title: How to merge 3 or more ids into 1 64bit id in php
body: <p>Using bit shift, it is easy to do for 2 ids as follows:</p>
  
  <pre><code>$id1 = 125;
  $id2 = 23;
  $mergedid = ($id1 &lt;&lt; 8) + $id2
  </code></pre>
  
  <p>then to obtain each id:</p>
  
  <pre><code>$id1 = $mergedid &gt;&gt; 8;
  $id2 = $mergedid &amp; 0xFF;
  </code></pre>
  
  <p>Anyonw knows how to do for 3 or more ids?</p>