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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
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @file
* Implementation of the FPC-D cache compressor.
*/
#include "mem/cache/compressors/fpcd.hh"
#include "mem/cache/compressors/dictionary_compressor_impl.hh"
#include "params/FPCD.hh"
FPCD::FPCD(const Params *p)
: DictionaryCompressor<uint32_t>(p)
{
}
void
FPCD::addToDictionary(DictionaryEntry data)
{
// The dictionary behaves as a table with FIFO as replacement policy
if (numEntries == 2) {
dictionary[penultimateIndex] = dictionary[previousIndex];
dictionary[previousIndex] = data;
} else {
dictionary[numEntries++] = data;
}
}
std::unique_ptr<BaseCacheCompressor::CompressionData>
FPCD::compress(const uint64_t* data, Cycles& comp_lat, Cycles& decomp_lat)
{
std::unique_ptr<BaseCacheCompressor::CompressionData> comp_data =
DictionaryCompressor<uint32_t>::compress(data);
// Set compression latency (Accounts for zero checks, ones check, match
// previous check, match penultimate check, repeated values check, pattern
// selection, shifting, at a rate of 16B per cycle)
comp_lat = Cycles(blkSize/2);
// Set decompression latency. The original claim of 2 cycles is likely
// too unrealistic
decomp_lat = Cycles(4);
// Return compressed line
return comp_data;
}
FPCD*
FPCDParams::create()
{
return new FPCD(this);
}