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Introduce evaluate_pawn_storm() to unify redundant code

Browse source 
No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-05-14 10:42:53 +02:00
parent 0b49ec9822
commit ea5af9b8c0
2 changed files with 52 additions and 59 deletions
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102
src/pawns.cpp
View file

@ -143,7 +143,7 @@ void PawnInfo::clear() {
/// in a 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) {
PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const {
assert(pos.is_ok());
@ -178,13 +178,13 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) {
template<Color Us>
Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
Bitboard theirPawns, PawnInfo* pi) {
Bitboard theirPawns, PawnInfo* pi) const {
Bitboard b;
Square s, s2;
Square s;
File f;
Rank r, r2;
Rank r;
int bonus;
bool passed, isolated, doubled, opposed, chain, backward, candidate;
int bonus, v;
Score value = make_score(0, 0);
const Square* ptr = pos.piece_list_begin(Us, PAWN);
@ -205,60 +205,15 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN));
// We calculate kingside and queenside pawn storm scores for
// both colors. These are used when evaluating middle game
// positions with opposite side castling.
//
// Each pawn is given a base score given by a piece square table
// (KStormTable[] or QStormTable[]). Pawns which seem to have good
// chances of creating an open file by exchanging itself against
// an enemy pawn on an adjacent file gets an additional bonus.
// 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;
// Kingside pawn storms
bonus = KStormTable[relative_square(Us, s)];
if (f >= FILE_F)
{
b = outpost_mask(Us, s) & theirPawns & (FileFBB | FileGBB | FileHBB);
while (b)
{
// Give a bonus according to the distance of the nearest enemy pawn
s2 = pop_1st_bit(&b);
r2 = square_rank(s2);
v = StormLeverBonus[f] - 2 * rank_distance(r, r2);
bonus = (f <= FILE_C ? evaluate_pawn_storm<Us, QueenSide>(s, r, f, theirPawns) : 0);
pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus;
// 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) == FILE_H ? 4 : 2);
bonus += v;
}
}
pi->ksStormValue[Us] += bonus;
// Queenside pawn storms
bonus = QStormTable[relative_square(Us, s)];
if (f <= FILE_C)
{
b = outpost_mask(Us, s) & theirPawns & (FileABB | FileBBB | FileCBB);
while (b)
{
// Give a bonus according to the distance of the nearest enemy pawn
s2 = pop_1st_bit(&b);
r2 = square_rank(s2);
v = StormLeverBonus[f] - 4 * 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) == FILE_A ? 4 : 2);
bonus += v;
}
}
pi->qsStormValue[Us] += bonus;
// Our rank and previous one. Used for chain detection.
// 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
@ -342,6 +297,39 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns,
}
/// 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 {
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);
Bitboard b = outpost_mask(Us, s) & theirPawns & StormFilesBB;
int bonus = 0;
while (b)
{
// 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;
}
return bonus;
}
/// 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) {

9
src/pawns.h
View file

@ -78,14 +78,19 @@ private:
class PawnInfoTable {
enum SideType { KingSide, QueenSide };
public:
PawnInfoTable(unsigned numOfEntries);
~PawnInfoTable();
PawnInfo* get_pawn_info(const Position& pos);
PawnInfo* get_pawn_info(const Position& pos) const;
private:
template<Color Us>
Score evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi);
Score evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi) const;
template<Color Us, SideType Side>
int evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const;
unsigned size;
PawnInfo* entries;