====== Návrh a realizace FIR filtru ======
[[http://www.flickr.com/photos/pitel/5468520017|{{ http://farm6.static.flickr.com/5058/5468520017_39b43b07c9_z.jpg |FIR filter}}]]
<file make Makefile>CC=gcc
RM=rm -f
CFLAGS=-O2 -pipe -pedantic-errors -Wall -Wextra -march=native -fomit-frame-pointer -std=c99

all: gen fir

.PHONY: clean

gen: gen.c
	$(CC) $(CFLAGS) -lm -D_GNU_SOURCE $< -o $@

fir: fir.c
	$(CC) $(CFLAGS) $< -o $@

clean:
	$(RM) *.raw fir gen

run: all
	./gen | tee original.raw | ./fir > filtered.raw

plot: run
	gnuplot plot.gnu</file>
<file c gen.c>#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#define SR 44100
#define freq1 1000
#define freq2 10000
#define samples 100000

int main(/*int argc, char *argv[]*/) {
	for (size_t sample = 0; sample < samples; sample++) {
		printf ("%f\n", sin(2 * M_PI * freq1 * sample / SR) / 2 + sin(2 * M_PI * freq2 * sample / SR) / 2);
	}
	return EXIT_SUCCESS;
}</file>
<file c fir.c>#include <stdlib.h>
#include <stdio.h>
#include <strings.h>

int main() {
	const float coeff[] = {.1, .1, .09, .09, .08, .06, .05, .04, .02, .01, 0, -.01, -.02, -.02, -.02, -.02, -.02, -.02, -.01, -.01, 0, 0, .01, .01, .01, .01, .01, .01, .01, 1};	//Jednicka je zarazka!
	
	size_t coefs = 0;
	while (coeff[++coefs] < 1);	//Pocet koeficientu
	
	float history[coefs];
	bzero(&history, coefs * sizeof(float));	//Vynulovani
	
	float x;
	while (scanf("%f", &x) != EOF) {
		//printf("%f\n", x);
		
		//Posun prvku v poli
		for (size_t i = coefs; i > 0; i--) {
			history[i] = history[i - 1];
		}
		history[0] = x;
		//printa(history, coefs);
		
		//FIR
		float out = 0;
		for (size_t i = 0; i < coefs; i++) {
			out += history[i] * coeff[i];
		}
		
		printf("%f\n", out);
	}
	return EXIT_SUCCESS;
}</file>
<file gnuplot plot.gnu>plot [0:500] "original.raw" with lines, "filtered.raw" with lines
pause -1</file>