cache_modified_output_iterator.cuh

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/******************************************************************************
 * Copyright (c) 2011, Duane Merrill.  All rights reserved.
 * Copyright (c) 2011-2018, NVIDIA CORPORATION.  All rights reserved.
 * 
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 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
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 *     * Neither the name of the NVIDIA CORPORATION nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
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#pragma once

#include <iterator>
#include <iostream>

#include "../thread/thread_load.cuh"
#include "../thread/thread_store.cuh"
#include "../util_device.cuh"
#include "../util_namespace.cuh"

#if (THRUST_VERSION >= 100700)
    // This iterator is compatible with Thrust API 1.7 and newer
    #include <thrust/iterator/iterator_facade.h>
    #include <thrust/iterator/iterator_traits.h>
#endif // THRUST_VERSION


CUB_NS_PREFIX

namespace cub {


template <
    CacheStoreModifier  MODIFIER,
    typename            ValueType,
    typename            OffsetT = ptrdiff_t>
class CacheModifiedOutputIterator
{
private:

    // Proxy object
    struct Reference
    {
        ValueType* ptr;

        __host__ __device__ __forceinline__ Reference(ValueType* ptr) : ptr(ptr) {}

        __device__ __forceinline__ ValueType operator =(ValueType val)
        {
            ThreadStore<MODIFIER>(ptr, val);
            return val;
        }
    };

public:

    // Required iterator traits
    typedef CacheModifiedOutputIterator         self_type;              
    typedef OffsetT                             difference_type;        
    typedef void                                value_type;             
    typedef void                                pointer;                
    typedef Reference                           reference;              

#if (THRUST_VERSION >= 100700)
    // Use Thrust's iterator categories so we can use these iterators in Thrust 1.7 (or newer) methods
    typedef typename thrust::detail::iterator_facade_category<
        thrust::device_system_tag,
        thrust::random_access_traversal_tag,
        value_type,
        reference
      >::type iterator_category;                                        
#else
    typedef std::random_access_iterator_tag     iterator_category;      
#endif  // THRUST_VERSION

private:

    ValueType* ptr;

public:

    template <typename QualifiedValueType>
    __host__ __device__ __forceinline__ CacheModifiedOutputIterator(
        QualifiedValueType* ptr)     
    :
        ptr(const_cast<typename RemoveQualifiers<QualifiedValueType>::Type *>(ptr))
    {}

    __host__ __device__ __forceinline__ self_type operator++(int)
    {
        self_type retval = *this;
        ptr++;
        return retval;
    }


    __host__ __device__ __forceinline__ self_type operator++()
    {
        ptr++;
        return *this;
    }

    __host__ __device__ __forceinline__ reference operator*() const
    {
        return Reference(ptr);
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ self_type operator+(Distance n) const
    {
        self_type retval(ptr + n);
        return retval;
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ self_type& operator+=(Distance n)
    {
        ptr += n;
        return *this;
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ self_type operator-(Distance n) const
    {
        self_type retval(ptr - n);
        return retval;
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ self_type& operator-=(Distance n)
    {
        ptr -= n;
        return *this;
    }

    __host__ __device__ __forceinline__ difference_type operator-(self_type other) const
    {
        return ptr - other.ptr;
    }

    template <typename Distance>
    __host__ __device__ __forceinline__ reference operator[](Distance n) const
    {
        return Reference(ptr + n);
    }

    __host__ __device__ __forceinline__ bool operator==(const self_type& rhs)
    {
        return (ptr == rhs.ptr);
    }

    __host__ __device__ __forceinline__ bool operator!=(const self_type& rhs)
    {
        return (ptr != rhs.ptr);
    }

    friend std::ostream& operator<<(std::ostream& os, const self_type& itr)
    {
        return os;
    }
};

       // end group UtilIterator

}               // CUB namespace
CUB_NS_POSTFIX  // Optional outer namespace(s)