From d0de6f924767f55674690243ebdf126fd98e4906 Mon Sep 17 00:00:00 2001
From: H.G. Muller <h.g.muller@hccnet.nl>
Date: Thu, 16 Sep 2010 18:58:37 +0200
Subject: [PATCH] Extend mate test to drop games

MateTest() in case of no legal moves now also looks if there are legal
drops that can resolve the check. This provides reliable mate testing in
Crazyhouse and Shogi, so these are now made subject to adjudications too.
---
 backend.c |    4 +---
 moves.c   |    9 +++++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/backend.c b/backend.c
index 12cef35..d539198 100644
--- a/backend.c
+++ b/backend.c
@@ -6666,8 +6666,7 @@ Adjudicate(ChessProgramState *cps)
 	ChessProgramState *engineOpponent = (gameMode == TwoMachinesPlay ? cps->other : (cps ? NULL : &first));
 	Boolean canAdjudicate = !appData.icsActive;
 
-	// most tests only when we understand the game, i.e. legality-checking on, and (for the time being) no piece drops
-	if(gameInfo.holdingsSize == 0 || gameInfo.variant == VariantSuper || gameInfo.variant == VariantGreat) {
+	// most tests only when we understand the game, i.e. legality-checking on
 	    if( appData.testLegality )
 	    {   /* [HGM] Some more adjudications for obstinate engines */
 		int nrW, nrB, bishopColor, staleW, staleB, nr[EmptySquare+1], i;
@@ -6819,7 +6818,6 @@ Adjudicate(ChessProgramState *cps)
                      }
                 } else moveCount = 6;
 	    }
-	}
 	  
 	if (appData.debugMode) { int i;
 	    fprintf(debugFP, "repeat test fmm=%d bmm=%d ep=%d, reps=%d\n",
diff --git a/moves.c b/moves.c
index f4f33b2..3e58f42 100644
--- a/moves.c
+++ b/moves.c
@@ -1219,6 +1219,15 @@ int MateTest(board, flags)
     if (cl.count > 0) {
 	return inCheck ? MT_CHECK : MT_NONE;
     } else {
+        if(gameInfo.holdingsWidth && gameInfo.variant != VariantSuper || gameInfo.variant != VariantGreat) { // drop game
+            int r, f, n, holdings = flags & F_WHITE_ON_MOVE ? BOARD_WIDTH-1 : 0;
+            for(r=0; r<BOARD_HEIGHT; r++) for(f=BOARD_LEFT; f<BOARD_RGHT; f++) if(board[r][f] == EmptySquare) // all empty squares
+                for(n=0; n<BOARD_HEIGHT; n++) // all pieces in hand
+                    if(board[n][holdings] != EmptySquare) {
+                        int moveType = LegalDrop(board, flags, board[n][holdings], r, f);
+                        if(moveType == WhiteDrop || moveType == BlackDrop) return MT_CHECK; // we can resolve check by legal drop
+                    }
+        }
 	if(gameInfo.variant == VariantSuicide) // [HGM] losers: always stalemate, since no check, but result varies
 		return myPieces == hisPieces ? MT_STALEMATE :
 					myPieces > hisPieces ? MT_STAINMATE : MT_STEALMATE;
-- 
1.7.0.4