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//                        Kokkos v. 2.0
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/// \file Kokkos_Atomic.hpp
/// \brief Atomic functions
///
/// This header file defines prototypes for the following atomic functions:
///   - exchange
///   - compare and exchange
///   - add
///
/// Supported types include:
///   - signed and unsigned 4 and 8 byte integers
///   - float
///   - double
///
/// They are implemented through GCC compatible intrinsics, OpenMP
/// directives and native CUDA intrinsics.
///
/// Including this header file requires one of the following
/// compilers:
///   - NVCC (for CUDA device code only)
///   - GCC (for host code only)
///   - Intel (for host code only)
///   - A compiler that supports OpenMP 3.1 (for host code only)

#ifndef KOKKOS_ATOMIC_HPP
#define KOKKOS_ATOMIC_HPP

#include <Kokkos_Macros.hpp>
#include <Kokkos_HostSpace.hpp>
#include <impl/Kokkos_Traits.hpp>

//----------------------------------------------------------------------------
#if defined(_WIN32)
#define KOKKOS_ATOMICS_USE_WINDOWS
#else
#if defined( __CUDA_ARCH__ ) && defined( KOKKOS_HAVE_CUDA )

// Compiling NVIDIA device code, must use Cuda atomics:

#define KOKKOS_ATOMICS_USE_CUDA

#elif ! defined( KOKKOS_ATOMICS_USE_GCC ) && \
      ! defined( KOKKOS_ATOMICS_USE_INTEL ) && \
      ! defined( KOKKOS_ATOMICS_USE_OMP31 )

// Compiling for non-Cuda atomic implementation has not been pre-selected.
// Choose the best implementation for the detected compiler.
// Preference: GCC, INTEL, OMP31

#if defined( KOKKOS_COMPILER_GNU ) || \
    defined( KOKKOS_COMPILER_CLANG ) || \
    ( defined ( KOKKOS_COMPILER_NVCC ) && defined ( __GNUC__ ) )

#define KOKKOS_ATOMICS_USE_GCC

#elif defined( KOKKOS_COMPILER_INTEL ) || \
      defined( KOKKOS_COMPILER_CRAYC )

#define KOKKOS_ATOMICS_USE_INTEL

#elif defined( _OPENMP ) && ( 201107 <= _OPENMP )

#define KOKKOS_ATOMICS_USE_OMP31

#else

#error "KOKKOS_ATOMICS_USE : Unsupported compiler"

#endif

#endif /* Not pre-selected atomic implementation */
#endif

//----------------------------------------------------------------------------

// Forward decalaration of functions supporting arbitrary sized atomics
// This is necessary since Kokkos_Atomic.hpp is internally included very early
// through Kokkos_HostSpace.hpp as well as the allocation tracker.
#ifdef KOKKOS_HAVE_CUDA
namespace Kokkos {
namespace Impl {
/// \brief Aquire a lock for the address
///
/// This function tries to aquire the lock for the hash value derived
/// from the provided ptr. If the lock is successfully aquired the
/// function returns true. Otherwise it returns false.
__device__ inline
bool lock_address_cuda_space(void* ptr);

/// \brief Release lock for the address
///
/// This function releases the lock for the hash value derived
/// from the provided ptr. This function should only be called
/// after previously successfully aquiring a lock with
/// lock_address.
__device__ inline
void unlock_address_cuda_space(void* ptr);
}
}
#endif


namespace Kokkos {
template <typename T>
KOKKOS_INLINE_FUNCTION
void atomic_add(volatile T * const dest, const T src);

// Atomic increment
template<typename T>
KOKKOS_INLINE_FUNCTION
void atomic_increment(volatile T* a);

template<typename T>
KOKKOS_INLINE_FUNCTION
void atomic_decrement(volatile T* a);
}

