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feilong is a suite of core and expanded libraries that include utility classes, http, excel,cvs, io classes, and much much more.

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/*
 * Javassist, a Java-bytecode translator toolkit.
 * Copyright (C) 1999- Shigeru Chiba. All Rights Reserved.
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License.  Alternatively, the contents of this file may be used under
 * the terms of the GNU Lesser General Public License Version 2.1 or later,
 * or the Apache License Version 2.0.
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 */

package com.feilong.lib.javassist.bytecode;

/**
 * A collection of static methods for reading and writing a byte array.
 */
public class ByteArray{

    /**
     * Reads an unsigned 16bit integer at the index.
     */
    public static int readU16bit(byte[] code,int index){
        return ((code[index] & 0xff) << 8) | (code[index + 1] & 0xff);
    }

    /**
     * Reads a signed 16bit integer at the index.
     */
    public static int readS16bit(byte[] code,int index){
        return (code[index] << 8) | (code[index + 1] & 0xff);
    }

    /**
     * Writes a 16bit integer at the index.
     */
    public static void write16bit(int value,byte[] code,int index){
        code[index] = (byte) (value >>> 8);
        code[index + 1] = (byte) value;
    }

    /**
     * Reads a 32bit integer at the index.
     */
    public static int read32bit(byte[] code,int index){
        return (code[index] << 24) | ((code[index + 1] & 0xff) << 16) | ((code[index + 2] & 0xff) << 8) | (code[index + 3] & 0xff);
    }

    /**
     * Writes a 32bit integer at the index.
     */
    public static void write32bit(int value,byte[] code,int index){
        code[index] = (byte) (value >>> 24);
        code[index + 1] = (byte) (value >>> 16);
        code[index + 2] = (byte) (value >>> 8);
        code[index + 3] = (byte) value;
    }

    /**
     * Copies a 32bit integer.
     *
     * @param src
     *            the source byte array.
     * @param isrc
     *            the index into the source byte array.
     * @param dest
     *            the destination byte array.
     * @param idest
     *            the index into the destination byte array.
     */
    static void copy32bit(byte[] src,int isrc,byte[] dest,int idest){
        dest[idest] = src[isrc];
        dest[idest + 1] = src[isrc + 1];
        dest[idest + 2] = src[isrc + 2];
        dest[idest + 3] = src[isrc + 3];
    }
}