| 39 | /// \see scatter() |
| 40 | template<class Iterator> |
| 41 | inline void random_shuffle(Iterator first, |
| 42 | Iterator last, |
| 43 | command_queue &queue = system::default_queue()) |
| 44 | { |
| 45 | BOOST_STATIC_ASSERT(is_device_iterator<Iterator>::value); |
| 46 | typedef typename std::iterator_traits<Iterator>::value_type value_type; |
| 47 | |
| 48 | size_t count = detail::iterator_range_size(first, last); |
| 49 | if(count == 0){ |
| 50 | return; |
| 51 | } |
| 52 | |
| 53 | // generate shuffled indices on the host |
| 54 | std::vector<cl_uint> random_indices(count); |
| 55 | boost::iota(random_indices, 0); |
| 56 | #ifdef BOOST_COMPUTE_USE_CPP11 |
| 57 | std::random_device nondeterministic_randomness; |
| 58 | std::default_random_engine random_engine(nondeterministic_randomness()); |
| 59 | std::shuffle(random_indices.begin(), random_indices.end(), random_engine); |
| 60 | #else |
| 61 | std::random_shuffle(random_indices.begin(), random_indices.end()); |
| 62 | #endif |
| 63 | |
| 64 | // copy random indices to the device |
| 65 | const context &context = queue.get_context(); |
| 66 | vector<cl_uint> indices(count, context); |
| 67 | ::boost::compute::copy(random_indices.begin(), |
| 68 | random_indices.end(), |
| 69 | indices.begin(), |
| 70 | queue); |
| 71 | |
| 72 | // make a copy of the values on the device |
| 73 | vector<value_type> tmp(count, context); |
| 74 | ::boost::compute::copy(first, |
| 75 | last, |
| 76 | tmp.begin(), |
| 77 | queue); |
| 78 | |
| 79 | // write values to their new locations |
| 80 | ::boost::compute::scatter(tmp.begin(), |
| 81 | tmp.end(), |
| 82 | indices.begin(), |
| 83 | first, |
| 84 | queue); |
| 85 | } |
| 86 | |
| 87 | } // end compute namespace |
| 88 | } // end boost namespace |