From bf368bef696bee3555a370ac8ff88418e1f5c498 Mon Sep 17 00:00:00 2001
From: H.G. Muller <h.g.muller@hccnet.nl>
Date: Mon, 5 Oct 2009 20:01:53 -0700
Subject: [PATCH] new forceIllegalMoves option

The -forceIllegalMoves option uses setboard or edit to force a position when an engine refuses the move leading to it by an "Illegal Move" message.
Especially for engines using the edit command this was a bit tricky, because of the a2a3 kludge to avoid using the white and black commands.
---
 backend.c           |   23 +++++++++++++++++++++++
 common.h            |    1 +
 winboard/winboard.c |    1 +
 3 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/backend.c b/backend.c
index 304acc2..5fb842c 100644
--- a/backend.c
+++ b/backend.c
@@ -6390,6 +6390,29 @@ if(appData.debugMode) fprintf(debugFP, "nodes = %d, %lld\n", (int) programStats.
 	}
 #endif
 	if (pausing) PauseEvent();
+      if(appData.forceIllegal) {
+	    // [HGM] illegal: machine refused move; force position after move into it
+          SendToProgram("force\n", cps);
+          if(!cps->useSetboard) { // hideous kludge on kludge, because SendBoard sucks.
+		// we have a real problem now, as SendBoard will use the a2a3 kludge
+		// when black is to move, while there might be nothing on a2 or black
+		// might already have the move. So send the board as if white has the move.
+		// But first we must change the stm of the engine, as it refused the last move
+		SendBoard(cps, 0); // always kludgeless, as white is to move on boards[0]
+		if(WhiteOnMove(forwardMostMove)) {
+		    SendToProgram("a7a6\n", cps); // for the engine black still had the move
+		    SendBoard(cps, forwardMostMove); // kludgeless board
+		} else {
+		    SendToProgram("a2a3\n", cps); // for the engine white still had the move
+		    CopyBoard(boards[forwardMostMove+1], boards[forwardMostMove]);
+		    SendBoard(cps, forwardMostMove+1); // kludgeless board
+		}
+          } else SendBoard(cps, forwardMostMove); // FEN case, also sets stm properly
+	    if(gameMode == MachinePlaysWhite || gameMode == MachinePlaysBlack ||
+		 gameMode == TwoMachinesPlay)
+              SendToProgram("go\n", cps);
+	    return;
+      } else
 	if (gameMode == PlayFromGameFile) {
 	    /* Stop reading this game file */
 	    gameMode = EditGame;
diff --git a/common.h b/common.h
index fb218bc..83c6837 100644
--- a/common.h
+++ b/common.h
@@ -601,6 +601,7 @@ typedef struct {
     char *fenOverride1;
     char *fenOverride2;
     Boolean keepAlive;  /* [HGM] alive     */
+    Boolean forceIllegal;/*[HGM] illegal   */
 } AppData, *AppDataPtr;
 
 /* [AS] PGN tags (for showing in the game list) */
diff --git a/winboard/winboard.c b/winboard/winboard.c
index 3b2dd29..bbd8563 100644
--- a/winboard/winboard.c
+++ b/winboard/winboard.c
@@ -1339,6 +1339,7 @@ ArgDescriptor argDescriptors[] = {
   { "secondNeedsNoncompliantFEN", ArgString, (LPVOID) &appData.fenOverride2, FALSE },
   { "keepAlive", ArgInt, (LPVOID) &appData.keepAlive, FALSE },
   { "icstype", ArgInt, (LPVOID) &ics_type, FALSE },
+  { "forceIllegalMoves", ArgTrue, (LPVOID) &appData.forceIllegal, FALSE },
 
 #ifdef ZIPPY
   { "zippyTalk", ArgBoolean, (LPVOID) &appData.zippyTalk, FALSE },
-- 
1.7.0.4