tfarm.lua

local rowLength = 20
local numRows = 16
local turnRightFirst = true

local turnRightNext = turnRightFirst
local currentSlot = 1

function setActiveSlot(slotNumber)
    slotNumber = tonumber(slotNumber)
    if slotNumber ~= nil then
        currentSlot = slotNumber
        turtle.select(slotNumber)
    end
end

function harvest()
    print("Harvesting...")
    setActiveSlot(1)
    turtle.digDown()
    turtle.placeDown()
end

function refuelFromLastSlot()
    setActiveSlot(16)
    turtle.refuel()
end

function turn(numberOfTimes, goRight)
    if goRight == true then
        for i=0, numberOfTimes do
            turtle.turnRight()
        end
    else
        for i=0, numberOfTimes do
            turtle.turnLeft()
        end
    end
end

function returnHome()
    turtle.forward()
    turtle.turnRight()
    for i=0, 30 do
        turtle.forward()
    end
end

refuelFromLastSlot()
for i=0, numRows do
    for j=0, rowLength do
        turtle.forward()
        harvest()
    end

    turn(1, turnRightNext)
    turtle.forward()
    turtle.forward()
    turn(1, turnRightNext)
    turnRightNext = not turnRightNext
end

returnHome()