123 lines
2.8 KiB
C++
123 lines
2.8 KiB
C++
/*
|
|
|
|
Arsenic algorithm: BWT and arithmetic coding.
|
|
|
|
The code in this file is based on TheUnarchiver.
|
|
See README.md and docs/licenses/TheUnarchiver.txt for more information.
|
|
|
|
Copyright (C) 2019, Guillaume Gonnet
|
|
|
|
This program is free software: you can redistribute it and/or modify it under
|
|
the terms of the GNU General Public License as published by the Free Software
|
|
Foundation, either version 3 of the License, or (at your option) any later
|
|
version.
|
|
|
|
This program is distributed in the hope that it will be useful, but WITHOUT ANY
|
|
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
|
|
PARTICULAR PURPOSE. See the GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License along with
|
|
this program. If not, see <https://www.gnu.org/licenses/>.
|
|
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include "stuffit/methods.h"
|
|
#include "stuffit/utils/bwt.h"
|
|
#include "stuffit/utils/crc.h"
|
|
#include "utils/bit_reader.h"
|
|
|
|
#include <memory>
|
|
|
|
namespace maconv {
|
|
namespace stuffit {
|
|
|
|
|
|
// Store an arithmetic symbol.
|
|
struct ArithmeticSymbol {
|
|
int symbol;
|
|
int freq;
|
|
};
|
|
|
|
|
|
// The arithmetic model.
|
|
struct ArithmeticModel {
|
|
|
|
// Initialize the model with some values.
|
|
void Initialize(int firstsymb, int lastsym, int incr, int freqlimit);
|
|
|
|
// Reset the model.
|
|
void ResetModel();
|
|
|
|
// Increase the model frequency at |symindex| by |increment|.
|
|
void IncreaseFrequency(int symindex);
|
|
|
|
int total_freq;
|
|
int increment;
|
|
int freq_limit;
|
|
|
|
int num_symbols;
|
|
ArithmeticSymbol symbols[128];
|
|
};
|
|
|
|
|
|
// The arithmetic decoder.
|
|
struct ArithmeticDecoder {
|
|
|
|
// Initialize the decoder with some values.
|
|
void Initialize(uint8_t *data, uint32_t length);
|
|
|
|
// Get the next arithmetic code.
|
|
void NextCode(int symlow, int symsize, int symtot);
|
|
|
|
// Get the next arithmetic symbol.
|
|
int NextSymbol(ArithmeticModel *model);
|
|
|
|
// Get the next word (that has |n| bits).
|
|
int NextWord(ArithmeticModel *model, int n);
|
|
|
|
utils::BitReaderBE input;
|
|
int range, code;
|
|
};
|
|
|
|
|
|
|
|
// Arsenic compression algorithm.
|
|
struct ArsenicMethod : CompressionMethod {
|
|
|
|
// Initialize the algorithm.
|
|
void Initialize() override;
|
|
|
|
// Read the next block.
|
|
void ReadNextBlock();
|
|
|
|
|
|
// Read the next byte.
|
|
int32_t ReadNextByte();
|
|
|
|
// Read the next bytes.
|
|
int32_t ReadBytes(uint8_t *data, uint32_t length) override;
|
|
|
|
|
|
ArithmeticModel initial_model, selector_model, mtf_model[7];
|
|
ArithmeticDecoder decoder;
|
|
MtfDecoder mtf;
|
|
|
|
std::unique_ptr<uint8_t[]> block;
|
|
int block_bits, block_size;
|
|
bool end_of_blocks;
|
|
|
|
int num_bytes, byte_count, transform_index;
|
|
std::unique_ptr<uint32_t[]> transform;
|
|
|
|
int randomized, rand_count, rand_index;
|
|
int repeat, count, last;
|
|
|
|
uint32_t crc, compcrc;
|
|
};
|
|
|
|
|
|
} // namespace stuffit
|
|
} // namespace maconv
|