code: private void readNetscapeExt() {
          do {
              readBlock();
              if (block[0] == 1) {
                  // Loop count sub-block.
                  int b1 = ((int) block[1]) & 0xff;
                  int b2 = ((int) block[2]) & 0xff;
                  header.loopCount = (b2 << 8) | b1;
                  if(header.loopCount == 0) {
                      header.loopCount = GifDecoder.LOOP_FOREVER;
                  }
              }
          } while ((blockSize > 0) && !err());
      }
docs: Reads Netscape extension to obtain iteration count.