//
// Copyright (c) 2009 Advanced Micro Devices, Inc. All rights reserved.
//

/*! \file atomic.hpp
 *  \brief  Declarations for Memory order access and Atomic operations.
 *
 *  \author Laurent Morichetti (laurent.morichetti@amd.com)
 *  \date   October 2008
 */

#ifndef ATOMIC_HPP_
#define ATOMIC_HPP_

#include "top.hpp"

#include <type_traits>

#ifdef _WIN32
#include <intrin.h>
#elif defined(ATI_ARCH_X86)
#include <emmintrin.h>
#include <xmmintrin.h>
#endif  // !_WIN32

#include <atomic>
#include <utility>

namespace amd {

/*! \addtogroup Threads
 *  @{
 *
 *  \addtogroup Atomic Atomic Operations
 *  @{
 */

/*! \brief Static functions for atomic operations.
 */
class AtomicOperation : AllStatic {
 private:
  //! Template to specialize atomic intrinsics on register size.
  template <int N> struct Intrinsics {
    /*! \brief %Atomic add.
     *
     *  Atomically add \a inc to \a *dest and return the prior value.
     */
    template <typename T> static inline T add(T increment, volatile T* dest);

    /*! \brief %Atomic exchange.
     *
     *  Atomically exchange value with *dest and return the prior value.
     */
    template <typename T> static inline T swap(T value, volatile T* dest);

    /*! \brief %Atomic compare and exchange.
     *
     *  Atomically compare and xchge value with *dest if *dest == compare.
     *  Return the prior value.
     */
    template <typename T> static inline T compareAndSwap(T compare, volatile T* dest, T value);

    /*! \brief %Atomic increment.
     *
     *  Atomically increment *dest and return the prior value.
     */
    template <typename T> static inline T increment(volatile T* dest);

    /*! \brief %Atomic exchange.
     *
     *  Atomically decrement *dest and return the prior value.
     */
    template <typename T> static inline T decrement(volatile T* dest);

    /*! \brief %Atomic or.
     *
     *  Atomically or \a mask to \a *dest and return the prior value.
     */
    template <typename T> static inline T _or(T mask, volatile T* dest);

    /*! \brief %Atomic and.
     *
     *  Atomically and \a mask to \a *dest and return the prior value.
     */
    template <typename T> static inline T _and(T mask, volatile T* dest);
  };

 public:
  /*! \brief %Atomic add.
   *
   *  Atomically add \a inc to \a *dest and return the prior value.
   */
  template <typename T> static T add(T inc, volatile T* dest) {
    return Intrinsics<sizeof(T)>::add((T)inc, dest);
  }

  /*! \brief %Atomic exchange.
   *
   *  Atomically exchange value with *dest and return the prior value.
   */
  template <typename T> static T swap(T value, volatile T* dest) {
    return Intrinsics<sizeof(T)>::swap(value, dest);
  }

  /*! \brief %Atomic compare and exchange.
   *
   *  Atomically compare and exchange value with *dest if *dest == compare.
   *  Return the prior value.
   */
  template <typename T> static T compareAndSwap(T compare, volatile T* dest, T value) {
    return Intrinsics<sizeof(T)>::compareAndSwap(compare, dest, value);
  }

  /*! \brief %Atomic increment.
   *
   *  Atomically increment *dest and return the prior value.
   */
  template <typename T> static T increment(volatile T* dest) {
    return Intrinsics<sizeof(T)>::increment(dest);
  }

  /*! \brief %Atomic decrement.
   *
   *  Atomically decrement *dest and return the prior value.
   */
  template <typename T> static T decrement(volatile T* dest) {
    return Intrinsics<sizeof(T)>::decrement(dest);
  }

  /*! \brief %Atomic or.
   *
   *  Atomically or \a mask to \a *dest and return the prior value.
   */
  template <typename T> static T _or(T mask, volatile T* dest) {
    return Intrinsics<sizeof(T)>::_or((T)mask, dest);
  }

  /*! \brief %Atomic and.
   *
   *  Atomically or \a mask to \a *dest and return the prior value.
   */
  template <typename T> static T _and(T mask, volatile T* dest) {
    return Intrinsics<sizeof(T)>::_and((T)mask, dest);
  }
};

/*@}*/

#if defined(_MSC_VER)

