c# - 如何在 VB.NET 中实现 Bitboard？

Question

我的问题是:

是否可以实现 bitboard在 vb.net 中？

在 VB 中做位板的任何教程/引用资料？

C# 答案是可以接受的，因为它并不难翻译。

Answer 1

要在 VB(或 C#)中实现位板，请使用 System.UInt64 .这可以容纳 64 位，国际象棋棋盘的每个方格 1 位。这种值类型适用于许多快速的按位运算。我不建议使用另一张海报推荐的 BitArray，因为它太慢了。任何体面的国际象棋引擎的基本要求之一是速度。

要回答您的第二个问题，这是 good bitboard tutorial .

以下是我自己的 C# 国际象棋引擎中的一些示例。正如您从代码中看到的那样，使用位板可能需要一段时间才能理解，但它们通常非常快，尤其是对于位置评估。

示例 1 - 位板定义:

internal UInt64 WhiteKing;
internal UInt64 WhiteQueens;
internal UInt64 WhiteRooks;
internal UInt64 WhiteBishops;
internal UInt64 WhiteKnights;
internal UInt64 WhitePawns;
internal UInt64 WhitePieces;

示例 2 - 位板初始化:

// Initialise piece bitboards using square contents.
private void InitPieceBitboards()
{
    this.WhiteKing = 0; 
    this.WhiteQueens = 0; 
    this.WhiteRooks = 0; 
    this.WhiteBishops = 0; 
    this.WhiteKnights = 0; 
    this.WhitePawns = 0;

    for (Int16 i = 0; i < 64; i++)
    {
        if (this.Squares[i] == Constants.WHITE_KING)
        {
            this.WhiteKing = this.WhiteKing | Constants.BITSET[i];
        }
        if (this.Squares[i] == Constants.WHITE_QUEEN)
        {
            this.WhiteQueens = this.WhiteQueens | Constants.BITSET[i];
        } 
        if (this.Squares[i] == Constants.WHITE_ROOK) 
        {
            this.WhiteRooks = this.WhiteRooks | Constants.BITSET[i];
        }
        if (this.Squares[i] == Constants.WHITE_BISHOP) 
        {
            this.WhiteBishops = this.WhiteBishops | Constants.BITSET[i];
        }
        if (this.Squares[i] == Constants.WHITE_KNIGHT) 
        {
            this.WhiteKnights = this.WhiteKnights | Constants.BITSET[i];
        }
        if (this.Squares[i] == Constants.WHITE_PAWN) 
        {
            this.WhitePawns = this.WhitePawns | Constants.BITSET[i];
        }

        this.WhitePieces = this.WhiteKing | this.WhiteQueens | 
                           this.WhiteRooks | this.WhiteBishops | 
                           this.WhiteKnights | this.WhitePawns;
        this.BlackPieces = this.BlackKing | this.BlackQueens | 
                           this.BlackRooks | this.BlackBishops | 
                           this.BlackKnights | this.BlackPawns;
        this.SquaresOccupied = this.WhitePieces | this.BlackPieces;
    }
}

示例 3 - 移动生成:

// We can't capture one of our own pieces.
eligibleSquares = ~this.WhitePieces;

// Generate moves for white knights.
remainingKnights = this.WhiteKnights;

// Generate the moves for each knight...
while (remainingKnights != 0)
{
    squareFrom = BitOps.BitScanForward(remainingKnights);
    generatedMoves = Constants.ATTACKS_KNIGHT[squareFrom] & eligibleSquares;
    while (generatedMoves != 0)
    {
        squareTo = BitOps.BitScanForward(generatedMoves);
        moveList.Add(new Move(squareFrom, squareTo, Constants.WHITE_KNIGHT, 
                              this.Squares[squareTo], Constants.EMPTY));
        generatedMoves ^= Constants.BITSET[squareTo];
    }
    // Finished with this knight - move on to the next one.
    remainingKnights ^= Constants.BITSET[squareFrom];
}    

示例 4 - 计算 Material 分数:

// Material score from scratch, in centipawns from White's perspective.
internal static Int32 ScoreMaterial(Board position)
{
    return BitOps.BitCountWegner(position.WhitePawns)   * Constants.VALUE_PAWN +
           BitOps.BitCountWegner(position.WhiteKnights) * Constants.VALUE_KNIGHT +
           BitOps.BitCountWegner(position.WhiteBishops) * Constants.VALUE_BISHOP +
           BitOps.BitCountWegner(position.WhiteRooks)   * Constants.VALUE_ROOK   +
           BitOps.BitCountWegner(position.WhiteQueens)  * Constants.VALUE_QUEEN  -
           BitOps.BitCountWegner(position.BlackPawns)   * Constants.VALUE_PAWN   -
           BitOps.BitCountWegner(position.BlackKnights) * Constants.VALUE_KNIGHT -
           BitOps.BitCountWegner(position.BlackBishops) * Constants.VALUE_BISHOP -
           BitOps.BitCountWegner(position.BlackRooks)   * Constants.VALUE_ROOK   -
           BitOps.BitCountWegner(position.BlackQueens)  * Constants.VALUE_QUEEN;
}

示例 5 - 计算工件移动性:

// Calculate mobility score for white knights.
remainingPieces = position.WhiteKnights;
while (remainingPieces != 0)
{
    squareFrom = BitOps.BitScanForward(remainingPieces);
    mobilityKnight += BitOps.BitCountWegner(Constants.ATTACKS_KNIGHT[squareFrom]
                                            & unoccupiedSquares);
    remainingPieces ^= Constants.BITSET[squareFrom];
 }