[V5,6/6] examples/pipeline: add packet recirculation example

diff --git a/examples/pipeline/examples/recirculation.cli b/examples/pipeline/examples/recirculation.cli
new file mode 100644
index 0000000000..f855c5c327
--- /dev/null
+++ b/examples/pipeline/examples/recirculation.cli
@@ -0,0 +1,34 @@ 
+; SPDX-License-Identifier: BSD-3-Clause
+; Copyright(c) 2022 Intel Corporation
+
+;
+; Customize the LINK parameters to match your setup.
+;
+mempool MEMPOOL0 buffer 2304 pool 32K cache 256 cpu 0
+
+link LINK0 dev 0000:18:00.0 rxq 1 128 MEMPOOL0 txq 1 512 promiscuous on
+link LINK1 dev 0000:18:00.1 rxq 1 128 MEMPOOL0 txq 1 512 promiscuous on
+link LINK2 dev 0000:3b:00.0 rxq 1 128 MEMPOOL0 txq 1 512 promiscuous on
+link LINK3 dev 0000:3b:00.1 rxq 1 128 MEMPOOL0 txq 1 512 promiscuous on
+
+;
+; PIPELINE0 setup.
+;
+pipeline PIPELINE0 create 0
+
+pipeline PIPELINE0 port in 0 link LINK0 rxq 0 bsz 32
+pipeline PIPELINE0 port in 1 link LINK1 rxq 0 bsz 32
+pipeline PIPELINE0 port in 2 link LINK2 rxq 0 bsz 32
+pipeline PIPELINE0 port in 3 link LINK3 rxq 0 bsz 32
+
+pipeline PIPELINE0 port out 0 link LINK0 txq 0 bsz 32
+pipeline PIPELINE0 port out 1 link LINK1 txq 0 bsz 32
+pipeline PIPELINE0 port out 2 link LINK2 txq 0 bsz 32
+pipeline PIPELINE0 port out 3 link LINK3 txq 0 bsz 32
+
+pipeline PIPELINE0 build ./examples/pipeline/examples/recirculation.spec
+
+;
+; Pipelines-to-threads mapping.
+;
+thread 1 pipeline PIPELINE0 enable
diff --git a/examples/pipeline/examples/recirculation.spec b/examples/pipeline/examples/recirculation.spec
new file mode 100644
index 0000000000..3cc115610e
--- /dev/null
+++ b/examples/pipeline/examples/recirculation.spec
@@ -0,0 +1,81 @@ 
+; SPDX-License-Identifier: BSD-3-Clause
+; Copyright(c) 2022 Intel Corporation
+
+; This simple example illustrates how to perform packet recirculation. The "recirculate" instruction
+; is used to mark the current packet for recirculation, which means that at TX time the packet is
+; reinjected into the pipeline for another full pass as opposed to being sent to the output port.
+;
+; The same packet can be recirculated multiple times, with the recirculation pass ID retrieved by
+; the "recircid" instruction. The pass ID can be used by the program to execute different code on
+; the same packet in different pipeline passes. The packet meta-data is preserved between the
+; pipeline passes.
+
+//
+// Headers
+//
+struct ethernet_h {
+	bit<48> dst_addr
+	bit<48> src_addr
+	bit<16> ethertype
+}
+
+struct ipv4_h {
+	bit<8> ver_ihl
+	bit<8> diffserv
+	bit<16> total_len
+	bit<16> identification
+	bit<16> flags_offset
+	bit<8> ttl
+	bit<8> protocol
+	bit<16> hdr_checksum
+	bit<32> src_addr
+	bit<32> dst_addr
+}
+
+struct udp_h {
+	bit<16> src_port
+	bit<16> dst_port
+	bit<16> length
+	bit<16> checksum
+}
+
+header ethernet instanceof ethernet_h
+header ipv4 instanceof ipv4_h
+header udp instanceof udp_h
+
+//
+// Meta-data.
+//
+struct metadata_t {
+	bit<32> port
+	bit<32> pass_id
+}
+
+metadata instanceof metadata_t
+
+//
+// Pipeline.
+//
+apply {
+	rx m.port
+	extract h.ethernet
+	extract h.ipv4
+	extract h.udp
+
+	//
+	// State machine based on the recirculation pass ID.
+	//
+	// During each of the first 5 passes through the pipeline (m.pass_id is 0 .. 4), the UDP
+	// source port is incremented and the packet is marked for recirculation, while on the final
+	// iteration (m.pass_id is 5) the packet is sent out.
+	//
+	recircid m.pass_id
+	jmpgt EMIT m.pass_id 4
+	add h.udp.src_port 1
+	recirculate
+
+	EMIT : emit h.ethernet
+	emit h.ipv4
+	emit h.udp
+	tx m.port
+}