DroidFish: Implemented support for external UCI engines.

DroidFish/res/menu/options_menu.xml

@@ -42,6 +42,10 @@
     <item
         android:id="@+id/select_book"
         android:title="@string/option_select_book">
+    </item>
+    <item
+        android:id="@+id/select_engine"
+        android:title="@string/option_select_engine">
     </item>
         <item
         android:id="@+id/set_color_theme"

DroidFish/res/values-de/strings.xml

@@ -1,14 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <string name="app_name">DroidFish</string>
-    <string-array name="engine_texts">
+
-        <item>Stockfish</item>
-        <item>CuckooChess</item>
-    </string-array>
-    <string-array name="engine_values">
-       <item>stockfish</item>
-       <item>cuckoochess</item>
-    </string-array>
     <string-array name="engine_threads_texts">
         <item>Automatisch</item>
         <item>1</item>
@@ -414,8 +407,6 @@ wenn Sie es nicht aktiv nutzen.\
     <string name="prefs_autoSwapSides_title">Automatischer Seitenwechsel</string>
     <string name="prefs_autoSwapSides_summary">Seiten beim Start einer neuen Partie automatisch wechseln (Einstellung <i>Ansicht drehen</i> ignorieren)</string>
     <string name="prefs_engine_settings">Engine-Einstellungen</string>
-    <string name="prefs_engine_title">Schach-Engine</string>
-    <string name="prefs_engine_summary">Auswahl der Schach-Engine</string>
     <string name="prefs_strength_title">Spielstärke</string>
     <string name="prefs_ponderMode_title">Vorausberechnung</string>
     <string name="prefs_ponderMode_summary">Vorausberechnung von Zügen durch die Engine, wenn der Spieler am Zug ist</string>

DroidFish/res/values/strings.xml

@@ -1,15 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <string name="app_name">DroidFish</string>
-    <string-array name="engine_texts">
-        <item>Stockfish</item>
-        <item>CuckooChess</item>
-    </string-array>
-    <string-array name="engine_values">
-       <item>stockfish</item>
-       <item>cuckoochess</item>
-    </string-array>
-    <string name="engine_default">stockfish</string>
 
     <string-array name="engine_threads_texts">
         <item>Automatic</item>
@@ -305,6 +296,7 @@ you are not actively using the program.\
     <string name="edit_move_counters">Edit Move Counters</string>
     <string name="internal_book">&lt;Internal Book&gt;</string>
     <string name="select_opening_book_file">Select opening book file</string>
+    <string name="select_chess_engine">Select Chess Engine</string>
     <string name="select_pgn_file">Select PGN file to open</string>
     <string name="select_pgn_file_save">Save to PGN file</string>
     <string name="select_scid_file">Select Scid file to open</string>
@@ -401,6 +393,9 @@ you are not actively using the program.\
     <string name="after_selected">After Selected</string>
     <string name="replace_selected">Replace Selected</string>
     <string name="engine">Engine</string>
+    <string name="engine_error">Engine error</string>
+    <string name="stockfish_engine">Stockfish</string>
+    <string name="cuckoochess_engine">CuckooChess</string>
 
     <string name="err_too_few_spaces">Too few spaces</string>
     <string name="err_invalid_piece">Invalid piece</string>
@@ -425,6 +420,7 @@ you are not actively using the program.\
     <string name="option_force_computer_move">Force Computer Move</string>
     <string name="option_draw">Claim/Offer/Accept Draw</string>
     <string name="option_select_book">Select Opening Book</string>
+    <string name="option_select_engine">Select Chess Engine</string>
     <string name="option_color_theme">Set Color Theme</string>
     <string name="option_about">About / Help</string>
 
