my $ep = "-";
if ($pos->{'ep_file_num'} != -1) {
my $col = $pos->{'ep_file_num'};
- my $nep = (qw(a b c d e f g h))[$col];
+ $ep = (qw(a b c d e f g h))[$col];
if ($pos->{'toplay'} eq 'B') {
- $nep .= "3";
+ $ep .= "3";
} else {
- $nep .= "6";
- }
-
- #
- # Showing the en passant square when actually no capture can be made
- # seems to confuse at least Rybka. Thus, check if there's actually
- # a pawn of the opposite side that can do the en passant move, and if
- # not, just lie -- it doesn't matter anyway. I'm unsure what's the
- # "right" thing as per the standard, though.
- #
- if ($pos->{'toplay'} eq 'B') {
- $ep = $nep if ($col > 0 && $pos->{'board'}[4][$col-1] eq 'p');
- $ep = $nep if ($col < 7 && $pos->{'board'}[4][$col+1] eq 'p');
- } else {
- $ep = $nep if ($col > 0 && $pos->{'board'}[3][$col-1] eq 'P');
- $ep = $nep if ($col < 7 && $pos->{'board'}[3][$col+1] eq 'P');
+ $ep .= "6";
}
}
$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() };