Simple Mining Turtle Tunnel

print("How long should I go forward for?")
length=tonumber(read())
current=0
oneBehind=-1

function DigFace()
	turtle.turnLeft()
	turtle.dig()
	turtle.digDown() turtle.down()
	turtle.dig()
	turtle.digDown() turtle.down()
	turtle.dig()
	turtle.turnRight() turtle.turnRight()
	turtle.dig() turtle.up()
	turtle.dig() turtle.up()
	turtle.dig()
	turtle.turnLeft()
end

function EmptyInventory(dist)
	turtle.turnRight() turtle.turnRight()
	while current>0 do
		turtle.forward()
		current=current-1
	end
	turtle.down() turtle.down()

	for i=1,16 do
		turtle.select(i)
		turtle.dropDown()
	end
	turtle.select(1)

	turtle.turnRight() turtle.turnRight()
	turtle.up() turtle.up()
	while current<dist do
		turtle.forward()
		current=current+1
	end
end

while current<length do
	if oneBehind<current then DigFace() end
	turtle.dig()
	oneBehind=oneBehind+1
	if turtle.forward() then
		current=current+1
		oneBehind=current-1
	end
	if turtle.getItemCount(16)>0 then EmptyInventory(current) end
end

EmptyInventory(0)