Tpetra parallel linear algebra Version of the Day
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Tpetra_Details_get1DConstView.hpp
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41
42#ifndef TPETRA_DETAILS_GET1DCONSTVIEW_HPP
43#define TPETRA_DETAILS_GET1DCONSTVIEW_HPP
44
49
50#include "Tpetra_ConfigDefs.hpp"
51#include "Tpetra_Util.hpp"
52#include "Kokkos_DualView.hpp"
53#include <Teuchos_Array.hpp>
54#include <utility>
55
56namespace Tpetra {
57namespace Details {
58
59// mfh 28 Apr 2016: Sometimes we have a raw host array, and we need
60// to make a Kokkos::View out of it that lives in a certain memory
61// space. We don't want to make a deep copy of the input array if
62// we don't need to, but if the memory spaces are different, we need
63// to. The following code does that. The struct is an
64// implementation detail, and the "free" function
65// get1DConstViewOfUnmanagedArray is the interface to call.
66
67template<class ST, class DT,
68 const bool outputIsHostMemory =
69 std::is_same<typename DT::memory_space, Kokkos::HostSpace>::value>
70struct Get1DConstViewOfUnmanagedHostArray {};
71
72template<class ST, class DT>
73struct Get1DConstViewOfUnmanagedHostArray<ST, DT, true> {
74 typedef Kokkos::View<const ST*, Kokkos::HostSpace, Kokkos::MemoryUnmanaged> output_view_type;
75
76 static output_view_type
77 getView (const char /* label */ [], const ST* x_raw, const size_t x_len)
78 {
79 // We can return the input array, wrapped as an unmanaged View.
80 // Ignore the label, since unmanaged Views don't have labels.
81 return output_view_type (x_raw, x_len);
82 }
83};
84
85template<class ST, class DT>
86struct Get1DConstViewOfUnmanagedHostArray<ST, DT, false> {
87 typedef Kokkos::View<const ST*, Kokkos::HostSpace, Kokkos::MemoryUnmanaged> input_view_type;
88 typedef Kokkos::View<const ST*, DT> output_view_type;
89
90 static output_view_type
91 getView (const char label[], const ST* x_raw, const size_t x_len)
92 {
93 input_view_type x_in (x_raw, x_len);
94 // The memory spaces are different, so we have to create a new
95 // View which is a deep copy of the input array.
96 //
97 // FIXME (mfh 28 Apr 2016) This needs to be converted to
98 // std::string, else the compiler can't figure out what
99 // constructor we're calling.
100 Kokkos::View<ST*, DT> x_out (std::string (label), x_len);
101 // DEEP_COPY REVIEW - NOT TESTED
102 Kokkos::deep_copy (x_out, x_in);
103 return x_out;
104 }
105};
106
107template<class ST, class DT>
108 typename Get1DConstViewOfUnmanagedHostArray<ST, DT>::output_view_type
109get1DConstViewOfUnmanagedHostArray (const char label[], const ST* x_raw, const size_t x_len)
110{
111 return Get1DConstViewOfUnmanagedHostArray<ST, DT>::getView (label, x_raw, x_len);
112}
113
114} // namespace Details
115} // namespace Tpetra
116
117#endif // TPETRA_DETAILS_GET1DCONSTVIEW_HPP
Stand-alone utility functions and macros.
Implementation details of Tpetra.
Namespace Tpetra contains the class and methods constituting the Tpetra library.