williamr@2: #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED williamr@2: #define BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED williamr@2: williamr@2: // MS compatible compilers support #pragma once williamr@2: williamr@2: #if defined(_MSC_VER) && (_MSC_VER >= 1020) williamr@2: # pragma once williamr@2: #endif williamr@2: williamr@2: // williamr@2: // detail/sp_counted_base_gcc_x86.hpp - g++ on 486+ or AMD64 williamr@2: // williamr@2: // Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd. williamr@2: // Copyright 2004-2005 Peter Dimov williamr@2: // williamr@2: // Distributed under the Boost Software License, Version 1.0. (See williamr@2: // accompanying file LICENSE_1_0.txt or copy at williamr@2: // http://www.boost.org/LICENSE_1_0.txt) williamr@2: // williamr@2: // williamr@2: // Lock-free algorithm by Alexander Terekhov williamr@2: // williamr@2: // Thanks to Ben Hitchings for the #weak + (#shared != 0) williamr@2: // formulation williamr@2: // williamr@2: williamr@2: #include williamr@2: williamr@2: namespace boost williamr@2: { williamr@2: williamr@2: namespace detail williamr@2: { williamr@2: williamr@2: inline int atomic_exchange_and_add( int * pw, int dv ) williamr@2: { williamr@2: // int r = *pw; williamr@2: // *pw += dv; williamr@2: // return r; williamr@2: williamr@2: int r; williamr@2: williamr@2: __asm__ __volatile__ williamr@2: ( williamr@2: "lock\n\t" williamr@2: "xadd %1, %0": williamr@2: "=m"( *pw ), "=r"( r ): // outputs (%0, %1) williamr@2: "m"( *pw ), "1"( dv ): // inputs (%2, %3 == %1) williamr@2: "memory", "cc" // clobbers williamr@2: ); williamr@2: williamr@2: return r; williamr@2: } williamr@2: williamr@2: inline void atomic_increment( int * pw ) williamr@2: { williamr@2: //atomic_exchange_and_add( pw, 1 ); williamr@2: williamr@2: __asm__ williamr@2: ( williamr@2: "lock\n\t" williamr@2: "incl %0": williamr@2: "=m"( *pw ): // output (%0) williamr@2: "m"( *pw ): // input (%1) williamr@2: "cc" // clobbers williamr@2: ); williamr@2: } williamr@2: williamr@2: inline int atomic_conditional_increment( int * pw ) williamr@2: { williamr@2: // int rv = *pw; williamr@2: // if( rv != 0 ) ++*pw; williamr@2: // return rv; williamr@2: williamr@2: int rv, tmp; williamr@2: williamr@2: __asm__ williamr@2: ( williamr@2: "movl %0, %%eax\n\t" williamr@2: "0:\n\t" williamr@2: "test %%eax, %%eax\n\t" williamr@2: "je 1f\n\t" williamr@2: "movl %%eax, %2\n\t" williamr@2: "incl %2\n\t" williamr@2: "lock\n\t" williamr@2: "cmpxchgl %2, %0\n\t" williamr@2: "jne 0b\n\t" williamr@2: "1:": williamr@2: "=m"( *pw ), "=&a"( rv ), "=&r"( tmp ): // outputs (%0, %1, %2) williamr@2: "m"( *pw ): // input (%3) williamr@2: "cc" // clobbers williamr@2: ); williamr@2: williamr@2: return rv; williamr@2: } williamr@2: williamr@2: class sp_counted_base williamr@2: { williamr@2: private: williamr@2: williamr@2: sp_counted_base( sp_counted_base const & ); williamr@2: sp_counted_base & operator= ( sp_counted_base const & ); williamr@2: williamr@2: int use_count_; // #shared williamr@2: int weak_count_; // #weak + (#shared != 0) williamr@2: williamr@2: public: williamr@2: williamr@2: sp_counted_base(): use_count_( 1 ), weak_count_( 1 ) williamr@2: { williamr@2: } williamr@2: williamr@2: virtual ~sp_counted_base() // nothrow williamr@2: { williamr@2: } williamr@2: williamr@2: // dispose() is called when use_count_ drops to zero, to release williamr@2: // the resources managed by *this. williamr@2: williamr@2: virtual void dispose() = 0; // nothrow williamr@2: williamr@2: // destroy() is called when weak_count_ drops to zero. williamr@2: williamr@2: virtual void destroy() // nothrow williamr@2: { williamr@2: delete this; williamr@2: } williamr@2: williamr@2: virtual void * get_deleter( std::type_info const & ti ) = 0; williamr@2: williamr@2: void add_ref_copy() williamr@2: { williamr@2: atomic_increment( &use_count_ ); williamr@2: } williamr@2: williamr@2: bool add_ref_lock() // true on success williamr@2: { williamr@2: return atomic_conditional_increment( &use_count_ ) != 0; williamr@2: } williamr@2: williamr@2: void release() // nothrow williamr@2: { williamr@2: if( atomic_exchange_and_add( &use_count_, -1 ) == 1 ) williamr@2: { williamr@2: dispose(); williamr@2: weak_release(); williamr@2: } williamr@2: } williamr@2: williamr@2: void weak_add_ref() // nothrow williamr@2: { williamr@2: atomic_increment( &weak_count_ ); williamr@2: } williamr@2: williamr@2: void weak_release() // nothrow williamr@2: { williamr@2: if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 ) williamr@2: { williamr@2: destroy(); williamr@2: } williamr@2: } williamr@2: williamr@2: long use_count() const // nothrow williamr@2: { williamr@2: return static_cast( use_count_ ); williamr@2: } williamr@2: }; williamr@2: williamr@2: } // namespace detail williamr@2: williamr@2: } // namespace boost williamr@2: williamr@2: #endif // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_GCC_X86_HPP_INCLUDED