Turtle Counter

-- Simple program that mines forward along a 1x2 passageway until
-- it detects a block corresponding to the block in (tstslt) then it returns
-- to the start. It then outputs the number of blocks to the required block
-- v03
-- by LN

local travld = 0 -- How many blocks we travel
local dist = 0 -- As above
local done = 0 -- when 1 indicates block matching tstslt matched
local job = "Counter"
local tstslt = 16 -- Slot to compare against (1-16)

local function refuel()
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" or fuelLevel > 0 then
        return
    end

    local function tryRefuel()
        for n=1,16 do
            if turtle.getItemCount(n) > 0 then
                turtle.select(n)
                if turtle.refuel(1) then
                    turtle.select(1)
                    return true
                end
            end
        end
        turtle.select(1)
        return false
    end

    if not tryRefuel() then
        print( "Add more fuel to continue." )
        while not tryRefuel() do
            sleep(1)
        end
        print( "Resuming..." ..job)
    end
end

local function tryDigDown()
    while turtle.detectDown() do
        turtle.digDown()
        sleep(0.5)
    end
end

local function tryDig()
    while turtle.detect() do
        turtle.dig()
        sleep(0.5)
    end
end

local function tryForward()
    refuel()
    while not turtle.forward() do
        if turtle.detect() then
            if not tryDig() then
                return false
            end
        elseif turtle.attack() then
        else
            sleep( 0.5 )
        end
    end
    return true
end

local function testDown()
end

local function reverse()
    turtle.turnLeft()
    turtle.turnLeft()
end

local function travel()
    while done ~= 1 do
        turtle.select(16)
        if turtle.compareDown() then
            done = 1
--          travld = travld + 1
            print("True")
        else
            done = 0
            print("False")
            if (done == 0) then
                tryDigDown()
                tryDig()
                tryForward()
                travld = travld + 1
            end
        end
    turtle.select(1)
    print("Done = " .. done)
    end
end

local function rtb()
reverse()
dist = travld
while dist > 0 do
    tryForward()
    dist = dist - 1
end
reverse()
end

-- Program...


travel()
rtb()
print("This Turtle Counted a total of: " .. travld .. " blocks before RTB.")