#!/usr/bin/perl

use strict;

my $encoding = 'UTF-16';

my $Usage = "Usage: $0 [-BE|-LE] file.u16\n";
if ( @ARGV and $ARGV[0] =~ /^-([BL]E)$/ ) {
    $encoding .= $1;
    shift;
}
die $Usage unless ( @ARGV == 1 and -f $ARGV[0] );

my $filename = pop @ARGV;

# if user didn't specify byte order, let's check the input file

if ( $encoding eq 'UTF-16' ) {
    my $first_short;
    open( F, "<", $filename ) or die "$filename: $!";

    my $n = sysread( F, $first_short, 2 );
    die "sysread failed on $filename" unless ( $n == 2 );

    if ( $first_short == pack( 'S', 0xfeff ) or
         $first_short == pack( 'S', 0xfffe ) {
        # it's a BOM, and using ":encoding(UTF-16)" is fine
    }
    else {
        die "$filename has no BOM; please specify byte order\n$Usage";
    }
}
close F;

open( F, "<:$encoding", $filename );

# ... and go to work...