////
#include <cassert>
-#include <cstring>
#include "bitcount.h"
#include "evaluate.h"
namespace {
+ // Struct EvalInfo contains various information computed and collected
+ // by the evaluation functions.
+ struct EvalInfo {
+
+ // Pointer to pawn hash table entry
+ PawnInfo* pi;
+
+ // attackedBy[color][piece type] is a bitboard representing all squares
+ // attacked by a given color and piece type, attackedBy[color][0] contains
+ // all squares attacked by the given color.
+ Bitboard attackedBy[2][8];
+
+ // kingZone[color] is the zone around the enemy king which is considered
+ // by the king safety evaluation. This consists of the squares directly
+ // adjacent to the king, and the three (or two, for a king on an edge file)
+ // squares two ranks in front of the king. For instance, if black's king
+ // is on g8, kingZone[WHITE] is a bitboard containing the squares f8, h8,
+ // f7, g7, h7, f6, g6 and h6.
+ Bitboard kingZone[2];
+
+ // kingAttackersCount[color] is the number of pieces of the given color
+ // which attack a square in the kingZone of the enemy king.
+ int kingAttackersCount[2];
+
+ // kingAttackersWeight[color] is the sum of the "weight" of the pieces of the
+ // given color which attack a square in the kingZone of the enemy king. The
+ // weights of the individual piece types are given by the variables
+ // QueenAttackWeight, RookAttackWeight, BishopAttackWeight and
+ // KnightAttackWeight in evaluate.cpp
+ int kingAttackersWeight[2];
+
+ // kingAdjacentZoneAttacksCount[color] is the number of attacks to squares
+ // directly adjacent to the king of the given color. Pieces which attack
+ // more than one square are counted multiple times. For instance, if black's
+ // king is on g8 and there's a white knight on g5, this knight adds
+ // 2 to kingAdjacentZoneAttacksCount[BLACK].
+ int kingAdjacentZoneAttacksCount[2];
+ };
+
const int Sign[2] = { 1, -1 };
// Evaluation grain size, must be a power of 2
// Function prototypes
template<bool HasPopCnt>
- Value do_evaluate(const Position& pos, EvalInfo& ei);
+ Value do_evaluate(const Position& pos, Value margins[]);
template<Color Us, bool HasPopCnt>
void init_attack_tables(const Position& pos, EvalInfo& ei);
template<Color Us, bool HasPopCnt>
- void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei);
+ Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility);
template<Color Us, bool HasPopCnt>
- void evaluate_king(const Position& pos, EvalInfo& ei);
+ Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]);
template<Color Us>
- void evaluate_threats(const Position& pos, EvalInfo& ei);
+ Score evaluate_threats(const Position& pos, EvalInfo& ei);
template<Color Us, bool HasPopCnt>
int evaluate_space(const Position& pos, EvalInfo& ei);
template<Color Us>
- void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
+ Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
inline Score apply_weight(Score v, Score weight);
Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
/// evaluate() is the main evaluation function. It always computes two
/// values, an endgame score and a middle game score, and interpolates
/// between them based on the remaining material.
-Value evaluate(const Position& pos, EvalInfo& ei) {
+Value evaluate(const Position& pos, Value margins[]) {
- return CpuHasPOPCNT ? do_evaluate<true>(pos, ei)
- : do_evaluate<false>(pos, ei);
+ return CpuHasPOPCNT ? do_evaluate<true>(pos, margins)
+ : do_evaluate<false>(pos, margins);
}
namespace {
template<bool HasPopCnt>
-Value do_evaluate(const Position& pos, EvalInfo& ei) {
+Value do_evaluate(const Position& pos, Value margins[]) {
+ EvalInfo ei;
ScaleFactor factor[2];
+ Score w_mob, b_mob;
assert(pos.is_ok());
assert(pos.thread() >= 0 && pos.thread() < MAX_THREADS);
assert(!pos.is_check());
- memset(&ei, 0, sizeof(EvalInfo));
-
// Initialize by reading the incrementally updated scores included in the
- // position object (material + piece square tables)
- ei.value = pos.value();
+ // position object (material + piece square tables).
+ Score value = pos.value();
+
+ // margins[color] stores the uncertainty estimation of position's evaluation
+ // and typically is used by the search for pruning decisions.
