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/*
* Mark's Second Echo Canceller
*
* Copyright (C) 2002, Digium, Inc.
*
* This program is free software and may be used and
* distributed according to the terms of the GNU
* General Public License, incorporated herein by
* reference.
*
*/
#ifndef _MARK2_ECHO_H
#define _MARK2_ECHO_H
#ifdef __KERNEL__
#include <linux/kernel.h>
#include <linux/slab.h>
#define MALLOC(a) kmalloc((a), GFP_KERNEL)
#define FREE(a) kfree(a)
#else
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include <math.h>
#define MALLOC(a) malloc(a)
#define FREE(a) free(a)
#endif
/* Get optimized routines for math */
#include "arith.h"
#ifndef NULL
#define NULL 0
#endif
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE (!FALSE)
#endif
#include "mec2_const.h"
/* Circular buffer definition */
typedef struct {
int idx_d;
int size_d;
short *buf_d; /* Twice as large as we need */
} echo_can_cb_s;
// class definition
//
typedef struct {
/* Echo canceller definition */
/* absolute time */
int i_d;
/* pre-computed constants */
int N_d;
int beta2_i;
// declare accumulators for power computations
//
int Ly_i;
int Lu_i;
// declare an accumulator for the near-end signal detector
//
int s_tilde_i;
int HCNTR_d;
// circular buffers and coefficients
//
int *a_i;
short *a_s;
echo_can_cb_s y_s;
echo_can_cb_s s_s;
echo_can_cb_s u_s;
echo_can_cb_s y_tilde_s;
int y_tilde_i;
/* Max memory */
short max_y_tilde;
int max_y_tilde_pos;
} echo_can_state_t;
static inline void init_cb_s(echo_can_cb_s *cb, int len, void *where)
{
cb->buf_d = (short *)where;
cb->idx_d = 0;
cb->size_d = len;
}
static inline void add_cc_s(echo_can_cb_s *cb, short newval)
{
/* Can't use modulus because N+M isn't a power of two (generally) */
cb->idx_d--;
if (cb->idx_d < (int)0)
{cb->idx_d += cb->size_d;}
/* Load two copies into memory */
cb->buf_d[cb->idx_d] = newval;
cb->buf_d[cb->idx_d + cb->size_d] = newval;
}
static inline short get_cc_s(echo_can_cb_s *cb, int pos)
{
/* Load two copies into memory */
return cb->buf_d[cb->idx_d + pos];
}
static inline void init_cc(echo_can_state_t *ec, int N, int maxy, int maxu) {
void *ptr = ec;
unsigned long tmp;
/* double-word align past end of state */
ptr += sizeof(echo_can_state_t);
tmp = (unsigned long)ptr;
tmp += 3;
tmp &= ~3L;
ptr = (void *)tmp;
// reset parameters
//
ec->N_d = N;
ec->beta2_i = DEFAULT_BETA1_I;
// allocate coefficient memory
//
ec->a_i = ptr;
ptr += (sizeof(int) * ec->N_d);
ec->a_s = ptr;
ptr += (sizeof(short) * ec->N_d);
/* Reset Y circular buffer (short version) */
init_cb_s(&ec->y_s, maxy, ptr);
ptr += (sizeof(short) * (maxy) * 2);
/* Reset Sig circular buffer (short version for FIR filter) */
init_cb_s(&ec->s_s, (1 << DEFAULT_ALPHA_ST_I), ptr);
ptr += (sizeof(short) * (1 << DEFAULT_ALPHA_ST_I) * 2);
init_cb_s(&ec->u_s, maxu, ptr);
ptr += (sizeof(short) * maxu * 2);
// allocate a buffer for the reference signal power computation
//
init_cb_s(&ec->y_tilde_s, ec->N_d, ptr);
// reset absolute time
//
ec->i_d = (int)0;
// reset the power computations (for y and u)
//
ec->Ly_i = DEFAULT_CUTOFF_I;
// reset the near-end speech detector
//
ec->s_tilde_i = 0;
ec->HCNTR_d = (int)0;
// exit gracefully
//
}
static inline void echo_can_free(echo_can_state_t *ec)
{
FREE(ec);
}
static inline short echo_can_update(echo_can_state_t *ec, short iref, short isig) {
/* declare local variables that are used more than once
*/
int k;
int rs;
short u;
int Py_i;
int two_beta_i;
