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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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<keyword>Data Types</keyword>
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<refentrytitle>Data Types</refentrytitle>
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<year>2007-2010</year>
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<holder>The Khronos Group Inc.
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Permission is hereby granted, free of charge, to any person obtaining a
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copy of this software and/or associated documentation files (the
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"Materials"), to deal in the Materials without restriction, including
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without limitation the rights to use, copy, modify, merge, publish,
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distribute, sublicense, and/or sell copies of the Materials, and to
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permit persons to whom the Materials are furnished to do so, subject to
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the condition that this copyright notice and permission notice shall be included
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in all copies or substantial portions of the Materials.</holder>
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<manvolnum>3</manvolnum>
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<!-- ================================ SYNOPSIS -->
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<refnamediv id="DataTypes">
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<refname>Data Types</refname>
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<!-- ================================ DESCRIPTION -->
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<refsect1 id="description"><title>Description</title>
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These are the data types available in the OpenCL C programming language. Click on a
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category name in the table below to see information about specific data types.
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<informaltable frame="all">
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<tgroup cols="2" align="left" colsep="1" rowsep="1">
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<colspec colname="col1" colnum="1" />
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<colspec colname="col2" colnum="2" />
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<entry>Data type category</entry>
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<entry>Included data types</entry>
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<citerefentry href="scalarDataTypes"><refentrytitle>Scalar data types</refentrytitle></citerefentry>
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<type>bool</type>, <type>char</type>, <type>cl_char</type>,
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<type>unsigned char</type>, <type>uchar</type>, <type>cl_uchar</type>,
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<type>short</type>, <type>cl_short</type>, <type>unsigned short</type>,
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<type>ushort</type>, <type>int</type>, <type>unsigned int</type>,
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<type>uint</type>, <type>long</type>, <type>unsigned long</type>,
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<type>ulong</type>, <type>float</type>, <type>half</type>, <type>size_t</type>,
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<type>ptrdiff_t</type>, <type>intptr_t</type>, <type>uintptr_t</type>,
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<type>void</type>, <type>double</type>, and <type>half</type> floating point types.
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<citerefentry href="vectorDataTypes"><refentrytitle>Vector data types</refentrytitle></citerefentry>
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<type>char<replaceable>n</replaceable></type>, <type>uchar<replaceable>n</replaceable></type>,
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<type>short<replaceable>n</replaceable></type>, <type>ushort<replaceable>n</replaceable></type>,
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<type>int<replaceable>n</replaceable></type>, <type>uint<replaceable>n</replaceable></type>,
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<type>long<replaceable>n</replaceable></type>, <type>ulong<replaceable>n</replaceable></type>,
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<type>float<replaceable>n</replaceable></type>, double<replaceable>n</replaceable>, and optional half<replaceable>n</replaceable> types.
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<citerefentry href="abstractDataTypes"><refentrytitle>Abstract data types</refentrytitle></citerefentry>
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<type>cl_platform_id</type>, <type>cl_device_id</type>,
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<type>cl_context</type>, <type>cl_command_queue</type>,
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<type>cl_mem</type>, <type>cl_program</type>,
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<type>cl_kernel</type>, <type>cl_event</type>, and
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<type>cl_sampler</type>.
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<citerefentry href="reservedDataTypes"><refentrytitle>Reserved Data Types</refentrytitle></citerefentry>
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<type>bool<replaceable>n</replaceable></type>,
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<type>half<replaceable>n</replaceable></type>, <type>quad</type>,
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<type>quad<replaceable>n</replaceable></type>,
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<type>complex half</type>, <type>complex half<replaceable>n</replaceable></type>,
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<type>imaginary half</type>, <type>imaginary half<replaceable>n</replaceable></type>,
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<type>complex float</type>, <type>complex float<replaceable>n</replaceable></type>,
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<type>imaginary float</type>, <type>imaginary float<replaceable>n</replaceable></type>,
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<type>complex double</type>, <type>complex double<replaceable>n</replaceable></type>,
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<type>imaginary double</type>, <type>imaginary double<replaceable>n</replaceable></type>,
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<type>complex quad</type>, <type>complex quad<replaceable>n</replaceable></type>,
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<type>imaginary quad</type>, <type>imaginary quad<replaceable>n</replaceable></type>,
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<type>float<replaceable>n</replaceable></type>x<emphasis>m</emphasis>,
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<type>double<replaceable>n</replaceable></type>x<emphasis>m</emphasis>,
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<type>long double</type>, <type>long double<replaceable>n</replaceable></type>,
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<type>long long</type>, <type>long long<replaceable>n</replaceable></type>,
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<type>unsigned long long</type>, <type>ulong long</type>, and
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<type>ulong long<replaceable>n</replaceable></type>.
