/*
 * Copyright (c) 2015 ARM Limited
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Gabor Dozsa
 */

/* @file
 * Header packet class for dist-gem5 runs.
 *
 * For a high level description about dist-gem5 see comments in
 * header file dist_iface.hh.
 *
 * The DistHeaderPkt class defines the format of message headers
 * sent among gem5 processes during a dist gem5 simulation. A header packet
 * can either carry the description of data packet (i.e. a simulated Ethernet
 * packet) or a synchronisation related control command. In case of
 * data packet description, the corresponding data packet always follows
 * the header packet back-to-back.
 */
#ifndef __DEV_DIST_PACKET_HH__
#define __DEV_DIST_PACKET_HH__

#include <cstring>

#include "base/types.hh"

class DistHeaderPkt
{
  private:
    DistHeaderPkt() {}
    ~DistHeaderPkt() {}

  public:
    enum class ReqType { immediate, collective, pending, none };
    /**
     *  The msg type defines what information a dist header packet carries.
     */
    enum class MsgType
    {
        dataDescriptor,
        cmdSyncReq,
        cmdSyncAck,
        unknown
    };

    struct Header
    {
        /**
         * The msg type field is valid for all header packets.
         *
         * @note senderRank is used with data packets while collFlags are used
         * by sync ack messages to trigger collective ckpt or exit events.
         */
        MsgType msgType;
        Tick sendTick;
        /**
         * Length used for modeling timing in the simulator.
         * (from EthPacketData::simLength).
         */
        unsigned simLength;
        union {
            Tick sendDelay;
            Tick syncRepeat;
        };
        union {
            /**
             * Actual length of the simulated Ethernet packet.
             * (from EthPacketData::length).
             */
            unsigned dataPacketLength;
            struct {
                ReqType needCkpt;
                ReqType needStopSync;
                ReqType needExit;
            };
        };
    };
};

#endif