#!/usr/bin/perl -w
use strict;
use warnings;
use Fcntl qw (:DEFAULT :flock);
use Digest::CRC;

my $datei = 'test_crc.txt';
my $fh;

# Datei erzeugen
srand (time ^ $$);
my @atoms = ('a'..'z', 'A'..'Z' ,0..9);
sysopen ($fh,$datei,O_RDWR|O_CREAT) or die "$!";
seek ($fh,0,0);
truncate ($fh,0);
my $string = '';
my $l = 0;
while ($l < 500 * 1024 * 1024) {
    $string .= $atoms[rand scalar @atoms] . $string . $atoms[rand scalar @atoms];
    $l += length ($string);
    print $fh $string;
}

# Quersumme
print "Start...\n";
my $start = time ();
my $ctx = Digest::CRC -> new (type => "crc32");
seek ($fh,0,0);
$ctx -> addfile ($fh);
my $crc = $ctx -> digest;
my $ende = time ();
print "$crc\n";
print "Zeit: " . ($ende - $start) . " Sec\n";