@@ -434,8 +430,6 @@ you are not actively using the program.\
     <string name="prefs_autoSwapSides_title">Auto Swap Sides</string>
     <string name="prefs_autoSwapSides_summary">Automatically swap sides when new game started. Also overrides Flip Board setting</string>
     <string name="prefs_engine_settings">Engine Settings</string>
-    <string name="prefs_engine_title">Engine</string>
-    <string name="prefs_engine_summary">Chess Engine</string>
     <string name="prefs_strength_title">Strength</string>
     <string name="prefs_ponderMode_title">Pondering</string>
     <string name="prefs_ponderMode_summary">Let engine think while waiting for opponent\'s move</string>

DroidFish/res/xml/preferences.xml

@@ -18,14 +18,6 @@
     </PreferenceCategory>
     <PreferenceCategory
         android:title="@string/prefs_engine_settings">
-        <ListPreference
-            android:key="engine"
-            android:title="@string/prefs_engine_title"
-            android:summary="@string/prefs_engine_summary"
-            android:entryValues="@array/engine_values"
-            android:entries="@array/engine_texts"
-            android:defaultValue="@string/engine_default">
-        </ListPreference>
         <org.petero.droidfish.SeekBarPreference
             android:key="strength"
             android:defaultValue="1000"

DroidFish/src/org/petero/droidfish/DroidFish.java

@@ -160,6 +160,7 @@ public class DroidFish extends Activity implements GUIInterface {
 
     private final static String bookDir = "DroidFish";
     private final static String pgnDir = "DroidFish" + File.separator + "pgn";
+    private final static String engineDir = "DroidFish" + File.separator + "uci";
     private BookOptions bookOptions = new BookOptions();
     private PGNOptions pgnOptions = new PGNOptions();
 
@@ -732,6 +733,10 @@ public class DroidFish extends Activity implements GUIInterface {
             removeDialog(SELECT_BOOK_DIALOG);
             showDialog(SELECT_BOOK_DIALOG);
             return true;
+        case R.id.select_engine:
+            removeDialog(SELECT_ENGINE_DIALOG);
+            showDialog(SELECT_ENGINE_DIALOG);
+            return true;
         case R.id.set_color_theme:
             showDialog(SET_COLOR_THEME_DIALOG);
             return true;
@@ -1004,16 +1009,17 @@ public class DroidFish extends Activity implements GUIInterface {
     static private final int ABOUT_DIALOG = 2;
     static private final int SELECT_MOVE_DIALOG = 3;
     static private final int SELECT_BOOK_DIALOG = 4;
-    static private final int SELECT_PGN_FILE_DIALOG = 5;
+    static private final int SELECT_ENGINE_DIALOG = 5;
-    static private final int SELECT_PGN_FILE_SAVE_DIALOG = 6;
+    static private final int SELECT_PGN_FILE_DIALOG = 6;
-    static private final int SET_COLOR_THEME_DIALOG = 7;
+    static private final int SELECT_PGN_FILE_SAVE_DIALOG = 7;
-    static private final int GAME_MODE_DIALOG = 8;
+    static private final int SET_COLOR_THEME_DIALOG = 8;
-    static private final int SELECT_PGN_SAVE_NEWFILE_DIALOG = 9;
+    static private final int GAME_MODE_DIALOG = 9;
-    static private final int MOVELIST_MENU_DIALOG = 10;
+    static private final int SELECT_PGN_SAVE_NEWFILE_DIALOG = 10;
-    static private final int THINKING_MENU_DIALOG = 11;
+    static private final int MOVELIST_MENU_DIALOG = 11;
-    static private final int GO_BACK_MENU_DIALOG = 12;
+    static private final int THINKING_MENU_DIALOG = 12;
-    static private final int GO_FORWARD_MENU_DIALOG = 13;
+    static private final int GO_BACK_MENU_DIALOG = 13;
-    static private final int FILE_MENU_DIALOG = 14;
+    static private final int GO_FORWARD_MENU_DIALOG = 14;
+    static private final int FILE_MENU_DIALOG = 15;
 
