/*
//@HEADER
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//                        Kokkos v. 2.0
//              Copyright (2014) Sandia Corporation
//
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
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// 1. Redistributions of source code must retain the above copyright
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#ifndef KOKKOS_CUDA_HPP
#define KOKKOS_CUDA_HPP

#include <Kokkos_Macros.hpp>
#if defined( KOKKOS_ENABLE_CUDA )

#include <Kokkos_Core_fwd.hpp>

#include <iosfwd>
#include <vector>

#include <Kokkos_CudaSpace.hpp>

#include <Kokkos_Parallel.hpp>
#include <Kokkos_TaskScheduler.hpp>
#include <Kokkos_Layout.hpp>
#include <Kokkos_ScratchSpace.hpp>
#include <Kokkos_MemoryTraits.hpp>
#include <impl/Kokkos_Tags.hpp>


/*--------------------------------------------------------------------------*/

namespace Kokkos {
namespace Impl {
class CudaExec ;
} // namespace Impl
} // namespace Kokkos

/*--------------------------------------------------------------------------*/

namespace Kokkos {

/// \class Cuda
/// \brief Kokkos Execution Space that uses CUDA to run on GPUs.
///
/// An "execution space" represents a parallel execution model.  It tells Kokkos
/// how to parallelize the execution of kernels in a parallel_for or
/// parallel_reduce.  For example, the Threads execution space uses Pthreads or
/// C++11 threads on a CPU, the OpenMP execution space uses the OpenMP language
/// extensions, and the Serial execution space executes "parallel" kernels
/// sequentially.  The Cuda execution space uses NVIDIA's CUDA programming
/// model to execute kernels in parallel on GPUs.
class Cuda {
public:
  //! \name Type declarations that all Kokkos execution spaces must provide.
  //@{

  //! Tag this class as a kokkos execution space
  typedef Cuda                  execution_space ;

#if defined( KOKKOS_ENABLE_CUDA_UVM )
  //! This execution space's preferred memory space.
  typedef CudaUVMSpace          memory_space ;
#else
  //! This execution space's preferred memory space.
  typedef CudaSpace             memory_space ;
#endif

  //! This execution space preferred device_type
  typedef Kokkos::Device<execution_space,memory_space> device_type;

  //! The size_type best suited for this execution space.
  typedef memory_space::size_type  size_type ;

  //! This execution space's preferred array layout.
  typedef LayoutLeft            array_layout ;

  //!
  typedef ScratchMemorySpace< Cuda >  scratch_memory_space ;

  //@}
  //--------------------------------------------------
  //! \name Functions that all Kokkos devices must implement.
  //@{

  /// \brief True if and only if this method is being called in a
  ///   thread-parallel function.
  KOKKOS_INLINE_FUNCTION static int in_parallel() {
#if defined( __CUDA_ARCH__ )
    return true;
#else
    return false;
#endif
  }

  /** \brief  Set the device in a "sleep" state.
   *
   * This function sets the device in a "sleep" state in which it is
   * not ready for work.  This may consume less resources than if the
   * device were in an "awake" state, but it may also take time to
   * bring the device from a sleep state to be ready for work.
   *
   * \return True if the device is in the "sleep" state, else false if
   *   the device is actively working and could not enter the "sleep"
   *   state.
   */
  static bool sleep();

  /// \brief Wake the device from the 'sleep' state so it is ready for work.
  ///
  /// \return True if the device is in the "ready" state, else "false"
  ///  if the device is actively working (which also means that it's
  ///  awake).
  static bool wake();

  /// \brief Wait until all dispatched functors complete.
  ///
  /// The parallel_for or parallel_reduce dispatch of a functor may
  /// return asynchronously, before the functor completes.  This
  /// method does not return until all dispatched functors on this
  /// device have completed.
  static void fence();

  //! Free any resources being consumed by the device.
  static void finalize();

  //! Has been initialized
  static int is_initialized();

  /** \brief  Return the maximum amount of concurrency.  */
  static int concurrency();

