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/*
* Copyright (c) 2019 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.
*/
/** @file
* Definition of a perfect compressor, that always manages to compress to
* its maximum compression ratio.
*/
#ifndef __MEM_CACHE_COMPRESSORS_PERFECT_COMPRESSOR_HH__
#define __MEM_CACHE_COMPRESSORS_PERFECT_COMPRESSOR_HH__
#include <cstdint>
#include <memory>
#include <vector>
#include "base/types.hh"
#include "mem/cache/compressors/base.hh"
struct PerfectCompressorParams;
class PerfectCompressor : public BaseCacheCompressor
{
protected:
class CompData;
/** Size to which this compressor always compresses. */
const int compressedSize;
/** Number of cycles needed to perform compression. */
const Cycles compressionLatency;
/** Number of cycles needed to perform decompression. */
const Cycles decompressionLatency;
std::unique_ptr<CompressionData> compress(const uint64_t* cache_line,
Cycles& comp_lat, Cycles& decomp_lat) override;
void decompress(const CompressionData* comp_data, uint64_t* data) override;
public:
typedef PerfectCompressorParams Params;
PerfectCompressor(const Params *p);
~PerfectCompressor() {};
};
class PerfectCompressor::CompData : public CompressionData
{
public:
/** The original data is simply copied over to this vector. */
std::vector<uint64_t> entries;
/**
* Default constructor that creates a copy of the original data.
*
* @param data The data to be compressed.
* @param num_entries The number of qwords in the data.
*/
CompData(const uint64_t* data, std::size_t num_entries);
~CompData() = default;
};
#endif //__MEM_CACHE_COMPRESSORS_PERFECT_COMPRESSOR_HH__