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<citerefentry href="otherDataTypes"><refentrytitle>Other data types</refentrytitle></citerefentry>
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<type>image2d_t</type>, <type>image3d_t</type>, <type>image2d_array_t</type>,
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<type>image1d_t</type>, <type>image31_buffer_t</type>, <type>image1d_array_t</type>,
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<type>sampler_t</type>, and <type>event_t</type>.
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<!-- ================================ NOTES -->
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<refsect1 id="notes"><title>Alignment of Types</title>
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A data item declared to be a data type in memory is always aligned to the size of the
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data type in bytes. For example, a <type>float4</type> variable will be aligned to a
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16-byte boundary, and a <type>char2</type> variable will be aligned to a 2-byte boundary.
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For 3-component vector data types, the size of the data type is 4 *
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sizeof(component). This means that a 3-component vector data type
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will be aligned to a 4 * sizeof(component) boundary. The <citerefentry
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href="vloadn"><refentrytitle>vload3</refentrytitle></citerefentry> and <citerefentry
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href="vstoren"><refentrytitle>vstore3</refentrytitle></citerefentry> built-in functions
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can be used to read and write, respectively, 3-component vector data types from an
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array of packed scalar data type.
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A built-in data type that is not a power of two bytes in size must be aligned to the next
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larger power of two. This rule applies to built-in types only, not <code>structs</code>
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or <code>unions</code>.
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The OpenCL compiler is responsible for aligning data items to the appropriate
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alignment as required by the data type. For arguments to a <citerefentry
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href="functionQualifiers"><refentrytitle>__kernel</refentrytitle></citerefentry>
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function declared to be a pointer to a data type, the OpenCL compiler can
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assume that the pointee is always appropriately aligned as required by the
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data type. The behavior of an unaligned load or store is undefined, except
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for the <citerefentry><refentrytitle>vloadn</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>vload_halfn</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>vstoren</refentrytitle></citerefentry>, and
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<citerefentry><refentrytitle>vstore_halfn</refentrytitle></citerefentry> functions. The
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vector load functions can read a vector from an address aligned to the element type
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of the vector. The vector store functions can write a vector to an address aligned
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to the element type of the vector.
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The user is responsible for ensuring that data passed into and out of OpenCL buffers are
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natively aligned relative to the start of the buffer as described above. This implies
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that OpenCL buffers created with <constant>CL_MEM_USE_HOST_PTR</constant> need to provide
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an appropriately aligned host memory pointer that is aligned to the data types used to
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access these buffers in a kernel(s). As well, the user is responsible to ensure that
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data passed into and out of OpenCL images are properly aligned to the granularity of
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the data representing a single pixel (e.g. <varname>image_num_channels</varname>
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* sizeof(<varname>image_channel_data_type</varname>)) except for
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<constant>CL_RGB</constant> and <constant>CL_RGBx</constant> images where
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the data must be aligned to the granularity of a single channel in a pixel
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(i.e. sizeof(<varname>image_channel_data_type</varname>)).
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OpenCL makes no requirement about the alignment of OpenCL application defined data
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types outside of buffers and images, except that the underlying vector primitives (e.g.
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<type>__cl_float4</type>) where defined shall be directly accessible as such
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using appropriate named fields in the <constant>cl_type</constant> union. Nevertheless,
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it is recommended that the <code>cl_platform.h</code> header should attempt to
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naturally align OpenCL defined application data types (e.g. <type>cl_float4</type>)
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according to their type.
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<!-- ================================ SPECIFICATION -->
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<!-- Set the "uri" attribute in the <olink /> element to the "named destination" for the PDF page
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<refsect1 id="specification"><title>Specification</title>
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<imagedata fileref="pdficon_small1.gif" format="gif" />
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<olink uri="scalarDataTypes">OpenCL Specification</olink>
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<!-- ================================ ALSO SEE
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<refsect1 id="seealso"><title>Also see</title>
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<citerefentry><refentrytitle>cl_khr_fp64</refentrytitle></citerefentry>
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<!-- ============================== COPYRIGHT -->
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<!-- Content included from copyright.inc.xsl -->
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<refsect3 id="Copyright"><title></title>
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