src/mem/cache/compressors/multi.hh

   1 /*
   2  * Copyright (c) 2019-2020 Inria
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  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
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  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /** @file
  30  * Definition of the a multi compressor that choses the best compression
  31  * among multiple compressors.
  32  */
  33
  34 #ifndef __MEM_CACHE_COMPRESSORS_MULTI_HH__
  35 #define __MEM_CACHE_COMPRESSORS_MULTI_HH__
  36
  37 #include <cstdint>
  38 #include <vector>
  39
  40 #include "base/statistics.hh"
  41 #include "base/types.hh"
  42 #include "mem/cache/compressors/base.hh"
  43
  44 struct MultiCompressorParams;
  45
  46 namespace Compressor {
  47
  48 class Multi : public Base
  49 {
  50   protected:
  51     /**
  52      * Compression data for the multi compressor. It contains the compression
  53      * data of the best compressor, along with its index in the list of
  54      * sub-compressors.
  55      */
  56     class MultiCompData;
  57
  58     /** List of sub-compressors. */
  59     std::vector<Base*> compressors;
  60
  61     struct MultiStats : public Stats::Group
  62     {
  63         const Multi& compressor;
  64
  65         MultiStats(BaseStats &base_group, Multi& _compressor);
  66
  67         void regStats() override;
  68
  69         /**
  70          * Number of times each compressor provided the nth best compression.
  71          */
  72         Stats::Vector2d ranks;
  73     } multiStats;
  74
  75   public:
  76     typedef MultiCompressorParams Params;
  77     Multi(const Params *p);
  78     ~Multi();
  79
  80     std::unique_ptr<Base::CompressionData> compress(
  81         const uint64_t* data, Cycles& comp_lat, Cycles& decomp_lat) override;
  82
  83     void decompress(const CompressionData* comp_data, uint64_t* data) override;
  84 };
  85
  86 class Multi::MultiCompData : public CompressionData
  87 {
  88   private:
  89     /** Index of the compressor that provided these compression results. */
  90     const uint8_t index;
  91
  92   public:
  93     /** Compression data of the best compressor. */
  94     std::unique_ptr<Base::CompressionData> compData;
  95
  96     /**
  97      * Default constructor.
  98      *
  99      * @param index Index of the compressor that provided this compression.
 100      * @param comp_data Compression data of the best compressor.
 101      */
 102     MultiCompData(unsigned index,
 103         std::unique_ptr<Base::CompressionData> comp_data);
 104
 105     /** Default destructor. */
 106     ~MultiCompData() = default;
 107
 108     /** Get the index of the best compressor. */
 109     uint8_t getIndex() const;
 110 };
 111
 112 } // namespace Compressor
 113
 114 #endif //__MEM_CACHE_COMPRESSORS_MULTI_HH__