spandsp  3.0.0
private/t31.h
1 /*
2  * SpanDSP - a series of DSP components for telephony
3  *
4  * private/t31.h - A T.31 compatible class 1 FAX modem interface.
5  *
6  * Written by Steve Underwood <steveu@coppice.org>
7  *
8  * Copyright (C) 2004 Steve Underwood
9  *
10  * All rights reserved.
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU Lesser General Public License version 2.1,
14  * as published by the Free Software Foundation.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19  * GNU Lesser General Public License for more details.
20  *
21  * You should have received a copy of the GNU Lesser General Public
22  * License along with this program; if not, write to the Free Software
23  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24  */
25 
26 #if !defined(_SPANDSP_PRIVATE_T31_H_)
27 #define _SPANDSP_PRIVATE_T31_H_
28 
29 #define T31_TX_BUF_LEN (4096)
30 #define T31_TX_BUF_HIGH_TIDE (4096 - 1024)
31 #define T31_TX_BUF_LOW_TIDE (1024)
32 
33 #define T31_MAX_HDLC_LEN 284
34 /*! The maximum length of an HDLC frame buffer. This must be big enough for ECM frames. */
35 #define T31_T38_MAX_HDLC_LEN 260
36 /*! The number of HDLC transmit buffers */
37 #define T31_TX_HDLC_BUFS 256
38 
39 /*!
40  T.31 T.38 HDLC buffer.
41 */
42 typedef struct
43 {
44  /*! \brief HDLC message buffers. */
45  uint8_t buf[T31_MAX_HDLC_LEN];
46  /*! \brief HDLC message lengths. */
47  int16_t len;
49 
50 /*!
51  T.31 T.38 HDLC state.
52 */
53 typedef struct
54 {
55  /*! \brief HDLC message buffers. */
56  t31_hdlc_buf_t buf[T31_TX_HDLC_BUFS];
57  /*! \brief HDLC buffer number for input. */
58  int in;
59  /*! \brief HDLC buffer number for output. */
60  int out;
62 
63 /*!
64  Analogue FAX front end channel descriptor. This defines the state of a single working
65  instance of an analogue line FAX front end.
66 */
67 typedef struct
68 {
69  fax_modems_state_t modems;
70  v8_state_t v8;
71 
72  /*! The transmit signal handler to be used when the current one has finished sending. */
73  span_tx_handler_t next_tx_handler;
74  void *next_tx_user_data;
75 
76  /*! \brief No of data bits in current_byte. */
77  int bit_no;
78  /*! \brief The current data byte in progress. */
80 
81  /*! \brief Rx power meter, used to detect silence. */
83  /*! \brief Last sample, used for an elementary HPF for the power meter. */
84  int16_t last_sample;
85  /*! \brief The current silence threshold. */
87 
88  /*! \brief Samples of silence heard */
91 
92 /*!
93  Analogue FAX front end channel descriptor. This defines the state of a single working
94  instance of an analogue line FAX front end.
95 */
96 typedef struct
97 {
98  /*! \brief Core T.38 IFP support */
100 
101  /*! \brief The current transmit step being timed */
103 
104  /*! \brief True is there has been some T.38 data missed */
106 
107  /*! \brief The number of octets to send in each image packet (non-ECM or ECM) at the current
108  rate and the current specified packet interval. */
110 
111  /*! \brief An HDLC context used when sending HDLC messages to the terminal port
112  as if it were non-ECM data (ECM mode support). */
114  /*! \brief An HDLC context used when receiving HDLC messages from the terminal port.
