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<body class="book toc2 toc-left" style="max-width: 100;">
<div id="header">
<h1>The OpenCL<sup>&#8482;</sup> C 2.0 Specification</h1>
<div class="details">
<span id="author" class="author">Document Revision: 40</span><br>
<span id="revnumber">version 2.2-7,</span>
<span id="revdate">Sat, 12 May 2018 13:21:28 +0000</span>
<br><span id="revremark">from git branch: master commit: ab6da3001e9eeafaa36c18888ca7eb4ebb9768af</span>
</div>
<div id="toc" class="toc2">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#the-opencl-c-programming-language">1. The OpenCL C Programming Language</a>
<ul class="sectlevel2">
<li><a href="#supported-data-types">1.1. Supported Data Types</a>
<ul class="sectlevel3">
<li><a href="#built-in-scalar-data-types">1.1.1. Built-in Scalar Data Types</a></li>
<li><a href="#built-in-vector-data-types">1.1.2. Built-in Vector Data Types<sup>4</sup></a></li>
<li><a href="#other-built-in-data-types">1.1.3. Other Built-in Data Types</a></li>
<li><a href="#reserved-data-types">1.1.4. Reserved Data Types</a></li>
<li><a href="#alignment-of-types">1.1.5. Alignment of Types</a></li>
<li><a href="#vector-literals">1.1.6. Vector Literals</a></li>
<li><a href="#vector-components">1.1.7. Vector Components</a></li>
<li><a href="#aliasing-rules">1.1.8. Aliasing Rules</a></li>
<li><a href="#keywords">1.1.9. Keywords</a></li>
</ul>
</li>
<li><a href="#conversions-and-type-casting">1.2. Conversions and Type Casting</a>
<ul class="sectlevel3">
<li><a href="#implicit-conversions">1.2.1. Implicit Conversions</a></li>
<li><a href="#explicit-casts">1.2.2. Explicit Casts</a></li>
<li><a href="#explicit-conversions">1.2.3. Explicit Conversions</a></li>
<li><a href="#reinterpreting-data-as-another-type">1.2.4. Reinterpreting Data As Another Type</a></li>
<li><a href="#pointer-casting">1.2.5. Pointer Casting</a></li>
<li><a href="#usual-arithmetic-conversions">1.2.6. Usual Arithmetic Conversions</a></li>
</ul>
</li>
<li><a href="#operators">1.3. Operators</a>
<ul class="sectlevel3">
<li><a href="#operators-arithmetic">1.3.1. Arithmetic Operators</a></li>
<li><a href="#operators-unary">1.3.2. Unary Operators</a></li>
<li><a href="#operators-prepost">1.3.3. Operators</a></li>
<li><a href="#operators-relational">1.3.4. Relational Operators</a></li>
<li><a href="#operators-equality">1.3.5. Equality Operators</a></li>
<li><a href="#operators-bitwise">1.3.6. Bitwise Operators</a></li>
<li><a href="#operators-logical">1.3.7. Logical Operators</a></li>
<li><a href="#operators-logical-unary">1.3.8. Unary Logical Operator</a></li>
<li><a href="#operators-ternary-selection">1.3.9. Ternary Selection Operator</a></li>
<li><a href="#operators-shift">1.3.10. Shift Operators</a></li>
<li><a href="#operators-sizeof">1.3.11. Sizeof Operator</a></li>
<li><a href="#operators-comma">1.3.12. Comma Operator</a></li>
<li><a href="#operators-indirection">1.3.13. Indirection Operator</a></li>
<li><a href="#operators-address">1.3.14. Address Operator</a></li>
<li><a href="#operators-assignment">1.3.15. Assignment Operator</a></li>
</ul>
</li>
<li><a href="#vector-operations">1.4. Vector Operations</a></li>
<li><a href="#address-space-qualifiers">1.5. Address Space Qualifiers</a>
<ul class="sectlevel3">
<li><a href="#global-or-global">1.5.1. <code>__global</code> (or <code>global</code>)</a></li>
<li><a href="#local-or-local">1.5.2. <code>__local</code> (or <code>local</code>)</a></li>
<li><a href="#constant-or-constant">1.5.3. <code>__constant</code> (or <code>constant</code>)</a></li>
<li><a href="#private-or-private">1.5.4. <code>__private</code> (or <code>private</code>)</a></li>
<li><a href="#the-generic-address-space">1.5.5. The generic address space</a></li>
<li><a href="#changes-to-C99">1.5.6. Changes to C99</a></li>
</ul>
</li>
<li><a href="#access-qualifiers">1.6. Access Qualifiers</a></li>
<li><a href="#function-qualifiers">1.7. Function Qualifiers</a>
<ul class="sectlevel3">
<li><a href="#kernel-or-kernel">1.7.1. <code>__kernel</code> (or <code>kernel</code>)</a></li>
<li><a href="#optional-attribute-qualifiers">1.7.2. Optional Attribute Qualifiers</a></li>
</ul>
</li>
<li><a href="#storage-class-specifiers">1.8. Storage-Class Specifiers</a></li>
<li><a href="#restrictions">1.9. Restrictions</a></li>
<li><a href="#preprocessor-directives-and-macros">1.10. Preprocessor Directives and Macros</a></li>
<li><a href="#attribute-qualifiers">1.11. Attribute Qualifiers</a>
<ul class="sectlevel3">
<li><a href="#specifying-attributes-of-types">1.11.1. Specifying Attributes of Types</a></li>
<li><a href="#specifying-attributes-of-functions">1.11.2. Specifying Attributes of Functions</a></li>
<li><a href="#specifying-attributes-of-variables">1.11.3. Specifying Attributes of Variables</a></li>
<li><a href="#specifying-attributes-of-blocks-and-control-flow-statements">1.11.4. Specifying Attributes of Blocks and Control-Flow-Statements</a></li>
<li><a href="#specifying-attribute-for-unrolling-loops">1.11.5. Specifying Attribute For Unrolling Loops</a></li>
<li><a href="#extending-attribute-qualifiers">1.11.6. Extending Attribute Qualifiers</a></li>
</ul>
</li>
<li><a href="#blocks">1.12. Blocks</a>
<ul class="sectlevel3">
<li><a href="#declaring-and-using-a-block">1.12.1. Declaring and Using a Block</a></li>
<li><a href="#declaring-a-block-reference">1.12.2. Declaring a Block Reference</a></li>
<li><a href="#block-literal-expressions">1.12.3. Block Literal Expressions</a></li>
<li><a href="#control-flow">1.12.4. Control Flow</a></li>
<li><a href="#restrictions-1">1.12.5. Restrictions</a></li>
</ul>
</li>
<li><a href="#built-in-functions">1.13. Built-in Functions</a>
<ul class="sectlevel3">
<li><a href="#work-item-functions">1.13.1. Work-Item Functions</a></li>
<li><a href="#math-functions">1.13.2. Math Functions</a></li>
<li><a href="#integer-functions">1.13.3. Integer Functions</a></li>
<li><a href="#common-functions">1.13.4. Common Functions<sup>33</sup></a></li>
<li><a href="#geometric-functions">1.13.5. Geometric Functions<sup>34</sup></a></li>
<li><a href="#relational-functions">1.13.6. Relational Functions</a></li>
