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tools/cub-1.8.0/cub/block/block_exchange.cuh
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/******************************************************************************
* Copyright (c) 2011, Duane Merrill. All rights reserved.
* Copyright (c) 2011-2018, NVIDIA CORPORATION. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* 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.
* * 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.
* * 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************/
/**
* \file
* The cub::BlockExchange class provides [<em>collective</em>](index.html#sec0) methods for rearranging data partitioned across a CUDA thread block.
*/
#pragma once
#include "../util_ptx.cuh"
#include "../util_arch.cuh"
#include "../util_macro.cuh"
#include "../util_type.cuh"
#include "../util_namespace.cuh"
/// Optional outer namespace(s)
CUB_NS_PREFIX
/// CUB namespace
namespace cub {
/**
* \brief The BlockExchange class provides [<em>collective</em>](index.html#sec0) methods for rearranging data partitioned across a CUDA thread block. 
* \ingroup BlockModule
*
* \tparam T The data type to be exchanged.
* \tparam BLOCK_DIM_X The thread block length in threads along the X dimension
* \tparam ITEMS_PER_THREAD The number of items partitioned onto each thread.
* \tparam WARP_TIME_SLICING <b>[optional]</b> When \p true, only use enough shared memory for a single warp's worth of tile data, time-slicing the block-wide exchange over multiple synchronized rounds. Yields a smaller memory footprint at the expense of decreased parallelism. (Default: false)
* \tparam BLOCK_DIM_Y <b>[optional]</b> The thread block length in threads along the Y dimension (default: 1)
* \tparam BLOCK_DIM_Z <b>[optional]</b> The thread block length in threads along the Z dimension (default: 1)
* \tparam PTX_ARCH <b>[optional]</b> \ptxversion
*
* \par Overview
* - It is commonplace for blocks of threads to rearrange data items between
* threads. For example, the device-accessible memory subsystem prefers access patterns
* where data items are "striped" across threads (where consecutive threads access consecutive items),
* yet most block-wide operations prefer a "blocked" partitioning of items across threads
* (where consecutive items belong to a single thread).
* - BlockExchange supports the following types of data exchanges:
* - Transposing between [<em>blocked</em>](index.html#sec5sec3) and [<em>striped</em>](index.html#sec5sec3) arrangements
* - Transposing between [<em>blocked</em>](index.html#sec5sec3) and [<em>warp-striped</em>](index.html#sec5sec3) arrangements
* - Scattering ranked items to a [<em>blocked arrangement</em>](index.html#sec5sec3)
* - Scattering ranked items to a [<em>striped arrangement</em>](index.html#sec5sec3)
* - \rowmajor
*
* \par A Simple Example
* \blockcollective{BlockExchange}
* \par
* The code snippet below illustrates the conversion from a "blocked" to a "striped" arrangement
* of 512 integer items partitioned across 128 threads where each thread owns 4 items.
* \par
* \code
* #include <cub/cub.cuh> // or equivalently <cub/block/block_exchange.cuh>
*
* __global__ void ExampleKernel(int *d_data, ...)
* {
* // Specialize BlockExchange for a 1D block of 128 threads owning 4 integer items each
* typedef cub::BlockExchange<int, 128, 4> BlockExchange;
*
* // Allocate shared memory for BlockExchange
* __shared__ typename BlockExchange::TempStorage temp_storage;
*
* // Load a tile of data striped across threads
* int thread_data[4];
* cub::LoadDirectStriped<128>(threadIdx.x, d_data, thread_data);
*
* // Collectively exchange data into a blocked arrangement across threads
* BlockExchange(temp_storage).StripedToBlocked(thread_data);
*
* \endcode
* \par
* Suppose the set of striped input \p thread_data across the block of threads is
* <tt>{ [0,128,256,384], [1,129,257,385], ..., [127,255,383,511] }</tt>.
* The corresponding output \p thread_data in those threads will be
* <tt>{ [0,1,2,3], [4,5,6,7], [8,9,10,11], ..., [508,509,510,511] }</tt>.
*
* \par Performance Considerations
* - Proper device-specific padding ensures zero bank conflicts for most types.
