Allow variable tablesize.

2004/08/10 10:46:18-07:00 osdl.net!shemminger
Rename: tc/dist_paretonormal.c -> tc/paretonormal.c

(Logical change 1.71)

1 files changed, 90 insertions, 0 deletions

diff --git a/tc/paretonormal.c b/tc/paretonormal.c
index e69de29b..d6c5273d 100644
--- a/tc/paretonormal.c
+++ b/tc/paretonormal.c
@@ -0,0 +1,90 @@
+/*
+ * Paretoormal distribution table generator
+ *
+ * This distribution is simply .25*normal + .75*pareto; a combination
+ * which seems to match experimentally observed distributions reasonably
+ *  well, but is computationally easy to handle.
+ * The entries represent a scaled inverse of the cumulative distribution
+ * function.
+ *
+ * Taken from the uncopyrighted NISTnet code.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <limits.h>
+#include <malloc.h>
+
+#include <linux/types.h>
+#include <linux/pkt_sched.h>
+
+#define TABLESIZE	16384
+#define TABLEFACTOR	TCA_NETEM_TABLEFACTOR
+
+static double
+normal(double x, double mu, double sigma)
+{
+	return .5 + .5*erf((x-mu)/(sqrt(2.0)*sigma));
+}
+
+
+static const double a=3.0;
+
+static int
+paretovalue(int i)
+{
+	double dvalue;
+
+	i = 65536-4*i;
+	dvalue = (double)i/(double)65536;
+	dvalue = 1.0/pow(dvalue, 1.0/a);
+	dvalue -= 1.5;
+	dvalue *= (4.0/3.0)*(double)TABLEFACTOR;
+	if (dvalue > 32767)
+		dvalue = 32767;
+	return (int)rint(dvalue);
+}	
+
+int
+main(int argc, char **argv)
+{
+	double x;
+	double *table;
+	int i,n;
+
+	table = calloc(TABLESIZE, sizeof(double));
+	if (!table) {
+		fprintf(stderr, "Out of memory!\n");
+		exit(1);
+	}
+
+	for (x = -10.0; x < 10.05; x += .00005) {
+		i = (int)rint(TABLESIZE*normal(x, 0.0, 1.0));
+		table[i] = x;
+	}
+	printf(
+"# This is the distribution table for the paretonormal distribution.\n"
+	);
+
+	for (i = n = 0; i < TABLESIZE; i += 4) {
+		int normvalue, parvalue, value;
+
+		normvalue = (int) rint(table[i]*TABLEFACTOR);
+		parvalue = paretovalue(i);
+
+		value = (normvalue+3*parvalue)/4;
+		if (value < SHRT_MIN) value = SHRT_MIN;
+		if (value > SHRT_MAX) value = SHRT_MAX;
+
+		printf(" %d", value);
+		if (++n == 8) {
+			putchar('\n');
+			n = 0;
+		}
+	}
+	free(table);
+
+	return 0;
+}