Patch #4736 for Chessbox from Miguel A. Arévalo - Added support for user interaction while thinking, you can force move now with PLAY and quit with OFF (iRiver example). Yield only on Search as any Evaluate will be preceded by a Search. Plus some minor code policing from me to remove tabs in both the patch and the original code

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8896 a1c6a512-1295-4272-9138-f99709370657

3 files changed, 350 insertions, 317 deletions

diff --git a/apps/plugins/chessbox/chessbox.c b/apps/plugins/chessbox/chessbox.c
index 161de45e90..2e863b957b 100644
--- a/apps/plugins/chessbox/chessbox.c
+++ b/apps/plugins/chessbox/chessbox.c
@@ -26,9 +26,9 @@
 
 /* type definitions */
 struct cb_command {
-	int type;
-	char mv_s[5];
-	unsigned short mv;
+    int type;
+    char mv_s[5];
+    unsigned short mv;
 };
 
 /* External bitmaps */
@@ -131,7 +131,7 @@ PLUGIN_HEADER
 #define TILE_WIDTH  8
 #define TILE_HEIGHT 8
 #else
-  #error BEJEWELED: Unsupported LCD
+    #error CHESSBOX: Unsupported LCD
 #endif
 
 /* Calculate Offsets */
@@ -139,11 +139,15 @@ PLUGIN_HEADER
 #define YOFS ((LCD_HEIGHT-8*TILE_HEIGHT)/2)
 
 /* commands enum */
-#define COMMAND_MOVE	1
-#define COMMAND_PLAY	2
-#define COMMAND_LEVEL	3
-/*#define COMMAND_RESTART	4*/
-#define COMMAND_QUIT	5
+#define COMMAND_NOP        0
+#define COMMAND_MOVE       1
+#define COMMAND_PLAY       2
+#define COMMAND_LEVEL      3
+/*#define COMMAND_RESTART    4*/
+#define COMMAND_QUIT       5
+
+/* "While thinking" command */
+int wt_command = COMMAND_NOP;
 
 /* GCC wants this to be present for some targets */
 void* memcpy(void* dst, const void* src, size_t size)
@@ -153,278 +157,298 @@ void* memcpy(void* dst, const void* src, size_t size)
 
 /* ---- Get the board column and row (e2 f.e.) for a physical x y ---- */
 void xy2cr ( short x, short y, short *c, short *r ) {
-	if (computer == black ) {
-		*c = x ;
-		*r = y ;
-	} else {
-		*c = 7 - x ;
-		*r = 7 - y ;
-	}
+    if (computer == black ) {
+        *c = x ;
+        *r = y ;
+    } else {
+        *c = 7 - x ;
+        *r = 7 - y ;
+    }
 }
 
 /* ---- get physical x y for a board column and row (e2 f.e.) ---- */
 void cr2xy ( short c, short r, short *x, short *y ) {
-	if ( computer == black ) {
-		*x = c ;
-		*y = r ;
-	} else {
-		*x = 7 - c ;
-		*y = 7 - r ;
-	}
+    if ( computer == black ) {
+        *x = c ;
+        *y = r ;
+    } else {
+        *x = 7 - c ;
+        *y = 7 - r ;
+    }
 }
 
 /* ---- Draw a complete board ---- */
 static void cb_drawboard (void) {
     short r , c , x , y ;
-	short l , piece , p_color ;
-	int b_color=1;
-	
-	rb->lcd_clear_display();
+    short l , piece , p_color ;
+    int b_color=1;
+    
+    rb->lcd_clear_display();
 
