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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 * super_tone_tx.h - Flexible telephony supervisory tone generation.
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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) 2001 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: super_tone_tx.h,v 1.8 2006/10/24 13:45:28 steveu Exp $
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26 */
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27
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28 #if !defined(_SUPER_TONE_TX_H_)
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29 #define _SUPER_TONE_TX_H_
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30
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31 /*! \page super_tone_tx_page Supervisory tone generation
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32
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33 \section super_tone_tx_page_sec_1 What does it do?
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34
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35 The supervisory tone generator may be configured to generate most of the world's
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36 telephone supervisory tones - things like ringback, busy, number unobtainable,
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37 and so on. It uses tree structure tone descriptions, which can deal with quite
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38 complex cadence patterns.
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39
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40 \section super_tone_tx_page_sec_2 How does it work?
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41
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42 */
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43
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44 typedef struct super_tone_tx_step_s super_tone_tx_step_t;
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45
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46 typedef struct
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47 {
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48 int32_t phase_rate[2];
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49 float gain[2];
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50 uint32_t phase[2];
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51 int current_position;
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52 int level;
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53 super_tone_tx_step_t *levels[4];
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54 int cycles[4];
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55 } super_tone_tx_state_t;
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56
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57 struct super_tone_tx_step_s
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58 {
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59 int32_t phase_rate[2];
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60 float gain[2];
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61 int tone;
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62 int length;
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63 int cycles;
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64 super_tone_tx_step_t *next;
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65 super_tone_tx_step_t *nest;
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66 };
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67
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68 super_tone_tx_step_t *super_tone_tx_make_step(super_tone_tx_step_t *s,
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69 float f1,
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70 float l1,
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71 float f2,
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72 float l2,
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73 int length,
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74 int cycles);
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75
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76 void super_tone_tx_free(super_tone_tx_step_t *s);
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77
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78 /*! Initialise a supervisory tone generator.
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79 \brief Initialise a supervisory tone generator.
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80 \param s The supervisory tone generator context.
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81 \param tree The supervisory tone tree to be generated.
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82 \return The supervisory tone generator context. */
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83 super_tone_tx_state_t *super_tone_tx_init(super_tone_tx_state_t *s, super_tone_tx_step_t *tree);
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84
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85 /*! Generate a block of audio samples for a supervisory tone pattern.
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86 \brief Generate a block of audio samples for a supervisory tone pattern.
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87 \param tone The supervisory tone context.
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88 \param amp The audio sample buffer.
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89 \param max_samples The maximum number of samples to be generated.
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90 \return The number of samples generated. */
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91 int super_tone_tx(super_tone_tx_state_t *s, int16_t amp[], int max_samples);
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92
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93 #endif
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94 /*- End of file ------------------------------------------------------------*/
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