DRAMSys/dram/src/simulation/ReorderBuffer.h

/*
 * Copyright (c) 2015, University of Kaiserslautern
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. Neither the name of the copyright holder 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 HOLDER
 * 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:
 *    Janik Schlemminger
 *    Robert Gernhardt
 *    Matthias Jung
 */

#ifndef REORDERBUFFER_H
#define REORDERBUFFER_H

#include <deque>
#include <systemc.h> 
#include <set>

using namespace std;
using namespace tlm;

template<unsigned int BUSWIDTH = 128>
struct ReorderBuffer: public sc_module
{
public:
    tlm_utils::simple_initiator_socket<ReorderBuffer,BUSWIDTH, tlm::tlm_base_protocol_types> iSocket;
    tlm_utils::simple_target_socket<ReorderBuffer, BUSWIDTH, tlm::tlm_base_protocol_types> tSocket;

    SC_CTOR(ReorderBuffer) :
            payloadEventQueue(this, &ReorderBuffer::peqCallback), responseIsPendingInInitator(false)
    {
        iSocket.register_nb_transport_bw(this, &ReorderBuffer::nb_transport_bw);
        tSocket.register_nb_transport_fw(this, &ReorderBuffer::nb_transport_fw);
    }

private:
    tlm_utils::peq_with_cb_and_phase<ReorderBuffer> payloadEventQueue;
    deque<tlm_generic_payload*> pendingRequestsInOrder;
    set<tlm_generic_payload*>   receivedResponses;

    bool responseIsPendingInInitator;


    // Initiated by dram side
    tlm_sync_enum nb_transport_bw(tlm_generic_payload& payload, tlm_phase& phase, sc_time& bwDelay)
    {
        payloadEventQueue.notify(payload, phase, bwDelay);
        return TLM_ACCEPTED;
    }

    // Initiated by initator side (players)
    tlm_sync_enum nb_transport_fw(tlm_generic_payload& payload, tlm_phase& phase,
            sc_time& fwDelay)
    {
        if (phase == BEGIN_REQ)
        {
             payload.acquire();
        }
        else if (phase == END_RESP)
        {
            payload.release();
        }

        payloadEventQueue.notify(payload, phase, fwDelay);
        return TLM_ACCEPTED;
    }

    void peqCallback(tlm_generic_payload& payload, const tlm_phase& phase)
    {
        //Phases initiated by initiator side
        if (phase == BEGIN_REQ)
        {
             pendingRequestsInOrder.push_back(&payload);
             sendToTarget(payload, phase, SC_ZERO_TIME );
        }

        else if (phase == END_RESP)
        {
            responseIsPendingInInitator = false;
            pendingRequestsInOrder.pop_front();
            receivedResponses.erase(&payload);
            sendNextResponse();
        }

        //Phases initiated by dram side
        else if (phase == END_REQ)
        {
            sendToInitiator(payload, phase, SC_ZERO_TIME);
        }
        else if (phase == BEGIN_RESP)
        {
            sendToTarget(payload, END_RESP, SC_ZERO_TIME);
            receivedResponses.emplace(&payload);
            sendNextResponse();
        }


        else
        {
            SC_REPORT_FATAL(0, "Payload event queue in arbiter was triggered with unknown phase");
        }
    }

    void sendToTarget(tlm_generic_payload& payload, const tlm_phase& phase, const sc_time& delay)
    {
        tlm_phase TPhase = phase;
        sc_time TDelay = delay;
        iSocket->nb_transport_fw(payload, TPhase, TDelay);
    }

    void sendToInitiator(tlm_generic_payload& payload, const tlm_phase& phase, const sc_time& delay)
    {


        sc_assert(phase == END_REQ ||
                 (phase == BEGIN_RESP && pendingRequestsInOrder.front() == &payload && receivedResponses.count(&payload)));

        tlm_phase TPhase = phase;
        sc_time TDelay = delay;
        tSocket->nb_transport_bw(payload, TPhase, TDelay);
    }

    void sendNextResponse()
    {
        //only send the next response when there response for the oldest pending request (requestsInOrder.front())
        //has been received
        if(!responseIsPendingInInitator && receivedResponses.count(pendingRequestsInOrder.front()))
        {
            tlm_generic_payload* payloadToSend = pendingRequestsInOrder.front();
            responseIsPendingInInitator = true;
            sendToInitiator(*payloadToSend,BEGIN_RESP,SC_ZERO_TIME);
        }
//        else if(!responseIsPendingInInitator && receivedResponses.size()>0 && !receivedResponses.count(pendingRequestsInOrder.front())>0)
//        {
//            cout << "cant send this response, because we are still waiting for response of oldest pending request. Elemts in buffer: " <<  receivedResponses.size() << endl;
//        }
    }

};




#endif // REORDERBUFFER_H