osdl.net!shemminger | dfe6094 | 2005-02-09 22:05:41 +0000 | [diff] [blame^] | 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 | |
| 17 | static double |
| 18 | normal(double x, double mu, double sigma) |
| 19 | { |
| 20 | return .5 + .5*erf((x-mu)/(sqrt(2.0)*sigma)); |
| 21 | } |
| 22 | |
| 23 | int |
| 24 | main(int argc, char **argv) |
| 25 | { |
| 26 | double x, *table; |
| 27 | int i, n; |
| 28 | |
| 29 | table = calloc(sizeof(double), TABLESIZE+1); |
| 30 | if (!table) { |
| 31 | fprintf(stderr, "Not enough memory\n"); |
| 32 | return 1; |
| 33 | } |
| 34 | |
| 35 | |
| 36 | for (x = -10.0; x < 10.05; x += .00005) { |
| 37 | i = (int)rint(TABLESIZE*normal(x, 0.0, 1.0)); |
| 38 | table[i] = x; |
| 39 | } |
| 40 | |
| 41 | |
| 42 | printf("# This is the distribution table for the normal distribution.\n"); |
| 43 | for (i = n = 0; i < TABLESIZE; i += 4) { |
| 44 | int value = (int) rint(table[i]*TABLEFACTOR); |
| 45 | if (value < SHRT_MIN) value = SHRT_MIN; |
| 46 | if (value > SHRT_MAX) value = SHRT_MAX; |
| 47 | |
| 48 | printf(" %d", value); |
| 49 | if (++n == 8) { |
| 50 | putchar('\n'); |
| 51 | n = 0; |
| 52 | } |
| 53 | } |
| 54 | free(table); |
| 55 | return 0; |
| 56 | } |