OutputIterator inclusive_scan(InputIterator first, InputIterator last,
OutputIterator result, BinaryOperation bOp)
{
if (first != last) {
typename std::iterator_traits<InputIterator>::value_type init = *first;
*result++ = init;
if (++first != last)
return inclusive_scan(first, last, result, bOp, init);
}
return result;
}
cl::Buffer inclusive_scan(cl::Buffer input, size_t input_size)
{
if (block_size >= input_size) {
return small_array_scan(input, input_size);
} else {
cl::Buffer subblocks;
cl::Buffer last_elements;
std::tie(subblocks, last_elements) = subblock_scan(input, input_size);
cl::Buffer last_elements_scaned = inclusive_scan(last_elements, input_size / block_size);
return merge(subblocks, last_elements_scaned, input_size);
}
}
OutputIterator inclusive_scan(InputIterator first, InputIterator last,
OutputIterator result)
{
typedef typename std::iterator_traits<InputIterator>::value_type VT;
return inclusive_scan(first, last, result, std::plus<VT>());
}
int main()
{
try {
std::vector<cl::Device> devices;
// select platform
cl::Platform platform = selectPlatform();
// select device
platform.getDevices(CL_DEVICE_TYPE_ALL, &devices);
cl::Device device = selectDevice(devices);
// create context
context = cl::Context(devices);
// create command queue
queue = cl::CommandQueue(context, device, CL_QUEUE_PROFILING_ENABLE);
// load opencl source
std::ifstream cl_file("inclusive_scan.cl");
std::string cl_string{std::istreambuf_iterator<char>(cl_file),
std::istreambuf_iterator<char>()};
cl::Program::Sources source(1,
std::make_pair(cl_string.c_str(),
cl_string.length() + 1));
// create programm
program = cl::Program(context, source);
// compile opencl source
try {
program.build(devices);
size_t input_size;
std::ifstream input_file("input.txt");
input_file >> input_size;
std::vector<float> input(input_size);
// for (size_t i = 0; i < input_size; ++i) {
// input[i] = i % 10;
// }
for (int i = 0; i < input_size; i++) {
input_file >> input[i];
}
std::vector<float> output(input_size, 0);
cl::Buffer dev_input (context, CL_MEM_READ_ONLY, sizeof(float) * input_size);
queue.enqueueWriteBuffer(dev_input, CL_TRUE, 0, sizeof(float) * input_size, &input[0]);
cl::Buffer dev_output = inclusive_scan(dev_input, input_size);
queue.enqueueReadBuffer(dev_output, CL_TRUE, 0, sizeof(float) * input_size, &output[0]);
queue.finish();
cpu_check(input, output);
std::ofstream output_file("output.txt");
for (int i = 0; i < input_size; i++) {
output_file << output[i] << " ";
}
}
catch (cl::Error const & e) {
std::string log_str = program.getBuildInfo<CL_PROGRAM_BUILD_LOG>(device);
std::cout << std::endl << e.what() << " : " << e.err() << std::endl;
std::cout << log_str;
return 0;
}
}
catch (cl::Error const & e) {
std::cout << "Error: " << e.what() << " #" << e.err() << std::endl;
}
return 0;
}
