mem-cache: Create CPack compressor
Implementation of C-Pack, as described in "C-Pack: A High-
Performance Microprocessor Cache Compression Algorithm".
C-Pack uses pattern matching schemes to detect and compress
frequently appearing data patterns. As in the original paper,
it divides the input in 32-bit words, and uses 6 patterns to
match with its dictionary.
For the patterns, each letter represents a byte: Z is a null
byte, M is a dictionary match, X is a new value. The patterns
are ZZZZ, XXXX, MMMM, MMXX, ZZZX, MMMX.
Change-Id: I2efc9db2c862620dcc1155300e39be558f9017e0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/11105
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/src/mem/cache/compressors/Compressors.py b/src/mem/cache/compressors/Compressors.py
index 1d9de19..b266ccc 100644
--- a/src/mem/cache/compressors/Compressors.py
+++ b/src/mem/cache/compressors/Compressors.py
@@ -45,3 +45,8 @@
use_more_compressors = Param.Bool(True, "True if should use all possible" \
"combinations of base and delta for the compressors. False if using" \
"only the lowest possible delta size for each base size.");
+
+class CPack(BaseCacheCompressor):
+ type = 'CPack'
+ cxx_class = 'CPack'
+ cxx_header = "mem/cache/compressors/cpack.hh"
diff --git a/src/mem/cache/compressors/SConscript b/src/mem/cache/compressors/SConscript
index 38ce340..0b3ba64 100644
--- a/src/mem/cache/compressors/SConscript
+++ b/src/mem/cache/compressors/SConscript
@@ -34,3 +34,4 @@
Source('base.cc')
Source('bdi.cc')
+Source('cpack.cc')
diff --git a/src/mem/cache/compressors/cpack.cc b/src/mem/cache/compressors/cpack.cc
new file mode 100644
index 0000000..1192963
--- /dev/null
+++ b/src/mem/cache/compressors/cpack.cc
@@ -0,0 +1,227 @@
+/*
+ * Copyright (c) 2018 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
+ * Implementation of the CPack cache compressor.
+ */
+
+#include "mem/cache/compressors/cpack.hh"
+
+#include <algorithm>
+#include <cstdint>
+
+#include "debug/CacheComp.hh"
+#include "params/CPack.hh"
+
+CPack::CompData::CompData(const std::size_t dictionary_size)
+ : CompressionData()
+{
+}
+
+CPack::CompData::~CompData()
+{
+}
+
+CPack::CPack(const Params *p)
+ : BaseCacheCompressor(p), dictionarySize(2*blkSize/8)
+{
+ dictionary.resize(dictionarySize);
+
+ resetDictionary();
+}
+
+void
+CPack::resetDictionary()
+{
+ // Reset number of valid entries
+ numEntries = 0;
+
+ // Set all entries as 0
+ std::array<uint8_t, 4> zero_word = {0, 0, 0, 0};
+ std::fill(dictionary.begin(), dictionary.end(), zero_word);
+}
+
+std::unique_ptr<CPack::Pattern>
+CPack::compressWord(const uint32_t data)
+{
+ // Split data in bytes
+ const std::array<uint8_t, 4> bytes = {
+ static_cast<uint8_t>(data & 0xFF),
+ static_cast<uint8_t>((data >> 8) & 0xFF),
+ static_cast<uint8_t>((data >> 16) & 0xFF),
+ static_cast<uint8_t>((data >> 24) & 0xFF)
+ };
+
+ // Start as a no-match pattern. A negative match location is used so that
+ // patterns that depend on the dictionary entry don't match
+ std::unique_ptr<Pattern> pattern =
+ PatternFactory::getPattern(bytes, {0, 0, 0, 0}, -1);
+
+ // Search for word on dictionary
+ for (std::size_t i = 0; i < numEntries; i++) {
+ // Try matching input with possible patterns
+ std::unique_ptr<Pattern> temp_pattern =
+ PatternFactory::getPattern(bytes, dictionary[i], i);
+
+ // Check if found pattern is better than previous