*
*/
template <
typename InputT,
int BLOCK_DIM_X,
int ITEMS_PER_THREAD,
bool WARP_TIME_SLICING = false,
int BLOCK_DIM_Y = 1,
int BLOCK_DIM_Z = 1,
int PTX_ARCH = CUB_PTX_ARCH>
class BlockExchange
{
private:
/******************************************************************************
* Constants
******************************************************************************/
/// Constants
enum
{
/// The thread block size in threads
BLOCK_THREADS = BLOCK_DIM_X * BLOCK_DIM_Y * BLOCK_DIM_Z,
LOG_WARP_THREADS = CUB_LOG_WARP_THREADS(PTX_ARCH),
WARP_THREADS = 1 << LOG_WARP_THREADS,
WARPS = (BLOCK_THREADS + WARP_THREADS - 1) / WARP_THREADS,
LOG_SMEM_BANKS = CUB_LOG_SMEM_BANKS(PTX_ARCH),
SMEM_BANKS = 1 << LOG_SMEM_BANKS,
TILE_ITEMS = BLOCK_THREADS * ITEMS_PER_THREAD,
TIME_SLICES = (WARP_TIME_SLICING) ? WARPS : 1,
TIME_SLICED_THREADS = (WARP_TIME_SLICING) ? CUB_MIN(BLOCK_THREADS, WARP_THREADS) : BLOCK_THREADS,
TIME_SLICED_ITEMS = TIME_SLICED_THREADS * ITEMS_PER_THREAD,
WARP_TIME_SLICED_THREADS = CUB_MIN(BLOCK_THREADS, WARP_THREADS),
WARP_TIME_SLICED_ITEMS = WARP_TIME_SLICED_THREADS * ITEMS_PER_THREAD,
// Insert padding to avoid bank conflicts during raking when items per thread is a power of two and > 4 (otherwise we can typically use 128b loads)
INSERT_PADDING = (ITEMS_PER_THREAD > 4) && (PowerOfTwo<ITEMS_PER_THREAD>::VALUE),
PADDING_ITEMS = (INSERT_PADDING) ? (TIME_SLICED_ITEMS >> LOG_SMEM_BANKS) : 0,
};
/******************************************************************************
* Type definitions
******************************************************************************/
/// Shared memory storage layout type
struct __align__(16) _TempStorage
{
InputT buff[TIME_SLICED_ITEMS + PADDING_ITEMS];
};
public:
/// \smemstorage{BlockExchange}
struct TempStorage : Uninitialized<_TempStorage> {};
private:
/******************************************************************************
* Thread fields
******************************************************************************/
/// Shared storage reference
_TempStorage &temp_storage;
/// Linear thread-id
unsigned int linear_tid;
unsigned int lane_id;
unsigned int warp_id;
unsigned int warp_offset;
/******************************************************************************
* Utility methods
******************************************************************************/
/// Internal storage allocator
__device__ __forceinline__ _TempStorage& PrivateStorage()
{
__shared__ _TempStorage private_storage;
return private_storage;
}
/**
* Transposes data items from <em>blocked</em> arrangement to <em>striped</em> arrangement. Specialized for no timeslicing.
*/
template <typename OutputT>
__device__ __forceinline__ void BlockedToStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
Int2Type<false> /*time_slicing*/)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (linear_tid * ITEMS_PER_THREAD) + ITEM;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = int(ITEM * BLOCK_THREADS) + linear_tid;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
/**
* Transposes data items from <em>blocked</em> arrangement to <em>striped</em> arrangement. Specialized for warp-timeslicing.
