ial error condition.</p>
</div>
<div class="ulist">
<ul>
<li>
<p><code>struct async</code></p>
</li>
</ul>
</div>
<div class="paragraph">
<p>This describes a function to run asynchronously, whose purpose is
to produce output that the caller reads.</p>
</div>
<div class="paragraph">
<p>The caller:</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>allocates and clears (memset(&amp;asy, 0, sizeof(asy));) a
struct async variable;</p>
</li>
<li>
<p>initializes .proc and .data;</p>
</li>
<li>
<p>c