Function ncdirect_double_box 

pub unsafe extern "C" fn ncdirect_double_box(
    n: *mut ncdirect,
    ul: u64,
    ur: u64,
    ll: u64,
    lr: u64,
    ylen: c_uint,
    xlen: c_uint,
    ctlword: c_uint,
) -> c_int

ncdirect_box() with the double box-drawing characters