1 | #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED |
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2 | #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_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_cw_x86.hpp - CodeWarrion on 486+ |
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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 | // Copyright 2005 Rene Rivera |
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16 | // |
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17 | // Distributed under the Boost Software License, Version 1.0. (See |
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18 | // accompanying file LICENSE_1_0.txt or copy at |
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19 | // http://www.boost.org/LICENSE_1_0.txt) |
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20 | // |
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21 | // |
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22 | // Lock-free algorithm by Alexander Terekhov |
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23 | // |
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24 | // Thanks to Ben Hitchings for the #weak + (#shared != 0) |
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25 | // formulation |
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26 | // |
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27 | |
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28 | #include <boost/detail/sp_typeinfo.hpp> |
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29 | |
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30 | namespace boost |
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31 | { |
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32 | |
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33 | namespace detail |
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34 | { |
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35 | |
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36 | inline int atomic_exchange_and_add( int * pw, int dv ) |
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37 | { |
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38 | // int r = *pw; |
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39 | // *pw += dv; |
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40 | // return r; |
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41 | |
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42 | asm |
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43 | { |
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44 | mov esi, [pw] |
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45 | mov eax, dv |
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46 | lock xadd dword ptr [esi], eax |
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47 | } |
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48 | } |
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49 | |
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50 | inline void atomic_increment( int * pw ) |
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51 | { |
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52 | //atomic_exchange_and_add( pw, 1 ); |
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53 | |
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54 | asm |
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55 | { |
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56 | mov esi, [pw] |
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57 | lock inc dword ptr [esi] |
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58 | } |
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59 | } |
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60 | |
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61 | inline int atomic_conditional_increment( int * pw ) |
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62 | { |
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63 | // int rv = *pw; |
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64 | // if( rv != 0 ) ++*pw; |
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65 | // return rv; |
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66 | |
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67 | asm |
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68 | { |
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69 | mov esi, [pw] |
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70 | mov eax, dword ptr [esi] |
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71 | L0: |
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72 | test eax, eax |
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73 | je L1 |
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74 | mov ebx, eax |
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75 | inc ebx |
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76 | lock cmpxchg dword ptr [esi], ebx |
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77 | jne L0 |
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78 | L1: |
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79 | } |
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80 | } |
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81 | |
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82 | class sp_counted_base |
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83 | { |
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84 | private: |
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85 | |
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86 | sp_counted_base( sp_counted_base const & ); |
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87 | sp_counted_base & operator= ( sp_counted_base const & ); |
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88 | |
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89 | int use_count_; // #shared |
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90 | int weak_count_; // #weak + (#shared != 0) |
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91 | |
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92 | public: |
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93 | |
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94 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) |
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95 | { |
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96 | } |
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97 | |
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98 | virtual ~sp_counted_base() // nothrow |
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99 | { |
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100 | } |
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101 | |
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102 | // dispose() is called when use_count_ drops to zero, to release |
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103 | // the resources managed by *this. |
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104 | |
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105 | virtual void dispose() = 0; // nothrow |
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106 | |
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107 | // destroy() is called when weak_count_ drops to zero. |
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108 | |
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109 | virtual void destroy() // nothrow |
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110 | { |
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111 | delete this; |
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112 | } |
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113 | |
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114 | virtual void * get_deleter( sp_typeinfo const & ti ) = 0; |
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115 | |
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116 | void add_ref_copy() |
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117 | { |
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118 | atomic_increment( &use_count_ ); |
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119 | } |
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120 | |
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121 | bool add_ref_lock() // true on success |
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122 | { |
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123 | return atomic_conditional_increment( &use_count_ ) != 0; |
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124 | } |
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125 | |
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126 | void release() // nothrow |
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127 | { |
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128 | if( atomic_exchange_and_add( &use_count_, -1 ) == 1 ) |
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129 | { |
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130 | dispose(); |
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131 | weak_release(); |
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132 | } |
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133 | } |
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134 | |
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135 | void weak_add_ref() // nothrow |
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136 | { |
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137 | atomic_increment( &weak_count_ ); |
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138 | } |
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139 | |
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140 | void weak_release() // nothrow |
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141 | { |
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142 | if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 ) |
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143 | { |
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144 | destroy(); |
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145 | } |
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146 | } |
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147 | |
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148 | long use_count() const // nothrow |
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149 | { |
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150 | return static_cast<int const volatile &>( use_count_ ); |
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151 | } |
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152 | }; |
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153 | |
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154 | } // namespace detail |
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155 | |
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156 | } // namespace boost |
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157 | |
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158 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_CW_X86_HPP_INCLUDED |
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