block_radix_sort.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.
 *
 ******************************************************************************/

#pragma once

#include "block_exchange.cuh"
#include "block_radix_rank.cuh"
#include "../util_ptx.cuh"
#include "../util_arch.cuh"
#include "../util_type.cuh"
#include "../util_namespace.cuh"

CUB_NS_PREFIX

namespace cub {

template <
    typename                KeyT,
    int                     BLOCK_DIM_X,
    int                     ITEMS_PER_THREAD,
    typename                ValueT                   = NullType,
    int                     RADIX_BITS              = 4,
    bool                    MEMOIZE_OUTER_SCAN      = (CUB_PTX_ARCH >= 350) ? true : false,
    BlockScanAlgorithm      INNER_SCAN_ALGORITHM    = BLOCK_SCAN_WARP_SCANS,
    cudaSharedMemConfig     SMEM_CONFIG             = cudaSharedMemBankSizeFourByte,
    int                     BLOCK_DIM_Y             = 1,
    int                     BLOCK_DIM_Z             = 1,
    int                     PTX_ARCH                = CUB_PTX_ARCH>
class BlockRadixSort
{
private:

    /******************************************************************************
     * Constants and type definitions
     ******************************************************************************/

    enum
    {
        // The thread block size in threads
        BLOCK_THREADS               = BLOCK_DIM_X * BLOCK_DIM_Y * BLOCK_DIM_Z,

        // Whether or not there are values to be trucked along with keys
        KEYS_ONLY                   = Equals<ValueT, NullType>::VALUE,
    };

    // KeyT traits and unsigned bits type
    typedef Traits<KeyT>                        KeyTraits;
    typedef typename KeyTraits::UnsignedBits    UnsignedBits;

    typedef BlockRadixRank<
            BLOCK_DIM_X,
            RADIX_BITS,
            false,
            MEMOIZE_OUTER_SCAN,
            INNER_SCAN_ALGORITHM,
            SMEM_CONFIG,
            BLOCK_DIM_Y,
            BLOCK_DIM_Z,
            PTX_ARCH>
        AscendingBlockRadixRank;

    typedef BlockRadixRank<
            BLOCK_DIM_X,
            RADIX_BITS,
            true,
            MEMOIZE_OUTER_SCAN,
            INNER_SCAN_ALGORITHM,
            SMEM_CONFIG,
            BLOCK_DIM_Y,
            BLOCK_DIM_Z,
            PTX_ARCH>
        DescendingBlockRadixRank;

    typedef BlockExchange<KeyT, BLOCK_DIM_X, ITEMS_PER_THREAD, false, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH> BlockExchangeKeys;

    typedef BlockExchange<ValueT, BLOCK_DIM_X, ITEMS_PER_THREAD, false, BLOCK_DIM_Y, BLOCK_DIM_Z, PTX_ARCH> BlockExchangeValues;

    union _TempStorage
    {
        typename AscendingBlockRadixRank::TempStorage  asending_ranking_storage;
        typename DescendingBlockRadixRank::TempStorage descending_ranking_storage;
        typename BlockExchangeKeys::TempStorage        exchange_keys;
        typename BlockExchangeValues::TempStorage      exchange_values;
    };


    /******************************************************************************
     * Thread fields
     ******************************************************************************/

    _TempStorage &temp_storage;

    unsigned int linear_tid;

    /******************************************************************************
     * Utility methods
     ******************************************************************************/

    __device__ __forceinline__ _TempStorage& PrivateStorage()
    {
        __shared__ _TempStorage private_storage;
        return private_storage;
    }

    __device__ __forceinline__ void RankKeys(
        UnsignedBits    (&unsigned_keys)[ITEMS_PER_THREAD],
        int             (&ranks)[ITEMS_PER_THREAD],
        int             begin_bit,
        int             pass_bits,
        Int2Type<false> /*is_descending*/)
    {
        AscendingBlockRadixRank(temp_storage.asending_ranking_storage).RankKeys(
            unsigned_keys,
            ranks,
            begin_bit,
            pass_bits);
    }

    __device__ __forceinline__ void RankKeys(
        UnsignedBits    (&unsigned_keys)[ITEMS_PER_THREAD],
        int             (&ranks)[ITEMS_PER_THREAD],
        int             begin_bit,
        int             pass_bits,
        Int2Type<true>  /*is_descending*/)
    {
        DescendingBlockRadixRank(temp_storage.descending_ranking_storage).RankKeys(
            unsigned_keys,
            ranks,
            begin_bit,
            pass_bits);
    }

    __device__ __forceinline__ void ExchangeValues(
        ValueT          (&values)[ITEMS_PER_THREAD],
        int             (&ranks)[ITEMS_PER_THREAD],
        Int2Type<false> /*is_keys_only*/,
        Int2Type<true>  /*is_blocked*/)
    {
        CTA_SYNC();

