AlpakaInterface/interface/alpakastdAlgorithm.h

0001 #ifndef HeterogeneousCore_AlpakaInterface_interface_alpakastdAlgorithm_h
0002 #define HeterogeneousCore_AlpakaInterface_interface_alpakastdAlgorithm_h
0003
0004 #include <algorithm>
0005 #include <functional>
0006 #include <utility>
0007
0008 #include <alpaka/alpaka.hpp>
0009
0010 // reimplementation of std algorithms able to work on device code
0011
0012 namespace alpaka_std {
0013
0014   template <typename RandomIt, typename T, typename Compare = std::less<T>>
0015   ALPAKA_FN_HOST_ACC constexpr RandomIt lower_bound(RandomIt first, RandomIt last, const T &value, Compare comp = {}) {
0016     auto count = last - first;
0017
0018     while (count > 0) {
0019       auto it = first;
0020       auto step = count / 2;
0021       it += step;
0022       if (comp(*it, value)) {
0023         first = ++it;
0024         count -= step + 1;
0025       } else {
0026         count = step;
0027       }
0028     }
0029     return first;
0030   }
0031
0032   template <typename RandomIt, typename T, typename Compare = std::less<T>>
0033   ALPAKA_FN_HOST_ACC constexpr RandomIt upper_bound(RandomIt first, RandomIt last, const T &value, Compare comp = {}) {
0034     auto count = last - first;
0035
0036     while (count > 0) {
0037       auto it = first;
0038       auto step = count / 2;
0039       it += step;
0040       if (!comp(value, *it)) {
0041         first = ++it;
0042         count -= step + 1;
0043       } else {
0044         count = step;
0045       }
0046     }
0047     return first;
0048   }
0049
0050 }  // namespace alpaka_std
0051
0052 #endif  // HeterogeneousCore_AlpakaInterface_interface_alpakastdAlgorithm_h