void evaluate_space(const Position &p, Color us, EvalInfo &ei);
inline Value apply_weight(Value v, int w);
+ Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]);
int count_1s_8bit(Bitboard b);
}
-/// scale_by_game_phase() interpolates between a middle game and an endgame
-/// score, based on game phase. It also scales the return value by a
-/// ScaleFactor array.
-
-Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
-
- assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
- assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
- assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
-
- ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
-
- Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
- return Value(int(result) & ~(GrainSize - 1));
-}
-
namespace {
// evaluate_common() computes terms common to all pieces attack
}
+ // scale_by_game_phase() interpolates between a middle game and an endgame
+ // score, based on game phase. It also scales the return value by a
+ // ScaleFactor array.
+
+ Value scale_by_game_phase(Value mv, Value ev, Phase ph, const ScaleFactor sf[]) {
+
+ assert(mv > -VALUE_INFINITE && mv < VALUE_INFINITE);
+ assert(ev > -VALUE_INFINITE && ev < VALUE_INFINITE);
+ assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
+
+ ev = apply_scale_factor(ev, sf[(ev > Value(0) ? WHITE : BLACK)]);
+
+ Value result = Value(int((mv * ph + ev * (128 - ph)) / 128));
+ return Value(int(result) & ~(GrainSize - 1));
+ }
+
+
// count_1s_8bit() counts the number of nonzero bits in the 8 least
// significant bits of a Bitboard. This function is used by the king
// shield evaluation.
// evaluation of the position is more than NullMoveMargin below beta.
const Value NullMoveMargin = Value(0x300);
- //Null move search refutes move when Nullvalue >= Beta - Delta. Index is depth
- //in full plies. Last index is 9+.
- const Value NullMoveDeltaMidgame[] =
- { Value(-8), Value( 6), Value(-15), Value( 9), Value(21),
- Value(34), Value(54), Value( 59), Value(61), Value(61) };
-
- const Value NullMoveDeltaEndgame[] =
- { Value( 6), Value( 0), Value(-13), Value(-9), Value(-35),
- Value(12), Value(24), Value( 9), Value( 5), Value( 5) };
-
// Pruning criterions. See the code and comments in ok_to_prune() to
// understand their precise meaning.
const bool PruneEscapeMoves = false;
&& ok_to_do_nullmove(pos)
&& approximateEval >= beta - NullMoveMargin)
{
- //Calculate correct delta. Idea and tuning from Joona Kiiski.
- ScaleFactor factor[2] = { SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL };
- Phase phase = pos.game_phase();
- int i = Min(depth / OnePly, 9);
- Value delta = scale_by_game_phase(NullMoveDeltaMidgame[i], NullMoveDeltaEndgame[i], phase, factor);
-
ss[ply].currentMove = MOVE_NULL;
StateInfo st;
pos.do_null_move(st);
int R = (depth >= 4 * OnePly ? 4 : 3); // Null move dynamic reduction
- Value nullValue = -search(pos, ss, -(beta-delta-1), depth-R*OnePly, ply+1, false, threadID);
+ Value nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
pos.undo_null_move();
{
/* Do not return unproven mates */
}
- else if (nullValue >= beta - delta)
+ else if (nullValue >= beta)
{
if (depth < 6 * OnePly)
return beta;