00001 /* 00002 * SpanDSP - a series of DSP components for telephony 00003 * 00004 * t38_gateway.h - A T.38, less the packet exchange part 00005 * 00006 * Written by Steve Underwood <steveu@coppice.org> 00007 * 00008 * Copyright (C) 2005, 2006, 2007 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: t38_gateway.h,v 1.41 2008/03/05 13:38:24 steveu Exp $ 00026 */ 00027 00028 /*! \file */ 00029 00030 #if !defined(_SPANDSP_T38_GATEWAY_H_) 00031 #define _SPANDSP_T38_GATEWAY_H_ 00032 00033 /*! \page t38_gateway_page T.38 real time FAX over IP PSTN gateway 00034 \section t38_gateway_page_sec_1 What does it do? 00035 00036 The T.38 gateway facility provides a robust interface between T.38 IP packet streams and 00037 and 8k samples/second audio streams. It provides the buffering and flow control features needed 00038 to maximum the tolerance of jitter and packet loss on the IP network. 00039 00040 \section t38_gateway_page_sec_2 How does it work? 00041 */ 00042 00043 #define T38_RX_BUF_LEN 2048 00044 #define T38_NON_ECM_TX_BUF_LEN 16384 00045 #define T38_TX_HDLC_BUFS 256 00046 /* Make sure the HDLC frame buffers are big enough for ECM frames. */ 00047 #define T38_MAX_HDLC_LEN 260 00048 00049 /*! 00050 T.38 gateway state. 00051 */ 00052 typedef struct 00053 { 00054 /*! Core T.38 support */ 00055 t38_core_state_t t38; 00056 00057 /*! \brief TRUE if ECM FAX mode is allowed through the gateway. */ 00058 int ecm_allowed; 00059 /*! \brief Use talker echo protection when transmitting. */ 00060 int use_tep; 00061 00062 /*! \brief If TRUE, transmit silence when there is nothing else to transmit. If FALSE return only 00063 the actual generated audio. Note that this only affects untimed silences. Timed silences 00064 (e.g. the 75ms silence between V.21 and a high speed modem) will alway be transmitted as 00065 silent audio. */ 00066 int transmit_on_idle; 00067 00068 /*! \brief A bit mask of the currently supported modem types. */ 00069 int supported_modems; 00070 00071 int suppress_nsx; 00072 00073 /*! \brief The number of pages for which a confirm (MCF) message was returned. */ 00074 int pages_confirmed; 00075 /*! \brief HDLC message buffers. */ 00076 uint8_t hdlc_buf[T38_TX_HDLC_BUFS][T38_MAX_HDLC_LEN]; 00077 /*! \brief HDLC message lengths. */ 00078 int hdlc_len[T38_TX_HDLC_BUFS]; 00079 /*! \brief HDLC message status flags. */ 00080 int hdlc_flags[T38_TX_HDLC_BUFS]; 00081 /*! \brief HDLC buffer contents. */ 00082 int hdlc_contents[T38_TX_HDLC_BUFS]; 00083 /*! \brief HDLC buffer number for input. */ 00084 int hdlc_in; 00085 /*! \brief HDLC buffer number for output. */ 00086 int hdlc_out; 00087 00088 /*! \brief Progressively calculated CRC for HDLC messaging received from a modem. */ 00089 uint16_t crc; 00090 00091 /*! \brief non-ECM and HDLC modem receive data buffer */ 00092 uint8_t rx_data[T38_RX_BUF_LEN]; 00093 int rx_data_ptr; 00094 00095 /*! \brief non-ECM modem transmit data buffer */ 00096 uint8_t non_ecm_tx_data[T38_NON_ECM_TX_BUF_LEN]; 00097 int non_ecm_tx_in_ptr; 00098 int non_ecm_tx_out_ptr; 00099 00100 /*! \brief The location of the most recent EOL marker in the non-ECM data buffer */ 00101 int non_ecm_tx_latest_eol_ptr; 00102 unsigned int non_ecm_bit_stream; 00103 /*! \brief The non-ECM flow control fill octet (0xFF before the first data, and 0x00 00104 once data has started). */ 00105 uint8_t non_ecm_flow_control_fill_octet; 00106 /*! \brief TRUE if we are in the initial all ones part of non-ECM transmission. */ 00107 int non_ecm_at_initial_all_ones; 00108 /*! \brief TRUE is the end of non-ECM data indication has been received. */ 00109 int non_ecm_data_finished; 00110 /*! \brief The current octet being sent as non-ECM data. */ 00111 unsigned int non_ecm_rx_bit_stream; 00112 unsigned int non_ecm_tx_octet; 00113 /*! \brief The current bit number in the current non-ECM octet. */ 00114 int non_ecm_bit_no; 00115 int non_ecm_in_octets; 00116 int non_ecm_out_octets; 00117 int non_ecm_in_rows; 00118 int non_ecm_out_rows; 00119 /*! \brief A count of the number of non-ECM fill octets generated for flow control control 00120 purposes. */ 00121 int non_ecm_flow_control_fill_octets; 00122 00123 /*! \brief the current class of field being received - i.e. none, non-ECM or HDLC */ 00124 int current_rx_field_class; 00125 /*! \brief The T.38 indicator currently in use */ 00126 int in_progress_rx_indicator; 00127 00128 /*! \brief The