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	/*
	* Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
	*/
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	package com.sun.org.apache.bcel.internal.generic;

	import java.io.DataOutputStream;
	import java.io.IOException;

	import com.sun.org.apache.bcel.internal.Const;
	import com.sun.org.apache.bcel.internal.util.ByteSequence;

	/**
	* Abstract super class for instructions dealing with local variables.
	*
	* @version $Id: LocalVariableInstruction.java 1747278 2016-06-07 17:28:43Z
	* britter $
	*/
	public abstract class LocalVariableInstruction extends Instruction implements TypedInstruction,
	IndexedInstruction {

	private int n = -1; // index of referenced variable
	private short c_tag = -1; // compact version, such as ILOAD_0
	private short canon_tag = -1; // canonical tag such as ILOAD

	private boolean wide() {
	return n > Const.MAX_BYTE;
	}

	/**
	* Empty constructor needed for the Class.newInstance() statement in
	* Instruction.readInstruction(). Not to be used otherwise. tag and length
	* are defined in readInstruction and initFromFile, respectively.
	*/
	LocalVariableInstruction(final short canon_tag, final short c_tag) {
	super();
	this.canon_tag = canon_tag;
	this.c_tag = c_tag;
	}

	/**
	* Empty constructor needed for the Class.newInstance() statement in
	* Instruction.readInstruction(). Also used by IINC()!
	*/
	LocalVariableInstruction() {
	}

	/**
	* @param opcode Instruction opcode
	* @param c_tag Instruction number for compact version, ALOAD_0, e.g.
	* @param n local variable index (unsigned short)
	*/
	protected LocalVariableInstruction(final short opcode, final short c_tag, final int n) {
	super(opcode, (short) 2);
	this.c_tag = c_tag;
	canon_tag = opcode;
	setIndex(n);
	}

	/**
	* Dump instruction as byte code to stream out.
	*
	* @param out Output stream
	*/
	@Override
	public void dump(final DataOutputStream out) throws IOException {
	if (wide()) {
	out.writeByte(Const.WIDE);
	}
	out.writeByte(super.getOpcode());
	if (super.getLength() > 1) { // Otherwise ILOAD_n, instruction, e.g.
	if (wide()) {
	out.writeShort(n);
	} else {
	out.writeByte(n);
	}
	}
	}

	/**
	* Long output format:
	*
	* <name of opcode> "["<opcode number>"]" "("<length of
	* instruction>")" "<"< local variable index>">"
	*
	* @param verbose long/short format switch
	* @return mnemonic for instruction
	*/
	@Override
	public String toString(final boolean verbose) {
	final short _opcode = super.getOpcode();
	if (((_opcode >= Const.ILOAD_0) && (_opcode <= Const.ALOAD_3))
	\|\| ((_opcode >= Const.ISTORE_0) && (_opcode <= Const.ASTORE_3))) {
	return super.toString(verbose);
	}
	return super.toString(verbose) + " " + n;
	}

	/**
	* Read needed data (e.g. index) from file.
	* <pre>
	* (ILOAD <= tag <= ALOAD_3) \|\| (ISTORE <= tag <= ASTORE_3)
	* </pre>
	*/
	@Override
	protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
	if (wide) {
	n = bytes.readUnsignedShort();
	super.setLength(4);
	} else {
	final short _opcode = super.getOpcode();
	if (((_opcode >= Const.ILOAD) && (_opcode <= Const.ALOAD))
	\|\| ((_opcode >= Const.ISTORE) && (_opcode <= Const.ASTORE))) {
	n = bytes.readUnsignedByte();
	super.setLength(2);
	} else if (_opcode <= Const.ALOAD_3) { // compact load instruction such as ILOAD_2
	n = (_opcode - Const.ILOAD_0) % 4;
	super.setLength(1);
	} else { // Assert ISTORE_0 <= tag <= ASTORE_3
	n = (_opcode - Const.ISTORE_0) % 4;
	super.setLength(1);
	}
	}
	}

	/**
	* @return local variable index (n) referred by this instruction.
	*/
	@Override
	public final int getIndex() {
	return n;
	}

	/**
	* Set the local variable index. also updates opcode and length TODO Why?
	*
	* @see #setIndexOnly(int)
	*/
	@Override
	public void setIndex(final int n) { // TODO could be package-protected?
	if ((n < 0) \|\| (n > Const.MAX_SHORT)) {
	throw new ClassGenException("Illegal value: " + n);
	}
	this.n = n;
	// Cannot be < 0 as this is checked above
	if (n <= 3) { // Use more compact instruction xLOAD_n
	super.setOpcode((short) (c_tag + n));
	super.setLength(1);
	} else {
	super.setOpcode(canon_tag);
	if (wide()) {
	super.setLength(4);
	} else {
	super.setLength(2);
	}
	}
	}

	/**
	* @return canonical tag for instruction, e.g., ALOAD for ALOAD_0
	*/
	public short getCanonicalTag() {
	return canon_tag;
	}

	/**
	* Returns the type associated with the instruction - in case of ALOAD or
	* ASTORE Type.OBJECT is returned. This is just a bit incorrect, because
	* ALOAD and ASTORE may work on every ReferenceType (including Type.NULL)
	* and ASTORE may even work on a ReturnaddressType .
	*
	* @return type associated with the instruction
	*/
	@Override
	public Type getType(final ConstantPoolGen cp) {
	switch (canon_tag) {
	case Const.ILOAD:
	case Const.ISTORE:
	return Type.INT;
	case Const.LLOAD:
	case Const.LSTORE:
	return Type.LONG;
	case Const.DLOAD:
	case Const.DSTORE:
	return Type.DOUBLE;
	case Const.FLOAD:
	case Const.FSTORE:
	return Type.FLOAT;
	case Const.ALOAD:
	case Const.ASTORE:
	return Type.OBJECT;
	default:
	throw new ClassGenException("Oops: unknown case in switch" + canon_tag);
	}
	}

	/**
	* Sets the index of the referenced variable (n) only
	*
	* @since 6.0
	* @see #setIndex(int)
	*/
	final void setIndexOnly(final int n) {
	this.n = n;
	}
	}

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