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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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#ifndef OS_CPU_LINUX_ZERO_ATOMIC_LINUX_ZERO_HPP
#define OS_CPU_LINUX_ZERO_ATOMIC_LINUX_ZERO_HPP

#include "runtime/os.hpp"

// Implementation of class atomic

template<size_t byte_size>
struct Atomic::PlatformAdd
  : Atomic::AddAndFetch<Atomic::PlatformAdd<byte_size> >
{
  template<typename I, typename D>
  D add_and_fetch(I add_value, D volatile* dest, atomic_memory_order order) const;
};

template<>
template<typename I, typename D>
inline D Atomic::PlatformAdd<4>::add_and_fetch(I add_value, D volatile* dest,
                                               atomic_memory_order order) const {
  STATIC_ASSERT(4 == sizeof(I));
  STATIC_ASSERT(4 == sizeof(D));

  return __sync_add_and_fetch(dest, add_value);
}

template<>
template<typename I, typename D>
inline D Atomic::PlatformAdd<8>::add_and_fetch(I add_value, D volatile* dest,
                                               atomic_memory_order order) const {
  STATIC_ASSERT(8 == sizeof(I));
  STATIC_ASSERT(8 == sizeof(D));
  return __sync_add_and_fetch(dest, add_value);
}

template<>
template<typename T>
inline T Atomic::PlatformXchg<4>::operator()(T exchange_value,
                                             T volatile* dest,
                                             atomic_memory_order order) const {
  STATIC_ASSERT(4 == sizeof(T));
  // __sync_lock_test_and_set is a bizarrely named atomic exchange
  // operation.  Note that some platforms only support this with the
  // limitation that the only valid value to store is the immediate
  // constant 1.  There is a test for this in JNI_CreateJavaVM().
  T result = __sync_lock_test_and_set (dest, exchange_value);
  // All atomic operations are expected to be full memory barriers
  // (see atomic.hpp). However, __sync_lock_test_and_set is not
  // a full memory barrier, but an acquire barrier. Hence, this added
  // barrier.
  __sync_synchronize();
  return result;
}

template<>
template<typename T>
inline T Atomic::PlatformXchg<8>::operator()(T exchange_value,
                                             T volatile* dest,
                                             atomic_memory_order order) const {
  STATIC_ASSERT(8 == sizeof(T));
  T result = __sync_lock_test_and_set (dest, exchange_value);
  __sync_synchronize();
  return result;
}

// No direct support for cmpxchg of bytes; emulate using int.
template<>
struct Atomic::PlatformCmpxchg<1> : Atomic::CmpxchgByteUsingInt {};

template<>
template<typename T>
inline T Atomic::PlatformCmpxchg<4>::operator()(T exchange_value,
                                                T volatile* dest,
                                                T compare_value,
                                                atomic_memory_order order) const {
  STATIC_ASSERT(4 == sizeof(T));
  return __sync_val_compare_and_swap(dest, compare_value, exchange_value);
}

template<>
template<typename T>
inline T Atomic::PlatformCmpxchg<8>::operator()(T exchange_value,
                                                T volatile* dest,
                                                T compare_value,
                                                atomic_memory_order order) const {
  STATIC_ASSERT(8 == sizeof(T));
  return __sync_val_compare_and_swap(dest, compare_value, exchange_value);
}

template<>
template<typename T>
inline T Atomic::PlatformLoad<8>::operator()(T const volatile* src) const {
  STATIC_ASSERT(8 == sizeof(T));
  volatile int64_t dest;
  os::atomic_copy64(reinterpret_cast<const volatile int64_t*>(src), reinterpret_cast<volatile int64_t*>(&dest));
  return PrimitiveConversions::cast<T>(dest);
}

template<>
template<typename T>
inline void Atomic::PlatformStore<8>::operator()(T volatile* dest,
                                                 T store_value) const {
  STATIC_ASSERT(8 == sizeof(T));
  os::atomic_copy64(reinterpret_cast<const volatile int64_t*>(&store_value), reinterpret_cast<volatile int64_t*>(dest));
}

#endif // OS_CPU_LINUX_ZERO_ATOMIC_LINUX_ZERO_HPP