From: Marco Costalba Date: Sat, 9 Apr 2011 18:50:56 +0000 (+0100) Subject: Assorted code style and comments in pawns.cpp and pawns.h X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=2f1935078da225c90f7887ed8c345cc7baebcfcc Assorted code style and comments in pawns.cpp and pawns.h The only interesting thing is that a backward or isolated pawn cannot be a candidate passer, so code this condition. No functional change. Signed-off-by: Marco Costalba --- diff --git a/src/pawns.cpp b/src/pawns.cpp index 6fc2f2fe..997aa214 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -17,27 +17,15 @@ along with this program. If not, see . */ - -//// -//// Includes -//// - #include -#include +#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 @@ -77,14 +65,9 @@ namespace { } -//// -//// Functions -//// - - /// 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 { @@ -100,11 +83,11 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { 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); @@ -124,13 +107,16 @@ PawnInfo* PawnInfoTable::get_pawn_info(const Position& pos) const { template Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi) const { + + const BitCountType Max15 = CpuIs64Bit ? CNT64_MAX15 : CNT32_MAX15; + 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); // Loop through all pawns of the current color and score each pawn @@ -144,11 +130,11 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, // 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); @@ -156,15 +142,13 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, chain = ourPawns & neighboring_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 neighboring 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(s, Us) & theirPawns)) { // We now know that there are no friendly pawns beside or behind this @@ -178,21 +162,24 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, 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 + // 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(b) >= count_1s(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); @@ -214,3 +201,33 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, } 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 +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_neighboring_files_bb(ksq); + r = ksq & (7 << 3); + for (int i = 0; i < 3; i++) + { + r += Shift; + shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (64 >> i); + } + } + kingSquares[Us] = ksq; + kingShelters[Us] = make_score(shelter, 0); + return kingShelters[Us]; +} + +// Explicit template instantiation +template Score PawnInfo::updateShelter(const Position& pos, Square ksq); +template Score PawnInfo::updateShelter(const Position& pos, Square ksq); diff --git a/src/pawns.h b/src/pawns.h index 549aafa9..cc3e5e66 100644 --- a/src/pawns.h +++ b/src/pawns.h @@ -20,7 +20,6 @@ #if !defined(PAWNS_H_INCLUDED) #define PAWNS_H_INCLUDED -#include "bitboard.h" #include "position.h" #include "tt.h" #include "types.h" @@ -66,28 +65,14 @@ private: /// method is get_pawn_info, which returns a pointer to a PawnInfo object. class PawnInfoTable : public SimpleHash { - - enum SideType { KingSide, QueenSide }; - public: PawnInfo* get_pawn_info(const Position& pos) const; - void prefetch(Key key) const; private: template Score evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi) const; }; -inline Square pawn_push(Color c) { - return c == WHITE ? DELTA_N : DELTA_S; -} - -inline void PawnInfoTable::prefetch(Key key) const { - - unsigned index = unsigned(key & (PawnTableSize - 1)); - PawnInfo* pi = entries + index; - ::prefetch((char*) pi); -} inline Score PawnInfo::pawns_value() const { return value; @@ -102,7 +87,7 @@ inline Bitboard PawnInfo::passed_pawns(Color c) const { } inline int PawnInfo::file_is_half_open(Color c, File f) const { - return (halfOpenFiles[c] & (1 << int(f))); + return halfOpenFiles[c] & (1 << int(f)); } inline int PawnInfo::has_open_file_to_left(Color c, File f) const { @@ -113,31 +98,6 @@ inline int PawnInfo::has_open_file_to_right(Color c, File f) const { return halfOpenFiles[c] & ~((1 << int(f+1)) - 1); } -/// PawnInfo::updateShelter() calculates and caches king shelter. It is called -/// only when king square changes, about 20% of total king_shelter() calls. -template -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_neighboring_files_bb(ksq); - r = square_rank(ksq) * 8; - for (int i = 1; i < 4; i++) - { - r += Shift; - shelter += BitCount8Bit[(pawns >> r) & 0xFF] * (128 >> i); - } - } - kingSquares[Us] = ksq; - kingShelters[Us] = make_score(shelter, 0); - return kingShelters[Us]; -} - template inline Score PawnInfo::king_shelter(const Position& pos, Square ksq) { return kingSquares[Us] == ksq ? kingShelters[Us] : updateShelter(pos, ksq); diff --git a/src/tt.h b/src/tt.h index 5ca5c237..fe4cee62 100644 --- a/src/tt.h +++ b/src/tt.h @@ -51,6 +51,7 @@ public: virtual ~SimpleHash() { delete [] entries; } Entry* find(Key key) const { return entries + ((uint32_t)key & (HashSize - 1)); } + void prefetch(Key key) const { ::prefetch((char*)find(key)); } protected: Entry* entries; diff --git a/src/types.h b/src/types.h index bf0a03f4..f5e30c74 100644 --- a/src/types.h +++ b/src/types.h @@ -463,4 +463,8 @@ inline bool square_is_ok(Square s) { return s >= SQ_A1 && s <= SQ_H8; } +inline Square pawn_push(Color c) { + return c == WHITE ? DELTA_N : DELTA_S; +} + #endif // !defined(TYPES_H_INCLUDED)