LXR iproute2/netem/normal.c

   1/*
   2 * Normal distribution table generator
   3 * Taken from the uncopyrighted NISTnet code.
   4 */
   5#include <stdio.h>
   6#include <stdlib.h>
   7#include <math.h>
   8#include <string.h>
   9#include <limits.h>
  10
  11#include <linux/types.h>
  12#include <linux/pkt_sched.h>
  13
  14#define TABLESIZE 16384
  15#define TABLEFACTOR NETEM_DIST_SCALE
  16
  17static double
  18normal(double x, double mu, double sigma)
  19{
  20        return .5 + .5*erf((x-mu)/(sqrt(2.0)*sigma));
  21}
  22
  23
  24int
  25main(int argc, char **argv)
  26{
  27        int i, n;
  28        double x;
  29        double table[TABLESIZE+1];
  30
  31        for (x = -10.0; x < 10.05; x += .00005) {
  32                i = rint(TABLESIZE * normal(x, 0.0, 1.0));
  33                table[i] = x;
  34        }
  35
  36
  37        printf("# This is the distribution table for the normal distribution.\n");
  38        for (i = n = 0; i < TABLESIZE; i += 4) {
  39                int value = (int) rint(table[i]*TABLEFACTOR);
  40                if (value < SHRT_MIN) value = SHRT_MIN;
  41                if (value > SHRT_MAX) value = SHRT_MAX;
  42
  43                printf(" %d", value);
  44                if (++n == 8) {
  45                        putchar('\n');
  46                        n = 0;
  47                }
  48        }
  49
  50        return 0;
  51}
  52