private/t31.h

00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * private/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 1.7 2009/02/12 12:38:39 steveu Exp $
00026  */
00027 
00028 #if !defined(_SPANDSP_PRIVATE_T31_H_)
00029 #define _SPANDSP_PRIVATE_T31_H_
00030 
00031 /*!
00032     Analogue FAX front end channel descriptor. This defines the state of a single working
00033     instance of an analogue line FAX front end.
00034 */
00035 typedef struct
00036 {
00037     fax_modems_state_t modems;
00038 
00039     /*! The transmit signal handler to be used when the current one has finished sending. */
00040     span_tx_handler_t *next_tx_handler;
00041     void *next_tx_user_data;
00042 
00043     /*! \brief No of data bits in current_byte. */
00044     int bit_no;
00045     /*! \brief The current data byte in progress. */
00046     int current_byte;
00047 
00048     /*! \brief Rx power meter, used to detect silence. */
00049     power_meter_t rx_power;
00050     /*! \brief Last sample, used for an elementary HPF for the power meter. */
00051     int16_t last_sample;
00052     /*! \brief The current silence threshold. */
00053     int32_t silence_threshold_power;
00054 
00055     /*! \brief Samples of silence heard */
00056     int silence_heard;
00057 } t31_audio_front_end_state_t;
00058 
00059 /*!
00060     Analogue FAX front end channel descriptor. This defines the state of a single working
00061     instance of an analogue line FAX front end.
00062 */
00063 typedef struct
00064 {
00065     /*! \brief Internet Aware FAX mode bit mask. */
00066     int iaf;
00067     /*! \brief Required time between T.38 transmissions, in ms. */
00068     int ms_per_tx_chunk;
00069     /*! \brief Bit fields controlling the way data is packed into chunked for transmission. */
00070     int chunking_modes;
00071 
00072     /*! \brief Core T.38 IFP support */
00073     t38_core_state_t t38;
00074 
00075     /*! \brief The current transmit step being timed */
00076     int timed_step;
00077 
00078     /*! \brief TRUE is there has been some T.38 data missed */
00079     int rx_data_missing;
00080 
00081     /*! \brief The number of octets to send in each image packet (non-ECM or ECM) at the current
00082                rate and the current specified packet interval. */
00083     int octets_per_data_packet;
00084 
00085     /*! \brief An HDLC context used when sending HDLC messages to the terminal port
00086                (ECM mode support). */
00087     hdlc_tx_state_t hdlc_tx_term;
00088     /*! \brief An HDLC context used when receiving HDLC messages from the terminal port.
00089                (ECM mode support). */
00090     hdlc_rx_state_t hdlc_rx_term;
00091 
00092     struct
00093     {
00094         uint8_t buf[T31_T38_MAX_HDLC_LEN];
00095         int len;
00096     } hdlc_rx;
00097 
00098     struct
00099     {
00100         /*! \brief The number of extra bits in a fully stuffed version of the
00101                    contents of the HDLC transmit buffer. This is needed to accurately
00102                    estimate the playout time for this frame, through an analogue modem. */
00103         int extra_bits;
00104     } hdlc_tx;
00105 
00106     /*! \brief TRUE if we are using ECM mode. This is used to select HDLC faking, necessary
00107                with clunky class 1 modems. */
00108     int ecm_mode;
00109 
00110     /*! \brief Counter for trailing non-ECM bytes, used to flush out the far end's modem. */
00111     int non_ecm_trailer_bytes;
00112 
00113     /*! \brief The next queued tramsit indicator */
00114     int next_tx_indicator;
00115     /*! \brief The current T.38 data type being transmitted */
00116     int current_tx_data_type;
00117 
00118     /*! \brief The current operating mode of the receiver. */
00119     int current_rx_type;
00120     /*! \brief The current operating mode of the transmitter. */
00121     int current_tx_type;
00122 
00123     /*! \brief Current transmission bit rate. */
00124     int tx_bit_rate;
00125     /*! \brief A "sample" count, used to time events. */
00126     int32_t samples;
00127     /*! \brief The value for samples at the next transmission point. */
00128     int32_t next_tx_samples;
00129     /*! \brief The current receive timeout. */
00130     int32_t timeout_rx_samples;
00131 } t31_t38_front_end_state_t;
00132 
00133 /*!
00134     T.31 descriptor. This defines the working state for a single instance of
00135     a T.31 FAX modem.
00136 */
00137 struct t31_state_s
00138 {
00139     at_state_t at_state;
00140     t31_modem_control_handler_t *modem_control_handler;
00141     void *modem_control_user_data;
00142 
00143     t31_audio_front_end_state_t audio;
00144     t31_t38_front_end_state_t t38_fe;
00145     /*! TRUE if working in T.38 mode. */
00146     int t38_mode;
00147 
00148     /*! HDLC buffer, for composing an HDLC frame from the computer to the channel. */
00149     struct
00150     {
00151         uint8_t buf[T31_MAX_HDLC_LEN];
00152         int len;
00153         int ptr;
00154         /*! \brief TRUE when the end of HDLC data from the computer has been detected. */
00155         int final;
00156     } hdlc_tx;
00157     /*! Buffer for data from the computer to the channel. */
00158     struct
00159     {
00160         uint8_t data[T31_TX_BUF_LEN];
00161         /*! \brief The number of bytes stored in transmit buffer. */
00162         int in_bytes;
00163         /*! \brief The number of bytes sent from the transmit buffer. */
00164         int out_bytes;
00165         /*! \brief TRUE if the flow of real data has started. */
00166         int data_started;
00167         /*! \brief TRUE if holding up further data into the buffer, for flow control. */
00168         int holding;
00169         /*! \brief TRUE when the end of non-ECM data from the computer has been detected. */
00170         int final;
00171     } tx;
00172 
00173     /*! TRUE if DLE prefix just used */
00174     int dled;
00175 
00176         /*! \brief Samples of silence awaited, as specified in a "wait for silence" command */
00177     int silence_awaited;
00178 
00179     /*! \brief The current bit rate for the FAX fast message transfer modem. */
00180     int bit_rate;
00181     /*! \brief TRUE if a valid HDLC frame has been received in the current reception period. */
00182     int rx_frame_received;
00183 
00184     /*! \brief Samples elapsed in the current call */
00185     int64_t call_samples;
00186     int64_t dte_data_timeout;
00187 
00188     /*! \brief The currently queued modem type. */
00189     int modem;
00190     /*! \brief TRUE when short training mode has been selected by the computer. */
00191     int short_train;
00192     queue_state_t *rx_queue;
00193 
00194     /*! \brief Error and flow logging control */
00195     logging_state_t logging;
00196 };
00197 
00198 #endif
00199 /*- End of file ------------------------------------------------------------*/

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