예제 #1
0
파일: cache.c 프로젝트: Fierralin/gnugo
void
sgf_trace_semeai(const char *func, int str1, int str2, int move, 
		 int result1, int result2, const char *message)
{
  char buf[100];

  sprintf(buf, "%s %c%d %c%d: ", func,
	  J(str1) + 'A' + (J(str1) >= 8), board_size - I(str1),
	  J(str2) + 'A' + (J(str2) >= 8), board_size - I(str2));
  
  if (ON_BOARD(move))
    sprintf(buf + strlen(buf), "%s %s %c%d",
	    result_to_string(result1), result_to_string(result2),
	    J(move) + 'A' + (J(move) >= 8), board_size - I(move));
  else if (is_pass(move))
    sprintf(buf + strlen(buf), "%s %s PASS",
	    result_to_string(result1), result_to_string(result2));
  else
    sprintf(buf + strlen(buf), "%s %s [%d]",
	    result_to_string(result1), result_to_string(result2),
	    move);

  if (message)
    sprintf(buf + strlen(buf), " (%s)", message);
  
  sgftreeAddComment(sgf_dumptree, buf);
}
예제 #2
0
void
clear_unconditionally_meaningless_moves()
{
  int pos;
  
  for (pos = BOARDMIN; pos < BOARDMAX; pos++)
    if (ON_BOARD(pos)) {
      meaningless_black_moves[pos] = -1;
      meaningless_white_moves[pos] = -1;
    }
}
예제 #3
0
static int
goal_dist(int pos, signed char goal[BOARDMAX])
{
  int dist = 10000;
  int ii;

  for (ii = BOARDMIN; ii < BOARDMAX; ii++)
    if (ON_BOARD(ii) && goal[ii])
      dist = gg_min(dist, square_dist(ii, pos));

  return dist;
}
예제 #4
0
파일: semeai.c 프로젝트: epichub/neatzsche
/* neighbor_of_dragon(pos, origin) returns true if the vertex at (pos) is a
 * neighbor of the dragon with origin at (origin).
 */
static int 
neighbor_of_dragon(int pos, int origin)
{
  int k;
  if (pos == NO_MOVE)
    return 0;

  for (k = 0; k < 4; k++)
    if (ON_BOARD(pos + delta[k]) && dragon[pos + delta[k]].origin == origin)
      return 1;

  return 0;
}
예제 #5
0
파일: hash.c 프로젝트: epichub/neatzsche
/* Compute hash value to identify the goal area.
 *
 * FIXME: It would be cleaner to have a separate zobrist array for the
 *        goal and xor the values in goal as usual.
 */
Hash_data
goal_to_hashvalue(const char *goal)
{
  int i, pos;
  Hash_data return_value;
  
  for (i = 0; i < NUM_HASHVALUES; i++)
    return_value.hashval[i] = 0;
  
  for (pos = BOARDMIN; pos < BOARDMAX; pos++)
    if (ON_BOARD(pos) && goal[pos])
      for (i = 0; i < NUM_HASHVALUES; i++) 
	return_value.hashval[i] += (white_hash[pos].hashval[i]
				    + black_hash[pos].hashval[i]);
  
  return return_value;
}
/* Returns 1 if the stored board is compatible with the current board,
 * 0 otherwise.
 */
static int
verify_stored_board(char p[BOARDMAX])
{
  int pos;
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!ON_BOARD(pos))
      continue;
    else if (p[pos] == GRAY)
      continue;
    else if ((p[pos] & 3) != board[pos])
      return 0;
    else if (!(p[pos] & HIGH_LIBERTY_BIT))
      continue;
    else if (countlib(pos) <= 4)
      return 0;
  }
  
  return 1;
}
void
decide_combination(int color)
{
  int attack_move;
  char defense_moves[BOARDMAX];
  SGFTree tree;
  int first = 1;
  int pos;

  /* Prepare pattern matcher and reading code. */
  reset_engine();

  silent_examine_position(color, EXAMINE_ALL);

  if (*outfilename)
    sgffile_begindump(&tree);
  count_variations = 1;

  if (atari_atari(color, &attack_move, defense_moves, verbose)) {
    gprintf("Combination attack for %C at %1m, defense at ", color,
	    attack_move);
    for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
      if (ON_BOARD(pos) && defense_moves[pos]) {
	if (first)
	  first = 0;
	else
	  gprintf(", ");
	gprintf("%1m", pos);
      }
    }
    gprintf("\n");
  }
  else
    gprintf("No Combination attack for %C\n", color);
  
  sgffile_enddump(outfilename);
  count_variations = 0;
}
/* Look for a valid read result in the persistent cache.
 * Return 1 if found, 0 otherwise.
 */
int
search_persistent_reading_cache(int routine, int str, int *result, int *move)
{
  int k;
  struct reading_cache *entry;

  k = find_persistent_reading_cache_entry(routine, str);
  if (k == -1)
    return 0;

  /* Match found. Increase score and fill in the answer. */
  entry = &(persistent_reading_cache[k]);
  entry->score += entry->nodes;
  if (result)
    *result = entry->result;
  if (move)
    *move = entry->move;
  ASSERT1(entry->result == 0
	  || entry->move == NO_MOVE
	  || ON_BOARD(entry->move),
	  entry->move);
  
  if ((debug & DEBUG_READING_PERFORMANCE)
      && entry->nodes >= MIN_READING_NODES_TO_REPORT) {
    if (entry->result != 0)
      gprintf("%o%s %1m = %d %1m, cached (%d nodes) ",
	      routine == ATTACK ? "attack" : "defend",
	      str, entry->result, entry->move, entry->nodes);
    else 
      gprintf("%o%s %1m = %d, cached (%d nodes) ",
	      routine == ATTACK ? "attack" : "defend",
	      str, entry->result, entry->nodes);
    dump_stack();
  }
  
  return 1;
}
void
decide_position(int color)
{
  int pos;
  int move = NO_MOVE;
  int acode = 0, dcode = 0;
  int kworm;
  static const char *snames[] = {"dead", "alive", "critical", "unknown"};
  SGFTree tree;

  /* Prepare pattern matcher and reading code. */
  reset_engine();

  silent_examine_position(color, EXAMINE_DRAGONS_WITHOUT_OWL);

  /* We want to see the reading performed, not just a result picked
   * from the cache. Thus we clear the cache here. */
  reading_cache_clear();

  if (*outfilename)
    sgffile_begindump(&tree);

  count_variations = 1;

  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!ON_BOARD(pos)
	|| dragon[pos].origin != pos
	|| board[pos] == EMPTY
	|| DRAGON2(pos).escape_route >= 6)
      continue;

    gprintf("\nanalyzing %1m\n", pos);
    gprintf("status=%s, escape=%d\n", 
	    snames[dragon[pos].crude_status], DRAGON2(pos).escape_route);
    acode = owl_attack(pos, &move, NULL, &kworm);
    if (acode) {
      if (acode == WIN) {
	if (move == NO_MOVE)
	  gprintf("%1m is dead as it stands\n", pos);
	else
	  gprintf("%1m can be attacked at %1m (%d variations)\n", 
		  pos, move, count_variations);
      }
      else if (acode == KO_A)
	gprintf("%1m can be attacked with ko (good) at %1m (%d variations)\n", 
		pos, move, count_variations);
      else if (acode == KO_B)
	gprintf("%1m can be attacked with ko (bad) at %1m (%d variations)\n", 
		pos, move, count_variations);
      else if (acode == GAIN)
	gprintf("%1m can be attacked with gain (captures %1m) at %1m (%d variations)", 
		pos, kworm, move, count_variations);
      
      count_variations = 1;
      dcode = owl_defend(pos, &move, NULL, &kworm);
      if (dcode) {
	if (dcode == WIN) {
	  if (move == NO_MOVE)
	    gprintf("%1m is alive as it stands\n", pos);
	  else 
	    gprintf("%1m can be defended at %1m (%d variations)\n", 
		    pos, move, count_variations);
	}
	else if (dcode == KO_A)
	  gprintf("%1m can be defended with ko (good) at %1m (%d variations)\n", 
		  pos, move, count_variations);
	else if (dcode == KO_B)
	  gprintf("%1m can be defended with ko (bad) at %1m (%d variations)\n",
		  pos, move, count_variations);
	else if (dcode == LOSS)
	  gprintf("%1m can be defended with loss (loses %1m) at %1m (%d variations)", 
		  pos, kworm, move, count_variations);
      }
      else
	gprintf("%1m cannot be defended (%d variations)\n", 
		pos, count_variations);
    }
    else 
      gprintf("%1m cannot be attacked (%d variations)\n", 
	      pos, count_variations);
    
    if (acode) {
      if (dcode)
	gprintf("status of %1m revised to CRITICAL\n", pos);
      else
	gprintf("status of %1m revised to DEAD\n", pos);
    }
    else
      gprintf("status of %1m revised to ALIVE\n", pos);
  }
  
