src/mem/cache/replacement_policies/replaceable_entry.hh

   1 /**
   2  * Copyright (c) 2018 Inria
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  *
  28  * Authors: Daniel Carvalho
  29  */
  30
  31 #ifndef __MEM_CACHE_REPLACEMENT_POLICIES_REPLACEABLE_ENTRY_HH__
  32 #define __MEM_CACHE_REPLACEMENT_POLICIES_REPLACEABLE_ENTRY_HH__
  33
  34 #include <cstdint>
  35 #include <memory>
  36
  37 /**
  38  * The replacement data needed by replacement policies. Each replacement policy
  39  * should have its own implementation of replacement data.
  40  */
  41 struct ReplacementData {};
  42
  43 /**
  44  * A replaceable entry is a basic entry in a 2d table-like structure that needs
  45  * to have replacement functionality. This entry is located in a specific row
  46  * and column of the table (set and way in cache nomenclature), which are
  47  * stored within the entry itself.
  48  *
  49  * It contains the replacement data pointer, which must be instantiated by the
  50  * replacement policy before being used.
  51  * @sa Replacement Policies
  52  */
  53 class ReplaceableEntry
  54 {
  55   private:
  56     /**
  57      * Set to which this entry belongs.
  58      */
  59     uint32_t _set;
  60
  61     /**
  62      * Way (relative position within the set) to which this entry belongs.
  63      */
  64     uint32_t _way;
  65
  66    public:
  67      /**
  68       * Replacement data associated to this entry.
  69       * It must be instantiated by the replacement policy before being used.
  70       */
  71      std::shared_ptr<ReplacementData> replacementData;
  72
  73     /**
  74      * Set both the set and way. Should be called only once.
  75      *
  76      * @param set The set of this entry.
  77      * @param way The way of this entry.
  78      */
  79     void setPosition(const uint32_t set, const uint32_t way) {
  80         _set = set;
  81         _way = way;
  82     }
  83
  84     /**
  85      * Get set number.
  86      *
  87      * @return The set to which this entry belongs.
  88      */
  89     uint32_t getSet() const { return _set; }
  90
  91     /**
  92      * Get way number.
  93      *
  94      * @return The way to which this entry belongs.
  95      */
  96     uint32_t getWay() const { return _way; }
  97 };
  98
  99 #endif // __MEM_CACHE_REPLACEMENT_POLICIES_REPLACEABLE_ENTRY_HH_