title: One instruction to clear PF (Parity Flag) -- get odd number of bits in result register
body: <p>In x86 assembly, is it possible to clear the Parity Flag in one and only one instruction, working under <em>any</em> initial register configuration?</p>
  
  <p>This is equivalent to creating a result register with an <em>odd</em> number of bits, with any operation that sets flags (expressly excluding <code>mov</code>).  </p>
  
  <p>For contrast, setting the parity flag can be done in one instruction:</p>
  
  <pre><code>cmp bl, bl
  </code></pre>
  
  <p>And there are many ways to clear the parity flag with two instructions:</p>
  
  <pre><code>and bl, 0 
  or  bl, 1
  </code></pre>
  
  <p>However, the one-instruction method remains elusive.</p>