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| <title>Explicit conversions with convert_T()</title> |
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| <meta name="keywords" content=" Explicit conversions with convert_T() " /> |
| </head> |
| <body> |
| <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="convert_T"></a> |
| <h1>Explicit conversions with convert_T()</h1> |
| <p> |
| Explicit type conversions using convert_<code xmlns="http://www.w3.org/1999/xhtml" class="varname">T</code>() |
| </p> |
| </div> |
| <div class="refsect2"> |
| <a id="synopsis"></a> |
| <h3> |
| </h3> |
| <div class="informaltable"> |
| <table border="0"> |
| <colgroup> |
| <col align="left" class="col1" /> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td align="left"> |
| convert_<em class="replaceable"><code>destType</code></em>(<em class="replaceable"><code>srctype val</code></em>) |
| <em class="replaceable"><code>destType</code></em> convert_<em class="replaceable"><code>destType</code></em>[_sat][<em class="replaceable"><code>roundingMode</code></em>] (<em class="replaceable"><code>srcType val</code></em>) |
| <em class="replaceable"><code>destTypen</code></em> convert_<em class="replaceable"><code>destTypen</code></em>[_sat][<em class="replaceable"><code>roundingMode</code></em>] (<em class="replaceable"><code>srcTypen val</code></em>) |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| </div> |
| <div class="refsect1"> |
| <a id="description"></a> |
| <h2>Description</h2> |
| <p> |
| Explicit conversions may be performed using the <code class="code">convert_<dest type name>(srctype)</code> suite of functions. These provide a full set of type conversions between supported types (see |
| <a class="citerefentry" href="scalarDataTypes.html"><span class="citerefentry"><span class="refentrytitle">Scalar Data Types</span></span></a>) |
| except for the following types: |
| <span class="type">bool</span>, <span class="type">half</span>, <span class="type">size_t</span>, <span class="type">ptrdiff_t</span>, <span class="type">intptr_t</span>, <span class="type">uintptr_t</span>, and <span class="type">void</span>. The number of elements in the source and destination vectors must match. |
| </p> |
| <p> |
| Explicit conversions from a type to the same type has no effect on the type or value of an |
| expression. |
| </p> |
| <p> |
| The behavior of the conversion may be modified by one or two optional modifiers that specify |
| saturation for out-of-range inputs and rounding behavior. |
| </p> |
| <p> |
| The full form of the scalar convert function is: |
| </p> |
| <div class="literallayout"> |
| <p> <code class="code"><em class="replaceable"><code>destType</code></em> convert_<em class="replaceable"><code>destType</code></em>[_sat][<em class="replaceable"><code>roundingMode</code></em>](<em class="replaceable"><code>srcType val</code></em>)</code></p> |
| </div> |
| <p> |
| </p> |
| <p> |
| The full form of the vector convert function is: |
| </p> |
| <div class="literallayout"> |
| <p> <code class="code"><em class="replaceable"><code>destTypen</code></em> convert_<em class="replaceable"><code>destTypen</code></em>[_sat][<em class="replaceable"><code>roundingMode</code></em>](<em class="replaceable"><code>srcTypen val</code></em>)</code></p> |
| </div> |
| <p> |
| |
| </p> |
| <h4><a id="id-1.5.7"></a>Data Types</h4> |
| <p> |
| The operand and result type may be the same type and must have the same number of elements. Conversions are available for the following scalar types and built-in vector types derived therefrom: <span class="type">char</span>, <span class="type">uchar</span>, <span class="type">short</span>, <span class="type">ushort</span>, <span class="type">int</span>, <span class="type">uint</span>, <span class="type">long</span>, <span class="type">ulong</span>, and <span class="type">float</span>. |
| </p> |
| <h4><a id="id-1.5.9"></a>Rounding Modes</h4> |
| <p> |
| Conversions to and from floating-point type shall conform to IEEE-754 rounding rules. |
| Conversions involving a floating-point or integer source operand or destination type may have an |
| optional rounding mode modifier. These are described in the table below: |
| </p> |
| <p> |
| </p> |
| <div class="informaltable"> |
| <table border="1"> |
| <colgroup> |
| <col align="left" class="col1" /> |
| <col align="left" class="col2" /> |
| </colgroup> |
| <thead> |
| <tr> |
| <th align="left">Modifier</th> |
| <th align="left">Rounding Mode Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td align="left"> |
| <p> |
| <code class="code">_rte</code> |
| </p> |
| </td> |
| <td align="left"> |
| <p> |
| Round to nearest even |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <p> |
| <code class="code">_rtz</code> |
| </p> |
| </td> |
| <td align="left"> |
| <p> |
| Round towards zero |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <p> |
| <code class="code">_rtp</code> |
| </p> |
| </td> |
| <td align="left"> |
| <p> |
| Round toward positive infinity |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <p> |
| <code class="code">_rtn</code> |
| </p> |
| </td> |
| <td align="left"> |
| <p> |
| Round toward negative infinity |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td align="left"> |
