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SergiusAC/kernel_saxpy.cl

Created July 7, 2019 15:03
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kernel_saxpy.cl
__kernel void saxpy(__global float *x, __global float *y, float a)
{
const int i = get_global_id(0);
y[i] += a * x[i];
}
Raw
test_opencl.cpp
#define CL_TARGET_OPENCL_VERSION 110
#ifdef __APPLE__
#include <OpenCL/opencl.h>
#else
#include <CL/cl.h>
#endif
#include <vector>
#include <iostream>
#include <string>
#include <fstream>
std::string loadKernel(const char *name)
{
std::fstream fin(name);
std::string result(
(std::istreambuf_iterator<char>(fin)),
std::istreambuf_iterator<char>()
);
return result;
}
cl_program createProgram(const std::string &source, cl_context context)
{
size_t lengths[1] = { source.size() };
const char *sources[1] = { source.data() };
cl_int error = 0;
cl_program program = clCreateProgramWithSource(context, 1, sources, lengths, &error);
return program;
}
int main()
{
// Geting information about a platform and devices
cl_uint platformIdCount = 0;
clGetPlatformIDs(0, nullptr, &platformIdCount);
std::cout << "Number of platforms: " << platformIdCount << std::endl;
std::vector<cl_platform_id> platformIds(platformIdCount);
clGetPlatformIDs(platformIdCount, platformIds.data(), nullptr);
for (auto it = platformIds.begin(); it != platformIds.end(); it++) {
std::cout << *it << std::endl;
}
std::cout << std::endl;
cl_uint deviceIdCount = 0;
clGetDeviceIDs(platformIds[0], CL_DEVICE_TYPE_ALL, 0, nullptr, &deviceIdCount);
std::cout << "Number of devices: " << deviceIdCount << std::endl;
std::vector<cl_device_id> deviceIds(deviceIdCount);
clGetDeviceIDs(platformIds[0], CL_DEVICE_TYPE_ALL, deviceIdCount, deviceIds.data(), nullptr);
for (auto it = deviceIds.begin(); it != deviceIds.end(); it++) {
std::cout << *it << std::endl;
}
std::cout << std::endl;
// creating the context
cl_int error;
const cl_context_properties contextProperties[] = {
CL_CONTEXT_PLATFORM,
reinterpret_cast<cl_context_properties>(platformIds[0]),
0, 0
};
cl_context context = clCreateContext(
contextProperties, deviceIdCount, deviceIds.data(),
nullptr, nullptr, &error
);
// building program
cl_program program = createProgram(loadKernel("kernel_saxpy.cl"), context);
clBuildProgram(program, deviceIdCount, deviceIds.data(), nullptr, nullptr, nullptr);
// creating kernel
cl_kernel kernel = clCreateKernel(program, "saxpy", &error);
// creating buffers
static const size_t testDataSize = 10; // 2^10
std::vector<float> a(testDataSize), b(testDataSize);
int i = 1;
for (auto it = a.begin(); it != a.end(); it++) {
*it = i;
i++;
}
cl_mem aBuffer = clCreateBuffer(
context,
CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR,
sizeof(float) * testDataSize,
a.data(),
&error
);
cl_mem bBuffer = clCreateBuffer(
context,
CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR,
sizeof(float) * testDataSize,
b.data(),
&error
);
// creating command-queue
cl_command_queue queue = clCreateCommandQueue(context, deviceIds[0], 0, &error);
// we're ready to finally run code
clSetKernelArg(kernel, 0, sizeof(cl_mem), &aBuffer);
clSetKernelArg(kernel, 1, sizeof(cl_mem), &bBuffer);
static const float num = 2.0f;
clSetKernelArg(kernel, 2, sizeof(float), &num);
const size_t globalWorkSize[] = { testDataSize, 0, 0 };
clEnqueueNDRangeKernel(queue, kernel, 1, nullptr, globalWorkSize, nullptr, 0, nullptr, nullptr);
clEnqueueReadBuffer(queue, bBuffer, CL_TRUE, 0, sizeof(float) * testDataSize, b.data(), 0, nullptr, nullptr);
for (auto it = b.begin(); it != b.end(); it++) {
std::cout << *it << " ";
}
// release used resources
clReleaseCommandQueue(queue);
clReleaseMemObject(bBuffer);
clReleaseMemObject(aBuffer);
clReleaseKernel(kernel);
clReleaseProgram(program);
clReleaseContext(context);
}
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