1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>fls64</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="The Linux Kernel API"><link rel="up" href="ch02s03.html" title="Bit Operations"><link rel="prev" href="API-fls.html" title="fls"><link rel="next" href="kernel-lib.html" title="Chapter&#160;3.&#160;Basic Kernel Library Functions"></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">fls64</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-fls.html">Prev</a>&#160;</td><th width="60%" align="center">Bit Operations</th><td width="20%" align="right">&#160;<a accesskey="n" href="kernel-lib.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-fls64"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>fls64 &#8212; 
2     find last set bit in a 64-bit word
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">int <b class="fsfunc">fls64 </b>(</code></td><td>__u64 <var class="pdparam">x</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1123209748"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>x</code></em></span></dt><dd><p>
4     the word to search
5    </p></dd></dl></div></div><div class="refsect1"><a name="idp1123211316"></a><h2>Description</h2><p>
6   This is defined in a similar way as the libc and compiler builtin
7   ffsll, but returns the position of the most significant set bit.
8   </p><p>
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10   fls64(value) returns 0 if value is 0 or the position of the last
11   set bit if value is nonzero. The last (most significant) bit is
12   at position 64.
13</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-fls.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="ch02s03.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="kernel-lib.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">fls</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;Chapter&#160;3.&#160;Basic Kernel Library Functions</td></tr></table></div></body></html>
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