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    <title>shuffle, shuffle2</title>
    <meta name="generator" content="DocBook XSL Stylesheets V1.78.1" />
    <meta name="keywords" content="shuffle, shuffle2" />
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    <div class="refentry">
      <a id="id-1"></a>
      <div class="titlepage"></div>
      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="shuffle"></a>
        <h1>shuffle</h1>
        <p>
            Constructs a permutation of elements from one (or two) input vectors.
        </p>
      </div>
      <div class="refsynopsisdiv">
        <h2></h2>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
            <tr valign="bottom">
              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef">
                    gentype<em class="replaceable">n</em>
                    <strong class="fsfunc">
                        shuffle
                    </strong>
                (</code>
                <td>gentype<em xmlns="http://www.w3.org/1999/xhtml" class="replaceable">m</em> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">x</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>ugentype<em xmlns="http://www.w3.org/1999/xhtml" class="replaceable">n</em> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">mask</var><code>)</code></td>
            </tr>
          </table>
        </div>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
            <tr valign="bottom">
              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef">
                    gentype<em class="replaceable">n</em>
                    <strong class="fsfunc">
                        shuffle2
                    </strong>
                (</code>
                <td>gentype<em xmlns="http://www.w3.org/1999/xhtml" class="replaceable">m</em> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">x</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>gentype<em xmlns="http://www.w3.org/1999/xhtml" class="replaceable">m</em> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">y</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>ugentype<em xmlns="http://www.w3.org/1999/xhtml" class="replaceable">n</em> <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">mask</var><code>)</code></td>
            </tr>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
          The <code class="function">shuffle</code> and <code class="function">shuffle2</code>
          built-in functions construct a permutation of elements from one or two input
          vectors respectively that are of the same type, returning a vector with the
          same element type as the input and length that is the same as the shuffle
          mask. The size of each element in the <code class="varname">mask</code> must match the
          size of each element in the result. For <code class="function">shuffle</code>, only the
          <a class="citerefentry" href="ilogb.html"><span class="citerefentry"><span class="refentrytitle">ilogb</span></span></a>(2<em class="replaceable"><code>m</code></em>-1)
          least significant bits of each <code class="varname">mask</code>
          element are considered. For <code class="function">shuffle2</code>, only the
          <a class="citerefentry" href="ilogb.html"><span class="citerefentry"><span class="refentrytitle">ilogb</span></span></a>(2<em class="replaceable"><code>m</code></em>-1)+1
          least significant bits of each <code class="varname">mask</code> element are considered. Other
          bits in the <code class="varname">mask</code> shall be ignored.
        </p>
        <p>
          The elements of the input vectors are numbered from left to right across one or
          both of the vectors.  For this purpose, the number of elements in a vector is given by
          <a class="citerefentry" href="vec_step.html"><span class="citerefentry"><span class="refentrytitle">vec_step</span></span></a>(gentype<em class="replaceable"><code>m</code></em>).
          The shuffle <code class="varname">mask</code> operand specifies, for each element of the result
          vector, which element of the one or two input vectors the result element gets.
        </p>
        <p>
          We use the generic type name <span class="type">gentype<em class="replaceable"><code>n</code></em></span>
          (or <span class="type">gentype<em class="replaceable"><code>m</code></em></span>) to indicate the
          built-in data types <span class="type">char{2|4|8|16}</span>, <span class="type">uchar{2|4|8|16}</span>,
          <span class="type">short{2|4|8|16}</span>, <span class="type">ushort{2|4|8|16}</span>, <span class="type">int{2|4|8|16}</span>,
          <span class="type">uint{2|4|8|16}</span>, <span class="type">long{2|4|8|16}</span>, <span class="type">ulong{2|4|8|16}</span>,
          or <span class="type">float{2|4|8|16}</span> as the type for the arguments unless otherwise
          stated. We use the generic name <span class="type">ugentype<em class="replaceable"><code>n</code></em></span>
          to indicate the built-in unsigned integer data types. If the <span class="type">double</span>
          is supported, then <span class="type">gentype<em class="replaceable"><code>n</code></em></span> (or
          <span class="type">gentype<em class="replaceable"><code>m</code></em></span>) also indicate the built-in data
          types <span class="type">double{2|4|8|16}</span>.
        </p>
        <p>
          The generic type name <span class="type">gentype<em class="replaceable"><code>n</code></em></span>
          (or <span class="type">gentype<em class="replaceable"><code>m</code></em></span>)
          may indicate the data type <span class="type">half{2|4|8|16}</span> if the
          <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a> extension
          is supported.
        </p>
      </div>
      <div class="refsect2">
        <a id="example1"></a>
        <h3>
            Example
        </h3>
        <div class="informaltable">
          <table border="0">
            <colgroup>
              <col align="left" class="col1" />
            </colgroup>
            <tbody>
              <tr>
                <td align="left">
uint4 mask = (uint4)(3, 2, 1, 0);
float4 a;
float4 r = shuffle(a, mask);
// r.s0123 = a.wzyx

uint8 mask = (uint8)(0, 1, 2, 3, 4, 5, 6, 7);

float4 a, b;
float8 r = shuffle2(a, b, mask);
// r.s0123 = a.xyzw
// r.s4567 = b.xyzw

uint4 mask;
float8 a;
float4 b;
b = shuffle(a, mask);

                        </td>
              </tr>
            </tbody>
          </table>
        </div>
        <p>
          Examples that are not valid are:
        </p>
        <div class="informaltable">
          <table border="0">
            <colgroup>
              <col align="left" class="col1" />
            </colgroup>
            <tbody>
              <tr>
                <td align="left">
uint8 mask;
short16 a;
short8 b;
b = shuffle(a, mask);

                        </td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />

            <a href="http://www.khronos.org/registry/cl/specs/opencl-1.2.pdf#page=282" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="miscVectorFunctions.html"><span class="citerefentry"><span class="refentrytitle">Miscellaneous Vector Functions</span></span></a>
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2011 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
permit persons to whom the Materials are furnished to do so, subject to
the condition that this copyright notice and permission notice shall be included
in all copies or substantial portions of the Materials.
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