+			train.index = index - 0.5
+			train.velocity = 0
+			train.ctrl.lzb = 0
+			minetest.after(0, advtrains.invalidate_path, id)
+		else
+			train.speed_restriction = speed
+			train.is_shunt = shunt
+		end
+	end
+end
+
+advtrains.tnc_register_on_approach(function(pos, id, train, index, lzbdata)
+
+	--atdebug(id,"IL ApprC",pos,index,lzbdata)
+	--train.debug = advtrains.print_concat_table({train.is_shunt,"|",index,"|",lzbdata})
+
+	local pts = advtrains.roundfloorpts(pos)
+	local cn  = train.path_cn[index]
+	local travsht = lzbdata.travsht
+	
+	if travsht==nil then
+		travsht = train.is_shunt
+	end
+	
+	local travspd = lzbdata.travspd
+	local travwspd = lzbdata.travwspd
+	
+	-- check for signal
+	local asp, spos = il.db.get_ip_signal_asp(pts, cn)
+	
+	-- do ARS if needed
+	if spos then
+		--atdebug(id,"IL Spos (ARS)",spos,asp)
+		local sigd = il.db.get_sigd_for_signal(spos)
+		if sigd then
+			il.ars_check(sigd, train)
+		end
+	end
+	--atdebug("trav: ",pos, cn, asp, spos, "travsht=", lzb.travsht)
+	local lspd
+	if asp then
+		--atdebug(id,"IL Signal",spos,asp)
+		local nspd = 0
+		--interpreting aspect and determining speed to proceed
+		if travsht then
+			--shunt move
+			if asp.shunt.free then
+				nspd = SHUNT_SPEED_MAX
+			elseif asp.shunt.proceed_as_main and asp.main.free then
+				nspd = asp.main.speed
+				travsht = false
+			end
+		else
+			--train move
+			if asp.main.free then
+				nspd = asp.main.speed
+			elseif asp.shunt.free then
+				nspd = SHUNT_SPEED_MAX
+				travsht = true
+			end
+		end
+		-- nspd can now be: 1. !=0: new speed restriction, 2. =0: stop here or 3. nil: keep travspd
+		if nspd then
+			if nspd == -1 then
+				travspd = nil
+			else
+				travspd = nspd
+			end
+		end
+		
+		local nwspd = asp.info.w_speed
+		if nwspd then
+			if nwspd == -1 then
+				travwspd = nil
+			else
+				travwspd = nwspd
+			end
+		end
+		--atdebug("ns,wns,ts,wts", nspd, nwspd, travspd, travwspd)
+		lspd = travspd
+		if travwspd and (not lspd or lspd>travwspd) then
+			lspd = travwspd
+		end
+		
+		local udata = {signal_pos = spos}
+		local callback = get_over_function(lspd, travsht)
+		advtrains.lzb_add_checkpoint(train, index, lspd, callback)
+	end
+	lzbdata.travsht = travsht
+	lzbdata.travspd = travspd
+	lzbdata.travwspd = travwspd
+end)
diff --git a/advtrains_interlocking/init.lua b/advtrains_interlocking/init.lua
index 37f962b..a2f5882 100644
--- a/advtrains_interlocking/init.lua
+++ b/advtrains_interlocking/init.lua
@@ -22,7 +22,7 @@ dofile(modpath.."tcb_ts_ui.lua")
 dofile(modpath.."route_ui.lua")
 dofile(modpath.."tool.lua")
 
-dofile(modpath.."lzb.lua")
+dofile(modpath.."approach.lua")
 dofile(modpath.."ars.lua")
 dofile(modpath.."tsr_rail.lua")
 
diff --git a/advtrains_interlocking/lzb.lua b/advtrains_interlocking/lzb.lua
deleted file mode 100644
index 8541525..0000000
--- a/advtrains_interlocking/lzb.lua
+++ /dev/null
@@ -1,292 +0,0 @@
--- lzb.lua
--- Enforced and/or automatic train override control, obeying signals
-
-local function approach_callback(parpos, train_id, train, index)
-	local pos = advtrains.round_vector_floor_y(parpos)
-	
-	local node=pnode or advtrains.ndb.get_node(pos)
-	local ndef=minetest.registered_nodes[node.name]
-	if ndef and ndef.advtrains and ndef.advtrains.on_train_approach then
-		ndef.advtrains.on_train_approach(pos, train_id, train, index)
-	end
-end
-
-
---[[
-Documentation of train.lzb table
-train.lzb = {
-	trav = Current index that the traverser has advanced so far
-	travsht = boolean indicating whether the train will be a shunt move at "trav"
-	travspd = speed restriction at end of traverser
-	travwspd = warning speed res.t
-	oncoming = table containing oncoming signals, in order of appearance on the path
-		{
-			pos = position of the signal (not the IP!). Can be nil
-			idx = where this is on the path
-			spd = speed allowed to pass (determined dynamically)
-			npr = <boolean> "No permanent restriction" If true, this is only a punctual restriction.