  sgffile_enddump(outfilename);
  count_variations = 0;
}
예제 #10
0
/* Generate a move to definitely settle the position after the game
 * has been finished. The purpose of this is to robustly determine
 * life and death status and to distinguish between life in seki and
 * life with territory.
 *
 * The strategy is basically to turn all own living stones into
 * invincible ones and remove from the board all dead opponent stones.
 * Stones which cannot be removed, nor turned invincible, are alive in
 * seki.
 *
 * If do_capture_dead_stones is 0, opponent stones are not necessarily
 * removed from the board. This happens if they become unconditionally
 * dead anyway.
 *
 * Moves are generated in the following order of priority:
 * 0. Play edge liberties in certain positions. This is not really
 *    necessary, but often it can simplify the tactical and strategical
 *    reading substantially, making subsequent moves faster to generate.
 * 1. Capture an opponent string in atari and adjacent to own
 *    invincible string. Moves leading to ko or snapback are excluded.
 * 2. Extend an invincible string to a liberty of an opponent string.
 * 3. Connect a non-invincible string to an invincible string.
 * 4. Extend an invincible string towards an opponent string or an own
 *    non-invincible string.
 * 5. Split a big eyespace of an alive own dragon without invincible
 *    strings into smaller pieces.
 * 6. Play a liberty of a dead opponent dragon.
 *
 * Steps 2--4 are interleaved to try to optimize the efficiency of the
 * moves. In step 5 too, efforts are made to play efficient moves.  By
 * efficient we here mean moves which are effectively settling the
 * position and simplify the tactical and strategical reading for
 * subsequent moves.
 *
 * Steps 1--4 are guaranteed to be completely safe. Step 0 and 5
 * should also be risk-free. Step 6 on the other hand definitely
 * isn't. Consider for example this position:
 *
 * .XXXXX.
 * XXOOOXX
 * XOO.OOX
 * XOXXXOX
 * XO.XXOX
 * -------
 *
 * In order to remove the O stones, it is necessary to play on one of
 * the inner liberties, but one of them lets O live. Thus we have to
 * check carefully for blunders at this step.
 *
 * Update: Step 0 is only safe against blunders if care is taken not
 *         to get into a shortage of liberties.
 *         Step 5 also has some risks. Consider this position:
 *
 *         |XXXXX.
 *         |OOOOXX
 *         |..O.OX
 *         |OX*OOX
 *         +------
 *
 *         Playing at * allows X to make seki.
 *
 * IMPORTANT RESTRICTION:
 * Before calling this function it is mandatory to call genmove() or
 * genmove_conservative(). For this function to be meaningful, the
 * genmove() call should return pass.
 */
int
aftermath_genmove(int *aftermath_move, int color,
		  int under_control[BOARDMAX],
		  int do_capture_dead_stones)
{
  int k;
  int other = OTHER_COLOR(color);
  int distance[BOARDMAX];
  int score[BOARDMAX];
  float owl_hotspot[BOARDMAX];
  float reading_hotspot[BOARDMAX];
  int dragons[BOARDMAX];
  int something_found;
  int closest_opponent = NO_MOVE;
  int closest_own = NO_MOVE;
  int d;
  int move = NO_MOVE;
  int pos = NO_MOVE;
  int best_score;
  int best_scoring_move;
  
  owl_hotspots(owl_hotspot);
  reading_hotspots(reading_hotspot);
  
  /* As a preparation we compute a distance map to the invincible strings. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!ON_BOARD(pos))
      continue;
    else if (board[pos] == color && worm[pos].invincible)
      distance[pos] = 0;
    else if (!do_capture_dead_stones
	     && ((board[pos] == other 
		  && worm[pos].unconditional_status == DEAD)
		 || (board[pos] == color
		     && worm[pos].unconditional_status == ALIVE)))
      distance[pos] = 0;
    else
      distance[pos] = -1;
  }
  
  d = 0;
  do {
    something_found = 0;
    for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
      if (ON_BOARD(pos) && distance[pos] == -1) {
	for (k = 0; k < 4; k++) {
	  int pos2 = pos + delta[k];
	  if (!ON_BOARD(pos2))
	    continue;
	  if ((d == 0 || board[pos2] == EMPTY)
	      && distance[pos2] == d) {
	    if (d > 0 && board[pos] == other) {
	      distance[pos] = d + 1;
	      if (closest_opponent == NO_MOVE)
		closest_opponent = pos;
	    }
	    else if (d > 0 && board[pos] == color) {
	      distance[pos] = d + 1;
	      if (closest_own == NO_MOVE)
		closest_own = pos;
	    }
	    else if (board[pos] == EMPTY) {
	      distance[pos] = d + 1;
	      something_found = 1;
	    }
	    break;
	  }
	}
      }
    }
    d++;
  } while (something_found);

  if (under_control) {
    for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
      if (!ON_BOARD(pos))
	continue;
      else if (distance[pos] == -1)
	under_control[pos] = 0;
      else
	under_control[pos] = 1;
    }
  }
  
  if (debug & DEBUG_AFTERMATH) {
    int m, n;
    for (m = 0; m < board_size; m++) {
      for (n = 0; n < board_size; n++) {
	pos = POS(m, n);
	if (distance[pos] > 0)
	  fprintf(stderr, "%2d", distance[pos]);
	else if (distance[pos] == 0) {
	  if (board[pos] == WHITE)
	    gprintf(" o");
	  else if (board[pos] == BLACK)
	    gprintf(" x");
	  else
	    gprintf(" ?");
	}
	else {
	  if (board[pos] == WHITE)
	    gprintf(" O");
	  else if (board[pos] == BLACK)
	    gprintf(" X");
	  else
	    gprintf(" .");
	}
      }
      gprintf("\n");
    }
  
    gprintf("Closest opponent %1m", closest_opponent);
    if (closest_opponent != NO_MOVE)
      gprintf(", distance %d\n", distance[closest_opponent]);
    else
      gprintf("\n");

    gprintf("Closest own %1m", closest_own);
    if (closest_own != NO_MOVE)
      gprintf(", distance %d\n", distance[closest_own]);
    else
      gprintf("\n");
  }

  /* Case 0. This is a special measure to avoid a certain kind of
   * tactical reading inefficiency.
   *
   * Here we play on edge liberties in the configuration
   *
   * XO.
   * .*.
   * ---
   *
   * to stop X from "leaking" out along the edge. Sometimes this can
   * save huge amounts of tactical reading for later moves.
   */
  best_scoring_move = NO_MOVE;
  best_score = 5;
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    int libs;
    if (board[pos] != EMPTY
	|| distance[pos] == 0)
      continue;

    libs = approxlib(pos, color, 3, NULL);
    if (libs < 3)
      continue;

    if (is_self_atari(pos, other))
      continue;
    
    for (k = 0; k < 4; k++) {
      int dir = delta[k];
      int right = delta[(k+1)%4];
      if (!ON_BOARD(pos - dir)
	  && board[pos + dir] == color
	  && board[pos + dir + right] == other
	  && board[pos + dir - right] == other
	  && (libs > countlib(pos + dir)
	      || (libs > 4
		  && libs == countlib(pos + dir)))
	  && (DRAGON2(pos + dir).safety == INVINCIBLE
	      || DRAGON2(pos + dir).safety == STRONGLY_ALIVE)) {
	int this_score = 20 * (owl_hotspot[pos] + reading_hotspot[pos]);
	if (this_score > best_score) {
	  best_score = this_score;
	  best_scoring_move = pos;
	}
      }
    }
  }
  
  if (best_scoring_move != NO_MOVE
      && safe_move(best_scoring_move, color) == WIN) {
    *aftermath_move = best_scoring_move;
    DEBUG(DEBUG_AFTERMATH, "Closing edge at %1m\n", best_scoring_move);
    return 1;
  }

  /* Case 1. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    int lib;
    if (board[pos] == other
	&& worm[pos].unconditional_status != DEAD
	&& countlib(pos) == 1
	&& ((ON_BOARD(SOUTH(pos))    && distance[SOUTH(pos)] == 0)
	    || (ON_BOARD(WEST(pos))  && distance[WEST(pos)]  == 0)
	    || (ON_BOARD(NORTH(pos)) && distance[NORTH(pos)] == 0)
	    || (ON_BOARD(EAST(pos))  && distance[EAST(pos)]  == 0))) {
      findlib(pos, 1, &lib);
      /* Make sure we don't play into a ko or a (proper) snapback. */
      if (countstones(pos) > 1 || !is_self_atari(lib, color)) {
	*aftermath_move = lib;
	return 1;
      }
    }
  }

  /* Cases 2--4. */
  if (closest_opponent != NO_MOVE || closest_own != NO_MOVE) {
    if (closest_own == NO_MOVE)
      move = closest_opponent;
    else
      move = closest_own;

    /* if we're about to play at distance 1, try to optimize the move. */
    if (distance[move] == 2) {
      char mx[BOARDMAX];
      char mark = 0;
      memset(mx, 0, sizeof(mx));
      best_score = 0;
      best_scoring_move = move;

      for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
	int score = 0;
	int move_ok = 0;
	if (!ON_BOARD(pos) || distance[pos] != 1)
	  continue;
	mark++;
	for (k = 0; k < 4; k++) {
	  int pos2 = pos + delta[k];
	  if (!ON_BOARD(pos2))
	    continue;
	  if (distance[pos2] < 1)
	    score--;
	  else if (board[pos2] == EMPTY)
	    score++;
	  else if (mx[pos2] == mark)
	    score--;
	  else {
	    if (board[pos2] == color) {
	      move_ok = 1;
	      score += 7;
	      if (countstones(pos2) > 2)
		score++;
	      if (countstones(pos2) > 4)
		score++;
	      if (countlib(pos2) < 4)
		score++;
	      if (countlib(pos2) < 3)
		score++;
	    }
	    else {
	      int deltalib = (approxlib(pos, other, MAXLIBS, NULL)
			      - countlib(pos2));
	      move_ok = 1;
	      score++;
	      if (deltalib >= 0)
		score++;
	      if (deltalib > 0)
		score++;
	    }
	    mark_string(pos2, mx, mark);
	  }
	}
	if (is_suicide(pos, other))
	  score -= 3;
	
	if (0)
	  gprintf("Score %1m = %d\n", pos, score);
	
	if (move_ok && score > best_score) {
	  best_score = score;
	  best_scoring_move = pos;
	}
      }
      move = best_scoring_move;
    }

    while (distance[move] > 1) {
      for (k = 0; k < 4; k++) {
	int pos2 = move + delta[k];
	if (ON_BOARD(pos2)
	    && board[pos2] == EMPTY
	    && distance[pos2] == distance[move] - 1) {
	  move = pos2;
	  break;
	}
      }
    }
    *aftermath_move = move;
    return 1;
  }
  
