From d81f573a5e990af8eb8de5efdea8aa156aa97c1e Mon Sep 17 00:00:00 2001
From: H.G.Muller <hgm@hgm-xboard.(none)>
Date: Wed, 8 Nov 2017 11:30:05 +0100
Subject: [PATCH] Fix Seirawan gating at Rook square in PGN castling moves

The 'reverse gatings' were written as RxK also in PGN, which was ugly.
Now a file disambiguator behind the ID of the gated piece is used for
all castling gatings (also those at the King square). On input omission
of the disambiguator defaults to King square.
---
 moves.c  |   11 +++++++++--
 parser.c |   13 +++++++++++--
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/moves.c b/moves.c
index 6461583..a6b066b 100644
--- a/moves.c
+++ b/moves.c
@@ -2401,9 +2401,9 @@ CoordsToAlgebraic (Board board, int flags, int rf, int ff, int rt, int ft, int p
             ((ff == BOARD_WIDTH>>1 && (ft == BOARD_LEFT+2 || ft == BOARD_RGHT-2)) ||
              (ff == (BOARD_WIDTH-1)>>1 && (ft == BOARD_LEFT+1 || ft == BOARD_RGHT-3)))) {
             if(ft==BOARD_LEFT+1 || ft==BOARD_RGHT-2)
-	      snprintf(out, MOVE_LEN, "O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
+	      snprintf(out, MOVE_LEN, "O-O%c%c%c", promoChar ? '/' : 0, ToUpper(promoChar), ff + AAA);
             else
-	      snprintf(out, MOVE_LEN, "O-O-O%c%c", promoChar ? '/' : 0, ToUpper(promoChar));
+	      snprintf(out, MOVE_LEN, "O-O-O%c%c%c", promoChar ? '/' : 0, ToUpper(promoChar), ff + AAA);
 
 	    /* This notation is always unambiguous, unless there are
 	       kings on both the d and e files, with "wild castling"
@@ -2478,8 +2478,15 @@ CoordsToAlgebraic (Board board, int flags, int rf, int ff, int rt, int ft, int p
             *outp++ = ToUpper(promoChar);
         }
         else if (gameInfo.variant == VariantSChess && promoChar) { // and in S-Chess we have gating
+            ChessSquare victim = board[rt][ft];
+            if(piece == WhiteRook && victim == WhiteKing ||
+               piece == BlackRook && victim == BlackKing) {
+                strncpy(out, "O-O-O", MOVE_LEN);
+                outp = out + 3 + 2*(ft > ff);
+            }
             *outp++ = '/';
             *outp++ = ToUpper(promoChar);
+            if(out[0] == 'O') *outp++ = ff + AAA;
         }
 	*outp = NULLCHAR;
         return cl.kind;
diff --git a/parser.c b/parser.c
index 0938242..797a40c 100644
--- a/parser.c
+++ b/parser.c
@@ -642,9 +642,12 @@ badMove:// we failed to find algebraic move
 		    Match("OO", p) || Match("oo", p) || Match("00", p)) castlingType = 1;
 	    if(castlingType) { //code from old parser, collapsed for both castling types, and streamlined a bit
 		int rf, ff, rt, ft; ChessSquare king;
-		char promo=NULLCHAR;
+		char promo=NULLCHAR, gate = 0;
 
-		if(gameInfo.variant == VariantSChess) promo = PromoSuffix(p);
+		if(gameInfo.variant == VariantSChess) {
+		    promo = PromoSuffix(p);
+		    if(promo && **p >= 'a' && **p < AAA + BOARD_RGHT) gate = *(*p)++;
+		}
 
 		if (yyskipmoves) return (int) AmbiguousMove; /* not disambiguated */
 
@@ -680,6 +683,12 @@ badMove:// we failed to find algebraic move
 		    if (appData.debugMode) fprintf(debugFP, "Parser FRC (type=%d) %d %d\n", castlingType, ff, ft);
 		    if(ff == NoRights || ft == NoRights) return ImpossibleMove;
 		}
+		if(gate) { // gating disambiguator present
+		    if(gate != ff + AAA) {
+			int h = ft; ft = ff; ff = h; // reverse for gating at Rook square
+			if(gate != AAA + initialRights[castlingType+(wom?-1:2)]) return ImpossibleMove;
+		    }
+		}
 		sprintf(currentMoveString, "%c%c%c%c%c",ff+AAA,rf+ONE,ft+AAA,rt+ONE,promo);
 		if (appData.debugMode) fprintf(debugFP, "(%d-type) castling %d %d\n", castlingType, ff, ft);
 
-- 
1.7.0.4