/**
* @brief Restore a board.
*
* Restore a board by un-flipping its discs and restoring every other data,
* according to the 'move' description, in order to cancel a update_move.
*
* @param board board to restore.
* @param move a Move structure describing the modification.
*/
void restore(Board board, Move move)
{
swap_players(board);
board.player ^= (move.flipped | Bit.X_TO_BIT[move.x]);
board.opponent ^= move.flipped;
check(board);
}
/**
* @brief Compute a board resulting of an opponent move played on a previous board.
*
* Compute the board after passing and playing a move.
*
* @param board board to play the move on.
* @param x opponent move to play.
* @param next resulting board.
* @return flipped discs.
*/
ulong pass_next(int x, Board next)
{
const ulong flipped = flip[x](board.opponent, board.player);
next.opponent = board.opponent ^ (flipped | Bit.X_TO_BIT[x]);
next.player = board.player ^ flipped;
return flipped;
}
/**
* @brief Compute a board resulting of a move played on a previous board.
*
* @param board board to play the move on.
* @param x move to play.
* @param next resulting board.
* @return flipped discs.
*/
ulong next(int x, Board next)
{
const ulong flipped = flip[x](board.player, board.opponent);
const ulong player = board.opponent ^ flipped;
next.opponent = board.player ^ (flipped | Bit.X_TO_BIT[x]);
next.player = player;
return flipped;
}
/**
* @brief Compare two board for equality
*
* @param b1 first board
* @param b2 second board
* @return true if both board are equal
*/
static bool equal(Board b1, Board b2)
{
return (b1.player == b2.player && b1.opponent == b2.opponent);
}
/**
* @brief Compare two board
*
* @param b1 first board
* @param b2 second board
* @return -1, 0, 1
*/
static int compare(Board b1, Board b2)
{
if (b1.player > b2.player) return 1;
else if (b1.player < b2.player) return -1;
else if (b1.opponent > b2.opponent) return 1;
else if (b1.opponent < b2.opponent) return -1;
else return 0;
}
/**
* @brief unique board
*
* Compute a board unique from all its possible symertries.
*
* @param board input board
* @param unique output board
*/
public int unique(Board unique)
{
Board sym;
int i, s = 0;
unique = new Board(player, opponent);
for (i = 1; i < 8; ++i) {
sym = symetry(i);
if (compare(sym, unique) < 0) {
unique = sym;
s = i;
}
}
return s;
}
