title: Assembly: when would test %esi,%esi return not equal?
body: <p>Starting in the Assembly areas and hard to find a decent tutorial of sort. 
  Would like to find an "Assembly for Dummies" book. </p>
  
  <p>I have come across the following and the 'test' command is always run using the same address or registry. </p>
  
  <pre><code>0x08048e14 &lt;+21&gt;:   test   %esi,%esi
  0x08048e16 &lt;+23&gt;:   jne    0x8048e4b &lt;main+76&gt;
  </code></pre>
  
  <p>Since the same registry or address is being AND when would it not return that these are the same?</p>