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<4>::add(T increment, volatile T* dest) {
  return (T)_InterlockedExchangeAdd((volatile long*)dest, (long)increment);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<4>::swap(T value, volatile T* dest) {
  return (T)_InterlockedExchange((volatile long*)dest, (long)value);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<4>::compareAndSwap(T compare, volatile T* dest, T value) {
  return (T)_InterlockedCompareExchange((volatile long*)dest, (long)value, (long)compare);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<4>::increment(volatile T* dest) {
  return (T)(_InterlockedIncrement((volatile long*)dest) - 1L);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<4>::decrement(volatile T* dest) {
  return (T)(_InterlockedDecrement((volatile long*)dest) + 1L);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<4>::_or(T mask, volatile T* dest) {
  return (T)_InterlockedOr((volatile long*)dest, (long)mask);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<4>::_and(T mask, volatile T* dest) {
  return (T)_InterlockedAnd((volatile long*)dest, (long)mask);
}

#ifdef _WIN64

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<8>::add(T increment, volatile T* dest) {
  return (T)_InterlockedExchangeAdd64((volatile __int64*)dest, (__int64)increment);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<8>::swap(T value, volatile T* dest) {
  return (T)_InterlockedExchange64((volatile __int64*)dest, (__int64)value);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<8>::compareAndSwap(T compare, volatile T* dest, T value) {
  return (T)_InterlockedCompareExchange64((volatile __int64*)dest, (__int64)value,
                                          (__int64)compare);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<8>::increment(volatile T* dest) {
  return (T)(_InterlockedIncrement64((volatile __int64*)dest) - 1LL);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<8>::decrement(volatile T* dest) {
  return (T)(_InterlockedDecrement64((volatile __int64*)dest) + 1LL);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<8>::_or(T mask, volatile T* dest) {
  return (T)_InterlockedOr64((volatile long*)dest, (long)mask);
}

template <>
template <typename T>
inline T AtomicOperation::Intrinsics<8>::_and(T mask, volatile T* dest) {
  return (T)_InterlockedAnd64((volatile long*)dest, (long)mask);
}

#endif  // _LP64

#elif defined(__GNUC__)

template <int N>
template <typename T>
inline T AtomicOperation::Intrinsics<N>::add(T inc, volatile T* dest) {
  return __sync_fetch_and_add(dest, inc);
}

template <int N>
template <typename T>
inline T AtomicOperation::Intrinsics<N>::swap(T value, volatile T* dest) {
  return __sync_lock_test_and_set(dest, value);
}

template <int N>
template <typename T>
inline T AtomicOperation::Intrinsics<N>::compareAndSwap(T compare, volatile T* dest, T value) {
  return __sync_val_compare_and_swap(dest, compare, value);
}

template <int N>
template <typename T>
inline T AtomicOperation::Intrinsics<N>::increment(volatile T* dest) {
  return add(T(1), dest);
}

template <int N>
template <typename T>
inline T AtomicOperation::Intrinsics<N>::decrement(volatile T* dest) {
  return add(T(-1), dest);
}

template <int N>
template <typename T>
inline T AtomicOperation::Intrinsics<N>::_or(T mask, volatile T* dest) {
  return __sync_fetch_and_or(dest, mask);
}

template <int N>
template <typename T>
inline T AtomicOperation::Intrinsics<N>::_and(T mask, volatile T* dest) {
  return __sync_fetch_and_and(dest, mask);
}

#else
#error Unimplemented
#endif

/*! \addtogroup Atomic Atomic Operations
 *  @{
 */

/*! \brief A variable of type T with atomic properties.
 */
template <typename T> class Atomic {
 private:
  typedef typename std::remove_volatile<
      typename std::remove_pointer<typename std::remove_reference<T>::type>::type>::type value_type;
  typename std::add_volatile<T>::type value_;  //!< \brief The variable.

 public:
  //! Construct a new %Atomic variable of type T.
  Atomic() : value_(T(0)) {}
  //! Construct a new %Atomic variable of type T from \a value.
  Atomic(T value) : value_(value) {}
  //! Construct a new %Atomic variable of type T from another %Atomic.
  Atomic(const Atomic<T>& atomic) : value_(atomic.value_) {}
  //! Copy value into this %Atomic variable.
  Atomic<T>& operator=(T value) {
    value_ = value;
    return *this;
  }