+ if (temp_pattern->getSizeBits() < pattern->getSizeBits()) {
+ pattern = std::move(temp_pattern);
+ }
+ }
+
+ // Update stats
+ patternStats[pattern->getPatternNumber()]++;
+
+ // Push into dictionary
+ if ((numEntries < dictionarySize) && pattern->shouldAllocate()) {
+ dictionary[numEntries++] = bytes;
+ }
+
+ return pattern;
+}
+
+std::unique_ptr<BaseCacheCompressor::CompressionData>
+CPack::compress(const uint64_t* data, Cycles& comp_lat, Cycles& decomp_lat)
+{
+ std::unique_ptr<CompData> comp_data =
+ std::unique_ptr<CompData>(new CompData(dictionarySize));
+
+ // Compression size
+ std::size_t size = 0;
+
+ // Reset dictionary
+ resetDictionary();
+
+ // Compress every word sequentially
+ for (std::size_t i = 0; i < blkSize/8; i++) {
+ const uint32_t first_word = ((data[i])&0xFFFFFFFF00000000) >> 32;
+ const uint32_t second_word = (data[i])&0x00000000FFFFFFFF;
+
+ // Compress both words
+ std::unique_ptr<Pattern> first_pattern = compressWord(first_word);
+ std::unique_ptr<Pattern> second_pattern = compressWord(second_word);
+
+ // Update total line compression size
+ size += first_pattern->getSizeBits() + second_pattern->getSizeBits();
+
+ // Print debug information
+ DPRINTF(CacheComp, "Compressed %08x to %s\n", first_word,
+ first_pattern->print());
+ DPRINTF(CacheComp, "Compressed %08x to %s\n", second_word,
+ second_pattern->print());
+
+ // Append to pattern list
+ comp_data->entries.push_back(std::move(first_pattern));
+ comp_data->entries.push_back(std::move(second_pattern));
+ }
+
+ // Set final compression size
+ comp_data->setSizeBits(size);
+
+ // Set compression latency (Accounts for pattern matching, length
+ // generation, packaging and shifting)
+ comp_lat = Cycles(blkSize/8+5);
+
+ // Set decompression latency (1 qword per cycle)
+ decomp_lat = Cycles(blkSize/8);
+
+ // Return compressed line
+ return std::move(comp_data);
+}
+
+uint32_t
+CPack::decompressWord(const Pattern* pattern)
+{
+ std::array<uint8_t, 4> data;
+
+ // Search for matching entry
+ std::vector<std::array<uint8_t, 4>>::iterator entry_it =
+ dictionary.begin();
+ std::advance(entry_it, pattern->getMatchLocation());
+
+ // Decompress the match. If the decompressed value must be added to
+ // the dictionary, do it
+ if (pattern->decompress(*entry_it, data)) {
+ dictionary[numEntries++] = data;
+ }
+
+ // Return word
+ return (((((data[3] << 8) | data[2]) << 8) | data[1]) << 8) | data[0];
+}
+
+void
+CPack::decompress(const CompressionData* comp_data, uint64_t* data)
+{
+ const CompData* cpack_comp_data = static_cast<const CompData*>(comp_data);
+
+ // Reset dictionary
+ resetDictionary();
+
+ // Decompress every entry sequentially
+ std::vector<uint32_t> decomp_words;
+ for (const auto& entry : cpack_comp_data->entries) {
+ const uint32_t word = decompressWord(&*entry);
+ decomp_words.push_back(word);
+
+ // Print debug information
+ DPRINTF(CacheComp, "Decompressed %s to %x\n", entry->print(), word);
+ }
+
+ // Concatenate the decompressed words to generate the cache lines
+ for (std::size_t i = 0; i < blkSize/8; i++) {
+ data[i] = (static_cast<uint64_t>(decomp_words[2*i]) << 32) |
+ decomp_words[2*i+1];
+ }
+}
+
+void
+CPack::regStats()
+{
+ BaseCacheCompressor::regStats();
+
+ // We store the frequency of each pattern
+ patternStats
+ .init(Pattern::getNumPatterns())
+ .name(name() + ".pattern")
+ .desc("Number of data entries that were compressed to this pattern.")
