Outpost tuning

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 55c5014a447c7f44c6614815bf49a100e4b4a87d..4f99eb870e5fc712ea7121fb6d042407a711c793 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)

-  Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad

 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by


@@ -17,13 +17,10 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 

-
-////
-//// Includes
-////
-
+#include <algorithm>

 #include <cassert>
 #include <cassert>

-#include <cstring>
+#include <iomanip>
+#include <sstream>

 
 #include "bitcount.h"
 #include "evaluate.h"
 
 #include "bitcount.h"
 #include "evaluate.h"


@@ -32,870 +29,868 @@
 #include "thread.h"
 #include "ucioption.h"
 
 #include "thread.h"
 #include "ucioption.h"
 

+namespace {
+
+  // Struct EvalInfo contains various information computed and collected
+  // by the evaluation functions.
+  struct EvalInfo {
+
+    // Pointers to material and pawn hash table entries
+    Material::Entry* mi;
+    Pawns::Entry* pi;
+
+    // attackedBy[color][piece type] is a bitboard representing all squares
+    // attacked by a given color and piece type, attackedBy[color][ALL_PIECES]
+    // contains all squares attacked by the given color.
+    Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
+
+    // kingRing[color] is the zone around the king which is considered
+    // by the king safety evaluation. This consists of the squares directly
+    // adjacent to the king, and the three (or two, for a king on an edge file)
+    // squares two ranks in front of the king. For instance, if black's king
+    // is on g8, kingRing[BLACK] is a bitboard containing the squares f8, h8,
+    // f7, g7, h7, f6, g6 and h6.
+    Bitboard kingRing[COLOR_NB];
+
+    // kingAttackersCount[color] is the number of pieces of the given color
+    // which attack a square in the kingRing of the enemy king.
+    int kingAttackersCount[COLOR_NB];
+
+    // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
+    // given color which attack a square in the kingRing of the enemy king. The
+    // weights of the individual piece types are given by the variables
+    // QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
+    // KnightAttackWeight in evaluate.cpp
+    int kingAttackersWeight[COLOR_NB];
+
+    // kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
+    // directly adjacent to the king of the given color. Pieces which attack
+    // more than one square are counted multiple times. For instance, if black's
+    // king is on g8 and there's a white knight on g5, this knight adds
+    // 2 to kingAdjacentZoneAttacksCount[BLACK].
+    int kingAdjacentZoneAttacksCount[COLOR_NB];
+
+    Bitboard pinnedPieces[COLOR_NB];
+  };

 
 

-////
-//// Local definitions
-////
+  namespace Tracing {

 
 

-namespace {
+    enum Terms { // First 8 entries are for PieceType
+      MATERIAL = 8, IMBALANCE, MOBILITY, THREAT, PASSED, SPACE, TOTAL, TERMS_NB
+    };

 
 

-  const int Sign[2] = { 1, -1 };
+    Score terms[COLOR_NB][TERMS_NB];
+    EvalInfo ei;
+    ScaleFactor sf;

 
 

-  // Evaluation grain size, must be a power of 2
-  const int GrainSize = 8;
+    double to_cp(Value v);
+    void add_term(int idx, Score term_w, Score term_b = SCORE_ZERO);
+    void format_row(std::stringstream& ss, const char* name, int idx);
+    std::string do_trace(const Position& pos);
+  }

 
 

-  // Evaluation weights, initialized from UCI options
-  enum { Mobility, PawnStructure, PassedPawns, Space, KingDangerUs, KingDangerThem };
-  Score Weights[6];
+  // Evaluation weights, indexed by evaluation term
+  enum { Mobility, PawnStructure, PassedPawns, Space, KingSafety };
+  const struct Weight { int mg, eg; } Weights[] = {
+    {289, 344}, {233, 201}, {221, 273}, {46, 0}, {318, 0}
+  };

 
   typedef Value V;
   #define S(mg, eg) make_score(mg, eg)
 
 
   typedef Value V;
   #define S(mg, eg) make_score(mg, eg)
 

-  // Internal evaluation weights. These are applied on top of the evaluation
-  // weights read from UCI parameters. The purpose is to be able to change
-  // the evaluation weights while keeping the default values of the UCI
-  // parameters at 100, which looks prettier.
-  //
-  // Values modified by Joona Kiiski
-  const Score WeightsInternal[] = {
-      S(248, 271), S(233, 201), S(252, 259), S(46, 0), S(247, 0), S(259, 0)
-  };
-
-  // Pieces mobility bonus in middle game and endgame, indexed by piece type
-  // and number of attacked squares not occupied by friendly pieces.
+  // MobilityBonus[PieceType][attacked] contains bonuses for middle and end
+  // game, indexed by piece type and number of attacked squares not occupied by
+  // friendly pieces.

   const Score MobilityBonus[][32] = {
   const Score MobilityBonus[][32] = {

-     {}, {},
-     { S(-38,-33), S(-25,-23), S(-12,-13), S( 0, -3), S(12,  7), S(25, 17), // Knights
-       S( 31, 22), S( 38, 27), S( 38, 27) },
-     { S(-25,-30), S(-11,-16), S(  3, -2), S(17, 12), S(31, 26), S(45, 40), // Bishops
-       S( 57, 52), S( 65, 60), S( 71, 65), S(74, 69), S(76, 71), S(78, 73),
-       S( 79, 74), S( 80, 75), S( 81, 76), S(81, 76) },
-     { S(-20,-36), S(-14,-19), S( -8, -3), S(-2, 13), S( 4, 29), S(10, 46), // Rooks
-       S( 14, 62), S( 19, 79), S( 23, 95), S(26,106), S(27,111), S(28,114),
-       S( 29,116), S( 30,117), S( 31,118), S(32,118) },
-     { S(-10,-18), S( -8,-13), S( -6, -7), S(-3, -2), S(-1,  3), S( 1,  8), // Queens
-       S(  3, 13), S(  5, 19), S(  8, 23), S(10, 27), S(12, 32), S(15, 34),
-       S( 16, 35), S( 17, 35), S( 18, 35), S(20, 35), S(20, 35), S(20, 35),
-       S( 20, 35), S( 20, 35), S( 20, 35), S(20, 35), S(20, 35), S(20, 35),
-       S( 20, 35), S( 20, 35), S( 20, 35), S(20, 35), S(20, 35), S(20, 35),
-       S( 20, 35), S( 20, 35) }
+    {}, {},
+    { S(-65,-50), S(-42,-30), S(-9,-10), S( 3,  0), S(15, 10), S(27, 20), // Knights
+      S( 37, 28), S( 42, 31), S(44, 33) },
+    { S(-52,-47), S(-28,-23), S( 6,  1), S(20, 15), S(34, 29), S(48, 43), // Bishops
+      S( 60, 55), S( 68, 63), S(74, 68), S(77, 72), S(80, 75), S(82, 77),
+      S( 84, 79), S( 86, 81) },
+    { S(-47,-53), S(-31,-26), S(-5,  0), S( 1, 16), S( 7, 32), S(13, 48), // Rooks
+      S( 18, 64), S( 22, 80), S(26, 96), S(29,109), S(31,115), S(33,119),
+      S( 35,122), S( 36,123), S(37,124) },
+    { S(-42,-40), S(-28,-23), S(-5, -7), S( 0,  0), S( 6, 10), S(11, 19), // Queens
+      S( 13, 29), S( 18, 38), S(20, 40), S(21, 41), S(22, 41), S(22, 41),
+      S( 22, 41), S( 23, 41), S(24, 41), S(25, 41), S(25, 41), S(25, 41),
+      S( 25, 41), S( 25, 41), S(25, 41), S(25, 41), S(25, 41), S(25, 41),
+      S( 25, 41), S( 25, 41), S(25, 41), S(25, 41) }

   };
 
   };
 

-  // Outpost bonuses for knights and bishops, indexed by square (from white's
-  // point of view).
-  const Value OutpostBonus[][64] = {
-  {
-  //  A     B     C     D     E     F     G     H
+  // Outpost[PieceType][Square] contains bonuses for knights and bishops outposts,
+  // indexed by piece type and square (from white's point of view).
+  const Value Outpost[][SQUARE_NB] = {
+  {// A     B     C     D     E     F     G     H

     V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
     V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
     V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
     V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
     V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),
     V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Knights
     V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
     V(0), V(0), V(4), V(8), V(8), V(4), V(0), V(0),
     V(0), V(4),V(17),V(26),V(26),V(17), V(4), V(0),
     V(0), V(8),V(26),V(35),V(35),V(26), V(8), V(0),

-    V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0),
-    V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
-    V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) },
+    V(0), V(4),V(17),V(17),V(17),V(17), V(4), V(0) },

   {
     V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
     V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
     V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
     V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
     V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),
   {
     V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0), // Bishops
     V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
     V(0), V(0), V(5), V(5), V(5), V(5), V(0), V(0),
     V(0), V(5),V(10),V(10),V(10),V(10), V(5), V(0),
     V(0),V(10),V(21),V(21),V(21),V(21),V(10), V(0),

-    V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0),
-    V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0),
-    V(0), V(0), V(0), V(0), V(0), V(0), V(0), V(0) }
+    V(0), V(5), V(8), V(8), V(8), V(8), V(5), V(0) }

