src/mem/cache/compressors/repeated_qwords.cc

/*
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/** @file
 * Implementation of a repeated values compressor, which compresses data if
 * it is entirely composed of repeated qwords.
 */

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

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

namespace Compressor {

RepeatedQwords::RepeatedQwords(const Params &p)
    : DictionaryCompressor<uint64_t>(p)
{
}

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

std::unique_ptr<Base::CompressionData>
RepeatedQwords::compress(const std::vector<Chunk>& chunks,
    Cycles& comp_lat, Cycles& decomp_lat)
{
    std::unique_ptr<Base::CompressionData> comp_data =
        DictionaryCompressor::compress(chunks);

    // 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;
}

} // namespace Compressor