Mighty perl monks, do you have anty suggestions on how to make the following subroutine, and the following part of my code, case insensitive. I know that it sounds trivial but I had problems doing it.

sub get_Hx{
  my $site = $_[0];
  my $no_of_sequences =length($site);
  my $sum = 0;
  foreach(qw/A C D E F G H I J K L M N P Q R S T V W Y _ \./){
    my $count = () = $site =~ /$_/g;
    $sum += -($count/$no_of_sequences)*log_2($count/$no_of_sequences) 
+if($count > 0);
  }
  return $sum;
}
[download]

also I nedd the same thing for the next block of code.

my $site1;
my $site2;


my $l=0;
foreach $site1 (@site1) {
   my @site1_parts = split(//, $site1);
    $l++;
    my $j=0;
    my $mutual;
    my $Hx= get_Hx($site1);
    #print "$Hx\n";
    
   foreach $site2 (@site2) {#begining of loop2 for each site 2
           $j++;
      my $Hy = get_Hx($site2);
        
        my $Hxy;
        my %counts;
        my @count_collection;
       
        my @site2_parts = split(//, $site2);

        my $i = @site1_parts;
        $counts{get_index($site1_parts[$i], $site2_parts[$i])}++ while
+ ($i--);
          push(@count_collection, \%counts);
          foreach my $counts (@count_collection) {
            my $total;
            foreach (sort keys %$counts) {
  #print "$counts{$_}\n";
        my $freq = $counts->{$_}/length($site1);
        my $MI = -$freq * log_2$freq; #$total +=$freq;
        $Hxy +=$MI;
        
  }
            #print "$Hxy \ $Hx\ $Hy \n"; 
            $mutual = $Hx + $Hy - $Hxy;
}
        
        
        
        print " $l,$j,$mutual\n";
       #print " $l,$j\n";
        #print($_, ': ', $counts{$_}, $/) foreach (sort keys %counts);
        #print($/);
   }#end of loop2 for each site2
 
   
}
[download]

By case insensitive I mean that whenever my program finds an A or an a it should do countA +2 and not two different counters. Thanks for anyone's help