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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 base delta immediate compressor. @see BDI
*/
#ifndef __MEM_CACHE_COMPRESSORS_BASE_DELTA_HH__
#define __MEM_CACHE_COMPRESSORS_BASE_DELTA_HH__
#include <array>
#include <cstdint>
#include <map>
#include <memory>
#include "base/bitfield.hh"
#include "mem/cache/compressors/dictionary_compressor.hh"
struct BaseDictionaryCompressorParams;
struct Base64Delta8Params;
struct Base64Delta16Params;
struct Base64Delta32Params;
struct Base32Delta8Params;
struct Base32Delta16Params;
struct Base16Delta8Params;
/**
* Base class for all base-delta-immediate compressors. Although not proposed
* like this in the original paper, the sub-compressors of BDI are dictionary
* based with 2 possible patterns: no match, where a dictionary entry must be
* allocated, and masked delta match with a dictionary entry, where the delta
* must be stored instead. The maximum number of dictionary entries is 2, and
* one of them is reserved for a zero base if using immediate compression.
*
* @tparam BaseType Type of a base (dictionary) entry.
*/
template <class BaseType, std::size_t DeltaSizeBits>
class BaseDelta : public DictionaryCompressor<BaseType>
{
protected:
static constexpr int DEFAULT_MAX_NUM_BASES = 2;
using DictionaryEntry =
typename DictionaryCompressor<BaseType>::DictionaryEntry;
// Forward declaration of all possible patterns
class PatternX;
class PatternM;
/**
* 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, M, NUM_PATTERNS
} PatternNumber;
uint64_t getNumPatterns() const override { return NUM_PATTERNS; }
/**
* Convenience factory declaration. The templates must be organized by
* size, with the smallest first, and "no-match" last.
*/
using PatternFactory = typename DictionaryCompressor<BaseType>::template
Factory<PatternM, PatternX>;
std::unique_ptr<typename DictionaryCompressor<BaseType>::Pattern>
getPattern(const DictionaryEntry& bytes,
const DictionaryEntry& dict_bytes,
const int match_location) const override
{
return PatternFactory::getPattern(bytes, dict_bytes, match_location);
}
std::string
getName(int number) const override
{
static std::map<int, std::string> pattern_names = {
{X, "X"}, {M, "M"}
};
return pattern_names[number];
}
void resetDictionary() override;
void addToDictionary(DictionaryEntry data) override;
std::unique_ptr<BaseCacheCompressor::CompressionData>
compress(const uint64_t* data, Cycles& comp_lat,
Cycles& decomp_lat) override;
public:
typedef BaseDictionaryCompressorParams Params;
BaseDelta(const Params *p);
~BaseDelta() = default;
};
template <class BaseType, std::size_t DeltaSizeBits>
class BaseDelta<BaseType, DeltaSizeBits>::PatternX
: public DictionaryCompressor<BaseType>::UncompressedPattern
{
public:
// A delta entry containing the value 0 is added even if it is an entirely
// new base
PatternX(const DictionaryEntry bytes, const int match_location)
: DictionaryCompressor<BaseType>::UncompressedPattern(X, 0,
std::ceil(std::log2(DEFAULT_MAX_NUM_BASES)) + DeltaSizeBits,
match_location, bytes)
{
}
};
template <class BaseType, std::size_t DeltaSizeBits>
class BaseDelta<BaseType, DeltaSizeBits>::PatternM : public
DictionaryCompressor<BaseType>::template DeltaPattern<DeltaSizeBits>
{
public:
// The number of bits reserved for the bitmask entry is proportional to
// the maximum number of bases
PatternM(const DictionaryEntry bytes, const int match_location)
: DictionaryCompressor<BaseType>::template DeltaPattern<DeltaSizeBits>(
M, 1, std::ceil(std::log2(DEFAULT_MAX_NUM_BASES)), match_location,
bytes)
{
}
};
class Base64Delta8 : public BaseDelta<uint64_t, 8>
{
public:
typedef Base64Delta8Params Params;
Base64Delta8(const Params *p);
~Base64Delta8() = default;
};
class Base64Delta16 : public BaseDelta<uint64_t, 16>
{
public:
typedef Base64Delta16Params Params;
Base64Delta16(const Params *p);
~Base64Delta16() = default;
};
class Base64Delta32 : public BaseDelta<uint64_t, 32>
{
public:
typedef Base64Delta32Params Params;
Base64Delta32(const Params *p);
~Base64Delta32() = default;
};
class Base32Delta8 : public BaseDelta<uint32_t, 8>
{
public:
typedef Base32Delta8Params Params;
Base32Delta8(const Params *p);
~Base32Delta8() = default;
};
class Base32Delta16 : public BaseDelta<uint32_t, 16>
{
public:
typedef Base32Delta16Params Params;
Base32Delta16(const Params *p);
~Base32Delta16() = default;
};
class Base16Delta8 : public BaseDelta<uint16_t, 8>
{
public:
typedef Base16Delta8Params Params;
Base16Delta8(const Params *p);
~Base16Delta8() = default;
};
#endif //__MEM_CACHE_COMPRESSORS_BASE_DELTA_HH__
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