t38_gateway.c File Reference
`#include <inttypes.h>`
`#include <stdlib.h>`
`#include <stdio.h>`
`#include <fcntl.h>`
`#include <time.h>`
`#include <string.h>`
`#include "floating_fudge.h"`
`#include <assert.h>`
`#include <tiffio.h>`
`#include "spandsp/telephony.h"`
`#include "spandsp/logging.h"`
`#include "spandsp/queue.h"`
`#include "spandsp/dc_restore.h"`
`#include "spandsp/bit_operations.h"`
`#include "spandsp/power_meter.h"`
`#include "spandsp/complex.h"`
`#include "spandsp/tone_detect.h"`
`#include "spandsp/tone_generate.h"`
`#include "spandsp/async.h"`
`#include "spandsp/crc.h"`
`#include "spandsp/hdlc.h"`
`#include "spandsp/silence_gen.h"`
`#include "spandsp/fsk.h"`
`#include "spandsp/v29tx.h"`
`#include "spandsp/v29rx.h"`
`#include "spandsp/v27ter_tx.h"`
`#include "spandsp/v27ter_rx.h"`
`#include "spandsp/v17tx.h"`
`#include "spandsp/v17rx.h"`
`#include "spandsp/super_tone_rx.h"`
`#include "spandsp/modem_connect_tones.h"`
`#include "spandsp/timezone.h"`
`#include "spandsp/t4_rx.h"`
`#include "spandsp/t4_tx.h"`
`#include "spandsp/t4_t6_decode.h"`
`#include "spandsp/t4_t6_encode.h"`
`#include "spandsp/t30_fcf.h"`
`#include "spandsp/t35.h"`
`#include "spandsp/t30.h"`
`#include "spandsp/t30_logging.h"`
`#include "spandsp/fax_modems.h"`
`#include "spandsp/t38_core.h"`
`#include "spandsp/t38_non_ecm_buffer.h"`
`#include "spandsp/t38_gateway.h"`
`#include "spandsp/private/logging.h"`
`#include "spandsp/private/silence_gen.h"`
`#include "spandsp/private/fsk.h"`
`#include "spandsp/private/v17tx.h"`
`#include "spandsp/private/v17rx.h"`
`#include "spandsp/private/v27ter_tx.h"`
`#include "spandsp/private/v27ter_rx.h"`
`#include "spandsp/private/v29tx.h"`
`#include "spandsp/private/v29rx.h"`
`#include "spandsp/private/modem_connect_tones.h"`
`#include "spandsp/private/hdlc.h"`
`#include "spandsp/private/fax_modems.h"`
`#include "spandsp/private/timezone.h"`
`#include "spandsp/private/t4_t6_decode.h"`
`#include "spandsp/private/t4_t6_encode.h"`
`#include "spandsp/private/t4_rx.h"`
`#include "spandsp/private/t4_tx.h"`
`#include "spandsp/private/t30.h"`
`#include "spandsp/private/t38_core.h"`
`#include "spandsp/private/t38_non_ecm_buffer.h"`
`#include "spandsp/private/t38_gateway.h"`

## Macros

#define | DEFAULT_MS_PER_TX_CHUNK 30
#define | HDLC_START_BUFFER_LEVEL 8
#define | INDICATOR_TX_COUNT 3
#define | DATA_TX_COUNT 1
#define | DATA_END_TX_COUNT 3
#define | MAX_NSX_SUPPRESSION 10
#define | HDLC_FRAMING_OK_THRESHOLD 5

