protected static Hashcode nextZobrist()
{
#if CryptoServiceProvider
ZobristRNG.GetBytes(ZobristBuffer);
#else
ZobristRandom.NextBytes(ZobristBuffer);
#endif
var qHash = BitConverter.ToUInt64(ZobristBuffer, 0);
#if TestZobrist
Zobrists.Add(qHash);
#endif
return(qHash);
}
protected static void loadZobrist()
{
ZobristTurn = nextZobrist();
// For En Passant File:
for (var n = 0; n < ZobristFile.Length; n++)
{
ZobristFile[n] = nextZobrist();
}
// For Castling Abilities:
for (var n = 0; n < ZobristRights.Length; n++)
{
ZobristRights[n] = nextZobrist();
}
// For Pieces that can be held by each Square:
for (var nPiece = 0; nPiece < nPieces; nPiece++)
{
var bPawn = nPiece == vP6; //[Speed]Pawns cannot appear on their First or Last Rank:
var nMin = (Int32)(bPawn ? sq.a2 : sq.a1);
var nMax = (Int32)(bPawn ? sq.h7 : sq.h8);
for (var n = nMin; n <= nMax; n++)
{
// White Piece:
ZobristWhite[nPiece][n] = nextZobrist();
// Black Piece:
ZobristBlack[nPiece][n] = nextZobrist();
}
}
// Distinguish actual Draws as well as Draw2:
for (var n = 0; n < ZobristDraw.Length; n++)
{
ZobristDraw[n] = nextZobrist();
}
// For Excluded Moves
for (var n = 0; n < nSquares; n++)
{
ZobristExcludedFrom[n] = nextZobrist();
ZobristExcludedTo[n] = nextZobrist();
}
for (var n = 0; n < ZobristExcludedPromotion.Length; n++)
{
ZobristExcludedPromotion[n] = nextZobrist();
}
ZobristExcludedCastles = nextZobrist();
#if RNGStatistics
var nCount = Zobrists.Count;
var decSum = 0M;
LogLine($"\nHashcodes = {Zobrists.Count}");
foreach (var qHash in Zobrists)
{
decSum += qHash;
#if DumpZobrist
LogLine(formatHash(qHash));
#endif
}
var dMean = (Double)decSum / nCount;
var dRange = Pow(2, 64);
var dMeanIdeal = dRange / 2;
var dMeanError = dMean / dMeanIdeal - 1;
LogLine($"Mean = {dMean:e} {100 * dMeanError:n2}%");
if (nCount > 1)
{
var dSquareSum = 0.0;
foreach (var qHash in Zobrists)
{
var dDelta = qHash - dMean;
dSquareSum += dDelta * dDelta;
}
var dVariance = dSquareSum / (nCount - 1);
var dDeviation = Sqrt(dVariance);
var dDeviationIdeal = dRange / Sqrt(12.0);
var dDeviationError = dDeviation / dDeviationIdeal - 1;
LogLine($"s.d. = {dDeviation:e} {100 * dDeviationError:n2}%");
}
#endif
#if TestZobrist
Zobrists.Sort();
var qLastCode = default(Hashcode);
foreach (var qHash in Zobrists)
{
if (qHash == qLastCode)
{
Trace.Assert(qHash != qLastCode, "Duplicate Hashcode Found");
break;
}
qLastCode = qHash;
}
#endif
}