new forceIllegalMoves option

[xboard.git] / backend.c

diff --git a/backend.c b/backend.c
index 304acc2..5fb842c 100644 (file)
--- 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;