/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 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
/// Constants and variables
- // Doubled pawn penalty by file, middle game
- const Value DoubledPawnMidgamePenalty[8] = {
- Value(13), Value(20), Value(23), Value(23),
- Value(23), Value(23), Value(20), Value(13)
- };
-
- // Doubled pawn penalty by file, endgame
- const Value DoubledPawnEndgamePenalty[8] = {
- Value(43), Value(48), Value(48), Value(48),
- Value(48), Value(48), Value(48), Value(43)
- };
-
- // Isolated pawn penalty by file, middle game
- const Value IsolatedPawnMidgamePenalty[8] = {
- Value(25), Value(36), Value(40), Value(40),
- Value(40), Value(40), Value(36), Value(25)
- };
-
- // Isolated pawn penalty by file, endgame
- const Value IsolatedPawnEndgamePenalty[8] = {
- Value(30), Value(35), Value(35), Value(35),
- Value(35), Value(35), Value(35), Value(30)
- };
+ #define S(mg, eg) make_score(mg, eg)
- // Backward pawn penalty by file, middle game
- const Value BackwardPawnMidgamePenalty[8] = {
- Value(20), Value(29), Value(33), Value(33),
- Value(33), Value(33), Value(29), Value(20)
+ // Doubled pawn penalty by file
+ const Score DoubledPawnPenalty[8] = {
+ S(13, 43), S(20, 48), S(23, 48), S(23, 48),
+ S(23, 48), S(23, 48), S(20, 48), S(13, 43)
};
- // Backward pawn penalty by file, endgame
- const Value BackwardPawnEndgamePenalty[8] = {
- Value(28), Value(31), Value(31), Value(31),
- Value(31), Value(31), Value(31), Value(28)
+ // Isolated pawn penalty by file
+ const Score IsolatedPawnPenalty[8] = {
+ S(25, 30), S(36, 35), S(40, 35), S(40, 35),
+ S(40, 35), S(40, 35), S(36, 35), S(25, 30)
};
- // Pawn chain membership bonus by file, middle game
- const Value ChainMidgameBonus[8] = {
- Value(11), Value(13), Value(13), Value(14),
- Value(14), Value(13), Value(13), Value(11)
+ // Backward pawn penalty by file
+ const Score BackwardPawnPenalty[8] = {
+ 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, endgame
- const Value ChainEndgameBonus[8] = {
- Value(-1), Value(-1), Value(-1), Value(-1),
- Value(-1), Value(-1), Value(-1), Value(-1)
+ // Pawn chain membership bonus by file
+ const Score ChainBonus[8] = {
+ 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, middle game
- const Value CandidateMidgameBonus[8] = {
- Value( 0), Value( 6), Value(6), Value(14),
- Value(34), Value(83), Value(0), Value( 0)
+ // Candidate passed pawn bonus by rank
+ const Score CandidateBonus[8] = {
+ S( 0, 0), S( 6, 13), S(6,13), S(14,29),
+ S(34,68), S(83,166), S(0, 0), S( 0, 0)
};
- // Candidate passed pawn bonus by rank, endgame
- const Value CandidateEndgameBonus[8] = {
- Value( 0), Value( 13), Value(13), Value(29),
- Value(68), Value(166), Value( 0), Value( 0)
+ // UnpairedPawnsTable[] gives a score according to the number
+ // of panws that do not have an enemy pawn in front of them.
+ const int UnpairedPawnsTable[8] = {
+ SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL,
+ SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL, SCALE_FACTOR_NORMAL
};
// Pawn storm tables for positions with opposite castling
pi->pawnAttacks[BLACK] = ((blackPawns >> 7) & ~FileABB) | ((blackPawns >> 9) & ~FileHBB);
// Evaluate pawns for both colors
- Values whiteValues = evaluate_pawns<WHITE>(pos, whitePawns, blackPawns, pi);
- Values blackValues = evaluate_pawns<BLACK>(pos, blackPawns, whitePawns, pi);
-
- pi->mgValue = int16_t(whiteValues.first - blackValues.first);
- pi->egValue = int16_t(whiteValues.second - blackValues.second);
+ pi->value = evaluate_pawns<WHITE>(pos, whitePawns, blackPawns, pi)
+ - evaluate_pawns<BLACK>(pos, blackPawns, whitePawns, pi);
return pi;
}
/// PawnInfoTable::evaluate_pawns() evaluates each pawn of the given color
template<Color Us>
-PawnInfoTable::Values PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
- Bitboard theirPawns, PawnInfo* pi) {
+Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
+ Bitboard theirPawns, PawnInfo* pi) {
Square s;
File f;
Rank r;
- bool passed, isolated, doubled, chain, backward, candidate;
+ bool passed, isolated, doubled, opposed, chain, backward, candidate;
int bonus;
- Value mgValue = Value(0);
- Value egValue = Value(0);
+ Score value = make_score(0, 0);
const Square* ptr = pos.piece_list_begin(Us, PAWN);
+ int unpairedPawnsNum = pos.piece_count(Us, PAWN);
// Initialize pawn storm scores by giving bonuses for open files
for (f = FILE_A; f <= FILE_H; f++)
assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
// Passed, isolated or doubled pawn?
