+/* Makes subfield 'sf' within 'flow' exactly match the 'sf->n_bits'
+ * least-significant bits in 'x'.
+ */
+void
+mf_write_subfield_flow(const struct mf_subfield *sf,
+ const union mf_subvalue *x, struct flow *flow)
+{
+ const struct mf_field *field = sf->field;
+ union mf_value value;
+
+ mf_get_value(field, flow, &value);
+ bitwise_copy(x, sizeof *x, sf->ofs, &value, field->n_bytes,
+ sf->ofs, sf->n_bits);
+ mf_set_flow_value(field, &value, flow);
+}
+