X-Git-Url: https://git.sesse.net/?p=remoteglot;a=blobdiff_plain;f=Board.pm;h=d2a6e0e425f7b48c8584c47e07e1692fd42ab604;hp=39c8134096b5897a0e7bd0ff47baad0441fe310f;hb=0a124edc28c716548327826127a9145da091a3d0;hpb=d40118a8adcb0da790ab1087296287e7eeab7c2c

diff --git a/Board.pm b/Board.pm
index 39c8134..d2a6e0e 100644
--- a/Board.pm
+++ b/Board.pm
@@ -221,6 +221,45 @@ sub fen {
 	return join('/', @rows);
 }
 
+# Returns a compact bit string describing the same data as fen().
+# This is encoded using a Huffman-like encoding, and should be
+# typically about 1/3 the number of bytes.
+sub bitpacked_fen {
+	my ($board) = @_;
+	my $bits = "";
+
+	for my $row (0..7) {
+		for my $col (0..7) {
+			my $piece = $board->[$row][$col];
+			if ($piece eq '-') {
+				$bits .= "0";
+				next;
+			}
+
+			my $color = (lc($piece) eq $piece) ? 0 : 1;
+			$bits .= "1" . $color;
+
+			if (lc($piece) eq 'p') {
+				$bits .= "0";
+			} elsif (lc($piece) eq 'n') {
+				$bits .= "100";
+			} elsif (lc($piece) eq 'b') {
+				$bits .= "101";
+			} elsif (lc($piece) eq 'r') {
+				$bits .= "1110";
+			} elsif (lc($piece) eq 'q') {
+				$bits .= "11110";
+			} elsif (lc($piece) eq 'k') {
+				$bits .= "11111";
+			} else {
+				die "Unknown piece $piece";
+			}
+		}
+	}
+
+	return pack('b*', $bits);
+}
+
 sub can_reach {
 	my ($board, $piece, $from_row, $from_col, $to_row, $to_col) = @_;