public Brain(StaticEvaluator staticEvaluator)
{
_StaticEvaluator = staticEvaluator;
for (int i = 0; i < _PlyInfo.Length; i++)
{
_PlyInfo[i] = new PlyInfo();
}
}
public void AddPosition(Board board, Move bestMove, int score, int searchDepth, int currentPly, Sides currentSide, HashEntryTypes type)
{
score = StaticEvaluator.RemovePlyDependence(score);
UInt64 hashKey = currentSide == Sides.White ? board.HashKey : ~board.HashKey;
UInt64 globalTableIndex = hashKey % (UInt64)_GlobalTable.Length;
UInt64 localTableIndex = hashKey % (UInt64)_LocalTable.Length;
HashEntry globalEntry = _GlobalTable[globalTableIndex];
if (globalEntry.IsStale)
{
_GlobalTable[globalTableIndex] = new HashEntry(hashKey, bestMove, score, searchDepth, type);
}
else
{
bool isMoreValuable = searchDepth > globalEntry.SearchDepth ||
searchDepth == globalEntry.SearchDepth && type == HashEntryTypes.Exact;
if (globalEntry.HashKey == hashKey)
{
bool improvesBound = searchDepth == globalEntry.SearchDepth &&
(type == HashEntryTypes.LowerBound && globalEntry.Type == HashEntryTypes.LowerBound && score > globalEntry.Score ||
type == HashEntryTypes.UpperBound && globalEntry.Type == HashEntryTypes.LowerBound && score < globalEntry.Score);
if (isMoreValuable || improvesBound)
{
_GlobalTable[globalTableIndex] = new HashEntry(hashKey, bestMove, score, searchDepth, type);
}
}
else
{
if (isMoreValuable)
{
_GlobalTable[globalTableIndex] = new HashEntry(hashKey, bestMove, score, searchDepth, type);
_LocalTable[localTableIndex] = globalEntry;
}
else
{
_LocalTable[localTableIndex] = new HashEntry(hashKey, bestMove, score, searchDepth, type);
}
}
}
}
HashEntryTypes LookupPosition(HashEntry[] table, UInt64 hashKey, int desiredDepth, int currentPly, Sides currentSide, ref int alpha, ref int beta)
{
UInt64 tableIndex = hashKey % (UInt64)table.Length;
if (table[tableIndex].HashKey == hashKey)
{
table[tableIndex].IsStale = false;
int score = StaticEvaluator.AddPlyDependence(table[tableIndex].Score, currentPly);
if (table[tableIndex].SearchDepth < desiredDepth)
{
return(HashEntryTypes.Junk);
}
switch (table[tableIndex].Type)
{
case HashEntryTypes.LowerBound:
if (score >= beta)
{
beta = score;
return(HashEntryTypes.LowerBound);
}
break;
case HashEntryTypes.Exact:
alpha = score;
return(HashEntryTypes.Exact);
case HashEntryTypes.UpperBound:
if (score <= alpha)
{
alpha = score;
return(HashEntryTypes.UpperBound);
}
break;
}
}
return(HashEntryTypes.Junk);
}
protected override void AnalyzeOurBoard()
{
_NodesEvaluated = 0;
_TranspositionTable.SetStale();
int depth = 2;
int score = 0;
while (true)
{
score = Search(depth, score);
if (!_AreWeThinking)
{
break;
}
_Score = score;
_BestMove = _PlyInfo[0].PrincipalVariation[0];
_PrincipalVariation.Clear();
for (int i = 0; i < _PlyInfo[0].PrincipalVariationLength; i++)
{
_PrincipalVariation.Add(_PlyInfo[0].PrincipalVariation[i]);
}
ReportSearchInformation(depth);
if (StaticEvaluator.IsMate(_Score))
{
break;
}
StuffPrincipalVariationIntoTranspositionTable(0, _OurSide, depth);
depth++;
}
}
protected int AlphaBetaSearch(int alpha, int beta, int remainingDepth, int currentPly, Sides currentSide)
{
_NodesEvaluated++;
_PlyInfo[currentPly].PrincipalVariationLength = currentPly;
if (currentPly >= PlyInfo.MaxPly)
{
return(beta);
}
switch (_TranspositionTable.LookupPosition(_ScratchBoard, remainingDepth, currentPly, currentSide, ref alpha, ref beta))
{
case HashEntryTypes.LowerBound:
return(beta);
case HashEntryTypes.Exact:
Move transpositionTableMove = _TranspositionTable.GetBestMove(_ScratchBoard, currentSide);
if (!transpositionTableMove.Equals(Move.Empty))
{
UpdatePrincipalVariation(transpositionTableMove, currentPly);
}
return(alpha);
case HashEntryTypes.UpperBound:
return(alpha);
}
if (remainingDepth <= 0)
{
return(QuiescenceSearch(alpha, beta, currentPly, currentSide));
}
int pruneScore;
if (CanPrune(alpha, beta, remainingDepth, currentPly, currentSide, out pruneScore))
{
return(pruneScore);
}
List <Move> moves;
if (GenerateMoves(currentPly, currentSide, out moves) == MoveGenerationResults.Mated)
{
int mateScore = -StaticEvaluator.MateScoreFromPly(currentPly);
_TranspositionTable.AddPosition(_ScratchBoard, Move.Empty,
mateScore, remainingDepth, currentPly, currentSide, HashEntryTypes.Exact);
return(mateScore);
}
_PlyInfo[currentPly].Board.CopyFrom(_ScratchBoard);
int originalAlpha = alpha;
foreach (Move move in moves)
{
if (!_AreWeThinking)
{
return(alpha);
}
if (_ScratchBoard.MakeMove(move) == MakeMoveResults.UndoMove)
{
UndoMove(currentPly);
continue;
}
int score = -AlphaBetaSearch(-beta, -alpha, remainingDepth - 1, currentPly + 1, Board.OtherSide(currentSide));
UndoMove(currentPly);
if (score >= beta)
{
SetKiller(move, currentPly);
_TranspositionTable.AddPosition(_ScratchBoard, move, score,
remainingDepth, currentPly, currentSide, HashEntryTypes.LowerBound);
return(score);
}
if (score > alpha)
{
alpha = score;
UpdatePrincipalVariation(move, currentPly);
}
}
if (alpha == originalAlpha)
{
_TranspositionTable.AddPosition(_ScratchBoard, Move.Empty,
alpha, remainingDepth, currentPly, currentSide, HashEntryTypes.UpperBound);
}
else
{
SetKiller(_PlyInfo[currentPly].PrincipalVariation[currentPly], currentPly);
_TranspositionTable.AddPosition(_ScratchBoard, _PlyInfo[currentPly].PrincipalVariation[currentPly],
alpha, remainingDepth, currentPly, currentSide, HashEntryTypes.Exact);
}
return(alpha);
}
public BasicAlphaBetaBrain(StaticEvaluator staticEvaluator, int memoryCapacity_MB)
: base(staticEvaluator, memoryCapacity_MB)
{
}
public NullMoveBrain(StaticEvaluator staticEvaluator, int memoryCapacity_MB)
: base(staticEvaluator, memoryCapacity_MB)
{
}
public MTDfBrain(StaticEvaluator staticEvaluator, int memoryCapacity_MB)
: base(staticEvaluator, memoryCapacity_MB)
{
}
public TranspositionTableBrain(StaticEvaluator staticEvaluator, int memoryCapacity_MB)
: base(staticEvaluator)
{
_TranspositionTable = new TranspositionTable(memoryCapacity_MB * 1024 * 1024);
}