   };
 
   };
 

-  // ThreatBonus[attacking][attacked] contains bonus according to which
-  // piece type attacks which one.
-  const Score ThreatBonus[8][8] = {
-    {}, {},
-    { S(0, 0), S( 7, 39), S( 0,  0), S(24, 49), S(41,100), S(41,100) }, // KNIGHT
-    { S(0, 0), S( 7, 39), S(24, 49), S( 0,  0), S(41,100), S(41,100) }, // BISHOP
-    { S(0, 0), S(-1, 29), S(15, 49), S(15, 49), S( 0,  0), S(24, 49) }, // ROOK
-    { S(0, 0), S(15, 39), S(15, 39), S(15, 39), S(15, 39), S( 0,  0) }  // QUEEN
+  // Threat[attacking][attacked] contains bonuses according to which piece
+  // type attacks which one.
+  const Score Threat[][PIECE_TYPE_NB] = {
+    { S(0, 0), S( 7, 39), S(24, 49), S(24, 49), S(41,100), S(41,100) }, // Minor
+    { S(0, 0), S(15, 39), S(15, 45), S(15, 45), S(15, 45), S(24, 49) }  // Major

   };
 
   };
 

-  // ThreatedByPawnPenalty[] contains a penalty according to which piece
+  // ThreatenedByPawn[PieceType] contains a penalty according to which piece

   // type is attacked by an enemy pawn.
   // type is attacked by an enemy pawn.

-  const Score ThreatedByPawnPenalty[8] = {
-    S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
+  const Score ThreatenedByPawn[] = {
+    S(0, 0), S(0, 0), S(80, 119), S(80, 119), S(117, 199), S(127, 218)

   };
 
   };
 

-  #undef S
-
-  // Rooks and queens on the 7th rank (modified by Joona Kiiski)
-  const Score RookOn7thBonus  = make_score(47, 98);
-  const Score QueenOn7thBonus = make_score(27, 54);
-
-  // Rooks on open files (modified by Joona Kiiski)
-  const Score RookOpenFileBonus = make_score(43, 43);
-  const Score RookHalfOpenFileBonus = make_score(19, 19);
+  // Hanging contains a bonus for each enemy hanging piece
+  const Score Hanging = S(23, 20);

 
 

-  // Penalty for rooks trapped inside a friendly king which has lost the
-  // right to castle.
-  const Value TrappedRookPenalty = Value(180);
+  #undef S

 
 

-  // The SpaceMask[color] contains the area of the board which is considered
-  // by the space evaluation. In the middle game, each side is given a bonus
+  const Score RookOnPawn       = make_score(10, 28);
+  const Score RookOpenFile     = make_score(43, 21);
+  const Score RookSemiopenFile = make_score(19, 10);
+  const Score BishopPawns      = make_score( 8, 12);
+  const Score MinorBehindPawn  = make_score(16,  0);
+  const Score TrappedRook      = make_score(92,  0);
+  const Score Unstoppable      = make_score( 0, 20);
+
+  // Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
+  // a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
+  // happen in Chess960 games.
+  const Score TrappedBishopA1H1 = make_score(50, 50);
+
+  // SpaceMask[Color] contains the area of the board which is considered
+  // by the space evaluation. In the middlegame, each side is given a bonus

   // based on how many squares inside this area are safe and available for
   // friendly minor pieces.
   // based on how many squares inside this area are safe and available for
   // friendly minor pieces.

-  const Bitboard SpaceMask[2] = {
-    (1ULL<<SQ_C2) | (1ULL<<SQ_D2) | (1ULL<<SQ_E2) | (1ULL<<SQ_F2) |
-    (1ULL<<SQ_C3) | (1ULL<<SQ_D3) | (1ULL<<SQ_E3) | (1ULL<<SQ_F3) |
-    (1ULL<<SQ_C4) | (1ULL<<SQ_D4) | (1ULL<<SQ_E4) | (1ULL<<SQ_F4),
-    (1ULL<<SQ_C7) | (1ULL<<SQ_D7) | (1ULL<<SQ_E7) | (1ULL<<SQ_F7) |
-    (1ULL<<SQ_C6) | (1ULL<<SQ_D6) | (1ULL<<SQ_E6) | (1ULL<<SQ_F6) |
-    (1ULL<<SQ_C5) | (1ULL<<SQ_D5) | (1ULL<<SQ_E5) | (1ULL<<SQ_F5)
+  const Bitboard SpaceMask[] = {
+    (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank2BB | Rank3BB | Rank4BB),
+    (FileCBB | FileDBB | FileEBB | FileFBB) & (Rank7BB | Rank6BB | Rank5BB)

   };
 
   };
 

-  /// King danger constants and variables. The king danger scores are taken
-  /// from the KingDangerTable[]. Various little "meta-bonuses" measuring
-  /// the strength of the enemy attack are added up into an integer, which
-  /// is used as an index to KingDangerTable[].
-
-  // KingAttackWeights[] contains king attack weights by piece type
-  const int KingAttackWeights[8] = { 0, 0, 2, 2, 3, 5 };
+  // King danger constants and variables. The king danger scores are taken
+  // from KingDanger[]. Various little "meta-bonuses" measuring the strength
+  // of the enemy attack are added up into an integer, which is used as an
+  // index to KingDanger[].
+  //
+  // KingAttackWeights[PieceType] contains king attack weights by piece type
+  const int KingAttackWeights[] = { 0, 0, 2, 2, 3, 5 };

 
   // Bonuses for enemy's safe checks
 
   // Bonuses for enemy's safe checks

-  const int QueenContactCheckBonus = 3;
-  const int QueenCheckBonus        = 2;
-  const int RookCheckBonus         = 1;
-  const int BishopCheckBonus       = 1;
-  const int KnightCheckBonus       = 1;
-
-  // InitKingDanger[] contains bonuses based on the position of the defending
-  // king.
-  const int InitKingDanger[64] = {
-     2,  0,  2,  5,  5,  2,  0,  2,
-     2,  2,  4,  8,  8,  4,  2,  2,
-     7, 10, 12, 12, 12, 12, 10,  7,
-    15, 15, 15, 15, 15, 15, 15, 15,
-    15, 15, 15, 15, 15, 15, 15, 15,
-    15, 15, 15, 15, 15, 15, 15, 15,
-    15, 15, 15, 15, 15, 15, 15, 15,
-    15, 15, 15, 15, 15, 15, 15, 15
-  };
-
-  // KingDangerTable[color][] contains the actual king danger weighted scores
-  Score KingDangerTable[2][128];
+  const int QueenContactCheck = 24;
+  const int RookContactCheck  = 16;
+  const int QueenCheck        = 12;
+  const int RookCheck         = 8;
+  const int BishopCheck       = 2;
+  const int KnightCheck       = 3;
+
+  // KingDanger[attackUnits] contains the actual king danger weighted
+  // scores, indexed by a calculated integer number.
+  Score KingDanger[128];
+
+  const int ScalePawnSpan[2] = { 38, 56 };
+
+  // apply_weight() weighs score 'v' by weight 'w' trying to prevent overflow
+  Score apply_weight(Score v, const Weight& w) {
+    return make_score(mg_value(v) * w.mg / 256, eg_value(v) * w.eg / 256);
+  }

 
 

-  // Pawn and material hash tables, indexed by the current thread id.
-  // Note that they will be initialized at 0 being global variables.
-  MaterialInfoTable* MaterialTable[MAX_THREADS];
-  PawnInfoTable* PawnTable[MAX_THREADS];

 
 

-  // Function prototypes
-  template<bool HasPopCnt>
-  Value do_evaluate(const Position& pos, EvalInfo& ei);
+  // init_eval_info() initializes king bitboards for given color adding
+  // pawn attacks. To be done at the beginning of the evaluation.

 
 

-  template<Color Us, bool HasPopCnt>
-  void init_attack_tables(const Position& pos, EvalInfo& ei);
+  template<Color Us>
+  void init_eval_info(const Position& pos, EvalInfo& ei) {

 
 

-  template<Color Us, bool HasPopCnt>
-  void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
+    const Color  Them = (Us == WHITE ? BLACK : WHITE);
+    const Square Down = (Us == WHITE ? DELTA_S : DELTA_N);

 
 

-  template<Color Us, bool HasPopCnt>
-  void evaluate_king(const Position& pos, EvalInfo& ei);
+    ei.pinnedPieces[Us] = pos.pinned_pieces(Us);

 
 

-  template<Color Us>
-  void evaluate_threats(const Position& pos, EvalInfo& ei);
+    Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
+    ei.attackedBy[Us][ALL_PIECES] = ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);

 
 

-  template<Color Us, bool HasPopCnt>
-  int evaluate_space(const Position& pos, EvalInfo& ei);
+    // Init king safety tables only if we are going to use them
+    if (pos.count<QUEEN>(Us) && pos.non_pawn_material(Us) > QueenValueMg + PawnValueMg)
+    {
+        ei.kingRing[Them] = b | shift_bb<Down>(b);
+        b &= ei.attackedBy[Us][PAWN];
+        ei.kingAttackersCount[Us] = b ? popcount<Max15>(b) : 0;
+        ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
+    }
+    else
+        ei.kingRing[Them] = ei.kingAttackersCount[Us] = 0;
+  }

