ec_GF2m_add
MP_CHECKOK(ec_GF2m_add(&ry, &rx, &ry, group->meth));
MP_CHECKOK(ec_GF2m_add(&ry, &rx, &ry, group->meth));
MP_CHECKOK(ec_GF2m_add(&ry, &rx, &ry, group->meth));
mp_err ec_GF2m_add(const mp_int *a, const mp_int *b, mp_int *r,
meth->field_add = &ec_GF2m_add;
meth->field_sub = &ec_GF2m_add;