-	for (r = 0; r < 8; r++) {
+    for (r = 0; r < 8; r++) {
         for (c = 0; c < 8; c++) {
             l = locn[r][c];
             piece   = board[l] ;
-			p_color = color[l] ;
-			cr2xy ( c , r , &x , &y );
-			if ( piece == no_piece ) {
-				rb->lcd_bitmap_part ( chessbox_pieces , 0 ,
-									  TILE_HEIGHT * b_color ,
-									  TILE_WIDTH ,
-									  XOFS + x*TILE_WIDTH ,
-				                      YOFS + ( 7 - y )*TILE_HEIGHT ,
-				                      TILE_WIDTH ,
-				                      TILE_HEIGHT );
-			} else {
-			    rb->lcd_bitmap_part ( chessbox_pieces ,
-									  0 ,
-					                  2 * TILE_HEIGHT +
-				                          4 * TILE_HEIGHT * ( piece - 1 ) +
-				                          2 * TILE_HEIGHT * p_color +
-				                          TILE_HEIGHT * b_color ,
-									  TILE_WIDTH ,
-									  XOFS + x*TILE_WIDTH ,
-				                      YOFS + (7 - y)*TILE_HEIGHT ,
-				                      TILE_WIDTH ,
-				                      TILE_HEIGHT );
-			}
-			b_color = (b_color == 1) ? 0 : 1 ;
+            p_color = color[l] ;
+            cr2xy ( c , r , &x , &y );
+            if ( piece == no_piece ) {
+                rb->lcd_bitmap_part ( chessbox_pieces , 0 ,
+                                      TILE_HEIGHT * b_color ,
+                                      TILE_WIDTH ,
+                                      XOFS + x*TILE_WIDTH ,
+                                      YOFS + ( 7 - y )*TILE_HEIGHT ,
+                                      TILE_WIDTH ,
+                                      TILE_HEIGHT );
+            } else {
+                rb->lcd_bitmap_part ( chessbox_pieces ,
+                                      0 ,
+                                      2 * TILE_HEIGHT +
+                                          4 * TILE_HEIGHT * ( piece - 1 ) +
+                                          2 * TILE_HEIGHT * p_color +
+                                          TILE_HEIGHT * b_color ,
+                                      TILE_WIDTH ,
+                                      XOFS + x*TILE_WIDTH ,
+                                      YOFS + (7 - y)*TILE_HEIGHT ,
+                                      TILE_WIDTH ,
+                                      TILE_HEIGHT );
+            }
+            b_color = (b_color == 1) ? 0 : 1 ;
         }
-		b_color = (b_color == 1) ? 0 : 1 ;
+        b_color = (b_color == 1) ? 0 : 1 ;
+    }
+    
+    /* draw board limits */
+    if ( LCD_WIDTH > TILE_WIDTH*8 ) {
+        rb->lcd_set_drawmode ( DRMODE_FG );
+        rb->lcd_drawline ( XOFS - 1 , YOFS ,
+                           XOFS - 1 , YOFS + TILE_HEIGHT*8 );
+        rb->lcd_drawline ( XOFS + 8*TILE_WIDTH , YOFS ,
+                           XOFS + 8*TILE_WIDTH , YOFS + TILE_HEIGHT*8 );
+    }
+    if ( LCD_HEIGHT > TILE_HEIGHT*8 ) {
+        rb->lcd_set_drawmode ( DRMODE_FG );
+        rb->lcd_drawline ( XOFS , YOFS - 1 ,
+                           XOFS + TILE_WIDTH*8 , YOFS - 1 );
+        rb->lcd_drawline ( XOFS , YOFS + TILE_HEIGHT*8  ,
+                           XOFS + 8*TILE_WIDTH , YOFS + TILE_HEIGHT*8 );
     }
-	
-	/* draw board limits */
-	if ( LCD_WIDTH > TILE_WIDTH*8 ) {
-		rb->lcd_set_drawmode ( DRMODE_FG );
-		rb->lcd_drawline ( XOFS - 1 , YOFS ,
-		                   XOFS - 1 , YOFS + TILE_HEIGHT*8 );
-		rb->lcd_drawline ( XOFS + 8*TILE_WIDTH , YOFS ,
-		                   XOFS + 8*TILE_WIDTH , YOFS + TILE_HEIGHT*8 );
-	}
-	if ( LCD_HEIGHT > TILE_HEIGHT*8 ) {
-		rb->lcd_set_drawmode ( DRMODE_FG );
-		rb->lcd_drawline ( XOFS , YOFS - 1 ,
-		                   XOFS + TILE_WIDTH*8 , YOFS - 1 );
-		rb->lcd_drawline ( XOFS , YOFS + TILE_HEIGHT*8  ,
-		                   XOFS + 8*TILE_WIDTH , YOFS + TILE_HEIGHT*8 );
-	}
-	rb->lcd_update();
+    rb->lcd_update();
 }
 
