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/**
* Copyright (c) 2018 Inria
* 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: Daniel Carvalho
*/
#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_BASE_HH__
#define __MEM_CACHE_REPLACEMENT_POLICIES_BASE_HH__
#include <memory>
#include "params/BaseReplacementPolicy.hh"
#include "sim/sim_object.hh"
/**
* The replacement data needed by the replacement policy.
* Each replacement policy should have its own replacement data.
*/
struct ReplacementData {};
/**
* A replaceable entry is used by any table-like structure that needs to
* implement replacement functionality. It provides the replacement data
* pointer instantiated and needed by the replacement policy used.
* @sa Replacement Policies
*/
class ReplaceableEntry
{
private:
/**
* Set to which this entry belongs.
*/
uint32_t _set;
/**
* Way (relative position within the set) to which this entry belongs.
*/
uint32_t _way;
public:
/**
* Replacement data associated to this entry.
* It is instantiated by the replacement policy.
*/
std::shared_ptr<ReplacementData> replacementData;
/**
* Set both the set and way. Should be called only once.
*
* @param set The set of this entry.
* @param way The way of this entry.
*/
void setPosition(const uint32_t set, const uint32_t way) {
_set = set;
_way = way;
}
/**
* Get set number.
*
* @return The set to which this entry belongs.
*/
uint32_t getSet() const { return _set; }
/**
* Get way number.
*
* @return The way to which this entry belongs.
*/
uint32_t getWay() const { return _way; }
};
/**
* Replacement candidates as chosen by the indexing policy.
*/
typedef std::vector<ReplaceableEntry*> ReplacementCandidates;
/**
* A common base class of cache replacement policy objects.
*/
class BaseReplacementPolicy : public SimObject
{
public:
/**
* Convenience typedef.
*/
typedef BaseReplacementPolicyParams Params;
/**
* Construct and initiliaze this replacement policy.
*/
BaseReplacementPolicy(const Params *p) : SimObject(p) {}
/**
* Destructor.
*/
virtual ~BaseReplacementPolicy() {}
/**
* Invalidate replacement data to set it as the next probable victim.
*
* @param replacement_data Replacement data to be invalidated.
*/
virtual void invalidate(const std::shared_ptr<ReplacementData>&
replacement_data) const = 0;
/**
* Update replacement data.
*
* @param replacement_data Replacement data to be touched.
*/
virtual void touch(const std::shared_ptr<ReplacementData>&
replacement_data) const = 0;
/**
* Reset replacement data. Used when it's holder is inserted/validated.
*
* @param replacement_data Replacement data to be reset.
*/
virtual void reset(const std::shared_ptr<ReplacementData>&
replacement_data) const = 0;
/**
* Find replacement victim among candidates.
*
* @param candidates Replacement candidates, selected by indexing policy.
* @return Replacement entry to be replaced.
*/
virtual ReplaceableEntry* getVictim(
const ReplacementCandidates& candidates) const = 0;
/**
* Instantiate a replacement data entry.
*
* @return A shared pointer to the new replacement data.
*/
virtual std::shared_ptr<ReplacementData> instantiateEntry() = 0;
};
#endif // __MEM_CACHE_REPLACEMENT_POLICIES_BASE_HH__
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