X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitbase.cpp;h=d6238395a2cecfa58b9a9402fcd46c0478f18488;hp=19cf3f7901f7eae4fc205bb065b426adf8368624;hb=6056a434191e97e61ff8657a50a1f645ca8dfb79;hpb=5dc23121215039938a9ef4e59ae934312774571c
diff --git a/src/bitbase.cpp b/src/bitbase.cpp
index 19cf3f79..d6238395 100644
--- a/src/bitbase.cpp
+++ b/src/bitbase.cpp
@@ -1,38 +1,26 @@
/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008 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
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 .
*/
-
-////
-//// Includes
-////
-
#include
-#include "bitbase.h"
#include "bitboard.h"
-#include "move.h"
-#include "square.h"
-
-
-////
-//// Local definitions
-////
+#include "types.h"
namespace {
@@ -46,304 +34,251 @@ namespace {
struct KPKPosition {
void from_index(int index);
- int to_index() const;
bool is_legal() const;
bool is_immediate_draw() const;
bool is_immediate_win() const;
- Bitboard wk_attacks() const;
- Bitboard bk_attacks() const;
- Bitboard pawn_attacks() const;
-
+ Bitboard wk_attacks() const { return StepAttacksBB[WK][whiteKingSquare]; }
+ Bitboard bk_attacks() const { return StepAttacksBB[BK][blackKingSquare]; }
+ Bitboard pawn_attacks() const { return StepAttacksBB[WP][pawnSquare]; }
+
Square whiteKingSquare, blackKingSquare, pawnSquare;
Color sideToMove;
};
-
-
- Result *Bitbase;
- const int IndexMax = 2*24*64*64;
- int UnknownCount = 0;
-
- void initialize();
- bool next_iteration();
- Result classify_wtm(const KPKPosition &p);
- Result classify_btm(const KPKPosition &p);
- int compute_index(Square wksq, Square bksq, Square psq, Color stm);
- int compress_result(Result r);
-
-}
+ // The possible pawns squares are 24, the first 4 files and ranks from 2 to 7
+ const int IndexMax = 2 * 24 * 64 * 64; // color * wp_sq * wk_sq * bk_sq
+
+ // Each uint32_t stores results of 32 positions, one per bit
+ uint32_t KPKBitbase[IndexMax / 32];
-////
-//// Functions
-////
+ Result classify_wtm(const KPKPosition& pos, const Result bb[]);
+ Result classify_btm(const KPKPosition& pos, const Result bb[]);
+ int compute_index(Square wksq, Square bksq, Square wpsq, Color stm);
+}
-void generate_kpk_bitbase(uint8_t bitbase[]) {
- // Allocate array and initialize:
- Bitbase = new Result[IndexMax];
- initialize();
- // Iterate until all positions are classified:
- while(next_iteration());
+uint32_t probe_kpk_bitbase(Square wksq, Square wpsq, Square bksq, Color stm) {
- // Compress bitbase into the supplied parameter:
- int i, j, b;
- for(i = 0; i < 24576; i++) {
- for(b = 0, j = 0; j < 8; b |= (compress_result(Bitbase[8*i+j]) << j), j++);
- bitbase[i] = b;
- }
+ int index = compute_index(wksq, bksq, wpsq, stm);
- // Release allocated memory:
- delete [] Bitbase;
+ return KPKBitbase[index / 32] & (1 << (index & 31));
}
-namespace {
+void init_kpk_bitbase() {
- void KPKPosition::from_index(int index) {
- int s;
- sideToMove = Color(index % 2);
- blackKingSquare = Square((index / 2) % 64);
- whiteKingSquare = Square((index / 128) % 64);
- s = (index / 8192) % 24;
- pawnSquare = make_square(File(s % 4), Rank(s / 4 + 1));
+ Result bb[IndexMax];
+ KPKPosition pos;
+ bool repeat;
