nth_kday

static VALUE
datetime_s_nth_kday(int argc, VALUE *argv, VALUE klass)
{
    VALUE vy, vm, vn, vk, vh, vmin, vs, vof, vsg, y, fr, fr2, ret;
    int m, n, k, h, min, s, rof;
    double sg;

    rb_scan_args(argc, argv, "09", &vy, &vm, &vn, &vk,
                 &vh, &vmin, &vs, &vof, &vsg);

    y = INT2FIX(-4712);
    m = 1;
    n = 1;
    k = 1;

    h = min = s = 0;
    fr2 = INT2FIX(0);
    rof = 0;
    sg = DEFAULT_SG;

    switch (argc) {
      case 9:
        val2sg(vsg, sg);
      case 8:
        val2off(vof, rof);
      case 7:
        num2int_with_frac(s, positive_inf);
      case 6:
        num2int_with_frac(min, 6);
      case 5:
        num2int_with_frac(h, 5);
      case 4:
        num2int_with_frac(k, 4);
      case 3:
        n = NUM2INT(vn);
      case 2:
        m = NUM2INT(vm);
      case 1:
        y = vy;
    }

    {
        VALUE nth;
        int ry, rm, rn, rk, rh, rmin, rs, rjd, rjd2, ns;

        if (!valid_nth_kday_p(y, m, n, k, sg,
                              &nth, &ry,
                              &rm, &rn, &rk, &rjd,
                              &ns))
            rb_raise(rb_eArgError, "invalid date");
        if (!c_valid_time_p(h, min, s, &rh, &rmin, &rs))
            rb_raise(rb_eArgError, "invalid date");
        canon24oc();

        rjd2 = jd_local_to_utc(rjd,
                               time_to_df(rh, rmin, rs),
                               rof);
        ret = d_complex_new_internal(klass,
                                     nth, rjd2,
                                     0, INT2FIX(0),
                                     rof, sg,
                                     0, 0, 0,
                                     rh, rmin, rs,
                                     HAVE_JD | HAVE_TIME);
    }
    add_frac();
    return ret;
}