$ cat bin2hex.pl
#!/usr/bin/perl
use strict; use warnings;

for my $b (qw(101101110101001010010100101000101011101010101010101010
              1  10 101 1010 10101 101010 11010011 000000000000001 0001111
              11111 11000011
)) {
    print "$b --> ", bin2hex($b), "\n";
}

sub bin2hex {
    my $bin = shift;

    # Make input bit string a multiple of 4
    $bin = substr("0000",length($bin)%4) . $bin if length($bin)%4;

    my ($hex, $nybble) = ("");
    while (length($bin)) {
        ($nybble,$bin) = (substr($bin,0,4), substr($bin,4));
        $nybble = eval "0b$nybble";
        $hex .= substr("0123456789ABCDEF", $nybble, 1);
    }
    return $hex;
}

$ perl bin2hex.pl
101101110101001010010100101000101011101010101010101010 --> 2DD4A528AEAAAA
1 --> 1
10 --> 2
101 --> 5
1010 --> A
10101 --> 15
101010 --> 2A
11010011 --> D3
000000000000001 --> 0001
0001111 --> 0F
11111 --> 1F
11000011 --> C3