 /* ---- Switch mark on board ---- */
 void cb_switch ( short x , short y ) {
-	rb->lcd_set_drawmode ( DRMODE_COMPLEMENT );
-	rb->lcd_drawrect ( XOFS + x*TILE_WIDTH + 1 ,
-	                   YOFS + ( 7 - y )*TILE_HEIGHT +1 ,
-	                   TILE_WIDTH-2 , TILE_HEIGHT-2 );
-	rb->lcd_update();
+    rb->lcd_set_drawmode ( DRMODE_COMPLEMENT );
+    rb->lcd_drawrect ( XOFS + x*TILE_WIDTH + 1 ,
+                       YOFS + ( 7 - y )*TILE_HEIGHT +1 ,
+                       TILE_WIDTH-2 , TILE_HEIGHT-2 );
+    rb->lcd_update();
+}
+
+/* ---- callback for capturing interaction while thinking ---- */
+void cb_wt_callback ( void ) {
+    int button = BUTTON_NONE;
+    
+    wt_command = COMMAND_NOP;
+    button = rb->button_get(false);
+    switch (button) {
+        case CB_QUIT:
+            wt_command = COMMAND_QUIT;
+            timeout = true;
+            break;
+        case CB_PLAY:
+            wt_command = COMMAND_PLAY;
+            timeout = true;
+            break;
+    }
 }
 
 /* ---- increase playing level ---- */
 void cb_levelup ( void ) {
-	Level ++;
-	if ( Level == 8 ) Level = 1;
-	switch (Level) {
-    	case 1 :
-			TCmoves = 60;
-			TCminutes = 5;
-			rb->splash ( 50 , true , "Level 1: 60 moves / 5 min" );
-			break;
-    	case 2 :
-			TCmoves = 60;
-			TCminutes = 15;
-			rb->splash ( 50 , true , "Level 2: 60 moves / 15 min" );
-			break;
-    	case 3 :
-			TCmoves = 60;
-			TCminutes = 30;
-			rb->splash ( 50 , true , "Level 3: 60 moves / 30 min" );
-			break;
-    	case 4 :
-			TCmoves = 40;
-			TCminutes = 30;
-			rb->splash ( 50 , true , "Level 4: 40 moves / 30 min" );
-			break;
-    	case 5 :
-			TCmoves = 40;
-			TCminutes = 60;
-			rb->splash ( 50 , true , "Level 5: 40 moves / 60 min" );
-			break;
-    	case 6 :
-			TCmoves = 40;
-			TCminutes = 120;
-			rb->splash ( 50 , true , "Level 6: 40 moves / 120 min" );
-			break;
-    	case 7 :
-			TCmoves = 40;
-			TCminutes = 240;
-			rb->splash ( 50 , true , "Level 7: 40 moves / 240 min" );
-			break;
-    	case 8 :
-			TCmoves = 1;
-			TCminutes = 15;
-			rb->splash ( 50 , true , "Level 8: 1 move / 15 min" );
-			break;
-      	case 9 :
-			TCmoves = 1;
-			TCminutes = 60;
-			rb->splash ( 50 , true , "Level 9: 1 move / 60 min" );
-			break;
-      	case 10 :
-			TCmoves = 1;
-			TCminutes = 600;
-			rb->splash ( 50 , true , "Level 10: 1 move / 600 min" );
-			break;
-	}
+    Level ++;
+    if ( Level == 8 ) Level = 1;
+    switch (Level) {
+        case 1 :
+            TCmoves = 60;
+            TCminutes = 5;
+            rb->splash ( 50 , true , "Level 1: 60 moves / 5 min" );
+            break;
+        case 2 :
+            TCmoves = 60;
+            TCminutes = 15;
+            rb->splash ( 50 , true , "Level 2: 60 moves / 15 min" );
+            break;
+        case 3 :
+            TCmoves = 60;
+            TCminutes = 30;
+            rb->splash ( 50 , true , "Level 3: 60 moves / 30 min" );
+            break;
+        case 4 :
+            TCmoves = 40;
+            TCminutes = 30;
+            rb->splash ( 50 , true , "Level 4: 40 moves / 30 min" );
+            break;
+        case 5 :
+            TCmoves = 40;
+            TCminutes = 60;
+            rb->splash ( 50 , true , "Level 5: 40 moves / 60 min" );
+            break;
+        case 6 :
+            TCmoves = 40;
+            TCminutes = 120;
+            rb->splash ( 50 , true , "Level 6: 40 moves / 120 min" );
+            break;
+        case 7 :
+            TCmoves = 40;
+            TCminutes = 240;
+            rb->splash ( 50 , true , "Level 7: 40 moves / 240 min" );
+            break;
+        case 8 :
+            TCmoves = 1;
+            TCminutes = 15;
+            rb->splash ( 50 , true , "Level 8: 1 move / 15 min" );
+            break;
+          case 9 :
+            TCmoves = 1;
+            TCminutes = 60;
+            rb->splash ( 50 , true , "Level 9: 1 move / 60 min" );
+            break;
+          case 10 :
+            TCmoves = 1;
+            TCminutes = 600;
+            rb->splash ( 50 , true , "Level 10: 1 move / 600 min" );
+            break;
+    }
     TCflag = (TCmoves > 1);
-  	SetTimeControl();
+      SetTimeControl();
 };
 
