# 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) = @_;
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() };