drivers/misc/echo/oslec.h

   1 /*
   2  *  OSLEC - A line echo canceller.  This code is being developed
   3  *          against and partially complies with G168. Using code from SpanDSP
   4  *
   5  * Written by Steve Underwood <steveu@coppice.org>
   6  *         and David Rowe <david_at_rowetel_dot_com>
   7  *
   8  * Copyright (C) 2001 Steve Underwood and 2007-2008 David Rowe
   9  *
  10  * All rights reserved.
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2, as
  14  * published by the Free Software Foundation.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  24  *
  25  */
  26
  27 #ifndef __OSLEC_H
  28 #define __OSLEC_H
  29
  30 /* Mask bits for the adaption mode */
  31 #define ECHO_CAN_USE_ADAPTION   0x01
  32 #define ECHO_CAN_USE_NLP        0x02
  33 #define ECHO_CAN_USE_CNG        0x04
  34 #define ECHO_CAN_USE_CLIP       0x08
  35 #define ECHO_CAN_USE_TX_HPF     0x10
  36 #define ECHO_CAN_USE_RX_HPF     0x20
  37 #define ECHO_CAN_DISABLE        0x40
  38
  39 /**
  40  * oslec_state: G.168 echo canceller descriptor.
  41  *
  42  * This defines the working state for a line echo canceller.
  43  */
  44 struct oslec_state;
  45
  46 /**
  47  * oslec_create - Create a voice echo canceller context.
  48  * @len: The length of the canceller, in samples.
  49  * @return: The new canceller context, or NULL if the canceller could not be
  50  * created.
  51  */
  52 struct oslec_state *oslec_create(int len, int adaption_mode);
  53
  54 /**
  55  * oslec_free - Free a voice echo canceller context.
  56  * @ec: The echo canceller context.
  57  */
  58 void oslec_free(struct oslec_state *ec);
  59
  60 /**
  61  * oslec_flush - Flush (reinitialise) a voice echo canceller context.
  62  * @ec: The echo canceller context.
  63  */
  64 void oslec_flush(struct oslec_state *ec);
  65
  66 /**
  67  * oslec_adaption_mode - set the adaption mode of a voice echo canceller context.
  68  * @ec The echo canceller context.
  69  * @adaption_mode: The mode.
  70  */
  71 void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode);
  72
  73 void oslec_snapshot(struct oslec_state *ec);
  74
  75 /**
  76  * oslec_update: Process a sample through a voice echo canceller.
  77  * @ec: The echo canceller context.
  78  * @tx: The transmitted audio sample.
  79  * @rx: The received audio sample.
  80  *
  81  * The return value is the clean (echo cancelled) received sample.
  82  */
  83 int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx);
  84
  85 /**
  86  * oslec_hpf_tx: Process to high pass filter the tx signal.
  87  * @ec: The echo canceller context.
  88  * @tx: The transmitted auio sample.
  89  *
  90  * The return value is the HP filtered transmit sample, send this to your D/A.
  91  */
  92 int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx);
  93
  94 #endif /* __OSLEC_H */