current T.38 data type being sent. */ 00129 int current_tx_data_type; 00130 00131 /*! \brief TRUE if we are in error correcting (ECM) mode */ 00132 int ecm_mode; 00133 /*! \brief The current bit rate for the fast modem. */ 00134 int fast_bit_rate; 00135 /*! \brief The current fast modem type. */ 00136 int fast_modem; 00137 /*! \brief TRUE if between DCS and TCF, and we want the fast image modem to 00138 start in the T.38 data at a predictable time from the end of the 00139 V.21 signal. */ 00140 int tcf_mode_predictable_modem_start; 00141 /*! \brief TRUE if a carrier is present. Otherwise FALSE. */ 00142 int rx_signal_present; 00143 /*! \brief TRUE if a modem has trained correctly. */ 00144 int rx_trained; 00145 00146 /*! \brief A tone generator context used to generate supervisory tones during 00147 FAX handling. */ 00148 tone_gen_state_t tone_gen; 00149 /*! \brief An HDLC context used when receiving HDLC messages. */ 00150 hdlc_rx_state_t hdlcrx; 00151 00152 /*! \brief HDLC data used when transmitting HDLC messages. */ 00153 hdlc_tx_state_t hdlctx; 00154 00155 /*! \brief A V.21 FSK modem context used when transmitting HDLC over V.21 00156 messages. */ 00157 fsk_tx_state_t v21_tx; 00158 /*! \brief A V.21 FSK modem context used when receiving HDLC over V.21 00159 messages. */ 00160 fsk_rx_state_t v21_rx; 00161 00162 /*! \brief A V.17 modem context used when sending FAXes at 7200bps, 9600bps 00163 12000bps or 14400bps*/ 00164 v17_tx_state_t v17_tx; 00165 /*! \brief A V.29 modem context used when receiving FAXes at 7200bps, 9600bps 00166 12000bps or 14400bps*/ 00167 v17_rx_state_t v17_rx; 00168 00169 /*! \brief A V.29 modem context used when sending FAXes at 7200bps or 00170 9600bps */ 00171 v29_tx_state_t v29_tx; 00172 /*! \brief A V.29 modem context used when receiving FAXes at 7200bps or 00173 9600bps */ 00174 v29_rx_state_t v29_rx; 00175 00176 /*! \brief A V.27ter modem context used when sending FAXes at 2400bps or 00177 4800bps */ 00178 v27ter_tx_state_t v27ter_tx; 00179 /*! \brief A V.27ter modem context used when receiving FAXes at 2400bps or 00180 4800bps */ 00181 v27ter_rx_state_t v27ter_rx; 00182 00183 /*! \brief */ 00184 dc_restore_state_t dc_restore; 00185 00186 /*! \brief Used to insert timed silences. */ 00187 silence_gen_state_t silence_gen; 00188 00189 /*! \brief The immediately active receive signal handler, which may hop between 00190 rx_handler and dummy_rx(). */ 00191 span_rx_handler_t *immediate_rx_handler; 00192 /*! \brief The current receive signal handler */ 00193 span_rx_handler_t *rx_handler; 00194 /*! \brief An opaque pointer, passed to rx_handler. */ 00195 void *rx_user_data; 00196 00197 /*! \brief The current transmit signal handler */ 00198 span_tx_handler_t *tx_handler; 00199 /*! \brief An opaque pointer, passed to tx_handler. */ 00200 void *tx_user_data; 00201 /*! \brief The transmit signal handler to be used when the current one has finished sending. */ 00202 span_tx_handler_t *next_tx_handler; 00203 /*! \brief An opaque pointer, passed to next_tx_handler. */ 00204 void *next_tx_user_data; 00205 00206 /*! \brief The number of octets to send in each image packet (non-ECM or ECM) at the current 00207 rate and the current specified packet interval. */ 00208 int octets_per_data_packet; 00209 00210 /*! \brief The type of fast receive modem currently active, which may be T38_NONE */ 00211 int fast_rx_active; 00212 /*! \brief The number of samples until the next timeout event */ 00213 int samples_to_timeout; 00214 /*! \brief TRUE if in image data mode (as opposed to TCF mode). */ 00215 int image_data_mode; 00216 /*! \brief TRUE if in image data modem is to use short training. */ 00217 int short_train; 00218 00219 /*! \brief TRUE if we need to corrupt the HDLC frame in progress, so the receiver cannot 00220 interpret it. */ 00221 int corrupt_the_frame_to_t38; 00222 /*! \brief TRUE if we need to corrupt the HDLC frame in progress, so the receiver cannot 00223 interpret it. */ 00224 int corrupt_the_frame_from_t38; 00225 00226 /*! \brief The currently select receiver type */ 00227 int current_rx_type; 00228 /*! \brief The currently select transmitter type */ 00229 int current_tx_type; 00230 00231 /*! \brief Audio logging file handles */ 00232 int fax_audio_rx_log; 00233 int fax_audio_tx_log; 00234 /*! \brief Error and flow logging control */ 00235 logging_state_t logging; 00236 } t38_gateway_state_t; 00237 00238 typedef struct 00239 { 00240 /*! \brief The current bit rate for image transfer. */ 00241 int bit_rate; 00242 /*! \brief TRUE if error correcting mode is used. */ 00243 int error_correcting_mode; 00244 /*! \brief The number of pages transferred so far. */ 00245 int pages_transferred; 00246 } t38_stats_t; 00247 00248 #if defined(__cplusplus) 00249 extern "C" 00250 { 00251 #endif 00252 00253 /*! \brief Initialise a gateway mode T.38 context. 