     @Override
     protected Dialog onCreateDialog(int id) {
@@ -1225,6 +1231,45 @@ public class DroidFish extends Activity implements GUIInterface {
             AlertDialog alert = builder.create();
             return alert;
         }
+        case SELECT_ENGINE_DIALOG: {
+            String[] fileNames = findFilesInDirectory(engineDir, null);
+            final int numFiles = fileNames.length;
+            final String[] items = new String[numFiles + 2];
+            final String[] ids = new String[numFiles + 2];
+            ids[0] = "stockfish";   items[0] = getString(R.string.stockfish_engine);
+            ids[1] = "cuckoochess"; items[1] = getString(R.string.cuckoochess_engine);
+            String sep = File.separator;
+            String base = Environment.getExternalStorageDirectory() + sep + engineDir + sep;
+            for (int i = 0; i < numFiles; i++) {
+                ids[i+2] = base + fileNames[i];
+                items[i+2] = fileNames[i];
+            }
+            String currEngine = ctrl.getEngine();
+            int defaultItem = 0;
+            for (int i = 0; i < ids.length; i++) {
+                if (ids[i].equals(currEngine)) {
+                    defaultItem = i;
+                    break;
+                }
+            }
+            AlertDialog.Builder builder = new AlertDialog.Builder(this);
+            builder.setTitle(R.string.select_chess_engine);
+            builder.setSingleChoiceItems(items, defaultItem, new DialogInterface.OnClickListener() {
+                public void onClick(DialogInterface dialog, int item) {
+                    if ((item < 0) || (item >= ids.length))
+                        return;
+                    Editor editor = settings.edit();
+                    String engine = ids[item];
+                    editor.putString("engine", engine);
+                    editor.commit();
+                    dialog.dismiss();
+                    int strength = settings.getInt("strength", 1000);
+                    setEngineStrength(engine, strength);
+                }
+            });
+            AlertDialog alert = builder.create();
+            return alert;
+        }
         case SELECT_PGN_FILE_DIALOG: {
             final String[] fileNames = findFilesInDirectory(pgnDir, null);
             final int numFiles = fileNames.length;
@@ -1773,6 +1818,13 @@ public class DroidFish extends Activity implements GUIInterface {
         Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_SHORT).show();
     }
 
+    @Override
+    public void reportEngineError(String errMsg) {
+        String msg = String.format("%s: %s",
+                getString(R.string.engine_error), errMsg);
+        Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_LONG).show();
+    }
+
     @Override
     public void computerMoveMade() {
         if (soundEnabled) {

DroidFish/src/org/petero/droidfish/GUIInterface.java

@@ -67,6 +67,9 @@ public interface GUIInterface {
     /** Report UCI engine name. */
     public void reportEngineName(String engine);
 
+    /** Report UCI engine error message. */
+    public void reportEngineError(String errMsg);
+
     /** Called when computer made a move. GUI can notify user, for example by playing a sound. */
     public void computerMoveMade();
 

DroidFish/src/org/petero/droidfish/engine/DroidComputerPlayer.java

@@ -25,7 +25,6 @@ import java.util.ArrayList;
 
 import org.petero.droidfish.book.BookOptions;
 import org.petero.droidfish.book.DroidBook;
-import org.petero.droidfish.engine.cuckoochess.CuckooChessEngine;
 import org.petero.droidfish.gamelogic.Move;
 import org.petero.droidfish.gamelogic.MoveGen;
 import org.petero.droidfish.gamelogic.Pair;
@@ -292,10 +291,10 @@ public class DroidComputerPlayer {
     /** Stop the engine process. */
     public final synchronized void shutdownEngine() {
         if (uciEngine != null) {
-            uciEngine.shutDown();
-            uciEngine = null;
             engineMonitor.interrupt();
             engineMonitor = null;
+            uciEngine.shutDown();
+            uciEngine = null;
         }
         engineState.state = MainState.DEAD;
     }
@@ -543,15 +542,20 @@ public class DroidComputerPlayer {
         myAssert(searchRequest != null);
 
         engineName = "Computer";
-        if ("cuckoochess".equals(searchRequest.engine))
+        uciEngine = UCIEngineBase.getEngine(searchRequest.engine, new UCIEngine.Report() {
-            uciEngine = new CuckooChessEngine();
+            @Override
-        else
+            public void reportError(String errMsg) {
-            uciEngine = new StockFishJNI();
+                if (errMsg != null) {
+                    listener.reportEngineError(errMsg);
+                }
+            }
+        });
         uciEngine.initialize();
 
