Create a new version of paste:

-- branch
-- Creates a 1x1x3 tunnel of the length specified by the user
--    then mines 3 blocks to the right and tunnels back
-- Torches, if supplied, will be placed on the right-hand wall at 8 block intervals
-- Written by HarvDad, March 2014

args = {...}
nArgs = #args

print("branch: Rev 1.3")

loop = 0;
x = 0
y = 0
z = 0
face = 0
minimumFuel = 100
missionMessage = "Mission complete."
abort = false
local currentFuelLevel = turtle.getFuelLevel()

if nArgs == 0 or (nArgs == 1 and args[1]== "help") then
	print("Creates a 2x2 tunnel with sealed sides.")
	print("Place fuel in slot 1")
	print("Place patch material (like cobblestone) in slot 2.")
	print("If torches are desired, place torches in slot 16.")
	print("Usage: branch <length>")
	return
end

if nArgs ~= 1 then
  print("Usage: branch <length>")
  return
end

length = tonumber(args[1])
if length == nil then
  print("\"", args[1], "\" is not a valid length")
  return
end
if length < 1 then
  print("length must be a positive number greater than zero")
end

targetArea = length
areaCovered = 1;


function left()
 if face == 0 then face = 1 turtle.turnLeft() return end 
 if face == 1 then face = 2 turtle.turnLeft() return end
 if face == 2 then face = 3 turtle.turnLeft() return end
 if face == 3 then face = 0 turtle.turnLeft() return end
 print("function left\(\): Bad face value: ", face)
end

function right()
 if face == 0 then face = 3 turtle.turnRight() return end 
 if face == 1 then face = 0 turtle.turnRight() return end
 if face == 2 then face = 1 turtle.turnRight() return end
 if face == 3 then face = 2 turtle.turnRight() return end
 print("function right\(\): Bad face value: ", face)
end

function up()
	success = false

	repeat
		while turtle.detectUp() do	-- This loop added in case of falling sand or whatever
		  turtle.digUp()
		end
	  success = turtle.up()
	until success
  y = y+1
end

function rise(nBlocks)
  local i
  for i=1,nBlocks do
    up()
  end
end

function descend(nBlocks)
  local i
  for i=1,nBlocks do
    down()
  end
end

function down()
  if turtle.detectDown() then
    turtle.digDown()
  end
  turtle.down()
  y = y-1
end


function forward()
	while turtle.detect() do	-- This loop added in case of falling sand or whatever
	  turtle.dig()
	end
	for i=1,10 do
		if turtle.forward() then
			break
		end
		turtle.attack()
		sleep(2)
	end
  	if face == 0 then z = z+1 return end
  	if face == 1 then x = x-1 return end
  	if face == 2 then z = z-1 return end
  	if face == 3 then x = x+1 return end
end

function patch()
	turtle.select(2)
	turtle.place()
end

function patchUp()
	turtle.select(2)
	turtle.placeUp()
end

function patchDown()
	turtle.select(2)
	turtle.placeDown()
end

addTorch = true
torchSpacing = 8
torchSpot = 6

function mineForward()
	forward()

	while turtle.detectUp() do	-- This loop added in case of falling sand or whatever
	  turtle.digUp()
--	  turtle.suckUp()
	end

	if turtle.detectDown() then
		turtle.digDown()
--		turtle.suckDown()
	end

	if addTorch then
		if (torchSpot % torchSpacing) == 0 then
			left()
			left()
			turtle.select(16)
			turtle.place()	
			right()
			right()
		end
	end
	torchSpot = torchSpot + 1
end

function setFace(f)
	if f == 0 then
	  if face == 0 then return end
	  if face == 1 then right() return end
	  if face == 2 then right() right() return end
	  if face == 3 then left() return end
	end

	if f == 1 then
	  if face == 0 then left() return end
	  if face == 1 then return end
	  if face == 2 then right() return end
	  if face == 3 then right() right() return end
	end

	if f == 2 then
	  if face == 0 then left() left() return end
	  if face == 1 then left() return end
	  if face == 2 then return end
	  if face == 3 then right() return end
	end

	if f == 3 then
	  if face == 0 then right() return end
	  if face == 1 then left() left() return end
	  if face == 2 then left() return end
	  if face == 3 then return end
	end
end

function checkFuel()
	if currentFuelLevel == "unlimited" then
		return true
	end

	if currentFuelLevel < minimumFuel then
	  if not turtle.refuel(200) then
		  areaCovered = targetArea
		  missionMessage = "Mission aborted due to low fuel."
		  abort = true
	    return false
	  end
	end
  return true
end

function home(targetY)
--  print("home:face ", face, ", x = ", x, ", z = ", z)
  if x < 0 then
	setFace(3)
	while x < 0 do
	  forward()
	end
  else
    if x > 0 then
  	  setFace(1)
	  while x > 0 do
	    forward()
	  end
    end
  end

  if z < 0 then
	setFace(0)
	while z < 0 do
	  forward()
	end
  else
    if z > 0 then
  	  setFace(2)
	  while z > 0 do
	    forward()
	  end
    end
  end
end

function dump()
	for i=2,14 do
		turtle.select(i)
		turtle.dropDown()
	end
end

function branchLoop()
	torchSpot = 6
	local i

	for i=1,length do
		mineForward()
	end

	right()

	for i=1,3 do
		mineForward()
	end

	right()

	for i=1,length do
		mineForward()
	end

	setFace(0)
	down()

	if turtle.detectDown() then
		turtle.select(15)
		if not turtle.compareDown() then
			turtle.digDown()
--			turtle.suckDown()
			turtle.placeDown()
		end
	end
	if turtle.compareDown() then
		dump()
	end
end

-- MAIN PROGRAM

turtle.select(1)

print("Current Fuel Level: ", currentFuelLevel)

if currentFuelLevel ~= "unlimited" then
	if currentFuelLevel < minimumFuel then
		if not turtle.refuel() then
		  print("No fuel")
		  return
		end
	end
end

for loop=1,5 do
	addTorch = false

	rise(1)
	for i=1,5 do
	  mineForward()
	end
	turtle.back()
	turtle.back()
	left()
	addTorch = true
	branchLoop()
end


print(missionMessage, " Current fuel level is ", turtle.getFuelLevel())