Fix min-Shogi promotion zone

In integer arithmetic N*2/3 is not the same as N - N/3, with as a result
that the white promotion zone was 2 ranks deep on 5x5 boards. This only
happened in LegalityTest, but because this would classify all moves to
4th rank an non-promotions, they would be printed with a faulty
deferral (=) sign as promochar in SAN.

diff --git a/moves.c b/moves.c
index 5f4b3f9..ecd7b48 100644 (file)
--- a/moves.c
+++ b/moves.c
@@ -1151,7 +1151,7 @@ if(appData.debugMode)fprintf(debugFP,"SHOGI promoChar = %c\n", promoChar ? promo
                 return CharToPiece(promoChar) == EmptySquare ? ImpossibleMove : IllegalMove;
             else if(flags & F_WHITE_ON_MOVE) {
                 if( (int) piece < (int) WhiteWazir &&
-                     (rf >= BOARD_HEIGHT*2/3 || rt >= BOARD_HEIGHT*2/3) ) {
+                     (rf >= BOARD_HEIGHT - BOARD_HEIGHT/3 || rt >= BOARD_HEIGHT - BOARD_HEIGHT/3) ) {
                     if( (piece == WhitePawn || piece == WhiteQueen) && rt > BOARD_HEIGHT-2 ||
                          piece == WhiteKnight && rt > BOARD_HEIGHT-3) /* promotion mandatory */
                        cl.kind = promoChar == '=' ? IllegalMove : WhitePromotion;