use strict;
use warnings;
use Benchmark;
 
my $line = 'x' x 100;
 
open my $frontend, '>>', '/dev/null' or die $!;
 
Benchmark::cmpthese(-1, {
    _regex => \&_regex,
   # _unpack1 => \&_unpack1,
    _unpack2 => \&_unpack2
 });
 
 sub _regex {
     my $tmp_line = $line;
     if( length $tmp_line < 4000 ){
        $tmp_line .= "\t" x 30;
    }
    else{
         $tmp_line =~ s/(.{4000})/$1\t/g;
     }
     print $frontend $tmp_line;
 }
 
  
 sub _unpack2 {
     my $tmp_line = $line;
     my $len = length($tmp_line);
     my $pos = 0;
     my $tab = 30;
     
     if( length $tmp_line < 4000 ){
        $tmp_line .= "\t" x 30;
    }
    else {
     while ( my $s = unpack("x$pos A4000", $tmp_line) ) {
         $tab--;
         print $frontend "$s\t";
         $pos += 4000;
         last if $pos >= $len;
     }
    }
     print $frontend "\t" x $tab;
     print $frontend "\n";
}