title: Hex number operations in c#
body: <p>I am making an application in C# and I have hex numbers such as <code>0x0FF8,0xFFFA</code> etc. </p>
  
  <p>Here I want only <code>12 bit</code> from right to left. Suppose I have a number as <code>0x0FF8</code>.
  So I just want to make operation on <code>FF8.(12 bits)</code>, and this is signed number. </p>
  
  <p>It is the decimal number is <code>-8</code>. In my application I have to first find whether number is negative or not? And after that its value. </p>
  
  <p>I am not getting how to do it in C# efficiently as I have to do it very fast.
  The number representation is as <code>0x0FF8= -8</code> please see the link <a href="http://www.swarthmore.edu/NatSci/echeeve1/Ref/BinaryMath/NumSys.html" rel="nofollow">http://www.swarthmore.edu/NatSci/echeeve1/Ref/BinaryMath/NumSys.html</a></p>