hdlc.h File Reference

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Classes
struct	hdlc_rx_state_t
struct	hdlc_rx_stats_t
struct	hdlc_tx_state_t
Defines
#define	_HDLC_H_
#define	HDLC_MAXFRAME_LEN   400
Typedefs
typedef void(*)	hdlc_frame_handler_t (void *user_data, int ok, const uint8_t *pkt, int len)
typedef void(*)	hdlc_underflow_handler_t (void *user_data)
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.
hdlc_rx_state_t *	hdlc_rx_init (hdlc_rx_state_t *s, int crc32, int report_bad_frames, int framing_ok_threshold, hdlc_frame_handler_t handler, void *user_data)
	Initialise an HDLC receiver context.
int	hdlc_rx_get_stats (hdlc_rx_state_t *s, hdlc_rx_stats_t *t)
	Get the current receive statistics.
void	hdlc_rx_bit (hdlc_rx_state_t *s, int new_bit)
void	hdlc_rx_byte (hdlc_rx_state_t *s, int new_byte)
hdlc_tx_state_t *	hdlc_tx_init (hdlc_tx_state_t *s, int crc32, hdlc_underflow_handler_t handler, void *user_data)
	Initialise an HDLC transmitter context.
void	hdlc_tx_frame (hdlc_tx_state_t *s, const uint8_t *frame, int len)
void	hdlc_tx_preamble (hdlc_tx_state_t *s, int len)
int	hdlc_tx_getbit (hdlc_tx_state_t *s)
int	hdlc_tx_getbyte (hdlc_tx_state_t *s)

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Detailed Description

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Define Documentation

#define HDLC_MAXFRAME_LEN   400

HDLC_MAXFRAME_LEN is the maximum length of a stuffed HDLC frame, excluding the CRC.

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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.

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.

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.

int hdlc_rx_get_stats	(	hdlc_rx_state_t *	s,
		hdlc_rx_stats_t *	t
	)

Get the current receive statistics.

Parameters:

	s	A pointer to an HDLC receiver context.
	t	A pointer to the buffer for the statistics.

Returns:

0 for OK, else -1.

hdlc_rx_state_t* hdlc_rx_init	(	hdlc_rx_state_t *	s,
		int	crc32,
		int	report_bad_frames,
		int	framing_ok_threshold,
		hdlc_frame_handler_t	handler,
		void *	user_data
	)

Initialise an HDLC receiver context.

Parameters:

	s	A pointer to an HDLC receiver context.
	crc32	TRUE to use CRC32. FALSE to use CRC16.
	report_bad_frames	TRUE to request the reporting of bad frames.
	framing_ok_threshold	The number of flags needed to start the framing OK condition.
	handler	The function to be called when a good HDLC frame is received.
	user_data	An opaque parameter for the callback routine.

Returns:

A pointer to the HDLC receiver context.

hdlc_tx_state_t* hdlc_tx_init	(	hdlc_tx_state_t *	s,
		int	crc32,
		hdlc_underflow_handler_t	handler,
		void *	user_data
	)

Initialise an HDLC transmitter context.

Parameters:

	s	A pointer to an HDLC transmitter context.
	handler	The callback function called when the HDLC transmitter underflows.
	user_data	An opaque parameter for the callback routine.

Returns:

A pointer to the HDLC transmitter context.

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