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90 lines
2.1 KiB
C
90 lines
2.1 KiB
C
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#ifndef ENGINE_SHARED_HUFFMAN_H
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#define ENGINE_SHARED_HUFFMAN_H
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class CHuffman
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{
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enum
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{
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HUFFMAN_EOF_SYMBOL = 256,
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HUFFMAN_MAX_SYMBOLS=HUFFMAN_EOF_SYMBOL+1,
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HUFFMAN_MAX_NODES=HUFFMAN_MAX_SYMBOLS*2-1,
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HUFFMAN_LUTBITS = 10,
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HUFFMAN_LUTSIZE = (1<<HUFFMAN_LUTBITS),
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HUFFMAN_LUTMASK = (HUFFMAN_LUTSIZE-1)
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};
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struct CNode
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{
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// symbol
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unsigned m_Bits;
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unsigned m_NumBits;
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// don't use pointers for this. shorts are smaller so we can fit more data into the cache
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unsigned short m_aLeafs[2];
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// what the symbol represents
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unsigned char m_Symbol;
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};
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CNode m_aNodes[HUFFMAN_MAX_NODES];
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CNode *m_apDecodeLut[HUFFMAN_LUTSIZE];
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CNode *m_pStartNode;
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int m_NumNodes;
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void Setbits_r(CNode *pNode, int Bits, int Depth);
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void ConstructTree(const unsigned *pFrequencies);
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public:
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/*
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Function: huffman_init
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Inits the compressor/decompressor.
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Parameters:
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huff - Pointer to the state to init
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frequencies - A pointer to an array of 256 entries of the frequencies of the bytes
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Remarks:
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- Does no allocation what so ever.
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- You don't have to call any cleanup functions when you are done with it
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*/
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void Init(const unsigned *pFrequencies);
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/*
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Function: huffman_compress
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Compresses a buffer and outputs a compressed buffer.
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Parameters:
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huff - Pointer to the huffman state
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input - Buffer to compress
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input_size - Size of the buffer to compress
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output - Buffer to put the compressed data into
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output_size - Size of the output buffer
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Returns:
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Returns the size of the compressed data. Negative value on failure.
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*/
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int Compress(const void *pInput, int InputSize, void *pOutput, int OutputSize);
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/*
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Function: huffman_decompress
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Decompresses a buffer
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Parameters:
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huff - Pointer to the huffman state
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input - Buffer to decompress
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input_size - Size of the buffer to decompress
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output - Buffer to put the uncompressed data into
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output_size - Size of the output buffer
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Returns:
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Returns the size of the uncompressed data. Negative value on failure.
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*/
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int Decompress(const void *pInput, int InputSize, void *pOutput, int OutputSize);
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};
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#endif // __HUFFMAN_HEADER__
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