arq_protocol.c File Reference

#include "arq_protocol.h"
#include <string.h>
#include <stdio.h>
#include <stdatomic.h>
#include <math.h>
#include "../common/virtual_clock.h"
#include "../modem/freedv/freedv_api.h"
#include "../modem/modem_mfsk.h"
#include "../modem/framer.h"
#include "arq.h"

Include dependency graph for arq_protocol.c:

Functions
void	init_model (void)
int	arithmetic_encode (const char *msg, uint8_t *output)
int	arithmetic_decode (uint8_t *input, int max_len, char *output, int max_output)
const arq_mode_timing_t *	arq_protocol_mode_timing (int freedv_mode)
	Look up mode timing entry for a FreeDV mode.
float	arq_protocol_longest_burst_s (void)
	Longest single-burst airtime across the whole mode table, in seconds.
float	arq_protocol_call_interval_s (void)
	Return the CALL/ACCEPT retry interval in seconds, applying any CALLINT override.
float	arq_protocol_call_interval_for_mode_s (int mode)
int	arq_protocol_retry_rank (const char *local_call, const char *remote_call)
uint64_t	arq_protocol_retry_deadline_ms (float seconds, int rank)
int	arq_protocol_encode_hdr (uint8_t *buf, size_t buf_len, const arq_frame_hdr_t *hdr)
	Encode a parsed header into the first ARQ_FRAME_HDR_SIZE bytes of buf.
int	arq_protocol_decode_hdr (const uint8_t *buf, size_t buf_len, arq_frame_hdr_t *hdr)
	Decode the ARQ header from the first bytes of buf.
uint8_t	arq_protocol_bw_token_from_hz (int bw_hz)
	Map a configured bandwidth in Hz to an on-air BW token.
int	arq_protocol_bw_hz_from_token (uint8_t bw_token)
	Map an on-air BW token back to Hz.
uint8_t	arq_protocol_encode_snr (float snr_db)
	Encode a floating-point SNR (dB) into the snr_raw wire byte.
float	arq_protocol_decode_snr (uint8_t snr_raw)
	Decode snr_raw wire byte back to float dB.
int	arq_protocol_build_disconnect (uint8_t *buf, size_t buf_len, uint8_t session_id, uint8_t snr_raw)
	DISCONNECT frame (PACKET_TYPE_ARQ_CONTROL).
uint16_t	arq_protocol_callsign_crc16 (const char *callsign)
	Compute CRC16-CCITT of an uppercase-normalised callsign.
static int	encode_callsign_payload (const char *src, const char *dst, uint8_t *out, size_t out_cap)
static int	decode_callsign_payload (const uint8_t *in, size_t in_len, char *src_out, char *dst_out)
static int	encode_callsign_only_payload (const char *src, uint8_t *out, size_t out_cap)
static int	decode_callsign_only_payload (const uint8_t *in, size_t in_len, char *src_out)
static uint8_t	connect_ext (uint8_t bw_token)
static void	put_crc16 (uint8_t *p, uint16_t crc)
static uint16_t	get_crc16 (const uint8_t *p)
bool	arq_protocol_connect_version_ok (const uint8_t *buf, size_t buf_len)
	Is buf a CALL or ACCEPT of this protocol version?
static int	connect_bw_hz (const uint8_t *buf)
int	arq_protocol_build_call (uint8_t *buf, size_t buf_len, uint8_t session_id, const char *caller, const char *called, int bw_hz)
	Build a CALL.
int	arq_protocol_build_accept (uint8_t *buf, size_t buf_len, uint8_t session_id, const char *called, const char *caller, int bw_hz, int start_level, uint16_t nonce)
	Build an ACCEPT.
bool	arq_protocol_connect_dst_matches (const uint8_t *buf, const char *callsign)
	Is a CALL or ACCEPT addressed to callsign (bytes 2-3, all 16 bits)?
int	arq_protocol_parse_call (const uint8_t *buf, size_t buf_len, uint8_t *session_id_out, char *caller_out, int *bw_hz_out)
	Parse a CALL: session id, the caller's callsign, the bandwidth.
int	arq_protocol_parse_accept (const uint8_t *buf, size_t buf_len, arq_accept_t *out)
	Parse an ACCEPT.
int	arq_protocol_build_cq (uint8_t *buf, size_t buf_len, const char *src, int bw_hz)
	Build a compact DATAC16 CQ frame carrying source callsign and BW token.
int	arq_protocol_parse_cq (const uint8_t *buf, size_t buf_len, char *src_out, int *bw_hz_out)
	Parse a compact DATAC16 CQ frame.

