import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.border.Border; /* * A simple GUI simulator for the machine * in Appendix C of Computer Science: An Overview. * * Written by Mike Slattery - Nov. 2001 * Modified by Glenn Brookshear - Mar. 2002 */ public class Simulator { public static void main (String[] args) { MachDisplay md = new MachDisplay(); md.addWindowListener(new DisplayWindowListener()); md.show(); } } class DisplayWindowListener extends WindowAdapter { public void windowClosing(WindowEvent e) {System.exit(0); } } class MachDisplay extends JFrame { JTextArea inArea; // extend edge of grid to make checking neighbors easier JLabel[][] mem = new JLabel[17][17]; JLabel[][] regs = new JLabel[16][2]; JLabel[][] spRegs = new JLabel[2][2]; JButton clearb, loadb, runb, stepb, haltb, helpb; boolean running; static String toHex(int val, int width) { //Return a string of at least width chars holding //the hex representation of the non-negative val. String s = Integer.toHexString(val).toUpperCase(); while (s.length() < width) s = "0"+s; return s; } static int toInt(String hex) { int r = 0; //Return the value represented by the string hex try { r = Integer.parseInt(hex, 16); } catch (Exception e) { //System.out.println("Trouble with :"+hex+":"); }; return r; } // First design the visual layout. MachDisplay() { super("Simple Computer"); setSize(850,700); JPanel contPanel = new JPanel(new BorderLayout()); JPanel memPanel = new JPanel(new BorderLayout()); memPanel.add(new JLabel("Main Memory", SwingConstants.CENTER), BorderLayout.NORTH); JPanel memContPanel = new JPanel(new GridLayout(17,17,5,5)); Border b = BorderFactory.createCompoundBorder( BorderFactory.createEmptyBorder(5,5,5,5), BorderFactory.createLineBorder(Color.black,2)); memContPanel.setBorder(b); memPanel.add(memContPanel, BorderLayout.CENTER); JPanel cpuPanel = new JPanel(new BorderLayout()); cpuPanel.add(new JLabel("CPU", SwingConstants.CENTER), BorderLayout.NORTH); JPanel gpRegPanel = new JPanel(new GridLayout(16,2,5,5)); JPanel spRegPanel = new JPanel(new GridLayout(2,2,5,5)); JPanel regPanel = new JPanel(new FlowLayout(0,15,0)); regPanel.setBorder(b); regPanel.add(gpRegPanel, BorderLayout.EAST); regPanel.add(spRegPanel, BorderLayout.WEST); cpuPanel.add(regPanel, BorderLayout.CENTER); // Create space for regs and memory in // internal arrays for(int i = 0; i < 16; i++) { regs[i][0] = new JLabel("R"+toHex(i,1)); regs[i][1] = new JLabel("00"); } spRegs[0][0] = new JLabel("PC"); spRegs[0][1] = new JLabel("00"); spRegs[1][0] = new JLabel("IR"); spRegs[1][1] = new JLabel("0000"); for(int i = 0; i < 17; i++) { mem[i][0] = new JLabel(toHex(i-1,1), SwingConstants.CENTER); for(int j = 1; j < 17; j++) if (i == 0) mem[i][j] = new JLabel(toHex(j-1,1), SwingConstants.CENTER); else mem[i][j] = new JLabel("00"); } // Reset a special case mem[0][0].setText(""); // Then display the arrays on screen for(int i = 0; i < 16; i++) { gpRegPanel.add(regs[i][0]); gpRegPanel.add(regs[i][1]); } for(int i = 0; i < 2; i++) { spRegPanel.add(spRegs[i][0]); spRegPanel.add(spRegs[i][1]); } for(int i = 0; i < 17; i++) { for(int j = 0; j < 17; j++) memContPanel.add(mem[i][j]); } contPanel.add(cpuPanel, BorderLayout.WEST); contPanel.add(memPanel, BorderLayout.CENTER); JPanel inPanel = new JPanel(new BorderLayout()); inPanel.add(new JLabel("Data Input Window",SwingConstants.CENTER), BorderLayout.NORTH); inArea = new JTextArea(10,10); inArea.setBorder(b); inPanel.add(inArea, BorderLayout.CENTER); contPanel.add(inPanel, BorderLayout.NORTH); JPanel controls = new JPanel(); BListen ops = new BListen(); clearb = new JButton("Clear Memory"); clearb.addActionListener(ops); controls.add(clearb); loadb = new JButton("Load Data"); loadb.addActionListener(ops); controls.add(loadb); runb = new JButton("Run"); runb.addActionListener(ops); controls.add(runb); stepb = new JButton("Single Step"); stepb.addActionListener(ops); controls.add(stepb); haltb = new JButton("Halt"); haltb.addActionListener(ops); controls.add(haltb); helpb = new JButton("Help"); helpb.addActionListener(ops); controls.add(helpb); contPanel.add(controls, BorderLayout.SOUTH); setContentPane(contPanel); } // Next, define the Listener classes that make things work class BListen implements ActionListener { public void actionPerformed(ActionEvent e) { Object button = e.getSource(); if (button == clearb) clearMem(); else if (button == loadb) initMem(); else if (button == runb) doRun(); else if (button == stepb) doStep(); else if (button == haltb) running = false; else if (button == helpb) getHelp(); } } class Runner extends Thread { public void run() { running = true; while (running) doStep(); System.out.println("Simulated execution halted."); } } void clearMem() { for (int i = 1; i < 17; i++) for (int j = 1; j < 17; j++) mem[i][j].setText("00"); } void getHelp() {String helpString = "The machine is programmed by means of the data input window.\n\n" + "The syntax follows these examples:\n" + " [PC] 80 Sets the program counter to 80 (hex).\n" + " [R7] 23 Sets the contents of register 7 to 23 (hex).\n" + " [30] 40 56 C0 00 Sets the contents of memory starting\n" + " at 30 (hex) to the values 40, 56, C0, 00.\n\n" + "The syntax is free format. For example, \n" + " [PC] \n" + " 00 [00] 20 FF\n" + " 40 02 C0 00 \n" + "sets the program counter and memory cells. \n\n" + "Once changes have been entered into the data input window\n" + " they can be transferred into the machine by clicking the\n" + " Load Data button.\n\n" + "Programs can be placed in the data input window or saved from \n" + " the data input window by copying (highlight text and then \n" + " type Ctrl-C) and pasting (Ctrl-V) from or to a text file.\n"; JDialog helpBox = new JDialog(); helpBox.setSize(new Dimension(500, 300)); JTextArea helpArea = new JTextArea(23, 70); helpArea.append(helpString); JScrollPane helpScrollPane = new JScrollPane(helpArea); helpBox.getContentPane().add(helpScrollPane); helpBox.show(); } // Finally, the methods that actually run the machine void initMem() { // Process program input. // Values in square brackets set mem address // for loading of following values. // Value in asterisks sets initial PC. // First, clear various regs, etc. for (int i = 0; i < 16; i++) regs[i][1].setText("00"); spRegs[0][1].setText("00"); spRegs[1][1].setText("0000"); for (int i = 1; i < 17; i++) for (int j = 1; j < 17; j++) mem[i][j].setText("00"); String input = inArea.getText(); // The following code should parse valid input, but will // be unpredictable on invalid input. int address = 0; int rNum = 0; int ptr = 0; boolean chgReg = false; boolean chgMem = false; boolean chgPC = false; while (ptr < input.length()) { char c = input.charAt(ptr); if (c <= ' ') { //System.out.println("skip"); ptr++; continue; } else if (c == '[') { ptr++; c = input.charAt(ptr); if (c == 'R' || c == 'r') { rNum = toInt(input.substring(ptr+1, ptr+2)); chgReg = true; chgMem = false; chgPC = false; } else if (c == 'P' || c =='p') { chgPC = true; chgMem = false; chgReg = false; } else { address = toInt(input.substring(ptr,ptr+2)); chgMem = true; chgPC = false; chgReg = false; } ptr += 3; } else // should be hex digit { //System.out.println("Bottom:"+c+":"); int val = toInt(input.substring(ptr,ptr+2)); //System.out.println("Read:"+val); ptr += 2; if (chgPC) spRegs[0][1].setText(toHex(val,2)); if (chgReg) regs[rNum][1].setText(toHex(val,2)); if (chgMem) { mem[(address/16)+1][(address%16)+1].setText(toHex(val,2)); address++; } } } } void doStep() { //Execute one step of the machine //Get current program counter int loc = toInt(spRegs[0][1].getText()); //I think this next case will never happen, but... if ((loc < 0) || (loc > 0xFE)) { System.out.println("Illegal instruction address"); running = false; return; } //Fetch instruction String byte1 = mem[(loc/16)+1][(loc%16)+1].getText(); loc++; loc &= 0xFF; String byte2 = mem[(loc/16)+1][(loc%16)+1].getText(); loc++; loc &= 0xFF; spRegs[1][1].setText(byte1 + byte2); //Reset