cas64strong.hpp

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#ifndef BOOST_DETAIL_ATOMIC_CAS64STRONG_HPP
#define BOOST_DETAIL_ATOMIC_CAS64STRONG_HPP

//  Distributed under the Boost Software License, Version 1.0.
//  See accompanying file LICENSE_1_0.txt or copy at
//  http://www.boost.org/LICENSE_1_0.txt)
//
//  Copyright (c) 2011 Helge Bahmann

// Build 64-bit atomic operation from platform_cmpxchg64_strong
// primitive. It is assumed that 64-bit loads/stores are not
// atomic, so they are funnelled through cmpxchg as well.

#include <boost/memory_order.hpp>
#include <boost/atomic/detail/base.hpp>

namespace boost {
namespace detail {
namespace atomic {

/* integral types */

template<typename T, bool Sign>
class base_atomic<T, int, 8, Sign> {
        typedef base_atomic this_type;
        typedef T value_type;
        typedef T difference_type;
public:
        explicit base_atomic(value_type v) : v_(v) {}
        base_atomic(void) {}
        
        void
        store(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type expected = v_;
                do {
                } while (!compare_exchange_strong(expected, v, order, memory_order_relaxed));
        }
        
        value_type
        load(memory_order order = memory_order_seq_cst) const volatile
        {
                value_type v = const_cast<const volatile value_type &>(v_);
                do {
                } while (!const_cast<base_atomic *>(this)->compare_exchange_strong(v, v, order, memory_order_relaxed));
                return v;
        }
        
        value_type
        exchange(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, v, order, memory_order_relaxed));
                return original;
        }
        
        bool
        compare_exchange_weak(
                value_type & expected,
                value_type desired,
                memory_order success_order,
                memory_order failure_order) volatile
        {
                return compare_exchange_strong(expected, desired, success_order, failure_order);
        }
        
        bool
        compare_exchange_strong(
                value_type & expected,
                value_type desired,
                memory_order success_order,
                memory_order failure_order) volatile
        {
                platform_fence_before(success_order);
                
                bool success = platform_cmpxchg64_strong(expected, desired, &v_);
                
                if (success) {
                        platform_fence_after(success_order);
                } else {
                        platform_fence_after(failure_order);
                }
                
                return success;
        }
        
        value_type
        fetch_add(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original + v, order, memory_order_relaxed));
                return original;
        }
        
        value_type
        fetch_sub(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original - v, order, memory_order_relaxed));
                return original;
        }
        
        value_type
        fetch_and(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original & v, order, memory_order_relaxed));
                return original;
        }
        
        value_type
        fetch_or(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original | v, order, memory_order_relaxed));
                return original;
        }
        
        value_type
        fetch_xor(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original ^ v, order, memory_order_relaxed));
                return original;
        }
        
        bool
        is_lock_free(void) const volatile
        {
                return true;
        }
        
        BOOST_ATOMIC_DECLARE_INTEGRAL_OPERATORS
private:
        base_atomic(const base_atomic &) /* = delete */ ;
        void operator=(const base_atomic &) /* = delete */ ;
        value_type v_;
};

/* pointer types */

template<bool Sign>
class base_atomic<void *, void *, 8, Sign> {
        typedef base_atomic this_type;
        typedef void * value_type;
        typedef ptrdiff_t difference_type;
public:
        explicit base_atomic(value_type v) : v_(v) {}
        base_atomic(void) {}
        
        void
        store(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type expected = v_;
                do {
                } while (!compare_exchange_strong(expected, v, order, memory_order_relaxed));
        }
        
        value_type
        load(memory_order order = memory_order_seq_cst) const volatile
        {
                value_type v = const_cast<const volatile value_type &>(v_);
                do {
                } while (!const_cast<base_atomic *>(this)->compare_exchange_strong(v, v, order, memory_order_relaxed));
                return v;
        }
        
        value_type
        exchange(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, v, order, memory_order_relaxed));
                return original;
        }
        
        bool
        compare_exchange_weak(
                value_type & expected,
                value_type desired,
                memory_order success_order,
                memory_order failure_order) volatile
        {
                return compare_exchange_strong(expected, desired, success_order, failure_order);
        }
        
        bool
        compare_exchange_strong(
                value_type & expected,
                value_type desired,
                memory_order success_order,
                memory_order failure_order) volatile
        {
                platform_fence_before(success_order);
                
                bool success = platform_cmpxchg64_strong(expected, desired, &v_);
                
                if (success) {
                        platform_fence_after(success_order);
                } else {
                        platform_fence_after(failure_order);
                }
                
                return success;
        }
        
        value_type
        fetch_add(difference_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original + v, order, memory_order_relaxed));
                return original;
        }
        
        value_type
        fetch_sub(difference_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original - v, order, memory_order_relaxed));
                return original;
        }
        
        bool
        is_lock_free(void) const volatile
        {
                return true;
        }
        