+
+ // Initialize table
+ for (int i = 0; i < IndexMax; i++)
+ {
+ pos.from_index(i);
+ bb[i] = !pos.is_legal() ? RESULT_INVALID
+ : pos.is_immediate_draw() ? RESULT_DRAW
+ : pos.is_immediate_win() ? RESULT_WIN : RESULT_UNKNOWN;
}
+ // Iterate until all positions are classified (30 cycles needed)
+ do {
+ repeat = false;
- int KPKPosition::to_index() const {
- return compute_index(whiteKingSquare, blackKingSquare, pawnSquare,
- sideToMove);
- }
-
+ for (int i = 0; i < IndexMax; i++)
+ if (bb[i] == RESULT_UNKNOWN)
+ {
+ pos.from_index(i);
- bool KPKPosition::is_legal() const {
- if(whiteKingSquare == pawnSquare || whiteKingSquare == blackKingSquare ||
- pawnSquare == blackKingSquare)
- return false;
- if(sideToMove == WHITE) {
- if(bit_is_set(this->wk_attacks(), blackKingSquare))
- return false;
- if(bit_is_set(this->pawn_attacks(), blackKingSquare))
- return false;
- }
- else {
- if(bit_is_set(this->bk_attacks(), whiteKingSquare))
- return false;
- }
- return true;
- }
+ bb[i] = (pos.sideToMove == WHITE) ? classify_wtm(pos, bb)
+ : classify_btm(pos, bb);
+ if (bb[i] != RESULT_UNKNOWN)
+ repeat = true;
+ }
+ } while (repeat);
- bool KPKPosition::is_immediate_draw() const {
- if(sideToMove == BLACK) {
- Bitboard wka = this->wk_attacks();
- Bitboard bka = this->bk_attacks();
-
- // Case 1: Stalemate
- if((bka & ~(wka | this->pawn_attacks())) == EmptyBoardBB)
- return true;
-
- // Case 2: King can capture pawn
- if(bit_is_set(bka, pawnSquare) && !bit_is_set(wka, pawnSquare))
- return true;
- }
- else {
- // Case 1: Stalemate
- if(whiteKingSquare == SQ_A8 && pawnSquare == SQ_A7 &&
- (blackKingSquare == SQ_C7 || blackKingSquare == SQ_C8))
- return true;
- }
+ // Map 32 position results into one KPKBitbase[] entry
+ for (int i = 0; i < IndexMax / 32; i++)
+ for (int j = 0; j < 32; j++)
+ if (bb[32 * i + j] == RESULT_WIN || bb[32 * i + j] == RESULT_LOSS)
+ KPKBitbase[i] |= (1 << j);
+}
- return false;
- }
+namespace {
- bool KPKPosition::is_immediate_win() const {
- // The position is an immediate win if it is white to move and the white
- // pawn can be promoted without getting captured:
- return
- sideToMove == WHITE &&
- square_rank(pawnSquare) == RANK_7 &&
- (square_distance(blackKingSquare, pawnSquare+DELTA_N) > 1 ||
- bit_is_set(this->wk_attacks(), pawnSquare+DELTA_N));
- }
-
+ // A KPK bitbase index is an integer in [0, IndexMax] range
+ //
+ // Information is mapped in this way
+ //
+ // bit 0: side to move (WHITE or BLACK)
+ // bit 1- 6: black king square (from SQ_A1 to SQ_H8)
+ // bit 7-12: white king square (from SQ_A1 to SQ_H8)
+ // bit 13-14: white pawn file (from FILE_A to FILE_D)
+ // bit 15-17: white pawn rank - 1 (from RANK_2 - 1 to RANK_7 - 1)
- Bitboard KPKPosition::wk_attacks() const {
- return StepAttackBB[WK][whiteKingSquare];
- }
+ int compute_index(Square wksq, Square bksq, Square wpsq, Color stm) {
+
+ assert(square_file(wpsq) <= FILE_D);
+ int p = int(square_file(wpsq)) + 4 * int(square_rank(wpsq) - 1);
+ int r = int(stm) + 2 * int(bksq) + 128 * int(wksq) + 8192 * p;
- Bitboard KPKPosition::bk_attacks() const {
- return StepAttackBB[BK][blackKingSquare];
+ assert(r >= 0 && r < IndexMax);
