diff --git a/netem/normal.c b/netem/normal.c index e69de29b..e6683db8 100644 --- a/netem/normal.c +++ b/netem/normal.c @@ -0,0 +1,56 @@ +/* + * Normal distribution table generator + * Taken from the uncopyrighted NISTnet code. + */ +#include +#include +#include +#include +#include + +#include +#include + +#define TABLESIZE 16384 +#define TABLEFACTOR NETEM_DIST_SCALE + +static double +normal(double x, double mu, double sigma) +{ + return .5 + .5*erf((x-mu)/(sqrt(2.0)*sigma)); +} + +int +main(int argc, char **argv) +{ + double x, *table; + int i, n; + + table = calloc(sizeof(double), TABLESIZE+1); + if (!table) { + fprintf(stderr, "Not enough memory\n"); + return 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 normal distribution.\n"); + for (i = n = 0; i < TABLESIZE; i += 4) { + int value = (int) rint(table[i]*TABLEFACTOR); + 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; +}