source: NonGTP/Boost/boost/detail/sp_counted_base_gcc_ia64.hpp @ 857

Revision 857, 3.6 KB checked in by igarcia, 19 years ago (diff)
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1#ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED
2#define BOOST_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED
3
4//
5//  detail/sp_counted_base_gcc_ia64.hpp - g++ on IA64
6//
7//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
8//  Copyright 2004-2005 Peter Dimov
9//  Copyright 2005 Ben Hutchings
10//
11//  Distributed under the Boost Software License, Version 1.0. (See
12//  accompanying file LICENSE_1_0.txt or copy at
13//  http://www.boost.org/LICENSE_1_0.txt)
14//
15//
16//  Lock-free algorithm by Alexander Terekhov
17//
18
19#include <typeinfo>
20
21namespace boost
22{
23
24namespace detail
25{
26
27inline void atomic_increment( long * pw )
28{
29    // ++*pw;
30
31    long tmp;
32
33    // No barrier is required here but fetchadd always has an acquire or
34    // release barrier associated with it.  We choose release as it should be
35    // cheaper.
36    __asm__ ("fetchadd8.rel %0=[%2],1" :
37         "=r"(tmp), "=m"(*pw) :
38         "r"(pw));
39}
40
41inline long atomic_decrement( long * pw )
42{
43    // return --*pw;
44
45    long rv;
46
47    __asm__ ("     fetchadd8.rel %0=[%2],-1 ;; \n"
48             "     cmp.eq        p7,p0=1,%0 ;; \n"
49             "(p7) ld8.acq       %0=[%2]    " :
50             "=&r"(rv), "=m"(*pw) :
51             "r"(pw) :
52             "p7");
53
54    return rv;
55}
56
57inline long atomic_conditional_increment( long * pw )
58{
59    // if( *pw != 0 ) ++*pw;
60    // return *pw;
61
62    long rv, tmp, tmp2;
63
64    __asm__ ("0:   ld8          %0=[%4]           ;; \n"
65         "     cmp.eq       p7,p0=0,%0        ;; \n"
66         "(p7) br.cond.spnt 1f                \n"
67         "     mov          ar.ccv=%0         \n"
68         "     add          %1=1,%0           ;; \n"
69         "     cmpxchg8.acq %2=[%4],%1,ar.ccv ;; \n"
70         "     cmp.ne       p7,p0=%0,%2       ;; \n"
71         "(p7) br.cond.spnt 0b                \n"
72         "     mov          %0=%1             ;; \n"
73         "1:" :
74         "=&r"(rv), "=&r"(tmp), "=&r"(tmp2), "=m"(*pw) :
75         "r"(pw) :
76         "ar.ccv", "p7");
77
78    return rv;
79}
80
81class sp_counted_base
82{
83private:
84
85    sp_counted_base( sp_counted_base const & );
86    sp_counted_base & operator= ( sp_counted_base const & );
87
88    long use_count_;        // #shared
89    long weak_count_;       // #weak + (#shared != 0)
90
91public:
92
93    sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
94    {
95    }
96
97    virtual ~sp_counted_base() // nothrow
98    {
99    }
100
101    // dispose() is called when use_count_ drops to zero, to release
102    // the resources managed by *this.
103
104    virtual void dispose() = 0; // nothrow
105
106    // destroy() is called when weak_count_ drops to zero.
107
108    virtual void destroy() // nothrow
109    {
110        delete this;
111    }
112
113    virtual void * get_deleter( std::type_info const & ti ) = 0;
114
115    void add_ref_copy()
116    {
117        atomic_increment( &use_count_ );
118    }
119
120    bool add_ref_lock() // true on success
121    {
122        return atomic_conditional_increment( &use_count_ ) != 0;
123    }
124
125    void release() // nothrow
126    {
127        if( atomic_decrement( &use_count_ ) == 0 )
128        {
129            dispose();
130            weak_release();
131        }
132    }
133
134    void weak_add_ref() // nothrow
135    {
136        atomic_increment( &weak_count_ );
137    }
138
139    void weak_release() // nothrow
140    {
141        if( atomic_decrement( &weak_count_ ) == 0 )
142        {
143            destroy();
144        }
145    }
146
147    long use_count() const // nothrow
148    {
149        return static_cast<long const volatile &>( use_count_ );
150    }
151};
152
153} // namespace detail
154
155} // namespace boost
156
157#endif  // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED
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