-				speed_restriction is not set then, and train can accelerate after passing point
-				This is (as of Nov 2017) used by "lines" to brake the train down to 2 when approaching a stop
-				The actual "stop" command is given when the train passes the rail (on_train_enter callback)
-		}
-}
-each step, for every item in "oncoming", we need to determine the location to start braking (+ some safety margin)
-and, if we passed this point for at least one of the items, initiate brake.
-When speed has dropped below, say 3, decrease the margin to zero, so that trains actually stop at the signal IP.
-The spd variable and travsht need to be updated on every aspect change. it's probably best to reset everything when any aspect changes
-
-The traverser stops at signals that result in spd==0, because changes beyond there are likely.
-]]
-
-local il = advtrains.interlocking
-
-local params = {
-	BRAKE_SPACE = 10,
-	AWARE_ZONE  = 50,
-
-	ADD_STAND  =  2.5,
-	ADD_SLOW   =  1.5,
-	ADD_FAST   =  7,
-	ZONE_ROLL  =  2,
-	ZONE_HOLD  =  5, -- added on top of ZONE_ROLL
-	ZONE_VSLOW =  3, -- When speed is <2, still allow accelerating
-
-	DST_FACTOR =  1.5,
-
-	SHUNT_SPEED_MAX = advtrains.SHUNT_SPEED_MAX,
-}
-
-function advtrains.interlocking.set_lzb_param(par, val)
-	if params[par] and tonumber(val) then
-		params[par] = tonumber(val)
-	else
-		error("Inexistant param or not a number")
-	end
-end
-
-
-local function look_ahead(id, train)
-	
-	local acc = advtrains.get_acceleration(train, 1)
-	local vel = train.velocity
-	local brakedst = ( -(vel*vel) / (2*acc) ) * params.DST_FACTOR
-	
-	local brake_i = advtrains.path_get_index_by_offset(train, train.index, brakedst + params.BRAKE_SPACE)
-	--local aware_i = advtrains.path_get_index_by_offset(train, brake_i, AWARE_ZONE)
-	
-	local lzb = train.lzb
-	local trav = lzb.trav
-	local travspd = lzb.travspd
-	local travwspd = lzb.travwspd
-	local lspd
-	
-	--train.debug = lspd
-	
-	while trav <= brake_i and (not lspd or lspd>0) do
-		trav = trav + 1
-		local pos = advtrains.path_get(train, trav)
-		local pts = advtrains.roundfloorpts(pos)
-		local cn  = train.path_cn[trav]
-		-- check offtrack
-		if trav > train.path_trk_f then
-			lspd = 0
-			table.insert(lzb.oncoming, {
-				idx = trav-1,
-				spd = 0,
-			})
-		else
-			-- run callback, if exists
-			approach_callback(pos, id, train, trav)
-			
-			-- check for signal
-			local asp, spos = il.db.get_ip_signal_asp(pts, cn)
-			
-			-- do ARS if needed
-			if spos then
-				local sigd = il.db.get_sigd_for_signal(spos)
-				if sigd then
-					il.ars_check(sigd, train)
-				end
-			end
-			--atdebug("trav: ",pos, cn, asp, spos, "travsht=", lzb.travsht)
-			if asp then
-				local nspd = 0
-				--interpreting aspect and determining speed to proceed
-				if lzb.travsht then
-					--shunt move
-					if asp.shunt.free then
