atomic.h

/*
    Copyright 2005-2011 Intel Corporation.  All Rights Reserved.

    The source code contained or described herein and all documents related
    to the source code ("Material") are owned by Intel Corporation or its
    suppliers or licensors.  Title to the Material remains with Intel
    Corporation or its suppliers and licensors.  The Material is protected
    by worldwide copyright laws and treaty provisions.  No part of the
    Material may be used, copied, reproduced, modified, published, uploaded,
    posted, transmitted, distributed, or disclosed in any way without
    Intel's prior express written permission.

    No license under any patent, copyright, trade secret or other
    intellectual property right is granted to or conferred upon you by
    disclosure or delivery of the Materials, either expressly, by
    implication, inducement, estoppel or otherwise.  Any license under such
    intellectual property rights must be express and approved by Intel in
    writing.
*/

#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"

#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
    // Workaround for overzealous compiler warnings 
    #pragma warning (push)
    #pragma warning (disable: 4244 4267)
#endif

namespace tbb {

enum memory_semantics {
    full_fence,
    acquire,
    release,
    relaxed
};

namespace internal {

#if __TBB_ATTRIBUTE_ALIGNED_PRESENT
    #define __TBB_DECL_ATOMIC_FIELD(t,f,a) t f  __attribute__ ((aligned(a)));
#elif __TBB_DECLSPEC_ALIGN_PRESENT
    #define __TBB_DECL_ATOMIC_FIELD(t,f,a) __declspec(align(a)) t f;
#else 
    #error Do not know syntax for forcing alignment.
#endif

template<size_t S>
struct atomic_rep;           // Primary template declared, but never defined.

template<>
struct atomic_rep<1> {       // Specialization
    typedef int8_t word;
    int8_t value;
};
template<>
struct atomic_rep<2> {       // Specialization
    typedef int16_t word;
    __TBB_DECL_ATOMIC_FIELD(int16_t,value,2)
};
template<>
struct atomic_rep<4> {       // Specialization
#if _MSC_VER && __TBB_WORDSIZE==4
    // Work-around that avoids spurious /Wp64 warnings
    typedef intptr_t word;
#else
    typedef int32_t word;
#endif
    __TBB_DECL_ATOMIC_FIELD(int32_t,value,4)
};
#if __TBB_64BIT_ATOMICS
template<>
struct atomic_rep<8> {       // Specialization
    typedef int64_t word;
    __TBB_DECL_ATOMIC_FIELD(int64_t,value,8)
};
#endif

template<size_t Size, memory_semantics M>
struct atomic_traits;        // Primary template declared, but not defined.

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

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

template<memory_semantics M>
struct atomic_load_store_traits;    // Primary template declaration

#define __TBB_DECL_ATOMIC_LOAD_STORE_PRIMITIVES(M)                      \
    template<> struct atomic_load_store_traits<M> {                     \
        template <typename T>                                           \
        inline static T load( const volatile T& location ) {            \
            return __TBB_load_##M( location );                          \
        }                                                               \
        template <typename T>                                           \
        inline static void store( volatile T& location, T value ) {     \
            __TBB_store_##M( location, value );                         \
        }                                                               \
    }

#if __TBB_USE_FENCED_ATOMICS
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(1,full_fence)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(2,full_fence)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(4,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(1,release)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(2,release)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(4,release)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(1,relaxed)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(2,relaxed)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(4,relaxed)
#if __TBB_64BIT_ATOMICS
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(8,full_fence)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(8,acquire)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(8,release)
__TBB_DECL_FENCED_ATOMIC_PRIMITIVES(8,relaxed)
#endif
#else /* !__TBB_USE_FENCED_ATOMICS */
__TBB_DECL_ATOMIC_PRIMITIVES(1)
__TBB_DECL_ATOMIC_PRIMITIVES(2)
__TBB_DECL_ATOMIC_PRIMITIVES(4)
#if __TBB_64BIT_ATOMICS
__TBB_DECL_ATOMIC_PRIMITIVES(8)
#endif
#endif /* !__TBB_USE_FENCED_ATOMICS */

__TBB_DECL_ATOMIC_LOAD_STORE_PRIMITIVES(full_fence);
__TBB_DECL_ATOMIC_LOAD_STORE_PRIMITIVES(acquire);
__TBB_DECL_ATOMIC_LOAD_STORE_PRIMITIVES(release);
__TBB_DECL_ATOMIC_LOAD_STORE_PRIMITIVES(relaxed);


#define __TBB_MINUS_ONE(T) (T(T(0)-T(1)))


template<typename T>
struct atomic_impl {
protected:
    atomic_rep<sizeof(T)> rep;
private:
    union converter {
        T value;
        typename atomic_rep<sizeof(T)>::word bits;
    };
public:
    typedef T value_type;

    template<memory_semantics M>
    value_type fetch_and_store( value_type value ) {
        converter u, w;
        u.value = value;
        w.bits = internal::atomic_traits<sizeof(value_type),M>::fetch_and_store(&rep.value,u.bits);
        return w.value;
    }

