text: /*
   *
   * Copyright 2015, Google Inc.
   * 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 Google Inc. 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 THE COPYRIGHT
   * OWNER OR CONTRIBUTORS 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.
   *
   */
  
  #include "src/core/lib/support/murmur_hash.h"
  
  #include <string.h>
  
  #define ROTL32(x, r) ((x) << (r)) | ((x) >> (32 - (r)))
  
  #define FMIX32(h)    \
    (h) ^= (h) >> 16;  \
    (h) *= 0x85ebca6b; \
    (h) ^= (h) >> 13;  \
    (h) *= 0xc2b2ae35; \
    (h) ^= (h) >> 16;
  
  uint32_t gpr_murmur_hash3(const void *key, size_t len, uint32_t seed) {
    const uint8_t *data = (const uint8_t *)key;
    const size_t nblocks = len / 4;
    int i;
  
    uint32_t h1 = seed;
    uint32_t k1;
  
    const uint32_t c1 = 0xcc9e2d51;
    const uint32_t c2 = 0x1b873593;
  
    const uint32_t *blocks = ((const uint32_t *)key) + nblocks;
    const uint8_t *tail = (const uint8_t *)(data + nblocks * 4);
  
    /* body */
    for (i = -(int)nblocks; i; i++) {
      memcpy(&k1, blocks + i, sizeof(uint32_t));
      k1 = GRPC_LE_WORD(k1);
      k1 *= c1;
      k1 = ROTL32(k1, 15);
      k1 *= c2;
  
      h1 ^= k1;
      h1 = ROTL32(h1, 13);
      h1 = h1 * 5 + 0xe6546b64;
    }
  
    k1 = 0;
  
    /* tail */
    switch (len & 3) {
      case 3:
        k1 ^= ((uint32_t)tail[2]) << 16;
      case 2:
        k1 ^= ((uint32_t)tail[1]) << 8;
      case 1:
        k1 ^= tail[0];
        k1 *= c1;
        k1 = ROTL32(k1, 15);
        k1 *= c2;
        h1 ^= k1;
    };
  
    /* finalization */
    h1 ^= (uint32_t)len;
    FMIX32(h1);
    return h1;
  }
  