pub const rxctrl = packed struct {
        rxen:  u1,
        r1:    u15 = 0, // reserved
        rxcnt: u3,
        r2:    u13 = 0, // reserved

        pub fn init(enable: bool, rxcnt: u3) rxctrl {
            return rxctrl {
                .rxen  = @bitCast(u1, enable),
                .rxcnt = rxcnt,
            };
        }
    };