Turbo Tree Overflow

rednet.open("left")

local mainID = 15

local function forward(count)
    for k = 1,count do
        turtle.forward()
    end
end

local function goUp(count)
    for k = 1,count do
        turtle.up()
    end
end

local function goDown(count)
    for k = 1,count do
        turtle.down()
    end
end

while true do
    while turtle.getItemCount() == 0 do    --Get items
        if not turtle.suck() then
            rednet.send(mainID, "home")
            sleep(.5)
            local a = 5
            while a ~= 0 do
                rednet.send(mainID, tostring(a))
                sleep(60)
            end
            rednet.send(mainID, tostring(a))
        end
    end

    rednet.send(mainID, "away")
    local data = turtle.getItemDetail()

    if data.name == "minecraft:log" then    --Sort logs
        turtle.turnRight()
        turtle.turnRight()
        forward(8)
        turtle.turnLeft()
        goDown(2)
        if not turtle.drop() then   --Try to put in one of 3 chests
            goDown(1)
            if not turtle.drop() then
                turtle.dropDown()
                goUp(1)
            end
            goUp(1)
        end
        goUp(2)
        turtle.turnLeft()
        forward(8)
    elseif data.name == "minecraft:sapling" then    --Sort saplings
        turtle.turnRight()
        goDown(2)
        if not turtle.drop() then
            goDown(1)
            if not turtle.drop() then
                turtle.dropDown()
            end
            goUp(1)
        end
        goUp(2)
    elseif data.name == "minecraft:coal" then   --Sort charcoal, refuel if needed
        if turtle.getFuelLevel() < (turtle.getFuelLimit() - 5120) then
            turtle.refuel()
        else
            goDown(3)
            turtle.dropDown()
            goUp(3)
        end
    else    --Sort everything else
        turtle.turnRight()
        turtle.turnRight()
        forward(8)
        turtle.turnLeft()
        goDown(4)
        if not turtle.drop() then
            turtle.dropDown()
        end
        goUp(4)
        turtle.turnLeft()
        forward(8)
    end
end

rednet.close("left")