operandstackpanel.java

这是有关Java虚拟机的实现代码,是学习和使用Java虚拟机的朋友们不可或缺的代码

/*
* Copyright (c) 1996-1999 Bill Venners. All Rights Reserved.
*
* This Java source file is part of the Interactive Illustrations Web
* Site, which is delivered in the applets directory of the CD-ROM
* that accompanies the book "Inside the Java 2 Virtual Machine" by Bill
* Venners, published by McGraw-Hill, 1999, ISBN: 0-07-135093-4. This
* source file is provided for evaluation purposes only, but you can
* redistribute it under certain conditions, described in the full
* copyright notice below.
*
* Full Copyright Notice:
*
* All the web pages and Java applets delivered in the applets
* directory of the CD-ROM, consisting of ".html," ".gif," ".class,"
* and ".java" files, are copyrighted (c) 1996-1999 by Bill
* Venners, and all rights are reserved.  This material may be copied
* and placed on any commercial or non-commercial web server on any
* network (including the internet) provided that the following
* guidelines are followed:
*
* a. All the web pages and Java Applets (".html," ".gif," ".class,"
* and ".java" files), including the source code, that are delivered
* in the applets directory of the CD-ROM that
* accompanies the book must be published together on the same web
* site.
*
* b. All the web pages and Java Applets (".html," ".gif," ".class,"
* and ".java" files) must be published "as is" and may not be altered
* in any way.
*
* c. All use and access to this web site must be free, and no fees
* can be charged to view these materials, unless express written
* permission is obtained from Bill Venners.
*
* d. The web pages and Java Applets may not be distributed on any
* media, other than a web server on a network, and may not accompany
* any book or publication.
*
* BILL VENNERS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE
* SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR PARTICULAR PURPOSE, OR NON-INFRINGEMENT.  BILL VENNERS
* SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY A LICENSEE AS A
* RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES.
*/
package COM.artima.jvmsim;
import java.awt.*;

/**
* This class represents that portion of the user interface
* that displays the words on the operand stack.
*
* @author  Bill Venners
*/
class OperandStackPanel extends Panel {

    private int memoryLocationsVisibleCount;

    private Label[] pointer;
    private Label[] address;
    private Label[] wordValue;
    private Label[] logicalValue;

    private int currentOptopRow;

    private ColoredLabel optopRegister;

    OperandStackPanel(int maxStack) {

        // Add one to maxStack so that "optop>" has somewhere to go
        // when the stack is full.
        memoryLocationsVisibleCount = maxStack + 1;
        pointer = new Label[memoryLocationsVisibleCount];
        address = new Label[memoryLocationsVisibleCount];
        wordValue = new Label[memoryLocationsVisibleCount];
        logicalValue = new Label[memoryLocationsVisibleCount];

        // Initialize the title
        Label title = new Label(StringTable.operandStack, Label.CENTER);
        title.setFont(new Font("Helvetica", Font.BOLD, 11));

        // Initialize the labelled pc register panel
        Panel registerPanel = new Panel();
        registerPanel.setLayout(new BorderLayout(5,5));
        optopRegister = new ColoredLabel("0000", Label.CENTER, Color.lightGray);
        optopRegister.setFont(new Font("TimesRoman", Font.PLAIN, 11));
        Label pcRegTitle = new Label(StringTable.optop, Label.RIGHT);
        pcRegTitle.setFont(new Font("Helvetica", Font.ITALIC, 11));
        registerPanel.add("East", optopRegister);
        registerPanel.add("Center", pcRegTitle);

        // Put the title and the pc register panel on the same panel
        Panel titleRegisterPanel = new Panel();
        titleRegisterPanel.setLayout(new BorderLayout());
        titleRegisterPanel.add("West", registerPanel);
        titleRegisterPanel.add("Center", title);

        // Initialize column titles
        Panel columnTitles = new Panel();
        int[] hComponentCellWidths = { 2, 2, 2, 3 };
        columnTitles.setLayout(new GridSnapLayout(1, 9, hComponentCellWidths));
        columnTitles.setFont(new Font("Helvetica", Font.ITALIC, 11));
        columnTitles.add(new Label("", Label.CENTER));
        columnTitles.add(new Label(StringTable.offset, Label.CENTER));
        columnTitles.add(new Label(StringTable.hexValue, Label.CENTER));
        columnTitles.add(new Label(StringTable.value, Label.LEFT));

