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/*
* filter.c
*
* Copyright (c) 2018 Disi A
*
* Author: Disi A
* Email: adis@live.cn
* https://www.mathworks.com/matlabcentral/profile/authors/3734620-disi-a
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include "filter.h"
#include <stddef.h>
#if DOUBLE_PRECISION
#define COS cos
#define SIN sin
#define TAN tan
#define COSH cosh
#define SINH sinh
#define SQRT sqrt
#define LOG log
#else
#define COS cosf
#define SIN sinf
#define TAN tanf
#define COSH coshf
#define SINH sinhf
#define SQRT sqrtf
#define LOG logf
#endif
void update_bw_low_pass_filter(BWLowPass* filter, FTR_PRECISION s, FTR_PRECISION f, FTR_PRECISION q)
{
FTR_PRECISION a = TAN((FTR_PRECISION)(M_PI * f / s));
FTR_PRECISION a2 = a * a;
FTR_PRECISION r;
int i;
for(i=0; i < filter -> n; ++i){
r = SIN((FTR_PRECISION)(M_PI * (2.0 * i + 1.0) / (4.0 * filter->n)));
s = (FTR_PRECISION) (a2 + 2.0 * a * r + 1.0);
filter->A[i] = a2 / s;
filter->d1[i] = (FTR_PRECISION) (2.0 * (1 - a2) / s);
filter->d2[i] = (FTR_PRECISION)(-(a2 - 2.0 * a * r + 1.0) / s);
}
}
BWLowPass* create_bw_low_pass_filter(int order, FTR_PRECISION s, FTR_PRECISION f) {
BWLowPass* filter = (BWLowPass *) malloc(sizeof(BWLowPass));
filter -> n = order/2;
filter -> A = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d1 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d2 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> w0 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w1 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w2 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
if (filter->d2 == NULL)
{
free_bw_low_pass(filter);
return NULL;
}
FTR_PRECISION a = TAN((FTR_PRECISION)(M_PI * f / s));
FTR_PRECISION a2 = a * a;
FTR_PRECISION r;
int i;
for(i=0; i < filter -> n; ++i){
r = SIN((FTR_PRECISION)(M_PI * (2.0 * i + 1.0) / (4.0 * filter->n)));
s = (FTR_PRECISION) (a2 + 2.0 * a * r + 1.0);
filter->A[i] = a2 / s;
filter->d1[i] = (FTR_PRECISION) (2.0 * (1 - a2) / s);
filter->d2[i] = (FTR_PRECISION)(-(a2 - 2.0 * a * r + 1.0) / s);
}
return filter;
}
BWHighPass* create_bw_high_pass_filter(int order, FTR_PRECISION s, FTR_PRECISION f){
BWHighPass* filter = (BWHighPass *) malloc(sizeof(BWHighPass));
filter -> n = order/2;
filter -> A = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d1 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d2 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> w0 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w1 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w2 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
if (filter->d2 == NULL)
{
free_bw_high_pass(filter);
return NULL;
}
FTR_PRECISION a = TAN((FTR_PRECISION) (M_PI * f/s));
FTR_PRECISION a2 = a * a;
FTR_PRECISION r;
int i;
for(i=0; i < filter -> n; ++i){
r = SIN((FTR_PRECISION)(M_PI * (2.0 * i + 1.0) / ( 4.0 * filter->n)));
s = (FTR_PRECISION) (a2 + 2.0 * a * r + 1.0);
filter -> A[i] = (FTR_PRECISION) (1.0 / s);
filter -> d1[i] = (FTR_PRECISION) (2.0 * (1 - a2) / s);
filter -> d2[i] = (FTR_PRECISION) (- (a2 - 2.0 * a * r + 1.0) / s);
}
return filter;
}