115  as if it were non-ECM data (ECM mode support). */
117 
118  struct
119  {
120  uint8_t buf[T31_T38_MAX_HDLC_LEN];
121  int len;
122  } hdlc_rx;
123 
124  struct
125  {
126  /*! \brief The number of extra bits in a fully stuffed version of the
127  contents of the HDLC transmit buffer. This is needed to accurately
128  estimate the playout time for this frame, through an analogue modem. */
130  } hdlc_tx;
131 
132  t31_hdlc_state_t hdlc_from_t31;
133 
134  /*! \brief True if we are using ECM mode. This is used to select HDLC faking, which is
135  necessary with clunky class 1 modems. */
136  int ecm_mode;
137 
138  /*! \brief Counter for trailing non-ECM bytes, used to flush out the far end's modem. */
140 
141  /*! \brief The next queued tramsit indicator */
143  /*! \brief The current T.38 data type being transmitted */
145 
146  /*! \brief The current operating mode of the receiver. */
148  /*! \brief The current operating mode of the transmitter. */
150 
151  /*! \brief Current transmission bit rate. */
153  /*! \brief A "sample" count, used to time events. */
154  span_sample_timer_t samples;
155  /*! \brief The value for samples at the next transmission point. */
156  span_sample_timer_t next_tx_samples;
157  /*! \brief The current transmit timeout. */
158  span_sample_timer_t timeout_tx_samples;
159  /*! \brief The current receive timeout. */
160  span_sample_timer_t timeout_rx_samples;
162 
163 /*!
164  T.31 descriptor. This defines the working state for a single instance of
165  a T.31 FAX modem.
166 */
168 {
169  at_state_t at_state;
170  t31_modem_control_handler_t modem_control_handler;
171  void *modem_control_user_data;
172 
175 
176  /*! True if working in T.38 mode. */
177  bool t38_mode;
178 
179  /*! HDLC buffer, for composing an HDLC frame from the computer to the channel. */
180  struct
181  {
182  /*! \brief The HDLC transmit buffer. */
183  uint8_t buf[T31_MAX_HDLC_LEN];
184  int len;
185  int ptr;
186  /*! \brief True when the end of HDLC data from the computer has been detected. */
187  bool final;
188  } hdlc_tx;
189  /*! Buffer for data from the computer to the channel. */
190  struct
191  {
192  /*! \brief The transmit buffer. */
193  uint8_t buf[T31_TX_BUF_LEN];
194  /*! \brief The number of bytes stored in the transmit buffer. */
195  int in_bytes;
196  /*! \brief The number of bytes sent from the transmit buffer. */
198  /*! \brief True if the flow of real data has started. */
200  /*! \brief True if holding up further data into the buffer, for flow control. */
201  bool holding;
202  /*! \brief True when the end of non-ECM data from the computer has been detected. */
203  bool final;
204  } non_ecm_tx;
205 
206  /*! True if DLE prefix just used */
207  bool dled;
208 
209  /*! \brief Samples of silence awaited, as specified in a "wait for silence" command */
211 
212  /*! \brief The current bit rate for the FAX fast message transfer modem. */
213  int bit_rate;
214  /*! \brief True if a valid HDLC frame has been received in the current reception period. */
216 
217  /*! \brief Samples elapsed in the current call */
218  int64_t call_samples;
219  int64_t dte_data_timeout;
220 
221  /*! \brief The currently queued modem type. */
222  int modem;
223  /*! \brief True when short training mode has been selected by the computer. */
225  queue_state_t *rx_queue;
226 
227  /*! \brief Error and flow logging control */
229 };
230 
231 #endif
232 /*- End of file ------------------------------------------------------------*/
Definition: private/queue.h:33
int16_t len
HDLC message lengths.
Definition: private/t31.h:47
int extra_bits
The number of extra bits in a fully stuffed version of the contents of the HDLC transmit buffer...
Definition: private/t31.h:129
int in_bytes
The number of bytes stored in the transmit buffer.
Definition: private/t31.h:195
span_sample_timer_t timeout_rx_samples
The current receive timeout.
Definition: private/t31.h:160
Definition: private/power_meter.h:33
int silence_awaited
Samples of silence awaited, as specified in a "wait for silence" command.
Definition: private/t31.h:210
int tx_bit_rate
Current transmission bit rate.
Definition: private/t31.h:152
t38_core_state_t t38
Core T.38 IFP support.
