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<?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>atomicAdd - OpenGL Shading Language (GLSL)</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="atomicAdd"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>atomicAdd — perform an atomic addition to a variable</p></div><div class="refsynopsisdiv"><h2>Declaration</h2><div class="funcsynopsis"><p><code class="funcdef">int <b class="fsfunc">atomicAdd</b>(</code>inout int <var class="pdparam">mem</var>, int <var class="pdparam">data</var><code>)</code>;</p><p><code class="funcdef">uint <b class="fsfunc">atomicAdd</b>(</code>inout uint <var class="pdparam">mem</var>, uint <var class="pdparam">data</var><code>)</code>;</p></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>mem</code></em></span></dt><dd><p>
                    The variable to use as the target of the operation.
                </p></dd><dt><span class="term"><em class="parameter"><code>data</code></em></span></dt><dd><p>
                    The data to be added to <em class="parameter"><code>mem</code></em>.
                </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
            <code class="function">atomicAdd</code> performs an atomic addition of <em class="parameter"><code>data</code></em> to the contents of
            <em class="parameter"><code>mem</code></em> and returns the original contents of <em class="parameter"><code>mem</code></em>
            from before the addition occured. The contents of the memory being updated by the atomic operation are
            guaranteed not to be modified by any other assignment or atomic memory function in any shader
            invocation between the time the original value is read and the time the new value is written.
        </p><p>
            Atomic memory functions are supported only for a limited set of variables.  A shader will fail to compile 
            if the value passed to the mem argument of  an atomic memory function does not correspond to a buffer or 
            shared variable.  It is acceptable to pass an element of an array or a single component of a vector to the 
            mem argument of an atomic memory function, as long as the underlying array or vector is a buffer or 
            shared variable.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="versions"></a><h2>Version Support</h2><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>Function</strong></span></th><th align="left"><span class="bold"><strong>Version 1.10</strong></span></th><th align="left"><span class="bold"><strong>Version 1.20</strong></span></th><th align="left"><span class="bold"><strong>Version 1.30</strong></span></th><th align="left"><span class="bold"><strong>Version 1.40</strong></span></th><th align="left"><span class="bold"><strong>Version 1.50</strong></span></th><th align="left"><span class="bold"><strong>Version 3.30</strong></span></th><th align="left"><span class="bold"><strong>Version 4.00</strong></span></th><th align="left"><span class="bold"><strong>Version 4.10</strong></span></th><th align="left"><span class="bold"><strong>Version 4.20</strong></span></th><th align="center"><span class="bold"><strong>Version 4.30</strong></span></th></tr><tr><th align="left">atomicAdd</th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>-</em></span></th><th align="center"><span class="emphasis"><em>Y</em></span></th></tr></thead></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a href="atomicAnd.xml"><span class="citerefentry"><span class="refentrytitle">atomicAnd</span></span></a>,
            <a href="atomicOr.xml"><span class="citerefentry"><span class="refentrytitle">atomicOr</span></span></a>,
            <a href="atomicXor.xml"><span class="citerefentry"><span class="refentrytitle">atomicXor</span></span></a>,
            <a href="atomicMin.xml"><span class="citerefentry"><span class="refentrytitle">atomicMin</span></span></a>,
            <a href="atomicMax.xml"><span class="citerefentry"><span class="refentrytitle">atomicMax</span></span></a>,
            <a href="atomicExchange.xml"><span class="citerefentry"><span class="refentrytitle">atomicExchange</span></span></a>,
            <a href="atomicCompSwap.xml"><span class="citerefentry"><span class="refentrytitle">atomicCompSwap</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 2011-2012 Khronos Group.
            This material may be distributed subject to the terms and conditions set forth in
            the Open Publication License, v 1.0, 8 June 1999.
            <a href="http://opencontent.org/openpub/" target="_top">http://opencontent.org/openpub/</a>.
        </p></div></div></body></html>
