title: hexadecimal array in C
body: <p>I am trying to learn expansion header configuration of a processor on this instruction <a href="http://41j.com/blog/2011/09/beagleboard-gpio-input-driverless/" rel="nofollow">http://41j.com/blog/2011/09/beagleboard-gpio-input-driverless/</a></p>
  
  <p>I have a part that I could not understand</p>
  
  <pre><code>volatile ulong *pinconf;
  pinconf = (ulong*) mmap(NULL, 0x10000, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0x48000000);
  pinconf[0x2168/4] = 0x001C001C;
  </code></pre>
  
  <p>Can anyone explain how does the <code>pinconf</code> array works? what value does it store?</p>
  
  <p>Edit: What I really could not understand what does <code>pinconf[0x2168/4]</code> mean. is it an hexadecimal array and what value does it refer to?</p>