output.txt

empty_loop         0.076
unpack_i16         2.097    2.021
ord_i16            0.925    0.849
unpack_u16         2.051    1.975
ord_u16            0.740    0.664
------------------------
Total              5.889

php -v
PHP 7.0.5 (cli) (built: Apr 23 2016 10:48:01) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies

unpack_vs_ord.php

<?php

function unpack_i16($n, $buffer) {
    for ($i = 0; $i < $n; ++$i) {
        $num = \unpack('n', $buffer[0].$buffer[1])[1];
    }
}

function ord_i16($n, $buffer) {
    for ($i = 0; $i < $n; ++$i) {
        $hi = \ord($buffer[0]);
        $lo = \ord($buffer[1]);

        if ($hi & 128) {
            $num = - (0x010000 - (($hi << 8) | $lo));
            continue;
        }

        $num = $hi << 8 | $lo;
    }
}

function unpack_u16($n, $buffer) {
    for ($i = 0; $i < $n; ++$i) {
        $num = \unpack('s', $buffer[1].$buffer[0])[1];
    }
}

function ord_u16($n, $buffer) {
    for ($i = 0; $i < $n; ++$i) {
        $hi = \ord($buffer[0]);
        $lo = \ord($buffer[1]);
        $num = $hi << 8 | $lo;
    }
}

function empty_loop($n) {
    for ($i = 0; $i < $n; ++$i) {
    }
}

function getmicrotime()
{
    $t = gettimeofday();
    return ($t['sec'] + $t['usec'] / 1000000);
}

function start_test()
{
    ob_start();
    return getmicrotime();
}

function end_test($start, $name, $overhead = null)
{
    global $total;
    global $last_time;
    $end = getmicrotime();
    ob_end_clean();
    $last_time = $end-$start;
    $total += $last_time;
    $num = number_format($last_time,3);
    $pad = str_repeat(" ", 24-strlen($name)-strlen($num));
    if (is_null($overhead)) {
        echo $name.$pad.$num."\n";
    } else {
        $num2 = number_format($last_time - $overhead,3);
        echo $name.$pad.$num."    ".$num2."\n";
    }
    ob_start();
    return getmicrotime();
}

function total()
{
    global $total;
    $pad = str_repeat("-", 24);
    echo $pad."\n";
    $num = number_format($total,3);
    $pad = str_repeat(" ", 24-strlen("Total")-strlen($num));
    echo "Total".$pad.$num."\n";
}

const N = 9000000;
const BUFFER = "\xff\x7f";

$t0 = $t = start_test();
empty_loop(N);
$t = end_test($t, 'empty_loop');
$overhead = $last_time;

unpack_i16(N, BUFFER);
$t = end_test($t, 'unpack_i16', $overhead);

ord_i16(N, BUFFER);
$t = end_test($t, 'ord_i16', $overhead);

unpack_u16(N, BUFFER);
$t = end_test($t, 'unpack_u16', $overhead);

ord_u16(N, BUFFER);
$t = end_test($t, 'ord_u16', $overhead);

total();