 /* ---- main user loop ---- */
 struct cb_command cb_getcommand (void) {
-	static short x = 4 , y = 4 ;
-	short c , r , l;
-	int button, lastbutton = BUTTON_NONE;
-	int marked = false , from_marked = false ;
-	short marked_x = 0 , marked_y = 0 ;
-	struct cb_command result = { 0, {0,0,0,0,0}, 0 };
-	
-	cb_switch ( x , y );
-	/* main loop */
-	while ( true ) {
-		button = rb->button_get(true);
-		switch (button) {
-			case CB_QUIT:
-				result.type = COMMAND_QUIT;
-				return result;
-/*			case CB_RESTART:
-				result.type = COMMAND_RESTART;
-				return result;*/
-			case CB_LEVEL:
-				result.type = COMMAND_LEVEL;
-				return result;
-			case CB_PLAY:
+    static short x = 4 , y = 4 ;
+    short c , r , l;
+    int button, lastbutton = BUTTON_NONE;
+    int marked = false , from_marked = false ;
+    short marked_x = 0 , marked_y = 0 ;
+    struct cb_command result = { 0, {0,0,0,0,0}, 0 };
+    
+    cb_switch ( x , y );
+    /* main loop */
+    while ( true ) {
+        button = rb->button_get(true);
+        switch (button) {
+            case CB_QUIT:
+                result.type = COMMAND_QUIT;
+                return result;
+#if 0
+            case CB_RESTART:
+                result.type = COMMAND_RESTART;
+                return result;
+#endif
+            case CB_LEVEL:
+                result.type = COMMAND_LEVEL;
+                return result;
+            case CB_PLAY:
 #ifdef CB_PLAY_PRE
                 if (lastbutton != CB_PLAY_PRE)
                     break;
 #endif
-				result.type = COMMAND_PLAY;
-				return result;
-			case CB_UP:
-				if ( !from_marked ) cb_switch ( x , y );
-				y++;
-				if ( y == 8 ) {
-					y = 0;
-					x--;
-					if ( x < 0 ) x = 7;
-				}
-				if ( marked && ( marked_x == x ) && ( marked_y == y ) ) {
-					from_marked = true ;
-				} else {
-					from_marked = false ;
-					cb_switch ( x , y );
-				}
-				break;
-			case CB_DOWN:
-				if ( !from_marked ) cb_switch ( x , y );
-				y--;
-				if ( y < 0 ) {
-					y = 7;
-					x++;
-					if ( x == 8 ) x = 0;
-				}
-				if ( marked && ( marked_x == x ) && ( marked_y == y ) ) {
-					from_marked = true ;
-				} else {
-					from_marked = false ;
-					cb_switch ( x , y );
-				}
-				break;
-			case CB_LEFT:
-				if ( !from_marked ) cb_switch ( x , y );
-				x--;
-				if ( x < 0 ) {
-					x = 7;
-					y++;
-					if ( y == 8 ) y = 0;
-				}
-				if ( marked && ( marked_x == x ) && ( marked_y == y ) ) {
-					from_marked = true ;
-				} else {
-					from_marked = false ;
-					cb_switch ( x , y );
-				}
-				break;
-			case CB_RIGHT:
-				if ( !from_marked ) cb_switch ( x , y );
-				x++;
-				if ( x == 8 ) {
-					x = 0;
-					y--;
-					if ( y < 0 ) y = 7;
-				}
-				if ( marked && ( marked_x == x ) && ( marked_y == y ) ) {
-					from_marked = true ;
-				} else {
-					from_marked = false ;
-					cb_switch ( x , y );
-				}
-				break;
-			case CB_SELECT:
+                result.type = COMMAND_PLAY;
+                return result;
+            case CB_UP:
+                if ( !from_marked ) cb_switch ( x , y );
+                y++;
+                if ( y == 8 ) {
+                    y = 0;
+                    x--;
+                    if ( x < 0 ) x = 7;
+                }
+                if ( marked && ( marked_x == x ) && ( marked_y == y ) ) {
+                    from_marked = true ;
+                } else {
+                    from_marked = false ;
+                    cb_switch ( x , y );
+                }
+                break;
+            case CB_DOWN:
+                if ( !from_marked ) cb_switch ( x , y );
+                y--;
+                if ( y < 0 ) {
+                    y = 7;
+                    x++;
+                    if ( x == 8 ) x = 0;
+                }
+                if ( marked && ( marked_x == x ) && ( marked_y == y ) ) {
+                    from_marked = true ;
+                } else {
+                    from_marked = false ;
+                    cb_switch ( x , y );
+                }
+                break;
+            case CB_LEFT:
+                if ( !from_marked ) cb_switch ( x , y );
+                x--;
+                if ( x < 0 ) {
+                    x = 7;
+                    y++;
+                    if ( y == 8 ) y = 0;
+                }
+                if ( marked && ( marked_x == x ) && ( marked_y == y ) ) {
+                    from_marked = true ;
+                } else {
+                    from_marked = false ;
+                    cb_switch ( x , y );
+                }
+                break;
+            case CB_RIGHT:
+                if ( !from_marked ) cb_switch ( x , y );
+                x++;
+                if ( x == 8 ) {
+                    x = 0;
+                    y--;
+                    if ( y < 0 ) y = 7;
+                }
+                if ( marked && ( marked_x == x ) && ( marked_y == y ) ) {
+                    from_marked = true ;
+                } else {
+                    from_marked = false ;
+                    cb_switch ( x , y );
+                }
+                break;
+            case CB_SELECT:
 #ifdef CB_SELECT_PRE
                 if (lastbutton != CB_SELECT_PRE)
                     break;
 #endif
-				if ( !marked ) {
-					xy2cr ( x , y , &c , &r );
+                if ( !marked ) {
+                    xy2cr ( x , y , &c , &r );
                     l = locn[r][c];
                     if ( ( color[l]!=computer ) && ( board[l]!=no_piece ) ) {
-					    marked = true;
-					    from_marked = true ;
-					    marked_x = x;
-					    marked_y = y;
-					}
-				} else {
-					if ( ( marked_x == x ) && ( marked_y == y ) ) {
-						marked = false;
-						from_marked = false;
-					} else {
-						xy2cr ( marked_x , marked_y , &c , &r );
-						result.mv_s[0] = 'a' + c;
-						result.mv_s[1] = '1' + r;
-						xy2cr ( x , y , &c , &r );
-						result.mv_s[2] = 'a' + c;
-						result.mv_s[3] = '1' + r;
-						result.mv_s[4] = '\00';
-						result.type = COMMAND_MOVE;
-						return result;
-					}
-				}
-				break;
-		}
-		if (button != BUTTON_NONE)
+                        marked = true;
+                        from_marked = true ;
+                        marked_x = x;
+                        marked_y = y;
+                    }
+                } else {
+                    if ( ( marked_x == x ) && ( marked_y == y ) ) {
+                        marked = false;
+                        from_marked = false;
+                    } else {
+                        xy2cr ( marked_x , marked_y , &c , &r );
+                        result.mv_s[0] = 'a' + c;
+                        result.mv_s[1] = '1' + r;
+                        xy2cr ( x , y , &c , &r );
+                        result.mv_s[2] = 'a' + c;
+                        result.mv_s[3] = '1' + r;
+                        result.mv_s[4] = '\00';
+                        result.type = COMMAND_MOVE;
+                        return result;
+                    }
+                }
+                break;
+        }
+        if (button != BUTTON_NONE)
             lastbutton = button;
-	}
+    }
 