/***************************************************************************
//
// flow A on pg. 428
//
***************************************************************************/
/* eq. (16): high-pass filter the input to generate the next value;
// push the current value into the circular buffer
//
// sdc_im1_d = sdc_d;
// sdc_d = sig;
// s_i_d = sdc_d;
// s_d = s_i_d;
// s_i_d = (float)(1.0 - gamma_d) * s_i_d
+ (float)(0.5 * (1.0 - gamma_d)) * (sdc_d - sdc_im1_d); */
/* Delete last sample from power estimate */
ec->y_tilde_i -= abs(get_cc_s(&ec->y_s, (1 << DEFAULT_ALPHA_YT_I) - 1 )) >> DEFAULT_ALPHA_YT_I;
/* push the reference data onto the circular buffer */
add_cc_s(&ec->y_s, iref);
/* eq. (2): compute r in fixed-point */
rs = CONVOLVE2(ec->a_s, ec->y_s.buf_d + ec->y_s.idx_d, ec->N_d);
rs >>= 15;
/* eq. (3): compute the output value (see figure 3) and the error
// note: the error is the same as the output signal when near-end
// speech is not present
*/
u = isig - rs;
add_cc_s(&ec->u_s, u);
/* Delete oldest part of received s_tilde */
ec->s_tilde_i -= abs(get_cc_s(&ec->s_s, (1 << DEFAULT_ALPHA_ST_I) - 1 ));
/* push the signal on the circular buffer, too */
add_cc_s(&ec->s_s, isig);
ec->s_tilde_i += abs(isig);
ec->y_tilde_i += abs(iref) >> DEFAULT_ALPHA_ST_I;
/* Add to our list of recent y_tilde's */
add_cc_s(&ec->y_tilde_s, ec->y_tilde_i);
/****************************************************************************
//
// flow B on pg. 428
//
****************************************************************************/
/* compute the new convergence factor
*/
Py_i = (ec->Ly_i >> DEFAULT_SIGMA_LY_I) * (ec->Ly_i >> DEFAULT_SIGMA_LY_I);
Py_i >>= 15;
if (ec->HCNTR_d > 0) {
Py_i = (1 << 15);
}
#if 0
printf("Py: %e, Py_i: %e\n", Py, Py_i * AMPL_SCALE_1);
#endif
/* Vary rate of adaptation depending on position in the file
// Do not do this for the first (DEFAULT_UPDATE_TIME) secs after speech
// has begun of the file to allow the echo cancellor to estimate the
// channel accurately
*/
#if 0
if (ec->start_speech_d != 0 ){
if ( ec->i_d > (DEFAULT_T0 + ec->start_speech_d)*(SAMPLE_FREQ) ){
ec->beta2_d = max_cc_float(MIN_BETA,
DEFAULT_BETA1 * exp((-1/DEFAULT_TAU)*((ec->i_d/(float)SAMPLE_FREQ) -
DEFAULT_T0 -
ec->start_speech_d)));
}
}
else {ec->beta2_d = DEFAULT_BETA1;}
#endif
ec->beta2_i = DEFAULT_BETA1_I; /* Fixed point, inverted */
two_beta_i = (ec->beta2_i * Py_i) >> 15; /* Fixed point version, inverted */
if (!two_beta_i)
two_beta_i++;
/* Update Lu_i (Suppressed power estimate) */
ec->Lu_i -= abs(get_cc_s(&ec->u_s, (1 << DEFAULT_SIGMA_LU_I) - 1 )) ;
ec->Lu_i += abs(u);
/* eq. (10): update power estimate of the reference
*/
ec->Ly_i -= abs(get_cc_s(&ec->y_s, (1 << DEFAULT_SIGMA_LY_I) - 1)) ;
ec->Ly_i += abs(iref);
if (ec->Ly_i < DEFAULT_CUTOFF_I)
ec->Ly_i = DEFAULT_CUTOFF_I;
#if 0
printf("Float: %e, Int: %e\n", ec->Ly_d, (ec->Ly_i >> DEFAULT_SIGMA_LY_I) * AMPL_SCALE_1);
#endif
if (ec->y_tilde_i > ec->max_y_tilde) {
/* New highest y_tilde with full life */
ec->max_y_tilde = ec->y_tilde_i;
ec->max_y_tilde_pos = ec->N_d - 1;
} else if (--ec->max_y_tilde_pos < 0) {
/* Time to find new max y tilde... */
ec->max_y_tilde = MAX16(ec->y_tilde_s.buf_d + ec->y_tilde_s.idx_d, ec->N_d, &ec->max_y_tilde_pos);
}
if ((ec->s_tilde_i >> (DEFAULT_ALPHA_ST_I - 1)) > ec->max_y_tilde)
{
ec->HCNTR_d = DEFAULT_HANGT;
}
else if (ec->HCNTR_d > (int)0)
{
ec->HCNTR_d--;
}
/* update coefficients if no near-end speech and we have enough signal
* to bother trying to update.