BWBandPass* create_bw_band_pass_filter(int order, FTR_PRECISION s, FTR_PRECISION fl, FTR_PRECISION fu){
if(fu <= fl){
printf("ERROR:Lower half-power frequency is smaller than higher half-power frequency");
return NULL;
}
BWBandPass* filter = (BWBandPass *) malloc(sizeof(BWBandPass));
filter -> n = order/4;
filter -> A = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d1 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d2 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d3 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d4 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> w0 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w1 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w2 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w3 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w4 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
FTR_PRECISION a = COS(M_PI*(fu+fl)/s)/COS(M_PI*(fu-fl)/s);
FTR_PRECISION a2 = a*a;
FTR_PRECISION b = TAN(M_PI*(fu-fl)/s);
FTR_PRECISION b2 = b*b;
FTR_PRECISION r;
int i;
for(i=0; i<filter->n; ++i){
r = SIN( (FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / (4.0 * filter->n)));
s = (FTR_PRECISION)(b2 + 2.0 * b * r + 1.0);
filter->A[i] = b2/s;
filter->d1[i] = (FTR_PRECISION) (4.0 * a * (1.0 + b * r) / s);
filter->d2[i] = (FTR_PRECISION) (2.0 * (b2 - 2.0 * a2 - 1.0)/ s);
filter->d3[i] = (FTR_PRECISION) (4.0 * a * (1.0 - b * r ) / s);
filter->d4[i] = (FTR_PRECISION) (- (b2 - 2.0 * b * r + 1.0) / s);
}
return filter;
}
BWBandStop* create_bw_band_stop_filter(int order, FTR_PRECISION s, FTR_PRECISION fl, FTR_PRECISION fu){
if(fu <= fl){
printf("ERROR:Lower half-power frequency is smaller than higher half-power frequency");
return NULL;
}
BWBandStop* filter = (BWBandStop *) malloc(sizeof(BWBandStop));
filter -> n = order/4;
filter -> A = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d1 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d2 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d3 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> d4 = (FTR_PRECISION *)malloc(filter -> n*sizeof(FTR_PRECISION));
filter -> w0 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w1 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w2 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w3 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
filter -> w4 = (FTR_PRECISION *)calloc(filter -> n, sizeof(FTR_PRECISION));
FTR_PRECISION a = COS(M_PI*(fu+fl)/s)/COS(M_PI*(fu-fl)/s);
FTR_PRECISION a2 = a*a;
FTR_PRECISION b = TAN(M_PI*(fu-fl)/s);
FTR_PRECISION b2 = b*b;
FTR_PRECISION r;
int i;
for(i=0; i<filter->n; ++i){
r = SIN((FTR_PRECISION) (M_PI * (2.0 * i + 1.0 ) / ( 4.0 * filter->n)));
s = (FTR_PRECISION) (b2 + 2.0 * b * r + 1.0);
filter->A[i] = (FTR_PRECISION) (1.0 / s);
filter->d1[i] = (FTR_PRECISION) (4.0 * a * (1.0 + b * r ) / s);
filter->d2[i] = (FTR_PRECISION) (2.0 * (b2 - 2.0 * a2- 1.0) / s);
filter->d3[i] = (FTR_PRECISION) (4.0 * a * (1.0 - b * r) / s);
filter->d4[i] = (FTR_PRECISION) (- (b2 - 2.0 * b * r + 1.0) / s);
}
filter->r = (FTR_PRECISION) (4.0 * a);
filter->s = (FTR_PRECISION) (4.0 * a2 + 2.0);
return filter;
}
