Modified Excavation Script

function digforward(n)
	for i = 1, n do
		repeat
			if turtle.detect() then turtle.dig() end
		until turtle.forward()
	if direction == 1 then gx = gx + 1 end
	if direction == 2 then gy = gy + 1 end
	if direction == 3 then gx = gx - 1 end
	if direction == 4 then gy = gy - 1 end
	end
end

function movedown(n)
	for i = 1, n do
		repeat
			if turtle.detectDown() then turtle.digDown() end
		until turtle.down()
		gz = gz + 1
	end
end

function moveup(n)
	for i = 1, n do
		repeat
			if turtle.detectUp() then turtle.digUp() end
		until turtle.up()
		gz = gz - 1
	end
end

function turnright(n)
	for i = 1, n do
		turtle.turnRight()
		direction = direction + 1
		if direction > 4 then direction = 1 end
	end
end

function dumpinventory()
	for i = 2, 16 do
		turtle.select(i)
		turtle.drop()
	end
	turtle.select(1)
end

function dumpores()
	local rx, ry, rz, rdirection = gx, gy, gz, direction
	gohome()
	face(3)
	dumpinventory()
	gotoz(rz)
	gotoy(ry)
	gotox(rx)
	face(rdirection)
end

function waitforfuel()
	local rx, ry, rz, rdirection = gx, gy, gz, direction
	gohome()
	face(3)
	dumpinventory()
	print("Turtle needs more fuel. Refill and press ENTER to continue.")
	io.read()
	refuel()
	gotoz(rz)
	gotoy(ry)
	gotox(rx)
	face(rdirection)
end

function digoutblock(isup, isdown)
	if isup and turtle.detectUp() and (not turtle.compareUp())
	then turtle.digUp() end
	if isdown and turtle.detectDown() and (not turtle.compareDown())
	then turtle.digDown() end
	if turtle.getItemCount(16) > 0 then dumpores() end
	if turtle.getFuelLevel() < 100 then waitforfuel() end
end

function turn(isright)
	if isright then
		turtle.turnRight()
		direction = direction + 1
		if direction > 4 then direction = 1 end
	else
		turtle.turnLeft()
		direction = direction - 1
		if direction < 1 then direction = 4 end
	end
end

function digoutrow(x, isup, isdown)
	digoutblock(isup, isdown)
	if x > 1 then digforward(1) digoutrow((x - 1), isup, isdown) end
end

function digoutlayer(x, y, isup, isdown, isright)
	digoutrow(x, isup, isdown)
	if y > 1 then
		turn(isright)
		digforward(1)
		turn(isright)
		digoutlayer(x, (y - 1), isup, isdown, (not isright))
	else turnright(2) end
end

function iseven(n)
	if math.fmod(n, 2) == 0 then return true
	else return false end
end

function getright(y, isright)
	if iseven(y) then return not isright
	else return isright end
end

function face(n)
	if direction == n then return end
	turnright(1)
	face(n)
end

function gotox(x)
	if gx > x then face(3)
	elseif gx < x then face(1)
	elseif gx == x then return end
	digforward(1)
	gotox(x)
end

function gotoy(y)
	if gy > y then face(4)
	elseif gy < y then face(2)
	elseif gy == y then return end
	digforward(1)
	gotoy(y)
end

function gotoz(z)
	if gz > z then moveup(1) gotoz(z) end
	if gz < z then movedown(1) gotoz(z) end
end

function gohome()
	gotox(0)
	gotoy(0)
	gotoz(0)
	face(1)
end

function excavate(x, y, z, isright)

	print("Excacating "..x.." "..y.." "..z)
	if z >= 3 then
		movedown(1)
		digoutlayer(x, y, true, true, isright)
	end

	if z > 3 then
		movedown(2)
		excavate(x, y, (z - 3), getright(y, isright))
	end

	if z == 2 then digoutlayer(x, y, false, true, isright) end
	if z == 1 then digoutlayer(x, y, false, false, isright) end
	if z < 4 then gohome() end
end

function refuel()
	for i = 1, 16 do
		turtle.select(i)
		turtle.refuel()
	end
	turtle.select(1)
end



refuel()

	turtle.select(1)
	gx = 0
	gy = 0
	gz = 0
	direction = 1
excavate(30, 3, 50, true)