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atomic.h

/*
    Copyright 2005-2007 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks.

    Threading Building Blocks is free software; you can redistribute it
    and/or modify it under the terms of the GNU General Public License
    version 2 as published by the Free Software Foundation.

    Threading Building Blocks is distributed in the hope that it will be
    useful, but WITHOUT ANY WARRANTY; without even the implied warranty
    of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Threading Building Blocks; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    As a special exception, you may use this file as part of a free software
    library without restriction.  Specifically, if other files instantiate
    templates or use macros or inline functions from this file, or you compile
    this file and link it with other files to produce an executable, this
    file does not by itself cause the resulting executable to be covered by
    the GNU General Public License.  This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

#ifndef __TBB_atomic_H
#define __TBB_atomic_H

#include <cstddef>
#include "tbb_stddef.h"

#if _MSC_VER 
#define __TBB_LONG_LONG __int64
#else
#define __TBB_LONG_LONG long long
#endif /* _MSC_VER */

#include "tbb_machine.h"

namespace tbb {

//! Specifies memory fencing.
00046 enum memory_semantics {
    //! For internal use only.
00048     __TBB_full_fence,
    //! Acquire fence
00050     acquire,
    //! Release fence
00052     release
};

//! @cond INTERNAL
namespace internal {

template<size_t Size, memory_semantics M>
struct atomic_traits {       // Primary template
};

template<size_t Size>
struct atomic_word {             // Primary template
    typedef intptr word;
};

template<typename I>            // Primary template
struct atomic_base {
    volatile I my_value;
};

#if __GNUC__ 
#define __TBB_DECL_ATOMIC_FIELD(t,f,a) t f  __attribute__ ((aligned(a)));
#elif defined(__INTEL_COMPILER)||_MSC_VER >= 1300
#define __TBB_DECL_ATOMIC_FIELD(t,f,a) __declspec(align(a)) t f;
#else 
#error Do not know syntax for forcing alignment.
#endif /* __GNUC__ */

template<>
struct atomic_word<8> {          // Specialization
    typedef int64_t word;
};

#if _WIN32 && __TBB_x86_64
// ATTENTION: On 64-bit Windows, we currently have to specialize atomic_word
// for every size to avoid type conversion warnings
// See declarations of atomic primitives in machine/windows_em64t.h
template<>
struct atomic_word<1> {          // Specialization
    typedef int8_t word;
};
template<>
struct atomic_word<2> {          // Specialization
    typedef int16_t word;
};
template<>
struct atomic_word<4> {          // Specialization
    typedef int32_t word;
};
#endif

template<>
struct atomic_base<uint64_t> {   // Specialization
    __TBB_DECL_ATOMIC_FIELD(volatile uint64_t,my_value,8)
};

template<>
struct atomic_base<int64_t> {    // Specialization
    __TBB_DECL_ATOMIC_FIELD(volatile int64_t,my_value,8)
};

#define __TBB_DECL_FENCED_ATOMIC_PRIMITIVES(S,M)                         \
    template<> struct atomic_traits<S,M> {                               \
        typedef atomic_word<S>::word word;                               \
        inline static word compare_and_swap( volatile void* location, word new_value, word comparand ) {\
            return __TBB_CompareAndSwap##S##M(location,new_value,comparand);    \
        }                                                                       \
        inline static word fetch_and_add( volatile void* location, word addend ) { \
            return __TBB_FetchAndAdd##S##M(location,addend);                    \
        }                                                                       \
        inline static word fetch_and_store( volatile void* location, word value ) {\
            return __TBB_FetchAndStore##S##M(location,value);                   \
        }                                                                       \
    };

#define __TBB_DECL_ATOMIC_PRIMITIVES(S)                                  \
    template<memory_semantics M>                                         \
    struct atomic_traits<S,M> {                                          \
        typedef atomic_word<S>::word word;                               \
        inline static word compare_and_swap( volatile void* location, word new_value, word comparand ) {\
            return __TBB_CompareAndSwap##S(location,new_value,comparand);       \
        }                                                                       \
        inline static word fetch_and_add( volatile void* location, word addend ) { \
            return __TBB_FetchAndAdd##S(location,addend);                       \
        }                                                                       \
        inline static word fetch_and_store( volatile void* location, word value ) {\
            return __TBB_FetchAndStore##S(location,value);                      \
        }                                                                       \
    };