 
 

-  template<Color Us>
-  void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);

 
 

-  inline Score apply_weight(Score v, Score weight);
-  Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
-  Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
-  void init_safety();
-}
+  // evaluate_outpost() evaluates bishop and knight outpost squares

 
 

+  template<PieceType Pt, Color Us>
+  Score evaluate_outpost(const Position& pos, const EvalInfo& ei, Square s) {

 
 

-////
-//// Functions
-////
+    const Color Them = (Us == WHITE ? BLACK : WHITE);

 
 

+    assert (Pt == BISHOP || Pt == KNIGHT);

 
 

-/// Prefetches in pawn hash tables
+    // Initial bonus based on square
+    Value bonus = Outpost[Pt == BISHOP][relative_square(Us, s)];

 
 

-void prefetchPawn(Key key, int threadID) {
+    // Increase bonus if supported by pawn, especially if the opponent has
+    // no minor piece which can trade with the outpost piece.
+    if (bonus && (ei.attackedBy[Us][PAWN] & s))
+    {
+        if (   !pos.pieces(Them, KNIGHT)
+            && !(squares_of_color(s) & pos.pieces(Them, BISHOP)))
+            bonus += bonus + bonus / 2;
+        else
+            bonus += bonus / 2;
+    }

 
 

-    PawnTable[threadID]->prefetch(key);
-}
+    return make_score(bonus * 2, bonus / 2);
+  }

 
 

-/// evaluate() is the main evaluation function. It always computes two
-/// values, an endgame score and a middle game score, and interpolates
-/// between them based on the remaining material.
-Value evaluate(const Position& pos, EvalInfo& ei) {

 
 

-    return CpuHasPOPCNT ? do_evaluate<true>(pos, ei)
-                        : do_evaluate<false>(pos, ei);
-}
+  // evaluate_pieces() assigns bonuses and penalties to the pieces of a given color

 
 

-namespace {
+  template<PieceType Pt, Color Us, bool Trace>
+  Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score* mobility, Bitboard* mobilityArea) {

 
 

-template<bool HasPopCnt>
-Value do_evaluate(const Position& pos, EvalInfo& ei) {
+    Bitboard b;
+    Square s;
+    Score score = SCORE_ZERO;

 
 

-  ScaleFactor factor[2];
+    const PieceType NextPt = (Us == WHITE ? Pt : PieceType(Pt + 1));
+    const Color Them = (Us == WHITE ? BLACK : WHITE);
+    const Square* pl = pos.list<Pt>(Us);

 
 

-  assert(pos.is_ok());
-  assert(pos.thread() >= 0 && pos.thread() < MAX_THREADS);
-  assert(!pos.is_check());
+    ei.attackedBy[Us][Pt] = 0;

 
 

-  memset(&ei, 0, sizeof(EvalInfo));
+    while ((s = *pl++) != SQ_NONE)
+    {
+        // Find attacked squares, including x-ray attacks for bishops and rooks
+        b = Pt == BISHOP ? attacks_bb<BISHOP>(s, pos.pieces() ^ pos.pieces(Us, QUEEN))
+          : Pt ==   ROOK ? attacks_bb<  ROOK>(s, pos.pieces() ^ pos.pieces(Us, ROOK, QUEEN))
+                         : pos.attacks_from<Pt>(s);

 
 

-  // Initialize by reading the incrementally updated scores included in the
-  // position object (material + piece square tables)
-  ei.value = pos.value();
+        if (ei.pinnedPieces[Us] & s)
+            b &= LineBB[pos.king_square(Us)][s];

 
 

-  // Probe the material hash table
-  ei.mi = MaterialTable[pos.thread()]->get_material_info(pos);
-  ei.value += ei.mi->material_value();
+        ei.attackedBy[Us][ALL_PIECES] |= ei.attackedBy[Us][Pt] |= b;

 
 

-  // If we have a specialized evaluation function for the current material
-  // configuration, call it and return
-  if (ei.mi->specialized_eval_exists())
-      return ei.mi->evaluate(pos);
+        if (b & ei.kingRing[Them])
+        {
+            ei.kingAttackersCount[Us]++;
+            ei.kingAttackersWeight[Us] += KingAttackWeights[Pt];
+            Bitboard bb = b & ei.attackedBy[Them][KING];
+            if (bb)
+                ei.kingAdjacentZoneAttacksCount[Us] += popcount<Max15>(bb);
+        }

 
 

-  // After get_material_info() call that modifies them
-  factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
-  factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
+        if (Pt == QUEEN)
+            b &= ~(  ei.attackedBy[Them][KNIGHT]
+                   | ei.attackedBy[Them][BISHOP]
+                   | ei.attackedBy[Them][ROOK]);

 
 

-  // Probe the pawn hash table
-  ei.pi = PawnTable[pos.thread()]->get_pawn_info(pos);
-  ei.value += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
+        int mob = Pt != QUEEN ? popcount<Max15>(b & mobilityArea[Us])
+                              : popcount<Full >(b & mobilityArea[Us]);

 
 

-  // Initialize attack bitboards with pawns evaluation
-  init_attack_tables<WHITE, HasPopCnt>(pos, ei);
-  init_attack_tables<BLACK, HasPopCnt>(pos, ei);
+        mobility[Us] += MobilityBonus[Pt][mob];

 
 

-  // Evaluate pieces
-  evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
-  evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
+        // Decrease score if we are attacked by an enemy pawn. The remaining part
+        // of threat evaluation must be done later when we have full attack info.
+        if (ei.attackedBy[Them][PAWN] & s)
+            score -= ThreatenedByPawn[Pt];

 
 

-  // Kings. Kings are evaluated after all other pieces for both sides,
-  // because we need complete attack information for all pieces when computing
-  // the king safety evaluation.
-  evaluate_king<WHITE, HasPopCnt>(pos, ei);
-  evaluate_king<BLACK, HasPopCnt>(pos, ei);
+        if (Pt == BISHOP || Pt == KNIGHT)
+        {
+            // Penalty for bishop with same colored pawns
+            if (Pt == BISHOP)
+                score -= BishopPawns * ei.pi->pawns_on_same_color_squares(Us, s);
+
+            // Bishop and knight outpost square
+            if (!(pos.pieces(Them, PAWN) & pawn_attack_span(Us, s)))
+                score += evaluate_outpost<Pt, Us>(pos, ei, s);
+
+            // Bishop or knight behind a pawn
+            if (    relative_rank(Us, s) < RANK_5
+                && (pos.pieces(PAWN) & (s + pawn_push(Us))))
+                score += MinorBehindPawn;
+        }

 
 

-  // Evaluate tactical threats, we need full attack info including king
-  evaluate_threats<WHITE>(pos, ei);
-  evaluate_threats<BLACK>(pos, ei);
+        if (Pt == ROOK)
+        {
+            // Rook piece attacking enemy pawns on the same rank/file
+            if (relative_rank(Us, s) >= RANK_5)
+            {
+                Bitboard pawns = pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s];
+                if (pawns)
+                    score += popcount<Max15>(pawns) * RookOnPawn;
+            }

 
 

-  // Evaluate passed pawns, we need full attack info including king
-  evaluate_passed_pawns<WHITE>(pos, ei);
-  evaluate_passed_pawns<BLACK>(pos, ei);
+            // Give a bonus for a rook on a open or semi-open file
+            if (ei.pi->semiopen_file(Us, file_of(s)))
+                score += ei.pi->semiopen_file(Them, file_of(s)) ? RookOpenFile : RookSemiopenFile;

 
 

-  Phase phase = ei.mi->game_phase();
+            if (mob > 3 || ei.pi->semiopen_file(Us, file_of(s)))
+                continue;

 
 

-  // Middle-game specific evaluation terms
-  if (phase > PHASE_ENDGAME)
-  {
-      // Evaluate pawn storms in positions with opposite castling
-      if (   square_file(pos.king_square(WHITE)) >= FILE_E
-          && square_file(pos.king_square(BLACK)) <= FILE_D)
+            Square ksq = pos.king_square(Us);

 
 

-          ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
+            // Penalize rooks which are trapped by a king. Penalize more if the
+            // king has lost its castling capability.
+            if (   ((file_of(ksq) < FILE_E) == (file_of(s) < file_of(ksq)))
+                && (rank_of(ksq) == rank_of(s) || relative_rank(Us, ksq) == RANK_1)
+                && !ei.pi->semiopen_side(Us, file_of(ksq), file_of(s) < file_of(ksq)))
+                score -= (TrappedRook - make_score(mob * 22, 0)) * (1 + !pos.can_castle(Us));
+        }

 
 

-      else if (   square_file(pos.king_square(WHITE)) <= FILE_D
-               && square_file(pos.king_square(BLACK)) >= FILE_E)
+        // An important Chess960 pattern: A cornered bishop blocked by a friendly
+        // pawn diagonally in front of it is a very serious problem, especially
+        // when that pawn is also blocked.
+        if (   Pt == BISHOP
+            && pos.is_chess960()
+            && (s == relative_square(Us, SQ_A1) || s == relative_square(Us, SQ_H1)))
+        {
+            Square d = pawn_push(Us) + (file_of(s) == FILE_A ? DELTA_E : DELTA_W);
+            if (pos.piece_on(s + d) == make_piece(Us, PAWN))
+                score -= !pos.empty(s + d + pawn_push(Us))                ? TrappedBishopA1H1 * 4
+                        : pos.piece_on(s + d + d) == make_piece(Us, PAWN) ? TrappedBishopA1H1 * 2
+                                                                          : TrappedBishopA1H1;
+        }
+    }

