src/mem/cache/compressors/perfect.cc

/*
 * Copyright (c) 2019-2020 Inria
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/** @file
 * Implementation of a perfect compressor, which compresses data to its
 * maximum allowed compression ratio.
 */

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

#include <algorithm>

#include "debug/CacheComp.hh"
#include "params/PerfectCompressor.hh"

namespace Compressor {

Perfect::Perfect(const Params *p)
  : Base(p), compressedSize(8 * blkSize / p->max_compression_ratio),
    compressionLatency(p->compression_latency),
    decompressionLatency(p->decompression_latency)
{
}

std::unique_ptr<Base::CompressionData>
Perfect::compress(const std::vector<Chunk>& chunks,
    Cycles& comp_lat, Cycles& decomp_lat)
{
    // Compress every word sequentially
    std::unique_ptr<Base::CompressionData> comp_data(new CompData(chunks));

    // Set relevant metadata
    comp_data->setSizeBits(compressedSize);
    comp_lat = compressionLatency;
    decomp_lat = decompressionLatency;

    return comp_data;
}

void
Perfect::decompress(const CompressionData* comp_data,
    uint64_t* data)
{
    // Decompress every entry sequentially
    fromChunks(static_cast<const CompData*>(comp_data)->chunks, data);
}

} // namespace Compressor

Compressor::Perfect*
PerfectCompressorParams::create()
{
    return new Compressor::Perfect(this);
}