#!/use/bin/perl

use strict;
use warnings;

sub udiv64 {
    my ($a, $b) = @_;
    return 0 if $b > $a;
    my $c = $a >> 1;
    my $d = do { use integer; $c / $b };
    my $e = $a - (do { use integer; $d * $b } << 1);
    ($d << 1) + do { use integer; $e / $b }
}

use Devel::Peek;
Dump udiv64(10_000_000_000_000_000_011, 10);
Dump udiv64(10_000_000_000_000_000_011, 1)