#!/pro/bin/perl -slw

use 5.016;
use warnings;

use Benchmark qw{cmpthese :hireswallclock};

my $n = 0x80061861;

say "and_rshift:    $n => ", join (' : ', and_rshift    ());
say "lshift_rshift: $n => ", join (' : ', lshift_rshift ());
say "mixed:         $n => ", join (' : ', mixed         ());
say "mixed_assign:  $n => ", join (' : ', mixed_assign  ());
say "just_shift:    $n => ", join (' : ', just_shift    ());

cmpthese (-10, {
    and_rshift    => \&and_rshift,
    lshift_rshift => \&lshift_rshift,
    mixed         => \&mixed,
    mixed_assign  => \&mixed_assign,
    just_shift    => \&just_shift,
    });

sub and_rshift
{
    my ($top14, $nxt6, $mid6, $bot6);

    for (1..10000) {
        $top14 = ($n & 0xfffc0000) >> 18;
        $nxt6  = ($n & 0x0003f000) >> 12;
        $mid6  = ($n & 0x00000fc0) >> 6;
        $bot6  = ($n & 0x0000003f);
        }

    return ($top14, $nxt6, $mid6, $bot6);
    }

sub lshift_rshift
{
    my ($top14, $nxt6, $mid6, $bot6);

    for (1..10000) {
        $top14 = $n >> 18;
        $nxt6  = $n << 46 >> 58;
        $mid6  = $n << 52 >> 58;
        $bot6  = $n << 58 >> 58;
        }

    return ($top14, $nxt6, $mid6, $bot6);
    }

sub mixed
{
    my ($top14, $nxt6, $mid6, $bot6);

    for (1..10000) {
        ($top14, $nxt6, $mid6, $bot6) =
            ($n >> 18, $n >> 12 & 0x3f, $n >> 6 & 0x3f, $n & 0x3f);
        }

    return ($top14, $nxt6, $mid6, $bot6);
    }

sub mixed_assign
{
    my ($top14, $nxt6, $mid6, $bot6);

    for (1..10000) {
        $top14 = $n >> 18;
        $nxt6  = $n >> 12 & 0x3f;
        $mid6  = $n >> 6 & 0x3f;
        $bot6  = $n & 0x3f;
        }

    return ($top14, $nxt6, $mid6, $bot6);
    }

sub just_shift
{
    my ($top14, $nxt6, $mid6, $bot6);

    for (1..10000) {
        ($top14, $nxt6, $mid6, $bot6) =
            ($n >> 18, $n << 46 >> 58, $n << 52 >> 58, $n << 58 >> 58)
+;
        }

    return ($top14, $nxt6, $mid6, $bot6);
    }
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