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/*
*
* 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/support/murmur_hash.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;
/* Block read - if your platform needs to do endian-swapping or can only
handle aligned reads, do the conversion here */
#define GETBLOCK32(p, i) (p)[(i)]
gpr_uint32 gpr_murmur_hash3(const void *key, size_t len, gpr_uint32 seed) {
const gpr_uint8 *data = (const gpr_uint8 *)key;
const size_t nblocks = len / 4;
int i;
gpr_uint32 h1 = seed;
gpr_uint32 k1;
const gpr_uint32 c1 = 0xcc9e2d51;
const gpr_uint32 c2 = 0x1b873593;
const gpr_uint32 *blocks = ((const gpr_uint32 *)key) + nblocks;
const gpr_uint8 *tail = (const gpr_uint8 *)(data + nblocks * 4);
/* body */
for (i = -(int)nblocks; i; i++) {
k1 = GETBLOCK32(blocks, i);
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 ^= ((gpr_uint32)tail[2]) << 16;
case 2:
k1 ^= ((gpr_uint32)tail[1]) << 8;
case 1:
k1 ^= tail[0];
k1 *= c1;
k1 = ROTL32(k1, 15);
k1 *= c2;
h1 ^= k1;
};
/* finalization */
h1 ^= (gpr_uint32)len;
FMIX32(h1);
return h1;
}
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