start changing T-ramp code (old was too ugly)

LibSidServo/movingfilter.c

@@ -0,0 +1,46 @@
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define NFILT	(5)
+
+static double filterK[NFILT];
+
+static void buildFilter(){
+	filterK[NFILT-1] = 1.;
+	double sum = 1.;
+	for(int i = NFILT-2; i > -1; --i){
+		filterK[i] = (filterK[i+1] + 1.) * 1.1;
+		sum += filterK[i];
+	}
+	for(int i = 0; i < NFILT; ++i){
+		filterK[i] /= sum;
+		fprintf(stderr, "%d: %g\n", i, filterK[i]);
+	}
+}
+
+static double filter(double val){
+	static int ctr = 0;
+	static double lastvals[NFILT] = {0.};
+	for(int i = NFILT-1; i > 0; --i) lastvals[i] = lastvals[i-1];
+	lastvals[0] = val;
+	double r = 0.;
+	if(ctr < NFILT){
+		++ctr;
+		return val;
+	}
+	for(int i = 0; i < NFILT; ++i) r += filterK[i] * lastvals[i];
+	return r;
+}
+
+int main(int argc, char **argv){
+	buildFilter();
+	printf("Signal\tNoiced\tFiltered\n");
+	for(int i = 0; i < 100; ++i){
+		double di = (double)i;
+		double sig = di * di / 1e5 + sin(i * M_PI / 1500.);
+		double noiced = sig + 0.1 * (drand48() - 0.5);
+		printf("%.3f\t%.3f\t%.3f\n", sig, noiced, filter(noiced));
+	}
+	return 0;
+}