X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fpawns.cpp;h=d65b0418f0145f448c3d37dff8ecb7262c86fdaf;hp=ea5f9287c2940ef820efc93498333cdfed45b6fb;hb=49e110c52b19f5c99954d4797b8e991b0b60007c;hpb=b2fadf32aa57012f2140bc32d5f2433efae3e730
diff --git a/src/pawns.cpp b/src/pawns.cpp
index ea5f9287..d65b0418 100644
--- a/src/pawns.cpp
+++ b/src/pawns.cpp
@@ -17,6 +17,7 @@
along with this program. If not, see .
*/
+#include
#include
#include "bitboard.h"
@@ -62,15 +63,16 @@ namespace {
S(34,68), S(83,166), S(0, 0), S( 0, 0)
};
- // Weakness of our pawn shelter in front of the king indexed by [king pawn][rank]
- const Value ShelterWeakness[2][RANK_NB] =
- { { V(141), V(0), V(38), V(102), V(128), V(141), V(141) },
- { V( 61), V(0), V(16), V( 44), V( 56), V( 61), V( 61) } };
+ // Weakness of our pawn shelter in front of the king indexed by [rank]
+ const Value ShelterWeakness[RANK_NB] =
+ { V(100), V(0), V(27), V(73), V(92), V(101), V(101) };
- // Danger of enemy pawns moving toward our king indexed by [pawn blocked][rank]
- const Value StormDanger[2][RANK_NB] =
- { { V(26), V(0), V(128), V(51), V(26) },
- { V(13), V(0), V( 64), V(25), V(13) } };
+ // Danger of enemy pawns moving toward our king indexed by
+ // [no friendly pawn | pawn unblocked | pawn blocked][rank of enemy pawn]
+ const Value StormDanger[3][RANK_NB] = {
+ { V( 0), V(64), V(128), V(51), V(26) },
+ { V(26), V(32), V( 96), V(38), V(20) },
+ { V( 0), V( 0), V( 64), V(25), V(13) }};
// Max bonus for king safety. Corresponds to start position with all the pawns
// in front of the king and no enemy pawn on the horizont.
@@ -90,7 +92,6 @@ namespace {
Bitboard b;
Square s;
File f;
- Rank r;
bool passed, isolated, doubled, opposed, chain, backward, candidate;
Score value = SCORE_ZERO;
const Square* pl = pos.list(Us);
@@ -102,7 +103,7 @@ namespace {
e->kingSquares[Us] = SQ_NONE;
e->semiopenFiles[Us] = 0xFF;
e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_bb(ourPawns);
- e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & BlackSquares);
+ e->pawnsOnSquares[Us][BLACK] = popcount(ourPawns & DarkSquares);
e->pawnsOnSquares[Us][WHITE] = pos.count(Us) - e->pawnsOnSquares[Us][BLACK];
// Loop through all pawns of the current color and score each pawn
@@ -111,13 +112,12 @@ namespace {
assert(pos.piece_on(s) == make_piece(Us, PAWN));
f = file_of(s);
- r = rank_of(s);
// This file cannot be semi-open
e->semiopenFiles[Us] &= ~(1 << f);
// Our rank plus previous one. Used for chain detection
- b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
+ b = rank_bb(s) | rank_bb(s - pawn_push(Us));
// Flag the pawn as passed, isolated, doubled or member of a pawn
// chain (but not the backward one).
@@ -127,29 +127,25 @@ namespace {
opposed = theirPawns & forward_bb(Us, s);
passed = !(theirPawns & passed_pawn_mask(Us, s));
- // Test for backward pawn
- backward = false;
-
+ // Test for backward pawn.
// If the pawn is passed, isolated, or member of a pawn chain it cannot
// be backward. If there are friendly pawns behind on adjacent files
// or if can capture an enemy pawn it cannot be backward either.
- if ( !(passed | isolated | chain)
- && !(ourPawns & pawn_attack_span(Them, s))
- && !(pos.attacks_from(s, Us) & theirPawns))
+ if ( (passed | isolated | chain)
+ || (ourPawns & pawn_attack_span(Them, s))
+ || (pos.attacks_from(s, Us) & theirPawns))
+ backward = false;
+ else
{
// We now know that there are no friendly pawns beside or behind this
// pawn on adjacent files. We now check whether the pawn is
// backward by looking in the forward direction on the adjacent
- // files, and seeing whether we meet a friendly or an enemy pawn first.
- b = pos.attacks_from(s, Us);
-
- // Note that we are sure to find something because pawn is not passed
- // nor isolated, so loop is potentially infinite, but it isn't.
- while (!(b & (ourPawns | theirPawns)))
- b = shift_bb(b);
+ // files, and picking the closest pawn there.
+ b = pawn_attack_span(Us, s) & (ourPawns | theirPawns);
+ b = pawn_attack_span(Us, s) & rank_bb(backmost_sq(Us, b));
- // The friendly pawn needs to be at least two ranks closer than the
- // enemy pawn in order to help the potentially backward pawn advance.
+ // If we have an enemy pawn in the same or next rank, the pawn is
+ // backward because it cannot advance without being captured.
backward = (b | shift_bb(b)) & theirPawns;
}
@@ -220,25 +216,21 @@ Value Entry::shelter_storm(const Position& pos, Square ksq) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
Value safety = MaxSafetyBonus;
- Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, ksq) | rank_bb(ksq));
- Bitboard ourPawns = b & pos.pieces(Us) & ~rank_bb(ksq);
+ Bitboard b = pos.pieces(PAWN) & (in_front_bb(Us, rank_of(ksq)) | rank_bb(ksq));
+ Bitboard ourPawns = b & pos.pieces(Us);
Bitboard theirPawns = b & pos.pieces(Them);
Rank rkUs, rkThem;
- File kf = file_of(ksq);
-
- kf = (kf == FILE_A) ? FILE_B : (kf == FILE_H) ? FILE_G : kf;
+ File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
for (int f = kf - 1; f <= kf + 1; f++)
{
- // Shelter penalty is higher for the pawn in front of the king
b = ourPawns & FileBB[f];
- rkUs = b ? rank_of(Us == WHITE ? lsb(b) : ~msb(b)) : RANK_1;
- safety -= ShelterWeakness[f != kf][rkUs];
+ rkUs = b ? relative_rank(Us, backmost_sq(Us, b)) : RANK_1;
+ safety -= ShelterWeakness[rkUs];
- // Storm danger is smaller if enemy pawn is blocked
b = theirPawns & FileBB[f];
- rkThem = b ? rank_of(Us == WHITE ? lsb(b) : ~msb(b)) : RANK_1;
- safety -= StormDanger[rkThem == rkUs + 1][rkThem];
+ rkThem = b ? relative_rank(Us, frontmost_sq(Them, b)) : RANK_1;
+ safety -= StormDanger[rkUs == RANK_1 ? 0 : rkThem == rkUs + 1 ? 2 : 1][rkThem];
}
return safety;