adde flowlet_switching exercise

SIGCOMM_2015/flowlet_switching/p4src/includes/parser.p4

@@ -0,0 +1,77 @@
+/*
+Copyright 2013-present 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.
+*/
+
+parser start {
+    return parse_ethernet;
+}
+
+#define ETHERTYPE_IPV4 0x0800
+
+header ethernet_t ethernet;
+
+parser parse_ethernet {
+    extract(ethernet);
+    return select(latest.etherType) {
+        ETHERTYPE_IPV4 : parse_ipv4;
+        default: ingress;
+    }
+}
+
+header ipv4_t ipv4;
+
+field_list ipv4_checksum_list {
+        ipv4.version;
+        ipv4.ihl;
+        ipv4.diffserv;
+        ipv4.totalLen;
+        ipv4.identification;
+        ipv4.flags;
+        ipv4.fragOffset;
+        ipv4.ttl;
+        ipv4.protocol;
+        ipv4.srcAddr;
+        ipv4.dstAddr;
+}
+
+field_list_calculation ipv4_checksum {
+    input {
+        ipv4_checksum_list;
+    }
+    algorithm : csum16;
+    output_width : 16;
+}
+
+calculated_field ipv4.hdrChecksum  {
+    verify ipv4_checksum;
+    update ipv4_checksum;
+}
+
+#define IP_PROTOCOLS_TCP 6
+
+parser parse_ipv4 {
+    extract(ipv4);
+    return select(latest.protocol) {
+        IP_PROTOCOLS_TCP : parse_tcp;
+        default: ingress;
+    }
+}
+
+header tcp_t tcp;
+
+parser parse_tcp {
+    extract(tcp);
+    return ingress;
+}