Support for the P4 language

P4 is a language to describe the processing pipeline of network devices

samples/P4/mirror_acl.p4

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+// Copyright 2015, Barefoot Networks, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+action set_mirror_id(session_id) {
+    clone_ingress_pkt_to_egress(session_id);
+}
+
+table mirror_acl {
+    reads {
+        ingress_metadata.if_label : ternary;
+        ingress_metadata.bd_label : ternary;
+
+        /* ip acl */
+        ingress_metadata.lkp_ipv4_sa : ternary;
+        ingress_metadata.lkp_ipv4_da : ternary;
+        ingress_metadata.lkp_ip_proto : ternary;
+
+        /* mac acl */
+        ingress_metadata.lkp_mac_sa : ternary;
+        ingress_metadata.lkp_mac_da : ternary;
+        ingress_metadata.lkp_mac_type : ternary;
+    }
+    actions {
+        nop;
+        set_mirror_id;
+    }
+    size : INGRESS_MIRROR_ACL_TABLE_SIZE;
+}