241 lines
7.5 KiB
C
241 lines
7.5 KiB
C
/*
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* libteletone
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* Copyright (C) 2005-2014, Anthony Minessale II <anthm@freeswitch.org>
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*
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* libteletone_detect.c Tone Detection Code
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*
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* Exception:
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* The author hereby grants the use of this source code under the
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* following license if and only if the source code is distributed
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* as part of the openzap library. Any use or distribution of this
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* source code outside the scope of the openzap library will nullify the
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* following license and reinact the MPL 1.1 as stated above.
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*
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* Copyright (c) 2007, Anthony Minessale II
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* * Neither the name of the original author; nor the names of any contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*********************************************************************************
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*
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* Derived from tone_detect.h - General telephony tone detection, and specific
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* detection of DTMF.
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*
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* Copyright (C) 2001 Steve Underwood <steveu@coppice.org>
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*
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* Despite my general liking of the GPL, I place this code in the
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* public domain for the benefit of all mankind - even the slimy
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* ones who might try to proprietize my work and use it to my
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* detriment.
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*
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*
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*/
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#ifndef LIBTELETONE_DETECT_H
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#define LIBTELETONE_DETECT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <libteletone.h>
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/*! \file libteletone_detect.h
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\brief Tone Detection Routines
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This module is responsible for tone detection specifics
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*/
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#ifndef FALSE
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#define FALSE 0
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#ifndef TRUE
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#define TRUE (!FALSE)
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#endif
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#endif
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/* Basic DTMF specs:
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*
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* Minimum tone on = 40ms
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* Minimum tone off = 50ms
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* Maximum digit rate = 10 per second
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* Normal twist <= 8dB accepted
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* Reverse twist <= 4dB accepted
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* S/N >= 15dB will detect OK
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* Attenuation <= 26dB will detect OK
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* Frequency tolerance +- 1.5% will detect, +-3.5% will reject
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*/
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#define DTMF_THRESHOLD 8.0e7
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#define DTMF_NORMAL_TWIST 6.3 /* 8dB */
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#define DTMF_REVERSE_TWIST 2.5 /* 4dB */
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#define DTMF_RELATIVE_PEAK_ROW 6.3 /* 8dB */
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#define DTMF_RELATIVE_PEAK_COL 6.3 /* 8dB */
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#define DTMF_2ND_HARMONIC_ROW 2.5 /* 4dB */
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#define DTMF_2ND_HARMONIC_COL 63.1 /* 18dB */
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#define GRID_FACTOR 4
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#define BLOCK_LEN 102
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#define M_TWO_PI 2.0*M_PI
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/*! \brief A continer for the elements of a Goertzel Algorithm (The names are from his formula) */
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typedef struct {
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float v2;
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float v3;
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double fac;
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} teletone_goertzel_state_t;
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/*! \brief A container for a DTMF detection state.*/
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typedef struct {
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int hit1;
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int hit2;
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int hit3;
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int hit4;
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int mhit;
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teletone_goertzel_state_t row_out[GRID_FACTOR];
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teletone_goertzel_state_t col_out[GRID_FACTOR];
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teletone_goertzel_state_t row_out2nd[GRID_FACTOR];
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teletone_goertzel_state_t col_out2nd[GRID_FACTOR];
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float energy;
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int current_sample;
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char digits[TELETONE_MAX_DTMF_DIGITS + 1];
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int current_digits;
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int detected_digits;
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int lost_digits;
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int digit_hits[16];
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} teletone_dtmf_detect_state_t;
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/*! \brief An abstraction to store the coefficient of a tone frequency */
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typedef struct {
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float fac;
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} teletone_detection_descriptor_t;
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/*! \brief A container for a single multi-tone detection
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TELETONE_MAX_TONES dictates the maximum simultaneous tones that can be present
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in a multi-tone representation.
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*/
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typedef struct {
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int sample_rate;
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teletone_detection_descriptor_t tdd[TELETONE_MAX_TONES];
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teletone_goertzel_state_t gs[TELETONE_MAX_TONES];
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teletone_goertzel_state_t gs2[TELETONE_MAX_TONES];
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int tone_count;
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float energy;
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int current_sample;
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int min_samples;
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int total_samples;
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int positives;
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int negatives;
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int hits;
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int positive_factor;
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int negative_factor;
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int hit_factor;
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} teletone_multi_tone_t;
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/*!
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\brief Initilize a multi-frequency tone detector
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\param mt the multi-frequency tone descriptor
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\param map a representation of the multi-frequency tone
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*/
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TELETONE_API(void) teletone_multi_tone_init(teletone_multi_tone_t *mt, teletone_tone_map_t *map);
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/*!
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\brief Check a sample buffer for the presence of the mulit-frequency tone described by mt
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\param mt the multi-frequency tone descriptor
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\param sample_buffer an array aof 16 bit signed linear samples
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\param samples the number of samples present in sample_buffer
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\return true when the tone was detected or false when it is not
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*/
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TELETONE_API(int) teletone_multi_tone_detect (teletone_multi_tone_t *mt,
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int16_t sample_buffer[],
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int samples);
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/*!
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\brief Initilize a DTMF detection state object
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\param dtmf_detect_state the DTMF detection state to initilize
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\param sample_rate the desired sample rate
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*/
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TELETONE_API(void) teletone_dtmf_detect_init (teletone_dtmf_detect_state_t *dtmf_detect_state, int sample_rate);
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/*!
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\brief Check a sample buffer for the presence of DTMF digits
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\param dtmf_detect_state the detection state object to check
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\param sample_buffer an array aof 16 bit signed linear samples
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\param samples the number of samples present in sample_buffer
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\return true when DTMF was detected or false when it is not
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*/
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TELETONE_API(int) teletone_dtmf_detect (teletone_dtmf_detect_state_t *dtmf_detect_state,
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int16_t sample_buffer[],
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int samples);
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/*!
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\brief retrieve any collected digits into a string buffer
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\param dtmf_detect_state the detection state object to check
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\param buf the string buffer to write to
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\param max the maximum length of buf
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\return the number of characters written to buf
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*/
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TELETONE_API(int) teletone_dtmf_get (teletone_dtmf_detect_state_t *dtmf_detect_state,
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char *buf,
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int max);
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/*!
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\brief Step through the Goertzel Algorithm for each sample in a buffer
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\param goertzel_state the goertzel state to step the samples through
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\param sample_buffer an array aof 16 bit signed linear samples
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\param samples the number of samples present in sample_buffer
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*/
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TELETONE_API(void) teletone_goertzel_update(teletone_goertzel_state_t *goertzel_state,
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int16_t sample_buffer[],
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int samples);
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#ifdef __cplusplus
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}
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#endif
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#endif
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/* For Emacs:
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* Local Variables:
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* mode:c
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* indent-tabs-mode:t
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* tab-width:4
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* c-basic-offset:4
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* End:
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* For VIM:
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* vim:set softtabstop=4 shiftwidth=4 tabstop=4 noet:
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*/
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