From: H.G.Muller Date: Thu, 24 Nov 2016 18:47:46 +0000 (+0100) Subject: Improve identification of e.p. victim X-Git-Url: http://winboard.nl/cgi-bin?p=xboard.git;a=commitdiff_plain;h=e30a78284219ac19697175114c16740c7aab850b Improve identification of e.p. victim The move generator now generates e.p. moves of default Pawns based on the file of the skipped square of the previous multi-push, rather than the e.p. rights (which were set only if ApplyMove suspects an e.p. capture is actually possible, which might not be the case when opponent Pawns do not capture as expected). A standard Pawn capturing to an empty square will now always capture the previously multi-pushed Pawn. Only if there is none it will guess where the victim should be based on FIDE rules, and would not capture any non-Pawns in that location. This heuristic should work for default Pawns against any other kind of Pawn. The existence of e.p. rights might not be recognized when comparing positions, however, so that rep draws could be declared after a two-fold repetition. --- diff --git a/backend.c b/backend.c index f465f95..c3a68e7 100644 --- a/backend.c +++ b/backend.c @@ -10213,16 +10213,16 @@ ParseGameHistory (char *game) void ApplyMove (int fromX, int fromY, int toX, int toY, int promoChar, Board board) { - ChessSquare captured = board[toY][toX], piece, pawn, king, killed, killed2; int p, rookX, oldEP, epRank, epFile, berolina = 0; + ChessSquare captured = board[toY][toX], piece, pawn, king, killed, killed2; int p, rookX, oldEP, epRank, epFile, lastFile, lastRank, berolina = 0; int promoRank = gameInfo.variant == VariantMakruk || gameInfo.variant == VariantGrand || gameInfo.variant == VariantChuChess ? 3 : 1; /* [HGM] compute & store e.p. status and castling rights for new position */ /* we can always do that 'in place', now pointers to these rights are passed to ApplyMove */ if(gameInfo.variant == VariantBerolina) berolina = EP_BEROLIN_A; - oldEP = (signed char)board[EP_FILE]; epRank = board[EP_RANK]; epFile = board[EP_FILE]; + oldEP = (signed char)board[EP_STATUS]; epRank = board[EP_RANK]; epFile = board[EP_FILE]; lastFile = board[LAST_FILE],lastRank = board[LAST_RANK]; board[EP_STATUS] = EP_NONE; - board[EP_FILE] = board[EP_RANK] = 100; + board[EP_FILE] = board[EP_RANK] = board[LAST_FILE] = board[LAST_RANK] = 100; if (fromY == DROP_RANK) { /* must be first */ @@ -10256,8 +10256,8 @@ ApplyMove (int fromX, int fromY, int toX, int toY, int promoChar, Board board) pawn = board[fromY][fromX]; if(pieceDesc[pawn] && strchr(pieceDesc[pawn], 'e')) { // piece with user-defined e.p. capture if(captured == EmptySquare && toX == epFile && (toY == (epRank & 127) || toY + (pawn < BlackPawn ? -1 : 1) == epRank - 128)) { - captured = board[epRank + (pawn < BlackPawn ? -1 : 1)][oldEP & berolina-1]; // remove victim - board[epRank + (pawn < BlackPawn ? -1 : 1)][oldEP & berolina-1] = EmptySquare; + captured = board[lastRank][lastFile]; // remove victim + board[lastRank][lastFile] = EmptySquare; pawn = EmptySquare; // kludge to suppress old e.p. code } } @@ -10278,6 +10278,7 @@ ApplyMove (int fromX, int fromY, int toX, int toY, int promoChar, Board board) if(toX fromX) board[EP_STATUS] = toX; + board[LAST_FILE] = toX; board[LAST_RANK] = toY; } } else if( pawn == BlackPawn ) { @@ -10291,6 +10292,7 @@ ApplyMove (int fromX, int fromY, int toX, int toY, int promoChar, Board board) if(toX fromX) board[EP_STATUS] = toX; + board[LAST_FILE] = toX; board[LAST_RANK] = toY; } } @@ -10385,18 +10387,16 @@ ApplyMove (int fromX, int fromY, int toX, int toY, int promoChar, Board board) board[toY][toX] = (ChessSquare) (PROMOTED(board[toY][toX])); board[fromY][fromX] = EmptySquare; } else if ((fromY >= BOARD_HEIGHT>>1) - && (oldEP == toX || oldEP == EP_UNKNOWN || appData.testLegality || abs(toX - fromX) > 4) + && (epFile == toX || oldEP == EP_UNKNOWN || appData.testLegality || abs(toX - fromX) > 4) && (toX != fromX) && gameInfo.variant != VariantXiangqi && gameInfo.variant != VariantBerolina && (pawn == WhitePawn) && (board[toY][toX] == EmptySquare)) { + if(lastFile == 100) lastFile = (board[fromY][toX] == BlackPawn ? toX : fromX), lastRank = fromY; // assume FIDE e.p. if victim present board[fromY][fromX] = EmptySquare; board[toY][toX] = piece; - if(toY == epRank - 128 + 1) - captured = board[toY - 2][toX], board[toY - 2][toX] = EmptySquare; - else - captured = board[toY - 1][toX], board[toY - 1][toX] = EmptySquare; + captured = board[lastRank][lastFile], board[lastRank][lastFile] = EmptySquare; } else if ((fromY == BOARD_HEIGHT-4) && (toX == fromX) && gameInfo.variant == VariantBerolina @@ -10452,18 +10452,16 @@ ApplyMove (int fromX, int fromY, int toX, int toY, int promoChar, Board board) board[toY][toX] = (ChessSquare) (PROMOTED(board[toY][toX])); board[fromY][fromX] = EmptySquare; } else if ((fromY < BOARD_HEIGHT>>1) - && (oldEP == toX || oldEP == EP_UNKNOWN || appData.testLegality || abs(toX - fromX) > 4) + && (epFile == toX && epRank == toY || oldEP == EP_UNKNOWN || appData.testLegality || abs(toX - fromX) > 4) && (toX != fromX) && gameInfo.variant != VariantXiangqi && gameInfo.variant != VariantBerolina && (pawn == BlackPawn) && (board[toY][toX] == EmptySquare)) { + if(lastFile == 100) lastFile = (board[fromY][toX] == WhitePawn ? toX : fromX), lastRank = fromY; board[fromY][fromX] = EmptySquare; board[toY][toX] = piece; - if(toY == epRank - 128 - 1) - captured = board[toY + 2][toX], board[toY + 2][toX] = EmptySquare; - else - captured = board[toY + 1][toX], board[toY + 1][toX] = EmptySquare; + captured = board[lastRank][lastFile], board[lastRank][lastFile] = EmptySquare; } else if ((fromY == 3) && (toX == fromX) && gameInfo.variant == VariantBerolina diff --git a/common.h b/common.h index 9a4c2c4..2aff360 100644 --- a/common.h +++ b/common.h @@ -181,6 +181,8 @@ typedef char *String; #define BOARD_RGHT (gameInfo.boardWidth + gameInfo.holdingsWidth) #define CASTLING (BOARD_RANKS-1) /* [HGM] hide in upper rank */ #define VIRGIN (BOARD_RANKS-2) /* [HGM] pieces not moved */ +#define LAST_RANK CASTLING][(BOARD_FILES-8) /* [HGM] in upper rank */ +#define LAST_FILE CASTLING][(BOARD_FILES-7) /* [HGM] in upper rank */ #define TOUCHED_W CASTLING][(BOARD_FILES-6) /* [HGM] in upper rank */ #define TOUCHED_B CASTLING][(BOARD_FILES-5) /* [HGM] in upper rank */ #define EP_RANK CASTLING][(BOARD_FILES-4) /* [HGM] in upper rank */ diff --git a/moves.c b/moves.c index 2f6a706..876564c 100644 --- a/moves.c +++ b/moves.c @@ -809,9 +809,10 @@ GenPseudoLegal (Board board, int flags, MoveCallback callback, VOIDSTAR closure, rf, ff, rf + 1, ff + s, closure); } if (rf >= BOARD_HEIGHT+1>>1) {// [HGM] grand: 4th & 5th rank on 10-board + int victimFile = (board[LAST_FILE] == 100 ? ff + s : board[LAST_FILE]); if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && - (epfile == ff + s || epfile == EP_UNKNOWN) && rf < BOARD_HEIGHT-3 && - board[rf][ff + s] == BlackPawn && + (board[EP_FILE] == ff + s || epfile == EP_UNKNOWN) && rf < BOARD_HEIGHT-3 && + (board[rf][victimFile] == BlackPawn || board[rf][victimFile] == BlackLance) && board[rf+1][ff + s] == EmptySquare) { callback(board, flags, WhiteCapturesEnPassant, rf, ff, rf+1, ff + s, closure); @@ -859,9 +860,10 @@ GenPseudoLegal (Board board, int flags, MoveCallback callback, VOIDSTAR closure, rf, ff, rf - 1, ff + s, closure); } if (rf < BOARD_HEIGHT>>1) { + int victimFile = (board[LAST_FILE] == 100 ? ff + s : board[LAST_FILE]); if (ff + s >= BOARD_LEFT && ff + s < BOARD_RGHT && - (epfile == ff + s || epfile == EP_UNKNOWN) && rf > 2 && - board[rf][ff + s] == WhitePawn && + (board[EP_FILE] == ff + s || epfile == EP_UNKNOWN) && rf > 2 && + (board[rf][victimFile] == WhitePawn || board[rf][victimFile] == WhiteLance) && board[rf-1][ff + s] == EmptySquare) { callback(board, flags, BlackCapturesEnPassant, rf, ff, rf-1, ff + s, closure);