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<keyword>Data Types</keyword>
<refentrytitle>Data Types</refentrytitle>
<holder>The Khronos Group Inc.
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<!-- ================================ SYNOPSIS -->
<refnamediv id="DataTypes">
<refname>Data Types</refname>
OpenCL data types.
<!-- ================================ DESCRIPTION -->
<refsect1 id="description"><title>Description</title>
These are the data types available in the OpenCL C programming language. Click on a
category name in the table below to see information about specific data types.
<informaltable frame="all">
<tgroup cols="2" align="left" colsep="1" rowsep="1">
<colspec colname="col1" colnum="1" />
<colspec colname="col2" colnum="2" />
<entry>Data type category</entry>
<entry>Included data types</entry>
<citerefentry href="scalarDataTypes"><refentrytitle>Scalar data types</refentrytitle></citerefentry>
<type>bool</type>, <type>char</type>, <type>cl_char</type>,
<type>unsigned char</type>, <type>uchar</type>, <type>cl_uchar</type>,
<type>short</type>, <type>cl_short</type>, <type>unsigned short</type>,
<type>ushort</type>, <type>int</type>, <type>unsigned int</type>,
<type>uint</type>, <type>long</type>, <type>unsigned long</type>,
<type>ulong</type>, <type>float</type>, <type>half</type>, <type>size_t</type>,
<type>ptrdiff_t</type>, <type>intptr_t</type>, <type>uintptr_t</type>,
<type>void</type>, <type>double</type>, and <type>half</type> floating point types.
<citerefentry href="vectorDataTypes"><refentrytitle>Vector data types</refentrytitle></citerefentry>
<type>char<replaceable>n</replaceable></type>, <type>uchar<replaceable>n</replaceable></type>,
<type>short<replaceable>n</replaceable></type>, <type>ushort<replaceable>n</replaceable></type>,
<type>int<replaceable>n</replaceable></type>, <type>uint<replaceable>n</replaceable></type>,
<type>long<replaceable>n</replaceable></type>, <type>ulong<replaceable>n</replaceable></type>,
<type>float<replaceable>n</replaceable></type>, double<replaceable>n</replaceable>, and optional half<replaceable>n</replaceable> types.
<citerefentry href="abstractDataTypes"><refentrytitle>Abstract data types</refentrytitle></citerefentry>
<type>cl_platform_id</type>, <type>cl_device_id</type>,
<type>cl_context</type>, <type>cl_command_queue</type>,
<type>cl_mem</type>, <type>cl_program</type>,
<type>cl_kernel</type>, <type>cl_event</type>, and
<citerefentry href="reservedDataTypes"><refentrytitle>Reserved Data Types</refentrytitle></citerefentry>
<type>half<replaceable>n</replaceable></type>, <type>quad</type>,
<type>complex half</type>, <type>complex half<replaceable>n</replaceable></type>,
<type>imaginary half</type>, <type>imaginary half<replaceable>n</replaceable></type>,
<type>complex float</type>, <type>complex float<replaceable>n</replaceable></type>,
<type>imaginary float</type>, <type>imaginary float<replaceable>n</replaceable></type>,
<type>complex double</type>, <type>complex double<replaceable>n</replaceable></type>,
<type>imaginary double</type>, <type>imaginary double<replaceable>n</replaceable></type>,
<type>complex quad</type>, <type>complex quad<replaceable>n</replaceable></type>,
<type>imaginary quad</type>, <type>imaginary quad<replaceable>n</replaceable></type>,
<type>long double</type>, <type>long double<replaceable>n</replaceable></type>,
<type>long long</type>, <type>long long<replaceable>n</replaceable></type>,
<type>unsigned long long</type>, <type>ulong long</type>, and
<type>ulong long<replaceable>n</replaceable></type>.
<citerefentry href="otherDataTypes"><refentrytitle>Other data types</refentrytitle></citerefentry>
<type>image2d_t</type>, <type>image3d_t</type>, <type>image2d_array_t</type>,
<type>image1d_t</type>, <type>image31_buffer_t</type>, <type>image1d_array_t</type>,
<type>sampler_t</type>, and <type>event_t</type>.
<!-- ================================ NOTES -->
<refsect1 id="notes"><title>Alignment of Types</title>
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 <type>float4</type> variable will be aligned to a
16-byte boundary, and a <type>char2</type> variable will be aligned to a 2-byte boundary.
For 3-component vector data types, the size of the data type is 4 *
sizeof(component). This means that a 3-component vector data type
will be aligned to a 4 * sizeof(component) boundary. The <citerefentry
href="vloadn"><refentrytitle>vload3</refentrytitle></citerefentry> and <citerefentry
href="vstoren"><refentrytitle>vstore3</refentrytitle></citerefentry> built-in functions
can be used to read and write, respectively, 3-component vector data types from an
array of packed scalar data type.
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 <code>structs</code>
or <code>unions</code>.
The OpenCL compiler is responsible for aligning data items to the appropriate
alignment as required by the data type. For arguments to a <citerefentry
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 <citerefentry><refentrytitle>vloadn</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>vstoren</refentrytitle></citerefentry>, and
<citerefentry><refentrytitle>vstore_halfn</refentrytitle></citerefentry> functions. 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.
The user is responsible for ensuring that data passed into and out of OpenCL buffers are
natively aligned relative to the start of the buffer as described above. This implies
that OpenCL buffers created with <constant>CL_MEM_USE_HOST_PTR</constant> need to provide
an appropriately aligned host memory pointer that is aligned to the data types used to
access these buffers in a kernel(s). As well, the user is responsible to ensure that
data passed into and out of OpenCL images are properly aligned to the granularity of
the data representing a single pixel (e.g. <varname>image_num_channels</varname>
* sizeof(<varname>image_channel_data_type</varname>)) except for
<constant>CL_RGB</constant> and <constant>CL_RGBx</constant> images where
the data must be aligned to the granularity of a single channel in a pixel
(i.e. sizeof(<varname>image_channel_data_type</varname>)).
OpenCL makes no requirement about the alignment of OpenCL application defined data
types outside of buffers and images, except that the underlying vector primitives (e.g.
<type>__cl_float4</type>) where defined shall be directly accessible as such
using appropriate named fields in the <constant>cl_type</constant> union. Nevertheless,
it is recommended that the <code>cl_platform.h</code> header should attempt to
naturally align OpenCL defined application data types (e.g. <type>cl_float4</type>)
according to their type.
<!-- ================================ SPECIFICATION -->
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<refsect1 id="specification"><title>Specification</title>
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<olink uri="scalarDataTypes">OpenCL Specification</olink>
<!-- ================================ ALSO SEE
<refsect1 id="seealso"><title>Also see</title>
</refsect1> -->
<!-- ============================== COPYRIGHT -->
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<refsect3 id="Copyright"><title></title>
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<!-- 17-Oct-2011 -->