Mercurial > hg > audiostuff
diff spandsp-0.0.3/spandsp-0.0.3/src/spandsp/tone_generate.h @ 5:f762bf195c4b
import spandsp-0.0.3
author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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date | Fri, 25 Jun 2010 16:00:21 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/spandsp-0.0.3/spandsp-0.0.3/src/spandsp/tone_generate.h Fri Jun 25 16:00:21 2010 +0200 @@ -0,0 +1,145 @@ +/* + * SpanDSP - a series of DSP components for telephony + * + * tone_generate.h - General telephony tone generation, and specific + * generation of Bell MF, MFC/R2 and network supervisory tones. + * + * Written by Steve Underwood <steveu@coppice.org> + * + * Copyright (C) 2001 Steve Underwood + * + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2, as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * + * $Id: tone_generate.h,v 1.24 2006/11/24 12:34:55 steveu Exp $ + */ + +/*! \file */ + +#if !defined(_TONE_GENERATE_H_) +#define _TONE_GENERATE_H_ + +/*! \page tone_generation_page Tone generation +\section tone_generation_page_sec_1 What does it do? +The tone generation module provides for the generation of cadenced tones, +suitable for a wide range of telephony applications. + +\section tone_generation_page_sec_2 How does it work? +Oscillators are a problem. They oscillate due to instability, and yet we need +them to behave in a stable manner. A look around the web will reveal many papers +on this subject. Many describe rather complex solutions to the problem. However, +we are only concerned with telephony applications. It is possible to generate +the tones we need with a very simple efficient scheme. It is also practical to +use an exhaustive test to prove the oscillator is stable under all the +conditions in which we will use it. +*/ + +/*! + Cadenced dual tone generator descriptor. +*/ +typedef struct +{ + int32_t phase_rate[2]; + float gain[2]; + int modulate; + + int duration[4]; + + int repeat; +} tone_gen_descriptor_t; + +/*! + Cadenced dual tone generator state descriptor. This defines the state of + a single working instance of a generator. +*/ +typedef struct +{ + int32_t phase_rate[2]; + float gain[2]; + int modulate; + + uint32_t phase[2]; + + int duration[4]; + + int repeat; + + int current_section; + int current_position; +} tone_gen_state_t; + +typedef struct +{ + /*! First freq */ + int f1; + /*! Second freq. 0 for none. Negative for an AM modulation tone. */ + int f2; + /*! Level of the first freq (dBm0) */ + int8_t level1; + /*! Level of the second freq (dBm0), or % modulation for AM */ + int8_t level2; + /*! Tone on time (ms) */ + uint16_t on_time1; + /*! Minimum post tone silence (ms) */ + uint16_t off_time1; + /*! Tone on time (ms) */ + uint16_t on_time2; + /*! Minimum post tone silence (ms) */ + uint16_t off_time2; + /*! TRUE if cyclic tone, FALSE for one shot. */ + int8_t repeat; +} cadenced_tone_t; + +#ifdef __cplusplus +extern "C" { +#endif + +void make_tone_descriptor(tone_gen_descriptor_t *desc, cadenced_tone_t *tone); + +/*! Create a tone generator descriptor + \brief Create a tone generator descriptor + \param s The descriptor + \param f1 The first frequency, in Hz + \param l1 The level of the first frequency, in dBm0 + \param f2 0 for no second frequency, a positive number for the second frequency, + in Hz, or a negative number for an AM modulation frequency, in Hz + \param l2 The level of the second frequency, in dBm0, or the percentage modulation depth + for an AM modulated tone. + \param d1 x + \param d2 x + \param d3 x + \param d4 x + \param repeat x */ +void make_tone_gen_descriptor(tone_gen_descriptor_t *s, + int f1, + int l1, + int f2, + int l2, + int d1, + int d2, + int d3, + int d4, + int repeat); + +void tone_gen_init(tone_gen_state_t *s, tone_gen_descriptor_t *t); + +int tone_gen(tone_gen_state_t *s, int16_t amp[], int max_samples); + +#ifdef __cplusplus +} +#endif + +#endif +/*- End of file ------------------------------------------------------------*/