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bell_r2_mf.h
Go to the documentation of this file.
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/*
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* SpanDSP - a series of DSP components for telephony
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*
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* bell_r2_mf.h - Bell MF and MFC/R2 tone generation and detection.
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2001 Steve Underwood
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/*! \file */
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#if !defined(_SPANDSP_BELL_R2_MF_H_)
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#define _SPANDSP_BELL_R2_MF_H_
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/*! \page mfc_r2_tone_generation_page MFC/R2 tone generation
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\section mfc_r2_tone_generation_page_sec_1 What does it do?
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The MFC/R2 tone generation module provides for the generation of the
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repertoire of 15 dual tones needs for the digital MFC/R2 signalling protocol.
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\section mfc_r2_tone_generation_page_sec_2 How does it work?
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*/
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/*! \page bell_mf_tone_generation_page Bell MF tone generation
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\section bell_mf_tone_generation_page_sec_1 What does it do?
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The Bell MF tone generation module provides for the generation of the
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repertoire of 15 dual tones needs for various Bell MF signalling protocols.
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\section bell_mf_tone_generation_page_sec_2 How does it work?
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Basic Bell MF tone generation specs:
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- Tone on time = KP: 100+-7ms. All other signals: 68+-7ms
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- Tone off time (between digits) = 68+-7ms
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- Frequency tolerance +- 1.5%
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- Signal level -7+-1dBm per frequency
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*/
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/*! \page mfc_r2_tone_rx_page MFC/R2 tone receiver
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\section mfc_r2_tone_rx_page_sec_1 What does it do?
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The MFC/R2 tone receiver module provides for the detection of the
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repertoire of 15 dual tones needs for the digital MFC/R2 signalling protocol.
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It is compliant with ITU-T Q.441D.
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\section mfc_r2_tone_rx_page_sec_2 How does it work?
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Basic MFC/R2 tone detection specs:
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- Receiver response range: -5dBm to -35dBm
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- Difference in level for a pair of frequencies
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- Adjacent tones: <5dB
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- Non-adjacent tones: <7dB
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- Receiver not to detect a signal of 2 frequencies of level -5dB and
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duration <7ms.
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- Receiver not to recognise a signal of 2 frequencies having a difference
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in level >=20dB.
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- Max received signal frequency error: +-10Hz
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- The sum of the operate and release times of a 2 frequency signal not to
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exceed 80ms (there are no individual specs for the operate and release
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times).
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- Receiver not to release for signal interruptions <=7ms.
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- System malfunction due to signal interruptions >7ms (typically 20ms) is
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prevented by further logic elements.
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*/
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/*! \page bell_mf_tone_rx_page Bell MF tone receiver
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\section bell_mf_tone_rx_page_sec_1 What does it do?
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The Bell MF tone receiver module provides for the detection of the
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repertoire of 15 dual tones needs for various Bell MF signalling protocols.
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It is compliant with ITU-T Q.320, ITU-T Q.322, ITU-T Q.323B.
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\section bell_mf_tone_rx_page_sec_2 How does it work?
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Basic Bell MF tone detection specs:
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- Frequency tolerance +- 1.5% +-10Hz
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- Signal level -14dBm to 0dBm
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- Perform a "two and only two tones present" test.
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- Twist <= 6dB accepted
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- Receiver sensitive to signals above -22dBm per frequency
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- Test for a minimum of 55ms if KP, or 30ms of other signals.
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- Signals to be recognised if the two tones arrive within 8ms of each other.
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- Invalid signals result in the return of the re-order tone.
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Note: Above -3dBm the signal starts to clip. We can detect with a little clipping,
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but not up to 0dBm, which the above spec seems to require. There isn't a lot
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we can do about that. Is the spec. incorrectly worded about the dBm0 reference
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point, or have I misunderstood it?
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*/
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/*! The maximum number of Bell MF digits we can buffer. */
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#define MAX_BELL_MF_DIGITS 128
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/*!