+ ;
+
+ for (unsigned i = 0; i < Pattern::getNumPatterns(); ++i) {
+ patternStats.subname(i, Pattern::getName(i));
+ patternStats.subdesc(i, "Number of data entries that match pattern " +
+ Pattern::getName(i));
+ }
+}
+
+CPack*
+CPackParams::create()
+{
+ return new CPack(this);
+}
diff --git a/src/mem/cache/compressors/cpack.hh b/src/mem/cache/compressors/cpack.hh
new file mode 100644
index 0000000..664a376
--- /dev/null
+++ b/src/mem/cache/compressors/cpack.hh
@@ -0,0 +1,551 @@
+/*
+ * Copyright (c) 2018 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 CPack compression, from "C-Pack: A High-Performance
+ * Microprocessor Cache Compression Algorithm".
+ *
+ * The dictionary is composed of 32-bit entries.
+ *
+ * The patterns are implemented as individual classes that have a checking
+ * function isPattern(), to determine if the data fits the pattern, and a
+ * decompress() function, which decompresses the contents of a pattern.
+ * Every new pattern must inherit from the Pattern class and be added to the
+ * patternFactory.
+ */
+
+#ifndef __MEM_CACHE_COMPRESSORS_CPACK_HH__
+#define __MEM_CACHE_COMPRESSORS_CPACK_HH__
+
+#include <array>
+#include <cstdint>
+#include <map>
+#include <memory>
+#include <vector>
+
+#include "base/types.hh"
+#include "mem/cache/compressors/base.hh"
+
+struct CPackParams;
+
+class CPack : public BaseCacheCompressor
+{
+ private:
+ /**
+ * Compression data for CPack. It consists of a vector of patterns.
+ */
+ class CompData;
+
+ // Forward declaration of all possible patterns
+ class Pattern;
+ class PatternZZZZ;
+ class PatternXXXX;
+ class PatternMMMM;
+ class PatternMMXX;
+ class PatternZZZX;
+ class PatternMMMX;
+
+ /**
+ * Create a factory to determine if input matches a pattern. The if else
+ * chains are constructed by recursion. The patterns should be explored
+ * sorted by size for correct behaviour.
+ */
+ template <class Head, class... Tail>
+ struct Factory
+ {
+ static std::unique_ptr<Pattern> getPattern(
+ const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes, const int match_location)
+ {
+ // If match this pattern, instantiate it. If a negative match
+ // location is used, the patterns that use the dictionary bytes
+ // must return false. This is used when there are no dictionary
+ // entries yet
+ if (Head::isPattern(bytes, dict_bytes, match_location)) {
+ return std::unique_ptr<Pattern>(
+ new Head(bytes, match_location));
+ // Otherwise, go for next pattern
+ } else {
+ return Factory<Tail...>::getPattern(bytes, dict_bytes,
+ match_location);
+ }
+ }
+ };
+
+ /**
+ * Specialization to end the recursion.
+ */
+ template <class Head>
+ struct Factory<Head>
+ {
+ static std::unique_ptr<Pattern> getPattern(
+ const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes, const int match_location)
+ {
+ // Instantiate last pattern. Should be the XXXX pattern.
+ return std::unique_ptr<Pattern>(new Head(bytes, match_location));
+ }
+ };
+
+ /**
+ * Convenience factory declaration. The templates must be organized by
+ * size, with the smallest first, and "no-match" last.
+ */
+ using PatternFactory = Factory<PatternZZZZ, PatternMMMM, PatternZZZX,
+ PatternMMMX, PatternMMXX, PatternXXXX>;
+
+ /**
+ * The dictionary.
+ */
+ std::vector<std::array<uint8_t, 4>> dictionary;
+
+ /**
+ * Dictionary size.