CHELowPass* create_che_low_pass_filter(int n, FTR_PRECISION epsilon, FTR_PRECISION s, FTR_PRECISION f){
CHELowPass* filter = (CHELowPass *) malloc(sizeof(CHELowPass));
filter -> m = n/2;
filter -> A = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d1 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d2 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> w0 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w1 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w2 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
if (filter->d2 == NULL)
{
free_che_low_pass(filter);
return NULL;
}
FTR_PRECISION a = TAN((FTR_PRECISION) (M_PI * f/ s));
FTR_PRECISION a2 = a * a;
FTR_PRECISION u = LOG((FTR_PRECISION) (1.0 + SQRT((FTR_PRECISION) (1.0 + epsilon * epsilon)) / epsilon));
FTR_PRECISION su = SINH(u/(FTR_PRECISION)n);
FTR_PRECISION cu = COSH(u/(FTR_PRECISION)n);
FTR_PRECISION b,c;
int i;
for(i=0; i<filter->m; ++i){
b = SIN((FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / (2.0 * n))) * su;
c = COS((FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / (2.0 * n))) * cu;
c = b*b + c*c;
s = (FTR_PRECISION) (a2 * c + 2.0 * a * b + 1.0);
filter->A[i] = (FTR_PRECISION) (a2 / (4.0 * s));
filter->d1[i] = (FTR_PRECISION) (2.0 * (1 - a2 * c) / s);
filter->d2[i] = (FTR_PRECISION) (- (a2 * c - 2.0 * a * b + 1.0) / s);
}
filter->ep = (FTR_PRECISION) (2.0 / epsilon); // used to normalize
return filter;
}
CHEHighPass* create_che_high_pass_filter(int n, FTR_PRECISION epsilon, FTR_PRECISION s, FTR_PRECISION f){
CHEHighPass* filter = (CHELowPass *) malloc(sizeof(CHEHighPass));
filter -> m = n/2;
filter -> A = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d1 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d2 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> w0 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w1 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w2 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
if (filter->d2 == NULL)
{
free_che_high_pass(filter);
return NULL;
}
FTR_PRECISION a = TAN((FTR_PRECISION) (M_PI * f/ s));
FTR_PRECISION a2 = a * a;
FTR_PRECISION u = LOG((FTR_PRECISION) (1.0 + SQRT((FTR_PRECISION) (1.0 + epsilon*epsilon))) / epsilon);
FTR_PRECISION su = SINH(u/(FTR_PRECISION)n);
FTR_PRECISION cu = COSH(u/(FTR_PRECISION)n);
FTR_PRECISION b,c;
int i;
for(i=0; i<filter->m; ++i){
b = SIN((FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / (2.0 * n))) * su;
c = COS((FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / (2.0 * n))) * cu;
c = b*b + c*c;
s = (FTR_PRECISION) (a2 + 2.0 * a * b + c);
filter->A[i] = (FTR_PRECISION) (1.0 / (4.0 * s));
filter->d1[i] = (FTR_PRECISION) (2.0 * (c - a2)/s);
filter->d2[i] = (FTR_PRECISION) (- (a2 - 2.0 * a * b + c) / s);
}
filter->ep = (FTR_PRECISION) (2.0 / epsilon); // used to normalize
return filter;
}
CHEBandPass* create_che_band_pass_filter(int n, FTR_PRECISION epsilon, FTR_PRECISION s, FTR_PRECISION f_lower, FTR_PRECISION f_upper){
CHEBandPass* filter = (CHEBandPass *) malloc(sizeof(CHEBandPass));
filter -> m = n/4;
