Redstone Communication

function receiveRedstone(timeout)
  local tim

  --Set possible timeout
  if timeout then
    tim = os.startTimer(timeout)
  end
  while true do
    local event, timer = os.pullEvent()
    --If we got a redstone event, then we didn't hit our timeout and are ready to receive
    if event == "redstone" then

      --Map each line so we know what order we're going to receive in
      local receiveTbl = {}
      for a,v in ipairs(rs.getSides()) do
        receiveTbl[math.floor(rs.getBundledInput(v)/256)] = v
      end

      --Default each of our values.

      --ReceivedValues is our integers of each line in order
      local receivedValues = {0,0,0,0,0,0}

      --OldValue is the 9th bit of the first line, it toggles between 0 and 1 to show we're changing characters
      local oldValue = 0

      --Our string to build
      local buildString = ""

      --Our ending bool, gets changed to false if the 10th bit of 1st line is true
      local endBits = true

      --Loop
      while endBits do

        --Grab 9th bit, compare to old
        local curValue = bit.band(receivedValues[1],256)
        if( curValue ~= oldValue) then

          --If different, change old to new
          oldValue = curValue

          --If the 10th bit in first line is on, this is the final time we're running
          if(bit.band(receivedValues[1],512) ~= 0) then
            endBits = false
          end

          --Loop through our received values table
          for a,v in ipairs(receivedValues) do

            --If the value isn't 0 (or technically two full null characters)
            if v ~= 0 then

              --Tack onto end of buildString
              buildString = buildString .. string.char(v%256)

              --#If we're not the first line, tack the second half onto the end as well
              if a ~= 1 then
                buildString = buildString .. string.char(math.floor(v/256))
              end
            end
          end
        end


        --Pullevent on redstone
        os.pullEvent("redstone")

        --Update values based on redstone change
        for a,v in ipairs(receiveTbl) do
          receivedValues[a] = rs.getBundledInput(v)
        end

      end

      --We received the 10th bit, return true that we got a message, and the message itself
      return true, buildString
    elseif event == "timer" and timer == tim then

      --We timed out, return false
      return false, ""
    end
  end
end

function sendRedstone(str)
  --Create our sending table. Just a local table that holds the sides of the computer
  local sendTbl = rs.getSides()

  --Convert the characters in the string
  local sending = {}
  for i = 1, #str do
    sending[i] = string.byte(string.sub(str,i,i))
  end


  --Ping end server and identify each line
  for i = 1, #sendTbl do
    rs.setBundledOutput(sendTbl[i],256*i)
  end

  --Reset the lines to get ready for sending
  sleep(.1)
  for i = 1, #sendTbl do
    rs.setBundledOutput(sendTbl[i],0)
  end
  sleep(.1)


  --Send bytes in order

  --Bool is for first line, it's our toggling bit
  local bool = true

  --I is the current character to send, curSide is the line to send it through
  local i = 1
  local curSide = 1

  --While we have still have more characters to send
  while i <= #sending do

    --bytesToSend is our integer representing the 16 bit number to send on the line
    local bytesToSend = 0

    --Add just the first character's 0-255 representation, increment our character by 1
    bytesToSend = bytesToSend + sending[i]
    i = i + 1

    --If we're on our first line then if our toggle bit needs to be on, then turn it on
    if (curSide == 1) then
      if (bool) then
        bytesToSend = bytesToSend + 256
      end

    --Elseif we still have more characters to send
    elseif (i <= #sending) then
      --Add other character bit shifted right by 8 bits and increment i
      bytesToSend = bytesToSend + sending[i] * 256
      i = i + 1
    end

    --Set the output to our number
    rs.setBundledOutput(sendTbl[curSide],bytesToSend)

    --If we're on side 6, sleep so we can update, set side to 1, and toggle bool
    if curSide == 6 then
      curSide = 1
      sleep(.1)
      bool = not bool
    else
      --Else, increment curSide
      curSide = curSide + 1
    end
  end

  --End of write, need to make sure that any unused character lines are cleared.
  while (curSide <= 6) do
    rs.setBundledOutput(sendTbl[curSide],0)
    curSide = curSide + 1
  end

  --Add the 10th bit to the first line
  rs.setBundledOutput(sendTbl[1],rs.getBundledOutput(sendTbl[1]) + (2 * 256))

  --Sleep then clear lines, we're done.
  sleep(.1)
  for a,v in ipairs(sendTbl) do
    rs.setBundledOutput(v,0)
  end
end