 
 

-          ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
+    if (Trace)
+        Tracing::terms[Us][Pt] = score;

 
 

-      // Evaluate space for both sides
-      if (ei.mi->space_weight() > 0)
-      {
-          int s = evaluate_space<WHITE, HasPopCnt>(pos, ei) - evaluate_space<BLACK, HasPopCnt>(pos, ei);
-          ei.value += apply_weight(make_score(s * ei.mi->space_weight(), 0), Weights[Space]);
-      }
+    return score - evaluate_pieces<NextPt, Them, Trace>(pos, ei, mobility, mobilityArea);

   }
 
   }
 

-  // Mobility
-  ei.value += apply_weight(ei.mobility, Weights[Mobility]);
+  template<>
+  Score evaluate_pieces<KING, WHITE, false>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }
+  template<>
+  Score evaluate_pieces<KING, WHITE,  true>(const Position&, EvalInfo&, Score*, Bitboard*) { return SCORE_ZERO; }

 
 

-  // If we don't already have an unusual scale factor, check for opposite
-  // colored bishop endgames, and use a lower scale for those
-  if (   phase < PHASE_MIDGAME
-      && pos.opposite_colored_bishops()
-      && (   (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > VALUE_ZERO)
-          || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < VALUE_ZERO)))
-  {
-      ScaleFactor sf;
-
-      // Only the two bishops ?
-      if (   pos.non_pawn_material(WHITE) == BishopValueMidgame
-          && pos.non_pawn_material(BLACK) == BishopValueMidgame)
-      {
-          // Check for KBP vs KB with only a single pawn that is almost
-          // certainly a draw or at least two pawns.
-          bool one_pawn = (pos.piece_count(WHITE, PAWN) + pos.piece_count(BLACK, PAWN) == 1);
-          sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);
-      }
-      else
-          // Endgame with opposite-colored bishops, but also other pieces. Still
-          // a bit drawish, but not as drawish as with only the two bishops.
-           sf = ScaleFactor(50);
-
-      if (factor[WHITE] == SCALE_FACTOR_NORMAL)
-          factor[WHITE] = sf;
-      if (factor[BLACK] == SCALE_FACTOR_NORMAL)
-          factor[BLACK] = sf;
-  }

 
 

-  // Interpolate between the middle game and the endgame score
-  return Sign[pos.side_to_move()] * scale_by_game_phase(ei.value, phase, factor);
-}
+  // evaluate_king() assigns bonuses and penalties to a king of a given color

 
 

-} // namespace
+  template<Color Us, bool Trace>
+  Score evaluate_king(const Position& pos, const EvalInfo& ei) {

 
 

-/// init_eval() initializes various tables used by the evaluation function
+    const Color Them = (Us == WHITE ? BLACK : WHITE);

 
 

-void init_eval(int threads) {
+    Bitboard undefended, b, b1, b2, safe;
+    int attackUnits;
+    const Square ksq = pos.king_square(Us);

 
 

-  assert(threads <= MAX_THREADS);
+    // King shelter and enemy pawns storm
+    Score score = ei.pi->king_safety<Us>(pos, ksq);

 
 

-  for (int i = 0; i < MAX_THREADS; i++)
-  {
-    if (i >= threads)
+    // Main king safety evaluation
+    if (ei.kingAttackersCount[Them])

     {
     {

-        delete PawnTable[i];
-        delete MaterialTable[i];
-        PawnTable[i] = NULL;
-        MaterialTable[i] = NULL;
-        continue;
-    }
-    if (!PawnTable[i])
-        PawnTable[i] = new PawnInfoTable();
-    if (!MaterialTable[i])
-        MaterialTable[i] = new MaterialInfoTable();
-  }
-}
-
+        // Find the attacked squares around the king which have no defenders
+        // apart from the king itself
+        undefended =  ei.attackedBy[Them][ALL_PIECES]
+                    & ei.attackedBy[Us][KING]
+                    & ~(  ei.attackedBy[Us][PAWN]   | ei.attackedBy[Us][KNIGHT]
+                        | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
+                        | ei.attackedBy[Us][QUEEN]);

 
 

-/// quit_eval() releases heap-allocated memory at program termination
+        // Initialize the 'attackUnits' variable, which is used later on as an
+        // index to the KingDanger[] array. The initial value is based on the
+        // number and types of the enemy's attacking pieces, the number of
+        // attacked and undefended squares around our king and the quality of
+        // the pawn shelter (current 'score' value).
+        attackUnits =  std::min(20, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
+                     + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + popcount<Max15>(undefended))
+                     + 2 * (ei.pinnedPieces[Us] != 0)
+                     - mg_value(score) / 32;
+
+        // Analyse the enemy's safe queen contact checks. Firstly, find the
+        // undefended squares around the king that are attacked by the enemy's
+        // queen...
+        b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
+        if (b)
+        {
+            // ...and then remove squares not supported by another enemy piece
+            b &= (  ei.attackedBy[Them][PAWN]   | ei.attackedBy[Them][KNIGHT]
+                  | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);

 
 

-void quit_eval() {
+            if (b)
+                attackUnits +=  QueenContactCheck * popcount<Max15>(b);
+        }

 
 

-  for (int i = 0; i < MAX_THREADS; i++)
-  {
-      delete PawnTable[i];
-      delete MaterialTable[i];
-      PawnTable[i] = NULL;
-      MaterialTable[i] = NULL;
-  }
-}
+        // Analyse the enemy's safe rook contact checks. Firstly, find the
+        // undefended squares around the king that are attacked by the enemy's
+        // rooks...
+        b = undefended & ei.attackedBy[Them][ROOK] & ~pos.pieces(Them);

 
 

+        // Consider only squares where the enemy's rook gives check
+        b &= PseudoAttacks[ROOK][ksq];

 
 

-/// read_weights() reads evaluation weights from the corresponding UCI parameters
+        if (b)
+        {
+            // ...and then remove squares not supported by another enemy piece
+            b &= (  ei.attackedBy[Them][PAWN]   | ei.attackedBy[Them][KNIGHT]
+                  | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][QUEEN]);

 
 

-void read_weights(Color us) {
+            if (b)
+                attackUnits +=  RookContactCheck * popcount<Max15>(b);
+        }

 
 

-  // King safety is asymmetrical. Our king danger level is weighted by
-  // "Cowardice" UCI parameter, instead the opponent one by "Aggressiveness".
-  const int kingDangerUs   = (us == WHITE ? KingDangerUs   : KingDangerThem);
-  const int kingDangerThem = (us == WHITE ? KingDangerThem : KingDangerUs);
+        // Analyse the enemy's safe distance checks for sliders and knights
+        safe = ~(pos.pieces(Them) | ei.attackedBy[Us][ALL_PIECES]);

 
 

-  Weights[Mobility]       = weight_option("Mobility (Middle Game)", "Mobility (Endgame)", WeightsInternal[Mobility]);
-  Weights[PawnStructure]  = weight_option("Pawn Structure (Middle Game)", "Pawn Structure (Endgame)", WeightsInternal[PawnStructure]);
-  Weights[PassedPawns]    = weight_option("Passed Pawns (Middle Game)", "Passed Pawns (Endgame)", WeightsInternal[PassedPawns]);
-  Weights[Space]          = weight_option("Space", "Space", WeightsInternal[Space]);
-  Weights[kingDangerUs]   = weight_option("Cowardice", "Cowardice", WeightsInternal[KingDangerUs]);
-  Weights[kingDangerThem] = weight_option("Aggressiveness", "Aggressiveness", WeightsInternal[KingDangerThem]);
+        b1 = pos.attacks_from<ROOK>(ksq) & safe;
+        b2 = pos.attacks_from<BISHOP>(ksq) & safe;

 
 

-  // If running in analysis mode, make sure we use symmetrical king safety. We do this
-  // by replacing both Weights[kingDangerUs] and Weights[kingDangerThem] by their average.
-  if (get_option_value_bool("UCI_AnalyseMode"))
-      Weights[kingDangerUs] = Weights[kingDangerThem] = (Weights[kingDangerUs] + Weights[kingDangerThem]) / 2;
+        // Enemy queen safe checks
+        b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
+        if (b)
+            attackUnits += QueenCheck * popcount<Max15>(b);

 
 

-  init_safety();
-}
+        // Enemy rooks safe checks
+        b = b1 & ei.attackedBy[Them][ROOK];
+        if (b)
+            attackUnits += RookCheck * popcount<Max15>(b);

 
 

+        // Enemy bishops safe checks
+        b = b2 & ei.attackedBy[Them][BISHOP];
+        if (b)
+            attackUnits += BishopCheck * popcount<Max15>(b);

 
 

-namespace {
+        // Enemy knights safe checks
+        b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
+        if (b)
+            attackUnits += KnightCheck * popcount<Max15>(b);

 
 

-  // init_attack_tables() initializes king bitboards for both sides adding
-  // pawn attacks. To be done before other evaluations.
+        // To index KingDanger[] attackUnits must be in [0, 99] range
+        attackUnits = std::min(99, std::max(0, attackUnits));

 
 

-  template<Color Us, bool HasPopCnt>
-  void init_attack_tables(const Position& pos, EvalInfo& ei) {
+        // Finally, extract the king danger score from the KingDanger[]
+        // array and subtract the score from evaluation.
+        score -= KingDanger[attackUnits];
+    }

 
 

-    const Color Them = (Us == WHITE ? BLACK : WHITE);
+    if (Trace)
+        Tracing::terms[Us][KING] = score;

 
 

-    Bitboard b = ei.attackedBy[Them][KING] = pos.attacks_from<KING>(pos.king_square(Them));
-    ei.kingZone[Us] = (b | (Us == WHITE ? b >> 8 : b << 8));
-    ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
-    b &= ei.attackedBy[Us][PAWN];
-    if (b)
-        ei.kingAttackersCount[Us] = count_1s_max_15<HasPopCnt>(b) / 2;
+    return score;

   }
 
 
   }
 
 

-  // evaluate_outposts() evaluates bishop and knight outposts squares
+  // evaluate_threats() assigns bonuses according to the type of attacking piece
+  // and the type of attacked one.

