<?xml version="1.0" encoding="ANSI_X3.4-1968" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>Accessing Port Space</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Bus-Independent Device Accesses" /><link rel="up" href="ch04.html" title="Chapter 4. Port Space Accesses" /><link rel="prev" href="ch04.html" title="Chapter 4. Port Space Accesses" /><link rel="next" href="ch05.html" title="Chapter 5. Public Functions Provided" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Accessing Port Space</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch04.html">Prev</a> </td><th width="60%" align="center">Chapter 4. Port Space Accesses</th><td width="20%" align="right"> <a accesskey="n" href="ch05.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="Accessing Port Space"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="accessing_port_space"></a>Accessing Port Space</h2></div></div></div><p> Accesses to this space are provided through a set of functions which allow 8-bit, 16-bit and 32-bit accesses; also known as byte, word and long. These functions are <code class="function">inb</code>, <code class="function">inw</code>, <code class="function">inl</code>, <code class="function">outb</code>, <code class="function">outw</code> and <code class="function">outl</code>. </p><p> Some variants are provided for these functions. Some devices require that accesses to their ports are slowed down. This functionality is provided by appending a <code class="function">_p</code> to the end of the function. There are also equivalents to memcpy. The <code class="function">ins</code> and <code class="function">outs</code> functions copy bytes, words or longs to the given port. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch04.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch04.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch05.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 4. Port Space Accesses </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 5. Public Functions Provided</td></tr></table></div></body></html>