Fix infinite loop in cylinder moves

[xboard.git] / moves.c

diff --git a/moves.c b/moves.c
index 647aa44..54f46c8 100644 (file)
--- a/moves.c
+++ b/moves.c
@@ -300,6 +300,9 @@ MovesFromString (Board board, int flags, int f, int r, int tx, int ty, int angle
                    break;
          case 'N': all = 0xFF;  // oblique atom (degenerate 8-fold)
                    if(tx >= 0) goto king;        // continuation legs specified in K/Q system!
+                   if(*desc == 'h') {            // chiral direction sets 'hr' and 'hl'
+                       dirSet = (desc[1] == 'r' ? 0x55 :  0xAA); desc += 2;
+                   } else
                    while(islower(*desc) && (i = dirType[*desc-'a']) != '0') {
                        int b = dirs2[*desc-'a']; // when alone, use narrow version
                        if(desc[1] == 'h') b = dirs1[*desc-'a'], desc += 2; // dirs1 is wide version
@@ -376,7 +379,7 @@ MovesFromString (Board board, int flags, int f, int r, int tx, int ty, int angle
        if(dy == 1) skip = jump - 1, jump = 1;        // on W & F atoms 'j' = skip first square
         do {
          for(dir=0, bit=1; dir<8; dir++, bit += bit) { // loop over directions
-           int i = expo, j = skip, hop = mode, vx, vy;
+           int i = expo, j = skip, hop = mode, vx, vy, loop = 0;
            if(!(bit & dirSet)) continue;             // does not move in this direction
            if(dy != 1) j = 0;                        // 
            vx = dx*rot[dir][0] + dy*rot[dir][1];     // rotate step vector
@@ -386,12 +389,12 @@ MovesFromString (Board board, int flags, int f, int r, int tx, int ty, int angle
            do {                                      // traverse ray
                x += vx; y += vy;                     // step to next square
                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(x <  BOARD_LEFT) { if(mode & 128) x += BOARD_RGHT - BOARD_LEFT, loop++; else break; }
+               if(x >= BOARD_RGHT) { if(mode & 128) x -= BOARD_RGHT - BOARD_LEFT, loop++; else break; }
                if(j) { j--; continue; }              // skip irrespective of occupation
                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(x == f && y == r)          occup = 4;     else                         // start square counts as empty
+               if(x == f && y == r && !loop) occup = 4;     else // start square counts as empty (if not around cylinder!)
                if(board[y][x] < BlackPawn)   occup = 0x101; else
                if(board[y][x] < EmptySquare) occup = 0x102; else
                                              occup = 4;
@@ -430,6 +433,7 @@ MovesFromString (Board board, int flags, int f, int r, int tx, int ty, int angle
                        cb(board, flags, mine == 1 ? WhiteKingSideCastle : BlackKingSideCastle, r, f, y, f + expo, cl);
                    break;
                }
+               if(mode & 16 && (board[y][x] == WhiteKing || board[y][x] == BlackKing)) break; // tame piece, cannot capture royal
                if(occup & mode) cb(board, flags, NormalMove, r, f, y, x, cl);    // allowed, generate
                if(occup != 4) break; // not valid transit square
            } while(--i);