Root/drivers/staging/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

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