1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>parport_read</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Linux Device Drivers"><link rel="up" href="parportdev.html" title="Chapter&#160;3.&#160;Parallel Port Devices"><link rel="prev" href="API-parport-write.html" title="parport_write"><link rel="next" href="API-parport-set-timeout.html" title="parport_set_timeout"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">parport_read</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-parport-write.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;3.&#160;Parallel Port Devices</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-parport-set-timeout.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-parport-read"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>parport_read &#8212; 
2     read a block of data from a parallel port
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">ssize_t <b class="fsfunc">parport_read </b>(</code></td><td>struct parport * <var class="pdparam">port</var>, </td></tr><tr><td>&#160;</td><td>void * <var class="pdparam">buffer</var>, </td></tr><tr><td>&#160;</td><td>size_t <var class="pdparam">len</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1110950748"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>port</code></em></span></dt><dd><p>
4     port to read from
5    </p></dd><dt><span class="term"><em class="parameter"><code>buffer</code></em></span></dt><dd><p>
6     data buffer (in kernel space)
7    </p></dd><dt><span class="term"><em class="parameter"><code>len</code></em></span></dt><dd><p>
8     number of bytes of data to transfer
9    </p></dd></dl></div></div><div class="refsect1"><a name="idp1110954420"></a><h2>Description</h2><p>
10   This will read up to <em class="parameter"><code>len</code></em> bytes of <em class="parameter"><code>buffer</code></em> to the port
11   specified, using the IEEE 1284 transfer mode most recently
12   negotiated to (using <code class="function">parport_negotiate</code>), as long as that
13   mode supports reverse transfers (peripheral to host).
14   </p><p>
15
16   It is the caller's responsibility to ensure that the first
17   <em class="parameter"><code>len</code></em> bytes of <em class="parameter"><code>buffer</code></em> are available to write to.
18   </p><p>
19
20   This function returns the number of bytes transferred (if zero
21   or positive), or else an error code.
22</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-parport-write.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="parportdev.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-parport-set-timeout.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">parport_write</span>&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">parport_set_timeout</span></td></tr></table></div></body></html>
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