Make sure that reversi doesn't enter an infinite loop when using 1 or 2 AIs.

+ some changes that will be needed for more advanced AIs (which aren't ready to commit yet)


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@13758 a1c6a512-1295-4272-9138-f99709370657

apps/plugins/reversi/reversi-game.c

@@ -120,24 +120,9 @@ static int reversi_count_free_cells(const reversi_board_t *game) {
  * can make a move. Note that the implementation is not correct
  * as a game may be finished even if there are free cells
  */
-bool reversi_game_is_finished(const reversi_board_t *game) {
-    return (reversi_count_free_cells(game) == 0);
-}
-
-
-/* Finds out who should place the next stone. It's the partner
- * of the last move or WHITE if the game is just started.
- *
- * Returns WHITE or BLACK.
- */
-int reversi_get_turn(const reversi_board_t *game) {
-    int moves;
-    moves = reversi_count_moves(game);
-    if (moves == 0) {
-        return WHITE;
-    } else {
-        return reversi_flipped_color(MOVE_PLAYER(game->history[moves-1]));
-    }
+bool reversi_game_is_finished(const reversi_board_t *game, int player) {
+    return (reversi_count_free_cells(game) == 0)
+           || (reversi_count_passes(game,player) == 2);
 }
 
 
@@ -165,6 +150,7 @@ static int reversi_count_player_moves(const reversi_board_t *game,
     return cnt;
 }
 
+/* Returns the number of moves available for the specified player */
 int reversi_count_player_available_moves(const reversi_board_t *game,
         const int player) {
     int cnt = 0, row, col;
@@ -176,6 +162,17 @@ int reversi_count_player_available_moves(const reversi_board_t *game,
     return cnt;
 }
 
+/* Returns the number of players who HAVE to pass (2 == game is stuck) */
+int reversi_count_passes(const reversi_board_t *game, const int player) {
+    if(reversi_count_player_available_moves(game,player)==0) {
+        if(reversi_count_player_available_moves(game,
+                    reversi_flipped_color(player))==0) {
+            return 2;
+        }
+        return 1;
+    }
+    return 0;
+}
 
 /* Returns the number of moves made by WHITE so far */
 int reversi_count_white_moves(const reversi_board_t *game) {

apps/plugins/reversi/reversi-game.h

@@ -23,11 +23,11 @@
 #include <stdbool.h>
 #include "plugin.h"
 
-#define WHITE 1       /* WHITE constant, it always plays first (as in chess) */
-#define BLACK 2       /* BLACK constant */
-#define FREE  0       /* Free place constant */
+#define WHITE  1      /* WHITE constant, it always plays first (as in chess) */
+#define BLACK -1      /* BLACK constant */
+#define FREE   0      /* Free place constant */
 
-#define BOARD_SIZE 8
+#define BOARD_SIZE  8
 #define INIT_STONES 4
 
 /* Description of a move. A move is stored as a byte in the following format:
@@ -50,7 +50,7 @@ typedef unsigned char move_t;
 /* State of a board */
 typedef struct _reversi_board_t {
     /* The current state of the game (BLACK/WHITE/FREE) */
-    char board[BOARD_SIZE][BOARD_SIZE];
+    int board[BOARD_SIZE][BOARD_SIZE];
 
     /* Game history. First move (mostly, but not necessarily, black) is stored
      * in history[0], second move (mostly, but not necessarily, white) is
@@ -64,8 +64,7 @@ typedef struct _reversi_board_t {
 
 void reversi_init_game(reversi_board_t *game);
 int reversi_flipped_color(const int color);
-bool reversi_game_is_finished(const reversi_board_t *game);
-int reversi_get_turn(const reversi_board_t *game);
+bool reversi_game_is_finished(const reversi_board_t *game, int cur_player);
 int reversi_count_occupied_cells(const reversi_board_t *game,
         int *white_count, int *black_count);
 int reversi_count_moves(const reversi_board_t *game);
@@ -77,6 +76,7 @@ int reversi_is_valid_move(const reversi_board_t *game,
         const int row, const int col, const int player);
 int reversi_count_player_available_moves(const reversi_board_t *game,
         const int player);
+int reversi_count_passes(const reversi_board_t *game, const int player);
 
 
 #endif

apps/plugins/reversi/reversi-gui.c

@@ -190,13 +190,13 @@ static int cur_player;
 static cursor_wrap_mode_t cursor_wrap_mode;
 
 static bool quit_plugin;
+static bool game_finished;
 
 
 /* Initialises the state of the game (starts a new game) */
 static void reversi_gui_init(void) {
     reversi_init_game(&game);
-    white_strategy = &strategy_human;
-    black_strategy = &strategy_human;
+    game_finished = false;
     cur_player = BLACK;
 
     /* Place the cursor so that WHITE can make a move */
@@ -330,9 +330,10 @@ static struct opt_items strategy_settings[] = {
     { "Human", NULL },
     { "Naive robot", NULL },
     { "Simple robot", NULL },
+    //{ "AB robot", NULL },
 };
 static const game_strategy_t * const strategy_values[] = {
-    &strategy_human, &strategy_naive, &strategy_simple };
+    &strategy_human, &strategy_naive, &strategy_simple, /*&strategy_ab*/ };
 
 
 /* Sets the strategy for the specified player. 'player' is the
@@ -354,6 +355,9 @@ static bool reversi_gui_choose_strategy(
     result = rb->set_option(prompt, &index, INT, strategy_settings, num_items, NULL);
     (*player) = strategy_values[index];
 
+    if((*player)->init_func)
+        (*player)->init_func(&game);
+
     return result;
 }
 