filter -> A = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d1 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d2 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d3 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d4 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> w0 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w1 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w2 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w3 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w4 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
FTR_PRECISION a = COS(M_PI*(f_lower+f_upper)/s)/COS(M_PI*(f_upper-f_lower)/s);
FTR_PRECISION a2 = a*a;
FTR_PRECISION b = TAN(M_PI*(f_upper-f_lower)/s);
FTR_PRECISION b2 = b*b;
FTR_PRECISION u = LOG((FTR_PRECISION) (1.0 + SQRT((FTR_PRECISION) (1.0 + epsilon * epsilon))) / epsilon);
FTR_PRECISION su = SINH((FTR_PRECISION) (2.0 * u / (FTR_PRECISION)n));
FTR_PRECISION cu = COSH((FTR_PRECISION) (2.0 * u / (FTR_PRECISION)n));
FTR_PRECISION r,c;
int i;
for(i=0; i < filter->m; ++i){
r = SIN((FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / n)) * su;
c = COS((FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / n)) * cu;
c = r*r + c*c;
s = (FTR_PRECISION) (b2 * c + 2.0 * b * r + 1.0);
filter->A[i] = (FTR_PRECISION) (b2 / (4.0 * s));
filter->d1[i] = (FTR_PRECISION) (4.0 * a * (1.0 + b * r) / s);
filter->d2[i] = (FTR_PRECISION) (2.0 * (b2 * c - 2.0 * a2 - 1.0) / s);
filter->d3[i] = (FTR_PRECISION) (4.0 * a * (1.0 - b * r) / s);
filter->d4[i] = (FTR_PRECISION) (- (b2 * c - 2.0 * b * r + 1.0) / s);
}
filter->ep = (FTR_PRECISION) (2.0 / epsilon); // used to normalize
return filter;
}
CHEBandStop* create_che_band_stop_filter(int n, FTR_PRECISION epsilon, FTR_PRECISION s, FTR_PRECISION f_lower, FTR_PRECISION f_upper){
CHEBandStop* filter = (CHEBandStop *) malloc(sizeof(CHEBandStop));
filter -> m = n/4;
filter -> A = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d1 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d2 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d3 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> d4 = (FTR_PRECISION *)malloc(filter -> m*sizeof(FTR_PRECISION));
filter -> w0 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w1 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w2 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w3 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
filter -> w4 = (FTR_PRECISION *)calloc(filter -> m, sizeof(FTR_PRECISION));
FTR_PRECISION a = COS(M_PI*(f_lower+f_upper)/s)/COS(M_PI*(f_upper-f_lower)/s);
FTR_PRECISION a2 = a*a;
FTR_PRECISION b = TAN(M_PI*(f_upper-f_lower)/s);
FTR_PRECISION b2 = b*b;
FTR_PRECISION u = LOG((FTR_PRECISION) (1.0 + SQRT((FTR_PRECISION) (1.0 + epsilon * epsilon))) / epsilon);
FTR_PRECISION su = SINH((FTR_PRECISION) (2.0*u/(FTR_PRECISION)n));
FTR_PRECISION cu = COSH((FTR_PRECISION) (2.0*u/(FTR_PRECISION)n));
FTR_PRECISION r,c;
int i;
for(i=0; i < filter->m; ++i){
r = SIN((FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / n)) * su;
c = COS((FTR_PRECISION) (M_PI * (2.0 * i + 1.0) / n))*cu;
c = r*r + c*c;
s = (FTR_PRECISION) (b2 + 2.0 * b * r + c);
filter->A[i] = (FTR_PRECISION) (1.0 / (4.0 * s));
filter->d1[i] = (FTR_PRECISION) (4.0 * a * (c + b * r)/s);