## Enumerations

enum | { DISBIT1 = 0x01 , DISBIT2 = 0x02 , DISBIT3 = 0x04 , DISBIT4 = 0x08 , DISBIT5 = 0x10 , DISBIT6 = 0x20 , DISBIT7 = 0x40 , DISBIT8 = 0x80 }
enum | { HDLC_FLAG_FINISHED = 0x01 , HDLC_FLAG_CORRUPT_CRC = 0x02 , HDLC_FLAG_PROCEED_WITH_OUTPUT = 0x04 , HDLC_FLAG_MISSING_DATA = 0x08 }
enum | { FLAG_INDICATOR = 0x100 , FLAG_DATA = 0x200 }
enum | { TIMED_MODE_STARTUP = 0 , TIMED_MODE_IDLE , TIMED_MODE_TCF_PREDICTABLE_MODEM_START_FAST_MODEM_ANNOUNCED , TIMED_MODE_TCF_PREDICTABLE_MODEM_START_FAST_MODEM_SEEN , TIMED_MODE_TCF_PREDICTABLE_MODEM_START_PAST_V21_MODEM , TIMED_MODE_TCF_PREDICTABLE_MODEM_START_BEGIN }

## Functions

int | t38_gateway_rx (t38_gateway_state_t *s, int16_t amp[], int len)
int | t38_gateway_rx_fillin (t38_gateway_state_t *s, int len)
int | t38_gateway_tx (t38_gateway_state_t *s, int16_t amp[], int max_len)
void | t38_gateway_get_transfer_statistics (t38_gateway_state_t *s, t38_stats_t *t)
| Get the current transfer statistics.
t38_core_state_t * | t38_gateway_get_t38_core_state (t38_gateway_state_t *s)
| Get a pointer to the T.38 core IFP packet engine associated with a T.38 context.
logging_state_t * | t38_gateway_get_logging_state (t38_gateway_state_t *s)
| Get a pointer to the logging context associated with a T.38 context.
void | t38_gateway_set_ecm_capability (t38_gateway_state_t *s, int ecm_allowed)
| Control whether error correcting mode (ECM) is allowed.
void | t38_gateway_set_transmit_on_idle (t38_gateway_state_t *s, int transmit_on_idle)
| Select whether silent audio will be sent when transmit is idle.
void | t38_gateway_set_supported_modems (t38_gateway_state_t *s, int supported_modems)
| Specify supported modems.
void | t38_gateway_set_nsx_suppression (t38_gateway_state_t *s, const uint8_t *from_t38, int from_t38_len, const uint8_t *from_modem, int from_modem_len)
| Select whether NSC, NSF, and NSS should be suppressed.
void | t38_gateway_set_tep_mode (t38_gateway_state_t *s, int use_tep)
| Select whether TEP will be sent for the image modems.
void | t38_gateway_set_fill_bit_removal (t38_gateway_state_t *s, int remove)
| Select whether non-ECM fill bits are to be removed during transmission.
void | t38_gateway_set_real_time_frame_handler (t38_gateway_state_t *s, t38_gateway_real_time_frame_handler_t *handler, void *user_data)
| Set a callback function for T.30 frame exchange monitoring.
t38_gateway_state_t * | t38_gateway_init (t38_gateway_state_t *s, t38_tx_packet_handler_t *tx_packet_handler, void *tx_packet_user_data)
| Initialise a gateway mode T.38 context.
int | t38_gateway_release (t38_gateway_state_t *s)
| Release a T.38 context.
int | t38_gateway_free (t38_gateway_state_t *s)
| Free a T.38 context.

## Macro Definition Documentation

## DATA_END_TX_COUNT

#define DATA_END_TX_COUNT 3

The number of transmissions of terminating data IFP packets

## DATA_TX_COUNT

#define DATA_TX_COUNT 1

The number of transmissions of data IFP packets

## DEFAULT_MS_PER_TX_CHUNK

#define DEFAULT_MS_PER_TX_CHUNK 30

The default number of milliseconds per transmitted IFP when sending bulk T.38 data

## HDLC_FRAMING_OK_THRESHOLD

#define HDLC_FRAMING_OK_THRESHOLD 5

The number of consecutive flags to declare HDLC framing is OK.

## HDLC_START_BUFFER_LEVEL

#define HDLC_START_BUFFER_LEVEL 8

The number of bytes which must be in the audio to T.38 HDLC buffer before we start outputting them as IFP messages.

## INDICATOR_TX_COUNT

#define INDICATOR_TX_COUNT 3

The number of transmissions of indicator IFP packets

## MAX_NSX_SUPPRESSION

#define MAX_NSX_SUPPRESSION 10

The maximum number of bytes to be zapped, in order to corrupt NSF, NSS and NSC messages, so the receiver does not recognise them.

