scan

function checkSlot()
  if turtle.getItemCount(curSlot) == 0 then
    if curSlot ~= 15 then
      curSlot = curSlot + 1
      turtle.select(curSlot)
      checkSlot()
    elseif curSlot == 15 then
      --[[
      curSlot = 1
      turtle.select(curSlot)
      print("Out of blocks press enter")
      read()
      --]]
      turtle.select(16)
      turtle.placeUp()
      for i = 1, 15 do
        turtle.select(i)
        turtle.suckUp()
      end
      turtle.select(16)
      turtle.digUp()
      curSlot = 1
      turtle.select(curSlot)
    end
  end
end

len = 0
curSlot = 1

turtle.select(curSlot)

while turtle.forward() do
  len = len + 1
end

print("Wall is "..len.." in length")

turtle.up()
turtle.turnLeft()
turtle.turnLeft()

while true do
  for i = 1,len do
    checkSlot()
    turtle.placeDown()
    turtle.forward()
  end
  checkSlot()
  turtle.placeDown()
  turtle.up()
  turtle.turnLeft()
  turtle.turnLeft()
end