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