t31.h

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00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * t31.h - A T.31 compatible class 1 FAX modem interface.
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2004 Steve Underwood
00009  *
00010  * All rights reserved.
00011  *
00012  * This program is free software; you can redistribute it and/or modify
00013  * it under the terms of the GNU Lesser General Public License version 2.1,
00014  * as published by the Free Software Foundation.
00015  *
00016  * This program is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  * GNU Lesser General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU Lesser General Public
00022  * License along with this program; if not, write to the Free Software
00023  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00024  *
00025  * $Id: t31.h,v 1.47 2008/04/17 14:27:00 steveu Exp $
00026  */
00027 
00028 /*! \file */
00029 
00030 #if !defined(_SPANDSP_T31_H_)
00031 #define _SPANDSP_T31_H_
00032 
00033 /*! \page t31_page T.31 Class 1 FAX modem protocol handling
00034 \section t31_page_sec_1 What does it do?
00035 The T.31 class 1 FAX modem modules implements a class 1 interface to the FAX
00036 modems in spandsp.
00037 
00038 \section t31_page_sec_2 How does it work?
00039 */
00040 
00041 typedef struct t31_state_s t31_state_t;
00042 
00043 typedef int (t31_modem_control_handler_t)(t31_state_t *s, void *user_data, int op, const char *num);
00044 
00045 #define T31_TX_BUF_LEN          (4096)
00046 #define T31_TX_BUF_HIGH_TIDE    (4096 - 1024)
00047 #define T31_TX_BUF_LOW_TIDE     (1024)
00048 
00049 /*!
00050     T.31 descriptor. This defines the working state for a single instance of
00051     a T.31 FAX modem.
00052 */
00053 struct t31_state_s
00054 {
00055     at_state_t at_state;
00056     t31_modem_control_handler_t *modem_control_handler;
00057     void *modem_control_user_data;
00058 
00059     /*! The current receive signal handler */
00060     span_rx_handler_t *rx_handler;
00061     void *rx_user_data;
00062 
00063     /*! The current transmit signal handler */
00064     span_tx_handler_t *tx_handler;
00065     void *tx_user_data;
00066     /*! The transmit signal handler to be used when the current one has finished sending. */
00067     span_tx_handler_t *next_tx_handler;
00068     void *next_tx_user_data;
00069 
00070     /*! If TRUE, transmit silence when there is nothing else to transmit. If FALSE return only
00071         the actual generated audio. Note that this only affects untimed silences. Timed silences
00072         (e.g. the 75ms silence between V.21 and a high speed modem) will alway be transmitted as
00073         silent audio. */
00074     int transmit_on_idle;
00075 
00076     /*! \brief Use talker echo protection when transmitting. */
00077     int use_tep;    
00078 
00079     uint8_t hdlc_tx_buf[256];
00080     int hdlc_tx_len;
00081     int hdlc_tx_ptr;
00082     /*! TRUE if DLE prefix just used */
00083     int dled;
00084     uint8_t tx_data[T31_TX_BUF_LEN];
00085     /*! \brief The number of bytes stored in transmit buffer. */
00086     int tx_in_bytes;
00087     /*! \brief The number of bytes sent from the transmit buffer. */
00088     int tx_out_bytes;
00089     int tx_holding;
00090     int tx_data_started;
00091     int bit_no;
00092     int current_byte;
00093 
00094     /*! \brief The current bit rate for the FAX fast message transfer modem. */
00095     int bit_rate;
00096     int rx_message_received;
00097 
00098     /*! \brief A tone generator context used to generate supervisory tones during
00099                FAX handling. */
00100     tone_gen_state_t tone_gen;
00101     /*! \brief An HDLC context used when receiving HDLC over V.21 messages. */
00102     hdlc_rx_state_t hdlcrx;
00103     /*! \brief An HDLC context used when transmitting HDLC over V.21 messages. */
00104     hdlc_tx_state_t hdlctx;
00105     /*! \brief A V.21 FSK modem context used when transmitting HDLC over V.21
00106                messages. */
00107     fsk_tx_state_t v21_tx;
00108     /*! \brief A V.21 FSK modem context used when receiving HDLC over V.21
00109                messages. */
00110     fsk_rx_state_t v21_rx;
00111 
00112     /*! \brief A V.17 modem context used when sending FAXes at 7200bps, 9600bps
00113                12000bps or 14400bps*/
00114     v17_tx_state_t v17_tx;
00115     /*! \brief A V.29 modem context used when receiving FAXes at 7200bps, 9600bps
00116                12000bps or 14400bps*/
00117     v17_rx_state_t v17_rx;
00118 
00119     /*! \brief A V.27ter modem context used when sending FAXes at 2400bps or
00120                4800bps */
00121     v27ter_tx_state_t v27ter_tx;
00122     /*! \brief A V.27ter modem context used when receiving FAXes at 2400bps or
00123                4800bps */
00124     v27ter_rx_state_t v27ter_rx;
00125 
00126     /*! \brief A V.29 modem context used when sending FAXes at 7200bps or
00127                9600bps */
00128     v29_tx_state_t v29_tx;
00129     /*! \brief A V.29 modem context used when receiving FAXes at 7200bps or
00130                9600bps */
00131     v29_rx_state_t v29_rx;
00132 
00133     /*! \brief Used to insert timed silences. */
00134     silence_gen_state_t silence_gen;
00135 
00136     /*! \brief Rx power meter, use to detect silence */
00137     power_meter_t rx_power;
00138     int16_t last_sample;
00139     int32_t silence_threshold_power;
00140     
00141     t38_core_state_t t38;
00142     int rx_signal_present;
00143     /*! \brief The next queued tramsit indicator */
00144     int next_tx_indicator;
00145     /*! \brief The current T.38 data type being transmitted */
00146     int current_tx_data_type;
00147 
00148     int ms_per_tx_chunk;