- passed = Position::pawn_is_passed(theirPawns, Us, s);
- isolated = Position::pawn_is_isolated(ourPawns, s);
- doubled = Position::pawn_is_doubled(ourPawns, Us, s);
+ passed = !(theirPawns & passed_pawn_mask(Us, s));
+ isolated = !(ourPawns & neighboring_files_bb(s));
+ doubled = ourPawns & squares_behind(Us, s);
+ opposed = theirPawns & squares_in_front_of(Us, s);
+
+ // Decrease number of unpaired pawns
+ if (opposed)
+ unpairedPawnsNum--;
// We calculate kingside and queenside pawn storm
// scores for both colors. These are used when evaluating
Bitboard b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB);
while (b)
{
+ // Give a bonus according to the distance of the nearest enemy pawn
Square s2 = pop_1st_bit(&b);
+ int v = StormLeverBonus[f] - 2 * square_distance(s, s2);
+
+ // If enemy pawn has no pawn beside itself is particularly vulnerable.
+ // Big bonus, especially against a weakness on the rook file
if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- {
- // The enemy pawn has no pawn beside itself, which makes it
- // particularly vulnerable. Big bonus, especially against a
- // weakness on the rook file.
- if (square_file(s2) == FILE_H)
- bonus += 4*StormLeverBonus[f] - 8*square_distance(s, s2);
- else
- bonus += 2*StormLeverBonus[f] - 4*square_distance(s, s2);
- } else
- // There is at least one enemy pawn beside the enemy pawn we look
- // at, which means that the pawn has somewhat better chances of
- // defending itself by advancing. Smaller bonus.
- bonus += StormLeverBonus[f] - 2*square_distance(s, s2);
+ v *= (square_file(s2) == FILE_H ? 4 : 2);
+
+ bonus += v;
}
}
pi->ksStormValue[Us] += bonus;
Bitboard b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB);
while (b)
{
+ // Give a bonus according to the distance of the nearest enemy pawn
Square s2 = pop_1st_bit(&b);
+ int v = StormLeverBonus[f] - 4 * square_distance(s, s2);
+
+ // If enemy pawn has no pawn beside itself is particularly vulnerable.
+ // Big bonus, especially against a weakness on the rook file
if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2)))
- {
- // The enemy pawn has no pawn beside itself, which makes it
- // particularly vulnerable. Big bonus, especially against a
- // weakness on the rook file.
- if (square_file(s2) == FILE_A)
- bonus += 4*StormLeverBonus[f] - 16*square_distance(s, s2);
- else
- bonus += 2*StormLeverBonus[f] - 8*square_distance(s, s2);
- } else
- // There is at least one enemy pawn beside the enemy pawn we look
- // at, which means that the pawn has somewhat better chances of
- // defending itself by advancing. Smaller bonus.
- bonus += StormLeverBonus[f] - 4*square_distance(s, s2);
+ v *= (square_file(s2) == FILE_A ? 4 : 2);
+
+ bonus += v;
}
}
pi->qsStormValue[Us] += bonus;
// Test for candidate passed pawn
candidate = !passed
- && !(theirPawns & file_bb(f))
+ && !opposed
&& ( count_1s_max_15(neighboring_files_bb(f) & (behind_bb(Us, r) | rank_bb(r)) & ourPawns)
- count_1s_max_15(neighboring_files_bb(f) & in_front_bb(Us, r) & theirPawns)
>= 0);
if (isolated)
{
- mgValue -= IsolatedPawnMidgamePenalty[f];
- egValue -= IsolatedPawnEndgamePenalty[f];
+ value -= IsolatedPawnPenalty[f];
if (!(theirPawns & file_bb(f)))
- {
- mgValue -= IsolatedPawnMidgamePenalty[f] / 2;
- egValue -= IsolatedPawnEndgamePenalty[f] / 2;
- }
+ value -= IsolatedPawnPenalty[f] / 2;
}
if (doubled)
- {
- mgValue -= DoubledPawnMidgamePenalty[f];
- egValue -= DoubledPawnEndgamePenalty[f];
- }
+ value -= DoubledPawnPenalty[f];
+
if (backward)
{
- mgValue -= BackwardPawnMidgamePenalty[f];
- egValue -= BackwardPawnEndgamePenalty[f];
+ value -= BackwardPawnPenalty[f];
if (!(theirPawns & file_bb(f)))
- {
- mgValue -= BackwardPawnMidgamePenalty[f] / 2;
- egValue -= BackwardPawnEndgamePenalty[f] / 2;
- }
+ value -= BackwardPawnPenalty[f] / 2;
}
if (chain)
- {
- mgValue += ChainMidgameBonus[f];
- egValue += ChainEndgameBonus[f];
- }
+ value += ChainBonus[f];
+
if (candidate)
- {
- mgValue += CandidateMidgameBonus[relative_rank(Us, s)];
- egValue += CandidateEndgameBonus[relative_rank(Us, s)];
- }
+ value += CandidateBonus[relative_rank(Us, s)];
}
- return Values(mgValue, egValue);
+ // Calculate a scale factor to be used to evaluate if position is drawish
+ pi->factor[Us] = UnpairedPawnsTable[unpairedPawnsNum];
+
+ return value;
}
projects / stockfish / blobdiff