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1 | #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED |
2 | #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED | |
3 | ||
4 | // MS compatible compilers support #pragma once | |
5 | ||
6 | #if defined(_MSC_VER) && (_MSC_VER >= 1020) | |
7 | # pragma once | |
8 | #endif | |
9 | ||
10 | // | |
11 | // detail/sp_counted_base_cw_x86.hpp - CodeWarrion on 486+ | |
12 | // | |
13 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. | |
14 | // Copyright 2004-2005 Peter Dimov | |
15 | // Copyright 2005 Rene Rivera | |
16 | // | |
17 | // Distributed under the Boost Software License, Version 1.0. (See | |
18 | // accompanying file LICENSE_1_0.txt or copy at | |
19 | // http://www.boost.org/LICENSE_1_0.txt) | |
20 | // | |
21 | // | |
22 | // Lock-free algorithm by Alexander Terekhov | |
23 | // | |
24 | // Thanks to Ben Hitchings for the #weak + (#shared != 0) | |
25 | // formulation | |
26 | // | |
27 | ||
28 | #include <boost/detail/sp_typeinfo.hpp> | |
29 | ||
30 | namespace boost | |
31 | { | |
32 | ||
33 | namespace detail | |
34 | { | |
35 | ||
36 | inline int atomic_exchange_and_add( int * pw, int dv ) | |
37 | { | |
38 | // int r = *pw; | |
39 | // *pw += dv; | |
40 | // return r; | |
41 | ||
42 | asm | |
43 | { | |
44 | mov esi, [pw] | |
45 | mov eax, dv | |
46 | lock xadd dword ptr [esi], eax | |
47 | } | |
48 | } | |
49 | ||
50 | inline void atomic_increment( int * pw ) | |
51 | { | |
52 | //atomic_exchange_and_add( pw, 1 ); | |
53 | ||
54 | asm | |
55 | { | |
56 | mov esi, [pw] | |
57 | lock inc dword ptr [esi] | |
58 | } | |
59 | } | |
60 | ||
61 | inline int atomic_conditional_increment( int * pw ) | |
62 | { | |
63 | // int rv = *pw; | |
64 | // if( rv != 0 ) ++*pw; | |
65 | // return rv; | |
66 | ||
67 | asm | |
68 | { | |
69 | mov esi, [pw] | |
70 | mov eax, dword ptr [esi] | |
71 | L0: | |
72 | test eax, eax | |
73 | je L1 | |
74 | mov ebx, eax | |
75 | inc ebx | |
76 | lock cmpxchg dword ptr [esi], ebx | |
77 | jne L0 | |
78 | L1: | |
79 | } | |
80 | } | |
81 | ||
82 | class sp_counted_base | |
83 | { | |
84 | private: | |
85 | ||
86 | sp_counted_base( sp_counted_base const & ); | |
87 | sp_counted_base & operator= ( sp_counted_base const & ); | |
88 | ||
89 | int use_count_; // #shared | |
90 | int weak_count_; // #weak + (#shared != 0) | |
91 | ||
92 | public: | |
93 | ||
94 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) | |
95 | { | |
96 | } | |
97 | ||
98 | virtual ~sp_counted_base() // nothrow | |
99 | { | |
100 | } | |
101 | ||
102 | // dispose() is called when use_count_ drops to zero, to release | |
103 | // the resources managed by *this. | |
104 | ||
105 | virtual void dispose() = 0; // nothrow | |
106 | ||
107 | // destroy() is called when weak_count_ drops to zero. | |
108 | ||
109 | virtual void destroy() // nothrow | |
110 | { | |
111 | delete this; | |
112 | } | |
113 | ||
114 | virtual void * get_deleter( sp_typeinfo const & ti ) = 0; | |
115 | virtual void * get_untyped_deleter() = 0; | |
116 | ||
117 | void add_ref_copy() | |
118 | { | |
119 | atomic_increment( &use_count_ ); | |
120 | } | |
121 | ||
122 | bool add_ref_lock() // true on success | |
123 | { | |
124 | return atomic_conditional_increment( &use_count_ ) != 0; | |
125 | } | |
126 | ||
127 | void release() // nothrow | |
128 | { | |
129 | if( atomic_exchange_and_add( &use_count_, -1 ) == 1 ) | |
130 | { | |
131 | dispose(); | |
132 | weak_release(); | |
133 | } | |
134 | } | |
135 | ||
136 | void weak_add_ref() // nothrow | |
137 | { | |
138 | atomic_increment( &weak_count_ ); | |
139 | } | |
140 | ||
141 | void weak_release() // nothrow | |
142 | { | |
143 | if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 ) | |
144 | { | |
145 | destroy(); | |
146 | } | |
147 | } | |
148 | ||
149 | long use_count() const // nothrow | |
150 | { | |
151 | return static_cast<int const volatile &>( use_count_ ); | |
152 | } | |
153 | }; | |
154 | ||
155 | } // namespace detail | |
156 | ||
157 | } // namespace boost | |
158 | ||
159 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED |