Better Computer Craft Turtle Item Sorter

slotsFinished = {}
for fillIndex = 1, 16 do
    slotsFinished[fillIndex] = false
end

function compactInv()
    for checkSlot = 1, 16 do
        if turtle.getItemCount(checkSlot) > 0 then
            turtle.select(checkSlot)
            for testSlot = checkSlot, 16 do
                if turtle.compareTo(testSlot) then
                    turtle.select(testSlot)
                    turtle.transferTo(checkSlot, turtle.getItemCount(testSlot))
                    turtle.select(checkSlot)
                end
            end
        end
    end
end

function cleanInv(startSlot, stopSlot, stepSize)
    if stepSize > 0 then
        stepSize = 1
        endOfInv = 1
    elseif stepSize < 0 then
        stepSize = -1
        endOfInv = 16
    else
        stepSize = -1
        endOfInv = 16
    end

    if startSlot > 16 then startSlot = 16 end
    if startSlot < 1 then startSlot = 1 end
    if stopSlot > 16 then stopSlot = 16 end
    if stopSlot < 1 then stopSlot = 1 end

    for checkSlot = startSlot, stopSlot, stepSize do
        while turtle.getItemCount(checkSlot) > 0 do
            moveSlot = endOfInv
            turtle.select(checkSlot)
            while not turtle.transferTo(moveSlot, turtle.getItemCount(checkSlot)) do
                moveSlot = moveSlot + stepSize
            end
            if moveSlot == checkSlot then
                break
            end
        end
    end
end

function checkIfFull() --returns true if the inventory is full and needs to dropUp() the first slot to free a slot
    if turtle.getItemCount(1) > 0 then
        return true
    else
        return false
    end
end

function getNextUnsorted()
    for checkIndex = 1, 16 do
        if not slotsFinished[checkIndex] then
            return checkIndex -- returns the first unsorted slot
            -- break -- should be unnecessary, but there just in case
        end
    end
    return 0
end

function sortInv()
    local droppedItem = false
    if checkIfFull() then
        turtle.select(1)
        turtle.dropUp()
        droppedItem = true
    end
    sortsMade = 0
    while sortsMade <= 16 do
        turtle.select(16)
        openSlot = getNextUnsorted()
        turtle.transferTo(openSlot, turtle.getItemCount(16))
        slotsFinished[openSlot] = true
        cleanInv(16, getNextUnsorted(), -1)
        sortsMade = sortsMade + 1
        for checkSlot = 16, openSlot, -1 do
            if checkSlot == (getNextUnsorted()) then
                break
            end
            turtle.select(openSlot)
            if turtle.compareTo(checkSlot) then
                turtle.select(checkSlot)
                while turtle.getItemCount(checkSlot) > 0 do
                    moveSlot = openSlot + 1
                    while not turtle.transferTo(moveSlot, turtle.getItemCount(checkSlot)) do
                        moveSlot = moveSlot + 1
                    end
                end
                slotsFinished[moveSlot] = true
                cleanInv(checkSlot, getNextUnsorted(), -1)
                sortsMade = sortsMade + 1
                checkSlot = 16
            end
        end
    end
    if droppedItem then
        turtle.suckUp()
    end
end

compactInv()
cleanInv(16, 1, -1)
sortInv()
cleanInv(1, 16, 1)
turtle.select(1)