public static val qsearch(cPosicion pos, cStackMov[] ss, int ssPos, val alpha, val beta, ply depth, NodeType NT, bool InCheck)
{
bool PvNode = (NT == cTipoNodo.PV);
cPosInfo st = null;
cTablaHashStruct tte;
hash posKey;
mov ttMove, move, bestMove;
val bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha = 0;
bool givesCheck, evasionPrunable;
ply ttDepth;
if (PvNode)
oldAlpha = alpha;
ss[ssPos].currentMove = bestMove = cMovType.MOV_NAN;
ss[ssPos].ply = ss[ssPos - 1].ply + 1;
if (pos.IsTablas() || ss[ssPos].ply > cSearch.MAX_PLY)
return ss[ssPos].ply > cSearch.MAX_PLY && !InCheck ? cEval.Eval(pos) : DrawValue[pos.ColorMueve()];
ttDepth = ((InCheck || depth >= cPly.DEPTH_QS_CHECKS) ? cPly.DEPTH_QS_CHECKS
: cPly.DEPTH_QS_NO_CHECKS);
posKey = pos.ClaveHash();
tte = cMotor.m_TablaHash.Buscar(posKey);
ttMove = (tte != null ? tte.GetMove() : cMovType.MOV_NAN);
ttValue = tte != null ? value_from_tt(tte.GetValue(), ss[ssPos].ply) : cValoresJuego.NAN;
if (tte != null
&& tte.GetDepth() >= ttDepth
&& ttValue != cValoresJuego.NAN
&& (PvNode ? tte.GetBound() == cBordes.BOUND_EXACT
: (ttValue >= beta) ? (tte.GetBound() & cBordes.BOUND_LOWER) != 0
: (tte.GetBound() & cBordes.BOUND_UPPER) != 0))
{
ss[ssPos].currentMove = ttMove;
return ttValue;
}
if (InCheck)
{
ss[ssPos].staticEval = cValoresJuego.NAN;
bestValue = futilityBase = -cValoresJuego.INFINITO;
}
else
{
if (tte != null)
{
if ((ss[ssPos].staticEval = bestValue = tte.GetValueEval()) == cValoresJuego.NAN)
ss[ssPos].staticEval = bestValue = cEval.Eval(pos);
if (ttValue != cValoresJuego.NAN)
if ((tte.GetBound() & (ttValue > bestValue ? cBordes.BOUND_LOWER : cBordes.BOUND_UPPER)) != 0)
bestValue = ttValue;
}
else
ss[ssPos].staticEval = bestValue = cEval.Eval(pos);
if (bestValue >= beta)
{
if (tte == null)
cMotor.m_TablaHash.Save(pos.ClaveHash(), value_to_tt(bestValue, ss[ssPos].ply), cBordes.BOUND_LOWER,
cPly.DEPTH_NONE, cMovType.MOV_NAN, ss[ssPos].staticEval);
return bestValue;
}
if (PvNode && bestValue > alpha)
alpha = bestValue;
futilityBase = bestValue + 128;
}
cMovOrder mp = new cMovOrder(pos, ttMove, depth, History, cTypes.GetToCasilla(ss[ssPos - 1].currentMove));
cInfoJaque ci = new cInfoJaque(pos);
st = new cPosInfo();
while ((move = mp.SiguienteMovimientoEnFalso()) != cMovType.MOV_NAN)
{
givesCheck = cTypes.TipoMovimiento(move) == cMovType.NORMAL && 0 == ci.m_Candidatas
? (ci.m_Jaque[cTypes.TipoPieza(pos.GetPieza(cTypes.GetFromCasilla(move)))] & cBitBoard.m_nCasillas[cTypes.GetToCasilla(move)]) != 0
: pos.IsJaque(move, ci);
if (!PvNode
&& !InCheck
&& !givesCheck
&& move != ttMove
&& futilityBase > -cValoresJuego.GANA
&& !pos.IsPeonAvanzado(move))
{
futilityValue = futilityBase + cPosicion.m_nValPieza[cFaseJuego.FASE_FINAL][pos.GetPieza(cTypes.GetToCasilla(move))];
if (futilityValue < beta)
{
bestValue = Math.Max(bestValue, futilityValue);
continue;
}
if (futilityBase < beta && pos.SEE(move) <= cValoresJuego.CERO)
{
bestValue = Math.Max(bestValue, futilityBase);
continue;
}
}
evasionPrunable = InCheck
&& bestValue > cValoresJuego.MATE_MAXIMO_VS
&& !pos.IsCaptura(move)
&& 0 == pos.CanEnroque(pos.ColorMueve());
if (!PvNode
&& (!InCheck || evasionPrunable)
&& move != ttMove
&& cTypes.TipoMovimiento(move) != cMovType.PROMOCION
&& pos.SEEReducido(move) < cValoresJuego.CERO)
continue;
if (!pos.IsLegalMov(move, ci.m_Clavadas))
continue;
ss[ssPos].currentMove = move;
pos.DoMov(move, st, ci, givesCheck);
value = givesCheck ? -qsearch(pos, ss, ssPos + 1, -beta, -alpha, depth - cPly.ONE_PLY, NT, true)
: -qsearch(pos, ss, ssPos + 1, -beta, -alpha, depth - cPly.ONE_PLY, NT, false);
pos.DesMov(move);
if (value > bestValue)
{
bestValue = value;
if (value > alpha)
{
if (PvNode && value < beta)
{
alpha = value;
bestMove = move;
}
else
{
cMotor.m_TablaHash.Save(posKey, value_to_tt(value, ss[ssPos].ply), cBordes.BOUND_LOWER,
ttDepth, move, ss[ssPos].staticEval);
return value;
}
}
}
}
if (InCheck && bestValue == -cValoresJuego.INFINITO)
return cTypes.MateEnVs(ss[ssPos].ply);
cMotor.m_TablaHash.Save(posKey, value_to_tt(bestValue, ss[ssPos].ply),
PvNode && bestValue > oldAlpha ? cBordes.BOUND_EXACT : cBordes.BOUND_UPPER,
ttDepth, bestMove, ss[ssPos].staticEval);
return bestValue;
}