 }
 
@@ -432,77 +456,87 @@ struct cb_command cb_getcommand (void) {
 * plugin entry point.
 ******************************************************************************/
 enum plugin_status plugin_start(struct plugin_api* api, void* parameter) {
-	struct cb_command command;
-	/* init status */
-	bool exit = false;
-	
+    struct cb_command command;
+    /* init status */
+    bool exit = false;
+    
     /* plugin init */
     (void)parameter;
     rb = api;
     /* end of plugin init */
 
-	/* load opening book, soon */
-	
-	/* init board */
-	GNUChess_Initialize();
-	
-	/* draw the board */
-	/* I don't like configscreens, start game inmediatly */
-	cb_drawboard();
-	
-	while (!exit) {
-		if ( mate ) {
-			rb->splash ( 500 , true , "Checkmate!" );
-			rb->button_get(true);
-			GNUChess_Initialize();
-			cb_drawboard();
-		}
-		command = cb_getcommand ();
-		switch (command.type) {
-			case COMMAND_MOVE:
-				if ( ! VerifyMove ( command.mv_s , 0 , &command.mv ) ) {
-					rb->splash ( 50 , true , "Illegal move!" );
-					cb_drawboard();
-				} else {
-					cb_drawboard();
-					rb->splash ( 0 , true , "Thinking..." );
+    /* load opening book, soon */
+    
+    /* init board */
+    GNUChess_Initialize();
+    
+    /* draw the board */
+    /* I don't like configscreens, start game inmediatly */
+    cb_drawboard();
+    
+    while (!exit) {
+        if ( mate ) {
+            rb->splash ( 500 , true , "Checkmate!" );
+            rb->button_get(true);
+            GNUChess_Initialize();
+            cb_drawboard();
+        }
+        command = cb_getcommand ();
+        switch (command.type) {
+            case COMMAND_MOVE:
+                if ( ! VerifyMove ( command.mv_s , 0 , &command.mv ) ) {
+                    rb->splash ( 50 , true , "Illegal move!" );
+                    cb_drawboard();
+                } else {
+                    cb_drawboard();
+                    rb->splash ( 0 , true , "Thinking..." );
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
-					rb->cpu_boost ( true );
+                    rb->cpu_boost ( true );
 #endif
-					SelectMove ( computer , 0 );
+                    SelectMove ( computer , 0 , cb_wt_callback );
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
-					rb->cpu_boost ( false );
+                    rb->cpu_boost ( false );
 #endif
-					cb_drawboard();
-				}
-				break;
-/*			case COMMAND_RESTART:
-				GNUChess_Initialize();
-				cb_drawboard();
-				break;*/
-			case COMMAND_PLAY:
-				opponent = !opponent; computer = !computer;
-				rb->splash ( 0 , true , "Thinking..." );
+                    if ( wt_command == COMMAND_QUIT ) {
+                        exit = true;
+                        break;
+                    }
+                    cb_drawboard();
+                }
+                break;
+#if 0
+            case COMMAND_RESTART:
+                GNUChess_Initialize();
+                cb_drawboard();
+                break;
+#endif
+            case COMMAND_PLAY:
+                opponent = !opponent; computer = !computer;
+                rb->splash ( 0 , true , "Thinking..." );
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
-				rb->cpu_boost ( true );
+                rb->cpu_boost ( true );
 #endif
-				SelectMove ( computer , 0 );
+                SelectMove ( computer , 0 , cb_wt_callback );
 #ifdef HAVE_ADJUSTABLE_CPU_FREQ
-				rb->cpu_boost ( false );
+                rb->cpu_boost ( false );
 #endif
-				cb_drawboard();
-				break;
-			case COMMAND_LEVEL:
-				cb_levelup ( );
-				cb_drawboard();
-				break;
-			case COMMAND_QUIT:
-				/*cb_saveposition();*/
-				exit = true;
-				break;
-		}
-	}
-	
+                if ( wt_command == COMMAND_QUIT ) {
+                    exit = true;
+                    break;
+                }
+                cb_drawboard();
+                break;
+            case COMMAND_LEVEL:
+                cb_levelup ( );
+                cb_drawboard();
+                break;
+            case COMMAND_QUIT:
+                /*cb_saveposition();*/
+                exit = true;
+                break;
+        }
+    }
+    
     rb->lcd_setfont(FONT_UI);
     return PLUGIN_OK;
 }
diff --git a/apps/plugins/chessbox/gnuchess.c b/apps/plugins/chessbox/gnuchess.c
index 879c083ce7..9bd07c8eee 100644
--- a/apps/plugins/chessbox/gnuchess.c
+++ b/apps/plugins/chessbox/gnuchess.c
@@ -279,7 +279,8 @@ void CopyBoard( short a[64] , short b[64] );
 void OpeningBook ( void );
 int  search ( short side, short ply, short depth,
               short alpha, short beta,
-			  unsigned short bstline[], short *rpt );
+			  unsigned short bstline[], short *rpt,
+              void (*callback)(void) );
 int  evaluate ( short side, short xside, short ply, short depth,
                 short alpha, short beta );
 int  ProbeTTable ( short side, short depth,
@@ -333,9 +334,6 @@ short pscore[3];
   xside = otherside[side];
   pscore[white] = pscore[black] = 0;
 
