hdlc.c File Reference

#include <stdlib.h>
#include <inttypes.h>
#include <string.h>
#include <stdio.h>
#include "spandsp/telephony.h"
#include "spandsp/async.h"
#include "spandsp/crc.h"
#include "spandsp/bit_operations.h"
#include "spandsp/hdlc.h"
#include "spandsp/private/hdlc.h"

Functions
	SPAN_DECLARE_NONSTD (void)
void	hdlc_rx_set_max_frame_len (hdlc_rx_state_t *s, size_t max_len)
	Set the maximum frame length for an HDLC receiver context.
void	hdlc_rx_set_octet_counting_report_interval (hdlc_rx_state_t *s, int interval)
	Set the octet counting report interval.
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.
void	hdlc_rx_set_frame_handler (hdlc_rx_state_t *s, hdlc_frame_handler_t handler, void *user_data)
	Change the put_bit function associated with an HDLC receiver context.
void	hdlc_rx_set_status_handler (hdlc_rx_state_t *s, modem_rx_status_func_t handler, void *user_data)
	Change the status report function associated with an HDLC receiver context.
int	hdlc_rx_release (hdlc_rx_state_t *s)
	Release an HDLC receiver context.
int	hdlc_rx_free (hdlc_rx_state_t *s)
	Free an HDLC receiver context.
int	hdlc_rx_get_stats (hdlc_rx_state_t *s, hdlc_rx_stats_t *t)
	Get the current receive statistics.
int	hdlc_tx_frame (hdlc_tx_state_t *s, const uint8_t *frame, size_t len)
	Transmit a frame.
int	hdlc_tx_flags (hdlc_tx_state_t *s, int len)
	Transmit a specified quantity of flag octets, typically as a preamble.
int	hdlc_tx_abort (hdlc_tx_state_t *s)
	Send an abort.
int	hdlc_tx_corrupt_frame (hdlc_tx_state_t *s)
	Corrupt the frame currently being transmitted, by giving it the wrong CRC.
	SPAN_DECLARE_NONSTD (int)
	Get the next bit of a transmitted serial bit stream.
void	hdlc_tx_set_max_frame_len (hdlc_tx_state_t *s, size_t max_len)
	Set the maximum frame length for an HDLC transmitter context.
hdlc_tx_state_t *	hdlc_tx_init (hdlc_tx_state_t *s, int crc32, int inter_frame_flags, int progressive, hdlc_underflow_handler_t handler, void *user_data)
	Initialise an HDLC transmitter context.
int	hdlc_tx_release (hdlc_tx_state_t *s)
int	hdlc_tx_free (hdlc_tx_state_t *s)

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Detailed Description

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Function Documentation

int hdlc_rx_free

(

hdlc_rx_state_t *

s

)

Free an HDLC receiver context.

Free an HDLC receiver context.

Parameters:

s

A pointer to an HDLC receiver context.

Returns:

0 for OK

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 ITU CRC32. FALSE to use ITU CRC16.
	report_bad_frames	TRUE to request the reporting of bad frames.
	framing_ok_threshold	The number of back-to-back flags needed to start the framing OK condition. This may be used where a series of flag octets is used as a preamble, such as in the T.30 protocol.
	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.

int hdlc_rx_release

(

hdlc_rx_state_t *

s

)

Release an HDLC receiver context.

Release an HDLC receiver context.

Parameters:

s

A pointer to an HDLC receiver context.

Returns:

0 for OK

void hdlc_rx_set_frame_handler	(	hdlc_rx_state_t *	s,
		hdlc_frame_handler_t	handler,
		void *	user_data
	)

Change the put_bit function associated with an HDLC receiver context.

Change the put_bit function associated with an HDLC receiver context.

Parameters:

	s	A pointer to an HDLC receiver context.
	handler	The function to be called when a good HDLC frame is received.
	user_data	An opaque parameter for the callback routine.

void hdlc_rx_set_max_frame_len	(	hdlc_rx_state_t *	s,
		size_t	max_len
	)

Set the maximum frame length for an HDLC receiver context.

