Unit testing. MemoryRange work.

src/main/java/com/loomcom/lm6502/AddressDecoder.java

@@ -1,20 +1,32 @@
 package com.loomcom.lm6502;
 
-import java.util.Map;
+import java.util.*;
 
 public class AddressDecoder {
-	/**
-	 * Map of memory ranges to IO devices.
-	 */
-	private Map<MemoryRange, Device> m_ioMap;
 
-	public AddressDecoder() {}
+	public static final int MEMORY_BOTTOM = 0x0000;
+	public static final int MEMORY_TOP = 0xFFFF;
+
+	/**
+	 * Ordered map of memory ranges to IO devices.
+	 */
+	private SortedMap<MemoryRange, Device> ioMap;
+
+	public AddressDecoder() {
+		ioMap = new TreeMap();
+	}
 
 	public void addDevice(Device d)
-		throws MemoryConflictException {
+		throws MemoryRangeException {
 		// Make sure there's no memory overlap.
+		for (MemoryRange memRange : ioMap.keySet()) {
+			if (d.getMemoryRange().overlapsWith(memRange)) {
+				throw new MemoryRangeException("The device being added overlaps with an existing device.");
+			}
+		}
+
 		// Add the device to the map.
-		m_ioMap.put(d.getMemoryRange(), d);
+		ioMap.put(d.getMemoryRange(), d);
 	}
 
 	/**
@@ -23,49 +35,40 @@ public class AddressDecoder {
 	 * device.
 	 */
 	public boolean isComplete() {
+		// Emtpy maps cannot be complete.
+		if (ioMap.isEmpty()) { return false; }
+
+		// Loop over devices and ensure they are contiguous.
+		MemoryRange prev = null;
+		int i = 0;
+		int size = ioMap.size();
+		for (Map.Entry e : ioMap.entrySet()) {
+			MemoryRange cur = (MemoryRange)e.getKey();
+			if (i == 0) {
+				// If the first entry doesn't start at MEMORY_BOTTOM, return false.
+				if (cur.getStartAddress() != MEMORY_BOTTOM) { return false; }
+			} else if (i < size - 1) {
+				// Otherwise, compare previous map's end against this map's
+				// top.  They must be adjacent!
+				if (cur.getStartAddress() - 1 != prev.getEndAddress()) {
+					return false;
+				}
+			} else {
+				// If the last entry doesn't end at MEMORY_TOP, return false;
+				if (cur.getEndAddress() != MEMORY_TOP) { return false; }
+			}
+			i++;
+			prev = cur;
+		}
+
+		// Must be complete.
 		return true;
 	}
 
 	/**
-	 * Returns true if the memory map is 'sparse', i.e., there
-	 * are gaps between IO devices.
+	 * Returns true if there are any gap in the memory map.
 	 */
-	public boolean isSparse() {
+	public boolean hasGaps() {
 		return !isComplete();
 	}
-}
-
-class MemoryRange {
-	public int m_startAddress;
-	public int m_endAddress;
-
-	/**
-	 * @returns true if the address is included within this range,
-	 *					false otherwise.
-	 */
-	public boolean includes(int address) {
-		return (address <= m_endAddress &&
-						address >= m_startAddress);
-	}
-
-	public void setStartAddress(int startAddress) {
-		m_startAddress = startAddress;
-	}
-
-	public void setEndAddress(int endAddress) {
-		m_endAddress = endAddress;
-	}
-
-	public int getStartAddress() {
-		return m_startAddress;
-	}
-
-	public int getEndAddress() {
-		return m_endAddress;
-	}
-}
-
-/**
- * Excption that will be thrown if devices conflict in the IO map.
- */
-class MemoryConflictException extends Exception {}
+}

src/main/java/com/loomcom/lm6502/CommandParser.java

@@ -4,13 +4,14 @@ import java.io.*;
 
 public class CommandParser {
 
-	private BufferedReader m_in;
-	private BufferedWriter m_out;
-	private Simulator m_simulator;
+	private BufferedReader in;
+	private BufferedWriter out;
+	private Simulator simulator;
 
-	public CommandParser(InputStream in, OutputStream out, Simulator s) {
-		m_in	= new BufferedReader(new InputStreamReader(in));
-		m_out = new BufferedWriter(new OutputStreamWriter(out));
+	public CommandParser(InputStream i, OutputStream o, Simulator s) {
+		this.in = new BufferedReader(new InputStreamReader(i));
+		this.out = new BufferedWriter(new OutputStreamWriter(o));
+		this.simulator = s;
 	}
 
 	public void run() {
@@ -45,20 +46,20 @@ public class CommandParser {
 	}
 
 	private void prompt() throws IOException {
-		m_out.write("j6502> ");
-		m_out.flush();
+		out.write("j6502> ");
+		out.flush();
 	}
 
 	private String readLine() throws IOException {
-		String line = m_in.readLine();
+		String line = in.readLine();
 		if (line == null) { return null; }
 		return line.trim();
 	}
 
 	private void writeLine(String line) throws IOException {
-		m_out.write(line);
-		m_out.newLine();
-		m_out.flush();
+		out.write(line);
+		out.newLine();
+		out.flush();
 	}
 
