Adjudicate perpetual checks as loss also in Shogi

The Xiangqi code for recognizing perpetual checks is now also activated for
Shogi, but in this case we bail out before checking for perpetual chases.
The mini-Shogi case is then recognized as a win for gote.

diff --git a/backend.c b/backend.c
index aafb11f..67e2d1b 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -7859,7 +7859,7 @@ Adjudicate (ChessProgramState *cps)
                              /* adjudicate after user-specified nr of repeats */
                             int result = GameIsDrawn;
                             char *details = "XBoard adjudication: repetition draw";
-                            if(gameInfo.variant == VariantXiangqi && appData.testLegality) {
+                            if((gameInfo.variant == VariantXiangqi || gameInfo.variant == VariantShogi) && appData.testLegality) {
                                // [HGM] xiangqi: check for forbidden perpetuals
                                int m, ourPerpetual = 1, hisPerpetual = 1;
                                for(m=forwardMostMove; m>k; m-=2) {
@@ -7877,6 +7877,12 @@ Adjudicate (ChessProgramState *cps)
                                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
+                               if(gameInfo.variant == VariantShogi) { // in Shogi other repetitions are draws
+                                   if(BOARD_HEIGHT == 5 && BOARD_RGHT - BOARD_LEFT == 5) { // but in mini-Shogi gote wins!
+                                       result = BlackWins;
+                                       details = "Xboard adjudication: repetition";
+                                   }
+                               } else // it must be XQ
                                // Now check for perpetual chases
                                if(!ourPerpetual && !hisPerpetual) { // no perpetual check, test for chase
                                    hisPerpetual = PerpetualChase(k, forwardMostMove);