Function creachadair_imath_sys::mp_int_exptmod

pub unsafe extern "C" fn mp_int_exptmod(
    a: mp_int,
    b: mp_int,
    m: mp_int,
    c: mp_int
) -> mp_result

Sets c to the value of a raised to the b power, reduced modulo m. It returns MP_RANGE if b < 0 or MP_UNDEF if m == 0.