// Different node types, used as template parameter
enum NodeType { Root, PV, NonPV };
- // Dynamic razoring margin based on depth
+ // Razoring and futility margin based on depth
inline Value razor_margin(Depth d) { return Value(512 + 32 * d); }
+ inline Value futility_margin(Depth d) { return Value(200 * d); }
- // Futility lookup tables (initialized at startup) and their access functions
- int FutilityMoveCounts[2][16]; // [improving][depth]
+ // Futility and reductions lookup tables, initialized at startup
+ int FutilityMoveCounts[2][16]; // [improving][depth]
+ Depth Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber]
- inline Value futility_margin(Depth d) {
- return Value(200 * d);
+ template <bool PvNode> inline Depth reduction(bool i, Depth d, int mn) {
+ return Reductions[PvNode][i][std::min(d, 63 * ONE_PLY)][std::min(mn, 63)];
}
- // Reduction lookup tables (initialized at startup) and their access function
- int8_t Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber]
+ // Skill struct is used to implement strength limiting
+ struct Skill {
+ Skill(int l) : level(l) {}
+ bool enabled() const { return level < 20; }
+ bool time_to_pick(Depth depth) const { return depth / ONE_PLY == 1 + level; }
+ Move best_move(size_t multiPV) { return best ? best : pick_best(multiPV); }
+ Move pick_best(size_t multiPV);
- template <bool PvNode> inline Depth reduction(bool i, Depth d, int mn) {
- return (Depth) Reductions[PvNode][i][std::min(int(d), 63)][std::min(mn, 63)];
- }
+ int level;
+ Move best = MOVE_NONE;
+ };
size_t PVIdx;
TimeManager TimeMgr;
void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
string uci_pv(const Position& pos, Depth depth, Value alpha, Value beta);
- struct Skill {
- Skill(int l) : level(l) {}
- bool enabled() const { return level < 20; }
- bool time_to_pick(Depth depth) const { return depth / ONE_PLY == 1 + level; }
- Move best_move(size_t multiPV) { return best ? best : pick_best(multiPV); }
- Move pick_best(size_t multiPV);
-
- int level;
- Move best = MOVE_NONE;
- };
-
} // namespace
void Search::init() {
- // Init reductions array
- for (int d = 1; d < 64; ++d)
- for (int mc = 1; mc < 64; ++mc)
- {
- double pvRed = 0.00 + log(double(d)) * log(double(mc)) / 3.00;
- double nonPVRed = 0.33 + log(double(d)) * log(double(mc)) / 2.25;
+ const double K[][2] = {{ 0.83, 2.25 }, { 0.50, 3.00 }};
- Reductions[1][1][d][mc] = int8_t( pvRed >= 1.0 ? pvRed + 0.5: 0);
- Reductions[0][1][d][mc] = int8_t(nonPVRed >= 1.0 ? nonPVRed + 0.5: 0);
+ for (int pv = 0; pv <= 1; ++pv)
+ for (int imp = 0; imp <= 1; ++imp)
+ for (int d = 1; d < 64; ++d)
+ for (int mc = 1; mc < 64; ++mc)
+ {
+ double r = K[pv][0] + log(d) * log(mc) / K[pv][1];
- Reductions[1][0][d][mc] = Reductions[1][1][d][mc];
- Reductions[0][0][d][mc] = Reductions[0][1][d][mc];
+ if (r >= 1.5)
+ Reductions[pv][imp][d][mc] = int(r) * ONE_PLY;
- // Increase reduction when eval is not improving
- if (Reductions[0][0][d][mc] >= 2)
- Reductions[0][0][d][mc] += 1;
- }
+ // Increase reduction when eval is not improving
+ if (!pv && !imp && Reductions[pv][imp][d][mc] >= 2 * ONE_PLY)
+ Reductions[pv][imp][d][mc] += ONE_PLY;
+ }
- // Init futility move count array
for (int d = 0; d < 16; ++d)
{
FutilityMoveCounts[0][d] = int(2.4 + 0.773 * pow(d + 0.00, 1.8));
// played quiet moves.
Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY));
History.update(pos.moved_piece(move), to_sq(move), bonus);
+
for (int i = 0; i < quietsCnt; ++i)
{
Move m = quiets[i];