-  /* ok, I will yield here for lower levels */
-  rb->yield();
-
   for (c1 = white; c1 <= black; c1++)
     {
       c2 = otherside[c1];
@@ -1018,8 +1016,7 @@ register int sq;
 /* ............    MOVE GENERATION & SEARCH ROUTINES    .............. */
 
 
-int SelectMove(side,iop)
-short side,iop;
+int SelectMove( short side, short iop , void (*callback)(void))
 
 /*
    Select a move by calling function search() at progressively deeper 
@@ -1078,21 +1075,21 @@ static short i,alpha,beta,score,tempb,tempc,tempsf,tempst,xside,rpt;
     {
       Sdepth++;
       /*ShowDepth(' ');*/
-      score = search(side,1,Sdepth,alpha,beta,PrVar,&rpt);
+      score = search(side,1,Sdepth,alpha,beta,PrVar,&rpt,callback);
       for (i = 1; i <= Sdepth; i++) killr0[i] = PrVar[i];
       if (score < alpha && !timeout)
         {
           /*ShowDepth('-');*/
           ExtraTime = 10*ResponseTime;
           ZeroTTable();
-          score = search(side,1,Sdepth,-9000,beta,PrVar,&rpt);
+          score = search(side,1,Sdepth,-9000,beta,PrVar,&rpt,callback);
         }
       if (score > beta && !timeout && !(root->flags & exact))
         {
           /*ShowDepth('+');*/
           ExtraTime = 0;
           ZeroTTable();
-          score = search(side,1,Sdepth,alpha,9000,PrVar,&rpt);
+          score = search(side,1,Sdepth,alpha,9000,PrVar,&rpt,callback);
         }
       score = root->score;
       if (!timeout)
@@ -1209,9 +1206,9 @@ struct BookEntry *p;
     }\
 }
 
-int search(side,ply,depth,alpha,beta,bstline,rpt)
-short side,ply,depth,alpha,beta,*rpt;
-unsigned short bstline[];
+int search( short side, short ply, short depth,
+            short alpha, short beta, unsigned short bstline[], short *rpt,
+            void (*callback)(void) )
 
 /*
    Perform an alpha-beta search to determine the score for the current 
@@ -1238,8 +1235,10 @@ short xside,pbst,d,e,cf,score,rcnt;
 unsigned short mv,nxtline[maxdepth];
 struct leaf *node,tmp;
 
-  /* ok, I will yield here for higher levels */
+  /* this is the only place we need to yield */
   rb->yield();
+  /* and check for user interaction */
+  callback();
 
   NodeCnt++;
   xside = otherside[side];
@@ -1308,7 +1307,7 @@ struct leaf *node,tmp;
           PawnThreat[ply] = (node->flags & pwnthrt);
           Tscore[ply] = node->score;
           node->score = -search(xside,ply+1,depth-1,-beta,-alpha,
-                                nxtline,&rcnt);
+                                nxtline,&rcnt,callback);
           if (abs(node->score) > 9000) node->flags |= exact;
           else if (rcnt == 1) node->score /= 2;
           if (rcnt >= 2 || GameCnt-Game50 > 99 ||
diff --git a/apps/plugins/chessbox/gnuchess.h b/apps/plugins/chessbox/gnuchess.h
index 68ef9f9a81..e94748919a 100644
--- a/apps/plugins/chessbox/gnuchess.h
+++ b/apps/plugins/chessbox/gnuchess.h
@@ -26,6 +26,7 @@ extern short board[64];
 extern short color[64];
 extern long Level;
 extern short TCflag,TCmoves,TCminutes;
+extern short timeout;
 
 /* ---- RockBox integration ---- */
 extern struct plugin_api* rb;
@@ -33,8 +34,7 @@ extern struct plugin_api* rb;
 /* ---- The beginning of a GNUChess v2 APIfication ---- */
 void SetTimeControl(void);
 void GNUChess_Initialize(void);
-int VerifyMove(char s[],short iop,unsigned short *mv);
-int  SelectMove ( short side, short iop);
-
+int  VerifyMove(char s[],short iop,unsigned short *mv);
+int  SelectMove ( short side, short iop , void (*callback)(void) );
 
 #endif