+        final UCIEngine uci = uciEngine;
         engineMonitor = new Thread(new Runnable() {
             public void run() {
-                monitorLoop();
+                monitorLoop(uci);
             }
         });
         engineMonitor.start();
@@ -569,16 +573,17 @@ public class DroidComputerPlayer {
     private final static long guiUpdateInterval = 100;
     private long lastGUIUpdate = 0;
 
-    private final void monitorLoop() {
+    private final void monitorLoop(UCIEngine uci) {
         while (true) {
             int timeout = getReadTimeout();
-            UCIEngine uci = uciEngine;
-            if (uci == null)
-                return;
-            String s = uci.readLineFromEngine(timeout);
             if (Thread.currentThread().isInterrupted())
                 return;
-            processEngineOutput(s);
+            String s = uci.readLineFromEngine(timeout);
+            if ((s == null) || Thread.currentThread().isInterrupted())
+                return;
+            processEngineOutput(uci, s);
+            if (Thread.currentThread().isInterrupted())
+                return;
             notifyGUI();
             if (Thread.currentThread().isInterrupted())
                 return;
@@ -586,7 +591,10 @@ public class DroidComputerPlayer {
     }
 
     /** Process one line of data from the engine. */
-    private final synchronized void processEngineOutput(String s) {
+    private final synchronized void processEngineOutput(UCIEngine uci, String s) {
+        if (Thread.currentThread().isInterrupted())
+            return;
+
         if (s == null) {
             shutdownEngine();
             return;
@@ -595,17 +603,13 @@ public class DroidComputerPlayer {
         if (s.length() == 0)
             return;
 
-        UCIEngine uci = uciEngine;
-        if (uci == null)
-            return;
         switch (engineState.state) {
         case READ_OPTIONS: {
             if (readUCIOption(s)) {
-                if (!"cuckoochess".equals(engineState.engine))
+                uci.initOptions();
-                    uci.setOption("Hash", 16);
                 uci.setOption("Ponder", false);
                 uci.writeLineToEngine("ucinewgame");
-                uciEngine.writeLineToEngine("isready");
+                uci.writeLineToEngine("isready");
                 engineState.state = MainState.WAIT_READY;
             }
             break;
@@ -642,7 +646,7 @@ public class DroidComputerPlayer {
         case STOP_SEARCH: {
             String[] tokens = tokenize(s);
             if (tokens[0].equals("bestmove")) {
-                uciEngine.writeLineToEngine("isready");
+                uci.writeLineToEngine("isready");
                 engineState.state = MainState.WAIT_READY;
             }
             break;
@@ -860,6 +864,9 @@ public class DroidComputerPlayer {
 
     /** Notify GUI about search statistics. */
     private final synchronized void notifyGUI() {
+        if (Thread.currentThread().isInterrupted())
+            return;
+
         long now = System.currentTimeMillis();
         if (now < lastGUIUpdate + guiUpdateInterval)
             return;

