X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=8b997b6056b99e8a55208fb980bd8312849cbca6;hp=6664742e5641c47386e6b6dff7d67995987340ce;hb=4d647428d8f6b02a404e6b7fda5dbbf17090f271;hpb=12ef8f71a2822f91e844e26d352d5fc27ac9559f

diff --git a/src/pawns.cpp b/src/pawns.cpp
index 6664742e..8b997b60 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -116,22 +116,10 @@ namespace {
         phalanx    = neighbours & rank_bb(s);
         supported  = neighbours & rank_bb(s - Up);
 
-        // A pawn is backward when it is behind all pawns of the same color on the
-        // adjacent files and cannot be safely advanced.
-        if (!neighbours || lever || relative_rank(Us, s) >= RANK_5)
-            backward = false;
-        else
-        {
-            // Find the backmost rank with neighbours or stoppers
-            b = rank_bb(backmost_sq(Us, neighbours | stoppers));
-
-            // The pawn is backward when it cannot safely progress to that rank:
-            // either there is a stopper in the way on this rank, or there is a
-            // stopper on adjacent file which controls the way to that rank.
-            backward = (b | shift<Up>(b & adjacent_files_bb(f))) & stoppers;
-
-            assert(!(backward && (forward_ranks_bb(Them, s + Up) & neighbours)));
-        }
+        // A pawn is backward when it is behind all pawns of the same color
+        // on the adjacent files and cannot be safely advanced.
+        backward =  !(ourPawns & pawn_attack_span(Them, s + Up))
+                  && (stoppers & (leverPush | (s + Up)));
 
         // Passed pawns will be properly scored in evaluation because we need
         // full attack info to evaluate them. Include also not passed pawns
@@ -179,7 +167,7 @@ namespace Pawns {
 
 void init() {
 
-  static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 76, 100, 175, 330 };
+  static constexpr int Seed[RANK_NB] = { 0, 13, 24, 18, 65, 100, 175, 330 };
 
   for (int opposed = 0; opposed <= 1; ++opposed)
       for (int phalanx = 0; phalanx <= 1; ++phalanx)
@@ -226,8 +214,8 @@ Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
 
   enum { Unopposed, BlockedByPawn, Unblocked };
   constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
-  constexpr Direction Up   = (Us == WHITE ? NORTH : SOUTH);
-  constexpr Bitboard  BlockRanks = (Us == WHITE ? Rank2BB | Rank3BB : Rank7BB | Rank6BB);
+  constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
+  constexpr Bitboard  BlockRanks = (Us == WHITE ? Rank1BB | Rank2BB : Rank8BB | Rank7BB);
 
   Bitboard b = pos.pieces(PAWN) & (forward_ranks_bb(Us, ksq) | rank_bb(ksq));
   Bitboard ourPawns = b & pos.pieces(Us);
@@ -235,7 +223,7 @@ Value Entry::evaluate_shelter(const Position& pos, Square ksq) {
 
   Value safety = (ourPawns & file_bb(ksq)) ? Value(5) : Value(-5);
 
-  if ((theirPawns & (FileABB | FileHBB) & BlockRanks) & (ksq + Up))
+  if (shift<Down>(theirPawns) & (FileABB | FileHBB) & BlockRanks & ksq)
       safety += 374;
 
   File center = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));