title: questions on 0xff
body: <p>I am working on a C++ code. Not very sure what the code below is trying to do. Would like someone's help on it.</p>
  
  <pre><code>int pval = t_gamma[depth[i]];
          int lb = pval &amp; 0xff;
          switch (pval&gt;&gt;8) {
              case 0:
                  depth_mid[3*i+0] = 255;
                  depth_mid[3*i+1] = 255-lb;
                  depth_mid[3*i+2] = 255-lb;
                  break;
              case 1:
                  depth_mid[3*i+0] = 255;
                  depth_mid[3*i+1] = lb;
                  depth_mid[3*i+2] = 0;
                  break;
              case 2:
                  depth_mid[3*i+0] = 255-lb;
                  depth_mid[3*i+1] = 255;
                  depth_mid[3*i+2] = 0;
                  break;
              case 3:
                  depth_mid[3*i+0] = 0;
                  depth_mid[3*i+1] = 255;
                  depth_mid[3*i+2] = lb;
                  break;
              case 4:
                  depth_mid[3*i+0] = 0;
                  depth_mid[3*i+1] = 255-lb;
                  depth_mid[3*i+2] = 255;
                  break;
              case 5:
                  depth_mid[3*i+0] = 0;
                  depth_mid[3*i+1] = 0;
                  depth_mid[3*i+2] = 255-lb;
                  break;
              default:
                  depth_mid[3*i+0] = 0;
                  depth_mid[3*i+1] = 0;
                  depth_mid[3*i+2] = 0;
                  break;
          }
  </code></pre>