public HashEntry(UInt64 key, Move move, int score, int searchDepth, HashEntryTypes type)
{
HashKey = key;
Move = move;
Score = score;
SearchDepth = searchDepth;
Type = type;
IsStale = false;
}
public HashEntryTypes LookupPosition(Board board, int desiredDepth, int currentPly, Sides currentSide, ref int alpha, ref int beta)
{
UInt64 hashKey = currentSide == Sides.White ? board.HashKey : ~board.HashKey;
HashEntryTypes result = LookupPosition(_GlobalTable, hashKey, desiredDepth, currentPly, currentSide, ref alpha, ref beta);
if (result == HashEntryTypes.Junk)
{
result = LookupPosition(_LocalTable, hashKey, desiredDepth, currentPly, currentSide, ref alpha, ref beta);
}
return(result);
}
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);
}
}
}
}