DroidFish/src/org/petero/droidfish/engine/ExternalEngine.java

@@ -0,0 +1,183 @@
+package org.petero.droidfish.engine;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.channels.FileChannel;
+import java.util.LinkedList;
+import java.util.List;
+
+public class ExternalEngine extends UCIEngineBase {
+    private File engineFileName;
+    private static final String exePath = "/data/data/org.petero.droidfish/engine.exe";
+    private final Report report;
+    private Process engineProc;
+    private Thread stdInThread;
+    private Thread stdErrThread;
+    private List<String> inLines;
+
+    public ExternalEngine(String engine, Report report) {
+        this.report = report;
+        engineFileName = new File(engine);
+        engineProc = null;
+        stdInThread = null;
+        stdErrThread = null;
+        inLines = new LinkedList<String>();
+    }
+
+    /** @inheritDoc */
+    @Override
+    protected void startProcess() {
+        try {
+            copyFile(engineFileName, new File(exePath));
+            chmod(exePath);
+            ProcessBuilder pb = new ProcessBuilder(exePath);
+            engineProc = pb.start();
+
+            // Start a thread to read stdin
+            stdInThread = new Thread(new Runnable() {
+                @Override
+                public void run() {
+                    Process ep = engineProc;
+                    if (ep == null)
+                        return;
+                    InputStream is = ep.getInputStream();
+                    InputStreamReader isr = new InputStreamReader(is);
+                    BufferedReader br = new BufferedReader(isr);
+                    String line;
+                    try {
+                        while ((line = br.readLine()) != null) {
+                            if ((ep == null) || Thread.currentThread().isInterrupted())
+                                return;
+                            synchronized (inLines) {
+                                inLines.add(line);
+                                inLines.notify();
+                            }
+                        }
+                    } catch (IOException e) {
+                        return;
+                    }
+                }
+            });
+            stdInThread.start();
+
+            // Start a thread to ignore stderr
+            stdErrThread = new Thread(new Runnable() {
+                @Override
+                public void run() {
+                    byte[] buffer = new byte[128];
+                    while (true) {
+                        Process ep = engineProc;
+                        if ((ep == null) || Thread.currentThread().isInterrupted())
+                            return;
+                        try {
+                            ep.getErrorStream().read(buffer);
+                        } catch (IOException e) {
+                            return;
+                        }
+                    }
+                }
+            });
+            stdErrThread.start();
+        } catch (IOException ex) {
+            report.reportError(ex.getMessage());
+        }
+    }
+
+    /** @inheritDoc */
+    @Override
+    public void initOptions() {
+        setOption("Hash", 16);
+    }
+
+    /** @inheritDoc */
+    @Override
+    public void setStrength(int strength) {
+    }
+
+    /** @inheritDoc */
+    @Override
+    public String readLineFromEngine(int timeoutMillis) {
+        try {
+            synchronized (inLines) {
+                if (inLines.size() == 0) {
+                    Thread inThread = stdInThread;
+                    if ((inThread == null) || !inThread.isAlive())
+                        return null;
+                    inLines.wait(timeoutMillis);
+                }
+            }
+            synchronized (inLines) {
+                if (inLines.size() > 0) {
+                    String ret = inLines.get(0);
+                    inLines.remove(0);
+//                    System.out.printf("Engine -> GUI: %s\n", ret);
+                    return ret;
+                }
+            }
+        } catch (InterruptedException e) {
+        }
+        return "";
+    }
+
+    /** @inheritDoc */
+    @Override
+    public void writeLineToEngine(String data) {
+//        System.out.printf("GUI -> Engine: %s\n", data);
+        data += "\n";
+        try {
+            Process ep = engineProc;
+            if (ep != null)
+                ep.getOutputStream().write(data.getBytes());
+        } catch (IOException e) {
+        }
+    }
+
+    /** @inheritDoc */
+    @Override
+    public void shutDown() {
+        super.shutDown();
+        if (engineProc != null)
+            engineProc.destroy();
+        engineProc = null;
+        if (stdInThread != null)
+            stdInThread.interrupt();
+        if (stdErrThread != null)
+            stdErrThread.interrupt();
+    }
+
+    private final static void copyFile(File from, File to) throws IOException {
+        if (to.exists() && (from.length() == to.length()) && (from.lastModified() == to.lastModified()))
+            return;
+        if (to.exists())
+            to.delete();
+        to.createNewFile();
+        FileChannel inFC = null;
+        FileChannel outFC = null;
+        try {
+            inFC = new FileInputStream(from).getChannel();
+            outFC = new FileOutputStream(to).getChannel();
+            long cnt = outFC.transferFrom(inFC, 0, inFC.size());
+            if (cnt < inFC.size())
+                throw new IOException("File copy failed");
+        } finally {
+            if (inFC != null) { try { inFC.close(); } catch (IOException ex) {} }
+            if (outFC != null) { try { outFC.close(); } catch (IOException ex) {} }
+            to.setLastModified(from.lastModified());
+        }
+    }
+
+    private final void chmod(String exePath) throws IOException {
+        Process proc = Runtime.getRuntime().exec(new String[]{"chmod", "744", exePath});
+        try {
+            proc.waitFor();
+        } catch (InterruptedException e) {
+            proc.destroy();
+            throw new IOException("chmod failed");
+        }
+    }
+}

