Always scale using pawn contribution

[stockfish] / src / material.cpp

diff --git a/src/material.cpp b/src/material.cpp
index c0237e7cac7507f3442977d0ffc153c3058544ef..b18d29d06b28715fec73884130ed2cd11260921f 100644 (file)
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -31,7 +31,7 @@ namespace {
 
   // Polynomial material imbalance parameters
 
-  const int QuadraticOurs[][PIECE_TYPE_NB] = {
+  constexpr int QuadraticOurs[][PIECE_TYPE_NB] = {
     //            OUR PIECES
     // pair pawn knight bishop rook queen
     {1667                               }, // Bishop pair
@@ -39,10 +39,10 @@ namespace {
     {  32,  255,  -3                    }, // Knight      OUR PIECES
     {   0,  104,   4,    0              }, // Bishop
     { -26,   -2,  47,   105,  -149      }, // Rook
-    {-185,   24, 122,   137,  -134,   0 }  // Queen
+    {-189,   24, 117,   133,  -134, -10 }  // Queen
   };
 
-  const int QuadraticTheirs[][PIECE_TYPE_NB] = {
+  constexpr int QuadraticTheirs[][PIECE_TYPE_NB] = {
     //           THEIR PIECES
     // pair pawn knight bishop rook queen
     {   0                               }, // Bishop pair
@@ -50,13 +50,7 @@ namespace {
     {   9,   63,   0                    }, // Knight      OUR PIECES
     {  59,   65,  42,     0             }, // Bishop
     {  46,   39,  24,   -24,    0       }, // Rook
-    { 101,  100, -37,   141,  268,    0 }  // Queen
-  };
-
-  // QueenMinorsImbalance[opp_minor_count] is applied when only one side has a queen.
-  // It contains a bonus/malus for the side with the queen.
-  const int QueenMinorsImbalance[13] = {
-    31, -8, -15, -25, -5
+    {  97,  100, -42,   137,  268,    0 }  // Queen
   };
 
   // Endgame evaluation and scaling functions are accessed directly and not through
@@ -74,7 +68,7 @@ namespace {
           && pos.non_pawn_material(us) >= RookValueMg;
   }
 
-  bool is_KBPsKs(const Position& pos, Color us) {
+  bool is_KBPsK(const Position& pos, Color us) {
     return   pos.non_pawn_material(us) == BishopValueMg
           && pos.count<BISHOP>(us) == 1
           && pos.count<PAWN  >(us) >= 1;
@@ -93,7 +87,7 @@ namespace {
   template<Color Us>
   int imbalance(const int pieceCount[][PIECE_TYPE_NB]) {
 
-    const Color Them = (Us == WHITE ? BLACK : WHITE);
+    constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
 
     int bonus = 0;
 
@@ -112,10 +106,6 @@ namespace {
         bonus += pieceCount[Us][pt1] * v;
     }
 
-    // Special handling of Queen vs. Minors
-    if  (pieceCount[Us][QUEEN] == 1 && pieceCount[Them][QUEEN] == 0)
-         bonus += QueenMinorsImbalance[pieceCount[Them][KNIGHT] + pieceCount[Them][BISHOP]];
-
     return bonus;
   }
 
@@ -175,7 +165,7 @@ Entry* probe(const Position& pos) {
   // case we don't return after setting the function.
   for (Color c = WHITE; c <= BLACK; ++c)
   {
-    if (is_KBPsKs(pos, c))
+    if (is_KBPsK(pos, c))
         e->scalingFunction[c] = &ScaleKBPsK[c];
 
     else if (is_KQKRPs(pos, c))
@@ -216,22 +206,16 @@ Entry* probe(const Position& pos) {
       e->factor[BLACK] = uint8_t(npm_b <  RookValueMg   ? SCALE_FACTOR_DRAW :
                                  npm_w <= BishopValueMg ? 4 : 14);
 
-  if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
-      e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;
-
-  if (pos.count<PAWN>(BLACK) == 1 && npm_b - npm_w <= BishopValueMg)
-      e->factor[BLACK] = (uint8_t) SCALE_FACTOR_ONEPAWN;
-
   // Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder
   // for the bishop pair "extended piece", which allows us to be more flexible
   // in defining bishop pair bonuses.
-  const int PieceCount[COLOR_NB][PIECE_TYPE_NB] = {
+  const int pieceCount[COLOR_NB][PIECE_TYPE_NB] = {
   { pos.count<BISHOP>(WHITE) > 1, pos.count<PAWN>(WHITE), pos.count<KNIGHT>(WHITE),
     pos.count<BISHOP>(WHITE)    , pos.count<ROOK>(WHITE), pos.count<QUEEN >(WHITE) },
   { pos.count<BISHOP>(BLACK) > 1, pos.count<PAWN>(BLACK), pos.count<KNIGHT>(BLACK),
     pos.count<BISHOP>(BLACK)    , pos.count<ROOK>(BLACK), pos.count<QUEEN >(BLACK) } };
 
-  e->value = int16_t((imbalance<WHITE>(PieceCount) - imbalance<BLACK>(PieceCount)) / 16);
+  e->value = int16_t((imbalance<WHITE>(pieceCount) - imbalance<BLACK>(pieceCount)) / 16);
   return e;
 }