Open3D (C++ API)  0.12.0
ParallelScan.h
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26 
27 #pragma once
28 
29 #include <tbb/parallel_for.h>
30 
31 #include "tbb/parallel_scan.h"
32 #if TBB_INTERFACE_VERSION >= 10000
33 #include "pstl/execution"
34 #include "pstl/numeric"
35 #endif
36 
37 namespace open3d {
38 namespace utility {
39 
40 namespace {
41 template <class Tin, class Tout>
42 class ScanSumBody {
43  Tout sum;
44  const Tin* in;
45  Tout* const out;
46 
47 public:
48  ScanSumBody(Tout* out_, const Tin* in_) : sum(0), in(in_), out(out_) {}
49  Tout get_sum() const { return sum; }
50 
51  template <class Tag>
52  void operator()(const tbb::blocked_range<size_t>& r, Tag) {
53  Tout temp = sum;
54  for (size_t i = r.begin(); i < r.end(); ++i) {
55  temp = temp + in[i];
56  if (Tag::is_final_scan()) out[i] = temp;
57  }
58  sum = temp;
59  }
60  ScanSumBody(ScanSumBody& b, tbb::split) : sum(0), in(b.in), out(b.out) {}
61  void reverse_join(ScanSumBody& a) { sum = a.sum + sum; }
62  void assign(ScanSumBody& b) { sum = b.sum; }
63 };
64 } // namespace
65 
66 template <class Tin, class Tout>
67 void InclusivePrefixSum(const Tin* first, const Tin* last, Tout* out) {
68 #if TBB_INTERFACE_VERSION >= 10000
69  // use parallelstl if we have TBB 2018 or later
70  std::inclusive_scan(pstl::execution::par_unseq, first, last, out);
71 #else
72  ScanSumBody<Tin, Tout> body(out, first);
73  size_t n = std::distance(first, last);
74  tbb::parallel_scan(tbb::blocked_range<size_t>(0, n), body);
75 #endif
76 }
77 
78 } // namespace utility
79 } // namespace open3d
void InclusivePrefixSum(const Tin *first, const Tin *last, Tout *out)
Definition: ParallelScan.h:67
Definition: PinholeCameraIntrinsic.cpp:35