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71 lines
2.4 KiB
C++
71 lines
2.4 KiB
C++
/// \file
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/// \brief \b [Internal] Generates a huffman encoding tree, used for string and global compression.
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///
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/// This file is part of RakNet Copyright 2003 Kevin Jenkins.
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///
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/// Usage of RakNet is subject to the appropriate license agreement.
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/// Creative Commons Licensees are subject to the
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/// license found at
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/// http://creativecommons.org/licenses/by-nc/2.5/
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/// Single application licensees are subject to the license found at
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/// http://www.rakkarsoft.com/SingleApplicationLicense.html
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/// Custom license users are subject to the terms therein.
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/// GPL license users are subject to the GNU General Public
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/// License as published by the Free
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/// Software Foundation; either version 2 of the License, or (at your
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/// option) any later version.
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#ifndef __HUFFMAN_ENCODING_TREE
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#define __HUFFMAN_ENCODING_TREE
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#include "DS_HuffmanEncodingTreeNode.h"
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#include "BitStream.h"
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#include "Export.h"
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#include "DS_LinkedList.h"
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/// This generates special cases of the huffman encoding tree using 8 bit keys with the additional condition that unused combinations of 8 bits are treated as a frequency of 1
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class RAK_DLL_EXPORT HuffmanEncodingTree
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{
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public:
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HuffmanEncodingTree();
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~HuffmanEncodingTree();
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/// Pass an array of bytes to array and a preallocated BitStream to receive the output
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/// \param [in] input Array of bytes to encode
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/// \param [in] sizeInBytes size of \a input
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/// \param [out] output The bitstream to write to
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void EncodeArray( unsigned char *input, unsigned sizeInBytes, RakNet::BitStream * output );
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// Decodes an array encoded by EncodeArray()
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unsigned DecodeArray( RakNet::BitStream * input, unsigned sizeInBits, unsigned maxCharsToWrite, unsigned char *output );
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void DecodeArray( unsigned char *input, unsigned sizeInBits, RakNet::BitStream * output );
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/// Given a frequency table of 256 elements, all with a frequency of 1 or more, generate the tree
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void GenerateFromFrequencyTable( unsigned int frequencyTable[ 256 ] );
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/// Free the memory used by the tree
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void FreeMemory( void );
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private:
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/// The root node of the tree
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HuffmanEncodingTreeNode *root;
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/// Used to hold bit encoding for one character
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struct CharacterEncoding
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{
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unsigned char* encoding;
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unsigned short bitLength;
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};
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CharacterEncoding encodingTable[ 256 ];
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void InsertNodeIntoSortedList( HuffmanEncodingTreeNode * node, DataStructures::LinkedList<HuffmanEncodingTreeNode *> *huffmanEncodingTreeNodeList ) const;
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};
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#endif
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