 	/**

src/main/java/com/loomcom/lm6502/Cpu.java

@@ -5,33 +5,22 @@ package com.loomcom.lm6502;
  */
 public class Cpu {
 
-	/**
-	 * The Program Counter.
-	 */
-	private int m_pc;
-
-	/**
-	 * The system stack pointer.
-	 */
-	private int m_sp;
-
-	/**
-	 * Reference to the simulator
-	 */
-	private Simulator m_sim;
+	private int pc;
+	private int sp;
+	private Simulator sim;
 
 	public Cpu(Simulator sim) {
 		reset();
-		this.m_sim = sim;
+		this.sim = sim;
 	}
 
 	/**
 	 * Reset the CPU to known initial values.
 	 */
 	public void reset() {
-		m_sp = 0x01ff;
+		sp = 0x01ff;
 		/* locations fffc and fffd hold the reset vector address */
-		m_pc = 0xfffc;
+		pc = 0xfffc;
 	}
 
 	/**
@@ -51,7 +40,7 @@ public class Cpu {
 	 *         Program Counter.
 	 */
 	private int readAddress() {
-		return readAddress(m_pc);
+		return readAddress(pc);
 	}
 
 	/**
@@ -62,11 +51,11 @@ public class Cpu {
 	 * @return The address specified in the two bytes at location <tt>addr</tt>
 	 */
 	private int readAddress(int address) {
-		return (m_sim.read(address)<<8 & m_sim.read(address+1));
+		return (sim.read(address)<<8 & sim.read(address+1));
 	}
 
 	public Simulator getSimulator() {
-		return m_sim;
+		return sim;
 	}
 
 }

src/main/java/com/loomcom/lm6502/Device.java

@@ -7,34 +7,34 @@
 public abstract class Device {
 
 	/** The memory range for this device. */
-	private MemoryRange m_memoryRange;
+	private MemoryRange memoryRange;
 
 	/** Reference to the CPU, for interrupts. */
-	private Cpu m_cpu;
+	private Cpu cpu;
 
 	public Device(MemoryRange range, Cpu cpu) {
-		m_memoryRange = range;
-		m_cpu = cpu;
+		this.memoryRange = range;
+		this.cpu = cpu;
 	}
 
 	public MemoryRange getMemoryRange() {
-		return m_memoryRange;
+		return memoryRange;
 	}
 
 	public int getEndAddress() {
-		return m_memoryRange.getEndAddress();
+		return memoryRange.getEndAddress();
 	}
 
 	public int getStartAddress() {
-		return m_memoryRange.getStartAddress();
+		return memoryRange.getStartAddress();
 	}
 
 	public void generateInterrupt() {
-		m_cpu.interrupt();
+		cpu.interrupt();
 	}
 
 	public void generateNonMaskableInterrupt() {
-		m_cpu.nmiInterrupt();
+		cpu.nmiInterrupt();
 	}
 
 }

src/main/java/com/loomcom/lm6502/MemoryRange.java

@@ -0,0 +1,66 @@
+package com.loomcom.lm6502;
+
+public class MemoryRange implements Comparable<MemoryRange> {
+	public int startAddress;
+	public int endAddress;
+
+	public MemoryRange(int startAddress, int endAddress)
+		    throws MemoryRangeException {
+		if (startAddress < 0 || endAddress < 0) {
+			throw new MemoryRangeException("Addresses cannot be less than 0.");
+		}
+		if (startAddress >= endAddress) {
+			throw new MemoryRangeException("End address must be greater than start address.");
+		}
+		this.startAddress = startAddress;
+		this.endAddress = endAddress;
+	}
+
+	public int getStartAddress() {
+		return startAddress;
+	}
+
+	public int getEndAddress() {
+		return endAddress;
+	}
+
+	/**
+	 * Checks for address inclusion in the range.
+	 *
+	 * @returns true if the address is included within this range,
+	 *					false otherwise.
+	 */
+	public boolean includes(int address) {
+		return (address <= endAddress &&
+		        address >= startAddress);
+	}
+
+	/**
+	 * Checks for overlapping memory ranges.
+	 *
+	 * @returns true if this range overlaps in any way with the other.
+	 */
+	public boolean overlapsWith(MemoryRange other) {
+		return ((this.getEndAddress() >= other.getStartAddress() &&
+						 this.getEndAddress() <= other.getEndAddress()) ||
+						(other.getEndAddress() >= this.getStartAddress() &&
+						 other.getEndAddress() <= this.getEndAddress()) ||
+						(this.getStartAddress() <= other.getStartAddress() &&
+						 this.getEndAddress() >= other.getEndAddress()) ||
+						(other.getStartAddress() <= this.getStartAddress() &&
+						 other.getEndAddress() >= this.getEndAddress()));
+	}
+
+	// Implementation of Comparable interface
+	public int compareTo(MemoryRange other) {
+		if (other == null) {
+			throw new NullPointerException("Cannot compare to null.");
+		}
+		if (this == other) {
+			return 0;
+		}
+		Integer thisStartAddr = new Integer(this.getStartAddress());
+		Integer thatStartAddr = new Integer(other.getStartAddress());
+		return thisStartAddr.compareTo(thatStartAddr);
+	}
+}

src/main/java/com/loomcom/lm6502/MemoryRangeException.java

@@ -0,0 +1,10 @@
+package com.loomcom.lm6502;
+
+/**
+ * Exception that will be thrown if devices conflict in the IO map.
+ */
+class MemoryRangeException extends Exception {
+	public MemoryRangeException(String msg) {
+		super(msg);
+	}
+}