From: H.G.Muller <hgm@hgm-xboard.(none)>
Date: Mon, 15 May 2017 13:15:08 +0000 (+0200)
Subject: Prevent pawn-drop mates in Shogi
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=d8482b77dca489c145a5a208cf1d4877907b7903;p=crazywa.git

Prevent pawn-drop mates in Shogi

In case of a mate we now check if the previous move was a Pawn drop,
and correct the score to a win if we detect one. In Crazyhouse we
test for check, and correct to draw due to stalemate without one.
---

diff --git a/dropper.c b/dropper.c
index e421cba..37111d0 100644
--- a/dropper.c
+++ b/dropper.c
@@ -1429,6 +1429,12 @@ if(PATH)printf("%d:%d:%d iter end, max=%d, alpha=%d start=%d\n", ply, depth,iter
 
     } while(iterDepth < maxDepth && (ply || !TimeIsUp(1)));   // IID loop
 
+    if(bestScore == -INF) { // we are mated!
+	if(perpLoses) {     // Shogi
+	    if(ff->fromSqr == handSlot[stm]) bestScore = INF; // mated by Pawn drop, so we win!
+	} else if(f.checker == CK_NONE) bestScore = 0;        // stalemate in zh is draw
+    }
+
   cutoff:
     // delayed-loss bonus
     bestScore += (bestScore < curEval);