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scan_block.hpp
/*
* Software License Agreement (BSD License)
*
* Copyright (c) 2011, Willow Garage, Inc.
* All rights reserved.
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* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
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* * Redistributions of source code must retain the above copyright
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* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
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* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* Author: Anatoly Baskeheev, Itseez Ltd, (myname.mysurname@mycompany.com)
*/
#ifndef PCL_GPU_OCTREE_SCAN_BLOCK_HPP
#define PCL_GPU_OCTREE_SCAN_BLOCK_HPP
namespace pcl
{
namespace device
{
enum ScanKind { exclusive, inclusive } ;
template <ScanKind Kind , class T>
__device__ __forceinline__ T scan_warp ( volatile T *ptr , const unsigned int idx = threadIdx.x )
{
const unsigned int lane = idx & 31; // index of thread in warp (0..31)
if ( lane >= 1) ptr [idx ] = ptr [idx - 1] + ptr [idx];
if ( lane >= 2) ptr [idx ] = ptr [idx - 2] + ptr [idx];
if ( lane >= 4) ptr [idx ] = ptr [idx - 4] + ptr [idx];
if ( lane >= 8) ptr [idx ] = ptr [idx - 8] + ptr [idx];
if ( lane >= 16) ptr [idx ] = ptr [idx - 16] + ptr [idx];
if( Kind == inclusive )
return ptr [idx ];
else
return (lane > 0) ? ptr [idx - 1] : 0;
}
template <ScanKind Kind , class T>
__device__ __forceinline__ T scan_block( volatile T *ptr , const unsigned int idx = threadIdx.x )
{
const unsigned int lane = idx & 31;
const unsigned int warpid = idx >> 5;
// Step 1: Intra - warp scan in each warp
T val = scan_warp <Kind>( ptr , idx );
__syncthreads ();
// Step 2: Collect per - warp partial results
/* if( warpid == 0 )
if( lane == 31 )
ptr [ warpid ] = ptr [idx ];
__syncthreads ();
if( warpid > 0 ) */
if( lane == 31 )
ptr [ warpid ] = ptr [idx ];
__syncthreads ();
// Step 3: Use 1st warp to scan per - warp results
if( warpid == 0 )
scan_warp<inclusive>( ptr , idx );
__syncthreads ();
// Step 4: Accumulate results from Steps 1 and 3
if ( warpid > 0)
val = ptr [warpid -1] + val;
__syncthreads ();
// Step 5: Write and return the final result
ptr[idx] = val;
__syncthreads ();
return val ;
}
}
}
#endif /* PCL_GPU_OCTREE_SCAN_BLOCK_HPP */
pcl::device
Definition device_array.h:315
pcl::device::scan_warp
__device__ __forceinline__ T scan_warp(volatile T *ptr, const unsigned int idx=threadIdx.x)
Definition device.hpp:87
pcl::device::ScanKind
ScanKind
Definition device.hpp:83
pcl::device::exclusive
@ exclusive
Definition device.hpp:83
pcl::device::inclusive
@ inclusive
Definition device.hpp:83
pcl::device::scan_block
__device__ __forceinline__ T scan_block(volatile T *ptr, const unsigned int idx=threadIdx.x)
Definition scan_block.hpp:65
pcl
Definition convolution.h:46