        // Exchange values through shared memory in blocked arrangement
        BlockExchangeValues(temp_storage.exchange_values).ScatterToBlocked(values, ranks);
    }

    __device__ __forceinline__ void ExchangeValues(
        ValueT          (&values)[ITEMS_PER_THREAD],
        int             (&ranks)[ITEMS_PER_THREAD],
        Int2Type<false> /*is_keys_only*/,
        Int2Type<false> /*is_blocked*/)
    {
        CTA_SYNC();

        // Exchange values through shared memory in blocked arrangement
        BlockExchangeValues(temp_storage.exchange_values).ScatterToStriped(values, ranks);
    }

    template <int IS_BLOCKED>
    __device__ __forceinline__ void ExchangeValues(
        ValueT                  (&/*values*/)[ITEMS_PER_THREAD],
        int                     (&/*ranks*/)[ITEMS_PER_THREAD],
        Int2Type<true>          /*is_keys_only*/,
        Int2Type<IS_BLOCKED>    /*is_blocked*/)
    {}

    template <int DESCENDING, int KEYS_ONLY>
    __device__ __forceinline__ void SortBlocked(
        KeyT                    (&keys)[ITEMS_PER_THREAD],          
        ValueT                  (&values)[ITEMS_PER_THREAD],        
        int                     begin_bit,                          
        int                     end_bit,                            
        Int2Type<DESCENDING>    is_descending,                      
        Int2Type<KEYS_ONLY>     is_keys_only)                       
    {
        UnsignedBits (&unsigned_keys)[ITEMS_PER_THREAD] =
            reinterpret_cast<UnsignedBits (&)[ITEMS_PER_THREAD]>(keys);

        // Twiddle bits if necessary
        #pragma unroll
        for (int KEY = 0; KEY < ITEMS_PER_THREAD; KEY++)
        {
            unsigned_keys[KEY] = KeyTraits::TwiddleIn(unsigned_keys[KEY]);
        }

        // Radix sorting passes
        while (true)
        {
            int pass_bits = CUB_MIN(RADIX_BITS, end_bit - begin_bit);

            // Rank the blocked keys
            int ranks[ITEMS_PER_THREAD];
            RankKeys(unsigned_keys, ranks, begin_bit, pass_bits, is_descending);
            begin_bit += RADIX_BITS;

            CTA_SYNC();

            // Exchange keys through shared memory in blocked arrangement
            BlockExchangeKeys(temp_storage.exchange_keys).ScatterToBlocked(keys, ranks);

            // Exchange values through shared memory in blocked arrangement
            ExchangeValues(values, ranks, is_keys_only, Int2Type<true>());

            // Quit if done
            if (begin_bit >= end_bit) break;

            CTA_SYNC();
        }

        // Untwiddle bits if necessary
        #pragma unroll
        for (int KEY = 0; KEY < ITEMS_PER_THREAD; KEY++)
        {
            unsigned_keys[KEY] = KeyTraits::TwiddleOut(unsigned_keys[KEY]);
        }
    }

public:

#ifndef DOXYGEN_SHOULD_SKIP_THIS    // Do not document

    template <int DESCENDING, int KEYS_ONLY>
    __device__ __forceinline__ void SortBlockedToStriped(
        KeyT                    (&keys)[ITEMS_PER_THREAD],          
        ValueT                  (&values)[ITEMS_PER_THREAD],        
        int                     begin_bit,                          
        int                     end_bit,                            
        Int2Type<DESCENDING>    is_descending,                      
        Int2Type<KEYS_ONLY>     is_keys_only)                       
    {
        UnsignedBits (&unsigned_keys)[ITEMS_PER_THREAD] =
            reinterpret_cast<UnsignedBits (&)[ITEMS_PER_THREAD]>(keys);

        // Twiddle bits if necessary
        #pragma unroll
        for (int KEY = 0; KEY < ITEMS_PER_THREAD; KEY++)
        {
            unsigned_keys[KEY] = KeyTraits::TwiddleIn(unsigned_keys[KEY]);
        }

        // Radix sorting passes
        while (true)
        {
            int pass_bits = CUB_MIN(RADIX_BITS, end_bit - begin_bit);

            // Rank the blocked keys
            int ranks[ITEMS_PER_THREAD];
            RankKeys(unsigned_keys, ranks, begin_bit, pass_bits, is_descending);
            begin_bit += RADIX_BITS;

            CTA_SYNC();

            // Check if this is the last pass
            if (begin_bit >= end_bit)
            {
                // Last pass exchanges keys through shared memory in striped arrangement
                BlockExchangeKeys(temp_storage.exchange_keys).ScatterToStriped(keys, ranks);

                // Last pass exchanges through shared memory in striped arrangement
                ExchangeValues(values, ranks, is_keys_only, Int2Type<false>());