 
 

-  template<PieceType Piece, Color Us>
-  void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
+  template<Color Us, bool Trace>
+  Score evaluate_threats(const Position& pos, const EvalInfo& ei) {

 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 

-    assert (Piece == BISHOP || Piece == KNIGHT);
+    Bitboard b, weakEnemies, protectedEnemies;
+    Score score = SCORE_ZERO;

 
 

-    // Initial bonus based on square
-    Value bonus = OutpostBonus[Piece == BISHOP][relative_square(Us, s)];
+    // Protected enemies
+    protectedEnemies = (pos.pieces(Them) ^ pos.pieces(Them,PAWN))
+                      & ei.attackedBy[Them][PAWN]
+                      & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);

 
 

-    // Increase bonus if supported by pawn, especially if the opponent has
-    // no minor piece which can exchange the outpost piece
-    if (bonus && bit_is_set(ei.attackedBy[Us][PAWN], s))
+    if(protectedEnemies)
+        score += Threat[0][type_of(pos.piece_on(lsb(protectedEnemies)))];
+
+    // Enemies not defended by a pawn and under our attack
+    weakEnemies =  pos.pieces(Them)
+                 & ~ei.attackedBy[Them][PAWN]
+                 & ei.attackedBy[Us][ALL_PIECES];
+
+    // Add a bonus according if the attacking pieces are minor or major
+    if (weakEnemies)

     {
     {

-        if (    pos.pieces(KNIGHT, Them) == EmptyBoardBB
-            && (SquaresByColorBB[square_color(s)] & pos.pieces(BISHOP, Them)) == EmptyBoardBB)
-            bonus += bonus + bonus / 2;
-        else
-            bonus += bonus / 2;
+        b = weakEnemies & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+        if (b)
+            score += Threat[0][type_of(pos.piece_on(lsb(b)))];
+
+        b = weakEnemies & (ei.attackedBy[Us][ROOK] | ei.attackedBy[Us][QUEEN]);
+        if (b)
+            score += Threat[1][type_of(pos.piece_on(lsb(b)))];
+
+        b = weakEnemies & ~ei.attackedBy[Them][ALL_PIECES];
+        if (b)
+            score += more_than_one(b) ? Hanging * popcount<Max15>(b) : Hanging;

     }
     }

-    ei.value += Sign[Us] * make_score(bonus, bonus);
-  }

 
 

+    if (Trace)
+        Tracing::terms[Us][Tracing::THREAT] = score;

 
 

-  // evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
+    return score;
+  }

 
 

-  template<PieceType Piece, Color Us, bool HasPopCnt>
-  void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {

 
 

-    Bitboard b;
-    Square s, ksq;
-    int mob;
-    File f;
+  // evaluate_passed_pawns() evaluates the passed pawns of the given color
+
+  template<Color Us, bool Trace>
+  Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {

 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
     const Color Them = (Us == WHITE ? BLACK : WHITE);

-    const Square* ptr = pos.piece_list_begin(Us, Piece);

 
 

-    while ((s = *ptr++) != SQ_NONE)
-    {
-        // Find attacked squares, including x-ray attacks for bishops and rooks
-        if (Piece == KNIGHT || Piece == QUEEN)
-            b = pos.attacks_from<Piece>(s);
-        else if (Piece == BISHOP)
-            b = bishop_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(QUEEN, Us));
-        else if (Piece == ROOK)
-            b = rook_attacks_bb(s, pos.occupied_squares() & ~pos.pieces(ROOK, QUEEN, Us));
-        else
-            assert(false);
+    Bitboard b, squaresToQueen, defendedSquares, unsafeSquares;
+    Score score = SCORE_ZERO;

 
 

-        // Update attack info
-        ei.attackedBy[Us][Piece] |= b;
+    b = ei.pi->passed_pawns(Us);

 
 

-        // King attacks
-        if (b & ei.kingZone[Us])
-        {
-            ei.kingAttackersCount[Us]++;
-            ei.kingAttackersWeight[Us] += KingAttackWeights[Piece];
-            Bitboard bb = (b & ei.attackedBy[Them][KING]);
-            if (bb)
-                ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
-        }
-
-        // Mobility
-        mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
-                              : count_1s<HasPopCnt>(b & no_mob_area));
+    while (b)
+    {
+        Square s = pop_lsb(&b);

 
 

-        ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
+        assert(pos.pawn_passed(Us, s));

 
 

-        // Decrease score if we are attacked by an enemy pawn. Remaining part
-        // of threat evaluation must be done later when we have full attack info.
-        if (bit_is_set(ei.attackedBy[Them][PAWN], s))
-            ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
+        int r = relative_rank(Us, s) - RANK_2;
+        int rr = r * (r - 1);

 
 

-        // Bishop and knight outposts squares
-        if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Us))
-            evaluate_outposts<Piece, Us>(pos, ei, s);
+        // Base bonus based on rank
+        Value mbonus = Value(17 * rr), ebonus = Value(7 * (rr + r + 1));

 
 

-        // Queen or rook on 7th rank
-        if (  (Piece == ROOK || Piece == QUEEN)
-            && relative_rank(Us, s) == RANK_7
-            && relative_rank(Us, pos.king_square(Them)) == RANK_8)
+        if (rr)

         {
         {

-            ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
-        }
+            Square blockSq = s + pawn_push(Us);

 
 

-        // Special extra evaluation for rooks
-        if (Piece == ROOK)
-        {
-            // Open and half-open files
-            f = square_file(s);
-            if (ei.pi->file_is_half_open(Us, f))
+            // Adjust bonus based on the king's proximity
+            ebonus +=  square_distance(pos.king_square(Them), blockSq) * 5 * rr
+                     - square_distance(pos.king_square(Us  ), blockSq) * 2 * rr;
+
+            // If blockSq is not the queening square then consider also a second push
+            if (relative_rank(Us, blockSq) != RANK_8)
+                ebonus -= square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * rr;
+
+            // If the pawn is free to advance, then increase the bonus
+            if (pos.empty(blockSq))

             {
             {

-                if (ei.pi->file_is_half_open(Them, f))
-                    ei.value += Sign[Us] * RookOpenFileBonus;
-                else
-                    ei.value += Sign[Us] * RookHalfOpenFileBonus;
-            }
+                // If there is a rook or queen attacking/defending the pawn from behind,
+                // consider all the squaresToQueen. Otherwise consider only the squares
+                // in the pawn's path attacked or occupied by the enemy.
+                defendedSquares = unsafeSquares = squaresToQueen = forward_bb(Us, s);

 
 

-            // Penalize rooks which are trapped inside a king. Penalize more if
-            // king has lost right to castle.
-            if (mob > 6 || ei.pi->file_is_half_open(Us, f))
-                continue;
+                Bitboard bb = forward_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);

 
 

-            ksq = pos.king_square(Us);
+                if (!(pos.pieces(Us) & bb))
+                    defendedSquares &= ei.attackedBy[Us][ALL_PIECES];

 
 

-            if (    square_file(ksq) >= FILE_E
-                &&  square_file(s) > square_file(ksq)
-                && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
-            {
-                // Is there a half-open file between the king and the edge of the board?
-                if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
-                    ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
-                                                                         : (TrappedRookPenalty - mob * 16), 0);
-            }
-            else if (    square_file(ksq) <= FILE_D
-                     &&  square_file(s) < square_file(ksq)
-                     && (relative_rank(Us, ksq) == RANK_1 || square_rank(ksq) == square_rank(s)))
-            {
-                // Is there a half-open file between the king and the edge of the board?
-                if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
-                    ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
-                                                                         : (TrappedRookPenalty - mob * 16), 0);
-            }
-        }
-    }
-  }
+                if (!(pos.pieces(Them) & bb))
+                    unsafeSquares &= ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them);

 
 

+                // If there aren't any enemy attacks, assign a big bonus. Otherwise
+                // assign a smaller bonus if the block square isn't attacked.
+                int k = !unsafeSquares ? 15 : !(unsafeSquares & blockSq) ? 9 : 0;