  /* Case 5.
   * If we reach here, either all strings of a dragon are invincible
   * or no string is. Next we try to make alive dragons invincible by
   * splitting big eyes into smaller ones. Our strategy is to search
   * for an empty vertex with as many eye points as possible adjacent
   * and with at least one alive but not invincible stone adjacent or
   * diagonal.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    int eyespace_neighbors = 0;
    int own_neighbors = 0;
    int own_diagonals = 0;
    int opponent_dragons = 0;
    int own_worms = 0;
    int safety = UNKNOWN;
    int bonus = 0;
    int mx[BOARDMAX];
    score[pos] = 0;
      
    if (board[pos] != EMPTY || distance[pos] != -1)
      continue;

    memset(mx, 0, sizeof(mx));
    
    for (k = 0; k < 8; k++) {
      int pos2 = pos + delta[k];
      if (!ON_BOARD(pos2))
	continue;
      
      if (board[pos2] == EMPTY) {
	if (k < 4)
	  eyespace_neighbors++;
	continue;
      }
      
      if (board[pos2] == other) {
	int origin = dragon[pos2].origin;
	
	if (k < 4) {
	  if (dragon[pos2].status == ALIVE) {
	    safety = DEAD;
	    break;
	  }
	  else if (!mx[origin]) {
	    eyespace_neighbors++;
	    opponent_dragons++;
	  }
	}

	if (!mx[origin] && dragon[pos2].status == DEAD) {
	  bonus++;
	  if (k < 4 
	      && countlib(pos2) <= 2 
	      && countstones(pos2) >= 3)
	    bonus++;
	  
	  if (k < 4 && countlib(pos2) == 1)
	    bonus += 3;
	}
	mx[origin] = 1;
      }
      else if (board[pos2] == color) {
	dragons[pos] = pos2;
	
	if (safety == UNKNOWN && dragon[pos2].status == ALIVE)
	  safety = ALIVE;
	
	if (DRAGON2(pos2).safety == INVINCIBLE)
	  safety = INVINCIBLE;
	
	if (k < 4) {
	  int apos = worm[pos2].origin;
	  
	  if (!mx[apos]) {
	    own_worms++;
	    if (countstones(apos) == 1)
	      bonus += 2;
	    if (countlib(apos) < 6
		&& approxlib(pos, color, 5, NULL) < countlib(apos))
	      bonus -= 5;
	    mx[apos] = 1;
	  }
	  
	  if (countlib(apos) <= 2) {
	    int r;
	    int important = 0;
	    int safe_atari = 0;
	    for (r = 0; r < 4; r++) {
	      d = delta[r];
	      if (!ON_BOARD(apos+d))
		continue;
	      if (board[apos+d] == other
		  && dragon[apos+d].status == DEAD)
		important = 1;
	      else if (board[apos+d] == EMPTY
		       && !is_self_atari(apos+d, other))
		safe_atari = 1;
	    }
	    if (approxlib(pos, color, 3, NULL) > 2) {
	      bonus++;
	      if (important) {
		bonus += 2;
		if (safe_atari)
		  bonus += 2;
	      }
	    }
	  }
	  
	  own_neighbors++;
	}
	else
	  own_diagonals++;
      }
    }
    if (safety == DEAD || safety == UNKNOWN
	|| eyespace_neighbors == 0
	|| (own_neighbors + own_diagonals) == 0)
      continue;
    
    if (bonus < 0)
      bonus = 0;
      
    score[pos] = 4 * eyespace_neighbors + bonus;
    if (safety == INVINCIBLE) {
      score[pos] += own_neighbors;
      if (own_neighbors < 2)
	score[pos] += own_diagonals;
      if (own_worms > 1 && eyespace_neighbors >= 1)
	score[pos] += 10 + 5 * (own_worms - 2);
    }
    else if (eyespace_neighbors > 2)
      score[pos] += own_diagonals;
    
    /* Splitting bonus. */
    if (opponent_dragons > 1)
      score[pos] += 10 * (opponent_dragons - 1);
    
    /* Hotspot bonus. */
    {
      int owl_hotspot_bonus = (int) (20.0 * owl_hotspot[pos]);
      int reading_hotspot_bonus = (int) (20.0 * reading_hotspot[pos]);
      int hotspot_bonus = owl_hotspot_bonus + reading_hotspot_bonus;
      
      /* Don't allow the hotspot bonus to turn a positive score into
       * a non-positive one.
       */
      if (score[pos] > 0 && score[pos] + hotspot_bonus <= 0)
	hotspot_bonus = 1 - score[pos];
      
      score[pos] += hotspot_bonus;
      
      if (1 && (debug & DEBUG_AFTERMATH))
	gprintf("Score %1M = %d (hotspot bonus %d + %d)\n", pos, score[pos],
		owl_hotspot_bonus, reading_hotspot_bonus);
    }
    
    /* Avoid taking ko. */
    if (is_ko(pos, color, NULL))
      score[pos] = (score[pos] + 1) / 2;
  }
  
  while (1) {
    int bb;
    best_score = 0;
    move = NO_MOVE;
    for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
      if (ON_BOARD(pos) && score[pos] > best_score) {
	best_score = score[pos];
	move = pos;
      }
    }

    if (move == NO_MOVE)
      break;

    bb = dragons[move];
    if (is_illegal_ko_capture(move, color)
	|| !safe_move(move, color)
	|| (DRAGON2(bb).safety != INVINCIBLE
	    && DRAGON2(bb).safety != STRONGLY_ALIVE
	    && owl_does_defend(move, bb, NULL) != WIN)
	|| (!confirm_safety(move, color, NULL, NULL))) {
      score[move] = 0;
    }
    else {
      /* If we're getting short of liberties, we must be more careful.
       * Check that no adjacent string or dragon gets more alive by
       * the move.
       */
      int libs = approxlib(move, color, 5, NULL);
      int move_ok = 1;
      if (libs < 5) {
	for (k = 0; k < 4; k++) {
	  if (board[move + delta[k]] == color
	      && countlib(move + delta[k]) > libs)
	    break;
	}
	if (k < 4) {
	  if (trymove(move, color, "aftermath-B", move + delta[k])) {
	    int adjs[MAXCHAIN];
	    int neighbors;
	    int r;
	    neighbors = chainlinks(move, adjs);
	    for (r = 0; r < neighbors; r++) {
	      if (worm[adjs[r]].attack_codes[0] != 0
		  && (find_defense(adjs[r], NULL)
		      > worm[adjs[r]].defense_codes[0])) {
		DEBUG(DEBUG_AFTERMATH,
		      "Blunder: %1m becomes tactically safer after %1m\n",
		      adjs[r], move);
		move_ok = 0;
	      }
	    }
	    popgo();
	    for (r = 0; r < neighbors && move_ok; r++) {
	      if (dragon[adjs[r]].status == DEAD
		  && !owl_does_attack(move, adjs[r], NULL)) {
		DEBUG(DEBUG_AFTERMATH,
		      "Blunder: %1m becomes more alive after %1m\n",
		      adjs[r], move);
		move_ok = 0;
	      }
	    }
	  }
	}
      }

      if (!move_ok)
	score[move] = 0;
      else {
	*aftermath_move = move;
	DEBUG(DEBUG_AFTERMATH, "Splitting eyespace at %1m\n", move);
	return 1;
      }
    }
  }

  /* Case 6.
   * Finally we try to play on liberties of remaining DEAD opponent
   * dragons, carefully checking against mistakes.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    int target;
    int cc = NO_MOVE;
    int self_atari_ok = 0;
    if (board[pos] != EMPTY || distance[pos] != -1)
      continue;
    target = NO_MOVE;
    for (k = 0; k < 4; k++) {
      int pos2 = pos + delta[k];
      if (!ON_BOARD(pos2))
	continue;
      if (board[pos2] == other 
	  && dragon[pos2].status != ALIVE
	  && (do_capture_dead_stones 
	      || worm[pos2].unconditional_status != DEAD)
	  && DRAGON2(pos2).safety != INESSENTIAL) {
	target = pos2;
	break;
      }
    }
    if (target == NO_MOVE)
      continue;
    
    /* At this point, (pos) is a move that potentially may capture
     * a dead opponent string at (target).
     */
    
    if (!trymove(pos, color, "aftermath-A", target))
      continue;
    
