audiostuff: spandsp-0.0.6pre17/src/modem

author	Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date	Fri, 25 Jun 2010 15:50:58 +0200
parents
children

rev	line source
4 26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	1 /*
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	2 * SpanDSP - a series of DSP components for telephony
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	3 *
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	4 * modem_echo.c - An echo cancellor, suitable for electrical echos in GSTN modems
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	5 *
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	6 * Written by Steve Underwood <steveu@coppice.org>
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	7 *
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	8 * Copyright (C) 2001, 2003, 2004 Steve Underwood
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	9 *
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	10 * All rights reserved.
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	11 *
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	12 * This program is free software; you can redistribute it and/or modify
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	13 * it under the terms of the GNU Lesser General Public License version 2.1,
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	14 * as published by the Free Software Foundation.
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	15 *
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	16 * This program is distributed in the hope that it will be useful,
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	19 * GNU Lesser General Public License for more details.
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	20 *
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	21 * You should have received a copy of the GNU Lesser General Public
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	22 * License along with this program; if not, write to the Free Software
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	24 *
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	25 * $Id: modem_echo.c,v 1.26 2009/09/22 13:11:04 steveu Exp $
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	26 */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	27
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	28 /! \file /
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	29
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	30 /* The FIR taps must be adapted as 32 bit values, to get the necessary finesse
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	31 in the adaption process. However, they are applied as 16 bit values (bits 30-15
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	32 of the 32 bit values) in the FIR. For the working 16 bit values, we need 4 sets.
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	33 */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	34
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	35 #if defined(HAVE_CONFIG_H)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	36 #include "config.h"
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	37 #endif
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	38
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	39 #include <stdlib.h>
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	40 #include <inttypes.h>
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	41 #include <string.h>
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	42 #include <stdio.h>
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	43 #if defined(HAVE_TGMATH_H)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	44 #include <tgmath.h>
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	45 #endif
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	46 #if defined(HAVE_MATH_H)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	47 #include <math.h>
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	48 #endif
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	49 #include "floating_fudge.h"
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	50
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	51 #include "spandsp/telephony.h"
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	52 #include "spandsp/bit_operations.h"
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	53 #include "spandsp/dc_restore.h"
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	54 #include "spandsp/modem_echo.h"
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	55
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	56 #include "spandsp/private/modem_echo.h"
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	57
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	58 SPAN_DECLARE(modem_echo_can_state_t *) modem_echo_can_create(int len)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	59 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	60 modem_echo_can_state_t *ec;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	61
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	62 if ((ec = (modem_echo_can_state_t ) malloc(sizeof(ec))) == NULL)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	63 return NULL;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	64 memset(ec, 0, sizeof(*ec));
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	65 ec->taps = len;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	66 ec->curr_pos = ec->taps - 1;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	67 if ((ec->fir_taps32 = (int32_t ) malloc(ec->tapssizeof(int32_t))) == NULL)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	68 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	69 free(ec);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	70 return NULL;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	71 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	72 memset(ec->fir_taps32, 0, ec->taps*sizeof(int32_t));
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	73 if ((ec->fir_taps16 = (int16_t ) malloc(ec->tapssizeof(int16_t))) == NULL)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	74 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	75 free(ec->fir_taps32);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	76 free(ec);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	77 return NULL;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	78 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	79 memset(ec->fir_taps16, 0, ec->taps*sizeof(int16_t));
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	80 if (fir16_create(&ec->fir_state, ec->fir_taps16, ec->taps) == NULL)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	81 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	82 free(ec->fir_taps16);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	83 free(ec->fir_taps32);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	84 free(ec);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	85 return NULL;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	86 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	87 return ec;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	88 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	89 /- End of function --------------------------------------------------------/
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	90
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	91 SPAN_DECLARE(void) modem_echo_can_free(modem_echo_can_state_t *ec)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	92 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	93 fir16_free(&ec->fir_state);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	94 free(ec->fir_taps32);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	95 free(ec->fir_taps16);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	96 free(ec);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	97 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	98 /- End of function --------------------------------------------------------/
