Lua 5.1 logical right shift (32bit)

    -- logical right shift (32bit)
    local rshift = function(value, amount)
        if amount == 0 then
            return value
        end
        if amount < 0 then
            error("illegal argument #2: shift amount must be greater than zero.")
        end

        -- first logical right shift
        if value < 0 then
            assert(value >= -0xffffffff)
            value = 0x80000000 + math.floor(value / 2)
        else
            value = math.floor(value / 2)
        end
        -- and more
        for i = 2, amount do
            value = math.floor(value / 2)
        end
        return value
    end