    /* It is frequently necessary to sacrifice own stones in order
     * to force the opponent's stones to be removed from the board,
     * e.g. by adding stones to fill up a nakade shape. However, we
     * should only play into a self atari if the sacrificed stones
     * are classified as INESSENTIAL. Thus it would be ok for O to
     * try a self atari in this position:
     *
     * |OOOO
     * |XXXO
     * |..XO
     * |OOXO
     * +----
     *
     * but not in this one:
     *
     * |XXX..
     * |OOXX.
     * |.OOXX
     * |XXOOX
     * |.O.OX
     * +-----
     */

    self_atari_ok = 1;
    for (k = 0; k < 4; k++) {
      if (board[pos + delta[k]] == color
	  && DRAGON2(pos + delta[k]).safety != INESSENTIAL) {
	self_atari_ok = 0;
	cc = pos + delta[k];
	break;
      }
    }
    
    /* Copy the potential move to (move). */
    move = pos;
    
    /* If the move is a self atari, but that isn't okay, try to
     * recursively find a backfilling move which later makes the
     * potential move possible.
     */
    if (!self_atari_ok) {
      while (countlib(pos) == 1) {
	int lib;
	findlib(pos, 1, &lib);
	move = lib;
	if (!trymove(move, color, "aftermath-B", target))
	  break;
      }
      
      if (countlib(pos) == 1)
	move = NO_MOVE;
    }

    while (stackp > 0)
      popgo();
    
    if (move == NO_MOVE)
      continue;
      
    /* Make sure that the potential move really isn't a self
     * atari. In the case of a move found after backfilling this
     * could happen (because the backfilling moves happened to
     * capture some stones).
     */
    if (!self_atari_ok && is_self_atari(move, color))
      continue;
    
    /* Consult the owl code to determine whether the considered move
     * really is effective. Blunders should be detected here.
     */
    if (owl_does_attack(move, target, NULL) == WIN) {
      /* If we have an adjacent own dragon, which is not inessential,
       * verify that it remains safe.
       */
      if (cc != NO_MOVE && !owl_does_defend(move, cc, NULL))
	continue;

      /* If we don't allow self atari, also call confirm safety to
       * avoid setting up combination attacks.
       */
      if (!self_atari_ok && !confirm_safety(move, color, NULL, NULL))
	continue;
	  
      *aftermath_move = move;
      DEBUG(DEBUG_AFTERMATH, "Filling opponent liberty at %1m\n", move);
      return 1;
    }
  }
  
  /* Case 7.
   * In very rare cases it turns out we need yet another pass. An
   * example is this position:
   *
   * |.....
   * |OOOO.
   * |XXXO.
   * |.OXO.
   * |O.XO.
   * +-----
   *
   * Here the X stones are found tactically dead and therefore the
   * corner O stones have been amalgamated with the surrounding
   * stones. Since the previous case only allows sacrificing
   * INESSENTIAL stones, it fails to take X off the board.
   *
   * The solution is to look for tactically attackable opponent stones
   * that still remain on the board but should be removed.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] == other
	&& (worm[pos].unconditional_status == UNKNOWN
	    || do_capture_dead_stones)
	&& (DRAGON2(pos).safety == DEAD
	    || DRAGON2(pos).safety == TACTICALLY_DEAD)
	&& worm[pos].attack_codes[0] != 0
	&& !is_illegal_ko_capture(worm[pos].attack_points[0], color)) {
      *aftermath_move = worm[pos].attack_points[0];
      DEBUG(DEBUG_AFTERMATH, "Tactically attack %1m at %1m\n",
	    pos, *aftermath_move);
      return 1;
    }
  }
  
  /* No move found. */
  return -1;
}
예제 #11
0
static void
play_aftermath(int color)
{
  int pos;
  struct board_state saved_board;
  struct aftermath_data *a = &aftermath;
  static int current_board[BOARDMAX];
  static int current_color = EMPTY;
  int cached_board = 1;
  gg_assert(color == BLACK || color == WHITE);

  if (current_color != color) {
    current_color = color;
    cached_board = 0;
  }

  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (ON_BOARD(pos) && board[pos] != current_board[pos]) {
      current_board[pos] = board[pos];
      cached_board = 0;
    }
  }

  /* If this is exactly the same position as the one we analyzed the
   * last time, the content of the aftermath struct is up to date.
   */
  if (cached_board)
    return;

  a->white_captured = white_captured;
  a->black_captured = black_captured;
  a->white_prisoners = 0;
  a->black_prisoners = 0;
  a->white_territory = 0;
  a->black_territory = 0;
  a->white_area = 0;
  a->black_area = 0;
  
  store_board(&saved_board);
  do_play_aftermath(color, a);
  restore_board(&saved_board);
  
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!ON_BOARD(pos))
      continue;
    if (a->black_control[pos]) {
      a->black_area++;
      if (board[pos] == WHITE) {
	a->black_territory++;
	a->white_prisoners++;
	a->final_status[pos] = DEAD;
      }
      else if (board[pos] == EMPTY) {
	a->black_territory++;
	a->final_status[pos] = BLACK_TERRITORY;
      }
      else
	a->final_status[pos] = ALIVE;
    }
    else if (a->white_control[pos]) {
      a->white_area++;
      if (board[pos] == BLACK) {
	a->white_territory++;
	a->black_prisoners++;
	a->final_status[pos] = DEAD;
      }
      else if (board[pos] == EMPTY) {
	a->white_territory++;
	a->final_status[pos] = WHITE_TERRITORY;
      }
      else
	a->final_status[pos] = ALIVE;
    }
    else {
      if (board[pos] == EMPTY)
	a->final_status[pos] = DAME;
      else {
	a->final_status[pos] = ALIVE_IN_SEKI;
	if (board[pos] == WHITE)
	  a->white_area++;
	else
	  a->black_area++;
      }
    }
  }

  if (debug & DEBUG_AFTERMATH) {
    gprintf("White captured: %d\n", a->white_captured);
    gprintf("Black captured: %d\n", a->black_captured);
    gprintf("White prisoners: %d\n", a->white_prisoners);
    gprintf("Black prisoners: %d\n", a->black_prisoners);
    gprintf("White territory: %d\n", a->white_territory);
    gprintf("Black territory: %d\n", a->black_territory);
    gprintf("White area: %d\n", a->white_area);
    gprintf("Black area: %d\n", a->black_area);
  }
}
예제 #12
0
void
unconditional_life(int unconditional_territory[BOARDMAX], int color)
{
  int found_one;
  int other = OTHER_COLOR(color);
  int libs[MAXLIBS];
  int liberties;
  int pos;
  int k, r;
  int moves_played;
  int potential_sekis[BOARDMAX];
  int none_invincible;

  /* Initialize unconditional_territory array. */
  memset(unconditional_territory, 0,
	 sizeof(unconditional_territory[0]) * BOARDMAX);
  
  /* Find isolated two-stone strings which might be involved in the
   * kind of seki described in the comments.
   */
  memset(potential_sekis, 0, sizeof(potential_sekis));
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    int isolated = 1;
    int stones[2];
    int pos2;
    
    if (board[pos] != color
	|| find_origin(pos) != pos
	|| countstones(pos) != 2)
      continue;
    
    findstones(pos, 2, stones);
    for (k = 0; k < 2 && isolated; k++) {
      for (r = 0; r < 8 && isolated; r++) {
	pos2 = stones[k] + delta[r];
	if (!ON_BOARD(pos2)
	    || (board[pos2] == color
		&& !same_string(pos, pos2)))
	  isolated = 0;
      }
    }

    if (isolated) {
      potential_sekis[stones[0]] = 1;
      potential_sekis[stones[1]] = 1;
    }
  }
  
  moves_played = capture_non_invincible_strings(color, potential_sekis,
						&none_invincible);

  /* If there are no invincible strings, nothing can be unconditionally
   * settled.
   */
  if (none_invincible) {
    /* Take back all moves. */
    while (moves_played > 0) {
      popgo();
      moves_played--;
    }
    return;
  }
  
  /* The strings still remaining except those marked in
   * potential_sekis[] are uncapturable. Now see which opponent
   * strings can survive.
   *
   * 1. Play opponent stones on all liberties of the unconditionally
   *    alive strings except where illegal.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] != color || potential_sekis[pos] || find_origin(pos) != pos)
      continue;
      
    /* Play as many liberties as we can. */
    liberties = findlib(pos, MAXLIBS, libs);
    for (k = 0; k < liberties; k++) {
      if (trymove(libs[k], other, "unconditional_life", pos))
	moves_played++;
    }
  }

  /* 2. Recursively extend opponent strings in atari, except where this
   *    would be suicide.
   */
  found_one = 1;
  while (found_one) {
    /* Nothing found so far in this turn of the loop. */
    found_one = 0;

    for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
      if (board[pos] != other || countlib(pos) > 1)
	continue;
	
      /* Try to extend the string at (m, n). */
      findlib(pos, 1, libs);
      if (trymove(libs[0], other, "unconditional_life", pos)) {
	moves_played++;
	found_one = 1;
      }
    }
  }

