gem5/src/mem/protocol/MI_example-dir.sm

machine(Directory, "Directory protocol") {

  MessageBuffer forwardFromDir, network="To", virtual_network="2", ordered="true";
  MessageBuffer responseFromDir, network="To", virtual_network="1", ordered="false";

  MessageBuffer requestToDir, network="From", virtual_network="0", ordered="true";
  MessageBuffer unblockToDir, network="From", virtual_network="3", ordered="true";

  // STATES
  enumeration(State, desc="Directory states", default="Directory_State_I") {
    // Base states
    I, desc="Invalid";
    M, desc="Modified";

    MI, desc="Blocked on a writeback";
  }

  // Events
  enumeration(Event, desc="Directory events") {
    GETX, desc="A GETX arrives";
    GETS, desc="A GETS arrives";
    PUTX, desc="A PUTX arrives";
    PUTX_NotOwner, desc="A PUTX arrives";
    PUTO, desc="A PUTO arrives";
    Unblock, desc="An unblock message arrives";
  }

  // TYPES

  // DirectoryEntry
  structure(Entry, desc="...") {
    State DirectoryState,          desc="Directory state";
    DataBlock DataBlk,             desc="data for the block";
    NetDest Sharers,                   desc="Sharers for this block";
    NetDest Owner,                     desc="Owner of this block";
  }

  external_type(DirectoryMemory) {
    Entry lookup(Address);
    bool isPresent(Address);
  }


  // ** OBJECTS **

  DirectoryMemory directory, constructor_hack="i";

  State getState(Address addr) {
    return directory[addr].DirectoryState;
  }

  void setState(Address addr, State state) {
    if (directory.isPresent(addr)) {

      if (state == State:I)  {
        assert(directory[addr].Owner.count() == 0);
        assert(directory[addr].Sharers.count() == 0);
      }

      if (state == State:M) {
        assert(directory[addr].Owner.count() == 1);
        assert(directory[addr].Sharers.count() == 0);
      }

      directory[addr].DirectoryState := state;
    }
  }

  // ** OUT_PORTS **
  out_port(forwardNetwork_out, RequestMsg, forwardFromDir);
  out_port(responseNetwork_out, ResponseMsg, responseFromDir);
  out_port(requestQueue_out, ResponseMsg, requestToDir); // For recycling requests

  // ** IN_PORTS **


  in_port(requestQueue_in, RequestMsg, requestToDir) {
    if (requestQueue_in.isReady()) {
      peek(requestQueue_in, RequestMsg) {
        if (in_msg.Type == CoherenceRequestType:GETS) {
          trigger(Event:GETS, in_msg.Address);
        } else if (in_msg.Type == CoherenceRequestType:GETX) {
          trigger(Event:GETX, in_msg.Address);
        } else if (in_msg.Type == CoherenceRequestType:PUTX) {
          if (directory[in_msg.Address].Owner.isElement(in_msg.Requestor)) {
            trigger(Event:PUTX, in_msg.Address);
          } else {
            trigger(Event:PUTX_NotOwner, in_msg.Address);
          }
        } else if (in_msg.Type == CoherenceRequestType:PUTO) {
          trigger(Event:PUTO, in_msg.Address);
        } else {
          error("Invalid message");
        }
      }
    }
  }

  in_port(unblockNetwork_in, ResponseMsg, unblockToDir) {
    if (unblockNetwork_in.isReady()) {
      peek(unblockNetwork_in, ResponseMsg) {
        if (in_msg.Type == CoherenceResponseType:UNBLOCK) {
          trigger(Event:Unblock, in_msg.Address);
        } else {
          error("Invalid message");
        }
      }
    }
  }



  // Actions

  action(a_sendWriteBackAck, "a", desc="Send writeback ack to requestor") {
    peek(requestQueue_in, RequestMsg) {
      enqueue(forwardNetwork_out, RequestMsg, latency="DIRECTORY_LATENCY") {
        out_msg.Address := address;
        out_msg.Type := CoherenceRequestType:WB_ACK;
        out_msg.Requestor := in_msg.Requestor;
        out_msg.Destination.add(in_msg.Requestor);
        out_msg.MessageSize := MessageSizeType:Writeback_Control;
      }
    }
  }