*/
template <typename OutputT>
__device__ __forceinline__ void BlockedToStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
Int2Type<true> /*time_slicing*/)
{
InputT temp_items[ITEMS_PER_THREAD];
#pragma unroll
for (int SLICE = 0; SLICE < TIME_SLICES; SLICE++)
{
const int SLICE_OFFSET = SLICE * TIME_SLICED_ITEMS;
const int SLICE_OOB = SLICE_OFFSET + TIME_SLICED_ITEMS;
CTA_SYNC();
if (warp_id == SLICE)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (lane_id * ITEMS_PER_THREAD) + ITEM;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
}
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
// Read a strip of items
const int STRIP_OFFSET = ITEM * BLOCK_THREADS;
const int STRIP_OOB = STRIP_OFFSET + BLOCK_THREADS;
if ((SLICE_OFFSET < STRIP_OOB) && (SLICE_OOB > STRIP_OFFSET))
{
int item_offset = STRIP_OFFSET + linear_tid - SLICE_OFFSET;
if ((item_offset >= 0) && (item_offset < TIME_SLICED_ITEMS))
{
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_items[ITEM] = temp_storage.buff[item_offset];
}
}
}
}
// Copy
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
output_items[ITEM] = temp_items[ITEM];
}
}
/**
* Transposes data items from <em>blocked</em> arrangement to <em>warp-striped</em> arrangement. Specialized for no timeslicing
*/
template <typename OutputT>
__device__ __forceinline__ void BlockedToWarpStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
Int2Type<false> /*time_slicing*/)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = warp_offset + ITEM + (lane_id * ITEMS_PER_THREAD);
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
WARP_SYNC(0xffffffff);
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = warp_offset + (ITEM * WARP_TIME_SLICED_THREADS) + lane_id;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
/**
* Transposes data items from <em>blocked</em> arrangement to <em>warp-striped</em> arrangement. Specialized for warp-timeslicing
*/
template <typename OutputT>
__device__ __forceinline__ void BlockedToWarpStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
Int2Type<true> /*time_slicing*/)
{
if (warp_id == 0)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ITEM + (lane_id * ITEMS_PER_THREAD);
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
WARP_SYNC(0xffffffff);
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (ITEM * WARP_TIME_SLICED_THREADS) + lane_id;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
#pragma unroll
for (unsigned int SLICE = 1; SLICE < TIME_SLICES; ++SLICE)
{
CTA_SYNC();
if (warp_id == SLICE)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ITEM + (lane_id * ITEMS_PER_THREAD);
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
WARP_SYNC(0xffffffff);
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (ITEM * WARP_TIME_SLICED_THREADS) + lane_id;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
}
}
/**
* Transposes data items from <em>striped</em> arrangement to <em>blocked</em> arrangement. Specialized for no timeslicing.
*/
template <typename OutputT>
__device__ __forceinline__ void StripedToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
Int2Type<false> /*time_slicing*/)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = int(ITEM * BLOCK_THREADS) + linear_tid;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
CTA_SYNC();
// No timeslicing
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (linear_tid * ITEMS_PER_THREAD) + ITEM;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
/**
* Transposes data items from <em>striped</em> arrangement to <em>blocked</em> arrangement. Specialized for warp-timeslicing.
*/
template <typename OutputT>
__device__ __forceinline__ void StripedToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
Int2Type<true> /*time_slicing*/)
{
// Warp time-slicing
InputT temp_items[ITEMS_PER_THREAD];
#pragma unroll
for (int SLICE = 0; SLICE < TIME_SLICES; SLICE++)
{
const int SLICE_OFFSET = SLICE * TIME_SLICED_ITEMS;
const int SLICE_OOB = SLICE_OFFSET + TIME_SLICED_ITEMS;
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
// Write a strip of items
const int STRIP_OFFSET = ITEM * BLOCK_THREADS;
const int STRIP_OOB = STRIP_OFFSET + BLOCK_THREADS;
if ((SLICE_OFFSET < STRIP_OOB) && (SLICE_OOB > STRIP_OFFSET))
{
int item_offset = STRIP_OFFSET + linear_tid - SLICE_OFFSET;
if ((item_offset >= 0) && (item_offset < TIME_SLICED_ITEMS))
{
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
}
}
CTA_SYNC();
if (warp_id == SLICE)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (lane_id * ITEMS_PER_THREAD) + ITEM;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_items[ITEM] = temp_storage.buff[item_offset];
}
}
}
// Copy
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
output_items[ITEM] = temp_items[ITEM];
}
}
/**
* Transposes data items from <em>warp-striped</em> arrangement to <em>blocked</em> arrangement. Specialized for no timeslicing
*/
template <typename OutputT>
__device__ __forceinline__ void WarpStripedToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
Int2Type<false> /*time_slicing*/)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = warp_offset + (ITEM * WARP_TIME_SLICED_THREADS) + lane_id;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
WARP_SYNC(0xffffffff);
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = warp_offset + ITEM + (lane_id * ITEMS_PER_THREAD);
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
/**
* Transposes data items from <em>warp-striped</em> arrangement to <em>blocked</em> arrangement. Specialized for warp-timeslicing
*/
template <typename OutputT>
__device__ __forceinline__ void WarpStripedToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
Int2Type<true> /*time_slicing*/)
{
#pragma unroll
for (unsigned int SLICE = 0; SLICE < TIME_SLICES; ++SLICE)
{
CTA_SYNC();
if (warp_id == SLICE)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (ITEM * WARP_TIME_SLICED_THREADS) + lane_id;
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_storage.buff[item_offset] = input_items[ITEM];
}
WARP_SYNC(0xffffffff);
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ITEM + (lane_id * ITEMS_PER_THREAD);
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
}
}
/**
* Exchanges data items annotated by rank into <em>blocked</em> arrangement. Specialized for no timeslicing.
