X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=sidebyside;f=src%2Fpawns.cpp;h=37db2cf513e0babdc11b7235da701dfa3311c840;hb=984ee9d05b6b1916e564047b2a0b8f117f911bca;hp=fca33f281a2bb69c6641d6f0c519b50a40c9dadf;hpb=c5ec94d0f1b128fc2c691c7231663a345409d5cc;p=stockfish
diff --git a/src/pawns.cpp b/src/pawns.cpp
index fca33f28..37db2cf5 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"
@@ -30,49 +31,48 @@ namespace {
#define S(mg, eg) make_score(mg, eg)
// Doubled pawn penalty by opposed flag and file
- const Score DoubledPawnPenalty[2][FILE_NB] = {
+ const Score Doubled[2][FILE_NB] = {
{ S(13, 43), S(20, 48), S(23, 48), S(23, 48),
S(23, 48), S(23, 48), S(20, 48), S(13, 43) },
{ S(13, 43), S(20, 48), S(23, 48), S(23, 48),
S(23, 48), S(23, 48), S(20, 48), S(13, 43) }};
// Isolated pawn penalty by opposed flag and file
- const Score IsolatedPawnPenalty[2][FILE_NB] = {
+ const Score Isolated[2][FILE_NB] = {
{ S(37, 45), S(54, 52), S(60, 52), S(60, 52),
S(60, 52), S(60, 52), S(54, 52), S(37, 45) },
{ S(25, 30), S(36, 35), S(40, 35), S(40, 35),
S(40, 35), S(40, 35), S(36, 35), S(25, 30) }};
// Backward pawn penalty by opposed flag and file
- const Score BackwardPawnPenalty[2][FILE_NB] = {
+ const Score Backward[2][FILE_NB] = {
{ S(30, 42), S(43, 46), S(49, 46), S(49, 46),
S(49, 46), S(49, 46), S(43, 46), S(30, 42) },
{ S(20, 28), S(29, 31), S(33, 31), S(33, 31),
S(33, 31), S(33, 31), S(29, 31), S(20, 28) }};
// Pawn chain membership bonus by file
- const Score ChainBonus[FILE_NB] = {
+ const Score ChainMember[FILE_NB] = {
S(11,-1), S(13,-1), S(13,-1), S(14,-1),
S(14,-1), S(13,-1), S(13,-1), S(11,-1)
};
// Candidate passed pawn bonus by rank
- const Score CandidateBonus[RANK_NB] = {
+ const Score CandidatePassed[RANK_NB] = {
S( 0, 0), S( 6, 13), S(6,13), S(14,29),
S(34,68), S(83,166), S(0, 0), S( 0, 0)
};
- const Score PawnStructureWeight = S(233, 201);
+ // 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) };
- // 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) } };
-
- // 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.
@@ -82,18 +82,29 @@ namespace {
#undef V
template
- Score evaluate_pawns(const Position& pos, Bitboard ourPawns,
- Bitboard theirPawns, Pawns::Entry* e) {
+ Score evaluate(const Position& pos, Pawns::Entry* e) {
- const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+ const Square Up = (Us == WHITE ? DELTA_N : DELTA_S);
+ const Square Right = (Us == WHITE ? DELTA_NE : DELTA_SW);
+ const Square Left = (Us == WHITE ? DELTA_NW : DELTA_SE);
Bitboard b;
Square s;
File f;
- Rank r;
bool passed, isolated, doubled, opposed, chain, backward, candidate;
Score value = SCORE_ZERO;
- const Square* pl = pos.piece_list(Us, PAWN);
+ const Square* pl = pos.list(Us);
+
+ Bitboard ourPawns = pos.pieces(Us, PAWN);
+ Bitboard theirPawns = pos.pieces(Them, PAWN);
+
+ e->passedPawns[Us] = e->candidatePawns[Us] = 0;
+ e->kingSquares[Us] = SQ_NONE;
+ e->semiopenFiles[Us] = 0xFF;
+ e->pawnAttacks[Us] = shift_bb(ourPawns) | shift_bb(ourPawns);
+ 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
while ((s = *pl++) != SQ_NONE)
@@ -101,13 +112,12 @@ namespace {
assert(pos.piece_on(s) == make_piece(Us, PAWN));
f = file_of(s);
- r = rank_of(s);
- // This file cannot be half open
- e->halfOpenFiles[Us] &= ~(1 << f);
+ // 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).