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	99
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	100 SPAN_DECLARE(void) modem_echo_can_flush(modem_echo_can_state_t *ec)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	101 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	102 ec->tx_power = 0;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	103
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	104 fir16_flush(&ec->fir_state);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	105 ec->fir_state.curr_pos = ec->taps - 1;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	106 memset(ec->fir_taps32, 0, ec->taps*sizeof(int32_t));
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	107 memset(ec->fir_taps16, 0, ec->taps*sizeof(int16_t));
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	108 ec->curr_pos = ec->taps - 1;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	109 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	110 /- End of function --------------------------------------------------------/
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	111
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	112 SPAN_DECLARE(void) modem_echo_can_adaption_mode(modem_echo_can_state_t *ec, int adapt)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	113 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	114 ec->adapt = adapt;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	115 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	116 /- End of function --------------------------------------------------------/
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	117
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	118 SPAN_DECLARE(int16_t) modem_echo_can_update(modem_echo_can_state_t *ec, int16_t tx, int16_t rx)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	119 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	120 int32_t echo_value;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	121 int clean_rx;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	122 int shift;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	123 int i;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	124 int offset1;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	125 int offset2;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	126
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	127 /* Evaluate the echo - i.e. apply the FIR filter */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	128 /* Assume the gain of the FIR does not exceed unity. Exceeding unity
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	129 would seem like a rather poor thing for an echo cancellor to do :)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	130 This means we can compute the result with a total disregard for
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	131 overflows. 16bits x 16bits -> 31bits, so no overflow can occur in
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	132 any multiply. While accumulating we may overflow and underflow the
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	133 32 bit scale often. However, if the gain does not exceed unity,
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	134 everything should work itself out, and the final result will be
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	135 OK, without any saturation logic. */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	136 /* Overflow is very much possible here, and we do nothing about it because
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	137 of the compute costs */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	138 echo_value = fir16(&ec->fir_state, tx);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	139
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	140 /* And the answer is..... */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	141 clean_rx = rx - echo_value;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	142 //printf("%8d %8d %8d %8d\n", tx, rx, echo_value, clean_rx);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	143 if (ec->adapt)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	144 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	145 /* Calculate short term power levels using very simple single pole IIRs */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	146 /* TODO: Is the nasty modulus approach the fastest, or would a real
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	147 tx*tx power calculation actually be faster? Using the squares
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	148 makes the numbers grow a lot! */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	149 ec->tx_power += ((tx*tx - ec->tx_power) >> 5);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	150
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	151 shift = 1;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	152 /* Update the FIR taps */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	153 offset2 = ec->curr_pos;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	154 offset1 = ec->taps - offset2;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	155 for (i = ec->taps - 1; i >= offset1; i--)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	156 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	157 /* Leak to avoid the coefficients drifting beyond the ability of the
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	158 adaption process to bring them back under control. */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	159 ec->fir_taps32[i] -= (ec->fir_taps32[i] >> 23);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	160 ec->fir_taps32[i] += (ec->fir_state.history[i - offset1]*clean_rx) >> shift;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	161 ec->fir_taps16[i] = (int16_t) (ec->fir_taps32[i] >> 15);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	162 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	163 for ( ; i >= 0; i--)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	164 {
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	165 ec->fir_taps32[i] -= (ec->fir_taps32[i] >> 23);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	166 ec->fir_taps32[i] += (ec->fir_state.history[i + offset2]*clean_rx) >> shift;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	167 ec->fir_taps16[i] = (int16_t) (ec->fir_taps32[i] >> 15);
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	168 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	169 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	170
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	171 /* Roll around the rolling buffer */
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	172 if (ec->curr_pos <= 0)
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	173 ec->curr_pos = ec->taps;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	174 ec->curr_pos--;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	175 return (int16_t) clean_rx;
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	176 }
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	177 /- End of function --------------------------------------------------------/
26cd8f1ef0b1 import spandsp-0.0.6pre17 Peter Meerwald <pmeerw@cosy.sbg.ac.at> parents: diff changeset	178 /- End of file ------------------------------------------------------------/

4

26cd8f1ef0b1 import spandsp-0.0.6pre17