/*
//@HEADER
// ************************************************************************
//
//                        Kokkos v. 3.0
//       Copyright (2020) National Technology & Engineering
//               Solutions of Sandia, LLC (NTESS).
//
// Under the terms of Contract DE-NA0003525 with NTESS,
// the U.S. Government retains certain rights in this software.
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// modification, are permitted provided that the following conditions are
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// documentation and/or other materials provided with the distribution.
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// 3. Neither the name of the Corporation nor the names of the
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// Questions? Contact Christian R. Trott (crtrott@sandia.gov)
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*/

#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
#include <xmmintrin.h>
#endif

#include <Kokkos_Macros.hpp>
#if defined(KOKKOS_ATOMIC_HPP) && !defined(KOKKOS_ATOMIC_FETCH_SUB_HPP)
#define KOKKOS_ATOMIC_FETCH_SUB_HPP

namespace Kokkos {

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

#if defined(KOKKOS_ENABLE_CUDA)
#if defined(__CUDA_ARCH__) || defined(KOKKOS_IMPL_CUDA_CLANG_WORKAROUND)

// Support for int, unsigned int, unsigned long long int, and float

__inline__ __device__ int atomic_fetch_sub(volatile int* const dest,
                                           const int val) {
  return atomicSub((int*)dest, val);
}

__inline__ __device__ unsigned int atomic_fetch_sub(
    volatile unsigned int* const dest, const unsigned int val) {
  return atomicSub((unsigned int*)dest, val);
}

__inline__ __device__ unsigned int atomic_fetch_sub(
    volatile int64_t* const dest, const int64_t val) {
  return atomic_fetch_add(dest, -val);
}

__inline__ __device__ unsigned int atomic_fetch_sub(volatile float* const dest,
                                                    const float val) {
  return atomicAdd((float*)dest, -val);
}

#if (600 <= __CUDA_ARCH__)
__inline__ __device__ unsigned int atomic_fetch_sub(volatile double* const dest,
                                                    const double val) {
  return atomicAdd((double*)dest, -val);
}
#endif

template <typename T>
__inline__ __device__ T atomic_fetch_sub(
    volatile T* const dest,
    typename std::enable_if<sizeof(T) == sizeof(int), const T>::type val) {
  union U {
    int i;
    T t;
    KOKKOS_INLINE_FUNCTION U() {}
  } oldval, assume, newval;

  oldval.t = *dest;

  do {
    assume.i = oldval.i;
    newval.t = assume.t - val;
    oldval.i = atomicCAS((int*)dest, assume.i, newval.i);
  } while (assume.i != oldval.i);

  return oldval.t;
}

template <typename T>
__inline__ __device__ T atomic_fetch_sub(
    volatile T* const dest,
    typename std::enable_if<sizeof(T) != sizeof(int) &&
                                sizeof(T) == sizeof(unsigned long long int),
                            const T>::type val) {
  union U {
    unsigned long long int i;
    T t;
    KOKKOS_INLINE_FUNCTION U() {}
  } oldval, assume, newval;

  oldval.t = *dest;

  do {
    assume.i = oldval.i;
    newval.t = assume.t - val;
    oldval.i = atomicCAS((unsigned long long int*)dest, assume.i, newval.i);
  } while (assume.i != oldval.i);

  return oldval.t;
}

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

template <typename T>
__inline__ __device__ T
atomic_fetch_sub(volatile T* const dest,
                 typename std::enable_if<(sizeof(T) != 4) && (sizeof(T) != 8),
                                         const T>::type& val) {
  T return_val;
  // This is a way to (hopefully) avoid dead lock in a warp
  int done                 = 0;
  unsigned int mask        = __activemask();
  unsigned int active      = __ballot_sync(mask, 1);
  unsigned int done_active = 0;
  while (active != done_active) {
    if (!done) {
      if (Impl::lock_address_cuda_space((void*)dest)) {
        Kokkos::memory_fence();
        return_val = *dest;
        *dest      = return_val - val;
        Kokkos::memory_fence();
        Impl::unlock_address_cuda_space((void*)dest);
        done = 1;
      }
    }
    done_active = __ballot_sync(mask, done);
  }
  return return_val;
}
#endif
#endif
//----------------------------------------------------------------------------
#if !defined(__CUDA_ARCH__) || defined(KOKKOS_IMPL_CUDA_CLANG_WORKAROUND)
#if defined(KOKKOS_ENABLE_GNU_ATOMICS) || defined(KOKKOS_ENABLE_INTEL_ATOMICS)

inline int atomic_fetch_sub(volatile int* const dest, const int val) {
#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
  _mm_prefetch((const char*)dest, _MM_HINT_ET0);
#endif
  return __sync_fetch_and_sub(dest, val);
}

inline long int atomic_fetch_sub(volatile long int* const dest,
                                 const long int val) {
#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
  _mm_prefetch((const char*)dest, _MM_HINT_ET0);
#endif
  return __sync_fetch_and_sub(dest, val);
}

