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 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)
- };
-
- // 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)
- };
-
- // 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)
- };
+ // Doubled pawn penalty by opposed flag and file
+ const Score DoubledPawnPenalty[2][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) },
+ { 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][8] = {
+ { 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][8] = {
+ { 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[8] = {
S(34,68), S(83,166), S(0, 0), S( 0, 0)
};
- // Pawn storm tables for positions with opposite castling
- const int QStormTable[64] = {
- 0, 0, 0, 0, 0, 0, 0, 0,
- -22,-22,-22,-14,-6, 0, 0, 0,
- -6,-10,-10,-10,-6, 0, 0, 0,
- 4, 12, 16, 12, 4, 0, 0, 0,
- 16, 23, 23, 16, 0, 0, 0, 0,
- 23, 31, 31, 23, 0, 0, 0, 0,
- 23, 31, 31, 23, 0, 0, 0, 0,
- 0, 0, 0, 0, 0, 0, 0, 0
- };
-
- const int KStormTable[64] = {
- 0, 0, 0, 0, 0, 0, 0, 0,
- 0, 0, 0,-10,-19,-28,-33,-33,
- 0, 0, 0,-10,-15,-19,-24,-24,
- 0, 0, 0, 0, 1, 1, 1, 1,
- 0, 0, 0, 0, 1, 10, 19, 19,
- 0, 0, 0, 0, 1, 19, 31, 27,
- 0, 0, 0, 0, 0, 22, 31, 22,
- 0, 0, 0, 0, 0, 0, 0, 0
- };
-
- // Pawn storm open file bonuses by file
- const int16_t QStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 };
- const int16_t KStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 };
-
- // Pawn storm lever bonuses by file
- const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 };
-
#undef S
}
-////
-//// Functions
-////
-
-/// PawnInfoTable c'tor and d'tor instantiated one each thread
-
-PawnInfoTable::PawnInfoTable(unsigned numOfEntries) : size(numOfEntries) {
-
- entries = new PawnInfo[size];
- if (!entries)
- {
- std::cerr << "Failed to allocate " << (numOfEntries * sizeof(PawnInfo))
- << " bytes for pawn hash table." << std::endl;
- Application::exit_with_failure();
- }
-}
-
-
-PawnInfoTable::~PawnInfoTable() {
-
- delete [] entries;
-}
-
-
-/// PawnInfo::clear() resets to zero the PawnInfo entry. Note that
-/// kingSquares[] is initialized to SQ_NONE instead.
-
-void PawnInfo::clear() {
-
- memset(this, 0, sizeof(PawnInfo));
- kingSquares[WHITE] = kingSquares[BLACK] = SQ_NONE;
-}
-
-
/// PawnInfoTable::get_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 {
assert(pos.is_ok());
Key key = pos.get_pawn_key();
- unsigned index = unsigned(key & (size - 1));
- PawnInfo* pi = entries + index;
+ PawnInfo* pi = find(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
- pi->clear();
+ // 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 whitePawns = pos.pieces(PAWN, WHITE);
- Bitboard blackPawns = pos.pieces(PAWN, BLACK);
- pi->pawnAttacks[WHITE] = ((whitePawns << 9) & ~FileABB) | ((whitePawns << 7) & ~FileHBB);
- pi->pawnAttacks[BLACK] = ((blackPawns >> 7) & ~FileABB) | ((blackPawns >> 9) & ~FileHBB);
+ Bitboard wPawns = pos.pieces(PAWN, WHITE);
+ Bitboard bPawns = pos.pieces(PAWN, BLACK);
+ pi->pawnAttacks[WHITE] = ((wPawns << 9) & ~FileABB) | ((wPawns << 7) & ~FileHBB);
+ pi->pawnAttacks[BLACK] = ((bPawns >> 7) & ~FileABB) | ((bPawns >> 9) & ~FileHBB);
// Evaluate pawns for both colors
- pi->value = evaluate_pawns<WHITE>(pos, whitePawns, blackPawns, pi)
- - evaluate_pawns<BLACK>(pos, blackPawns, whitePawns, pi);
+ pi->value = evaluate_pawns<WHITE>(pos, wPawns, bPawns, pi)
+ - evaluate_pawns<BLACK>(pos, bPawns, wPawns, pi);
return pi;
}
template<Color Us>
Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
- Bitboard theirPawns, PawnInfo* pi) const {
+ Bitboard theirPawns, PawnInfo* pi) {
+
+ const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15;
+ const Color Them = (Us == WHITE ? BLACK : WHITE);
+
Bitboard b;
Square s;
File f;
Rank r;
- int bonus;
bool passed, isolated, doubled, opposed, chain, backward, candidate;
- Score value = make_score(0, 0);
+ Score value = SCORE_ZERO;
const Square* ptr = pos.piece_list_begin(Us, PAWN);
- // Initialize pawn storm scores by giving bonuses for open files
- for (f = FILE_A; f <= FILE_H; f++)
- if (!(ourPawns & file_bb(f)))
- {
- pi->ksStormValue[Us] += KStormOpenFileBonus[f];
- pi->qsStormValue[Us] += QStormOpenFileBonus[f];
- pi->halfOpenFiles[Us] |= (1 << f);
- }
-
// Loop through all pawns of the current color and score each pawn
while ((s = *ptr++) != SQ_NONE)
{
+ assert(pos.piece_on(s) == make_piece(Us, PAWN));
+
f = square_file(s);
r = square_rank(s);
- assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
+ // This file cannot be half open
+ pi->halfOpenFiles[Us] &= ~(1 << f);
- // Calculate kingside and queenside pawn storm scores for both colors to be
- // used when evaluating middle game positions with opposite side castling.
