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1 /*
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2 * SpanDSP - a series of DSP components for telephony
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3 *
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4 * t31.h - A T.31 compatible class 1 FAX modem interface.
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5 *
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6 * Written by Steve Underwood <steveu@coppice.org>
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7 *
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8 * Copyright (C) 2004 Steve Underwood
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9 *
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10 * All rights reserved.
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11 *
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12 * This program is free software; you can redistribute it and/or modify
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13 * it under the terms of the GNU General Public License version 2, as
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14 * published by the Free Software Foundation.
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15 *
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16 * This program is distributed in the hope that it will be useful,
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17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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19 * GNU General Public License for more details.
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20 *
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21 * You should have received a copy of the GNU General Public License
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22 * along with this program; if not, write to the Free Software
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23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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24 *
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25 * $Id: t31.h,v 1.37 2006/10/24 13:45:28 steveu Exp $
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26 */
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27
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28 /*! \file */
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29
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30 #if !defined(_T31_H_)
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31 #define _T31_H_
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32
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33 /*! \page t31_page T.31 Class 1 FAX modem protocol handling
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34 \section t31_page_sec_1 What does it do?
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35 The T.31 class 1 FAX modem modules implements a class 1 interface to the FAX
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36 modems in spandsp.
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37
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38 \section t31_page_sec_2 How does it work?
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39 */
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40
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41 typedef struct t31_state_s t31_state_t;
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42
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43 typedef int (t31_modem_control_handler_t)(t31_state_t *s, void *user_data, int op, const char *num);
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44
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45 #define T31_TX_BUF_LEN (4096*32)
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46 #define T31_TX_BUF_HIGH_TIDE (4096*32 - 1024)
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47 #define T31_TX_BUF_LOW_TIDE (1024)
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48
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49 /*!
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50 T.31 descriptor. This defines the working state for a single instance of
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51 a T.31 FAX modem.
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52 */
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53 struct t31_state_s
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54 {
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55 at_state_t at_state;
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56 t31_modem_control_handler_t *modem_control_handler;
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57 void *modem_control_user_data;
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58
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59 /*! The current receive signal handler */
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60 span_rx_handler_t *rx_handler;
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61 void *rx_user_data;
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62
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63 /*! The current transmit signal handler */
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64 span_tx_handler_t *tx_handler;
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65 void *tx_user_data;
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66 /*! The transmit signal handler to be used when the current one has finished sending. */
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67 span_tx_handler_t *next_tx_handler;
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68 void *next_tx_user_data;
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69
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70 /*! If TRUE, transmit silence when there is nothing else to transmit. If FALSE return only
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71 the actual generated audio. Note that this only affects untimed silences. Timed silences
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72 (e.g. the 75ms silence between V.21 and a high speed modem) will alway be transmitted as
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73 silent audio. */
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74 int transmit_on_idle;
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75
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76 uint8_t hdlc_tx_buf[256];
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77 int hdlc_tx_len;
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78 int hdlc_tx_ptr;
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79 /*! TRUE if DLE prefix just used */
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80 int dled;
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81 uint8_t tx_data[T31_TX_BUF_LEN];
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82 /*! \brief The number of bytes stored in transmit buffer. */
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83 int tx_in_bytes;
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84 /*! \brief The number of bytes sent from the transmit buffer. */
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85 int tx_out_bytes;
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86 int tx_holding;
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87 int tx_data_started;
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88 int bit_no;
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89 int current_byte;
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90
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91 /*! \brief The current bit rate for the FAX fast message transfer modem. */
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92 int bit_rate;
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93 int rx_message_received;
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94
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95 /*! \brief A tone generator context used to generate supervisory tones during
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96 FAX handling. */
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97 tone_gen_state_t tone_gen;
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98 /*! \brief An HDLC context used when receiving HDLC over V.21 messages. */
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99 hdlc_rx_state_t hdlcrx;
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100 /*! \brief An HDLC context used when transmitting HDLC over V.21 messages. */
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101 hdlc_tx_state_t hdlctx;
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102 /*! \brief A V.21 FSK modem context used when transmitting HDLC over V.21
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103 messages. */
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104 fsk_tx_state_t v21tx;
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105 /*! \brief A V.21 FSK modem context used when receiving HDLC over V.21
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106 messages. */
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107 fsk_rx_state_t v21rx;
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108
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109 #if defined(ENABLE_V17)
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110 /*! \brief A V.17 modem context used when sending FAXes at 7200bps, 9600bps
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111 12000bps or 14400bps*/
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112 v17_tx_state_t v17tx;
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113 /*! \brief A V.29 modem context used when receiving FAXes at 7200bps, 9600bps
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114 12000bps or 14400bps*/
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115 v17_rx_state_t v17rx;
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116 #endif
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117
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118 /*! \brief A V.29 modem context used when sending FAXes at 7200bps or
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119 9600bps */
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120 v29_tx_state_t v29tx;
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121 /*! \brief A V.29 modem context used when receiving FAXes at 7200bps or
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122 9600bps */
