X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmaterial.cpp;h=2f6af13f462c4dda354d5ef1edf2e970b7a6b56c;hp=a1eff233302982c1a6728da40c603075864dc5a2;hb=a89b26bedd7e07f23c8292dcdccbd527c68d56f4;hpb=153309e28702d8e5f49f4772bfb61f9f9ed965fc

diff --git a/src/material.cpp b/src/material.cpp
index a1eff233..2f6af13f 100644
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -31,13 +31,10 @@ namespace {
   const Value MidgameLimit = Value(15581);
   const Value EndgameLimit = Value(3998);
 
-  // Scale factors used when one side has no more pawns
-  const int NoPawnsSF[4] = { 6, 12, 32 };
-
   // Polynomial material balance parameters
 
   //                                  pair  pawn knight bishop rook queen
-  const int LinearCoefficients[6] = { 1852, -162, -1122, -183,  249, -52 };
+  const int LinearCoefficients[6] = { 1852, -162, -1122, -183,  249, -154 };
 
   const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = {
     // pair pawn knight bishop rook queen
@@ -46,7 +43,7 @@ namespace {
     {  35,  271,  -4                    }, // Knight
     {   0,  105,   4,    0              }, // Bishop
     { -27,   -2,  46,   100,  -141      }, // Rook
-    {  58,   29,  83,   148,  -163,   0 }  // Queen
+    {-177,   25, 129,   142,  -137,   0 }  // Queen
   };
 
   const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = {
@@ -57,12 +54,11 @@ namespace {
     {  10,   62,   0                    }, // Knight      OUR PIECES
     {  57,   64,  39,     0             }, // Bishop
     {  50,   40,  23,   -22,    0       }, // Rook
-    { 106,  101,   3,   151,  171,    0 }  // Queen
+    {  98,  105, -39,   141,  274,    0 }  // Queen
   };
 
   // Endgame evaluation and scaling functions are accessed directly and not through
-  // the function maps because they correspond to more then one material hash key.
-  Endgame<KmmKm> EvaluateKmmKm[] = { Endgame<KmmKm>(WHITE), Endgame<KmmKm>(BLACK) };
+  // the function maps because they correspond to more than one material hash key.
   Endgame<KXK>   EvaluateKXK[]   = { Endgame<KXK>(WHITE),   Endgame<KXK>(BLACK) };
 
   Endgame<KBPsK>  ScaleKBPsK[]  = { Endgame<KBPsK>(WHITE),  Endgame<KBPsK>(BLACK) };
@@ -119,6 +115,7 @@ namespace {
 
         value += pc * v;
     }
+
     return value;
   }
 
@@ -165,21 +162,6 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
       return e;
   }
 
-  if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN))
-  {
-      // Minor piece endgame with at least one minor piece per side and
-      // no pawns. Note that the case KmmK is already handled by KXK.
-      assert((pos.pieces(WHITE, KNIGHT) | pos.pieces(WHITE, BISHOP)));
-      assert((pos.pieces(BLACK, KNIGHT) | pos.pieces(BLACK, BISHOP)));
-
-      if (   pos.count<BISHOP>(WHITE) + pos.count<KNIGHT>(WHITE) <= 2
-          && pos.count<BISHOP>(BLACK) + pos.count<KNIGHT>(BLACK) <= 2)
-      {
-          e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
-          return e;
-      }
-  }
-
   // OK, we didn't find any special evaluation function for the current
   // material configuration. Is there a suitable scaling function?
   //
@@ -193,7 +175,7 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
       return e;
   }
 
-  // Generic scaling functions that refer to more then one material
+  // Generic scaling functions that refer to more than one material
   // distribution. They should be probed after the specialized ones.
   // Note that these ones don't return after setting the function.
   if (is_KBPsKs<WHITE>(pos))
@@ -211,7 +193,7 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
   Value npm_w = pos.non_pawn_material(WHITE);
   Value npm_b = pos.non_pawn_material(BLACK);
 
-  if (npm_w + npm_b == VALUE_ZERO)
+  if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN))
   {
       if (!pos.count<PAWN>(BLACK))
       {
@@ -233,28 +215,19 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) {
   }
 
   // No pawns makes it difficult to win, even with a material advantage. This
-  // catches some trivial draws like KK, KBK and KNK
+  // catches some trivial draws like KK, KBK and KNK and gives a very drawish
+  // scale factor for cases such as KRKBP and KmmKm (except for KBBKN).
   if (!pos.count<PAWN>(WHITE) && npm_w - npm_b <= BishopValueMg)
-  {
-      e->factor[WHITE] = (uint8_t)
-      (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(WHITE), 2)]);
-  }
+      e->factor[WHITE] = uint8_t(npm_w < RookValueMg ? SCALE_FACTOR_DRAW : npm_b <= BishopValueMg ? 4 : 12);
 
   if (!pos.count<PAWN>(BLACK) && npm_b - npm_w <= BishopValueMg)
-  {
-      e->factor[BLACK] = (uint8_t)
-      (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(BLACK), 2)]);
-  }
+      e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW : npm_w <= BishopValueMg ? 4 : 12);
 
   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;
-  }
 
   // Compute the space weight
   if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg)