text: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.
   */
  
  //-----------------------------------------------------------------------------
  // The original MurmurHash3 was written by Austin Appleby, and is placed in the
  // public domain. This source code, implemented by Licht Takeuchi, is based on
  // the orignal MurmurHash3 source code.
  #include "Murmur3_32Hash.h"
  
  #include <boost/predef.h>
  #include <limits>
  
  #if BOOST_COMP_MSVC
  #include <stdlib.h>
  #define ROTATE_LEFT(x, y) _rotl(x, y)
  #else
  #define ROTATE_LEFT(x, y) rotate_left(x, y)
  #endif
  
  #if BOOST_ENDIAN_LITTLE_BYTE
  #define BYTESPWAP(x) (x)
  #elif BOOST_ENDIAN_BIG_BYTE
  #if BOOST_COMP_CLANG || BOOST_COMP_GNUC
  #define BYTESPWAP(x) __builtin_bswap32(x)
  #elif BOOST_COMP_MSVC
  #define BYTESPWAP(x) _byteswap_uint32(x)
  #else
  #endif
  #else
  #endif
  
  #define MACRO_CHUNK_SIZE 4
  #define MACRO_C1 0xcc9e2d51U
  #define MACRO_C2 0x1b873593U
  
  namespace pulsar {
  
  Murmur3_32Hash::Murmur3_32Hash() : seed(0) {}
  
  int32_t Murmur3_32Hash::makeHash(const std::string &key) {
      return static_cast<int32_t>(makeHash(&key.front(), key.length()) & std::numeric_limits<int32_t>::max());
  }
  
  uint32_t Murmur3_32Hash::makeHash(const void *key, const int64_t len) {
      const uint8_t *data = reinterpret_cast<const uint8_t *>(key);
      const int nblocks = len / MACRO_CHUNK_SIZE;
      uint32_t h1 = seed;
      const uint32_t *blocks = reinterpret_cast<const uint32_t *>(data + nblocks * MACRO_CHUNK_SIZE);
  
      for (int i = -nblocks; i != 0; i++) {
          uint32_t k1 = BYTESPWAP(blocks[i]);
  
          k1 = mixK1(k1);
          h1 = mixH1(h1, k1);
      }
  
      const uint8_t *tail = reinterpret_cast<const uint8_t *>(data + nblocks * MACRO_CHUNK_SIZE);
      uint32_t k1 = 0;
      switch (len - nblocks * MACRO_CHUNK_SIZE) {
          case 3:
              k1 ^= static_cast<uint32_t>(tail[2]) << 16;
          case 2:
              k1 ^= static_cast<uint32_t>(tail[1]) << 8;
          case 1:
              k1 ^= static_cast<uint32_t>(tail[0]);
      };
  
      h1 ^= mixK1(k1);
      h1 ^= len;
      h1 = fmix(h1);
  
      return h1;
  }
  
  uint32_t Murmur3_32Hash::fmix(uint32_t h) {
      h ^= h >> 16;
      h *= 0x85ebca6b;
      h ^= h >> 13;
      h *= 0xc2b2ae35;
      h ^= h >> 16;
  
      return h;
  }
  
  uint32_t Murmur3_32Hash::mixK1(uint32_t k1) {
      k1 *= MACRO_C1;
      k1 = ROTATE_LEFT(k1, 15);
      k1 *= MACRO_C2;
      return k1;
  }
  
  uint32_t Murmur3_32Hash::mixH1(uint32_t h1, uint32_t k1) {
      h1 ^= k1;
      h1 = ROTATE_LEFT(h1, 13);
      return h1 * 5 + 0xe6546b64;
  }
  
  uint32_t Murmur3_32Hash::rotate_left(uint32_t x, uint8_t r) { return (x << r) | (x >> ((32 - r))); }
  }  // namespace pulsar
  