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// $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.
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.
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.
*/
// ----------------------------------------------------------------------
//
// 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
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