BitsTest.java

/* This file is part of the Joshua Machine Translation System.
 * 
 * Joshua is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1
 * of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */
package joshua.util;

import org.testng.Assert;
import org.testng.annotations.Test;

/**
 * Unit tests for doing bit twiddling.
 *
 * @author Lane Schwartz
 */
public class BitsTest {

	@Test
	public void positiveLowBitsLongEncoding() {
		
		int[] highs = {Integer.MIN_VALUE, -1234567890, -1, 0, 1, 1234567890, Integer.MAX_VALUE};
		
		for (int high : highs) {
			for (int low=0, step=(Integer.MAX_VALUE/754); low>=0 && low<=Integer.MAX_VALUE; low+=step) {
				
				Assert.assertTrue(step > 0);
				Assert.assertTrue(low >= 0);

				long encoded = Bits.encodeAsLong(high, low);

				Assert.assertEquals(Bits.decodeHighBits(encoded), high);
				Assert.assertEquals(Bits.decodeLowBits(encoded), low);
			}
		}
		
	}
	
	@Test
	public void negativeLowBitsLongEncoding() {

		int[] highs = {Integer.MIN_VALUE, -1234567890, -1, 0, 1, 1234567890, Integer.MAX_VALUE};

		for (int high : highs) {
			for (int low=Integer.MIN_VALUE, step=(Integer.MAX_VALUE/754); low<=0 && low>=Integer.MIN_VALUE; low-=step) {

				Assert.assertTrue(step > 0);
				Assert.assertTrue(low <= 0);

				long encoded = Bits.encodeAsLong(high, low);

				Assert.assertEquals(Bits.decodeHighBits(encoded), high);
				Assert.assertEquals(Bits.decodeLowBits(encoded), low);
			}
		}
	}
	
	
	@Test
	public void positiveHighBitsLongEncoding() {
		
		int[] lows = {Integer.MIN_VALUE, -1234567890, -1, 0, 1, 1234567890, Integer.MAX_VALUE};
		
		for (int low : lows) {
			for (int high=0, step=(Integer.MAX_VALUE/754); high>=0 && high<=Integer.MAX_VALUE; high+=step) {
				
				Assert.assertTrue(step > 0);
				Assert.assertTrue(high >= 0);

				long encoded = Bits.encodeAsLong(high, low);

				Assert.assertEquals(Bits.decodeHighBits(encoded), high);
				Assert.assertEquals(Bits.decodeLowBits(encoded), low);
			}
		}
	}
	
	@Test
	public void negativeHighBitsLongEncoding() {

		int[] lows = {Integer.MIN_VALUE, -1234567890, -1, 0, 1, 1234567890, Integer.MAX_VALUE};

		for (int low : lows) {
			for (int high=Integer.MIN_VALUE, step=(Integer.MAX_VALUE/754); high<=0 && high>=Integer.MIN_VALUE; high-=step) {

				Assert.assertTrue(step > 0);
				Assert.assertTrue(high <= 0);

				long encoded = Bits.encodeAsLong(high, low);

				Assert.assertEquals(Bits.decodeHighBits(encoded), high);
				Assert.assertEquals(Bits.decodeLowBits(encoded), low);
			}
		}
	}
	
	
	@Test
	public void positiveLowBitsIntEncoding() {
		
		short[] highs = {Short.MIN_VALUE, -12345, -1, 0, 1, 12345, Short.MAX_VALUE};
		
		for (short high : highs) {
			for (short low=0, step=(Short.MAX_VALUE/75); low>=0 && low<=Short.MAX_VALUE; low+=step) {
				
				Assert.assertTrue(step > 0);
				Assert.assertTrue(low >= 0);

				int encoded = Bits.encodeAsInt(high, low);

				Assert.assertEquals(Bits.decodeHighBits(encoded), high);
				Assert.assertEquals(Bits.decodeLowBits(encoded), low);
			}
		}
		
	}
	
	@Test
	public void negativeLowBitsIntEncoding() {

		short[] highs = {Short.MIN_VALUE, -12345, -1, 0, 1, 12345, Short.MAX_VALUE};

		for (short high : highs) {
			for (short low=0, step=(Short.MAX_VALUE/75); low>=0 && low>=Short.MIN_VALUE; low-=step) {

				Assert.assertTrue(step > 0);
				Assert.assertTrue(low <= 0);

				int encoded = Bits.encodeAsInt(high, low);

				Assert.assertEquals(Bits.decodeHighBits(encoded), high);
				Assert.assertEquals(Bits.decodeLowBits(encoded), low);
			}
		}
	}
	
	
	@Test
	public void positiveHighBitsIntEncoding() {
		
		short[] lows = {Short.MIN_VALUE, -12345, -1, 0, 1, 12345, Short.MAX_VALUE};
		
		for (short low : lows) {
			for (short high=0, step=(Short.MAX_VALUE/75); high>=0 && high<=Short.MAX_VALUE; high+=step) {
				
				Assert.assertTrue(step > 0);
				Assert.assertTrue(high >= 0);

				int encoded = Bits.encodeAsInt(high, low);

				Assert.assertEquals(Bits.decodeHighBits(encoded), high);
				Assert.assertEquals(Bits.decodeLowBits(encoded), low);
			}
		}
	}
	
	@Test
	public void negativeHighBitsIntEncoding() {

		short[] lows = {Short.MIN_VALUE, -12345, -1, 0, 1, 12345, Short.MAX_VALUE};
		
		for (short low : lows) {
			for (short high=0, step=(Short.MAX_VALUE/75); high>=0 && high>=Short.MIN_VALUE; high-=step) {

				Assert.assertTrue(step > 0);
				Assert.assertTrue(high <= 0);

				int encoded = Bits.encodeAsInt(high, low);

				Assert.assertEquals(Bits.decodeHighBits(encoded), high);
				Assert.assertEquals(Bits.decodeLowBits(encoded), low);
			}
		}
	}
}