Parameters:

	s	A pointer to an HDLC receiver context.
	max_len	The maximum permitted length of a frame.

void hdlc_rx_set_octet_counting_report_interval	(	hdlc_rx_state_t *	s,
		int	interval
	)

Set the octet counting report interval.

Parameters:

	s	A pointer to an HDLC receiver context.
	interval	The interval, in octets.

void hdlc_rx_set_status_handler	(	hdlc_rx_state_t *	s,
		modem_rx_status_func_t	handler,
		void *	user_data
	)

Change the status report function associated with an HDLC receiver context.

Change the status report function associated with an HDLC receiver context.

Parameters:

	s	A pointer to an HDLC receiver context.
	handler	The callback routine used to report status changes.
	user_data	An opaque parameter for the callback routine.

int hdlc_tx_abort

(

hdlc_tx_state_t *

s

)

Send an abort.

Parameters:

s

A pointer to an HDLC transmitter context.

Returns:

0 if the frame was aborted, else -1.

int hdlc_tx_corrupt_frame

(

hdlc_tx_state_t *

s

)

Corrupt the frame currently being transmitted, by giving it the wrong CRC.

Parameters:

s

A pointer to an HDLC transmitter context.

Returns:

0 if the frame was corrupted, else -1.

References HDLC_MAXFRAME_LEN.

int hdlc_tx_flags	(	hdlc_tx_state_t *	s,
		int	len
	)

Transmit a specified quantity of flag octets, typically as a preamble.

Parameters:

	s	A pointer to an HDLC transmitter context.
	len	The length of the required period of flags, in flag octets. If len is zero this requests that HDLC transmission be terminated when the buffers have fully drained.

Returns:

0 if the flags were accepted for transmission, else -1.

int hdlc_tx_frame	(	hdlc_tx_state_t *	s,
		const uint8_t *	frame,
		size_t	len
	)

Transmit a frame.

Parameters:

	s	A pointer to an HDLC transmitter context.
	frame	A pointer to the frame to be transmitted.
	len	The length of the frame to be transmitted.

Returns:

0 if the frame was accepted for transmission, else -1.

References crc_itu16_calc(), crc_itu32_calc(), and HDLC_MAXFRAME_LEN.

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

Initialise an HDLC transmitter context.

Parameters:

	s	A pointer to an HDLC transmitter context.
	crc32	TRUE to use ITU CRC32. FALSE to use ITU CRC16.
	inter_frame_flags	The minimum flag octets to insert between frames (usually one).
	progressive	TRUE if frame creation works in progressive mode.
	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.

References HDLC_MAXFRAME_LEN.

void hdlc_tx_set_max_frame_len	(	hdlc_tx_state_t *	s,
		size_t	max_len
	)

Set the maximum frame length for an HDLC transmitter context.

Parameters:

	s	A pointer to an HDLC transmitter context.
	max_len	The maximum length.

References HDLC_MAXFRAME_LEN.

SPAN_DECLARE_NONSTD

(

int

)

Get the next bit of a transmitted serial bit stream.

Get the next bit of data from a T.38 rate adapting non-ECM buffer context.

Get a bit of received non-ECM image data.

Get the next bit of a transmitted serial bit stream.

Parameters:

user_data

An opaque point which must point to a transmitter context.

Returns:

the next bit, or PUTBIT_END_OF_DATA to indicate the data stream has ended.

Get the next bit of a transmitted serial bit stream.

Process a block of received V.8 audio samples.

Fake processing of a missing block of received V.29 modem audio samples.

Fake processing of a missing block of received V.27ter modem audio samples.

Generate a block of V.22bis modem audio samples.

Fake processing of a missing block of received V.22bis modem audio samples.

Process a block of received V.18 audio samples.

Fake processing of a missing block of received V.17 modem audio samples.

Generate a block of FAX audio samples.

Apply fake received audio processing.

Generate a block of T.31 modem audio samples.

Fake processing of a missing block of received T.31 modem audio samples.

Dummy receive fillin callback.

Dummy receive callback.

Process a block of samples through an instance of the modem connect tones detector.

Get the next sequence of bytes for transmission.

Get the next byte for transmission.

Fake processing of a missing block of received FSK modem audio samples.