  //! Return the %Atomic variable value.
  operator T() const { return T(value_); }
  //! Return the %Atomic variable value.
  T operator->() const { return T(value_); }
  //! Return the %Atomic variable's address.
  typename std::add_pointer<typename std::add_volatile<value_type>::type>::type operator&() {
    return &value_;
  }

  //! Atomically add \a inc to this variable.
  Atomic<T>& operator+=(value_type inc) {
    if (std::is_pointer<T>::value) {
      inc *= sizeof(typename std::remove_pointer<T>::type);
    }
    AtomicOperation::add(inc, &value_);
    return *this;
  }

  //! Atomically subtract \a inc to this variable.
  Atomic<T>& operator-=(value_type inc) {
    value_type modifier = 0;
    if (std::is_pointer<T>::value) {
      inc *= sizeof(typename std::remove_pointer<T>::type);
    }
    AtomicOperation::add(modifier - inc, &value_);
    return *this;
  }

  //! Atomically OR \a value to this variable.
  Atomic<T>& operator|=(value_type mask) {
    AtomicOperation::_or(mask, &value_);
    return *this;
  }

  //! Atomically AND \a value to this variable.
  Atomic<T>& operator&=(value_type mask) {
    AtomicOperation::_and(mask, &value_);
    return *this;
  }

  //! Atomically increment this variable and return its new value.
  typename std::remove_reference<T>::type operator++() {
    if (std::is_pointer<T>::value) {
      value_type inc = static_cast<value_type>(sizeof(typename std::remove_pointer<T>::type));
      return AtomicOperation::add(inc, &value_) + 1;
    } else {
      return AtomicOperation::increment(&value_) + 1;
    }
  }

  //! Atomically decrement this variable and return its new value.
  typename std::remove_reference<T>::type operator--() {
    if (std::is_pointer<T>::value) {
      value_type inc =
          static_cast<value_type>(-static_cast<typename std::make_signed<value_type>::type>(
              sizeof(typename std::remove_pointer<T>::type)));
      return AtomicOperation::add(inc, &value_) - 1;
    } else {
      return AtomicOperation::decrement(&value_) - 1;
    }
  }

  //! Atomically increment this variable and return its previous value.
  typename std::remove_reference<T>::type operator++(int) {
    if (std::is_pointer<T>::value) {
      value_type inc = static_cast<value_type>(sizeof(typename std::remove_pointer<T>::type));
      return AtomicOperation::add(inc, &value_);
    } else {
      return AtomicOperation::increment(&value_);
    }
  }

  //! Atomically decrement this variable and return its previous value.
  T operator--(int) {
    if (std::is_pointer<T>::value) {
      value_type inc =
          static_cast<value_type>(-static_cast<typename std::make_signed<value_type>::type>(
              sizeof(typename std::remove_pointer<T>::type)));
      return AtomicOperation::add(inc, &value_);
    } else {
      return AtomicOperation::decrement(&value_);
    }
  }

  /*! \brief Atomically compare this variable with \a compare and set
   *  to value if equals
   */
  bool compareAndSet(T compare, T value) {
    return compare == AtomicOperation::compareAndSwap(compare, &value_, value);
  }

  //! Atomically set this variable to \a value and return its previous value.
  T swap(T value) { return AtomicOperation::swap(value, &value_); }

  /*! \brief Execute a stores fence followed by a store to this variable.
   *
   *  This storeRelease operation ensures that all store to memory operations
   *  preceding this function will be globally visible before the update to
   *  this variable's value.
   */
  void storeRelease(T value) {
    std::atomic_thread_fence(std::memory_order_release);
    value_ = value;
  }

  /*! \brief Execute a load from this variable followed by a loads fence.
   *
   *  This loadAcquire operation ensures that all load from memory operations
   *  following this function will be globally visible after the read from
   *  this variable's value.
   */
  T loadAcquire() const {
    T value = value_;
    std::atomic_thread_fence(std::memory_order_acquire);
    return value;
  }
};

//! Helper function to tie an Atomic<T&> to a variable of type T.
template <typename T> inline Atomic<T&> make_atomic(T& t) { return Atomic<T&>(t); }


/*! @}
 *  @}
 */

}  // namespace amd

#endif /*ATOMIC_HPP_*/