Class Calculator

java.lang.Object
  java.awt.Component
      java.awt.Container
          java.awt.Panel
              java.applet.Applet
                  Calculator

All Implemented Interfaces:

ImageObserver, MenuContainer, Serializable, Accessible

public class Calculator
extends Applet

A tiny whole-number calculator — stack architecture.

An object of this class is an Applet, featuring the logic (state machine) and the display of an integer stack calculator. It has four stack registers (x, y, z and t just like the famous HP pocket calculators).

Decimal and hexadecimal display and entry are supported.
The number range is (Java) long (64 bit, 2s complement).

This Applet can be used to demonstrate (Java) integer arithmetic as well as the stack computer architecture.

The keyboard for digits, "Enter" (the stack push) and the operations is not part of the Applet. (In that sense the Applet is a pure demo of MatrixDisplay, MatrixTextDisplay and DisplayPattern.) The (key) entries are supplied by public methods. The keypad may thus be implemented by buttons in the "forms" of an embedding HTML page.

See the minimal demo page calculator.html and the source.

Copyright 2001, 2003, 2004, 2009 Albrecht Weinert

Version:

46 (28.04.2010)

Author:

Albrecht Weinert

See Also:

MatrixDisplay, DisplayPattern, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.applet.Applet

Applet.AccessibleApplet

Nested classes/interfaces inherited from class java.awt.Panel

Panel.AccessibleAWTPanel

Nested classes/interfaces inherited from class java.awt.Container

Container.AccessibleAWTContainer

Nested classes/interfaces inherited from class java.awt.Component

Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy

Field Summary

static int	ANZ_EL Number of 5*8 elements in display.
protected boolean	autoEnter State: next digit entry will do an Enter (push stack) before.
protected boolean	enterTo0 State: next digit entry will clear X before.
protected boolean	hex State: Hex calculator.
protected MatrixTextDisplay	md The display.
protected static byte[][]	MINI_E Display pattern for minified (5*3) E.
protected static byte[][]	MINI_H Display pattern for minified (5*3) H.
static String	NVC Name, version, copyright.
protected long	t Stack register T (Stack is x, y, z, t).
protected boolean	thrOn Do the marquee (running) version display.
protected long	x Main register X (=display register).
protected long	y Stack register Y (Stack is x, y, z, t).
protected long	z Stack register Z (Stack is x, y, z, t).

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

Calculator()

Method Summary

void	chgSign() Change the sign of x: x = -x.
void	chgXY() Exchange x and y.
void	clrXclrAll() Clear X or all registers.
void	digIn(int digit) Entry of a digit (0..9; ..15).
void	divide() Division (integer) x = y / x.
void	divide2() Division and remainder (integer) x,y = (y / x), (x mod y).
void	enter() Push operation respectively Enter.
void	init() Initialising.
void	invHex() Hex-Decimal toggle.
void	minus() Subtraction x = y - x.
void	mod() Modulo (integer remainder) x = y % x.
void	multiply() Multiplication x = x * y.
void	paint(Graphics g) Paint the display.
void	plus() Addition x = y + x.
void	reset() Reset to "power on" state.
void	rollDown() Roll down the stack (t becomes the previous x).
void	showX() Renew the X display.
void	update(Graphics g) Update the display.
void	yHx() Exponent (y power x) x = y ** x.

Methods inherited from class java.applet.Applet

destroy, getAccessibleContext, getAppletContext, getAppletInfo, getAudioClip, getAudioClip, getCodeBase, getDocumentBase, getImage, getImage, getLocale, getParameter, getParameterInfo, isActive, newAudioClip, play, play, resize, resize, setStub, showStatus, start, stop

Methods inherited from class java.awt.Panel

addNotify

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getAlignmentX, getAlignmentY, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getComponentZOrder, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getInsets, getLayout, getListeners, getMaximumSize, getMinimumSize, getMousePosition, getPreferredSize, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicyProvider, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, paramString, preferredSize, print, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, removeNotify, setComponentZOrder, setFocusCycleRoot, setFocusTraversalKeys, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setFont, setLayout, transferFocusBackward, transferFocusDownCycle, validate, validateTree

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, disable, disableEvents, dispatchEvent, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusUpCycle

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

NVC

public static final String NVC

Name, version, copyright.

See Also:

Constant Field Values

x

protected long x

Main register X (=display register).

y

protected long y

Stack register Y (Stack is x, y, z, t).

z

protected long z

Stack register Z (Stack is x, y, z, t).

t

protected long t

Stack register T (Stack is x, y, z, t).

