Add board/position output to a bitpacked format.

diff --git a/Board.pm b/Board.pm
index 39c8134096b5897a0e7bd0ff47baad0441fe310f..d2a6e0e425f7b48c8584c47e07e1692fd42ab604 100644 (file)
--- a/Board.pm
+++ b/Board.pm
@@ -221,6 +221,45 @@ sub fen {
        return join('/', @rows);
 }
 
        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) = @_;
        
 sub can_reach {
        my ($board, $piece, $from_row, $from_col, $to_row, $to_col) = @_;
        

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() };