Calculate a feature percentage with numeric (incremented) user id

percentage.php

<?php

$feature = 'test';
$limit = 100;
$percentage = 0.5; // ie. 0,5

function calculatePercentage($id) {
        $hex = hash('sha256', $id);
        $len = min(40, strlen($hex));
        $vMax = 1 << $len;
        $v = 0;
        for ($i = 0; $i < $len; $i++) {
            $bit = hexdec($hex[$i]) < 8 ? 0 : 1;
            $v = ($v << 1) + $bit;
        }
        $w = $v / $vMax;
        return $w;
    }
    
$numOn = 0;
$numOff = 0;
for ($i = 0; $i < $limit; $i++) {
    if (calculatePercentage(sprintf('%s.%d', $feature, $i)) < $percentage) {
        $numOn++;
    } else {
        $numOff++;
    }
}
    
echo sprintf('On: [%d] | Off: [%d]', $numOn, $numOff);

crc32(sprintf('%s.%d', $feature, $i)) % 100 < $percentage works also when $percentage = 50