 
 

-  // evaluate_threats<>() assigns bonuses according to the type of attacking piece
-  // and the type of attacked one.
+                // If the path to queen is fully defended, assign a big bonus.
+                // Otherwise assign a smaller bonus if the block square is defended.
+                if (defendedSquares == squaresToQueen)
+                    k += 6;

 
 

-  template<Color Us>
-  void evaluate_threats(const Position& pos, EvalInfo& ei) {
+                else if (defendedSquares & blockSq)
+                    k += 4;

 
 

-    const Color Them = (Us == WHITE ? BLACK : WHITE);
+                mbonus += k * rr, ebonus += k * rr;
+            }
+            else if(pos.pieces(Us) & blockSq)
+                mbonus += rr * 3 + r * 2 + 3, ebonus += rr + r * 2;
+        } // rr != 0

 
 

-    Bitboard b;
-    Score bonus = SCORE_ZERO;
-
-    // Enemy pieces not defended by a pawn and under our attack
-    Bitboard weakEnemies =  pos.pieces_of_color(Them)
-                          & ~ei.attackedBy[Them][PAWN]
-                          & ei.attackedBy[Us][0];
-    if (!weakEnemies)
-        return;
-
-    // Add bonus according to type of attacked enemy pieces and to the
-    // type of attacking piece, from knights to queens. Kings are not
-    // considered because are already special handled in king evaluation.
-    for (PieceType pt1 = KNIGHT; pt1 < KING; pt1++)
-    {
-        b = ei.attackedBy[Us][pt1] & weakEnemies;
-        if (b)
-            for (PieceType pt2 = PAWN; pt2 < KING; pt2++)
-                if (b & pos.pieces(pt2))
-                    bonus += ThreatBonus[pt1][pt2];
+        if (pos.count<PAWN>(Us) < pos.count<PAWN>(Them))
+            ebonus += ebonus / 4;
+
+        score += make_score(mbonus, ebonus);

     }
     }

-    ei.value += Sign[Us] * bonus;
-  }

 
 

+    if (Trace)
+        Tracing::terms[Us][Tracing::PASSED] = apply_weight(score, Weights[PassedPawns]);

 
 

-  // evaluate_pieces_of_color<>() assigns bonuses and penalties to all the
-  // pieces of a given color.
+    // Add the scores to the middlegame and endgame eval
+    return apply_weight(score, Weights[PassedPawns]);
+  }

 
 

-  template<Color Us, bool HasPopCnt>
-  void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {

 
 

-    const Color Them = (Us == WHITE ? BLACK : WHITE);
+  // evaluate_unstoppable_pawns() scores the most advanced among the passed and
+  // candidate pawns. In case both players have no pieces but pawns, this is
+  // somewhat related to the possibility that pawns are unstoppable.

 
 

-    // Do not include in mobility squares protected by enemy pawns or occupied by our pieces
-    const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
+  Score evaluate_unstoppable_pawns(Color us, const EvalInfo& ei) {

 
 

-    evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
-    evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
-    evaluate_pieces<ROOK,   Us, HasPopCnt>(pos, ei, no_mob_area);
-    evaluate_pieces<QUEEN,  Us, HasPopCnt>(pos, ei, no_mob_area);
+    Bitboard b = ei.pi->passed_pawns(us) | ei.pi->candidate_pawns(us);

 
 

-    // Sum up all attacked squares
-    ei.attackedBy[Us][0] =   ei.attackedBy[Us][PAWN]   | ei.attackedBy[Us][KNIGHT]
-                           | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
-                           | ei.attackedBy[Us][QUEEN]  | ei.attackedBy[Us][KING];
+    return b ? Unstoppable * int(relative_rank(us, frontmost_sq(us, b))) : SCORE_ZERO;

   }
 
 
   }
 
 

-  // evaluate_king<>() assigns bonuses and penalties to a king of a given color
-
-  template<Color Us, bool HasPopCnt>
-  void evaluate_king(const Position& pos, EvalInfo& ei) {
+  // evaluate_space() computes the space evaluation for a given side. The
+  // space evaluation is a simple bonus based on the number of safe squares
+  // available for minor pieces on the central four files on ranks 2--4. Safe
+  // squares one, two or three squares behind a friendly pawn are counted
+  // twice. Finally, the space bonus is scaled by a weight taken from the
+  // material hash table. The aim is to improve play on game opening.
+  template<Color Us>
+  int evaluate_space(const Position& pos, const EvalInfo& ei) {

 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 

-    Bitboard undefended, b, b1, b2, safe;
-    bool sente;
-    int attackUnits;
-    const Square ksq = pos.king_square(Us);
+    // Find the safe squares for our pieces inside the area defined by
+    // SpaceMask[]. A square is unsafe if it is attacked by an enemy
+    // pawn, or if it is undefended and attacked by an enemy piece.
+    Bitboard safe =   SpaceMask[Us]
+                   & ~pos.pieces(Us, PAWN)
+                   & ~ei.attackedBy[Them][PAWN]
+                   & (ei.attackedBy[Us][ALL_PIECES] | ~ei.attackedBy[Them][ALL_PIECES]);

 
 

-    // King shelter
-    ei.value += Sign[Us] * ei.pi->king_shelter(pos, Us, ksq);
+    // Find all squares which are at most three squares behind some friendly pawn
+    Bitboard behind = pos.pieces(Us, PAWN);
+    behind |= (Us == WHITE ? behind >>  8 : behind <<  8);
+    behind |= (Us == WHITE ? behind >> 16 : behind << 16);

 
 

-    // King safety. This is quite complicated, and is almost certainly far
-    // from optimally tuned.
-    if (   pos.piece_count(Them, QUEEN) >= 1
-        && ei.kingAttackersCount[Them]  >= 2
-        && pos.non_pawn_material(Them)  >= QueenValueMidgame + RookValueMidgame
-        && ei.kingAdjacentZoneAttacksCount[Them])
-    {
-        // Is it the attackers turn to move?
-        sente = (Them == pos.side_to_move());
+    // Since SpaceMask[Us] is fully on our half of the board
+    assert(unsigned(safe >> (Us == WHITE ? 32 : 0)) == 0);

 
 

-        // Find the attacked squares around the king which has no defenders
-        // apart from the king itself
-        undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
-        undefended &= ~(  ei.attacked_by(Us, PAWN)   | ei.attacked_by(Us, KNIGHT)
-                        | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
-                        | ei.attacked_by(Us, QUEEN));
+    // Count safe + (behind & safe) with a single popcount
+    return popcount<Full>((Us == WHITE ? safe << 32 : safe >> 32) | (behind & safe));
+  }

 
 

-        // Initialize the 'attackUnits' variable, which is used later on as an
-        // index to the KingDangerTable[] array. The initial value is based on
-        // the number and types of the enemy's attacking pieces, the number of
-        // attacked and undefended squares around our king, the square of the
-        // king, and the quality of the pawn shelter.
-        attackUnits =  Min(25, (ei.kingAttackersCount[Them] * ei.kingAttackersWeight[Them]) / 2)
-                     + 3 * (ei.kingAdjacentZoneAttacksCount[Them] + count_1s_max_15<HasPopCnt>(undefended))
-                     + InitKingDanger[relative_square(Us, ksq)]
-                     - mg_value(ei.pi->king_shelter(pos, Us, ksq)) / 32;
-
-        // Analyse enemy's safe queen contact checks. First find undefended
-        // squares around the king attacked by enemy queen...
-        b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
-        if (b)
-        {
-            // ...then remove squares not supported by another enemy piece
-            b &= (  ei.attacked_by(Them, PAWN)   | ei.attacked_by(Them, KNIGHT)
-                  | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK));
-            if (b)
-                attackUnits += QueenContactCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
-        }

 
 

-        // Analyse enemy's safe distance checks for sliders and knights
-        safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
+  // do_evaluate() is the evaluation entry point, called directly from evaluate()

 
 

-        b1 = pos.attacks_from<ROOK>(ksq) & safe;
-        b2 = pos.attacks_from<BISHOP>(ksq) & safe;
+  template<bool Trace>
+  Value do_evaluate(const Position& pos) {

 
 

-        // Enemy queen safe checks
-        b = (b1 | b2) & ei.attacked_by(Them, QUEEN);
-        if (b)
-            attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b);
+    assert(!pos.checkers());

 
 

-        // Enemy rooks safe checks
-        b = b1 & ei.attacked_by(Them, ROOK);
-        if (b)
-            attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b);
+    EvalInfo ei;
+    Score score, mobility[2] = { SCORE_ZERO, SCORE_ZERO };
+    Thread* thisThread = pos.this_thread();

 
 

-        // Enemy bishops safe checks
-        b = b2 & ei.attacked_by(Them, BISHOP);
-        if (b)
-            attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b);
+    // Initialize score by reading the incrementally updated scores included
+    // in the position object (material + piece square tables).
+    // Score is computed from the point of view of white.
+    score = pos.psq_score();

 
 

