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<!-- ================================ SYNOPSIS -->
<refnamediv id="clGetExtensionFunctionAddressForPlatform">
Returns the address of the extension function named by
<varname>funcname</varname> for a given <varname>platform</varname>.
<refsynopsisdiv xmlns:xlink=""><title></title>
<link xlink:href="scalarDataTypes.html">void*</link>
<link xlink:href="abstractDataTypes.html">cl_platform_id</link>
<link xlink:href="scalarDataTypes.html">char</link>
<!-- ================================ PARAMETERS -->
<refsect1 id="parameters">
<term> <varname> funcname </varname> </term>
<para> <!-- parameter description -->
Name of an extension function.
<!-- ================================ DESCRIPTION -->
<refsect1 id="description"><title>Description</title>
The function <function>clGetExtensionFunctionAddressForPlatform</function> returns
the address of the extension function named by <varname>funcname</varname> for a
given <varname>platform</varname>. The pointer returned should be cast to a function
pointer type matching the extension function's definition defined in the appropriate
extension specification and header file.
A return value of NULL indicates that the specified function does not exist for the
implementation or <varname>platform</varname> is not a valid platform. A non-NULL
return value for <function>clGetExtensionFunctionAddressForPlatform</function>
does not guarantee that an extension function is actually supported by
the platform. The application must also make a corresponding query using
(platform, <constant>CL_PLATFORM_EXTENSIONS</constant>, ... ) or
(device,<constant>CL_DEVICE_EXTENSIONS</constant>, ... ) to determine if an extension
is supported by the OpenCL implementation.
<function>clGetExtensionFunctionAddressForPlatform</function> may not be queried
for core (non-extension) functions in OpenCL. For functions that are queryable with
<function>clGetExtensionFunctionAddressForPlatform</function>, implementations may
choose to also export those functions statically from the object libraries implementing
those functions. However, portable applications cannot rely on this behavior.
Function pointer typedefs must be declared for all extensions that add API entrypoints.
These typedefs are a required part of the extension interface, to be provided in
an appropriate header (such as <code>cl_ext.h</code> if the extension is an OpenCL
extension, or <code>cl_gl_ext.h</code> if the extension is an OpenCL/OpenGL sharing
<!-- ================================ NOTES -->
<refsect1 id="notes"><title>Notes</title>
Since there is no way to qualify the query with a device, the function pointer
returned must work for all implementations of that extension on different devices
for a platform. The behavior of calling a device extension function on a device not
supporting that extension is undefined.
<!-- spec rev. 19 refers to clGetExtensionFunctionAddress() which does not exist -->
If the <citerefentry><refentrytitle>cl_khr_icd</refentrytitle></citerefentry>
extension is enabled, for functions supported by the ICD Loader,
will return the function pointer of the ICD Loader
implementation. For extension functions which the ICD
Loader is unaware of, the function
will determine the vendor
implementation to return based on the string passed in.
The ICD Loader will return the result from querying
on the vendor ICD enumerated by the ICD
Loader whose ICD suffix is a suffix of the function
name being queried. If no such vendor exists
or the suffix of the function is <code>KHR</code> or <code>EXT</code> then
will return NULL.
<!-- ================================ EXAMPLE -->
<refsect2 id="example1">
The following convention must be followed for all extensions affecting the host API,
where TAG can be <constant>KHR</constant>, <constant>EXT</constant> or vendor-specific:
<informaltable frame="none">
<tgroup cols="1" align="left" colsep="0" rowsep="0">
<colspec colname="col1" colnum="1" /> <tbody>
<entry>#ifndef extension_name
#define extension_name 1
// all data typedefs, token #defines, prototypes, and
// function pointer typedefs for this extension
// function pointer typedefs must use the
// following naming convention
typedef CL_API_ENTRY return type
(CL_API_CALL *clextension_func_nameTAG_fn)(...);
#endif // extension_name
Consider, for example, the
extension. This extension would add the following to <code>cl_gl_ext.h</code>:
<informaltable frame="none">
<tgroup cols="1" align="left" colsep="0" rowsep="0">
<colspec colname="col1" colnum="1" />
<entry>#ifndef cl_khr_gl_sharing
#define cl_khr_gl_sharing 1
// all data typedefs, token #defines, prototypes, and
// function pointer typedefs for this extension
#define CL_GL_CONTEXT_KHR 0x2008
#define CL_EGL_DISPLAY_KHR 0x2009
#define CL_GLX_DISPLAY_KHR 0x200A
#define CL_WGL_HDC_KHR 0x200B
// function pointer typedefs must use the
// following naming convention
typedef CL_API_ENTRY cl_int
(CL_API_CALL *clGetGLContextInfoKHR_fn)(
const cl_context_properties * /* properties */,
cl_gl_context_info /* param_name */,
size_t /* param_value_size */,
void * /* param_value */,
size_t * /*param_value_size_ret*/);
#endif // cl_khr_gl_sharing
<!-- ================================ SPECIFICATION -->
<!-- Set the "uri" attribute in the <olink /> element to the "named destination" for the PDF page
<refsect1 id="specification"><title>Specification</title>
<imagedata fileref="pdficon_small1.gif" format="gif" />
<olink uri="clGetExtensionFunctionAddressForPlatform">OpenCL Specification</olink>
<!-- ================================ ALSO SEE -->
<refsect1 id="seealso"><title>Also see</title>
<!-- ============================== COPYRIGHT -->
<!-- Content included from -->
<refsect3 id="Copyright"><title></title>
<imagedata fileref="KhronosLogo.jpg" format="jpg" />
<para />
<!-- 24-Dec-2013, rev. 19 -->