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tools/cub-1.8.0/cub/thread/thread_scan.cuh 10.3 KB
8dcb6dfcb   Yannick Estève   first commit
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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
   * Thread utilities for sequential prefix scan over statically-sized array types
   */
  
  #pragma once
  
  #include "../thread/thread_operators.cuh"
  #include "../util_namespace.cuh"
  
  /// Optional outer namespace(s)
  CUB_NS_PREFIX
  
  /// CUB namespace
  namespace cub {
  
  /// Internal namespace (to prevent ADL mishaps between static functions when mixing different CUB installations)
  namespace internal {
  
  
  /**
   * \addtogroup UtilModule
   * @{
   */
  
  /**
   * 
  ame Sequential prefix scan over statically-sized array types
   * @{
   */
  
  template <
      int         LENGTH,
      typename    T,
      typename    ScanOp>
  __device__ __forceinline__ T ThreadScanExclusive(
      T                   inclusive,
      T                   exclusive,
      T                   *input,                 ///< [in] Input array
      T                   *output,                ///< [out] Output array (may be aliased to \p input)
      ScanOp              scan_op,                ///< [in] Binary scan operator
      Int2Type<LENGTH>    /*length*/)
  {
      #pragma unroll
      for (int i = 0; i < LENGTH; ++i)
      {
          inclusive = scan_op(exclusive, input[i]);
          output[i] = exclusive;
          exclusive = inclusive;
      }
  
      return inclusive;
  }
  
  
  
  /**
   * \brief Perform a sequential exclusive prefix scan over \p LENGTH elements of the \p input array, seeded with the specified \p prefix.  The aggregate is returned.
   *
   * \tparam LENGTH     LengthT of \p input and \p output arrays
   * \tparam T          <b>[inferred]</b> The data type to be scanned.
   * \tparam ScanOp     <b>[inferred]</b> Binary scan operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ScanOp>
  __device__ __forceinline__ T ThreadScanExclusive(
      T           *input,                 ///< [in] Input array
      T           *output,                ///< [out] Output array (may be aliased to \p input)
      ScanOp      scan_op,                ///< [in] Binary scan operator
      T           prefix,                 ///< [in] Prefix to seed scan with
      bool        apply_prefix = true)    ///< [in] Whether or not the calling thread should apply its prefix.  If not, the first output element is undefined.  (Handy for preventing thread-0 from applying a prefix.)
  {
      T inclusive = input[0];
      if (apply_prefix)
      {
          inclusive = scan_op(prefix, inclusive);
      }
      output[0] = prefix;
      T exclusive = inclusive;
  
      return ThreadScanExclusive(inclusive, exclusive, input + 1, output + 1, scan_op, Int2Type<LENGTH - 1>());
  }
  
  
  /**
   * \brief Perform a sequential exclusive prefix scan over the statically-sized \p input array, seeded with the specified \p prefix.  The aggregate is returned.
   *
   * \tparam LENGTH     <b>[inferred]</b> LengthT of \p input and \p output arrays
   * \tparam T          <b>[inferred]</b> The data type to be scanned.
   * \tparam ScanOp     <b>[inferred]</b> Binary scan operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ScanOp>
  __device__ __forceinline__ T ThreadScanExclusive(
      T           (&input)[LENGTH],       ///< [in] Input array
      T           (&output)[LENGTH],      ///< [out] Output array (may be aliased to \p input)
      ScanOp      scan_op,                ///< [in] Binary scan operator
      T           prefix,                 ///< [in] Prefix to seed scan with
      bool        apply_prefix = true)    ///< [in] Whether or not the calling thread should apply its prefix.  (Handy for preventing thread-0 from applying a prefix.)
  {
      return ThreadScanExclusive<LENGTH>((T*) input, (T*) output, scan_op, prefix, apply_prefix);
  }
  
  
  
  
  
  
  
