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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.
*
* Authors: Daniel Carvalho
*/
/** @file
* Definition of a zero compressor, which compressed data if it is entirely
* composed of zero bits.
*/
#ifndef __MEM_CACHE_COMPRESSORS_ZERO_HH__
#define __MEM_CACHE_COMPRESSORS_ZERO_HH__
#include <array>
#include <cstdint>
#include <map>
#include <memory>
#include "mem/cache/compressors/dictionary_compressor.hh"
struct ZeroCompressorParams;
class ZeroCompressor : public DictionaryCompressor<uint64_t>
{
protected:
using DictionaryEntry = DictionaryCompressor<uint64_t>::DictionaryEntry;
// Forward declaration of all possible patterns
class PatternX;
class PatternZ;
/**
* The patterns proposed in the paper. Each letter represents a byte:
* Z is a null byte, M is a dictionary match, X is a new value.
* These are used as indexes to reference the pattern data. If a new
* pattern is added, it must be done before NUM_PATTERNS.
*/
typedef enum {
X, Z, NUM_PATTERNS
} PatternNumber;
/**
* Convenience factory declaration. The templates must be organized by
* size, with the smallest first, and "no-match" last.
*/
using PatternFactory = Factory<PatternZ, PatternX>;
uint64_t getNumPatterns() const override { return NUM_PATTERNS; }
std::string
getName(int number) const override
{
static std::map<int, std::string> pattern_names = {
{X, "X"}, {Z, "Z"}
};
return pattern_names[number];
};
std::unique_ptr<Pattern>
getPattern(const DictionaryEntry& bytes, const DictionaryEntry& dict_bytes,
const int match_location) const override
{
return PatternFactory::getPattern(bytes, dict_bytes, match_location);
}
void addToDictionary(DictionaryEntry data) override;
std::unique_ptr<BaseCacheCompressor::CompressionData> compress(
const uint64_t* data, Cycles& comp_lat, Cycles& decomp_lat) override;
public:
typedef ZeroCompressorParams Params;
ZeroCompressor(const Params *p);
~ZeroCompressor() = default;
};
class ZeroCompressor::PatternX
: public DictionaryCompressor::UncompressedPattern
{
public:
PatternX(const DictionaryEntry bytes, const int match_location)
: DictionaryCompressor::UncompressedPattern(X, 0, 1, match_location,
bytes)
{
}
};
class ZeroCompressor::PatternZ
: public DictionaryCompressor::MaskedValuePattern<0, 0xFFFFFFFFFFFFFFFF>
{
public:
PatternZ(const DictionaryEntry bytes, const int match_location)
: DictionaryCompressor::MaskedValuePattern<0, 0xFFFFFFFFFFFFFFFF>(
Z, 1, 1, match_location, bytes)
{
}
};
#endif //__MEM_CACHE_COMPRESSORS_ZERO_HH__
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