@@ -117,41 +127,37 @@ 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 & attack_span_mask(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);
+ // 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));
- // 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)))
- Us == WHITE ? b <<= 8 : b >>= 8;
-
- // The friendly pawn needs to be at least two ranks closer than the
- // enemy pawn in order to help the potentially backward pawn advance.
- backward = (b | (Us == WHITE ? b << 8 : b >> 8)) & theirPawns;
+ // 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;
}
- assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns));
+ assert(opposed | passed | (pawn_attack_span(Us, s) & theirPawns));
// A not passed pawn is a candidate to become passed if it is free to
// advance and if the number of friendly pawns beside or behind this
// pawn on adjacent files is higher or equal than the number of
// enemy pawns in the forward direction on the adjacent files.
candidate = !(opposed | passed | backward | isolated)
- && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != 0
- && popcount(b) >= popcount(attack_span_mask(Us, s) & theirPawns);
+ && (b = pawn_attack_span(Them, s + pawn_push(Us)) & ourPawns) != 0
+ && popcount(b) >= popcount(pawn_attack_span(Us, s) & theirPawns);
// Passed pawns will be properly scored in evaluation because we need
// full attack info to evaluate passed pawns. Only the frontmost passed
@@ -161,24 +167,30 @@ namespace {
// Score this pawn
if (isolated)
- value -= IsolatedPawnPenalty[opposed][f];
+ value -= Isolated[opposed][f];
if (doubled)
- value -= DoubledPawnPenalty[opposed][f];
+ value -= Doubled[opposed][f];
if (backward)
- value -= BackwardPawnPenalty[opposed][f];
+ value -= Backward[opposed][f];
if (chain)
- value += ChainBonus[f];
+ value += ChainMember[f];
if (candidate)
- value += CandidateBonus[relative_rank(Us, s)];
+ {
+ value += CandidatePassed[relative_rank(Us, s)];
+
+ if (!doubled)
+ e->candidatePawns[Us] |= s;
+ }
}
return value;
}
-}
+
+} // namespace
namespace Pawns {
@@ -191,27 +203,11 @@ Entry* probe(const Position& pos, Table& entries) {
Key key = pos.pawn_key();
Entry* e = entries[key];
- // If e->key matches the position's pawn hash key, it means that we
- // have analysed this pawn structure before, and we can simply return
- // the information we found the last time instead of recomputing it.
if (e->key == key)
return e;
e->key = key;
- e->passedPawns[WHITE] = e->passedPawns[BLACK] = 0;
- e->kingSquares[WHITE] = e->kingSquares[BLACK] = SQ_NONE;
- e->halfOpenFiles[WHITE] = e->halfOpenFiles[BLACK] = 0xFF;
-
- Bitboard wPawns = pos.pieces(WHITE, PAWN);
- Bitboard bPawns = pos.pieces(BLACK, PAWN);
- e->pawnAttacks[WHITE] = ((wPawns & ~FileHBB) << 9) | ((wPawns & ~FileABB) << 7);
- e->pawnAttacks[BLACK] = ((bPawns & ~FileHBB) >> 7) | ((bPawns & ~FileABB) >> 9);
-
- e->value = evaluate_pawns(pos, wPawns, bPawns, e)
- - evaluate_pawns(pos, bPawns, wPawns, e);
-
- e->value = apply_weight(e->value, PawnStructureWeight);
-
+ e->value = evaluate(pos, e) - evaluate(pos, e);
return e;
}
@@ -225,25 +221,21 @@ 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) ? kf++ : (kf == FILE_H) ? kf-- : kf;
+ File kf = std::max(FILE_B, std::min(FILE_G, file_of(ksq)));
- for (int f = kf - 1; f <= kf + 1; f++)
+ 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;