ceph/src/boost/libs/smart_ptr/include/boost/smart_ptr/detail/sp_counted_base_gcc_x86.hpp

   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
  27 #include <boost/detail/sp_typeinfo.hpp>
  28
  29 namespace boost
  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 boost
 173
 174 #endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED