xref: /gem5/src/mem/cache/prefetch/stride.hh

/*
 * Copyright (c) 2005 The Regents of The University of Michigan
 * 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;
 * neither the name of the copyright holders 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
 * 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.
 *
 * Authors: Ron Dreslinski
 */

/**
 * @file
 * Describes a strided prefetcher.
 */

#ifndef __MEM_CACHE_PREFETCH_STRIDE_PREFETCHER_HH__
#define __MEM_CACHE_PREFETCH_STRIDE_PREFETCHER_HH__

#include <climits>

#include "mem/cache/prefetch/base.hh"

class StridePrefetcher : public BasePrefetcher
{
  protected:

    static const int Max_Contexts = 64;

    // These constants need to be changed with the type of the
    // 'confidence' field below.
    static const int Max_Conf = INT_MAX;
    static const int Min_Conf = INT_MIN;

    class StrideEntry
    {
      public:
        Addr instAddr;
        Addr missAddr;
        int stride;
        int confidence;
    };

    Addr *lastMissAddr[Max_Contexts];

    std::list<StrideEntry*> table[Max_Contexts];
    Tick latency;
    int degree;
    bool useContextId;

  public:

    StridePrefetcher(const BaseCacheParams *p)
        : BasePrefetcher(p), latency(p->prefetch_latency),
          degree(p->prefetch_degree), useContextId(p->prefetch_use_cpu_id)
    {
    }

    ~StridePrefetcher() {}

    void calculatePrefetch(PacketPtr &pkt, std::list<Addr> &addresses,
                           std::list<Tick> &delays);
};

#endif // __MEM_CACHE_PREFETCH_STRIDE_PREFETCHER_HH__