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materialPlotHelper.hpp
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1 // This file is part of the Acts project.
2 //
3 // Copyright (C) 2016-2019 CERN for the benefit of the Acts project
4 //
5 // This Source Code Form is subject to the terms of the Mozilla Public
6 // License, v. 2.0. If a copy of the MPL was not distributed with this
7 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 
9 #pragma once
10 
11 #include <cstdint>
12 #include <iosfwd>
13 
14 namespace Acts {
15 
27 class GeometryIdentifier {
28  public:
29  using Value = uint64_t;
30 
32  constexpr GeometryIdentifier(Value encoded) : m_value(encoded) {}
34  GeometryIdentifier() = default;
36  GeometryIdentifier(const GeometryIdentifier&) = default;
37  ~GeometryIdentifier() = default;
40 
42  constexpr Value value() const { return m_value; }
43 
45  constexpr Value volume() const { return getBits(volume_mask); }
47  constexpr Value boundary() const { return getBits(boundary_mask); }
49  constexpr Value layer() const { return getBits(layer_mask); }
51  constexpr Value approach() const { return getBits(approach_mask); }
53  constexpr Value sensitive() const { return getBits(sensitive_mask); }
54 
55  private:
56  // clang-format off
57  static constexpr Value volume_mask = 0xff00000000000000; // 255 volumes
58  static constexpr Value boundary_mask = 0x00ff000000000000; // 255 boundaries
59  static constexpr Value layer_mask = 0x0000fff000000000; // 4095 layers
60  static constexpr Value approach_mask = 0x0000000ff0000000; // 255 approach surfaces
61  static constexpr Value sensitive_mask = 0x000000000fffffff; // (2^28)-1 sensitive surfaces
62  // clang-format on
63 
64  Value m_value = 0;
65 
67  static constexpr int extractShift(Value mask) {
68  // use compiler builtin to extract the number of trailing bits from the
69  // mask. the builtin should be available on all supported compilers.
70  // need unsigned long long version (...ll) to ensure uint64_t compatibility.
71  // WARNING undefined behaviour for mask == 0 which we should not have.
72  return __builtin_ctzll(mask);
73  }
75  constexpr Value getBits(Value mask) const {
76  return (m_value & mask) >> extractShift(mask);
77  }
78 
79  friend constexpr bool operator==(GeometryIdentifier lhs,
81  return lhs.m_value == rhs.m_value;
82  }
83  friend constexpr bool operator<(GeometryIdentifier lhs,
85  return lhs.m_value < rhs.m_value;
86  }
87 };
88 
89 std::ostream& operator<<(std::ostream& os, GeometryIdentifier id);
90 
91 } // namespace Acts