Implement Betza o modifier for cylinder boards

[xboard.git] / moves.c

diff --git a/moves.c b/moves.c
index 054ee6b..a3eebcc 100644 (file)
--- a/moves.c
+++ b/moves.c
@@ -250,6 +250,7 @@ MovesFromString (Board board, int flags, int f, int r, char *desc, MoveCallback
        if(!mode) mode = his + 4;// no mode spec, use default = mc
        if(*desc == 'p') mode |= 32, desc++;
        if(*desc == 'g') mode |= 64, desc++;
+       if(*desc == 'o') mode |= 128, desc++;
        if(*desc == 'n') jump = 0, desc++;
        while(*desc == 'j') jump++, desc++;
        dx = xStep[*p-'A'] - '0';                     // step vector of atom
@@ -257,7 +258,9 @@ MovesFromString (Board board, int flags, int f, int r, char *desc, MoveCallback
        if(isdigit(*++p)) expo = atoi(p++);           // read exponent
        if(expo > 9) p++;                             // allow double-digit
        desc = p;                                     // this is start of next move
-       if(initial && board[r][f] != initialPosition[r][f]) continue;
+       if(initial && (board[r][f] != initialPosition[r][f] ||
+                      r == 0              && board[TOUCHED_W] & 1<<f ||
+                      r == BOARD_HEIGHT-1 && board[TOUCHED_B] & 1<<f   ) ) continue;
        if(expo > 1 && dx == 0 && dy == 0) {          // castling indicated by O + number
            mode |= 16; dy = 1;
        }
@@ -270,7 +273,9 @@ MovesFromString (Board board, int flags, int f, int r, char *desc, MoveCallback
            x = f; y = r;                             // start square
            do {
                x += vx; y += vy;                     // step to next square
-               if(y < 0 || y >= BOARD_HEIGHT || x < BOARD_LEFT || x >= BOARD_RGHT) break;
+               if(y < 0 || y >= BOARD_HEIGHT) break; // vertically off-board: always done
+               if(x <  BOARD_LEFT) { if(mode & 128) x += BOARD_RGHT - BOARD_LEFT; else break; }
+               if(x >= BOARD_RGHT) { if(mode & 128) x -= BOARD_RGHT - BOARD_LEFT; else break; }
                if(!jump    && board[y - vy + vy/2][x - vx + vx/2] != EmptySquare) break; // blocked
                if(jump > 1 && board[y - vy + vy/2][x - vx + vx/2] == EmptySquare) break; // no hop
                if(board[y][x] < BlackPawn)   occup = 1; else