<li><a href="#vector-data-load-and-store-functions">1.13.7. Vector Data Load and Store Functions</a></li>
<li><a href="#synchronization-functions">1.13.8. Synchronization Functions</a></li>
<li><a href="#address-space-qualifier-functions">1.13.9. Address Space Qualifier Functions</a></li>
<li><a href="#async-copies">1.13.10. Async Copies from Global to Local Memory, Local to Global Memory, and Prefetch</a></li>
<li><a href="#atomic-functions">1.13.11. Atomic Functions</a></li>
<li><a href="#miscellaneous-vector-functions">1.13.12. Miscellaneous Vector Functions</a></li>
<li><a href="#printf">1.13.13. printf</a></li>
<li><a href="#image-read-and-write-functions">1.13.14. Image Read and Write Functions</a></li>
<li><a href="#work-group-functions">1.13.15. Work-group Functions</a></li>
<li><a href="#pipe-functions">1.13.16. Pipe Functions</a></li>
<li><a href="#enqueuing-kernels">1.13.17. Enqueuing Kernels</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#opencl-numerical-compliance">2. OpenCL Numerical Compliance</a>
<ul class="sectlevel2">
<li><a href="#rounding-modes-1">2.1. Rounding Modes</a></li>
<li><a href="#inf-nan-and-denormalized-numbers">2.2. INF, NaN and Denormalized Numbers</a></li>
<li><a href="#floating-point-exceptions">2.3. Floating-Point Exceptions</a></li>
<li><a href="#relative-error-as-ulps">2.4. Relative Error as ULPs</a></li>
<li><a href="#edge-case-behavior">2.5. Edge Case Behavior</a>
<ul class="sectlevel3">
<li><a href="#additional-requirements-beyond-c99-tc2">2.5.1. Additional Requirements Beyond C99 TC2</a></li>
<li><a href="#changes-to-c99-tc2-behavior">2.5.2. Changes to C99 TC2 Behavior</a></li>
<li><a href="#edge-case-behavior-in-flush-to-zero-mode">2.5.3. Edge Case Behavior in Flush To Zero Mode</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#image-addressing-and-filtering">3. Image Addressing and Filtering</a>
<ul class="sectlevel2">
<li><a href="#image-coordinates">3.1. Image Coordinates</a></li>
<li><a href="#addressing-and-filter-modes">3.2. Addressing and Filter Modes</a></li>
<li><a href="#conversion-rules">3.3. Conversion Rules</a>
<ul class="sectlevel3">
<li><a href="#conversion-rules-for-normalized-integer-channel-data-types">3.3.1. Conversion rules for normalized integer channel data types</a></li>
<li><a href="#conversion-rules-for-half-precision-floating-point-channel-data-type">3.3.2. Conversion rules for half precision floating-point channel data type</a></li>
<li><a href="#conversion-rules-for-floating-point-channel-data-type">3.3.3. Conversion rules for floating-point channel data type</a></li>
<li><a href="#conversion-rules-for-signed-and-unsigned-8-bit-16-bit-and-32-bit-integer-channel-data-types">3.3.4. Conversion rules for signed and unsigned 8-bit, 16-bit and 32-bit integer channel data types</a></li>
<li><a href="#conversion-rules-for-srgba-and-sbgra-images">3.3.5. Conversion rules for sRGBA and sBGRA images</a></li>
</ul>
</li>
<li><a href="#selecting-an-image-from-an-image-array">3.4. Selecting an Image from an Image Array</a></li>
</ul>
</li>
<li><a href="#references">4. Normative References</a></li>
</ul>
</div>
</div>
<div id="content">
<div id="preamble">
<div class="sectionbody">
<div style="page-break-after: always;"></div>
<div class="paragraph">
<p>Copyright 2008-2018 The Khronos Group.</p>
</div>
<div class="paragraph">
<p>This specification is protected by copyright laws and contains material proprietary
to the Khronos Group, Inc. Except as described by these terms, it or any components
may not be reproduced, republished, distributed, transmitted, displayed, broadcast
or otherwise exploited in any manner without the express prior written permission
of Khronos Group.</p>
</div>
<div class="paragraph">
<p>Khronos Group grants a conditional copyright license to use and reproduce the
unmodified specification for any purpose, without fee or royalty, EXCEPT no licenses
to any patent, trademark or other intellectual property rights are granted under
these terms. Parties desiring to implement the specification and make use of
Khronos trademarks in relation to that implementation, and receive reciprocal patent
license protection under the Khronos IP Policy must become Adopters and confirm the
implementation as conformant under the process defined by Khronos for this
specification; see <a href="https://www.khronos.org/adopters" class="bare">https://www.khronos.org/adopters</a>.</p>
</div>
<div class="paragraph">
<p>Khronos Group makes no, and expressly disclaims any, representations or warranties,
express or implied, regarding this specification, including, without limitation:
merchantability, fitness for a particular purpose, non-infringement of any
intellectual property, correctness, accuracy, completeness, timeliness, and
reliability. Under no circumstances will the Khronos Group, or any of its Promoters,
Contributors or Members, or their respective partners, officers, directors,
employees, agents or representatives be liable for any damages, whether direct,
indirect, special or consequential damages for lost revenues, lost profits, or
otherwise, arising from or in connection with these materials.</p>
</div>
<div class="paragraph">
<p>Vulkan is a registered trademark and Khronos, OpenXR, SPIR, SPIR-V, SYCL, WebGL,
WebCL, OpenVX, OpenVG, EGL, COLLADA, glTF, NNEF, OpenKODE, OpenKCAM, StreamInput,
OpenWF, OpenSL ES, OpenMAX, OpenMAX AL, OpenMAX IL, OpenMAX DL, OpenML and DevU are
trademarks of the Khronos Group Inc. ASTC is a trademark of ARM Holdings PLC,
OpenCL is a trademark of Apple Inc. and OpenGL and OpenML are registered trademarks
and the OpenGL ES and OpenGL SC logos are trademarks of Silicon Graphics
International used under license by Khronos. All other product names, trademarks,
and/or company names are used solely for identification and belong to their
respective owners.</p>
</div>
<div style="page-break-after: always;"></div>
<div class="paragraph">
<p><strong>Acknowledgements</strong></p>
</div>
<div class="paragraph">
<p>The OpenCL specification is the result of the contributions of many people,
representing a cross section of the desktop, hand-held, and embedded
computer industry.