*/
template <typename OutputT, typename OffsetT>
__device__ __forceinline__ void ScatterToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD], ///< [in] Corresponding scatter ranks
Int2Type<false> /*time_slicing*/)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ranks[ITEM];
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
temp_storage.buff[item_offset] = input_items[ITEM];
}
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (linear_tid * ITEMS_PER_THREAD) + ITEM;
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
/**
* Exchanges data items annotated by rank into <em>blocked</em> arrangement. Specialized for warp-timeslicing.
*/
template <typename OutputT, typename OffsetT>
__device__ __forceinline__ void ScatterToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD], ///< [in] Corresponding scatter ranks
Int2Type<true> /*time_slicing*/)
{
InputT temp_items[ITEMS_PER_THREAD];
#pragma unroll
for (int SLICE = 0; SLICE < TIME_SLICES; SLICE++)
{
CTA_SYNC();
const int SLICE_OFFSET = TIME_SLICED_ITEMS * SLICE;
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ranks[ITEM] - SLICE_OFFSET;
if ((item_offset >= 0) && (item_offset < WARP_TIME_SLICED_ITEMS))
{
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
temp_storage.buff[item_offset] = input_items[ITEM];
}
}
CTA_SYNC();
if (warp_id == SLICE)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (lane_id * ITEMS_PER_THREAD) + ITEM;
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
temp_items[ITEM] = temp_storage.buff[item_offset];
}
}
}
// Copy
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
output_items[ITEM] = temp_items[ITEM];
}
}
/**
* Exchanges data items annotated by rank into <em>striped</em> arrangement. Specialized for no timeslicing.
*/
template <typename OutputT, typename OffsetT>
__device__ __forceinline__ void ScatterToStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD], ///< [in] Corresponding scatter ranks
Int2Type<false> /*time_slicing*/)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ranks[ITEM];
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
temp_storage.buff[item_offset] = input_items[ITEM];
}
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = int(ITEM * BLOCK_THREADS) + linear_tid;
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
/**
* Exchanges data items annotated by rank into <em>striped</em> arrangement. Specialized for warp-timeslicing.
*/
template <typename OutputT, typename OffsetT>
__device__ __forceinline__ void ScatterToStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items to exchange, converting between <em>blocked</em> and <em>striped</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD], ///< [in] Corresponding scatter ranks
Int2Type<true> /*time_slicing*/)
{
InputT temp_items[ITEMS_PER_THREAD];
#pragma unroll
for (int SLICE = 0; SLICE < TIME_SLICES; SLICE++)
{
const int SLICE_OFFSET = SLICE * TIME_SLICED_ITEMS;
const int SLICE_OOB = SLICE_OFFSET + TIME_SLICED_ITEMS;
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ranks[ITEM] - SLICE_OFFSET;
if ((item_offset >= 0) && (item_offset < WARP_TIME_SLICED_ITEMS))
{
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
temp_storage.buff[item_offset] = input_items[ITEM];
}
}
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
// Read a strip of items
const int STRIP_OFFSET = ITEM * BLOCK_THREADS;
const int STRIP_OOB = STRIP_OFFSET + BLOCK_THREADS;
if ((SLICE_OFFSET < STRIP_OOB) && (SLICE_OOB > STRIP_OFFSET))
{
int item_offset = STRIP_OFFSET + linear_tid - SLICE_OFFSET;
if ((item_offset >= 0) && (item_offset < TIME_SLICED_ITEMS))
{
if (INSERT_PADDING) item_offset += item_offset >> LOG_SMEM_BANKS;
temp_items[ITEM] = temp_storage.buff[item_offset];
}
}
}
}
// Copy
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
output_items[ITEM] = temp_items[ITEM];
}
}
public:
/******************************************************************//**
*
ame Collective constructors
*********************************************************************/
//@{
/**
* \brief Collective constructor using a private static allocation of shared memory as temporary storage.
