/*******************************************************************************
* Copyright (c) 2000, 2012 QNX Software Systems and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* QNX Software Systems - initial API and implementation
* Markus Schorn (Wind River Systems)
*******************************************************************************/
package org.eclipse.cdt.internal.core;
import java.io.IOException;
public class ByteUtils {
/**
* Concatenates two bytes to make a short
*
* @param bytes
* collection of bytes; must provide a minimum of two bytes starting at [offset]
* @param offset
* zero-based index into [bytes], identifying the first input byte
* @param isle
* if true, bytes are concatenated in little-endian order (the first input byte in the
* collection represents the least-significant byte of the resulting short); otherwise
* big-endian
* @return the resulting short
* @throws IOException
* if an insufficient number of bytes are supplied
*/
public static short makeShort(byte[] bytes, int offset, boolean isle) throws IOException {
if (bytes.length < offset + 2)
throw new IOException();
return isle ?
(short) ((bytes[offset + 1] << 8) | (bytes[offset + 0] & 0xff)) :
(short) ((bytes[offset + 0] << 8) | (bytes[offset + 1] & 0xff));
}
/**
* Concatenates four bytes to make an int
*
* @param bytes
* collection of bytes; must provide a minimum of four bytes starting at [offset]
* @param offset
* zero-based index into [bytes], identifying the first input byte
* @param isle
* if true, bytes are concatenated in little-endian order (the first input byte in the
* collection represents the least-significant byte of the resulting short); otherwise
* big-endian
* @return the resulting int
* @throws IOException
* if an insufficient number of bytes are supplied
*/
public static long makeInt(byte[] bytes, int offset, boolean isle) throws IOException {
if (bytes.length < offset + 4)
throw new IOException();
return isle ?
(bytes[offset + 3] << 24) + ((bytes[offset + 2] & 0xff) << 16) + ((bytes[offset + 1] & 0xff) << 8) + (bytes[offset + 0] & 0xff) :
(bytes[offset + 0] << 24) + ((bytes[offset + 1] & 0xff) << 16) + ((bytes[offset + 2] & 0xff) << 8) + (bytes[offset + 3] & 0xff);
}
/**
* Concatenates eight bytes to make a long
*
* @param bytes
* collection of bytes; must provide a minimum of eight bytes starting at [offset]
* @param offset
* zero-based index into [bytes], identifying the first input byte
* @param isle
* if true, bytes are concatenated in little-endian order (the first input byte in the
* collection represents the least-significant byte of the resulting short); otherwise
* big-endian
* @return the resulting int
* @throws IOException
* if an insufficient number of bytes are supplied
*/
public static long makeLong(byte[] bytes, int offset, boolean isle) throws IOException {
long result = 0;
int shift = 0;
if (isle)
for (int i = 7; i >= 0; i--) {
shift = i * 8;
result += ( ((long)bytes[offset + i]) << shift) & (0xffL << shift);
}
else
for (int i = 0; i <= 7; i++) {
shift = (7 - i) * 8;
result += ( ((long)bytes[offset + i]) << shift) & (0xffL << shift);
}
return result;
}
}