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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>bitmap_pos_to_ord</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="The Linux Kernel API" /><link rel="up" href="ch03.html#id2630756" title="Bitmap Operations" /><link rel="prev" href="re117.html" title="bitmap_copy_le" /><link rel="next" href="re119.html" title="bitmap_ord_to_pos" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>bitmap_pos_to_ord</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re117.html">Prev</a> </td><th width="60%" align="center">Bitmap Operations</th><td width="20%" align="right"> <a accesskey="n" href="re119.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="bitmap_pos_to_ord"><a id="API-bitmap-pos-to-ord"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>bitmap_pos_to_ord —
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">int <b class="fsfunc">bitmap_pos_to_ord </b>(</code></td><td>const unsigned long * <var class="pdparam">buf</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">pos</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">bits</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id2634468"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>buf</code></em></span></dt><dd><p>
pointer to a bitmap
</p></dd><dt><span class="term"><em class="parameter"><code>pos</code></em></span></dt><dd><p>
a bit position in <em class="parameter"><code>buf</code></em> (0 <= <em class="parameter"><code>pos</code></em> < <em class="parameter"><code>bits</code></em>)
</p></dd><dt><span class="term"><em class="parameter"><code>bits</code></em></span></dt><dd><p>
number of valid bit positions in <em class="parameter"><code>buf</code></em>
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2634551"></a><h2>Description</h2><p>
Map the bit at position <em class="parameter"><code>pos</code></em> in <em class="parameter"><code>buf</code></em> (of length <em class="parameter"><code>bits</code></em>) to the
ordinal of which set bit it is. If it is not set or if <em class="parameter"><code>pos</code></em>
is not a valid bit position, map to -1.
</p><p>
If for example, just bits 4 through 7 are set in <em class="parameter"><code>buf</code></em>, then <em class="parameter"><code>pos</code></em>
values 4 through 7 will get mapped to 0 through 3, respectively,
and other <em class="parameter"><code>pos</code></em> values will get mapped to 0. When <em class="parameter"><code>pos</code></em> value 7
gets mapped to (returns) <em class="parameter"><code>ord</code></em> value 3 in this example, that means
that bit 7 is the 3rd (starting with 0th) set bit in <em class="parameter"><code>buf</code></em>.
</p><p>
The bit positions 0 through <em class="parameter"><code>bits</code></em> are valid positions in <em class="parameter"><code>buf</code></em>.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re117.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch03.html#id2630756">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re119.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>bitmap_copy_le</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>bitmap_ord_to_pos</span></td></tr></table></div></body></html>