+ margins[WHITE] = margins[BLACK] = VALUE_ZERO;
// Probe the material hash table
- ei.mi = MaterialTable[pos.thread()]->get_material_info(pos);
- ei.value += ei.mi->material_value();
+ MaterialInfo* mi = MaterialTable[pos.thread()]->get_material_info(pos);
+ value += mi->material_value();
// If we have a specialized evaluation function for the current material
- // configuration, call it and return
- if (ei.mi->specialized_eval_exists())
- return ei.mi->evaluate(pos);
+ // configuration, call it and return.
+ if (mi->specialized_eval_exists())
+ return mi->evaluate(pos);
// After get_material_info() call that modifies them
- factor[WHITE] = ei.mi->scale_factor(pos, WHITE);
- factor[BLACK] = ei.mi->scale_factor(pos, BLACK);
+ factor[WHITE] = mi->scale_factor(pos, WHITE);
+ factor[BLACK] = mi->scale_factor(pos, BLACK);
// Probe the pawn hash table
ei.pi = PawnTable[pos.thread()]->get_pawn_info(pos);
- ei.value += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
+ value += apply_weight(ei.pi->pawns_value(), Weights[PawnStructure]);
// Initialize attack bitboards with pawns evaluation
init_attack_tables<WHITE, HasPopCnt>(pos, ei);
init_attack_tables<BLACK, HasPopCnt>(pos, ei);
- // Evaluate pieces
- evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei);
- evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei);
+ // Evaluate pieces and mobility
+ value += evaluate_pieces_of_color<WHITE, HasPopCnt>(pos, ei, w_mob)
+ - evaluate_pieces_of_color<BLACK, HasPopCnt>(pos, ei, b_mob);
- // Kings. Kings are evaluated after all other pieces for both sides,
- // because we need complete attack information for all pieces when computing
+ value += apply_weight(w_mob - b_mob, Weights[Mobility]);
+
+ // Evaluate kings after all other pieces for both sides, because we
+ // need complete attack information for all pieces when computing
// the king safety evaluation.
- evaluate_king<WHITE, HasPopCnt>(pos, ei);
- evaluate_king<BLACK, HasPopCnt>(pos, ei);
+ value += evaluate_king<WHITE, HasPopCnt>(pos, ei, margins)
+ - evaluate_king<BLACK, HasPopCnt>(pos, ei, margins);
// Evaluate tactical threats, we need full attack info including king
- evaluate_threats<WHITE>(pos, ei);
- evaluate_threats<BLACK>(pos, ei);
+ value += evaluate_threats<WHITE>(pos, ei)
+ - evaluate_threats<BLACK>(pos, ei);
// Evaluate passed pawns, we need full attack info including king
- evaluate_passed_pawns<WHITE>(pos, ei);
- evaluate_passed_pawns<BLACK>(pos, ei);
+ value += evaluate_passed_pawns<WHITE>(pos, ei)
+ - evaluate_passed_pawns<BLACK>(pos, ei);
- Phase phase = ei.mi->game_phase();
+ Phase phase = mi->game_phase();
// Middle-game specific evaluation terms
if (phase > PHASE_ENDGAME)
if ( square_file(pos.king_square(WHITE)) >= FILE_E
&& square_file(pos.king_square(BLACK)) <= FILE_D)
- ei.value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
+ value += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0);
else if ( square_file(pos.king_square(WHITE)) <= FILE_D
&& square_file(pos.king_square(BLACK)) >= FILE_E)
- ei.value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
+ value += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0);
// Evaluate space for both sides
- if (ei.mi->space_weight() > 0)
+ if (mi->space_weight() > 0)
{
int s = evaluate_space<WHITE, HasPopCnt>(pos, ei) - evaluate_space<BLACK, HasPopCnt>(pos, ei);
- ei.value += apply_weight(make_score(s * ei.mi->space_weight(), 0), Weights[Space]);
+ value += apply_weight(make_score(s * mi->space_weight(), 0), Weights[Space]);
}
}
- // Mobility
- ei.value += apply_weight(ei.mobility, Weights[Mobility]);
-
// If we don't already have an unusual scale factor, check for opposite
// colored bishop endgames, and use a lower scale for those
if ( phase < PHASE_MIDGAME
&& pos.opposite_colored_bishops()
- && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(ei.value) > VALUE_ZERO)
- || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(ei.value) < VALUE_ZERO)))
