/*

* Portions Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

* The original NIST Statistical Test Suite code is placed in public domain.

* (http://csrc.nist.gov/groups/ST/toolkit/rng/documentation_software.html) 

* 

* This software was developed at the National Institute of Standards and Technology by 

* employees of the Federal Government in the course of their official duties. Pursuant

* to title 17 Section 105 of the United States Code this software is not subject to 

* copyright protection and is in the public domain. The NIST Statistical Test Suite is

* an experimental system. NIST assumes no responsibility whatsoever for its use by other 

* parties, and makes no guarantees, expressed or implied, about its quality, reliability, 

* or any other characteristic. We would appreciate acknowledgment if the software is used.

*/

#include "openc.h"

#include "../include/externs.h"

#include "../include/cephes.h"

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

                    B L O C K  F R E Q U E N C Y  T E S T

 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

void

BlockFrequency(int M, int n)

{

	int		i, j, N, blockSum;

	double	p_value, sum, pi, v, chi_squared;

	N = n/M; 		/* # OF SUBSTRING BLOCKS      */

	sum = 0.0;

	for ( i=0; i<N; i++ ) {

		blockSum = 0;

		for ( j=0; j<M; j++ )

			blockSum += epsilon[j+i*M];

		pi = (double)blockSum/(double)M;

		v = pi - 0.5;

		sum += v*v;

	}

	chi_squared = 4.0 * M * sum;

	p_value = cephes_igamc(N/2.0, chi_squared/2.0);

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\t\tBLOCK FREQUENCY TEST\n");

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\t---------------------------------------------\n");

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\tCOMPUTATIONAL INFORMATION:\n");

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\t---------------------------------------------\n");

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\t(a) Chi^2           = %f\n", chi_squared);

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\t(b) # of substrings = %d\n", N);

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\t(c) block length    = %d\n", M);

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\t(d) Note: %d bits were discarded.\n", n % M);

	fprintf(stats[TEST_BLOCK_FREQUENCY], "\t\t---------------------------------------------\n");

	fprintf(stats[TEST_BLOCK_FREQUENCY], "%s\t\tp_value = %f\n\n", p_value < ALPHA ? "FAILURE" : "SUCCESS", p_value);

	fprintf(results[TEST_BLOCK_FREQUENCY], "%f\n", p_value);

}