Definition: private/t31.h:99
hdlc_rx_state_t hdlc_rx_non_ecm
An HDLC context used when receiving HDLC messages from the terminal port. as if it were non-ECM data ...
Definition: private/t31.h:116
int out_bytes
The number of bytes sent from the transmit buffer.
Definition: private/t31.h:197
int modem
The currently queued modem type.
Definition: private/t31.h:222
bool rx_data_missing
True is there has been some T.38 data missed.
Definition: private/t31.h:105
bool holding
True if holding up further data into the buffer, for flow control.
Definition: private/t31.h:201
span_sample_timer_t timeout_tx_samples
The current transmit timeout.
Definition: private/t31.h:158
Definition: private/hdlc.h:91
int octets_per_data_packet
The number of octets to send in each image packet (non-ECM or ECM) at the current rate and the curren...
Definition: private/t31.h:109
int current_byte
The current data byte in progress.
Definition: private/t31.h:79
int current_tx_data_type
The current T.38 data type being transmitted.
Definition: private/t31.h:144
Definition: private/t31.h:67
span_tx_handler_t next_tx_handler
Definition: private/t31.h:73
bool data_started
True if the flow of real data has started.
Definition: private/t31.h:199
bool short_train
True when short training mode has been selected by the computer.
Definition: private/t31.h:224
int current_rx_type
The current operating mode of the receiver.
Definition: private/t31.h:147
int bit_rate
The current bit rate for the FAX fast message transfer modem.
Definition: private/t31.h:213
int64_t call_samples
Samples elapsed in the current call.
Definition: private/t31.h:218
power_meter_t rx_power
Rx power meter, used to detect silence.
Definition: private/t31.h:82
Definition: private/t31.h:42
span_sample_timer_t next_tx_samples
The value for samples at the next transmission point.
Definition: private/t31.h:156
int timed_step
The current transmit step being timed.
Definition: private/t31.h:102
int current_tx_type
The current operating mode of the transmitter.
Definition: private/t31.h:149
uint8_t buf[284]
The HDLC transmit buffer.
Definition: private/t31.h:183
int non_ecm_trailer_bytes
Counter for trailing non-ECM bytes, used to flush out the far end&#39;s modem.
Definition: private/t31.h:139
bool rx_frame_received
True if a valid HDLC frame has been received in the current reception period.
Definition: private/t31.h:215
Definition: private/fax_modems.h:34
hdlc_tx_state_t hdlc_tx_non_ecm
An HDLC context used when sending HDLC messages to the terminal port as if it were non-ECM data (ECM ...
Definition: private/t31.h:113
bool dled
Definition: private/t31.h:207
logging_state_t logging
Error and flow logging control.
Definition: private/t31.h:228
Definition: private/t31.h:53
span_sample_timer_t samples
A "sample" count, used to time events.
Definition: private/t31.h:154
int16_t last_sample
Last sample, used for an elementary HPF for the power meter.
Definition: private/t31.h:84
int out
HDLC buffer number for output.
Definition: private/t31.h:60
int silence_heard
Samples of silence heard.
Definition: private/t31.h:89
Definition: private/logging.h:33
bool t38_mode
Definition: private/t31.h:177
int in
HDLC buffer number for input.
Definition: private/t31.h:58
int bit_no
No of data bits in current_byte.
Definition: private/t31.h:77
struct t31_state_s::@67 hdlc_tx
Definition: private/hdlc.h:32
Definition: private/t38_core.h:34
int32_t silence_threshold_power
The current silence threshold.
Definition: private/t31.h:86
int next_tx_indicator
The next queued tramsit indicator.
Definition: private/t31.h:142
Definition: private/t31.h:167
struct t31_state_s::@68 non_ecm_tx
int ecm_mode
True if we are using ECM mode. This is used to select HDLC faking, which is necessary with clunky cla...
Definition: private/t31.h:136
Definition: private/t31.h:96
Definition: private/at_interpreter.h:44
Definition: private/v8.h:29