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/*
* Copyright (c) 2019-2020 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.
*/
/** @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