+ */
+ const std::size_t dictionarySize;
+
+ /**
+ * Number of valid entries in the dictionary.
+ */
+ std::size_t numEntries;
+
+ /**
+ * @defgroup CompressionStats Compression specific statistics.
+ * @{
+ */
+
+ /**
+ * Number of data entries that were compressed to each pattern.
+ */
+ Stats::Vector patternStats;
+
+ /**
+ * @}
+ */
+
+ /**
+ * Compress data.
+ *
+ * @param data Data to be compressed.
+ * @return The pattern this data matches.
+ */
+ std::unique_ptr<Pattern> compressWord(const uint32_t data);
+
+ /**
+ * Decompress a word.
+ *
+ * @param pattern The pattern to be decompressed.
+ * @return The decompressed word.
+ */
+ uint32_t decompressWord(const Pattern* pattern);
+
+ /**
+ * Clear all dictionary entries.
+ */
+ void resetDictionary();
+
+ /**
+ * Apply compression.
+ *
+ * @param data The cache line to be compressed.
+ * @param comp_lat Compression latency in number of cycles.
+ * @param decomp_lat Decompression latency in number of cycles.
+ * @return Cache line after compression.
+ */
+ std::unique_ptr<BaseCacheCompressor::CompressionData> compress(
+ const uint64_t* data, Cycles& comp_lat, Cycles& decomp_lat) override;
+
+ /**
+ * Decompress data.
+ *
+ * @param comp_data Compressed cache line.
+ * @param data The cache line to be decompressed.
+ */
+ void decompress(const CompressionData* comp_data, uint64_t* data) override;
+
+ public:
+ /** Convenience typedef. */
+ typedef CPackParams Params;
+
+ /**
+ * Default constructor.
+ */
+ CPack(const Params *p);
+
+ /**
+ * Default destructor.
+ */
+ ~CPack() {};
+
+ /**
+ * Register local statistics.
+ */
+ void regStats() override;
+};
+
+/**
+ * The compressed data is composed of multiple pattern entries. To add a new
+ * pattern one should inherit from this class and implement isPattern() and
+ * decompress. Then the new pattern must be added to the PatternFactory
+ * declaration in crescent order of size (in the CPack class). The pattern
+ * must be also added to the Name enum in the CPack::Pattern class before
+ * NUM_PATTERNS.
+ */
+class CPack::Pattern
+{
+ protected:
+
+ /**
+ * 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 {
+ ZZZZ, XXXX, MMMM, MMXX, ZZZX, MMMX, NUM_PATTERNS
+ } PatternNumber;
+
+ /**
+ * Pattern enum number.
+ */
+ const PatternNumber patternNumber;
+
+ /**
+ * Code associated to the pattern.
+ */
+ const uint8_t code;
+
+ /**
+ * Length, in bits, of the code and match location.
+ */
+ const uint8_t length;
+
+ /**
+ * Number of unmatched bytes;
+ */
+ const uint8_t numUnmatchedBytes;
+
+ /**
+ * Index representing the the match location.
+ */
+ const int matchLocation;
+
+ /**
+ * Wether the pattern allocates a dictionary entry or not.
+ */
+ const bool allocate;
+
+ /**
+ * Get code of this pattern.
+ *
+ * @return The code.
+ */
+ uint8_t getCode() const { return code; }
+
+ public:
+ /**
+ * Default constructor.
+ *
+ * @param number Pattern number.
+ * @param code Code associated to this pattern.
+ * @param metadata_length Length, in bits, of the code and match location.
+ * @param num_unmatched_bytes Number of unmatched bytes.
+ * @param match_location Index of the match location.
+ */
+ Pattern(const PatternNumber number, const uint64_t code,
+ const uint64_t metadata_length, const uint64_t num_unmatched_bytes,
+ const int match_location, const bool allocate = true)
+ : patternNumber(number), code(code), length(metadata_length),
+ numUnmatchedBytes(num_unmatched_bytes),
+ matchLocation(match_location), allocate(allocate) {};
+
+ /**
+ * Default destructor.
