1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
//---------------------------------------------------------------------------//
// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
//
// Distributed under the Boost Software License, Version 1.0
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
//
// See http://boostorg.github.com/compute for more information.
//---------------------------------------------------------------------------//
#include <iostream>
#include <boost/compute/function.hpp>
#include <boost/compute/system.hpp>
#include <boost/compute/algorithm/count_if.hpp>
#include <boost/compute/container/vector.hpp>
#include <boost/compute/iterator/buffer_iterator.hpp>
#include <boost/compute/random/default_random_engine.hpp>
#include <boost/compute/types/fundamental.hpp>
namespace compute = boost::compute;
int main()
{
// get default device and setup context
compute::device gpu = compute::system::default_device();
compute::context context(gpu);
compute::command_queue queue(context, gpu);
std::cout << "device: " << gpu.name() << std::endl;
using compute::uint_;
using compute::uint2_;
#ifdef CI_BUILD // lower number of points for CI builds
size_t n = 2000;
#else
// ten million random points
size_t n = 10000000;
#endif
// generate random numbers
compute::default_random_engine rng(queue);
compute::vector<uint_> vector(n * 2, context);
rng.generate(vector.begin(), vector.end(), queue);
// function returing true if the point is within the unit circle
BOOST_COMPUTE_FUNCTION(bool, is_in_unit_circle, (const uint2_ point),
{
const float x = point.x / (float) UINT_MAX - 1;
const float y = point.y / (float) UINT_MAX - 1;
return (x*x + y*y) < 1.0f;
});
// iterate over vector<uint> as vector<uint2>
compute::buffer_iterator<uint2_> start =
compute::make_buffer_iterator<uint2_>(vector.get_buffer(), 0);
compute::buffer_iterator<uint2_> end =
compute::make_buffer_iterator<uint2_>(vector.get_buffer(), vector.size() / 2);
// count number of random points within the unit circle
size_t count = compute::count_if(start, end, is_in_unit_circle, queue);
// print out values
float count_f = static_cast<float>(count);
std::cout << "count: " << count << " / " << n << std::endl;
std::cout << "ratio: " << count_f / float(n) << std::endl;
std::cout << "pi = " << (count_f / float(n)) * 4.0f << std::endl;
return 0;
}
|
