ANGLE OpenCL Headers

The OpenCL headers ANGLE uses are the original headers from Khronos.

Updating headers

1. Clone https://github.com/KhronosGroup/OpenCL-Headers.git.
2. Inspect the differences between all headers from OpenCL-Headers/CL/ and this folder.
   • Changes of supported enums have to be updated in src/common/packed_cl_enums.json.
   • Changes of supported entry points have to be updated in src/libGLESv2/cl_stubs.cpp.
3. Copy all headers from OpenCL-Headers/CL/ over to this folder.