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 General Public License version 2, as
00014  * 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 General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU General Public License
00022  * 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 1.43 2007/05/15 13:22:43 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     uint8_t hdlc_tx_buf[256];
00077     int hdlc_tx_len;
00078     int hdlc_tx_ptr;
00079     /*! TRUE if DLE prefix just used */
00080     int dled;
00081     uint8_t tx_data[T31_TX_BUF_LEN];
00082     /*! \brief The number of bytes stored in transmit buffer. */
00083     int tx_in_bytes;
00084     /*! \brief The number of bytes sent from the transmit buffer. */
00085     int tx_out_bytes;
00086     int tx_holding;
00087     int tx_data_started;
00088     int bit_no;
00089     int current_byte;
00090 
00091     /*! \brief The current bit rate for the FAX fast message transfer modem. */
00092     int bit_rate;
00093     int rx_message_received;
00094 
00095     /*! \brief A tone generator context used to generate supervisory tones during
00096                FAX handling. */
00097     tone_gen_state_t tone_gen;
00098     /*! \brief An HDLC context used when receiving HDLC over V.21 messages. */
00099     hdlc_rx_state_t hdlcrx;
00100     /*! \brief An HDLC context used when transmitting HDLC over V.21 messages. */
00101     hdlc_tx_state_t hdlctx;
00102     /*! \brief A V.21 FSK modem context used when transmitting HDLC over V.21
00103                messages. */
00104     fsk_tx_state_t v21tx;
00105     /*! \brief A V.21 FSK modem context used when receiving HDLC over V.21
00106                messages. */
00107     fsk_rx_state_t v21rx;
00108 
00109     /*! \brief A V.17 modem context used when sending FAXes at 7200bps, 9600bps
00110                12000bps or 14400bps*/
00111     v17_tx_state_t v17tx;
00112     /*! \brief A V.29 modem context used when receiving FAXes at 7200bps, 9600bps
00113                12000bps or 14400bps*/
00114     v17_rx_state_t v17rx;
00115 
00116     /*! \brief A V.29 modem context used when sending FAXes at 7200bps or
00117                9600bps */
00118     v29_tx_state_t v29tx;
00119     /*! \brief A V.29 modem context used when receiving FAXes at 7200bps or
00120                9600bps */
00121     v29_rx_state_t v29rx;
00122 
00123     /*! \brief A V.27ter modem context used when sending FAXes at 2400bps or
00124                4800bps */
00125     v27ter_tx_state_t v27ter_tx;
00126     /*! \brief A V.27ter modem context used when receiving FAXes at 2400bps or
00127                4800bps */
00128     v27ter_rx_state_t v27ter_rx;
00129 
00130     /*! \brief Used to insert timed silences. */
00131     silence_gen_state_t silence_gen;
00132 
00133     /*! \brief Rx power meter, use to detect silence */
00134     power_meter_t rx_power;
00135     int16_t last_sample;
00136     int32_t silence_threshold_power;
00137     
00138     t38_core_state_t t38;
00139 
00140         /*! \brief Samples of silence heard */
00141     int silence_heard;
00142         /*! \brief Samples of silence awaited */
00143     int silence_awaited;
00144     /*! \brief Samples elapsed in the current call */
00145     int64_t call_samples;
00146     int64_t dte_data_timeout;
00147     int modem;
00148     int short_train;
00149     int hdlc_final;
00150     int data_final;
00151     queue_state_t *rx_queue;
00152 
00153     uint8_t hdlc_rx_buf[256];
00154     int hdlc_rx_len;
00155     
00156     int t38_mode;
00157     int timed_step;
00158     int current_tx_data;
00159     int64_t next_send_samples;
00160     int next_tx_indicator;
00161 
00162     int current_rx_type;
00163     int current_tx_type;
00164 
00165     /*! \brief TRUE is there has been some T.38 data missed */
00166     int missing_data;
00167 
00168     int octets_per_non_ecm_packet;
00169 
00170     /*! \brief Error and flow logging control */
00171     logging_state_t logging;
00172 };
00173 
00174 #if defined(__cplusplus)
00175 extern "C"
00176 {
00177 #endif
00178 
00179 void t31_call_event(t31_state_t *s, int event);
00180 
00181 int t31_at_rx(t31_state_t *s, const char *t, int len);
00182 
00183 /*! Process a block of received T.31 modem audio samples.
00184     \brief Process a block of received T.31 modem audio samples.
00185     \param s The T.31 modem context.
00186     \param amp The audio sample buffer.
00187     \param len The number of samples in the buffer.
00188     \return The number of samples unprocessed. */
00189 int t31_rx(t31_state_t *s, int16_t amp[], int len);
00190 
00191 /*! Generate a block of T.31 modem audio samples.
00192     \brief Generate a block of T.31 modem audio samples.
00193     \param s The T.31 modem context.
00194     \param amp The audio sample buffer.
00195     \param max_len The number of samples to be generated.
00196     \return The number of samples actually generated.
00197 */
00198 int t31_tx(t31_state_t *s, int16_t amp[], int max_len);
00199 
00200 int t31_t38_send_timeout(t31_state_t *s, int samples);
00201 
00202 /*! Select whether silent audio will be sent when transmit is idle.
00203     \brief Select whether silent audio will be sent when transmit is idle.
00204     \param s The T.31 modem context.
00205     \param transmit_on_idle TRUE if silent audio should be output when the transmitter is
00206            idle. FALSE to transmit zero length audio when the transmitter is idle. The default
00207            behaviour is FALSE.
00208 */
00209 void t31_set_transmit_on_idle(t31_state_t *s, int transmit_on_idle);
00210 
00211 /*! Initialise a T.31 context. This must be called before the first
00212     use of the context, to initialise its contents.
00213     \brief Initialise a T.31 context.
00214     \param s The T.31 context.
00215     \param at_tx_handler A callback routine to handle AT interpreter channel output.
00216     \param at_tx_user_data An opaque pointer passed in called to at_tx_handler.
00217     \param modem_control_handler A callback routine to handle control of the modem (off-hook, etc).
00218     \param modem_control_user_data An opaque pointer passed in called to modem_control_handler.
00219     \param tx_t38_packet_handler ???
00220     \param tx_t38_packet_user_data ???
00221     \return A pointer to the T.31 context. */
00222 t31_state_t *t31_init(t31_state_t *s,
00223                       at_tx_handler_t *at_tx_handler,
00224                       void *at_tx_user_data,
00225                       t31_modem_control_handler_t *modem_control_handler,
00226                       void *modem_control_user_data,
00227                       t38_tx_packet_handler_t *tx_t38_packet_handler,
00228                       void *tx_t38_packet_user_data);
00229 
00230 /*! Release a T.31 context.
00231     \brief Release a T.31 context.
00232     \param s The T.31 context.
00233     \return 0 for OK */
00234 int t31_release(t31_state_t *s);
00235 
00236 #if defined(__cplusplus)
00237 }
00238 #endif
00239 
00240 #endif
00241 /*- End of file ------------------------------------------------------------*/

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