+ && ( (factor[WHITE] == SCALE_FACTOR_NORMAL && eg_value(value) > VALUE_ZERO)
+ || (factor[BLACK] == SCALE_FACTOR_NORMAL && eg_value(value) < VALUE_ZERO)))
{
ScaleFactor sf;
}
// Interpolate between the middle game and the endgame score
- return Sign[pos.side_to_move()] * scale_by_game_phase(ei.value, phase, factor);
+ return Sign[pos.side_to_move()] * scale_by_game_phase(value, phase, factor);
}
} // namespace
ei.kingZone[Us] = (b | (Us == WHITE ? b >> 8 : b << 8));
ei.attackedBy[Us][PAWN] = ei.pi->pawn_attacks(Us);
b &= ei.attackedBy[Us][PAWN];
- if (b)
- ei.kingAttackersCount[Us] = count_1s_max_15<HasPopCnt>(b) / 2;
+ ei.kingAttackersCount[Us] = b ? count_1s_max_15<HasPopCnt>(b) / 2 : 0;
+ ei.kingAdjacentZoneAttacksCount[Us] = ei.kingAttackersWeight[Us] = 0;
}
// evaluate_outposts() evaluates bishop and knight outposts squares
template<PieceType Piece, Color Us>
- void evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
+ Score evaluate_outposts(const Position& pos, EvalInfo& ei, Square s) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
else
bonus += bonus / 2;
}
- ei.value += Sign[Us] * make_score(bonus, bonus);
+ return make_score(bonus, bonus);
}
// evaluate_pieces<>() assigns bonuses and penalties to the pieces of a given color
template<PieceType Piece, Color Us, bool HasPopCnt>
- void evaluate_pieces(const Position& pos, EvalInfo& ei, Bitboard no_mob_area) {
+ Score evaluate_pieces(const Position& pos, EvalInfo& ei, Score& mobility, Bitboard no_mob_area) {
Bitboard b;
Square s, ksq;
int mob;
File f;
+ Score bonus = SCORE_ZERO;
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Square* ptr = pos.piece_list_begin(Us, Piece);
+ ei.attackedBy[Us][Piece] = 0;
+
while ((s = *ptr++) != SQ_NONE)
{
// Find attacked squares, including x-ray attacks for bishops and rooks
mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b & no_mob_area)
: count_1s<HasPopCnt>(b & no_mob_area));
- ei.mobility += Sign[Us] * MobilityBonus[Piece][mob];
+ mobility += MobilityBonus[Piece][mob];
// Decrease score if we are attacked by an enemy pawn. Remaining part
// of threat evaluation must be done later when we have full attack info.
if (bit_is_set(ei.attackedBy[Them][PAWN], s))
- ei.value -= Sign[Us] * ThreatedByPawnPenalty[Piece];
+ bonus -= ThreatedByPawnPenalty[Piece];
// Bishop and knight outposts squares
if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Us))
- evaluate_outposts<Piece, Us>(pos, ei, s);
+
bonus += evaluate_outposts<Piece, Us>(pos, ei, s);
// Queen or rook on 7th rank
if ( (Piece == ROOK || Piece == QUEEN)
&& relative_rank(Us, s) == RANK_7
&& relative_rank(Us, pos.king_square(Them)) == RANK_8)
{
- ei.value += Sign[Us] * (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
+ bonus += (Piece == ROOK ? RookOn7thBonus : QueenOn7thBonus);
}
// Special extra evaluation for rooks
if (ei.pi->file_is_half_open(Us, f))
{
if (ei.pi->file_is_half_open(Them, f))
- ei.value += Sign[Us] * RookOpenFileBonus;
+ bonus += RookOpenFileBonus;
else
- ei.value += Sign[Us] * RookHalfOpenFileBonus;
+ bonus += RookHalfOpenFileBonus;
}
// Penalize rooks which are trapped inside a king. Penalize more if
{
// Is there a half-open file between the king and the edge of the board?
if (!ei.pi->has_open_file_to_right(Us, square_file(ksq)))
- ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
- : (TrappedRookPenalty - mob * 16), 0);
+ bonus -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
+ : (TrappedRookPenalty - mob * 16), 0);
}
else if ( square_file(ksq) <= FILE_D
&& square_file(s) < square_file(ksq)
{
// Is there a half-open file between the king and the edge of the board?
if (!ei.pi->has_open_file_to_left(Us, square_file(ksq)))
- ei.value -= Sign[Us] * make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
- : (TrappedRookPenalty - mob * 16), 0);
+ bonus -= make_score(pos.can_castle(Us) ? (TrappedRookPenalty - mob * 16) / 2
+ : (TrappedRookPenalty - mob * 16), 0);
}
}
}
+ return bonus;
}
// and the type of attacked one.