DroidFish/src/org/petero/droidfish/engine/StockFishJNI.java

@@ -23,18 +23,19 @@ public class StockFishJNI extends UCIEngineBase {
         System.loadLibrary("stockfishjni");
     }
 
+    /** @inheritDoc */
     @Override
-    public void setStrength(int strength) {
+    public final void initOptions() {
+        setOption("Hash", 16);
+    }
+
+    /** @inheritDoc */
+    @Override
+    public final void setStrength(int strength) {
         setOption("Skill Level", strength/50);
     }
 
-    /**
+    /** @inheritDoc */
-     * Read a line from the process.
-     * @param timeoutMillis Maximum time to wait for data
-     * @return The line, without terminating newline characters,
-     *         or empty string if no data available,
-     *         or null if I/O error.
-     */
     @Override
     public final String readLineFromEngine(int timeoutMillis) {
         String ret = readFromProcess(timeoutMillis);
@@ -46,14 +47,15 @@ public class StockFishJNI extends UCIEngineBase {
         return ret;
     }
 
-    /** Write a line to the process. \n will be added automatically. */
+    /** @inheritDoc */
     @Override
     public final synchronized void writeLineToEngine(String data) {
 //      System.out.printf("GUI -> Engine: %s\n", data);
         writeToProcess(data + "\n");
     }
 
-    /** Start the child process. */
+    /** @inheritDoc */
+    @Override
     protected final native void startProcess();
 
     /**

DroidFish/src/org/petero/droidfish/engine/UCIEngine.java

@@ -20,15 +20,24 @@ package org.petero.droidfish.engine;
 
 public interface UCIEngine {
 
+    /** For reporting engine error messages. */
+    public interface Report {
+        /** Report error message to GUI. */
+        void reportError(String errMsg);
+    }
+
     /** Start engine. */
     public void initialize();
 
+    /** Initialize default options. */
+    public void initOptions();
+
     /** Shut down engine. */
     public void shutDown();
 
     /**
      * Read a line from the engine.
-     * @param timeoutMillis Maximum time to wait for data
+     * @param timeoutMillis Maximum time to wait for data.
      * @return The line, without terminating newline characters,
      *         or empty string if no data available,
      *         or null if I/O error.

DroidFish/src/org/petero/droidfish/engine/UCIEngineBase.java

@@ -2,10 +2,21 @@ package org.petero.droidfish.engine;
 
 import java.util.HashMap;
 
+import org.petero.droidfish.engine.cuckoochess.CuckooChessEngine;
+
 public abstract class UCIEngineBase implements UCIEngine {
 
     private boolean processAlive;
 
+    public static UCIEngine getEngine(String engine, Report report) {
+        if ("cuckoochess".equals(engine))
+            return new CuckooChessEngine(report);
+        else if ("stockfish".equals(engine))
+            return new StockFishJNI();
+        else
+            return new ExternalEngine(engine, report);
+    }
+
     protected UCIEngineBase() {
         processAlive = false;
     }
@@ -21,7 +32,7 @@ public abstract class UCIEngineBase implements UCIEngine {
     }
 
     @Override
-    public final void shutDown() {
+    public void shutDown() {
         if (processAlive) {
             writeLineToEngine("quit");
             processAlive = false;

DroidFish/src/org/petero/droidfish/engine/cuckoochess/CuckooChessEngine.java

@@ -51,12 +51,8 @@ public class CuckooChessEngine extends UCIEngineBase {
     private NioInputStream inFromEngine;
     private Thread engineThread;
 
