xref: /linux/drivers/misc/echo/oslec.h (revision 75bf465f0bc33e9b776a46d6a1b9b990f5fb7c37)
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  */
31 struct 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  */
39 struct 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  */
45 void 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  */
51 void 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  */
58 void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode);
59 
60 void 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  */
70 int16_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  */
79 int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx);
80 
81 #endif /* __OSLEC_H */
82