/*
 * JOCL - Java bindings for OpenCL
 *
 * Copyright 2009 Marco Hutter - http://www.jocl.org/
 */

package jocltest;

import static org.jocl.CL.*;

import org.jocl.*;

/**
 * A small JOCL sample.
 */
public class JOCLSample
{
    /**
     * The source code of the OpenCL program to execute
     */
    static int n = 1;
    static int tot = 20000000;
    static int m = tot/n;

    private static String programSource =
        "__kernel void "+
        "sampleKernel(__global const float *a,"+
        "             __global const float *b,"+
        "             __global float *c)"+
        "{"+
        "    int gid = get_global_id(0);"+
        "    float res = 0.0f;"+
        "    for (int i=0; i<"+m+"; i++) {"+
        "        res+=tanh(0.5596853f+i*0.001f+a[gid]);"+
        "    }"+
        "    c[gid]=res;"+
        "}";


    /**
     * The entry point of this sample
     *
     * @param args Not used
     */
    public static void main(String args[])
    {
        // Create input- and output data
        float srcArrayA[] = new float[n];
        float srcArrayB[] = new float[n];
        float dstArray[] = new float[n];
        for (int i=0; i<n; i++)
        {
            srcArrayA[i] = i;
            srcArrayB[i] = i;
        }
        long timestart = System.currentTimeMillis();
        Pointer srcA = Pointer.to(srcArrayA);
        Pointer srcB = Pointer.to(srcArrayB);
        Pointer dst = Pointer.to(dstArray);

        // The platform, device type and device number
        // that will be used
        final int platformIndex = 0;
        final long deviceType = CL_DEVICE_TYPE_ALL;
        final int deviceIndex = 0;

        // Enable exceptions and subsequently omit error checks in this sample
        CL.setExceptionsEnabled(true);

        // Obtain the number of platforms
        int numPlatformsArray[] = new int[1];
        clGetPlatformIDs(0, null, numPlatformsArray);
        int numPlatforms = numPlatformsArray[0];

        // Obtain a platform ID
        cl_platform_id platforms[] = new cl_platform_id[numPlatforms];
        clGetPlatformIDs(platforms.length, platforms, null);
        cl_platform_id platform = platforms[platformIndex];

        // Initialize the context properties
        cl_context_properties contextProperties = new cl_context_properties();
        contextProperties.addProperty(CL_CONTEXT_PLATFORM, platform);

        // Obtain the number of devices for the platform
        int numDevicesArray[] = new int[1];
        clGetDeviceIDs(platform, deviceType, 0, null, numDevicesArray);
        int numDevices = numDevicesArray[0];

        // Obtain a device ID
        cl_device_id devices[] = new cl_device_id[numDevices];
        clGetDeviceIDs(platform, deviceType, numDevices, devices, null);
        cl_device_id device = devices[deviceIndex];

        // Create a context for the selected device
        cl_context context = clCreateContext(
            contextProperties, 1, new cl_device_id[]{device},
            null, null, null);

        // Create a command-queue for the selected device
        cl_command_queue commandQueue =
            clCreateCommandQueue(context, device, 0, null);

        // Allocate the memory objects for the input- and output data
        cl_mem memObjects[] = new cl_mem[3];
        memObjects[0] = clCreateBuffer(context,
            CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR,
            Sizeof.cl_float * n, srcA, null);
        memObjects[1] = clCreateBuffer(context,
            CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR,
            Sizeof.cl_float * n, srcB, null);
        memObjects[2] = clCreateBuffer(context,
            CL_MEM_READ_WRITE,
            Sizeof.cl_float * n, null, null);

        // Create the program from the source code
        cl_program program = clCreateProgramWithSource(context,
            1, new String[]{ programSource }, null, null);

        // Build the program
        clBuildProgram(program, 0, null, null, null, null);

        // Create the kernel
        cl_kernel kernel = clCreateKernel(program, "sampleKernel", null);

        // Set the arguments for the kernel
        clSetKernelArg(kernel, 0,
            Sizeof.cl_mem, Pointer.to(memObjects[0]));
        clSetKernelArg(kernel, 1,
            Sizeof.cl_mem, Pointer.to(memObjects[1]));
        clSetKernelArg(kernel, 2,
            Sizeof.cl_mem, Pointer.to(memObjects[2]));

        // Set the work-item dimensions
        long global_work_size[] = new long[]{n};
        long local_work_size[] = new long[]{1};

        // Execute the kernel
        clEnqueueNDRangeKernel(commandQueue, kernel, 1, null,
            global_work_size, local_work_size, 0, null, null);

        // Read the output data
        clEnqueueReadBuffer(commandQueue, memObjects[2], CL_TRUE, 0,
            n * Sizeof.cl_float, dst, 0, null, null);

        // Release kernel, program, and memory objects
        clReleaseMemObject(memObjects[0]);
        clReleaseMemObject(memObjects[1]);
        clReleaseMemObject(memObjects[2]);
        clReleaseKernel(kernel);
        clReleaseProgram(program);
        clReleaseCommandQueue(commandQueue);
        clReleaseContext(context);

        // Verify the result
        long timemid = System.currentTimeMillis();
        //System.out.println(n);
        double res = 0;
        for (int i=0; i<n; i++)
        {
            for (int k=0; k<m; k++) res+=Math.tan(0.5596853+i*0.001+srcArrayA[i]);
        }
        long timeend = System.currentTimeMillis();
        System.out.println("res="+res);
        System.out.println("GPU time: "+(timemid-timestart)+" ms");
        System.out.println("CPU time: "+(timeend-timemid)+" ms");
    }
}