-    public CuckooChessEngine() {
+    public CuckooChessEngine(Report report) {
-        try {
+        pos = null;
-            pos = TextIO.readFEN(TextIO.startPosFEN);
-        } catch (ChessParseError ex) {
-            throw new RuntimeException();
-        }
         moves = new ArrayList<Move>();
         quit = false;
         try {
@@ -64,14 +60,12 @@ public class CuckooChessEngine extends UCIEngineBase {
             engineToGui = Pipe.open();
             inFromEngine = new NioInputStream(engineToGui);
         } catch (IOException e) {
+            report.reportError(e.getMessage());
         }
     }
 
+    /** @inheritDoc */
     @Override
-    public void setStrength(int strength) {
-        setOption("strength", strength);
-    }
-
     protected final void startProcess() {
         engineThread = new Thread(new Runnable() {
             public void run() {
@@ -87,6 +81,17 @@ public class CuckooChessEngine extends UCIEngineBase {
         engineThread.start();
     }
 
+    /** @inheritDoc */
+    @Override
+    public final void initOptions() {
+    }
+
+    /** @inheritDoc */
+    @Override
+    public final void setStrength(int strength) {
+        setOption("strength", strength);
+    }
+
     private final void mainLoop(NioInputStream is, NioPrintStream os) {
         String line;
         while ((line = is.readLine()) != null) {
@@ -97,6 +102,7 @@ public class CuckooChessEngine extends UCIEngineBase {
         }
     }
 
+    /** @inheritDoc */
     @Override
     public final String readLineFromEngine(int timeoutMillis) {
         if ((engineThread != null) && !engineThread.isAlive())
@@ -110,6 +116,7 @@ public class CuckooChessEngine extends UCIEngineBase {
         return ret;
     }
 
+    /** @inheritDoc */
     @Override
     public final synchronized void writeLineToEngine(String data) {
 //        System.out.printf("GUI -> Engine: %s\n", data);
@@ -224,6 +231,13 @@ public class CuckooChessEngine extends UCIEngineBase {
                         sPar.infinite = true;
                     }
                 }
+                if (pos == null) {
+                    try {
+                        pos = TextIO.readFEN(TextIO.startPosFEN);
+                    } catch (ChessParseError ex) {
+                        throw new RuntimeException();
+                    }
+                }
                 if (ponder) {
                     engine.startPonder(pos, moves, sPar);
                 } else {

DroidFish/src/org/petero/droidfish/gamelogic/DroidChessController.java

@@ -157,6 +157,11 @@ public class DroidChessController {
         }
     }
 
+    /** Return current engine identifier. */
+    public final synchronized String getEngine() {
+        return engine;
+    }
+
     /** Notify controller that preferences has changed. */
     public final synchronized void prefsChanged() {
         updateBookHints();
@@ -649,6 +654,8 @@ public class DroidChessController {
                     tmpPos.makeMove(ponderMove, ui);
                 }
                 for (Move m : pv.pv) {
+                    if (m == null)
+                        break;
                     String moveStr = TextIO.moveToString(tmpPos, m, false);
                     buf.append(String.format(" %s", moveStr));
                     tmpPos.makeMove(m, ui);
@@ -701,6 +708,15 @@ public class DroidChessController {
                 }
             });
         }
+        
+        @Override
+        public void reportEngineError(final String errMsg) {
+            gui.runOnUIThread(new Runnable() {
+                public void run() {
+                    gui.reportEngineError(errMsg);
+                }
+            });
+        }
     }
 
     /** Discard current search. Return true if GUI update needed. */

DroidFish/src/org/petero/droidfish/gamelogic/SearchListener.java

@@ -90,4 +90,7 @@ public interface SearchListener {
 
     /** Report engine name. */
     public void notifyEngineName(String engineName);
+
+    /** Report engine error. */
+    public void reportEngineError(String errMsg);
 }