Jeff Thompson | f7d4994 | 2013-08-01 16:47:40 -0700 | [diff] [blame] | 1 | #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED |
| 2 | #define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED |
| 3 | |
| 4 | // MS compatible compilers support #pragma once |
| 5 | |
| 6 | #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
| 7 | # pragma once |
| 8 | #endif |
| 9 | |
| 10 | // |
| 11 | // detail/sp_counted_base_gcc_x86.hpp - g++ on 486+ or AMD64 |
| 12 | // |
| 13 | // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. |
| 14 | // Copyright 2004-2005 Peter Dimov |
| 15 | // |
| 16 | // Distributed under the Boost Software License, Version 1.0. (See |
| 17 | // accompanying file LICENSE_1_0.txt or copy at |
| 18 | // http://www.boost.org/LICENSE_1_0.txt) |
| 19 | // |
| 20 | // |
| 21 | // Lock-free algorithm by Alexander Terekhov |
| 22 | // |
| 23 | // Thanks to Ben Hitchings for the #weak + (#shared != 0) |
| 24 | // formulation |
| 25 | // |
| 26 | |
Jeff Thompson | 2277ce5 | 2013-08-01 17:34:11 -0700 | [diff] [blame] | 27 | #include <ndnboost/detail/sp_typeinfo.hpp> |
Jeff Thompson | f7d4994 | 2013-08-01 16:47:40 -0700 | [diff] [blame] | 28 | |
| 29 | namespace ndnboost |
| 30 | { |
| 31 | |
| 32 | namespace detail |
| 33 | { |
| 34 | |
| 35 | inline int atomic_exchange_and_add( int * pw, int dv ) |
| 36 | { |
| 37 | // int r = *pw; |
| 38 | // *pw += dv; |
| 39 | // return r; |
| 40 | |
| 41 | int r; |
| 42 | |
| 43 | __asm__ __volatile__ |
| 44 | ( |
| 45 | "lock\n\t" |
| 46 | "xadd %1, %0": |
| 47 | "=m"( *pw ), "=r"( r ): // outputs (%0, %1) |
| 48 | "m"( *pw ), "1"( dv ): // inputs (%2, %3 == %1) |
| 49 | "memory", "cc" // clobbers |
| 50 | ); |
| 51 | |
| 52 | return r; |
| 53 | } |
| 54 | |
| 55 | inline void atomic_increment( int * pw ) |
| 56 | { |
| 57 | //atomic_exchange_and_add( pw, 1 ); |
| 58 | |
| 59 | __asm__ |
| 60 | ( |
| 61 | "lock\n\t" |
| 62 | "incl %0": |
| 63 | "=m"( *pw ): // output (%0) |
| 64 | "m"( *pw ): // input (%1) |
| 65 | "cc" // clobbers |
| 66 | ); |
| 67 | } |
| 68 | |
| 69 | inline int atomic_conditional_increment( int * pw ) |
| 70 | { |
| 71 | // int rv = *pw; |
| 72 | // if( rv != 0 ) ++*pw; |
| 73 | // return rv; |
| 74 | |
| 75 | int rv, tmp; |
| 76 | |
| 77 | __asm__ |
| 78 | ( |
| 79 | "movl %0, %%eax\n\t" |
| 80 | "0:\n\t" |
| 81 | "test %%eax, %%eax\n\t" |
| 82 | "je 1f\n\t" |
| 83 | "movl %%eax, %2\n\t" |
| 84 | "incl %2\n\t" |
| 85 | "lock\n\t" |
| 86 | "cmpxchgl %2, %0\n\t" |
| 87 | "jne 0b\n\t" |
| 88 | "1:": |
| 89 | "=m"( *pw ), "=&a"( rv ), "=&r"( tmp ): // outputs (%0, %1, %2) |
| 90 | "m"( *pw ): // input (%3) |
| 91 | "cc" // clobbers |
| 92 | ); |
| 93 | |
| 94 | return rv; |
| 95 | } |
| 96 | |
| 97 | class sp_counted_base |
| 98 | { |
| 99 | private: |
| 100 | |
| 101 | sp_counted_base( sp_counted_base const & ); |
| 102 | sp_counted_base & operator= ( sp_counted_base const & ); |
| 103 | |
| 104 | int use_count_; // #shared |
| 105 | int weak_count_; // #weak + (#shared != 0) |
| 106 | |
| 107 | public: |
| 108 | |
| 109 | sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) |
| 110 | { |
| 111 | } |
| 112 | |
| 113 | virtual ~sp_counted_base() // nothrow |
| 114 | { |
| 115 | } |
| 116 | |
| 117 | // dispose() is called when use_count_ drops to zero, to release |
| 118 | // the resources managed by *this. |
| 119 | |
| 120 | virtual void dispose() = 0; // nothrow |
| 121 | |
| 122 | // destroy() is called when weak_count_ drops to zero. |
| 123 | |
| 124 | virtual void destroy() // nothrow |
| 125 | { |
| 126 | delete this; |
| 127 | } |
| 128 | |
| 129 | virtual void * get_deleter( sp_typeinfo const & ti ) = 0; |
| 130 | virtual void * get_untyped_deleter() = 0; |
| 131 | |
| 132 | void add_ref_copy() |
| 133 | { |
| 134 | atomic_increment( &use_count_ ); |
| 135 | } |
| 136 | |
| 137 | bool add_ref_lock() // true on success |
| 138 | { |
| 139 | return atomic_conditional_increment( &use_count_ ) != 0; |
| 140 | } |
| 141 | |
| 142 | void release() // nothrow |
| 143 | { |
| 144 | if( atomic_exchange_and_add( &use_count_, -1 ) == 1 ) |
| 145 | { |
| 146 | dispose(); |
| 147 | weak_release(); |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | void weak_add_ref() // nothrow |
| 152 | { |
| 153 | atomic_increment( &weak_count_ ); |
| 154 | } |
| 155 | |
| 156 | void weak_release() // nothrow |
| 157 | { |
| 158 | if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 ) |
| 159 | { |
| 160 | destroy(); |
| 161 | } |
| 162 | } |
| 163 | |
| 164 | long use_count() const // nothrow |
| 165 | { |
| 166 | return static_cast<int const volatile &>( use_count_ ); |
| 167 | } |
| 168 | }; |
| 169 | |
| 170 | } // namespace detail |
| 171 | |
| 172 | } // namespace ndnboost |
| 173 | |
| 174 | #endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED |