public int SearchBestMove(byte depth, Dot player, float alpha, float beta)
{
int bestMove = 0;
var moves = MoveGenerator.GenerateMoves(player);
Dot nextPlayer = player.NextPlayer();
foreach (var move in moves)
{
if (alpha < beta)
{
if (Field.MakeMove(move))
{
HashField.UpdateHash();
float tmp = -EvaluatePosition((byte)(depth - 1), nextPlayer, -beta, -alpha, HashField.Key,
MoveGenerator.GenerateMoves(nextPlayer, moves));
Field.UnmakeMove();
HashField.UpdateHash();
if (tmp > alpha)
{
alpha = tmp;
bestMove = move;
}
}
}
}
return(bestMove);
}
private unsafe float EvaluatePosition(byte depth, Dot player, float alpha, float beta, ulong key, HashSet <int> moves)
{
float oldAlpha = alpha;
Dot nextPlayer = player.NextPlayer();
float score = CheckCollision(player, depth, alpha, beta, key, moves);
if (score >= 0)
{
return(score);
}
if (depth == 0)
{
return(Estimator.Estimate(player));
}
foreach (var move in moves)
{
if (Field.MakeMove(move))
{
HashField.UpdateHash();
float tmp = -EvaluatePosition((byte)(depth - 1), nextPlayer, -beta, -alpha, HashField.Key,
MoveGenerator.GenerateMoves(nextPlayer, moves));
Field.UnmakeMove();
HashField.UpdateHash();
if (tmp > alpha)
{
TranspositionTable.RecordHash(
(byte)depth, tmp, tmp < beta ? enmHashEntryType.Exact : enmHashEntryType.Beta, HashField.Key, (ushort)move);
alpha = tmp;
if (alpha >= beta)
{
return(beta);
}
}
}
}
if (alpha == oldAlpha)
{
TranspositionTable.RecordHash((byte)depth, alpha, enmHashEntryType.Alpha, HashField.Key, 0);
}
return(alpha);
}
private unsafe float CheckCollision(Dot player, byte depth, float alpha, float beta, ulong key, HashSet <int> moves)
{
fixed(HashEntry *hashEntry = &TranspositionTable.HashEntries_[key % AiSettings.HashTableSize])
{
if (hashEntry->HashKey == key)
{
if (hashEntry->Depth >= depth)
{
float score = hashEntry->Score;
if (hashEntry->Type == enmHashEntryType.Alpha)
{
if (score <= alpha)
{
return(alpha);
}
/*if (score < beta)
* beta = score;
* if (beta <= alpha)
* return alpha;*/
}
else
{
if (score > alpha)
{
alpha = score;
}
if (alpha >= beta)
{
return(beta);
}
}
}
if (hashEntry->Type != enmHashEntryType.Alpha && depth != 0)
{
if (Field.MakeMove(hashEntry->BestMove))
{
HashField.UpdateHash();
float tmp = -EvaluatePosition((byte)(depth - 1), player.NextPlayer(), -beta, -alpha, HashField.Key,
MoveGenerator.GenerateMoves(player.NextPlayer(), moves));
Field.UnmakeMove();
HashField.UpdateHash();
if (tmp > alpha)
{
TranspositionTable.RecordHash(depth, tmp,
tmp < beta ? enmHashEntryType.Exact : enmHashEntryType.Beta,
key, hashEntry->BestMove);
alpha = tmp;
if (alpha >= beta)
{
return(beta);
}
}
}
}
}
}
return(-1);
}