Function secp256k1_ellswift_xdh

pub unsafe extern "C" fn secp256k1_ellswift_xdh(
    ctx: *const Context,
    output: *mut u8,
    ell_a64: *const u8,
    ell_b64: *const u8,
    seckey32: *const u8,
    party: i32,
    hashfp: Option<unsafe extern "C" fn(_: *mut u8, _: *const u8, _: *const u8, _: *const u8, _: *mut c_void) -> i32>,
    data: *mut c_void,
) -> i32