00254 \param s The T.38 context. 00255 \param tx_packet_handler A callback routine to encapsulate and transmit T.38 packets. 00256 \param tx_packet_user_data An opaque pointer passed to the tx_packet_handler routine. 00257 \return A pointer to the termination mode T.38 context, or NULL if there was a problem. */ 00258 t38_gateway_state_t *t38_gateway_init(t38_gateway_state_t *s, 00259 t38_tx_packet_handler_t *tx_packet_handler, 00260 void *tx_packet_user_data); 00261 00262 /*! Free a gateway mode T.38 context. 00263 \brief Free a T.38 context. 00264 \param s The T.38 context. 00265 \return 0 for OK, else -1. */ 00266 int t38_gateway_free(t38_gateway_state_t *s); 00267 00268 /*! Process a block of received FAX audio samples. 00269 \brief Process a block of received FAX audio samples. 00270 \param s The T.38 context. 00271 \param amp The audio sample buffer. 00272 \param len The number of samples in the buffer. 00273 \return The number of samples unprocessed. */ 00274 int t38_gateway_rx(t38_gateway_state_t *s, int16_t amp[], int len); 00275 00276 /*! Generate a block of FAX audio samples. 00277 \brief Generate a block of FAX audio samples. 00278 \param s The T.38 context. 00279 \param amp The audio sample buffer. 00280 \param max_len The number of samples to be generated. 00281 \return The number of samples actually generated. 00282 */ 00283 int t38_gateway_tx(t38_gateway_state_t *s, int16_t amp[], int max_len); 00284 00285 /*! Control whether error correcting mode (ECM) is allowed. 00286 \brief Control whether error correcting mode (ECM) is allowed. 00287 \param s The T.38 context. 00288 \param ecm_allowed TRUE is ECM is to be allowed. 00289 */ 00290 void t38_gateway_set_ecm_capability(t38_gateway_state_t *s, int ecm_allowed); 00291 00292 /*! Select whether silent audio will be sent when transmit is idle. 00293 \brief Select whether silent audio will be sent when transmit is idle. 00294 \param s The T.38 context. 00295 \param transmit_on_idle TRUE if silent audio should be output when the FAX transmitter is 00296 idle. FALSE to transmit zero length audio when the FAX transmitter is idle. The default 00297 behaviour is FALSE. 00298 */ 00299 void t38_gateway_set_transmit_on_idle(t38_gateway_state_t *s, int transmit_on_idle); 00300 00301 /*! Specify which modem types are supported by a T.30 context. 00302 \brief Specify supported modems. 00303 \param s The T.38 context. 00304 \param supported_modems Bit field list of the supported modems. 00305 */ 00306 void t38_gateway_set_supported_modems(t38_gateway_state_t *s, int supported_modems); 00307 00308 /*! Select whether NSC, NSF, and NSS should be suppressed. It selected, the contents of 00309 these messages are forced to zero for all octets beyond the message type. This makes 00310 them look like manufacturer specific messages, from a manufacturer which does not exist. 00311 \brief Select whether NSC, NSF, and NSS should be suppressed. 00312 \param s The T.38 context. 00313 \param suppress_nsx TRUE if NSC, NSF, and NSS should be suppressed. 00314 */ 00315 void t38_gateway_set_nsx_suppression(t38_gateway_state_t *s, int suppress_nsx); 00316 00317 /*! Select whether talker echo protection tone will be sent for the image modems. 00318 \brief Select whether TEP will be sent for the image modems. 00319 \param s The T.38 context. 00320 \param use_tep TRUE if TEP should be sent. 00321 */ 00322 void t38_gateway_set_tep_mode(t38_gateway_state_t *s, int use_tep); 00323 00324 /*! Get the current transfer statistics for the current T.38 session. 00325 \brief Get the current transfer statistics. 00326 \param s The T.38 context. 00327 \param t A pointer to a buffer for the statistics. */ 00328 void t38_gateway_get_transfer_statistics(t38_gateway_state_t *s, t38_stats_t *t); 00329 00330 #if defined(__cplusplus) 00331 } 00332 #endif 00333 00334 #endif 00335 /*- End of file ------------------------------------------------------------*/