                // Quit
                break;
            }

            // Exchange keys through shared memory in blocked arrangement
            BlockExchangeKeys(temp_storage.exchange_keys).ScatterToBlocked(keys, ranks);

            // Exchange values through shared memory in blocked arrangement
            ExchangeValues(values, ranks, is_keys_only, Int2Type<true>());

            CTA_SYNC();
        }

        // Untwiddle bits if necessary
        #pragma unroll
        for (int KEY = 0; KEY < ITEMS_PER_THREAD; KEY++)
        {
            unsigned_keys[KEY] = KeyTraits::TwiddleOut(unsigned_keys[KEY]);
        }
    }

#endif // DOXYGEN_SHOULD_SKIP_THIS

    struct TempStorage : Uninitialized<_TempStorage> {};


    /******************************************************************/

    __device__ __forceinline__ BlockRadixSort()
    :
        temp_storage(PrivateStorage()),
        linear_tid(RowMajorTid(BLOCK_DIM_X, BLOCK_DIM_Y, BLOCK_DIM_Z))
    {}


    __device__ __forceinline__ BlockRadixSort(
        TempStorage &temp_storage)             
    :
        temp_storage(temp_storage.Alias()),
        linear_tid(RowMajorTid(BLOCK_DIM_X, BLOCK_DIM_Y, BLOCK_DIM_Z))
    {}


    /******************************************************************/

    __device__ __forceinline__ void Sort(
        KeyT    (&keys)[ITEMS_PER_THREAD],          
        int     begin_bit   = 0,                    
        int     end_bit     = sizeof(KeyT) * 8)      
    {
        NullType values[ITEMS_PER_THREAD];

        SortBlocked(keys, values, begin_bit, end_bit, Int2Type<false>(), Int2Type<KEYS_ONLY>());
    }


    __device__ __forceinline__ void Sort(
        KeyT    (&keys)[ITEMS_PER_THREAD],          
        ValueT  (&values)[ITEMS_PER_THREAD],        
        int     begin_bit   = 0,                    
        int     end_bit     = sizeof(KeyT) * 8)      
    {
        SortBlocked(keys, values, begin_bit, end_bit, Int2Type<false>(), Int2Type<KEYS_ONLY>());
    }

    __device__ __forceinline__ void SortDescending(
        KeyT    (&keys)[ITEMS_PER_THREAD],          
        int     begin_bit   = 0,                    
        int     end_bit     = sizeof(KeyT) * 8)      
    {
        NullType values[ITEMS_PER_THREAD];

        SortBlocked(keys, values, begin_bit, end_bit, Int2Type<true>(), Int2Type<KEYS_ONLY>());
    }


    __device__ __forceinline__ void SortDescending(
        KeyT    (&keys)[ITEMS_PER_THREAD],          
        ValueT  (&values)[ITEMS_PER_THREAD],        
        int     begin_bit   = 0,                    
        int     end_bit     = sizeof(KeyT) * 8)      
    {
        SortBlocked(keys, values, begin_bit, end_bit, Int2Type<true>(), Int2Type<KEYS_ONLY>());
    }


    /******************************************************************/


    __device__ __forceinline__ void SortBlockedToStriped(
        KeyT    (&keys)[ITEMS_PER_THREAD],          
        int     begin_bit   = 0,                    
        int     end_bit     = sizeof(KeyT) * 8)      
    {
        NullType values[ITEMS_PER_THREAD];

        SortBlockedToStriped(keys, values, begin_bit, end_bit, Int2Type<false>(), Int2Type<KEYS_ONLY>());
    }


    __device__ __forceinline__ void SortBlockedToStriped(
        KeyT    (&keys)[ITEMS_PER_THREAD],          
        ValueT  (&values)[ITEMS_PER_THREAD],        
        int     begin_bit   = 0,                    
        int     end_bit     = sizeof(KeyT) * 8)      
    {
        SortBlockedToStriped(keys, values, begin_bit, end_bit, Int2Type<false>(), Int2Type<KEYS_ONLY>());
    }


    __device__ __forceinline__ void SortDescendingBlockedToStriped(
        KeyT    (&keys)[ITEMS_PER_THREAD],          
        int     begin_bit   = 0,                    
        int     end_bit     = sizeof(KeyT) * 8)      
    {
        NullType values[ITEMS_PER_THREAD];

        SortBlockedToStriped(keys, values, begin_bit, end_bit, Int2Type<true>(), Int2Type<KEYS_ONLY>());
    }


    __device__ __forceinline__ void SortDescendingBlockedToStriped(
        KeyT    (&keys)[ITEMS_PER_THREAD],          
        ValueT  (&values)[ITEMS_PER_THREAD],        
        int     begin_bit   = 0,                    
        int     end_bit     = sizeof(KeyT) * 8)      
    {
        SortBlockedToStriped(keys, values, begin_bit, end_bit, Int2Type<true>(), Int2Type<KEYS_ONLY>());
    }



};

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