  /* Now see whether there are any significant sekis on the board. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!potential_sekis[pos]
	|| board[pos] == EMPTY
	|| find_origin(pos) != pos)
      continue;
    for (r = 0; r < 4; r++) {
      int up = delta[r];
      int right = delta[(r + 1) % 4];
      int locally_played_moves = 0;
      if (board[pos + up] != color
	  || board[pos + up + up] != EMPTY
	  || board[pos - up] != EMPTY)
	continue;
      for (k = 0; k < 2; k++) {
	if (k == 1)
	  right = -right;
	if (board[pos + right] != EMPTY || board[pos + up - right] != EMPTY)
	  continue;
	if (board[pos - right] == EMPTY
	    && trymove(pos - right, other, "unconditional_life", pos))
	  locally_played_moves++;
	if (board[pos + up + right] == EMPTY
	    && trymove(pos + up + right, other, "unconditional_life", pos))
	  locally_played_moves++;
	if (board[pos - right] == other && board[pos + up + right] == other
	    && same_string(pos - right, pos + up + right)) {
	  /* This is a critical seki. Extend the string with one stone
           * in an arbitrary direction to break the seki.
	   */
	  while (locally_played_moves > 0) {
	    popgo();
	    locally_played_moves--;
	  }
	  trymove(pos - up, color, "unconditional_life", pos);
	  moves_played++;
	  break;
	}
	else {
	  while (locally_played_moves > 0) {
	    popgo();
	    locally_played_moves--;
	  }
	}
      }
      if (countstones(pos) > 2)
	break;
    }
  }

  /* Capture the strings involved in potential sekis. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!potential_sekis[pos] || board[pos] == EMPTY)
      continue;
    /* Play as many liberties as we can. */
    liberties = findlib(pos, MAXLIBS, libs);
    for (k = 0; k < liberties; k++) {
      if (trymove(libs[k], other, "unconditional_life", pos))
	moves_played++;
    }
  }
    

  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    int apos;
    int bpos;
    int aopen, bopen;
    int alib, blib;
    if (board[pos] != other || countlib(pos) != 2)
      continue;
    findlib(pos, 2, libs);
    apos = libs[0];
    bpos = libs[1];
    if (abs(I(apos) - I(bpos)) + abs(J(apos) - J(bpos)) != 1)
      continue;
    
    /* Only two liberties and these are adjacent. Play one. We want
     * to maximize the number of open liberties. In this particular
     * situation we can count this with approxlib for the opposite
     * color. If the number of open liberties is the same, we
     * maximize the total number of obtained liberties.
     * Two relevant positions:
     *
     * |XXX. 
     * |OOXX    |XXXXXXX
     * |O.OX    |OOXOOOX
     * |..OX    |..OO.OX
     * +----    +-------
     */
    aopen = approxlib(apos, color, 4, NULL);
    bopen = approxlib(bpos, color, 4, NULL);
    alib  = approxlib(apos, other, 4, NULL);
    blib  = approxlib(bpos, other, 4, NULL);
    
    if (aopen > bopen || (aopen == bopen && alib >= blib)) {
      trymove(apos, other, "unconditional_life", pos);
      moves_played++;
    }
    else {
      trymove(bpos, other, "unconditional_life", pos);
      moves_played++;
    }
  }
  
  /* Identify unconditionally alive stones and unconditional territory. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] == color && !potential_sekis[pos]) {
      unconditional_territory[pos] = 1;
      if (find_origin(pos) == pos) {
	liberties = findlib(pos, MAXLIBS, libs);
	for (k = 0; k < liberties; k++)
	  unconditional_territory[libs[k]] = 2;
      }
    }
    else if (board[pos] == other && countlib(pos) == 1) {
      unconditional_territory[pos] = 2;
      findlib(pos, 1, libs);
      unconditional_territory[libs[0]] = 2;
    }
  }
  
  /* Take back all moves. */
  while (moves_played > 0) {
    popgo();
    moves_played--;
  }
}
예제 #13
0
static void
compute_active_reading_area(struct persistent_cache_entry *entry,
			    const char goal[BOARDMAX], int dummy)
{
  signed char active[BOARDMAX];
  int pos, r;
  UNUSED(dummy);

  /* Remains to set the board. We let the active area be the contested
   * string and reading shadow + adjacent empty and strings +
   * neighbors of active area so far + one more expansion from empty
   * to empty.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++)
    active[pos] = goal[pos];

  signed_mark_string(entry->apos, active, 1);

  /* To be safe, also add the successful move. */
  if (entry->result != 0 && entry->move != 0)
    active[entry->move] = 1;

  /* Add adjacent strings and empty. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!ON_BOARD(pos))
      continue;
    if (active[pos] != 0) 
      continue;
    if ((ON_BOARD(SOUTH(pos)) && active[SOUTH(pos)] == 1)
	|| (ON_BOARD(WEST(pos)) && active[WEST(pos)] == 1)
	|| (ON_BOARD(NORTH(pos)) && active[NORTH(pos)] == 1)
	|| (ON_BOARD(EAST(pos)) && active[EAST(pos)] == 1)) {
      if (IS_STONE(board[pos]))
	signed_mark_string(pos, active, 2);
      else
	active[pos] = 2;
    }
  }

  /* Remove invincible strings. No point adding their liberties and
   * neighbors.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!ON_BOARD(pos))
      continue;
    if (IS_STONE(board[pos]) && worm[pos].invincible)
      active[pos] = 0;
  }
  
  /* Expand empty to empty. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (IS_STONE(board[pos]) || active[pos] != 0) 
      continue;
    if ((board[SOUTH(pos)] == EMPTY && active[SOUTH(pos)] == 2)
	|| (board[WEST(pos)] == EMPTY && active[WEST(pos)] == 2)
	|| (board[NORTH(pos)] == EMPTY && active[NORTH(pos)] == 2)
	|| (board[EAST(pos)] == EMPTY && active[EAST(pos)] == 2))
      active[pos] = 3;
  }
  
  /* Add neighbors of active area so far. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!ON_BOARD(pos))
      continue;
    if (active[pos] != 0) 
      continue;
    if ((ON_BOARD(SOUTH(pos)) && active[SOUTH(pos)] > 0
	 && active[SOUTH(pos)] < 4)
	|| (ON_BOARD(WEST(pos)) && active[WEST(pos)] > 0
	    && active[WEST(pos)] < 4)
	|| (ON_BOARD(NORTH(pos)) && active[NORTH(pos)] > 0
	    && active[NORTH(pos)] < 4)
	|| (ON_BOARD(EAST(pos)) && active[EAST(pos)] > 0
	    && active[EAST(pos)] < 4))
      active[pos] = 4;
  }

  /* Also add the previously played stones to the active area. */
  for (r = 0; r < stackp; r++)
    active[entry->stack[r]] = 5;

  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (!ON_BOARD(pos))
      continue;
    entry->board[pos] = 
      active[pos] != 0 ? board[pos] : GRAY;
  }
}
예제 #14
0
static void compute_active_owl_area(struct persistent_cache_entry *entry,
				    const char goal[BOARDMAX],
				    int goal_color)
{
  int k, r;
  int pos;
  int other = OTHER_COLOR(goal_color);
  signed char active[BOARDMAX];

  /* We let the active area be the goal +
   * distance four expansion through empty intersections and own stones +
   * adjacent opponent strings +
   * liberties and neighbors of adjacent opponent strings with less than
   * five liberties +
   * liberties and neighbors of low liberty neighbors of adjacent opponent
   * strings with less than five liberties.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++)
    if (ON_BOARD(pos))
      active[pos] = (goal[pos] != 0);

  /* Also add critical moves to the active area. */
  if (ON_BOARD1(entry->move))
    active[entry->move] = 1;

  if (ON_BOARD1(entry->move2))
    active[entry->move2] = 1;

  /* Distance four expansion through empty intersections and own stones. */
  for (k = 1; k < 5; k++) {
    for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
      if (!ON_BOARD(pos) || board[pos] == other || active[pos] > 0) 
	continue;
      if ((ON_BOARD(SOUTH(pos)) && active[SOUTH(pos)] == k)
	  || (ON_BOARD(WEST(pos)) && active[WEST(pos)] == k)
	  || (ON_BOARD(NORTH(pos)) && active[NORTH(pos)] == k)
	  || (ON_BOARD(EAST(pos)) && active[EAST(pos)] == k)) {
	if (board[pos] == EMPTY)
	  active[pos] = k + 1;
	else
	  signed_mark_string(pos, active, (signed char) (k + 1));
      }
    }
  }
  
  /* Adjacent opponent strings. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] != other || active[pos] != 0) 
      continue;
    for (r = 0; r < 4; r++) {
      int pos2 = pos + delta[r];
      if (ON_BOARD(pos2) && board[pos2] != other && active[pos2] != 0) {
	signed_mark_string(pos, active, 1);
	break;
      }
    }
  }
  
  /* Liberties of adjacent opponent strings with less than five liberties +
   * liberties of low liberty neighbors of adjacent opponent strings
   * with less than five liberties.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] == other && active[pos] > 0 && countlib(pos) < 5) {
      int libs[4];
      int liberties = findlib(pos, 4, libs);
      int adjs[MAXCHAIN];
      int adj;
      for (r = 0; r < liberties; r++)
	active[libs[r]] = 1;
      
      /* Also add liberties of neighbor strings if these are three
       * or less.
       */
      adj = chainlinks(pos, adjs);
      for (r = 0; r < adj; r++) {
	signed_mark_string(adjs[r], active, -1);
	if (countlib(adjs[r]) <= 3) {
	  int s;
	  int adjs2[MAXCHAIN];
	  int adj2;
	  liberties = findlib(adjs[r], 3, libs);
	  for (s = 0; s < liberties; s++)
	    active[libs[s]] = 1;
	  adj2 = chainlinks(pos, adjs2);
	  for (s = 0; s < adj2; s++)
	    signed_mark_string(adjs2[s], active, -1);
	}
      }
    }
  }
  
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    int value = board[pos];
    if (!ON_BOARD(pos))
      continue;
    if (!active[pos])
      value = GRAY;
    else if (IS_STONE(board[pos]) && countlib(pos) > 4 && active[pos] > 0)
      value |= HIGH_LIBERTY_BIT;
    
    entry->board[pos] = value;
  }
}
void
store_persistent_owl_cache(int routine, int apos, int bpos, int cpos,
			   int result, int move, int move2, int certain,
			   int tactical_nodes,
			   char goal[BOARDMAX], int goal_color)
{
  char active[BOARDMAX];
  int pos;
  int k;
  int r;
  int other = OTHER_COLOR(goal_color);
  gg_assert(stackp == 0);

  /* If cache is full, first try to purge it. */
  if (persistent_owl_cache_size == MAX_OWL_CACHE_SIZE)
    purge_persistent_owl_cache();

  /* FIXME: Kick out oldest or least expensive entry instead of giving up. */
  if (persistent_owl_cache_size == MAX_OWL_CACHE_SIZE) {
    TRACE_OWL_PERFORMANCE("Persistent owl cache full.\n");
    return;
  }

  persistent_owl_cache[persistent_owl_cache_size].boardsize  	 = board_size;
  persistent_owl_cache[persistent_owl_cache_size].routine    	 = routine;
  persistent_owl_cache[persistent_owl_cache_size].apos	     	 = apos;
  persistent_owl_cache[persistent_owl_cache_size].bpos	     	 = bpos;
  persistent_owl_cache[persistent_owl_cache_size].cpos	     	 = cpos;
  persistent_owl_cache[persistent_owl_cache_size].result     	 = result;
  persistent_owl_cache[persistent_owl_cache_size].result_certain = certain;
  persistent_owl_cache[persistent_owl_cache_size].move	         = move;
  persistent_owl_cache[persistent_owl_cache_size].move2	         = move2;
  persistent_owl_cache[persistent_owl_cache_size].tactical_nodes =
    tactical_nodes;
  persistent_owl_cache[persistent_owl_cache_size].movenum = movenum;
  
  /* Remains to set the board. We let the active area be
   * the goal +
   * distance four expansion through empty intersections and own stones +
   * adjacent opponent strings +
   * liberties of adjacent opponent strings with less than five liberties +
   * liberties of low liberty neighbors of adjacent opponent strings
   * with less than five liberties.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++)
    if (ON_BOARD(pos))
      active[pos] = (goal[pos] != 0);

  /* Also add critical moves to the active area. */
  if (ON_BOARD1(move))
    active[move] = 1;

  if (ON_BOARD1(move2))
    active[move2] = 1;

  /* Distance four expansion through empty intersections and own stones. */
  for (k = 1; k < 5; k++) {
    for (pos = BOARDMIN; pos < BOARDMAX; pos++){
      if (!ON_BOARD(pos) || board[pos] == other || active[pos] != 0) 
	continue;
      if ((ON_BOARD(SOUTH(pos)) && active[SOUTH(pos)] == k)
	  || (ON_BOARD(WEST(pos)) && active[WEST(pos)] == k)
	  || (ON_BOARD(NORTH(pos)) && active[NORTH(pos)] == k)
	  || (ON_BOARD(EAST(pos)) && active[EAST(pos)] == k)) {
	if (board[pos] == EMPTY)
	  active[pos] = k + 1;
	else
	  mark_string(pos, active, (char) (k + 1));
      }
    }
  }
  
  /* Adjacent opponent strings. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] != other || active[pos] != 0) 
      continue;
    for (r = 0; r < 4; r++) {
      int pos2 = pos + delta[r];
      if (ON_BOARD(pos2) && board[pos2] != other && active[pos2] != 0) {
	mark_string(pos, active, (char) 1);
	break;
      }
    }
  }
  
  /* Liberties of adjacent opponent strings with less than five liberties +
   * liberties of low liberty neighbors of adjacent opponent strings
   * with less than five liberties.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] == other && active[pos] != 0 && countlib(pos) < 5) {
      int libs[4];
      int liberties = findlib(pos, 4, libs);
      int adjs[MAXCHAIN];
      int adj;
      for (r = 0; r < liberties; r++)
	active[libs[r]] = 1;
      
      /* Also add liberties of neighbor strings if these are three
       * or less.
       */
      adj = chainlinks(pos, adjs);
      for (r = 0; r < adj; r++) {
	if (countlib(adjs[r]) <= 3) {
	  int s;
	  liberties = findlib(adjs[r], 3, libs);
	  for (s = 0; s < liberties; s++)
	    active[libs[s]] = 1;
	}
      }
    }
  }
  
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    int value = board[pos];
    if (!ON_BOARD(pos))
      continue;
    if (!active[pos])
      value = GRAY;
    else if (IS_STONE(board[pos]) && countlib(pos) > 4)
      value |= HIGH_LIBERTY_BIT;
    
    persistent_owl_cache[persistent_owl_cache_size].board[pos] = value;
  }

  if (debug & DEBUG_OWL_PERSISTENT_CACHE) {
    gprintf("%o Stored result in cache (entry %d):\n",
	    persistent_owl_cache_size);
    print_persistent_owl_cache_entry(persistent_owl_cache_size);
  }
  
  persistent_owl_cache_size++;
}
/* Store a new read result in the persistent cache. */
void
store_persistent_reading_cache(int routine, int str, int result, int move,
			       int nodes)
{
  char active[BOARDMAX];
  int k;
  int r;
  int score = nodes;
  struct reading_cache *entry;

  ASSERT1(result == 0 || (move == 0) || ON_BOARD(move), move);

  /* Never cache results at too great depth. */
  if (stackp > MAX_READING_CACHE_DEPTH)
    return;

  /* If cache is still full, consider kicking out an old entry. */
  if (persistent_reading_cache_size == MAX_READING_CACHE_SIZE) {
    int worst_entry = -1;
    int worst_score = score;
    
    for (k = 1; k < persistent_reading_cache_size; k++) {
      if (persistent_reading_cache[k].score < worst_score) {
	worst_score = persistent_reading_cache[k].score;
	worst_entry = k;
      }
    }

    if (worst_entry != -1) {
      /* Move the last entry in the cache here to make space.
       */
      if (worst_entry < persistent_reading_cache_size - 1)
	persistent_reading_cache[worst_entry] 
	  = persistent_reading_cache[persistent_reading_cache_size - 1];
      persistent_reading_cache_size--;
    }
    else
      return;
  }

  entry = &(persistent_reading_cache[persistent_reading_cache_size]);
  entry->boardsize       = board_size;
  entry->movenum         = movenum;
  entry->nodes           = nodes;
  entry->score           = score;
  entry->remaining_depth = depth - stackp;
  entry->routine         = routine;
  entry->str	         = str;
  entry->result          = result;
  entry->move	         = move;

  for (r = 0; r < MAX_READING_CACHE_DEPTH; r++) {
    if (r < stackp)
      get_move_from_stack(r, &(entry->stack[r]), &(entry->move_color[r]));
    else {
      entry->stack[r] = 0;
      entry->move_color[r] = EMPTY;
    }
  }
  
  /* Remains to set the board. We let the active area be the contested
   * string and reading shadow + adjacent empty and strings +
   * neighbors of active area so far + one more expansion from empty
   * to empty.
   */
  for (k = BOARDMIN; k < BOARDMAX; k++)
    active[k] = shadow[k];

  mark_string(str, active, 1);

  /* To be safe, also add the successful move. */
  if (result != 0 && move != 0)
    active[move] = 1;

  /* Add adjacent strings and empty. */
  for (k = BOARDMIN; k < BOARDMAX; k++) {
    if (!ON_BOARD(k))
      continue;
    if (active[k] != 0) 
      continue;
    if ((ON_BOARD(SOUTH(k)) && active[SOUTH(k)] == 1)
	|| (ON_BOARD(WEST(k)) && active[WEST(k)] == 1)
	|| (ON_BOARD(NORTH(k)) && active[NORTH(k)] == 1)
	|| (ON_BOARD(EAST(k)) && active[EAST(k)] == 1)) {
      if (IS_STONE(board[k]))
	mark_string(k, active, 2);
      else
	active[k] = 2;
    }
  }

  /* Remove invincible strings. No point adding their liberties and
   * neighbors.
   */
  for (k = BOARDMIN; k < BOARDMAX; k++) {
    if (!ON_BOARD(k))
      continue;
    if (IS_STONE(board[k]) && worm[k].invincible)
      active[k] = 0;
  }
  
  /* Expand empty to empty. */
  for (k = BOARDMIN; k < BOARDMAX; k++) {
    if (IS_STONE(board[k]) || active[k] != 0) 
      continue;
    if ((board[SOUTH(k)] == EMPTY && active[SOUTH(k)] == 2)
	|| (board[WEST(k)] == EMPTY && active[WEST(k)] == 2)
	|| (board[NORTH(k)] == EMPTY && active[NORTH(k)] == 2)
	|| (board[EAST(k)] == EMPTY && active[EAST(k)] == 2))
      active[k] = 3;
  }
  
