Improved version with CAN mapping in the config string

racecapture3.lua

-- Copyright 2016 Mash at boostedforums.net
-- Minify before use by https://mothereff.in/lua-minifier
-- Editor https://ace.c9.io/build/kitchen-sink.html
-- don't remove excessive commas or comments - minify will deal with it

function dump(o)
   if type(o) == 'table' then
      local s = '{ '
      for k,v in pairs(o) do
         if type(k) ~= 'number' then k = '"'..k..'"' end
         s = s .. '['..k..'] = ' .. dump(v) .. ','
      end
      return s .. '} '
   else
      return tostring(o)
   end
end

function initCAN( channel, baud )
end

function setTickRate(rate)
end

function getUptime()
  return 0
end

local chanId = 0
function addChannel(name,sampleRate,precision,minv,maxv,unit)
  print("addChannel", name,sampleRate,precision,minv,maxv, unit)
  chanId = chanId + 1
  return chanId
end

function txCAN(channel, id, isExtended, data, timeout )
  print("txCAN", channel, id, isExtended, dump(data), timeout)
end

function rxCAN(channel, timeout )
  print("rxCAN", channel, timeout)
end

function collectgarbage()
end

-- ========================= CAN CONFIG =======================================
local canCon ="0x7E0,0x805100;160;8,TPS,0,100,%,100/255;8,APP,0,100,%,1/2,-16@"
local canMap = {}

local sb,sl,sm = string.byte,string.len,string.match
function readOne(pos)
	local c = sb(canCon,pos)
	if c==nil then return nil,pos+1 end
	if (c > 47 and c < 58) or c==45 then -- read number
		local nums = sm(canCon,"[-.%xxX]+",pos)
		local num = tonumber(nums)
		local pos2 = pos+sl(nums)
		c=sb(canCon,pos2)
		if c==42 or c==47 then -- MULTIPLY or DIVIDE
			pos2=pos2+1
			local nums2=sm(canCon,"[-.%xxX]+",pos2)
			local num2=tonumber(nums2)
			pos2 = pos2+sl(nums2)
			if c==42 then num=num*num2 else num=num/num2 end			
		end
		return num,pos2
	end
	-- Read string
	local st = sm(canCon,"[^,;@]+",pos)
	if st==nil then return nil,pos+1
	else return st, pos+sl(st) end
end

function ss(pos)
	return string.sub(canCon,pos,pos)
end

function canRDmap()
	local cmi,res,pos = 1,nil,1

	while pos <= sl(canCon) do
		canMap[cmi]=nil -- separator of requests
		canMap[cmi+1],pos=readOne(pos) -- address
		canMap[cmi+2],pos=readOne(pos+1) -- pid
		if ss(pos) =="," then
		                        	canMap[cmi+3],pos=readOne(pos+1) -- priority
		else canMap[cmi+3]=1 end	
		
		--print("REQUEST Address: "..canMap[cmi+1].." PID: "..canMap[cmi+2].." Priority: "..canMap[cmi+3])

		local cmi_len = cmi+4
		canMap[cmi_len]=0
		cmi=cmi+5
		while ss(pos)~="@" do
			-- Address,PID,Priority (1)
			-- ;Bits,Name,Min,Max,Unit,Mult(1),Add(0),Signed(0/1 - default 0)
			-- ;Bits - skip number of bits forward
			-- @

			-- nil, address, pid, priority, length - request
			-- bits, nil - skip 
			-- bits, channelId, mult, add, signed - channel
			--print("  start char "..ss(pos))

			local name,minv,maxv,precision,unit,mult = "",0,0,0,"",1
			canMap[cmi],pos=readOne(pos+1) --bits
			--print("  bits: "..canMap[cmi])
			canMap[cmi_len]=canMap[cmi_len]+canMap[cmi] -- count length 
			if ss(pos)~="," then
				--print("  skip "..ss(pos))
				canMap[cmi+1]=nil -- Skip
				cmi=cmi+2
			else
				name,pos = readOne(pos+1)
				minv,pos = readOne(pos+1)
				maxv,pos = readOne(pos+1)
				if ss(pos)=="," then unit,pos = readOne(pos+1) --unit
				else unit = "" end
				if ss(pos)=="," then mult,pos = readOne(pos+1) --mult
				else mult=1 end
				canMap[cmi+2]=mult
				if ss(pos)=="," then canMap[cmi+3],pos = readOne(pos+1) --add
				else canMap[cmi+3]=0 end
				if ss(pos)=="," then canMap[cmi+4],pos = readOne(pos+1) --sign
				else canMap[cmi+4]=0 end
				