Variables
_Atomic int	arq_call_retry_slots = ARQ_CALL_RETRY_SLOTS_DEFAULT
_Atomic int	arq_accept_retry_slots = ARQ_ACCEPT_RETRY_SLOTS_DEFAULT
_Atomic int	arq_disconnect_retry_slots = ARQ_DISCONNECT_RETRY_SLOTS_DEFAULT
_Atomic int	arq_retry_stagger_ms = ARQ_RETRY_STAGGER_MS_DEFAULT
_Atomic int	arq_disconnect_drain_timeout_s = ARQ_DISCONNECT_DRAIN_TIMEOUT_S_DEFAULT
const arq_mode_timing_t	arq_mode_table []
const int	arq_mode_table_count
_Atomic float	arq_callint_override_s = 0.0f

Function Documentation

arithmetic_decode()

int arithmetic_decode ( uint8_t *  input, int  max_len, char *  output, int  max_output  )

extern

arithmetic_encode()

int arithmetic_encode ( const char *  msg, uint8_t *  output  )

extern

arq_protocol_build_accept()

int arq_protocol_build_accept	(	uint8_t *	buf,
		size_t	buf_len,
		uint8_t	session_id,
		const char *	called,
		const char *	caller,
		int	bw_hz,
		int	start_level,
		uint16_t	nonce
	)

Build an ACCEPT.

called: the callsign the CALL was addressed to (the callee's primary or a secondary); start_level 0..6, or ARQ_ACCEPT_LEVEL_CTL_DEAF.

Returns

ARQ_CONTROL_FRAME_SIZE (14), or -1.

arq_protocol_build_call()

int arq_protocol_build_call	(	uint8_t *	buf,
		size_t	buf_len,
		uint8_t	session_id,
		const char *	caller,
		const char *	called,
		int	bw_hz
	)

Build a CALL.

Returns

ARQ_CONTROL_FRAME_SIZE (14), or -1.

arq_protocol_build_cq()

int arq_protocol_build_cq	(	uint8_t *	buf,
		size_t	buf_len,
		const char *	src,
		int	bw_hz
	)

Build a compact DATAC16 CQ frame carrying source callsign and BW token.

arq_protocol_build_disconnect()

int arq_protocol_build_disconnect	(	uint8_t *	buf,
		size_t	buf_len,
		uint8_t	session_id,
		uint8_t	snr_raw
	)

DISCONNECT frame (PACKET_TYPE_ARQ_CONTROL).

arq_protocol_bw_hz_from_token()

int arq_protocol_bw_hz_from_token

(

uint8_t

bw_token

)

Map an on-air BW token back to Hz.

Returns

500/2300/2750 on success, or 0 if the token is invalid.

arq_protocol_bw_token_from_hz()

uint8_t arq_protocol_bw_token_from_hz

(

int

bw_hz

)

Map a configured bandwidth in Hz to an on-air BW token.

Returns

ARQ_BW_TOKEN_* value, or ARQ_BW_TOKEN_NONE if unsupported.

arq_protocol_call_interval_for_mode_s()

float arq_protocol_call_interval_for_mode_s

(

int

mode

)

arq_protocol_call_interval_s()

float arq_protocol_call_interval_s

(

void

)

Return the CALL/ACCEPT retry interval in seconds, applying any CALLINT override.

Falls back to the DATAC16 table default (8.0s).

arq_protocol_callsign_crc16()

uint16_t arq_protocol_callsign_crc16

(

const char *

callsign

)

Compute CRC16-CCITT of an uppercase-normalised callsign.

Used to encode/validate the DST field in CALL/ACCEPT frames.

arq_protocol_connect_dst_matches()

bool arq_protocol_connect_dst_matches	(	const uint8_t *	buf,
		const char *	callsign
	)

Is a CALL or ACCEPT addressed to callsign (bytes 2-3, all 16 bits)?

arq_protocol_connect_version_ok()

bool arq_protocol_connect_version_ok	(	const uint8_t *	buf,
		size_t	buf_len
	)

Is buf a CALL or ACCEPT of this protocol version?

arq_protocol_decode_hdr()

int arq_protocol_decode_hdr	(	const uint8_t *	buf,
		size_t	buf_len,
		arq_frame_hdr_t *	hdr
	)

Decode the ARQ header from the first bytes of buf.

Returns

0 on success, -1 if buf too short.

arq_protocol_decode_snr()

float arq_protocol_decode_snr

(

uint8_t

snr_raw

)

Decode snr_raw wire byte back to float dB.

Returns

SNR in dB, or 0.0f if snr_raw == 0 (unknown).

arq_protocol_encode_hdr()

int arq_protocol_encode_hdr	(	uint8_t *	buf,
		size_t	buf_len,
		const arq_frame_hdr_t *	hdr
	)

Encode a parsed header into the first ARQ_FRAME_HDR_SIZE bytes of buf.

Returns

0 on success, -1 if buf_len < ARQ_FRAME_HDR_SIZE.

arq_protocol_encode_snr()

uint8_t arq_protocol_encode_snr

(

float

snr_db

)

Encode a floating-point SNR (dB) into the snr_raw wire byte.