*/
if (!ec->HCNTR_d && !(ec->i_d % DEFAULT_M) &&
(ec->Lu_i > MIN_UPDATE_THRESH_I)) {
// loop over all filter coefficients
//
for (k=0; k<ec->N_d; k++) {
// eq. (7): compute an expectation over M_d samples
//
int grad2;
grad2 = CONVOLVE2(ec->u_s.buf_d + ec->u_s.idx_d,
ec->y_s.buf_d + ec->y_s.idx_d + k, DEFAULT_M);
// eq. (7): update the coefficient
//
ec->a_i[k] += grad2 / two_beta_i;
ec->a_s[k] = ec->a_i[k] >> 16;
}
}
/* paragraph below eq. (15): if no near-end speech,
// check for residual error suppression
*/
#ifndef NO_ECHO_SUPPRESSOR
#ifdef AGGRESSIVE_SUPPRESSOR
if ((ec->HCNTR_d < AGGRESSIVE_HCNTR) && (ec->Ly_i > (ec->Lu_i << 1))) {
u = u * (ec->Lu_i >> DEFAULT_SIGMA_LU_I) / ((ec->Ly_i >> (DEFAULT_SIGMA_LY_I)) + 1);
u = u * (ec->Lu_i >> DEFAULT_SIGMA_LU_I) / ((ec->Ly_i >> (DEFAULT_SIGMA_LY_I)) + 1);
}
#else
if ((ec->HCNTR_d == 0) && ((ec->Ly_i/(ec->Lu_i + 1)) > DEFAULT_SUPPR_I)) {
u = u * (ec->Lu_i >> DEFAULT_SIGMA_LU_I) / ((ec->Ly_i >> (DEFAULT_SIGMA_LY_I + 2)) + 1);
}
#endif
#endif
#if 0
if ((ec->HCNTR_d == 0) && ((ec->Lu_d/ec->Ly_d) < DEFAULT_SUPPR) &&
(ec->Lu_d/ec->Ly_d > EC_MIN_DB_VALUE)) {
suppr_factor = (10/(float)(SUPPR_FLOOR-SUPPR_CEIL))*log(ec->Lu_d/ec->Ly_d)
- SUPPR_CEIL/(float)(SUPPR_FLOOR - SUPPR_CEIL);
u_suppr = pow(10.0,(suppr_factor)*RES_SUPR_FACTOR/10.0)*u_suppr;
}
#endif
ec->i_d++;
return u;
}
static inline echo_can_state_t *echo_can_create(int len, int adaption_mode)
{
echo_can_state_t *ec;
int maxy;
int maxu;
maxy = len + DEFAULT_M;
maxu = DEFAULT_M;
if (maxy < (1 << DEFAULT_ALPHA_YT_I))
maxy = (1 << DEFAULT_ALPHA_YT_I);
if (maxy < (1 << DEFAULT_SIGMA_LY_I))
maxy = (1 << DEFAULT_SIGMA_LY_I);
if (maxu < (1 << DEFAULT_SIGMA_LU_I))
maxu = (1 << DEFAULT_SIGMA_LU_I);
ec = (echo_can_state_t *)MALLOC(sizeof(echo_can_state_t) +
4 + /* align */
sizeof(int) * len + /* a_i */
sizeof(short) * len + /* a_s */
2 * sizeof(short) * (maxy) + /* y_s */
2 * sizeof(short) * (1 << DEFAULT_ALPHA_ST_I) + /* s_s */
2 * sizeof(short) * (maxu) + /* u_s */
2 * sizeof(short) * len); /* y_tilde_s */
if (ec) {
memset(ec, 0, sizeof(echo_can_state_t) +
4 + /* align */
sizeof(int) * len + /* a_i */
sizeof(short) * len + /* a_s */
2 * sizeof(short) * (maxy) + /* y_s */
2 * sizeof(short) * (1 << DEFAULT_ALPHA_ST_I) + /* s_s */
2 * sizeof(short) * (maxu) + /* u_s */
2 * sizeof(short) * len); /* y_tilde_s */
init_cc(ec, len, maxy, maxu);
}
return ec;
}
static inline int echo_can_traintap(echo_can_state_t *ec, int pos, short val)
{
/* Reset hang counter to avoid adjustments after
initial forced training */
ec->HCNTR_d = ec->N_d << 1;
if (pos >= ec->N_d)
return 1;
ec->a_i[pos] = val << 17;
ec->a_s[pos] = val << 1;
if (++pos >= ec->N_d)
return 1;
return 0;
}
#endif
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