Turtle circle/cylinder digger

-- by morganamilo ([email protected]) based on http://pastebin.com/TgDE8CSY

local args = {...}
local radius = tonumber(args[1]) --the size of the radius includes the center block
local depth = tonumber(args[2])

local usage = 'Usage:' .. shell.getRunningProgram() .. ' <radius> <depth>'

if table.getn(args) ~= 2 then
  print(usage)
  error()
end

if radius == nil or depth == nil then
  print('Radius and depth must both be numbers')
  error()
end

if radius ~= math.floor(args[1]) or depth ~= math.floor(args[2]) then
  print('Radius and depth must be whole numbers')
  error()
end

if radius < 3 or depth < 1 then
  print('Radius must be at least 3, depth must be at least 1')
  error()
end

local x = 0
local y = 0 --in minecraft y is really z but the turtles coords are relative to itself so it doesnt matter

local xDiff = {0, 1, 0, -1}
local yDiff = {1, 0, -1, 0}

local orient = 1
local moves = {}

function forward()
  x = x + xDiff[orient + 1]
  y = y + yDiff[orient + 1]

  table.insert(moves, 'forward')
end

function left()
  orient = orient - 1
  orient = (orient % 4)

  if moves[table.getn(moves)] ~= 'right' then
     table.insert(moves, 'left')
  else
    table.remove(moves)
  end
end

function right()
  orient = orient + 1
  orient = (orient % 4)

  table.insert(moves, 'right')
end

function doMoves()
  for n = 1, table.getn(moves) do
    if moves[n] == 'forward' then
      turtle.dig()
      while turtle.forward() == false do
        if turtle.getFuelLevel() == 0 then
          print('Out of fuel\nWaiting for fuel in slot 1...')
            while turtle.getFuelLevel() == 0 do
             turtle.refuel()
             end
             print('Fuel level is: ' .. turtle.getFuelLevel())

          end
        end
    end
    if moves[n] == 'left' then
      turtle.turnLeft() end
    if moves[n] == 'right' then
      turtle.turnRight() end
  end
  moves = {}
end

function round(n)
  if n - math.floor(n) >= 0.5 then
    return math.ceil(n)
  else
    return math.floor(n)
  end
end

function inRad(x, y, rad)
  return round(math.sqrt(x*x+y*y)) < rad
end

function nextInRad(rad)
  nextX = x + xDiff[orient + 1]
  nextY = y + yDiff[orient + 1]
  return inRad(nextX, nextY, rad)
end

function digRing(rad)
  while nextInRad(rad) do forward() end
  left()

  originalX = x
  originalY = y

  repeat
    while nextInRad(rad) do forward() end
    while not nextInRad(rad) do left() end
    forward()
    right()
  until x == originalX and y == originalY

  doMoves()
end

function digLayer()
  for n=1,4 do
    turtle.dig()
    turtle.turnLeft()
  end

  for n = 2, radius do
    digRing(n)
  end

  left()
  left()
  for n = 2, radius do
    forward()
  end
  left()
  left()
  doMoves()
end

function digCyl()
  for n = 1, depth do
    digLayer(radius)
    if n ~= depth then
      turtle.digDown()
      while turtle.down() == false do
          if turtle.getFuelLevel() == 0 then
            print('Out of fuel\nWaiting for fuel in slot 1...')
              while turtle.getFuelLevel() == 0 do
                turtle.refuel()
              end
                print('Fuel level is: ' .. turtle.getFuelLevel())
          end
      end
    end
  end
end

digCyl()
print('Done!')