+ */
+ virtual ~Pattern() = default;
+
+ /**
+ * Trick function to get the number of patterns.
+ *
+ * @return The number of defined patterns.
+ */
+ static uint64_t getNumPatterns() { return NUM_PATTERNS; };
+
+ /**
+ * Get enum number associated to this pattern.
+ *
+ * @return The pattern enum number.
+ */
+ PatternNumber getPatternNumber() const { return patternNumber; };
+
+ /**
+ * Get meta-name assigned to the given pattern.
+ *
+ * @param number The number of the pattern.
+ * @return The meta-name of the pattern.
+ */
+ static std::string getName(int number)
+ {
+ static std::map<PatternNumber, std::string> patternNames = {
+ {ZZZZ, "ZZZZ"}, {XXXX, "XXXX"}, {MMMM, "MMMM"},
+ {MMXX, "MMXX"}, {ZZZX, "ZZZX"}, {MMMX, "MMMX"}
+ };
+
+ return patternNames[(PatternNumber)number];
+ };
+
+ /**
+ * Get the index of the dictionary match location.
+ *
+ * @return The index of the match location.
+ */
+ uint8_t getMatchLocation() const { return matchLocation; }
+
+ /**
+ * Get size, in bits, of the pattern (excluding prefix). Corresponds to
+ * unmatched_data_size + code_length.
+ *
+ * @return The size.
+ */
+ std::size_t getSizeBits() const {
+ return numUnmatchedBytes*CHAR_BIT + length;
+ }
+
+ /**
+ * Determine if pattern allocates a dictionary entry.
+ *
+ * @return True if should allocate a dictionary entry.
+ */
+ bool shouldAllocate() const {
+ return allocate;
+ }
+
+ std::string print() const {
+ return csprintf("pattern %s (encoding %x, size %u bits)",
+ getName(patternNumber), getCode(), getSizeBits());
+ }
+
+ /**
+ * Decompress the pattern. Each pattern has its own way of interpreting
+ * its data.
+ *
+ * @param dict_bytes The bytes in the corresponding matching entry.
+ * @param data The decompressed pattern.
+ * @return Whether entry should be added to dictionary or not.
+ */
+ virtual bool decompress(const std::array<uint8_t, 4> dict_bytes,
+ std::array<uint8_t, 4>& data) const = 0;
+};
+
+class CPack::PatternZZZZ : public Pattern
+{
+ public:
+ PatternZZZZ(const std::array<uint8_t, 4> bytes, const int match_location)
+ : Pattern(ZZZZ, 0x0, 2, 0, 0, false) {}
+
+ static bool isPattern(const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes,
+ const int match_location)
+ {
+ return (bytes[3] == 0) && (bytes[2] == 0) && (bytes[1] == 0) &&
+ (bytes[0] == 0);
+ }
+
+ bool decompress(const std::array<uint8_t, 4> dict_bytes,
+ std::array<uint8_t, 4>& data) const override
+ {
+ data = {0, 0, 0, 0};
+ return false;
+ }
+};
+
+class CPack::PatternXXXX : public Pattern
+{
+ private:
+ /**
+ * A copy of the word.
+ */
+ const std::array<uint8_t, 4> bytes;
+
+ public:
+ PatternXXXX(const std::array<uint8_t, 4> bytes, const int match_location)
+ : Pattern(XXXX, 0x1, 2, 4, 0, true), bytes(bytes) {}
+
+ static bool isPattern(const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes,
+ const int match_location)
+ {
+ // It can always be an unmatch, as it is set to this class when other
+ // patterns fail
+ return true;
+ }
+
+ bool decompress(const std::array<uint8_t, 4> dict_bytes,
+ std::array<uint8_t, 4>& data) const override
+ {
+ data = bytes;
+ return true;
+ }
+};
+
+class CPack::PatternMMMM : public Pattern
+{
+ public:
+ PatternMMMM(const std::array<uint8_t, 4> bytes, const int match_location)
+ : Pattern(MMMM, 0x2, 6, 0, match_location, true) {}
+
+ static bool isPattern(const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes,
+ const int match_location)
+ {
+ return (bytes == dict_bytes) && (match_location >= 0);
+ }
+
+ bool decompress(const std::array<uint8_t, 4> dict_bytes,
+ std::array<uint8_t, 4>& data) const override
+ {
+ data = dict_bytes;
+ return true;
+ }
+};
+
+class CPack::PatternMMXX : public Pattern
+{
+ private:
+ /**
+ * A copy of the unmatched bytes.
