/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
+ Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, 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
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-
-////
-//// Includes
-////
-
#include <cassert>
-#include <cstring>
+#include "bitboard.h"
#include "bitcount.h"
#include "pawns.h"
#include "position.h"
-
-////
-//// Local definitions
-////
-
namespace {
- /// Constants and variables
-
#define S(mg, eg) make_score(mg, eg)
// Doubled pawn penalty by opposed flag and file
S(34,68), S(83,166), S(0, 0), S( 0, 0)
};
- #undef S
-}
+ const Score PawnStructureWeight = S(233, 201);
+ #undef S
-////
-//// Functions
-////
+ inline Score apply_weight(Score v, Score w) {
+ return make_score((int(mg_value(v)) * mg_value(w)) / 0x100,
+ (int(eg_value(v)) * eg_value(w)) / 0x100);
+ }
+}
-/// PawnInfoTable::get_pawn_info() takes a position object as input, computes
+/// PawnInfoTable::pawn_info() takes a position object as input, computes
/// a PawnInfo object, and returns a pointer to it. The result is also stored
-/// in a hash table, so we don't have to recompute everything when the same
+/// in an hash table, so we don't have to recompute everything when the same
/// pawn structure occurs again.
-PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
+PawnInfo* PawnInfoTable::pawn_info(const Position& pos) const {
- assert(pos.is_ok());
-
- Key key = pos.get_pawn_key();
- PawnInfo* pi = find(key);
+ Key key = pos.pawn_key();
+ PawnInfo* pi = probe(key);
// If pi->key matches the position's pawn hash key, it means that we
// have analysed this pawn structure before, and we can simply return
if (pi->key == key)
return pi;
- // Clear the PawnInfo object, and set the key
- memset(pi, 0, sizeof(PawnInfo));
- pi->halfOpenFiles[WHITE] = pi->halfOpenFiles[BLACK] = 0xFF;
- pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE;
+ // Initialize PawnInfo entry
pi->key = key;
+ pi->passedPawns[WHITE] = pi->passedPawns[BLACK] = 0;
+ pi->kingSquares[WHITE] = pi->kingSquares[BLACK] = SQ_NONE;
+ pi->halfOpenFiles[WHITE] = pi->halfOpenFiles[BLACK] = 0xFF;
// Calculate pawn attacks
Bitboard wPawns = pos.pieces(PAWN, WHITE);
pi->pawnAttacks[WHITE] = ((wPawns << 9) & ~FileABB) | ((wPawns << 7) & ~FileHBB);
pi->pawnAttacks[BLACK] = ((bPawns >> 7) & ~FileABB) | ((bPawns >> 9) & ~FileHBB);
- // Evaluate pawns for both colors
+ // Evaluate pawns for both colors and weight the result
pi->value = evaluate_pawns<WHITE>(pos, wPawns, bPawns, pi)
- evaluate_pawns<BLACK>(pos, bPawns, wPawns, pi);
+
+ pi->value = apply_weight(pi->value, PawnStructureWeight);
+
return pi;
}
template<Color Us>
Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
- Bitboard theirPawns, PawnInfo* pi) const {
+ Bitboard theirPawns, PawnInfo* pi) {
+
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+
Bitboard b;
Square s;
File f;
Rank r;
bool passed, isolated, doubled, opposed, chain, backward, candidate;
Score value = SCORE_ZERO;
- const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
- const Square* ptr = pos.piece_list_begin(Us, PAWN);
+ const Square* pl = pos.piece_list(Us, PAWN);
// Loop through all pawns of the current color and score each pawn
- while ((s = *ptr++) != SQ_NONE)
+ while ((s = *pl++) != SQ_NONE)
{
- assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
+ assert(pos.piece_on(s) == make_piece(Us, PAWN));
- f = square_file(s);
- r = square_rank(s);
+ f = file_of(s);
+ r = rank_of(s);
// This file cannot be half open
pi->halfOpenFiles[Us] &= ~(1 << f);
- // Our rank plus previous one. Used for chain detection.
+ // Our rank plus previous one. Used for chain detection
b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
- // Passed, isolated, doubled or member of a pawn
- // chain (but not the backward one) ?
+ // Flag the pawn as passed, isolated, doubled or member of a pawn
+ // chain (but not the backward one).
passed = !(theirPawns & passed_pawn_mask(Us, s));
doubled = ourPawns & squares_in_front_of(Us, s);
opposed = theirPawns & squares_in_front_of(Us, s);
- isolated = !(ourPawns & neighboring_files_bb(f));
- chain = ourPawns & neighboring_files_bb(f) & b;
+ isolated = !(ourPawns & adjacent_files_bb(f));
+ chain = ourPawns & adjacent_files_bb(f) & b;
// Test for backward pawn
- //
backward = false;
- // If the pawn is passed, isolated, or member of a pawn chain
- // it cannot be backward. If can capture an enemy pawn or if
- // there are friendly pawns behind on neighboring files it cannot
- // be backward either.
+ // 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(opposite_color(Us), s))
+ && !(ourPawns & attack_span_mask(Them, s))
&& !(pos.attacks_from<PAWN>(s, Us) & theirPawns))
{
// We now know that there are no friendly pawns beside or behind this
- // pawn on neighboring files. We now check whether the pawn is
- // backward by looking in the forward direction on the neighboring
+ // 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<PAWN>(s, Us);
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.
+ // 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;
}
- assert(passed | opposed | (attack_span_mask(Us, s) & theirPawns));
+ assert(opposed | passed | (attack_span_mask(Us, s) & theirPawns));
- // Test for candidate passed pawn
- candidate = !(opposed | passed)
- && (b = attack_span_mask(opposite_color(Us), s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
- && count_1s<Max15>(b) >= count_1s<Max15>(attack_span_mask(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<Max15>(b) >= popcount<Max15>(attack_span_mask(Us, s) & theirPawns);
- // Mark the pawn as passed. Pawn will be properly scored in evaluation
- // because we need full attack info to evaluate passed pawns. Only the
- // frontmost passed pawn on each file is considered a true passed pawn.
+ // Passed pawns will be properly scored in evaluation because we need
+ // full attack info to evaluate passed pawns. Only the frontmost passed
+ // pawn on each file is considered a true passed pawn.
if (passed && !doubled)
- set_bit(&(pi->passedPawns[Us]), s);
+ pi->passedPawns[Us] |= s;
// Score this pawn
if (isolated)
}
return value;
}
+
+
+/// PawnInfo::updateShelter() calculates and caches king shelter. It is called
+/// only when king square changes, about 20% of total king_shelter() calls.
+template<Color Us>
+Score PawnInfo::updateShelter(const Position& pos, Square ksq) {
+
+ const int Shift = (Us == WHITE ? 8 : -8);
+
+ Bitboard pawns;
+ int r, shelter = 0;
+
+ if (relative_rank(Us, ksq) <= RANK_4)
+ {
+ pawns = pos.pieces(PAWN, Us) & this_and_adjacent_files_bb(file_of(ksq));
+ r = ksq & (7 << 3);
+ for (int i = 0; i < 3; i++)
+ {
+ r += Shift;
+ shelter += BitCount8Bit[(pawns >> r) & 0xFF] << (6 - i);
+ }
+ }
+ kingSquares[Us] = ksq;
+ kingShelters[Us] = make_score(shelter, 0);
+ return kingShelters[Us];
+}
+
+// Explicit template instantiation
+template Score PawnInfo::updateShelter<WHITE>(const Position& pos, Square ksq);
+template Score PawnInfo::updateShelter<BLACK>(const Position& pos, Square ksq);
projects / stockfish / blobdiff