        BOOST_ATOMIC_DECLARE_BASE_OPERATORS
private:
        base_atomic(const base_atomic &) /* = delete */ ;
        void operator=(const base_atomic &) /* = delete */ ;
        value_type v_;
};

template<typename T, bool Sign>
class base_atomic<T *, void *, 8, Sign> {
        typedef base_atomic this_type;
        typedef T * value_type;
        typedef ptrdiff_t difference_type;
public:
        explicit base_atomic(value_type v) : v_(v) {}
        base_atomic(void) {}
        
        void
        store(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type expected = v_;
                do {
                } while (!compare_exchange_strong(expected, v, order, memory_order_relaxed));
        }
        
        value_type
        load(memory_order order = memory_order_seq_cst) const volatile
        {
                value_type v = const_cast<const volatile value_type &>(v_);
                do {
                } while (!const_cast<base_atomic *>(this)->compare_exchange_strong(v, v, order, memory_order_relaxed));
                return v;
        }
        
        value_type
        exchange(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, v, order, memory_order_relaxed));
                return original;
        }
        
        bool
        compare_exchange_weak(
                value_type & expected,
                value_type desired,
                memory_order success_order,
                memory_order failure_order) volatile
        {
                return compare_exchange_strong(expected, desired, success_order, failure_order);
        }
        
        bool
        compare_exchange_strong(
                value_type & expected,
                value_type desired,
                memory_order success_order,
                memory_order failure_order) volatile
        {
                platform_fence_before(success_order);
                
                bool success = platform_cmpxchg64_strong(expected, desired, &v_);
                
                if (success) {
                        platform_fence_after(success_order);
                } else {
                        platform_fence_after(failure_order);
                }
                
                return success;
        }
        
        value_type
        fetch_add(difference_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original + v, order, memory_order_relaxed));
                return original;
        }
        
        value_type
        fetch_sub(difference_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, original - v, order, memory_order_relaxed));
                return original;
        }
        
        bool
        is_lock_free(void) const volatile
        {
                return true;
        }
        
        BOOST_ATOMIC_DECLARE_POINTER_OPERATORS
private:
        base_atomic(const base_atomic &) /* = delete */ ;
        void operator=(const base_atomic &) /* = delete */ ;
        value_type v_;
};

/* generic types */

template<typename T, bool Sign>
class base_atomic<T, void, 8, Sign> {
        typedef base_atomic this_type;
        typedef T value_type;
        typedef uint64_t storage_type;
public:
        explicit base_atomic(value_type v) : v_(0)
        {
                memcpy(&v_, &v, sizeof(value_type));
        }
        base_atomic(void) : v_(0) {}
        
        void
        store(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type expected;
                memcpy(&expected, const_cast<storage_type *>(&v_), sizeof(value_type));
                do {
                } while (!compare_exchange_strong(expected, v, order, memory_order_relaxed));
        }
        
        value_type
        load(memory_order order = memory_order_seq_cst) const volatile
        {
                value_type v;
                memcpy(&v, const_cast<storage_type *>(&v_), sizeof(value_type));
                do {
                } while (!const_cast<base_atomic *>(this)->compare_exchange_strong(v, v, order, memory_order_relaxed));
                return v;
        }
        
        value_type
        exchange(value_type v, memory_order order = memory_order_seq_cst) volatile
        {
                value_type original = load(memory_order_relaxed);
                do {
                } while (!compare_exchange_weak(original, v, order, memory_order_relaxed));
                return original;
        }
        
        bool
        compare_exchange_weak(
                value_type & expected,
                value_type desired,
                memory_order success_order,
                memory_order failure_order) volatile
        {
                return compare_exchange_strong(expected, desired, success_order, failure_order);
        }
        
        bool
        compare_exchange_strong(
                value_type & expected,
                value_type desired,
                memory_order success_order,
                memory_order failure_order) volatile
        {
                
                storage_type expected_s = 0, desired_s = 0;
                memcpy(&expected_s, &expected, sizeof(value_type));
                memcpy(&desired_s, &desired, sizeof(value_type));
                
                platform_fence_before(success_order);
                bool success = platform_cmpxchg64_strong(expected_s, desired_s, &v_);
                
                if (success) {
                        platform_fence_after(success_order);
                } else {
                        platform_fence_after(failure_order);
                        memcpy(&expected, &expected_s, sizeof(value_type));
                }
                
                return success;
        }
        
        bool
        is_lock_free(void) const volatile
        {
                return true;
        }
        
        BOOST_ATOMIC_DECLARE_BASE_OPERATORS
private:
        base_atomic(const base_atomic &) /* = delete */ ;
        void operator=(const base_atomic &) /* = delete */ ;
        storage_type v_;
};

}
}
}

#endif