X-Git-Url: https://git.sesse.net/?p=remoteglot;a=blobdiff_plain;f=Position.pm;h=3e39e46f0f09ed2d762b6e3f3eca002b800e974b;hp=93bde53d334670e64a114f9881545ae37be8f987;hb=e961331f0f08ba475f53599442c0d330bd520c91;hpb=6dd4f0d4b11f86cc8490bbb0462259232fa80a7a

diff --git a/Position.pm b/Position.pm
index 93bde53..3e39e46 100644
--- a/Position.pm
+++ b/Position.pm
@@ -74,13 +74,13 @@ sub from_fen {
 	if ($castling =~ /Q/) {
 		$pos->{'white_castle_q'} = _col_num_to_letter(_find_piece_col($board->[7], 'R'));
 	}
-	while ($castling =~ s/([A-H])//g) {
+	while ($castling =~ s/([A-H])//) {
 		my $rook_col = lc($1);
-		my $king_col = _find_piece_col($board->[7], 'K');
-		if ($rook_col < $king_col) {
-			$pos->{'white_castle_q'} = _col_num_to_letter($rook_col);
+		my $king_col = _col_num_to_letter(_find_piece_col($board->[7], 'K'));
+		if ($rook_col lt $king_col) {
+			$pos->{'white_castle_q'} = $rook_col;
 		} else {
-			$pos->{'white_castle_k'} = _col_num_to_letter($rook_col);
+			$pos->{'white_castle_k'} = $rook_col;
 		}
 	}
 	if ($castling =~ /k/) {
@@ -89,13 +89,13 @@ sub from_fen {
 	if ($castling =~ /q/) {
 		$pos->{'black_castle_q'} = _col_num_to_letter(_find_piece_col($board->[0], 'r'));
 	}
-	while ($castling =~ s/([a-h])//g) {
+	while ($castling =~ s/([a-h])//) {
 		my $rook_col = $1;
-		my $king_col = _find_piece_col($board->[0], 'k');
-		if ($rook_col < $king_col) {
-			$pos->{'black_castle_q'} = _col_num_to_letter($rook_col);
+		my $king_col = _col_num_to_letter(_find_piece_col($board->[0], 'k'));
+		if ($rook_col lt $king_col) {
+			$pos->{'black_castle_q'} = $rook_col;
 		} else {
-			$pos->{'black_castle_k'} = _col_num_to_letter($rook_col);
+			$pos->{'black_castle_k'} = $rook_col;
 		}
 	}
 	$pos->{'time_since_100move_rule_reset'} = $halfmove_clock // 0;
@@ -275,8 +275,11 @@ sub make_move {
 		$np->{'black_castle_k'} = undef;
 	}
 
-	# 50-move rule.
-	if (lc($piece) eq 'p' || $dest_piece ne '-') {
+	# 50-move rule. Note that castle does not reset the counter, per FIDE rules.
+	my $castling = (lc($piece) eq 'k' && abs($from_col - $to_col) > 1) ||  # King moves two squares.
+		($piece eq 'K' && $dest_piece eq 'R') ||  # Chess960-style king-takes-rook.
+		($piece eq 'k' && $dest_piece eq 'r');
+	if (!$castling && (lc($piece) eq 'p' || $dest_piece ne '-')) {
 		$np->{'time_since_100move_rule_reset'} = 0;
 	} else {
 		$np->{'time_since_100move_rule_reset'} = $pos->{'time_since_100move_rule_reset'} + 1;