PC spRegs[0][1].setText(toHex(loc,2)); int opcode = toInt(byte1.substring(0,1)); if (opcode == 1) //Load { int reg = toInt(byte1.substring(1,2)); int address = toInt(byte2); regs[reg][1].setText(mem[(address/16)+1][(address%16)+1].getText()); } else if (opcode == 2) //Load Immediate { int reg = toInt(byte1.substring(1,2)); regs[reg][1].setText(byte2); } else if (opcode == 3) //Store { int reg = toInt(byte1.substring(1,2)); int address = toInt(byte2); mem[(address/16)+1][(address%16)+1].setText(regs[reg][1].getText()); } else if (opcode == 4) //Reg move { regs[toInt(byte2.substring(1,2))][1].setText(regs[toInt(byte2.substring(0,1))][1].getText()); } else if (opcode == 5) //Add 2's comp { int reg1 = toInt(byte1.substring(1,2)); int reg2 = toInt(byte2.substring(0,1)); int reg3 = toInt(byte2.substring(1,2)); int val2 = toInt(regs[reg2][1].getText()); int val3 = toInt(regs[reg3][1].getText()); int sum = (val2 + val3) & 0xFF; regs[reg1][1].setText(toHex(sum,2)); } else if (opcode == 6) //Add float { int reg1 = toInt(byte1.substring(1,2)); int reg2 = toInt(byte2.substring(0,1)); int reg3 = toInt(byte2.substring(1,2)); int mant2 = (toInt(regs[reg2][1].getText())) % 16; int mant3 = (toInt(regs[reg3][1].getText())) % 16; int exp2 = ((toInt(regs[reg2][1].getText())) & 0x70) / 16; int exp3 = ((toInt(regs[reg3][1].getText())) & 0x70) / 16; int sign[] = new int[2]; sign[0] = 1; sign[1] = -1; int sign1 = 0; int sign2 = (toInt(regs[reg2][1].getText())) / 128; int sign3 = (toInt(regs[reg3][1].getText())) / 128; mant2 = (mant2 << exp2) * sign[sign2]; mant3 = (mant3 << exp3) * sign[sign3]; int mant1 = mant2 + mant3; if (mant1 < 0) { sign1 = 0x8; mant1 = -mant1; } int exp1 = 0; while (mant1 > 15) { mant1 = mant1 / 2; exp1++; } regs[reg1][1].setText(toHex(((sign1 | exp1) * 16) + mant1, 2)); } else if (opcode == 7) //Or { int reg1 = toInt(byte1.substring(1,2)); int reg2 = toInt(byte2.substring(0,1)); int reg3 = toInt(byte2.substring(1,2)); int val2 = toInt(regs[reg2][1].getText()); int val3 = toInt(regs[reg3][1].getText()); int result = val2 | val3; regs[reg1][1].setText(toHex(result,2)); } else if (opcode == 8) //And { int reg1 = toInt(byte1.substring(1,2)); int reg2 = toInt(byte2.substring(0,1)); int reg3 = toInt(byte2.substring(1,2)); int val2 = toInt(regs[reg2][1].getText()); int val3 = toInt(regs[reg3][1].getText()); int result = val2 & val3; regs[reg1][1].setText(toHex(result,2)); } else if (opcode == 9) //Xor { int reg1 = toInt(byte1.substring(1,2)); int reg2 = toInt(byte2.substring(0,1)); int reg3 = toInt(byte2.substring(1,2)); int val2 = toInt(regs[reg2][1].getText()); int val3 = toInt(regs[reg3][1].getText()); int result = val2 ^ val3; regs[reg1][1].setText(toHex(result,2)); } else if (opcode == 0xA) //Rotate { int reg = toInt(byte1.substring(1,2)); int val = (toInt(byte2.substring(1,2))) % 8; int bits = toInt(regs[reg][1].getText()); bits = bits << (8 - val); int hbits = (0xFF00 & bits) >> 8; int lbits = (0x00FF & bits); regs[reg][1].setText(toHex((hbits | lbits), 2)); } else if (opcode == 0xB) //Branch { int reg = toInt(byte1.substring(1,2)); String val1 = regs[0][1].getText(); String val2 = regs[reg][1].getText(); if (val1.equals(val2)) spRegs[0][1].setText(byte2); } else if (opcode == 0xC) //Halt { running = false; } else if (opcode == 0xD) //Load indirect { int reg1 = toInt(byte1.substring(1,2)); int reg2 = toInt(byte2.substring(1,2)); int addr = toInt(regs[reg2][1].getText()); regs[reg1][1].setText(mem[(addr / 16) +1][(addr % 16) + 1].getText()); } else if (opcode == 0xE) //Store indirect { int reg1 = toInt(byte1.substring(1,2)); int reg2 = toInt(byte2.substring(1,2)); int addr = toInt(regs[reg2][1].getText()); mem[(addr / 16) + 1][(addr % 16) + 1].setText(regs[reg1][1].getText()); } else { System.out.println("Unexpected opcode="+opcode); running = false; } } void doRun() { // Use a separate Thread to run the program. This way // we can stop an infinite loop (with the Halt button). Runner r = new Runner(); r.start(); } }