Add noserver station program

programs.info

@@ -153,6 +153,16 @@
             "libevent","checkarg","util","simple_data_structure"
         }
     },
+    ["noserver-station"]={
+        title="NoServer Station",
+        info="Railway control system used in NoServer",
+        files={
+            "programs/noserver-station/station.lua"
+        },
+        requires={
+            "libevent"
+        }
+    },
     ["prtsc"]={
         title="Print Screen",
         info="Save screen to file when PrtSc key is pressed.",

programs/noserver-station/station.lua

@@ -0,0 +1,179 @@
+require("libevent")
+local event=require('event')
+local computer=require('computer')
+local component=require('component')
+local sides=require('sides')
+
+---------- Config ----------
+local addr_redin = ""
+local addr_redout = ""
+local addr_next_station = ""
+local limit_train_interval = 10  -- Trains must be separate with this time, should be greater than 2.
+----------------------------
+
+local note = component.iron_noteblock
+local sign = component.sign
+local redin = component.proxy(addr_redin)
+local redout = component.proxy(addr_redout)
+
+if not redin or not redout or not sign or not note then
+    print("device not ready.")
+    return
+end
+
+local track_side_map = {
+    sides.north,
+    sides.east,
+    sides.south,
+    sides.west
+}
+local side_track_map = {
+    [sides.north] = 1,
+    [sides.east] = 2,
+    [sides.south] = 3,
+    [sides.west] = 4
+}
+
+local function setRed(track_id)
+    redout.setOutput(track_side_map[track_id], 0)
+end
+
+local function setGreen(track_id)
+    redout.setOutput(track_side_map[track_id], 15)
+end
+
+local function printf(fmt, ...)
+    print(string.format(fmt, ...))
+end
+
+local workers = {}
+local bus = CreateEventBus()
+bus:listen("redstone_changed")
+bus:listen("_eve_timer")
+bus:listen("interrupted")
+
+local function StartTask(fn)
+    local c = coroutine.create(fn)
+    local ok, ticket = coroutine.resume(c)
+    if coroutine.status(c) ~= "dead" then
+        workers[ticket] = c
+    end
+end
+
+local _ticket_holder = 0
+
+local function GenerateTicket()
+    _ticket_holder = _ticket_holder + 1
+    return string.format("tk_%d", _ticket_holder)
+end
+
+local function listenerSleep(second)
+    local ticket = GenerateTicket()
+    event.timer(second, function()
+        event.push("_eve_timer", ticket)
+    end, 1)
+    -- print("<-- listenerSleep yield.", ticket)
+    coroutine.yield(ticket)
+    -- print("--> listenerSleep resume.", ticket)
+end
+
+local function stationAlarm(second)
+    for i=1, second*2 do
+        component.iron_noteblock.playNote(6, 6)
+        listenerSleep(0.5)
+    end
+end
+
+-- Try to acquire token that allow train leave station
+local global_token_locked = false
+
+local function acquireToken()
+    if not global_token_locked then
+        global_token_locked = true
+        return
+    end
+    while global_token_locked do
+        listenerSleep(1)
+    end
+    global_token_locked = true
+end
+
+local function releaseToken()
+    global_token_locked = false
+end
+
+local sign_states = {}
+
+local function stationSignUpdate()
+    local t = {}
+    for i, s in pairs(sign_states) do
+        table.insert(t, string.format("[%s]: %s", i, s))
+    end
+    sign.setValue(sides.up, table.concat(t, '\n'))
+end
+
+local function stationAddSign(track_id, status)
+    sign_states[track_id] = status
+    stationSignUpdate()
+end
+
+local function stationClearSign(track_id)
+    sign_states[track_id] = nil
+    stationSignUpdate()
+end
+
+print("Press Ctrl+C to stop.")
+while true do
+    local e = bus:next(-1, 0.05)
+    -- print(e.event)
+    if e.event == "interrupted" then
+        break
+    elseif e.event == "redstone_changed" then
+        if e.address == addr_redin and e.newValue == 15 then
+            local track_id = side_track_map[e.side]
+            if track_id then
+                StartTask(function()
+                    printf("got train at track %s", track_id)
+                    stationAddSign(track_id, "Waiting")
+                    listenerSleep(15)
+                    acquireToken()
+                    printf("track %s acquired token.", track_id)
+                    stationAddSign(track_id, "About to leave")
+                    printf("start alarm for track %s", track_id)
+                    stationAlarm(8)
+                    stationAddSign(track_id, "Leaving...")
+                    printf("track %s set to green.", track_id)
+                    setGreen(track_id)
+                    listenerSleep(2.5)
+                    printf("track %s set to red.", track_id)
+                    setRed(track_id)
+                    stationClearSign(track_id)
+                    listenerSleep(limit_train_interval - 2)
+                    releaseToken()
+                    printf("token released at track %s", track_id)
+                end)
+            end
+        end
+    elseif e.event == "_eve_timer" then
+        local ticket = e.data[1]
+        if type(ticket) == "table" then
+            for k, v in pairs(ticket) do
+                print(k,v)
+            end
+        end
+        -- print("<debug> got ticket", ticket)
+        if workers[ticket] then
+            local c = workers[ticket]
+            workers[ticket] = nil
+            -- print("<debug> resuming thread", c)
+            local ok, new_ticket = coroutine.resume(c)
+            if coroutine.status(c) ~= "dead" then
+                workers[new_ticket] = c
+            end
+        else
+            -- print("<debug> ticket not found.", ticket)
+        end
+    end
+end
+
+bus:close()