*/
__device__ __forceinline__ BlockExchange()
:
temp_storage(PrivateStorage()),
linear_tid(RowMajorTid(BLOCK_DIM_X, BLOCK_DIM_Y, BLOCK_DIM_Z)),
warp_id((WARPS == 1) ? 0 : linear_tid / WARP_THREADS),
lane_id(LaneId()),
warp_offset(warp_id * WARP_TIME_SLICED_ITEMS)
{}
/**
* \brief Collective constructor using the specified memory allocation as temporary storage.
*/
__device__ __forceinline__ BlockExchange(
TempStorage &temp_storage) ///< [in] Reference to memory allocation having layout type TempStorage
:
temp_storage(temp_storage.Alias()),
linear_tid(RowMajorTid(BLOCK_DIM_X, BLOCK_DIM_Y, BLOCK_DIM_Z)),
lane_id(LaneId()),
warp_id((WARPS == 1) ? 0 : linear_tid / WARP_THREADS),
warp_offset(warp_id * WARP_TIME_SLICED_ITEMS)
{}
//@} end member group
/******************************************************************//**
*
ame Structured exchanges
*********************************************************************/
//@{
/**
* \brief Transposes data items from <em>striped</em> arrangement to <em>blocked</em> arrangement.
*
* \par
* - \smemreuse
*
* \par Snippet
* The code snippet below illustrates the conversion from a "striped" to a "blocked" arrangement
* of 512 integer items partitioned across 128 threads where each thread owns 4 items.
* \par
* \code
* #include <cub/cub.cuh> // or equivalently <cub/block/block_exchange.cuh>
*
* __global__ void ExampleKernel(int *d_data, ...)
* {
* // Specialize BlockExchange for a 1D block of 128 threads owning 4 integer items each
* typedef cub::BlockExchange<int, 128, 4> BlockExchange;
*
* // Allocate shared memory for BlockExchange
* __shared__ typename BlockExchange::TempStorage temp_storage;
*
* // Load a tile of ordered data into a striped arrangement across block threads
* int thread_data[4];
* cub::LoadDirectStriped<128>(threadIdx.x, d_data, thread_data);
*
* // Collectively exchange data into a blocked arrangement across threads
* BlockExchange(temp_storage).StripedToBlocked(thread_data, thread_data);
*
* \endcode
* \par
* Suppose the set of striped input \p thread_data across the block of threads is
* <tt>{ [0,128,256,384], [1,129,257,385], ..., [127,255,383,511] }</tt> after loading from device-accessible memory.
* The corresponding output \p thread_data in those threads will be
* <tt>{ [0,1,2,3], [4,5,6,7], [8,9,10,11], ..., [508,509,510,511] }</tt>.
*
*/
template <typename OutputT>
__device__ __forceinline__ void StripedToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD]) ///< [out] Items from exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
{
StripedToBlocked(input_items, output_items, Int2Type<WARP_TIME_SLICING>());
}
/**
* \brief Transposes data items from <em>blocked</em> arrangement to <em>striped</em> arrangement.
*
* \par
* - \smemreuse
*
* \par Snippet
* The code snippet below illustrates the conversion from a "blocked" to a "striped" arrangement
* of 512 integer items partitioned across 128 threads where each thread owns 4 items.
* \par
* \code
* #include <cub/cub.cuh> // or equivalently <cub/block/block_exchange.cuh>
*
* __global__ void ExampleKernel(int *d_data, ...)
* {
* // Specialize BlockExchange for a 1D block of 128 threads owning 4 integer items each
* typedef cub::BlockExchange<int, 128, 4> BlockExchange;
*
* // Allocate shared memory for BlockExchange
* __shared__ typename BlockExchange::TempStorage temp_storage;
*
* // Obtain a segment of consecutive items that are blocked across threads
* int thread_data[4];
* ...
*
* // Collectively exchange data into a striped arrangement across threads
* BlockExchange(temp_storage).BlockedToStriped(thread_data, thread_data);
*
* // Store data striped across block threads into an ordered tile
* cub::StoreDirectStriped<STORE_DEFAULT, 128>(threadIdx.x, d_data, thread_data);
*
* \endcode
* \par
* Suppose the set of blocked input \p thread_data across the block of threads is
* <tt>{ [0,1,2,3], [4,5,6,7], [8,9,10,11], ..., [508,509,510,511] }</tt>.
