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/*
* Copyright (c) 2019 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 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"
PerfectCompressor::CompData::CompData(const uint64_t* data,
std::size_t num_entries)
: CompressionData(), entries(data, data + num_entries)
{
}
PerfectCompressor::PerfectCompressor(const Params *p)
: BaseCacheCompressor(p),
compressedSize(8 * blkSize / p->max_compression_ratio),
compressionLatency(p->compression_latency),
decompressionLatency(p->decompression_latency)
{
}
std::unique_ptr<BaseCacheCompressor::CompressionData>
PerfectCompressor::compress(const uint64_t* cache_line, Cycles& comp_lat,
Cycles& decomp_lat)
{
// Compress every word sequentially
std::unique_ptr<BaseCacheCompressor::CompressionData> comp_data(
new CompData(cache_line, blkSize/8));
// Set relevant metadata
comp_data->setSizeBits(compressedSize);
comp_lat = compressionLatency;
decomp_lat = decompressionLatency;
return comp_data;
}
void
PerfectCompressor::decompress(const CompressionData* comp_data,
uint64_t* data)
{
// Decompress every entry sequentially
const std::vector<uint64_t>& entries =
static_cast<const CompData*>(comp_data)->entries;
assert(entries.size() == (blkSize/8));
std::copy(entries.begin(), entries.end(), data);
}
PerfectCompressor*
PerfectCompressorParams::create()
{
return new PerfectCompressor(this);
}
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