+
+ return r;
}
+ void KPKPosition::from_index(int index) {
- Bitboard KPKPosition::pawn_attacks() const {
- return StepAttackBB[WP][pawnSquare];
+ int s = (index / 8192) % 24;
+
+ sideToMove = Color(index % 2);
+ blackKingSquare = Square((index / 2) % 64);
+ whiteKingSquare = Square((index / 128) % 64);
+ pawnSquare = make_square(File(s % 4), Rank(s / 4 + 1));
}
+ bool KPKPosition::is_legal() const {
- void initialize() {
- KPKPosition p;
- for(int i = 0; i < IndexMax; i++) {
- p.from_index(i);
- if(!p.is_legal())
- Bitbase[i] = RESULT_INVALID;
- else if(p.is_immediate_draw())
- Bitbase[i] = RESULT_DRAW;
- else if(p.is_immediate_win())
- Bitbase[i] = RESULT_WIN;
- else {
- Bitbase[i] = RESULT_UNKNOWN;
- UnknownCount++;
- }
+ if ( whiteKingSquare == pawnSquare
+ || whiteKingSquare == blackKingSquare
+ || blackKingSquare == pawnSquare)
+ return false;
+
+ if (sideToMove == WHITE)
+ {
+ if ( bit_is_set(wk_attacks(), blackKingSquare)
+ || bit_is_set(pawn_attacks(), blackKingSquare))
+ return false;
}
- }
+ else if (bit_is_set(bk_attacks(), whiteKingSquare))
+ return false;
+ return true;
+ }
- bool next_iteration() {
- KPKPosition p;
- int previousUnknownCount = UnknownCount;
-
- for(int i = 0; i < IndexMax; i++)
- if(Bitbase[i] == RESULT_UNKNOWN) {
- p.from_index(i);
+ bool KPKPosition::is_immediate_draw() const {
- Bitbase[i] = (p.sideToMove == WHITE)? classify_wtm(p) : classify_btm(p);
+ if (sideToMove == BLACK)
+ {
+ Bitboard wka = wk_attacks();
+ Bitboard bka = bk_attacks();
- if(Bitbase[i] == RESULT_WIN || Bitbase[i] == RESULT_LOSS ||
- Bitbase[i] == RESULT_DRAW)
- UnknownCount--;
- }
+ // Case 1: Stalemate
+ if ((bka & ~(wka | pawn_attacks())) == EmptyBoardBB)
+ return true;
- return UnknownCount != previousUnknownCount;
+ // Case 2: King can capture pawn
+ if (bit_is_set(bka, pawnSquare) && !bit_is_set(wka, pawnSquare))
+ return true;
+ }
+ else
+ {
+ // Case 1: Stalemate (possible pawn files are only from A to D)
+ if ( whiteKingSquare == SQ_A8
+ && pawnSquare == SQ_A7
+ && (blackKingSquare == SQ_C7 || blackKingSquare == SQ_C8))
+ return true;
+ }
+ return false;
}
+ bool KPKPosition::is_immediate_win() const {
- Result classify_wtm(const KPKPosition &p) {
+ // The position is an immediate win if it is white to move and the
+ // white pawn can be promoted without getting captured.
+ return sideToMove == WHITE
+ && square_rank(pawnSquare) == RANK_7
+ && whiteKingSquare != pawnSquare + DELTA_N
+ && ( square_distance(blackKingSquare, pawnSquare + DELTA_N) > 1
+ || bit_is_set(wk_attacks(), pawnSquare + DELTA_N));
+ }
+
+ Result classify_wtm(const KPKPosition& pos, const Result bb[]) {
// If one move leads to a position classified as RESULT_LOSS, the result
- // of the current position is RESULT_WIN. If all moves lead to positions
- // classified as RESULT_DRAW, the current position is classified as
- // RESULT_DRAW. Otherwise, the current position is classified as
- // RESULT_UNKNOWN.
+ // of the current position is RESULT_WIN. If all moves lead to positions
+ // classified as RESULT_DRAW, the current position is classified RESULT_DRAW
+ // otherwise the current position is classified as RESULT_UNKNOWN.
