ceph/src/boost/libs/compute/example/simple_kernel.cpp

   1 //---------------------------------------------------------------------------//
   2 // Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
   3 //
   4 // Distributed under the Boost Software License, Version 1.0
   5 // See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt
   7 //
   8 // See http://boostorg.github.com/compute for more information.
   9 //---------------------------------------------------------------------------//
  10
  11 #include <iostream>
  12
  13 #include <boost/compute/core.hpp>
  14
  15 namespace compute = boost::compute;
  16
  17 // this example demonstrates how to use the Boost.Compute classes to
  18 // setup and run a simple vector addition kernel on the GPU
  19 int main()
  20 {
  21     // get the default device
  22     compute::device device = compute::system::default_device();
  23
  24     // create a context for the device
  25     compute::context context(device);
  26
  27     // setup input arrays
  28     float a[] = { 1, 2, 3, 4 };
  29     float b[] = { 5, 6, 7, 8 };
  30
  31     // make space for the output
  32     float c[] = { 0, 0, 0, 0 };
  33
  34     // create memory buffers for the input and output
  35     compute::buffer buffer_a(context, 4 * sizeof(float));
  36     compute::buffer buffer_b(context, 4 * sizeof(float));
  37     compute::buffer buffer_c(context, 4 * sizeof(float));
  38
  39     // source code for the add kernel
  40     const char source[] =
  41         "__kernel void add(__global const float *a,"
  42         "                  __global const float *b,"
  43         "                  __global float *c)"
  44         "{"
  45         "    const uint i = get_global_id(0);"
  46         "    c[i] = a[i] + b[i];"
  47         "}";
  48
  49     // create the program with the source
  50     compute::program program =
  51         compute::program::create_with_source(source, context);
  52
  53     // compile the program
  54     program.build();
  55
  56     // create the kernel
  57     compute::kernel kernel(program, "add");
  58
  59     // set the kernel arguments
  60     kernel.set_arg(0, buffer_a);
  61     kernel.set_arg(1, buffer_b);
  62     kernel.set_arg(2, buffer_c);
  63
  64     // create a command queue
  65     compute::command_queue queue(context, device);
  66
  67     // write the data from 'a' and 'b' to the device
  68     queue.enqueue_write_buffer(buffer_a, 0, 4 * sizeof(float), a);
  69     queue.enqueue_write_buffer(buffer_b, 0, 4 * sizeof(float), b);
  70
  71     // run the add kernel
  72     queue.enqueue_1d_range_kernel(kernel, 0, 4, 0);
  73
  74     // transfer results back to the host array 'c'
  75     queue.enqueue_read_buffer(buffer_c, 0, 4 * sizeof(float), c);
  76
  77     // print out results in 'c'
  78     std::cout << "c: [" << c[0] << ", "
  79                         << c[1] << ", "
  80                         << c[2] << ", "
  81                         << c[3] << "]" << std::endl;
  82
  83     return 0;
  84 }