Following is a partial list of the contributors, including the company that
they represented at the time of their contribution:</p>
</div>
<div class="paragraph">
<p>Chuck Rose, Adobe<br>
Eric Berdahl, Adobe<br>
Shivani Gupta, Adobe<br>
Bill Licea Kane, AMD<br>
Ed Buckingham, AMD<br>
Jan Civlin, AMD<br>
Laurent Morichetti, AMD<br>
Mark Fowler, AMD<br>
Marty Johnson, AMD<br>
Michael Mantor, AMD<br>
Norm Rubin, AMD<br>
Ofer Rosenberg, AMD<br>
Brian Sumner, AMD<br>
Victor Odintsov, AMD<br>
Aaftab Munshi, Apple<br>
Abe Stephens, Apple<br>
Alexandre Namaan, Apple<br>
Anna Tikhonova, Apple<br>
Chendi Zhang, Apple<br>
Eric Bainville, Apple<br>
David Hayward, Apple<br>
Giridhar Murthy, Apple<br>
Ian Ollmann, Apple<br>
Inam Rahman, Apple<br>
James Shearer, Apple<br>
MonPing Wang, Apple<br>
Tanya Lattner, Apple<br>
Mikael Bourges-Sevenier, Aptina<br>
Anton Lokhmotov, ARM<br>
Dave Shreiner, ARM<br>
Hedley Francis, ARM<br>
Robert Elliott, ARM<br>
Scott Moyers, ARM<br>
Tom Olson, ARM<br>
Anastasia Stulova, ARM<br>
Christopher Thompson-Walsh, Broadcom<br>
Holger Waechtler, Broadcom<br>
Norman Rink, Broadcom<br>
Andrew Richards, Codeplay<br>
Maria Rovatsou, Codeplay<br>
Alistair Donaldson, Codeplay<br>
Alastair Murray, Codeplay<br>
Stephen Frye, Electronic Arts<br>
Eric Schenk, Electronic Arts<br>
Daniel Laroche, Freescale<br>
David Neto, Google<br>
Robin Grosman, Huawei<br>
Craig Davies, Huawei<br>
Brian Horton, IBM<br>
Brian Watt, IBM<br>
Gordon Fossum, IBM<br>
Greg Bellows, IBM<br>
Joaquin Madruga, IBM<br>
Mark Nutter, IBM<br>
Mike Perks, IBM<br>
Sean Wagner, IBM<br>
Jon Parr, Imagination Technologies<br>
Robert Quill, Imagination Technologies<br>
James McCarthy, Imagination Technologie<br>
Jon Leech, Independent<br>
Aaron Kunze, Intel<br>
Aaron Lefohn, Intel<br>
Adam Lake, Intel<br>
Alexey Bader, Intel<br>
Allen Hux, Intel<br>
Andrew Brownsword, Intel<br>
Andrew Lauritzen, Intel<br>
Bartosz Sochacki, Intel<br>
Ben Ashbaugh, Intel<br>
Brian Lewis, Intel<br>
Geoff Berry, Intel<br>
Hong Jiang, Intel<br>
Jayanth Rao, Intel<br>
Josh Fryman, Intel<br>
Larry Seiler, Intel<br>
Mike MacPherson, Intel<br>
Murali Sundaresan, Intel<br>
Paul Lalonde, Intel<br>
Raun Krisch, Intel<br>
Stephen Junkins, Intel<br>
Tim Foley, Intel<br>
Timothy Mattson, Intel<br>
Yariv Aridor, Intel<br>
Michael Kinsner, Intel<br>
Kevin Stevens, Intel<br>
Jon Leech, Khronos<br>
Benjamin Bergen, Los Alamos National Laboratory<br>
Roy Ju, Mediatek<br>
Bor-Sung Liang, Mediatek<br>
Rahul Agarwal, Mediatek<br>
Michal Witaszek, Mobica<br>
JenqKuen Lee, NTHU<br>
Amit Rao, NVIDIA<br>
Ashish Srivastava, NVIDIA<br>
Bastiaan Aarts, NVIDIA<br>
Chris Cameron, NVIDIA<br>
Christopher Lamb, NVIDIA<br>
Dibyapran Sanyal, NVIDIA<br>
Guatam Chakrabarti, NVIDIA<br>
Ian Buck, NVIDIA<br>
Jaydeep Marathe, NVIDIA<br>
Jian-Zhong Wang, NVIDIA<br>
Karthik Raghavan Ravi, NVIDIA<br>
Kedar Patil, NVIDIA<br>
Manjunath Kudlur, NVIDIA<br>
Mark Harris, NVIDIA<br>
Michael Gold, NVIDIA<br>
Neil Trevett, NVIDIA<br>
Richard Johnson, NVIDIA<br>
Sean Lee, NVIDIA<br>
Tushar Kashalikar, NVIDIA<br>
Vinod Grover, NVIDIA<br>
Xiangyun Kong, NVIDIA<br>
Yogesh Kini, NVIDIA<br>
Yuan Lin, NVIDIA<br>
Mayuresh Pise, NVIDIA<br>
Allan Tzeng, QUALCOMM<br>
Alex Bourd, QUALCOMM<br>
Anirudh Acharya, QUALCOMM<br>
Andrew Gruber, QUALCOMM<br>
Andrzej Mamona, QUALCOMM<br>
Benedict Gaster, QUALCOMM<br>
Bill Torzewski, QUALCOMM<br>
Bob Rychlik, QUALCOMM<br>
Chihong Zhang, QUALCOMM<br>
Chris Mei, QUALCOMM<br>
Colin Sharp, QUALCOMM<br>
David Garcia, QUALCOMM<br>
David Ligon, QUALCOMM<br>
Jay Yun, QUALCOMM<br>
Lee Howes, QUALCOMM<br>
Richard Ruigrok, QUALCOMM<br>
Robert J. Simpson, QUALCOMM<br>
Sumesh Udayakumaran, QUALCOMM<br>
Vineet Goel, QUALCOMM<br>
Lihan Bin, QUALCOMM<br>
Vlad Shimanskiy, QUALCOMM<br>
Jian Liu, QUALCOMM<br>
Tasneem Brutch, Samsung<br>
Yoonseo Choi, Samsung<br>
Dennis Adams, Sony<br>
Pr-Anders Aronsson, Sony<br>
Jim Rasmusson, Sony<br>
Thierry Lepley, STMicroelectronics<br>
Anton Gorenko, StreamHPC<br>
Jakub Szuppe, StreamHPC<br>
Vincent Hindriksen, StreamHPC<br>
Alan Ward, Texas Instruments<br>
Yuan Zhao, Texas Instruments<br>
Pete Curry, Texas Instruments<br>
Simon McIntosh-Smith, University of Bristol<br>
James Price, University of Bristol<br>
Paul Preney, University of Windsor<br>
Shane Peelar, University of Windsor<br>
Brian Hutsell, Vivante<br>
Mike Cai, Vivante<br>
Sumeet Kumar, Vivante<br>
Wei-Lun Kao, Vivante<br>
Xing Wang, Vivante<br>
Jeff Fifield, Xilinx<br>
Hem C. Neema, Xilinx<br>
Henry Styles, Xilinx<br>
Ralph Wittig, Xilinx<br>
Ronan Keryell, Xilinx<br>
AJ Guillon, YetiWare Inc<br></p>
</div>
<div style="page-break-after: always;"></div>
</div>
</div>
<div class="sect1">
<h2 id="the-opencl-c-programming-language">1. The OpenCL C Programming Language</h2>
<div class="sectionbody">
<div class="paragraph">
<p>This section describes the OpenCL C programming language used to create
kernels that are executed on OpenCL device(s).
