Hello I have a very simple example program and I cannot find the mistake.
The global and offset arguments when I call enqueueNDRangeKernel are completely ignored. The get_global_id(0) always gives 0 to the local argument-1 (in this case 49). As I understand the Api, I thought I should get 30 to 79? Where is the problem?
#include <iostream>
#include <string>
const std::string kernelSource =
"__kernel void square ( __global float* A, const __global float* B, int N)
"
"{
"
" int i = get_global_id(0);
"
" if (i<100) A[i] = i;
"
"}
";
int main(int argc, char *argv[])
{
try {
std::vector<cl::Platform> platforms;
cl_int N = 100;
std::vector<cl::Device> devices;
cl::Platform::get(&platforms);
platforms.begin()->getDevices(CL_DEVICE_TYPE_ALL, & devices);
cl::Context context(devices);
cl::Device& device = devices.front();
cl::CommandQueue cmdqueue(context, device);
cl::Buffer inputBuffer(context, CL_MEM_READ_WRITE, 200 * sizeof(cl_float));
cl::Buffer outputBuffer(context, CL_MEM_READ_WRITE, 200 * sizeof(cl_float));
cl_float inputs[200],outputs[200];
for (int i=0;i<100;i++){
inputs[i] = i;
outputs[i] = 0;
}
cmdqueue.enqueueWriteBuffer(inputBuffer, true, 0, 200*sizeof(cl_float),inputs);
cmdqueue.finish();
cl::Program::Sources sourceCode;
sourceCode.push_back(std::make_pair(kernelSource.c_str(),kernelSource.size()));
cl::Program program = cl::Program(context, sourceCode);
program.build(devices);
cl::Kernel kernel(program, "square");
kernel.setArg(0, outputBuffer);
kernel.setArg(1, inputBuffer);
kernel.setArg(2,N);
cl::Event event;
cmdqueue.enqueueNDRangeKernel(kernel,cl::NDRange(30),cl::NDRange(50), cl::NDRange(25),NULL,&event);
event.wait();
cmdqueue.enqueueReadBuffer(outputBuffer, true, 0, 200*sizeof(cl_float),outputs);
cmdqueue.finish();
for (int i=0;i<100;i++){
std::cout << outputs[i] << std::endl;
}
}
catch (cl::Error& err) {
std::cerr << "OpenCL error: " << err.what() << "(" << err.err() << ")" << std::endl;
return 1;
}
}