Prime drag race

prime.php

<?php
$passes = 0;                            //Init passes
$sieveSize = 1000000;                   //Set sieve size
$runTime = 10;                          //The amount of seconds the script should be running for
$stopTime = microtime(true) + $runTime;

$q = sqrt($sieveSize);
while (microtime(true) < $stopTime) {
    $factor = 3;
    $rawbits = [];
    while ($factor < $q) {
        for ($i = $factor; $i <= $sieveSize; $i += 2) {
            if (!isset($rawbits[$i])) {
                $factor = $i;
                break;
            }
        }

        $ft2 = $factor * 2;
        for ($i = $factor * $factor; $i <= $sieveSize; $i += $ft2) {
            $rawbits[$i] = 1;
        }

        $factor += 2;
    }
    $passes++;
}
$endTime = microtime(true);
$startTime  = $stopTime - $runTime;

$rawbitCount = ($sieveSize / 2) - array_sum($rawbits);

$primeCounts = [
    10 => 4,
    100 => 25,
    1000 => 168,
    10000 => 1229,
    100000 => 9592,
    1000000 => 78498,
    10000000 => 664579,
    100000000 => 5761455,
];

//Print the results
printf(
    "Passes: %d, Time: %dms, Avg: %dms, Limit: %d, Count: %d, Valid: %s",
    $passes,
    (int)(($endTime - $startTime) * 1000),
    (($endTime - $startTime) * 1000) / $passes,
    $sieveSize,
    $rawbitCount,
    $primeCounts[$sieveSize] === $rawbitCount ? 'True' : 'False'
);

// Following 2 lines added by rbergen to conform to drag race output format
echo "\n\n";
printf("DennisdeBest;%d;%f;1;algorithm=base,faithful=no\n", $passes, $endTime - $startTime);