/*
   ULISCAN.c   ---blocksize of 8

1 Oct 98
1 Dec 98
21 Dec 98 	uliscan.c derived from ueli8.c
2 May 99   handles stdin

This version has // comments removed for Sun cc


This implements Ueli M Maurer's
"Universal Statistical Test for Random Bit Generators"
using L=8

Accepts a filename on the command line;
writes its results, with other info, to stdout.

Handles input file exhaustion gracefully.

Ref: J. Cryptology v 5 no 2, 1992 pp 89-105
also on the web somewhere, which is where I found it.

-David Honig
honig@sprynet.com


Built with Wedit 2.3, lcc-win32
http://www.cs.virginia.edu/~lcc-win32




Usage:
	ULISCAN filename
	outputs to stdout

*/




#define L 8
#define V (1<<L)
#define Q (10*V)
#define K (100   *Q)
#define MAXSAMP (Q + K)

#include <stdio.h>
#include <math.h>




int main(  argc, argv )
int argc;
char **argv;
{
FILE *fptr;
int i,j;
int b, c;
int table[V];
double sum=0.0;
int iproduct=1;
int run;

extern double	log(/* double x */);

printf("Uliscan 2 May 98 \nL=%d %d %d \n", L, V, MAXSAMP);
if (argc <2)
	{fptr=stdin;
	} 
else
	{printf("Measuring file %s\n", argv[1]);
	fptr=fopen(argv[1],"rb");
	if (fptr == NULL) {printf("Can't find %s\n", argv[1]); exit(-1); }
	}

for (i=0; i<V; i++) table[i]=0;
for (i=0; i<Q; i++)	{
	b=  fgetc(fptr);
	table[ b ]=i;
}

printf("Init done\n");

printf("Expected value for blocksize=8 is  7.1836656\n");

run=1;
 while (run)
 {	sum=0.0;
    iproduct=1;

	if (run)
	  for (i=Q;  run && i<Q+K; i++)
		{j=i;
		b=fgetc(fptr); if (b<0) run=0;
		if (run) {
			if (table[b] > j) j += K;
			sum += log( (double) ( j-table[b] ) ) ;

			table[ b ]=i;
		}
	}

	if (!run) 	printf("Premature end of file; read %d blocks.\n", i-Q);

	sum = (sum/( (double) (i-Q) ) ) /  log(2.0);
	printf("%4.4f ", sum);
	for (i=0; i< (int) (sum*8.0 + 0.50 ) ; i++)
		printf("-");
	printf("\n");



	/* refill initial table */
	if (0) for (i=0; i<Q; i++)	{
		b=  fgetc(fptr);
		if (b<0) run=0;
		else table[ b ]=i;
		}

   }
}