Cyclic Redundancy Check
[Utils]

This library is intended to calculate the crc for a data string. This library was developed by Lammert Bies and readapt to LAR purposes. This lib contains source code for functions to calculate five commonly used CRC values: CRC-16, CRC-32, CRC-DNP, CRC-SICK, CRC-Kermit and CRC-CCITT. To calculate a CRC, the following three steps must be followed: 1. Initialize the CRC value. For CRC-16, CRC-SICK CRC-Kermit and CRC-DNP the initial value of the CRC is 0. For CRC-CCITT and CRC-MODBUS, the value 0xffff is used. CRC-32 starts with an initial value of 0xffffffffL. 2. For each byte of the data starting with the first byte, call the function update_crc_16(), update_crc_32(), update_crc_dnp(), update_crc_sick(), update_crc_kermit() or update_crc_ccitt() to recalculate the value of the CRC. 3. Only for CRC-32: When all bytes have been processed, take the one's complement of the obtained CRC value. 4. Only for CRC-DNP: After all input processing, the one's complement of the CRC is calcluated and the two bytes of the CRC are swapped. 5. Only for CRC-Kermit and CRC-SICK: After all input processing, the one's complement of the CRC is calcluated and the two bytes of the CRC are swapped. More...

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Files
file	crc.h
	header for this library. Defines public funtions prototypes this library makes available to other modules.
Defines
#define	CRC_VERSION   "1.16"
#define	FALSE   0
#define	TRUE   1
Functions
unsigned short	update_crc_16 (unsigned short crc, char c)
unsigned long	update_crc_32 (unsigned long crc, char c)
unsigned short	update_crc_ccitt (unsigned short crc, unsigned char c)
unsigned short	update_crc_dnp (unsigned short crc, char c)
unsigned short	update_crc_kermit (unsigned short crc, char c)
unsigned short	update_crc_sick (unsigned short crc, char c, char prev_byte)

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Detailed Description

This library is intended to calculate the crc for a data string. This library was developed by Lammert Bies and readapt to LAR purposes. This lib contains source code for functions to calculate five commonly used CRC values: CRC-16, CRC-32, CRC-DNP, CRC-SICK, CRC-Kermit and CRC-CCITT. To calculate a CRC, the following three steps must be followed: 1. Initialize the CRC value. For CRC-16, CRC-SICK CRC-Kermit and CRC-DNP the initial value of the CRC is 0. For CRC-CCITT and CRC-MODBUS, the value 0xffff is used. CRC-32 starts with an initial value of 0xffffffffL. 2. For each byte of the data starting with the first byte, call the function update_crc_16(), update_crc_32(), update_crc_dnp(), update_crc_sick(), update_crc_kermit() or update_crc_ccitt() to recalculate the value of the CRC. 3. Only for CRC-32: When all bytes have been processed, take the one's complement of the obtained CRC value. 4. Only for CRC-DNP: After all input processing, the one's complement of the CRC is calcluated and the two bytes of the CRC are swapped. 5. Only for CRC-Kermit and CRC-SICK: After all input processing, the one's complement of the CRC is calcluated and the two bytes of the CRC are swapped.

Author:

dgameiro

Version:

1.0

Date:

27 April 2010

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Define Documentation

#define CRC_VERSION   "1.16"

Referenced by main().

#define FALSE   0

#define TRUE   1

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Function Documentation

unsigned short update_crc_16	(	unsigned short	crc,
		char	c
	)

References crc_tab16, crc_tab16_init, init_crc16_tab(), and tmp.

Referenced by main().

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unsigned long update_crc_32	(	unsigned long	crc,
		char	c
	)

References crc_tab32, crc_tab32_init, init_crc32_tab(), and tmp.

Referenced by main().

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unsigned short update_crc_ccitt	(	unsigned short	crc,
		unsigned char	c
	)

References crc_tabccitt, crc_tabccitt_init, init_crcccitt_tab(), and tmp.

Referenced by calc_crc_16(), and main().

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unsigned short update_crc_dnp	(	unsigned short	crc,
		char	c
	)

References crc_tabdnp, crc_tabdnp_init, init_crcdnp_tab(), and tmp.

Referenced by main().

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unsigned short update_crc_kermit	(	unsigned short	crc,
		char	c
	)

References crc_tabkermit, crc_tabkermit_init, init_crckermit_tab(), and tmp.

Referenced by main().

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unsigned short update_crc_sick	(	unsigned short	crc,
		char	c,
		char	prev_byte
	)

References P_SICK.

Referenced by main().

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