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 1.31 2007/04/08 08:16:18 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 float fac; 00037 int samples; 00038 } goertzel_descriptor_t; 00039 00040 /*! 00041 Floating point Goertzel filter state descriptor. 00042 */ 00043 typedef struct 00044 { 00045 float v2; 00046 float v3; 00047 float fac; 00048 int samples; 00049 int current_sample; 00050 } goertzel_state_t; 00051 00052 #if defined(__cplusplus) 00053 extern "C" 00054 { 00055 #endif 00056 00057 /*! \brief Create a descriptor for use with either a Goertzel transform */ 00058 void make_goertzel_descriptor(goertzel_descriptor_t *t, 00059 float freq, 00060 int samples); 00061 00062 /*! \brief Initialise the state of a Goertzel transform. 00063 \param s The Goertzel context. If NULL, a context is allocated with malloc. 00064 \param t The Goertzel descriptor. 00065 \return A pointer to the Goertzel state. */ 00066 goertzel_state_t *goertzel_init(goertzel_state_t *s, 00067 goertzel_descriptor_t *t); 00068 00069 /*! \brief Reset the state of a Goertzel transform. 00070 \param s The Goertzel context. 00071 \param t The Goertzel descriptor. 00072 \return A pointer to the Goertzel state. */ 00073 void goertzel_reset(goertzel_state_t *s); 00074 00075 /*! \brief Update the state of a Goertzel transform. 00076 \param s The Goertzel context 00077 \param amp The samples to be transformed 00078 \param samples The number of samples 00079 \return The number of samples unprocessed */ 00080 int goertzel_update(goertzel_state_t *s, 00081 const int16_t amp[], 00082 int samples); 00083 00084 /*! \brief Evaluate the final result of a Goertzel transform. 00085 \param s The Goertzel context 00086 \return The result of the transform. */ 00087 float goertzel_result(goertzel_state_t *s); 00088 00089 /*! \brief Update the state of a Goertzel transform. 00090 \param s The Goertzel context 00091 \param amp The sample to be transformed. */ 00092 static __inline__ void goertzel_sample(goertzel_state_t *s, int16_t amp) 00093 { 00094 float v1; 00095 00096 v1 = s->v2; 00097 s->v2 = s->v3; 00098 s->v3 = s->fac*s->v2 - v1 + amp; 00099 s->current_sample++; 00100 } 00101 /*- End of function --------------------------------------------------------*/ 00102 00103 #if defined(__cplusplus) 00104 } 00105 #endif 00106 00107 #endif 00108 /*- End of file ------------------------------------------------------------*/