arbiter.h

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//    sampalib.org ESL library and tools
//    Copyright (C) 2007  Thierry Grellier
//
//    This program is free software; you can redistribute it and/or modify
//    it under the terms of the GNU General Public License version 2 as
//    published by the Free Software Foundation.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    You should have received a copy of the GNU General Public License along
//    with this program; if not, write to the Free Software Foundation, Inc.,
//    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
//    contact: www.sampalib.org

#ifndef SAMPA_ARBITER_H
#define SAMPA_ARBITER_H

#include "sampa/component/protocol.h"
#include "sampa/core/gated.h"
#include "sampa/core/sarray.h"
#include "sampa/core/fifo.h"

namespace Sampa {

  class Arbiter : public Module, public InitiatorResponseInterface {
    SAMPA_MODULE(Arbiter);
  public: 
    class Requester : public Target, public TargetRequestInterface {
      SAMPA_PERSISTENT(Requester);
    public:
      Requester(const Name& name);
      const Request& get_request() const;
      bool recieve_request(const Request& request);
      bool is_requesting() const;
      void bind_initiator(Initiator*);
    protected:
      Arbiter*       m_arbiter;
      Gated<Request> m_request;
      Gated<bool>    m_requesting;
    };
    
    Arbiter(const Name& name);

    void bind_initiator(Initiator* initiator);
    Target* get_target(const std::string&);
    void bind_target(Target* target);
    Initiator* get_initiator() { return &p_initiator; }
    void bind_clock(Clock*);
    
    enum SchedulingPolicy {
      PRIORITY,
      ROUND_ROBIN
    };
    
  private:
    friend class Requester;
    
    void complete_restart();
    bool recieve_response(const Response& response);   
    const char* get_initiator_name() const;
    void recieve_request();
    void arbitrate_priority();
    void arbitrate_roundrobin();
    void acknowledge_request_forwarded();
    void forward_elected();
    void forward_response();
    int  check(int);
    void acknowledge_response_forwarded();

    SizeParameter                         m_num_requester;    
    Array<Requester>                      m_requesters;
    Initiator                             p_initiator;
    Gated<short>                          m_elected;
    short                                 m_num_requesting;
    short                                 m_arbitrated;
    short                                 m_stalled;
    short                                 m_bound;
    Fifo                                  m_outstanding_fifo;
    Array<int>                            m_outstandings;
    ClockedEventSingle                    e_elected;
    Gated<Response>                       m_response;
    Gated<bool>                           m_response_pending;
    Gated<bool>                           m_accept_response;
    EventSingle                           e_arbitration;
    EnumeratedParameter<SchedulingPolicy> m_policy;
  };

}

#endif

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