#if defined(KOKKOS_ENABLE_GNU_ATOMICS)

inline unsigned int atomic_fetch_sub(volatile unsigned int* const dest,
                                     const unsigned int val) {
#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
  _mm_prefetch((const char*)dest, _MM_HINT_ET0);
#endif
  return __sync_fetch_and_sub(dest, val);
}

inline unsigned long int atomic_fetch_sub(
    volatile unsigned long int* const dest, const unsigned long int val) {
#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
  _mm_prefetch((const char*)dest, _MM_HINT_ET0);
#endif
  return __sync_fetch_and_sub(dest, val);
}

inline unsigned long long int atomic_fetch_sub(
    volatile unsigned long long int* const dest,
    const unsigned long long int val) {
#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
  _mm_prefetch((const char*)dest, _MM_HINT_ET0);
#endif
  return __sync_fetch_and_sub(dest, val);
}

#endif

template <typename T>
inline T atomic_fetch_sub(
    volatile T* const dest,
    typename std::enable_if<sizeof(T) == sizeof(int), const T>::type val) {
  union U {
    int i;
    T t;
    KOKKOS_INLINE_FUNCTION U() {}
  } oldval, assume, newval;

#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
  _mm_prefetch((const char*)dest, _MM_HINT_ET0);
#endif

  oldval.t = *dest;

  do {
    assume.i = oldval.i;
    newval.t = assume.t - val;
    oldval.i = __sync_val_compare_and_swap((int*)dest, assume.i, newval.i);
  } while (assume.i != oldval.i);

  return oldval.t;
}

template <typename T>
inline T atomic_fetch_sub(volatile T* const dest,
                          typename std::enable_if<sizeof(T) != sizeof(int) &&
                                                      sizeof(T) == sizeof(long),
                                                  const T>::type val) {
#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
  _mm_prefetch((const char*)dest, _MM_HINT_ET0);
#endif

  union U {
    long i;
    T t;
    KOKKOS_INLINE_FUNCTION U() {}
  } oldval, assume, newval;

  oldval.t = *dest;

  do {
    assume.i = oldval.i;
    newval.t = assume.t - val;
    oldval.i = __sync_val_compare_and_swap((long*)dest, assume.i, newval.i);
  } while (assume.i != oldval.i);

  return oldval.t;
}

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

template <typename T>
inline T atomic_fetch_sub(
    volatile T* const dest,
    typename std::enable_if<(sizeof(T) != 4) && (sizeof(T) != 8),
                            const T>::type& val) {
#if defined(KOKKOS_ENABLE_RFO_PREFETCH)
  _mm_prefetch((const char*)dest, _MM_HINT_ET0);
#endif

  while (!Impl::lock_address_host_space((void*)dest))
    ;
  Kokkos::memory_fence();
  T return_val = *dest;
  *dest        = return_val - val;
  Kokkos::memory_fence();
  Impl::unlock_address_host_space((void*)dest);
  return return_val;
}

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

#elif defined(KOKKOS_ENABLE_OPENMP_ATOMICS)

template <typename T>
T atomic_fetch_sub(volatile T* const dest, const T val) {
  T retval;
#pragma omp atomic capture
  {
    retval = dest[0];
    dest[0] -= val;
  }
  return retval;
}

#elif defined(KOKKOS_ENABLE_SERIAL_ATOMICS)

template <typename T>
T atomic_fetch_sub(volatile T* const dest_v, const T val) {
  T* dest  = const_cast<T*>(dest_v);
  T retval = *dest;
  *dest -= val;
  return retval;
}

#endif
#endif

// dummy for non-CUDA Kokkos headers being processed by NVCC
#if defined(__CUDA_ARCH__) && !defined(KOKKOS_ENABLE_CUDA)
template <typename T>
__inline__ __device__ T atomic_fetch_sub(volatile T* const,
                                         Kokkos::Impl::identity_t<T>) {
  return T();
}
#endif

}  // namespace Kokkos

#include <impl/Kokkos_Atomic_Assembly.hpp>
#endif
