addrmap top {
    reg {
        regwidth = 64;
        accesswidth = 32;
        field {
            sw=w;
            hw=r;
        } xf[64];
    } x;

    reg {
        regwidth = 64;
        accesswidth = 32;
        field {
            sw=r;
            hw=w;
            we;
            onread=rclr;
        } yf[64];
    } y;
};