Returns

Encoded byte (0 if snr_db is out of range or unknown).

arq_protocol_longest_burst_s()

float arq_protocol_longest_burst_s

(

void

)

Longest single-burst airtime across the whole mode table, in seconds.

The RX side must be able to hold a burst of ANY mode the peer might send, not just the one currently selected — the peer can change rung between our bursts, and the first frame of the new rung arrives before we know about it. Buffers sized from the active mode are therefore always one step behind.

arq_protocol_mode_timing()

const arq_mode_timing_t * arq_protocol_mode_timing

(

int

freedv_mode

)

Look up mode timing entry for a FreeDV mode.

Returns

Pointer to timing entry, or NULL if mode is unknown.

arq_protocol_parse_accept()

int arq_protocol_parse_accept	(	const uint8_t *	buf,
		size_t	buf_len,
		arq_accept_t *	out
	)

Parse an ACCEPT.

Returns

0, or -1 (wrong version, bad bandwidth token, a reserved bit set, a start rung off the ladder).

arq_protocol_parse_call()

int arq_protocol_parse_call	(	const uint8_t *	buf,
		size_t	buf_len,
		uint8_t *	session_id_out,
		char *	caller_out,
		int *	bw_hz_out
	)

Parse a CALL: session id, the caller's callsign, the bandwidth.

Returns

0, or -1 (wrong version, bad bandwidth token, undecodable call).

arq_protocol_parse_cq()

int arq_protocol_parse_cq	(	const uint8_t *	buf,
		size_t	buf_len,
		char *	src_out,
		int *	bw_hz_out
	)

Parse a compact DATAC16 CQ frame.

arq_protocol_retry_deadline_ms()

uint64_t arq_protocol_retry_deadline_ms	(	float	seconds,
		int	rank
	)

arq_protocol_retry_rank()

int arq_protocol_retry_rank	(	const char *	local_call,
		const char *	remote_call
	)

connect_bw_hz()

static int connect_bw_hz ( const uint8_t *  buf )

static

connect_ext()

static uint8_t connect_ext ( uint8_t  bw_token )

static

decode_callsign_only_payload()

static int decode_callsign_only_payload ( const uint8_t *  in, size_t  in_len, char *  src_out  )

static

decode_callsign_payload()

static int decode_callsign_payload ( const uint8_t *  in, size_t  in_len, char *  src_out, char *  dst_out  )

static

encode_callsign_only_payload()

static int encode_callsign_only_payload ( const char *  src, uint8_t *  out, size_t  out_cap  )

static

encode_callsign_payload()

static int encode_callsign_payload ( const char *  src, const char *  dst, uint8_t *  out, size_t  out_cap  )

static

get_crc16()

static uint16_t get_crc16 ( const uint8_t *  p )

static

init_model()

void init_model ( void  )

extern

put_crc16()

static void put_crc16 ( uint8_t *  p, uint16_t  crc  )

static

Variable Documentation

arq_accept_retry_slots

_Atomic int arq_accept_retry_slots = ARQ_ACCEPT_RETRY_SLOTS_DEFAULT

arq_call_retry_slots

_Atomic int arq_call_retry_slots = ARQ_CALL_RETRY_SLOTS_DEFAULT

arq_callint_override_s

_Atomic float arq_callint_override_s = 0.0f

arq_disconnect_drain_timeout_s

_Atomic int arq_disconnect_drain_timeout_s = ARQ_DISCONNECT_DRAIN_TIMEOUT_S_DEFAULT

arq_disconnect_retry_slots

_Atomic int arq_disconnect_retry_slots = ARQ_DISCONNECT_RETRY_SLOTS_DEFAULT

arq_mode_table

const arq_mode_timing_t arq_mode_table[]

Initial value:

= {
    
    {  FREEDV_MODE_DATAC16,   3.74f,     8.0f,           14   },
    {  FREEDV_MODE_DATAC15,   4.40f,     12.0f,          30   },
    {  FREEDV_MODE_DATAC4,    5.80f,     14.0f,          54   },
    {  FREEDV_MODE_DATAC3,    3.82f,     12.0f,          126  },
    {  FREEDV_MODE_DATAC1,    4.81f,     13.0f,          510  },
    {  FREEDV_MODE_DATAC17,   7.40f,     15.0f,          1180 },
    {  FREEDV_MODE_QAM16C2,   3.70f,     12.0f,          1213 },
    
    {  MERCURY_MODE_MFSK,     13.50f,    18.0f,          98   },
}

arq_mode_table_count

const int arq_mode_table_count

Initial value:

=
    (int)(sizeof(arq_mode_table) / sizeof(arq_mode_table[0]))

arq_retry_stagger_ms

_Atomic int arq_retry_stagger_ms = ARQ_RETRY_STAGGER_MS_DEFAULT