/*
* Copyright (C) 2014 Dr. John Lindsay <jlindsay@uoguelph.ca>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package whitebox.structures;
/**
* This class is used to create a 2-D array of 4-bit integers, known as nibbles. Nibbles
* can hold the numbers 0-15 and are relatively compact.
* @author johnlindsay
*/
public class NibbleArray2D {
private int rows = 0;
private int columns = 0;
private int columnsInBytes = 0;
private byte[][] data;
public NibbleArray2D(int rows, int columns) {
this.rows = rows;
this.columns = columns;
columnsInBytes = (int)(Math.ceil(columns / 2.0));
data = new byte[rows][columnsInBytes];
}
public void setValue(int row, int column, int value) {
if (row < 0 || row >= rows || column < 0 || column >= columns) {
return;
}
if (value > 15 || value < 0) {
return;
}
// which byte-row and byte-col will it be in?
int colB = column / 2;
int colOffset = (column % 2);
byte existingval = data[row][colB];
byte newVal;
if (colOffset == 0) {
newVal = (byte)((existingval & 240) | value);
} else {
newVal = (byte)((existingval & 15) | (value << 4));
}
data[row][colB] = newVal;
}
public int getValue(int row, int column) {
if (row < 0 || row >= rows || column < 0 || column >= columns) {
return -1;
}
// which byte-row and byte-col will it be in?
int colB = column / 2;
int colOffset = column % 2;
byte val = data[row][colB];
if (colOffset == 0) {
return val & 15;
} else {
return (val & 240) >> 4;
}
}
public static void main(String[] arg) {
NibbleArray2D nibble = new NibbleArray2D(100, 100);
nibble.setValue(5, 4, 4);
nibble.setValue(5, 4, 8);
nibble.setValue(5, 5, 12);
nibble.setValue(6, 76, 9);
System.out.println(nibble.getValue(5, 4));
System.out.println(nibble.getValue(5, 5));
System.out.println(nibble.getValue(6, 76));
nibble.setValue(6, 76, 87);
System.out.println(nibble.getValue(6, 76));
}
}