+void
+nxm_format_stack_pop(const struct ofpact_stack *pop, struct ds *s)
+{
+ ds_put_cstr(s, "pop:");
+ mf_format_subfield(&pop->subfield, s);
+}
+
+/* Common set for both push and pop actions. */
+static void
+stack_action_from_openflow__(const struct nx_action_stack *nasp,
+ struct ofpact_stack *stack_action)
+{
+ stack_action->subfield.field = mf_from_nxm_header(ntohl(nasp->field));
+ stack_action->subfield.ofs = ntohs(nasp->offset);
+ stack_action->subfield.n_bits = ntohs(nasp->n_bits);
+}
+
+static void
+nxm_stack_to_nxast__(const struct ofpact_stack *stack_action,
+ struct nx_action_stack *nasp)
+{
+ nasp->offset = htons(stack_action->subfield.ofs);
+ nasp->n_bits = htons(stack_action->subfield.n_bits);
+ nasp->field = htonl(stack_action->subfield.field->nxm_header);
+}
+
+enum ofperr
+nxm_stack_push_from_openflow(const struct nx_action_stack *nasp,
+ struct ofpbuf *ofpacts)
+{
+ struct ofpact_stack *push;
+
+ push = ofpact_put_STACK_PUSH(ofpacts);
+ stack_action_from_openflow__(nasp, push);
+
+ return nxm_stack_push_check(push, NULL);
+}
+
+enum ofperr
+nxm_stack_pop_from_openflow(const struct nx_action_stack *nasp,
+ struct ofpbuf *ofpacts)
+{
+ struct ofpact_stack *pop;
+
+ pop = ofpact_put_STACK_POP(ofpacts);
+ stack_action_from_openflow__(nasp, pop);
+
+ return nxm_stack_pop_check(pop, NULL);
+}
+
+enum ofperr
+nxm_stack_push_check(const struct ofpact_stack *push,
+ const struct flow *flow)
+{
+ return mf_check_src(&push->subfield, flow);
+}
+
+enum ofperr
+nxm_stack_pop_check(const struct ofpact_stack *pop,
+ const struct flow *flow)
+{
+ return mf_check_dst(&pop->subfield, flow);
+}
+
+void
+nxm_stack_push_to_nxast(const struct ofpact_stack *stack,
+ struct ofpbuf *openflow)
+{
+ nxm_stack_to_nxast__(stack, ofputil_put_NXAST_STACK_PUSH(openflow));
+}
+
+void
+nxm_stack_pop_to_nxast(const struct ofpact_stack *stack,
+ struct ofpbuf *openflow)
+{
+ nxm_stack_to_nxast__(stack, ofputil_put_NXAST_STACK_POP(openflow));
+}
+
+/* nxm_execute_stack_push(), nxm_execute_stack_pop(). */
+static void
+nx_stack_push(struct ofpbuf *stack, union mf_subvalue *v)
+{
+ ofpbuf_put(stack, v, sizeof *v);
+}
+
+static union mf_subvalue *
+nx_stack_pop(struct ofpbuf *stack)
+{
+ union mf_subvalue *v = NULL;
+
+ if (ofpbuf_size(stack)) {
+
+ ofpbuf_set_size(stack, ofpbuf_size(stack) - sizeof *v);
+ v = (union mf_subvalue *) ofpbuf_tail(stack);
+ }
+
+ return v;
+}
+
+void
+nxm_execute_stack_push(const struct ofpact_stack *push,
+ const struct flow *flow, struct flow_wildcards *wc,
+ struct ofpbuf *stack)
+{
+ union mf_subvalue mask_value;
+ union mf_subvalue dst_value;
+
+ memset(&mask_value, 0xff, sizeof mask_value);
+ mf_write_subfield_flow(&push->subfield, &mask_value, &wc->masks);
+
+ mf_read_subfield(&push->subfield, flow, &dst_value);
+ nx_stack_push(stack, &dst_value);
+}
+
+void
+nxm_execute_stack_pop(const struct ofpact_stack *pop,
+ struct flow *flow, struct flow_wildcards *wc,
+ struct ofpbuf *stack)
+{
+ union mf_subvalue *src_value;
+
+ src_value = nx_stack_pop(stack);
+
+ /* Only pop if stack is not empty. Otherwise, give warning. */
+ if (src_value) {
+ union mf_subvalue mask_value;
+
+ memset(&mask_value, 0xff, sizeof mask_value);
+ mf_write_subfield_flow(&pop->subfield, &mask_value, &wc->masks);
+ mf_write_subfield_flow(&pop->subfield, src_value, flow);
+ } else {
+ if (!VLOG_DROP_WARN(&rl)) {
+ char *flow_str = flow_to_string(flow);
+ VLOG_WARN_RL(&rl, "Failed to pop from an empty stack. On flow \n"
+ " %s", flow_str);
+ free(flow_str);
+ }
+ }