mirror of
https://github.com/zeek/zeek.git
synced 2025-10-02 14:48:21 +00:00
f5a76c1aed
This largely copies over Spicy's `.clang-format` configuration file. The one place where we deviate is header include order since Zeek depends on headers being included in a certain order.
133 lines
3.8 KiB
C++
133 lines
3.8 KiB
C++
/*
|
|
Apply various randomness tests to a stream of bytes
|
|
|
|
by John Walker -- September 1996
|
|
http://www.fourmilab.ch/random
|
|
|
|
This software is in the public domain. Permission to use, copy, modify,
|
|
and distribute this software and its documentation for any purpose and
|
|
without fee is hereby granted, without any conditions or restrictions.
|
|
This software is provided “as is” without express or implied warranty.
|
|
|
|
Modified for Zeek/Bro by Seth Hall - July 2010
|
|
*/
|
|
|
|
#include "zeek/RandTest.h"
|
|
|
|
#include <cmath>
|
|
|
|
constexpr double log2of10 = 3.32192809488736234787;
|
|
|
|
/* RT_LOG2 -- Calculate log to the base 2 */
|
|
static double rt_log2(double x) { return log2of10 * log10(x); }
|
|
|
|
// RT_INCIRC = pow(pow(256.0, (double) (RT_MONTEN / 2)) - 1, 2.0);
|
|
constexpr double RT_INCIRC = 281474943156225.0;
|
|
|
|
namespace zeek::detail {
|
|
|
|
RandTest::RandTest() {
|
|
totalc = 0;
|
|
mp = 0;
|
|
sccfirst = 1;
|
|
inmont = mcount = 0;
|
|
cexp = montex = montey = montepi = sccu0 = scclast = scct1 = scct2 = scct3 = 0.0;
|
|
|
|
for ( int i = 0; i < 256; i++ ) {
|
|
ccount[i] = 0;
|
|
}
|
|
}
|
|
|
|
void RandTest::add(const void* buf, int bufl) {
|
|
const unsigned char* bp = static_cast<const unsigned char*>(buf);
|
|
int oc;
|
|
|
|
while ( bufl-- > 0 ) {
|
|
oc = *bp++;
|
|
ccount[oc]++; /* Update counter for this bin */
|
|
totalc++;
|
|
|
|
/* Update inside / outside circle counts for Monte Carlo
|
|
computation of PI */
|
|
monte[mp++] = oc; /* Save character for Monte Carlo */
|
|
if ( mp >= RT_MONTEN ) /* Calculate every RT_MONTEN character */
|
|
{
|
|
mp = 0;
|
|
mcount++;
|
|
montex = 0;
|
|
montey = 0;
|
|
for ( int mj = 0; mj < RT_MONTEN / 2; mj++ ) {
|
|
montex = (montex * 256.0) + monte[mj];
|
|
montey = (montey * 256.0) + monte[(RT_MONTEN / 2) + mj];
|
|
}
|
|
if ( montex * montex + montey * montey <= RT_INCIRC ) {
|
|
inmont++;
|
|
}
|
|
}
|
|
|
|
/* Update calculation of serial correlation coefficient */
|
|
if ( sccfirst ) {
|
|
sccfirst = 0;
|
|
sccu0 = oc;
|
|
}
|
|
else {
|
|
scct1 = scct1 + scclast * oc;
|
|
}
|
|
|
|
scct2 = scct2 + oc;
|
|
scct3 = scct3 + (oc * oc);
|
|
scclast = oc;
|
|
oc <<= 1;
|
|
}
|
|
}
|
|
|
|
void RandTest::end(double* r_ent, double* r_chisq, double* r_mean, double* r_montepicalc, double* r_scc) {
|
|
int i;
|
|
double ent = 0.0;
|
|
double chisq = 0.0;
|
|
double datasum = 0.0;
|
|
double prob[256]; /* Probabilities per bin for entropy */
|
|
|
|
/* Complete calculation of serial correlation coefficient */
|
|
scct1 = scct1 + scclast * sccu0;
|
|
scct2 = scct2 * scct2;
|
|
double scc = totalc * scct3 - scct2;
|
|
if ( scc == 0.0 )
|
|
scc = -100000;
|
|
else
|
|
scc = (totalc * scct1 - scct2) / scc;
|
|
|
|
/* Scan bins and calculate probability for each bin and
|
|
Chi-Square distribution. The probability will be reused
|
|
in the entropy calculation below. While we're at it,
|
|
we sum of all the data which will be used to compute the
|
|
mean. */
|
|
cexp = totalc / 256.0; /* Expected count per bin */
|
|
for ( i = 0; i < 256; i++ ) {
|
|
double a = ccount[i] - cexp;
|
|
|
|
prob[i] = ((double)ccount[i]) / totalc;
|
|
chisq += (a * a) / cexp;
|
|
datasum += ((double)i) * ccount[i];
|
|
}
|
|
|
|
/* Calculate entropy */
|
|
for ( i = 0; i < 256; i++ ) {
|
|
if ( prob[i] > 0.0 ) {
|
|
ent += prob[i] * rt_log2(1 / prob[i]);
|
|
}
|
|
}
|
|
|
|
/* Calculate Monte Carlo value for PI from percentage of hits
|
|
within the circle */
|
|
montepi = mcount == 0 ? 0 : 4.0 * (((double)inmont) / mcount);
|
|
|
|
/* Return results through arguments */
|
|
*r_ent = ent;
|
|
*r_chisq = chisq;
|
|
*r_mean = datasum / totalc;
|
|
*r_montepicalc = montepi;
|
|
*r_scc = scc;
|
|
}
|
|
|
|
} // namespace zeek::detail
|