repeated_qwords.cc

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/*
 * Copyright (c) 2019 Inria
 * All rights reserved.
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 * neither the name of the copyright holders nor the names of its
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 * 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
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * Authors: Daniel Carvalho
 */

#include "mem/cache/compressors/repeated_qwords.hh"

#include "debug/CacheComp.hh"
#include "mem/cache/compressors/dictionary_compressor_impl.hh"
#include "params/RepeatedQwordsCompressor.hh"

RepeatedQwordsCompressor::RepeatedQwordsCompressor(const Params *p)
    : DictionaryCompressor<uint64_t>(p)
{
}

void
RepeatedQwordsCompressor::addToDictionary(DictionaryEntry data)
{
    assert(numEntries < dictionarySize);
    dictionary[numEntries++] = data;
}

std::unique_ptr<BaseCacheCompressor::CompressionData>
RepeatedQwordsCompressor::compress(const uint64_t* data, Cycles& comp_lat,
    Cycles& decomp_lat)
{
    std::unique_ptr<BaseCacheCompressor::CompressionData> comp_data =
        DictionaryCompressor::compress(data);

    // Since there is a single value repeated over and over, there should be
    // a single dictionary entry. If there are more, the compressor failed
    assert(numEntries >= 1);
    if (numEntries > 1) {
        comp_data->setSizeBits(blkSize * 8);
        DPRINTF(CacheComp, "Repeated qwords compression failed\n");
    }

    // Set compression latency
    comp_lat = Cycles(1);

    // Set decompression latency
    decomp_lat = Cycles(1);

    // Return compressed line
    return comp_data;
}

RepeatedQwordsCompressor*
RepeatedQwordsCompressorParams::create()
{
    return new RepeatedQwordsCompressor(this);
}