my @fifo;
my $MAX_FIFO = 53; #max size is optional

sub add_entry
{
   die "Cicular buffer overflow\n" if (@fifo >= $MAX_FIFO);
   my $entry = shift;  #well, $_[0] is ok for syntax too
                       #but I think this is more clear
                       #these simple assignment statements are 
                       #  not "expensive"
   push @fifo, $entry; 
}

sub get_entry
{
   return (shift @fifo);
}