From d673eea800511d61eb78b80bc9062bef2ee9ad74 Mon Sep 17 00:00:00 2001
From: Peter Osterlund <peterosterlund2@gmail.com>
Date: Sun, 14 Feb 2016 20:33:51 +0100
Subject: [PATCH] DroidFish: Handle 50-move draw rule when "probe at root" is
 enabled in settings.

---
 .../src/org/petero/droidfish/tb/Probe.java     | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/DroidFish/src/org/petero/droidfish/tb/Probe.java b/DroidFish/src/org/petero/droidfish/tb/Probe.java
index a069118..6bb8e0d 100644
--- a/DroidFish/src/org/petero/droidfish/tb/Probe.java
+++ b/DroidFish/src/org/petero/droidfish/tb/Probe.java
@@ -280,18 +280,26 @@ public class Probe {
         UndoInfo ui = new UndoInfo();
         for (Move m : moveList) {
             pos.makeMove(m, ui);
+            int pliesToDraw = Math.max(100 - pos.halfMoveClock, 1);
             GtbProbeResult res = gtbProbe(pos);
             pos.unMakeMove(m, ui);
             if (res.result == GtbProbeResult.UNKNOWN) {
                 unknownMoves.add(m);
             } else {
                 int wScore;
-                if (res.result == GtbProbeResult.WMATE)
-                    wScore = MATE0 - res.pliesToMate;
-                else if (res.result == GtbProbeResult.BMATE)
-                    wScore = -(MATE0 - res.pliesToMate);
-                else
+                if (res.result == GtbProbeResult.WMATE) {
+                    if (res.pliesToMate <= pliesToDraw)
+                        wScore = MATE0 - res.pliesToMate;
+                    else
+                        wScore = 1;
+                } else if (res.result == GtbProbeResult.BMATE) {
+                    if (res.pliesToMate <= pliesToDraw)
+                        wScore = -(MATE0 - res.pliesToMate);
+                    else
+                        wScore = -1;
+                } else {
                     wScore = 0;
+                }
                 int score = pos.whiteMove ? wScore : -wScore;
                 if (score > bestScore) {
                     optimalMoves.clear();