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https://github.com/libretro/scummvm.git
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95 lines
2.5 KiB
C++
95 lines
2.5 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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// Based on eos' Huffman code
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#ifndef COMMON_HUFFMAN_H
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#define COMMON_HUFFMAN_H
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#include "common/array.h"
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#include "common/list.h"
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#include "common/types.h"
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namespace Common {
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/**
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* Huffman bitstream decoding
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*
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* Used in engines:
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* - scumm
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*/
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class Huffman {
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public:
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/** Construct a Huffman decoder.
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*
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* @param maxLength Maximal code length. If 0, it's searched for.
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* @param codeCount Number of codes.
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* @param codes The actual codes.
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* @param lengths Lengths of the individual codes.
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* @param symbols The symbols. If 0, assume they are identical to the code indices.
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*/
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Huffman(uint8 maxLength, uint32 codeCount, const uint32 *codes, const uint8 *lengths, const uint32 *symbols = nullptr);
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~Huffman();
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/** Modify the codes' symbols. */
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void setSymbols(const uint32 *symbols = nullptr);
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/** Return the next symbol in the bitstream. */
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template<class BITSTREAM>
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uint32 getSymbol(BITSTREAM &bits) const {
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uint32 code = 0;
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for (uint32 i = 0; i < _codes.size(); i++) {
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bits.addBit(code, i);
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for (CodeList::const_iterator cCode = _codes[i].begin(); cCode != _codes[i].end(); ++cCode)
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if (code == cCode->code)
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return cCode->symbol;
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}
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error("Unknown Huffman code");
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return 0;
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}
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private:
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struct Symbol {
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uint32 code;
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uint32 symbol;
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Symbol(uint32 c, uint32 s);
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};
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typedef List<Symbol> CodeList;
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typedef Array<CodeList> CodeLists;
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typedef Array<Symbol *> SymbolList;
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/** Lists of codes and their symbols, sorted by code length. */
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CodeLists _codes;
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/** Sorted list of pointers to the symbols. */
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SymbolList _symbols;
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};
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} // End of namespace Common
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#endif // COMMON_HUFFMAN_H
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