Add board/position output to a bitpacked format.

[remoteglot] / Board.pm

diff --git a/Board.pm b/Board.pm
index 655b7f1bbb70a43ff56be1a3f17cdc26524aa8b3..d2a6e0e425f7b48c8584c47e07e1692fd42ab604 100644 (file)
--- a/Board.pm
+++ b/Board.pm
@@ -200,8 +200,11 @@ sub parse_pretty_move {
                        push @squares, [ $row, $col ];
                }
        }
+       if (scalar @squares == 0) {
+               die "Impossible move $move";
+       }
        if (scalar @squares != 1) {
-               die "Ambigious or impossible move $move";
+               die "Ambigious move $move";
        }
        return (@{$squares[0]}, $to_row, $to_col, $promo);
 }
@@ -218,6 +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) = @_;
        
@@ -425,6 +467,19 @@ sub prettyprint_move {
        return ($pretty, $nb);
 }
 
+sub num_pieces {
+       my ($board) = @_;
+
+       my $num = 0;
+       for my $row (0..7) {
+               for my $col (0..7) {
+                       my $piece = $board->[$row][$col];
+                       ++$num if ($piece ne '-');
+               }
+       }
+       return $num;    
+}
+
 sub _prettyprint_move_no_check_or_mate {
         my ($board, $from_row, $from_col, $to_row, $to_col, $promo) = @_;
        my $piece = $board->[$from_row][$from_col];