]>
Commit | Line | Data |
---|---|---|
7c673cae FG |
1 | ///////////////////////////////////////////////////////////////////////////// |
2 | // | |
3 | // (C) Copyright Ion Gaztanaga 2007-2013 | |
4 | // | |
5 | // Distributed under the Boost Software License, Version 1.0. | |
6 | // (See accompanying file LICENSE_1_0.txt or copy at | |
7 | // http://www.boost.org/LICENSE_1_0.txt) | |
8 | // | |
9 | // See http://www.boost.org/libs/intrusive for documentation. | |
10 | // | |
11 | ///////////////////////////////////////////////////////////////////////////// | |
12 | ||
13 | #ifndef BOOST_INTRUSIVE_POINTER_PLUS_BITS_HPP | |
14 | #define BOOST_INTRUSIVE_POINTER_PLUS_BITS_HPP | |
15 | ||
16 | #include <boost/intrusive/detail/config_begin.hpp> | |
17 | #include <boost/intrusive/intrusive_fwd.hpp> | |
18 | #include <boost/intrusive/detail/mpl.hpp> //ls_zeros | |
19 | #include <boost/intrusive/detail/assert.hpp> //BOOST_INTRUSIVE_INVARIANT_ASSERT | |
20 | ||
21 | #if defined(BOOST_HAS_PRAGMA_ONCE) | |
22 | # pragma once | |
23 | #endif | |
24 | ||
11fdf7f2 TL |
25 | |
26 | //GCC reports uninitialized values when an uninitialized pointer plus bits type | |
27 | //is asigned some bits or some pointer value, but that's ok, because we don't want | |
28 | //to default initialize parts that are not being updated. | |
29 | #if defined(BOOST_GCC) | |
30 | # if (BOOST_GCC >= 40600) | |
31 | # pragma GCC diagnostic push | |
32 | # pragma GCC diagnostic ignored "-Wuninitialized" | |
92f5a8d4 TL |
33 | # if (BOOST_GCC >= 40700) |
34 | # pragma GCC diagnostic ignored "-Wmaybe-uninitialized" | |
35 | # endif | |
11fdf7f2 TL |
36 | # endif |
37 | #endif | |
38 | ||
7c673cae FG |
39 | namespace boost { |
40 | namespace intrusive { | |
41 | ||
42 | //!This trait class is used to know if a pointer | |
43 | //!can embed extra bits of information if | |
44 | //!it's going to be used to point to objects | |
45 | //!with an alignment of "Alignment" bytes. | |
46 | template<class VoidPointer, std::size_t Alignment> | |
47 | struct max_pointer_plus_bits | |
48 | { | |
49 | static const std::size_t value = 0; | |
50 | }; | |
51 | ||
52 | //!This is a specialization for raw pointers. | |
53 | //!Raw pointers can embed extra bits in the lower bits | |
54 | //!if the alignment is multiple of 2pow(NumBits). | |
55 | template<std::size_t Alignment> | |
56 | struct max_pointer_plus_bits<void*, Alignment> | |
57 | { | |
58 | static const std::size_t value = detail::ls_zeros<Alignment>::value; | |
59 | }; | |
60 | ||
61 | //!This is class that is supposed to have static methods | |
62 | //!to embed extra bits of information in a pointer. | |
63 | //!This is a declaration and there is no default implementation, | |
64 | //!because operations to embed the bits change with every pointer type. | |
65 | //! | |
66 | //!An implementation that detects that a pointer type whose | |
67 | //!has_pointer_plus_bits<>::value is non-zero can make use of these | |
68 | //!operations to embed the bits in the pointer. | |
69 | template<class Pointer, std::size_t NumBits> | |
70 | struct pointer_plus_bits | |
71 | #ifdef BOOST_INTRUSIVE_DOXYGEN_INVOKED | |
72 | {} | |
73 | #endif | |
74 | ; | |
75 | ||
76 | //!This is the specialization to embed extra bits of information | |
77 | //!in a raw pointer. The extra bits are stored in the lower bits of the pointer. | |
78 | template<class T, std::size_t NumBits> | |
79 | struct pointer_plus_bits<T*, NumBits> | |
80 | { | |
81 | static const uintptr_t Mask = uintptr_t((uintptr_t(1u) << NumBits) - 1); | |
82 | typedef T* pointer; | |
83 | ||
84 | BOOST_INTRUSIVE_FORCEINLINE static pointer get_pointer(pointer n) | |
85 | { return pointer(uintptr_t(n) & uintptr_t(~Mask)); } | |
86 | ||
87 | BOOST_INTRUSIVE_FORCEINLINE static void set_pointer(pointer &n, pointer p) | |
88 | { | |
89 | BOOST_INTRUSIVE_INVARIANT_ASSERT(0 == (uintptr_t(p) & Mask)); | |
90 | n = pointer(uintptr_t(p) | (uintptr_t(n) & Mask)); | |
91 | } | |
92 | ||
93 | BOOST_INTRUSIVE_FORCEINLINE static std::size_t get_bits(pointer n) | |
94 | { return std::size_t(uintptr_t(n) & Mask); } | |
95 | ||
96 | BOOST_INTRUSIVE_FORCEINLINE static void set_bits(pointer &n, std::size_t c) | |
97 | { | |
98 | BOOST_INTRUSIVE_INVARIANT_ASSERT(uintptr_t(c) <= Mask); | |
99 | n = pointer(uintptr_t((get_pointer)(n)) | uintptr_t(c)); | |
100 | } | |
101 | }; | |
102 | ||
103 | } //namespace intrusive | |
104 | } //namespace boost | |
105 | ||
11fdf7f2 TL |
106 | #if defined(BOOST_GCC) && (BOOST_GCC >= 40600) |
107 | # pragma GCC diagnostic pop | |
108 | #endif | |
109 | ||
7c673cae FG |
110 | #include <boost/intrusive/detail/config_end.hpp> |
111 | ||
112 | #endif //BOOST_INTRUSIVE_POINTER_PLUS_BITS_HPP |