perl function parameters what to pass

Can any one can help me out for following perl code. I m a vb guy so i dont understand the below code.
I want to help someone . I only want how can i execute the below function mean what parameters should pass in the below function to get dummy value without error

use strict;
use Math::BigInteger;
use CRC;

sub text2bn($$)
{
   my ($blockbitsize, $text) = @_;

   my $blocksize = $blockbitsize / 8; 
   my $hblocksize = $blocksize * 2;
   srand; 
   my $seed = int rand 65535;
   my $hseed = sprintf "%04X",$seed;

   my $len = length $text;
   my $lenfull = $len + 2 + 4 + 4; # 2 - seed; 4 - crc; 4 - len; 

   my $padlen = $blocksize - $lenfull % $blocksize if $lenfull % $blocksize; 

   my $hm = uc (sprintf ("%08X",$len) . 
            unpack ('H*',$text) . unpack ('H*','.' x $padlen));
   my $crc = CRC::checksum($hm);
   my $hm = sprintf ("%08X",$crc) . $hm;
   srand $seed;

   $hm =~ s/(..)/sprintf ("%02X", hex($1) ^ int rand 255)/ges;
   $hm = $hseed . $hm;

   my @hblocks = $hm =~ /(.{$hblocksize})/gs;
   my @bn_blocks = map 
   {
      restore Math::BigInteger ( pack 'H*',$_);
   } @hblocks;
   @bn_blocks;
}