bool unknownFound = false;
Bitboard b;
Square s;
-
+ Result r;
+
// King moves
- b = p.wk_attacks();
- while(b) {
- s = pop_1st_bit(&b);
- switch(Bitbase[compute_index(s, p.blackKingSquare, p.pawnSquare,
- BLACK)]) {
- case RESULT_LOSS:
- return RESULT_WIN;
-
- case RESULT_UNKNOWN:
- unknownFound = true;
- break;
-
- case RESULT_DRAW: case RESULT_INVALID:
- break;
-
- default:
- assert(false);
- }
+ b = pos.wk_attacks();
+ while (b)
+ {
+ s = pop_1st_bit(&b);
+ r = bb[compute_index(s, pos.blackKingSquare, pos.pawnSquare, BLACK)];
+
+ if (r == RESULT_LOSS)
+ return RESULT_WIN;
+
+ if (r == RESULT_UNKNOWN)
+ unknownFound = true;
}
// Pawn moves
- if(square_rank(p.pawnSquare) < RANK_7) {
- s = p.pawnSquare + DELTA_N;
- switch(Bitbase[compute_index(p.whiteKingSquare, p.blackKingSquare, s,
- BLACK)]) {
- case RESULT_LOSS:
- return RESULT_WIN;
-
- case RESULT_UNKNOWN:
- unknownFound = true;
- break;
-
- case RESULT_DRAW: case RESULT_INVALID:
- break;
-
- default:
- assert(false);
- }
-
- if(square_rank(s) == RANK_3 &&
- s != p.whiteKingSquare && s != p.blackKingSquare) {
- s += DELTA_N;
- switch(Bitbase[compute_index(p.whiteKingSquare, p.blackKingSquare, s,
- BLACK)]) {
- case RESULT_LOSS:
- return RESULT_WIN;
-
- case RESULT_UNKNOWN:
- unknownFound = true;
- break;
-
- case RESULT_DRAW: case RESULT_INVALID:
- break;
-
- default:
- assert(false);
+ if (square_rank(pos.pawnSquare) < RANK_7)
+ {
+ s = pos.pawnSquare + DELTA_N;
+ r = bb[compute_index(pos.whiteKingSquare, pos.blackKingSquare, s, BLACK)];
+
+ if (r == RESULT_LOSS)
+ return RESULT_WIN;
+
+ if (r == RESULT_UNKNOWN)
+ unknownFound = true;
+
+ // Double pawn push
+ if ( square_rank(s) == RANK_3
+ && s != pos.whiteKingSquare
+ && s != pos.blackKingSquare)
+ {
+ s += DELTA_N;
+ r = bb[compute_index(pos.whiteKingSquare, pos.blackKingSquare, s, BLACK)];
+
+ if (r == RESULT_LOSS)
+ return RESULT_WIN;
+
+ if (r == RESULT_UNKNOWN)
+ unknownFound = true;
}
- }
}
-
- return unknownFound? RESULT_UNKNOWN : RESULT_DRAW;
+ return unknownFound ? RESULT_UNKNOWN : RESULT_DRAW;
}
- Result classify_btm(const KPKPosition &p) {
+ Result classify_btm(const KPKPosition& pos, const Result bb[]) {
// If one move leads to a position classified as RESULT_DRAW, the result
- // of the current position is RESULT_DRAW. If all moves lead to positions
+ // of the current position is RESULT_DRAW. If all moves lead to positions
// classified as RESULT_WIN, the current position is classified as
- // RESULT_LOSS. Otherwise, the current position is classified as
+ // RESULT_LOSS. Otherwise, the current position is classified as
// RESULT_UNKNOWN.
bool unknownFound = false;
Bitboard b;
Square s;
+ Result r;
// King moves
- b = p.bk_attacks();
- while(b) {
- s = pop_1st_bit(&b);
- switch(Bitbase[compute_index(p.whiteKingSquare, s, p.pawnSquare,
- WHITE)]) {
- case RESULT_DRAW:
- return RESULT_DRAW;
-
- case RESULT_UNKNOWN:
- unknownFound = true;
- break;
-
- case RESULT_WIN: case RESULT_INVALID:
- break;
-
- default:
- assert(false);
- }
- }
-
- return unknownFound? RESULT_UNKNOWN : RESULT_LOSS;
- }
+ b = pos.bk_attacks();
+ while (b)
+ {
+ s = pop_1st_bit(&b);
+ r = bb[compute_index(pos.whiteKingSquare, s, pos.pawnSquare, WHITE)];
+ if (r == RESULT_DRAW)
+ return RESULT_DRAW;
- int compute_index(Square wksq, Square bksq, Square psq, Color stm) {
- int p = int(square_file(psq)) + (int(square_rank(psq)) - 1) * 4;
- int result = int(stm) + 2*int(bksq) + 128*int(wksq) + 8192*p;
- assert(result >= 0 && result < IndexMax);
- return result;
+ if (r == RESULT_UNKNOWN)
+ unknownFound = true;
+ }
+ return unknownFound ? RESULT_UNKNOWN : RESULT_LOSS;
}
-
- int compress_result(Result r) {
- return (r == RESULT_WIN || r == RESULT_LOSS)? 1 : 0;
- }
-
-}
+}