osdl.net!shemminger | c2fdec5 | 2005-02-09 22:05:41 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Paretoormal distribution table generator |
| 3 | * |
| 4 | * This distribution is simply .25*normal + .75*pareto; a combination |
| 5 | * which seems to match experimentally observed distributions reasonably |
| 6 | * well, but is computationally easy to handle. |
| 7 | * The entries represent a scaled inverse of the cumulative distribution |
| 8 | * function. |
| 9 | * |
| 10 | * Taken from the uncopyrighted NISTnet code. |
| 11 | */ |
| 12 | #include <stdio.h> |
| 13 | #include <stdlib.h> |
| 14 | #include <stdlib.h> |
| 15 | #include <string.h> |
| 16 | #include <math.h> |
| 17 | #include <limits.h> |
| 18 | #include <malloc.h> |
| 19 | |
| 20 | #include <linux/types.h> |
| 21 | #include <linux/pkt_sched.h> |
| 22 | |
| 23 | #define TABLESIZE 16384 |
| 24 | #define TABLEFACTOR NETEM_DIST_SCALE |
| 25 | |
| 26 | static double |
| 27 | normal(double x, double mu, double sigma) |
| 28 | { |
| 29 | return .5 + .5*erf((x-mu)/(sqrt(2.0)*sigma)); |
| 30 | } |
| 31 | |
osdl.net!shemminger | c2fdec5 | 2005-02-09 22:05:41 +0000 | [diff] [blame] | 32 | static const double a=3.0; |
| 33 | |
| 34 | static int |
| 35 | paretovalue(int i) |
| 36 | { |
| 37 | double dvalue; |
| 38 | |
| 39 | i = 65536-4*i; |
| 40 | dvalue = (double)i/(double)65536; |
| 41 | dvalue = 1.0/pow(dvalue, 1.0/a); |
| 42 | dvalue -= 1.5; |
| 43 | dvalue *= (4.0/3.0)*(double)TABLEFACTOR; |
| 44 | if (dvalue > 32767) |
| 45 | dvalue = 32767; |
| 46 | return (int)rint(dvalue); |
| 47 | } |
| 48 | |
| 49 | int |
| 50 | main(int argc, char **argv) |
| 51 | { |
osdl.net!shemminger | c2fdec5 | 2005-02-09 22:05:41 +0000 | [diff] [blame] | 52 | int i,n; |
osdl.net!shemminger | f8f9de5 | 2005-03-30 18:11:49 +0000 | [diff] [blame] | 53 | double x; |
shemminger | 6864c1e | 2005-08-08 20:24:41 +0000 | [diff] [blame] | 54 | double table[TABLESIZE+1]; |
osdl.net!shemminger | c2fdec5 | 2005-02-09 22:05:41 +0000 | [diff] [blame] | 55 | |
| 56 | for (x = -10.0; x < 10.05; x += .00005) { |
osdl.net!shemminger | f8f9de5 | 2005-03-30 18:11:49 +0000 | [diff] [blame] | 57 | i = rint(TABLESIZE*normal(x, 0.0, 1.0)); |
osdl.net!shemminger | c2fdec5 | 2005-02-09 22:05:41 +0000 | [diff] [blame] | 58 | table[i] = x; |
| 59 | } |
| 60 | printf( |
| 61 | "# This is the distribution table for the paretonormal distribution.\n" |
| 62 | ); |
| 63 | |
| 64 | for (i = n = 0; i < TABLESIZE; i += 4) { |
| 65 | int normvalue, parvalue, value; |
| 66 | |
| 67 | normvalue = (int) rint(table[i]*TABLEFACTOR); |
| 68 | parvalue = paretovalue(i); |
| 69 | |
| 70 | value = (normvalue+3*parvalue)/4; |
| 71 | if (value < SHRT_MIN) value = SHRT_MIN; |
| 72 | if (value > SHRT_MAX) value = SHRT_MAX; |
| 73 | |
| 74 | printf(" %d", value); |
| 75 | if (++n == 8) { |
| 76 | putchar('\n'); |
| 77 | n = 0; |
| 78 | } |
| 79 | } |
osdl.net!shemminger | c2fdec5 | 2005-02-09 22:05:41 +0000 | [diff] [blame] | 80 | |
| 81 | return 0; |
| 82 | } |