The OpenCL C programming language (also referred to as OpenCL C) is based on
the <a href="#C99-spec">ISO/IEC 9899:1999 C language</a> Specification (a.k.a. &#8220;C99
Specification&#8221; or just &#8220;C99&#8221;) with specific extensions and restrictions.
Please refer to that Specification for a detailed description of the
language grammar.
This document describes modifications and restrictions to C99 supported in
OpenCL C.</p>
</div>
<div class="paragraph">
<p>In addition, some features of OpenCL C are based on the <a href="#C11-spec">ISO/IEC
9899:2011 C language</a> Specification (a.k.a. &#8220;C11 Specification&#8221; or just
&#8220;C11&#8221;.
Such features are described by reference to that Specification.</p>
</div>
<div class="sect2">
<h3 id="supported-data-types">1.1. Supported Data Types</h3>
<div class="paragraph">
<p>The following data types are supported.</p>
</div>
<div class="sect3">
<h4 id="built-in-scalar-data-types">1.1.1. Built-in Scalar Data Types</h4>
<div class="paragraph">
<p>The following table describes the list of built-in scalar data types.</p>
</div>
<table id="table-builtin-scalar-types" class="tableblock frame-all grid-all spread">
<caption class="title">Table 1. Built-in Scalar Data Types</caption>
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Type</strong></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Description</strong></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>bool</code><sup>1</sup></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A conditional data type which is either <em>true</em> or <em>false</em>.
The value <em>true</em> expands to the integer constant 1 and the value
<em>false</em> expands to the integer constant 0.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>char</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A signed two&#8217;s complement 8-bit integer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned char</code>, <code>uchar</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An unsigned 8-bit integer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>short</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A signed two&#8217;s complement 16-bit integer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned short</code>, <code>ushort</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An unsigned 16-bit integer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>int</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A signed two&#8217;s complement 32-bit integer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned int</code>, <code>uint</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An unsigned 32-bit integer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>long</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A signed two&#8217;s complement 64-bit integer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned long</code>, <code>ulong</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An unsigned 64-bit integer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>float</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 32-bit floating-point.
The <code>float</code> data type must conform to the IEEE 754 single precision
storage format.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>double</code><sup>2</sup></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 64-bit floating-point.
The <code>double</code> data type must conform to the IEEE 754 double precision
storage format.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>half</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 16-bit floating-point.
The <code>half</code> data type must conform to the IEEE 754-2008 half precision
storage format.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>size_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">The unsigned integer type<sup>3</sup> of the result of the <code>sizeof</code> operator.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ptrdiff_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A signed integer type<sup>3</sup> that is the result of subtracting two
pointers.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>intptr_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A signed integer type<sup>3</sup> with the property that any valid pointer to
<code>void</code> can be converted to this type, then converted back to pointer
to <code>void</code>, and the result will compare equal to the original pointer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>uintptr_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An unsigned integer type<sup>3</sup> with the property that any valid pointer
to <code>void</code> can be converted to this type, then converted back to
pointer to <code>void</code>, and the result will compare equal to the original
pointer.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>void</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">The <code>void</code> type comprises an empty set of values; it is an incomplete
type that cannot be completed.</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>[1] When any scalar value is converted to <code>bool</code>, the result is 0 if the
value compares equal to 0; otherwise, the result is 1.</p>
</div>
<div class="paragraph">
<p>[2] The <code>double</code> scalar type is an optional type that is supported if the
value of the <a href="#opencl-device-queries"><code>CL_DEVICE_DOUBLE_FP_CONFIG</code> device
query</a> is not zero.</p>
</div>
<div class="paragraph">
<p>[3] These are 32-bit types if the value of the <a href="#opencl-device-queries"><code>CL_DEVICE_ADDRESS_BITS</code> device query</a> is 32-bits, and 64-bit types if the
value of the query is 64-bits.</p>
</div>
<div class="paragraph">
<p>Most built-in scalar data types are also declared as appropriate types in
the OpenCL API (and header files) that can be used by an application.
The following table describes the built-in scalar data type in the OpenCL C
programming language and the corresponding data type available to the
application:</p>
</div>
<table class="tableblock frame-all grid-all spread">
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Type in OpenCL Language</strong></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>API type for application</strong></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>bool</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">n/a</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>char</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_char</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned char</code>, <code>uchar</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_uchar</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>short</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_short</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned short</code>, <code>ushort</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_ushort</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>int</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_int</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned int</code>, <code>uint</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_uint</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>long</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_long</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned long</code>, <code>ulong</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_ulong</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>float</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_float</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>double</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_double</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>half</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_half</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>size_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">n/a</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ptrdiff_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">n/a</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>intptr_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">n/a</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>uintptr_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">n/a</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>void</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>void</code></p></td>
</tr>
</tbody>
</table>
<div class="sect4">
<h5 id="the-half-data-type">The <code>half</code> data type</h5>
<div class="paragraph">
<p>The <code>half</code> data type must be IEEE 754-2008 compliant.
