// $Id: roundrobin_arb.hpp 5188 2012-08-30 00:31:31Z dub $

/*
 Copyright (c) 2007-2012, Trustees of The Leland Stanford Junior University
 All rights reserved.

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*/

// ----------------------------------------------------------------------
//
//  RoundRobin: Round Robin Arbiter
//
// ----------------------------------------------------------------------

#ifndef _ROUNDROBIN_HPP_
#define _ROUNDROBIN_HPP_

#include "arbiter.hpp"

class RoundRobinArbiter : public Arbiter {

  // Priority pointer
  int  _pointer ;

public:

  // Constructors
  RoundRobinArbiter( Module *parent, const string &name, int size ) ;

  // Print priority matrix to standard output
  virtual void PrintState() const ;
  
  // Update priority matrix based on last aribtration result
  virtual void UpdateState() ; 

  // Arbitrate amongst requests. Returns winning input and 
  // updates pointers to metadata when valid pointers are passed
  virtual int Arbitrate( int* id = 0, int* pri = 0) ;

  virtual void AddRequest( int input, int id, int pri ) ;

  virtual void Clear();

  static inline bool Supersedes(int input1, int pri1, int input2, int pri2, int offset, int size)
  {
    // in a round-robin scheme with the given number of positions and current 
    // offset, should a request at input1 with priority pri1 supersede a 
    // request at input2 with priority pri2?
    return ((pri1 > pri2) || 
	    ((pri1 == pri2) && 
	     (((input1 - offset + size) % size) < ((input2 - offset + size) % size))));
  }
  
} ;

#endif