filter->d2[i] = (FTR_PRECISION) (2.0 * (b2 - 2.0 * a2 * c - c) / s);
filter->d3[i] = (FTR_PRECISION) (4.0 * a * (c - b * r ) / s);
filter->d4[i] = (FTR_PRECISION) (- (b2 - 2.0 * b * r + c) / s);
}
filter->r = (FTR_PRECISION) (4.0 * a);
filter->s = (FTR_PRECISION) (4.0 * a2 + 2.0);
filter->ep = (FTR_PRECISION) (2.0 / epsilon); // used to normalize
return filter;
}
void free_bw_low_pass(BWLowPass* filter){
free(filter -> A);
free(filter -> d1);
free(filter -> d2);
free(filter -> w0);
free(filter -> w1);
free(filter -> w2);
free(filter);
}
void free_bw_high_pass(BWHighPass* filter){
free(filter -> A);
free(filter -> d1);
free(filter -> d2);
free(filter -> w0);
free(filter -> w1);
free(filter -> w2);
free(filter);
}
void free_bw_band_pass(BWBandPass* filter){
free(filter -> A);
free(filter -> d1);
free(filter -> d2);
free(filter -> d3);
free(filter -> d4);
free(filter -> w0);
free(filter -> w1);
free(filter -> w2);
free(filter -> w3);
free(filter -> w4);
free(filter);
}
void free_bw_band_stop(BWBandStop* filter){
free(filter -> A);
free(filter -> d1);
free(filter -> d2);
free(filter -> d3);
free(filter -> d4);
free(filter -> w0);
free(filter -> w1);
free(filter -> w2);
free(filter -> w3);
free(filter -> w4);
free(filter);
}
void free_che_low_pass(CHELowPass* filter){
free(filter -> A);
free(filter -> d1);
free(filter -> d2);
free(filter -> w0);
free(filter -> w1);
free(filter -> w2);
free(filter);
}
void free_che_high_pass(CHEHighPass* filter){
free(filter -> A);
free(filter -> d1);
free(filter -> d2);
free(filter -> w0);
free(filter -> w1);
free(filter -> w2);
free(filter);
}
void free_che_band_pass(CHEBandPass* filter){
free(filter -> A);
free(filter -> d1);
free(filter -> d2);
free(filter -> d3);
free(filter -> d4);
free(filter -> w0);
free(filter -> w1);
free(filter -> w2);
free(filter -> w3);
free(filter -> w4);
free(filter);
}
void free_che_band_stop(CHEBandStop* filter){
free(filter -> A);
free(filter -> d1);
free(filter -> d2);
free(filter -> d3);
free(filter -> d4);
free(filter -> w0);
free(filter -> w1);
free(filter -> w2);
free(filter -> w3);
free(filter -> w4);
free(filter);
}
FTR_PRECISION bw_low_pass(BWLowPass* filter, FTR_PRECISION x){
int i;
for(i=0; i<filter->n; ++i){
filter->w0[i] = filter->d1[i]*filter->w1[i] + filter->d2[i]*filter->w2[i] + x;
x = filter->A[i] * (filter->w0[i] + 2.0f * filter->w1[i] + filter->w2[i]);
filter->w2[i] = filter->w1[i];
filter->w1[i] = filter->w0[i];
}
return x;
}
FTR_PRECISION bw_high_pass(BWHighPass* filter, FTR_PRECISION x){
int i;
for(i=0; i<filter->n; ++i){
filter->w0[i] = filter->d1[i]*filter->w1[i] + filter->d2[i]*filter->w2[i] + x;
x = filter->A[i] * (filter->w0[i] - 2.0f * filter->w1[i] + filter->w2[i]);
filter->w2[i] = filter->w1[i];
filter->w1[i] = filter->w0[i];
}
return x;
}
FTR_PRECISION bw_band_pass(BWBandPass* filter, FTR_PRECISION x){
int i;
for(i=0; i<filter->n; ++i){
filter->w0[i] = filter->d1[i]*filter->w1[i] + filter->d2[i]*filter->w2[i]+ filter->d3[i]*filter->w3[i]+ filter->d4[i]*filter->w4[i] + x;
x = filter->A[i] * (filter->w0[i] - 2.0f * filter->w2[i] + filter->w4[i]);
filter->w4[i] = filter->w3[i];
