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140 lines
4.8 KiB
140 lines
4.8 KiB
#ifndef FLANN_UTIL_CUDA_HEAP_H
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#define FLANN_UTIL_CUDA_HEAP_H
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/*
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Copyright (c) 2011, Andreas Mützel <andreas.muetzel@gmx.net>
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of the <organization> nor the
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names of its contributors may be used to endorse or promote products
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derived from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY Andreas Mützel <andreas.muetzel@gmx.net> ''AS IS'' AND ANY
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EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL Andreas Mützel <andreas.muetzel@gmx.net> BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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namespace flann
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{
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namespace cuda
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{
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template <class T>
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__device__ __host__ void swap( T& x, T& y )
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{
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T t=x;
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x=y;
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y=t;
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}
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namespace heap
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{
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//! moves an element down the heap until all children are smaller than the element
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//! if c is a less-than comparator, it do this until all children are larger
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template <class GreaterThan, class RandomAccessIterator>
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__host__ __device__ void
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sift_down( RandomAccessIterator array, size_t begin, size_t length, GreaterThan c = GreaterThan() )
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{
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while( 2*begin+1 < length ) {
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size_t left = 2*begin+1;
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size_t right = 2*begin+2;
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size_t largest=begin;
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if((left < length)&& c(array[left], array[largest]) ) largest=left;
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if((right < length)&& c(array[right], array[largest]) ) largest=right;
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if( largest != begin ) {
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cuda::swap( array[begin], array[largest] );
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begin=largest;
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}
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else return;
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}
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}
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//! creates a max-heap in the array beginning at begin of length "length"
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//! if c is a less-than comparator, it will create a min-heap
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template <class GreaterThan, class RandomAccessIterator>
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__host__ __device__ void
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make_heap( RandomAccessIterator begin, size_t length, GreaterThan c = GreaterThan() )
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{
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int i=length/2-1;
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while( i>=0 ) {
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sift_down( begin, i, length, c );
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i--;
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}
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}
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//! verifies if the array is a max-heap
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//! if c is a less-than comparator, it will verify if it is a min-heap
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template <class GreaterThan, class RandomAccessIterator>
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__host__ __device__ bool
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is_heap( RandomAccessIterator begin, size_t length, GreaterThan c = GreaterThan() )
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{
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for( unsigned i=0; i<length; i++ ) {
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if((2*i+1 < length)&& c(begin[2*i+1],begin[i]) ) return false;
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if((2*i+2 < length)&& c(begin[2*i+2],begin[i]) ) return false;
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}
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return true;
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}
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//! moves an element down the heap until all children are smaller than the element
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//! if c is a less-than comparator, it do this until all children are larger
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template <class GreaterThan, class RandomAccessIterator, class RandomAccessIterator2>
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__host__ __device__ void
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sift_down( RandomAccessIterator key, RandomAccessIterator2 value, size_t begin, size_t length, GreaterThan c = GreaterThan() )
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{
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while( 2*begin+1 < length ) {
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size_t left = 2*begin+1;
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size_t right = 2*begin+2;
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size_t largest=begin;
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if((left < length)&& c(key[left], key[largest]) ) largest=left;
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if((right < length)&& c(key[right], key[largest]) ) largest=right;
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if( largest != begin ) {
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cuda::swap( key[begin], key[largest] );
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cuda::swap( value[begin], value[largest] );
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begin=largest;
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}
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else return;
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}
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}
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//! creates a max-heap in the array beginning at begin of length "length"
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//! if c is a less-than comparator, it will create a min-heap
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template <class GreaterThan, class RandomAccessIterator, class RandomAccessIterator2>
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__host__ __device__ void
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make_heap( RandomAccessIterator key, RandomAccessIterator2 value, size_t length, GreaterThan c = GreaterThan() )
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{
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int i=length/2-1;
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while( i>=0 ) {
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sift_down( key, value, i, length, c );
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i--;
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}
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}
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}
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}
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}
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#endif
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