incremental CRC-32 More...

#include "cgul_exception.h"

Include dependency graph for cgul_crc32_incr.h:

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Typedefs
typedef typedefCGUL_BEGIN_C struct cgul_crc32_incr *	cgul_crc32_incr_t

Functions
CGUL_EXPORT cgul_crc32_incr_t	cgul_crc32_incr__new (cgul_exception_t *cex, unsigned long g, unsigned long init, unsigned long final_xor, int reflected)

CGUL_EXPORT cgul_crc32_incr_t	cgul_crc32_incr__new_appends_size (cgul_exception_t *cex, unsigned long g, unsigned long init, unsigned long final_xor, int reflected, size_t size_xor)

CGUL_EXPORT void	cgul_crc32_incr__delete (cgul_crc32_incr_t crc)

CGUL_EXPORT void	cgul_crc32_incr__assign (cgul_exception_t *cex, cgul_crc32_incr_t lhs, cgul_crc32_incr_t rhs)

CGUL_EXPORT unsigned long	cgul_crc32_incr__crc (cgul_exception_t *cex, cgul_crc32_incr_t crc)

CGUL_EXPORT void	cgul_crc32_incr__update_block (cgul_exception_t cex, cgul_crc32_incr_t crc, const void block, size_t length)

CGUL_EXPORT void	cgul_crc32_incr__update_file (cgul_exception_t cex, cgul_crc32_incr_t crc, FILE f)

CGUL_EXPORT void	cgul_crc32_incr__update_fname (cgul_exception_t cex, cgul_crc32_incr_t crc, const char fname)

CGUL_EXPORT void	cgul_crc32_incr__reset (cgul_exception_t *cex, cgul_crc32_incr_t crc)

Detailed Description

This class is a wrapper around the cgul_crc32 class. It is designed so that CRC-32 values can be calculated incrementally. The problem is that cgul_crc32__crc() must be called to calculate the final CRC-32 value, but this operation destroys the previous state making it otherwise impossible to continue a CRC-32 calculation based on data already consumed. Without anything else, you would have to re-calculate the entire CRC-32 value from scratch. This class lets you incrementally calculate CRC-32 values by saving the intermediate state between calls to cgul_crc32__crc().

See also: cgul_crc32

Typedef Documentation

§ cgul_crc32_incr_t

typedef typedefCGUL_BEGIN_C struct cgul_crc32_incr* cgul_crc32_incr_t

Opaque pointer to a cgul_crc32_incr instance.

Function Documentation

§ cgul_crc32_incr__new()

CGUL_EXPORT cgul_crc32_incr_t cgul_crc32_incr__new	(	cgul_exception_t *	cex,
		unsigned long	g,
		unsigned long	init,
		unsigned long	final_xor,
		int	reflected
	)

Create a new cgul_crc32_incr object. Objects created with this constructor do not append the size to the data stream that is CRCed. The client is responsible for calling cgul_crc32_incr__delete() on the object returned. If an error occurs, NULL is returned, and an exception is thrown.

Parameters

[in,out]	cex	c-style exception
[in]	g	generator polynomial
[in]	init	initial value loaded into the accumulator
[in]	final_xor	value to xor with the calculated crc
[in]	reflected	whether to use the reflected algorithm

Returns: new cgul_crc32_incr instance

See also: cgul_crc32__new()

Referenced by cgul_crc32_incr_cxx::cgul_crc32_incr_cxx().

§ cgul_crc32_incr__new_appends_size()

CGUL_EXPORT cgul_crc32_incr_t cgul_crc32_incr__new_appends_size	(	cgul_exception_t *	cex,
		unsigned long	g,
		unsigned long	init,
		unsigned long	final_xor,
		int	reflected,
		size_t	size_xor
	)

Create a new cgul_crc32_incr object. Objects created with this constructor append the size to the data stream that is CRCed. The client is responsible for calling cgul_crc32_incr__delete() on the object returned. If an error occurs, NULL is returned, and an exception is thrown.

Parameters

[in,out]	cex	c-style exception
[in]	g	polynomial
[in]	init	initial value loaded into the accumulator
[in]	final_xor	value to xor with the calculated crc
[in]	reflected	whether to use the reflected algorithm
[in]	size_xor	value to xor with the size before appending

Returns: new cgul_crc32_incr instance

See also: cgul_crc32__new_appends_size()

Referenced by cgul_crc32_incr_cxx::cgul_crc32_incr_cxx().

