1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_PPC_HPP_INCLUDED
2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_PPC_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_ppc.hpp - CodeWarrior on PowerPC
12 //
13 // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
14 // Copyright 2004-2005 Peter Dimov
15 //
16 // Distributed under the Boost Software License, Version 1.0. (See
17 // accompanying file LICENSE_1_0.txt or copy at
18 // http://www.boost.org/LICENSE_1_0.txt)
19 //
20 //
21 // Lock-free algorithm by Alexander Terekhov
22 //
23 // Thanks to Ben Hitchings for the #weak + (#shared != 0)
24 // formulation
25 //
26
27 #include <boost/detail/sp_typeinfo.hpp>
28
29 namespace boost
30 {
31
32 namespace detail
33 {
34
atomic_increment(register long * pw)35 inline void atomic_increment( register long * pw )
36 {
37 register int a;
38
39 asm
40 {
41 loop:
42
43 lwarx a, 0, pw
44 addi a, a, 1
45 stwcx. a, 0, pw
46 bne- loop
47 }
48 }
49
atomic_decrement(register long * pw)50 inline long atomic_decrement( register long * pw )
51 {
52 register int a;
53
54 asm
55 {
56 sync
57
58 loop:
59
60 lwarx a, 0, pw
61 addi a, a, -1
62 stwcx. a, 0, pw
63 bne- loop
64
65 isync
66 }
67
68 return a;
69 }
70
atomic_conditional_increment(register long * pw)71 inline long atomic_conditional_increment( register long * pw )
72 {
73 register int a;
74
75 asm
76 {
77 loop:
78
79 lwarx a, 0, pw
80 cmpwi a, 0
81 beq store
82
83 addi a, a, 1
84
85 store:
86
87 stwcx. a, 0, pw
88 bne- loop
89 }
90
91 return a;
92 }
93
94 class sp_counted_base
95 {
96 private:
97
98 sp_counted_base( sp_counted_base const & );
99 sp_counted_base & operator= ( sp_counted_base const & );
100
101 long use_count_; // #shared
102 long weak_count_; // #weak + (#shared != 0)
103
104 public:
105
sp_counted_base()106 sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
107 {
108 }
109
~sp_counted_base()110 virtual ~sp_counted_base() // nothrow
111 {
112 }
113
114 // dispose() is called when use_count_ drops to zero, to release
115 // the resources managed by *this.
116
117 virtual void dispose() = 0; // nothrow
118
119 // destroy() is called when weak_count_ drops to zero.
120
destroy()121 virtual void destroy() // nothrow
122 {
123 delete this;
124 }
125
126 virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
127 virtual void * get_local_deleter( sp_typeinfo const & ti ) = 0;
128 virtual void * get_untyped_deleter() = 0;
129
add_ref_copy()130 void add_ref_copy()
131 {
132 atomic_increment( &use_count_ );
133 }
134
add_ref_lock()135 bool add_ref_lock() // true on success
136 {
137 return atomic_conditional_increment( &use_count_ ) != 0;
138 }
139
release()140 void release() // nothrow
141 {
142 if( atomic_decrement( &use_count_ ) == 0 )
143 {
144 dispose();
145 weak_release();
146 }
147 }
148
weak_add_ref()149 void weak_add_ref() // nothrow
150 {
151 atomic_increment( &weak_count_ );
152 }
153
weak_release()154 void weak_release() // nothrow
155 {
156 if( atomic_decrement( &weak_count_ ) == 0 )
157 {
158 destroy();
159 }
160 }
161
use_count() const162 long use_count() const // nothrow
163 {
164 return static_cast<long const volatile &>( use_count_ );
165 }
166 };
167
168 } // namespace detail
169
170 } // namespace boost
171
172 #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_PPC_HPP_INCLUDED
173