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<!ENTITY cmd "liboil-0.3">

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<refentry id="liboil-03-3">

<refmeta><refentrytitle>&cmd;</refentrytitle><manvolnum>3</manvolnum>

<refmiscinfo class="date">20 Feb 2009</refmiscinfo>

<refmiscinfo class="sectdesc">&man1;</refmiscinfo>

<refmiscinfo class="software">&release;</refmiscinfo>

<refmiscinfo class="arch">generic</refmiscinfo>

<refmiscinfo class="copyright">&suncopy;</refmiscinfo>

</refmeta>

<indexterm><primary>&cmd;</primary></indexterm><indexterm><primary>

Library of optimized functions.

</primary></indexterm>

<refnamediv id="liboil-03-3-name"><refname>&cmd;</refname>

<refpurpose>Library of optimized functions</refpurpose></refnamediv>

<refsect1 id="liboil-03-3-desc"><title>&desc-tt;</title>

<para>

<literal>&cmd;</literal> is a library of simple functions that are optimized

for various CPUs. These functions are generally loops implementing simple

algorithms, such as converting an array of N integers to floating-point numbers

or multiplying and summing an array of N numbers. Such functions are candidates

for significant optimization using various techniques, especially by using

extended instructions provided by modern CPUs (Altivec, MMX, SSE, etc.).

</para>

<para>

Liboil has a number of function classes, which are primarily seen by a

developer using the library as actual functions. One such function is:

</para>

<para>

<para>

<screen>

* void oil_tablelookup_u8 (uint8_t *dest, int dstr,

uint8_t *src, o int sstr, uint8_t *table,

int tablestride, int n);

</screen>

</para>

<para>

This function performs a table lookup for each element in the src array, and

puts the results in the dest array. In actuality, oil_tablelookup_u8 is

currently implemented as a preprocessor macro that generates the correct code

to call an indirect function.

</para>

<para>

Each function class has one or more function implementations, which are real

functions that perform the exact same action as defined by the documentation

for the function. Each class has one implementation that is the reference

implementation. This reference implementation is used to test the accuracy of

other implementations.

</para>

<para>

Presumably, the non-reference implementations can perform the action faster

than the reference implementation. Thus, the liboil initialization code (at

runtime) checks each implementation in a class to determine the fastest

implementation. Once this is done, the class's indirect function pointer points

to the optimal implementation. After this, any calls to the function class

(such as oil_tablelookup_u8() described above) will automatically be routed to

the fastest implementation.

</para>

</refsect1>

<refsect1 id="liboil-03-3-file"><title>&file-tt;</title>

<para>The following files are used by this application:</para>

<variablelist termlength="wholeline">

<varlistentry><term><filename>/usr/lib/&cmd;.so</filename> </term><listitem>

<para>&cmd; shared library</para></varlistentry>

<varlistentry><term><filename>/usr/share/gtk-doc/html/liboil</filename> </term><listitem>

<para>Location of developer documentation</para>

</listitem></varlistentry>

</variablelist></refsect1>

<refsect1 id="liboil-03-3-attr"><title>&attr-tt;</title>

<para>See <olink targetdocent="REFMAN5" localinfo="attributes-3"><citerefentry>

<refentrytitle>attributes</refentrytitle><manvolnum>5</manvolnum></citerefentry></olink>

for descriptions of the following attributes:</para>

<informaltable frame="all">

<tgroup cols="2" colsep="1" rowsep="1"><colspec colname="COLSPEC0" colwidth="1*">

<colspec colname="COLSPEC1" colwidth="1*">

<thead>

<row><entry align="center" valign="middle">ATTRIBUTE TYPE</entry><entry align="center"

valign="middle">ATTRIBUTE VALUE</entry></row>

</thead>

<tbody>

<row><entry><para>Availability</para></entry><entry><para>library/liboil</para></entry>

</row>

<row><entry colname="COLSPEC0"><para>Interface stability</para></entry><entry

colname="COLSPEC1"><para>Volatile</para></entry></row>

</tbody>

</tgroup>

</informaltable>

</refsect1>

<refsect1 id="liboil-03-3-also"><title>&also-tt;</title>

<para>

<citerefentry><refentrytitle>oil-bugreport</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>attributes</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>gnome-interfaces</refentrytitle><manvolnum>5</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>