immediatebyteinstruction.java

Java Bytecode Editor 是一个 JAVA 的字节码反汇编和修改器。它可以很方便的修改已经编译成 Class 文件的 JAVA 文件。

/*
    This library 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 2 of the license, or (at your option) any later version.
*/

package org.gjt.jclasslib.bytecode;

import org.gjt.jclasslib.io.ByteCodeInput;
import org.gjt.jclasslib.io.ByteCodeOutput;

import java.io.IOException;

/**
    Describes an instruction that is followed by an immediate unsigned byte.
 
    @author <a href="mailto:[e-mail]">Ingo Kegel</a>
    @version $Revision: 1.1 $ $Date: 2005/11/01 13:18:23 $
*/
public class ImmediateByteInstruction extends AbstractInstruction {

    /** Indicates whether the instuction is subject to a wide instruction or not. */
    protected boolean wide;
    
    private int immediateByte;

    /**
        Constructor.
        @param opcode the opcode
        @param wide whether the instruction is a wide instruction.
     */
    public ImmediateByteInstruction(int opcode, boolean wide) {
        super(opcode); 
        this.wide = wide;
    }

    /**
        Constructor.
        @param opcode the opcode
        @param wide whether the instruction is a wide instruction.
        @param immediateByte the immediate byte value.
     */
    public ImmediateByteInstruction(int opcode, boolean wide, int immediateByte) {
        this(opcode, wide); 
        this.immediateByte = immediateByte;
    }
    
    public int getSize() {
        return super.getSize() + (wide ? 2 : 1);
    }

    /**
        Get the immediate unsigned byte of this instruction.
        @return the byte
     */
    public int getImmediateByte() {
        return immediateByte;
    }

    /**
        Set the immediate unsigned byte of this instruction.
        @param immediateByte the byte
     */
     public void setImmediateByte(int immediateByte) {
        this.immediateByte = immediateByte;
    }
    
    /**
        Check whether the instuction is subject to a wide instruction or not.
        @return wide or not
     */
    public boolean isWide() {
        return wide;
    }
    
    /**
        Set whether the instuction is subject to a wide instruction or not.
        @param wide wide or not
     */
    public void setWide(boolean wide) {
        this.wide = wide;
    }
    
    public void read(ByteCodeInput in) throws IOException {
        super.read(in);

        if (wide) {
            immediateByte = in.readUnsignedShort();
        } else {
            immediateByte = in.readUnsignedByte();
        }
    }

    public void write(ByteCodeOutput out) throws IOException {
        super.write(out);

        if (wide) {
            out.writeShort(immediateByte);
        } else {
            out.writeByte(immediateByte);
        }
    }
    
}