Skip to content

Latest commit

 

History

History
86 lines (64 loc) · 2.62 KB

3.7-chinese.md

File metadata and controls

86 lines (64 loc) · 2.62 KB

#3.7 OpenCL C++ Wapper向量加法

Khronos组织也在后续的OpenCL标准中定义了一套C++ Wapper API。C++ API与C API是对应的(比如，cl::Memory对应cl_mem)，不过C++需要对异常和类进行处理。下面的代码对应的与代码清单3.4中的C代码相对应。

{%ace edit=false, lang='c_cpp'%} #define __CL_ENABLE_EXCEPTIONS

#include <CL/cl.hpp> #include #include #include #include

int main(){ const int elements = 2048; size_t datasize = sizeof(int) * elements;

int *A = new int[elements]; int *B = new int[elements]; int *C = new int[elements];

for (int i = 0; i < elements; i++){ A[i] = i; B[i] = i; }

try{ // Query for platforms std::vectorcl::Platform platforms; cl::Platform::get(&platforms);

// Get a list of devices on this platform
std::vector<cl::Device> devices;

platforms[0].getDevices(CL_DEVICE_TYPE_ALL, &devices);

// Create a context for the devices
cl::Context context(devices);

// Create a command-queue for the first device
cl::CommandQueue queue = cl::CommandQueue(context, devices[0]);

// Create the memory buffers
cl::Buffer bufferA = cl::Buffer(context, CL_MEM_READ_ONLY, datasize);
cl::Buffer bufferB = cl::Buffer(context, CL_MEM_READ_ONLY, datasize);
cl::Buffer bufferC = cl::Buffer(context, CL_MEM_WRITE_ONLY, datasize);

// Copy the input data to the input buffers using the
// command-queue for the first device
queue.enqueueWriteBuffer(bufferA, CL_TRUE, 0, datasize, A);
queue.enqueueWriteBuffer(bufferB, CL_TRUE, 0, datasize, B);

// Read the program source
std::ifstream sourceFile("vector_add_kernel.cl");
std::string sourceCode(std::istreambuf_iterator<char>(sourceFile), (std::istreambuf_iterator<char>()));
cl::Program::Source source(1, std::make_pair(sourceCode.c_str(), sourceCode.length() + 1);

// Create the program from the source code
cl::Program program = cl::Program(context, source);

// Build the program for the devices
program.build(devices);

// Create the kernel
cl::Kernel vecadd_kernel(program, "vecadd");

// Set the kernel arguments
vecadd_kernel.setArg(0, bufferA);
vecadd_kernel.setArg(1, bufferB);
vecadd_kernel.setArg(2, bufferC);

// Execute the kernel
cl::NDRange gloabl(elements);
cl::NDRange local(256);

queue.enqueueNDRangeKernel(vecadd_kernel, cl::NullRange, gloabl, local);

// Copy the output data back to the host
queue.enqueueReadBuffer(bufferC, CL_TRUE, 0, datasize, C);

} catch(cl::Error error){ std::cout << error.what() << "(" << error.err() << ")" << std::endl; } } {%endace%}

代码清单3.5 使用C++ Wapper实现的OpenCL向量相加