1 #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
2 #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
3
4 //
5 // detail/sp_counted_base_vacpp_ppc.hpp - xlC(vacpp) on POWER
6 // based on: detail/sp_counted_base_w32.hpp
7 //
8 // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
9 // Copyright 2004-2005 Peter Dimov
10 // Copyright 2006 Michael van der Westhuizen
11 // Copyright 2012 IBM Corp.
12 //
13 // Distributed under the Boost Software License, Version 1.0. (See
14 // accompanying file LICENSE_1_0.txt or copy at
15 // http://www.boost.org/LICENSE_1_0.txt)
16 //
17 //
18 // Lock-free algorithm by Alexander Terekhov
19 //
20 // Thanks to Ben Hitchings for the #weak + (#shared != 0)
21 // formulation
22 //
23
24 #include <boost/detail/sp_typeinfo.hpp>
25
26 extern "builtin" void __lwsync(void);
27 extern "builtin" void __isync(void);
28 extern "builtin" int __fetch_and_add(volatile int* addr, int val);
29 extern "builtin" int __compare_and_swap(volatile int*, int*, int);
30
31 namespace boost
32 {
33
34 namespace detail
35 {
36
atomic_increment(int * pw)37 inline void atomic_increment( int *pw )
38 {
39 // ++*pw;
40 __lwsync();
41 __fetch_and_add(pw, 1);
42 __isync();
43 }
44
atomic_decrement(int * pw)45 inline int atomic_decrement( int *pw )
46 {
47 // return --*pw;
48 __lwsync();
49 int originalValue = __fetch_and_add(pw, -1);
50 __isync();
51
52 return (originalValue - 1);
53 }
54
atomic_conditional_increment(int * pw)55 inline int atomic_conditional_increment( int *pw )
56 {
57 // if( *pw != 0 ) ++*pw;
58 // return *pw;
59
60 __lwsync();
61 int v = *const_cast<volatile int*>(pw);
62 for (;;)
63 // loop until state is known
64 {
65 if (v == 0) return 0;
66 if (__compare_and_swap(pw, &v, v + 1))
67 {
68 __isync(); return (v + 1);
69 }
70 }
71 }
72
73 class sp_counted_base
74 {
75 private:
76
77 sp_counted_base( sp_counted_base const & );
78 sp_counted_base & operator= ( sp_counted_base const & );
79
80 int use_count_; // #shared
81 int weak_count_; // #weak + (#shared != 0)
82 char pad[64] __attribute__((__aligned__(64)));
83 // pad to prevent false sharing
84 public:
85
sp_counted_base()86 sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
87 {
88 }
89
~sp_counted_base()90 virtual ~sp_counted_base() // nothrow
91 {
92 }
93
94 // dispose() is called when use_count_ drops to zero, to release
95 // the resources managed by *this.
96
97 virtual void dispose() = 0; // nothrow
98
99 // destroy() is called when weak_count_ drops to zero.
100
destroy()101 virtual void destroy() // nothrow
102 {
103 delete this;
104 }
105
106 virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
107 virtual void * get_local_deleter( sp_typeinfo const & ti ) = 0;
108 virtual void * get_untyped_deleter() = 0;
109
add_ref_copy()110 void add_ref_copy()
111 {
112 atomic_increment( &use_count_ );
113 }
114
add_ref_lock()115 bool add_ref_lock() // true on success
116 {
117 return atomic_conditional_increment( &use_count_ ) != 0;
118 }
119
release()120 void release() // nothrow
121 {
122 if( atomic_decrement( &use_count_ ) == 0 )
123 {
124 dispose();
125 weak_release();
126 }
127 }
128
weak_add_ref()129 void weak_add_ref() // nothrow
130 {
131 atomic_increment( &weak_count_ );
132 }
133
weak_release()134 void weak_release() // nothrow
135 {
136 if( atomic_decrement( &weak_count_ ) == 0 )
137 {
138 destroy();
139 }
140 }
141
use_count() const142 long use_count() const // nothrow
143 {
144 return *const_cast<volatile int*>(&use_count_);
145 }
146 };
147
148 } // namespace detail
149
150 } // namespace boost
151
152 #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
153