equal.hpp

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/*
Copyright (c) 2015, Scott Zuyderduyn
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//----------------------------------------------------------------------------
// algo/equal.hpp
//
// Extension of std::equal that recognizes device memory and can be called from
// host or device code.
//
// Author: Scott D. Zuyderduyn, Ph.D. (scott.zuyderduyn@utoronto.ca)
//----------------------------------------------------------------------------
#pragma once
#ifndef ECUDA_ALGO_EQUAL_HPP
#define ECUDA_ALGO_EQUAL_HPP

#include <iterator>
#include <vector>

#include "../global.hpp"
#include "../iterator.hpp"
#include "../utility.hpp"

namespace ecuda {

// forward declaration
template<class InputIterator1,class InputIterator2> __HOST__ __DEVICE__ inline bool equal( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2 );

namespace impl {

template<class InputIterator1,class InputIterator2>
__HOST__ __DEVICE__ inline bool equal( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, ecuda::pair<ecuda::false_type,ecuda::false_type> )
{
    #ifdef __CUDA_ARCH__
    return false; // never actually gets called, just here to trick nvcc
    #else
    return std::equal( first1, last1, first2 );
    #endif
}

template<class InputIterator1,class InputIterator2>
__HOST__ __DEVICE__ inline bool equal( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, ecuda::pair<ecuda::true_type,ecuda::false_type> )
{
    #ifdef __CUDA_ARCH__
    return false; // never actually gets called, just here to trick nvcc
    #else
    typedef typename ecuda::remove_const<typename ecuda::iterator_traits<InputIterator1>::value_type>::type valtype1;
    std::vector< valtype1, host_allocator<valtype1> > v1( static_cast<std::size_t>(ecuda::distance(first1,last1)) );
    ecuda::copy( first1, last1, v1.begin() );
    return std::equal( v1.begin(), v1.end(), first2 );
    #endif
}

ECUDA_SUPPRESS_HD_WARNINGS
template<class InputIterator,typename T,typename P>
__HOST__ __DEVICE__ inline bool equal(
    device_contiguous_block_iterator<T,P> first1,
    device_contiguous_block_iterator<T,P> last1,
    InputIterator first2,
    ecuda::pair<ecuda::true_type,ecuda::false_type>
)
{
    while( first1 != last1 ) {
        typename device_contiguous_block_iterator<T,P>::contiguous_iterator blockBegin = first1.contiguous_begin();
        typename device_contiguous_block_iterator<T,P>::contiguous_iterator blockEnd = first1.contiguous_end();
        if( !::ecuda::equal( blockBegin, blockEnd, first2 ) ) return false;
        ecuda::advance( first1, distance( blockBegin, blockEnd ) );
        ecuda::advance( first2, distance( blockBegin, blockEnd ) );
        //first1 += distance( blockBegin, blockEnd );
    }
    return true;
}

ECUDA_SUPPRESS_HD_WARNINGS
template<class InputIterator1,class InputIterator2>
__HOST__ __DEVICE__ inline bool equal( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, ecuda::pair<ecuda::false_type,ecuda::true_type> )
{
    InputIterator2 last2 = first2;
    ecuda::advance( last2, ecuda::distance(first1,last1) );
    return ecuda::equal( first2, last2, first1 );
}

template<class InputIterator1,typename T,typename P>
__HOST__ __DEVICE__ inline bool equal(
    InputIterator1 first1, InputIterator1 last1,
    device_contiguous_block_iterator<T,P> first2,
    ecuda::pair<ecuda::true_type,ecuda::true_type>
)
{
    while( first1 != last1 ) {
        typename device_contiguous_block_iterator<T,P>::contiguous_iterator blockBegin = first2.contiguous_begin();
        typename device_contiguous_block_iterator<T,P>::contiguous_iterator blockEnd = first2.contiguous_end();
        if( !equal( blockBegin, blockEnd, first1 ) ) return false;
        advance( first1, distance( blockBegin, blockEnd ) );
        //first1 += distance( blockBegin, blockEnd );
    }
    return true;
}

ECUDA_SUPPRESS_HD_WARNINGS
template<class InputIterator1,class InputIterator2>
__HOST__ __DEVICE__ inline bool equal(
    InputIterator1 first1, InputIterator1 last1,
    InputIterator2 first2,
    ecuda::pair<ecuda::true_type,ecuda::true_type>
)
{
    #ifdef __CUDA_ARCH__
    for( ; first1 != last1; ++first1, ++first2 ) if( !(*first1 == *first2) ) return false;
    return true;
    #else
    // strip const qualifiers otherwise cannot create std::vector<const T>
    typedef typename ecuda::remove_const<typename ecuda::iterator_traits<InputIterator1>::value_type>::type valtype1;
    typedef typename ecuda::remove_const<typename ecuda::iterator_traits<InputIterator2>::value_type>::type valtype2;
    InputIterator2 last2 = first2;
    ecuda::advance( last2, ecuda::distance(first1,last1) );
    // allocate temporary memory using host_allocator (i.e. cudaHostAlloc) for potential performance improvement
    std::vector< valtype1, host_allocator<valtype1> > v1( ecuda::distance( first1, last1 ) );
    std::vector< valtype2, host_allocator<valtype2> > v2( ecuda::distance( first2, last2 ) );
    ecuda::copy( first1, last1, v1.begin() );
    ecuda::copy( first2, last2, v2.begin() );
    return std::equal( v1.begin(), v1.end(), v2.begin() );
    #endif
}

} // namespace impl

ECUDA_SUPPRESS_HD_WARNINGS
template<class InputIterator1,class InputIterator2>
__HOST__ __DEVICE__ inline bool equal( InputIterator1 first1, InputIterator1 last1, InputIterator2 first2 )
{
    return impl::equal( first1, last1, first2, ecuda::pair<typename ecuda::iterator_traits<InputIterator1>::is_device_iterator,typename ecuda::iterator_traits<InputIterator2>::is_device_iterator>() );
}

} // namespace ecuda

#endif