Preparer

x,y,z=1,1,0
dir=0
count=turtle.getItemCount(1)

function Dig()
	local success,data=turtle.inspect()
	if success and not (data.name=="computercraft:turtle_expanded") then
		while turtle.detect() do
			turtle.dig()
		end
	end
end

function DigUp()
	local success,data=turtle.inspectUp()
	if success and not (data.name=="computercraft:turtle_expanded") then
		turtle.digUp()
	end
end

function DigDown()
	local success,data=turtle.inspectDown()
	if success then
		if data.name=="minecraft:bedrock" then return false
		elseif data.name=="computercraft:turtle_expanded" then
		else turtle.digDown()
		end
	end
	return true
end

function Forward()
	while not turtle.forward() do
		Dig()
		turtle.attack()
	end
	if (dir%2)==0 then y=y+1-(dir%4)
	else x=x+2-(dir%4)
	end
end

function Up()
	while not turtle.up() do
		DigUp()
		turtle.attackUp()
	end
	z=z+1
end

function Down()
	while not turtle.down() do
		DigDown()
		turtle.attackDown()
	end
	z=z-1
end

function Right()
	turtle.turnRight()
	dir=(dir-1)%4
end

function Left()
	turtle.turnLeft()
	dir=(dir+1)%4
end

function SelectCobble()
	for i=1,16 do
		local data=turtle.getItemDetail(i)
		if data and data.name=="minecraft:cobblestone" then
			turtle.select(i)
			break
		end
	end
end

if count>0 then
	turtle.select(1)
	DigDown() Down()
	DigDown() Down()
	DigDown()
	Left()
	for i=1,3*count do
		if (x%3)==0 then
			DigUp() turtle.placeUp()
		end
		Dig() Forward() DigDown()
	end
	DigUp() Up() DigUp() Up() DigUp() Up()
	Right() Dig() Forward() Right()
	while x>1 do
		DigUp()
		SelectCobble() turtle.placeUp()
		Dig() Forward()
	end
	SelectCobble() turtle.placeUp()
	Left()
end