This example expands on the definition of crypto_accelerator (#53).

The example adds two methods for encrypt/decrypt that assumes that inline accelerators operate immediately on the packet (e.g. deparse, decrypt and reparse).  Packet recirculation is not necessary for either inline method.
The example shows the use of inline encrypt and decrypt, as well as how the crypto accelerator results can be used.

examples/crypto-inline.p4

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+/*
+Copyright 2022 Advanced Micro Devices, 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.
+*/
+
+#include <core.p4>
+#include "../pna.p4"
+
+/// Crypto accelerator Extern
+enum bit<8> crypto_algorithm_e {
+    AES_GCM = 1
+}
+enum bit<8> crypto_results_e {
+    SUCCESS = 0,
+    AUTH_FAILURE = 1,
+    HW_ERROR = 2
+}
+
+enum bit<2> crypto_mode_e {
+    TUNNEL = 0,
+    TRANSPORT = 1,
+    TRANSPORT_NAT_T = 2
+}
+
+// special offset value to indicate that ICV is after payload
+#define ICV_AFTER_PAYLOAD ((int<32>)-1)
+
+extern crypto_accelerator {
+    /// constructor
+    /// Some methods provided in this object may be specific to an algorithm used.
+    /// Compiler may be able to check and warn/error when incorrect methods are used
+    crypto_accelerator(crypto_algorithm_e algo);
+
+
+    // security association index for this security session
+    // Some implementations do not need it.. in that case this method should result in no-op
+    void set_sa_index<T>(in T sa_index);
+
+    // Set the initialization data based on protocol used. E.g. salt, random number/ counter for ipsec
+    void set_iv<T>(in T iv);
+    void set_key<T,S>(in T key, in S key_size);   // 128, 192, 256
+
+    // authentication data format is protocol specific
+    // Add this data as a header into the packet and provide its offset and length using the
+    // following APIs
+    // The format of the auth data is not specified/mandated by this object definition
+    void set_auth_data_offset<T>(in T offset);
+    void set_auth_data_len<T>(in T len);
+
+    // Alternatively: Following API can be used to consturct protocol specific auth_data and
+    // provide it to the engine.
+    void add_auth_data<H>(in H auth_data);
+
+    // Auth trailer aka ICV is added by the engine after doing encryption operation
+    // Specify icv location - when a wire protocol wants to add ICV in a specific location (e.g. AH)
+    // The following apis can be used to specify the location of ICV in the packet
+    // special offset (TBD) indicates ICV is after the payload
+    void set_icv_offset<T>(in T offset);
+    void set_icv_len<L>(in L len);
+
+    // setup payload to be encrypted/decrypted
+    void set_payload_offset<T>(in T offset);
+    void set_payload_len<T>(in T len);
+
+    // operation
+    // crypto accelerator runs at the end of the pipeline (after deparser), the following
+    // methods will enable the accelerator to run encrypt/decrypt operations
+    void enable_encrypt<T>(in T enable_auth);
+    void enable_decrypt<T>(in T enable_auth);
+
+    // encrypt_inline runs immediately and returns control flow to the current pipeline
+    // stage. The method is responsible for encrypting the payload appropriately, creating
+    // the ESP header, calculating the payload offset and lengths, and reparsing the packet
+    crypto_results_e encrypt_inline<T,S,I>(in crypto_mode_e mode,
+                        in T enable_auth,
+                        in bit<32> spi,
+                        in S seq,
+                        in I iv);
+
+    // decrypt_inline runs immediately and returns control flow to the current pipeline
+    // stage. The method is responsible for decrypting the payload appropriately, removing
+    // the ESP header, calculating the payload offset and lengths, and reparsing the packet
+    crypto_results_e decrypt_inline<T,S>(in crypto_mode_e mode,
+                        in T enable_auth,
+                        in S seq);
+
+    // disable crypto engine
+    void disable();
+
+    crypto_results_e get_results();       // get results of the previous operation
+}