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OpenCL Bindings

How to use new OpenCL binding mechanism.

As a step towards the extension mechanism I needed a way to easily bind OpenCL to an interface.

Here is what I have come up with. We will use the ‘Square’ example.

You first define an interface with OpenCL annotations..


        interface Squarer extends OpenCL<Squarer>{
        @Kernel("{\n"//
             + "  const size_t id = get_global_id(0);\n"//
             + "  out[id] = in[id]*in[id];\n"//
             + "}\n")//
        public Squarer square(//
             Range _range,//
             @GlobalReadOnly("in") float[] in,//
             @GlobalWriteOnly("out") float[] out);
        }
        

This describes the API we wish to bind to a set of kernel entrypoints (here we only have one, but we could have many). Then you 'realize’ the interface by asking a device to create an implementation of the interface. Device is a new Aparapi class which represents a GPU or CPU OpenCL device. So here we are asking for the first (default) GPU device to realize the interface.


        Squarer squarer = Device.firstGPU(Squarer.class);
        

Now you can call the implementation directly with a Range.


        squarer.square(Range.create(in.length), in, out);
        

I think that we will have the easiest OpenCL binding out there…

Following some conversations/suggestions online http://a-hackers-craic.blogspot.com/2012/03/aparapi.html we could also offer the ability to provide the OpenCL source from a file/url course using interface level Annotations.

So we could allow.


        @OpenCL.Resource("squarer.cl");
        interface Squarer extends OpenCL<Squarer>{
             public Squarer square(//
               Range _range,//
               @GlobalReadOnly("in") float[] in,//
               @GlobalWriteOnly("out") float[] out);
        }
        

Or if the text is on-hand at compile time in a single constant string


        @OpenCL.Source("... opencl text here");
        interface Squarer extends OpenCL<Squarer>{
             public Squarer square(//
               Range _range,//
               @GlobalReadOnly("in") float[] in,//
               @GlobalWriteOnly("out") float[] out);
        }
        

Finally to allow for creation of dynamic OpenCL (good for FFT’s of various Radii).


        String openclSource = ...;
        Squarer squarer = Device.firstGPU(Squarer.class, openclSource);