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comparison spandsp-0.0.3/spandsp-0.0.3/src/spandsp/tone_detect.h @ 5:f762bf195c4b

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import spandsp-0.0.3
author Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date Fri, 25 Jun 2010 16:00:21 +0200
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4:26cd8f1ef0b1 5:f762bf195c4b
1 /*
2 * SpanDSP - a series of DSP components for telephony
3 *
4 * tone_detect.h - General telephony tone detection, and specific
5 * detection of Bell MF, and MFC/R2.
6 *
7 * Written by Steve Underwood <steveu@coppice.org>
8 *
9 * Copyright (C) 2001, 2005 Steve Underwood
10 *
11 * All rights reserved.
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License version 2, as
15 * published by the Free Software Foundation.
16 *
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
25 *
26 * $Id: tone_detect.h,v 1.27 2006/10/24 13:45:28 steveu Exp $
27 */
28
29 #if !defined(_TONE_DETECT_H_)
30 #define _TONE_DETECT_H_
31
32 /*!
33 Floating point Goertzel filter descriptor.
34 */
35 typedef struct
36 {
37 float fac;
38 int samples;
39 } goertzel_descriptor_t;
40
41 /*!
42 Floating point Goertzel filter state descriptor.
43 */
44 typedef struct
45 {
46 float v2;
47 float v3;
48 float fac;
49 int samples;
50 int current_sample;
51 } goertzel_state_t;
52
53 #ifdef __cplusplus
54 extern "C" {
55 #endif
56
57 /*! \brief Create a descriptor for use with either a Goertzel transform */
58 void make_goertzel_descriptor(goertzel_descriptor_t *t,
59 float freq,
60 int samples);
61
62 /*! \brief Initialise the state of a Goertzel transform.
63 \param s The Goertzel context. If NULL, a context is allocated with malloc.
64 \param t The Goertzel descriptor.
65 \return A pointer to the Goertzel state. */
66 goertzel_state_t *goertzel_init(goertzel_state_t *s,
67 goertzel_descriptor_t *t);
68
69 /*! \brief Reset the state of a Goertzel transform.
70 \param s The Goertzel context.
71 \param t The Goertzel descriptor.
72 \return A pointer to the Goertzel state. */
73 void goertzel_reset(goertzel_state_t *s);
74
75 /*! \brief Update the state of a Goertzel transform.
76 \param s The Goertzel context
77 \param amp The samples to be transformed
78 \param samples The number of samples
79 \return The number of samples unprocessed */
80 int goertzel_update(goertzel_state_t *s,
81 const int16_t amp[],
82 int samples);
83
84 /*! \brief Evaluate the final result of a Goertzel transform.
85 \param s The Goertzel context
86 \return The result of the transform. */
87 float goertzel_result(goertzel_state_t *s);
88
89 /*! \brief Update the state of a Goertzel transform.
90 \param s The Goertzel context
91 \param amp The sample to be transformed. */
92 static __inline__ void goertzel_sample(goertzel_state_t *s, int16_t amp)
93 {
94 float v1;
95
96 v1 = s->v2;
97 s->v2 = s->v3;
98 s->v3 = s->fac*s->v2 - v1 + amp;
99 s->current_sample++;
100 }
101 /*- End of function --------------------------------------------------------*/
102
103 #ifdef __cplusplus
104 }
105 #endif
106
107 #endif
108 /*- End of file ------------------------------------------------------------*/

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