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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 * sig_tone.h - Signalling tone processing for the 2280Hz, 2600Hz and similar
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5 * signalling tone used in older protocols.
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6 *
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7 * Written by Steve Underwood <steveu@coppice.org>
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8 *
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9 * Copyright (C) 2004 Steve Underwood
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10 *
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11 * All rights reserved.
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12 *
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13 * This program is free software; you can redistribute it and/or modify
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14 * it under the terms of the GNU General Public License version 2, as
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15 * published by the Free Software Foundation.
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16 *
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17 * This program is distributed in the hope that it will be useful,
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18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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20 * GNU General Public License for more details.
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21 *
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22 * You should have received a copy of the GNU General Public License
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23 * along with this program; if not, write to the Free Software
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24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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25 *
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26 * $Id: sig_tone.h,v 1.7 2006/10/24 13:22:02 steveu Exp $
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27 */
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28
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29 /*! \file */
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30
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31 /*! \page sig_tone_page The signaling tone processor
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32 \section sig_tone_sec_1 What does it do?
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33 The signaling tone processor handles the 2280Hz, 2400Hz and 2600Hz tones, used
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34 in many analogue signaling procotols, and digital ones derived from them.
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35
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36 \section sig_tone_sec_2 How does it work?
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37 TBD
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38 */
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39
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40 #if !defined(_SIG_TONE_H_)
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41 #define _SIG_TONE_H_
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42
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43 typedef int (*sig_tone_func_t)(void *user_data, int what);
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44
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45 /* The optional tone sets */
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46 enum
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47 {
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48 SIG_TONE_2280HZ = 1,
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49 SIG_TONE_2600HZ,
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50 SIG_TONE_2400HZ_2600HZ
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51 };
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52
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53 #define SIG_TONE_1_PRESENT 0x001
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54 #define SIG_TONE_1_CHANGE 0x002
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55 #define SIG_TONE_2_PRESENT 0x004
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56 #define SIG_TONE_2_CHANGE 0x008
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57 #define SIG_TONE_TX_PASSTHROUGH 0x010
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58 #define SIG_TONE_RX_PASSTHROUGH 0x020
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59 #define SIG_TONE_UPDATE_REQUEST 0x100
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60
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61 /*!
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62 Signaling tone descriptor. This defines the working state for a
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63 single instance of the transmit and receive sides of a signaling
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64 tone processor.
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65 */
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66 typedef struct
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67 {
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68 /*! \brief The tones used. */
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69 int tone_freq[2];
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70 /*! \brief The high and low tone amplitudes. */
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71 int tone_amp[2];
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72
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73 /*! \brief The delay, in audio samples, before the high level tone drops
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74 to a low level tone. */
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75 int high_low_timeout;
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76
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77 /*! \brief Some signaling tone detectors use a sharp initial filter,
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78 changing to a broader band filter after some delay. This
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79 parameter defines the delay. 0 means it never changes. */
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80 int sharp_flat_timeout;
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81
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82 /*! \brief Parameters to control the behaviour of the notch filter, used
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83 to remove the tone from the voice path in some protocols. */
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84 int notch_lag_time;
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85 int notch_allowed;
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86
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87 /*! \brief The tone on persistence check, in audio samples. */
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88 int tone_on_check_time;
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89 /*! \brief The tone off persistence check, in audio samples. */
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90 int tone_off_check_time;
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91
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92 /*! \brief The coefficients for the cascaded bi-quads notch filter. */
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93 int32_t notch_a1[3];
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94 int32_t notch_b1[3];
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95 int32_t notch_a2[3];
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96 int32_t notch_b2[3];
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97 int notch_postscale;
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98
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99 /*! \brief Flat mode bandpass bi-quad parameters */
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100 int32_t broad_a[3];
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101 int32_t broad_b[3];
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102 int broad_postscale;
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103
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104 /*! \brief The coefficients for the post notch leaky integrator. */
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105 int32_t notch_slugi;
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106 int32_t notch_slugp;
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107
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108 /*! \brief The coefficients for the post modulus leaky integrator in the
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109 unfiltered data path. The prescale value incorporates the
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110 detection ratio. This is called the guard ratio in some
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111 protocols. */
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112 int32_t unfiltered_slugi;
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113 int32_t unfiltered_slugp;
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114
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115 /*! \brief The coefficients for the post modulus leaky integrator in the
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116 bandpass filter data path. */
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117 int32_t broad_slugi;
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118 int32_t broad_slugp;
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119
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120 /*! \brief Masks which effectively threshold the notched, weighted and
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121 bandpassed data. */
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122 int32_t notch_threshold;
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123 int32_t unfiltered_threshold;
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124 int32_t broad_threshold;
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125 } sig_tone_descriptor_t;
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126
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127 typedef struct
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128 {
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129 /*! \brief The callback function used to handle signaling changes. */
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130 sig_tone_func_t sig_update;
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131 /*! \brief A user specified opaque pointer passed to the callback function. */
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132 void *user_data;
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133
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134 /*! \brief Transmit side parameters */
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135 sig_tone_descriptor_t *desc;
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136 int32_t phase_rate[2];
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137 int32_t tone_scaling[2];
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138 uint32_t phase_acc[2];
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139
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140 int high_low_timer;
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141
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142 /*! \brief The z's for the notch filter */
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143 int32_t notch_z1[3];
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144 int32_t notch_z2[3];
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145
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146 /*! \brief The z's for the weighting/bandpass filter. */
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147 int32_t broad_z[3];
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148
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149 /*! \brief The z's for the integrators. */
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150 int32_t notch_zl;
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151 int32_t broad_zl;
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152
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153 /*! \brief The thresholded data. */
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154 int32_t mown_notch;
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155 int32_t mown_bandpass;
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156
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157 int flat_mode;
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158 int tone_present;
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159 int notch_enabled;
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160 int flat_mode_timeout;
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161 int notch_insertion_timeout;
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162 int tone_persistence_timeout;
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163
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164 int current_tx_tone;
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165 int current_tx_timeout;
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166 int signaling_state_duration;
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167 } sig_tone_state_t;
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168
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169 /*! Initialise a signaling tone context.
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170 \brief Initialise a signaling tone context.
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171 \param s The signaling tone context.
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172 \param tone_type The type of signaling tone.
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173 \param sig_update Callback function to handle signaling updates.
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174 \param user_data An opaque pointer.
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175 \return A pointer to the signalling tone context, or NULL if there was a problem. */
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176 sig_tone_state_t *sig_tone_init(sig_tone_state_t *s, int tone_type, sig_tone_func_t sig_update, void *user_data);
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177
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178 /*! Process a block of received audio samples.
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179 \brief Process a block of received audio samples.
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180 \param s The signaling tone context.
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181 \param amp The audio sample buffer.
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182 \param len The number of samples in the buffer.
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183 \return The number of samples unprocessed. */
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184 int sig_tone_rx(sig_tone_state_t *s, int16_t amp[], int len);
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185
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186 /*! Generate a block of signaling tone audio samples.
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187 \brief Generate a block of signaling tone audio samples.
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188 \param s The signaling tone context.
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189 \param amp The audio sample buffer.
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190 \param len The number of samples to be generated.
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191 \return The number of samples actually generated. */
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192 int sig_tone_tx(sig_tone_state_t *s, int16_t amp[], int len);
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193
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194 #endif
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195 /*- End of file ------------------------------------------------------------*/
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