  /* Add neighbors of active area so far. */
  for (k = BOARDMIN; k < BOARDMAX; k++) {
    if (!ON_BOARD(k))
      continue;
    if (active[k] != 0) 
      continue;
    if ((ON_BOARD(SOUTH(k)) && active[SOUTH(k)] > 0 && active[SOUTH(k)] < 4)
	|| (ON_BOARD(WEST(k)) && active[WEST(k)] > 0 && active[WEST(k)] < 4)
	|| (ON_BOARD(NORTH(k)) && active[NORTH(k)] > 0 && active[NORTH(k)] < 4)
	|| (ON_BOARD(EAST(k)) && active[EAST(k)] > 0 && active[EAST(k)] < 4))
      active[k] = 4;
  }

  /* Also add the previously played stones to the active area. */
  for (r = 0; r < stackp; r++)
    active[entry->stack[r]] = 5;

  for (k = BOARDMIN; k < BOARDMAX; k++) {
    if (!ON_BOARD(k))
      continue;
    entry->board[k] = 
      active[k] != 0 ? board[k] : GRAY;
  }

  if (0) {
    gprintf("%o Stored result in cache (entry %d):\n",
	    persistent_reading_cache_size);
    print_persistent_reading_cache_entry(persistent_reading_cache_size);
    gprintf("%o Reading shadow was:\n");
    draw_reading_shadow();
  }
  
  persistent_reading_cache_size++;
}
예제 #17
0
int
compute_surroundings(int pos, int apos, int showboard, int *surround_size)
{
  int i, j;
  int m, n;
  int k;
  int dpos;
  int surrounded;
  
  int left_corner[MAX_BOARD];
  int right_corner[MAX_BOARD];
  int corner[BOARDMAX];
  int left_corners = 0, right_corners = 0;
  int corners = 0;
  int top_row, bottom_row;
  int color = board[pos];
  int other = OTHER_COLOR(color);
  int gi = 0;
  int gj = 0;
  int stones = 0;
  int found_some;
  
  signed char mf[BOARDMAX]; /* friendly dragon  */
  signed char mn[BOARDMAX]; /* neighbor dragons */
  int  sd[BOARDMAX]; /* distances to the goal */
  
  if (DRAGON2(pos).hostile_neighbors == 0)
    return(0);
  
  memset(mf, 0, sizeof(mf));
  memset(mn, 0, sizeof(mn));
  memset(sd, 0, sizeof(sd));
  
  mark_dragon(pos, mf, 1);

  /* mark hostile neighbors */

  for (k = 0; k < DRAGON2(pos).neighbors; k++) {
    int nd = DRAGON(DRAGON2(pos).adjacent[k]).origin;
    
    if (board[nd] != color) {
      if (0)
	gprintf("neighbor: %1m\n", nd);
      mark_dragon(nd, mn, 1);
    }
  }

  /* descend markings from stones lying on the 2nd and third lines */

  for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++)
    if (ON_BOARD(dpos) && mn[dpos]) {
      for (k = 0; k < 4; k++) {
        int d = delta[k];
        if (!ON_BOARD(dpos + d))
          continue;
        if (!ON_BOARD(dpos + 2*d)) {
          if (board[dpos + d] == EMPTY)
            mn[dpos + d] = 1;
        }
        else if (!ON_BOARD(dpos + 3*d)) {
          if (board[dpos + d] == EMPTY
              && board[dpos + 2*d] == EMPTY)
            mn[dpos + 2*d] = 1;
        }
      }
    }

  /* compute minimum distances to the goal */

  for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++)
    if (ON_BOARD(dpos) && mn[dpos]) 
      sd[dpos] = goal_dist(dpos, mf);

  /* revise markings */

  do {
    found_some = 0;
    for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++)
      if (ON_BOARD(dpos) && mn[dpos] && sd[dpos] > 8) {
        /* discard markings if we can find 2 stones
         * that verify :
         * - it is closer to the goal than we are
         * - it is closer to us than the goal is
         * - they are closer to each other than we are to the goal
         */
        for (i = BOARDMIN; i < BOARDMAX; i++)
	  if (ON_BOARD(i) && mn[i] && i != dpos
              && sd[i] < sd[dpos]
              && square_dist(i, dpos) < sd[dpos]) {
            for (j = i + 1; j < BOARDMAX; j++)
	      if (ON_BOARD(j) && mn[j] && j != dpos
                  && sd[j] < sd[dpos]
                  && square_dist(j, dpos) < sd[dpos]
                  && square_dist(i, j) < sd[dpos]) {
	        mn[dpos] = 0;
                found_some = 1;
                break;
              }
            if (mn[dpos] == 0)
              break;
          }
      }
  } while (found_some);

  /* prepare corner array */

  for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++)
    if (ON_BOARD(dpos) && mn[dpos])
      corner[corners++] = dpos;

  /* compute gravity center of the goal */

  for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++)
    if (ON_BOARD(dpos) && mf[dpos]) {
      gi += I(dpos);
      gj += J(dpos);
      stones++;
    }
  gi /= stones;
  gj /= stones;
  gg = POS(gi, gj);

  /* sort the corner array */

  gg_sort(corner, corners, sizeof(int), compare_angles);

  /* if apos is not NO_MOVE, mark it. */

  if (apos != NO_MOVE) {
    ASSERT_ON_BOARD1(apos);
    mn[apos] = 1;
  }
  
  if (showboard == 1) {
    show_surround_map(mf, mn);
  }

  /* find top row of surrounding polyhedron */
  
  top_row = -1;
  for (m = 0; m < board_size; m++) {
    if (top_row != -1)
      break;
    for (n = 0; n < board_size; n++)
      if (mn[POS(m, n)]) {
	left_corner[0] = POS(m, n);
	top_row = m;
	break;
      }
  }

  /* find bottom row */
  
  bottom_row = -1;
  for (m = board_size - 1; m >= 0; m--) {
    if (bottom_row != -1)
      break;
    for (n = 0; n < board_size; n++)
      if (mn[POS(m, n)]) {
	bottom_row = m;
	break;
      }
  }
  
  /* find the corners on the left side */
  
  for (left_corners = 1; I(left_corner[left_corners-1]) < bottom_row; 
       left_corners++) {
    int best_found = 0;
    float best_slope = 0.;
    int m = I(left_corner[left_corners-1]);
    int n = J(left_corner[left_corners-1]);
    
    for (i = m + 1; i <= bottom_row; i++)
      for (j = 0; j < board_size; j++)
	if (mn[POS(i, j)]) {
	  float slope = ((float) (j - n))/((float) (i - m));
	  if (0)
	    gprintf("(left) at %m, last %m, slope=%f\n", i, j, m, n, slope);
	  
	  if (!best_found || slope < best_slope) {
	    best_found = POS(i, j);
	    best_slope = slope;
	  }
	}
    ASSERT_ON_BOARD1(best_found);
    left_corner[left_corners] = best_found;
  }
  
  for (n = board_size-1; n >= 0; n--)
    if (mn[POS(top_row, n)]) {
      right_corner[0] = POS(top_row, n);
      break;
    }
  
  /* find the corners on the right side */
  
  for (right_corners = 1; I(right_corner[right_corners-1]) < bottom_row; 
       right_corners++) {
    int best_found = 0;
    float best_slope = 0.;
    int m = I(right_corner[right_corners-1]);
    int n = J(right_corner[right_corners-1]);
    
    for (i = m + 1; i <= bottom_row; i++) {
      for (j = board_size - 1; j >= 0; j--) {
	if (mn[POS(i, j)]) {
	  float slope = ((float) (j - n))/((float) (i - m));
	  if (0)
	    gprintf("(right) at %m, last %m, slope=%f\n", i, j, m, n, slope);
	  if (!best_found || slope > best_slope) {
	    best_found = POS(i, j);
	    best_slope = slope;
	  }
	}
      }
    }
    ASSERT_ON_BOARD1(best_found);
    right_corner[right_corners] = best_found;
  }
  
  if (0) {
    for (k = 0; k < left_corners; k++)
      gprintf("left corner %d: %1m\n", k, left_corner[k]);
    
    for (k = 0; k < right_corners; k++)
      gprintf("right corner %d: %1m\n", k, right_corner[k]);
  }

  /* Now mark the interior of the convex hull */
  
  for (n = J(left_corner[0]); n <= J(right_corner[0]); n++)
    mn[POS(top_row, n)] = 1;

  for (n = J(left_corner[left_corners-1]); 
       n <= J(right_corner[right_corners-1]); n++)
    mn[POS(bottom_row, n)] = 1;

  for (m = top_row+1; m < bottom_row; m++) {
    int left_boundary = -1, right_boundary = -1;
    for (k = 1; k < left_corners; k++) {
      if (I(left_corner[k]) > m) {
	float ti = I(left_corner[k-1]);
	float tj = J(left_corner[k-1]);
	float bi = I(left_corner[k]);
	float bj = J(left_corner[k]);
	
	if (0)
	  gprintf("(left) %d: %1m %1m\n", 
		  m, left_corner[k-1], left_corner[k]);
	/* left edge in this row is on segment (ti,tj) -> (bi, bj) */
	
	/* FIXME: Rewrite this to avoid floating point arithmetic */
	left_boundary = ceil(tj + (m - ti) * (bj - tj) / (bi - ti));
	break;
      }
    }

    for (k = 1; k < right_corners; k++) {
      if (I(right_corner[k]) > m) {
	float ti = I(right_corner[k-1]);
	float tj = J(right_corner[k-1]);
	float bi = I(right_corner[k]);
	float bj = J(right_corner[k]);
	
	if (0)
	  gprintf("(right) %d: %1m %1m\n", 
		  m, right_corner[k-1], right_corner[k]);