* The corresponding output \p thread_data in those threads will be
* <tt>{ [0,128,256,384], [1,129,257,385], ..., [127,255,383,511] }</tt> in
* preparation for storing to device-accessible memory.
*
*/
template <typename OutputT>
__device__ __forceinline__ void BlockedToStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD]) ///< [out] Items from exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
{
BlockedToStriped(input_items, output_items, Int2Type<WARP_TIME_SLICING>());
}
/**
* \brief Transposes data items from <em>warp-striped</em> arrangement to <em>blocked</em> arrangement.
*
* \par
* - \smemreuse
*
* \par Snippet
* The code snippet below illustrates the conversion from a "warp-striped" to a "blocked" arrangement
* of 512 integer items partitioned across 128 threads where each thread owns 4 items.
* \par
* \code
* #include <cub/cub.cuh> // or equivalently <cub/block/block_exchange.cuh>
*
* __global__ void ExampleKernel(int *d_data, ...)
* {
* // Specialize BlockExchange for a 1D block of 128 threads owning 4 integer items each
* typedef cub::BlockExchange<int, 128, 4> BlockExchange;
*
* // Allocate shared memory for BlockExchange
* __shared__ typename BlockExchange::TempStorage temp_storage;
*
* // Load a tile of ordered data into a warp-striped arrangement across warp threads
* int thread_data[4];
* cub::LoadSWarptriped<LOAD_DEFAULT>(threadIdx.x, d_data, thread_data);
*
* // Collectively exchange data into a blocked arrangement across threads
* BlockExchange(temp_storage).WarpStripedToBlocked(thread_data);
*
* \endcode
* \par
* Suppose the set of warp-striped input \p thread_data across the block of threads is
* <tt>{ [0,32,64,96], [1,33,65,97], [2,34,66,98], ..., [415,447,479,511] }</tt>
* after loading from device-accessible memory. (The first 128 items are striped across
* the first warp of 32 threads, the second 128 items are striped across the second warp, etc.)
* The corresponding output \p thread_data in those threads will be
* <tt>{ [0,1,2,3], [4,5,6,7], [8,9,10,11], ..., [508,509,510,511] }</tt>.
*
*/
template <typename OutputT>
__device__ __forceinline__ void WarpStripedToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD]) ///< [out] Items from exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
{
WarpStripedToBlocked(input_items, output_items, Int2Type<WARP_TIME_SLICING>());
}
/**
* \brief Transposes data items from <em>blocked</em> arrangement to <em>warp-striped</em> arrangement.
*
* \par
* - \smemreuse
*
* \par Snippet
* The code snippet below illustrates the conversion from a "blocked" to a "warp-striped" arrangement
* of 512 integer items partitioned across 128 threads where each thread owns 4 items.
* \par
* \code
* #include <cub/cub.cuh> // or equivalently <cub/block/block_exchange.cuh>
*
* __global__ void ExampleKernel(int *d_data, ...)
* {
* // Specialize BlockExchange for a 1D block of 128 threads owning 4 integer items each
* typedef cub::BlockExchange<int, 128, 4> BlockExchange;
*
* // Allocate shared memory for BlockExchange
* __shared__ typename BlockExchange::TempStorage temp_storage;
*
* // Obtain a segment of consecutive items that are blocked across threads
* int thread_data[4];
* ...
*
* // Collectively exchange data into a warp-striped arrangement across threads
* BlockExchange(temp_storage).BlockedToWarpStriped(thread_data, thread_data);
*
* // Store data striped across warp threads into an ordered tile
* cub::StoreDirectStriped<STORE_DEFAULT, 128>(threadIdx.x, d_data, thread_data);
*
* \endcode
* \par
* Suppose the set of blocked input \p thread_data across the block of threads is
* <tt>{ [0,1,2,3], [4,5,6,7], [8,9,10,11], ..., [508,509,510,511] }</tt>.
* The corresponding output \p thread_data in those threads will be
* <tt>{ [0,32,64,96], [1,33,65,97], [2,34,66,98], ..., [415,447,479,511] }</tt>
* in preparation for storing to device-accessible memory. (The first 128 items are striped across
* the first warp of 32 threads, the second 128 items are striped across the second warp, etc.)
