private static void PrintSearchResult(GameState state, DateTime startTime, AlphaBeta ab, int i, int score)
{
Console.Write("{0}\t{1}\t{2:0}\t{3}\t", i, score,
(DateTime.Now - startTime).TotalMilliseconds / 10, ab.Metrics.Nodes);
PrintPV(state.GameBoard, ab);
Console.WriteLine();
}
private static void PrintPV(Board b, AlphaBeta ab)
{
for (int j = 0; j < ab.PvLength[0]; j++)
{
var m = ab.PrincipalVariation[0, j];
Console.Write("{0} ", m.ToAlegbraicNotation(b));
b.MakeMove(m);
}
//Walk through the TT table to augment the PV
int hashTableMoves = 0;
List <ulong> hashKeys = new List <ulong>();
while (true)
{
//don't let the hashtable send us into a cycle
if (hashKeys.Contains(b.HashKey))
{
break;
}
var entry = TranspositionTable.Instance.Read(b.HashKey);
if (entry == null || entry.Type != (byte)TranspositionTableEntry.EntryType.PV)
{
break;
}
var m = new Move(entry.MoveValue);
Console.Write("{0}(HT) ", m.ToAlegbraicNotation(b));
if (!b.MakeMove(m))
{
throw new Exception("invalid move from HT!");
}
hashTableMoves++;
hashKeys.Add(b.HashKey);
}
while (hashTableMoves-- > 0)
{
b.UnMakeMove();
}
for (int j = ab.PvLength[0] - 1; j >= 0; j--)
{
b.UnMakeMove();
}
}
public static Move DoIterate(GameState state, Action interrupt)
{
state.TimeUp = false;
var startTime = DateTime.Now;
var timeLimit = GetThinkTimeSpan(state);
AlphaBeta ab = new AlphaBeta(state, () =>
{
if ((DateTime.Now - startTime) > timeLimit)
{
state.TimeUp = true;
}
interrupt();
});
//increment transposition table search Id
TranspositionTable.Instance.NextSearchId();
int alpha = -10000;
int beta = 10000;
Move bestMove = null;
//Console.WriteLine("Ply\tScore\tMillis\tNodes\tPV");
ab.Metrics.Depth = 0;
for (int i = 0; i < AlphaBeta.MAX_DEPTH && !state.TimeUp; i++)
{
int score;
int alphaRelax = 1, betaRelax = 1;
if (i > 0)
{
beta = alpha + 33;
alpha = alpha - 33;
}
do
{
score = ab.SearchRoot(alpha, beta, i);
bestMove = ab.PrincipalVariation[0, 0];
if (!state.TimeUp)
{
PrintSearchResult(state, startTime, ab, i, score);
}
if (score > alpha && score < beta)
{
alpha = score;
break;
}
else if (score >= beta)
{
if (score == 10000)
{
break;
}
beta = Math.Min(10000, beta + (33 * betaRelax));
betaRelax *= 4;
}
else if (score <= alpha)
{
if (score == -10000)
{
break;
}
alpha = Math.Max(-10000, alpha - (33 * alphaRelax));
alphaRelax *= 4;
}
} while (!state.TimeUp); //keep searching for a PV move until time is up
if (!state.TimeUp)
{
ab.Metrics.DepthNodes[i] = ab.Metrics.Nodes;
ab.Metrics.Depth = i;
}
if (Math.Abs(score) > 9900) // stop if we have found mate
{
break;
}
}
PrintMetrics(ab.Metrics, DateTime.Now - startTime);
return(bestMove);
}