gistfile1.lua

function isValuable()
        if not turtle.detect() then return false end

        for i=1,3 do
                turtle.select(i)
                if turtle.compare() then
                        print ("Same as "..i)
                        return false
                end
        end

        return true
end

function dive()
        local x, y, z = gps.locate(5)
        local todive = z - 6 -- Only want to go down to z = 6 to avoid bedrock.
        for depth=1,todive do

                -- Move down, digging first if we have to
                if turtle.detectDown() then
                        turtle.digDown()
                end
                turtle.down()
 
                -- Check around us for things we might want to gather
                for i=1,4 do
                        if isValuable() then turtle.dig() end
                        turtle.turnRight()
                end
        end
end
 
local tArgs = { ... }
local size
if tArgs[1] == nil then 
	size = 10
else
	size = tonumber(tArgs[1])
end

rednet.open("right")
local startx, starty, startz = gps.locate(5)
for inner=1,size do
        dive()
        local newx, newy, newz = gps.locate(5)
        local rise = startz - newz
        for i=1,rise do
                turtle.up()
        end
        turtle.turnRight()
        turtle.forward()
        turtle.forward()
        turtle.forward()
        turtle.forward()
        turtle.turnLeft()
end