        // Initialize the 4 column view of the method
        Panel methodView = new Panel();
        methodView.setLayout(new GridSnapLayout(memoryLocationsVisibleCount, 9, hComponentCellWidths));
        methodView.setBackground(Color.lightGray);
        Font plainFont = new Font("TimesRoman", Font.PLAIN, 11);
        methodView.setFont(plainFont);
        Font italicFont = new Font("TimesRoman", Font.ITALIC, 11);

        for (int i = 0; i < memoryLocationsVisibleCount; ++i) {

            pointer[i] = new Label("", Label.RIGHT);
            pointer[i].setFont(italicFont);
            methodView.add(pointer[i]);

            address[i] = new Label("", Label.CENTER);
            methodView.add(address[i]);

            wordValue[i] = new Label("", Label.CENTER);
            methodView.add(wordValue[i]);

            logicalValue[i] = new Label("", Label.LEFT);
            methodView.add(logicalValue[i]);
        }

        Panel methodViewWithTitles = new Panel();
        methodViewWithTitles.setLayout(new BorderLayout());
        methodViewWithTitles.add("North", columnTitles);
        methodViewWithTitles.add("Center", methodView);

        setLayout(new BorderLayout());
        add("North", titleRegisterPanel);
        add("Center", methodViewWithTitles);
    }

    public void updateView(int optop, Object[] operandStack) {
        // Assume length of array is one less that memoryLocationsVisibleCount,
        // which should equal maxStack + 1.
        int len = operandStack.length;
        for (int i = 0; i < len; ++i) {

            address[i].setText(Integer.toString(i));

            Object locVar = operandStack[i];
            if (locVar == null) {
                wordValue[i].setText("");
                logicalValue[i].setText("");
            }
            else if (locVar instanceof Integer) {

                Integer value = (Integer) locVar;
                HexString wordValueHexString = new HexString(value.intValue(), 8);
                wordValue[i].setText(wordValueHexString.getString());
                logicalValue[i].setText(value.toString());
            }
            else if (locVar instanceof Float) {

                Float wrapperVal = (Float) locVar;
                float fVal = wrapperVal.floatValue();
                int floatBits = Float.floatToIntBits(fVal);
                HexString wordValueHexString = new HexString(floatBits, 8);
                wordValue[i].setText(wordValueHexString.getString());
                logicalValue[i].setText(wrapperVal.toString());
            }
            else if (locVar instanceof Long) {
                Long value = (Long) locVar;
				long longValue = value.longValue();
				int lowerWord = (int) longValue;
				int upperWord = (int) (longValue >>> 32);
                HexString lowerWordHexString = new HexString(lowerWord, 8);
                HexString upperWordHexString = new HexString(upperWord, 8);
                wordValue[i].setText(lowerWordHexString.getString());
                wordValue[i + 1].setText(upperWordHexString.getString());
                logicalValue[i].setText(value.toString() + "L");
				++i; // must increment i twice in long case
            }
            else if (locVar instanceof Double) {
                Double value = (Double) locVar;
				double doubleValue = value.doubleValue();
				long longBits = Double.doubleToLongBits(doubleValue);
				int lowerWord = (int) longBits;
				int upperWord = (int) (longBits >>> 32);
                HexString lowerWordHexString = new HexString(lowerWord, 8);
                HexString upperWordHexString = new HexString(upperWord, 8);
                wordValue[i].setText(lowerWordHexString.getString());
                wordValue[i + 1].setText(upperWordHexString.getString());
                logicalValue[i].setText(value.toString());
				++i; // must increment i twice in double case
            }
            else if (locVar instanceof ReturnAddress) {

                ReturnAddress wrapper = (ReturnAddress) locVar;
                HexString wordValueHexString = new HexString(wrapper.getReturnAddress(), 8);
                wordValue[i].setText(wordValueHexString.getString());
                logicalValue[i].setText("RET ADDR");
            }
            else {
                // Its an object
                wordValue[i].setText(" OBJREF ");
                logicalValue[i].setText((locVar.getClass()).getName());
            }
        }

        optopRegister.setLabelText("    " + Integer.toString(optop));

        // Erase the old "optop>" pointer
        pointer[currentOptopRow].setText("");

        // Place the "optop>" pointer
        pointer[optop].setText(StringTable.optopPointer);
        currentOptopRow = optop;
    }

    public Insets insets() {
        return new Insets(5, 5, 5, 5);
    }
}