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