- bonus = (f >= FILE_F ? evaluate_pawn_storm<Us, KingSide>(s, r, f, theirPawns) : 0);
- pi->ksStormValue[Us] += KStormTable[relative_square(Us, s)] + bonus;
+ // Our rank plus previous one. Used for chain detection
+ b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1));
- bonus = (f <= FILE_C ? evaluate_pawn_storm<Us, QueenSide>(s, r, f, theirPawns) : 0);
- pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus;
-
- // Our rank plus previous one. Used for chain detection.
- b = rank_bb(r) | rank_bb(r + (Us == WHITE ? -1 : 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_behind(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;
// Test for backward pawn
- //
- // 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 ( (passed | isolated | chain)
- || (ourPawns & attack_span_mask(opposite_color(Us), s))
- || (pos.attacks_from<PAWN>(s, Us) & theirPawns))
- backward = false;
- else
+ backward = false;
+
+ // If the pawn is passed, isolated, or member of a pawn chain it cannot
+ // be backward. If there are friendly pawns behind on neighboring 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<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
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_max_15(b) >= count_1s_max_15(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 neighboring files is higher or equal than the number of
+ // enemy pawns in the forward direction on the neighboring files.
+ candidate = !(opposed | passed | backward | isolated)
+ && (b = attack_span_mask(Them, s + pawn_push(Us)) & ourPawns) != EmptyBoardBB
+ && count_1s<Max15>(b) >= count_1s<Max15>(attack_span_mask(Us, s) & theirPawns);
- // In order to prevent doubled passed pawns from receiving a too big
- // bonus, only the frontmost passed pawn on each file is considered as
- // a true passed pawn.
- if (passed && (ourPawns & squares_in_front_of(Us, s)))
- passed = false;
-
- // Mark the pawn as passed. Pawn will be properly scored in evaluation
- // because we need full attack info to evaluate passed pawns.
- if (passed)
- set_bit(&(pi->passedPawns), s);
+ // 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);
// Score this pawn
if (isolated)
- {
- value -= IsolatedPawnPenalty[f];
- if (!opposed)
- value -= IsolatedPawnPenalty[f] / 2;
- }
+ value -= IsolatedPawnPenalty[opposed][f];
+
if (doubled)
- value -= DoubledPawnPenalty[f];
+ value -= DoubledPawnPenalty[opposed][f];
if (backward)
- {
- value -= BackwardPawnPenalty[f];
- if (!opposed)
- value -= BackwardPawnPenalty[f] / 2;
- }
+ value -= BackwardPawnPenalty[opposed][f];
+
if (chain)
value += ChainBonus[f];
if (candidate)
value += CandidateBonus[relative_rank(Us, s)];
}
-
return value;
}
-/// PawnInfoTable::evaluate_pawn_storm() evaluates each pawn which seems
-/// to have good chances of creating an open file by exchanging itself
-/// against an enemy pawn on an adjacent file.
-
-template<Color Us, PawnInfoTable::SideType Side>
-int PawnInfoTable::evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const {
+/// 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 Bitboard StormFilesBB = (Side == KingSide ? FileFBB | FileGBB | FileHBB
- : FileABB | FileBBB | FileCBB);
- const int K = (Side == KingSide ? 2 : 4);
- const File RookFile = (Side == KingSide ? FILE_H : FILE_A);
+ const int Shift = (Us == WHITE ? 8 : -8);
- Bitboard b = attack_span_mask(Us, s) & theirPawns & StormFilesBB;
- int bonus = 0;
+ Bitboard pawns;
+ int r, shelter = 0;
- while (b)
+ if (relative_rank(Us, ksq) <= RANK_4)
{
- // Give a bonus according to the distance of the nearest enemy pawn
- Square s2 = pop_1st_bit(&b);
- Rank r2 = square_rank(s2);
- int v = StormLeverBonus[f] - K * rank_distance(r, r2);
-
- // 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)))
- v *= (square_file(s2) == RookFile ? 4 : 2);
-
- bonus += v;
+ pawns = pos.pieces(PAWN, Us) & this_and_neighboring_files_bb(ksq);
+ r = ksq & (7 << 3);
+ for (int i = 0; i < 3; i++)
+ {
+ r += Shift;
+ shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (64 >> i);
+ }
}
- return bonus;
+ kingSquares[Us] = ksq;
+ kingShelters[Us] = make_score(shelter, 0);
+ return kingShelters[Us];
}
-
-/// PawnInfo::updateShelter calculates and caches king shelter. It is called
-/// only when king square changes, about 20% of total get_king_shelter() calls.
-int PawnInfo::updateShelter(const Position& pos, Color c, Square ksq) {
-
- Bitboard pawns = pos.pieces(PAWN, c) & this_and_neighboring_files_bb(ksq);
- unsigned shelter = 0;
- unsigned r = ksq & (7 << 3);
-
- for (int i = 1, k = (c ? -8 : 8); i < 4; i++)
- {
- r += k;
- shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (128 >> i);
- }
- kingSquares[c] = ksq;
- kingShelters[c] = shelter;
- return shelter;
-}
+// Explicit template instantiation
+template Score PawnInfo::updateShelter<WHITE>(const Position& pos, Square ksq);
+template Score PawnInfo::updateShelter<BLACK>(const Position& pos, Square ksq);