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

    template<memory_semantics M>
    value_type compare_and_swap( value_type value, value_type comparand ) {
        converter u, v, w;
        u.value = value;
        v.value = comparand;
        w.bits = internal::atomic_traits<sizeof(value_type),M>::compare_and_swap(&rep.value,u.bits,v.bits);
        return w.value;
    }

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

    operator value_type() const volatile {                // volatile qualifier here for backwards compatibility 
        converter w;
        w.bits = __TBB_load_with_acquire( rep.value );
        return w.value;
    }

    template<memory_semantics M>
    value_type load () const {
        converter u;
        u.bits = internal::atomic_load_store_traits<M>::load( rep.value );
        return u.value;
    }

    value_type load () const {
        return load<acquire>();
    }

    template<memory_semantics M>
    void store ( value_type value ) {
        converter u;
        u.value = value;
        internal::atomic_load_store_traits<M>::store( rep.value, u.bits );
    }

    void store ( value_type value ) {
        store<release>( value );
    }

protected:
    value_type store_with_release( value_type rhs ) {
        converter u;
        u.value = rhs;
        __TBB_store_with_release(rep.value,u.bits);
        return rhs;
    }
};


template<typename I, typename D, typename StepType>
struct atomic_impl_with_arithmetic: atomic_impl<I> {
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->rep.value, addend*sizeof(StepType) ));
    }

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

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));
    }
};

} /* Internal */


template<typename T>
struct atomic: internal::atomic_impl<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);
    }
    atomic<T>& operator=( const atomic<T>& rhs ) {this->store_with_release(rhs); return *this;}
};

#define __TBB_DECL_ATOMIC(T) \
    template<> struct atomic<T>: internal::atomic_impl_with_arithmetic<T,T,char> {  \
        T operator=( T rhs ) {return store_with_release(rhs);}  \
        atomic<T>& operator=( const atomic<T>& rhs ) {store_with_release(rhs); return *this;}  \
    };

#if __TBB_64BIT_ATOMICS
__TBB_DECL_ATOMIC(__TBB_LONG_LONG)
__TBB_DECL_ATOMIC(unsigned __TBB_LONG_LONG)
#else
// test_atomic will verify that sizeof(long long)==8
#endif
__TBB_DECL_ATOMIC(long)
__TBB_DECL_ATOMIC(unsigned long)

#if defined(_MSC_VER) && __TBB_WORDSIZE==4
/* Special version of __TBB_DECL_ATOMIC that avoids gratuitous warnings from cl /Wp64 option. 
   It is identical to __TBB_DECL_ATOMIC(unsigned) except that it replaces operator=(T) 
   with an operator=(U) that explicitly converts the U to a T.  Types T and U should be
   type synonyms on the platform.  Type U should be the wider variant of T from the
   perspective of /Wp64. */
#define __TBB_DECL_ATOMIC_ALT(T,U) \
    template<> struct atomic<T>: internal::atomic_impl_with_arithmetic<T,T,char> {  \
        T operator=( U rhs ) {return store_with_release(T(rhs));}  \
        atomic<T>& operator=( const atomic<T>& rhs ) {store_with_release(rhs); return *this;}  \
    };
__TBB_DECL_ATOMIC_ALT(unsigned,size_t)
__TBB_DECL_ATOMIC_ALT(int,ptrdiff_t)
#else
__TBB_DECL_ATOMIC(unsigned)
__TBB_DECL_ATOMIC(int)
#endif /* defined(_MSC_VER) && __TBB_WORDSIZE==4 */

__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_with_arithmetic<T*,ptrdiff_t,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);
    }
    atomic<T*>& operator=( const atomic<T*>& rhs ) {
        this->store_with_release(rhs); return *this;
    }
    T* operator->() const {
        return (*this);
    }
};

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

// Helpers to workaround ugly syntax of calling template member function of a
// template class with template argument dependent on template parameters.

template <memory_semantics M, typename T>
T load ( const atomic<T>& a ) { return a.template load<M>(); }

template <memory_semantics M, typename T>
void store ( atomic<T>& a, T value ) { return a.template store<M>(value); }

} // namespace tbb

#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
    #pragma warning (pop)
#endif // warnings 4244, 4267 are back

#endif /* __TBB_atomic_H */

---

Copyright © 2005-2011 Intel Corporation. All Rights Reserved.

Intel, Pentium, Intel Xeon, Itanium, Intel XScale and VTune are registered trademarks or trademarks of Intel Corporation or its subsidiaries in the United States and other countries.

* Other names and brands may be claimed as the property of others.