#if __TBB_DECL_FENCED_ATOMICS
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(1,__TBB_full_fence)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(2,__TBB_full_fence)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(4,__TBB_full_fence)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(8,__TBB_full_fence)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(1,acquire)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(2,acquire)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(4,acquire)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(8,acquire)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(1,release)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(2,release)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(4,release)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(8,release)
#else
__TBB_DECL_ATOMIC_PRIMITIVES(1)
__TBB_DECL_ATOMIC_PRIMITIVES(2)
__TBB_DECL_ATOMIC_PRIMITIVES(4)
__TBB_DECL_ATOMIC_PRIMITIVES(8)
#endif

//! Additive inverse of 1 for type T.
/** Various compilers issue various warnings if -1 is used with various integer types.
    The baroque expression below avoids all the warnings (we hope). */
#define __TBB_MINUS_ONE(T) (T(T(0)-T(1)))

template<typename I, typename D, size_t Step>
struct atomic_impl: private atomic_base<I> {
private:
    typedef typename atomic_word<sizeof(I)>::word word;
public:
    typedef I value_type;

    template<memory_semantics M>
    value_type fetch_and_add( D addend ) {
        return value_type(internal::atomic_traits<sizeof(value_type),M>::fetch_and_add( &this->my_value, addend*Step ));
    }

    value_type fetch_and_add( D addend ) {
        return fetch_and_add<__TBB_full_fence>(addend);
    }

    template<memory_semantics M>
    value_type fetch_and_increment() {
        return fetch_and_add<M>(1);
    }

    value_type fetch_and_increment() {
        return fetch_and_add(1);
    }

    template<memory_semantics M>
    value_type fetch_and_decrement() {
        return fetch_and_add<M>(__TBB_MINUS_ONE(D));
    }

    value_type fetch_and_decrement() {
        return fetch_and_add(__TBB_MINUS_ONE(D));
    }

    template<memory_semantics M>
    value_type fetch_and_store( value_type value ) {
        return value_type(internal::atomic_traits<sizeof(value_type),M>::fetch_and_store(&this->my_value,word(value)));
    }

    value_type fetch_and_store( value_type value ) {
        return fetch_and_store<__TBB_full_fence>(value);
    }

    template<memory_semantics M>
    value_type compare_and_swap( value_type value, value_type comparand ) {
        return value_type(internal::atomic_traits<sizeof(value_type),M>::compare_and_swap(&this->my_value,word(value),word(comparand)));
    }

    value_type compare_and_swap( value_type value, value_type comparand ) {
        return compare_and_swap<__TBB_full_fence>(value,comparand);
    }

    operator value_type() const volatile {
        return __TBB_load_with_acquire( this->my_value );
    }

    value_type& _internal_reference() const {
        return static_cast<value_type&>(this->my_value);
    }

protected:
    value_type store_with_release( value_type rhs ) {
        __TBB_store_with_release(this->my_value,rhs);
        return rhs;
    }

public:
    value_type operator+=( D addend ) {
        return fetch_and_add(addend)+addend;
    }

    value_type operator-=( D addend ) {
        // Additive inverse of addend computed using binary minus,
        // instead of unary minus, for sake of avoiding compiler warnings.
        return operator+=(D(0)-addend);    
    }

    value_type operator++() {
        return fetch_and_add(1)+1;
    }

    value_type operator--() {
        return fetch_and_add(__TBB_MINUS_ONE(D))-1;
    }

    value_type operator++(int) {
        return fetch_and_add(1);
    }

    value_type operator--(int) {
        return fetch_and_add(__TBB_MINUS_ONE(D));
    }
};