Referenced by t38_gateway_set_nsx_suppression().

## Function Documentation

## t38_gateway_free()

int t38_gateway_free | ( | t38_gateway_state_t * | s | ) |

Free a T.38 context.

Free a gateway mode T.38 context.

Parameters

  s | The T.38 context.

Returns
  0 for OK, else -1.

## t38_gateway_get_logging_state()

logging_state_t * t38_gateway_get_logging_state | ( | t38_gateway_state_t * | s | ) |

Get a pointer to the logging context associated with a T.38 context.

Get a pointer to the logging context associated with a T.38 context.

Parameters

  s | The T.38 context.

Returns
  A pointer to the logging context, or NULL.

References t38_gateway_state_s::logging.

## t38_gateway_get_t38_core_state()

t38_core_state_t * t38_gateway_get_t38_core_state | ( | t38_gateway_state_t * | s | ) |

Get a pointer to the T.38 core IFP packet engine associated with a T.38 context.

Get a pointer to the T.38 core IFP packet engine associated with a gateway mode T.38 context.

Parameters

  s | The T.38 context.

Returns
  A pointer to the T.38 core context, or NULL.

References t38_gateway_t38_state_t::t38, and t38_gateway_state_s::t38x.

## t38_gateway_get_transfer_statistics()

void t38_gateway_get_transfer_statistics | ( | t38_gateway_state_t * | s,
|  | t38_stats_t * | t )

Get the current transfer statistics.

Get the current transfer statistics for the current T.38 session.

Parameters

  s | The T.38 context.
  t | A pointer to a buffer for the statistics.

References t38_stats_t::bit_rate, t38_gateway_state_s::core, t38_gateway_core_state_t::ecm_mode, t38_stats_t::error_correcting_mode, t38_gateway_core_state_t::fast_bit_rate, t38_gateway_core_state_t::pages_confirmed, and t38_stats_t::pages_transferred.

## t38_gateway_init()

t38_gateway_state_t * t38_gateway_init | ( | t38_gateway_state_t * | s,
|  | t38_tx_packet_handler_t * | tx_packet_handler,
|  | void * | tx_packet_user_data )

Initialise a gateway mode T.38 context.

Parameters

  s | The T.38 context.
  tx_packet_handler | A callback routine to encapsulate and transmit T.38 packets.
  tx_packet_user_data | An opaque pointer passed to the tx_packet_handler routine.

Returns
  A pointer to the termination mode T.38 context, or NULL if there was a problem.

References t38_gateway_state_s::audio, fax_modems_state_s::audio_rx_log, fax_modems_state_s::audio_tx_log, t38_gateway_state_s::core, t38_gateway_core_state_t::ecm_allowed, t38_gateway_state_s::logging, t38_gateway_audio_state_t::modems, t38_gateway_core_state_t::non_ecm_to_modem, t38_gateway_to_t38_state_t::octets_per_data_packet, t38_gateway_core_state_t::samples_to_timeout, T30_SUPPORT_V17, T30_SUPPORT_V27TER, T30_SUPPORT_V29, t38_gateway_set_nsx_suppression(), t38_gateway_set_supported_modems(), t38_non_ecm_buffer_init(), t38_gateway_core_state_t::timed_mode, and t38_gateway_core_state_t::to_t38.

## t38_gateway_release()

int t38_gateway_release | ( | t38_gateway_state_t * | s | ) |

Release a T.38 context.

Release a gateway mode T.38 context.

Parameters

  s | The T.38 context.

Returns
  0 for OK, else -1.

## t38_gateway_set_ecm_capability()

void t38_gateway_set_ecm_capability | ( | t38_gateway_state_t * | s,
|  | int | ecm_allowed )

Control whether error correcting mode (ECM) is allowed.

Control whether error correcting mode (ECM) is allowed.

Parameters

  s | The T.38 context.
  ecm_allowed | TRUE is ECM is to be allowed.

References t38_gateway_state_s::core, and t38_gateway_core_state_t::ecm_allowed.

