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GLAST/LAT > DAQ and FSW > FSW > Doxygen Index > LDT / V0-0-0

Constituent: encdec     Tag: linux-gcc

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HUFF.h File Reference

Huffman Encode/Decode, interface file. More...

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Data Structures
struct	_HUFF_code
	Huffman code for a symbol. More...
struct	_HUFF_node
	Node in a Huffman tree. More...
Typedefs
typedef _HUFF_node	HUFF_node
	Typedef for struct _HUFF_node.
typedef _HUFF_code	HUFF_code
	Typedef for struct _HUFF_code.
Functions
void	HUFF_accumulate (int *freqs, const unsigned char *original, int size)
	Accumulates the frequency distribution.
int	HUFF_build (HUFF_code *table, const int *freqs, int count)
	Builds a Huffman code table from the input frequency distribution.
int	HUFF_compress (const unsigned char *original, int size, const HUFF_code *table, unsigned char **compressed)
	Compresses the input array original into the output array.
int	HUFF_size (const HUFF_code *table, const int *freqs, int count)
	Computes the size, in bits, of the specified encode freqs.
int	HUFF_uncompress (const unsigned char *compressed, unsigned char **original)
	Decompresses the input byte stream compressed.

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Detailed Description

Huffman Encode/Decode, interface file.

Author:

JJRussell - russell@slac.stanford.edu

CVS $Id

Warning:

In their current state, these routines are not fit for Flight use. They can be used to determine compression factors and, in general, study the properties of Huffman encoding/decoding. However, they malloc all over the place and involve recursive calling techniques, neither of is appropriate for Flight code.

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Function Documentation

void HUFF_accumulate (  int *  freqs, const unsigned char *  original, int  size )

Accumulates the frequency distribution. Parameters: freqs  The accumulated and appropriately scaled frequency distribution. Must be at 256 characters in width original  The input set of characters. The distribution is created from this set size  The number of characters in original

int HUFF_build (  HUFF_code *  table, const int *  freqs, int  count )

Builds a Huffman code table from the input frequency distribution. Returns: Status Parameters: table  The table, must have at least count elements freqs  The frequency distribution count  The number of elements in the frequency distribution

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int HUFF_compress (  const unsigned char *  original, int  size, const HUFF_code *  table, unsigned char **  compressed )

Compresses the input array original into the output array. Returns: Size of the compressed data in bytes. Parameters: original  The array of bytes to compress size  The number of bytes in original to compress table  A previously built Huffman table used to encode the data compressed  Returned as a pointer to the compressed data

int HUFF_size (  const HUFF_code *  table, const int *  freqs, int  count )

Computes the size, in bits, of the specified encode freqs. Returns: The size in bits. Parameters: table  The table, must have at least count elements freqs  The frequency distribution count  The number of elements in the frequency distribution

int HUFF_uncompress (  const unsigned char *  compressed, unsigned char **  original )

Decompresses the input byte stream compressed. Returns: The number of decompressed bytes, i.e. the size of original Parameters: compressed  The compressed bit stream original  Returned as a pointer to the decompressed data

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