  
  
  template <
      int         LENGTH,
      typename    T,
      typename    ScanOp>
  __device__ __forceinline__ T ThreadScanInclusive(
      T                   inclusive,
      T                   *input,                 ///< [in] Input array
      T                   *output,                ///< [out] Output array (may be aliased to \p input)
      ScanOp              scan_op,                ///< [in] Binary scan operator
      Int2Type<LENGTH>    /*length*/)
  {
      #pragma unroll
      for (int i = 0; i < LENGTH; ++i)
      {
          inclusive = scan_op(inclusive, input[i]);
          output[i] = inclusive;
      }
  
      return inclusive;
  }
  
  
  /**
   * \brief Perform a sequential inclusive prefix scan over \p LENGTH elements of the \p input array.  The aggregate is returned.
   *
   * \tparam LENGTH     LengthT of \p input and \p output arrays
   * \tparam T          <b>[inferred]</b> The data type to be scanned.
   * \tparam ScanOp     <b>[inferred]</b> Binary scan operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ScanOp>
  __device__ __forceinline__ T ThreadScanInclusive(
      T           *input,                 ///< [in] Input array
      T           *output,                ///< [out] Output array (may be aliased to \p input)
      ScanOp      scan_op)                ///< [in] Binary scan operator
  {
      T inclusive = input[0];
      output[0] = inclusive;
  
      // Continue scan
      return ThreadScanInclusive(inclusive, input + 1, output + 1, scan_op, Int2Type<LENGTH - 1>());
  }
  
  
  /**
   * \brief Perform a sequential inclusive prefix scan over the statically-sized \p input array.  The aggregate is returned.
   *
   * \tparam LENGTH     <b>[inferred]</b> LengthT of \p input and \p output arrays
   * \tparam T          <b>[inferred]</b> The data type to be scanned.
   * \tparam ScanOp     <b>[inferred]</b> Binary scan operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ScanOp>
  __device__ __forceinline__ T ThreadScanInclusive(
      T           (&input)[LENGTH],       ///< [in] Input array
      T           (&output)[LENGTH],      ///< [out] Output array (may be aliased to \p input)
      ScanOp      scan_op)                ///< [in] Binary scan operator
  {
      return ThreadScanInclusive<LENGTH>((T*) input, (T*) output, scan_op);
  }
  
  
  /**
   * \brief Perform a sequential inclusive prefix scan over \p LENGTH elements of the \p input array, seeded with the specified \p prefix.  The aggregate is returned.
   *
   * \tparam LENGTH     LengthT of \p input and \p output arrays
   * \tparam T          <b>[inferred]</b> The data type to be scanned.
   * \tparam ScanOp     <b>[inferred]</b> Binary scan operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ScanOp>
  __device__ __forceinline__ T ThreadScanInclusive(
      T           *input,                 ///< [in] Input array
      T           *output,                ///< [out] Output array (may be aliased to \p input)
      ScanOp      scan_op,                ///< [in] Binary scan operator
      T           prefix,                 ///< [in] Prefix to seed scan with
      bool        apply_prefix = true)    ///< [in] Whether or not the calling thread should apply its prefix.  (Handy for preventing thread-0 from applying a prefix.)
  {
      T inclusive = input[0];
      if (apply_prefix)
      {
          inclusive = scan_op(prefix, inclusive);
      }
      output[0] = inclusive;
  
      // Continue scan
      return ThreadScanInclusive(inclusive, input + 1, output + 1, scan_op, Int2Type<LENGTH - 1>());
  }
  
  
  /**
   * \brief Perform a sequential inclusive prefix scan over the statically-sized \p input array, seeded with the specified \p prefix.  The aggregate is returned.
   *
   * \tparam LENGTH     <b>[inferred]</b> LengthT of \p input and \p output arrays
   * \tparam T          <b>[inferred]</b> The data type to be scanned.
   * \tparam ScanOp     <b>[inferred]</b> Binary scan operator type having member <tt>T operator()(const T &a, const T &b)</tt>
   */
  template <
      int         LENGTH,
      typename    T,
      typename    ScanOp>
  __device__ __forceinline__ T ThreadScanInclusive(
      T           (&input)[LENGTH],       ///< [in] Input array
      T           (&output)[LENGTH],      ///< [out] Output array (may be aliased to \p input)
      ScanOp      scan_op,                ///< [in] Binary scan operator
      T           prefix,                 ///< [in] Prefix to seed scan with
      bool        apply_prefix = true)    ///< [in] Whether or not the calling thread should apply its prefix.  (Handy for preventing thread-0 from applying a prefix.)
  {
      return ThreadScanInclusive<LENGTH>((T*) input, (T*) output, scan_op, prefix, apply_prefix);
  }
  
  
  //@}  end member group
  
  /** @} */       // end group UtilModule
  
  
  }               // internal namespace
  }               // CUB namespace
  CUB_NS_POSTFIX  // Optional outer namespace(s)