MINI_H

protected static final byte[][] MINI_H

Display pattern for minified (5*3) H.

Used as "Hex" marker.

MINI_E

protected static final byte[][] MINI_E

Display pattern for minified (5*3) E.

Used as "Error" marker.

ANZ_EL

public static final int ANZ_EL

Number of 5*8 elements in display.

Value: 20

See Also:

Constant Field Values

md

protected MatrixTextDisplay md

The display.

Die display itself will be implemented as a MatrixTextDisplay object.

It will be made for one line of 20 (ANZ_EL) 5 * 8 elements with 2 dots horizontal spacing. The matrix dots itself are sized 4 * 4 pixels and are densely packed.

Thus the applet's minimal size is about 596 * 60 (width * height).

hex

protected boolean hex

State: Hex calculator.

enterTo0

protected boolean enterTo0

State: next digit entry will clear X before.

autoEnter

protected boolean autoEnter

State: next digit entry will do an Enter (push stack) before.

thrOn

protected boolean thrOn

Do the marquee (running) version display.

Constructor Detail

Calculator

public Calculator()

Method Detail

init

public void init()

Initialising.

Overrides:

init in class Applet

update

public void update(Graphics g)

Update the display.

This method does not clear the background (to background colour) as paint() will update all matrix dots without flickering.

Overrides:

update in class Container

paint

public void paint(Graphics g)

Paint the display.

This method is equivalent to update().

Overrides:

paint in class Container

showX

public void showX()

Renew the X display.

digIn

public void digIn(int digit)

Entry of a digit (0..9; ..15).

This method has to be called with a parameter of 0..9..15, according to the digit key 0..9, A..F pressed.

The display will be updated accordingly. After a previous calculation / operation enter() will be processed before.

Implementation hint: As this method implements the numeric key pad of a pocket calculator it assumes that the number being entered / constructed in stack register x is not negative. (Changing sign would be an operation that ends the number entry.)

Parameters:

digit - The digit key entry: 0..9 decimal respectively 0..15 if hexadecimal. Values out of range will be ignored.

multiply

public void multiply()

Multiplication x = x * y.

This method uses the two lower stack registers as operands popping them and pushing the result. (t is copied to z as side effect).

divide

public void divide()

Division (integer) x = y / x.

This method uses the two lower stack registers as operands popping them and pushing the result. (t is copied to z as side effect).

divide2

public void divide2()

Division and remainder (integer) x,y = (y / x), (x mod y).

This method calculates the integer quotient y / x and the integer remainder y mod x (y % x in Java). The new content of x is the quotient and y will be the remainder. By exchanging chgXY() they can be viewed alternately.
Registers z and t remain unchanged.

mod

public void mod()

Modulo (integer remainder) x = y % x.

This method uses the two lower stack registers as operands popping them and pushing the result. (t is copied to z as side effect).
The remainder calculation uses Java y % x (sign) rules as they (surprisingly to many) are.

yHx

public void yHx()

Exponent (y power x) x = y ** x.

This method uses the two lower stack registers as operands popping them and pushing the result. (t is copied to z as side effect).

plus

public void plus()

Addition x = y + x.

minus

public void minus()

Subtraction x = y - x.

chgSign

public void chgSign()

Change the sign of x: x = -x.

The other stack registers remain unchanged.

invHex

public void invHex()

Hex-Decimal toggle.

This method changes the display and entering mode from decimal to hexadecimal and vice versa.

chgXY

public void chgXY()

Exchange x and y.

This method interchanges the content of x and y, leaving z and t unchanged.

rollDown

public void rollDown()

Roll down the stack (t becomes the previous x).

This method rolls the stack down or, to say it unambiguously, toward x. The former x content is put to t.

Calling this four times restores the original condition.

enter

public void enter()

Push operation respectively Enter.

This method pushes the stack one up (towards t). The former t content is lost and x and y have now the same content.
But x will be auto-cleared before the next digit entry.

reset

public void reset()

Reset to "power on" state.

This method clears all stack registers to 0, clear the error flag and sets the decimal mode.

Additionally marquee (running) display of the version info is started.
Enter (enter()) starts the normal operation.

clrXclrAll

public void clrXclrAll()

Clear X or all registers.

This method just sets x to 0 if not yet so. Otherwise all registers are set to 0.