| <p> |
| no modifier specified |
| </p> |
| </td> |
| <td align="left"> |
| <p> |
| Use the default rounding mode for this destination type, <code class="code">_rtz</code> for conversion to integers or the current rounding mode for conversion to floating-point types. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| <p> |
| </p> |
| <p> |
| By default, conversions to integer type use the <code class="code">_rtz</code> (round toward zero) rounding mode and conversions to floating-point type use the current rounding mode. The only default floating-point rounding mode supported is round to nearest even, i.e the current rounding mode will be <code class="code">_rte</code> for floating-point types. |
| </p> |
| <p> |
| </p> |
| <h4><a id="id-1.5.13.1"></a>Out-of-Range Behavior and Saturated Conversions</h4> |
| <p> |
| </p> |
| <p> |
| When the conversion operand is either greater than the greatest representable destination value or |
| less than the least representable destination value, it is said to be out-of-range. When converting |
| between integer types, the resulting value for out-of-range inputs will be equal to the set of least |
| significant bits in the source operand element that fit in the corresponding destination element. |
| When converting from a floating-point type to integer type, the behavior is implementation- |
| defined. |
| </p> |
| <p> |
| Conversions to integer type may opt to convert using the optional saturated mode by appending |
| the <code class="code">_sat</code> modifier to the conversion function name. When in saturated mode, values that are |
| outside the representable range shall clamp to the nearest representable value in the destination |
| format. (NaN should be converted to 0). |
| </p> |
| <p> |
| Conversions to floating-point type shall conform to IEEE-754 rounding rules. The _sat |
| modifier may not be used for conversions to floating-point formats. |
| </p> |
| </div> |
| <div class="refsect1"> |
| <a id="notes"></a> |
| <h2>Notes</h2> |
| <p> |
| For conversions to floating-point format, when a finite source |
| value exceeds the maximum representable finite |
| floating-point destination value, the rounding mode will affect |
| whether the result is the maximum finite floating-point value |
| or infinity of same sign as the source value, per IEEE-754 rules for rounding. |
| </p> |
| </div> |
| <div class="refsect2"> |
| <a id="example1"></a> |
| <h3> |
| Examples |
| </h3> |
| <div class="informaltable"> |
| <table border="0"> |
| <colgroup> |
| <col align="left" class="col1" /> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td align="left"> |
| short4 s; |
| |
| // negative values clamped to 0 |
| ushort4 u = convert_ushort4_sat( s ); |
| |
| // values > CHAR_MAX converted to CHAR_MAX |
| // values < CHAR_MIN converted to CHAR_MIN |
| char4 c = convert_char4_sat( s ); |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| </div> |
| <div class="refsect2"> |
| <a id="example2"></a> |
| <h3> |
| |
| </h3> |
| <div class="informaltable"> |
| <table border="0"> |
| <colgroup> |
| <col align="left" class="col1" /> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td align="left"> |
| float4 f; |
| |
| // values implementation defined for |
| // f > INT_MAX, f < INT_MIN or NaN |
| int4 i = convert_int4( f ); |
| |
| // values > INT_MAX clamp to INT_MAX, values < INT_MIN clamp |
| // to INT_MIN. NaN should produce 0. |
| // The _rtz rounding mode is |
| // used to produce the integer values. |
| int4 i2 = convert_int4_sat( f ); |
| |
| // similar to convert_int4, except that |
| // floating-point values are rounded to the nearest |
| // integer instead of truncated |
| int4 i3 = convert_int4_rte( f ); |
| |
| // similar to convert_int4_sat, except that |
| // floating-point values are rounded to the |
| // nearest integer instead of truncated |
| int4 i4 = convert_int4_sat_rte( f ); |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </div> |
| </div> |
| <div class="refsect2"> |
| <a id="example3"></a> |
| <h3> |
| |
| </h3> |
| <div class="informaltable"> |
| <table border="0"> |
| <colgroup> |
| <col align="left" class="col1" /> |
| </colgroup> |
| <tbody> |
| <tr> |
| <td align="left"> |
| int4 i; |
| |
| // convert ints to floats using the current rounding mode. |
| float4 f = convert_float4( i ); |
| |
| // convert ints to floats. integer values that cannot |
| // be exactly represented as floats should round up to the |
| // next representable float. |
| float4 f = convert_float4_rtp( i ); |
| </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-1.1.pdf#page=167" target="OpenCL Spec">OpenCL Specification</a> |
| </p> |
| </div> |
| <div class="refsect1"> |
| <a id="seealso"></a> |
| <h2>Also see</h2> |
| <p> |
| <a class="citerefentry" href="scalarDataTypes.html"><span class="citerefentry"><span class="refentrytitle">Scalar Data Types</span></span></a>, |
| <a class="citerefentry" href="vectorDataTypes.html"><span class="citerefentry"><span class="refentrytitle">Vector Data Types</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 © 2007-2010 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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