egment on the head of the unsent queue. If return is not ERR_OK, existing head remains intact</p>
<p>The split is accomplished by creating a new TCP segment and pbuf which holds the remainder payload after the split. The original pbuf is trimmed to new length. This allows splitting of read-only pbufs</p>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">pcb</td><td>the <a class="el" href="structtcp__pcb.html">tcp_pcb</a> for which to split the unsent head </td