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#include "tweak.h"
#include <stdio.h>
#include <stdlib.h>
#include "my-string.h"
#include <math.h>
static int bitcount[16];
static int rounds;
static int result;
#define MAX_WORST_ALLOWED 0.1f
/* FSP classic algo */
static unsigned short classic (void)
{
unsigned long k;
k = random();
k = k ^ (k >> 8) ^ (k >> 16) ^ (k << 8);
return k;
}
/* get low bits from random result */
static unsigned short simple (void)
{
return random();
}
/* get high bits from random result - better */
static unsigned short simple2 (void)
{
return (random() >> 15);
}
/* The following algorithm is recommended by Numerical Recipies: */
/* Best, but needs floating point division */
static unsigned short nr(void)
{
unsigned short ulRandom = ((float)(0xffff)*rand()/(RAND_MAX+1.0f));
return(ulRandom);
}
static void run_randomtest( unsigned short (*keygen)(void) )
{
int i,j;
unsigned short rnd;
/* zero bitcount first */
memset(bitcount,0,16*sizeof(int));
for(i=0;i<rounds;i++)
{
rnd=keygen();
for(j=0;j<16;j++)
{
if(rnd & 1)
bitcount[j]++;
rnd=rnd>>1;
}
}
}
static void print_bitcount(void)
{
int i;
float worst;
float ratio;
printf("Set ratio: ");
worst=0;
for(i=0;i<16;i++)
{
ratio=(float)bitcount[i]/rounds;
if(fabs(ratio-0.5f)>worst)
worst=fabs(ratio-0.5f);
printf("%.2f ",ratio);
}
printf(" Worst: %.3f\n",worst);
if(worst>MAX_WORST_ALLOWED) result++;
}
int main(int argc,const char *argv[])
{
rounds=2000;
if(argc>1)
{
rounds=atoi(argv[1]);
}
printf("Running %d rounds.\n\n",rounds);
result=0;
printf("Generator: classic\n");
run_randomtest(classic);
print_bitcount();
printf("Generator: simple\n");
run_randomtest(simple);
print_bitcount();
printf("Generator: simple2\n");
run_randomtest(simple2);
print_bitcount();
result=0;
printf("Generator: Numerical Recipes\n");
run_randomtest(nr);
print_bitcount();
return result;
}
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