#!/usr/bin/perl

use strict;
use warnings 'all';

my $bits;
{
    my $native = -1;
    $bits++ while $native >>= 1;
} 

sub rshift { # Should be signed/sign-propagating right shift
	my ($x, $y) = @_;
	my $mask = 0; 
	my $z = $x >> $y;
	$mask = ( -1 >> ($bits - $y) ) << ($bits - $y) if $x < 0;
	return $z | $mask;
}