§ cgul_crc32_incr__delete()

CGUL_EXPORT void cgul_crc32_incr__delete ( cgul_crc32_incr_t crc )

This function frees all internally allocated resources associated with the crc instance. The client must not attempt to use crc after calling this method.

Parameters

[in] crc cgul_crc32_incr instance

Referenced by cgul_crc32_incr_cxx::set_obj(), and cgul_crc32_incr_cxx::~cgul_crc32_incr_cxx().

§ cgul_crc32_incr__assign()

CGUL_EXPORT void cgul_crc32_incr__assign	(	cgul_exception_t *	cex,
		cgul_crc32_incr_t	lhs,
		cgul_crc32_incr_t	rhs
	)

Assign the current state of of rhs to lhs. This operation probably only makes sense if lhs and rhs have been constructed identically. If an error occurs, an exception is thrown.

Parameters

[in,out]	cex	c-style exception
[in]	lhs	left-hand side
[in]	rhs	right-hand side

Referenced by cgul_crc32_incr_cxx::assign().

§ cgul_crc32_incr__crc()

CGUL_EXPORT unsigned long cgul_crc32_incr__crc	(	cgul_exception_t *	cex,
		cgul_crc32_incr_t	crc
	)

This method completes the CRC calculation by performing the size XOR and the final XOR. Unlike cgul_crc32__crc(), this method does not reset the CRC-32 calculation. Instead, the current CRC-32 calculation can be continued with subsequent calls to cgul_crc32_incr__update_block(). The return value is the current value for the entire CRC-32 calculation. If an error occurs, an exception is thrown.

Parameters

[in,out]	cex	c-style exception
[in]	crc	`cgul_crc32_incr` instance

Returns: final crc value

Referenced by cgul_crc32_incr_cxx::crc().

§ cgul_crc32_incr__update_block()

CGUL_EXPORT void cgul_crc32_incr__update_block	(	cgul_exception_t *	cex,
		cgul_crc32_incr_t	crc,
		const void *	block,
		size_t	length
	)

This method updates the CRC by adding all the bytes in block to the calculation.

Parameters

[in]	cex	c-style exception
[in]	crc	`cgul_crc32_incr` instance
[in]	block	block of data to add to the crc
[in]	length	length of `block`

Referenced by cgul_crc32_incr_cxx::update_block().

§ cgul_crc32_incr__update_file()

CGUL_EXPORT void cgul_crc32_incr__update_file	(	cgul_exception_t *	cex,
		cgul_crc32_incr_t	crc,
		FILE *	f
	)

This method updates the CRC by adding all the bytes (starting at the current offset) in the file f to the calculation. If an error occurs, an exception is thrown.

Parameters

[in,out]	cex	c-style exception
[in]	crc	`cgul_crc32_incr` instance
[in]	f	input file

Referenced by cgul_crc32_incr_cxx::update_file().

§ cgul_crc32_incr__update_fname()

CGUL_EXPORT void cgul_crc32_incr__update_fname	(	cgul_exception_t *	cex,
		cgul_crc32_incr_t	crc,
		const char *	fname
	)

This method updates the CRC by adding all the bytes in the file with name fname to the calculation. If an error occurs, an exception is thrown.

Parameters

[in,out]	cex	c-style exception
[in]	crc	`cgul_crc32_incr` instance
[in]	fname	input file name

Referenced by cgul_crc32_incr_cxx::update_fname().

§ cgul_crc32_incr__reset()

CGUL_EXPORT void cgul_crc32_incr__reset	(	cgul_exception_t *	cex,
		cgul_crc32_incr_t	crc
	)

Reset to the initial internal state.

Parameters

[in]	cex	c-style exception
[in]	crc	`cgul_crc32_incr` instance

Referenced by cgul_crc32_incr_cxx::reset().

Typedefs

Functions

Detailed Description

Typedef Documentation

§ cgul_crc32_incr_t

Function Documentation

§ cgul_crc32_incr__new()

§ cgul_crc32_incr__new_appends_size()

§ cgul_crc32_incr__delete()

§ cgul_crc32_incr__assign()

§ cgul_crc32_incr__crc()

§ cgul_crc32_incr__update_block()

§ cgul_crc32_incr__update_file()

§ cgul_crc32_incr__update_fname()

§ cgul_crc32_incr__reset()