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Bell MF generator state descriptor. This defines the state of a single
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working instance of a Bell MF generator.
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*/
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typedef
struct
bell_mf_tx_state_s
bell_mf_tx_state_t
;
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/*!
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Bell MF digit detector descriptor.
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*/
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typedef
struct
bell_mf_rx_state_s
bell_mf_rx_state_t
;
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/*!
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MFC/R2 tone detector descriptor.
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*/
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typedef
struct
r2_mf_tx_state_s
r2_mf_tx_state_t
;
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/*!
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MFC/R2 tone detector descriptor.
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*/
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typedef
struct
r2_mf_rx_state_s
r2_mf_rx_state_t
;
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#if defined(__cplusplus)
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extern
"C"
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{
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#endif
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/*! \brief Generate a buffer of Bell MF tones.
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\param s The Bell MF generator context.
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\param amp The buffer for the generated signal.
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\param max_samples The required number of generated samples.
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\return The number of samples actually generated. This may be less than
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max_samples if the input buffer empties. */
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SPAN_DECLARE(
int
)
bell_mf_tx
(
bell_mf_tx_state_t
*s, int16_t amp[],
int
max_samples);
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/*! \brief Put a string of digits in a Bell MF generator's input buffer.
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\param s The Bell MF generator context.
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\param digits The string of digits to be added.
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\param len The length of the string of digits. If negative, the string is
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assumed to be a NULL terminated string.
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\return The number of digits actually added. This may be less than the
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length of the digit string, if the buffer fills up. */
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SPAN_DECLARE(
int
)
bell_mf_tx_put
(
bell_mf_tx_state_t
*s, const
char
*digits,
int
len);
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/*! \brief Initialise a Bell MF generator context.
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\param s The Bell MF generator context.
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\return A pointer to the Bell MF generator context.*/
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SPAN_DECLARE(
bell_mf_tx_state_t
*)
bell_mf_tx_init
(
bell_mf_tx_state_t
*s);
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/*! \brief Release a Bell MF generator context.
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\param s The Bell MF generator context.
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\return 0 for OK, else -1. */
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SPAN_DECLARE(
int
)
bell_mf_tx_release
(
bell_mf_tx_state_t
*s);
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/*! \brief Free a Bell MF generator context.
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\param s The Bell MF generator context.
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\return 0 for OK, else -1. */
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SPAN_DECLARE(
int
)
bell_mf_tx_free
(
bell_mf_tx_state_t
*s);
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/*! \brief Generate a block of R2 MF tones.
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\param s The R2 MF generator context.
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\param amp The buffer for the generated signal.
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\param samples The required number of generated samples.
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\return The number of samples actually generated. */
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SPAN_DECLARE(
int
)
r2_mf_tx
(
r2_mf_tx_state_t
*s, int16_t amp[],
int
samples);
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/*! \brief Generate a block of R2 MF tones.
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\param s The R2 MF generator context.
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\param digit The digit to be generated.
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\return 0 for OK, or -1 for a bad request. */
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SPAN_DECLARE(
int
)
r2_mf_tx_put
(
r2_mf_tx_state_t
*s,
char
digit);
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/*! \brief Initialise an R2 MF tone generator context.
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\param s The R2 MF generator context.
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\param fwd TRUE if the context is for forward signals. FALSE if the
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context is for backward signals.
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\return A pointer to the MFC/R2 generator context.*/
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SPAN_DECLARE(
r2_mf_tx_state_t
*)
r2_mf_tx_init
(
r2_mf_tx_state_t
*s,
int
fwd
);
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/*! \brief Release an R2 MF tone generator context.
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\param s The R2 MF tone generator context.
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\return 0 for OK, else -1. */
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SPAN_DECLARE(
int
)
r2_mf_tx_release
(
r2_mf_tx_state_t
*s);
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/*! \brief Free an R2 MF tone generator context.
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\param s The R2 MF tone generator context.
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\return 0 for OK, else -1. */
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SPAN_DECLARE(
int
)
r2_mf_tx_free
(
r2_mf_tx_state_t
*s);
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/*! Process a block of received Bell MF audio samples.