<code>half</code> numbers have 1 sign bit, 5 exponent bits, and 10 mantissa bits.
The interpretation of the sign, exponent and mantissa is analogous to IEEE
754 floating-point numbers.
The exponent bias is 15.
The <code>half</code> data type must represent finite and normal numbers, denormalized
numbers, infinities and NaN.
Denormalized numbers for the <code>half</code> data type which may be generated when
converting a <code>float</code> to a <code>half</code> using <strong>vstore_half</strong> and converting a <code>half</code>
to a <code>float</code> using <strong>vload_half</strong> cannot be flushed to zero.
Conversions from <code>float</code> to <code>half</code> correctly round the mantissa to 11 bits
of precision.
Conversions from <code>half</code> to <code>float</code> are lossless; all <code>half</code> numbers are
exactly representable as <code>float</code> values.</p>
</div>
<div class="paragraph">
<p>The <code>half</code> data type can only be used to declare a pointer to a buffer that
contains <code>half</code> values.
A few valid examples are given below:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c"><span class="directive">void</span>
bar (__global half *p)
{
...
}
__kernel <span class="directive">void</span>
foo (__global half *pg, __local half *pl)
{
__global half *ptr;
<span class="predefined-type">int</span> offset;
ptr = pg + offset;
bar(ptr);
}</code></pre>
</div>
</div>
<div class="paragraph">
<p>Below are some examples that are not valid usage of the <code>half</code> type:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">half a;
half b[<span class="integer">100</span>];
half *p;
a = *p; <span class="comment">// not allowed. must use *vload_half* function</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>Loads from a pointer to a <code>half</code> and stores to a pointer to a <code>half</code> can be
performed using the <a href="#vector-data-load-and-store-functions">vector data load
and store functions</a> <strong>vload_half</strong>, <strong>vload_half<em>n</em></strong>, <strong>vloada_halfn</strong> and
<strong>vstore_half</strong>, <strong>vstore_half<em>n</em></strong>, and <strong>vstorea_halfn</strong>.
The load functions read scalar or vector <code>half</code> values from memory and
convert them to a scalar or vector <code>float</code> value.
The store functions take a scalar or vector <code>float</code> value as input, convert
it to a <code>half</code> scalar or vector value (with appropriate rounding mode) and
write the <code>half</code> scalar or vector value to memory.</p>
</div>
</div>
</div>
<div class="sect3">
<h4 id="built-in-vector-data-types">1.1.2. Built-in Vector Data Types<sup>4</sup></h4>
<div class="paragraph">
<p>The <code>char</code>, <code>unsigned char</code>, <code>short</code>, <code>unsigned short</code>, <code>int</code>, <code>unsigned
int</code>, <code>long</code>, <code>unsigned long</code>, and <code>float</code> vector data types are supported.
The vector data type is defined with the type name, i.e. <code>char</code>, <code>uchar</code>,
<code>short</code>, <code>ushort</code>, <code>int</code>, <code>uint</code>, <code>long</code>, <code>ulong</code>, or <code>float</code>, followed by a
literal value <em>n</em> that defines the number of elements in the vector.
Supported values of <em>n</em> are 2, 3, 4, 8, and 16 for all vector data types.</p>
</div>
<div class="paragraph">
<p>[4] Built-in vector data types are supported by the OpenCL implementation
even if the underlying compute device does not support any or all of the
vector data types.
These are to be converted by the device compiler to appropriate instructions
that use underlying built-in types supported natively by the compute device.
Refer to Appendix B for a description of the order of the components of a
vector type in memory.</p>
</div>
<div class="paragraph">
<p>The following table describes the list of built-in vector data types.</p>
</div>
<table id="table-builtin-vector-types" class="tableblock frame-all grid-all spread">
<caption class="title">Table 2. Built-in Vector Data Types</caption>
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Type</strong></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Description</strong></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>char<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 8-bit signed two&#8217;s complement integer values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>uchar<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 8-bit unsigned integer values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>short<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 16-bit signed two&#8217;s complement integer values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ushort<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 16-bit unsigned integer values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>int<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 32-bit signed two&#8217;s complement integer values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>uint<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 32-bit unsigned integer values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>long<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 64-bit signed two&#8217;s complement integer values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ulong<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 64-bit unsigned integer values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>float<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 32-bit floating-point values.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>double<em>n</em></code><sup>5</sup></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A vector of <em>n</em> 64-bit floating-point values.</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>[5] The <code>double</code> vector type is an optional type that is supported if the
value of the <a href="#opencl-device-queries"><code>CL_DEVICE_DOUBLE_FP_CONFIG</code> device
query</a> is not zero.</p>
</div>
<div class="paragraph">
<p>The built-in vector data types are also declared as appropriate types in the
OpenCL API (and header files) that can be used by an application.
The following table describes the built-in vector data type in the OpenCL C
programming language and the corresponding data type available to the
application:</p>
</div>
<table class="tableblock frame-all grid-all spread">
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Type in OpenCL Language</strong></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>API type for application</strong></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>char<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_char<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>uchar<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_uchar<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>short<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_short<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ushort<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_ushort<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>int<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_int<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>uint<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_uint<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>long<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_long<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ulong<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_ulong<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>float<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_float<em>n</em></code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>double<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_double<em>n</em></code></p></td>
</tr>
</tbody>
</table>
</div>
<div class="sect3">
<h4 id="other-built-in-data-types">1.1.3. Other Built-in Data Types</h4>
<div class="paragraph">
<p>The following table describes the list of additional data types supported by
OpenCL.</p>
</div>
<table id="table-other-builtin-types" class="tableblock frame-all grid-all spread">
<caption class="title">Table 3. Other Built-in Data Types</caption>
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Type</strong></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Description</strong></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>image2d_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 2D image<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>image3d_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 3D image<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>image2d_array_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 2D image array<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>image1d_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 1D image<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>image1d_buffer_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 1D image created from a buffer object<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>image1d_array_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 1D image array<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>image2d_depth_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 2D depth image<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>image2d_array_depth_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 2D depth image array<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>sampler_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A sampler type<sup>6</sup>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>queue_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A device command queue.
This queue can only be used to enqueue commands from kernels executing
on the device.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>ndrange_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">The N-dimensional range over which a kernel executes.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>clk_event_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A device side event that identifies a command enqueue to
a device command queue.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>reserve_id_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A reservation ID.
