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#include <thrust/copy.h>
#include <thrust/device_vector.h>
#include <thrust/fill.h>
#include <thrust/functional.h>
#include <thrust/iterator/counting_iterator.h>
#include <thrust/iterator/permutation_iterator.h>
#include <thrust/iterator/transform_iterator.h>
#include <iostream>
#include "include/host_device.h"
// this example illustrates how to make repeated access to a range of values
// examples:
// repeated_range([0, 1, 2, 3], 1) -> [0, 1, 2, 3]
// repeated_range([0, 1, 2, 3], 2) -> [0, 0, 1, 1, 2, 2, 3, 3]
// repeated_range([0, 1, 2, 3], 3) -> [0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3]
// ...
template <typename Iterator>
class repeated_range
{
public:
typedef typename thrust::iterator_difference<Iterator>::type difference_type;
struct repeat_functor : public thrust::unary_function<difference_type, difference_type>
{
difference_type repeats;
repeat_functor(difference_type repeats)
: repeats(repeats)
{}
__host__ __device__ difference_type operator()(const difference_type& i) const
{
return i / repeats;
}
};
typedef typename thrust::counting_iterator<difference_type> CountingIterator;
typedef typename thrust::transform_iterator<repeat_functor, CountingIterator> TransformIterator;
typedef typename thrust::permutation_iterator<Iterator, TransformIterator> PermutationIterator;
// type of the repeated_range iterator
typedef PermutationIterator iterator;
// construct repeated_range for the range [first,last)
repeated_range(Iterator first, Iterator last, difference_type repeats)
: first(first)
, last(last)
, repeats(repeats)
{}
iterator begin() const
{
return PermutationIterator(first, TransformIterator(CountingIterator(0), repeat_functor(repeats)));
}
iterator end() const
{
return begin() + repeats * (last - first);
}
protected:
Iterator first;
Iterator last;
difference_type repeats;
};
int main()
{
thrust::device_vector<int> data(4);
data[0] = 10;
data[1] = 20;
data[2] = 30;
data[3] = 40;
// print the initial data
std::cout << "range ";
thrust::copy(data.begin(), data.end(), std::ostream_iterator<int>(std::cout, " "));
std::cout << std::endl;
typedef thrust::device_vector<int>::iterator Iterator;
// create repeated_range with elements repeated twice
repeated_range<Iterator> twice(data.begin(), data.end(), 2);
std::cout << "repeated x2: ";
thrust::copy(twice.begin(), twice.end(), std::ostream_iterator<int>(std::cout, " "));
std::cout << std::endl;
// create repeated_range with elements repeated x3
repeated_range<Iterator> thrice(data.begin(), data.end(), 3);
std::cout << "repeated x3: ";
thrust::copy(thrice.begin(), thrice.end(), std::ostream_iterator<int>(std::cout, " "));
std::cout << std::endl;
return 0;
}
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