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#pragma once

#if THRUST_DEVICE_COMPILER == THRUST_DEVICE_COMPILER_HCC
#include <thrust/detail/config.h>

#include <thrust/detail/alignment.h>
#include <thrust/detail/cstdint.h>
#include <thrust/detail/minmax.h>
#include <thrust/detail/raw_reference_cast.h>
#include <thrust/detail/temporary_array.h>
#include <thrust/detail/type_traits/iterator/is_output_iterator.h>
#include <thrust/device_vector.h>
#include <thrust/distance.h>
#include <thrust/functional.h>
#include <thrust/system/hip/detail/get_value.h>
#include <thrust/system/hip/detail/par_to_seq.h>
#include <thrust/system/hip/detail/util.h>

// rocprim include
#include <rocprim/rocprim.hpp>

BEGIN_NS_THRUST

// forward declare generic reduce
// to circumvent circular dependency
template <typename DerivedPolicy, typename InputIterator, typename T, typename BinaryFunction>
T __host__ __device__
reduce(const thrust::detail::execution_policy_base<DerivedPolicy>& exec,
       InputIterator                                               first,
       InputIterator                                               last,
       T                                                           init,
       BinaryFunction                                              binary_op);

namespace hip_rocprim
{
namespace __reduce
{
    template <class Policy, class InputIt, class Size, class T, class BinaryOp>
    T THRUST_HIP_RUNTIME_FUNCTION
    reduce(Policy& policy, InputIt first, Size num_items, T init, BinaryOp binary_op)
    {
        if(num_items == 0)
            return init;

        void*       d_temp_storage     = NULL;
        size_t      temp_storage_bytes = 0;
        hipStream_t stream             = hip_rocprim::stream(policy);
        T*          d_ret_ptr          = NULL;
        bool        debug_sync         = THRUST_HIP_DEBUG_SYNC_FLAG;

        // Determine temporary device storage requirements.
        hip_rocprim::throw_on_error(rocprim::reduce(d_temp_storage,
                                                    temp_storage_bytes,
                                                    first,
                                                    d_ret_ptr,
                                                    init,
                                                    num_items,
                                                    binary_op,
                                                    stream,
                                                    debug_sync),
                                    "reduce failed on 1st step");

        // Allocate temporary storage.
        d_temp_storage = hip_rocprim::get_memory_buffer(policy, sizeof(T) + temp_storage_bytes);
        hip_rocprim::throw_on_error(hipGetLastError(), "reduce failed to get memory buffer");

        d_ret_ptr = reinterpret_cast<T*>(reinterpret_cast<char*>(d_temp_storage)
                                         + temp_storage_bytes);

        hip_rocprim::throw_on_error(rocprim::reduce(d_temp_storage,
                                                    temp_storage_bytes,
                                                    first,
                                                    d_ret_ptr,
                                                    init,
                                                    num_items,
                                                    binary_op,
                                                    stream,
                                                    debug_sync),
                                    "reduce failed on 2nd step");

        T return_value = hip_rocprim::get_value(policy, d_ret_ptr);

        hip_rocprim::return_memory_buffer(policy, d_temp_storage);
        hip_rocprim::throw_on_error(hipGetLastError(), "reduce failed to return memory buffer");

        return return_value;
    }
}

//-------------------------
// Thrust API entry points
//-------------------------

template <class Derived, class InputIt, class Size, class T, class BinaryOp>
T THRUST_HIP_FUNCTION
reduce_n(execution_policy<Derived>& policy,
         InputIt                    first,
         Size                       num_items,
         T                          init,
         BinaryOp                   binary_op)
{
    THRUST_HIP_PRESERVE_KERNELS_WORKAROUND(
        (__reduce::reduce<Derived, InputIt, Size, T, BinaryOp>)
    );
#if __THRUST_HAS_HIPRT__
    return __reduce::reduce(policy, first, num_items, init, binary_op);
#else // __THRUST_HAS_HIPRT__
    return thrust::reduce(
        cvt_to_seq(derived_cast(policy)), first, first + num_items, init, binary_op
    );
#endif // __THRUST_HAS_HIPRT__
}

template <class Derived, class InputIt, class T, class BinaryOp>
T THRUST_HIP_FUNCTION
reduce(execution_policy<Derived>& policy,
       InputIt                    first,
       InputIt                    last,
       T                          init,
       BinaryOp                   binary_op)
{
    typedef typename iterator_traits<InputIt>::difference_type size_type;
    // FIXME: Check for RA iterator.
    size_type num_items = static_cast<size_type>(thrust::distance(first, last));
    return hip_rocprim::reduce_n(policy, first, num_items, init, binary_op);
}

template <class Derived, class InputIt, class T>
T THRUST_HIP_FUNCTION
reduce(execution_policy<Derived>& policy,
       InputIt                    first,
       InputIt                    last,
       T                          init)
{
    return hip_rocprim::reduce(policy, first, last, init, plus<T>());
}

template <class Derived, class InputIt>
typename iterator_traits<InputIt>::value_type THRUST_HIP_FUNCTION
reduce(execution_policy<Derived>& policy,
       InputIt                    first,
       InputIt                    last)
{
    typedef typename iterator_traits<InputIt>::value_type value_type;
    return hip_rocprim::reduce(policy, first, last, value_type(0));
}

} // namespace  hip_rocprim

END_NS_THRUST

#include <thrust/memory.h>
#include <thrust/reduce.h>

#endif