added Luacheck GitHub action (#210)

* added shields.io elements
* #209 luacheck action
* #209 cleanup to pass luacheck
* added check statuses to readme

rtu/dev/redstone_rtu.lua

@@ -34,7 +34,7 @@ function redstone_rtu.new()
     ---@param side string
     ---@param color integer
     function public.link_di(side, color)
-        local f_read = nil
+        local f_read    ---@type function
 
         if color then
             f_read = function ()
@@ -53,8 +53,8 @@ function redstone_rtu.new()
     ---@param side string
     ---@param color integer
     function public.link_do(side, color)
-        local f_read = nil
-        local f_write = nil
+        local f_read    ---@type function
+        local f_write   ---@type function
 
         if color then
             f_read = function ()

rtu/modbus.lua

@@ -347,11 +347,9 @@ function modbus.new(rtu_dev, use_parallel_read)
             response = { MODBUS_EXCODE.NEG_ACKNOWLEDGE }
         end
 
-        -- default is to echo back
-        local func_code = packet.func_code
-
-        -- echo back with error flag, on success the "error" will be acknowledgement
-        func_code = bit.bor(packet.func_code, MODBUS_FCODE.ERROR_FLAG)
+        -- default is to echo back<br>
+        -- but here we echo back with error flag, on success the "error" will be acknowledgement
+        local func_code = bit.bor(packet.func_code, MODBUS_FCODE.ERROR_FLAG)
 
         -- create reply
         local reply = comms.modbus_packet()
@@ -365,8 +363,8 @@ function modbus.new(rtu_dev, use_parallel_read)
     ---@param packet modbus_frame
     ---@return boolean return_code, modbus_packet reply
     function public.handle_packet(packet)
-        local return_code = true
-        local response = nil
+        local return_code   ---@type boolean
+        local response      ---@type table|MODBUS_EXCODE
 
         if packet.length >= 2 then
             -- handle  by function code

rtu/rtu.lua

@@ -14,9 +14,6 @@ local ESTABLISH_ACK = comms.ESTABLISH_ACK
 local SCADA_MGMT_TYPE = comms.SCADA_MGMT_TYPE
 local RTU_UNIT_TYPE = types.RTU_UNIT_TYPE
 
-local print = util.print
-local println = util.println
-local print_ts = util.print_ts
 local println_ts = util.println_ts
 
 -- create a new RTU unit
@@ -347,8 +344,8 @@ function rtu.comms(version, modem, local_port, server_port, range, conn_watchdog
             if protocol == PROTOCOL.MODBUS_TCP then
                 ---@cast packet modbus_frame
                 if rtu_state.linked then
-                    local return_code = false
-                    local reply = modbus.reply__neg_ack(packet)
+                    local return_code   ---@type boolean
+                    local reply         ---@type modbus_packet
 
                     -- handle MODBUS instruction
                     if packet.unit_id <= #units then

rtu/startup.lua

@@ -25,13 +25,11 @@ local sna_rtu      = require("rtu.dev.sna_rtu")
 local sps_rtu      = require("rtu.dev.sps_rtu")
 local turbinev_rtu = require("rtu.dev.turbinev_rtu")
 
-local RTU_VERSION = "v0.13.2"
+local RTU_VERSION = "v0.13.3"
 
 local RTU_UNIT_TYPE = types.RTU_UNIT_TYPE
 
-local print = util.print
 local println = util.println
-local print_ts = util.print_ts
 local println_ts = util.println_ts
 
 ----------------------------------------
@@ -287,9 +285,9 @@ local function main()
 
             local device = ppm.get_periph(name)
 
-            local type = nil            ---@type string|nil
-            local rtu_iface = nil       ---@type rtu_device
-            local rtu_type = nil        ---@type RTU_UNIT_TYPE
+            local type                  ---@type string|nil
+            local rtu_iface             ---@type rtu_device
+            local rtu_type              ---@type RTU_UNIT_TYPE
             local is_multiblock = false ---@type boolean
             local formed = nil          ---@type boolean|nil
             local faulted = nil         ---@type boolean|nil
@@ -356,11 +354,11 @@ local function main()
             elseif type == "solarNeutronActivator" then
                 -- SNA
                 rtu_type = RTU_UNIT_TYPE.SNA
-                rtu_iface, _ = sna_rtu.new(device)
+                rtu_iface, faulted = sna_rtu.new(device)
             elseif type == "environmentDetector" then
                 -- advanced peripherals environment detector
                 rtu_type = RTU_UNIT_TYPE.ENV_DETECTOR
-                rtu_iface, _ = envd_rtu.new(device)
+                rtu_iface, faulted = envd_rtu.new(device)
             elseif type == ppm.VIRTUAL_DEVICE_TYPE then
                 -- placeholder device
                 rtu_type = RTU_UNIT_TYPE.VIRTUAL

rtu/threads.lua

@@ -17,9 +17,6 @@ local threads = {}
 
 local RTU_UNIT_TYPE = types.RTU_UNIT_TYPE
 
-local print = util.print
-local println = util.println
-local print_ts = util.print_ts
 local println_ts = util.println_ts
 
 local MAIN_CLOCK  = 2   -- (2Hz, 40 ticks)