Fix engine stall on perpetual-check evasion

The adjudication code had already put the engine in force mode after
postponing the actual adjudication to the next move. Now first determine
if we want to adjudicate now, and with which result, before stopping the
engine and ending the game.

diff --git a/backend.c b/backend.c
index 031141a..53799ec 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -6839,11 +6839,8 @@ Adjudicate(ChessProgramState *cps)
                         if( rights == 0 && ++count > appData.drawRepeats-2 && canAdjudicate
                             && appData.drawRepeats > 1) {
                              /* adjudicate after user-specified nr of repeats */
-                            if(engineOpponent) {
-                              SendToProgram("force\n", engineOpponent); // suppress reply
-                              SendMoveToProgram(forwardMostMove-1, engineOpponent); /* make sure opponent gets to see move */
-                            }
-                             ShowMove(fromX, fromY, toX, toY); /*updates currentMove*/
+                            int result = GameIsDrawn;
+                            char *details = "XBoard adjudication: repetition draw";
                             if(gameInfo.variant == VariantXiangqi && appData.testLegality) { 
                                // [HGM] xiangqi: check for forbidden perpetuals
                                int m, ourPerpetual = 1, hisPerpetual = 1;
@@ -6856,27 +6853,31 @@ Adjudicate(ChessProgramState *cps)
                                if(appData.debugMode) fprintf(debugFP, "XQ perpetual test, our=%d, his=%d\n",
                                                                        ourPerpetual, hisPerpetual);
                                if(ourPerpetual && !hisPerpetual) { // we are actively checking him: forfeit
-                                   GameEnds( WhiteOnMove(forwardMostMove) ? WhiteWins : BlackWins, 
-                                          "Xboard adjudication: perpetual checking", GE_XBOARD );
-                                   return 1;
-                               }
-                               if(hisPerpetual && !ourPerpetual)   // he is checking us, but did not repeat yet
+                                   result = WhiteOnMove(forwardMostMove) ? WhiteWins : BlackWins;
+                                   details = "Xboard adjudication: perpetual checking";
+                               } else
+                               if(hisPerpetual && !ourPerpetual) { // he is checking us, but did not repeat yet
                                    break; // (or we would have caught him before). Abort repetition-checking loop.
+                               } else
                                // Now check for perpetual chases
                                if(!ourPerpetual && !hisPerpetual) { // no perpetual check, test for chase
                                    hisPerpetual = PerpetualChase(k, forwardMostMove);
                                    ourPerpetual = PerpetualChase(k+1, forwardMostMove);
                                    if(ourPerpetual && !hisPerpetual) { // we are actively chasing him: forfeit
-                                       GameEnds( WhiteOnMove(forwardMostMove) ? WhiteWins : BlackWins, 
-                                                     "Xboard adjudication: perpetual chasing", GE_XBOARD );
-                                       return 1;
-                                   }
+                                       result = WhiteOnMove(forwardMostMove) ? WhiteWins : BlackWins;
+                                       details = "Xboard adjudication: perpetual chasing";
+                                   } else
                                    if(hisPerpetual && !ourPerpetual)   // he is chasing us, but did not repeat yet
                                        break; // Abort repetition-checking loop.
                                }
                                // if neither of us is checking or chasing all the time, or both are, it is draw
                             }
-                             GameEnds( GameIsDrawn, "Xboard adjudication: repetition draw", GE_XBOARD );
+                            if(engineOpponent) {
+                              SendToProgram("force\n", engineOpponent); // suppress reply
+                              SendMoveToProgram(forwardMostMove-1, engineOpponent); /* make sure opponent gets to see move */
+                            }
+                             ShowMove(fromX, fromY, toX, toY); /*updates currentMove*/
+                             GameEnds( result, details, GE_XBOARD );
                              return 1;
                         }
                         if( rights == 0 && count > 1 ) /* occurred 2 or more times before */