ECC_POINT_INIT
struct ecc_point sum = ECC_POINT_INIT(sump[0], sump[1], ndigits);
ctx->pub_key = ECC_POINT_INIT(ctx->x, ctx->y,
struct ecc_point res = ECC_POINT_INIT(x1, y1, ndigits);
ctx->pub_key = ECC_POINT_INIT(ctx->_pubp[0], ctx->_pubp[1], ndigits);
struct ecc_point cc = ECC_POINT_INIT(s, e, ndigits); /* reuse s, e */