*
*/
template <typename OutputT>
__device__ __forceinline__ void BlockedToWarpStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD]) ///< [out] Items from exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
{
BlockedToWarpStriped(input_items, output_items, Int2Type<WARP_TIME_SLICING>());
}
//@} end member group
/******************************************************************//**
*
ame Scatter exchanges
*********************************************************************/
//@{
/**
* \brief Exchanges data items annotated by rank into <em>blocked</em> arrangement.
*
* \par
* - \smemreuse
*
* \tparam OffsetT <b>[inferred]</b> Signed integer type for local offsets
*/
template <typename OutputT, typename OffsetT>
__device__ __forceinline__ void ScatterToBlocked(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items from exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD]) ///< [in] Corresponding scatter ranks
{
ScatterToBlocked(input_items, output_items, ranks, Int2Type<WARP_TIME_SLICING>());
}
/**
* \brief Exchanges data items annotated by rank into <em>striped</em> arrangement.
*
* \par
* - \smemreuse
*
* \tparam OffsetT <b>[inferred]</b> Signed integer type for local offsets
*/
template <typename OutputT, typename OffsetT>
__device__ __forceinline__ void ScatterToStriped(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items from exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD]) ///< [in] Corresponding scatter ranks
{
ScatterToStriped(input_items, output_items, ranks, Int2Type<WARP_TIME_SLICING>());
}
/**
* \brief Exchanges data items annotated by rank into <em>striped</em> arrangement. Items with rank -1 are not exchanged.
*
* \par
* - \smemreuse
*
* \tparam OffsetT <b>[inferred]</b> Signed integer type for local offsets
*/
template <typename OutputT, typename OffsetT>
__device__ __forceinline__ void ScatterToStripedGuarded(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items from exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD]) ///< [in] Corresponding scatter ranks
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ranks[ITEM];
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
if (ranks[ITEM] >= 0)
temp_storage.buff[item_offset] = input_items[ITEM];
}
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = int(ITEM * BLOCK_THREADS) + linear_tid;
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
/**
* \brief Exchanges valid data items annotated by rank into <em>striped</em> arrangement.
*
* \par
* - \smemreuse
*
* \tparam OffsetT <b>[inferred]</b> Signed integer type for local offsets
* \tparam ValidFlag <b>[inferred]</b> FlagT type denoting which items are valid
*/
template <typename OutputT, typename OffsetT, typename ValidFlag>
__device__ __forceinline__ void ScatterToStripedFlagged(
InputT input_items[ITEMS_PER_THREAD], ///< [in] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OutputT output_items[ITEMS_PER_THREAD], ///< [out] Items from exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD], ///< [in] Corresponding scatter ranks
ValidFlag is_valid[ITEMS_PER_THREAD]) ///< [in] Corresponding flag denoting item validity
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = ranks[ITEM];
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
if (is_valid[ITEM])
temp_storage.buff[item_offset] = input_items[ITEM];
}
CTA_SYNC();
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = int(ITEM * BLOCK_THREADS) + linear_tid;
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
output_items[ITEM] = temp_storage.buff[item_offset];
}
}
//@} end member group
#ifndef DOXYGEN_SHOULD_SKIP_THIS // Do not document
__device__ __forceinline__ void StripedToBlocked(
InputT items[ITEMS_PER_THREAD]) ///< [in-out] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
{
StripedToBlocked(items, items);
}
__device__ __forceinline__ void BlockedToStriped(
InputT items[ITEMS_PER_THREAD]) ///< [in-out] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
{
BlockedToStriped(items, items);
}
__device__ __forceinline__ void WarpStripedToBlocked(
InputT items[ITEMS_PER_THREAD]) ///< [in-out] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
{
WarpStripedToBlocked(items, items);
}
__device__ __forceinline__ void BlockedToWarpStriped(
InputT items[ITEMS_PER_THREAD]) ///< [in-out] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
{
BlockedToWarpStriped(items, items);
}
template <typename OffsetT>
__device__ __forceinline__ void ScatterToBlocked(
InputT items[ITEMS_PER_THREAD], ///< [in-out] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD]) ///< [in] Corresponding scatter ranks
{
ScatterToBlocked(items, items, ranks);
}
template <typename OffsetT>
__device__ __forceinline__ void ScatterToStriped(
InputT items[ITEMS_PER_THREAD], ///< [in-out] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD]) ///< [in] Corresponding scatter ranks
{
ScatterToStriped(items, items, ranks);
}
template <typename OffsetT>
__device__ __forceinline__ void ScatterToStripedGuarded(
InputT items[ITEMS_PER_THREAD], ///< [in-out] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD]) ///< [in] Corresponding scatter ranks
{
ScatterToStripedGuarded(items, items, ranks);
}
template <typename OffsetT, typename ValidFlag>
__device__ __forceinline__ void ScatterToStripedFlagged(
InputT items[ITEMS_PER_THREAD], ///< [in-out] Items to exchange, converting between <em>striped</em> and <em>blocked</em> arrangements.