This opaque type is used to identify the reservation for
<a href="#pipe-functions">reading and writing a pipe</a>.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>event_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An event.
This can be used to identify <a href="#async-copies">async copies</a> from
<code>global</code> to <code>local</code> memory and vice-versa.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_mem_fence_flags</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">This is a bitfield and can be 0 or a combination of the following
values ORed together:</p>
<p class="tableblock"> <code>CLK_GLOBAL_MEM_FENCE</code><br>
<code>CLK_LOCAL_MEM_FENCE</code><br>
<code>CLK_IMAGE_MEM_FENCE</code></p>
<p class="tableblock"> These flags are described in detail in the
<a href="#synchronization-functions">synchronization functions</a> section.</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>[6] Refer to the detailed description of the built-in
<a href="#image-read-and-write-functions">functions that use this type</a>.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
<div class="paragraph">
<p>The <code>image2d_t</code>, <code>image3d_t</code>, <code>image2d_array_t</code>, <code>image1d_t</code>,
<code>image1d_buffer_t</code>, <code>image1d_array_t</code>, <code>image2d_depth_t</code>,
<code>image2d_array_depth_t</code> and <code>sampler_t</code> types are only defined if the device
supports images, i.e. the value of the <a href="#opencl-device-queries"><code>CL_DEVICE_IMAGE_SUPPORT</code> device query</a>) is <code>CL_TRUE</code>.</p>
</div>
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>The C99 derived types (arrays, structs, unions, functions, and pointers),
constructed from the built-in <a href="#built-in-scalar-data-types">scalar</a>,
<a href="#built-in-vector-data-types">vector</a>, and
<a href="#other-built-in-data-types">other</a> data types are supported, with specified
<a href="#restrictions">restrictions</a>.</p>
</div>
<div class="paragraph">
<p>The following tables describe the other built-in data types in OpenCL
described in <a href="#table-other-builtin-types">Other Built-in Data Types</a> and the corresponding data type
available to the application:</p>
</div>
<table class="tableblock frame-all grid-all spread">
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Type in OpenCL C</strong></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>API type for application</strong></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>queue_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_command_queue</code></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>clk_event_t</code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>cl_event</code></p></td>
</tr>
</tbody>
</table>
</div>
<div class="sect3">
<h4 id="reserved-data-types">1.1.4. Reserved Data Types</h4>
<div class="paragraph">
<p>The data type names described in the following table are reserved and cannot
be used by applications as type names.
The vector data type names defined in <a href="#table-builtin-vector-types">Built-in Vector Data Types</a>, but
where <em>n</em> is any value other than 2, 3, 4, 8 and 16, are also reserved.</p>
</div>
<table id="table-reserved-types" class="tableblock frame-all grid-all spread">
<caption class="title">Table 4. Reserved Data Types</caption>
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Type</strong></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Description</strong></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>bool<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A boolean vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>half<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 16-bit floating-point vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>quad</code>, <code>quad<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 128-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>complex half</code>, <code>complex half<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A complex 16-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>imaginary half</code>, <code>imaginary half<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An imaginary 16-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>complex float</code>, <code>complex float<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A complex 32-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>imaginary float</code>, <code>imaginary float<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An imaginary 32-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>complex double</code>, <code>complex double<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A complex 64-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>imaginary double</code>, <code>imaginary double<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An imaginary 64-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>complex quad</code>, <code>complex quad<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A complex 128-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>imaginary quad</code>, <code>imaginary quad<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An imaginary 128-bit floating-point scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>float<em>n</em>x<em>m</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An <em>n</em> × <em>m</em> matrix of single precision floating-point values
stored in column-major order.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>double<em>n</em>x<em>m</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">An <em>n</em> × <em>m</em> matrix of double precision floating-point values
stored in column-major order.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>long double</code> <code>long double<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A floating-point scalar and vector type with at least as much
precision and range as a <code>double</code> and no more precision and range than
a quad.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>long long, long long<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 128-bit signed integer scalar and vector.</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><code>unsigned long long</code>,
<code>ulong long</code>,
<code>ulong long<em>n</em></code></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">A 128-bit unsigned integer scalar and vector.</p></td>
</tr>
</tbody>
</table>
</div>
<div class="sect3">
<h4 id="alignment-of-types">1.1.5. Alignment of Types</h4>
<div class="paragraph">
<p>A data item declared to be a data type in memory is always aligned to the
size of the data type in bytes.
For example, a <code>float4</code> variable will be aligned to a 16-byte boundary, a
<code>char2</code> variable will be aligned to a 2-byte boundary.</p>
</div>
<div class="paragraph">
<p>For 3-component vector data types, the size of the data type is <code>4 *
sizeof(component)</code>.
This means that a 3-component vector data type will be aligned to a <code>4 *
sizeof(component)</code> boundary.
The <strong>vload3</strong> and <strong>vstore3</strong> built-in functions can be used to read and write,
respectively, 3-component vector data types from an array of packed scalar
data type.</p>
</div>
<div class="paragraph">
<p>A built-in data type that is not a power of two bytes in size must be
aligned to the next larger power of two.
This rule applies to built-in types only, not structs or unions.</p>
</div>
<div class="paragraph">
<p>The OpenCL compiler is responsible for aligning data items to the
appropriate alignment as required by the data type.
For arguments to a <code>__kernel</code> function declared to be a pointer to a data
type, the OpenCL compiler can assume that the pointee is always
appropriately aligned as required by the data type.
The behavior of an unaligned load or store is undefined, except for the
<a href="#vector-data-load-and-store-functions">vector data load and store
functions</a> <strong>vload<em>n</em></strong>, <strong>vload_half<em>n</em></strong>, <strong>vstore<em>n</em></strong>, and
<strong>vstore_half<em>n</em></strong>.
The vector load functions can read a vector from an address aligned to the
element type of the vector.
The vector store functions can write a vector to an address aligned to the
element type of the vector.</p>
</div>
</div>
<div class="sect3">
<h4 id="vector-literals">1.1.6. Vector Literals</h4>
<div class="paragraph">
<p>Vector literals can be used to create vectors from a list of scalars,
vectors or a mixture thereof.
A vector literal can be used either as a vector initializer or as a primary
expression.
A vector literal cannot be used as an l-value.</p>
</div>
<div class="paragraph">
<p>A vector literal is written as a parenthesized vector type followed by a
parenthesized comma delimited list of parameters.
A vector literal operates as an overloaded function.
The forms of the function that are available is the set of possible argument
lists for which all arguments have the same element type as the result
vector, and the total number of elements is equal to the number of elements
in the result vector.
