Spiral.lua

local maxLength = 10
local layersToDig = 50
local layer = 0
while (layer < layersToDig)
do
    turtle.digDown()
    turtle.down()
    local currentLength = maxLength

    while (currentLength > 0)
    do
        local index2 = 0
        while (index2 < 4)
        do
            local index = 0
            if ((index == 0 and index2 == 3) or (currentLength < maxLength and index2 == 1))
            then
                currentLength = currentLength - 1
            end
            while (index < currentLength)
            do
                if (turtle.getFuelLevel() <= 2000)
                then
                    turtle.refuel(turtle.getItemCount(1)-1)
                end

                while (turtle.detect())
                do
                    turtle.dig()
                    os.sleep(0.5)
                end
                turtle.forward()
                index = index + 1
            end
            turtle.turnRight()
            index2 = index2 + 1
        end
    end
    turtle.turnLeft()
    local halfMax = (maxLength / 2) - 1
    local index = 0;
    while (index < halfMax)
    do
        turtle.forward()
        index = index + 1
    end
    turtle.turnLeft()
    local index = 0
    while (index < halfMax)
    do
        turtle.forward()
        index = index + 1
    end
    turtle.turnLeft()
    turtle.turnLeft()
    layer = layer + 1
end