OffsetT ranks[ITEMS_PER_THREAD], ///< [in] Corresponding scatter ranks
ValidFlag is_valid[ITEMS_PER_THREAD]) ///< [in] Corresponding flag denoting item validity
{
ScatterToStriped(items, items, ranks, is_valid);
}
#endif // DOXYGEN_SHOULD_SKIP_THIS
};
#ifndef DOXYGEN_SHOULD_SKIP_THIS // Do not document
template <
typename T,
int ITEMS_PER_THREAD,
int LOGICAL_WARP_THREADS = CUB_PTX_WARP_THREADS,
int PTX_ARCH = CUB_PTX_ARCH>
class WarpExchange
{
private:
/******************************************************************************
* Constants
******************************************************************************/
/// Constants
enum
{
// Whether the logical warp size and the PTX warp size coincide
IS_ARCH_WARP = (LOGICAL_WARP_THREADS == CUB_WARP_THREADS(PTX_ARCH)),
WARP_ITEMS = (ITEMS_PER_THREAD * LOGICAL_WARP_THREADS) + 1,
LOG_SMEM_BANKS = CUB_LOG_SMEM_BANKS(PTX_ARCH),
SMEM_BANKS = 1 << LOG_SMEM_BANKS,
// Insert padding if the number of items per thread is a power of two and > 4 (otherwise we can typically use 128b loads)
INSERT_PADDING = (ITEMS_PER_THREAD > 4) && (PowerOfTwo<ITEMS_PER_THREAD>::VALUE),
PADDING_ITEMS = (INSERT_PADDING) ? (WARP_ITEMS >> LOG_SMEM_BANKS) : 0,
};
/******************************************************************************
* Type definitions
******************************************************************************/
/// Shared memory storage layout type
struct _TempStorage
{
T buff[WARP_ITEMS + PADDING_ITEMS];
};
public:
/// \smemstorage{WarpExchange}
struct TempStorage : Uninitialized<_TempStorage> {};
private:
/******************************************************************************
* Thread fields
******************************************************************************/
_TempStorage &temp_storage;
int lane_id;
public:
/******************************************************************************
* Construction
******************************************************************************/
/// Constructor
__device__ __forceinline__ WarpExchange(
TempStorage &temp_storage)
:
temp_storage(temp_storage.Alias()),
lane_id(IS_ARCH_WARP ?
LaneId() :
LaneId() % LOGICAL_WARP_THREADS)
{}
/******************************************************************************
* Interface
******************************************************************************/
/**
* \brief Exchanges valid data items annotated by rank into <em>striped</em> arrangement.
*
* \par
* - \smemreuse
*
* \tparam OffsetT <b>[inferred]</b> Signed integer type for local offsets
*/
template <typename OffsetT>
__device__ __forceinline__ void ScatterToStriped(
T items[ITEMS_PER_THREAD], ///< [in-out] Items to exchange
OffsetT ranks[ITEMS_PER_THREAD]) ///< [in] Corresponding scatter ranks
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
if (INSERT_PADDING) ranks[ITEM] = SHR_ADD(ranks[ITEM], LOG_SMEM_BANKS, ranks[ITEM]);
temp_storage.buff[ranks[ITEM]] = items[ITEM];
}
WARP_SYNC(0xffffffff);
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
{
int item_offset = (ITEM * LOGICAL_WARP_THREADS) + lane_id;
if (INSERT_PADDING) item_offset = SHR_ADD(item_offset, LOG_SMEM_BANKS, item_offset);
items[ITEM] = temp_storage.buff[item_offset];
}
}
};
#endif // DOXYGEN_SHOULD_SKIP_THIS
} // CUB namespace
CUB_NS_POSTFIX // Optional outer namespace(s)
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