z_count = 0
face = 1

function turn_left()
	turtle.turnLeft()
	if face == 0 then
		face = 1
	elseif face == 1 then
		face = 2
	elseif face == 2 then
		face = 3
	elseif face == 3 then
		face = 0
	end
end

function turn_right()
	turtle.turnRight()
	if face == 0 then
		face = 3
	elseif face == 1 then
		face = 0
	elseif face == 2 then
		face = 1
	elseif face == 3 then
		face = 2
	end
end

function dig_x(width)
	for i = 0,width, 1
	do
		turtle.digUp()
		turtle.dig()
		turtle.forward()
	end
end

	-- dig and move down one block to start the staircase
--	turtle.digDown()
--	turtle.down()
	-- we moved down once, so we increment the z_count
--	z_count = z_count + 1

function dig(width)
	-- face: 1, the starting position
	if face == 1 then
		turn_right()
		turtle.digDown()
		turtle.down()
		dig_x(width - 1)
	-- face: 0, we are faced right from starting position
	elseif face == 0 then
		turn_left()
		turtle.dig()
		turtle.forward()
		turn_left()
		dig_x(width - 1)
		turn_right()
		-- dig
	end
end

while(true)
	do
		dig(4)
	end