/*
 * 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 zero compressor, which compressed data if it is entirely
 * composed of zero bits.
 */

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

#include "debug/CacheComp.hh"
#include "mem/cache/compressors/dictionary_compressor_impl.hh"
#include "params/ZeroCompressor.hh"

ZeroCompressor::ZeroCompressor(const Params *p)
    : DictionaryCompressor<uint64_t>(p)
{
}

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

std::unique_ptr<BaseCacheCompressor::CompressionData>
ZeroCompressor::compress(const uint64_t* data, Cycles& comp_lat,
    Cycles& decomp_lat)
{
    std::unique_ptr<BaseCacheCompressor::CompressionData> comp_data =
        DictionaryCompressor::compress(data);

    // If there is any non-zero entry, the compressor failed
    if (numEntries > 0) {
        comp_data->setSizeBits(blkSize * 8);
        DPRINTF(CacheComp, "Zero compression failed\n");
    }

    // Set compression latency (Assumes full line zero comparison)
    comp_lat = Cycles(1);

    // Set decompression latency
    decomp_lat = Cycles(1);

    // Return compressed line
    return comp_data;
}

ZeroCompressor*
ZeroCompressorParams::create()
{
    return new ZeroCompressor(this);
}