-						nspd = params.SHUNT_SPEED_MAX
-					elseif asp.shunt.proceed_as_main and asp.main.free then
-						nspd = asp.main.speed
-						lzb.travsht = false
-					end
-				else
-					--train move
-					if asp.main.free then
-						nspd = asp.main.speed
-					elseif asp.shunt.free then
-						nspd = params.SHUNT_SPEED_MAX
-						lzb.travsht = true
-					end
-				end
-				-- nspd can now be: 1. !=0: new speed restriction, 2. =0: stop here or 3. nil: keep travspd
-				if nspd then
-					if nspd == -1 then
-						travspd = nil
-					else
-						travspd = nspd
-					end
-				end
-				
-				local nwspd = asp.info.w_speed
-				if nwspd then
-					if nwspd == -1 then
-						travwspd = nil
-					else
-						travwspd = nwspd
-					end
-				end
-				--atdebug("ns,wns,ts,wts", nspd, nwspd, travspd, travwspd)
-				lspd = travspd
-				if travwspd and (not lspd or lspd>travwspd) then
-					lspd = travwspd
-				end
-				
-				table.insert(lzb.oncoming, {
-					pos = spos,
-					idx = trav,
-					spd = lspd,
-					sht = lzb.travsht,
-				})
-			end
-		end
-	end
-	
-	lzb.trav = trav
-	lzb.travspd = travspd
-	lzb.travwspd = travwspd
-	
-	--train.debug = dump(lzb)
-	
-end
-
---[[
-Distance needed to accelerate from v0 to v1 with constant acceleration a:
-
-         v1 - v0     a   / v1 - v0 \ 2
-s = v0 * -------  +  - * | ------- |
-            a        2   \    a    /
-]]
-
-local function apply_control(id, train)
-	local lzb = train.lzb
-	
-	local i = 1
-	while i<=#lzb.oncoming do
-		if lzb.oncoming[i].idx < train.index then
-			local ent = lzb.oncoming[i]
-			local nodelete
-			if not ent.npr then
-				if ent.spd == 0 and minetest.settings:get_bool("at_il_force_lzb_halt") then
-					atwarn(train.id,"overrun LZB 0 restriction (red signal) ",ent.pos)
-					-- Set train 1 index backward. Hope this does not lead to bugs...
-					train.index = ent.idx - 0.5
-					train.velocity = 0
-					train.ctrl.lzb = 0
-					nodelete = true
-				else
-					train.speed_restriction = ent.spd
-					train.is_shunt = ent.sht
-				end
-			end
-			if not nodelete then
-				table.remove(lzb.oncoming, i)
-			end
-		else
-			i = i + 1
-		end
-	end
-	
-	for i, it in ipairs(lzb.oncoming) do
-		local a = advtrains.get_acceleration(train, 1) --should be negative
-		local v0 = train.velocity
-		local v1 = it.spd
-		if v1 and v1 <= v0 then
-			local f = (v1-v0) / a
-			local s = v0*f + a*f*f/2
-			
-			local st = s + params.ADD_SLOW
-			if v0 > 3 then
-				st = s + params.ADD_FAST
-			end
-			if v0<=0 then
-				st = s + params.ADD_STAND
-			end
-			
-			local i = advtrains.path_get_index_by_offset(train, it.idx, -st)
-			
-			--train.debug = dump({v0f=v0*f, aff=a*f*f,v0=v0, v1=v1, f=f, a=a, s=s, st=st, i=i, idx=train.index})
-			if i <= train.index then
-				-- Gotcha! Braking...
-				train.ctrl.lzb = 1
-				--train.debug = train.debug .. "BRAKE!!!"
