Function pio_gens 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn pio_gens(
    net: *const PioNetwork,
    bus: *mut i64,
    pg: *mut f64,
    pmax: *mut f64,
    pmin: *mut f64,
    in_service: *mut u8,
    cap: usize,
) -> usize

Write the generator table as parallel arrays, each up to cap entries, and return the total generator count. bus is the 1-based bus id (the pio_bus_ids id space). Any output pointer may be NULL to skip.