## t38_gateway_set_fill_bit_removal()

void t38_gateway_set_fill_bit_removal | ( | t38_gateway_state_t * | s,
|  | int | remove )

Select whether non-ECM fill bits are to be removed during transmission.

Select whether non-ECM fill bits are to be removed during transmission.

Parameters

  s | The T.38 context.
  remove | TRUE if fill bits are to be removed.

References t38_gateway_state_s::core, t38_gateway_to_t38_state_t::fill_bit_removal, and t38_gateway_core_state_t::to_t38.

## t38_gateway_set_nsx_suppression()

void t38_gateway_set_nsx_suppression | ( | t38_gateway_state_t * | s,
|  | const uint8_t * | from_t38,
|  | int | from_t38_len,
|  | const uint8_t * | from_modem,
|  | int | from_modem_len )

Select whether NSC, NSF, and NSS should be suppressed.

Select whether NSC, NSF, and NSS should be suppressed. It selected, the contents of these messages are forced to zero for all octets beyond the message type. This makes them look like manufacturer specific messages, from a manufacturer which does not exist.

Parameters

  s | The T.38 context.
  from_t38 | A string of bytes to overwrite the header of any NSC, NSF, and NSS frames passing through the gateway from T.38 the the modem.
  from_t38_len | The length of the overwrite string.
  from_modem | A string of bytes to overwrite the header of any NSC, NSF, and NSS frames passing through the gateway from the modem to T.38.
  from_modem_len | The length of the overwrite string.

References MAX_NSX_SUPPRESSION, t38_gateway_t38_state_t::suppress_nsx_len, and t38_gateway_state_s::t38x.

Referenced by t38_gateway_init().

## t38_gateway_set_real_time_frame_handler()

void t38_gateway_set_real_time_frame_handler | ( | t38_gateway_state_t * | s,
|  | t38_gateway_real_time_frame_handler_t * | handler,
|  | void * | user_data )

Set a callback function for T.30 frame exchange monitoring.

Set a callback function for T.30 frame exchange monitoring. This is called from the heart of the signal processing, so don't take too long in the handler routine.

Parameters

  s | The T.30 context.
  handler | The callback function.
  user_data | An opaque pointer passed to the callback function.

References t38_gateway_state_s::core, t38_gateway_core_state_t::real_time_frame_handler, and t38_gateway_core_state_t::real_time_frame_user_data.

## t38_gateway_set_supported_modems()

void t38_gateway_set_supported_modems | ( | t38_gateway_state_t * | s,
|  | int | supported_modems )

Specify supported modems.

Specify which modem types are supported by a T.30 context.

Parameters

  s | The T.38 context.
  supported_modems | Bit field list of the supported modems.

References t38_gateway_state_s::core, t38_gateway_core_state_t::supported_modems, T30_SUPPORT_V17, T30_SUPPORT_V29, t38_gateway_t38_state_t::t38, and t38_gateway_state_s::t38x.

Referenced by t38_gateway_init().

## t38_gateway_set_tep_mode()

void t38_gateway_set_tep_mode | ( | t38_gateway_state_t * | s,
|  | int | use_tep )

Select whether TEP will be sent for the image modems.

Select whether talker echo protection tone will be sent for the image modems.

Parameters

  s | The T.38 context.
  use_tep | TRUE if TEP should be sent.

References t38_gateway_state_s::audio, t38_gateway_audio_state_t::modems, and fax_modems_state_s::use_tep.

## t38_gateway_set_transmit_on_idle()

void t38_gateway_set_transmit_on_idle | ( | t38_gateway_state_t * | s,
|  | int | transmit_on_idle )

Select whether silent audio will be sent when transmit is idle.

Select whether silent audio will be sent when transmit is idle.

Parameters

  s | The T.38 context.
  transmit_on_idle | TRUE if silent audio should be output when the FAX transmitter is idle. FALSE to transmit zero length audio when the FAX transmitter is idle. The default behaviour is FALSE.

References t38_gateway_state_s::audio, t38_gateway_audio_state_t::modems, and fax_modems_state_s::transmit_on_idle.