/*

* 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/matrix.h"

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

R A N K  A L G O R I T H M  R O U T I N E S

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

#define	MATRIX_FORWARD_ELIMINATION	0

#define	MATRIX_BACKWARD_ELIMINATION	1

int

computeRank(int M, int Q, BitSequence **matrix)

{

	int		i, rank, m=MIN(M,Q);

	/* FORWARD APPLICATION OF ELEMENTARY ROW OPERATIONS */ 

	for ( i=0; i<m-1; i++ ) {

		if ( matrix[i][i] == 1 ) 

			perform_elementary_row_operations(MATRIX_FORWARD_ELIMINATION, i, M, Q, matrix);

		else { 	/* matrix[i][i] = 0 */

			if ( find_unit_element_and_swap(MATRIX_FORWARD_ELIMINATION, i, M, Q, matrix) == 1 ) 

				perform_elementary_row_operations(MATRIX_FORWARD_ELIMINATION, i, M, Q, matrix);

		}

	}

	/* BACKWARD APPLICATION OF ELEMENTARY ROW OPERATIONS */ 

	for ( i=m-1; i>0; i-- ) {

		if ( matrix[i][i] == 1 )

			perform_elementary_row_operations(MATRIX_BACKWARD_ELIMINATION, i, M, Q, matrix);

		else { 	/* matrix[i][i] = 0 */

			if ( find_unit_element_and_swap(MATRIX_BACKWARD_ELIMINATION, i, M, Q, matrix) == 1 )

				perform_elementary_row_operations(MATRIX_BACKWARD_ELIMINATION, i, M, Q, matrix);

		}

	} 

	rank = determine_rank(m, M, Q, matrix);

	return rank;

}

void

perform_elementary_row_operations(int flag, int i, int M, int Q, BitSequence **A)

{

	int		j, k;

	if ( flag == MATRIX_FORWARD_ELIMINATION ) {

		for ( j=i+1; j<M;  j++ )

			if ( A[j][i] == 1 ) 

				for ( k=i; k<Q; k++ ) 

					A[j][k] = (BitSequence)((A[j][k] + A[i][k]) % 2);

	}

	else {

		for ( j=i-1; j>=0;  j-- )

			if ( A[j][i] == 1 )

				for ( k=0; k<Q; k++ )

					A[j][k] = (BitSequence)((A[j][k] + A[i][k]) % 2);

	}

}

int

find_unit_element_and_swap(int flag, int i, int M, int Q, BitSequence **A)

{ 

	int		index, row_op=0;

	if ( flag == MATRIX_FORWARD_ELIMINATION ) {

		index = i+1;

		while ( (index < M) && (A[index][i] == 0) ) 

			index++;

			if ( index < M )

				row_op = swap_rows(i, index, Q, A);

	}

	else {

		index = i-1;

		while ( (index >= 0) && (A[index][i] == 0) ) 

			index--;

			if ( index >= 0 )

				row_op = swap_rows(i, index, Q, A);

	}

	return row_op;

}

int

swap_rows(int i, int index, int Q, BitSequence **A)

{

	int			p;

	BitSequence	temp;

	for ( p=0; p<Q; p++ ) {

		temp = A[i][p];

		A[i][p] = A[index][p];

		A[index][p] = temp;

	}

	return 1;

}

int

determine_rank(int m, int M, int Q, BitSequence **A)

{

	int		i, j, rank, allZeroes;

	/* DETERMINE RANK, THAT IS, COUNT THE NUMBER OF NONZERO ROWS */

	rank = m;

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

		allZeroes = 1; 

		for ( j=0; j<Q; j++)  {

			if ( A[i][j] == 1 ) {

				allZeroes = 0;

				break;

			}

		}

		if ( allZeroes == 1 )

			rank--;

	} 

	return rank;

}

BitSequence**

create_matrix(int M, int Q)

{

	int			i;

	BitSequence	**matrix;

	if ( (matrix = (BitSequence **) calloc(M, sizeof(BitSequence *))) == NULL ) {

		printf("ERROR IN FUNCTION create_matrix:  Insufficient memory available.\n");

		return NULL;

	}

	else {

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

			if ( (matrix[i] = (unsigned char*)calloc(Q, sizeof(BitSequence))) == NULL ) {

				printf("ERROR IN FUNCTION create_matrix: Insufficient memory for %dx%d matrix.\n", M, M);

				return NULL;

			}

		}

		return matrix;

	}

}

void

def_matrix(int M, int Q, BitSequence **m,int k)

{

	int		i,j;

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

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

			m[i][j] = epsilon[k*(M*Q)+j+i*M];

}

void

delete_matrix(int M, BitSequence **matrix)

{

	int		i;

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

		free(matrix[i]);

	free(matrix);

}