	/* FIXME: Rewrite this to avoid floating point arithmetic */
	right_boundary = floor(tj + (m - ti) * (bj - tj) / (bi - ti));
	break;
      }
    }

    for (n = left_boundary; n <= right_boundary; n++)
      mn[POS(m, n)] = 1;
  }
  
  /* mark the expanded region */

  for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++)
    if (ON_BOARD(dpos) && mn[dpos] == 1)
      for (k = 0; k < 4; k++)
	if (ON_BOARD(dpos + delta[k]) && !mn[dpos + delta[k]])
	  mn[dpos + delta[k]] = 2;
      
  /* Mark allied dragons that intersect the (unexpanded) hull.
   * These must all lie entirely within the hull for the
   * dragon to be considered surrounded. 
   *
   * Only neighbor dragons are considered since dragons that
   * are not neighbors are less likely to be helpful.
   */

  for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++) {
    int mpos;
    if (ON_BOARD(dpos) 
	&& mn[dpos] == 1
	&& board[dpos] == color
	&& are_neighbor_dragons(pos, dpos)
	&& !mf[dpos]) {

      for (mpos = BOARDMIN; mpos < BOARDMAX; mpos++)
	if (ON_BOARD(mpos) && is_same_dragon(mpos, dpos))
	  mf[mpos] = 2;
    }
    /* A special case
     *
     *  . X X .
     *  X O . X
     *  X . O O
     *  . O . .
     *
     * The O stone hasn't been amalgamated and the surround computations
     * might think this single stone dragon is surrounded, which in turn
     * can generate overvaluation of moves around this stone.
     * Consequently, we allow inclusion of the stones at kosumi distance
     * in the mf (friendly) array.
     */
    if (ON_BOARD(dpos) 
	&& mn[dpos] == 2
	&& board[dpos] == color
	&& are_neighbor_dragons(pos, dpos)
	&& !mf[dpos]) {
      for (k = 4; k < 8; k++)
	if (ON_BOARD(dpos + delta[k]) && board[dpos + delta[k]] == color
	    && mn[dpos + delta[k]] == 1
	    && board[dpos + delta[k-4]] == EMPTY
	    && board[dpos + delta[(k-3)%4]] == EMPTY) {
	  for (mpos = BOARDMIN; mpos < BOARDMAX; mpos++)
	    if (ON_BOARD(mpos) && is_same_dragon(mpos, dpos))
	      mf[mpos] = 2;
	}
    }
  }

  /* determine the surround status of the dragon */

  surrounded = SURROUNDED;

  /* Compute the maximum surround status awarded
   * If distances between enclosing stones are large, reduce to
   * WEAKLY_SURROUNDED. If (really) too large, then reduce to 0
   * FIXME: constants chosen completely ad hoc. Possibly better tunings
   *        can be found.
   */

  for (k = 0; k < corners - 1; k++) {
    if (is_edge_vertex(corner[k])
        && is_edge_vertex(corner[k+1]))
      continue;
    if (square_dist(corner[k], corner[k+1]) > 60) {
      surrounded = 0;
      break;
    }
    else if (square_dist(corner[k], corner[k+1]) > 27)
      surrounded = WEAKLY_SURROUNDED;
  }
  if (surrounded
      && (!is_edge_vertex(corner[0])
          || !is_edge_vertex(corner[corners-1]))) {
    if (square_dist(corner[0], corner[corners-1]) > 60)
      surrounded = 0;
    else if (square_dist(corner[0], corner[corners-1]) > 27)
      surrounded = WEAKLY_SURROUNDED;
  }

  if (surrounded)
    for (dpos = BOARDMIN; dpos < BOARDMAX; dpos++)
      if (mf[dpos]) {
	if (mn[dpos] == 0) {
	  surrounded = 0;
	  break;
	}
	else if (mn[dpos] == 2)
	  surrounded = WEAKLY_SURROUNDED;
      }

  /* revise the status for single stone dragons. */

  if (stones == 1
      && surrounded == WEAKLY_SURROUNDED
      && mn[pos] == 2)
    surrounded = 0;
      
  /* revise the status if an ikken tobi jumps out. */

  if (surrounded) {
    for (dpos = BOARDMIN; dpos < BOARDMAX && surrounded; dpos++) {
      if (!ON_BOARD(dpos) || !mf[dpos])
	continue;

      for (k = 0; k < 4; k++) {
	int up = delta[k];
	int right = delta[(k + 1) % 4];
	if (board[dpos + up] == EMPTY
	    && board[dpos + 2*up] == color
	    && mn[dpos + 2*up] != 1
	    && ON_BOARD(dpos + up + right)
	    && board[dpos + up + right] != other
	    && ON_BOARD(dpos + up - right)
	    && board[dpos + up - right] != other) {
	  surrounded = 0;
	  break;
	}
      }
    }
  }

  if (showboard == 1 || (showboard == 2 && surrounded)) {
    show_surround_map(mf, mn);
  }

  if (!apos && surrounded && surround_pointer < MAX_SURROUND) {
    memcpy(surroundings[surround_pointer].surround_map, mn, sizeof(mn));
    surroundings[surround_pointer].dragon_number = dragon[pos].id;
    surround_pointer++;
  }

  if (surround_size) {
    int pos;

    *surround_size = 0;
    for (pos = BOARDMIN; pos < BOARDMAX; pos++)
      if (ON_BOARD(pos) && mn[pos] == 1)
	(*surround_size)++;
  }

  return surrounded;
}
예제 #18
0
/* Computes the active area for the current board position and the
 * read result that has just been stored in *entry.
 */
static void
compute_active_breakin_area(struct persistent_cache_entry *entry,
			    const char breakin_shadow[BOARDMAX], int dummy)
{
  int pos;
  int k, r;
  signed char active[BOARDMAX];
  int other = OTHER_COLOR(board[entry->apos]);
  UNUSED(dummy);

  /* We let the active area be
   * the string to connect +
   * the breakin shadow (which contains the goal) +
   * distance two expansion through empty intersections and own stones +
   * adjacent opponent strings +
   * liberties and neighbors of adjacent opponent strings with less than
   * five liberties +
   * liberties and neighbors of low liberty neighbors of adjacent opponent
   * strings with less than five liberties.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++)
    active[pos] = breakin_shadow[pos];

  signed_mark_string(entry->apos, active, 1);

  /* To be safe, also add the successful move. */
  if (entry->result != 0 && entry->move != 0)
    active[entry->move] = 1;

  /* Distance two expansion through empty intersections and own stones. */
  for (k = 1; k < 3; k++) {
    for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
      if (!ON_BOARD(pos) || board[pos] == other || active[pos] != 0) 
	continue;
      if ((ON_BOARD(SOUTH(pos)) && active[SOUTH(pos)] == k)
	  || (ON_BOARD(WEST(pos)) && active[WEST(pos)] == k)
	  || (ON_BOARD(NORTH(pos)) && active[NORTH(pos)] == k)
	  || (ON_BOARD(EAST(pos)) && active[EAST(pos)] == k)) {
	if (board[pos] == EMPTY)
	  active[pos] = k + 1;
	else
	  signed_mark_string(pos, active, (signed char) (k + 1));
      }
    }
  }
  
  /* Adjacent opponent strings. */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] != other || active[pos] != 0) 
      continue;
    for (r = 0; r < 4; r++) {
      int pos2 = pos + delta[r];
      if (ON_BOARD(pos2)
	  && board[pos2] != other
	  && active[pos2] && active[pos2] <= 2) {
	signed_mark_string(pos, active, 1);
	break;
      }
    }
  }
  
  /* Liberties of adjacent opponent strings with less than four liberties +
   * liberties of low liberty neighbors of adjacent opponent strings
   * with less than five liberties.
   */
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    if (board[pos] == other && active[pos] > 0 && countlib(pos) < 4) {
      int libs[4];
      int liberties = findlib(pos, 3, libs);
      int adjs[MAXCHAIN];
      int adj;
      for (r = 0; r < liberties; r++)
	active[libs[r]] = 1;
      
      /* Also add liberties of neighbor strings if these are three
       * or less.
       */
      adj = chainlinks(pos, adjs);
      for (r = 0; r < adj; r++) {
	signed_mark_string(adjs[r], active, -1);
	if (countlib(adjs[r]) <= 3) {
	  int s;
	  int adjs2[MAXCHAIN];
	  int adj2;
	  liberties = findlib(adjs[r], 3, libs);
	  for (s = 0; s < liberties; s++)
	    active[libs[s]] = 1;
	  adj2 = chainlinks(pos, adjs2);
	  for (s = 0; s < adj2; s++)
	    signed_mark_string(adjs2[s], active, -1);
	}
      }
    }
  }
  
  for (pos = BOARDMIN; pos < BOARDMAX; pos++) {
    char value = board[pos];
    if (!ON_BOARD(pos))
      continue;
    if (!active[pos])
      value = GRAY;
    else if (IS_STONE(board[pos]) && countlib(pos) > 3 && active[pos] > 0)
      value |= HIGH_LIBERTY_BIT2;
    
    entry->board[pos] = value;
  }
}