  //! Print configuration information to the given output stream.
  static void print_configuration( std::ostream & , const bool detail = false );

  //@}
  //--------------------------------------------------
  //! \name  Cuda space instances

  ~Cuda() {}
  Cuda();
  explicit Cuda( const int instance_id );

  Cuda( Cuda && ) = default ;
  Cuda( const Cuda & ) = default ;
  Cuda & operator = ( Cuda && ) = default ;
  Cuda & operator = ( const Cuda & ) = default ;

  //--------------------------------------------------------------------------
  //! \name Device-specific functions
  //@{

  struct SelectDevice {
    int cuda_device_id ;
    SelectDevice() : cuda_device_id(0) {}
    explicit SelectDevice( int id ) : cuda_device_id( id ) {}
  };

  //! Initialize, telling the CUDA run-time library which device to use.
  static void initialize( const SelectDevice = SelectDevice()
                        , const size_t num_instances = 1 );

  /// \brief Cuda device architecture of the selected device.
  ///
  /// This matches the __CUDA_ARCH__ specification.
  static size_type device_arch();

  //! Query device count.
  static size_type detect_device_count();

  /** \brief  Detect the available devices and their architecture
   *          as defined by the __CUDA_ARCH__ specification.
   */
  static std::vector<unsigned> detect_device_arch();

  cudaStream_t cuda_stream() const { return m_stream ; }
  int          cuda_device() const { return m_device ; }

  //@}
  //--------------------------------------------------------------------------

  static const char* name();

private:

  int          m_device ;
  cudaStream_t m_stream ;
};

} // namespace Kokkos

/*--------------------------------------------------------------------------*/
/*--------------------------------------------------------------------------*/

namespace Kokkos {
namespace Impl {

template<>
struct MemorySpaceAccess
  < Kokkos::CudaSpace
  , Kokkos::Cuda::scratch_memory_space
  >
{
  enum { assignable = false };
  enum { accessible = true };
  enum { deepcopy   = false };
};

#if defined( KOKKOS_ENABLE_CUDA_UVM )

// If forcing use of UVM everywhere
// then must assume that CudaUVMSpace
// can be a stand-in for CudaSpace.
// This will fail when a strange host-side execution space
// that defines CudaUVMSpace as its preferredmemory space.

template<>
struct MemorySpaceAccess
  < Kokkos::CudaUVMSpace
  , Kokkos::Cuda::scratch_memory_space
  >
{
  enum { assignable = false };
  enum { accessible = true };
  enum { deepcopy   = false };
};

#endif


template<>
struct VerifyExecutionCanAccessMemorySpace
  < Kokkos::CudaSpace
  , Kokkos::Cuda::scratch_memory_space
  >
{
  enum { value = true };
  KOKKOS_INLINE_FUNCTION static void verify( void ) { }
  KOKKOS_INLINE_FUNCTION static void verify( const void * ) { }
};

template<>
struct VerifyExecutionCanAccessMemorySpace
  < Kokkos::HostSpace
  , Kokkos::Cuda::scratch_memory_space
  >
{
  enum { value = false };
  inline static void verify( void ) { CudaSpace::access_error(); }
  inline static void verify( const void * p ) { CudaSpace::access_error(p); }
};

} // namespace Impl
} // namespace Kokkos

/*--------------------------------------------------------------------------*/
/*--------------------------------------------------------------------------*/

#include <Cuda/Kokkos_CudaExec.hpp>
#include <Cuda/Kokkos_Cuda_View.hpp>
#include <Cuda/Kokkos_Cuda_Team.hpp>
#include <Cuda/Kokkos_Cuda_Parallel.hpp>
#include <Cuda/Kokkos_Cuda_Task.hpp>
#include <Cuda/Kokkos_Cuda_UniqueToken.hpp>

#include <KokkosExp_MDRangePolicy.hpp>
//----------------------------------------------------------------------------

#endif /* #if defined( KOKKOS_ENABLE_CUDA ) */
#endif /* #ifndef KOKKOS_CUDA_HPP */

