LXR linux/drivers/misc/echo/oslec.h

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 *  OSLEC - A line echo canceller.  This code is being developed
   4 *          against and partially complies with G168. Using code from SpanDSP
   5 *
   6 * Written by Steve Underwood <steveu@coppice.org>
   7 *         and David Rowe <david_at_rowetel_dot_com>
   8 *
   9 * Copyright (C) 2001 Steve Underwood and 2007-2008 David Rowe
  10 *
  11 * All rights reserved.
  12 */
  13
  14#ifndef __OSLEC_H
  15#define __OSLEC_H
  16
  17/* Mask bits for the adaption mode */
  18#define ECHO_CAN_USE_ADAPTION   0x01
  19#define ECHO_CAN_USE_NLP        0x02
  20#define ECHO_CAN_USE_CNG        0x04
  21#define ECHO_CAN_USE_CLIP       0x08
  22#define ECHO_CAN_USE_TX_HPF     0x10
  23#define ECHO_CAN_USE_RX_HPF     0x20
  24#define ECHO_CAN_DISABLE        0x40
  25
  26/**
  27 * oslec_state: G.168 echo canceller descriptor.
  28 *
  29 * This defines the working state for a line echo canceller.
  30 */
  31struct oslec_state;
  32
  33/**
  34 * oslec_create - Create a voice echo canceller context.
  35 * @len: The length of the canceller, in samples.
  36 * @return: The new canceller context, or NULL if the canceller could not be
  37 * created.
  38 */
  39struct oslec_state *oslec_create(int len, int adaption_mode);
  40
  41/**
  42 * oslec_free - Free a voice echo canceller context.
  43 * @ec: The echo canceller context.
  44 */
  45void oslec_free(struct oslec_state *ec);
  46
  47/**
  48 * oslec_flush - Flush (reinitialise) a voice echo canceller context.
  49 * @ec: The echo canceller context.
  50 */
  51void oslec_flush(struct oslec_state *ec);
  52
  53/**
  54 * oslec_adaption_mode - set the adaption mode of a voice echo canceller context.
  55 * @ec The echo canceller context.
  56 * @adaption_mode: The mode.
  57 */
  58void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode);
  59
  60void oslec_snapshot(struct oslec_state *ec);
  61
  62/**
  63 * oslec_update: Process a sample through a voice echo canceller.
  64 * @ec: The echo canceller context.
  65 * @tx: The transmitted audio sample.
  66 * @rx: The received audio sample.
  67 *
  68 * The return value is the clean (echo cancelled) received sample.
  69 */
  70int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx);
  71
  72/**
  73 * oslec_hpf_tx: Process to high pass filter the tx signal.
  74 * @ec: The echo canceller context.
  75 * @tx: The transmitted auio sample.
  76 *
  77 * The return value is the HP filtered transmit sample, send this to your D/A.
  78 */
  79int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx);
  80
  81#endif /* __OSLEC_H */
  82