#if WORDSIZE == 4
#if defined(__INTEL_COMPILER)||!defined(_MSC_VER)||_MSC_VER>=1400

template<>
inline atomic_impl<__TBB_LONG_LONG,__TBB_LONG_LONG,1>::operator atomic_impl<__TBB_LONG_LONG,__TBB_LONG_LONG,1>::value_type() const volatile {
    return __TBB_Load8(&this->my_value);
}

template<>
inline atomic_impl<unsigned __TBB_LONG_LONG,unsigned __TBB_LONG_LONG,1>::operator atomic_impl<unsigned __TBB_LONG_LONG,unsigned __TBB_LONG_LONG,1>::value_type() const volatile {
    return __TBB_Load8(&this->my_value);
}

template<>
inline atomic_impl<__TBB_LONG_LONG,__TBB_LONG_LONG,1>::value_type atomic_impl<__TBB_LONG_LONG,__TBB_LONG_LONG,1>::store_with_release( value_type rhs ) {
    __TBB_Store8(&this->my_value,rhs);
    return rhs;
}

template<>
inline atomic_impl<unsigned __TBB_LONG_LONG,unsigned __TBB_LONG_LONG,1>::value_type atomic_impl<unsigned __TBB_LONG_LONG,unsigned __TBB_LONG_LONG,1>::store_with_release( value_type rhs ) {
    __TBB_Store8(&this->my_value,rhs);
    return rhs;
}

#endif /* defined(__INTEL_COMPILER)||!defined(_MSC_VER)||_MSC_VER>=1400 */
#endif

} /* Internal */
//! @endcond

//! Primary template for atomic.
/** See the Reference for details.
    @ingroup synchronization */
template<typename T>
00296 struct atomic {
};

#define __TBB_DECL_ATOMIC(T) \
    template<> struct atomic<T>: internal::atomic_impl<T,T,1> {  \
        T operator=( T rhs ) {return store_with_release(rhs);}  \
    };

#if defined(__INTEL_COMPILER)||!defined(_MSC_VER)||_MSC_VER>=1400
__TBB_DECL_ATOMIC(__TBB_LONG_LONG)
__TBB_DECL_ATOMIC(unsigned __TBB_LONG_LONG)
#else
// Some old versions of MVSC cannot correctly compile templates with "long long".
#endif /* defined(__INTEL_COMPILER)||!defined(_MSC_VER)||_MSC_VER>=1400 */
__TBB_DECL_ATOMIC(long)
__TBB_DECL_ATOMIC(unsigned long)
__TBB_DECL_ATOMIC(unsigned int)
__TBB_DECL_ATOMIC(int)
__TBB_DECL_ATOMIC(unsigned short)
__TBB_DECL_ATOMIC(short)
__TBB_DECL_ATOMIC(char)
__TBB_DECL_ATOMIC(signed char)
__TBB_DECL_ATOMIC(unsigned char)

#if !defined(_MSC_VER)||defined(_NATIVE_WCHAR_T_DEFINED) 
__TBB_DECL_ATOMIC(wchar_t)
#endif /* _MSC_VER||!defined(_NATIVE_WCHAR_T_DEFINED) */

template<typename T> struct atomic<T*>: internal::atomic_impl<T*,ptrdiff_t,sizeof(T)> {
    T* operator=( T* rhs ) {
        // "this" required here in strict ISO C++ because store_with_release is a dependent name
        return this->store_with_release(rhs);
    }
    T* operator->() const {
        return (*this);
    }
};

template<>
struct atomic<void*> {
private:
    void* volatile my_value;

public:
    typedef void* value_type;

    template<memory_semantics M>
    value_type compare_and_swap( value_type value, value_type comparand ) {
        return value_type(internal::atomic_traits<sizeof(value_type),M>::compare_and_swap(&my_value,internal::intptr(value),internal::intptr(comparand)));
    }

    value_type compare_and_swap( value_type value, value_type comparand ) {
        return compare_and_swap<__TBB_full_fence>(value,comparand);
    }

    template<memory_semantics M>
    value_type fetch_and_store( value_type value ) {
        return value_type(internal::atomic_traits<sizeof(value_type),M>::fetch_and_store(&my_value,internal::intptr(value)));
    }

    value_type fetch_and_store( value_type value ) {
        return fetch_and_store<__TBB_full_fence>(value);
    }

    operator value_type() const {
        return __TBB_load_with_acquire(this->my_value);
    }

    value_type operator=( value_type rhs ) {
        __TBB_store_with_release(this->my_value,rhs);
        return rhs;
    }
};

} // namespace tbb

#endif /* __TBB_atomic_H */

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