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/*
* OSLEC - A line echo canceller. This code is being developed
* against and partially complies with G168. Using code from SpanDSP
*
* Written by Steve Underwood <steveu@coppice.org>
* and David Rowe <david_at_rowetel_dot_com>
*
* Copyright (C) 2001 Steve Underwood and 2007-2008 David Rowe
*
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#ifndef __OSLEC_H
#define __OSLEC_H
/* TODO: document interface */
/* Mask bits for the adaption mode */
#define ECHO_CAN_USE_ADAPTION 0x01
#define ECHO_CAN_USE_NLP 0x02
#define ECHO_CAN_USE_CNG 0x04
#define ECHO_CAN_USE_CLIP 0x08
#define ECHO_CAN_USE_TX_HPF 0x10
#define ECHO_CAN_USE_RX_HPF 0x20
#define ECHO_CAN_DISABLE 0x40
/*!
G.168 echo canceller descriptor. This defines the working state for a line
echo canceller.
*/
struct oslec_state;
/*! Create a voice echo canceller context.
\param len The length of the canceller, in samples.
\return The new canceller context, or NULL if the canceller could not be created.
*/
struct oslec_state *oslec_create(int len, int adaption_mode);
/*! Free a voice echo canceller context.
\param ec The echo canceller context.
*/
void oslec_free(struct oslec_state *ec);
/*! Flush (reinitialise) a voice echo canceller context.
\param ec The echo canceller context.
*/
void oslec_flush(struct oslec_state *ec);
/*! Set the adaption mode of a voice echo canceller context.
\param ec The echo canceller context.
\param adapt The mode.
*/
void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode);
void oslec_snapshot(struct oslec_state *ec);
/*! Process a sample through a voice echo canceller.
\param ec The echo canceller context.
\param tx The transmitted audio sample.
\param rx The received audio sample.
\return The clean (echo cancelled) received sample.
*/
int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx);
/*! Process to high pass filter the tx signal.
\param ec The echo canceller context.
\param tx The transmitted auio sample.
\return The HP filtered transmit sample, send this to your D/A.
*/
int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx);
#endif /* __OSLEC_H */
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