DroidFish: Implemented DTZ/WDL tablebase hints in the GUI when only syzygy tablebases are available.

DroidFish/jni/rtb/tbprobe.cpp

@@ -0,0 +1,108 @@
+/*
+    Texel - A UCI chess engine.
+    Copyright (C) 2014  Peter Österlund, peterosterlund2@gmail.com
+
+    This program 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.
+
+    This program 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 <http://www.gnu.org/licenses/>.
+*/
+
+/*
+ * tbprobe.cpp
+ *
+ *  Created on: Jun 2, 2014
+ *      Author: petero
+ */
+
+#include "tbprobe.hpp"
+#include "rtb-probe.hpp"
+#include "bitBoard.hpp"
+#include "position.hpp"
+#include "moveGen.hpp"
+#include <unordered_map>
+#include <cassert>
+
+
+static std::string currentRtbPath;
+
+void
+TBProbe::initialize(const std::string& rtbPath) {
+    if (rtbPath != currentRtbPath) {
+        Syzygy::init(rtbPath);
+        currentRtbPath = rtbPath;
+    }
+}
+
+bool
+TBProbe::rtbProbeDTZ(Position& pos, int& score) {
+    const int nPieces = BitBoard::bitCount(pos.occupiedBB());
+    if (nPieces > Syzygy::TBLargest)
+        return false;
+    if (pos.getCastleMask())
+        return false;
+    if (MoveGen::canTakeKing(pos))
+        return false;
+
+    int success;
+    const int dtz = Syzygy::probe_dtz(pos, &success);
+    if (!success)
+        return false;
+    if (dtz == 0) {
+        score = 0;
+        return true;
+    }
+    const int maxHalfMoveClock = std::abs(dtz) + pos.getHalfMoveClock();
+    if (abs(dtz) <= 2) {
+        if (maxHalfMoveClock > 101) {
+            score = 0;
+            return true;
+        } else if (maxHalfMoveClock == 101)
+            return false; // DTZ can be wrong when mate-in-1
+    } else {
+        if (maxHalfMoveClock > 100) {
+            score = 0;
+            return true;
+        }
+    }
+    score = dtz;
+    return true;
+}
+
+bool
+TBProbe::rtbProbeWDL(Position& pos, int& score) {
+    if (BitBoard::bitCount(pos.occupiedBB()) > Syzygy::TBLargest)
+        return false;
+    if (pos.getCastleMask())
+        return false;
+    if (MoveGen::canTakeKing(pos))
+        return false;
+
+    int success;
+    int wdl = Syzygy::probe_wdl(pos, &success);
+    if (!success)
+        return false;
+    switch (wdl) {
+    case 0: case 1: case -1:
+        score = 0;
+        break;
+    case 2:
+        score = 1;
+        break;
+    case -2:
+        score = -1;
+        break;
+    default:
+        return false;
+    }
+
+    return true;
+}