00149     int merge_tx_fields;
00150 
00151     /*! \brief The number of times an indicator packet will be sent. Numbers greater than one
00152                will increase reliability for UDP transmission. Zero is valid, to suppress all
00153                indicator packets for TCP transmission. */
00154     int indicator_tx_count;
00155 
00156     /*! \brief The number of times a data packet which ends transmission will be sent. Numbers
00157                greater than one will increase reliability for UDP transmission. Zero is not valid. */
00158     int data_end_tx_count;
00159 
00160     /*! \brief A "sample" count, used to time events */
00161     int32_t samples;
00162     int32_t next_tx_samples;
00163     int32_t timeout_rx_samples;
00164 
00165         /*! \brief Samples of silence heard */
00166     int silence_heard;
00167         /*! \brief Samples of silence awaited */
00168     int silence_awaited;
00169     /*! \brief Samples elapsed in the current call */
00170     int64_t call_samples;
00171     int64_t dte_data_timeout;
00172     int modem;
00173     int short_train;
00174     int hdlc_final;
00175     int data_final;
00176     queue_state_t *rx_queue;
00177 
00178     uint8_t hdlc_rx_buf[256];
00179     int hdlc_rx_len;
00180     
00181     int t38_mode;
00182     int timed_step;
00183     int current_tx_data;
00184 
00185     int current_rx_type;
00186     int current_tx_type;
00187 
00188     int trailer_bytes;
00189 
00190     /*! \brief TRUE is there has been some T.38 data missed */
00191     int missing_data;
00192 
00193     /*! \brief The number of octets to send in each image packet (non-ECM or ECM) at the current
00194                rate and the current specified packet interval. */
00195     int octets_per_data_packet;
00196 
00197     /*! \brief Error and flow logging control */
00198     logging_state_t logging;
00199 };
00200 
00201 #if defined(__cplusplus)
00202 extern "C"
00203 {
00204 #endif
00205 
00206 void t31_call_event(t31_state_t *s, int event);
00207 
00208 int t31_at_rx(t31_state_t *s, const char *t, int len);
00209 
00210 /*! Process a block of received T.31 modem audio samples.
00211     \brief Process a block of received T.31 modem audio samples.
00212     \param s The T.31 modem context.
00213     \param amp The audio sample buffer.
00214     \param len The number of samples in the buffer.
00215     \return The number of samples unprocessed. */
00216 int t31_rx(t31_state_t *s, int16_t amp[], int len);
00217 
00218 /*! Generate a block of T.31 modem audio samples.
00219     \brief Generate a block of T.31 modem audio samples.
00220     \param s The T.31 modem context.
00221     \param amp The audio sample buffer.
00222     \param max_len The number of samples to be generated.
00223     \return The number of samples actually generated.
00224 */
00225 int t31_tx(t31_state_t *s, int16_t amp[], int max_len);
00226 
00227 int t31_t38_send_timeout(t31_state_t *s, int samples);
00228 
00229 /*! Select whether silent audio will be sent when transmit is idle.
00230     \brief Select whether silent audio will be sent when transmit is idle.
00231     \param s The T.31 modem context.
00232     \param transmit_on_idle TRUE if silent audio should be output when the transmitter is
00233            idle. FALSE to transmit zero length audio when the transmitter is idle. The default
00234            behaviour is FALSE.
00235 */
00236 void t31_set_transmit_on_idle(t31_state_t *s, int transmit_on_idle);
00237 
00238 /*! Select whether TEP mode will be used (or time allowed for it (when transmitting).
00239     \brief Select whether TEP mode will be used.
00240     \param s The T.31 modem context.
00241     \param use_tep TRUE if TEP is to be ised.
00242 */
00243 void t31_set_tep_mode(t31_state_t *s, int use_tep);
00244 
00245 /*! Select whether T.38 data will be paced as it is transmitted.
00246     \brief Select whether T.38 data will be paced.
00247     \param s The T.31 modem context.
00248     \param without_pacing TRUE if data is to be sent as fast as possible. FALSE if it is
00249            to be paced.
00250 */
00251 void t31_set_t38_config(t31_state_t *s, int without_pacing);
00252 
00253 /*! Initialise a T.31 context. This must be called before the first
00254     use of the context, to initialise its contents.
00255     \brief Initialise a T.31 context.
00256     \param s The T.31 context.
00257     \param at_tx_handler A callback routine to handle AT interpreter channel output.
00258     \param at_tx_user_data An opaque pointer passed in called to at_tx_handler.
00259     \param modem_control_handler A callback routine to handle control of the modem (off-hook, etc).
00260     \param modem_control_user_data An opaque pointer passed in called to modem_control_handler.
00261     \param tx_t38_packet_handler ???
00262     \param tx_t38_packet_user_data ???
00263     \return A pointer to the T.31 context. */
00264 t31_state_t *t31_init(t31_state_t *s,
00265                       at_tx_handler_t *at_tx_handler,
00266                       void *at_tx_user_data,
00267                       t31_modem_control_handler_t *modem_control_handler,
00268                       void *modem_control_user_data,
00269                       t38_tx_packet_handler_t *tx_t38_packet_handler,
00270                       void *tx_t38_packet_user_data);
00271 
00272 /*! Release a T.31 context.
00273     \brief Release a T.31 context.
00274     \param s The T.31 context.
00275     \return 0 for OK */
00276 int t31_release(t31_state_t *s);
00277 
00278 #if defined(__cplusplus)
00279 }
00280 #endif
00281 
00282 #endif
00283 /*- End of file ------------------------------------------------------------*/

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