Description

Function pointer typedefs should be declared for all extensions that add API entrypoints. These typedefs are a required part of the extension interface, and should be provided in an appropriate header, such as cl_ext.h.

The following convention should be followed for all extensions affecting the host API:

#define cl_extension_name 1
#define CL_EXTENSION_NAME_NAME "cl_extension_name"

#define CL_EXTENSION_NAME_VERSION CL_MAKE_VERSION(major, minor, patch)

// all data typedefs and token #defines for this extension
#define CL_EXTENSION_ENUM_NAME_TAG    0xXXXX

// function types for extension functions
typedef return_type
clExtensionFunctionNameTAG_t(...);

// function pointer typedefs for extension functions
typedef clExtensionFunctionNameTAG_t *
clExtensionFunctionNameTAG_fn;

// extension function prototypes (optional)
extern return_type
clExtensionFunctionTAG(...);

where TAG can be KHR, EXT or vendor-specific.

Consider, for example, the cl_khr_create_command_queue extension. This extension adds the following to cl_ext.h:

#define cl_khr_create_command_queue 1
#define CL_KHR_CREATE_COMMAND_QUEUE_EXTENSION_NAME \
    "cl_khr_create_command_queue"

#define CL_KHR_CREATE_COMMAND_QUEUE_EXTENSION_VERSION CL_MAKE_VERSION(1, 0, 0)

typedef cl_properties       cl_queue_properties_khr;

typedef cl_command_queue CL_API_CALL
clCreateCommandQueueWithPropertiesKHR_t(
    cl_context context,
    cl_device_id device,
    const cl_queue_properties_khr* properties,
    cl_int* errcode_ret);

typedef clCreateCommandQueueWithPropertiesKHR_t *
clCreateCommandQueueWithPropertiesKHR_fn CL_API_SUFFIX__VERSION_1_2;

#if !defined(CL_NO_NON_ICD_DISPATCH_EXTENSION_PROTOTYPES)

extern CL_API_ENTRY cl_command_queue CL_API_CALL
clCreateCommandQueueWithPropertiesKHR(
    cl_context context,
    cl_device_id device,
    const cl_queue_properties_khr* properties,
    cl_int* errcode_ret) CL_API_SUFFIX__VERSION_1_2;

#endif /* !defined(CL_NO_NON_ICD_DISPATCH_EXTENSION_PROTOTYPES) */

See Also

No cross-references are available

Document Notes

For more information, see the OpenCL Specification

This page is extracted from the OpenCL Specification. Fixes and changes should be made to the Specification, not directly.

Copyright

Copyright 2014-2026 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0