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

    #Lets convert that ESN
    print "\n\n", "*" x22, "\n";
    print "ESN Converter v.01", "\n";
    print "*" x22, "\n";
    print "Please enter ESN:";
    chomp( my $hexnum = <STDIN> );

    push (my @hexnum, $hexnum);
    @hexnum = split ( ' ', $hexnum );

if ( $hexnum eq "" ) {
 
    print "Invalid Input!\n";
    print "Press <ENTER> to continue";<>; 
     
}
 
else {
 
  go(@hexnum);

}

sub go {

  if ( length( $hexnum[0] ) == 8 ) {
      my $mfg   = hex( substr( $hexnum, 0, 2 ) );
      my $serno = hex( substr( $hexnum, 2, 6 ) );
      printf( "\nDecimal:  %d %d\nHex:  %s\n\n", $mfg, $serno, $hexnum );
      print "Press <ENTER> to continue";<>;
  }
  elsif ( length( $hexnum[0] ) == 3 ) {
 
      printf( "\nDecimal:  %3d %8d\n", $hexnum[0], $hexnum[1] );
      printf( "Hex:  %2X%6X\n\n",      $hexnum[0], $hexnum[1] );
      print "Press <ENTER> to continue";<>;
  }

 else {
 
      die "Invalid Input!\n";
      print "Press <ENTER> to continue";<>;
  }
 
}