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123 v29_rx_state_t v29rx;
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124
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125 /*! \brief A V.27ter modem context used when sending FAXes at 2400bps or
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126 4800bps */
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127 v27ter_tx_state_t v27ter_tx;
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128 /*! \brief A V.27ter modem context used when receiving FAXes at 2400bps or
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129 4800bps */
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130 v27ter_rx_state_t v27ter_rx;
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131
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132 /*! \brief Used to insert timed silences. */
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133 silence_gen_state_t silence_gen;
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134
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135 /*! \brief Rx power meter, use to detect silence */
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136 power_meter_t rx_power;
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137 int16_t last_sample;
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138 int32_t silence_threshold_power;
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139
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140 t38_core_state_t t38;
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141
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142 /*! \brief Samples of silence heard */
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143 int silence_heard;
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144 /*! \brief Samples of silence awaited */
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145 int silence_awaited;
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146 /*! \brief Samples elapsed in the current call */
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147 int64_t call_samples;
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148 int64_t dte_data_timeout;
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149 int modem;
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150 int short_train;
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151 int hdlc_final;
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152 int data_final;
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153 queue_t rx_queue;
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154
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155 uint8_t hdlc_rx_buf[256];
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156 int hdlc_rx_len;
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157
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158 int t38_mode;
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159 int timed_step;
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160 int current_tx_data;
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161 int64_t next_send_samples;
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162 int next_tx_indicator;
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163
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164 int current_rx_type;
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165 int current_tx_type;
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166
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167 /*! \brief TRUE is there has been some T.38 data missed */
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168 int missing_data;
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169
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170 int octets_per_non_ecm_packet;
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171
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172 /*! \brief Error and flow logging control */
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173 logging_state_t logging;
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174 };
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175
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176 #ifdef __cplusplus
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177 extern "C" {
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178 #endif
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179
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180 void t31_call_event(t31_state_t *s, int event);
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181
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182 int t31_at_rx(t31_state_t *s, const char *t, int len);
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183
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184 /*! Process a block of received T.31 modem audio samples.
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185 \brief Process a block of received T.31 modem audio samples.
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186 \param s The T.31 modem context.
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187 \param amp The audio sample buffer.
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188 \param len The number of samples in the buffer.
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189 \return The number of samples unprocessed. */
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190 int t31_rx(t31_state_t *s, int16_t amp[], int len);
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191
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192 /*! Generate a block of T.31 modem audio samples.
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193 \brief Generate a block of T.31 modem audio samples.
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194 \param s The T.31 modem context.
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195 \param amp The audio sample buffer.
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196 \param max_len The number of samples to be generated.
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197 \return The number of samples actually generated.
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198 */
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199 int t31_tx(t31_state_t *s, int16_t amp[], int max_len);
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200
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201 int t31_t38_send_timeout(t31_state_t *s, int samples);
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202
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203 /*! Select whether silent audio will be sent when transmit is idle.
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204 \brief Select whether silent audio will be sent when transmit is idle.
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205 \param s The T.31 modem context.
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206 \param transmit_on_idle TRUE if silent audio should be output when the transmitter is
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207 idle. FALSE to transmit zero length audio when the transmitter is idle. The default
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208 behaviour is FALSE.
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209 */
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210 void t31_set_transmit_on_idle(t31_state_t *s, int transmit_on_idle);
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211
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212 /*! Initialise a T.31 context. This must be called before the first
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213 use of the context, to initialise its contents.
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214 \brief Initialise a T.31 context.
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215 \param s The T.31 context.
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216 \param at_tx_handler A callback routine to handle AT interpreter channel output.
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217 \param at_tx_user_data An opaque pointer passed in called to at_tx_handler.
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218 \param modem_control_handler A callback routine to handle control of the modem (off-hook, etc).
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219 \param modem_control_user_data An opaque pointer passed in called to modem_control_handler.
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220 \param tx_t38_packet_handler ???
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221 \param tx_t38_packet_user_data ???
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222 \return A pointer to the T.31 context. */
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223 t31_state_t *t31_init(t31_state_t *s,
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224 at_tx_handler_t *at_tx_handler,
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225 void *at_tx_user_data,
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226 t31_modem_control_handler_t *modem_control_handler,
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227 void *modem_control_user_data,
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228 t38_tx_packet_handler_t *tx_t38_packet_handler,
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229 void *tx_t38_packet_user_data);
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230
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231 /*! Release a T.31 context.
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232 \brief Release a T.31 context.
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233 \param s The T.31 context.
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234 \return 0 for OK */
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235 int t31_release(t31_state_t *s);
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236
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237 #ifdef __cplusplus
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238 }
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239 #endif
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240
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241 #endif
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242 /*- End of file ------------------------------------------------------------*/
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