X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitbase.cpp;h=e21d1fe95360ecc8fed2acf1e227d73e32443609;hp=15a797d962514219c6dce9c8b5c5404c132d7b0e;hb=HEAD;hpb=8d6d0223bfe357001208147bede5029a857e5180 diff --git a/src/bitbase.cpp b/src/bitbase.cpp deleted file mode 100644 index 15a797d9..00000000 --- a/src/bitbase.cpp +++ /dev/null @@ -1,173 +0,0 @@ -/* - Stockfish, a UCI chess playing engine derived from Glaurung 2.1 - Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2013 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 - the Free Software Foundation, either version 3 of the License, or - (at your option) any later version. - - Stockfish is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program. If not, see . -*/ - -#include -#include - -#include "bitboard.h" -#include "types.h" - -namespace { - - // The possible pawns squares are 24, the first 4 files and ranks from 2 to 7 - const unsigned IndexMax = 2*24*64*64; // stm * psq * wksq * bksq = 196608 - - // Each uint32_t stores results of 32 positions, one per bit - uint32_t KPKBitbase[IndexMax / 32]; - - // A KPK bitbase index is an integer in [0, IndexMax] range - // - // Information is mapped in a way that minimizes number of iterations: - // - // bit 0- 5: white king square (from SQ_A1 to SQ_H8) - // bit 6-11: black king square (from SQ_A1 to SQ_H8) - // bit 12: side to move (WHITE or BLACK) - // bit 13-14: white pawn file (from FILE_A to FILE_D) - // bit 15-17: white pawn RANK_7 - rank (from RANK_7 - RANK_7 to RANK_7 - RANK_2) - unsigned index(Color us, Square bksq, Square wksq, Square psq) { - return wksq + (bksq << 6) + (us << 12) + (file_of(psq) << 13) + ((RANK_7 - rank_of(psq)) << 15); - } - - enum Result { - INVALID = 0, - UNKNOWN = 1, - DRAW = 2, - WIN = 4 - }; - - inline Result& operator|=(Result& r, Result v) { return r = Result(r | v); } - - struct KPKPosition { - - operator Result() const { return res; } - Result classify_leaf(unsigned idx); - Result classify(const std::vector& db) - { return us == WHITE ? classify(db) : classify(db); } - - private: - template Result classify(const std::vector& db); - - Color us; - Square bksq, wksq, psq; - Result res; - }; - -} // namespace - - -bool Bitbases::probe_kpk(Square wksq, Square wpsq, Square bksq, Color us) { - - assert(file_of(wpsq) <= FILE_D); - - unsigned idx = index(us, bksq, wksq, wpsq); - return KPKBitbase[idx / 32] & (1 << (idx & 0x1F)); -} - - -void Bitbases::init_kpk() { - - unsigned idx, repeat = 1; - std::vector db(IndexMax); - - // Initialize db with known win / draw positions - for (idx = 0; idx < IndexMax; idx++) - db[idx].classify_leaf(idx); - - // Iterate through the positions until no more of the unknown positions can be - // changed to either wins or draws (15 cycles needed). - while (repeat) - for (repeat = idx = 0; idx < IndexMax; idx++) - repeat |= (db[idx] == UNKNOWN && db[idx].classify(db) != UNKNOWN); - - // Map 32 results into one KPKBitbase[] entry - for (idx = 0; idx < IndexMax; idx++) - if (db[idx] == WIN) - KPKBitbase[idx / 32] |= 1 << (idx & 0x1F); -} - - -namespace { - - Result KPKPosition::classify_leaf(unsigned idx) { - - wksq = Square((idx >> 0) & 0x3F); - bksq = Square((idx >> 6) & 0x3F); - us = Color ((idx >> 12) & 0x01); - psq = File ((idx >> 13) & 0x03) | Rank(RANK_7 - (idx >> 15)); - - // Check if two pieces are on the same square or if a king can be captured - if ( square_distance(wksq, bksq) <= 1 || wksq == psq || bksq == psq - || (us == WHITE && (StepAttacksBB[PAWN][psq] & bksq))) - return res = INVALID; - - if (us == WHITE) - { - // Immediate win if pawn can be promoted without getting captured - if ( rank_of(psq) == RANK_7 - && wksq != psq + DELTA_N - && ( square_distance(bksq, psq + DELTA_N) > 1 - ||(StepAttacksBB[KING][wksq] & (psq + DELTA_N)))) - return res = WIN; - } - // Immediate draw if is stalemate or king captures undefended pawn - else if ( !(StepAttacksBB[KING][bksq] & ~(StepAttacksBB[KING][wksq] | StepAttacksBB[PAWN][psq])) - || (StepAttacksBB[KING][bksq] & psq & ~StepAttacksBB[KING][wksq])) - return res = DRAW; - - return res = UNKNOWN; - } - - template - Result KPKPosition::classify(const std::vector& db) { - - // White to Move: If one move leads to a position classified as WIN, the result - // of the current position is WIN. If all moves lead to positions classified - // as DRAW, the current position is classified DRAW otherwise the current - // position is classified as UNKNOWN. - // - // Black to Move: If one move leads to a position classified as DRAW, the result - // of the current position is DRAW. If all moves lead to positions classified - // as WIN, the position is classified WIN otherwise the current position is - // classified UNKNOWN. - - const Color Them = (Us == WHITE ? BLACK : WHITE); - - Result r = INVALID; - Bitboard b = StepAttacksBB[KING][Us == WHITE ? wksq : bksq]; - - while (b) - r |= Us == WHITE ? db[index(Them, bksq, pop_lsb(&b), psq)] - : db[index(Them, pop_lsb(&b), wksq, psq)]; - - if (Us == WHITE && rank_of(psq) < RANK_7) - { - Square s = psq + DELTA_N; - r |= db[index(BLACK, bksq, wksq, s)]; // Single push - - if (rank_of(psq) == RANK_2 && s != wksq && s != bksq) - r |= db[index(BLACK, bksq, wksq, s + DELTA_N)]; // Double push - } - - if (Us == WHITE) - return res = r & WIN ? WIN : r & UNKNOWN ? UNKNOWN : DRAW; - else - return res = r & DRAW ? DRAW : r & UNKNOWN ? UNKNOWN : WIN; - } - -} // namespace