added 3 bmv2 examples: copy_to_cpu, meter, TLV_parsing

examples/copy_to_cpu/p4src/copy_to_cpu.p4

@@ -0,0 +1,87 @@
+header_type ethernet_t {
+    fields {
+        dstAddr : 48;
+        srcAddr : 48;
+        etherType : 16;
+    }
+}
+
+header_type intrinsic_metadata_t {
+    fields {
+        mcast_grp : 4;
+        egress_rid : 4;
+        mcast_hash : 16;
+        lf_field_list: 32;
+    }
+}
+
+header_type cpu_header_t {
+    fields {
+        device: 8;
+        reason: 8;
+    }
+}
+
+header cpu_header_t cpu_header;
+
+parser start {
+    return select(current(0, 64)) {
+        0 : parse_cpu_header;
+        default: parse_ethernet;
+    }
+}
+
+header ethernet_t ethernet;
+metadata intrinsic_metadata_t intrinsic_metadata;
+
+parser parse_ethernet {
+    extract(ethernet);
+    return ingress;
+}
+
+parser parse_cpu_header {
+    extract(cpu_header);
+    return parse_ethernet;
+}
+
+action _drop() {
+    drop();
+}
+
+action _nop() {
+}
+
+#define CPU_MIRROR_SESSION_ID                  250
+
+field_list copy_to_cpu_fields {
+    standard_metadata;
+}
+
+action do_copy_to_cpu() {
+    clone_ingress_pkt_to_egress(CPU_MIRROR_SESSION_ID, copy_to_cpu_fields);
+}
+
+table copy_to_cpu {
+    actions {do_copy_to_cpu;}
+    size : 1;
+}
+
+control ingress {
+    apply(copy_to_cpu);
+}
+
+action do_cpu_encap() {
+    add_header(cpu_header);
+    modify_field(cpu_header.device, 0);
+    modify_field(cpu_header.reason, 0xab);
+}
+
+table redirect {
+    reads { standard_metadata.instance_type : exact; }
+    actions { _drop; do_cpu_encap; }
+    size : 16;
+}
+
+control egress {
+    apply(redirect);
+}