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/*
*
* Copyright 2015 gRPC authors.
*
* 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.
*
*/
#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 *= 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;
}
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