-        // Enemy knights safe checks
-        b = pos.attacks_from<KNIGHT>(ksq) & ei.attacked_by(Them, KNIGHT) & safe;
-        if (b)
-            attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b);
-
-        // To index KingDangerTable[] attackUnits must be in [0, 99] range
-        attackUnits = Min(99, Max(0, attackUnits));
-
-        // Finally, extract the king danger score from the KingDangerTable[]
-        // array and subtract the score from evaluation. Set also ei.kingDanger[]
-        // value that will be used for pruning because this value can sometimes
-        // be very big, and so capturing a single attacking piece can therefore
-        // result in a score change far bigger than the value of the captured piece.
-        ei.value -= Sign[Us] * KingDangerTable[Us][attackUnits];
-        ei.kingDanger[Us] = mg_value(KingDangerTable[Us][attackUnits]);
-    }
-  }
+    // Probe the material hash table
+    ei.mi = Material::probe(pos, thisThread->materialTable, thisThread->endgames);
+    score += ei.mi->material_value();

 
 

+    // If we have a specialized evaluation function for the current material
+    // configuration, call it and return.
+    if (ei.mi->specialized_eval_exists())
+        return ei.mi->evaluate(pos);

 
 

-  // evaluate_passed_pawns<>() evaluates the passed pawns of the given color
+    // Probe the pawn hash table
+    ei.pi = Pawns::probe(pos, thisThread->pawnsTable);
+    score += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);

 
 

-  template<Color Us>
-  void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
+    // Initialize attack and king safety bitboards
+    init_eval_info<WHITE>(pos, ei);
+    init_eval_info<BLACK>(pos, ei);

 
 

-    const Color Them = (Us == WHITE ? BLACK : WHITE);
+    ei.attackedBy[WHITE][ALL_PIECES] |= ei.attackedBy[WHITE][KING];
+    ei.attackedBy[BLACK][ALL_PIECES] |= ei.attackedBy[BLACK][KING];

 
 

-    Bitboard squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
-    Bitboard b = ei.pi->passed_pawns(Us);
+    // Do not include in mobility squares protected by enemy pawns or occupied by our pawns or king
+    Bitboard mobilityArea[] = { ~(ei.attackedBy[BLACK][PAWN] | pos.pieces(WHITE, PAWN, KING)),
+                                ~(ei.attackedBy[WHITE][PAWN] | pos.pieces(BLACK, PAWN, KING)) };

 
 

-    while (b)
-    {
-        Square s = pop_1st_bit(&b);
+    // Evaluate pieces and mobility
+    score += evaluate_pieces<KNIGHT, WHITE, Trace>(pos, ei, mobility, mobilityArea);
+    score += apply_weight(mobility[WHITE] - mobility[BLACK], Weights[Mobility]);

 
 

-        assert(pos.pawn_is_passed(Us, s));
+    // Evaluate kings after all other pieces because we need complete attack
+    // information when computing the king safety evaluation.
+    score +=  evaluate_king<WHITE, Trace>(pos, ei)
+            - evaluate_king<BLACK, Trace>(pos, ei);

 
 

-        int r = int(relative_rank(Us, s) - RANK_2);
-        int tr = r * (r - 1);
+    // Evaluate tactical threats, we need full attack information including king
+    score +=  evaluate_threats<WHITE, Trace>(pos, ei)
+            - evaluate_threats<BLACK, Trace>(pos, ei);

 
 

-        // Base bonus based on rank
-        Value mbonus = Value(20 * tr);
-        Value ebonus = Value(10 + r * r * 10);
+    // Evaluate passed pawns, we need full attack information including king
+    score +=  evaluate_passed_pawns<WHITE, Trace>(pos, ei)
+            - evaluate_passed_pawns<BLACK, Trace>(pos, ei);

 
 

-        if (tr)
-        {
-            Square blockSq = s + pawn_push(Us);
+    // If both sides have only pawns, score for potential unstoppable pawns
+    if (!pos.non_pawn_material(WHITE) && !pos.non_pawn_material(BLACK))
+        score +=  evaluate_unstoppable_pawns(WHITE, ei)
+                - evaluate_unstoppable_pawns(BLACK, ei);

 
 

-            // Adjust bonus based on kings proximity
-            ebonus -= Value(square_distance(pos.king_square(Us), blockSq) * 3 * tr);
-            ebonus -= Value(square_distance(pos.king_square(Us), blockSq + pawn_push(Us)) * 1 * tr);
-            ebonus += Value(square_distance(pos.king_square(Them), blockSq) * 6 * tr);
+    // Evaluate space for both sides, only in middlegame
+    if (ei.mi->space_weight())
+    {
+        int s = evaluate_space<WHITE>(pos, ei) - evaluate_space<BLACK>(pos, ei);
+        score += apply_weight(s * ei.mi->space_weight(), Weights[Space]);
+    }

 
 

-            // If the pawn is free to advance, increase bonus
-            if (pos.square_is_empty(blockSq))
+    // Scale winning side if position is more drawish than it appears
+    Color strongSide = eg_value(score) > VALUE_DRAW ? WHITE : BLACK;
+    ScaleFactor sf = ei.mi->scale_factor(pos, strongSide);
+
+    // If we don't already have an unusual scale factor, check for certain
+    // types of endgames, and use a lower scale for those.
+    if (    ei.mi->game_phase() < PHASE_MIDGAME
+        && (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN))
+    {
+        if (pos.opposite_bishops()) {
+            // Ignoring any pawns, do both sides only have a single bishop and no
+            // other pieces?
+            if (   pos.non_pawn_material(WHITE) == BishopValueMg
+                && pos.non_pawn_material(BLACK) == BishopValueMg)

             {
             {

-                squaresToQueen = squares_in_front_of(Us, s);
-                defendedSquares = squaresToQueen & ei.attacked_by(Us);
-
-                // If there is an enemy rook or queen attacking the pawn from behind,
-                // add all X-ray attacks by the rook or queen. Otherwise consider only
-                // the squares in the pawn's path attacked or occupied by the enemy.
-                if (   (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them))
-                    && (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<ROOK>(s)))
-                    unsafeSquares = squaresToQueen;
-                else
-                    unsafeSquares = squaresToQueen & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
-
-                // If there aren't enemy attacks or pieces along the path to queen give
-                // huge bonus. Even bigger if we protect the pawn's path.
-                if (!unsafeSquares)
-                    ebonus += Value(tr * (squaresToQueen == defendedSquares ? 17 : 15));
-                else
-                    // OK, there are enemy attacks or pieces (but not pawns). Are those
-                    // squares which are attacked by the enemy also attacked by us ?
-                    // If yes, big bonus (but smaller than when there are no enemy attacks),
-                    // if no, somewhat smaller bonus.
-                    ebonus += Value(tr * ((unsafeSquares & defendedSquares) == unsafeSquares ? 13 : 8));
-
-                // At last, add a small bonus when there are no *friendly* pieces
-                // in the pawn's path.
-                if (!(squaresToQueen & pos.pieces_of_color(Us)))
-                    ebonus += Value(tr);
+                // Check for KBP vs KB with only a single pawn that is almost
+                // certainly a draw or at least two pawns.
+                bool one_pawn = (pos.count<PAWN>(WHITE) + pos.count<PAWN>(BLACK) == 1);
+                sf = one_pawn ? ScaleFactor(8) : ScaleFactor(32);

             }
             }

-        } // tr != 0
-
-        // Increase the bonus if the passed pawn is supported by a friendly pawn
-        // on the same rank and a bit smaller if it's on the previous rank.
-        supportingPawns = pos.pieces(PAWN, Us) & neighboring_files_bb(s);
-        if (supportingPawns & rank_bb(s))
-            ebonus += Value(r * 20);
-        else if (supportingPawns & rank_bb(s - pawn_push(Us)))
-            ebonus += Value(r * 12);
-
-        // Rook pawns are a special case: They are sometimes worse, and
-        // sometimes better than other passed pawns. It is difficult to find
-        // good rules for determining whether they are good or bad. For now,
-        // we try the following: Increase the value for rook pawns if the
-        // other side has no pieces apart from a knight, and decrease the
-        // value if the other side has a rook or queen.
-        if (square_file(s) == FILE_A || square_file(s) == FILE_H)
-        {
-            if (pos.non_pawn_material(Them) <= KnightValueMidgame)
-                ebonus += ebonus / 4;
-            else if (pos.pieces(ROOK, QUEEN, Them))
-                ebonus -= ebonus / 4;
+            else
+                // Endgame with opposite-colored bishops, but also other pieces. Still
+                // a bit drawish, but not as drawish as with only the two bishops.
+                 sf = ScaleFactor(50 * sf / SCALE_FACTOR_NORMAL);
+        } else if (    abs(eg_value(score)) <= BishopValueEg
+                   &&  ei.pi->pawn_span(strongSide) <= 1
+                   && !pos.pawn_passed(~strongSide, pos.king_square(~strongSide))) {
+            // Endings where weaker side can be place his king in front of the opponent's pawns are drawish.
+            sf = ScaleFactor(ScalePawnSpan[ei.pi->pawn_span(strongSide)]);

         }
         }

+    }

 
 

-        // Add the scores for this pawn to the middle game and endgame eval
-        ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), Weights[PassedPawns]);
+    // Interpolate between a middlegame and a (scaled by 'sf') endgame score
+    Value v =  mg_value(score) * int(ei.mi->game_phase())
+             + eg_value(score) * int(PHASE_MIDGAME - ei.mi->game_phase()) * sf / SCALE_FACTOR_NORMAL;

 
 

-    } // while
-  }
+    v /= int(PHASE_MIDGAME);

 
 

+    // In case of tracing add all single evaluation contributions for both white and black
+    if (Trace)
+    {
+        Tracing::add_term(Tracing::MATERIAL, pos.psq_score());
+        Tracing::add_term(Tracing::IMBALANCE, ei.mi->material_value());
+        Tracing::add_term(PAWN, ei.pi->pawns_value());
+        Tracing::add_term(Tracing::MOBILITY, apply_weight(mobility[WHITE], Weights[Mobility])
+                                           , apply_weight(mobility[BLACK], Weights[Mobility]));
+        Score w = ei.mi->space_weight() * evaluate_space<WHITE>(pos, ei);
+        Score b = ei.mi->space_weight() * evaluate_space<BLACK>(pos, ei);
+        Tracing::add_term(Tracing::SPACE, apply_weight(w, Weights[Space]), apply_weight(b, Weights[Space]));
+        Tracing::add_term(Tracing::TOTAL, score);
+        Tracing::ei = ei;
+        Tracing::sf = sf;
+    }

 
 

-  // evaluate_space() computes the space evaluation for a given side. The
-  // space evaluation is a simple bonus based on the number of safe squares
-  // available for minor pieces on the central four files on ranks 2--4. Safe
-  // squares one, two or three squares behind a friendly pawn are counted
-  // twice. Finally, the space bonus is scaled by a weight taken from the
-  // material hash table.
-  template<Color Us, bool HasPopCnt>
-  int evaluate_space(const Position& pos, EvalInfo& ei) {
+    return pos.side_to_move() == WHITE ? v : -v;
+  }

 
 

-    const Color Them = (Us == WHITE ? BLACK : WHITE);

 
 

-    // Find the safe squares for our pieces inside the area defined by
-    // SpaceMask[us]. A square is unsafe if it is attacked by an enemy
-    // pawn, or if it is undefended and attacked by an enemy piece.
-    Bitboard safe =   SpaceMask[Us]
-                   & ~pos.pieces(PAWN, Us)
-                   & ~ei.attacked_by(Them, PAWN)
-                   & (ei.attacked_by(Us) | ~ei.attacked_by(Them));
+  // Tracing function definitions

 
 

-    // Find all squares which are at most three squares behind some friendly pawn
-    Bitboard behind = pos.pieces(PAWN, Us);
-    behind |= (Us == WHITE ? behind >>  8 : behind <<  8);
-    behind |= (Us == WHITE ? behind >> 16 : behind << 16);
+  double Tracing::to_cp(Value v) { return double(v) / PawnValueEg; }
+
+  void Tracing::add_term(int idx, Score wScore, Score bScore) {

 
 

-    return count_1s_max_15<HasPopCnt>(safe) + count_1s_max_15<HasPopCnt>(behind & safe);
+    terms[WHITE][idx] = wScore;
+    terms[BLACK][idx] = bScore;

   }
 
   }
 

+  void Tracing::format_row(std::stringstream& ss, const char* name, int idx) {
+
+    Score wScore = terms[WHITE][idx];
+    Score bScore = terms[BLACK][idx];
+
+    switch (idx) {
+    case MATERIAL: case IMBALANCE: case PAWN: case TOTAL:
+        ss << std::setw(15) << name << " |   ---   --- |   ---   --- | "
+           << std::setw(5)  << to_cp(mg_value(wScore - bScore)) << " "
+           << std::setw(5)  << to_cp(eg_value(wScore - bScore)) << " \n";
+        break;
+    default:
+        ss << std::setw(15) << name << " | " << std::noshowpos
+           << std::setw(5)  << to_cp(mg_value(wScore)) << " "
+           << std::setw(5)  << to_cp(eg_value(wScore)) << " | "
+           << std::setw(5)  << to_cp(mg_value(bScore)) << " "
+           << std::setw(5)  << to_cp(eg_value(bScore)) << " | "
+           << std::setw(5)  << to_cp(mg_value(wScore - bScore)) << " "
+           << std::setw(5)  << to_cp(eg_value(wScore - bScore)) << " \n";
+    }
+  }

 
 

-  // apply_weight() applies an evaluation weight to a value trying to prevent overflow
+  std::string Tracing::do_trace(const Position& pos) {

 
 

-  inline Score apply_weight(Score v, Score w) {
-      return make_score((int(mg_value(v)) * mg_value(w)) / 0x100, (int(eg_value(v)) * eg_value(w)) / 0x100);
-  }
+    std::memset(terms, 0, sizeof(terms));

 
 

+    Value v = do_evaluate<true>(pos);
+    v = pos.side_to_move() == WHITE ? v : -v; // White's point of view

 
 

-  // 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.
+    std::stringstream ss;
+    ss << std::showpoint << std::noshowpos << std::fixed << std::setprecision(2)
+       << "      Eval term |    White    |    Black    |    Total    \n"
+       << "                |   MG    EG  |   MG    EG  |   MG    EG  \n"
+       << "----------------+-------------+-------------+-------------\n";

 
 

-  Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]) {
+    format_row(ss, "Material", MATERIAL);
+    format_row(ss, "Imbalance", IMBALANCE);
+    format_row(ss, "Pawns", PAWN);
+    format_row(ss, "Knights", KNIGHT);
+    format_row(ss, "Bishops", BISHOP);
+    format_row(ss, "Rooks", ROOK);
+    format_row(ss, "Queens", QUEEN);
+    format_row(ss, "Mobility", MOBILITY);
+    format_row(ss, "King safety", KING);
+    format_row(ss, "Threats", THREAT);
+    format_row(ss, "Passed pawns", PASSED);
+    format_row(ss, "Space", SPACE);

 
 

-    assert(mg_value(v) > -VALUE_INFINITE && mg_value(v) < VALUE_INFINITE);
-    assert(eg_value(v) > -VALUE_INFINITE && eg_value(v) < VALUE_INFINITE);
-    assert(ph >= PHASE_ENDGAME && ph <= PHASE_MIDGAME);
+    ss << "----------------+-------------+-------------+-------------\n";
+    format_row(ss, "Total", TOTAL);

 
 

-    Value eg = eg_value(v);
-    ScaleFactor f = sf[eg > VALUE_ZERO ? WHITE : BLACK];
-    Value ev = Value((eg * int(f)) / SCALE_FACTOR_NORMAL);
+    ss << "\nTotal Evaluation: " << to_cp(v) << " (white side)\n";

 
 

-    int result = (mg_value(v) * int(ph) + ev * int(128 - ph)) / 128;
-    return Value(result & ~(GrainSize - 1));
+    return ss.str();

   }
 
   }
 

+} // namespace

 
 

-  // weight_option() computes the value of an evaluation weight, by combining
-  // two UCI-configurable weights (midgame and endgame) with an internal weight.

 
 

-  Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight) {
+namespace Eval {

 
 

-    // Scale option value from 100 to 256
-    int mg = get_option_value_int(mgOpt) * 256 / 100;
-    int eg = get_option_value_int(egOpt) * 256 / 100;
+  /// evaluate() is the main evaluation function. It returns a static evaluation
+  /// of the position always from the point of view of the side to move.

 
 

-    return apply_weight(make_score(mg, eg), internalWeight);
+  Value evaluate(const Position& pos) {
+    return do_evaluate<false>(pos) + Tempo;

   }
 
   }
 

-  // init_safety() initizes the king safety evaluation, based on UCI
-  // parameters. It is called from read_weights().

 
 

-  void init_safety() {
+  /// trace() is like evaluate(), but instead of returning a value, it returns
+  /// a string (suitable for outputting to stdout) that contains the detailed
+  /// descriptions and values of each evaluation term. It's mainly used for
+  /// debugging.
+  std::string trace(const Position& pos) {
+    return Tracing::do_trace(pos);
+  }

 
 

-    const Value MaxSlope = Value(30);
-    const Value Peak = Value(1280);
-    Value t[100];

 
 

-    // First setup the base table
-    for (int i = 0; i < 100; i++)
-    {
-        t[i] = Value(int(0.4 * i * i));
+  /// init() computes evaluation weights from the corresponding UCI parameters
+  /// and setup king tables.

 
 

-        if (i > 0)
-            t[i] = Min(t[i], t[i - 1] + MaxSlope);
+  void init() {

 
 

-        t[i] = Min(t[i], Peak);
-    }
+    const double MaxSlope = 30;
+    const double Peak = 1280;

 
 

-    // Then apply the weights and get the final KingDangerTable[] array
-    for (Color c = WHITE; c <= BLACK; c++)
-        for (int i = 0; i < 100; i++)
-            KingDangerTable[c][i] = apply_weight(make_score(t[i], 0), Weights[KingDangerUs + c]);
+    for (int t = 0, i = 1; i < 100; ++i)
+    {
+        t = int(std::min(Peak, std::min(0.4 * i * i, t + MaxSlope)));
+        KingDanger[i] = apply_weight(make_score(t, 0), Weights[KingSafety]);
+    }

   }
   }

-}
+
+} // namespace Eval