util_temporary_storage.cuh

File members: /home/runner/work/cccl/cccl/cub/cub/util_temporary_storage.cuh
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 * Copyright (c) 2011, Duane Merrill.  All rights reserved.
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#pragma once

#include <cub/config.cuh>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cub/util_debug.cuh>
#include <cub/util_namespace.cuh>

CUB_NAMESPACE_BEGIN

#ifndef DOXYGEN_SHOULD_SKIP_THIS // Do not document

template <int ALLOCATIONS>
_CCCL_HOST_DEVICE _CCCL_FORCEINLINE cudaError_t AliasTemporaries(
  void* d_temp_storage,
  size_t& temp_storage_bytes,
  void* (&allocations)[ALLOCATIONS],
  const size_t (&allocation_sizes)[ALLOCATIONS])
{
  constexpr size_t ALIGN_BYTES = 256;
  constexpr size_t ALIGN_MASK  = ~(ALIGN_BYTES - 1);

  // Compute exclusive prefix sum over allocation requests
  size_t allocation_offsets[ALLOCATIONS];
  size_t bytes_needed = 0;
  for (int i = 0; i < ALLOCATIONS; ++i)
  {
    const size_t allocation_bytes = (allocation_sizes[i] + ALIGN_BYTES - 1) & ALIGN_MASK;
    allocation_offsets[i]         = bytes_needed;
    bytes_needed += allocation_bytes;
  }
  bytes_needed += ALIGN_BYTES - 1;

  // Check if the caller is simply requesting the size of the storage allocation
  if (!d_temp_storage)
  {
    temp_storage_bytes = bytes_needed;
    return cudaSuccess;
  }

  // Check if enough storage provided
  if (temp_storage_bytes < bytes_needed)
  {
    return CubDebug(cudaErrorInvalidValue);
  }

  // Alias
  d_temp_storage =
    reinterpret_cast<void*>((reinterpret_cast<uintptr_t>(d_temp_storage) + ALIGN_BYTES - 1) & ALIGN_MASK);
  for (int i = 0; i < ALLOCATIONS; ++i)
  {
    allocations[i] = static_cast<char*>(d_temp_storage) + allocation_offsets[i];
  }

  return cudaSuccess;
}

#endif // DOXYGEN_SHOULD_SKIP_THIS

CUB_NAMESPACE_END