Let FENs handle Betza initial rights in castlingless variants

When a variant has no castling, or is redefined to have no castling
through a 'piece' command for the King, the FEN castling field of a
written FEN will now contain the file ID of all pieces with initial
('i') moves in their Betza definition. On reading the virginity of
pieces not thus mentioned in the castling field will get their
virginity revoked.

diff --git a/backend.c b/backend.c
index 417d452..a7be826 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -17894,7 +17894,7 @@ char *
 PositionToFEN (int move, char *overrideCastling, int moveCounts)
 {
     int i, j, fromX, fromY, toX, toY;
-    int whiteToPlay;
+    int whiteToPlay, haveRights = nrCastlingRights;
     char buf[MSG_SIZ];
     char *p, *q;
     int emptycount;
@@ -17968,10 +17968,28 @@ PositionToFEN (int move, char *overrideCastling, int moveCounts)
     *p++ = whiteToPlay ? 'w' : 'b';
     *p++ = ' ';
 
+  if(pieceDesc[WhiteKing] && strchr(pieceDesc[WhiteKing], 'i') && !strchr(pieceDesc[WhiteKing], 'O')) { // redefined without castling
+    haveRights = 0; q = p;
+    for(i=BOARD_RGHT-1; i>=BOARD_LEFT; i--) {
+      piece = boards[move][0][i];
+      if(piece >= WhitePawn && piece <= WhiteKing && pieceDesc[piece] && strchr(pieceDesc[piece], 'i')) { // piece with initial move
+        if(!(boards[move][TOUCHED_W] & 1<<i)) *p++ = 'A' + i; // print file ID if it has not moved
+      }
+    }
+    for(i=BOARD_RGHT-1; i>=BOARD_LEFT; i--) {
+      piece = boards[move][BOARD_HEIGHT-1][i];
+      if(piece >= BlackPawn && piece <= BlackKing && pieceDesc[piece] && strchr(pieceDesc[piece], 'i')) { // piece with initial move
+        if(!(boards[move][TOUCHED_B] & 1<<i)) *p++ = 'a' + i; // print file ID if it has not moved
+      }
+    }
+    if(p == q) *p++ = '-';
+    *p++ = ' ';
+  }
+
   if(q = overrideCastling) { // [HGM] FRC: override castling & e.p fields for non-compliant engines
     while(*p++ = *q++); if(q != overrideCastling+1) p[-1] = ' '; else --p;
   } else {
-  if(nrCastlingRights) {
+  if(haveRights) {
      int handW=0, handB=0;
      if(gameInfo.variant == VariantSChess) { // for S-Chess, all virgin backrank pieces must be listed
        for(i=0; i<BOARD_HEIGHT; i++) handW += boards[move][i][BOARD_RGHT]; // count white held pieces
@@ -18291,6 +18309,21 @@ ParseFEN (Board board, int *blackPlaysFirst, char *fen, Boolean autoSize)
                                  && board[castlingRank[5]][initialRights[5]] != BlackKing) board[CASTLING][5] = NoRights;
     FENrulePlies = 0;
 
+    if(pieceDesc[WhiteKing] && strchr(pieceDesc[WhiteKing], 'i') && !strchr(pieceDesc[WhiteKing], 'O')) { // redefined without castling
+      char *q = p;
+      int w=0, b=0;
+      while(isalpha(*p)) {
+        if(isupper(*p)) w |= 1 << (*p++ - 'A');
+        if(islower(*p)) b |= 1 << (*p++ - 'a');
+      }
+      if(*p == '-') p++;
+      if(p != q) {
+        board[TOUCHED_W] = ~w;
+        board[TOUCHED_B] = ~b;
+        while(*p == ' ') p++;
+      }
+    } else
+
     if(nrCastlingRights) {
       int fischer = 0;
       if(gameInfo.variant == VariantSChess) for(i=0; i<BOARD_FILES; i++) virgin[i] = 0;