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| == Getting Started == | | == Getting Started == |
| Hello JOCL host program:
| | [[JOCL_Tutorial|Hello JOCL]] |
| <pre>
| |
| import com.jogamp.opencl.*;
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| import java.io.IOException;
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| import java.nio.FloatBuffer;
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| import java.util.Random;
| |
| | |
| import static java.lang.System.*;
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| import static com.jogamp.opencl.CLMemory.Mem.*;
| |
| | |
| /**
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| * Hello Java OpenCL example. Adds all elements of buffer A to buffer B
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| * and stores the result in buffer C.<br/>
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| * Sample was inspired by the Nvidia VectorAdd example written in C/C++
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| * which is bundled in the Nvidia OpenCL SDK.
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| * @author Michael Bien
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| */
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| public class HelloJOCL {
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| | |
| public static void main(String[] args) throws IOException {
| |
| | |
| int elementCount = 11444777; // Length of arrays to process
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| int localWorkSize = 256; // Local work size
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| int globalWorkSize = roundUp(localWorkSize, elementCount); // rounded up to the nearest multiple of the localWorkSize
| |
| | |
| // set up
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| CLContext context = CLContext.create();
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| CLProgram program = context.createProgram(HelloJOCL.class.getResourceAsStream("VectorAdd.cl")).build();
| |
| | |
| CLBuffer<FloatBuffer> clBufferA = context.createFloatBuffer(globalWorkSize, READ_ONLY);
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| CLBuffer<FloatBuffer> clBufferB = context.createFloatBuffer(globalWorkSize, READ_ONLY);
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| CLBuffer<FloatBuffer> clBufferC = context.createFloatBuffer(globalWorkSize, WRITE_ONLY);
| |
| | |
| // fill read buffers with random numbers.
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| fillBuffer(clBufferA.getBuffer(), 12345);
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| fillBuffer(clBufferB.getBuffer(), 67890);
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| | |
| // get a reference to the kernel functon with the name 'VectorAdd'
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| // and map the buffers to its input parameters.
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| CLKernel kernel = program.createCLKernel("VectorAdd");
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| kernel.putArgs(clBufferA, clBufferB, clBufferC).putArg(elementCount);
| |
| | |
| // create command queue on fastest device.
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| CLCommandQueue queue = context.getMaxFlopsDevice().createCommandQueue();
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| | |
| // asynchronous write of data to GPU device,
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| // blocking read later to get the computed results back.
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| long time = nanoTime();
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| queue.putWriteBuffer(clBufferA, false)
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| .putWriteBuffer(clBufferB, false)
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| .put1DRangeKernel(kernel, 0, globalWorkSize, localWorkSize)
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| .putReadBuffer(clBufferC, true);
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| time = nanoTime() - time;
| |
| | |
| // cleanup all resources associated with this context.
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| context.release();
| |
| | |
| // print first few elements of the resulting buffer to the console.
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| out.println("a+b=c results snapshot: ");
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| for(int i = 0; i < 10; i++)
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| out.print(clBufferC.getBuffer().get() + ", ");
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| out.println("...; " + clBufferC.getBuffer().remaining() + " more");
| |
| | |
| out.println("computation took: "+(time/1000000)+"ms");
| |
| }
| |
| | |
| /* utilities */
| |
| private static void fillBuffer(FloatBuffer buffer, int seed) {
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| Random rnd = new Random(seed);
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| while(buffer.remaining() != 0)
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| buffer.put(rnd.nextFloat()*100);
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| buffer.rewind();
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| }
| |
| | |
| private static int roundUp(int groupSize, int globalSize) {
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| int r = globalSize % groupSize;
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| if (r == 0) return globalSize;
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| else return globalSize + groupSize - r;
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| }
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| }
| |
| </pre>
| |
| Hello JOCL Kernel: | |
| <pre>
| |
| // OpenCL Kernel Function for element by element vector addition
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| kernel void VectorAdd(global const float* a, global const float* b, global float* c, int numElements) {
| |
| | |
| // get index into global data array
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| int iGID = get_global_id(0);
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| | |
| // bound check, equivalent to the limit on a 'for' loop
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| if (iGID >= numElements) {
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| return;
| |
| }
| |
| | |
| // add the vector elements
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| c[iGID] = a[iGID] + b[iGID];
| |
| }
| |
| </pre>
| |
Get the Source Code
The project repository is located on github.
You can create a local copy/branch of the git repository,
either anonymous:
or via SSH and your user credential, so you can easily push back your
changes to the github server:
- git clone git@github.com:username/gluegen.git gluegen
- git clone git@github.com:username/jocl.git jocl
- git clone git@github.com:username/jocl-demos.git jocl-demos
- git clone git@github.com:username/jogl.git jogl
Build Dependencies
GlueGen, JOGL
JDK6, ANT 1.8
Getting Started
Hello JOCL