Utility.java

/*
 * This file is part of JSTUN. 
 * 
 * Copyright (c) 2005 Thomas King <king@t-king.de> - All rights
 * reserved.
 * 
 * This software is licensed under either the GNU Public License (GPL),
 * or the Apache 2.0 license. Copies of both license agreements are
 * included in this distribution.
 */

package de.javawi.jstun.util;

public class Utility {

	public static final long fourBytesToLong(byte[] value)
			throws UtilityException {
		if (value.length < 4) {
			throw new UtilityException("Byte array too short!");
		}
		final int temp0 = value[0] & 0xFF;
		final int temp1 = value[1] & 0xFF;
		final int temp2 = value[2] & 0xFF;
		final int temp3 = value[3] & 0xFF;
		return (((long) temp0 << 24) + (temp1 << 16) + (temp2 << 8) + temp3);
	}

	public static final byte[] integerToFourBytes(int value)
			throws UtilityException {
		final byte[] result = new byte[4];
		if ((value > Math.pow(2, 63)) || (value < 0)) {
			throw new UtilityException("Integer value " + value
					+ " is larger than 2^63");
		}
		result[0] = (byte) ((value >>> 24) & 0xFF);
		result[1] = (byte) ((value >>> 16) & 0xFF);
		result[2] = (byte) ((value >>> 8) & 0xFF);
		result[3] = (byte) (value & 0xFF);
		return result;
	}

	public static final byte integerToOneByte(int value)
			throws UtilityException {
		if ((value > Math.pow(2, 15)) || (value < 0)) {
			throw new UtilityException("Integer value " + value
					+ " is larger than 2^15");
		}
		return (byte) (value & 0xFF);
	}

	public static final byte[] integerToTwoBytes(int value)
			throws UtilityException {
		final byte[] result = new byte[2];
		if ((value > Math.pow(2, 31)) || (value < 0)) {
			throw new UtilityException("Integer value " + value
					+ " is larger than 2^31");
		}
		result[0] = (byte) ((value >>> 8) & 0xFF);
		result[1] = (byte) (value & 0xFF);
		return result;
	}

	public static final int oneByteToInteger(byte value)
			throws UtilityException {
		return value & 0xFF;
	}

	public static final int twoBytesToInteger(byte[] value)
			throws UtilityException {
		if (value.length < 2) {
			throw new UtilityException("Byte array too short!");
		}
		final int temp0 = value[0] & 0xFF;
		final int temp1 = value[1] & 0xFF;
		return ((temp0 << 8) + temp1);
	}
}