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\brief Process a block of received Bell MF audio samples.
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\param s The Bell MF receiver context.
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\param amp The audio sample buffer.
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\param samples The number of samples in the buffer.
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\return The number of samples unprocessed. */
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SPAN_DECLARE(
int
)
bell_mf_rx
(
bell_mf_rx_state_t
*s, const int16_t amp[],
int
samples);
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/*! \brief Get a string of digits from a Bell MF receiver's output buffer.
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\param s The Bell MF receiver context.
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\param buf The buffer for the received digits.
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\param max The maximum number of digits to be returned,
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\return The number of digits actually returned. */
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SPAN_DECLARE(
size_t
)
bell_mf_rx_get
(
bell_mf_rx_state_t
*s,
char
*buf,
int
max);
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/*! \brief Initialise a Bell MF receiver context.
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\param s The Bell MF receiver context.
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\param callback An optional callback routine, used to report received digits. If
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no callback routine is set, digits may be collected, using the bell_mf_rx_get()
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function.
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\param user_data An opaque pointer which is associated with the context,
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and supplied in callbacks.
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\return A pointer to the Bell MF receiver context.*/
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SPAN_DECLARE(
bell_mf_rx_state_t
*)
bell_mf_rx_init
(
bell_mf_rx_state_t
*s,
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digits_rx_callback_t
callback
,
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void
*user_data);
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/*! \brief Release a Bell MF receiver context.
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\param s The Bell MF receiver context.
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\return 0 for OK, else -1. */
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SPAN_DECLARE(
int
)
bell_mf_rx_release
(
bell_mf_rx_state_t
*s);
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/*! \brief Free a Bell MF receiver context.
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\param s The Bell MF receiver context.
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\return 0 for OK, else -1. */
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SPAN_DECLARE(
int
)
bell_mf_rx_free
(
bell_mf_rx_state_t
*s);
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/*! Process a block of received R2 MF audio samples.
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\brief Process a block of received R2 MF audio samples.
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\param s The R2 MF receiver context.
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\param amp The audio sample buffer.
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\param samples The number of samples in the buffer.
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\return The number of samples unprocessed. */
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SPAN_DECLARE(
int
)
r2_mf_rx
(
r2_mf_rx_state_t
*s, const int16_t amp[],
int
samples);
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/*! \brief Get the current digit from an R2 MF receiver.
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\param s The R2 MF receiver context.
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\return The number digits being received. */
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SPAN_DECLARE(
int
)
r2_mf_rx_get
(
r2_mf_rx_state_t
*s);
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/*! \brief Initialise an R2 MF receiver context.
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\param s The R2 MF receiver context.
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\param fwd TRUE if the context is for forward signals. FALSE if the
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context is for backward signals.
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\param callback An optional callback routine, used to report received digits. If
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no callback routine is set, digits may be collected, using the r2_mf_rx_get()
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function.
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\param user_data An opaque pointer which is associated with the context,
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and supplied in callbacks.
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\return A pointer to the R2 MF receiver context. */
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SPAN_DECLARE(
r2_mf_rx_state_t
*)
r2_mf_rx_init
(
r2_mf_rx_state_t
*s,
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int
fwd,
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tone_report_func_t callback,
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void
*user_data);
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/*! \brief Release an R2 MF receiver context.
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\param s The R2 MF receiver context.
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\return 0 for OK, else -1. */
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SPAN_DECLARE(
int
)
r2_mf_rx_release
(
r2_mf_rx_state_t
*s);
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/*! \brief Free an R2 MF receiver context.
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\param s The R2 MF receiver context.
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\return 0 for OK, else -1. */
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SPAN_DECLARE(
int
)
r2_mf_rx_free
(
r2_mf_rx_state_t
*s);
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#if defined(__cplusplus)
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}
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#endif
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#endif
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/*- End of file ------------------------------------------------------------*/
src
spandsp
bell_r2_mf.h
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