Function ffpcnb 

pub unsafe extern "C" fn ffpcnb(
    fptr: *mut fitsfile,
    colnum: c_int,
    firstrow: LONGLONG,
    firstelem: LONGLONG,
    nelem: LONGLONG,
    array: *mut c_uchar,
    nulvalue: c_uchar,
    status: *mut c_int,
) -> c_int