-static d0_bignum_t *zero, *one, *four, *temp0, *temp1, *temp2, *temp3, *temp4;
+static d0_bignum_t *zero, *one, *four;
+static d0_bignum_t *temp0, *temp1, *temp2, *temp3, *temp4; // FIXME make these thread safe by putting them in some per-thread object