compress.h File Reference

The compression structure brings together all the tables required for the operation of the Arithmetic Probability Encoder and the various associated functions provided access to these tables. More...

#include <stdio.h>

Include dependency graph for compress.h:

This graph shows which files directly or indirectly include this file:


Typedefs
typedef LSEC_compression_	LSEC_compression
	Declaration of the opaque compression structure.
Functions
LSEC_compression *	LSEC_newCompression (unsigned int nbits, const char *name)
	Allocate and initialise a new compression structure.
void	LSEC_deleteCompression (LSEC_compression *cpr)
	Free the memory associated with the compression structure.
void	LSEC_clearCompression (LSEC_compression *cpr)
	Clear the compression structrure of any data from a previous cycle.
unsigned	LSEC_checkCompression (LSEC_compression *cpr)
	Check if there were errors during the histogram or encode operations.
void	LSEC_reportCompression (LSEC_compression cmp, FILE fp)
	Describe the contents of a compression structure.
void	LSEC_zeroBin (LSEC_compression *cpr, unsigned int bin)
	Set the selected bin of the histogram to zero.
unsigned int	LSEC_getBin (LSEC_compression *cpr, unsigned int bin)
	Return the contents of one bin of the histogram.
unsigned int	LSEC_getCount (LSEC_compression *cpr)
	Return the number of non-zero bins in the histogram.
unsigned	LSEC_process (LSEC_compression *cpr)
	Build the lookup, frequency and probability tables required by the APE.
unsigned *	LSEC_pack (LSEC_compression cpr, unsigned buffer)
	Pack the tables of a compression structure into a buffer.
unsigned	LSEC_packedSize32 (LSEC_compression *cpr)
	Calculate the size of a packed compression structure.

Detailed Description

The compression structure brings together all the tables required for the operation of the Arithmetic Probability Encoder and the various associated functions provided access to these tables.

Author:: James Swain -- jswain@slac.stanford.edu

Function Documentation

unsigned LSEC_checkCompression ( LSEC_compression * cpr )

Check if there were errors during the histogram or encode operations.

Parameters:

cpr Pointer to a compression structure

Return values:

LSEC_SYMOOR If any of the symbols histogrammed or encoded by this compression structure were out of range

LSEC_AWEFAIL If there were any error during the encoding

LSEC_SUCCESS If there were no errors

void LSEC_clearCompression ( LSEC_compression * cpr )

Clear the compression structrure of any data from a previous cycle.

Parameters:

cpr Pointer to an allocated, initialised, compression structure

void LSEC_deleteCompression ( LSEC_compression * cpr )

Free the memory associated with the compression structure.

Parameters:

cpr Pointer to an allocated compression structure

unsigned int LSEC_getBin ( LSEC_compression * cpr,

unsigned int bin

)

Return the contents of one bin of the histogram.

Parameters:

cpr Pointer to an allocated, initialised, populated, compression structure

bin ID of one of the bins of the histogram

Returns:
Contents of the bin

unsigned int LSEC_getCount ( LSEC_compression * cpr )

Return the number of non-zero bins in the histogram.

Parameters:

cpr Pointer to a compression structure

Returns:
Number of non-zero bins in the histogram

LSEC_compression* LSEC_newCompression ( unsigned int nbits,

const char * name

)

Allocate and initialise a new compression structure.

Parameters:

name String used in the reporting of error to identify a compression structure

nbits Number of symbols in the complete range of possible symbols (including excluded internal sub-ranges), hence the number of bins in the histogram and frequency tables

Returns:
Pointer to an allocated and initialised LSEC_compression structure
The order of calling the functions presented here should be LSEC_newCompression LSEC_histogram - Repeat as necessary LSEC_process LSEC_pack LSEC_compress - Repeat as necessary LSEC_clearCompression : repeat as necessary : LSEC_deleteCompression

unsigned* LSEC_pack ( LSEC_compression * cpr,

unsigned * buffer

)

Pack the tables of a compression structure into a buffer.
This routine selects sufficient data from the tables of the compression structure to be able to recreate the tables required to decompress the data, and pack it into the consignment

Parameters:

buffer Pointer to the start of the buffer to place the packed structure

cpr Pointer to an initialised, populated and processed compression structure

Returns:
Pointer to the word after this compression structure after packing

unsigned LSEC_packedSize32 ( LSEC_compression * cpr )

Calculate the size of a packed compression structure.
This routine calculates the number of 32-bit words required to hold the packed compression structure

Parameters:

cpr Pointer to a compression structure

Returns:
Size of the packed compression structure

unsigned LSEC_process ( LSEC_compression * cpr )

Build the lookup, frequency and probability tables required by the APE.

Parameters:

cpr Pointer to an allocated, initialised, populated, compression structure

Return values:

LSEC_SUCCESS If the processing goes well

void LSEC_reportCompression ( LSEC_compression * cmp,

FILE * fp

)

Describe the contents of a compression structure.
This routine formats the compression structure as ASCII text and writes it to the specified file

Parameters:

cmp Pointer to the compression structure

fp Pointer to the file used as the destination

void LSEC_zeroBin ( LSEC_compression * cpr,

unsigned int bin

)

Set the selected bin of the histogram to zero.
This indicates that this symbol will be selectively removed from the uncompressed data stream before encoding

Parameters:

cpr Pointer to an allocated, initialised, populated, compression structure

bin ID of one of the bins of the histogram

Generated on Thu Jun 14 05:29:48 2007 by

1.4.4

compress.h File Reference

Typedefs

Functions

Detailed Description

Function Documentation