1 | #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED |
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2 | #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED |
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3 | |
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4 | // |
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5 | // detail/sp_counted_base_gcc_ia64.hpp - g++ on IA64 |
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6 | // |
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7 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. |
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8 | // Copyright 2004-2006 Peter Dimov |
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9 | // Copyright 2005 Ben Hutchings |
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10 | // |
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11 | // Distributed under the Boost Software License, Version 1.0. (See |
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12 | // accompanying file LICENSE_1_0.txt or copy at |
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13 | // http://www.boost.org/LICENSE_1_0.txt) |
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14 | // |
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15 | // |
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16 | // Lock-free algorithm by Alexander Terekhov |
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17 | // |
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18 | |
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19 | #include <boost/detail/sp_typeinfo.hpp> |
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20 | |
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21 | namespace boost |
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22 | { |
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23 | |
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24 | namespace detail |
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25 | { |
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26 | |
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27 | inline void atomic_increment( int * pw ) |
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28 | { |
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29 | // ++*pw; |
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30 | |
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31 | int tmp; |
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32 | |
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33 | // No barrier is required here but fetchadd always has an acquire or |
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34 | // release barrier associated with it. We choose release as it should be |
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35 | // cheaper. |
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36 | __asm__ ("fetchadd4.rel %0=%1,1" : |
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37 | "=r"(tmp), "=m"(*pw) : |
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38 | "m"( *pw )); |
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39 | } |
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40 | |
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41 | inline int atomic_decrement( int * pw ) |
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42 | { |
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43 | // return --*pw; |
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44 | |
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45 | int rv; |
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46 | |
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47 | __asm__ (" fetchadd4.rel %0=%1,-1 ;; \n" |
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48 | " cmp.eq p7,p0=1,%0 ;; \n" |
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49 | "(p7) ld4.acq %0=%1 " : |
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50 | "=&r"(rv), "=m"(*pw) : |
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51 | "m"( *pw ) : |
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52 | "p7"); |
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53 | |
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54 | return rv; |
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55 | } |
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56 | |
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57 | inline int atomic_conditional_increment( int * pw ) |
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58 | { |
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59 | // if( *pw != 0 ) ++*pw; |
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60 | // return *pw; |
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61 | |
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62 | int rv, tmp, tmp2; |
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63 | |
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64 | __asm__ ("0: ld4 %0=%3 ;; \n" |
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65 | " cmp.eq p7,p0=0,%0 ;; \n" |
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66 | "(p7) br.cond.spnt 1f \n" |
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67 | " mov ar.ccv=%0 \n" |
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68 | " add %1=1,%0 ;; \n" |
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69 | " cmpxchg4.acq %2=%3,%1,ar.ccv ;; \n" |
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70 | " cmp.ne p7,p0=%0,%2 ;; \n" |
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71 | "(p7) br.cond.spnt 0b \n" |
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72 | " mov %0=%1 ;; \n" |
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73 | "1:" : |
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74 | "=&r"(rv), "=&r"(tmp), "=&r"(tmp2), "=m"(*pw) : |
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75 | "m"( *pw ) : |
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76 | "ar.ccv", "p7"); |
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77 | |
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78 | return rv; |
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79 | } |
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80 | |
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81 | class sp_counted_base |
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82 | { |
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83 | private: |
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84 | |
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85 | sp_counted_base( sp_counted_base const & ); |
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86 | sp_counted_base & operator= ( sp_counted_base const & ); |
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87 | |
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88 | int use_count_; // #shared |
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89 | int weak_count_; // #weak + (#shared != 0) |
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90 | |
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91 | public: |
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92 | |
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93 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) |
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94 | { |
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95 | } |
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96 | |
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97 | virtual ~sp_counted_base() // nothrow |
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98 | { |
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99 | } |
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100 | |
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101 | // dispose() is called when use_count_ drops to zero, to release |
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102 | // the resources managed by *this. |
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103 | |
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104 | virtual void dispose() = 0; // nothrow |
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105 | |
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106 | // destroy() is called when weak_count_ drops to zero. |
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107 | |
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108 | virtual void destroy() // nothrow |
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109 | { |
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110 | delete this; |
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111 | } |
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112 | |
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113 | virtual void * get_deleter( sp_typeinfo const & ti ) = 0; |
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114 | |
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115 | void add_ref_copy() |
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116 | { |
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117 | atomic_increment( &use_count_ ); |
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118 | } |
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119 | |
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120 | bool add_ref_lock() // true on success |
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121 | { |
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122 | return atomic_conditional_increment( &use_count_ ) != 0; |
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123 | } |
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124 | |
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125 | void release() // nothrow |
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126 | { |
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127 | if( atomic_decrement( &use_count_ ) == 0 ) |
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128 | { |
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129 | dispose(); |
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130 | weak_release(); |
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131 | } |
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132 | } |
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133 | |
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134 | void weak_add_ref() // nothrow |
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135 | { |
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136 | atomic_increment( &weak_count_ ); |
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137 | } |
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138 | |
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139 | void weak_release() // nothrow |
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140 | { |
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141 | if( atomic_decrement( &weak_count_ ) == 0 ) |
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142 | { |
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143 | destroy(); |
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144 | } |
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145 | } |
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146 | |
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147 | long use_count() const // nothrow |
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148 | { |
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149 | return static_cast<int const volatile &>( use_count_ ); // TODO use ld.acq here |
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150 | } |
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151 | }; |
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152 | |
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153 | } // namespace detail |
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154 | |
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155 | } // namespace boost |
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156 | |
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157 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED |
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