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    <title>clGetExtensionFunctionAddressForPlatform</title>
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    <div class="refentry">
      <a id="id-1"></a>
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      <div xmlns="" class="refnamediv">
        <a xmlns="http://www.w3.org/1999/xhtml" id="clGetExtensionFunctionAddressForPlatform"></a>
        <h1>clGetExtensionFunctionAddressForPlatform</h1>
        <p>
            Returns the address of the extension function named by
            <code xmlns="http://www.w3.org/1999/xhtml" class="varname">funcname</code> for a given <code xmlns="http://www.w3.org/1999/xhtml" class="varname">platform</code>.
        </p>
      </div>
      <div class="refsynopsisdiv">
        <h2></h2>
        <div class="funcsynopsis">
          <table xmlns="" border="0" summary="Function synopsis" cellspacing="0" cellpadding="0">
            <tr valign="bottom">
              <td>
                <code xmlns="http://www.w3.org/1999/xhtml" class="funcdef">
                   <a class="link" href="scalarDataTypes.html" target="pagedisplay">void*</a>
                    <strong class="fsfunc">
                        clGetExtensionFunctionAddressForPlatform
                    </strong>
                (</code>
                <td>
                    <a xmlns="http://www.w3.org/1999/xhtml" class="link" href="abstractDataTypes.html" target="pagedisplay">cl_platform_id</a>
                     <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">platform</var>
                , </td>
              </td>
            </tr>
            <tr valign="top">
              <td> </td>
              <td>const
                    <a xmlns="http://www.w3.org/1999/xhtml" class="link" href="scalarDataTypes.html" target="pagedisplay">char</a>
                     <var xmlns="http://www.w3.org/1999/xhtml" class="pdparam">*funcname</var>
               <code>)</code></td>
            </tr>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="parameters"></a>
        <h2>Parameters</h2>
        <div class="variablelist">
          <dl class="variablelist">
            <dt>
              <span class="term"> <code class="varname"> funcname </code> </span>
            </dt>
            <dd>
              <p> 
                        Name of an extension function.
                    </p>
            </dd>
          </dl>
        </div>
      </div>
      <div class="refsect1">
        <a id="description"></a>
        <h2>Description</h2>
        <p>
          The function <code class="function">clGetExtensionFunctionAddressForPlatform</code> returns
          the address of the extension function named by <code class="varname">funcname</code> for a
          given <code class="varname">platform</code>. 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.
        </p>
        <p>
          A return value of NULL indicates that the specified function does not exist for the
          implementation or <code class="varname">platform</code> is not a valid platform.  A non-NULL
          return value for <code class="function">clGetExtensionFunctionAddressForPlatform</code>
          does not guarantee that an extension function is actually supported by
          the platform. The application must also make a corresponding query using
          <a class="citerefentry" href="clGetPlatformInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetPlatformInfo</span></span></a>
          (platform, <code class="constant">CL_PLATFORM_EXTENSIONS</code>, ... ) or
          <a class="citerefentry" href="clGetDeviceInfo.html"><span class="citerefentry"><span class="refentrytitle">clGetDeviceInfo</span></span></a>
          (device,<code class="constant">CL_DEVICE_EXTENSIONS</code>, ... ) to determine if an extension
          is supported by the OpenCL implementation.
        </p>
        <p>
          <code class="function">clGetExtensionFunctionAddressForPlatform</code> may not be queried
          for core (non-extension) functions in OpenCL. For functions that are queryable with
          <code class="function">clGetExtensionFunctionAddressForPlatform</code>, implementations may
          choose to also export those functions statically from the object libraries implementing
          those functions. However, portable applications cannot rely on this behavior.
        </p>
        <p>
          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 class="code">cl_ext.h</code> if the extension is an OpenCL
          extension, or <code class="code">cl_gl_ext.h</code> if the extension is an OpenCL/OpenGL sharing
          extension).
        </p>
      </div>
      <div class="refsect1">
        <a id="notes"></a>
        <h2>Notes</h2>
        <p>
          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.
        </p>
        <p>
            
            If the <a class="citerefentry" href="cl_khr_icd.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_icd</span></span></a>
            extension is enabled, for functions supported by the ICD Loader, 
            <code class="function">clGetExtensionFunctionAddress</code> 
            will return the function pointer of the ICD Loader 
            implementation. For extension functions which the ICD
            Loader is unaware of, the function 
            <code class="function">clGetExtensionFunctionAddress</code> 
            will determine the vendor 
            implementation to return based on the string passed in. 
            The ICD Loader will return the result from querying 
            <code class="function">clGetExtensionFunctionAddress</code> 
            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 class="code">KHR</code> or <code class="code">EXT</code> then 
            <code class="function">clGetExtensionFunctionAddress</code> 
            will return NULL.
        </p>
      </div>
      <div class="refsect2">
        <a id="example1"></a>
        <h3>
            Example
        </h3>
        <p>
          The following convention must be followed for all extensions affecting the host API,
          where TAG can be <code class="constant">KHR</code>, <code class="constant">EXT</code> or vendor-specific:
        </p>
        <div class="informaltable">
          <table class="informaltable" border="0">
            <colgroup>
              <col align="left" class="col1" />
            </colgroup>
            <tbody>
              <tr>
                <td align="left">#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
                        </td>
              </tr>
            </tbody>
          </table>
        </div>
        <p>
            Consider, for example, the 
            <a class="citerefentry" href="cl_khr_gl_sharing.html"><span class="citerefentry"><span class="refentrytitle">cl_khr_gl_sharing</span></span></a> 
            extension. This extension would add the following to <code class="code">cl_gl_ext.h</code>:
        </p>
        <div class="informaltable">
          <table class="informaltable" border="0">
            <colgroup>
              <col align="left" class="col1" />
            </colgroup>
            <tbody>
              <tr>
                <td align="left">#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_INVALID_GL_SHAREGROUP_REFERENCE_KHR -1000
#define CL_CURRENT_DEVICE_FOR_GL_CONTEXT_KHR   0x2006
#define CL_DEVICES_FOR_GL_CONTEXT_KHR          0x2007
#define CL_GL_CONTEXT_KHR                      0x2008
#define CL_EGL_DISPLAY_KHR                     0x2009
#define CL_GLX_DISPLAY_KHR                     0x200A
#define CL_WGL_HDC_KHR                         0x200B
#define CL_CGL_SHAREGROUP_KHR                  0x200C

// 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
                        </td>
              </tr>
            </tbody>
          </table>
        </div>
      </div>
      <div class="refsect1">
        <a id="specification"></a>
        <h2>Specification</h2>
        <p>
            <img src="pdficon_small1.gif" />

            <a href="https://www.khronos.org/registry/cl/specs/opencl-2.1-extensions.pdf#namedest=clGetExtensionFunctionAddressForPlatform" target="OpenCL Spec">OpenCL Specification</a>
        </p>
      </div>
      <div class="refsect1">
        <a id="seealso"></a>
        <h2>Also see</h2>
        <p>
            <a class="citerefentry" href="EXTENSION.html"><span class="citerefentry"><span class="refentrytitle">EXTENSION</span></span></a>
        </p>
      </div>
      <div xmlns="" class="refsect3" lang="en" xml:lang="en"><a xmlns="http://www.w3.org/1999/xhtml" id="Copyright"></a><h4 xmlns="http://www.w3.org/1999/xhtml"></h4><img xmlns="http://www.w3.org/1999/xhtml" src="KhronosLogo.jpg" /><p xmlns="http://www.w3.org/1999/xhtml"></p>Copyright © 2007-2015 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
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