Add board/position output to a bitpacked format.

[remoteglot] / Position.pm

diff --git a/Position.pm b/Position.pm
index 807b0035876e3a261dae1f2e0097c371d7160953..9d90cfc777e2576dcd275815c8089774040ecc8d 100644 (file)
--- a/Position.pm
+++ b/Position.pm
@@ -97,6 +97,35 @@ sub fen {
        return $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() };
 sub to_json_hash {
        my $pos = shift;
        my $json = { %$pos, fen => $pos->fen() };