In addition, a form with a single scalar of the same type as the element
type of the vector is available.
For example, the following forms are available for <code>float4</code>:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">(float4)( <span class="predefined-type">float</span>, <span class="predefined-type">float</span>, <span class="predefined-type">float</span>, <span class="predefined-type">float</span> )
(float4)( float2, <span class="predefined-type">float</span>, <span class="predefined-type">float</span> )
(float4)( <span class="predefined-type">float</span>, float2, <span class="predefined-type">float</span> )
(float4)( <span class="predefined-type">float</span>, <span class="predefined-type">float</span>, float2 )
(float4)( float2, float2 )
(float4)( float3, <span class="predefined-type">float</span> )
(float4)( <span class="predefined-type">float</span>, float3 )
(float4)( <span class="predefined-type">float</span> )</code></pre>
</div>
</div>
<div class="paragraph">
<p>Operands are evaluated by standard rules for function evaluation, except
that implicit scalar widening shall not occur.
The order in which the operands are evaluated is undefined.
The operands are assigned to their respective positions in the result vector
as they appear in memory order.
That is, the first element of the first operand is assigned to <code>result.x</code>,
the second element of the first operand (or the first element of the second
operand if the first operand was a scalar) is assigned to <code>result.y</code>, etc.
In the case of the form that has a single scalar operand, the operand is
replicated across all lanes of the vector.</p>
</div>
<div class="paragraph">
<p>Examples:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float4 f = (float4)(<span class="float">1</span><span class="float">.0f</span>, <span class="float">2</span><span class="float">.0f</span>, <span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>);
uint4 u = (uint4)(<span class="integer">1</span>); <span class="comment">// u will be (1, 1, 1, 1).</span>
float4 f = (float4)float2)(<span class="float">1</span><span class="float">.0f</span>, <span class="float">2</span><span class="float">.0f</span>), (float2)(<span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>;
float4 f = (float4)(<span class="float">1</span><span class="float">.0f</span>, (float2)(<span class="float">2</span><span class="float">.0f</span>, <span class="float">3</span><span class="float">.0f</span>), <span class="float">4</span><span class="float">.0f</span>);
float4 f = (float4)(<span class="float">1</span><span class="float">.0f</span>, <span class="float">2</span><span class="float">.0f</span>); <span class="comment">// error</span></code></pre>
</div>
</div>
</div>
<div class="sect3">
<h4 id="vector-components">1.1.7. Vector Components</h4>
<div class="paragraph">
<p>The components of vector data types with 1 &#8230;&#8203; 4 components can be addressed
as <code>&lt;vector_data_type&gt;.xyzw</code>.
Vector data types of type <code>char2</code>, <code>uchar2</code>, <code>short2</code>, <code>ushort2</code>, <code>int2</code>,
<code>uint2</code>, <code>long2</code>, <code>ulong2</code>, and <code>float2</code> can access <code>.xy</code> elements.
Vector data types of type <code>char3</code>, <code>uchar3</code>, <code>short3</code>, <code>ushort3</code>, <code>int3</code>,
<code>uint3</code>, <code>long3</code>, <code>ulong3</code>, and <code>float3</code> can access <code>.xyz</code> elements.
Vector data types of type <code>char4</code>, <code>uchar4</code>, <code>short4</code>, <code>ushort4</code>, <code>int4</code>,
<code>uint4</code>, <code>long4</code>, <code>ulong4</code>, and <code>float4</code> can access <code>.xyzw</code> elements.</p>
</div>
<div class="paragraph">
<p>Accessing components beyond those declared for the vector type is an error
so, for example:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float2 pos;
pos.x = <span class="float">1</span><span class="float">.0f</span>; <span class="comment">// is legal</span>
pos.z = <span class="float">1</span><span class="float">.0f</span>; <span class="comment">// is illegal</span>
float3 pos;
pos.z = <span class="float">1</span><span class="float">.0f</span>; <span class="comment">// is legal</span>
pos.w = <span class="float">1</span><span class="float">.0f</span>; <span class="comment">// is illegal</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>The component selection syntax allows multiple components to be selected by
appending their names after the period (<strong>.</strong>).</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float4 c;
c.xyzw = (float4)(<span class="float">1</span><span class="float">.0f</span>, <span class="float">2</span><span class="float">.0f</span>, <span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>);
c.z = <span class="float">1</span><span class="float">.0f</span>;
c.xy = (float2)(<span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>);
c.xyz = (float3)(<span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>, <span class="float">5</span><span class="float">.0f</span>);</code></pre>
</div>
</div>
<div class="paragraph">
<p>The component selection syntax also allows components to be permuted or
replicated.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float4 pos = (float4)(<span class="float">1</span><span class="float">.0f</span>, <span class="float">2</span><span class="float">.0f</span>, <span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>);
float4 swiz= pos.wzyx; <span class="comment">// swiz = (4.0f, 3.0f, 2.0f, 1.0f)</span>
float4 dup = pos.xxyy; <span class="comment">// dup = (1.0f, 1.0f, 2.0f, 2.0f)</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>The component group notation can occur on the left hand side of an
expression.
To form an l-value, swizzling must be applied to an l-value of vector type,
contain no duplicate components, and it results in an l-value of scalar or
vector type, depending on number of components specified.
Each component must be a supported scalar or vector type.</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float4 pos = (float4)(<span class="float">1</span><span class="float">.0f</span>, <span class="float">2</span><span class="float">.0f</span>, <span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>);
pos.xw = (float2)(<span class="float">5</span><span class="float">.0f</span>, <span class="float">6</span><span class="float">.0f</span>);<span class="comment">// pos = (5.0f, 2.0f, 3.0f, 6.0f)</span>
pos.wx = (float2)(<span class="float">7</span><span class="float">.0f</span>, <span class="float">8</span><span class="float">.0f</span>);<span class="comment">// pos = (8.0f, 2.0f, 3.0f, 7.0f)</span>
pos.xyz = (float3)(<span class="float">3</span><span class="float">.0f</span>, <span class="float">5</span><span class="float">.0f</span>, <span class="float">9</span><span class="float">.0f</span>); <span class="comment">// pos = (3.0f, 5.0f, 9.0f, 4.0f)</span>
pos.xx = (float2)(<span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>);<span class="comment">// illegal - 'x' used twice</span>
<span class="comment">// illegal - mismatch between float2 and float4</span>
pos.xy = (float4)(<span class="float">1</span><span class="float">.0f</span>, <span class="float">2</span><span class="float">.0f</span>, <span class="float">3</span><span class="float">.0f</span>, <span class="float">4</span><span class="float">.0f</span>);
float4 a, b, c, d;
float16 x;
x = (float16)(a, b, c, d);
x = (float16)(a.xxxx, b.xyz, c.xyz, d.xyz, a.yzw);
<span class="comment">// illegal - component a.xxxxxxx is not a valid vector type</span>
x = (float16)(a.xxxxxxx, b.xyz, c.xyz, d.xyz);</code></pre>
</div>
</div>
<div class="paragraph">
<p>Elements of vector data types can also be accessed using a numeric index to
refer to the appropriate element in the vector.
The numeric indices that can be used are given in the table below:</p>
</div>
<table id="table-vector-indices" class="tableblock frame-all grid-all spread">
<caption class="title">Table 5. Numeric indices for built-in vector data types</caption>
<colgroup>
<col style="width: 50%;">
<col style="width: 50%;">
</colgroup>
<tbody>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Vector Components</strong></p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock"><strong>Numeric indices that can be used</strong></p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">2-component</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">0, 1</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">3-component</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">0, 1, 2</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">4-component</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">0, 1, 2, 3</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">8-component</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">0, 1, 2, 3, 4, 5, 6, 7</p></td>
</tr>
<tr>
<td class="tableblock halign-left valign-top"><p class="tableblock">16-component</p></td>
<td class="tableblock halign-left valign-top"><p class="tableblock">0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
a, A, b, B, c, C, d, D, e, E, f, F</p></td>
</tr>
</tbody>
</table>
<div class="paragraph">
<p>The numeric indices must be preceded by the letter <code>s</code> or <code>S</code>.</p>
</div>
<div class="paragraph">
<p>In the following example</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float8 f;</code></pre>
</div>
</div>
<div class="paragraph">
<p><code>f.s0</code> refers to the 1<sup>st</sup> element of the <code>float8</code> variable <code>f</code> and <code>f.s7</code>
refers to the 8<sup>th</sup> element of the <code>float8</code> variable <code>f</code>.</p>
</div>
<div class="paragraph">
<p>In the following example</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float16 x;</code></pre>
</div>
</div>
<div class="paragraph">
<p><code>x.sa</code> (or <code>x.sA</code>) refers to the 11<sup>th</sup> element of the <code>float16</code> variable
<code>x</code> and <code>x.sf</code> (or <code>x.sF</code>) refers to the 16<sup>th</sup> element of the <code>float16</code>
variable <code>x</code>.</p>
</div>
<div class="paragraph">
<p>The numeric indices used to refer to an appropriate element in the vector
cannot be intermixed with <code>.xyzw</code> notation used to access elements of a 1 ..
4 component vector.</p>
</div>
<div class="paragraph">
<p>For example</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float4 f, a;
a = f.x12w; <span class="comment">// illegal use of numeric indices with .xyzw</span>
a.xyzw = f.s0123; <span class="comment">// valid</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>Vector data types can use the <code>.lo</code> (or <code>.even</code>) and <code>.hi</code> (or <code>.odd</code>)
suffixes to get smaller vector types or to combine smaller vector types to a
larger vector type.
Multiple levels of <code>.lo</code> (or <code>.even</code>) and <code>.hi</code> (or <code>.odd</code>) suffixes can be
used until they refer to a scalar term.</p>
</div>
<div class="paragraph">
<p>The <code>.lo</code> suffix refers to the lower half of a given vector.
The <code>.hi</code> suffix refers to the upper half of a given vector.</p>
</div>
<div class="paragraph">
<p>The <code>.even</code> suffix refers to the even elements of a vector.
The <code>.odd</code> suffix refers to the odd elements of a vector.</p>
</div>
<div class="paragraph">
<p>Some examples to help illustrate this are given below:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float4 vf;
float2 low = vf.lo; <span class="comment">// returns vf.xy</span>
float2 high = vf.hi; <span class="comment">// returns vf.zw</span>
float2 even = vf.even; <span class="comment">// returns vf.xz</span>
float2 odd = vf.odd; <span class="comment">// returns vf.yw</span></code></pre>
</div>
</div>
<div class="paragraph">
<p>The suffixes <code>.lo</code> (or <code>.even</code>) and <code>.hi</code> (or <code>.odd</code>) for a 3-component
vector type operate as if the 3-component vector type is a 4-component
vector type with the value in the <code>w</code> component undefined.</p>
</div>
<div class="paragraph">
<p>Some examples are given below:</p>
</div>
<div class="listingblock">
<div class="content">
<pre class="CodeRay highlight"><code data-lang="c">float8 vf;
float4 odd = vf.odd;
float4 even = vf.even;
float2 high = vf.even.hi;
float2 low = vf.odd.lo;
<span class="comment">// interleave LR stereo stream</span>
float4 left, right;
float8 interleaved;
interleaved.even = left;
interleaved.odd = right;
<span class="comment">// deinterleave</span>
left = interleaved.even;
right = interleaved.odd;
<span class="comment">// transpose a 4x4 matrix</span>
<span class="directive">void</span> transpose( float4 m[<span class="integer">4</span>] )
{
<span class="comment">// read matrix into a float16 vector</span>
float16 x = (float16)( m[<span class="integer">0</span>], m[<span class="integer">1</span>], m[<span class="integer">2</span>], m[<span class="integer">3</span>] );
float16 t;
<span class="comment">// transpose</span>
t.even = x.lo;
t.odd = x.hi;
x.even = t.lo;
x.odd = t.hi;
<span class="comment">// write back</span>
m[<span class="integer">0</span>] = x.lo.lo; <span class="comment">// { m[0][0], m[1][0], m[2][0], m[3][0] }</span>
m[<span class="integer">1</span>] = x.lo.hi; <span class="comment">// { m[0][1], m[1][1], m[2][1], m[3][1] }</span>
m[<span class="integer">2</span>] = x.hi.lo; <span class="comment">// { m[0][2], m[1][2], m[2][2], m[3][2] }</span>
m[<span class="integer">3</span>] = x.hi.hi; <span class="comment">// { m[0][3], m[1][3], m[2][3], m[3][3] }</span>
}
float3 vf = (float3)(<span class="float">1</span><span class="float">.0f</span>, <span class="float">2</span><span class="float">.0f</span>, <span class="float">3</span><span class="float">.0f</span>);
float2 low = vf.lo; <span class="comment">// (1.0f, 2.0f);</span>
float2 high = vf.hi; <span class="comment">// (3.0f, _undefined_);</span></code></pre>
</div>
</div>