[857] | 1 | #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED
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| 2 | #define BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED
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| 3 |
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| 4 | // MS compatible compilers support #pragma once
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| 5 |
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| 6 | #if defined(_MSC_VER) && (_MSC_VER >= 1020)
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| 7 | # pragma once
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| 8 | #endif
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| 9 |
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| 10 | //
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| 11 | // detail/sp_counted_base_gcc_x86.hpp - g++ on 486+ or AMD64
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| 12 | //
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| 13 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
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| 14 | // Copyright 2004-2005 Peter Dimov
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| 15 | //
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| 16 | // Distributed under the Boost Software License, Version 1.0. (See
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| 17 | // accompanying file LICENSE_1_0.txt or copy at
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| 18 | // http://www.boost.org/LICENSE_1_0.txt)
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| 19 | //
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| 20 | //
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| 21 | // Lock-free algorithm by Alexander Terekhov
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| 22 | //
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| 23 | // Thanks to Ben Hitchings for the #weak + (#shared != 0)
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| 24 | // formulation
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| 25 | //
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| 26 |
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| 27 | #include <typeinfo>
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| 28 |
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| 29 | namespace boost
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| 30 | {
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| 31 |
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| 32 | namespace detail
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| 33 | {
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| 34 |
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| 35 | inline int atomic_exchange_and_add( int * pw, int dv )
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| 36 | {
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| 37 | // int r = *pw;
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| 38 | // *pw += dv;
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| 39 | // return r;
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| 40 |
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| 41 | int r;
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| 42 |
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| 43 | __asm__ __volatile__
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| 44 | (
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| 45 | "lock\n\t"
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| 46 | "xadd %1, %0":
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| 47 | "=m"( *pw ), "=r"( r ): // outputs (%0, %1)
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| 48 | "m"( *pw ), "1"( dv ): // inputs (%2, %3 == %1)
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| 49 | "memory", "cc" // clobbers
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| 50 | );
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| 51 |
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| 52 | return r;
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| 53 | }
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| 54 |
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| 55 | inline void atomic_increment( int * pw )
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| 56 | {
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| 57 | //atomic_exchange_and_add( pw, 1 );
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| 58 |
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| 59 | __asm__
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| 60 | (
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| 61 | "lock\n\t"
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| 62 | "incl %0":
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| 63 | "=m"( *pw ): // output (%0)
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| 64 | "m"( *pw ): // input (%1)
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| 65 | "cc" // clobbers
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| 66 | );
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| 67 | }
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| 68 |
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| 69 | inline int atomic_conditional_increment( int * pw )
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| 70 | {
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| 71 | // int rv = *pw;
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| 72 | // if( rv != 0 ) ++*pw;
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| 73 | // return rv;
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| 74 |
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| 75 | int rv, tmp;
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| 76 |
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| 77 | __asm__
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| 78 | (
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| 79 | "movl %0, %%eax\n\t"
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| 80 | "0:\n\t"
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| 81 | "test %%eax, %%eax\n\t"
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| 82 | "je 1f\n\t"
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| 83 | "movl %%eax, %2\n\t"
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| 84 | "incl %2\n\t"
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| 85 | "lock\n\t"
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| 86 | "cmpxchgl %2, %0\n\t"
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| 87 | "jne 0b\n\t"
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| 88 | "1:":
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| 89 | "=m"( *pw ), "=&a"( rv ), "=&r"( tmp ): // outputs (%0, %1, %2)
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| 90 | "m"( *pw ): // input (%3)
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| 91 | "cc" // clobbers
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| 92 | );
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| 93 |
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| 94 | return rv;
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| 95 | }
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| 96 |
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| 97 | class sp_counted_base
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| 98 | {
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| 99 | private:
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| 100 |
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| 101 | sp_counted_base( sp_counted_base const & );
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| 102 | sp_counted_base & operator= ( sp_counted_base const & );
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| 103 |
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| 104 | int use_count_; // #shared
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| 105 | int weak_count_; // #weak + (#shared != 0)
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| 106 |
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| 107 | public:
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| 108 |
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| 109 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
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| 110 | {
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| 111 | }
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| 112 |
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| 113 | virtual ~sp_counted_base() // nothrow
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| 114 | {
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| 115 | }
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| 116 |
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| 117 | // dispose() is called when use_count_ drops to zero, to release
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| 118 | // the resources managed by *this.
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| 119 |
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| 120 | virtual void dispose() = 0; // nothrow
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| 121 |
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| 122 | // destroy() is called when weak_count_ drops to zero.
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| 123 |
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| 124 | virtual void destroy() // nothrow
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| 125 | {
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| 126 | delete this;
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| 127 | }
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| 128 |
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| 129 | virtual void * get_deleter( std::type_info const & ti ) = 0;
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| 130 |
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| 131 | void add_ref_copy()
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| 132 | {
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| 133 | atomic_increment( &use_count_ );
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| 134 | }
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| 135 |
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| 136 | bool add_ref_lock() // true on success
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| 137 | {
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| 138 | return atomic_conditional_increment( &use_count_ ) != 0;
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| 139 | }
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| 140 |
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| 141 | void release() // nothrow
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| 142 | {
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| 143 | if( atomic_exchange_and_add( &use_count_, -1 ) == 1 )
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| 144 | {
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| 145 | dispose();
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| 146 | weak_release();
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| 147 | }
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| 148 | }
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| 149 |
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| 150 | void weak_add_ref() // nothrow
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| 151 | {
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| 152 | atomic_increment( &weak_count_ );
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| 153 | }
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| 154 |
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| 155 | void weak_release() // nothrow
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| 156 | {
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| 157 | if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 )
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| 158 | {
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| 159 | destroy();
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| 160 | }
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| 161 | }
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| 162 |
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| 163 | long use_count() const // nothrow
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| 164 | {
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| 165 | return static_cast<int const volatile &>( use_count_ );
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| 166 | }
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| 167 | };
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| 168 |
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| 169 | } // namespace detail
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| 170 |
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| 171 | } // namespace boost
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| 172 |
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| 173 | #endif // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED
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