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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.
*/
#ifndef __MEM_CACHE_COMPRESSORS_ENCODERS_BASE_HH__
#define __MEM_CACHE_COMPRESSORS_ENCODERS_BASE_HH__
#include <cstdint>
#include "base/compiler.hh"
namespace gem5
{
GEM5_DEPRECATED_NAMESPACE(Compressor, compression);
namespace compression
{
GEM5_DEPRECATED_NAMESPACE(Encoder, encoder);
namespace encoder
{
struct Code
{
/** Only the LSB of the code are relevant. */
uint64_t code;
/** Number of bits in the code. */
unsigned length;
};
/**
* Base class for encoders. The goal of encoders is to provide an alternative
* representation to values, ideally shorter than the value. The alternative
* representation is called a code.
*/
class Base
{
public:
Base() {}
virtual ~Base() = default;
/**
* The function responsible for the generation of the alternative value.
* If the size of the returning Code is greater than the maximum undelying
* type's size (e.g., 64 bits) the encoding results should be discarded.
*
* @param The value to be encoded.
* @return The encoded value.
*/
virtual Code encode(const uint64_t val) const = 0;
/**
* Decode a value.
* @sa encode()
*
* @param code The encoded value.
* @return The original value.
*/
virtual uint64_t decode(const uint64_t code) const = 0;
};
} // namespace encoder
} // namespace compression
} // namespace gem5
#endif //__MEM_CACHE_COMPRESSORS_ENCODERS_BASE_HH__