my $bom;
open IN, $filename or die $!;
read IN, $bom, 2;

my $bomval = unpack 'S', $bom;

if ( $bomval == 0xfeff ) {
   # this is bound to be a utf16 file --
   # you've already read the bom, so just move on and read the data
}
close IN;

##</code><code>##

my $size = -s $filename;
$size = 128 if $size > 128;

my $test;
open IN, $filename or die $!;
read IN, $test, $size;
seek IN, 0, 0;

my @bytes = unpack 'C*', $test;
my $nullhibytes = 0;
for ( my $i=o $i<$size; $i+=2 ) {
    $nullhibytes++ if ( $bytes[$i+1] == 0 and $bytes[$i] =~ /[ -~]/);
}

if ( $nullhibytes > 8 ) { 
    # this is probably a utf16 file (if it's text at all)
}
close IN;