title: Understanding this embedded c code
body: <p>I'm trying to understand this embedded c code. I think it means it is connecting port bits to some register in a bus. Correct me if I'm wrong. And what ever changes we make to the ports will be reflected on the bus registers. Here is the snippet of the code. Thanks.</p>
  
  <pre><code>/*--------------------------------------------------------------------------
  Local Variables
  --------------------------------------------------------------------------*/
  // Port bits assigned to Amba Peripheral Bus (APB)
  // P0^7..P0^0               // output=reg_addr, input=data_in (APB prdata)
  sbit APB_SEL = P1^7;        // select a bus transaction
  sbit APB_EN  = P1^6;        // enable/activate a component 0 = disable, 1 = enable
  </code></pre>