+ */
+ const uint8_t byte0;
+ const uint8_t byte1;
+
+ public:
+ PatternMMXX(const std::array<uint8_t, 4> bytes, const int match_location)
+ : Pattern(MMXX, 0xC, 8, 2, match_location, true),
+ byte0(bytes[0]), byte1(bytes[1]) {}
+
+ static bool isPattern(const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes,
+ const int match_location)
+ {
+ // Notice we don't compare bytes[0], as otherwise we'd be unnecessarily
+ // discarding MMXM. If that pattern is added this should be modified
+ return (bytes[3] == dict_bytes[3]) && (bytes[2] == dict_bytes[2]) &&
+ (bytes[1] != dict_bytes[1]) && (match_location >= 0);
+
+ }
+
+ bool decompress(const std::array<uint8_t, 4> dict_bytes,
+ std::array<uint8_t, 4>& data) const override
+ {
+ data = {byte0, byte1, dict_bytes[2], dict_bytes[3]};
+ return true;
+ }
+};
+
+class CPack::PatternZZZX : public Pattern
+{
+ private:
+ /**
+ * A copy of the unmatched byte.
+ */
+ const uint8_t byte;
+
+ public:
+ PatternZZZX(const std::array<uint8_t, 4> bytes, const int match_location)
+ : Pattern(ZZZX, 0xD, 4, 1, 0, false), byte(bytes[0]) {}
+
+ static bool isPattern(const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes,
+ const int match_location)
+ {
+ return (bytes[3] == 0) && (bytes[2] == 0) && (bytes[1] == 0) &&
+ (bytes[0] != 0);
+ }
+
+ bool decompress(const std::array<uint8_t, 4> dict_bytes,
+ std::array<uint8_t, 4>& data) const override
+ {
+ data = {byte, 0, 0, 0};
+ return false;
+ }
+};
+
+class CPack::PatternMMMX : public Pattern
+{
+ private:
+ /**
+ * A copy of the unmatched byte.
+ */
+ const uint8_t byte;
+
+ public:
+ PatternMMMX(const std::array<uint8_t, 4> bytes, const int match_location)
+ : Pattern(MMMX, 0xE, 8, 1, match_location, true),
+ byte(bytes[0]) {}
+
+ static bool isPattern(const std::array<uint8_t, 4>& bytes,
+ const std::array<uint8_t, 4>& dict_bytes,
+ const int match_location)
+ {
+ return (bytes[3] == dict_bytes[3]) && (bytes[2] == dict_bytes[2]) &&
+ (bytes[1] == dict_bytes[1]) && (bytes[0] != dict_bytes[0]) &&
+ (match_location >= 0);
+ }
+
+ bool decompress(const std::array<uint8_t, 4> dict_bytes,
+ std::array<uint8_t, 4>& data) const override
+ {
+ data = {byte, dict_bytes[1], dict_bytes[2], dict_bytes[3]};
+ return true;
+ }
+};
+
+class CPack::CompData : public CompressionData
+{
+ public:
+ /**
+ * The patterns matched in the original line.
+ */
+ std::vector<std::unique_ptr<Pattern>> entries;
+
+ /**
+ * Default constructor.
+ *
+ * @param dictionary_size Number of entries in the dictionary.
+ */
+ CompData(const std::size_t dictionary_size);
+
+ /**
+ * Default destructor.
+ */
+ ~CompData();
+};
+
+#endif //__MEM_CACHE_COMPRESSORS_CPACK_HH__