filter->w3[i] = filter->w2[i];
filter->w2[i] = filter->w1[i];
filter->w1[i] = filter->w0[i];
}
return x;
}
FTR_PRECISION bw_band_stop(BWBandStop* filter, FTR_PRECISION x){
int i;
for(i=0; i<filter->n; ++i){
filter->w0[i] = filter->d1[i]*filter->w1[i] + filter->d2[i]*filter->w2[i]+ filter->d3[i]*filter->w3[i]+ filter->d4[i]*filter->w4[i] + x;
x = filter->A[i]*(filter->w0[i] - filter->r*filter->w1[i] + filter->s*filter->w2[i]- filter->r*filter->w3[i] + filter->w4[i]);
filter->w4[i] = filter->w3[i];
filter->w3[i] = filter->w2[i];
filter->w2[i] = filter->w1[i];
filter->w1[i] = filter->w0[i];
}
return x;
}
FTR_PRECISION che_low_pass(CHELowPass* filter, FTR_PRECISION x){
int i;
for(i=0; i<filter->m; ++i){
filter->w0[i] = filter->d1[i]*filter->w1[i] + filter->d2[i]*filter->w2[i] + x;
x = filter->A[i] * (filter->w0[i] + 2.0f * filter->w1[i] + filter->w2[i]);
filter->w2[i] = filter->w1[i];
filter->w1[i] = filter->w0[i];
}
return x * filter->ep;
}
FTR_PRECISION che_high_pass(CHEHighPass* filter, FTR_PRECISION x){
int i;
for(i=0; i<filter->m; ++i){
filter->w0[i] = filter->d1[i]*filter->w1[i] + filter->d2[i]*filter->w2[i] + x;
x = filter->A[i] * (filter->w0[i] - 2.0f * filter->w1[i] + filter->w2[i]);
filter->w2[i] = filter->w1[i];
filter->w1[i] = filter->w0[i];
}
return x * filter->ep;
}
FTR_PRECISION che_band_pass(CHEBandPass* filter, FTR_PRECISION x){
int i;
for(i=0; i<filter->m; ++i){
filter->w0[i] = filter->d1[i]*filter->w1[i] + filter->d2[i]*filter->w2[i]+ filter->d3[i]*filter->w3[i]+ filter->d4[i]*filter->w4[i] + x;
x = filter->A[i] * (filter->w0[i] - 2.0f * filter->w2[i] + filter->w4[i]);
filter->w4[i] = filter->w3[i];
filter->w3[i] = filter->w2[i];
filter->w2[i] = filter->w1[i];
filter->w1[i] = filter->w0[i];
}
return x * filter->ep;
}
FTR_PRECISION che_band_stop(CHEBandStop* filter, FTR_PRECISION x){
int i;
for(i=0; i<filter->m; ++i){
filter->w0[i] = filter->d1[i]*filter->w1[i] + filter->d2[i]*filter->w2[i]+ filter->d3[i]*filter->w3[i]+ filter->d4[i]*filter->w4[i] + x;
x = filter->A[i]*(filter->w0[i] - filter->r*filter->w1[i] + filter->s*filter->w2[i]- filter->r*filter->w3[i] + filter->w4[i]);
filter->w4[i] = filter->w3[i];
filter->w3[i] = filter->w2[i];
filter->w2[i] = filter->w1[i];
filter->w1[i] = filter->w0[i];
}
return x * filter->ep;
}
FTR_PRECISION softmax(FTR_PRECISION* data, int size, int target_ind){
FTR_PRECISION sum = 0;
for(int i = 0; i < size; i++) sum += data[i];
return data[target_ind]/sum;
}
static const FTR_PRECISION SPIKE_KERNEL[] = {-1.0, 2.0, -1.0};
void spike_filter_upward(FTR_PRECISION * input, int size, FTR_PRECISION * output, FTR_PRECISION strength){
FTR_PRECISION mean = 0.0;
FTR_PRECISION std = 0.0;
FTR_PRECISION diff = 0.0;
for(int i=0; i < size; i++) mean += input[i];
mean /= size;
for(int i=0; i < size; i++){
diff = input[i] - mean;
std += diff * diff;
}
std = SQRT(std/size);
output[0] = 0.0;
output[size - 1] = 0.0;
for(int i=1; i<size-1; i++){
FTR_PRECISION val = input[i-1] * SPIKE_KERNEL[0] + input[i] * SPIKE_KERNEL[1] + input[i+1] * SPIKE_KERNEL[2];
if(val < strength * std) output[i] = 0.0;
else output[i] = val;
}
}
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