tone_detect.h

Go to the documentation of this file.
00001 /*
00002  * SpanDSP - a series of DSP components for telephony
00003  *
00004  * tone_detect.h - General telephony tone detection.
00005  *
00006  * Written by Steve Underwood <steveu@coppice.org>
00007  *
00008  * Copyright (C) 2001, 2005 Steve Underwood
00009  *
00010  * All rights reserved.
00011  *
00012  * This program is free software; you can redistribute it and/or modify
00013  * it under the terms of the GNU General Public License version 2, as
00014  * published by the Free Software Foundation.
00015  *
00016  * This program is distributed in the hope that it will be useful,
00017  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00018  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00019  * GNU General Public License for more details.
00020  *
00021  * You should have received a copy of the GNU General Public License
00022  * along with this program; if not, write to the Free Software
00023  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00024  *
00025  * $Id: tone_detect.h,v 1.32 2007/06/22 12:40:35 steveu Exp $
00026  */
00027 
00028 #if !defined(_SPANDSP_TONE_DETECT_H_)
00029 #define _SPANDSP_TONE_DETECT_H_
00030 
00031 /*!
00032     Floating point Goertzel filter descriptor.
00033 */
00034 typedef struct
00035 {
00036 #if defined(USE_FIXED_POINT_EXPERIMENTAL)
00037     int32_t fac;
00038 #else
00039     float fac;
00040 #endif
00041     int samples;
00042 } goertzel_descriptor_t;
00043 
00044 /*!
00045     Floating point Goertzel filter state descriptor.
00046 */
00047 typedef struct
00048 {
00049 #if defined(USE_FIXED_POINT_EXPERIMENTAL)
00050     int32_t v2;
00051     int32_t v3;
00052     int32_t fac;
00053 #else
00054     float v2;
00055     float v3;
00056     float fac;
00057 #endif
00058     int samples;
00059     int current_sample;
00060 } goertzel_state_t;
00061 
00062 #if defined(__cplusplus)
00063 extern "C"
00064 {
00065 #endif
00066 
00067 /*! \brief Create a descriptor for use with either a Goertzel transform */
00068 void make_goertzel_descriptor(goertzel_descriptor_t *t,
00069                               float freq,
00070                               int samples);
00071 
00072 /*! \brief Initialise the state of a Goertzel transform.
00073     \param s The Goertzel context. If NULL, a context is allocated with malloc.
00074     \param t The Goertzel descriptor.
00075     \return A pointer to the Goertzel state. */
00076 goertzel_state_t *goertzel_init(goertzel_state_t *s,
00077                                 goertzel_descriptor_t *t);
00078 
00079 /*! \brief Reset the state of a Goertzel transform.
00080     \param s The Goertzel context.
00081     \param t The Goertzel descriptor.
00082     \return A pointer to the Goertzel state. */
00083 void goertzel_reset(goertzel_state_t *s);
00084 
00085 /*! \brief Update the state of a Goertzel transform.
00086     \param s The Goertzel context.
00087     \param amp The samples to be transformed.
00088     \param samples The number of samples.
00089     \return The number of samples unprocessed */
00090 int goertzel_update(goertzel_state_t *s,
00091                     const int16_t amp[],
00092                     int samples);
00093 
00094 /*! \brief Evaluate the final result of a Goertzel transform.
00095     \param s The Goertzel context.
00096     \return The result of the transform. */
00097 float goertzel_result(goertzel_state_t *s);
00098 
00099 /*! \brief Update the state of a Goertzel transform.
00100     \param s The Goertzel context.
00101     \param amp The sample to be transformed. */
00102 static __inline__ void goertzel_sample(goertzel_state_t *s, int16_t amp)
00103 {
00104 #if defined(USE_FIXED_POINT_EXPERIMENTAL)
00105     int32_t v1;
00106 #else
00107     float v1;
00108 #endif
00109 
00110     v1 = s->v2;
00111     s->v2 = s->v3;
00112     s->v3 = s->fac*s->v2 - v1 + amp;
00113     s->current_sample++;
00114 }
00115 /*- End of function --------------------------------------------------------*/
00116 
00117 #if defined(__cplusplus)
00118 }
00119 #endif
00120 
00121 #endif
00122 /*- End of file ------------------------------------------------------------*/

Generated on Mon Jul 9 00:45:47 2007 for libspandsp by  doxygen 1.5.1