text: // ----------------------------------------------------------------------------
  // -                        Open3D: www.open3d.org                            -
  // ----------------------------------------------------------------------------
  // The MIT License (MIT)
  //
  // Copyright (c) 2018-2021 www.open3d.org
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  // IN THE SOFTWARE.
  // ----------------------------------------------------------------------------
  
  // Copyright 2019 Saman Ashkiani
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  // http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
  // implied. See the License for the specific language governing permissions
  // and limitations under the License.
  
  #pragma once
  #include <cstdint>
  
  #include "open3d/core/CUDAUtils.h"
  
  namespace open3d {
  namespace core {
  
  // Device-specific, safe for current NVIDIA architectures.
  static constexpr uint32_t kWarpSize = 32;
  
  //////////////////////
  // Tunable variables
  //////////////////////
  // Hashmap
  static constexpr uint32_t kSuperBlocks = 32;
  static constexpr uint32_t kBlocksPerSuperBlock = 4;
  static constexpr uint32_t kBlocksPerSuperBlockInBits = 2;
  static constexpr uint32_t kSlabsPerBlock = 1024;
  
  // Misc
  static constexpr uint32_t kMaxKeyByteSize = 32;
  static constexpr uint32_t kThreadsPerBlock = 128;
  
  //////////////////////
  // Combination of tunable variables
  //////////////////////
  static constexpr uint32_t kUIntsPerBlock = kSlabsPerBlock * kWarpSize;
  // We need one bitmap (32-bit) per slab (32 nodes). Number of bitmaps is equal
  // to number of slabs.
  static constexpr uint32_t kBitmapsPerSuperBlock =
          kBlocksPerSuperBlock * kSlabsPerBlock;
  static constexpr uint32_t kUIntsPerSuperBlock =
          kBlocksPerSuperBlock * kUIntsPerBlock + kBitmapsPerSuperBlock;
  
  //////////////////////
  // Non-tunable variables
  //////////////////////
  // Mask offsets
  static constexpr uint32_t kSuperBlockMaskBits = 27;
  static constexpr uint32_t kBlockMaskBits = 10;
  static constexpr uint32_t kSlabMaskBits = 5;
  
  // Masks & flags
  static constexpr uint32_t kSyncLanesMask = 0xFFFFFFFF;
  static constexpr uint32_t kNodePtrLanesMask = 0x7FFFFFFF;
  static constexpr uint32_t kNextSlabPtrLaneId = 31;
  
  static constexpr uint32_t kHeadSlabAddr = 0xFFFFFFFE;
  
  static constexpr uint32_t kEmptySlabAddr = 0xFFFFFFFF;
  static constexpr uint32_t kEmptyNodeAddr = 0xFFFFFFFF;
  static constexpr uint32_t kNullAddr = 0xFFFFFFFF;
  
  static constexpr uint32_t kNotFoundFlag = 0xFFFFFFFF;
  
  #define MEMCPY_AS_INTS(dst, src, num_bytes)              \
      auto dst_in_int = reinterpret_cast<int*>(dst);       \
      auto src_in_int = reinterpret_cast<const int*>(src); \
      int count_in_int = num_bytes / sizeof(int);          \
      for (int i = 0; i < count_in_int; ++i) {             \
          dst_in_int[i] = src_in_int[i];                   \
      }
  
  }  // namespace core
  }  // namespace open3d
  