my $row1 = pack 'C*', map 1+int( rand 2 ), 1..100;
my $row2 = pack 'C*', map 1+int( rand 2 ), 1..100;

substr( $row1, $_, 10 ) eq substr( $row2, $_, 10 )
        and print "Found match at offset; $_"
        for 0 .. length( $row1 ) - 10;