LXR linux/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 */
  44struct 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 */
  52struct 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 */
  58void 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 */
  64void 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 */
  71void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode);
  72
  73void 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 */
  83int16_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 */
  92int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx);
  93
  94#endif /* __OSLEC_H */
  95