title: Use macro with token-pasting operator
body: <p>I am facing a problem while making a code more general, I want to replace hardcoded values with macro but I am facing this issue :</p>
  <p>Original code :</p>
  <pre><code>#define io_dir_in(port, pin) NRF_P##port-&gt;PIN_CNF[pin] = (GPIO_PIN_CNF_DIR_Input &lt;&lt; GPIO_PIN_CNF_DIR_Pos) + (GPIO_PIN_CNF_INPUT_Connect &lt;&lt; GPIO_PIN_CNF_INPUT_Pos)
  
  io_dir_in(0, 0);
  </code></pre>
  <p>I added :</p>
  <pre><code>#define A_Port  0
  #define A_Pin   0
  </code></pre>
  <p>And replaced :</p>
  <pre><code>io_dir_in(A_Port, A_Pin);
  </code></pre>
  <p>But I get the error <code>identifer &quot;NRF_PA_Port&quot; is undefined</code> because <code>NRF_P</code> and <code>A_Port</code> are getting concatenated.<br> Anyway to make it work ?</p>