Fix off-by-one error with data address bounds & unit test to cover

Java/src/main/java/org/ciyam/at/Utils.java

@@ -71,7 +71,7 @@ interface Utils {
 		try {
 			final int address = codeByteBuffer.getInt() * MachineState.VALUE_SIZE;
 
-			if (address < 0 || address + MachineState.VALUE_SIZE >= dataByteBuffer.limit())
+			if (address < 0 || address + MachineState.VALUE_SIZE > dataByteBuffer.limit())
 				throw new InvalidAddressException("Data address out of bounds");
 
 			return address;

Java/src/test/java/org/ciyam/at/MiscTests.java

@@ -68,4 +68,18 @@ public class MiscTests extends ExecutableTest {
 		assertEquals((Long) (minActivationAmount - 1L), state.getFrozenBalance());
 	}
 
+	@Test
+	public void testDataAddressBounds() throws ExecutionException {
+		// Last possible valid address in data segment
+		int lastDataAddress = (dataByteBuffer.limit() / MachineState.VALUE_SIZE) - 1;
+
+		codeByteBuffer.put(OpCode.SET_VAL.value).putInt(lastDataAddress).putLong(8888L);
+		codeByteBuffer.put(OpCode.FIN_IMD.value);
+
+		execute(true);
+
+		assertTrue(state.isFinished());
+		assertFalse(state.hadFatalError());
+	}
+
 }