				while mult < 1 do
					precision=precision+1
					mult=mult*10
				end
								
				canMap[cmi+1]=addChannel(name,1000,precision,minv,maxv,unit)
				cmi=cmi+5
			end
		end
		pos=pos+1
	end
	canCon = nil -- Clean memory from large string we won't use anymore
end


function canRDall(count)
	-- nil, address, pid, priority, length - request
	-- bits, nil - skip 
	-- bits, channelId, mult, add, signed - channel

	local i = 1
	while canMap[i+1]~=nil do
		if (count % canMap[i+3]) == 0 then -- Priority implement 
		
			local data = canRD(canMap[i+1],canMap[i+2],canMap[i+4])
            i=i+5
            local bit = 1
            while canMap[i]~=nil do -- Set Channels
                if canMap[i+1]~=nil then
                    if data ~= nil then
                      local val = bitsToN(data,bit,canMap[i],canMap[i+4])
                      val=val*canMap[i+2]+canMap[i+3]
                      setChannel(canMap[i+1],val)
                    end
                    bit=bit+canMap[i]
                    i=i+5
                else -- skip bits
                    bit=bit+canMap[i]
                    i=i+2
                end
            end
		end
	end
end

-- =========== UP TO 24 BIT NUMBER EXTRACTION FROM BYTE ARRAY ==================
local band, bxor, bnot = bit.band, bit.bxor, bit.bnot
local lshift, rshift = bit.lshift, bit.rshift
function bitsToN(d,startBit,length,signed)
	local shift = (8 - ((startBit+length-1) % 8)) % 8
	local startByte = 1 + (startBit - 1 - ((startBit-1) % 8)) / 8--TODO: to //
	local bnumb = d[startByte]

	if (length+shift) > 8 then
		bnumb = d[startByte+1] + lshift(bnumb,8)
		if (length+shift) > 16 then
			bnumb = d[startByte+2] + lshift(bnumb,8)
		end
	end

	bnumb = rshift(bnumb,shift)
	bnumb = band(bnumb,2^length-1)
	if signed and bnumb > 0x7FFF then 
			bnumb = 0 - lshift(band(-bnot(0x1000+rshift(number,8)),0xFF),8) 
			- band(-bxor(0x1000+band(number,0xFF),0),0xFF) - 1
	end
	return bnumb
end

--============================ READ CAN DATA AND RETURN DATA BYTE ARRAY ========
function canRD(address,pid,reqLength) -- TODO: Check it works without padding
	local req
	if pid > 255 then -- MODE 23
		req = {5,0x23,rshift(pid,16),rshift(pid,8),band(pid,0xFF),reqLength}
	else -- MODE21
		req={2,0x21,pid}
	end
	
	res = txCAN(0, address, 0, req, 100) -- Send request
	if res ~= 1 then return nil end

  	local data = {}
  	local id, ext, d1 = rxCAN(0,100) -- Read Response
  	if id == nil then return nil end
--	for r,d in ipairs(d1) do print(d..",") end
--	println(" ")

	local i = 1
	local s = 3
	if d1[1] == 0x10 then s=s+1 end -- Multimessaging
	if pid < 256 then s=s+1 end -- Mode23 has more data
	while s<9 do
		data[i]=d1[s]
		i=i+1
		s=s+1
	end

  	if d1[1] ~= 0x10 then return data end -- Not multimessaging, so quit
  	
  	-- Read multi messages
  	res = txCAN(0, address, 0, {48,8,0},100) 
  	if res ~= 1 then return nil end
  	local messages = (d1[2] + 1) / 7
  	for m=1,messages do
  		local id, ext, d1 = rxCAN(0,100) 
  		if id == nil then return nil end
--		print(m..":   ")
--		for r,d in ipairs(d1) do print(d..",") end
--		println(" ")
  		local s=2
  		while s<9 and i<reqLength+1 do
  			data[i]=d1[s]
  			i=i+1
  			s=s+1
  		end
  	end
  	return data
end

-- ========================= MAIN CYCLE =======================================
local fpChan,tgtFP,chCANHz = 3,43.5,addChannel("CAN", 1, 0, 0, 300, "Hz")
initCAN(0, 500000)
setTickRate(1000)

for i=1,10 do rxCAN(0,5) end -- Clear CAN buffer
canRDmap()
collectgarbage()

function onTick()
	local started,mc = getUptime(),0
	print("START")
	
    canRDall(mc)
    collectgarbage()
    mc = mc + 1
end

onTick()