Turtle circle/cylinder digger v2.0

-- 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 z = 0

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

local orient = 1

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

  moved = turtle.forward()

  while not moved 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
    if turtle.detect() then turtle.dig() end
    moved = turtle.forward()
  end

  if z > -depth + 1 and turtle.detectDown() then turtle.digDown() end
  if turtle.detectUp() then turtle.digUp() end
end

function left()
  orient = orient - 1
  orient = (orient % 4)
  turtle.turnLeft()
end

function right()
  orient = orient + 1
  orient = (orient % 4)
  turtle.turnRight()
end

function down()
  if turtle.detectDown() then turtle.digDown() end
  moved = turtle.down()
  if not moved then
    repeat
        if turtle.detectDown() then turtle.digDown() end
        moved = turtle.down()
    until moved
  end
  z = z - 1
  if turtle.detectDown() and z > -depth + 1 then turtle.digDown() end
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 turn(n)
  if n % 2 == 0 then left()
  else right() end
end

function digLayer()
  for n = 1, (radius -1)*2 do
    while nextInRad(radius) do forward() end
    turn(n)
    if nextInRad(radius) then
      forward()
      if not (inRad(x, y - 1, radius) and inRad(x, y + 1, radius)) then
      turn(n)
      else
        turn(n + 1)
        while nextInRad(radius) do forward() end
        turn(n)
        turn(n)
      end

    else
      turn(n)
      while not inRad(x - 1, y, radius) or not inRad(x + 1, y, radius) do forward() end
      turn(n + 1)
      forward()
      turn(n)
    end
  end
  while nextInRad(radius) do forward() end

  left()
    left()
    if n ~= depth then
      for n = 1, 3 do
        if z > -depth + 1 then down() end
      end
    end
end

function digCyl()
  if depth > 1 then down() end
  for n = 1, 2 do
    while nextInRad(radius) do forward() end
    left()
  end
  left()

  for n = 1, (round((depth + 1)/3)*3)/3 do
    digLayer()
  end
  --if z > -depth + 1 then digLayer() end

  while y ~= 0 do forward() end
  turn(orient + 1)
  while x ~= 0 do forward() end
end

digCyl()
print('Done!')