Process a block of received FSK modem audio samples.

Apply T.30 transmit processing to generate a block of audio samples.

Apply fake T.30 receive processing when a block of audio samples is missing (e.g due to packet loss).

Parameters:

	s	The FAX context.
	len	The number of samples to fake.

Returns:

The number of samples unprocessed. This should only be non-zero if the software has reached the end of the FAX call.

Apply T.30 transmit processing to generate a block of audio samples.

Parameters:

	s	The FAX context.
	amp	The audio sample buffer.
	max_len	The number of samples to be generated.

Returns:

The number of samples actually generated. This will be zero when there is nothing to send.

Process a block of received FSK modem audio samples.

Parameters:

	s	The modem context.
	amp	The audio sample buffer.
	len	The number of samples in the buffer.

Returns:

The number of samples unprocessed.

Fake processing of a missing block of received FSK modem audio samples (e.g due to packet loss).

Parameters:

	s	The modem context.
	len	The number of samples to fake.

Returns:

The number of samples unprocessed.

Parameters:

s

A pointer to an HDLC transmitter context.

Returns:

The next byte for transmission.

Parameters:

	s	A pointer to an HDLC transmitter context.
	buf	The buffer for the data.
	max_len	The number of bytes to get.

Returns:

The number of bytes actually got.

Parameters:

	s	The context.
	amp	An array of signal samples.
	len	The number of samples in the array.

Returns:

The number of unprocessed samples.

A dummy routine to use as a receive callback, when we aren't really trying to process what is received. It just absorbs and ignores the data.

Parameters:

	user_data	The context.
	amp	The signal.buffer
	len	The length of the signal buffer

Returns:

0.

A dummy routine to use as a receive fillin callback, when we aren't really trying to process what is received. It just absorbs and ignores the request.

Parameters:

	user_data	The context.
	len	The length of the signal buffer

Returns:

0.

Fake processing of a missing block of received T.31 modem audio samples (e.g due to packet loss).

Parameters:

	s	The T.31 modem context.
	len	The number of samples to fake.

Returns:

The number of samples unprocessed.

Generate a block of T.31 modem audio samples.

Parameters:

	s	The T.31 modem context.
	amp	The audio sample buffer.
	max_len	The number of samples to be generated.

Returns:

The number of samples actually generated.

Apply fake processing when a block of audio samples is missing (e.g due to packet loss).

Parameters:

	s	The T.38 context.
	len	The number of samples to fake.

Returns:

The number of samples unprocessed. This should only be non-zero if the software has reached the end of the FAX call.

Generate a block of FAX audio samples.

Parameters:

	s	The T.38 context.
	amp	The audio sample buffer.
	max_len	The number of samples to be generated.

Returns:

The number of samples actually generated.

Fake processing of a missing block of received V.17 modem audio samples. (e.g due to packet loss).

Parameters:

	s	The modem context.
	len	The number of samples to fake.

Returns:

The number of samples unprocessed.

Process a block of received V.18 audio samples.

Parameters:

	s	The V.18 context.
	amp	The audio sample buffer.
	len	The number of samples in the buffer.

Fake processing of a missing block of received V.22bis modem audio samples. (e.g due to packet loss).

Parameters:

	s	The modem context.
	len	The number of samples to fake.

Returns:

The number of samples unprocessed.

Generate a block of V.22bis modem audio samples.

Parameters:

	s	The modem context.
	amp	The audio sample buffer.
	len	The number of samples to be generated.

Returns:

The number of samples actually generated.

Fake processing of a missing block of received V.27ter modem audio samples. (e.g due to packet loss).

Parameters:

	s	The modem context.
	len	The number of samples to fake.

Returns:

The number of samples unprocessed.

Fake processing of a missing block of received V.29 modem audio samples. (e.g due to packet loss).

Parameters:

	s	The modem context.
	len	The number of samples to fake.

Returns:

The number of samples unprocessed.

Process a block of received V.8 audio samples.

Parameters:

	s	The V.8 context.
	amp	The audio sample buffer.
	len	The number of samples in the buffer.

References SIG_STATUS_END_OF_DATA.