#if ! defined(_WIN32)
#include<impl/Kokkos_Atomic_Assembly_X86.hpp>
#endif

namespace Kokkos {


inline
const char * atomic_query_version()
{
#if defined( KOKKOS_ATOMICS_USE_CUDA )
  return "KOKKOS_ATOMICS_USE_CUDA" ;
#elif defined( KOKKOS_ATOMICS_USE_GCC )
  return "KOKKOS_ATOMICS_USE_GCC" ;
#elif defined( KOKKOS_ATOMICS_USE_INTEL )
  return "KOKKOS_ATOMICS_USE_INTEL" ;
#elif defined( KOKKOS_ATOMICS_USE_OMP31 )
  return "KOKKOS_ATOMICS_USE_OMP31" ;
#elif defined( KOKKOS_ATOMICS_USE_WINDOWS )
  return "KOKKOS_ATOMICS_USE_WINDOWS";
#endif
}

} // namespace Kokkos

#ifdef _WIN32
#include "impl/Kokkos_Atomic_Windows.hpp"
#else
//#include "impl/Kokkos_Atomic_Assembly_X86.hpp"

//----------------------------------------------------------------------------
// Atomic exchange
//
// template< typename T >
// T atomic_exchange( volatile T* const dest , const T val )
// { T tmp = *dest ; *dest = val ; return tmp ; }

#include "impl/Kokkos_Atomic_Exchange.hpp"

//----------------------------------------------------------------------------
// Atomic compare-and-exchange
//
// template<class T>
// bool atomic_compare_exchange_strong(volatile T* const dest, const T compare, const T val)
// { bool equal = compare == *dest ; if ( equal ) { *dest = val ; } return equal ; }

#include "impl/Kokkos_Atomic_Compare_Exchange_Strong.hpp"

//----------------------------------------------------------------------------
// Atomic fetch and add
//
// template<class T>
// T atomic_fetch_add(volatile T* const dest, const T val)
// { T tmp = *dest ; *dest += val ; return tmp ; }

#include "impl/Kokkos_Atomic_Fetch_Add.hpp"

//----------------------------------------------------------------------------
// Atomic fetch and sub
//
// template<class T>
// T atomic_fetch_sub(volatile T* const dest, const T val)
// { T tmp = *dest ; *dest -= val ; return tmp ; }

#include "impl/Kokkos_Atomic_Fetch_Sub.hpp"

//----------------------------------------------------------------------------
// Atomic fetch and or
//
// template<class T>
// T atomic_fetch_or(volatile T* const dest, const T val)
// { T tmp = *dest ; *dest = tmp | val ; return tmp ; }

#include "impl/Kokkos_Atomic_Fetch_Or.hpp"

//----------------------------------------------------------------------------
// Atomic fetch and and
//
// template<class T>
// T atomic_fetch_and(volatile T* const dest, const T val)
// { T tmp = *dest ; *dest = tmp & val ; return tmp ; }

#include "impl/Kokkos_Atomic_Fetch_And.hpp"
#endif /*Not _WIN32*/

//----------------------------------------------------------------------------
// Memory fence
//
// All loads and stores from this thread will be globally consistent before continuing
//
// void memory_fence() {...};
#include "impl/Kokkos_Memory_Fence.hpp"

//----------------------------------------------------------------------------
// Provide volatile_load and safe_load
//
// T volatile_load(T const volatile * const ptr);
//
// T const& safe_load(T const * const ptr);
// XEON PHI
// T safe_load(T const * const ptr

#include "impl/Kokkos_Volatile_Load.hpp"

#ifndef _WIN32
#include "impl/Kokkos_Atomic_Generic.hpp"
#endif
//----------------------------------------------------------------------------
// This atomic-style macro should be an inlined function, not a macro

#if defined( KOKKOS_COMPILER_GNU ) && !defined(__PGIC__)

  #define KOKKOS_NONTEMPORAL_PREFETCH_LOAD(addr) __builtin_prefetch(addr,0,0)
  #define KOKKOS_NONTEMPORAL_PREFETCH_STORE(addr) __builtin_prefetch(addr,1,0)

#else

  #define KOKKOS_NONTEMPORAL_PREFETCH_LOAD(addr) ((void)0)
  #define KOKKOS_NONTEMPORAL_PREFETCH_STORE(addr) ((void)0)

#endif

//----------------------------------------------------------------------------

#endif /* KOKKOS_ATOMIC_HPP */

