crc.c File Reference

#include <inttypes.h>
#include <stdio.h>
#include <string.h>
#include "spandsp/telephony.h"
#include "spandsp/crc.h"
#include "spandsp/bit_operations.h"

Functions
uint32_t	crc_itu32_calc (const uint8_t *buf, int len, uint32_t crc)
	Calculate the ITU/CCITT CRC-32 value in buffer.
int	crc_itu32_append (uint8_t *buf, int len)
	Append an ITU/CCITT CRC-32 value to a frame.
int	crc_itu32_check (const uint8_t *buf, int len)
	Check the ITU/CCITT CRC-32 value in a frame.
uint16_t	crc_itu16_calc (const uint8_t *buf, int len, uint16_t crc)
	Calculate the ITU/CCITT CRC-16 value in buffer.
int	crc_itu16_append (uint8_t *buf, int len)
	Append an ITU/CCITT CRC-16 value to a frame.
int	crc_itu16_check (const uint8_t *buf, int len)
	Check the ITU/CCITT CRC-16 value in a frame.

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Detailed Description

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Function Documentation

int crc_itu16_append	(	uint8_t *	buf,
		int	len
	)

Append an ITU/CCITT CRC-16 value to a frame.

Parameters:

	buf	The buffer containing the frame. This must be at least 2 bytes longer than the frame it contains, to allow room for the CRC value.
	len	The length of the frame.

Returns:

The new length of the frame.

uint16_t crc_itu16_calc	(	const uint8_t *	buf,
		int	len,
		uint16_t	crc
	)

Calculate the ITU/CCITT CRC-16 value in buffer.

Parameters:

	buf	The buffer containing the data.
	len	The length of the frame.
	crc	The initial CRC value. This is usually 0xFFFF, or 0 for a new block (it depends on the application). It is previous returned CRC value for the continuation of a block.

Returns:

The CRC value.

Referenced by adsi_tx_put_message(), and hdlc_tx_frame().

int crc_itu16_check	(	const uint8_t *	buf,
		int	len
	)

Check the ITU/CCITT CRC-16 value in a frame.

Parameters:

	buf	The buffer containing the frame.
	len	The length of the frame.

Returns:

TRUE if the CRC is OK, else FALSE.

int crc_itu32_append	(	uint8_t *	buf,
		int	len
	)

Append an ITU/CCITT CRC-32 value to a frame.

Parameters:

	buf	The buffer containing the frame. This must be at least 2 bytes longer than the frame it contains, to allow room for the CRC value.
	len	The length of the frame.

Returns:

The new length of the frame.

uint32_t crc_itu32_calc	(	const uint8_t *	buf,
		int	len,
		uint32_t	crc
	)

Calculate the ITU/CCITT CRC-32 value in buffer.

Parameters:

	buf	The buffer containing the data.
	len	The length of the frame.
	crc	The initial CRC value. This is usually 0xFFFFFFFF, or 0 for a new block (it depends on the application). It is previous returned CRC value for the continuation of a block.

Returns:

The CRC value.

Referenced by hdlc_tx_frame().

int crc_itu32_check	(	const uint8_t *	buf,
		int	len
	)

Check the ITU/CCITT CRC-32 value in a frame.

Parameters:

	buf	The buffer containing the frame.
	len	The length of the frame.

Returns:

TRUE if the CRC is OK, else FALSE.