@@ -557,6 +561,8 @@ enum plugin_status plugin_start(struct plugin_api *api, void *parameter) {
 
     game.rb = rb;
     rb->srand(*rb->current_tick); /* Some AIs use rand() */
+    white_strategy = &strategy_human;
+    black_strategy = &strategy_human;
 
     reversi_gui_init();
     cursor_wrap_mode = WRAP_FLAT;
@@ -580,21 +586,21 @@ enum plugin_status plugin_start(struct plugin_api *api, void *parameter) {
                 break;
         }
 
-        if(cur_strategy->is_robot) {
-            /* TODO: Check move validity */
+        if(cur_strategy->is_robot && !game_finished) {
             move_t m = cur_strategy->move_func(&game, cur_player);
             reversi_make_move(&game, MOVE_ROW(m), MOVE_COL(m), cur_player);
             cur_player = reversi_flipped_color(cur_player);
             draw_screen = true;
             /* TODO: Add some delay to prevent it from being too fast ? */
             /* TODO: Don't duplicate end of game check */
-            if (reversi_game_is_finished(&game)) {
+            if (reversi_game_is_finished(&game, cur_player)) {
                 reversi_count_occupied_cells(&game, &w_cnt, &b_cnt);
                 rb->snprintf(msg_buf, sizeof(msg_buf),
                         "Game over. %s have won.",
                         (w_cnt>b_cnt?"WHITE":"BLACK"));
                 rb->splash(HZ*2, msg_buf);
                 draw_screen = true; /* Must update screen after splash */
+                game_finished = true;
             }
             continue;
         }
@@ -618,17 +624,19 @@ enum plugin_status plugin_start(struct plugin_api *api, void *parameter) {
                         && (lastbutton != REVERSI_BUTTON_MAKE_MOVE_PRE))
                     break;
 #endif
+                if (game_finished) break;
                 if (reversi_make_move(&game, cur_row, cur_col, cur_player) > 0) {
                     /* Move was made. Global changes on the board are possible */
                     draw_screen = true; /* Redraw the screen next time */
                     cur_player = reversi_flipped_color(cur_player);
-                    if (reversi_game_is_finished(&game)) {
+                    if (reversi_game_is_finished(&game, cur_player)) {
                         reversi_count_occupied_cells(&game, &w_cnt, &b_cnt);
                         rb->snprintf(msg_buf, sizeof(msg_buf),
                                 "Game over. %s have won.",
                                 (w_cnt>b_cnt?"WHITE":"BLACK"));
                         rb->splash(HZ*2, msg_buf);
                         draw_screen = true; /* Must update screen after splash */
+                        game_finished = true;
                     }
                 } else {
                     /* An attempt to make an invalid move */

apps/plugins/reversi/reversi-strategy-naive.c

@@ -26,9 +26,11 @@
 
 static move_t naive_move_func(const reversi_board_t *game, int player) {
     int num_moves = reversi_count_player_available_moves(game, player);
-    int r = game->rb->rand()%num_moves;
+    int r;
     int row = 0;
     int col = 0;
+    if(!num_moves) return MOVE_INVALID;
+    r = game->rb->rand()%num_moves;
     while(true) {
         if(reversi_is_valid_move(game, row, col, player)) {
             r--;
@@ -49,5 +51,6 @@ static move_t naive_move_func(const reversi_board_t *game, int player) {
 
 const game_strategy_t strategy_naive = {
     true,
+    NULL,
     naive_move_func
 };

apps/plugins/reversi/reversi-strategy-simple.c

@@ -33,7 +33,7 @@ static void reversi_copy_board(reversi_board_t *dst,
     dst->rb->memcpy(dst->history,src->history,
                     (BOARD_SIZE*BOARD_SIZE - INIT_STONES)*sizeof(move_t));
     for(i=0;i<BOARD_SIZE;i++) {
-        dst->rb->memcpy(dst->board[i],src->board[i],BOARD_SIZE);
+        dst->rb->memcpy(dst->board[i],src->board[i],BOARD_SIZE*sizeof(int));
     }
 }
 
@@ -113,5 +113,6 @@ static move_t simple_move_func(const reversi_board_t *game, int player) {
 
 const game_strategy_t strategy_simple = {
     true,
+    NULL,
     simple_move_func
 };

apps/plugins/reversi/reversi-strategy.c

@@ -23,5 +23,6 @@
 /* Strategy that requires interaction with the user */
 const game_strategy_t strategy_human = {
     false,
+    NULL,
     NULL
 };

apps/plugins/reversi/reversi-strategy.h

@@ -28,11 +28,13 @@
    a move has been considered or HISTORY_INVALID_ENTRY if no move
    has been considered. The board should not be modified. */
 typedef move_t (*move_func_t)(const reversi_board_t *game, int color);
+typedef void   (*init_func_t)(const reversi_board_t *game);
 
 /* A playing party/strategy */
 typedef struct _game_strategy_t {
     const bool is_robot;     /* Is the player a robot or does it require user input? */
-    move_func_t move_func;   /* Function for advicing a move */
+    init_func_t init_func;   /* Initialise strategy */
+    move_func_t move_func;   /* Make a move */
 } game_strategy_t;
 
 
@@ -40,5 +42,9 @@ typedef struct _game_strategy_t {
 extern const game_strategy_t strategy_human;
 extern const game_strategy_t strategy_naive;
 extern const game_strategy_t strategy_simple;
+//extern const game_strategy_t strategy_ab;
+
+#define CHAOSNOISE 0.05 /**< Changerate of heuristic-value */
+#define CHAOSPROB  0.1  /**< Probability of change of the heuristic-value */
 
 #endif