#!/usr/bin/perl -w
use strict;

my $x = 
'0x0105000000000005150000009E15AE084A7CBC7A881C6A37C63F0000';

open    GG, ">c:/PerlMonks_346728.out" or die;
binmode GG or die;
print   GG second_to_first($x);
close   GG or die;

sub first_to_second {
  return join('', '0x', unpack 'H*', $_[0]);
}
sub second_to_first {
  local $_ = shift;
  s{^0x}{}i or die;
  return pack 'H*', $_;
}