96 lines
2.4 KiB
C++
96 lines
2.4 KiB
C++
/*
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Glaurung, a UCI chess playing engine.
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Copyright (C) 2004-2008 Tord Romstad
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Glaurung is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Glaurung is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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////
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//// Includes
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////
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#include <sstream>
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#include <string>
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#include "value.h"
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////
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//// Functions
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////
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/// value_to_tt() adjusts a mate score from "plies to mate from the root" to
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/// "plies to mate from the current ply". Non-mate scores are unchanged.
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/// The function is called before storing a value to the transposition table.
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Value value_to_tt(Value v, int ply) {
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if(v >= value_mate_in(100))
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return v + ply;
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else if(v <= value_mated_in(100))
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return v - ply;
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else
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return v;
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}
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/// value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score
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/// from the transposition table to a mate score corrected for the current
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/// ply depth.
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Value value_from_tt(Value v, int ply) {
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if(v >= value_mate_in(100))
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return v - ply;
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else if(v <= value_mated_in(100))
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return v + ply;
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else
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return v;
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}
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/// value_to_centipawns() converts a value from Glaurung's somewhat unusual
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/// scale of pawn = 256 to the more conventional pawn = 100.
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int value_to_centipawns(Value v) {
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return (int(v) * 100) / int(PawnValueMidgame);
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}
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/// value_from_centipawns() converts a centipawn value to Glaurung's internal
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/// evaluation scale. It's used when reading the values of UCI options
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/// containing material values (e.g. futility pruning margins).
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Value value_from_centipawns(int cp) {
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return Value((cp * 256) / 100);
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}
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/// value_to_string() converts a value to a string suitable for use with the
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/// UCI protocol.
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const std::string value_to_string(Value v) {
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std::stringstream s;
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if(abs(v) < VALUE_MATE - 200)
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s << "cp " << value_to_centipawns(v);
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else {
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s << "mate ";
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if(v > 0)
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s << (VALUE_MATE - v + 1) / 2;
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else
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s << -(VALUE_MATE + v) / 2;
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}
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return s.str();
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}
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