sdk/2.1/docs/man/xhtml/select.html

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    <title>select</title>
    <meta name="generator" content="DocBook XSL Stylesheets V1.79.1" />
    <meta name="keywords" content="select" />
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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="select"></a>
        <h1>select</h1>
        <p>
            For each component of a vector type, result[<code xmlns="http://www.w3.org/1999/xhtml" class="varname">i</code>] = if MSB of <code xmlns="http://www.w3.org/1999/xhtml" class="varname">c</code>[<code xmlns="http://www.w3.org/1999/xhtml" class="varname">i</code>] is set ? <code xmlns="http://www.w3.org/1999/xhtml" class="varname">b</code>[<code xmlns="http://www.w3.org/1999/xhtml" class="varname">i</code>] : <code xmlns="http://www.w3.org/1999/xhtml" class="varname">a</code>[<code xmlns="http://www.w3.org/1999/xhtml" class="varname">i</code>]. For scalar type, <span xmlns="http://www.w3.org/1999/xhtml" class="emphasis"><em>result</em></span> = <code xmlns="http://www.w3.org/1999/xhtml" class="varname">c</code> ? <code xmlns="http://www.w3.org/1999/xhtml" class="varname">b</code> : <code xmlns="http://www.w3.org/1999/xhtml" class="varname">a</code>.
        </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
                    <strong class="fsfunc">
                        select
                    </strong>
                (</code>
                <td>gentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">a</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>gentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">b</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>igentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">c</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
                    <strong class="fsfunc">
                        select
                    </strong>
                (</code>
                <td>gentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">a</var>, </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>gentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">b</var>, </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>ugentype <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">c</var><code>)</code></td>
            </tr>
          </table>
        </div>
      </div>
      <div class="refsect2">
        <a id="double"></a>
        <h3></h3>
        <div class="informaltable">
          <table class="informaltable" border="0">
            <colgroup>
              <col align="left" class="col1" />
            </colgroup>
            <tbody>
              <tr>
                <td align="left">
<span class="type"><a class="link" href="vectorDataTypes.html" target="pagedisplay">half<em class="replaceable"><code>n</code></em></a></span> <code class="function">select</code> (<span class="type"><a class="link" href="vectorDataTypes.html" target="_top">half<em class="replaceable"><code>n</code></em></a></span> <code class="varname">a</code>, <span class="type"><a class="link" href="vectorDataTypes.html" target="_top">half<em class="replaceable"><code>n</code></em></a></span> <code class="varname">b</code>,
            <span class="type"><a class="link" href="vectorDataTypes.html" target="pagedisplay">short<em class="replaceable"><code>n</code></em></a></span> <code class="varname">c</code>)      // if half extension enabled

<span class="type"><a class="link" href="vectorDataTypes.html" target="pagedisplay">half<em class="replaceable"><code>n</code></em></a></span> <code class="function">select</code> (<span class="type"><a class="link" href="vectorDataTypes.html" target="_top">half<em class="replaceable"><code>n</code></em></a></span> <code class="varname">a</code>, <span class="type"><a class="link" href="vectorDataTypes.html" target="_top">half<em class="replaceable"><code>n</code></em></a></span> <code class="varname">b</code>,
            <span class="type"><a class="link" href="vectorDataTypes.html" target="pagedisplay">ushort<em class="replaceable"><code>n</code></em></a></span> <code class="varname">c</code>)      // if half extension enabled
</td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
          For each component of a vector type, result[<code class="varname">i</code>]
          = if MSB of <code class="varname">c</code>[<code class="varname">i</code>]
          is set ? <code class="varname">b</code>[<code class="varname">i</code>] :
          <code class="varname">a</code>[<code class="varname">i</code>].
        </p>
        <p>
          For scalar type, <span class="emphasis"><em>result</em></span> = <code class="varname">c</code>
          ? <code class="varname">b</code> : <code class="varname">a</code>.
        </p>
        <p>
          <span class="type">igentype</span> and <span class="type">ugentype</span> must have the same number of elements
          and bits as <span class="type">gentype</span>.
        </p>
        <p>
            NOTE: The above definition means that the
            behavior of select and the ternary operator for
            vector and scalar types is dependent on different
            interpretations of the bit pattern of <code class="varname">c</code>.
        </p>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
        General information about relational functions:
    </p>
        <p>
      The argment type <span class="type">gentype</span> can be <span class="type">char</span>,
      <span class="type">char<em class="replaceable"><code>n</code></em></span>, <span class="type">uchar</span>,
      <span class="type">uchar<em class="replaceable"><code>n</code></em></span>, <span class="type">short</span>,
      <span class="type">short<em class="replaceable"><code>n</code></em></span>, <span class="type">ushort</span>,
      <span class="type">ushort<em class="replaceable"><code>n</code></em></span>, <span class="type">int</span>,
      <span class="type">int<em class="replaceable"><code>n</code></em></span>, <span class="type">uint</span>,
      <span class="type">uint<em class="replaceable"><code>n</code></em></span>, <span class="type">long</span>,
      <span class="type">long<em class="replaceable"><code>n</code></em></span>, <span class="type">ulong</span>,
      <span class="type">ulong<em class="replaceable"><code>n</code></em></span>, <span class="type">float</span>,
      <span class="type">float<em class="replaceable"><code>n</code></em></span>, <span class="type">double</span>, and
      <span class="type">double<em class="replaceable"><code>n</code></em></span>.
    </p>
        <p>
      The argument type <span class="type">igentype</span> refers to the built-in signed integer types,
      i.e. <span class="type">char</span>, <span class="type">char<em class="replaceable"><code>n</code></em></span>,
      <span class="type">short</span>, <span class="type">short<em class="replaceable"><code>n</code></em></span>, <span class="type">int</span>,
      <span class="type">int<em class="replaceable"><code>n</code></em></span>, <span class="type">long</span>, and
      <span class="type">long<em class="replaceable"><code>n</code></em></span>. 
      <em class="replaceable"><code>n</code></em> is 2, 3, 4, 8, or 16.
    </p>
        <p>
      The argument type <span class="type">ugentype</span> refers to the built-in unsigned integer types,
      i.e. <span class="type">uchar</span>, <span class="type">uchar<em class="replaceable"><code>n</code></em></span>,
      <span class="type">ushort</span>, <span class="type">ushort<em class="replaceable"><code>n</code></em></span>,
      <span class="type">uint</span>, <span class="type">uint<em class="replaceable"><code>n</code></em></span>, <span class="type">ulong</span>,
      and <span class="type">ulong<em class="replaceable"><code>n</code></em></span>. <em class="replaceable"><code>n</code></em> is 2,
      3, 4, 8, or 16.
    </p>
        <p>
      If an implementation extends this specification to support IEEE-754 flags or
      exceptions, then all built-in relational functions shall proceed without raising the
      <code class="varname">invalid</code> floating-point exception when one or more of the operands
      are NaNs.
    </p>
        <p>
      The built-in relational functions are extended with
      <a class="citerefentry" href="cl_khr_fp16.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_fp16</span></span></a> to
      include versions that take <span class="type">half</span>, and
      <span class="type">half{2|3|4|8|16}</span> as arguments.
    </p>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />

            <a href="https://www.khronos.org/registry/cl/specs/opencl-2.1-openclc.pdf#page=90" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="relationalFunctions.html"><span class="citerefentry"><span class="refentrytitle">Relational 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 © 2007-2015 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
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"Materials"), to deal in the Materials without restriction, including
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