-				return
-			end
-			
-			i = advtrains.path_get_index_by_offset(train, i, -params.ZONE_ROLL)
-			if i <= train.index and v0>1 then
-				-- roll control
-				train.ctrl.lzb = 2
-				return
-			end
-			i = advtrains.path_get_index_by_offset(train, i, -params.ZONE_HOLD)
-			if i <= train.index and v0>1 then
-				-- hold speed
-				train.ctrl.lzb = 3
-				return
-			end
-		end
-	end
-	train.ctrl.lzb = nil
-end
-
-local function invalidate(train)
-	train.lzb = {
-		trav = atfloor(train.index),
-		travsht = train.is_shunt,
-		oncoming = {}
-	}
-	-- possible FIX: do not clear LZB control when invalidating. This will be cleared when apply_control is run next time
-	--train.ctrl.lzb = nil
-end
-
-function advtrains.interlocking.lzb_invalidate(train)
-	invalidate(train)
-end
-
--- Add an (extra) lzb control point that is not a permanent restriction (see above)
--- (permanent restrictions are only to be imposed by signal ip's)
-function advtrains.interlocking.lzb_add_oncoming_npr(train, idx, spd)
-	local lzb = train.lzb
-	
-	table.insert(lzb.oncoming, {
-					idx = idx,
-					spd = spd,
-					npr = true,
-				})
-end
-
-
-advtrains.te_register_on_new_path(function(id, train)
-	invalidate(train)
-	look_ahead(id, train)
-end)
-
-advtrains.te_register_on_update(function(id, train)
-	if not train.path or not train.lzb then
-		atprint("LZB run: no path on train, skip step")
-		return
-	end
-	look_ahead(id, train)
-	apply_control(id, train)
-end, true)
diff --git a/advtrains_interlocking/signal_api.lua b/advtrains_interlocking/signal_api.lua
index d43125b..90bfaf4 100644
--- a/advtrains_interlocking/signal_api.lua
+++ b/advtrains_interlocking/signal_api.lua
@@ -226,9 +226,9 @@ function advtrains.interlocking.signal_on_aspect_changed(pos)
 	
 	local tns = advtrains.occ.get_trains_over(ipos)
 	for id, sidx in pairs(tns) do
-		local train = advtrains.trains[id]
+--		local train = advtrains.trains[id]
 		--if train.index <= sidx then
-			advtrains.interlocking.lzb_invalidate(train)
+		minetest.after(0, advtrains.invalidate_path, id)
 		--end
 	end
 end
diff --git a/advtrains_interlocking/tsr_rail.lua b/advtrains_interlocking/tsr_rail.lua
index 90e8101..89da290 100644
--- a/advtrains_interlocking/tsr_rail.lua
+++ b/advtrains_interlocking/tsr_rail.lua
@@ -34,7 +34,7 @@ local adefunc = function(def, preset, suffix, rotation)
 					if train.path_cn[index] == 1 then
 						local pe = advtrains.encode_pos(pos)
 						local npr = advtrains.interlocking.npr_rails[pe] or 2
-						advtrains.interlocking.lzb_add_oncoming_npr(train, index, npr)
+						advtrains.lzb_add_checkpoint(train, index, npr, nil)
 					end
 				end,
 			},
diff --git a/advtrains_line_automation/stoprail.lua b/advtrains_line_automation/stoprail.lua
index 2e6072e..e955d76 100644
--- a/advtrains_line_automation/stoprail.lua
+++ b/advtrains_line_automation/stoprail.lua
@@ -151,7 +151,7 @@ local adefunc = function(def, preset, suffix, rotation)
 								stdata.ars = {default=true}
 							end
 							if stdata.ars and (stdata.ars.default or advtrains.interlocking.ars_check_rule_match(stdata.ars, train) ) then
-								advtrains.interlocking.lzb_add_oncoming_npr(train, index, 2)
+								advtrains.lzb_add_checkpoint(train, index, 2, nil)
 								local stn = advtrains.lines.stations[stdata.stn]
 								local stnname = stn and stn.name or "Unknown Station"
 								train.text_inside = "Next Stop:\n"..stnname
-- 
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