LXR iproute2/netem/normal.c

   1/* SPDX-License-Identifier: NIST-PD */
   2/*
   3 * Normal distribution table generator
   4 * Taken from the uncopyrighted NISTnet code.
   5 */
   6#include <stdio.h>
   7#include <stdlib.h>
   8#include <math.h>
   9#include <string.h>
  10#include <limits.h>
  11
  12#include <linux/types.h>
  13#include <linux/pkt_sched.h>
  14
  15#define TABLESIZE 16384
  16#define TABLEFACTOR NETEM_DIST_SCALE
  17
  18static double
  19normal(double x, double mu, double sigma)
  20{
  21        return .5 + .5*erf((x-mu)/(sqrt(2.0)*sigma));
  22}
  23
  24
  25int
  26main(int argc, char **argv)
  27{
  28        int i, n;
  29        double x;
  30        double table[TABLESIZE+1];
  31
  32        for (x = -10.0; x < 10.05; x += .00005) {
  33                i = rint(TABLESIZE * normal(x, 0.0, 1.0));
  34                table[i] = x;
  35        }
  36
  37
  38        printf("# This is the distribution table for the normal distribution.\n");
  39        for (i = n = 0; i < TABLESIZE; i += 4) {
  40                int value = (int) rint(table[i]*TABLEFACTOR);
  41                if (value < SHRT_MIN) value = SHRT_MIN;
  42                if (value > SHRT_MAX) value = SHRT_MAX;
  43
  44                printf(" %d", value);
  45                if (++n == 8) {
  46                        putchar('\n');
  47                        n = 0;
  48                }
  49        }
  50
  51        return 0;
  52}
  53