epoc32/include/stdapis/boost/detail/sp_counted_base_gcc_ia64.hpp
author William Roberts <williamr@symbian.org>
Wed, 31 Mar 2010 12:33:34 +0100
branchSymbian3
changeset 4 837f303aceeb
permissions -rw-r--r--
Current Symbian^3 public API header files (from PDK 3.0.h)
This is the epoc32/include tree with the "platform" subtrees removed, and
all but a selected few mbg and rsg files removed.
     1 #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED
     2 #define BOOST_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED
     3 
     4 //
     5 //  detail/sp_counted_base_gcc_ia64.hpp - g++ on IA64
     6 //
     7 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
     8 //  Copyright 2004-2006 Peter Dimov
     9 //  Copyright 2005 Ben Hutchings
    10 //
    11 //  Distributed under the Boost Software License, Version 1.0. (See
    12 //  accompanying file LICENSE_1_0.txt or copy at
    13 //  http://www.boost.org/LICENSE_1_0.txt)
    14 //
    15 //
    16 //  Lock-free algorithm by Alexander Terekhov
    17 //
    18 
    19 #include <typeinfo>
    20 
    21 namespace boost
    22 {
    23 
    24 namespace detail
    25 {
    26 
    27 inline void atomic_increment( int * pw )
    28 {
    29     // ++*pw;
    30 
    31     int tmp;
    32 
    33     // No barrier is required here but fetchadd always has an acquire or
    34     // release barrier associated with it.  We choose release as it should be
    35     // cheaper.
    36     __asm__ ("fetchadd4.rel %0=%1,1" :
    37          "=r"(tmp), "=m"(*pw) :
    38          "m"( *pw ));
    39 }
    40 
    41 inline int atomic_decrement( int * pw )
    42 {
    43     // return --*pw;
    44 
    45     int rv;
    46 
    47     __asm__ ("     fetchadd4.rel %0=%1,-1 ;; \n"
    48              "     cmp.eq        p7,p0=1,%0 ;; \n"
    49              "(p7) ld4.acq       %0=%1    " :
    50              "=&r"(rv), "=m"(*pw) :
    51              "m"( *pw ) :
    52              "p7");
    53 
    54     return rv;
    55 }
    56 
    57 inline int atomic_conditional_increment( int * pw )
    58 {
    59     // if( *pw != 0 ) ++*pw;
    60     // return *pw;
    61 
    62     int rv, tmp, tmp2;
    63 
    64     __asm__ ("0:   ld4          %0=%3           ;; \n"
    65          "     cmp.eq       p7,p0=0,%0        ;; \n"
    66          "(p7) br.cond.spnt 1f                \n"
    67          "     mov          ar.ccv=%0         \n"
    68          "     add          %1=1,%0           ;; \n"
    69          "     cmpxchg4.acq %2=%3,%1,ar.ccv ;; \n"
    70          "     cmp.ne       p7,p0=%0,%2       ;; \n"
    71          "(p7) br.cond.spnt 0b                \n"
    72          "     mov          %0=%1             ;; \n"
    73          "1:" : 
    74          "=&r"(rv), "=&r"(tmp), "=&r"(tmp2), "=m"(*pw) :
    75          "m"( *pw ) :
    76          "ar.ccv", "p7");
    77 
    78     return rv;
    79 }
    80 
    81 class sp_counted_base
    82 {
    83 private:
    84 
    85     sp_counted_base( sp_counted_base const & );
    86     sp_counted_base & operator= ( sp_counted_base const & );
    87 
    88     int use_count_;        // #shared
    89     int weak_count_;       // #weak + (#shared != 0)
    90 
    91 public:
    92 
    93     sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
    94     {
    95     }
    96 
    97     virtual ~sp_counted_base() // nothrow
    98     {
    99     }
   100 
   101     // dispose() is called when use_count_ drops to zero, to release
   102     // the resources managed by *this.
   103 
   104     virtual void dispose() = 0; // nothrow
   105 
   106     // destroy() is called when weak_count_ drops to zero.
   107 
   108     virtual void destroy() // nothrow
   109     {
   110         delete this;
   111     }
   112 
   113     virtual void * get_deleter( std::type_info const & ti ) = 0;
   114 
   115     void add_ref_copy()
   116     {
   117         atomic_increment( &use_count_ );
   118     }
   119 
   120     bool add_ref_lock() // true on success
   121     {
   122         return atomic_conditional_increment( &use_count_ ) != 0;
   123     }
   124 
   125     void release() // nothrow
   126     {
   127         if( atomic_decrement( &use_count_ ) == 0 )
   128         {
   129             dispose();
   130             weak_release();
   131         }
   132     }
   133 
   134     void weak_add_ref() // nothrow
   135     {
   136         atomic_increment( &weak_count_ );
   137     }
   138 
   139     void weak_release() // nothrow
   140     {
   141         if( atomic_decrement( &weak_count_ ) == 0 )
   142         {
   143             destroy();
   144         }
   145     }
   146 
   147     long use_count() const // nothrow
   148     {
   149         return static_cast<int const volatile &>( use_count_ ); // TODO use ld.acq here
   150     }
   151 };
   152 
   153 } // namespace detail
   154 
   155 } // namespace boost
   156 
   157 #endif  // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_IA64_HPP_INCLUDED