X-Git-Url: https://git.sesse.net/?p=remoteglot;a=blobdiff_plain;f=Position.pm;h=9d90cfc777e2576dcd275815c8089774040ecc8d;hp=2e368f29fbbf7d8110edcc9c91472dc1821e5ae9;hb=0a124edc28c716548327826127a9145da091a3d0;hpb=ee7c89056c97c8b999034b5c7f2da0d7570b885f

diff --git a/Position.pm b/Position.pm
index 2e368f2..9d90cfc 100644
--- a/Position.pm
+++ b/Position.pm
@@ -75,27 +75,12 @@ sub fen {
 	my $ep = "-";
 	if ($pos->{'ep_file_num'} != -1) {
 		my $col = $pos->{'ep_file_num'};
-		my $nep = (qw(a b c d e f g h))[$col];
+		$ep = (qw(a b c d e f g h))[$col];
 
 		if ($pos->{'toplay'} eq 'B') {
-			$nep .= "3";
+			$ep .= "3";
 		} else {
-			$nep .= "6";
-		}
-
-		#
-		# Showing the en passant square when actually no capture can be made
-		# seems to confuse at least Rybka. Thus, check if there's actually
-		# a pawn of the opposite side that can do the en passant move, and if
-		# not, just lie -- it doesn't matter anyway. I'm unsure what's the
-		# "right" thing as per the standard, though.
-		#
-		if ($pos->{'toplay'} eq 'B') {
-			$ep = $nep if ($col > 0 && $pos->{'board'}[4][$col-1] eq 'p');
-			$ep = $nep if ($col < 7 && $pos->{'board'}[4][$col+1] eq 'p');
-		} else {
-			$ep = $nep if ($col > 0 && $pos->{'board'}[3][$col-1] eq 'P');
-			$ep = $nep if ($col < 7 && $pos->{'board'}[3][$col+1] eq 'P');
+			$ep .= "6";
 		}
 	}
 	$fen .= " ";
@@ -112,6 +97,35 @@ sub fen {
 	return $fen;
 }
 
+# Returns a compact bit string describing the same data as fen(),
+# except for the half-move and full-move clock.
+sub bitpacked_fen {
+	my $pos = shift;
+	my $board = $pos->{'board'}->bitpacked_fen();
+
+	my $bits = "";
+	if ($pos->{'toplay'} eq 'W') {
+		$bits .= "0";
+	} else {
+		$bits .= "1";
+	}
+
+	$bits .= $pos->{'white_castle_k'};
+	$bits .= $pos->{'white_castle_q'};
+	$bits .= $pos->{'black_castle_k'};
+	$bits .= $pos->{'black_castle_q'};
+
+	my $col = $pos->{'ep_file_num'};
+	if ($col == -1) {
+		$bits .= "0";
+	} else {
+		$bits .= "1";
+		$bits .= (qw(000 001 010 011 100 101 110 111))[$col];
+	}
+
+	return $board . pack('b*', $bits);
+}
+
 sub to_json_hash {
 	my $pos = shift;
 	my $json = { %$pos, fen => $pos->fen() };