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 #include <boost/config.hpp>
30
31 namespace boost
32 {
33
34 namespace detail
35 {
36
atomic_exchange_and_add(int * pw,int dv)37 inline int atomic_exchange_and_add( int * pw, int dv )
38 {
39 // int r = *pw;
40 // *pw += dv;
41 // return r;
42
43 asm
44 {
45 mov esi, [pw]
46 mov eax, dv
47 lock xadd dword ptr [esi], eax
48 }
49 }
50
atomic_increment(int * pw)51 inline void atomic_increment( int * pw )
52 {
53 //atomic_exchange_and_add( pw, 1 );
54
55 asm
56 {
57 mov esi, [pw]
58 lock inc dword ptr [esi]
59 }
60 }
61
atomic_conditional_increment(int * pw)62 inline int atomic_conditional_increment( int * pw )
63 {
64 // int rv = *pw;
65 // if( rv != 0 ) ++*pw;
66 // return rv;
67
68 asm
69 {
70 mov esi, [pw]
71 mov eax, dword ptr [esi]
72 L0:
73 test eax, eax
74 je L1
75 mov ebx, eax
76 inc ebx
77 lock cmpxchg dword ptr [esi], ebx
78 jne L0
79 L1:
80 }
81 }
82
83 class BOOST_SYMBOL_VISIBLE sp_counted_base
84 {
85 private:
86
87 sp_counted_base( sp_counted_base const & );
88 sp_counted_base & operator= ( sp_counted_base const & );
89
90 int use_count_; // #shared
91 int weak_count_; // #weak + (#shared != 0)
92
93 public:
94
sp_counted_base()95 sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
96 {
97 }
98
~sp_counted_base()99 virtual ~sp_counted_base() // nothrow
100 {
101 }
102
103 // dispose() is called when use_count_ drops to zero, to release
104 // the resources managed by *this.
105
106 virtual void dispose() = 0; // nothrow
107
108 // destroy() is called when weak_count_ drops to zero.
109
destroy()110 virtual void destroy() // nothrow
111 {
112 delete this;
113 }
114
115 virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
116 virtual void * get_local_deleter( sp_typeinfo const & ti ) = 0;
117 virtual void * get_untyped_deleter() = 0;
118
add_ref_copy()119 void add_ref_copy()
120 {
121 atomic_increment( &use_count_ );
122 }
123
add_ref_lock()124 bool add_ref_lock() // true on success
125 {
126 return atomic_conditional_increment( &use_count_ ) != 0;
127 }
128
release()129 void release() // nothrow
130 {
131 if( atomic_exchange_and_add( &use_count_, -1 ) == 1 )
132 {
133 dispose();
134 weak_release();
135 }
136 }
137
weak_add_ref()138 void weak_add_ref() // nothrow
139 {
140 atomic_increment( &weak_count_ );
141 }
142
weak_release()143 void weak_release() // nothrow
144 {
145 if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 )
146 {
147 destroy();
148 }
149 }
150
use_count() const151 long use_count() const // nothrow
152 {
153 return static_cast<int const volatile &>( use_count_ );
154 }
155 };
156
157 } // namespace detail
158
159 } // namespace boost
160
161 #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED
162