template<Color Us>
- void evaluate_threats(const Position& pos, EvalInfo& ei) {
+ Score evaluate_threats(const Position& pos, EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
& ~ei.attackedBy[Them][PAWN]
& ei.attackedBy[Us][0];
if (!weakEnemies)
- return;
+ return SCORE_ZERO;
// Add bonus according to type of attacked enemy pieces and to the
// type of attacking piece, from knights to queens. Kings are not
if (b & pos.pieces(pt2))
bonus += ThreatBonus[pt1][pt2];
}
- ei.value += Sign[Us] * bonus;
+ return bonus;
}
// pieces of a given color.
template<Color Us, bool HasPopCnt>
- void evaluate_pieces_of_color(const Position& pos, EvalInfo& ei) {
+ Score evaluate_pieces_of_color(const Position& pos, EvalInfo& ei, Score& mobility) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
+ Score bonus = SCORE_ZERO;
+
+ mobility = SCORE_ZERO;
+
// Do not include in mobility squares protected by enemy pawns or occupied by our pieces
const Bitboard no_mob_area = ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
- evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, no_mob_area);
- evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, no_mob_area);
- evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, no_mob_area);
- evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, no_mob_area);
+ bonus += evaluate_pieces<KNIGHT, Us, HasPopCnt>(pos, ei, mobility, no_mob_area);
+ bonus += evaluate_pieces<BISHOP, Us, HasPopCnt>(pos, ei, mobility, no_mob_area);
+ bonus += evaluate_pieces<ROOK, Us, HasPopCnt>(pos, ei, mobility, no_mob_area);
+ bonus += evaluate_pieces<QUEEN, Us, HasPopCnt>(pos, ei, mobility, no_mob_area);
// Sum up all attacked squares
ei.attackedBy[Us][0] = ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
| ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
| ei.attackedBy[Us][QUEEN] | ei.attackedBy[Us][KING];
+ return bonus;
}
// evaluate_king<>() assigns bonuses and penalties to a king of a given color
template<Color Us, bool HasPopCnt>
- void evaluate_king(const Position& pos, EvalInfo& ei) {
+ Score evaluate_king(const Position& pos, EvalInfo& ei, Value margins[]) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
const Square ksq = pos.king_square(Us);
// King shelter
- ei.value += Sign[Us] * ei.pi->king_shelter(pos, Us, ksq);
+ Score bonus = ei.pi->king_shelter(pos, Us, ksq);
// King safety. This is quite complicated, and is almost certainly far
// from optimally tuned.
// Find the attacked squares around the king which has no defenders
// apart from the king itself
- undefended = ei.attacked_by(Them) & ei.attacked_by(Us, KING);
- undefended &= ~( ei.attacked_by(Us, PAWN) | ei.attacked_by(Us, KNIGHT)
- | ei.attacked_by(Us, BISHOP) | ei.attacked_by(Us, ROOK)
- | ei.attacked_by(Us, QUEEN));
+ undefended = ei.attackedBy[Them][0] & ei.attackedBy[Us][KING];
+ undefended &= ~( ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT]
+ | ei.attackedBy[Us][BISHOP] | ei.attackedBy[Us][ROOK]
+ | ei.attackedBy[Us][QUEEN]);
// Initialize the 'attackUnits' variable, which is used later on as an
// index to the KingDangerTable[] array. The initial value is based on
// Analyse enemy's safe queen contact checks. First find undefended
// squares around the king attacked by enemy queen...
- b = undefended & ei.attacked_by(Them, QUEEN) & ~pos.pieces_of_color(Them);
+ b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces_of_color(Them);
if (b)
{
// ...then remove squares not supported by another enemy piece
- b &= ( ei.attacked_by(Them, PAWN) | ei.attacked_by(Them, KNIGHT)
- | ei.attacked_by(Them, BISHOP) | ei.attacked_by(Them, ROOK));
+ b &= ( ei.attackedBy[Them][PAWN] | ei.attackedBy[Them][KNIGHT]
+ | ei.attackedBy[Them][BISHOP] | ei.attackedBy[Them][ROOK]);
if (b)
attackUnits += QueenContactCheckBonus * count_1s_max_15<HasPopCnt>(b) * (sente ? 2 : 1);
}
// Analyse enemy's safe distance checks for sliders and knights
- safe = ~(pos.pieces_of_color(Them) | ei.attacked_by(Us));
+ safe = ~(pos.pieces_of_color(Them) | ei.attackedBy[Us][0]);
b1 = pos.attacks_from<ROOK>(ksq) & safe;
b2 = pos.attacks_from<BISHOP>(ksq) & safe;
// Enemy queen safe checks
- b = (b1 | b2) & ei.attacked_by(Them, QUEEN);
+ b = (b1 | b2) & ei.attackedBy[Them][QUEEN];
if (b)
attackUnits += QueenCheckBonus * count_1s_max_15<HasPopCnt>(b);
// Enemy rooks safe checks
- b = b1 & ei.attacked_by(Them, ROOK);
+ b = b1 & ei.attackedBy[Them][ROOK];
if (b)
attackUnits += RookCheckBonus * count_1s_max_15<HasPopCnt>(b);
// Enemy bishops safe checks
- b = b2 & ei.attacked_by(Them, BISHOP);
+ b = b2 & ei.attackedBy[Them][BISHOP];
if (b)
attackUnits += BishopCheckBonus * count_1s_max_15<HasPopCnt>(b);
// Enemy knights safe checks
- b = pos.attacks_from<KNIGHT>(ksq) & ei.attacked_by(Them, KNIGHT) & safe;
+ b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT] & safe;
if (b)
attackUnits += KnightCheckBonus * count_1s_max_15<HasPopCnt>(b);
attackUnits = Min(99, Max(0, attackUnits));
// Finally, extract the king danger score from the KingDangerTable[]
- // array and subtract the score from evaluation. Set also ei.kingDanger[]
+ // array and subtract the score from evaluation. Set also margins[]
// value that will be used for pruning because this value can sometimes
// be very big, and so capturing a single attacking piece can therefore
// result in a score change far bigger than the value of the captured piece.
- ei.value -= Sign[Us] * KingDangerTable[Us][attackUnits];
- ei.kingDanger[Us] = mg_value(KingDangerTable[Us][attackUnits]);
+ bonus -= KingDangerTable[Us][attackUnits];
+ margins[Us] += mg_value(KingDangerTable[Us][attackUnits]);
}
+ return bonus;
}
// evaluate_passed_pawns<>() evaluates the passed pawns of the given color
template<Color Us>
- void evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
+ Score evaluate_passed_pawns(const Position& pos, EvalInfo& ei) {
const Color Them = (Us == WHITE ? BLACK : WHITE);
+ Score bonus = SCORE_ZERO;
Bitboard squaresToQueen, defendedSquares, unsafeSquares, supportingPawns;
Bitboard b = ei.pi->passed_pawns(Us);
- while (b)
- {
+ if (!b)
+ return SCORE_ZERO;
+
+ do {
Square s = pop_1st_bit(&b);
assert(pos.pawn_is_passed(Us, s));
if (pos.square_is_empty(blockSq))
{
squaresToQueen = squares_in_front_of(Us, s);
- defendedSquares = squaresToQueen & ei.attacked_by(Us);
+ defendedSquares = squaresToQueen & ei.attackedBy[Us][0];
// If there is an enemy rook or queen attacking the pawn from behind,
// add all X-ray attacks by the rook or queen. Otherwise consider only
&& (squares_behind(Us, s) & pos.pieces(ROOK, QUEEN, Them) & pos.attacks_from<ROOK>(s)))
unsafeSquares = squaresToQueen;
else
- unsafeSquares = squaresToQueen & (ei.attacked_by(Them) | pos.pieces_of_color(Them));
+ unsafeSquares = squaresToQueen & (ei.attackedBy[Them][0] | pos.pieces_of_color(Them));
// If there aren't enemy attacks or pieces along the path to queen give
// huge bonus. Even bigger if we protect the pawn's path.
else if (pos.pieces(ROOK, QUEEN, Them))
ebonus -= ebonus / 4;
}
+ bonus += make_score(mbonus, ebonus);
- // Add the scores for this pawn to the middle game and endgame eval
- ei.value += Sign[Us] * apply_weight(make_score(mbonus, ebonus), Weights[PassedPawns]);
+ } while (b);
- } // while
+ // Add the scores to the middle game and endgame eval
+ return apply_weight(bonus, Weights[PassedPawns]);
}
// pawn, or if it is undefended and attacked by an enemy piece.
Bitboard safe = SpaceMask[Us]
& ~pos.pieces(PAWN, Us)
- & ~ei.attacked_by(Them, PAWN)
- & (ei.attacked_by(Us) | ~ei.attacked_by(Them));
+ & ~ei.attackedBy[Them][PAWN]
+ & (ei.attackedBy[Us][0] | ~ei.attackedBy[Them][0]);
// Find all squares which are at most three squares behind some friendly pawn
Bitboard behind = pos.pieces(PAWN, Us);
projects / stockfish / blobdiff