  action(b_sendWriteBackNack, "b", desc="Send writeback nack to requestor") {
    peek(requestQueue_in, RequestMsg) {
      enqueue(forwardNetwork_out, RequestMsg, latency="DIRECTORY_LATENCY") {
        out_msg.Address := address;
        out_msg.Type := CoherenceRequestType:WB_NACK;
        out_msg.Requestor := in_msg.Requestor;
        out_msg.Destination.add(in_msg.Requestor);
        out_msg.MessageSize := MessageSizeType:Writeback_Control;
      }
    }
  }

  action(c_clearOwner, "c", desc="Clear the owner field") {
    directory[address].Owner.clear();
  }

  action(d_sendData, "d", desc="Send data to requestor") {
    peek(requestQueue_in, RequestMsg) {
      enqueue(responseNetwork_out, ResponseMsg, latency="MEMORY_LATENCY") {
        out_msg.Address := address;

        if (in_msg.Type == CoherenceRequestType:GETS && directory[address].Sharers.count() == 0) {
          // out_msg.Type := CoherenceResponseType:DATA_EXCLUSIVE_CLEAN;
          out_msg.Type := CoherenceResponseType:DATA;
        } else {
          out_msg.Type := CoherenceResponseType:DATA;
        }

        out_msg.Sender := machineID;
        out_msg.Destination.add(in_msg.Requestor);
        out_msg.DataBlk := directory[in_msg.Address].DataBlk;
        out_msg.Dirty := false; // By definition, the block is now clean
        out_msg.Acks := directory[address].Sharers.count();
        if (directory[address].Sharers.isElement(in_msg.Requestor)) {
          out_msg.Acks := out_msg.Acks - 1;
        }
        out_msg.MessageSize := MessageSizeType:Response_Data;
      }
    }
  }

  action(e_ownerIsRequestor, "e", desc="The owner is now the requestor") {
    peek(requestQueue_in, RequestMsg) {
      directory[address].Owner.clear();
      directory[address].Owner.add(in_msg.Requestor);
    }
  }

  action(f_forwardRequest, "f", desc="Forward request to owner") {
    peek(requestQueue_in, RequestMsg) {
      APPEND_TRANSITION_COMMENT("Own: ");
      APPEND_TRANSITION_COMMENT(directory[in_msg.Address].Owner);
      APPEND_TRANSITION_COMMENT("Req: ");
      APPEND_TRANSITION_COMMENT(in_msg.Requestor);
      enqueue(forwardNetwork_out, RequestMsg, latency="DIRECTORY_LATENCY") {
        out_msg.Address := address;
        out_msg.Type := in_msg.Type;
        out_msg.Requestor := in_msg.Requestor;
        out_msg.Destination := directory[in_msg.Address].Owner;
        out_msg.Acks := directory[address].Sharers.count();
        if (directory[address].Sharers.isElement(in_msg.Requestor)) {
          out_msg.Acks := out_msg.Acks - 1;
        }
        out_msg.MessageSize := MessageSizeType:Forwarded_Control;
      }
    }
  }


  action(i_popIncomingRequestQueue, "i", desc="Pop incoming request queue") {
    requestQueue_in.dequeue();
  }

  action(j_popIncomingUnblockQueue, "j", desc="Pop incoming unblock queue") {
    unblockNetwork_in.dequeue();
  }

  action(l_writeDataToMemory, "l", desc="Write PUTX/PUTO data to memory") {
    // peek(unblockNetwork_in, ResponseMsg) {
    peek(requestQueue_in, RequestMsg) {
      // assert(in_msg.Dirty);
      // assert(in_msg.MessageSize == MessageSizeType:Writeback_Data);
      directory[in_msg.Address].DataBlk := in_msg.DataBlk;
      DEBUG_EXPR(in_msg.Address);
      DEBUG_EXPR(in_msg.DataBlk);
    }
  }



  // TRANSITIONS

  transition(I, GETX, M) {
    d_sendData;
    e_ownerIsRequestor;
    i_popIncomingRequestQueue;
  }



  transition(M, GETX, M) {
    f_forwardRequest;
    e_ownerIsRequestor;
    i_popIncomingRequestQueue;
  }

  // transition(M, PUTX, MI) {
  transition(M, PUTX, I) {
    c_clearOwner;
    l_writeDataToMemory;
    a_sendWriteBackAck;
    i_popIncomingRequestQueue;
  }

  transition(M, PUTX_NotOwner, M) {
    b_sendWriteBackNack;
    i_popIncomingRequestQueue;
  }

  transition(I, PUTX_NotOwner, I) {
    b_sendWriteBackNack;
    i_popIncomingRequestQueue;
  }


  transition(MI, Unblock, M) {
    j_popIncomingUnblockQueue;
  }

}